JP2013174749A - Optical element structure body - Google Patents

Abstract

Provided is an optical element structure capable of easily inspecting that respective alignment films for emitting right-eye image light and left-eye image light of an optical element plate are homogeneously configured.
An optical element plate used in a stereoscopic image display device, an adhesive for bonding the optical element plate and the display device, and a structure in which a release layer surface of a release film is bonded to the adhesive. Yes, the release film has an orientation of the orientation main axis of 12 degrees or less, an ISC-S value in crossed Nicols of 75 or less, and an image clarity value of 90% or more. An optical element structure comprising a release layer on at least one surface of a biaxially oriented polyester film containing 2.0 μm particles.
[Selection figure] None

Description

  The present invention relates to an optical element plate used in a stereoscopic image display device, an adhesive for bonding the optical element plate and the display device, and a structure made of a release film for protecting the adhesive, It is an object of the present invention to provide an optical element structure capable of easily inspecting that the respective alignment films for emitting the right-eye image light and the left-eye image light on the optical element plate are homogeneously configured.

  A flat panel display (hereinafter abbreviated as FPD) has a large screen such as a television as well as a portable device such as a laptop computer and a mobile phone because it is easy to increase in size, is lightweight, and can be thinned. It is also recognized as a major component in home appliances. Recently, FPDs that can realize stereoscopic video (hereinafter abbreviated as 3D video) for the purpose of new video expression have also appeared, and have influenced the display market and the consumer electronics market as new products.

There are several methods for realizing this 3D image, and one of them is bonded to an FPD with an optical element plate having respective alignment films for emitting right-eye image light and left-eye image light, There is a method achieved by viewing an image from the FPD with dedicated glasses. Adhesives are often used for bonding optical element plates, and in order to handle an optical element plate after the adhesive has been installed, it is necessary that the release film be bonded to protect the adhesive. is there.
Conventionally, as described in Patent Document 1, a specially defined film has not been used for this release film. Of course, a film in which a release layer is provided on a PET film may be used, and other films may be used. However, PET film has features such as thickness uniformity, stable mechanical and thermal properties, and fewer optical defects such as fish eyes than other materials. Release film using PET film Have been used favorably as a substrate for protecting adhesives.

  In recent years, as the FPD area shifts from a portable device size to a large size such as a television, an optical element plate for expressing a 3D image has to be enlarged. Conventionally, the release film did not affect the inspection that the alignment film that emits the image light for the right eye and the image light for the left eye is homogeneously configured, but because it became large, With a release film using a normal PET film, inspection has become difficult due to its optical characteristics. Furthermore, the pixel size of the FPD image is becoming smaller, and the size of the alignment film is also reduced accordingly, which accelerates the difficulty of inspection.

JP 2009-109968 A JP 2001-59949 A JP 2001-75048 A JP 2005-49865 A

  The present invention has been made in view of the above circumstances, and the problem to be solved is that the alignment films for emitting the right-eye image light and the left-eye image light of the optical element plate are configured uniformly. An object of the present invention is to provide an optical element structure that can be inspected.

  As a result of intensive studies in view of the above circumstances, the present inventor has found that the above problem can be easily solved by adopting a specific configuration, and the present invention has been completed.

  That is, the gist of the present invention is that an optical element plate used in a stereoscopic image display device, an adhesive for bonding the optical element plate and the display device, and a release layer surface of a release film are bonded to the adhesive. The release film has an orientation main axis direction of 12 degrees or less, an ISC-S value in crossed Nicols of 75 or less, and an image clarity value of 90% or more. The present invention resides in an optical element structure having a release layer on at least one surface of a biaxially oriented polyester film containing particles of 0.2 to 2.0 μm.

  According to the present invention, there is provided an optical element structure capable of easily inspecting that the respective alignment films that emit the right-eye image light and the left-eye image light of the optical element plate are configured uniformly. The industrial value of the present invention is high.

  As the polyester in the present invention, typically, for example, polyethylene terephthalate in which 80 mol% or more of the structural unit is ethylene terephthalate, polyethylene-2 in which 80 mol% or more of the structural unit is ethylene-2,6-naphthalate, Examples include 6-naphthalate and poly-1,4-cyclohexanedimethylene terephthalate in which 80 mol% or more of the structural unit is 1,4-cyclohexanedimethylene terephthalate. Other examples include polyethylene isophthalate and poly-1,4-butylene terephthalate.

