JP5044941B2 - Polyester film, method for producing the same, and use thereof - Google Patents

Description

  The present invention relates to a polyester film having a small retardation obtained by forming a polyester having a cyclic acetal skeleton in a diol unit by a melt extrusion method, and a method for producing the same. Furthermore, the present invention relates to a retardation film, a polarizing plate protective film, a light diffusion film, a lens sheet, an antireflection film, and an optical information recording medium using the polyester film.

[1] Polyester and polyester film In recent years, the demand for flat panel displays such as liquid crystal displays and plasma displays as display devices for personal computers, televisions, mobile phones, personal digital assistants, car navigation systems, liquid crystal projectors, and watches has grown rapidly. Yes.

  Flat panel displays are composed of various optical films such as polarizing plates, retardation films, prism sheets, and antireflection films. Among the performances required for these films, birefringence contributes to imaging properties. This is one of the important optical properties. In general, as the optical film, an optically isotropic film having a small birefringence such as a polarizing plate protective film or an optically anisotropic film having a certain birefringence such as a retardation film is used. However, since an optically anisotropic film is produced by subjecting an optically isotropic film to a stretching process, the optically isotropic film plays an important role.

  As optically isotropic films, films of triacetylcellulose, polycarbonate, amorphous cyclic polyolefin, polyethersulfone, polyarylate, polyester, and the like are known. Most of these films are produced by a casting method in which a resin is dissolved in a solvent and the film is formed while the solvent is evaporated (see Patent Documents 1 to 6). However, the casting method has a problem that the productivity is remarkably inferior and the residual solvent in the film has an adverse effect, and the production method using the solvent is not preferable from the viewpoint of reducing the environmental load.

  For this reason, several film forming methods by the melt extrusion method have been proposed. For example, it has been proposed to obtain an optically isotropic film by melt extrusion of amorphous cyclic polyolefin (see Patent Document 7). However, since the amorphous cyclic polyolefin is expensive, the film is also expensive, and the amorphous cyclic polyolefin has a low polarity so that a special adhesive is required to adhere to other members. There is.

  A method of forming polyethersulfone by melt extrusion has also been proposed (see Patent Document 8). However, since the resin itself is expensive, the film is also expensive, and a film having a smooth surface can be obtained. There is a problem that the film forming process is difficult and complicated.

  On the other hand, a method of obtaining an optically isotropic film by reheating a polycarbonate film formed by an extrusion method has been proposed (see Patent Document 9), but this method is economically disadvantageous because of the increased number of steps. Furthermore, there is a problem that the film surface may be damaged during the process. In fact, there is no known optically isotropic film that is formed by extrusion molding and has excellent economic efficiency.

[2] Retardation film The retardation film is obtained by stretching an optically isotropic film to develop birefringence.
The retardation film is an important member that realizes an improvement in contrast and expansion of a viewing angle range in an image display device such as a liquid crystal display device by optical compensation. As the resin for forming the retardation film, engineering plastic resins such as polycarbonate (hereinafter referred to as PC), triacetyl cellulose (hereinafter referred to as TAC), and cycloolefin polymer (hereinafter referred to as COP) are generally mentioned. The retardation film is produced by forming these resins into a film by a casting method or a melt extrusion method, and stretching the obtained raw film to express a desired retardation.

  Examples of the performance required for the raw film include small thickness unevenness, low retardation, small retardation unevenness, and high retardation expression at a low draw ratio in a film having an arbitrary thickness. By stretching an original film satisfying such performance, it becomes possible to produce a retardation film with less unevenness in thickness and optical properties.

  In recent years, overseas competitors have launched in Japan, and the appearance of SED (Surface-conduction Electron-emitter Display), which is a method other than liquid crystal display devices. It has entered the era. Therefore, the cost reduction of various members has begun to be demanded by the cost review of the liquid crystal display device itself by an electrical manufacturer. Therefore, further cost reduction is demanded for retardation films indispensable for liquid crystal display devices.

  However, in general production of a conventional PC or TAC film raw material, only film formation by a casting method having a high production cost is employed. The reason is that it is difficult to achieve low retardation in the melt extrusion method having a low production cost. In addition, a COP film produced by a conventionally known melt extrusion method has a problem in that retardation occurs due to orientation or stress of a polymer bond chain during molding (see Patent Document 10). Furthermore, since the stability of the optimum manufacturing conditions is low, it takes time until a raw film satisfying the required performance is stably produced. As a result, there is a problem that the yield is low and the cost is high.

  Disclosed is a method of overlapping STN liquid crystal cells (phase compensation of STN liquid crystal cells) in order to prevent coloring of display colors due to birefringence of STN (Super Twisted Nematic) liquid crystal cells and reduction in contrast. (See Non-Patent Document 1). Since the alignment of the liquid crystal is continuous, in order to compensate for the birefringence, it is necessary to compensate with an STN liquid crystal cell that is similarly continuously aligned. In Non-Patent Document 1, a plurality of retardation films are laminated instead of a reverse twist (reverse twist) STN liquid crystal cell. Non-Patent Document 1 describes that by laminating ten retardation films while shifting their slow axes, it has the same effect as a reverse twist (reverse twist) liquid crystal cell. Further, although a single retardation film has a certain effect, it is described that by laminating two sheets, a better effect than that of a single retardation film is obtained. However, no specific method for laminating the retardation film is mentioned.

  Further, it is disclosed that a retardation film (described as an optical compensation film in Non-Patent Document 2) is used by being bonded between a polarizing plate and a glass substrate (see Non-Patent Document 2). Furthermore, if the polarizing plate is composed only of a stretched polyvinyl alcohol (PVA) film, the strength and the size and shape change due to heat and humidity are large, so triacetyl cellulose (TAC) is laminated as a protective layer on both sides of the polarizing plate. It is common (refer nonpatent literature 2).

[3] Polarizing plate protective film The polarizing plate protective film is obtained using an optically isotropic film.
Liquid crystal display devices have been increasingly used year by year as space-saving image display devices with low power consumption. Conventionally, the large viewing angle dependence of images has been a major drawback of liquid crystal display devices, but recently, high viewing angle liquid crystal modes such as VA mode and IPS mode have been put into practical use, and high viewing angles such as televisions have been used. The demand for liquid crystal display devices is also rapidly expanding in required fields. A liquid crystal display device is composed of a liquid crystal cell, an alignment film, a polarizing plate, a retardation film, a field-of-view film, and a backlight. Further improvement in quality and productivity is required for the polarizing plate used in the liquid crystal display device. It has been.

  Typical optical films used for liquid crystal display devices include a polarizing plate protective film, an alignment film, a retardation film, a viewing angle widening film, and the like. The alignment film is in direct contact with the liquid crystal and has a function of aligning the liquid crystal with respect to the substrate. A typical material is aromatic polyimide. The retardation film is a material used for optical compensation, and is used for the purpose of preventing the occurrence of viewing angle dependency such as coloring of display caused by optical distortion due to birefringence or modulation in the viewing angle direction. Representative materials include polycarbonate and triacetyl cellulose (TAC), and recently, ZEONOR (Nippon Zeon Co., Ltd.) and Arton (JSR Co., Ltd.), which are bulky cyclic olefin resins. Viewing angle expansion film is a film that allows images to be seen clearly even when the screen is viewed from an oblique direction. Typical materials include stretched TAC film and discotic liquid crystal applied to a film substrate and oriented. There is.

  The polarizing plate is a film that transmits only polarized light in a specific direction of random polarized light (non-polarized light) such as natural light, and is generally composed of a polarizing film and a polarizing plate protective film. The polarizing film is a stretched polyvinyl alcohol film dyed with iodine or a dichroic dye. On the other hand, the polarizing plate protective film is a transparent resin film provided on one side or both sides of the polarizing film for the purpose of protecting the polarizing film, is optically transparent, has a uniform thickness, and has a product of birefringence and thickness. Are required to have a small retardation, small unevenness, and low moisture absorption. If the in-plane retardation is large, the unevenness is large, or the thickness unevenness is large, the image quality of the liquid crystal display device is remarkably deteriorated. In other words, a color skip phenomenon such as a partial thinning of the color, or an adverse effect such as distortion of the image occurs. Currently, a TAC film having transparency, low birefringence, and moderate rigidity is most widely used as a polarizing plate protective film (see Non-Patent Document 3).

  When these films are produced, various stresses are generated in the film during molding due to melt flow of the resin, drying shrinkage when removing the solvent, thermal shrinkage, stress during transportation, and the like. Therefore, the obtained film has a problem that retardation tends to remain due to birefringence due to molecular orientation induced by these stresses. As a method for producing a film, a solution casting method and a melt extrusion method are widely used. In optical films including the polarizing plate protective film, optical properties with extremely high accuracy are required, and the uniformity and appearance of the film thickness are particularly important, so the solution casting method has been adopted. Yes. The polarizing plate protective film is prepared by filtering a concentrated solution obtained by dissolving TAC in a solvent, then pouring it onto an endless support such as a roll or band, forming a self-support, peeling it off, and removing the solvent. And then dried.

  However, compared with the melt extrusion method, the solution casting method has a big problem that it is inferior in productivity and high in production cost because it undergoes a solvent removal step. If the solvent removal time is shortened in order to avoid these problems, whitening and retardation of the film and unevenness thereof will increase, and it will be difficult to produce a film having the characteristics required for a polarizing plate protective film. In addition, it is difficult to completely remove the solvent from the film. If there is residual unevenness of the solvent in the film, stress unevenness occurs during stretching, and uniform retardation cannot be realized, and display of portable OA equipment and automobiles In a liquid crystal display device that is used under conditions where the temperature changes drastically as in the device, warping may occur and a problem may occur in the image. Further, if the drying equipment is enriched so that the solvent can be completely removed, the manufacturing equipment cost becomes high, and a large amount of energy is required, so that the running cost becomes high. Furthermore, since a large amount of organic solvent such as methylene chloride (methylene chloride) is used during film production, the solvent may be volatilized into the atmosphere, which may adversely affect the health of workers and the environment. There is also a problem.

  For these reasons, in recent years, attempts have been made to convert the optical film production method from a solution casting method to a melt extrusion method. For example, an attempt has been made to produce an optical polycarbonate film having a low in-plane retardation in the visible wavelength range (10 nm or less) using a melt extrusion method (see Patent Document 11). However, since the in-plane retardation of the film obtained by melt extrusion is as high as 22 to 50 nm, the film is retained in a heating apparatus such as an oven or a drying furnace for a certain period of time while applying tension in the film processing direction. In-plane retardation is reduced to 10 nm or less. That is, a film having low in-plane retardation cannot be produced only by the melt extrusion method, and a film having low retardation is obtained by the next heat treatment step.

  Further, the TAC film has a problem that moisture permeability is large when used as a polarizing plate protective film. If the polarizing plate protective film has a large water vapor transmission rate, the heat and humidity resistance will deteriorate, causing dissociation of polyiodine ions and elimination of iodine in the polarizing film, leading to a decrease in polarizing performance and the possibility of warping the polarizing plate. There is. Therefore, many techniques for preventing the degradation of heat and heat resistance have been proposed. Most of them are methods of adding a hydrophobic additive to TAC or introducing a hydrophobic substituent to reduce its moisture permeability. (See Patent Documents 12 to 15). However, if the TAC film is excessively hydrophobized, the adhesive bonding between the TAC film and the polarizing film is hindered. In addition, since there are many additives that easily develop birefringence, there is a problem that the retardation of the film increases. That is, it has been difficult to obtain a polarizing plate protective film that achieves all of optical properties represented by high productivity, low retardation, and high total light transmittance, low moisture permeability, and appropriate polarizing plate bonding simultaneously.

[4] Lens sheet The lens sheet is obtained using an optically isotropic film as a base material.
In recent years, color liquid crystal display devices have been widely used in various fields as portable notebook personal computers, desktop personal computer liquid crystal monitors, liquid crystal television or car navigation monitors, mobile phone monitors, and the like. Since the liquid crystal itself is not a self-luminous element, a device that shines light from the back side, called a backlight, is used. The backlight includes a fluorescent tube, a light guide plate, a reflection sheet, a prism sheet, and the like. The prism sheet is disposed on the light exit surface of the light guide plate and improves the optical efficiency of the backlight to improve the luminance. For example, the prism sheet is obtained by forming an optical element in which prism rows having a triangular cross section are arranged in parallel on a resin film. A lens sheet (Fresnel lens sheet) in which an optical element having a concentric Fresnel lens portion is formed on the resin film surface may be used. In some cases, a lens sheet (lenticular lens sheet) in which an optical element having a lenticular lens portion in which a plurality of cylindrical lens rows are formed in parallel is formed on the surface of the resin film is used. The prism sheet, the Fresnel lens sheet, and the lenticular lens sheet are collectively referred to as a lens sheet.

  In general, a prism sheet is made by injecting an active energy ray-curable resin into a mold formed in a predetermined prism pattern, overlaying a transparent substrate thereon, and then irradiating active energy rays through the transparent substrate to form the curable resin. Obtained by curing. As the transparent substrate, a stretched heat-set polyethylene terephthalate film (O-PET) is often used because of mechanical strength, cost, transparency, and the like (see, for example, Patent Document 16). However, in order to prevent thermal shrinkage due to irradiation heat during curing, it is necessary to reduce the amount of irradiation energy, which is one reason why productivity is not improved. In addition, the production of O-PET is complicated because it includes many steps such as melt extrusion, stretching, and heat setting (see, for example, Patent Document 17). Furthermore, in applications such as car navigation and mobile phone monitors that are exposed to particularly high temperature environments, it is necessary to make the O-PET thick from the viewpoint of dimensional stability, which hinders thinning. Further, as described in Non-Patent Document 4, molecular orientation is not preferable for optical films, and there is a demand for resin films that are non-oriented (low retardation) and have strength without stretching. The present condition is that the resin film which satisfy | fills has not been obtained yet.

[5] Light diffusion film The light diffusion film is obtained using an optically isotropic film as a base material.
Conventionally, a stretched polyethylene terephthalate film (hereinafter referred to as a PET stretched film) has been used as a base material for a light diffusion film of a liquid crystal display, taking advantage of its excellent mechanical strength, heat resistance and dimensional stability at high temperatures.

