JP2013097279A - Circularly polarizing plate, method for manufacturing circularly polarizing plate, and an organic electroluminescence display device using circularly polarizing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circularly polarizing plate superior in curl resistance, the manufacturing method thereof, and an organic electroluminescence display device using the circularly polarizing plate and having less light leakage.SOLUTION: The circularly polarizing plate has a λ/4 retardation film (A), a polarizer, and a λ/4 retardation film (B) laminated in this order, and an angle formed between slow axes of respective λ/4 retardation films and an absorption axis of the polarizer is 45°. Each λ/4 retardation film is a stretched-polymer retardation film showing positive intrinsic birefringence, and an angle formed between the slow axes of the λ/4 retardation film (A) and the λ/4 retardation film (B) is 5° or less.

Description

  The present invention relates to a circularly polarizing plate, a method for producing a circularly polarizing plate, and an organic electroluminescence display device using the circularly polarizing plate.

  In recent years, stereoscopic image display devices such as televisions capable of displaying stereoscopic (3D) images have been proposed. As one of the methods for displaying the stereoscopic image, there is a method for allowing the observer to recognize the two-dimensional image as a stereoscopic image by wearing dedicated stereoscopic image viewing glasses by the observer. What is currently viewed as promising in this method is that the right-eye image and the left-eye image, which are parallax images, are alternately displayed in time series on the display that displays the image, and the observer uses glasses for viewing stereoscopic images. This is a method in which an image of a display is viewed while wearing (see, for example, Patent Document 1).

  The stereoscopic image display device including the display and the glasses for visually recognizing stereoscopic images has problems such as crosstalk (a phenomenon that appears double), a decrease in luminance, and a change in color when the head is tilted.

  In order to prevent the occurrence of such problems when the head is tilted, a λ / 4 plate (hereinafter referred to as a λ / 4 phase difference film) is provided on the surface on the viewing side of the display and the surface on the side far from the eyes of the stereoscopic image viewing glasses. Is also effective.

  In addition, for the purpose of preventing external light reflection of the organic electroluminescence display device, use of a circularly polarizing plate made of a combination of a λ / 4 plate and an absorption polarizer has been proposed (for example, see Patent Document 2).

  In the case of stereoscopic display using an organic electroluminescence display device, a λ / 4 retardation film, an absorptive polarizer, and a λ / 4 retardation having both the above-described antireflection function and the three-dimensional display image quality improvement function. A circularly polarizing plate having a film configuration is desired. However, when the circularly polarizing plate having such a configuration is manufactured by a conventional roll-to-roll bonding method, there is a problem that curl is large and a change in curl value with respect to humidity fluctuation is large.

  Further, the organic electroluminescence display device using the circularly polarizing plate has a problem that light leaks when the humidity changes.

Japanese Patent Laid-Open No. 8-201942 JP 2010-151910 A

  The present invention has been made in view of the above problems and circumstances, and a problem to be solved is to provide a circularly polarizing plate having excellent curl resistance. Another object of the present invention is to provide a manufacturing method thereof and an organic electroluminescence display device using the circularly polarized light with less light leakage.

  In order to solve the above-mentioned problems, the present inventor has examined the cause of the above-mentioned problems by paying attention to the anisotropy of elastic deformation during continuous production in a stretchable phase difference film. As a result, the λ / 4 phase difference film (A ), Absorption polarizer, and λ / 4 retardation film (B) laminated in this order, the retardation of λ / 4 retardation film (A) and λ / 4 retardation film (B) The inventors found that the angle formed by the axes is within 5 ° has a great effect on the curling resistance and the light leakage of the organic electroluminescence display device.

That is, the said subject which concerns on this invention is solved by the following means.
1. A λ / 4 retardation film (A), a polarizer, and a λ / 4 retardation film (B) are laminated in this order. The slow axis of each λ / 4 retardation film and the absorption axis of the polarizer And each λ / 4 retardation film is a polymer stretched retardation film exhibiting positive intrinsic birefringence, and the λ / 4 retardation film ( A circularly polarizing plate, wherein the angle formed by the slow axis between A) and the λ / 4 retardation film (B) is 5 ° or less.
2. Both the λ / 4 retardation film (A) and the λ / 4 retardation film (B) are cellulose ester resin films containing a plasticizer, and both in the thickness direction of the λ / 4 retardation film. 2. The circularly polarizing plate according to item 1 above, wherein both surfaces having a high plasticizer content ratio are disposed on the polarizer side or both on the side far from the polarizer.
3. 3. The circularly polarizing plate according to item 2, wherein both surfaces of the retardation film having a high plasticizer content ratio in the thickness direction are arranged on the side far from the polarizer.
4). It is a manufacturing method of the circularly-polarizing plate of the above-mentioned paragraph 2 or paragraph 3, Comprising: After producing an original fabric film, each original fabric film is a side with a high plasticizer content ratio in the thickness direction, A circularly polarized light characterized in that a λ / 4 retardation film (A) and a λ / 4 retardation film (B) are produced by obliquely stretching the original film with one on top and the other on the bottom. A manufacturing method of a board.
5. After producing the original film, each original film is stretched obliquely with the surface having the higher plasticizer content ratio in the thickness direction, one on the upper side and the other on the lower side. 5. The circularly polarizing plate according to item 4, wherein the λ / 4 retardation film (A) and the λ / 4 retardation film (B) each have an orientation angle of 45 °. Production method.
6). An organic electroluminescence display device using the circularly polarizing plate according to any one of items 1 to 3.

  The above means of the present invention can provide a circularly polarizing plate having excellent curl resistance. In addition, the manufacturing method and an organic electroluminescence display device with less light leakage using the circularly polarized light can be provided.

  The expression mechanism or action mechanism of the effect of the present invention is presumed as follows.

  When a protective film for a circularly polarizing plate (λ / 4 retardation films (A) and (B) in the present invention) and a polarizer are bonded together in a long length, a tension for conveyance is imparted to the retardation film. Therefore, although it is bonded in a state where elastic deformation has occurred, dimensional shrinkage occurs from the elastically deformed state after bonding. By aligning the slow axis direction of the two circularly polarizing plate protective films within 5 °, the dimensional shrinkage that occurs anisotropically can be matched with the upper and lower circularly polarizing plate protective films, and the curling resistance of the polarizing plate Can be improved.

It is a schematic diagram regarding a circularly-polarizing plate and a λ / 4 retardation film. It is a schematic diagram regarding the diagonal stretch apparatus in connection with this invention. It is a schematic diagram regarding an organic electroluminescent display apparatus.

  In the circularly polarizing plate of the present invention, a λ / 4 retardation film (A), a polarizer, and a λ / 4 retardation film (B) are laminated in this order, and the retardation of each λ / 4 retardation film. A circularly polarizing plate having an angle of 45 ° between the axis and the absorption axis of the polarizer, each λ / 4 retardation film is a polymer stretched retardation film exhibiting positive intrinsic birefringence, and The angle formed by the slow axis of the λ / 4 retardation film (A) and the λ / 4 retardation film (B) is 5 ° or less. This feature is a technical feature common to the inventions according to claims 1 to 6.

  In the circularly polarizing plate of the present invention, the λ / 4 retardation film (A) and the λ / 4 retardation film (B) are both cellulose ester resin films containing a plasticizer, and both λ / 4 From the viewpoint of curling fluctuation resistance due to humidity fluctuations, it is preferable that both surfaces having a higher plasticizer content ratio in the thickness direction of the retardation film are arranged on the polarizer side or on the side far from the polarizer. More preferably, both are arranged on the side far from the polarizer.

  The manufacturing method of the circularly polarizing plate is as follows. After the raw film is prepared, the surface with the higher plasticizer content ratio in the thickness direction of each original film is placed in the state where one side is on and the other side is on the lower side. The anti-film is obliquely stretched to produce the λ / 4 retardation film (A) and the λ / 4 retardation film (B), so that the λ / 4 retardation film (A) and λ / It is preferable because a roll set with the four retardation film (B) can be easily continuously produced.

  In the manufacturing method of the circularly polarizing plate, after producing the original film, each original film has a surface with a higher plasticizer content ratio in the thickness direction, one on the upper side and the other on the lower side. It is preferable that the orientation angles when producing the λ / 4 retardation film (A) and the λ / 4 retardation film (B) by obliquely stretching the original film are 45 °.

  The organic electroluminescence display device of the present invention can be suitably provided.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" is used in the meaning which includes the numerical value described before and behind that as a lower limit and an upper limit.

<Λ / 4 retardation film>
In the circularly polarizing plate of the present invention, a λ / 4 retardation film (A), a polarizer, and a λ / 4 retardation film (B) are laminated in this order, and the retardation of each λ / 4 retardation film. A circularly polarizing plate having an angle of 45 ° between the axis and the absorption axis of the polarizer, each λ / 4 retardation film is a polymer stretched retardation film exhibiting positive intrinsic birefringence, and The angle formed by the slow axis of the λ / 4 retardation film (A) and the λ / 4 retardation film (B) is 5 ° or less.

  The expression mechanism or action mechanism of the effect of the present invention is presumed as follows.

  Continuous production of a circularly polarizing plate is an absorption type so as to be disposed between two protective films for a long circularly polarizing plate (in the present invention, λ / 4 retardation films (A) and (B)). The polarizer is fed out at the same time, and the three films are bonded with an adhesive. Since the protective film for a circularly polarizing plate is a polymer stretched phase difference film having positive intrinsic birefringence, its elastic modulus has anisotropy in the plane. Since tension for conveyance is applied to the retardation film in the process from unwinding to bonding, the film is bonded in a state where elastic deformation has occurred, but when the tension disappears after bonding, the elastic deformation state changes to the normal state. Dimensional shrinkage occurs. Matching the direction of the slow axis of the two circularly polarizing plate protective films to within 5 ° means that the dimensional shrinkage that occurs anisotropically is matched between the upper and lower circularly polarizing plate protective films, thereby reducing the curl resistance of the polarizing plate. Can be improved.

  The material of the λ / 4 retardation film described in the present invention is not particularly limited, but cellulose ester can be used from the viewpoint of wavelength dispersion characteristics, adhesiveness to a polarizer, and transparency.

  Especially, it is preferable to contain the cellulose acylate which satisfy | fills following formula (1) and (2) from a viewpoint of suppression of the phase dispersion variation with respect to a wavelength dispersion characteristic and humidity.

Equation _{(1) 2.0 ≦ Z 1 <} 3.0
Formula (2) 0.5 <= X
(In formulas (1) and (2), Z ₁ represents the total acyl group substitution degree of cellulose acylate, and X represents the sum of the propionyl group substitution degree and butyryl group substitution degree of cellulose acylate.)
The “λ / 4 retardation film” described in the present invention means a film having a function of converting linearly polarized light having a specific wavelength into circularly polarized light (or circularly polarized light into linearly polarized light). The λ / 4 retardation film has an in-plane retardation value Ro of about ¼ for a predetermined wavelength of light (usually in the visible light region).