  Examples of copolymer components other than the above-described dominant component include propylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, neopentyl glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, diethylene glycol, Diol components such as triethylene glycol, polyethylene glycol, polytetramethylene glycol, polyalkylene glycol, isophthalic acid, 2,7-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, oxalic acid, malonic acid, succinic acid, adipic acid, Esterogenic derivatives such as azelaic acid, sebacic acid, diphenyl ether dicarboxylic acid and oxymonocarboxylic acid can be used.

  Further, as the polyester, in addition to a homopolymer or a copolymer, a small proportion of a blend with another resin can also be used. Examples of resins blended with polyethylene terephthalate include various copolymerized polyethylene terephthalates such as isophthalic acid copolymer, cyclohexanedimethylene terephthalate copolymer, polyethylene glycol copolymer, polyethylene naphthalate and copolymerized polyethylene naphthalate, poly Examples include butylene terephthalate.

  As a preferred method of adjusting the film haze value at the same time as imparting slipperiness to the polyester film, a method of blending particles into the polyester film is used. The film haze and image clarity value can be adjusted by the type, particle diameter, and content of the inert particles to be blended.

Examples of the particles to be blended in the film include silicon oxide, alumina, calcium carbonate, kaolin, titanium oxide, and crosslinked polymer fine powder as described in JP-B-59-5216. These particles may be used alone or in combination of two or more components. The blending amount of these particles is usually 1% by weight or less, preferably 0.01 to 1% by weight, more preferably 0.02 to 0.6% by weight, based on the polyester constituting the film. When the content of the particles is small, the film surface cannot be appropriately roughened, and in the film production process, there is a tendency that the surface is easily scratched or the winding properties are inferior. Further, when the content of the particles exceeds 1% by weight, the degree of roughening of the film surface becomes too large, and the transparency may be impaired.

  The average particle size of the particles contained in the polyester film needs to be in the range of 0.2 to 2.0 μm, and preferably in the range of 0.5 to 1.5 μm. In the case of particles having an average particle size of less than 0.2 μm, a large amount of particles are required to make the film surface an appropriate rough surface. Further, in the case of particles exceeding 2.0 μm, the image clarity value described later cannot be 90% or more, and the testability cannot be satisfied.

  On the other hand, in order to improve the transparency of the film, when a laminated film of two or more layers is used, a method of blending particles only in the surface layer is also preferably employed. The surface layer in this case is at least one of the front and back layers, and of course, particles can be blended in both the front and back layers. The blending amount of the particles in the case of such a laminated film is preferably 0.01 to 1% by weight, more preferably 0.02 to 0.6% by weight, based on the polyester constituting the surface layer.

  The particle size distribution of the particles used is preferably sharp. Specifically, those having a particle size distribution value of 1.0 to 2.0, which is an index representing the sharpness of the particle size distribution, are preferable. Here, the particle size distribution value is the particle size distribution value d25 / d75 (d25 and d75 are calculated by calculating the accumulated accumulation of the particle group from the large particle side, and the particle size corresponding to 25% and 75% of the total volume (μm Is a value defined by When the particle size distribution value exceeds 2.0, coarse particles become luminescent spots, which may similarly hinder foreign matter inspection.

  The method for adding particles to the polyester is not particularly limited, and a conventionally known method can be adopted. For example, it can be added at any stage of polymerizing the polymer.

  Also, a method of blending a slurry of particles dispersed in ethylene glycol or water with a vented kneading extruder and a polyester raw material, or a blending of dried particles and a polyester raw material using a kneading extruder. It is done by methods.

  In the present invention, the image clarity value of the biaxially oriented polyester film in the measurement method described later needs to be 90% or more. A release film using this biaxially oriented polyester film is used as a member of a laminate that is laminated with the configuration of an optical element plate, an adhesive, and a release film. This laminate is used for product inspection. The inspection is performed by the crossed Nicols method of polarized transmitted light. If the image clarity value of the biaxially oriented polyester film is less than 90% in this inspection step, the image may be distorted during defect inspection with crossed Nicol transmitted light, which may hinder visual inspection or automatic inspection. Furthermore, in order to obtain 3D images, the optical element plate described above has respective alignment films that emit image light for the right eye and image light for the left eye. Similarly, if the image distortion is large during defect inspection, It is not preferable because the alignment film is inspected to be processed in an orderly and homogeneous manner.