  In recent years, it has been necessary to increase the amount of light from a backlight light source in order to improve the contrast and enlarge the size of a liquid crystal display panel. However, the conventional PET film has a problem that even if the heat resistance is improved by stretching, the temperature rises during use and the heat resistance is still insufficient, so that the amount of light cannot be increased. A film for a light diffusing plate in which a raw film made of polyimide and polyethylene terephthalate is biaxially stretched to improve heat resistance is disclosed (see Patent Document 18). However, the stretching cost is as high as the conventional PET stretched film. Further, as described in Non-Patent Document 4, molecular orientation is not preferable for optical films, and there is a demand for resin films that are non-oriented (low retardation) and have strength without stretching. The present condition is that the resin film which satisfy | fills has not been obtained yet.

[6] Antireflection film The antireflection film is obtained using an optically isotropic film as a base material.
In recent years, the demand for flat panel displays such as liquid crystal displays, plasma displays, and projection displays as image display devices such as personal computers, televisions, mobile phones, portable information terminals, car navigation systems, liquid crystal projectors, and watches has been rapidly increasing. In these image display devices, an antireflection film is provided on the outermost layer of the image display device in order to suppress a decrease in visibility due to reflection of external light.

Triacetyl cellulose (TAC) and polyethylene terephthalate (PET) are mainly used for the base material of the antireflection film, and a hard coat layer and an antireflection layer are laminated on the base material.
The TAC substrate is prepared by continuously casting a solution obtained by dissolving TAC having a bound acetic acid amount (acetylation degree) of 60 to 62% and a plasticizer in a methylene chloride / methanol mixed solvent, and then evaporating the solvent. Obtained by a solution casting method. However, this solution casting method requires a long time and a large amount of energy for the melting step and the drying step, which causes high costs and environmental problems (see Patent Document 19). Further, when the antireflection layer is coated on the TAC film, since the TAC film is easily cut, continuous winding coating is difficult, and it is necessary to perform single-wafer coating, resulting in poor productivity (see Non-Patent Document 5). .

  Since a PET unstretched film is inferior in heat resistance, it may shrink due to heat when an antireflection layer is coated on the PET film by vapor deposition or the like. Therefore, it is necessary to reduce the amount of irradiation energy, which is one factor that productivity is not improved. In addition, the production of a PET film that has been stretched and heat-fixed to improve heat resistance includes many steps such as melt extrusion, stretching, and heat-setting (see Patent Document 20). Furthermore, in applications such as car navigation and mobile phone monitors that are exposed to particularly high temperature environments, it is necessary to make the stretched PET thick from the viewpoint of dimensional stability, which hinders thinning. Further, as described in Non-Patent Document 4, molecular orientation is not preferable for optical films, and there is a demand for resin films that are non-oriented (low retardation) and have strength without stretching. The present condition is that the resin film which satisfy | fills has not been obtained yet.

[7] Optical information recording medium The optical information recording medium is obtained using an optically isotropic film as a protective layer.
In recent years, the density of optical information recording media has been increasing, and ultra-high density optical discs such as Blu-ray discs are being realized. The Blu-ray disc can record large capacity data of 23 GB (giga byte) or more in single layer recording and 47 GB or more in two layer recording on a disc having a diameter of 120 mm. Blu-ray discs use an optical system with a recording / reproducing wavelength of about 405 nm and a numerical aperture of about 0.85, and achieve a high density by setting the track pitch of the grooves on the disc to about 0.32 μm. Due to this large numerical aperture, the distance between the pickup lens and the information recording / reproducing layer (hereinafter also simply referred to as “recording layer”) is much shorter than that of current DVD discs, and the thickness of the protective layer protecting the recording layer is 100 μm. And it is required to be very thin. Further, since the polarization of laser light is used for reproducing information, the protective layer is required to have optical isotropy. Usually, the protective layer is composed of a transparent adhesive layer and an optically isotropic film, and it is strongly demanded to produce the optically isotropic film at a low cost.

  In the Blu-ray disc, it is specified that the thickness of the protective layer formed on the laser beam incident side of the information recording / reproducing layer is 100 μm (± 2 μm). As an optical characteristic required for this protective layer, the in-plane retardation of the protective layer at a wavelength of 405 nm is 5 nm or less. Usually, a polycarbonate (hereinafter also simply referred to as “PC”) film obtained by a casting method is mainly used as a protective layer, but there is a problem that the disk cost increases due to the poor productivity. It was. Further, it is a well-known fact that a PC film obtained by melt extrusion of PC is difficult to achieve low retardation, and does not satisfy the performance as an optically isotropic film constituting a Blu-ray Disc protective layer. (Refer nonpatent literature 6).

The structure of a Blu-ray disc is usually that a reflective layer and a recording layer mainly composed of an organic dye are formed in this order on a base material on which guide grooves are formed, and a protective layer is formed on this recording layer. It has become. (See Patent Document 21).
JP-A-9-95544 Japanese Patent Laid-Open No. 7-256664 Japanese Patent No. 3404027 Japanese Patent Laid-Open No. 7-73876 JP-A-8-318538 JP 7-41572 A Japanese Patent Laid-Open No. 2003-279741 Japanese Patent No. 3035204 Japanese Patent No. 2769020 JP 2004-109355 A JP 2003-302522 A Japanese Patent Laid-Open No. 2002-22756 JP 2002-146044 A JP 2001-343528 A JP-A-9-90101 JP-A-10-197702 JP 2004-131728 A JP 2002-341114 A JP-A-7-11055 JP 2004-131728 A JP 2005-186607 A Kobayashi, Shira, Nagae, Analysis of phase plate type black and white STN-LCD, IEICE Technical Report, 88, 54, 9-16, 1988 Satake, “Adhesive for polarizing plate”, Adhesion technology, Vol. 25, No. 1, 2005, Vol. 78, pp. 25-30 Supervised by Fumio Ide, “Optical Film for Display”, CM Publishing, 2004. Demand Competitive Analysis for Optical Transparent Plastic Film Fuji Chimera Research Institute 2004.11.04, P128 Published by Yano Research Institute, Inc., 2005 High Performance Film Market Outlook and Strategies, pages 86-87 Kazuo Yahata, “Characteristics of optically transparent resin and molding technology and application to optical film—molding of polycarbonate film and development of optical application”, Technical Information Association, March 28, 2005, p. 1-36

  In view of the circumstances as described above, an object of the present invention is an optically isotropic polyester film that can be formed by extrusion molding and is excellent in economic efficiency, a method for producing the same, a retardation film using the polyester film, and a polarizing film. An object of the present invention is to provide an optical member such as a plate protective film, a light diffusion sheet, a lens sheet, an antireflection film, and an optical information recording medium.

  As a result of intensive studies, the present inventors have found that a polyester having a specific amount of a cyclic acetal skeleton in a diol unit can be easily formed by extrusion, and the obtained film has an in-plane retardation of a specific value or less. That an optically isotropic film excellent from the polyester can be produced economically, and the polyester is a retardation film, a polarizing plate protective film, a light diffusion sheet, a lens sheet, an antireflection film, an optical information recording medium, etc. The present invention has been found to satisfy the required characteristics of the optical member.

  That is, the present invention is a polyester film formed by melt extrusion using a polyester comprising a dicarboxylic acid unit and a diol unit, wherein 1 to 80 mol% of the diol unit is a diol unit having a cyclic acetal skeleton, The present invention relates to a polyester film having an in-plane retardation at a wavelength of 550 nm of 20 nm or less.

  Furthermore, the present invention provides a method for producing the polyester film, and an optical member such as a retardation film, a polarizing plate protective film, a light diffusion sheet, a lens sheet, an antireflection film, and an optical information recording medium, using the polyester film. About.

  The polyester film of the present invention can be easily formed into an optically isotropic film by an extrusion method having excellent economical efficiency. The polyester film of the present invention can be suitably used for optical films such as polarizing plates and retardation films, and the industrial significance of the present invention is great.

（一般式（１）において、Ｒ^１およびＲ^２は同一でも異なっていてもよく、それぞれ独立して、炭素数が１〜１０の脂肪族炭化水素基、炭素数が３〜１０の脂環式炭化水素基、及び炭素数が６〜１０の芳香族炭化水素基からなる群から選ばれる炭化水素基を表す）、または、一般式（２）：

（一般式（２）において、Ｒ^１は前記と同様であり、Ｒ^３は炭素数が１〜１０の脂肪族炭化水素基、炭素数が３〜１０の脂環式炭化水素基、及び炭素数が６〜１０の芳香族炭化水素基からなる群から選ばれる炭化水素基を表す）で表されるジオールに由来するジオール単位であることが好ましい。 The present invention is described in detail below.
[1] Polyester The polyester used in the present invention contains a diol unit having a cyclic acetal skeleton. The diol unit having a cyclic acetal skeleton has the general formula (1):

(In General Formula (1), R ¹ and R ² may be the same or different, and are each independently an aliphatic hydrocarbon group having 1 to 10 carbon atoms, or an alicyclic group having 3 to 10 carbon atoms. A hydrocarbon group and a hydrocarbon group selected from the group consisting of aromatic hydrocarbon groups having 6 to 10 carbon atoms), or general formula (2):

(In General Formula (2), R ¹ is the same as described above, and R ³ is an aliphatic hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, and a carbon number. Is a diol unit derived from a diol represented by the following formula: a hydrocarbon group selected from the group consisting of 6 to 10 aromatic hydrocarbon groups.

The R ² of the general formula (1) and R ¹ and formula (2) (1), a methylene group, an ethylene group, a propylene group, isopropylene group, structural isomers such as butylene group and isobutylene group, cyclohexylene Group, phenylene group and the like. Among these, a methylene group, an ethylene group, a propylene group, a butylene group, an isopropylene group, and an isobutylene group are preferable.

Examples of R ^{3 in the} general formula (2) include structural isomers such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, and an isobutyl group, a cyclohexyl group, and a phenyl group. Of these, a methyl group, an ethyl group, a propyl group, a butyl group, an isopropyl group, and an isobutyl group are preferable. Examples of the compounds of the general formulas (1) and (2) include 3,9-bis (1,1-dimethyl-2-hydroxyethyl) -2,4,8,10-tetraoxaspiro [5.5] undecane, 5-methylol-5-ethyl-2- (1,1-dimethyl-2-hydroxyethyl) -1,3-dioxane is preferred.

  Further, the diol unit other than the diol unit having a cyclic acetal skeleton is not particularly limited, but ethylene glycol, trimethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, Aliphatic diols such as diethylene glycol, propylene glycol and neopentyl glycol; 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 1,2-decahydronaphthalenediethanol, 1,3-decahydronaphthalenediethanol 1,4-decahydronaphthalene diethanol, 1,5-decahydronaphthalene diethanol, 1,6-decahydronaphthalene diethanol, 2,7-decahydronaphthalene diethanol, tetralin dimethanol, norbornane dimethyl Alicyclic diols such as diol, tricyclodecane dimethanol and pentacyclododecane dimethanol; polyether compounds such as polyethylene glycol, polypropylene glycol and polybutylene glycol; 2,2-bis (4-hydroxyphenyl) propane ( Bisphenol A), 2,2-bis (3,5-dibromo-4-hydroxyphenyl) propane (tetrabromobisphenol A), bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) octane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, 1,1-bis ( 3-tert-butyl-4-hydroxyphenyl) propane, Bis (hydroxyaryl) alkanes such as 2,2-bis (3-bromo-4-hydroxyphenyl) propane and 2,2-bis (3,5-dichloro-4-hydroxyphenylpropane); 1,1-bis (4-hydroxyphenyl) cyclopentane, 1,1-bis (4-hydroxyphenyl) cyclohexane (bisphenol Z), 1,1-bis (3,5-dibromo- Bis (hydroxyaryl) cycloalkanes such as 4-hydroxyphenyl) cyclohexane and 1,1-bis (3,5-dichloro-4-hydroxyphenyl) cyclohexane; 1,1-bis (4-hydroxyphenyl) -1- Biphenyl such as phenylethane and 1,1-bis (4-hydroxyphenyl) diphenylmethane (Hydroxyaryl) arylalkanes; dihydroxydiaryl ethers such as 4,4′-dihydroxydiphenyl ether and 4,4′-dihydroxy-3,3′-dimethyldiphenyl ether; 4,4′-dihydroxydiphenyl sulfide, 4,4 ′ Dihydroxy diaryl sulfides such as dihydroxy-3,3′-dimethyldiphenyl sulfide; dihydroxy diaryl sulfoxides such as 4,4′-dihydroxydiphenyl sulfoxide, 4,4′-dihydroxy-3,3′-dimethyldiphenyl sulfoxide; 4 , 4′-dihydroxydiphenylsulfone, 4,4′-dihydroxy-3,3′-dimethyldiphenylsulfone, and the like; hydroquinone, resorcin, 4,4′-dihydroxyl Biphenyl, 4,4'-dihydroxydiphenyl ether, 4,4'-aromatic dihydroxy compounds such dihydroxydiphenyl benzophenone; and diol units derived from alkylene oxide adducts of the aromatic dihydroxy compounds can be exemplified. Considering the mechanical strength of polyester, heat resistance, and the availability of diols, diol units derived from ethylene glycol, diethylene glycol, trimethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, etc. are preferred, Diol units derived from ethylene glycol are particularly preferred.

  The dicarboxylic acid unit of the polyester used in the present invention is not particularly limited, but succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, cyclohexanedicarboxylic acid. Acid, decalin dicarboxylic acid, norbornane dicarboxylic acid, tricyclodecane dicarboxylic acid, pentacyclododecanedicarboxylic acid, 3,9-bis (1,1-dimethyl-2-carboxyethyl) -2,4,8,10-tetraoxa Spiro [5.5] undecane, aliphatic dicarboxylic acids such as 5-carboxy-5-ethyl-2- (1,1-dimethyl-2-carboxyethyl) -1,3-dioxane; and terephthalic acid, isophthalic acid , Phthalic acid, 2-methylterephthalic acid, 1,3-naphthalene Derived from aromatic dicarboxylic acids such as rubonic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, tetralindicarboxylic acid Examples thereof include dicarboxylic acid units. In view of the mechanical strength of polyester, heat resistance, and the availability of dicarboxylic acid, dicarboxylic acid units derived from terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid are particularly preferred. In addition, the dicarboxylic acid structural unit of polyester may be comprised from 1 type, or may be comprised from 2 or more types.