  In the λ / 4 retardation film according to the present invention, Ro (550) measured at a wavelength of 550 nm is preferably in the range of 110 to 170 nm, Ro (550) is preferably 120 to 160 nm, and Ro (550) is 130. More preferably, it is ˜150 nm.

  The λ / 4 retardation film according to the present invention has a retardation plate having a retardation of approximately ¼ of the wavelength in the visible light wavelength range in order to obtain almost perfect circularly polarized light in the visible light wavelength range ( Film).

  “Retardation of approximately ¼ in the wavelength range of visible light” is a retardation value expressed by the following formula (3) measured at a wavelength of 450 nm, with a larger retardation at a wavelength of 400 to 700 nm. The ratio Ro (450) / Ro (550), which is a retardation value measured at a wavelength of 550 nm and a certain Ro (450), has a value of 0.72 to 0.92 for blue reproduction. It is preferably 0.77 to 0.87. Moreover, the value of the ratio Ro (550) / Ro (650) between Ro (550), which is a retardation value measured at a wavelength of 550 nm, and Ro (650), which is a retardation value measured at a wavelength of 650 nm, is 0.84 to 0.97 is preferable for red reproduction, and 0.84 to 0.92 is particularly preferable.

Formula (3): Ro = (nx−ny) × d
In the formula, nx and ny are the refractive index nx (also referred to as the maximum refractive index in the plane of the film and the refractive index in the slow axis direction) at 23 ° C./55% RH, 450 nm, 550 nm or 650 nm, ny (film). (Refractive index in a direction perpendicular to the slow axis in the plane), and d is the thickness (nm) of the film.

  Ro and Rt can be measured using an automatic birefringence meter. Using an automatic birefringence meter KOBRA-WPR (manufactured by Oji Scientific Instruments), Ro is calculated by birefringence measurement at each wavelength in an environment of 23 ° C. and 55% RH.

  A circularly polarizing plate is obtained by laminating so that the angle between the slow axis of the λ / 4 retardation film and the transmission axis of the polarizer described later is 45 °. “45 °” means 45 ± 5 °. The angle between the slow axis in the plane of the λ / 4 retardation film and the transmission axis of the polarizer is preferably 41 to 49 °, more preferably 42 to 48 °, and 43 to 47 °. More preferably, it is most preferably 44 to 46 °.

<Curl fluctuation due to humidity fluctuation of circularly polarizing plate>
In addition to adjusting the direction of the slow axis of the above-mentioned two circularly polarizing plate protective films to within 5 ° in the light leakage improvement under the environmental change of the organic electroluminescence device having the circularly polarizing plate, the circularly polarizing plate We also paid attention to the rate of dimensional change accompanying the moisture absorption and desorption of the protective film and the magnitude of the stress generated thereby. When the moisture absorption of the polarizing plate protective film placed under humidity fluctuation is suppressed, the change in dimensions is moderated. The gradual dimensional change is considered to reduce the stress applied to the polarizer and suppress the alignment disorder of the polarizer. Thereby, suppression of the light leakage under an environmental change can be achieved.

  That is, it has been found that the curl fluctuation due to the humidity fluctuation of the circularly polarizing plate can be further improved by improving the uniformity of the moisture absorption rate in the film thickness direction. Under the humidity fluctuation condition, the moisture in the two circularly polarizing plate protective films is released into the air or the moisture is taken in from the air, so that the polarizing plate protective film contracts or expands. At this time, if there is a difference in the rate of absorption / release, curling fluctuation of the polarizing plate protective film under environmental fluctuation will be caused. By arranging the plasticizer content ratio in the thickness direction of the circularly polarizing plate protective film symmetrically in the thickness direction of the circularly polarizing plate, the rate of moisture absorption and desorption can be controlled uniformly, and the humidity of the circularly polarizing plate Curl fluctuation due to fluctuations can be further suppressed.

  Hereinafter, both λ / 4 retardation film (A) and λ / 4 retardation film (B), which are preferred embodiments, are cellulose esters containing a plasticizer, and the thickness of both λ / 4 retardation films. The case where the surface side with a high plasticizer content ratio in the direction is arranged on both the polarizer side or the side far from the polarizer will be described with reference to the drawings.

  In the continuous production of circularly polarizing plates, it is difficult to achieve the relationship between the plasticizer distribution in the thickness direction of two circularly polarizing plates and the slow axis of each film with a single type of polarizing film roll. This problem can be solved by using a roll set of two circularly polarizing plate protective films comprising the four retardation film (A) and the λ / 4 retardation film (B). This problem will be described with reference to the drawings. FIG. 1 is a schematic diagram regarding a circularly polarizing plate and a λ / 4 retardation film.

  FIG. 1 (1) pays attention to the combination of the plasticizer content ratios in the thickness direction of the λ / 4 retardation film (A) 1a and the λ / 4 retardation film (B) 2a having different plasticizer content ratios in the thickness direction. It is a schematic diagram showing the distribution. The thick line in the figure schematically represents a surface with a high plasticizer content ratio. From FIG. 1 (1), it can be seen that there are four types of patterns (1-1) to (1-4).

  1 (2) and 1 (3) are schematic diagrams that take into account the slow axis of the λ / 4 retardation film in addition to the plasticizer content ratio.

  As shown in FIG. 1 (2), the same film roll (A1) having a slow axis of 45 ° when the λ / 4 retardation film is measured with the surface having a high plasticizer content ratio on the upper side, ( Prepare B1). When (A1) and (B1) are fed out and continuously bonded, the results of (A1 + B1), (A1 + B1R), (A1R + B1), (A1R + B1R) are the results of bonding with the front and back surfaces of (A1) and (B1) replaced. There are four categories. The symbol R indicates that the front and back surfaces are exchanged. In any of the classifications, it is not possible to achieve an arrangement in which the direction of the slow axis is parallel and symmetrical with respect to the thickness direction in which the plasticizer distribution is bonded. In FIG. 1 (2), the upper part represents the film roll A1, and the lower part represents the film roll B1.

  Similarly, as apparent from FIG. 1 (3), in the film roll combinations (C1 + D1R) and (C1R + D1), the slow axes of the two circularly polarizing plate protective films are parallel, and the thickness direction of the plasticizer An arrangement with a symmetric distribution was achieved. It is preferable to use a roll set of two circularly polarizing plate protective films comprising such a λ / 4 retardation film (A) and a λ / 4 retardation film (B). In FIG. 1 (3), the upper part represents the film roll C1, and the lower part represents the film roll D1.

(Plasticizer)
In the λ / 4 retardation film according to the present invention, it is preferable to add at least one plasticizer in the film. The plasticizer is generally an additive having an effect of improving brittleness, decreasing melt viscosity, or imparting flexibility by being added to a polymer. In the case of the resin according to a preferred embodiment, the resin is added to improve the hydrophilicity of the cellulose ester and the moisture permeability of the optical film, and thus has a function as a moisture permeation preventive agent.

  The λ / 4 retardation film according to the present invention is preferably a polyester resin shown below, a compound represented by the general formula (PEI), a compound represented by the general formula (PEII), or a carboxylic acid sugar ester compound as a plasticizer. Can be contained.

<Polyester resin>
The polyester resin that can be used in the present invention is obtained by polymerizing a dicarboxylic acid and a diol, and 70% or more of dicarboxylic acid structural units (constituent units derived from dicarboxylic acid) are derived from aromatic dicarboxylic acid, and 70% or more of the diol constituent units (constituent units derived from the diol) are derived from the aliphatic diol.

  The proportion of the structural unit derived from the aromatic dicarboxylic acid is 70% or more, preferably 80% or more, more preferably 90% or more.

  The proportion of the structural unit derived from the aliphatic diol is 70% or more, preferably 80% or more, and more preferably 90% or more. Two or more polyester resins may be used in combination.

  Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, naphthalenedicarboxylic acid such as 2,7-naphthalenedicarboxylic acid, and 4,4′-biphenyldicarboxylic acid. 3,4'-biphenyldicarboxylic acid and the like and ester-forming derivatives thereof.

  As the polyester resin, aliphatic dicarboxylic acids such as adipic acid, azelaic acid, and sebacic acid, and monocarboxylic acids such as benzoic acid, propionic acid, and butyric acid can be used without departing from the object of the present invention.

  Examples of the aliphatic diol include ethylene glycol, 1,3-propylene diol, 1,4-butanediol, 1,4-cyclohexanedimethanol, 1,6-hexanediol, and the like, and ester-forming derivatives thereof.

  As the polyester resin, monoalcohols such as butyl alcohol, hexyl alcohol, and octyl alcohol, and polyhydric alcohols such as trimethylolpropane, glycerin, and pentaerythritol can be used as long as the object of the present invention is not impaired.

  A known esterification method or transesterification method can be applied to the production of the polyester resin. Examples of the polycondensation catalyst used in the production of the polyester resin include known antimony compounds such as antimony trioxide and antimony pentoxide, germanium compounds such as germanium oxide, titanium compounds such as titanium acetate, and aluminum compounds such as aluminum chloride. Although it can, it is not limited to these.

  Preferred polyester resins include polyethylene terephthalate resin, polyethylene terephthalate-isophthalate copolymer resin, polyethylene-1,4-cyclohexanedimethylene-terephthalate copolymer resin, polyethylene-2,6-naphthalene dicarboxylate resin, polyethylene-2, 6-naphthalene dicarboxylate-terephthalate copolymer resin, polyethylene-terephthalate-4,4'-biphenyldicarboxylate resin, poly-1,3-propylene-terephthalate resin, polybutylene terephthalate resin, polybutylene-2,6-naphthalene There are dicarboxylate resins and the like.

  More preferable polyester resins include polyethylene terephthalate resin, polyethylene terephthalate-isophthalate copolymer resin, polyethylene-1,4-cyclohexanedimethylene-terephthalate copolymer resin, polybutylene terephthalate resin, and polyethylene-2,6-naphthalene dicarboxylate. Resin.

  The intrinsic viscosity of the polyester resin (phenol / 1,1,2,2-tetrachloroethane = value measured at 25 ° C. in a 60/40 mass ratio mixed solvent) is preferably 0.7 to 2.0 dl / g, more Preferably it is 0.8-1.5 dl / g. Since the molecular weight of the polyester resin is sufficiently high when the intrinsic viscosity is 0.7 or more, the molded product comprising the polyester resin composition obtained by using the polyester resin has mechanical properties necessary for the molded product and is transparent. Property is improved. When the intrinsic viscosity is 2.0 or less, the moldability is good.