  Moreover, it is preferable that the surface roughness (Ra) of a biaxially-oriented polyester film is 11-25 nm, More preferably, it is 11-22 nm. When Ra of the biaxially blended polyester film exceeds 25 nm, the planarity of the surface is impaired, and the polyester film becomes whitish, which may hinder the inspection of the optical element structure. On the contrary, when the Ra of the polyester film is less than 11 nm, the surface of the polyester film becomes extremely flat, and not only the inferior winding properties in the polyester film production process, but also when used as a member of an optical element structure as a release film However, since the member is on the outermost surface of the optical element structure, the slipperiness of the optical element structure is impaired, and the workability tends to be greatly deteriorated.

  In addition to the above-mentioned particles, conventionally known antioxidants, antistatic agents, thermal stabilizers, lubricants, dyes, pigments, and the like can be added to the polyester film in the present invention as necessary.

  The film thickness of this invention is 10-100 micrometers normally, Preferably it is the range of 20-75 micrometers. When this range is exceeded, the handleability of the film may deteriorate, or the production cost may increase.

  The biaxially oriented polyester film used for the release film of the present invention needs to satisfy that the inclination of the orientation main axis is 12 degrees or less and the ISC-S value in crossed Nicols is 75 or less. In addition, the inclination of the orientation principal axis here is also called an orientation angle, and is the inclination of the principal axis with respect to the film width direction or the longitudinal direction. As described above, the optical element laminate using the release film of the present invention is inspected by the crossed Nicols method of polarized transmitted light. In the case of a release film using a biaxially oriented polyester film having an orientation angle of more than 12 degrees in this inspection process, light leakage is large, which hinders the detection of defects such as foreign matter and scratches. Further, the above-described optical element plate has alignment films for emitting right-eye image light and left-eye image light in order to obtain a 3D image. Similarly, if the light leakage is large, each alignment film is orderly and homogeneous. It is not preferable because it also hinders the inspection of whether or not it has been processed. The ISC-S value is obtained by quantifying the luminance unevenness of the entire surface by an algorithm unique to I-System Co., Ltd. If this ISC-S value is greater than 75, the uneven brightness in the biaxially oriented polyester film surface becomes remarkable, which also becomes an obstacle in the crossed Nicols inspection of the laminate, which is not preferable.

  In the biaxially oriented polyester film of the present invention, the orientation of the orientation main axis can be adjusted by changing conditions such as the temperature and stretching ratio in longitudinal stretching, the temperature and stretching ratio in transverse stretching, and the relaxation treatment. Moreover, as a specific prescription for setting the ISC-S value of the polyester film to 75 or less, it is possible to obtain an unstretched film with extremely small longitudinal thickness unevenness. Furthermore, both ends of the unstretched film become thick due to the edge bead phenomenon during casting, and it is also preferable to reduce this. In addition, in the roll stretching process of sequential biaxial stretching, it is preferable to perform uniform stretching in the longitudinal direction as well as extremely uniform stretching in the width direction. As a means for uniformly stretching in the longitudinal direction, the draw ratio is an important factor. At the same time, the draw ratio in the longitudinal direction is an important factor for the inclination of the orientation main axis, and there is an appropriate range for both to satisfy the claims.

  For this reason, in the biaxially oriented polyester film of the present invention, the draw ratio in the longitudinal direction is preferably from 2.7 times to 3.0 times, more preferably from 2.8 times to 2.95 times. It is. When the draw ratio in the longitudinal direction is less than 2.7 times, the orientation angle can be easily reduced, but the ISC-S value tends to increase and luminance unevenness tends to become remarkable. Moreover, when the draw ratio in the longitudinal direction exceeds 3.0 times, the ISC-S value becomes small, but the orientation angle becomes large, and light leakage at the time of inspection increases, thereby hindering the detection of defects. Sometimes.

  Regardless of the stretching ratio in the longitudinal direction, it is preferable to reduce the temperature difference during stretching as a method for making the uniform in the width direction, and the preheating and stretching temperature should be sufficient so that the difference in film temperature in the width direction is small. It is preferable to increase the temperature and give a uniform amount of heat, and when there is a thickness difference in the width direction of the unstretched film, heating is performed accordingly, so that the film temperature difference is as small as possible in the width direction.

  In the biaxially oriented polyester film used for the release film of the present invention, the birefringence Δn, which is the difference in refractive index between the main orientation axis and the orientation axis perpendicular thereto, is preferably 0.05 or more. More preferably, it is 0.056 or more and 0.07 or less. When the birefringence Δn is less than 0.05, the distribution of the polyester molecular chains in the film plane becomes too random, and even in the direction of the orientation main axis is 12 degrees or less, the direction orthogonal to the main orientation axis. Because of this, the linearly polarized light used in the crossed Nicols method becomes close to circularly polarized light. For this reason, light leakage is likely to occur during the crossed Nicols inspection.