  The polyester used in the present invention is a unit derived from a monoalcohol such as butyl alcohol, hexyl alcohol, octyl alcohol, trimethylolpropane, etc., in order to adjust melt viscoelasticity, molecular weight, etc. Units derived from trihydric or higher polyhydric alcohols such as glycerin, 1,3,5-pentanetriol, pentaerythritol, units derived from monocarboxylic acids such as benzoic acid, propionic acid, butyric acid, trimellitic acid, pyromellitic A unit derived from a trivalent or higher polyvalent carboxylic acid such as an acid, or a unit derived from an oxyacid such as glycolic acid, lactic acid, hydroxybutyric acid, 2-hydroxyisobutyric acid, or hydroxybenzoic acid may be included.

  In consideration of moldability, heat resistance, mechanical performance, hydrolysis resistance, economy, and the like, the polyester used in the present invention has a diol unit having a cyclic acetal skeleton having 3,9-bis (1,1-dimethyl-2). -Hydroxyethyl) -2,4,8,10-tetraoxaspiro [5.5] undecane, a diol unit other than a diol unit having a cyclic acetal skeleton is ethylene glycol, diethylene glycol, trimethylene glycol , 1,4-butanediol, and 1,4-cyclohexanedimethanol, a diol unit derived from at least one diol, wherein the dicarboxylic acid unit is terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid Di derived from at least one dicarboxylic acid selected from It is preferably a carboxylic acid unit.

  The proportion of the diol unit having a cyclic acetal skeleton is preferably 1 to 80 mol% of the total diol units. By including 1 mol% or more of diol units having a cyclic acetal skeleton, a decrease in the crystallinity of the polyester and an increase in the glass transition temperature are achieved simultaneously, and the transparency and heat resistance of the polyester film are improved. In addition, the polyester film has improved processability, such as suppression of whiskers during processing such as cutting and punching, and further reduced retardation, uneven retardation, and reduced thickness unevenness during melt extrusion. The optical performance is improved. When the ratio of the diol unit having a cyclic acetal skeleton exceeds 80 mol%, the crystallinity of the polyester may increase, and the transparency of the resulting polyester film may decrease. Therefore, the ratio of the diol unit having a cyclic acetal skeleton is 1 to 80 mol%, preferably 5 to 60 mol%, based on the heat resistance, transparency, processability, and optical performance of the polyester film. 15-60 mol% is more preferable.

  It is preferable that the glass transition temperature of the polyester used for this invention is 85-160 degreeC, More preferably, it is 90-150 degreeC. When the glass transition temperature is within the above range, heat resistance necessary for processing can be obtained. The glass transition temperature of the polyester varies depending on the type and proportion of the structural unit. For example, the diol unit having a cyclic acetal skeleton is 3,9-bis (1,1-dimethyl-2-hydroxyethyl) -2,4,8. , 10-tetraoxaspiro [5.5] undecane, a diol unit other than a diol unit having a cyclic acetal skeleton is a diol unit derived from ethylene glycol, and a dicarboxylic acid unit is terephthalic acid When the dicarboxylic acid unit is derived from 2,6-naphthalenedicarboxylic acid, a glass transition temperature in the above range is easily achieved.

  The intrinsic viscosity of the polyester used in the present invention can be appropriately selected according to the molding method and application. The intrinsic viscosity measured at 25 ° C. using a mixed solvent of phenol and 1,1,2,2-tetrachloroethane in a mass ratio of 6: 4 is preferably in the range of 0.4 to 1.5 dl / g, More preferably, it is 0.5-1.2 dl / g, More preferably, it is 0.6-1.0 dl / g. When the intrinsic viscosity is within this range, the polyester of the present invention has an excellent balance between moldability and mechanical performance.

Although the melt viscosity of the polyester used in the present invention can also be selected as appropriate, it is preferably in the range of 300 to 7000 Pa · s, more preferably in the range of 500 to 7000 when measured at a temperature of 240 ° C. and a shear rate of 100 sec ^−1. 5000 Pa · s. When the melt viscosity is within this range, the polyester in the present invention has an excellent balance between moldability and mechanical performance. The melt viscosity depends on the intrinsic viscosity of the polyester, but also on the structural unit. The more diol units having a cyclic acetal skeleton, the higher the melt viscosity.

Although the melt strength of the polyester used in the present invention can be appropriately selected, the melt strength measured under conditions of a shear rate of 100 sec ⁻¹ and a melt viscosity of 1400 Pa · s is preferably 0.5 to 20 cN, more preferably. Is 1-10 cN. When the melt strength is in the above range, a film can be stably obtained particularly when a film is formed by the melt extrusion method.

  The method for producing the polyester used in the present invention is not particularly limited, and conventionally known polyester production methods can be applied. Examples thereof include a melt polymerization method such as a transesterification method and a direct esterification method, and a solution polymerization method. Various known stabilizers such as transesterification catalysts, esterification catalysts, etherification inhibitors, heat stabilizers, light stabilizers, polymerization regulators, and the like used in the production can be used. Is appropriately selected according to the color tone, safety, thermal stability, weather resistance, dissolution property, and the like.

  The polyester used in the present invention includes a lubricant, an antioxidant, a light stabilizer, an ultraviolet absorber, a plasticizer, an extender, a matting agent, a drying regulator, an antistatic agent, an antisettling agent, a surfactant, and a flow improver. Various additives such as agents, drying oils, waxes, fillers, colorants, reinforcing agents, surface smoothing agents, leveling agents, curing reaction accelerators, thickeners, and molding aids can be added. These additives may be added at the polyester production stage or at the molding stage.

[2] Polyester film Examples of the method for forming a polyester film include a melt extrusion method and a casting method. The melt extrusion method is preferable from the viewpoint of the balance between economy and film performance.

  The melt extrusion method will be further described in detail. The polyester film of the present invention can be formed using a conventionally known method. Examples of the melt extrusion method include a T die casting method and an inflation method, but the T die casting method is desirable for obtaining an optically isotropic film. A generally used extruder may be used as an apparatus for melting the polyester, and a single-screw extruder or a multi-screw extruder may be used. The extruder may have one or more vents, with the vents being depressurized to gas, moisture from the molten resin. Low molecular substances and the like may be removed. Moreover, you may provide a metal-mesh filter and a sintered filter in the front-end | tip or downstream side of an extruder as needed. As the die, a T die, a coat hanger die, a fish tail die, a stack plate die, or the like can be used. When a multilayer film is used, a feed block method, a multi-manifold method, or a multi-manifold / feed block mixing method can be used.

  The extrusion temperature is preferably 200 to 300 ° C, more preferably 210 to 280 ° C, and particularly preferably 220 to 270 ° C. When extrusion temperature exists in the said range, it is excellent in balance with the optical isotropy of the film obtained, smoothness, transparency, a color tone, a mechanical physical property, etc. The air gap (distance until the molten film is discharged from the die and comes into contact with the cooling roll) is preferably 0.1 to 100 mm, more preferably 1 to 50 mm, still more preferably 3 to 30 mm. When the air gap is in the above range, the orientation relaxation unevenness due to the resin heat in the cooling process between the air gaps (the influence of the environment around the air gap and the difference in the cooling rate between the center and the edge of the film) is kept small. In addition, it is possible to suppress an abrupt increase in film thickness at the end of the film due to neck-in.

  A conventionally known method can be used as a method for cooling the molten resin extruded from the die. Generally, it can be cooled by a cooling roll. The number of cooling rolls may be one, or two or more depending on the amount of molten resin discharged and the take-off speed. A method for bringing the molten resin into close contact with the cooling roll is not particularly limited, but an air knife method, an electrostatic adhesion method, and a vacuum method are often used. Cooling may be performed while only one surface of the molten resin is in contact with the cooling roll, or both surfaces may be cooled by sandwiching the molten resin using a plurality of cooling rolls. Since the polyester used in the present invention is a substantially amorphous resin, the temperature of the cooling roll can be set widely. In order to obtain an optically isotropic film, the temperature of the cooling roll is preferably in the range of the glass transition temperature of the polyester −30 ° C. to the glass transition temperature of the polyester + 30 ° C. The take-off speed varies depending on the apparatus such as the extrusion amount of the molten resin and the die width, but is preferably 0.2 to 100 m / min, more preferably 0.5 to 95 m / min, and still more preferably 1 to 90 m / min. Minutes. When the take-up speed is in the above range, a polyester film having a target thickness can be obtained. In order to obtain an optically isotropic film, it is preferable to control the rotation speed of a cooling roll, a pinch roll, a take-up roll, etc. so as not to be substantially stretched.

In the film production by the melt extrusion method, the molding distortion generated in the film is caused by the balance between molecular orientation (mainly MD direction) due to flow residual stress and molecular orientation (mainly TD direction) due to thermal stress. The flow residual stress is generated when the polymer chain stretched by the flow stress is solidified in the middle of returning to the entangled state after the flow is stopped and the tensile stress generated in the polymer chain remains without being relaxed. . The thermal stress is generated when the molten resin undergoes thermal contraction (thermal strain) with a temperature change in the cooling process.
As a result of various studies, the present inventors have found that molecular orientation caused by the shearing stress of the molten polymer in the T-die (MD orientation is dominant), molecular orientation in the extrusion direction caused by take-up (MD direction). , Relaxation of orientation caused by resin heat (mainly MD direction orientation relaxation) in the process where the molten resin discharged from the T-die is gradually cooled between the air gaps, and heat shrinkage that occurs when the film is cooled on the cooling roll is cooled It has been found that molding strain can be reduced by canceling out the degree of orientation such as molecular orientation (dominant in the TD direction) due to residual stress generated by being restrained by a roll. That is, extrusion molding is performed under conditions of an extrusion temperature of 200 to 300 ° C., an air gap of 0.1 to 100 mm, a take-off speed of 0.2 to 100 m / min, and a cooling roll temperature is set to a glass transition temperature of polyester of −30 ° C. to that of polyester. By setting the glass transition temperature + 30 ° C., the molding strain can be extremely reduced.

  Next, the polyester film of the present invention will be described. Hereinafter, the in-plane retardation Re is defined as (nx−ny) × d. However, d is the film thickness (nm), nx, ny (nx> ny) is the main refractive index in the film plane. However, since the main refractive index depends on the wavelength, hereinafter, the in-plane retardation at the wavelength λ (nm) is expressed as Re [λ]. The in-plane retardation Re [550] of the polyester film of the present invention is preferably 20 nm or less, more preferably 15 nm or less, still more preferably 10 nm or less, and particularly preferably 5 nm or less (each including zero). Further, (nx−nz) × d (nz is the main refractive index in the normal direction of the film surface) at a wavelength of 550 nm is preferably 100 nm or less, more preferably 50 nm or less, particularly preferably 20 nm or less (each zero). Included). When it exists in the said range, the polyester film of this invention can be used suitably as an optical film for display apparatuses.

The thickness of the polyester film can be arbitrarily set depending on the method of use, application, and required performance, but is generally preferably 1 to 500 μm, more preferably 5 to 300 μm, and still more preferably 10 to 200 μm. When it exists in the said range, the polyester film of this invention is excellent in workability, mechanical strength, and an optical physical property.
The thickness unevenness of the polyester film is preferably in the range of 0.9T to 1.1T, where T is the average thickness. More preferably, it is 0.93T-1.07T, More preferably, it is 0.97T-1.03T. The method for reducing the thickness unevenness in the extrusion direction (MD) is not particularly limited, but a vent is provided in the extruder, a gear pump is provided between the extruder and the die to make the resin discharge amount constant, or a cooling roll For example, a servo motor or a planetary gear is used for driving the motor to make the driving constant. A method for reducing the thickness variation in the width direction (TD) perpendicular to the extrusion direction is not particularly limited, but a method of adjusting the lip gap of the die by a thermal displacement type, a servo motor type, a pneumatic type, a piezoelectric element type, or the like. Can be used.
When there is a demand for polyester film with fewer defects or fish eyes, there is no particular limitation, but it is possible to reduce defects and fish eyes by removing foreign substances such as gel using a wire mesh filter or sintered metal filter. it can. These filters are provided between the extruder and the die, and produce a film while removing foreign substances. Moreover, you may clean the environment which forms a film, and may affix a protective film on a film.

  The total light transmittance of the polyester film of the present invention is preferably 85% or more, and more preferably 90% or more. Moreover, it is preferable that a haze is 3% or less, More preferably, it is 2% or less. When these values are in the above range, the performance is sufficient for use as an optical film.

  The polyester film of the present invention can be used as a film for various optical members and electronics members as it is or after being subjected to conventionally known processing and processing. Examples of processing and processing include adhesives, pressure-sensitive adhesives, mold release agents, antistatic agents, diffusing agents, cured resin coatings, prisms and lens formation and pasting, etching processes, vapor deposition, sputtering, stretching, embossing, etc. Examples include processing. Examples of the optical member include a polarizing plate, a lens sheet, an antireflection film, an antistatic film, a retardation film, an optical information recording medium, a λ / 4 plate, a λ / 2 plate, a touch panel, a viewing angle compensation film, an antiglare film, Examples include a light diffusing film, a reflective film, a lamp reflector, a plastic film substrate, a transparent conductive film, a protective film, and a pellicle.

[3] Retardation film The retardation film of the present invention comprises a film obtained by using the polyester film as a raw film and stretching it (sometimes referred to as a stretched polyester film or a stretched raw film). Has a layer. By using the polyester film, in-plane retardation of the film layer and / or Nz coefficient ((nx-nz) / (nx-ny), where nx, ny and nz are the same as those described above) The range can be controlled. Since the Nz coefficient depends on the wavelength, hereinafter, the Nz coefficient at the wavelength λ (nm) will be expressed as Nz [λ].

  The in-plane retardation Re [550] at a wavelength of 550 nm of the polyester raw film is preferably 20 nm or less, more preferably 15 nm or less, still more preferably 10 nm or less, and particularly preferably 5 nm or less. When in the above range, the in-plane retardation and / or the Nz coefficient can be controlled to an arbitrary numerical range by stretching the polyester raw film.

  The thickness of the polyester raw film can be arbitrarily set according to the required specifications. The thickness of the film layer is preferably as thin as possible from the viewpoint of reducing the weight of the liquid crystal display device, but the thickness of the polyester raw film for producing the retardation film is preferably 20 to 200 μm because of restrictions on the melt extruder. .

  The total light transmittance of the polyester raw film is preferably 85% or more, more preferably 90% or more. Moreover, it is preferable that a haze is 3% or less, More preferably, it is 2% or less. When these values are in the above range, the performance is sufficient as an original film for producing a retardation film.

