JP2011231263A - Biaxially oriented polyester film and mold release film using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biaxially oriented polyester film, wherein defects in optical inspection can be easily detected, which film produces as little oligomer separated out as possible, and is suitable for various optical applications including manufacture of liquid crystal structural members, such as liquid crystal polarizing plates, retardation plates; manufacture of PDP structural members; manufacture of organic EL structural members, manufacture of various kinds of display structural members; and to provide a mold release film using the same.SOLUTION: This biaxially oriented polyester film has an inclination of an orientation main axis of ≤11° and film haze value of 10-25%, wherein the intrinsic viscosity of polyester constituting at least one of the surface layers is ≥0.65. The mold release film has a mold release layer on one surface of the polyester film. In the mold release film, a releasing force of the mold release layer is within the range of 10-100 mN/cm, and an intrinsic viscosity of the polyester constituting the surface layer opposite to the mold release layer is ≥0.65.

Description

  The present invention relates to a release film using a polyester film which is excellent in compatibility with various optical inspections and has a minimal amount of oligomer precipitation on the film surface opposite to the release layer. For the production of LCD components such as polarizing plates and retardation plates used in LCD (sometimes abbreviated as LCD), for the production of plasma display panel (hereinafter abbreviated as PDP) components, organic electroluminescence (hereinafter referred to as “LCD”). The present invention provides a release film suitable for manufacturing various display components, such as for manufacturing components, which may be abbreviated as “organic EL”.

  Conventionally, a release film based on a polyester film has been used for various optical components such as a liquid crystal polarizing plate, a retardation plate component, a PDP component, an organic EL component, and various display components. Used for applications. As a problem in the use of a release film, an oligomer that precipitates on the opposite surface of the release layer may cause various problems in a roll in the manufacturing process, particularly in a laminate roll that is bonded to a polarizing plate after being subjected to adhesive processing. Can be mentioned.

  In recent years, with the advancement of the IT (Information Technology) field, the release film is required not only to improve productivity, but also to improve the quality of the release film used when manufacturing display members such as LCD, PDP, and organic EL. ing. From this point of view, various problems associated with the precipitation of oligomers become apparent.

  In order to cope with the various uses described above, it is desired that not only the mold release property is excellent, but also the foreign matter on the film surface is as small as possible. That is, since it is also an application that places importance on so-called visibility, especially when transmitting light, even a foreign matter on the film surface, which is not a problem at all in a normal film application, becomes a serious problem.

  For example, when the manufacturing process of a liquid crystal polarizing plate is given as an example, the manufacturing process includes a process in which a release film and a polarizing plate are bonded to each other via a pressure-sensitive adhesive layer and wound into a roll, and the oligomer is adhesive. It is thought that it precipitates through the drying process after agent coating. Oligomer deposited on the opposite surface of the release layer is transferred to the roll in contact with the opposite surface of the release layer in the laminate roll that bonds the liquid crystal polarizing plate and the release film coated with adhesive. , Will contaminate the roll. If the contaminated roll is left unattended, foreign matters are generated due to the falling off of the oligomer and mixed into the liquid crystal polarizing plate. Therefore, the roll must be cleaned, which may impair productivity.

  In recent years, with the aim of reducing the manufacturing cost accompanying productivity improvement, with the speeding up of the manufacturing process, there is a tendency to set the drying temperature in the drying process higher in particular, and the above-mentioned oligomer is more likely to precipitate, Since the roll is soiled, production is hindered.

  In the inspection process that involves optical evaluation such as the display performance, hue, contrast, and contamination of liquid crystal polarizing plates, measures to prevent the outflow of defective products are taken by visual observation or using a magnifier, but crystallized oligomers adhere. When the release film is used, there is a problem in that it is determined as a defective product due to the inclusion of foreign matter, resulting in problems such as a decrease in product yield.