  Next, although the manufacture example of the polyester film in this invention is demonstrated concretely, it is not limited to the following manufacture examples at all except the draw ratio of a longitudinal direction.

  That is, a method of using the polyester raw material described above and cooling and solidifying a molten sheet extruded from a die with a cooling roll to obtain an unstretched sheet is preferable. In this case, in order to improve the flatness of the sheet, it is necessary to improve the adhesion between the sheet and the rotary cooling drum, and an electrostatic application adhesion method and / or a liquid application adhesion method is preferably employed. Next, the obtained unstretched sheet is stretched in the biaxial direction. In that case, first, the unstretched sheet is stretched in one direction by a roll or a tenter type stretching machine. The stretching temperature is usually 70 to 120 ° C., preferably 80 to 110 ° C., and the draw ratio is usually 2.5 to 7 times. In the biaxially oriented polyester film of the present invention, the stretching temperature is 2.7 times to 3 times. It is necessary to be 0 times.

  Next, the film is stretched in the direction perpendicular to the first stretching direction. In that case, the stretching temperature is usually 70 to 170 ° C., and the stretching ratio is usually 3.0 to 7 times, preferably 3.5 to 6 times. is there. Subsequently, heat treatment is performed at a temperature of 180 to 270 ° C. under tension or under relaxation within 30% to obtain a biaxially oriented film.

  In the above-described stretching, a method in which stretching in one direction is performed in two or more stages can be employed. In that case, it is preferable to carry out so that the draw ratios in the two directions finally fall within the above ranges.

  In the present invention, the simultaneous biaxial stretching method can be adopted for the production of the polyester film constituting the release film. The simultaneous biaxial stretching method is a method in which the unstretched sheet is usually stretched and oriented in the machine direction and the width direction at 70 to 120 ° C., preferably 80 to 110 ° C., and stretch ratio. As an area magnification, it is 4 to 50 times, preferably 7 to 35 times, and more preferably 10 to 25 times. Subsequently, heat treatment is performed at a temperature of 170 to 250 ° C. under tension or under relaxation within 30% to obtain a stretched oriented film. With respect to the simultaneous biaxial stretching apparatus that employs the above-described stretching method, a conventionally known stretching method such as a screw method, a pantograph method, or a linear driving method can be employed.

  Although the method in particular of forming a coating layer on the surface of a polyester film is not restrict | limited, The method of apply | coating a coating liquid in the process of manufacturing a polyester film is employ | adopted suitably. Specifically, a method of applying and drying a coating solution on the surface of an unstretched sheet, a method of applying and drying a coating solution on the surface of a uniaxially stretched film, and a method of applying and drying a coating solution on the surface of a biaxially stretched film Etc. Among these, it is economical to apply a coating solution on the surface of an unstretched film or a uniaxially stretched film, and then simultaneously dry and cure the coating layer in the process of heat-treating the film.

  Moreover, as a method for forming the coating layer, a method in which some of the above-described coating methods are used in combination can be adopted as necessary. Specifically, a method of applying a first layer on the surface of an unstretched sheet and drying, then stretching in a uniaxial direction, and then applying and drying a second layer can be used.

  Use the reverse roll coater, gravure coater, rod coater, air doctor coater, etc. shown in “Coating Method” by Yuji Harasaki, Tsuji Shoten, published in 1979, as a method of applying the coating solution to the surface of the polyester film Can do.

  The coating solution used in the present invention is usually preferably adjusted with water as the main medium from the viewpoint of safety and hygiene. As long as water is the main medium, a small amount of an organic solvent may be contained for the purpose of improving the dispersion in water or improving the film forming performance. The organic solvent is preferably used as long as it is dissolved in water when mixed with water, which is the main medium. However, if it is a stable emulsion (emulsion) that does not separate after standing for a long time, Alternatively, it may be used in a state where it does not dissolve in water. The organic solvent may be used alone or in combination of two or more as necessary.

  In the present invention, the release layer formed on at least one surface of the biaxially oriented polyester film is not particularly limited as long as it contains a material having releasability. Among them, the one containing a curable silicone resin is preferable because the releasability is improved. A type having a curable silicone resin as a main component may be used, or a modified silicone type by graft polymerization with an organic resin such as a urethane resin, an epoxy resin, or an alkyd resin may be used.