Next, the stretching method for the polyester raw film will be described in detail. The original film can be stretched by uniaxial stretching, sequential biaxial stretching, or simultaneous biaxial stretching. Further, as described in Japanese Patent No. 2818983, a shrinkable film is adhered to one or both sides of the original film during stretching to form a laminate, and the laminate is heated and stretched to form an original film. By applying a contraction force in a direction orthogonal to the stretching direction, a film layer in which polymer chains oriented in the stretching direction and the thickness direction are mixed can be provided.
In the case of uniaxial stretching, a film layer having Nz [550] of about 1 can be obtained. In the case of sequential and simultaneous biaxial stretching, a film layer having Nz [550] of 1 to ∞ can be obtained. For example, for a retardation film suitably used for STN mode liquid crystal, a film layer obtained by uniaxial stretching and having Nz [550] of about 1 and in-plane retardation Re [550] of 100 to 500 nm is used. It is done. In addition, a retardation film suitably used for VA (Vertical Alignment) mode liquid crystal includes Nz [550] exceeding 1 to ∞, obtained by sequential or simultaneous biaxial stretching, and an in-plane letter. A film layer having a foundation Re [550] of 0 to 200 nm is used. The circularly polarizing plate used for the reflective / semi-transmissive liquid crystal and the circularly polarizing plate for blocking the reflected light on the internal ITO glass substrate of the touch panel must be a broadband λ / 4 plate. By laminating the λ / 2 plate and the λ / 4 plate at a wavelength of 550 nm with the respective optical axes inclined, a wide-band circularly polarizing plate can be obtained (see JP-A-10-068816). Such λ / 2 plates and λ / 4 plates can be manufactured by uniaxial stretching.
The draw ratio is preferably more than 1 and not more than 2 times, more preferably more than 1 and not more than 1.5 times, more preferably 1 in each of the MD direction and / or the TD direction so as not to cause the Boeing phenomenon. It is 1.2 times or less.
The stretching temperature is in the range from the glass transition temperature to the melting point of the polyester. The higher the stretching temperature, the lower the retardation at the same stretch ratio. Therefore, it is preferable to control the stretching to a desired retardation by changing the stretching temperature at a low stretching ratio that does not cause the Boeing phenomenon. In the case of simultaneous biaxial stretching, the temperature cannot be changed depending on the stretching direction, so that a desired retardation can be obtained by changing the stretching ratio depending on the stretching direction.

  In addition to the retardation film consisting of only the film layer, a retardation film having a multilayer structure in which two or more film layers are laminated, and an optically isotropic protective layer laminated on at least one surface of the film layer It may take the form of a film, a retardation film formed by integrating a polarizing plate on the film layer, a retardation film in which a peelable sheet is laminated on at least one surface of the film layer via an adhesive layer or an adhesive layer, and the like. it can.

The retardation film having a multilayer structure in which the film layers are laminated will be described in detail. As described above, a film layer having a retardation of any size can be obtained by stretching the polyester raw film. By laminating two or more film layers using a highly transparent adhesive or pressure-sensitive adhesive, a retardation film that can be suitably used for phase compensation of an STN liquid crystal cell is obtained.
Adhesives or pressure-sensitive adhesives include: polyvinyl alcohol polymers; acrylic polymers; silicone polymers; polyisocyanates; polyolefins; polyesters; polyethers; vinyl chloride / vinyl acetate copolymers; An adhesive or pressure-sensitive adhesive based on a suitable polymer such as a modified product is used. In order to improve the durability and adhesiveness of the adhesive or pressure-sensitive adhesive, other polymers, plasticizers, heat stabilizers, ultraviolet absorbers, crosslinking agents, fillers, etc. within the range not impairing the effects of the present invention. A known additive can be contained. As a method of applying the adhesive or pressure-sensitive adhesive on the film layer, a conventionally known method such as a coater head can be used, and the method is particularly limited as long as a uniform adhesive layer or pressure-sensitive adhesive layer is formed. Is not to be done. Moreover, it consists of the above components, and is a commercially available highly transparent adhesive transfer tape without a substrate (with a release film pasted on both sides of a film-like adhesive layer or pressure-sensitive adhesive layer, such as Pressure manufactured by Pola Techno Co., Ltd. The adhesive layer or the pressure-sensitive adhesive layer can also be configured using Senstive Adhesive AD-20, a substrate-less highly transparent adhesive transfer tape 8141 manufactured by Sumitomo 3M Limited, and the like. The thickness of the adhesive layer and the pressure-sensitive adhesive layer is preferably 5 to 50 μm.
As described above, a film layer having a retardation of any size can be obtained by stretching the polyester raw film of the present invention. The film layer can be laminated at an arbitrary angle. Today, liquid crystal has various modes. The thus obtained retardation film having a multilayer structure of the present invention can be applied not only to STN liquid crystal cells but also to any liquid crystal cell. .

  Next, a retardation film in which an optically isotropic protective layer is laminated on at least one surface of the film layer will be described in detail. Since the retardation of the film layer is expressed by the orientation of the polyester polymer chain constituting the film layer, if the film is damaged by scratches or the like due to external physical force during transportation or display assembly process, The retardation may change. In order to prevent this, an optically isotropic protective layer (thickness: preferably 5 to 50 μm) is laminated on at least one surface of the film layer. Examples of the optically isotropic protective layer include, but are not limited to, a polyester raw film and a polycarbonate film used in the present invention. The film layer and the optically isotropic protective layer are bonded by applying an adhesive or a pressure-sensitive adhesive on the film layer, and further pressing the optically isotropic protective layer thereon using a roller. Can be implemented. The adhesive layer or the pressure-sensitive adhesive layer can be formed in the same manner as described above.

Next, a retardation film formed by laminating and integrating a polarizing plate on the film layer will be described in detail.
A polyvinyl alcohol film is immersed in an aqueous solution containing iodine and potassium iodide, then immersed in an aqueous solution containing boric acid and potassium iodide, and uniaxially stretched to produce a polarizing plate (thickness: preferably 50 to 200 μm). Next, a triacetyl cellulose (TAC) sheet (thickness: preferably 40 to 80 μm) is laminated on one surface of the polarizing plate via an adhesive or an adhesive, and the film layer is formed on the other surface of the polarizing plate. Are laminated via an adhesive or a pressure-sensitive adhesive. Thus, the said film layer can be integrated with a polarizing plate as a protective layer of a polarizing plate. The adhesive layer or the pressure-sensitive adhesive layer can be formed in the same manner as described above.
When the film layer is used as a protective layer for a polarizing plate, the moisture permeability at 40 ° C. and 90% RH of the film layer is preferably 5 to 500 g / (m ² · 24 hr), more preferably 8 to 400 g. / (M ² · 24 hr), more preferably 10 to 300 g / (m ² · 24 hr). When the moisture permeability at 40 ° C. and 90% RH exceeds 500 g / (m ² · 24 hr), external moisture that has passed through the polarizing plate protective film permeates into the polarizing plate under conditions of high temperature and humidity, and serves as a polarizing plate. There is a possibility that the performance is lowered or the polarizing plate is warped. In addition, it is necessary to appropriately evaporate water taken into the polyvinyl alcohol film when immersed in an aqueous solution of iodine and potassium iodide through the polarizing plate protective layer, and the polarizing plate protective layer is required to have appropriate moisture permeability. .

  Next, the retardation film in which a peelable sheet is laminated on at least one surface of the film layer via an adhesive layer or an adhesive layer will be described in detail. A retardation film in which a peelable sheet (thickness: preferably 10 to 100 μm) is laminated on the film layer via an adhesive or a pressure-sensitive adhesive is easily attached to a polarizing plate or a glass substrate by peeling off the peelable sheet. You can match. The adhesive layer or the pressure-sensitive adhesive layer can be formed in the same manner as described above. As such a laminated structure of retardation film, film layer / adhesive layer or pressure-sensitive adhesive layer / release sheet, polarizing plate / adhesive layer or pressure-sensitive adhesive layer / film layer / adhesive layer or pressure-sensitive adhesive layer / release sheet Etc.

[4] Polarizing plate The polarizing plate of the present invention includes a film layer and a polarizing film made of the polyester film (unstretched).

40 ° C. of the polyester film, the moisture permeability at 90% RH is preferably ^{5~500g / (m 2 · 24hr)} , more preferably ^{8~400g / (m 2 · 24hr)} , more preferably 10 to 300 g / (m ² · 24 hr). When the water vapor permeability exceeds 500 g / (m ² · 24 hr), the external moisture that has passed through the film layer permeates the polarizing film under high-temperature and high-humidity conditions, and the performance as a polarizing plate deteriorates or warps the polarizing plate. May occur. In addition, a water-based adhesive is often used for bonding between the polarizing film and the film layer. If the moisture permeability is too small, drying of the water-based adhesive becomes slow, and there is a problem that it takes time to develop the adhesive strength. .

  The in-plane retardation Re [550] at a wavelength of 550 nm of the polyester film is preferably 20 nm or less, more preferably 15 nm or less, still more preferably 10 nm or less, and particularly preferably 5 nm or less. When the above range is exceeded, the image quality of the liquid crystal display device is significantly lowered. That is, there are problems such as a decrease in contrast, such as partial color fading, and distortion of an image.

  The thickness of the polyester film can be arbitrarily set according to the required specifications. The thickness of the polyester film is preferably 10 to 200 μm, more preferably 20 to 100 μm, still more preferably 30 to 80 μm. When the above range is exceeded, it is difficult to reduce the thickness and size of the liquid crystal display device.

  Furthermore, the difference between the maximum and minimum film thicknesses of the polyester film is preferably 5% or less of the average film thickness, more preferably 3% or less, and even more preferably 2% or less. Exceeding the above range, if the film thickness unevenness is large, the liquid crystal display device has a bad image quality and the image is distorted.

  The total light transmittance of the polyester film is preferably 85% or more, more preferably 90% or more. Moreover, it is preferable that a haze is 2% or less, More preferably, it is 1% or less. When the above range is exceeded, the transparency is remarkably lowered and the sharpness of the liquid crystal display device screen is impaired, which is not practical.

  The film layer is laminated on one side or both sides of the polarizing film with an appropriate adhesive or pressure-sensitive adhesive as necessary. The polarizing film is not particularly limited as long as it changes incident natural light into linearly polarized light. In particular, those excellent in light transmittance and degree of polarization are preferred. For example, it can be obtained by doping a film made of polyvinyl alcohol or partially formalized polyvinyl alcohol with a dichroic substance such as iodine or a dichroic dye, and then stretching. As the adhesive and the pressure-sensitive adhesive, those described above can be used, and the adhesive layer and the pressure-sensitive adhesive layer can be formed in the same manner as described above. The adhesive and the pressure-sensitive adhesive are preferably acrylic from the viewpoint of heat resistance and transparency, and more preferably an adhesive or pressure-sensitive adhesive made of an acrylate copolymer.

[5] Lens Sheet The lens sheet of the present invention includes a film layer made of the polyester film (unstretched) and an optical element formed on at least one surface of the film layer.

  The thickness of the polyester film can be arbitrarily set according to the required specifications. Generally, the thickness is 50 to 800 μm, preferably 80 μm or more from the viewpoint of handleability, and preferably 300 μm or less from the viewpoint of thinning the backlight.

  The total light transmittance of the polyester film is preferably 85% or more, and more preferably 90% or more. Moreover, it is preferable that a haze is 3% or less, More preferably, it is 2% or less. When these values are in the above range, the performance is sufficient for use as a transparent base material for a lens sheet.

  In order to improve the adhesion with the active energy ray-curable resin or thermosetting resin for forming the optical element, the surface of the film layer on which the optical element is to be formed is subjected to an adhesion improving treatment such as an anchor coat treatment. Is preferred.

As a first aspect of the optical element, a plurality of prism rows having a triangular cross section formed in parallel on one side or both sides of a film layer can be mentioned. In addition, when forming a some prism row | line on both surfaces of a film layer, it is preferable to arrange | position so that the some prism row | line | column of one surface may be orthogonally crossed with the several prism row | line | column of the other surface. The apex angle of the prism row is appropriately selected according to the directivity characteristic of the light emitted from the light guide so that the front luminance can be sufficiently improved, and is generally preferably in the range of 50 to 150 °. When arranging a plurality of prism rows so as to be on the light guide side in the backlight of the liquid crystal display device, the apex angle of the prism rows is preferably in the range of about 50 to 75 °, particularly preferably 55 to 70 °. . In the case where the plurality of prism rows are arranged on the liquid crystal panel side, the angle is preferably 80 to 100 °, particularly preferably 90 to 100 °. The pitch of the plurality of prism rows is preferably 20 to 300 μm, particularly preferably 20 to 120 μm. The refractive index of the prism row is preferably 1.45 or more, more preferably 1.50 or more, and further preferably 1.55 or more. A lens sheet having such an optical element is used as a prism sheet (see FIG. 3).
As a second aspect of the optical element, there is a lenticular lens portion in which a plurality of cylindrical lens rows are formed in parallel. A lens sheet having such an optical element is used as a lenticular lens sheet, and is arranged so that cylindrical lenses are arranged in the longitudinal direction of the liquid crystal display device. Thereby, the backlight light can be further diffused in the left-right direction of the display, and the viewing angle in the left-right direction of the display can be controlled. When the focal length of the cylindrical lens is long, the viewing angle in the left-right direction becomes small, and when the focal length is short, it is enlarged.
As a third aspect of the optical element, there is a Fresnel lens portion formed in a concentric Fresnel lens shape. A lens sheet having such an optical element is used as a Fresnel lens sheet, and is used for limiting the viewing angle of the display and improving the luminance.
Further, the Fresnel lens sheet and the lenticular lens sheet or prism sheet may be integrated on the front and back sides. For example, it is produced by forming each optical element on both surfaces of a film layer.

  The optical element is formed of an active energy ray curable resin or a thermosetting resin. Or you may shape the film layer surface directly to an optical element. When the active energy ray curable resin is formed, for example, the active energy ray curable resin is injected into a mold having a predetermined optical element pattern, the film layer is overlaid thereon, and the active energy ray is then passed through the film layer. An optical element is formed by curing the curable resin by irradiation. From the viewpoint of scratch resistance, handleability and productivity of the optical element, it is preferable to use an active energy ray-curable resin.

  The active energy ray curable resin is not particularly limited as long as it is a resin curable with active energy rays such as ultraviolet rays and electron beams. Such an active energy ray-curable resin preferably has (A) a monomer or oligomer capable of radical polymerization, and (B) an active energy ray-sensitive catalyst as a main component, and further includes (C) a heat-sensitive catalyst. May be.