  In addition to the foreign matter problem described above, components of liquid crystal display devices are usually inspected in a timely manner for evaluation of display capability, hue, contrast, and the like. However, the release film using the conventional biaxially oriented polyester as the base material has anisotropy, which hinders inspections that involve optical evaluation. Then, a new surface protection film is again pasted after the inspection is completed. The reason why the surface protective film is re-applied is that, even if the surface protective film can be re-applied, the beauty is lost if it is re-applied.

  In the above-described inspection, peeling and re-sticking of the surface protective film requires two steps in the process, which is a major obstacle in this field where cost reduction is pursued to the limit.

  As a method for solving the above problem, a method is proposed in which the orientation direction of the orientation axis of the biaxially oriented polyester is substantially the same as the orientation direction of the polarizing plate or the retardation plate, or the orientation is oriented to 90 °. However, the method using a biaxially oriented polyester film has a problem in that the yield decreases because it is difficult to strictly control the direction of the orientation main axis.

JP 2009-214355 A JP 2001-277455 A JP 2001-323141 A JP 2001-323142 A JP 2001-335649 A Japanese Unexamined Patent Publication No. 7-101026

  The present invention has been made in view of the above circumstances, and the problem to be solved is that it is possible to easily detect defects in optical inspection, and the amount of oligomer precipitation is as small as possible. For example, liquid crystal components such as liquid crystal polarizing plates and phase difference plates A biaxially oriented polyester film suitable for various optical components and the like, as well as a release film using the same, as well as for various display components, such as for manufacturing, for manufacturing PDP components, for manufacturing organic EL components, etc. There is.

  As a result of intensive studies in view of the above circumstances, the present inventors have found that the above problems can be easily solved by a film having a specific configuration, and have completed the present invention.

  That is, the gist of the present invention is that the orientation of the orientation main axis is 11 degrees or less, the film haze value is 10 to 25%, and the intrinsic viscosity of the polyester constituting at least one surface layer is 0.65 or more. A biaxially oriented polyester film, and a release film having a release layer on one side of the polyester film, and the release force of the release layer is in the range of 10 to 100 mN / cm, opposite to the release layer It exists in the release film characterized by being a polyester layer whose intrinsic viscosity of the polyester which comprises the surface layer of a surface is 0.65 or more.

  According to the present invention, it is possible to easily detect defects in the examination, and the amount of oligomer precipitation is as small as possible. For example, for manufacturing liquid crystal components such as liquid crystal polarizing plates and retardation plates, for manufacturing PDP components, organic EL components In addition to the production of various display components such as production, a biaxially oriented polyester film suitable for various optical applications and a release film using the same can be provided, and the industrial value of the present invention is high.

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

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

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

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

  Examples of the inert particles contained in the polyester film include particles of silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, kaolin, aluminum oxide, titanium oxide, and the like. Further, the heat-resistant organic particles described in JP-B-59-5216, JP-A-59-217755 and the like may be used. Examples of other heat-resistant organic particles include thermosetting urea resins, thermosetting phenol resins, thermosetting epoxy resins, benzoguanamine resins, and the like. Furthermore, it is possible to use precipitated particles in which a part of a metal compound such as a catalyst is precipitated and finely dispersed during the manufacturing process of the film raw material.

  On the other hand, the shape of the particles to be used is not particularly limited, and any of a spherical shape, a block shape, a rod shape, a flat shape and the like may be used. Moreover, there is no restriction | limiting in particular about the hardness, specific gravity, a color, etc. These series of particles may be used in combination of two or more as required.

  Moreover, the average particle diameter of the particle | grains to be used is 0.1-5 micrometers normally, Preferably it is the range of 0.2-3 micrometers. When the average particle size is less than 0.1 μm, the particles are likely to aggregate, resulting in insufficient dispersibility or an increase in film haze. On the other hand, when the thickness exceeds 5 μm, the surface roughness of the film becomes too rough, and a problem may occur when various surface functional layers are applied in a subsequent process.

  Furthermore, the content of particles in the polyester layer is usually 0.05 to 5% by weight, preferably 0.003 to 3% by weight. If the particle content is less than 0.05% by weight, the slipperiness of the film may be insufficient or the film haze may not be increased. On the other hand, when adding over 5 weight%, there exists a tendency for a film haze to become high too much.