  As the type of the curable silicone resin, any of the curing reaction types such as an addition type, a condensation type, an ultraviolet ray curable type, an electron beam curable type, and a solventless type can be used.

Specific examples include KS-774, KS-775, KS-778, KS-779H, KS-847H, KS-856, X-62-2422, X-62-2461, Dow manufactured by Shin-Etsu Chemical Co., Ltd. -Corning Asia Co., Ltd. DKQ3-202, DKQ3-203, DKQ3-204, DKQ3-205, DKQ3-210, Toshiba Silicone Co., Ltd. YSR-3022, TPR-6700, TPR-6720, TPR-6721, Toray Dow Corning Co., Ltd. SD7220, SD7226, SD7229, etc. are mentioned. Further, a release control agent may be used in combination to adjust the release property of the release layer.
Further, as described above, a silane compound having an amino group may be added to the release layer.

  In the present invention, as a method for providing a release layer on the polyester film, a conventionally known coating method such as reverse roll coating, gravure coating, bar coating, doctor blade coating, or the like can be used.

The application amount of the release layer in the present invention is usually in the range of 0.01 to 1 g / m ² .

  In the present invention, a coating layer such as an adhesive layer, an antistatic layer and an oligomer precipitation preventing layer may be provided on the surface where the release layer is not provided, and the polyester film may be subjected to corona treatment, plasma treatment, etc. A surface treatment may be applied.

  The peeling force of the release film in the present invention is usually 10 to 100 mN / cm, preferably 10 to 50 mN / cm. If the peeling force is less than 10 mN / cm, the peeling force may become too light and may cause a problem of easy peeling even in a scene where it is not necessary to peel off. On the other hand, if it exceeds 100 mN / cm, the peeling force Becomes too heavy, and the pressure-sensitive adhesive may be deformed when it is peeled off, causing problems in the subsequent steps, or the pressure-sensitive adhesive may adhere to the release film side.

  The pressure-sensitive adhesive layer used in the present invention is composed of known pressure-sensitive adhesives such as acrylic pressure-sensitive adhesives, rubber-based pressure-sensitive adhesives, block copolymer-based pressure-sensitive adhesives, polyisobutylene-based pressure-sensitive adhesives, and silicone-based pressure-sensitive adhesives. Generally, an adhesive is comprised as compositions, such as an elastomer, a tackifier, a softening agent (plasticizer), a deterioration preventing agent, a filler, and a crosslinking agent.

  Examples of the elastomer include natural rubber, synthetic isoprene rubber, reclaimed rubber, SBR, block copolymer, polyisobutylene, butyl rubber, polyacrylate copolymer, and silicone rubber according to the type of each pressure-sensitive adhesive. Examples of the tackifier include rosin, hydrogenated rosin ester, terpene resin, aromatic modified terpene resin, hydrogenated terpene resin, terpene phenol resin, aliphatic petroleum resin, aromatic petroleum resin, and aliphatic reductive water. Examples include petroleum resin, coumarone / indene resin, styrene resin, alkylphenol resin, and xylene resin.

  Examples of the softening agent include paraffinic process oil, naphthenic process oil, aromatic process oil, liquid polybutene, liquid polyisobutylene, liquid polyisoprene, dioctyl phthalate, dibutyl phthalate, castor oil, tall oil, and the like. Examples of the deterioration preventing agent include aromatic amine derivatives, phenol derivatives, organic thioates, and the like.

  Examples of the filler include zinc white, titanium white, calcium carbonate, clay, pigment, and carbon black. When a filler is contained, it is used in a range that does not greatly affect the total light transmittance of the release film.

  Formation of an adhesive layer is performed by the method of apply | coating an adhesive to the surface of the release layer of a release film. As a coating method, the same method as that used for forming the release layer can be adopted. The thickness of the pressure-sensitive adhesive layer is usually 10 to 50 μm, preferably 20 to 40 μm.

  Drying and / or curing (thermal curing, ionizing radiation curing, etc.) of the coating of the pressure-sensitive adhesive layer or the release layer can be performed individually or simultaneously. When performing simultaneously, it is preferable to carry out at the temperature of 80 degreeC or more. The drying and curing conditions are preferably 80 ° C. or higher and 10 seconds or longer. When the drying temperature is less than 80 ° C. or the curing time is less than 10 seconds, the coating film is not completely cured, and the coating film tends to fall off, which is not preferable.