<Compound represented by formula (PEI): aromatic group-terminated polyester compound>
The λ / 4 retardation film according to the present invention includes a compound represented by the following general formula (PEI) (hereinafter also referred to as “aromatic group-terminated polyester compound”) and a cellulose ester resin. To do. In the present invention, by containing the compound represented by the general formula (PEI), the phase difference can be freely controlled, the control to the target λ / 4 phase difference is easy, and the hardness of the film is increased. The effect of improving the hardness when the applied hard coat or antiglare hard coat is surface-treated is obtained.

Formula (PEI): B- (GA) _n -GB
(B represents a benzene monocarboxylic acid residue. G represents an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue having 6 to 12 carbon atoms, or an oxyalkylene glycol residue having 4 to 12 carbon atoms. And A represents an alkylene dicarboxylic acid residue having 4 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms, and n represents an integer of 0 or more.)
In the general formula (PEI), an arylcarboxylic acid residue represented by B and an alkylene glycol residue or oxyalkylene glycol residue or arylglycol residue represented by G, an alkylenedicarboxylic acid residue represented by A or It is composed of an aryl dicarboxylic acid residue, and can be obtained by the same reaction as a normal polyester compound.

  Examples of the arylcarboxylic acid component of the aromatic group-terminated polyester compound used include benzoic acid, para-tert-butylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethylbenzoic acid, ethylbenzoic acid, and normalpropylbenzoic acid. , Aminobenzoic acid, acetoxybenzoic acid and the like, and these can be used as one kind or a mixture of two or more kinds, respectively.

  Examples of the alkylene glycol component having 2 to 12 carbon atoms of the aromatic group-terminated polyester compound that can be used include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1, 3-butanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol ( Neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane) ), 3-methyl-1,5-pentanediol 1,6-hexanediol, 2,2,4-trimethyl-1,3 There are pentanediol, 2-ethyl 1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, etc. Glycol is used as one or a mixture of two or more.

  In particular, an alkylene glycol having 2 to 12 carbon atoms is particularly preferable because of excellent compatibility with a cellulose ester.

  Examples of the oxyalkylene glycol component having 4 to 12 carbon atoms of the aromatic group-terminated polyester compound include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol. , One or a mixture of two or more.

  Examples of the alkylene dicarboxylic acid component having 4 to 12 carbon atoms of the aromatic group-terminated polyester compound include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid. These are used as one kind or a mixture of two or more kinds.

  Examples of the arylene dicarboxylic acid component having 6 to 12 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, and the like.

  In the aromatic group-terminated polyester compound used in the present invention, n is preferably 1 or more and 100 or less, and the number average molecular weight is preferably 300 to 1500, more preferably 400 to 1000. .

  The acid value is 0.5 mgKOH / g or less, the hydroxy (hydroxyl group) value is 25 mgKOH / g or less, more preferably the acid value is 0.3 mgKOH / g or less, and the hydroxy (hydroxyl group) value is 15 mgKOH / g or less. is there.

  The aromatic group-terminated polyester compound represented by the general formula (PEI) according to the present invention is preferably contained in an amount of 0.5 to 30% by mass with respect to the cellulose ester resin.

  Specific examples of the aromatic group-terminated polyester compound that can be used in the present invention are shown below, but the present invention is not limited thereto.

本発明に係るセルロースエステルフィルムは、位相差値の変動を抑制して、表示品位を安定化するために、糖エステル化合物を、セルロースエステルフィルムの０．５〜３０質量％含むことが好ましく、特には、５〜３０質量％含むことが好ましい。

The cellulose ester film according to the present invention preferably contains a sugar ester compound in an amount of 0.5 to 30% by mass of the cellulose ester film in order to suppress the fluctuation of the retardation value and stabilize the display quality. It is preferable to contain 5-30 mass%.

  The content of the aromatic group-terminated polyester compound represented by the general formula (PEI) and the sugar ester compound can be selected in a mass ratio of 99: 1 to 1:99, and the total amount of both compounds is It is preferable that it is 1-40 mass% with respect to cellulose-ester resin.

<Compound represented by formula (PEII): Hydroxyl-terminated polyester>
In the present invention, various polyester compounds conventionally contained in optical films can be used. For example, as the polyester compound, a polyester having a hydroxy group at the terminal portion of the chemical structural formula as represented by the following general formula (PEII) (referred to as “hydroxy group-terminated polyester”) can also be used.

（式中、Ｂは、炭素数が２〜６の直鎖又は分岐のアルキレン、又はシクロアルキレン基を表す。Ａは、炭素数が６〜１４の芳香族環を表す。ｎは、２以上の自然数を表す。）
上式で表される化合物は、芳香環を有するジカルボン酸（「芳香族ジカルボン酸」ともいう。）と、炭素数が２〜６の直鎖又は分岐のアルキレン又はシクロアルキレンジオールから得られ、両末端がモノカルボン酸で封止されていないことが特徴である。

(In the formula, B represents a linear or branched alkylene having 2 to 6 carbon atoms or a cycloalkylene group. A represents an aromatic ring having 6 to 14 carbon atoms. N is 2 or more. Represents a natural number.)
The compound represented by the above formula is obtained from a dicarboxylic acid having an aromatic ring (also referred to as “aromatic dicarboxylic acid”) and a linear or branched alkylene or cycloalkylene diol having 2 to 6 carbon atoms. The terminal is not sealed with a monocarboxylic acid.

  Examples of the aromatic dicarboxylic acid having 6 to 16 carbon atoms include phthalic acid, isophthalic acid, terephthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3- And naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,8-naphthalenedicarboxylic acid, 2,2'-biphenyldicarboxylic acid, 4,4'-biphenyldicarboxylic acid, and the like. Among these, 2,6-naphthalenedicarboxylic acid and 4,4′-biphenyldicarboxylic acid are preferable.

  Examples of the linear or branched alkylene or cycloalkylene diol having 2 to 6 carbon atoms include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, and 1,3-butanediol. 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanediol 1,4-cyclohexanedimethanol and the like. Among these, ethanediol, 1,2-propanediol, 1,3-propanediol, and 1,3-butanediol are preferable.

  Among these, A is preferably a naphthalene ring or a biphenyl ring which may have a substituent, from the viewpoint of obtaining the effects of the present invention. Here, the substituent is an alkyl group having 1 to 6 carbon atoms, an alkenyl group, or an alkoxyl group.

  The hydroxy (hydroxyl) value (OH value) of the polyester compound according to the present invention is preferably 100 mgKOH / g or more and 500 mgKOH / g or less, and more preferably 170 to 400 mgKOH / g. Whether the hydroxy (hydroxyl group) value is larger or smaller than this range, the compatibility with cellulose acetate having a low acetyl substitution degree is lowered.

  If it is larger than this range, the hydrophobicity of the polyester compound will increase, and if it is smaller than this range, the intermolecular interaction (hydrogen bonds, etc.) between the polyester compounds will be stronger, so that precipitation in the film will proceed. it is conceivable that.

  Moreover, the measurement of a hydroxy (hydroxyl group) value can apply the acetic anhydride method etc. of Japanese Industrial Standard JISK1557-1: 2007.

  The number average molecular weight (Mn) of the polyester compound can be calculated from the following formula.

Mn = (number of hydroxy groups in the molecule) × 56110 / (hydroxy (hydroxyl group) value)
= 2 × 56110 / (hydroxy (hydroxyl group) value)
Polyester compounds can be easily obtained by a conventional method, either a hot melt condensation method using a polyesterification reaction or a transesterification reaction between the dicarboxylic acid and a diol, or an interfacial condensation method between an acid chloride of these acids and a glycol. Can be synthesized.

  Below, the polyester compound which concerns on this invention is illustrated.

一般式（ＰＥII）で表される化合物はセルロースアセテートに対し、１質量％以上５質量％未満添加することが好ましい。

The compound represented by the general formula (PEII) is preferably added in an amount of 1% by mass to less than 5% by mass with respect to cellulose acetate.

(Carboxylic acid sugar ester compound)
The λ / 4 retardation film according to the present invention preferably contains a carboxylic acid sugar ester compound as a plasticizer. The said compound can acquire the effect that water resistance improves by containing compatibility with a cellulose excellently. Since it can be contained in a large amount, it is supplemented with this compound when water resistance is insufficient with other additives.

  In the present application, “carboxylic acid sugar ester compound” refers to a compound having an ester bond derived from a hydroxy group of a saccharide and a carboxy group of a carboxylic acid.

  Examples of the carboxylic acid structural unit constituting the carboxylic acid sugar ester compound include aromatic carboxylic acids such as methylbenzoic acid (toluic acid), aromatic substituted aliphatic carboxylic acids such as phenylacetic acid, and fatty acids such as stearic acid. These carboxylic acids may be substituted with an alkoxy group, an alkylthio group, a halogen atom, a cyano group or a nitro group.

  Examples of preferred aromatic carboxylic acids include aromatic monocarboxylic acids, cinnamic acid, benzylic acid, biphenylcarboxylic acid, naphthalenecarboxylic acid having an alkyl group or alkoxy group introduced into the benzene ring of benzoic acid such as benzoic acid or toluic acid. Examples thereof include aromatic monocarboxylic acids having two or more benzene rings such as acid and tetralincarboxylic acid, or derivatives thereof. More specifically, xylyl acid, hemelic acid, mesitylene acid, prenylic acid, γ -Isoduric acid, duryl acid, mesitic acid, α-isoduric acid, cumic acid, α-toluic acid, hydroatropic acid, atropic acid, hydrocinnamic acid, salicylic acid, o-anisic acid, m-anisic acid, p-anisic acid, Creosote acid, o-homosalicylic acid, m-homosalicylic acid, p-homosalicylic acid, o-pyrocatechuic acid β-resorcylic acid, vanillic acid, isovanillic acid, veratromic acid, o-veratrumic acid, gallic acid, asaronic acid, mandelic acid, homoanisic acid, homovanillic acid, homoveratrumic acid, o-homoveratrumic acid, phthalonic acid, p-coumaric acid Among them, benzoic acid is particularly preferable.

  Preferred aliphatic carboxylic acids include acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid, Tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, laccellic acid, etc., undecylen Examples thereof include unsaturated fatty acids such as acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid and octenoic acid.

  The saccharides constituting the carboxylic acid sugar ester compound usually include monosaccharides, disaccharides, and oligosaccharides in which 3 to 6 monosaccharides are bonded, and among them, the number of carbon atoms is 6 ~ 48 saccharides are preferred, and monosaccharides and disaccharides are more preferred. Specific examples of monosaccharides include glucose, fructose, arabinose, mannose, and sorbitol, and examples of disaccharides include sucrose and maltose. From the viewpoint of supplying raw materials, glucose, fructose and sucrose are particularly preferable, and sucrose is most preferable.