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

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

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

  In the present invention, in order to further facilitate the detection of defects such as foreign matter and scratches on the polarizing plate, the film haze value is set to 10 to 25%, preferably 14 to 21%. When the haze value is less than 10%, there is little scattered light when light passes through the polyester film, and the inspection property is good. However, when there are scratches on the polyester film surface, the scratches on the polyester film surface are conspicuous at the time of inspection This makes it impossible to accurately test the defects of the specimen itself. On the other hand, when the haze value exceeds 21%, there is a lot of scattered light on the surface, and defects to be detected in the inspection are not detected, which is not preferable.

  In addition, the polyester film of the present invention preferably has a laminated structure having a two-layer structure or more. Film haze can be adjusted by blending particles added to the intermediate layer, and surface properties of the film can be adjusted by blending particles added to the surface layer.

  In the present invention, the film haze is adjusted by the particles to be blended in the film. However, in the case of a single layer, the surface roughness on both sides of the film is performed in order to perform a method such as blending a large amount of particles when the film haze is increased. The degree can be large.

  When a polyester film with a large surface roughness is used as the release film, when the release film is bonded to the adhesive material of the polarizing plate, bubbles are involved due to the effects of surface protrusions, or the surface of the release film is an adhesive material. When it is transferred to the surface of the film and the polarizing plate is bonded to the panel, bubbles may be formed.

  In the polyester film of the present invention, the intrinsic viscosity of the polyester constituting the surface layer on at least one side needs to be 0.65 or more. Preferably it is 0.70 or more. When the intrinsic viscosity is less than 0.65, it is impossible to prevent the oligomer from being easily precipitated by the particles to be blended in order to satisfy the above-described film haze. It is also necessary that the intrinsic viscosity of the opposite surface of the release layer is 0.65 or more. The release film that is bonded to the liquid crystal polarizing plate via the adhesive does not cause process contamination on the release layer side, but the opposite surface of the release layer is the laminate roll in the bonding process with the polarizing plate. This is because of direct contact.

  The film thickness of this invention is 10-100 micrometers normally, Preferably it is 20-75 micrometers, More preferably, it is the range of 20-50 micrometers. When this range is exceeded, the handleability of the film may deteriorate, or the production cost may increase.

  In the biaxially oriented polyester film of the present invention, the inclination of the orientation main axis is 11 degrees or less, preferably 9 degrees or less. Here, the orientation of the orientation main axis is called an orientation angle, and indicates the inclination of the main axis with respect to the film width direction or the longitudinal direction. In a release film using a biaxially oriented polyester film in which the inclination of the orientation main axis exceeds 11 degrees, light leakage is great during crossed Nicols inspection, which hinders detection of defects such as foreign matter and scratches.

  The orientation of the orientation main axis can be adjusted by changing conditions such as the temperature and stretching ratio in longitudinal stretching, the temperature and stretching ratio in transverse stretching, and the relaxation treatment.

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

  That is, a method of using the polyester raw material described above and cooling and solidifying a molten sheet extruded from a die with a cooling roll to obtain an unstretched sheet is preferable. In this case, in order to improve the flatness of the sheet, it is necessary to improve the adhesion between the sheet and the rotary cooling drum, and an electrostatic application adhesion method and / or a liquid application adhesion method are preferably employed. Next, the obtained unstretched sheet is stretched in the biaxial direction. In that case, first, the unstretched sheet is stretched in one direction by a roll or a tenter type stretching machine. The stretching temperature is usually 70 to 120 ° C., preferably 80 to 110 ° C., and the stretching ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times.

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

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

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

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

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

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

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

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

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

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

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

  The coating amount of the release layer in the present invention is usually in the range of 0.01-1 g / m2.

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

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

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

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

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

(2) Average particle diameter (d50)
The average particle size d50 was defined as the particle size having an integrated volume fraction of 50% in an equivalent spherical distribution measured using a centrifugal sedimentation type particle size distribution analyzer (SA-CP3 type) manufactured by Shimadzu Corporation.