  After drying the coating film of the pressure-sensitive adhesive layer, the optical element plate and the pressure-sensitive adhesive layer used in the stereoscopic image display device were bonded together, and the optical element plate, the pressure-sensitive adhesive layer, the release layer, and the biaxially oriented polyester film were laminated in this order. It is necessary for the present invention to form a laminate.

  The present invention requires an optical element plate for use in a stereoscopic image display device. There are various prescriptions for obtaining 3D images, but the optical element plate of the present invention has respective alignment films for emitting right-eye image light and left-eye image light, and each alignment film is homogeneous. It is preferable that the optical element plate is configured. For example, a product such as “Xpol” sold by Arisawa Manufacturing Co., Ltd. is representative. The alignment film can be formed by a known method.

Next, this description will be further described with reference to examples. However, the present invention is not limited to the following examples without departing from the gist thereof. In addition, the evaluation method of the physical property in a following example and a comparative example is as follows.

(1) Measurement of Intrinsic Viscosity of Polyester 1 g of polyester was accurately weighed and dissolved by adding 100 ml of a mixed solvent of phenol / tetrachloroethane = 50/50 (weight ratio), and measured at 30 ° C. When measuring the intrinsic viscosity of the opposite surface of the release layer, a measurement sample was taken from the surface of the polyester film and measured. In collecting the sample, a SAICAS (Surface and Interface Cutting Analysis System) apparatus manufactured by Daipura Wintes was used.

(2) Average particle size (d50) and particle size uniformity (d25 / d75)
The average particle size d50 was defined as the particle size having an integrated volume fraction of 50% in an equivalent spherical distribution measured using a centrifugal sedimentation type particle size distribution analyzer (SA-CP3 type) manufactured by Shimadzu Corporation. In addition, the ratio d25 / d75 of the diameter of the point having a weight fraction of 25% and the diameter of the point having a weight fraction of 75%, integrated from the large particle side, was used as the particle size distribution value.

(3) Measurement of orientation (orientation angle) of orientation main axis Using a polarizing microscope manufactured by Carl Zeiss, the orientation of the polyester film is observed, and the direction of the main orientation axis in the polyester film plane is relative to the width direction of the polyester film. The number of tilts was measured to determine the orientation angle. This measurement was carried out at a total of three locations on the center and both ends of the film, and the largest orientation angle value among the three locations was taken as the maximum orientation angle.

(4) Film haze The turbidity of the film was measured according to JIS-K6714 using a Nippon Denshoku Industries Co., Ltd. spheroid turbidimeter NDH-20D.

(5) ISC-S value Eyescale- manufactured by I-System Co., Ltd., using Dentsu Sangyo Co., Ltd. HF-SL-A312LC as a light source and using a polarizing plate having a single transmittance of 42% and an orthogonal transmittance of 0.009%. Measurements were performed using 3W. The measurement was performed by sandwiching the sample at an angle such that the luminance value was 200 cd / m ² between the orthogonal polarizing plates. The measurement area of the sample was 150 mm square, and measurement was performed at intervals of 150 mm for the entire product width to obtain the largest value.

(6) Birefringence Δn
Using an Abbe refractometer manufactured by Atago Optical Co., Ltd., the maximum refractive index nγ in the film plane and the refractive index nβ in the direction perpendicular thereto were measured, and the refractive index blowing from the following formula was measured. The refractive index was measured at 23 ° C. using sodium D line.
Birefringence index △ n = nγ-nβ

(7) Measurement of image clarity value According to JIS-K7105, the image clarity value of the film was measured by the transmission method with image clarity measuring instrument ICM-1 manufactured by Suga Test Instruments Co., Ltd. The value is read from an optical comb of 0.125 mm.

(8) Measurement of Ra JIS B0601-19 using a surface roughness measuring instrument SE3500 manufactured by Kosaka Laboratory.
Measurement was conducted according to 94. The measurement length was 2.5 mm.

(9) Evaluation of release film peeling force (F) After applying one side of a double-sided adhesive tape (Nitto Denko “No. 502”) to the surface of the release layer of the sample film, cut into a size of 50 mm × 300 mm After that, the peel strength after standing for 1 hour at room temperature is measured. For the peeling force, a tensile tester (“Intesco model 2001 type” manufactured by Intesco Co., Ltd.) was used, and 180 ° peeling was performed under the condition of a tensile speed of 300 mm / min.