  These saccharides have a plurality of hydroxy groups in the molecule, and can form an ester bond with the carboxylic acid structural unit described above.

  In particular, when sucrose is used as a saccharide, there are 8 hydroxy groups in the sucrose molecule, but the average number of ester bonds (also referred to as “average ester substitution degree”) is 1.0 or more. What is necessary is just 3.0-7.5, More preferably, it is 3.0-6.0.

  In the present invention, it is particularly preferable to contain a compound represented by the following general formula (4) and having a total average substitution degree in the range of 3.0 to 6.0.

なお、一般式（４）中、Ｒ₁〜Ｒ₈は、水素原子、置換若しくは無置換のアルキルカルボニル基、又は、置換若しくは無置換のアリールカルボニル基を表し、Ｒ₁〜Ｒ₈は、同じであっても、異なっていてもよい。

In General Formula (4), R _{1 to} R ₈ represent a hydrogen atom, a substituted or unsubstituted alkylcarbonyl group, or a substituted or unsubstituted arylcarbonyl group, and R _{1 to} R ₈ are the same. It may or may not be.

Preferable specific examples of the compound represented by the general formula (4) include compounds shown in Table 1. In addition, R described in the following table represents any one of R _{1 to} R ₈ . As the substituent for the alkylcarbonyl group and the arylcarbonyl group, substituents such as a phenyl group and an alkoxy group included in the alkylcarbonyl group and the arylcarbonyl group shown in the following table are preferable.

  Although the compound represented by the said General formula (4) and a reference compound are described below, it is not limited to these.

（合成例：一般式（４）で表される化合物）

撹拌装置、還流冷却器、温度計及び窒素ガス導入管を備えた四頭コルベンに、ショ糖３４．２ｇ（０．１モル）、無水安息香酸１８０．８ｇ（０．８モル）、ピリジン３７９．７ｇ（４．８モル）を仕込み、撹拌下に窒素ガス導入管から窒素ガスをバブリングさせながら昇温し、７０℃で５時間エステル化反応を行った。次に、コルベン内を４×１０²Ｐａ以下に減圧し、６０℃で過剰のピリジンを留去した後に、コルベン内を１．３×１０Ｐａ以下に減圧し、１２０℃まで昇温させ、無水安息香酸、生成した安息香酸の大部分を留去した。そして、次にトルエン１Ｌ、０．５質量％の炭酸ナトリウム水溶液３００ｇを添加し、５０℃で３０分間撹拌後、静置して、トルエン層を分取した。最後に、分取したトルエン層に水１００ｇを添加し、常温で３０分間水洗後、トルエン層を分取し、減圧下（４×１０²Ｐａ以下）、６０℃でトルエンを留去させ、化合物Ａ−１、Ａ−２、Ａ−３、Ａ−４及びＡ−５の混合物を得た。得られた混合物をＨＰＬＣ及びＬＣ−ＭＡＳＳで解析したところ、Ａ−１が７質量％、Ａ−２が５８質量％、Ａ−３が２３質量％、Ａ−４が９質量％、Ａ−５が３質量％であった。なお、得られた混合物の一部を、シリカゲルを用いたカラムクロマトグラフィーにより精製することで、それぞれ純度１００％のＡ−１、Ａ−２、Ａ−３、Ａ−４及びＡ−５を得た。

(Synthesis Example: Compound Represented by General Formula (4))

A four-headed colben equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet tube was mixed with 34.2 g (0.1 mol) of sucrose, 180.8 g (0.8 mol) of benzoic anhydride, 379. 7 g (4.8 mol) was charged, the temperature was raised while bubbling nitrogen gas from a nitrogen gas introduction tube with stirring, and an esterification reaction was carried out at 70 ° C. for 5 hours. Next, the inside of the Kolben was depressurized to 4 × 10 ² Pa or less, and after excess pyridine was distilled off at 60 ° C., the inside of the Kolben was depressurized to 1.3 × 10 Pa or less and the temperature was raised to 120 ° C. Most of the acid and benzoic acid formed were distilled off. Then, 1 L of toluene and 300 g of a 0.5% by mass aqueous sodium carbonate solution were added, and the mixture was stirred at 50 ° C. for 30 minutes and then allowed to stand to separate a toluene layer. Finally, 100 g of water is added to the collected toluene layer, and after washing with water at room temperature for 30 minutes, the toluene layer is separated, and the toluene is distilled off at 60 ° C. under reduced pressure (4 × 10 ² Pa or less). A mixture of A-1, A-2, A-3, A-4 and A-5 was obtained. When the obtained mixture was analyzed by HPLC and LC-MASS, A-1 was 7% by mass, A-2 was 58% by mass, A-3 was 23% by mass, A-4 was 9% by mass, A-5. Was 3% by mass. A part of the obtained mixture was purified by column chromatography using silica gel to obtain A-1, A-2, A-3, A-4 and A-5 having a purity of 100%, respectively. It was.

  The total average substitution degree of the compound represented by the general formula (1) added to the λ / 4 retardation film in the present invention is 3.0 to 7.5, but the range of the substitution degree is 3.0. It is preferably ˜6.0. The substitution degree distribution may be adjusted to the desired substitution degree by adjusting the esterification reaction time or mixing compounds having different substitution degrees.

(Other additives)
The λ / 4 retardation film according to the present invention can contain various compounds as additives in addition to the plasticizer. For example, a retardation developing agent, an antioxidant, an acid scavenger, a light stabilizer, an ultraviolet absorber, an optical anisotropy control agent, a matting agent, an antistatic agent, a release agent, and the like can be contained.

(Phase difference agent)
In the present invention, a retardation (also referred to as “retardation”) developing agent may be included. A phase difference (retardation) developing agent can be contained, for example in the ratio of 0.5-10 mass%, and it is preferable to make it contain in the ratio of 2-6 mass% further. By adopting a retardation developing agent, high Re developability can be obtained at a low draw ratio. The type of retardation developing agent is not particularly defined, but examples thereof include those made of rod-like or discotic compounds. As the rod-like or discotic compound, a compound having at least two aromatic rings can be preferably used as a retardation developing agent. The addition amount of the retardation developing agent composed of the rod-shaped compound is preferably 0.5 to 10 parts by mass, and 2 to 6 parts by mass with respect to 100 parts by mass of the polymer component containing the cellulose ester. Is more preferable.

  The discotic retardation developing agent is preferably used in a range of 0.5 to 10 parts by mass, and in a range of 1 to 8 parts by mass with respect to 100 parts by mass of the polymer component containing the cellulose ester. It is more preferable to use in the range of 2 to 6 parts by mass.

  Two or more kinds of retardation developing agents may be used in combination.

  The phase difference (retardation) developing agent preferably has maximum absorption in the wavelength region of 250 to 400 nm, and preferably has substantially no absorption in the visible region.

  The discotic compound will be described. As the discotic compound, a compound having at least two aromatic rings can be used.

  Here, the “aromatic ring” includes an aromatic heterocycle in addition to an aromatic hydrocarbon ring.

  The aromatic hydrocarbon ring is particularly preferably a 6-membered ring (that is, a benzene ring).

  The aromatic heterocycle is generally an unsaturated heterocycle. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable. Examples of aromatic heterocycles include furan ring, thiophene ring, pyrrole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, furazane ring, triazole ring, pyran ring, pyridine ring , Pyridazine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring.

  As the aromatic ring, a benzene ring, a condensed benzene ring, and biphenyls are preferable. In particular, a 1,3,5-triazine ring is preferably used. Specifically, for example, compounds disclosed in JP-A No. 2001-166144 are preferably used.

  The number of carbon atoms of the aromatic ring contained in the retardation developing agent is preferably 2-20, more preferably 2-12, further preferably 2-8, and 2-6. Most preferably.

<Ultraviolet absorber>
The λ / 4 retardation film according to the present invention can also contain an ultraviolet absorber. The ultraviolet absorber is intended to improve durability by absorbing ultraviolet rays of 400 nm or less, and in particular, the transmittance at a wavelength of 370 nm is preferably 10% or less, more preferably 5% or less, and further Preferably it is 2% or less.

  The ultraviolet absorber is not particularly limited, and examples thereof include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex compounds, inorganic powders, and the like. It is done.

  For example, 5-chloro-2- (3,5-di-sec-butyl-2-hydroxyphenyl) -2H-benzotriazole, (2-2H-benzotriazol-2-yl) -6- (linear and side Chain dodecyl) -4-methylphenol, 2-hydroxy-4-benzyloxybenzophenone, 2,4-benzyloxybenzophenone, etc., and tinuvin 109, tinuvin 171 There are tinuvins such as tinuvin 928, and these are all commercially available products from BASF Japan and can be preferably used.

  The UV absorbers preferably used in the present invention are benzotriazole UV absorbers, benzophenone UV absorbers, and triazine UV absorbers, particularly preferably benzotriazole UV absorbers and benzophenone UV absorbers. .

  In addition, a discotic compound such as a compound having a 1,3,5-triazine ring is also preferably used as the ultraviolet absorber.

  In this invention, it is preferable that a cellulose-ester solution contains 2 or more types of ultraviolet absorbers. As the UV absorber, a polymer UV absorber can also be preferably used, and in particular, a polymer type UV absorber described in JP-A-6-148430 is preferably used.

  The method of adding the UV absorber can be added to the dope after dissolving the UV absorber in an alcohol such as methanol, ethanol or butanol, an organic solvent such as methylene chloride, methyl acetate, acetone or dioxolane or a mixed solvent thereof. Or you may add directly in dope composition.

  For an inorganic powder that does not dissolve in an organic solvent, a dissolver or a sand mill is used in the organic solvent and cellulose ester to disperse and then added to the dope.

  The amount of UV absorber used is not uniform depending on the type of UV absorber, operating conditions, etc., but when the dry film thickness of the λ / 4 retardation film is 30 to 200 μm, 0.5-10 mass% is preferable, and 0.6-4 mass% is still more preferable.

<Antioxidant>
The antioxidant plays a role of delaying or preventing the decomposition of the λ / 4 retardation film by, for example, the residual solvent amount of halogen in the λ / 4 retardation film or phosphoric acid of the phosphoric acid plasticizer. Therefore, it is preferably contained in the λ / 4 retardation film.

  As such an antioxidant, a hindered phenol compound is preferably used. For example, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di- -T-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3 -(3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino)- 1,3,5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octa Sil-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide) 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-t-butyl-4-hydroxy Benzyl) -isocyanurate and the like.

  In particular, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3 -(3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] is preferred. Further, for example, hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di- A phosphorus processing stabilizer such as t-butylphenyl) phosphite may be used in combination.