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

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

(5) Heat treatment of film A4 size Kent paper and polyester film to be heat-treated are combined. At that time, clip the four corners with a gem clip or the like so that the opposite surface of the release layer is on the outside, and stop the Kent paper and polyester film. Under a nitrogen atmosphere, the polyester film is left in an oven at 160 ° C. for 30 minutes to perform heat treatment.

(6) Amount of oligomer on film surface after heat treatment Fold the polyester film after heat treatment so that the upper part is opened and the area of the bottom side is 250 cm ² to create a square box. When the coating layer is provided, the opposite surface of the release layer is set to the inside. Next, 10 ml of DMF is put in the box prepared by the above method, and the DMF is recovered after being left for 3 minutes. The recovered DMF is supplied to liquid chromatography (Shimadzu LC-7A) to determine the amount of oligomer in DMF, and this value is divided by the film area in contact with DMF to obtain the amount of oligomer on the film surface (mg / m ² ). To do. The amount of oligomer in DMF was determined from the peak area ratio between the standard sample peak area and the measured sample peak area (absolute calibration curve method). The standard sample was prepared by accurately weighing an oligomer (cyclic trimer) collected in advance and dissolving it in accurately measured DMF. The concentration of the standard sample is preferably in the range of 0.001 mg / ml to 0.01 mg / ml.
The conditions of the liquid chromatograph were as follows.
Mobile phase A: Acetonitrile Mobile phase B: 2% acetic acid aqueous solution Column: MCI GEL ODS 1HU manufactured by Mitsubishi Chemical Corporation
Column temperature: 40 ° C
Flow rate: 1 ml / min Detection wavelength: 254 nm

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

(8) Practical properties <Visual inspection under crossed Nicols>
A release agent is applied onto the film and the release film is obtained via an adhesive so that the width direction of the release film obtained under conditions of a dryer temperature of 120 ° C. and a line speed of 30 m / min is parallel to the orientation axis of the polarizing film. The polarizing film is adhered to the polarizing film to form a polarizing plate, and the polarizing plate for inspection is superimposed on the releasing film so that the orientation axis is orthogonal to the film width direction, and irradiated with white light from the polarizing plate side, It visually observed from the polarizing plate for a test | inspection, and the visual testability under cross nicol was evaluated according to the following reference | standard. In the measurement, A4 size samples were cut out from a total of three locations in the center and both ends in the width direction of the obtained film.
"Criteria"
○: Inspection is possible without optical interference. Δ: Optical interference is present but inspection is possible. ×: Optical interference is present and inspection is not possible. ○ and Δ are at a level where there is no problem in actual use.

<Release properties>
The release characteristics were evaluated from the situation when the release film was peeled off from the laminated film having the adhesive layer.
○: The release film is peeled off cleanly, and the phenomenon that the adhesive adheres to the release layer is not observed. Δ: The release film peels off, but the adhesive adheres to the release layer when peeled off at a high speed. : Adhesive adheres to the release film

<Roll contamination status>
When a laminated film having an adhesive layer was produced, in a laminating apparatus to be bonded to a polarizing plate, the roll contacting the surface opposite to the release layer was visually observed to evaluate the state of contamination of the roll by the oligomer.
○: No deposits are observed on the roll surface after production.
Δ: Slight deposits are observed on the roll surface after production, but there is no problem in production.
X: Deposits are observed on the roll surface after production, and roll cleaning is required.

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

<Manufacture of polyester (B)>
In the method for producing polyester (A), after adding ethyl acid phosphate, an ethylene glycol slurry of synthetic calcium carbonate particles having an average particle diameter of 0.8 μm was added so that the content of the particles with respect to the polyester was 1% by weight. Obtained polyester (B) using the method similar to the manufacturing method of polyester (A). The obtained polyester (B) had an intrinsic viscosity of 0.60.