(10) Practical characteristics <Visual inspection property under crossed Nicols>
A release agent is applied onto the biaxially oriented polyester film and dried / cured, and then an acrylic pressure-sensitive adhesive is applied onto the release layer of the obtained release film and dried / cured. In this laminate, the release film and the optical element plate are disposed via an adhesive so that the film width direction is parallel or orthogonal to the respective alignment films that emit the image light for the right eye and the image light for the left eye of the optical element plate. Are closely adhered to obtain a laminate. A polarizing plate installed so as to be parallel to the alignment film of the optical element plate of the laminated body and a polarizing plate installed so as to be orthogonal thereto are prepared. The laminates were stacked so that the laminate was sandwiched between the polarizing plates, irradiated with white light from the side of one polarizing plate, and visually inspected under crossed Nicols. Inspectability in visual inspection was evaluated according to the following criteria.
"Criteria"
○: Inspection is possible without optical interference, and the alignment state of alignment films for right-eye image light and left-eye image light is clearly visible. △: Inspection is possible although there is optical interference, for right-eye image light, left-eye image light. The alignment state of the alignment film for use can be seen to some extent. X: There is optical interference and inspection is not possible, and there are places where the alignment state of the alignment film for right-eye image light and left-eye image light cannot be seen. There is no problem level.

<Manufacture of polyester (A)>
Starting from 100 parts by weight of dimethyl terephthalate and 60 parts by weight of ethylene glycol, magnesium acetate tetrahydrate is added as a catalyst to the reactor, the reaction start temperature is 150 ° C., and the reaction temperature is gradually increased as methanol is distilled off. The temperature was raised to 230 ° C. after 3 hours. After 4 hours, the transesterification reaction was substantially terminated. Ethyl acid phosphate was added to the reaction mixture, which was then transferred to a polycondensation tank, and 0.04 part of antimony trioxide was added to carry out a polycondensation reaction for 4 hours. That is, the temperature was gradually raised from 230 ° C. to 280 ° C. On the other hand, the pressure was gradually reduced from normal pressure, and finally 0.3 mmHg. After the start of the reaction, the reaction was stopped at a time corresponding to an intrinsic viscosity of 0.60 due to a change in stirring power of the reaction vessel, and the polymer was discharged under nitrogen pressure to obtain a polyester chip (A). The intrinsic viscosity of this polyester was 0.60.

<Manufacture of polyester (B)>
In the method for producing polyester (A), after adding ethyl acid phosphate, an ethylene glycol slurry of synthetic calcium carbonate particles having an average particle diameter of 0.7 μm was added so that the content of the particles with respect to polyester was 2% by weight. Obtained polyester (B) using the method similar to the manufacturing method of polyester (A). The obtained polyester (B) had an intrinsic viscosity of 0.60.

<Manufacture of polyester (C)>
In the production method of polyester (B), the additive particles are the same as the production method of polyester (B) except that the synthetic calcium carbonate particles having an average particle diameter of 1.5 μm and the content with respect to the polyester are 1% by weight. Polyester (C) was obtained using the method. The obtained polyester (C) had an intrinsic viscosity of 0.60.

<Manufacture of polyester (D)>
In the method for producing polyester (B), the additive particles are the same as the method for producing polyester (B) except that silica particles having an average particle diameter of 3.2 μm and the content with respect to polyester are 0.6% by weight. Polyester (D) was obtained using the method. The obtained polyester (D) had an intrinsic viscosity of 0.60.

・ Polyester film-1
Polyester (A) 80 wt% and polyester (B) 20 wt% are mixed as the raw material of the surface layer, and polyester (A) 97 wt% and polyester (B) 3 wt% are mixed as the raw material of the intermediate layer, with two vents Each was supplied to an extruder, melt-extruded at 290 ° C., and then cooled and solidified on a cooling roll having a surface temperature set to 40 ° C. using an electrostatic application adhesion method to obtain an unstretched sheet. Next, the film was stretched 2.9 times in the longitudinal direction at 95 ° C., then subjected to a preheating process in a tenter and 5.4 times transverse stretching at 130 ° C., followed by heat treatment at 212 ° C. for 10 seconds, At 180 ° C., 6.8% relaxation was added in the width direction to obtain a master roll having a width of 4000 mm. A slit was made from a position of 1400 mm from the end of the master roll, and the core roll was wound up by 1000 m to obtain a polyester film-1. The total thickness of the obtained film was 38 μm, and the thickness of each layer was 3 μm / 32 μm / 3 μm.

・ Polyester film-2
In polyester film-1, polyester film-2 was obtained in the same manner as polyester film-1, except that the raw material composition was changed to the raw material composition shown in Table 1.