  The addition amount of these compounds is preferably 1 ppm to 1.0%, more preferably 10 to 1000 ppm in terms of mass ratio with respect to the total mass of the polymer (A) and the cellulose ester.

(Matting agent)
The thermoplastic resin substrate according to the present invention may be added with fine particles as a matting agent in order to prevent scratching or deterioration of transportability when the produced film is handled. preferable.

  As fine particles, examples of inorganic compounds include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, Examples thereof include magnesium silicate and calcium phosphate. Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable.

  The average primary particle diameter of the fine particles is preferably 5 to 400 nm, and more preferably 10 to 300 nm. These may be mainly contained as secondary aggregates having a particle size of 0.05 to 0.3 μm, and may be contained as primary particles without being aggregated if the particles have an average particle size of 80 to 400 nm. preferable. The content of these fine particles in the film is preferably 0.01 to 1% by mass, particularly preferably 0.05 to 0.5% by mass. In the case of a λ / 4 retardation film having a multilayer structure formed by the co-casting method, it is preferable to contain fine particles of this addition amount on the surface.

  Silicon dioxide fine particles are commercially available, for example, under the trade names Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above Nippon Aerosil Co., Ltd.). it can.

  Zirconium oxide fine particles are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) and can be used.

  Examples of the resin include a silicone resin, a fluororesin, and an acrylic resin. Silicone resins are preferable, and those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, 105, 108, 120, 145, 3120, and 240 (manufactured by Toshiba Silicone Co., Ltd.) It is marketed by name and can be used.

  Among these, Aerosil 200V and Aerosil R972V are particularly preferably used because they have a large effect of reducing the friction coefficient while keeping the haze of the λ / 4 retardation film low. In the λ / 4 retardation film according to the present invention, the dynamic friction coefficient of at least one surface is preferably 0.2 to 1.0.

<Method for producing circularly polarizing plate>
In the manufacturing method of the circularly polarizing plate of the present invention, after producing the raw film, each of the original films has the surface with the higher plasticizer content ratio in the thickness direction, one on the upper side and the other on the lower side. It is preferable to produce the λ / 4 retardation film (A) and the λ / 4 retardation film (B) by obliquely stretching the original film in the state. When produced in this way, as described above, the plasticizer content ratio is symmetric with respect to the polarizer in the thickness direction, and the λ / 4 retardation film (A) and the λ / 4 retardation film (B) are slow. Phase axes can be easily aligned.

  In the present invention, the λ / 4 retardation film (A) and λ / 4 obtained by obliquely stretching the original film from the original film in such a manner that one is on the upper side and the other is on the lower side as described above. It is preferable to use a roll set comprising the retardation film (B).

  Furthermore, it is a roll-shaped film set for a circularly polarizing plate protective film composed of a λ / 4 retardation film (A) and a λ / 4 retardation film (B), each λ / 4 retardation film being It is a stretched film containing a plasticizer, and the λ / 4 retardation film (A) and the λ / 4 retardation film (B) are respectively on the sides where the plasticizer content ratio is higher in the thickness direction. A roll-shaped film for a circularly polarizing plate protective film in which the slow axes of the λ / 4 retardation film (A) and the λ / 4 retardation film (B) are perpendicular to each other It is preferable to use a set.

  The original film to be used may be one type or two types, but it is possible to produce two types of λ / 4 retardation films from the same original film, symmetry of the plasticizer content ratio in the thickness direction, film thickness, etc. Is preferable because it can be more controlled.

  Moreover, the arrangement | positioning shown by (1-2) and (1-3) in FIG. 1 (1) becomes preferable because the plasticizer content ratio of the thickness direction of a circularly-polarizing plate becomes symmetrical. In particular, the arrangement shown in (1-2) is preferable because the outer surface (surface) is a surface having a high plasticizer content ratio, so that it becomes hydrophobic and curl fluctuation can be reduced against external humidity fluctuation.

  The plasticizer content ratio can be determined, for example, by measuring the concentration of the target substance in the film cross section using a time-of-flight secondary ion mass spectrometer (ToF-SIMS) (manufactured by Physical Electronics Co., Ltd.). In the thickness direction, the retardation film is divided into two, and the surface having a high plasticizer content ratio and the surface having a low plasticizer content can be determined from the average value of the concentration of the target substance in each region.

  In this invention, it is preferable to manufacture using a diagonal stretch apparatus. The oblique stretching apparatus is an apparatus for producing a retardation film whose slow axis is not parallel to the longitudinal direction of the long film by bending the film in an approximately 45 degree direction with respect to the initial transport direction of the film.

  In order to set the angle between the slow axis of the long film and the longitudinal direction of the long film to 45 ° and −45 °, it is necessary to change the bending angle. However, such a large change in bending angle is a major problem that causes an increase in apparatus cost and a decrease in yield when changing the bending angle.

  Using roll sets produced by arranging the plasticizer distribution in the thickness direction, and placing these films on the upper and lower sides when introducing these films into the oblique stretching device Thus, the production of a polarizing plate can improve the above-mentioned problems, and is a preferred embodiment.

  In addition, by setting the orientation angle to 45 °, it is easy and preferable to make the slow axis the same and the angle formed by the absorption axis of the polarizer to be 45 °.

<Method for producing long stretched film>
The λ / 4 retardation film according to the present invention is preferably a long stretched film manufactured by oblique stretching. An in-plane slow axis can be provided at an arbitrary angle with respect to the extending direction of the film by obliquely stretching the long original film.

  Here, the “long” means a film having a length of at least about 5 times the width of the film, preferably a length of 10 times or more, and specifically wound in a roll shape. It is possible to have a length (film roll) that can be stored or transported. In the manufacturing method of a long film, a film can be manufactured to desired arbitrary length by manufacturing a film continuously. In addition, the manufacturing method of a elongate stretched film may be made to supply to the diagonally stretching process after forming the elongate original film into a wound body once after forming the elongate original film, or after film formation The raw film may be continuously supplied from the film forming process to the oblique stretching process without winding up the original film. It is preferable to perform the film forming step and the oblique stretching step continuously, because the film forming conditions can be changed by feeding back the film thickness after stretching and the optical value result, and a desired long stretched film can be obtained.

  In the method for producing a long stretched film, a long stretched film having a slow axis at an angle of more than 0 ° and less than 90 ° with respect to the width direction of the film can be produced. Here, the angle with respect to the width direction of the film is an angle in the film plane. Since the slow axis is usually expressed in the stretching direction or a direction perpendicular to the stretching direction, by stretching at an angle of more than 0 ° and less than 90 ° with respect to the film extension direction, a long axis having such a slow axis is obtained. A stretched film can be produced.

  The angle formed by the extension direction of the long stretched film and the slow axis, that is, the orientation angle, can be arbitrarily set to a desired angle within a range of more than 0 ° and less than 90 °, more preferably 40 °. It can be set to 45 ° as a specific example.

<Manufacturing method of long original film>
The long original film used for producing the long stretched film can be obtained by a known method such as a solution cast molding method, an extrusion molding method, an inflation molding method and the like. Among these, the solution cast molding method is excellent in the flatness and transparency of the film, and the extrusion molding method makes it easy to reduce the retardation Rt in the thickness direction after oblique stretching, and the amount of residual volatile components is small and the film dimensions are small. It is preferable because it is excellent in stability. This long original film may be a single layer or a laminated film of two or more layers. The laminated film can be obtained by a known method such as a coextrusion molding method, a co-casting molding method, a film lamination method, or a coating method. Of these, the coextrusion molding method and the co-casting molding method are preferable.

  In the present invention, the thickness unevenness σm in the flow direction of the long original film supplied for stretching maintains the film take-up tension at the entrance of the oblique stretching tenter described later, and the optical characteristics such as the orientation angle and retardation. From the viewpoint of stabilization, it is necessary to be less than 0.30 μm, preferably less than 0.25 μm, more preferably less than 0.20 μm. When the thickness unevenness σm in the flow direction of the long original film is 0.30 μm or more, variations in optical properties such as retardation and orientation angle of the long stretched film are remarkably deteriorated.

  In order to keep the thickness unevenness σm in the flow direction of the long original film in the above range, in the case of the extrusion molding method, as described in JP-A-2004-233604, This can be achieved by a method of keeping the molten thermoplastic resin in a stable state. Specifically, 1) A method in which a sheet-like thermoplastic resin extruded from a die is brought into close contact with a cooling drum under a pressure of 50 kPa or less when a long original film is produced by a melt extrusion method; ) When manufacturing a long original film by the melt extrusion method, cover the area from the die opening to the first cooling drum that is in close contact with the enclosure member, and set the distance from the enclosure member to the die opening or the first cooling drum that is in close contact with it. 3) Heating the atmosphere within 10 mm from the sheet-like thermoplastic resin extruded from the die opening to a specific temperature when producing a long original film by the melt extrusion method. 4) A method in which a sheet-like thermoplastic resin extruded from a die so as to satisfy the relationship is brought into close contact with a cooling drum under a pressure of 50 kPa or less; 5) by a melt extrusion method A method of spraying a wind having a speed difference of 0.2 m / s or less from the cooling speed of the cooling drum that is first brought into contact with the sheet-like thermoplastic resin extruded from the die opening when producing the shakuhara film. ;

  Moreover, the film which has the thickness gradient of the width direction may be supplied as a elongate original film. The thickness gradient of the length of the original film, which can make the film thickness the most uniform at the position where stretching has been completed, can be experienced by stretching films with varying thickness gradients experimentally. Can be obtained. The gradient of the thickness of the long original film is adjusted so that, for example, the thickness of the end portion on the thick side is about 0.5 to 3% thicker than the end portion on the thin side. Can do.

  Although the width | variety of a elongate original film is not specifically limited, 500-4000 mm, Preferably it can be 1000-2000 mm. Further, the total film thickness of the long original film is not particularly limited, but is preferably in the range of 20 to 400 μm, preferably 20 to 200 μm.

  In addition, as a method for adjusting the width of the above-described long original film, a film obtained by a solution cast molding method or an extrusion molding method may be stretched in the transverse direction in the width direction or longitudinally stretched in the transport direction.

  The preferable elastic modulus at the stretching temperature during oblique stretching is expressed in terms of Young's modulus and is 0.01 MPa or more and 5000 MPa or less, more preferably 0.1 MPa or more and 500 MPa or less. If the elastic modulus is too low, the shrinkage rate during stretching and after stretching will be low, and wrinkles will be difficult to disappear.If it is too high, the tension applied during stretching will increase, and the strength of the part holding both side edges of the film will be increased. It is necessary to increase the load, and the load on the tenter in the subsequent process increases.