The radically polymerizable monomer or oligomer (A) can be used alone or in combination of two or more, but it is preferable to use in combination of two or more. The component (A) determines the optical performance of the optical element, and is appropriately selected according to the performance required for the lens sheet.
Examples of the component (A) include aliphatic mono (meth) acrylate, alicyclic mono (meth) acrylate, aromatic mono (meth) acrylate, aromatic di (meth) acrylate, and alicyclic di (meth) acrylate. (Meth) acrylates such as aliphatic di (meth) acrylates and polyfunctional (meth) acrylates; (meth) acrylates such as epoxy poly (meth) acrylates, urethane poly (meth) acrylates, and polyester poly (meth) acrylates Resins are preferred from the standpoint of their optical properties.

  The active energy ray-sensitive catalyst (B) is preferably a compound that generates a radical source mainly in response to ultraviolet rays having a wavelength of 200 to 400 nm, such as benzophenone, benzoin isopropyl ether, methylphenylglyoxylate, 1-hydroxycyclohexylphenyl. Examples include carbonyl compounds such as ketone and benzyldimethyl ketal; sulfur compounds; acylphosphine oxides such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide and the like. These can be used alone or in combination of two or more.

  The amount of the component (B) used is preferably 0.005 to 5 parts by weight, more preferably 0.02 to 2 parts by weight with respect to 100 parts by weight of the active energy ray-curable resin (A). If it is less than 0.005 parts by weight, the curability may not be sufficient, and if it exceeds 5 parts by weight, the deep part curability may be lowered or the color may be easily colored.

  As the heat-sensitive catalyst (C), an organic peroxide or an azo compound is preferable. Organic peroxides include benzoyl peroxide, octanoyl peroxide, diisopropyl peroxypercarbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, t-butylperoxyisobutyrate, and t-butylperoxy. -2-ethylhexanoate and the like. As the azo compound, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 2,2 ′ -Azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis (2-methylbutyronitrile) and the like. The amount of component (C) used is preferably 0 to 5 parts by weight, more preferably 0.005 to 2 parts by weight, based on 100 parts by weight of the active energy ray-curable resin (A). If the amount exceeds 5 parts by weight, the mechanical strength of the optical element may be reduced or coloring may be easily caused.

  If necessary, additives such as antioxidants, ultraviolet absorbers, yellowing inhibitors, bluing agents, pigments, diffusing agents, and fluorescent brightening agents may be added to the optical element.

  The lens sheet of the present invention obtained as described above has good dimensional stability at high temperatures. The dimensional change before and after being left in an 80 ° C environment for 30 minutes is 0%, and the dimensional change before and after being left in a 100 ° C environment for 30 minutes is 0%. 0%.

[6] Light Diffusion Film The light diffusion film of the present invention includes a film layer made of the polyester film (unstretched) and a light diffusion layer made of diffusion beads and a binder resin.

  The thickness of the polyester film can be arbitrarily set according to the required specifications. The thickness of the polyester film usually used is 10 to 150 μm. Considering the particle diameter of the diffusion beads for diffusing light of 1 to 50 μm and the thickness of the coating binder of about 10 to 20 μm, the thickness is preferably 40 to 100 μm.

  The total light transmittance of the polyester film is preferably 85% or more, more preferably 90% or more. Moreover, it is preferable that a haze is 2% or less, More preferably, it is 1% or less. If the haze is larger than this value, the incident light is diffused inside the film and the amount of emitted light is reduced, so that the light transmittance is reduced. Also, the lower the haze, the better. Moreover, the total thickness becomes like this. Preferably it is 35-130 micrometers, More preferably, it is 70-125 micrometers. If the total thickness is less than 35 μm, it is not preferable because it is difficult to handle when used as a light diffusion plate. On the other hand, if the total thickness is greater than 130 μm, the amount of light absorption increases and the light transmittance decreases, which is not preferable. When these values are in the appropriate range, sufficient performance is obtained.

Next, the structure and manufacturing method of the light-diffusion film of this invention are demonstrated.
As shown in FIG. 4, the light diffusion film of the present invention comprises a film layer made of the polyester film, and a light diffusion layer made of diffusion beads and a binder resin for fixing the diffusion beads. The light diffusion layer is formed by dispersing diffusion beads and the like in a binder resin.
Examples of the diffusion beads include known beads such as beads made of at least one substance selected from the group consisting of glass, acrylic resin, urethane resin, vinyl chloride resin, and polycarbonate resin. The average particle size of the beads is preferably 1 to 50 μm. The diffusion bead content is preferably 20 to 90% by weight of the light diffusion layer. If it is less than 20% by weight, light is not diffused uniformly, and if it exceeds 90% by weight, adhesion cannot be obtained.
The light diffusion layer can be provided by applying a binder resin and diffusion beads to the film layer by roller coating, roll coater, spray coating, electrostatic coating, or the like. The thickness of the light diffusion layer is preferably 0.5 to 50 μm, more preferably 1 to 20 μm, still more preferably 1.5 to 10 μm, and particularly preferably 2 to 6 μm.

  The binder resin is made of one or more resins selected from the group consisting of ionizing radiation curable resins, thermosetting resins, electron beam curable resins, and ultraviolet curable resins, and has a saturated hydrocarbon or polyether as the main chain. A polymer is preferable, and a polymer having a saturated hydrocarbon as a main chain is more preferable. The binder resin is preferably crosslinked. The polymer having a saturated hydrocarbon as the main chain is preferably an ethylenically unsaturated monomer polymer. In order to obtain a crosslinked binder resin, it is preferable to use a monomer having two or more ethylenically unsaturated groups.

  Examples of the monomer having two or more ethylenically unsaturated groups include esters of polyhydric alcohol and (meth) acrylic acid (for example, ethylene glycol di (meth) acrylate, 1,4-dichlorohexane diacrylate, pentaerythritol tetra). (Meth) acrylate), pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, Dipentaerythritol hexa (meth) acrylate, 1,3,5-cyclohexanetriol trimethacrylate, polyurethane polyacrylate, polyester polyacrylate), vinylbenzene derivative (Eg 1,4-divinylbenzene, 4-vinylbenzoic acid-2-acryloylethyl ester, 1,4-divinylcyclohexanone), vinyl sulfone (eg divinyl sulfone), acrylamide (eg methylene bisacrylamide) and methacrylamide Is mentioned. Among these, pentafunctional or higher acrylates such as dipentaerythritol hexaacrylate are preferable from the viewpoint of film hardness, that is, scratch resistance. A mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate is commercially available and is particularly preferably used.

  These monomers having two or more ethylenically unsaturated groups can be cured by a polymerization reaction by ionizing radiation or heat after being dissolved in a solvent, applied and dried together with various polymerization initiators and other additives.

  Instead of the monomer having two or more ethylenically unsaturated groups, an ethylenically unsaturated monomer having a crosslinkable functional group may be used to form a binder resin having a crosslinkable functional group. You may use the monomer which has a 2 or more ethylenically unsaturated group which has a crosslinkable functional group. Examples of crosslinkable functional groups include isocyanate groups, epoxy groups, aziridine groups, oxazoline groups, aldehyde groups, carbonyl groups, hydrazine groups, carboxyl groups, methylol groups, and active methylene groups. As the crosslinkable functional group, a crosslinkable functional group that decomposes and exhibits crosslinkability, such as a block isocyanate group, may be used. That is, in the present invention, the crosslinkable functional group may not exhibit crosslinkability itself, but may exhibit crosslinkability after decomposition. The binder resin having these crosslinkable functional groups forms a crosslinked structure by heating after coating. Using ethylenically unsaturated monomer, mixing vinyl sulfonic acid, acid anhydride, cyanoacrylate derivative, melamine, etherified methylol, ester, urethane, tetramethoxysilane and other metal alkoxides as monomers for introducing cross-linked structure Also good.

In order to increase the refractive index of the binder resin itself, a copolymer copolymer of a monomer having a high refractive index and / or metal oxide ultrafine particles having a high refractive index may be added to the binder resin. Examples of the monomer having a high refractive index include bis (4-methacryloylthiophenyl) sulfide, vinyl naphthalene, vinyl phenyl sulfide, 4-methacryloxyphenyl-4′-methoxyphenyl thioether, and the like. As the metal oxide ultrafine particles having a high refractive index, fine particles having a particle diameter of 100 nm or less, preferably 50 nm or less, comprising at least one oxide selected from zirconium, titanium, aluminum, indium, zinc, tin and antimony. Can be mentioned. Examples of the oxide include ZrO ₂ , TiO ₂ , Al ₂ O ₃ , In ₂ O ₃ , ZnO, SnO ₂ , Sb ₂ O ₃ , ITO, and the like. Among these, ZrO ₂ is particularly preferably used. The addition amount of the metal oxide ultrafine particles is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, based on the total mass of the binder resin.

  Examples of the method for curing the monomer used for the binder resin as described above include irradiation with an electron beam or ultraviolet rays. For example, in the case of electron beam curing, 50 to 1000 KeV emitted from various electron beam accelerators such as a Cockrowalton type, a bandegraph type, a resonant transformation type, an insulating core transformer type, a linear type, a dynamitron type, and a high frequency type. Preferably, an electron beam having an energy of 100 to 300 KeV is used, and in the case of ultraviolet curing, ultraviolet rays emitted from light such as an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc, a xenon arc, a metal halide lamp, etc. are used. it can.

The light diffusion film of the present invention has good dimensional stability at high temperatures. Specifically, the dimensional change before and after being left for 30 minutes in an environment of 80 ° C. is 0%, and further, the dimensional change before and after being left for 30 minutes in an environment of 100 ° C. is 0%, especially left in an environment of 120 ° C. for 30 minutes. The dimensional change before and after being performed is 0%. Therefore, even if the backlight of the liquid crystal display measure is replaced with the LED from the current fluorescent tube, the dimensional change due to the generated heat is very small.
At least one of the surfaces of the film layer may be matted. In addition, a light diffusing film can also be produced by kneading and dispersing acrylic beads in polyester and extruding them when performing melt T-die extrusion.

[7] Antireflection film The antireflection film of the present invention comprises a film layer made of the polyester film (unstretched) and an antireflection layer formed on at least one surface of the film layer.

  The in-plane retardation Re [550] at a wavelength of 550 nm of the polyester film is preferably 20 nm or less, more preferably 15 nm or less, still more preferably 10 nm or less, and particularly preferably 5 nm or less. When it exists in the said range, the antireflection film excellent in image visibility can be produced.

  The thickness of the polyester film can be arbitrarily set according to the required specifications. Generally, the thickness is 50 to 400 μm, preferably 80 μm or more from the viewpoint of handleability, and preferably 300 μm or less from the viewpoint of thinning the backlight.

  The total light transmittance of the polyester film is preferably 85% or more, and more preferably 90% or more. Moreover, it is preferable that a haze is 3% or less, More preferably, it is 2% or less. When these values are in the above range, sufficient performance is obtained.

  The antireflection layer is manufactured by a known method using a known material. The antireflection layer is formed on the film layer or on the hard coat laminated on the film layer. The antireflection layer may be a single layer or a multilayer. An antireflection film having a multilayer antireflection layer has a very low reflectance and is effective for a portable terminal without a backlight.

  As the material for the antireflection layer, metal fluoride such as magnesium fluoride, fluorine-containing organic compound, silica, indium oxide-tin oxide (ITO), and the like are used, but not limited thereto.

  The antireflection layer is not limited, but is a dry coating method, for example, a vacuum vapor deposition method, a physical vapor deposition method such as sputtering, and a chemical vapor deposition method such as CVD, or a wet coat in which a solution is applied and dried. Form by the method. Since an antireflection film having a low reflectance is obtained, vacuum deposition or sputtering is preferred. In vacuum deposition, there are a resistance heating method, an electron beam heating method, a high frequency induction heating method, and a laser beam heating method as methods for evaporating the antireflection layer material, and electron beam heating is generally used. The thickness of the antireflection layer is preferably 50 nm to 150 nm in the case of a single layer and 100 nm to 500 nm in the case of a multilayer. Within this range, the reflectance is 1% or less.

  A hard coat layer having a thickness of 1 to 15 μm may be laminated between the film layer and the antireflection layer (FIG. 5). The material for the hard coat layer is not particularly limited, and inorganic and oxides such as silica, alumina and polyorganosiloxane, and transparent and hard resins such as polyfunctional acrylic resins are used. As a method for forming the hard coat layer, dry coating such as vacuum deposition and wet coating such as solution coating can be used. In order to develop sufficient hardness (pencil hardness of 2H or more), a thickness of 1 μm or more is often required, so wet coating is often used. In the case of wet coating, it is preferable that an active ray curable resin, for example, an ester of an acrylic compound such as methacrylic acid and a polyfunctional alcohol is irradiated with active rays and crosslinked to form a hard coat.

[8] Optical information recording medium The optical information recording medium of the present invention comprises a film layer made of the polyester film (unstretched), a transparent adhesive layer, a recording layer, a reflective layer, and a substrate, which are sequentially laminated.

  The in-plane retardation Re [405] at a wavelength of 405 nm of the polyester film is preferably 20 nm or less, more preferably 15 nm or less, still more preferably 10 nm or less, and particularly preferably 5 nm or less. When it is in the above range, it is suitable as a protective layer for a Blu-ray disc, and a Blu-ray disc capable of stable recording and reproduction can be manufactured.

  The thickness of each layer can be arbitrarily set according to the required specifications. The thickness of the protective layer (transparent adhesive layer and optical film) is preferably 98 to 102 μm. If it is within this thickness range, the tracking servo works without any problem and no focus error occurs. The thickness of the transparent adhesive layer is preferably 10 to 30 μm, and the thickness of the film layer is preferably 70 to 90 μm.

  The total light transmittance of the polyester film is preferably 85% or more, more preferably 90% or more. Moreover, it is preferable that a haze is 3% or less, More preferably, it is 2% or less. When these values are in the above range, the optical isotropic film constituting the protective layer of the Blu-ray disc has sufficient performance.

