JP6536046B2 - Film and polarizing plate - Google Patents

Description

  The present invention relates to a film, and more particularly to a film that can be suitably used as a retardation film to be bonded to a polarizing plate used in a liquid crystal display, and a method for producing the same. The present invention also relates to a retardation film made of this film, a polarizing plate using this film, and a liquid crystal display device having this polarizing plate.

  In recent years, liquid crystal displays have been widely used as display devices for televisions, personal computers, digital cameras, mobile phones and the like. The liquid crystal display has a configuration of front side polarizing plate / liquid crystal / rear side polarizing plate, when the display side is the front side and the opposite side (backlight side) is the rear side. Further, depending on the liquid crystal system, the retardation film is sandwiched to prevent light leakage of the liquid crystal device. For example, in the VA (vertical alignment) liquid crystal system, front side polarizing plate / retardation film / liquid crystal / retardation film / It is considered as the composition of a back side polarizing plate.

  Heretofore, as a retardation film for light leakage prevention of liquid crystal, it has been proposed to use a triacetylcellulose film (hereinafter sometimes abbreviated as a TAC film) because it has high transparency and optical isotropy. (For example, Non-Patent Document 1).

  However, as the size and quality of liquid crystal displays have increased in recent years, improvements in mechanical strength and stability under high-temperature and high-humidity environments are being sought for members for liquid-crystal panels. On the other hand, since the TAC film is inferior in dimensional stability and heat and humidity resistance, the polarizing plate adopting the TAC film for the retardation film has problems of generation of stress accompanying shrinkage and functional deterioration of the polarizer, and such polarization It has been a problem to affect the image quality of a liquid crystal display device using a plate.

KONICA MINOLTA TECHNOLOGY REPORT VOL. 3 (2006) pp. 133 to 136 "Development of viewing angle widening film VA-TAC for VA type liquid crystal TV"

  The present invention has been made in view of the above situation, and the problem to be solved is that it is excellent in heat and humidity resistance and dimensional stability, and also excellent in mechanical strength, and is bonded to a polarizing plate used in a liquid crystal display. A film suitable as a retardation film, a method for producing the same, a retardation film comprising the film, a polarizing plate using the film, and a liquid crystal display device.

  MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in view of the said situation, the present inventors discovered that the above-mentioned subject could be easily solved if the film which consists of a specific structure was used, and came to complete this invention.

That is, according to the first aspect of the present invention, there is provided a film comprising a polycarbonate resin as a main component and having the following characteristics (1) to (3).
(1) Three-dimensional birefringence (Nx, Ny, Nz) is Nx>Ny> Nz.
(2) In-plane retardation (Re) is 30 nm ≦ Re ≦ 100 nm.
(3) Thickness retardation (Rth) is 100 nm ≦ Rth ≦ 180 nm.

Further, according to the second invention of the present invention, in the first invention, the biaxially stretched film is a uniaxially stretched film at a stretching temperature (T1), a stretching ratio (V1), and a biaxial stretching. There is provided a film characterized in that the eye drawing temperature (T2) and the draw ratio (V2) satisfy the following conditions (4) and (5).
(4) 10 ° C <T2-T1 <20 ° C
(5) 0.2 times <V2-V1 <1.0 times

  Furthermore, according to the third invention of the present invention, in the first or second invention, the polycarbonate resin is characterized by containing a structural unit derived from a dihydroxy compound represented by the following formula (I) A film is provided.

  Further, according to the fourth invention of the present invention, in the third invention, the polycarbonate resin further contains a structural unit derived from tricyclodecanedimethanol represented by the following formula (II) A film is provided.

Further, according to the fifth aspect of the present invention, a film obtained by film-forming a raw material to be a polycarbonate resin is biaxially stretched to obtain a film having the following characteristics (1) to (3). It is a method of manufacturing, and the stretching temperature (T1), the stretching ratio (V1), and the stretching temperature (T2) and the stretching ratio (V2) of biaxial stretching in the biaxial stretching are as follows. There is provided a method of producing a film characterized by satisfying the conditions (4) and (5).
(1) Three-dimensional birefringence (Nx, Ny, Nz) is Nx>Ny> Nz.
(2) In-plane retardation (Re) is 30 nm ≦ Re ≦ 100 nm.
(3) Thickness retardation (Rth) is 100 nm ≦ Rth ≦ 180 nm.
(4) 10 ° C <T2-T1 <20 ° C
(5) 0.2 times <V2-V1 <1.0 times

  Further, according to the sixth aspect of the present invention, there is provided a film produced by the method of producing a film according to the fifth aspect.