<Stretching with an oblique stretching tenter>
An obliquely stretched tenter is used in order to impart an oblique orientation to a long elongated raw film that is subjected to stretching in the production method according to the present embodiment. The obliquely stretched tenter used in this embodiment can freely set the orientation angle of the film by variously changing the rail pattern and the conveyance speed of the film gripper, and further, the orientation axis of the film across the film width direction. It is preferable that the film stretching apparatus be capable of evenly orienting with high precision on the left and right sides and controlling the film thickness and retardation with high precision.

  2 (a) and 2 (b) are schematic views of a tenter that can be stretched obliquely, which is used in the method for producing a long stretched film according to the present embodiment. However, this is an example, and the present invention is not limited to this.

  The long original film 4 whose direction is controlled by the guide roll 12-1 on the tenter entrance side has a gripping tool (clip holder) at the positions of the outer film holding start point 8-1 and the inner film holding start point 8-2. Part).

  The pair of left and right film grippers are transported and stretched at an equal speed with each other in the oblique direction indicated by the trajectory 7-1 of the outer film gripping means and the trajectory 7-2 of the inner film gripping means by the oblique stretching tenter 6. The gripping is released by the outer film gripping end point 9-1 and the inner film gripping end point 9-2, and the conveyance is controlled by the guide roll 12-2 on the tenter outlet side, whereby the obliquely stretched film 5 is formed. In the drawing, the long original film is obliquely stretched at an angle (feeding angle θi) in the film stretching direction 14-2 with respect to the film feeding direction 14-1.

  In FIGS. 2 (a) and 2 (b), the traveling speed of the gripping tool can be appropriately selected, but is usually 1 to 100 m / min.

  The pair of left and right film grippers having the same speed means that the travel speed of the pair of left and right grippers is substantially 1% or less of the travel speed.

  In general tenter devices, etc., there are speed irregularities that occur in the order of seconds or less depending on the period of the sprocket teeth that drive the chain, the frequency of the drive motor, etc. This does not correspond to the speed difference described in the embodiment of the invention.

  The manufacturing method of the elongate stretched film which concerns on embodiment of this invention is performed using the tenter which can be extended diagonally. This tenter is a device that widens a long original fabric film in an oblique direction with respect to its traveling direction (moving direction of the middle point in the film width direction) in an oven heating environment. The tenter includes an oven, a pair of rails on the left and right on which a gripping tool for transporting the film travels, and a number of gripping tools that travel on the rails. Both ends of the film fed out from the film roll and sequentially supplied to the entrance portion of the tenter are gripped by a gripping tool, the film is guided into the oven, and the film is released from the gripping tool at the exit portion of the tenter. The film released from the gripping tool is wound around the core. Each of the pair of rails has an endless continuous track, and the gripping tool which has released the grip of the film at the exit portion of the tenter travels outside and is sequentially returned to the entrance portion.

  2 (a) and 2 (b), the rail shape of the tenter is asymmetrical or bilaterally symmetric depending on the orientation angle θ, the draw ratio, etc. given to the long stretched film to be produced. It can be fine-tuned manually or automatically. In the present invention, a long thermoplastic resin film is stretched, and the orientation angle θ can be set to an arbitrary angle within a range of preferably 10 ° to 80 ° with respect to the winding direction after stretching. ing.

  Further, the traveling speed difference between the right and left gripping tools is appropriately selected depending on the tenter stretching method.

  In the obliquely stretched tenter used in the manufacturing method according to the embodiment of the present invention, it is preferable that the positions of the rail portions and the rail connecting portions can be set freely. Therefore, the oblique stretch tenter can be set to a draw ratio according to an arbitrary entrance width and exit width (the circled portion in FIG. 2 below is an example of a connecting portion).

  In the obliquely stretched tenter used in the manufacturing method according to the embodiment of the present invention, particularly in the tenter as shown in FIGS. 2 (a) and 2 (b), the rail for regulating the locus of the gripping tool often has a large bending rate. Desired. In order to avoid interference between gripping tools due to sudden bending or local stress concentration, it is desirable that the trajectory of the gripping tool draws an arc at the bent portion.

  In the obliquely stretched tenter shown in FIG. 2A, the traveling direction 14-1 at the tenter entrance of the long original film is different from the traveling direction at the tenter exit side of the stretched film. The feeding angle θi is an angle formed by the traveling direction 14-1 at the tenter inlet and the traveling direction 14-2 on the tenter exit side of the stretched film.

  In the obliquely stretched tenter shown in FIG. 2 (b), the traveling direction 14-1 at the tenter inlet of the long original film is different from the traveling direction at the tenter inlet at the feeding angle θi in the tenter. Converted and transported. Thereafter, the transport direction is further changed, and finally, a trajectory that matches the traveling direction on the tenter exit side of the stretched film is taken. In the present invention, in order to produce a film having an orientation angle θ of preferably 10 ° to 80 ° as described above, the feeding angle θi is 10 ° <θi <60 °, preferably 15 ° <θi <50 °. Set by. By setting the feeding angle θi in the above range, the variation in the optical characteristics in the width direction of the obtained film becomes good (smaller).

  In the embodiment of the present invention as shown in FIGS. 2 (a) and 2 (b), the left and right gripping tools of the tenter are configured to travel at a constant speed with a certain distance from the front and rear gripping tools.

  The film traveling in the oblique stretching tenter passes through an oven divided into a preheating zone, a lateral stretching zone, an oblique stretching zone, a holding zone, a cooling zone and the like in the tenter according to the rail pattern on which the film travels. However, it is not always necessary to transport the film in all the above zones in the above order. For example, as shown in the following combination example, only a part of the above zones is used, or any zone among the above zones is used several times. Or you may.

Preheating zone / oblique stretching zone / holding zone / cooling zone Preheating zone / lateral stretching zone / oblique stretching zone / holding zone / cooling zone Preheating zone / oblique stretching zone / lateral stretching zone / holding zone / cooling zone Preheating zone / lateral stretching zone 1 / oblique stretching zone / transverse stretching zone 2 / holding zone / cooling zone preheating zone / transverse stretching zone 1 / oblique stretching zone 1 / transverse stretching zone 2 / oblique stretching zone 2 / holding zone / cooling zone In the entrance, it refers to a section where the gripping tool that grips both ends of the film travels while maintaining a constant spacing.

  The transverse stretching zone refers to a section where the gap between the gripping tools gripping both ends of the film starts to reach a predetermined interval. At this time, the opening angle of the rail on which the gripping tools at both ends run may be opened at the same angle for both rails, or may be opened at different angles.

  The diagonally stretched zone means that the gripping tool that grips both ends of the film starts running on the bending rail while keeping the gripping tool spacing constant or spreads, and then both gripping tools run on the straight rail again. Refers to the interval until the beginning.

  The holding zone refers to a section in which the gripping tools at both ends travel while being parallel to each other in a period in which the interval between the gripping tools after the transverse stretching zone or the oblique stretching zone becomes constant again.

  The cooling zone refers to a section where the temperature in the zone is set to be equal to or lower than the glass transition temperature Tg ° C. of the thermoplastic resin constituting the film in the section after the holding zone.

  At this time, in consideration of shrinkage of the film due to cooling, a rail pattern that narrows the gap between the opposing gripping tools in advance may be used.

  The temperature of each zone is set to Tg to Tg + 30 ° C., the temperature of the stretching zone is set to Tg to Tg + 30 ° C., and the temperature of the cooling zone is set to Tg−30 to Tg ° C. with respect to the glass transition temperature Tg of the thermoplastic resin. It is preferable to do.

  In order to control the thickness unevenness in the width direction, a temperature difference may be given in the width direction in the stretching zone. In order to give a temperature difference in the width direction in the stretching zone, a method of adjusting the opening degree of the nozzle for sending warm air into the temperature-controlled room so as to make a difference in the width direction, and controlling heating by arranging heaters in the width direction are known. Can be used.

<Circularly polarizing plate>
In the circularly polarizing plate of the present invention, the angle formed by the slow axes of the λ / 4 retardation film (A) and the λ / 4 retardation film (B) is within 5 °. This angle means an angle difference between the two, and it is more preferable that the respective slow axes substantially coincide, that is, 0 to 2 °.

  Moreover, it is preferable to make it the elongate polarizing plate formed by laminating | stacking a long-form (lambda) / 4 phase difference film (stretched film) on both surfaces of a elongate polarizer.

  The polarizing plate of the present invention uses a stretched polyvinyl alcohol doped with iodine or a dichroic dye as a polarizer, and λ / 4 retardation film (A) / polarizer / λ / 4 retardation film ( It can be manufactured by bonding with the structure of B).

  The film thickness of the polarizer is 5 to 40 μm, preferably 5 to 30 μm, and particularly preferably 5 to 20 μm.

  The polarizing plate can be produced by a general method. The λ / 4 retardation film subjected to the alkali saponification treatment is preferably bonded to one surface of a polarizer prepared by immersing and stretching a polyvinyl alcohol film in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution.

  The polarizing plate can be constructed by further bonding a protective film on one surface of the polarizing plate and a separate film on the other surface. The protective film and the separate film are used for the purpose of protecting the polarizing plate at the time of shipping the polarizing plate and at the time of product inspection.

<Organic electroluminescence display device>
An example of the configuration of the organic EL image display device of the present invention is shown below, but is not limited thereto.

  A polarizer is placed on an organic EL device having a metal electrode, a TFT, a light emitting layer, a transparent electrode (ITO, etc.), an insulating layer, a sealing layer, and a transparent sheet (optional) on a substrate made of glass or polyimide. An organic EL image display device is configured by providing a circularly polarizing plate sandwiched between two types of λ / 4 retardation films. It is preferable that a protective film or a cured layer is laminated on the surface of the circularly polarizing plate. The cured layer not only prevents scratches on the surface of the organic EL image display device but also has an effect of preventing warpage due to the circularly polarizing plate. Further, an antireflection layer may be provided on the cured layer. The thickness of the organic EL element itself is about 1 μm.

  In general, in an organic EL image display device, a metal electrode, a light emitting layer, and a transparent electrode are sequentially laminated on a transparent substrate to form a light emitting element (organic EL element). Here, the light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer made of a triphenylamine derivative and the like and a light emitting layer made of a fluorescent organic solid such as anthracene, or Structures with various combinations, such as a laminate of such a light-emitting layer and an electron injection layer composed of a perylene derivative, and / or a laminate of these hole injection layer, light-emitting layer, and electron injection layer, are known. ing.

  In an organic EL image display device, holes and electrons are injected into the light emitting layer by applying a voltage to the transparent electrode and the metal electrode, and the energy generated by recombination of these holes and electrons excites the phosphor material. Then, light is emitted on the principle that the excited fluorescent material emits light when returning to the ground state. The mechanism of recombination in the middle is the same as that of a general diode, and as can be predicted from this, the current and the emission intensity show strong nonlinearity with rectification with respect to the applied voltage.