・ Polyester film-3
In the polyester film-1, the raw material composition is changed to the raw material composition-b shown in Table 1, the longitudinal draw ratio is changed to 2.95 times, and the heat setting temperature is changed to 220 ° C. Thus, a polyester film-3 was obtained.

・ Polyester film-4
In the polyester film-1, a polyester film-4 was obtained in the same manner as the polyester film-1, except that the raw material composition was changed to the raw material composition-b shown in Table 1 and the longitudinal draw ratio was changed to 2.7 times. .

・ Polyester film-5
In polyester film-1, polyester film-4 was obtained in the same manner as polyester film-1, except that the raw material composition was changed to the raw material composition shown in Table 1.

・ Polyester film-6
In Polyester Film-1, the raw material composition is changed to the raw material composition shown in Table 1, the longitudinal magnification is 3.0 times, the lateral magnification is 4.5 times, the heat setting temperature is 232 ° C., and the relaxation rate is A polyester film-5 was obtained in the same manner as the polyester film-1, except that the content was changed to 3.5%.

・ Polyester film-7
In the polyester film-1, the raw material composition is changed to the raw material composition shown in Table 1, and the longitudinal magnification is changed to 2.5 times and the heat setting temperature is changed to 200 ° C. Polyester film-6 was obtained.

Example 1:
A release agent having a release agent composition shown below is applied to Polyester film-1 by a reverse gravure coating method so that the coating amount (after drying) is 0.1 g / m 2, a dryer temperature of 120 ° C., a line speed A roll-shaped release film was obtained under the condition of 30 m / min.
・ Releasing agent composition Curing type silicone resin (KS-847H: manufactured by Shin-Etsu Chemical Co., Ltd.) 100 parts Curing agent (PL-50T: manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part MEK / toluene mixed solvent (mixing ratio is 1: 1) 1500 parts Next From the roll-shaped release film, a sheet having the same size as the 20-inch television screen is cut out from the end of the film corresponding to the end position of the master roll when the polyester film is formed. The pressure-sensitive adhesive having the following composition is applied to the release layer surface of this sheet by a simple doctor blade method, and dried and cured in an oven at a temperature of 120 ° C. for 2 minutes to obtain a pressure-sensitive adhesive layer. It was.
-Adhesive composition Acrylic adhesive (copolymer of n-butyl acrylate and acrylic acid) 100 parts Urethane acrylate oligomer (molecular weight 3000-10000) 100 parts Diisocyanate curing agent 25 parts p-chlorobenzophenone 10 parts Next adhesive An optical element plate (“XPol” manufactured by Arisawa Manufacturing Co., Ltd.) was bonded to the surface of the agent layer so that the direction of the alignment film and the width direction of the release film coincided to obtain an optical element structure.

Example 2:
In Example 1, the release film was obtained like Example 1 except having changed the polyester film-1 into the polyester film-2.

Example 3:
In Example 1, the release film was obtained like Example 1 except having changed the polyester film-1 into the polyester film-3.

Example 4:
In Example 1, a release film was obtained in the same manner as in Example 1 except that the polyester film-1 was changed to the polyester film-4.

Comparative Example 1:
In Example 1, a release film was obtained in the same manner as in Example 1 except that the polyester film-1 was changed to the polyester film-5.

Comparative Example 2:
In Example 1, a release film was obtained in the same manner as in Example 1 except that the polyester film-1 was changed to the polyester film-6.

Comparative Example 3:
In Example 1, the release film was obtained like Example 1 except having changed the polyester film-1 into the polyester film-7.

  The evaluation results of the films obtained in each example and comparative example are summarized in Table 2 below.

  The optical element structure of the present invention makes it easy to provide an optical element plate for expressing 3D images on a large FPD such as a television and contributes to stabilizing the quality of the final product. it can.

Claims (2)

An optical element plate used in a stereoscopic image display device, an adhesive for bonding the optical element plate and the display device, and a structure in which a release layer surface of a release film is bonded to the adhesive. Type film, the orientation of the orientation main axis is 12 degrees or less, the ISC-S value in crossed Nicols is 75 or less, and the image clarity value is 90% or more. An optical element structure comprising a release layer on at least one surface of a biaxially oriented polyester film containing particles. 2. The structure according to claim 1, wherein a birefringence Δn, which is a difference in refractive index between a main orientation axis of the biaxially oriented polyester film and an orientation axis perpendicular thereto, is 0.05 or more.