  Further, according to the seventh invention of the present invention, there is provided a retardation film comprising the film of any one of the first to fourth inventions or the sixth invention.

  Moreover, according to the 8th invention of this invention, the polarizing plate produced using the film which concerns on any one of the 1st-4th or 6th invention is provided.

  Further, according to a ninth aspect of the present invention, there is provided a liquid crystal display device provided with the polarizing plate according to the eighth aspect.

  According to the present invention, it is possible to provide a film suitable as a retardation film which is excellent in heat and humidity resistance and dimensional stability, is also excellent in mechanical strength, and is bonded to a polarizing plate used in a liquid crystal display. Its industrial value is high.

[the film]
The film of the present invention contains a polycarbonate resin as a main component, and has three-dimensional birefringence (Nx, Ny, Nz), in-plane retardation (Re), and thickness retardation (Rth) as shown in (1) to (3) below. Meet the requirements of
(1) Three-dimensional birefringence (Nx, Ny, Nz) is Nx>Ny> Nz.
(2) In-plane retardation (Re) is 30 nm ≦ Re ≦ 100 nm.
(3) Thickness retardation (Rth) is 100 nm ≦ Rth ≦ 180 nm.

Here, the in-plane retardation (Re) and the thickness retardation (Rth) are calculated by the following equation, where Nx is a slow axis.
Re = (Nx-Ny ) x film thickness Rth = ((Nx + Ny) / 2-Nz) x film thickness

  The term "main component" as used herein means that the content of the component in the film is preferably 50% by weight or more, more preferably 80% by weight or more, and still more preferably 90% by weight or more.

  The film of the present invention may have a single-layer structure or a multi-layer structure, and in the case of a multi-layer structure, four or more layers other than two- and three-layer structures as long as the gist of the present invention is not exceeded. It may be a multilayer, and is not particularly limited.

1. Physical Properties and the Like of Film Hereinafter, physical properties and the like of the film of the present invention will be specifically described.

(1) Three-Dimensional Birefringence Three-dimensional birefringence (Nx, Ny, Nz) of the film of the present invention is Nx>Ny> Nz.
That is, when the film of the present invention is used as a retardation film of a liquid crystal, particularly a liquid crystal device of a VA system, Nx is required to obtain a viewing angle widening effect without the need for sequentially laminating a plurality of retardation films. It is necessary that>Ny> Nz.

(2) In-plane retardation (Re)
The in-plane retardation (Re) of the film of the present invention is 30 nm or more and 100 nm or less, and particularly preferably 35 nm or more and 50 nm or less. That is, when the film of the present invention is used as a retardation film of a liquid crystal, particularly a liquid crystal device of a VA system, in order to effectively prevent light leakage, it is necessary to have an in-plane retardation (Re) within the above range is there. When the in-plane retardation (Re) of the film is out of the above range, light leakage from the liquid crystal from an oblique direction can not be prevented.

(3) Thickness retardation (Rth)
The thickness retardation (Rth) of the film of the present invention is 100 nm or more and 180 nm or less, and particularly preferably 120 nm or more and 160 nm or less. That is, when the film of the present invention is used as a retardation film of a liquid crystal, particularly a liquid crystal device of VA system, in order to effectively prevent light leakage, it is necessary to have a thickness retardation (Rth) within the above range is there. If the thickness retardation (Rth) of the film is out of the above range, it is impossible to offset the influence of light entering the liquid crystal from an oblique direction and the liquid crystal possessing the three-dimensional birefringence distribution of Positive-C.

  A film in which the three-dimensional birefringence (Nx, Ny, Nz), in-plane retardation (Re), and thickness retardation (Rth) satisfy the above conditions (1) to (3) is, for example, polycarbonate resin as a main component Preferably, the film can be produced by the method for producing a film of the present invention through a specific sequential biaxial stretching step described later, using a polycarbonate resin described later preferably.

  The specific methods of measuring the three-dimensional birefringence (Nx, Ny, Nz), the in-plane retardation (Ro) and the thickness retardation (Rth) of the film are as described in the section of Examples described later. is there.