  In an organic EL image display device, in order to extract light emitted from the light emitting layer, at least one of the electrodes must be transparent, and a transparent electrode usually formed of a transparent conductor such as indium tin oxide (ITO) is used as an anode. It is used as On the other hand, in order to facilitate electron injection and increase luminous efficiency, it is important to use a substance having a small work function for the cathode, and usually metal electrodes such as Mg—Ag and Al—Li can be used.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "mass part" "mass%" is represented.

<Example 1>
<Production of λ / 4 retardation film>
Fabrication of raw film <Dope solution composition>
Methylene chloride 340 parts by mass Ethanol 64 parts by mass Cellulose ester (cellulose acetate propionate: acetyl group substitution degree 1.5, propionyl group 0.9, total substitution degree 2.4; weight average molecular weight 190,000) 100 parts by weight sugar ester Compound A 7.0 parts by mass Polyester B 2.5 parts by mass TINUVIN 928 (manufactured by BASF Japan Ltd.) 1.5 parts by mass Fine particle additive solution 1 3.5 parts by mass The cellulose ester described in the above composition has intrinsic birefringence. Is a positive resin.

The fine particle addition liquid 1 was prepared by the following method.
<Fine particle dispersion 1>
Fine particles (Aerosil R812 manufactured by Nippon Aerosil Co., Ltd.) 11 parts by weight Ethanol 89 parts by weight The above was stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin.

<Fine particle addition liquid 1>
The fine particle dispersion 1 was slowly added to the dissolution tank containing methylene chloride with sufficient stirring. Further, the particles were dispersed by an attritor so that the secondary particles had a predetermined particle size. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution 1.

Methylene chloride 50 parts by weight Fine particle dispersion 1 50 parts by weight Polyester compound B prepared by the following method was used.

(Preparation of polyester B)
In a nitrogen atmosphere, 4.85 g of dimethyl terephthalate, 4.4 g of 1,2-propylene glycol, 6.8 g of p-toluic acid, and 10 mg of tetraisopropyl titanate were mixed and stirred at 140 ° C. for 2 hours. Stirring was carried out at ° C for 16 hours. Next, the temperature was lowered to 170 ° C., and unreacted 1,2-propylene glycol was distilled off under reduced pressure to obtain polyester B.

Acid value: 0.1 mg KOH / g
Number average molecular weight: 490
Dispersity: 1.4
Component content of molecular weight 300-1800: 90%
Hydroxy (hydroxyl group) value: 0.1 mgKOH / g
Hydroxy group content: 0.04%
Polyester B has a toluic acid ester at the end because monocarboxylic acid is used in an amount twice as much as that of dicarboxylic acid.

(Preparation of sugar ester compound A)
A four-headed Kolben equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet tube was charged with 34.2 g (0.1 mol) of sucrose, 240 g (0.8 mol) of benzoic anhydride, and 379.7 g of pyridine ( 4.8 mol) was added, the temperature was raised while bubbling nitrogen gas from a nitrogen gas inlet tube with stirring, and an esterification reaction was carried out at 70 ° C. for 5 hours. Next, the inside of the Kolben was depressurized to 4 × 10 ² Pa or less, and after excess pyridine was distilled off at 60 ° C., the inside of the Kolben was depressurized to 1.3 × 10 Pa or less and the temperature was raised to 120 ° C. Most of the acid and benzoic acid formed were distilled off. Finally, 100 g of water is added to the collected toluene layer, and after washing with water at room temperature for 30 minutes, the toluene layer is separated, and toluene is distilled off at 60 ° C. under reduced pressure (4 × 10 ² Pa or less). An ester compound A was obtained. The average degree of substitution was 7.3, and the octanol / water partition coefficient (log P value) was 12.43.

  The above was put into a sealed container and dissolved with stirring to prepare a dope solution. Next, an endless belt casting apparatus was used to uniformly cast the dope solution on a stainless steel belt support at a temperature of 33 ° C. and a width of 2000 mm. The temperature of the stainless steel belt was controlled at 30 ° C.

  On the stainless steel belt support, the solvent was evaporated until the residual solvent amount in the cast (cast) film became 75%, and then peeled off from the stainless steel belt support with a peeling tension of 110 N / m.

  The peeled cellulose ester film was stretched 1% in the width direction using a tenter while applying heat at 160 ° C. The residual solvent at the start of stretching was 15%.

  Next, drying was terminated while the drying zone was conveyed by a number of rolls. The drying temperature was 130 ° C. and the transport tension was 100 N / m.

  As described above, a long roll-shaped raw fabric film A having a dry film thickness of 110 μm was obtained.

<Slant stretching>
The roll-shaped long original film A was set in a slidable feeding device of the apparatus shown in FIG. 2A and supplied to an oblique stretching machine. At that time, the distance between the main axis of the guide roll 12-1 closest to the inlet portion of the oblique stretching apparatus and the grip start points (clip gripping portions) 8-1 and 8-2 of the oblique stretching apparatus was set to 80 cm. A clip with a length of 2 inches in the conveying direction was used, and a guide roll with a diameter of 10 cm was used. The tenter was stretched in the transverse direction at a stretching temperature of 200 ° C. and a stretching ratio of 1.8 times, and then contracted 0.71 times in the direction perpendicular to the stretching when the rail was bent 45 °. The stretched film was controlled such that the fluctuation in the take-up tension was less than 3% by performing feedback control in which the change in the tension measured with the roll 12-2 on the obliquely stretched tenter outlet side was reflected in the take-up motor rotation speed. Then, both ends of the film are trimmed, the conveyance direction is changed by a conveyance direction changing device composed of an airflow roll, and the film is wound by a slidable winding device to obtain a roll-like long stretched retardation film having a width of 2000 mm. It was.

  Moreover, it extended | stretched using the heating apparatus for temperature control over the width direction of a film. The heating device controlled the temperature so that the thickness of the film in the film width direction after stretching was approximately the same as the thickness direction film thickness distribution before stretching.

  The obtained λ / 4 retardation film (A), which is a long stretched film having an orientation angle of 45 °, was uniform in the longitudinal direction of the film.

  In the same manner as described above, a long λ / 4 retardation film (A) was obtained in which the bending angle of the rail was changed and the orientation angle was changed to 47 ° and 48 °. Similarly, a long λ / 4 retardation film (B) having an orientation angle changed to 45 ° 44 ° and 43 ° 35 ° was obtained.

<Production of circularly polarizing plates 1 to 5>
A 120 μm thick polyvinyl alcohol film was immersed in 100 kg of an aqueous solution containing 1 kg of iodine and 4 kg of boric acid and stretched 6 times at 50 ° C. to form a long polarizing film.

  Using this polarizing film as a polarizer, using a 5% aqueous solution of fully saponified polyvinyl alcohol as an adhesive, the following retardation films with different orientation angles were bonded to the polarizer. , Λ / 4 retardation film (A), polarizer, and λ / 4 retardation film (B) were prepared in the combinations shown in Table 1.

<Alkali saponification treatment>
Saponification step 2N-NaOH 50 ° C. 90 seconds water washing step Water 30 ° C. 45 seconds neutralization step 10 mass% HCl 30 ° C. 45 seconds water washing step Water 30 ° C. 45 seconds Saponification, water washing, neutralization, water washing under the above conditions And then dried at 80 ° C.

  The circularly polarizing plate 5 uses a cellulose ester film prepared by the above method as the λ / 4 retardation film (A), and a commercially available polycarbonate λ / with positive intrinsic birefringence as the λ / 4 retardation film (B). A four-phase difference film (Pure Ace WRS (manufactured by Teijin Limited)) is used as a raw material, and a long λ / 4 phase difference film is prepared using an oblique stretching device, and then bonded using an ultraviolet curable resin to form a circularly polarizing plate. Produced.

<Evaluation>
(1) Orientation angle θ, in-plane retardation Ro
Using a phase difference measuring device (manufactured by Oji Scientific Instruments, KOBRA-WPR), the orientation angle θ of the slow axis and Ro at 550 nm were determined. In addition, chromatic dispersion in the visible range was measured. The angle of the slow axis was described with the longitudinal direction of the long film as the 0 ° reference, the clockwise direction being +, and the counterclockwise direction being-. The absorption axis in the longitudinal direction of the polarizer was 0 °.

(2) Polarizing plate curl A sample having a diameter of 5 cm was cut out from the polarizing plate sample, left in a constant temperature and humidity chamber at a temperature of 23 ° C. and 55% RH for 24 hours, and then placed on a flat plate, using a curvature scale, 1 / r was obtained from the curvature radius r (m) having a matching curve, and this was used as a measure of the curl size. The curl size and ease of handling were ranked as follows.

：: Less than 0-5 ◯: Less than 5-10 ×: 10 or more Here, ◎ and ○ are practically easy to handle, but × is extremely difficult to handle.

  Table 1 shows the retardation values (Ro (550 nm)) of the circularly polarizing plates 1 to 5, the slow axis of the λ / 4 retardation film (A) and the λ / 4 retardation film (B) and the polarizer. The angle, the angle formed by the slow axis of the λ / 4 retardation film (A) and the λ / 4 retardation film (B), and the evaluation result of the polarizing plate curl are described.

  In the table, WRS represents Pure Ace WRS (manufactured by Teijin Limited). Moreover, the following abbreviations were used in the following tables.

表１から明らかなように、本発明の試料１〜３及び試料５は偏光板カール特性に優れた円偏光板であった。λ／４フィルム（Ａ）及びλ／４フィルム（Ｂ）の遅相軸のなす角を５°以下とすることにより、円偏光板作製時に掛る弾性のび状態から復元による歪みのバランスが改善され偏光板カールの良好な結果が得られた。 (A) Angle formed by slow axis of (B): Angle formed by slow axis of λ / 4 retardation film (A) and λ / 4 retardation film (B) Angle formed by slow axis and absorption axis: The angle between the slow axis of the λ / 4 retardation film and the absorption axis of the polarizer

As apparent from Table 1, Samples 1 to 3 and Sample 5 of the present invention were circularly polarizing plates excellent in polarizing plate curl characteristics. By setting the angle formed by the slow axes of the λ / 4 film (A) and the λ / 4 film (B) to 5 ° or less, the balance of strain due to restoration from the elastic stretch state during the production of the circularly polarizing plate is improved, and polarized light Good results of plate curl were obtained.

<Example 2>
<Production of raw film>
A long original fabric film (B) made of cellulose ester was obtained by casting film formation in the same manner as in Example 1. In the production of the roll-shaped long original film B, cellulose ester (cellulose acetate propionate: acetyl group substitution degree 1.5, propionyl group 0.9, total substitution degree) in <dope solution composition>2.4; weight average molecular weight 190,000), cellulose ester (cellulose acetate propionate: acetyl group substitution degree 1.9, propionyl group 0.7, total substitution degree 2.6; weight average molecular weight 160,000) It was used.