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

<Manufacture of polyester (D)>
Starting from 100 parts by weight of dimethyl terephthalate and 60 parts by weight of ethylene glycol, magnesium acetate tetrahydrate is added as a catalyst to the reactor, the reaction start temperature is 150 ° C., and the reaction temperature is gradually increased as methanol is distilled off. The temperature was raised to 230 ° C. after 3 hours. After 4 hours, the transesterification reaction was substantially terminated. Ethyl acid phosphate was added to the reaction mixture, which was then transferred to a polycondensation tank, and 0.04 part of antimony trioxide was added to carry out a polycondensation reaction for 4 hours. That is, the temperature was gradually raised from 230 ° C. to 280 ° C. On the other hand, the pressure was gradually reduced from normal pressure, and finally 0.3 mmHg. After the start of the reaction, the reaction was stopped at a time corresponding to an intrinsic viscosity of 0.45 due to a change in stirring power of the reaction tank, and the polymer was discharged under nitrogen pressure to obtain a polyester chip (D). The intrinsic viscosity of this polyester was 0.45.

<Manufacture of polyester (E)>
The intrinsic viscosity of this polyester chip was increased by a solid phase polycondensation method. After treatment in a preliminary crystallization tank at 170 ° C. in a nitrogen atmosphere for 0.5 hours, the moisture content becomes 0.005% at a temperature of 200 ° C. using a tower dryer that flows an inert gas. Until dried. Thereafter, it was sent to a solid phase polymerization tank and subjected to solid phase polymerization at 240 ° C. for 3 hours to obtain a polyester (E) having an intrinsic viscosity of 0.70.

<Manufacture of polyester (F)>
When producing the polyester (E), solid phase polymerization was performed in a solid phase polymerization tank for 5 hours to obtain a polyester (F) having an intrinsic viscosity of 0.80.

<Manufacture of polyester (G)>
When producing polyester (E), solid phase polymerization was performed in a solid phase polymerization tank for 9 hours to obtain polyester (F) having an intrinsic viscosity of 0.90.

・ Polyester film-1
As a raw material for the surface layer, 70% by weight of polyester (F) and 30% by weight of polyester (B) are mixed, and as a raw material for the intermediate layer, 84% by weight of polyester (A) and 16% by weight of polyester (B) are mixed. Each was supplied to an extruder with a vent and melt-extruded at 290 ° C., and then cooled and solidified on a cooling roll having a surface temperature set to 40 ° C. using an electrostatic application adhesion method to obtain an unstretched sheet. Next, the film was stretched 2.8 times in the longitudinal direction at 100 ° C., then subjected to a preheating step in a tenter and subjected to a transverse stretching of 5.1 times at 120 ° C., followed by heat treatment at 220 ° C. for 10 seconds, 4% relaxation was added in the width direction at 180 ° C. to obtain a master roll having a width of 4000 mm. A slit was made from a position of 1400 mm from the end of the master roll, and the core roll was wound up by 1000 m to obtain a polyester film-1. The total thickness of the obtained film was 38 μm, and the thickness of each layer was 4 μm / 30 μm / 4 μm.

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

・ Polyester film-3
In polyester film-1, polyester film-3 was obtained in the same manner as polyester film-1, except that the raw material composition was changed to raw material composition-3 shown in Table 1.

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

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

・ Polyester film-6
In polyester film-1, polyester film-6 was obtained in the same manner as polyester film-1, except that the raw material composition was changed to raw material composition-6 shown in Table 1.

・ Polyester film-7
In polyester film-1, polyester film-7 was obtained in the same manner as in production of polyester film-1, except that the stretching ratio in the longitudinal direction was changed to 2.9 times.

・ Polyester film-8
In the polyester film-1, a polyester film-8 was obtained in the same manner as the polyester film-1, except that the stretching ratio in the longitudinal direction was changed to 3.4 times and the stretching ratio in the width direction was changed to 4.2 times.

・ Polyester film-9
In polyester film-1, polyester film-9 was obtained in the same manner as polyester film-1, except that the raw material composition was changed to raw material composition-7 shown in Table 1.

・ Polyester film-10
In polyester film-1, polyester film-10 was obtained in the same manner as polyester film-1, except that the raw material composition was changed to raw material composition-8 shown in Table 1.