  A configuration example of the optical information recording medium of the present invention is shown in FIG. As shown in FIG. 6, the thickness of the base material is approximately 1100 μm. The material of the base material is not particularly limited as long as the guide groove having a pitch of 0.32 μm can be transferred by injection molding. Generally used is a polycarbonate resin which is inexpensive. A reflective layer and a recording layer are formed on a substrate by a known thin film forming technique such as an on-plating method or a sputtering method (see Japanese Patent Application Laid-Open Nos. 2005-216365 and 2005-158253). A polyester film is stuck on the recording layer thus formed via a transparent adhesive or a pressure-sensitive adhesive. As the transparent adhesive and the pressure-sensitive adhesive, those described in “[3] Retardation film” can be used, and an acrylic transparent adhesive or pressure-sensitive adhesive is preferable. A transparent adhesive or pressure-sensitive adhesive made of an acrylate copolymer is used. Is more preferable.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited by these examples.

The evaluation method of the polyester used in the Examples is as follows.
(1) Ratio of diol units having a cyclic acetal skeleton
^It computed from the < ¹ > H-NMR measurement result. The measuring apparatus used JNM-AL400 by JEOL Co., Ltd., and measured it at 400 MHz. Deuterated chloroform was used as the solvent.

(2) Glass transition temperature Using a DSC / TA-50WS manufactured by Shimadzu Corporation, about 10 mg of a sample was put in an aluminum non-sealed container and measured at a temperature rising rate of 20 ° C./min in a nitrogen gas (30 ml / min) stream. The temperature at the point where the DSC curve obtained was changed by ½ of the baseline difference before and after the transition was taken as the glass transition temperature.

(3) Intrinsic viscosity 0.5 g of polyester is dissolved in 120 g of a mixed solvent of phenol and 1,1,2,2-tetrachloroethane (mass ratio = 6: 4) by heating, filtered, cooled to 25 ° C., and a measurement sample. Was prepared. The measurement was performed at a temperature of 25 ° C. using a capillary viscometer automatic measuring device SS-300-L1 manufactured by Shibayama Scientific Machinery Co., Ltd.

(4) Melt viscosity Measured using Toyo Seiki Seisakusho, trade name: Capillograph 1C. The diameter of the capillary was 1 mm, the length was 10 mm, and the measurement conditions were a measurement temperature of 240 ° C., a preheating time of 3 minutes, and a shear rate of 100 sec ⁻¹ .

The evaluation method of the film of an Example and a comparative example is as follows.
(5) Thickness Measured using a digital micrometer M-30 manufactured by Sony Magnescale Co., Ltd.

(6) Retardation Incidence angle dependence of retardation around the slow axis was measured using a spectroscopic ellipsometer manufactured by JASCO Corporation, trade name: M-220. Retardation with an incident angle of 0 ° was designated as in-plane retardation Re. Since the size of the in-plane retardation Re depends on the measurement wavelength even in the same sample, the in-plane retardation when the measurement wavelength is λ (nm) is expressed as Re [λ].

(7) Total light transmittance, haze Measured according to JIS-K-7105, ASTM D1003. The film was conditioned for 48 hours and then measured in an atmosphere of 23 ° C. and 50% relative humidity. The measuring apparatus used is a fog value measuring apparatus (model: COH-300A) manufactured by Nippon Denshoku Industries Co., Ltd.

(8) Moisture permeability Using “L80-4005L” manufactured by LYSSY AG ZLLIKON, the moisture permeability was measured at a temperature and humidity condition of 40 ° C. and 90% RH according to the method described in JIS-K-7129.

(9) Dimensional change rate Measured according to JIS-K7133. Three lines were drawn vertically and horizontally on the film at intervals of 50 mm and stored in a hot air dryer at a predetermined temperature for 30 minutes, and the dimensional change rate was calculated by the following equation. In the table, the extrusion direction is referred to as MD direction, and the direction perpendicular to the extrusion direction is referred to as TD direction.
Dimensional change rate (%) = {(La−Lb) / La} × 100
La: Distance between lines before storage (50 mm)
Lb: Line spacing after saving

Production Examples 1-4
[Production of polyester]
The raw material monomers listed in Table 1 were charged into a 150-liter polyester production apparatus equipped with a packed tower rectification tower, a partial condenser, a full condenser, a cold trap, a stirrer, a heating device, and a nitrogen introduction tube. In the presence of 0.03 mol% of manganese acetate tetrahydrate with respect to the dicarboxylic acid component, the temperature was raised to 215 ° C. in a nitrogen atmosphere to conduct a transesterification reaction. After the reaction conversion rate of the dicarboxylic acid component reaches 90% or more, 0.02 mol% of antimony (III) oxide and 0.06 mol% of trimethyl phosphate are added to the dicarboxylic acid component and gradually increased. The temperature and pressure were reduced, and finally polycondensation was performed at 270 ° C. and 0.1 kPa or less. The reaction was terminated when the melt viscosity reached an appropriate level, and polyester was produced. The evaluation results are shown in Table 1.

The resin used in the comparative example is described below.
(1) Polyethylene terephthalate: manufactured by Nippon Unipet Co., Ltd., RT543C (abbreviated as PET in the table)
(2) Polycarbonate: manufactured by Mitsubishi Engineering Plastics, Iupilon E-2000 (abbreviated as PC in the table)

Examples 1-4
[Production of polyester film]
Single-axis extruder with vacuum vent (screw diameter 32mmφ) equipped with leaf disk polymer filter (opening 5μm, diameter 4inch, 8 sheets) and coat hanger type T-die with 300mm width, cooling roll (temperature controlled by heating medium) Possible), a film production facility comprising a take-up roll and a winder (adjustable tension) was used. Using polyester of Production Examples 1 to 4, extruder cylinder temperature 250 ° C., polymer filter temperature 250 ° C., T die temperature 250 ° C., cooling roll temperature 81 to 88 ° C., T die lip opening 0.7 mm, air gap 20 mm, discharge A film having a thickness of approximately 100 μm was produced under the conditions of a speed of 9 kg / h, a screw rotation speed of 55 rpm, and a take-up speed of 4 m / min. The evaluation results are shown in Table 2.

Comparative Example 1
[Production of polyester film]
Except changing the cooling roll temperature to 70 ° C. (glass transition temperature of the resin—34 ° C.), polyethylene terephthalate was melt-extruded in the same manner as in Example 1 to produce a film having a thickness of about 100 μm. During production, the adhesion between the film and the roll was poor, the film partially swelled, and an appearance defect occurred. The evaluation results are shown in Table 3.

Comparative Example 2
[Production of polyester film]
Except for changing the cooling roll temperature to 137 ° C. (resin glass transition temperature + 33 ° C.), polyethylene terephthalate was melt-extruded in the same manner as in Example 1 to produce a film having a thickness of about 100 μm. During production, the adhesion between the film and the roll was too good, and peeling marks were generated on the film due to repeated excessive adhesion and peeling. The evaluation results are shown in Table 3.

Comparative Example 3
[Production of polyethylene terephthalate film]
Melt extrusion was performed at a cylinder temperature of 220 to 275 ° C and a die temperature of 265 ° C. The extruded molten resin was cooled with a cooling roll set at 70 ° C. to produce a film having a thickness of about 100 μm. The evaluation results are shown in Table 3.

Comparative Example 4
[Manufacture of polycarbonate film]
Polyethylene terephthalate was melt extruded in the same manner as in Example 1 except that the cylinder temperature was changed to 220 to 260 ° C and the die temperature was 255 ° C. The extruded molten resin was cooled with a cooling roll set at 130 ° C. to produce a film having a thickness of about 100 μm. The evaluation results are shown in Table 3.

Examples 5-7
[Production of polyester film]
It consists of a single-screw extruder with a vacuum vent (screw diameter 50mmφ) equipped with a gear pump and a coat hanger type T die with a width of 550mm, a cooling roll (temperature can be adjusted with a heating medium), a take-up roll and a winder (with adjustable tension). Film production equipment was used. Using polyester of production example 1, extruder cylinder temperature 240 ° C, polymer filter temperature 240 ° C, gear pump temperature 240 ° C, T die temperature 240 ° C, cooling roll temperature 80-92 ° C, T die lip opening 0.5mm, air A film having a thickness of approximately 100 μm was produced under the conditions of a gap of 15 mm, a discharge speed of 30 kg / h, a screw rotation speed of 55 rpm, and a take-up speed of 12 m / min. The evaluation results are shown in Table 4.

Examples 8-9
[Production of polyester film]
A film having a thickness of 38 μm and 120 μm is obtained by performing melt extrusion of the polyester of Production Example 1 in the same manner as in Example 5 except that the cooling roll temperature is fixed at 80 ° C. and the take-up speed is changed to 30 m / min or 10 m / min. Manufactured. The evaluation results are shown in Table 4.

Table 1
Production Example Number Production Example 1 Production Example 2 Production Example 3 Production Example 4
Monomer charge (mole)
Dicarboxylic acid component (mol)
DMT 201.8 174.6 275.9 208.0
NDCM 0.0 0.0 14.5 0.0
Diol component (mol)
SPG 62.6 80.3 17.6 0.0
EG 341.1 356.2 508.4 330.7
DOG 0.0 0.0 0.0 0.0 43.7
Evaluation result of polyester Ratio of diol unit having cyclic acetal skeleton (mol%)
31 46 5 19
Glass transition temperature (° C.) 104 113 90 89
Intrinsic viscosity (dl / g) 0.70 0.66 0.67 0.73
Melt viscosity (Pa · s) 2150 2950 1860 2100
DMT: dimethyl terephthalate NDCM: dimethyl 2,6-naphthalenedicarboxylate EG: ethylene glycol SPG: 3,9-bis (1,1-dimethyl-2-hydroxyethyl) -2,4,8,10-tetraoxaspiro [ 5.5] Undecane DOG: 5-methylol-5-ethyl-2- (1,1-dimethyl-2-hydroxyethyl) -1,3-dioxane

Table 2
Example No. Example 1 Example 2 Example 3 Example 4
Resin Production Example 1 Production Example 2 Production Example 3 Production Example 4
Resin glass transition temperature (° C.) 104 113 90 89
Cooling roll temperature (° C) 81 88 80 85
Evaluation result of film Thickness (μm) 98 101 103 105
In-plane retardation Re [550] (nm) 12 10 18 14
Total light transmittance (%) 92 92 91 92
Haze (%) 0.4 0.5 0.4 0.5

Table 3
Comparative Example No. Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4
Resin Production Example 1 Production Example 1 PET PC
Resin glass transition temperature (° C.) 104 104 80 145
Cooling roll temperature (° C.) 70 137 70 130
Evaluation result of film Thickness (μm) 97 103 109 103
In-plane retardation Re [550] (nm) 32 45 23 28
Total light transmittance (%) 91 92 92 90
Haze (%) 0.4 0.4 1.3 0.4

Table 4
Example No. Example 5 Example 6 Example 7 Example 8 Example 9
Resin Production Example 1 Production Example 1 Production Example 1 Production Example 1 Production Example 1
Resin glass transition temperature (° C.) 104 104 104 104 104
Cooling roll temperature (° C) 80 90 92 80 80
Take-off speed (m / min) 12 12 12 30 10
Evaluation result of film Thickness (μm) 99 101 102 38 120
In-plane retardation
Re [550] (nm) 10 1 4 19 4
Total light transmittance (%) 92 92 92 92 92
Haze (%) 0.4 0.4 0.4 0.3 0.4

Below, the Example of the phase difference film comprised from the polyester film of this invention is described in detail.
[Evaluation method of retardation film]
(1) Calculation of Nz coefficient, thickness direction retardation Rth ([(nx + ny) / 2-nz] × d, where d is film thickness) Incidence angle of retardation around slow axis in film plane by spectroscopic ellipsometer Dependency was measured. From this measurement result, the length of the main axis of the refractive index ellipsoid of the stretched film, that is, the main refractive index nx, ny, nz was calculated from the thickness of the stretched film and the average refractive index of the resin. The calculation is based on the characteristic curve by the analytical solution of the incident angle dependence of the retardation by the refractive index ellipsoid model in the optical film described in Sharp Technique No. 85 (April 2004) “GRP type wide viewing angle LCD technology”. This was done by fitting the measured values. From the calculated main refractive indexes nx, ny, nz and the film thickness d, the Nz coefficient and the thickness direction retardation Rth were determined by the above formula. Since the Nz coefficient and Rth depend on the measurement wavelength, the Nz coefficient and thickness direction retardation at the measurement wavelength λ (nm) are expressed as Nz [λ] and Rth [λ].
FIG. 1 shows a measured value (dotted line) by a spectroscopic ellipsometer and a theoretical curve (solid line) by the above model of the retardation incident angle dependence around the slow axis of a polyester raw film at a wavelength of 550 nm.

Production Example 5
[Manufacture of polyester film]
Using a single-screw extruder (screw diameter: 50 mmφ) having a vacuum vent and a coat hanger die with a width of 550 mm, the polyester of Production Example 1 was melt-extruded under conditions of a cylinder temperature of 220 to 240 ° C., a die temperature of 240 ° C., and a discharge rate of 30 kg / h. Went. The extruded molten resin was cooled with a first roll at 96 ° C. and a second roll at 60 ° C., and taken up at 12 m / min to produce a polyester raw film having a thickness of 80 μm and a width of 480 mm. The evaluation results are shown in Table 5 and FIG.

Example 10
[Production of retardation film (stretched film)]
The polyester raw film is uniaxially stretched with a stretching machine under the conditions of stretching ratio = 1.5 times, stretching speed = 30 mm / min, stretching temperature = glass transition temperature of polyester of Production Example 1 + 7.57 ° C., retardation film 1 was produced. The evaluation results are shown in Table 6. Nz [550], in-plane retardation Re [550] and thickness direction retardation Rth [550] were calculated in the same manner as the polyester raw film.

Example 11
[Production of retardation film (stretched film)]
A retardation film 2 was produced in the same manner as in Example 8, except that the stretching temperature was glass transition temperature + 17.57 ° C. The evaluation results are shown in Table 6.

Example 12
[Production of retardation film (stretched film)]
A retardation film 3 was produced in the same manner as in Example 10 except that the stretching temperature was set to a glass transition temperature + 27.57 ° C. higher. The evaluation results are shown in Table 6.
FIG. 2 shows the position of the ellipsoid on the plane defined by Re [550] × Nz [550] and Re [550] of the polyester raw film and the stretched films of Examples 10 to 12.
As can be seen from FIG. 2, in the uniaxially stretched film, Nz [550] is approximately 1, and it can be seen that the in-plane retardation Re [550] increases as the stretching temperature decreases.