<Production of λ / 4 Film (A) and λ / 4 Film (B)>
Long film roll (B) Implemented with the A side up (the side with the higher plasticizer content ratio is the lower surface) and the B side up (the side with the higher plasticizer content ratio is the upper surface) when unrolling from the roll A roll set of λ / 4 retardation film was produced using the same oblique stretching machine as in Example 1.

<Production of circularly polarizing plate>
Using a roll set in which the relationship between the surface with a high plasticizer content and the slow axis was variously changed in the same manner as described above, the same method as in the production of the circularly polarizing plate described in Example 1, and the λ / 4 position The combination of the planes having different plasticizer content ratios of the retardation film (A) and the λ / 4 retardation film (B) is changed as described in the column of λ / 4 retardation film in Table 2 to obtain λ / 4 ( A), a polarizer, and a circularly polarizing plate (samples 11 to 26) having a configuration of λ / 4 (B) were produced. The arrangement number of the λ / 4 retardation film corresponds to the arrangement of FIG.

<Production of organic electroluminescence display device>
As shown in FIG. 3, a reflective electrode 2b made of chromium having a thickness of 80 nm is formed on a glass substrate 1b by sputtering, and ITO is formed on the reflective electrode as an anode by sputtering to a thickness of 40 nm. Poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT: PSS) as the hole transport layer is 80 nm thick by sputtering, and a shadow mask is used on the hole transport layer, as shown in FIG. Each light emitting layer 3bR, 3bG, 3bB was formed with a film thickness of 100 nm. As the red light emitting layer 3bR, tris (8-hydroxyquinolinate) aluminum (Alq ₃ ) and a luminescent compound [4- (dicyanomethylene) -2-methyl-6 (p-dimethylaminostyryl) -4H-pyran] ( DCM) were co-evaporated (mass ratio 99: 1) to form a thickness of 100 nm. The green light emitting layer 3bG was formed by co-evaporating Alq ₃ as a host and the light emitting compound coumarin 6 (mass ratio 99: 1) to a thickness of 100 nm. The blue light emitting layer 3bB was formed with a thickness of 100 nm by co-evaporating BAlq and a light emitting compound Perylene as a host (mass ratio 90:10).

さらに、発光層上に電子が効率的に注入できるような仕事関数の低い第１の陰極としてカルシウムを真空蒸着法により４ｎｍの厚さで成膜し、第１の陰極上に第２の陰極としてアルミニウムを２ｎｍの厚さで成膜した。ここで、第２の陰極として用いたアルミニウムはその上に形成される透明電極４ｂをスパッタリング法により成膜する際に、第１の陰極であるカルシウムが化学的変質をすることを防ぐ役割がある。以上のようにして、有機発光層を得た。次に、陰極上にスパッタリング法によって透明導電膜を８０ｎｍの厚さで成膜した。ここで透明導電膜としてはＩＴＯを用いた。さらに、透明導電膜上にＣＶＤ法によって窒化珪素を２００ｎｍ成膜することで、絶縁膜５ｂとした。

Further, calcium is deposited to a thickness of 4 nm by vacuum deposition as a first cathode having a low work function so that electrons can be efficiently injected onto the light emitting layer, and a second cathode is formed on the first cathode. Aluminum was deposited to a thickness of 2 nm. Here, the aluminum used as the second cathode has a role to prevent calcium as the first cathode from being chemically altered when the transparent electrode 4b formed thereon is formed by sputtering. . As described above, an organic light emitting layer was obtained. Next, a transparent conductive film was formed to a thickness of 80 nm on the cathode by sputtering. Here, ITO was used as the transparent conductive film. Furthermore, a silicon nitride film having a thickness of 200 nm was formed on the transparent conductive film by a CVD method to form the insulating film 5b.

  The insulating layer of the organic electroluminescence element 11b obtained above and the circularly polarizing plate 10b composed of the λ / 4 retardation film (B) 7b, the polarizer 8b, and the λ / 4 retardation film (A) 9b are bonded to the adhesive layer 6b. And an organic electroluminescence display device was manufactured.

  The following evaluation was performed on the circularly polarizing plates 11 to 26 and the corresponding organic electroluminescence display devices 11 to 26 using these.

<Evaluation>
(3) Curling fluctuation due to humidity fluctuation After measuring the value of the polarizing plate curl described in Example 1 above, the sample was placed in a constant temperature and humidity chamber at 23 ° C. and 80% RH, and again after 2 hours. The value of polarizing plate curl was measured by the method described in Example 1, and the difference was evaluated.
A: Change in polarizing plate curl (1 / r) is less than 2 due to humidity fluctuation.
○: The change of the polarizing plate curl (1 / r) is 2 or more and less than 5 due to humidity fluctuation.
(Triangle | delta): The change of polarizing plate curl (1 / r) is 5 or more and less than 10 by humidity fluctuation.
X: Change in polarizing plate curl (1 / r) is 10 or more due to humidity fluctuation. (4) (Light leakage of organic EL element)
The organic electroluminescence device was turned on for 2 hours in a constant temperature and humidity chamber at 23 ° C. and 55% RH, and then turned off, and the reflectance of the surface was measured. Next, the conditions were changed to 23 ° C. and 80% RH, and the organic electroluminescence element was turned on for 2 hours, then turned off, and the reflectance of the surface was measured. Evaluation was performed according to the following criteria from the change in reflectance before and after.
A: Change in reflectance is less than 50% based on the first measured value.
A: The change in reflectance is 50% or more and less than 100% based on the first measured value.
(Triangle | delta): The change of a reflectance is 100% or more and less than 150% on the basis of the first measured value.
X: The change in reflectance is 150% or more based on the first measured value.

  In Table 2, light leakage of the organic electroluminescence display device was described as light leakage. The arrangement of (A) and (B) represents a combination of arrangements of plasticizer content ratios in the thickness direction of the λ / 4 retardation film (A) and the λ / 4 retardation film (B), and the numbers are shown in FIG. This corresponds to the arrangement (1).

本発明試料はカール耐性に優れていることがわかる。更にλ／４位相差フィルムの配置が（１−２）、（１−３）のように、λ／４位相差フィルム（Ａ）とλ／４位相差フィルム（Ｂ）との厚さ方向における可塑剤含有比率を円偏光板の厚さ方向において対称的に配置されたロールセットから作製された有機エレクトロルミネッセンス表示装置１２、１４、２４、２６が光漏れが少なく好ましい。またこれら４種の有機エレクトロルミネッセンス表示装置は、簡易に生産出来る観点からも好ましい。さらに可塑剤含有比率高い側の面が、共に偏光子から遠い側に配置される（１−２）の配置のロールセットから作製された有機エレクトロルミネッセンス表示装置１４、２６が吸脱湿に伴う寸法変化の速度を低下させるためより好ましいことがわかる。

It turns out that the sample of the present invention is excellent in curling resistance. Further, the arrangement of the λ / 4 retardation film in the thickness direction of the λ / 4 retardation film (A) and the λ / 4 retardation film (B) as in (1-2) and (1-3) Organic electroluminescence display devices 12, 14, 24, and 26 produced from a roll set in which the plasticizer content is symmetrically arranged in the thickness direction of the circularly polarizing plate are preferable because of less light leakage. These four types of organic electroluminescence display devices are also preferable from the viewpoint of easy production. Further, the dimensions associated with the moisture absorption and desorption of the organic electroluminescence display devices 14 and 26 made from the roll set having the arrangement (1-2) in which the plasticizer content ratio side is located on the side far from the polarizer. It can be seen that it is preferable to reduce the speed of change.

1a λ / 4 retardation film (A)
2a λ / 4 retardation film (B)
3a Slow axis of λ / 4 retardation film (45 °)
4a Slow axis of λ / 4 retardation film (−45 °)
A1, B1, C1, D1 Film roll 1b Glass substrate 2b Reflective electrode 3b Light emitting layer 4b Transparent electrode 5b Insulating layer 6b Adhesive layer 7b λ / 4 retardation film (B)
8b Polarizer 9b λ / 4 retardation film (A)
10b Circularly polarizing plate 11b Organic electroluminescence element 4 Long original film 5 Long stretched film 6 Diagonal stretch tenter 7-1 Trajectory of outer film gripping means 7-2 Trajectory of inner film gripping means 8-1 Outer film Grip start point 8-2 Inner film grip start point 9-1 Outer film grip end point 9-2 Inner film grip end point 10-1 Outer oblique stretching start point 10-2 Inner oblique stretching start point 11-1 Outside Diagonal Stretching End Point 11-2 Inner Diagonal Stretching End Point 12-1 Tenter Inlet Side Guide Roll 12-2 Tenter Outlet Side Guide Roll 13 Film Stretching Direction 14-1 Film Transport Direction Before Diagonal Stretching 14-2 Diagonal Stretching direction 15 Portion where the conveyance speeds of the right and left gripping tools differ from each other W0 Film width length before oblique stretching W Film width length after oblique stretching

Claims (6)

  A λ / 4 retardation film (A), a polarizer, and a λ / 4 retardation film (B) are laminated in this order. The slow axis of each λ / 4 retardation film and the absorption axis of the polarizer And each λ / 4 retardation film is a polymer stretched retardation film exhibiting positive intrinsic birefringence, and the λ / 4 retardation film ( A circularly polarizing plate, wherein the angle formed by the slow axis between A) and the λ / 4 retardation film (B) is 5 ° or less.   Both the λ / 4 retardation film (A) and the λ / 4 retardation film (B) are cellulose ester resin films containing a plasticizer, and both in the thickness direction of the λ / 4 retardation film. 2. The circularly polarizing plate according to claim 1, wherein both surfaces having a high plasticizer content ratio are disposed on the polarizer side or on the side far from the polarizer.   3. The circularly polarizing plate according to claim 2, wherein both surfaces of the retardation films having a high plasticizer content ratio in the thickness direction are disposed on the side far from the polarizer.   It is a manufacturing method of the circularly-polarizing plate of Claim 2 or 3, Comprising: After producing an original fabric film, the surface of the side with the high plasticizer content ratio in the thickness direction of each original fabric film, one is an upper side In addition, a circularly polarizing plate is produced by producing a λ / 4 retardation film (A) and a λ / 4 retardation film (B) by obliquely stretching the original film with the other side down. Method.   After producing the original film, each original film is stretched obliquely with the surface having the higher plasticizer content ratio in the thickness direction, one on the upper side and the other on the lower side. 5. The circularly polarizing plate according to claim 4, wherein the orientation angles when the λ / 4 retardation film (A) and the λ / 4 retardation film (B) are both 45 °. Method.   An organic electroluminescence display device using the circularly polarizing plate according to any one of claims 1 to 3.

Images