・ Polyester film-11
In polyester film-1, polyester film-11 was obtained in the same manner as polyester film-1, except that the raw material composition was changed to raw material composition-9 shown in Table 1.

Example 1;
On polyester film-1, a release agent comprising release agent composition A shown below was applied by a reverse gravure coating method so that the coating amount (after drying) was 0.1 g / m 2, and the dryer temperature was 120 ° C. A roll-shaped release film was obtained under the condition of a line speed of 30 m / min.
・ Releasing agent composition-A
Curing type silicone resin (KS-847H: manufactured by Shin-Etsu Chemical) 100 parts Curing agent (PL-50T: manufactured by Shin-Etsu Chemical) 1 part MEK / toluene mixed solvent (mixing ratio is 1: 1) 1500 parts

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

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

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

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

Example 6:
In Example 1, the release film was obtained like Example 1 except having changed the polyester film-1 into the polyester film-6.

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

Example 8:
A release film was obtained in the same manner as in Example 1 except that the release agent composition-A was changed to the release agent composition-B shown below in Example 1.
・ Releasing agent composition-B
Curing type silicone resin (KS-774: manufactured by Shin-Etsu Chemical) 100 parts Curing agent (PL-4: manufactured by Shin-Etsu Chemical) 10 parts MEK / toluene mixed solvent (mixing ratio is 1: 1) 1500 parts

Example 9:
A release film was obtained in the same manner as in Example 1 except that the release agent composition-A was changed to the release agent composition-C shown below in Example 1.
・ Release composition-C
Curable silicone resin (KS-723A: manufactured by Shin-Etsu Chemical) 100 parts Curable silicone resin (KS-723B: manufactured by Shin-Etsu Chemical) 5 parts Curing agent (PS-3: manufactured by Shin-Etsu Chemical) 5 parts MEK / toluene mixed solvent (mixed) The ratio is 1: 1) 1500 parts

Comparative Example 1:
In Example 1, the release film was obtained like Example 1 except having changed the polyester film-1 into the polyester film-8.

Comparative Example 2:
In Example 1, the release film was obtained like Example 1 except having changed the polyester film-1 into the polyester film-9.

Comparative Example 3:
In Example 1, a release film was obtained in the same manner as in Example 1 except that the polyester film-1 was changed to the polyester film-10.

Comparative Example 4:
In Example 1, a release film was obtained in the same manner as in Example 1 except that the polyester film-1 was changed to the polyester film-11.

<Manufacture of polarizing plate with release film>
The acrylic adhesive shown below is applied to the polarizing plate so that the thickness after drying is 25 μm, and after passing through a 130 ° C. drying oven in 30 seconds, the release film is bonded, and the adhesive is interposed. Thus, a polarizing plate with a release film in which the release film and the polarizing film were adhered to each other was prepared. The laminating direction of the film was performed so that the width direction of the release film was parallel to the orientation axis of the polarizing film.
Acrylic adhesive coating solution Acrylic adhesive (Olivein BPS429-4: manufactured by Toyo Ink) 100 parts Curing agent (BPS8515: manufactured by Toyo Ink) 3 parts MEK / toluene mixed solvent (mixing ratio is 1: 1) 50 parts Each Example The evaluation results of the films obtained in Comparative Examples are summarized in Tables 2 to 4 below.

  The biaxially oriented polyester film of the present invention and a release film using the same can be suitably used, for example, as a release film for a liquid crystal polarizing plate.

Claims (2)

A biaxially oriented polyester film characterized in that the orientation of the orientation main axis is 11 degrees or less, the film haze value is 10 to 25%, and the intrinsic viscosity of the polyester constituting at least one surface layer is 0.65 or more. . A release film having a release layer on one surface of the biaxially oriented polyester film according to claim 1, wherein the release force of the release layer is in the range of 10 to 100 mN / cm, and the opposite surface of the release layer. A release film, wherein the polyester constituting the surface layer is a polyester layer having an intrinsic viscosity of 0.65 or more.