Example 13
[Multilayer retardation film]
Two retardation films 2 are laminated with acrylic adhesive [Sumitomo 3M, DP-8005 Clear] and the slow axis is shifted by 120 °, and this is laminated by using a roller and multilayered. A retardation film having a structure was produced.

Example 14
[Retardation film / protective layer]
A polyester original film having a thickness of 80 μm obtained in the same manner as in Production Example 5 as a protective layer was applied to the retardation film having a multilayer structure of Example 13 with an acrylic adhesive [Sumitomo 3M Co., Ltd., DP-8005 Clear]. ] To produce a retardation film on which an optically isotropic protective layer was laminated.

Example 15
[Retardation film / polarizing film]
A 75-μm-thick polyvinyl alcohol film [Kuraray Co., Ltd., Kuraray Vinylon # 7500] was mounted on the chuck and immersed in an aqueous solution at 30 ° C. containing 0.2 g / L iodine and 60 g / L potassium iodide for 240 seconds. Subsequently, it was immersed in a 30 ° C. aqueous solution containing 70 g / L of boric acid and 30 g / L of potassium iodide, and subjected to boric acid treatment for 5 minutes while being uniaxially stretched 6.0 times. Finally, it was dried at room temperature for 24 hours to produce a polarizing film. A triacetyl cellulose (TAC) sheet having a thickness of 40 μm was laminated on the polarizing film using a roller via an acrylic adhesive [Sumitomo 3M Co., Ltd., DP-8005 Clear]. On the other side, the retardation film 1 was laminated and integrated with a roller by shifting the light absorption axis of the polarizing film and the slow axis of the retardation film using the same acrylic adhesive.

Example 16
A retardation film in which polarizing plates were laminated and integrated was produced in the same manner as in Example 13 except that the polyester raw film of Production Example 5 was laminated instead of the 40 μm thick triacetylcellulose (TAC) sheet. When the protective layer and the retardation film on both sides of the polarizing plate are thus formed from the same polyester (polyester of Production Example 1), there is an effect of suppressing warpage due to moisture absorption.

Example 17
[Retardation film / adhesive layer or adhesive layer / peelable sheet]
On the side opposite to the protective layer of the retardation film of Example 14, a 25 μm thick acrylic highly transparent adhesive transfer tape (Sumitomo 3M Co., Ltd., substrate-less highly transparent adhesive transfer tape 8141) was laminated using a roller. did.

Table 5

Resin production example 1
Evaluation result of raw film Thickness (μm) 80
Nz [550] 14.97
In-plane retardation Re [550] (nm) 1.6
Thickness direction retardation Rth [550] (nm) 23.16
Moisture permeability ^{(g / m 2 / 24hr)} 88
Total light transmittance (%) 92
Haze (%) 0.4

Table 6
Example No. Example 10 Example 11 Example 12
Raw film Production Example 5 Production Example 5 Production Example 5
Evaluation result of stretched film Stretching temperature ΔT (° C) * +7.57 +17.57 +27.57
Stretch ratio (times) 1.5 1.5 1.5
Stretching speed (mm / min) 30 30 30
Thickness (μm) 50 50 50
Nz [550] 1.09 1.14 1.20
In-plane retardation Re [550] (nm) 590.7 284.1 118.2
Thickness direction retardation
Rth [550] (nm) 351.4 182.0 83.2
* Difference from glass transition temperature

  Below, the Example of the polarizing plate protective film comprised from the polyester film of this invention is described in detail.

[Evaluation method of polarizing plate]
(1) Light Leakage Test Two polarizing plates of 10 cm × 10 cm were cut out and left for 100 hours in an environment of temperature 80 ° C. and relative humidity 90% to prepare a test piece. The test piece was placed in crossed Nicol, placed in a light box with a color temperature of 5000K, and visually observed for light leakage.

Example 18
[Production of polyester film]
Using a single-screw extruder (screw diameter: 50 mmφ) having a vacuum vent and a coat hanger die with a width of 550 mm, the polyester of Production Example 1 was melt extruded under the conditions of a cylinder temperature of 240 ° C., a die temperature of 240 ° C., and a discharge speed of 30 kg / h. It was. The extruded molten resin was cooled with a first roll at 96 ° C. and a second roll at 60 ° C., and taken up at 12 m / min, to produce a polyester raw film having a thickness of 76 μm and a width of 480 mm. Table 7 shows the evaluation results.
[Preparation of polarizing plate]
A 75-μm-thick polyvinyl alcohol film [Kuraray Co., Ltd., Kuraray Vinylon # 7500] was mounted on the chuck and immersed in an aqueous solution at 30 ° C. containing 0.2 g / L iodine and 60 g / L potassium iodide for 240 seconds. Subsequently, it was immersed in a 30 ° C. aqueous solution containing 70 g / L of boric acid and 30 g / L of potassium iodide, and subjected to boric acid treatment for 5 minutes while being uniaxially stretched 6.0 times. Finally, it was dried at room temperature for 24 hours to produce a polarizing film. Subsequently, the polarizing film and the polyester film were bonded together through an acrylic adhesive [Sumitomo 3M Co., Ltd., DP-8005 clear] to obtain a polarizing plate. Table 7 shows the results of the light leakage test.

Example 19
[Production of polyester film]
A polyester raw film was produced in the same manner as in Example 18 except that the discharge speed was changed to 55 kg / h and the cylinder temperature and the die temperature were changed to 250 ° C. The thickness was 152 μm and the width was 497 mm. Table 7 shows the evaluation results.
[Preparation of polarizing plate]
A polarizing plate was obtained in the same manner as in Example 18 using the polyester film. Table 7 shows the results of the light leakage test.

Example 20
[Production of polyester film]
A polyester raw film was produced in the same manner as in Example 18 except that the first roll temperature was changed to 94 ° C. The thickness of the film was 74 μm and the width was 479 mm. Table 7 shows the evaluation results.
[Preparation of polarizing plate]
A polarizing plate was obtained in the same manner as in Example 18 using the polyester film. Table 7 shows the results of the light leakage test.

Example 21
[Production of polyester film]
A polyester raw film was produced in the same manner as in Example 18 except that the cylinder temperature and die temperature of the extruder were changed to 245 ° C. The thickness of the film was 74 μm and the width was 482 mm. Table 7 shows the evaluation results.
[Preparation of polarizing plate]
A polarizing plate was obtained in the same manner as in Example 18 using the polyester film. Table 7 shows the results of the light leakage test.

Comparative Example 5
[Manufacture of PC film]
Using a product name “Iupilon E-2000R” (abbreviated as PC in the table) manufactured by Mitsubishi Engineering Plastics, the cylinder temperature was changed to 290 ° C., the die temperature was changed to 290 ° C., and the temperature of the first roll was changed to 130 ° C. Except for the above, melt extrusion was carried out in the same manner as in Example 18. The obtained film had a thickness of 75 μm and a width of 476 mm. The evaluation results are shown in Table 8.
[Preparation of polarizing plate]
A polarizing plate was obtained in the same manner as in Example 18 using the above film. The results of the light leakage test are shown in Table 8.

Comparative Example 6
[Production of PET film]
Using Nippon Unipet Co., Ltd., RT543C (abbreviated as PET in the table), melt extrusion was performed in the same manner as in Example 18 except that the cylinder temperature and die temperature were changed to 270 ° C., and the temperature of the first roll was changed to 70 ° C. It was. The obtained film had a thickness of 75 μm and a width of 476 mm. The evaluation results are shown in Table 8.
[Preparation of polarizing plate]
A polarizing plate was obtained in the same manner as in Example 18 using the above film. The results of the light leakage test are shown in Table 8.

Comparative Example 7
[TAC cast film]
The product name “Fujitac Clear” (abbreviated as TAC in the table) manufactured by Fuji Photo Film Co., Ltd. was used as it was. The evaluation results are shown in Table 8.
[Preparation of polarizing plate]
A polarizing plate was obtained in the same manner as in Example 18 using the above film. The results of the light leakage test are shown in Table 8.

Table 7
Example No.Example 18 Example 19 Example 20 Example 21
Resin Production Example 1 Production Example 1 Production Example 1 Production Example 1
Production Method Melt Extrusion Melt Extrusion Melt Extrusion Evaluation Results of Melt Extruded Film Film Thickness (μm) 76 152 74 74
Unevenness of film thickness (μm) ± 1.3 ± 1.6 ± 1.4 ± 1.4
Unevenness of film thickness (%) ± 1.7 ± 1.1 ± 1.9 ± 1.9
In-plane retardation
Re [550] (nm) 1.9 2.9 3.7 4.6
Total light transmittance (%) 92 92 92 92
Haze (%) 0.3 0.4 0.3 0.3
Moisture permeability (g / (m ² · 24 hr)) 88 48 85 90
Evaluation of polarizing plate
Light leakage None None None None

Table 8
Example No. Comparative Example 5 Comparative Example 6 Comparative Example 7
Resin PC PET TAC
Manufacturing Method Melt Extrusion Melt Extrusion Evaluation Result of Solvent Cast Film Film Thickness (μm) 75 73 80
Unevenness of film thickness (μm) ± 5.0 ± 4.2 ± 2.1
Unevenness of film thickness (%) ± 6.7 ± 5.6 ± 2.6
In-plane retardation
Re [550] (nm) 25.1 26.2 4.8
Total light transmittance (%) 90 92 92
Haze (%) 0.5 1.2 0.2
Moisture permeability (g / (m ² · 24 hr)) 51 9 516
Evaluation of polarizing plate
Light leakage Yes Yes No

  Below, the Example of the lens sheet comprised from the polyester film of this invention is described in detail.

Examples 22 and 23
[Production and evaluation of polyester film]
Using a single-screw extruder (screw diameter: 50 mmφ) having a vacuum vent and a coat hanger die with a width of 550 mm, melt extrusion of the polyester of Production Example 2 under conditions of a cylinder temperature of 220 to 240 ° C., a die temperature of 240 ° C., and a discharge speed of 30 kg / h. Went. The extruded molten resin was cooled with a first roll set to Tg-10 ° C. and a second roll set to 60 ° C., and taken up at 12 m / min to produce a polyester film having a thickness of 100 μm and a width length of 480 mm. Table 9 shows the evaluation results.

[Manufacture and evaluation of prism sheets]
An optical element pattern (prism pattern) is formed on a 3 mm × 300 mm × 400 mm brass plate compliant with JIS 2804 by cutting parallel prisms with an apex angle of 65 ° and an isosceles triangle at a pitch of 50 μm, and then subjected to Ganizen plating. To give a lens mold. An appropriate amount of an acrylic ultraviolet curable monomer mixed solution was injected into the lens mold, and then a polyester film cut to an appropriate size was superposed while being pressed with a roll. Next, the resin was cured by irradiating ultraviolet rays for 45 seconds from three 6.4 kw ultraviolet lamps (manufactured by Western Quartz) with an irradiation intensity of 80 w / cm disposed above the polyester film, and then removed from the lens mold to remove the prism sheet. Obtained. Table 9 shows the evaluation results. The acrylic ultraviolet curable monomer mixture has the following composition.
Hitachi Chemical FA-321M ... 50% by weight
KAYARADR-604 ... 20% by weight, manufactured by Nippon Kayaku Co., Ltd.
Osaka Organic Chemical Co., Ltd. Biscoat # 192 ... 30% by weight
Mercury Darocur 1173 (radical photopolymerization initiator) 1.5 parts by weight
(FA-321M, KAYARADR-604 and biscoat # 192 correspond to the monomer or oligomer (A) capable of radical polymerization, and Darocur 1173 corresponds to the active energy ray-sensitive catalyst (B).)

Example 24
[Manufacture and evaluation of lenticular lens sheets]
A circular lenticular lens section made up of a plurality of parallel cylindrical lens rows is cut on a 3 mm × 300 mm × 400 mm brass plate conforming to JIS 2804 by cutting an arc row with a radius of curvature of 0.5 mm in parallel at a 0.2 mm pitch. Then, the lens mold was prepared by applying Ganizen plating. An appropriate amount of an acrylic ultraviolet curable monomer mixed solution was injected into the lens mold, and then a polyester film cut to an appropriate size was superposed while being pressed with a roll. Next, the resin was cured by irradiating ultraviolet rays from three 6.4 kw ultraviolet lamps (manufactured by Western Quartz) with an irradiation intensity of 80 w / cm disposed above the polyester film for 45 seconds, and then removed from the lens mold and lenticular lens sheet. Got. The acrylic UV curable monomer mixture is the same as that for the prism sheet.

Example 25
[Manufacture and evaluation of Fresnel lens sheet]
A Fresnel lens portion made of a concentric Fresnel lens having a focal length of 300 mm and a Fresnel zone pitch of 0.5 mm was formed on a 3 mm × 300 mm × 400 mm plate made of brass compliant with JIS 2804, and a lens mold was produced by applying Ganizen plating. . An appropriate amount of an acrylic ultraviolet curable monomer mixed solution was injected into the lens mold, and then a polyester film cut to an appropriate size was superposed while being pressed with a roll. Next, the resin was cured by irradiating ultraviolet rays from three 6.4 kw ultraviolet lamps (manufactured by Western Quartz) with an irradiation intensity of 80 w / cm disposed above the polyester film for 45 seconds, and then taken out from the lens mold to be a Fresnel lens sheet. Got. The acrylic UV curable monomer mixture is the same as that for the prism sheet.

Example 26
[Manufacture and evaluation of Fresnel lens / lenticular lens sheet]
After forming the Fresnel lens part on the surface of the polyester film in the same manner as in the manufacture of the Fresnel lens sheet, the lenticular lens part is formed on the other surface in the same manner as in the manufacture of the lenticular lens sheet. A sheet having a lens part and a lenticular lens part on the other surface was produced.

Example 27
[Production and evaluation of Fresnel lens / prism array sheet]
After the Fresnel lens portion is formed on the surface of the polyester film in the same manner as in the manufacture of the Fresnel lens sheet, an isosceles triangular prism array is formed on the other surface in the same manner as in the manufacture of the prism sheet. A sheet having a Fresnel lens portion and a prism array on the other surface was manufactured.

Table 9
Example No. Example 22 Example 23
Evaluation result of polyester film Total light transmittance (%) 92 92
Haze (%) 0.2 0.3
In-plane retardation Re [550] (nm) 2.0 1.9
Evaluation result of lens sheet Dimensional change rate (80 ° C,%) 0.0 0.0
(100 ° C,%) 0.0 0.0
(120 ° C,%) 0.5 0.0

  Below, the Example of the light-diffusion film comprised from the polyester film of this invention is described in detail.

Example 24
[Production of polyester film]
Using a single-screw extruder (screw diameter: 50 mmφ) having a vacuum vent and a coat hanger die with a width of 550 mm, melt extrusion of the polyester of Production Example 2 under conditions of a cylinder temperature of 220 to 240 ° C., a die temperature of 240 ° C., and a discharge speed of 30 kg / h. Went. The extruded molten resin was cooled with a first roll set to Tg-10 ° C. and a second roll set to 60 ° C., and taken up at 12 m / min to produce a polyester film having a thickness of 100 μm and a width length of 480 mm. Table 10 shows the evaluation results.

[Manufacture of light diffusion film]
UV curable resin (Nippon Kayaku DPHA, refractive index 1.51) 66 wt%, curing initiator (Ciba Geigy, Irgacure 184) 4 wt% as a binder resin constituting the light diffusion layer, and diffusion beads After mixing 30% by weight of acrylic beads (Sekisui Plastics Industry MBX-12, average particle size 12 μm, refractive index 1.49), methyl ethyl ketone / methyl isobutyl ketone (3/7 mass ratio) was added to obtain a solid content of 24%. It was adjusted to become. This composition was applied on a polyester film so as to have a dry film thickness of 6.0 μm and dried. Next, using a 160 W / cm air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.), an ultraviolet ray having an illuminance of 400 mW / cm ² and an integrated irradiation amount of 300 mJ / cm ² is irradiated to cure the coating layer, and a light diffusion film is formed. Produced.

Table 10

Resin production example 1
Evaluation result of film Thickness (μm) 80
Dimensional change (%) at 120 ° C for 30 minutes 0
In-plane retardation Re [550] (nm) 1.5
Total light transmittance (%) 92
Haze (%) 0.4

  Below, the Example of the antireflection film comprised from the polyester film of this invention is described in detail.

Examples 27 and 28
[Production and evaluation of polyester film]
Using a single-screw extruder (screw diameter: 50 mmφ) having a vacuum vent and a coat hanger die with a width of 550 mm, melt extrusion of the polyester of Production Example 2 under conditions of a cylinder temperature of 220 to 240 ° C., a die temperature of 240 ° C., and a discharge speed of 30 kg / h. Went. The extruded molten resin was cooled with a first roll set to Tg-10 ° C. and a second roll set to 60 ° C., and taken up at 12 m / min to produce a polyester film having a thickness of 100 μm and a width length of 480 mm. The evaluation results are shown in Table 11.

[Production and evaluation of antireflection film]
(Hardcoat layer coating on polyester film)
On the polyester film obtained above, Desolite Z7501 (manufactured by JSR Corporation) was applied so as to have a thickness after drying of 5 μm, and UV cured.
(Antireflection coating)
Next, magnesium fluoride was coated on the hard coat layer by an electron beam heating vapor deposition method so as to have a thickness of 100 nm to obtain an antireflection film. The evaluation results are shown in Table 11.

Table 11
Example No. Example 25 Example 26
Total light transmittance (%) 92 92
Haze (%) 0.2 0.3
In-plane retardation Re [550] (nm) 1.8
Evaluation result of antireflection film Dimensional change rate (80 ° C,%) 0.0 0.0
(100 ° C,%) 0.0 0.0

  Below, the Example of the optical information recording medium comprised from the polyester film of this invention is described in detail.

Example 27
[Production of polyester film]
Using a single-screw extruder (screw diameter: 50 mmφ) having a vacuum vent and a coat hanger die with a width of 550 mm, the polyester of Production Example 1 was melt-extruded under conditions of a cylinder temperature of 220 to 240 ° C., a die temperature of 240 ° C., and a discharge rate of 30 kg / h. Went. The extruded molten resin was cooled with a first roll set at 96 ° C. and a second roll set at 60 ° C., and taken up at 12 m / min to produce a polyester film having a thickness of 80 μm and a width length of 480 mm. The evaluation results are shown in Table 12.

[Manufacture of optical information recording media (Blu-ray Disc)]
Thin films (reflection layer and recording layer) were formed by sputtering on a polycarbonate resin circular substrate having a thickness of 1.1 mm formed by injection molding. Ag was formed as the reflective film, and the recording layer was formed in the order of ZiS—SiO ₂ dielectric film / Ge—Sb—Te recording film / ZiS—SiO 2 dielectric film. After film formation, the entire film was crystallized and initialized by heat treatment by laser light irradiation.
Next, the transparent adhesive was transferred to the polyester film from the highly transparent adhesive transfer tape using a roll laminator, and the obtained laminate was punched into a concentric donut shape having an outer diameter of 119.4 mmφ and an inner diameter of 22.5 mmφ. The obtained polyester film with a transparent adhesive was stuck on the recording layer with a roll laminator to produce an optical information recording medium. At that time, the total thickness of the polyester film and the transparent adhesive layer was considered to be 100 μm (± 2 μm). The thickness of the polyester film was 80 μm, and the thickness of the transparent adhesive layer was 20 μm. As a result of recording and reproducing the optical information recording medium thus manufactured with the Blu-ray Disc Recorder “BD-HD100” manufactured by Sharp Corporation, it was confirmed by visual observation of the recorded / reproduced image that good recording / reproducing was performed. .

Example 28
Instead of laminating a highly transparent adhesive transfer tape consisting of a transparent adhesive on a polyester film with a roll laminator, an acrylic adhesive (Sumitomo 3M, DP-8005 clear) was applied onto the polyester film from the coater head. An optical information recording medium was manufactured in the same manner as Example 27 except for the above.

Example 29
Instead of laminating a highly transparent adhesive transfer tape consisting of a transparent adhesive to a polyester film with a roll laminator, an acrylic-modified one-part moisture-curing adhesive (trade name: Bond Silex “Clear”, manufactured by Konishi Co., Ltd.) An optical information recording medium was produced in the same manner as in Example 27 except that the coating was applied on the polyester film from the coater head.

Example 30
Instead of laminating a highly transparent adhesive transfer tape consisting of a transparent adhesive on a polyester film with a roll laminator, an acetic acid-based one-component moisture-curing adhesive (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KE-41-T) ) Was coated on the polyester film from the coater head in the same manner as in Example 27 to produce an optical information recording medium.

Example 31
Instead of laminating a highly transparent adhesive transfer tape consisting of a transparent adhesive on a polyester film with a roll laminator, coater head with urethane one-component moisture-curing adhesive (trade name: Takenate M631N, manufactured by Mitsui Takeda Chemical Co., Ltd.) An optical information recording medium was produced in the same manner as in Example 27 except that the coating was applied to the polyester film.

Example 32
Instead of laminating a highly transparent adhesive transfer tape made of a transparent adhesive on a polyester film with a roll laminator, an acrylic solventless electron beam curable adhesive (trade name: DA-314, manufactured by Nagase ChemteX Corporation) An optical information recording medium was produced in the same manner as in Example 27 except that the coating was applied on the polyester film from the coater head.

Example 33
Instead of laminating a highly transparent adhesive transfer tape made of a transparent adhesive on a polyester film with a roll laminator, an epoxy-based solvent-free UV curable adhesive (Norland Products, product name: Norland Optical Adhesive 81) is applied from the coater head. An optical information recording medium was produced in the same manner as in Example 27 except that the coating was performed on the polyester film.

Example 34
Instead of laminating a highly transparent adhesive transfer tape consisting of a transparent adhesive on a polyester film with a roll laminator, an acrylic adhesive (made by Konishi Co., Ltd., trade name: Kony Bond) was applied on the polyester film from the coater head. Manufactured an optical information recording medium in the same manner as in Example 27.

Comparative Example 8
The transparent adhesive layer was removed from the protective layer of the Sony Blu-ray Disc BF23GB for recording, and the retardation of the obtained film was evaluated. The results are shown in FIG. When the absorption spectrum of the film was measured by the ATRFT-IR method, it was made of PC resin.
The optically isotropic polyester film of the present invention is excellent in optical transparency and has a small retardation due to birefringence. In particular, in a Blu-ray disc, it is particularly desirable that the in-plane retardation Re [405] at normal incidence at a wavelength of 405 nm is 5 nm or less. As can be seen from FIG. 7, Re [405] was 3.97 nm in Comparative Example 8, whereas it was 1.94 nm in Example 27.
The retardation at a wavelength of 405 nm in the range of the maximum incident angle ± 60 ° of Example 27 (converted from the numerical aperture of the pickup optical system of 0.85) is 20 nm or less, which is smaller than 40 nm or less of Comparative Example 8, preferable. As described above, since the change in the plane of polarization of the incident laser light caused by the birefringence of the polyester film is of no problem, the polyester film of the present invention is preferably used as a constituent material of the protective layer of the Blu-ray disc.

Table 12
Example No. Example 27 Comparative Example 8
Resin Production Example 1 PC
Evaluation result of film Thickness (μm) 80 80
In-plane retardation Re [405] (nm) 1.94 3.97
± 60 ° oblique incidence retardation (nm) 20 or less 40 or less Total light transmittance (%) 92 −
Haze (%) 0.4 −

  The polyester film of the present invention can be easily formed into an optically isotropic film by an extrusion method having excellent economical efficiency. The polyester film of the present invention can be suitably used for optical members such as polarizing plates and retardation films, and the industrial significance of the present invention is great.

A graph showing a measured value (dotted line) of a spectroscopic ellipsometer and a theoretical curve (solid line) based on a refractive index ellipsoid model. Retardation by uniaxial stretching Schematic which shows the structural example of a prism sheet. Schematic which shows the structural example of a light-diffusion film. Schematic which shows the structural example of an antireflection film. Schematic which shows the structural example of an optical information recording medium. The graph which shows the incident angle dependence of retardation.

Claims (24)

A polyester containing a dicarboxylic acid unit and a diol unit, wherein 1 to 80 mol% of the diol unit is a diol unit having a cyclic acetal skeleton, and the diol unit having a cyclic acetal skeleton is 3,9-bis (1 , 1-Dimethyl-2-hydroxyethyl) -2,4,8,10-tetraoxaspiro [5.5] undecane or 5-methylol-5-ethyl-2- (1,1-dimethyl-2-hydroxyethyl) ) A diol unit derived from 1,3-dioxane, and a diol unit other than a diol unit having a cyclic acetal skeleton is ethylene glycol, diethylene glycol, trimethylene glycol, 1,4-butanediol and 1,4-cyclohexanedi A diol unit derived from one or more diols selected from methanol , Thickness dicarboxylic acid units was formed into a film of terephthalic acid, by isophthalic acid, and 2,6-naphthalene melt extrusion of the polyester is a dicarboxylic acid unit derived from at least one dicarboxylic acid selected from dicarboxylic acids 1~500μm A method for producing a polyester film, comprising: a step of melt-extruding polyester to form a melt film; and a step of bringing the melt film into contact with a cooling roll to cool and solidify the polyester film. -300 ° C, air gap of 100 mm or less, take-off speed of 0.2-100 m / min, and the cooling roll temperature is adjusted to the range of polyester glass transition temperature-30 ° C to polyester glass transition temperature + 30 ° C. obtained by the process, put the wavelength 550nm Polyester film plane retardation is 20nm or less. Polyester film of claim 1 wherein or an optical member having a film layer made of stretched film obtained from a polyester film according to claim 1. The optical member according to claim 2 , wherein the optical member is a retardation film having a film layer made of the stretched film, the in-plane retardation and / or Nz coefficient of which are controlled. The optical member according to claim 3 , which has a multilayer structure in which two or more film layers are laminated. The optical member according to claim 3 or 4, wherein an optically isotropic protective layer is laminated on at least one surface of the film layer. The optical member according to claim 5 , wherein the optically isotropic protective layer has a film layer made of the polyester film according to claim 2. The optical member according to any one of claims 3 to 6 , wherein a polarizing plate is laminated and integrated on the film layer. The optical member according to any one of claims 3 to 7 , wherein a peelable sheet is laminated on at least one surface of the film layer via an adhesive layer or an adhesive layer. 3. The optical member according to claim 2 , wherein the optical member is a polarizing plate composed of a film layer made of the polyester film and a polarizing film, wherein the moisture permeability at 40 ° C. and 90% RH is 10 to 300 g / (m ² · 24 hr). . The optical member according to claim 9 , wherein the in-plane retardation of the polyester film at a wavelength of 550 nm is 5 nm or less. The optical member according to claim 9 or 10 , wherein the thickness of the polyester film is 200 µm or less, and the difference between the maximum and minimum film thicknesses is 2% or less of the average film thickness. The optical member according to any one of claims 9 to 11 , wherein the polyester film has a total light transmittance of 90% or more and a haze of 1% or less. The optical member according to claim 2 , wherein the optical member is a light diffusing film including a film layer made of the polyester film and a light diffusing layer made of diffusing beads and a binder resin. The optical member according to claim 13 , wherein the binder resin is made of at least one resin selected from the group consisting of an ionizing radiation curable resin, a thermosetting resin, an electron beam curable resin, and an ultraviolet curable resin. The optical member according to claim 13 or 14 , wherein the diffusion beads are made of at least one selected from the group consisting of glass, acrylic resin, urethane resin, vinyl chloride resin, and polycarbonate resin. The optical member according to claim 2 , which is a lens sheet comprising a film layer made of the polyester film and an optical element formed on at least one surface of the film layer. The optical member according to claim 16 , wherein the optical element is formed of an active energy ray curable resin. The optical member according to claim 16 or 17 , wherein the optical element has a prism portion formed in parallel and formed of a plurality of prism rows having a triangular cross section. The optical member according to claim 16 or 17 , wherein the optical element has a lenticular lens portion formed of a plurality of cylindrical lens rows formed in parallel. The optical member according to claim 16 or 17 , wherein the optical element has a Fresnel lens portion formed in a concentric Fresnel lens shape. The optical member according to claim 2 , which is an antireflection film comprising a film layer made of the polyester film and an antireflection layer laminated on the film layer. The optical member according to claim 2 , which is an optical information recording medium comprising a film layer made of the polyester film, a transparent adhesive layer, a recording layer, a reflective layer, and a base material, which are sequentially laminated. The optical member according to claim 22 , wherein the total thickness of the film layer and the transparent adhesive layer is 98 to 102 μm. The optical member according to claim 22 or 23 , wherein an in-plane retardation of the film layer at a wavelength of 405 nm is 5 nm or less.

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