The film thickness of the film of the present invention is not particularly limited, but the upper limit thereof is preferably 80 μm or less, more preferably 70 μm or less, and particularly preferably 60 μm or less. When the film thickness of the film exceeds 80 μm, the total film thickness of the polarizing plate using it becomes thick, and it becomes difficult to thin the liquid crystal panel. The film thickness of the film can be adjusted by the film forming conditions and the like. For example, in the case of producing a film by melt extrusion, the film thickness can be adjusted by the amount of extrusion and the take-up speed. When a film is produced by a solution flow method, the film thickness can be adjusted by the concentration of the solution and the like.
The lower limit of the film thickness of the film of the present invention is not particularly limited, but is usually 3 μm or more, preferably 5 μm or more, and more preferably 10 μm or more from the viewpoint of mechanical strength.

2. Polycarbonate Resin The film of the present invention contains, as a main component, a polycarbonate resin (hereinafter sometimes referred to as "the polycarbonate resin of the present invention").
Polycarbonate resin is excellent in dimensional stability and heat and humidity resistance, and mechanical strength and optical properties can be enhanced by material design. By using polycarbonate resin as a main component, polarized light used for liquid crystal display It is possible to obtain a high-performance film suitable as a retardation film to be bonded to a plate.

  Typical polycarbonate resins of the present invention include aromatic polycarbonates having a structural unit of 2,2′-bis (4-hydroxyphenyl) -propane (generally called bisphenol-A). The polycarbonate resin used is not limited to this, and, for example, 1,1-bis (4-hydroxyphenyl) -alkylcycloalkane, 1,1-bis (3-substituted-4-hydroxyphenyl) -alkylcycloalkane At least one dihydric phenol selected from the group consisting of 1,1-bis (3,5-substituted-4-hydroxyphenyl) -alkyl cycloalkanes and 9,9-bis (4-hydroxyphenyl) fluorenes Homo- or co-polycarbonates comprising the above monomers as monomer components; Mixtures of Le A and polycarbonate as a monomer component, such as a copolycarbonate of the above dihydric phenol and the bisphenol A monomers components.

  The polycarbonate resin of the present invention is a structure derived from a dihydroxy compound having a portion represented by the following formula (I) in part of the structure from the viewpoint of high transparency, high strength, high heat resistance, high weather resistance, etc. Polycarbonate resins containing units are preferred.

  More specifically, examples of the dihydroxy compound represented by the above-mentioned formula (I) include isosorbide, isomannide and isoidet which are in a stereoisomer relationship.

  The dihydroxy compound represented by the said Formula (I) is an ether diol which can be manufactured from saccharides using a biogenic substance as a raw material. In particular, isosorbide can be inexpensively produced by hydrogenating D-glucose obtained from starch and then dehydrating it, and can be obtained abundantly as a resource. Under these circumstances, isosorbide is most preferable as the dihydroxy compound represented by the above formula (I).

  The polycarbonate resin of the present invention may further contain a structural unit other than the structural unit derived from the dihydroxy compound having a portion represented by the above-mentioned formula (I). By further including a structural unit other than the structural unit derived from the dihydroxy compound having a portion represented by the formula (I), it becomes possible to improve processability and impact resistance.

  Among structural units other than the structural unit derived from the dihydroxy compound having a moiety represented by the formula (I), structural units derived from a dihydroxy compound having no aromatic ring are preferably used.

  More specifically, for example, mention may be made of structural units derived from aliphatic dihydroxy compounds described in WO 2004/111106 and structural units derived from alicyclic dihydroxy compounds described in WO 2007/148604. it can.

  Among structural units derived from the aliphatic dihydroxy compound, at least one selected from ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol and 1,6-hexanediol It is preferable to include a structural unit derived from a dihydroxy compound.

  Among the structural units derived from the alicyclic dihydroxy compound, those having a 5- or 6-membered ring structure are preferable. The six-membered ring structure may be fixed in a chair or cage shape by a covalent bond.

  By including a structural unit derived from an alicyclic dihydroxy compound having a five-membered ring structure or a six-membered ring structure, the heat resistance of the obtained polycarbonate resin can be increased.

  The number of carbon atoms contained in the alicyclic dihydroxy compound is usually preferably 70 or less, more preferably 50 or less, and still more preferably 30 or less.

As an alicyclic dihydroxy compound containing the said 5-membered ring structure or 6-membered ring structure, the thing as described in the above-mentioned WO2007 / 148604 can be mentioned.
Among them, cyclohexanedimethanol, tricyclodecanedimethanol, adamantanediol and pentacyclopentadecanedimethanol can be suitably exemplified. Among these, cyclohexane dimethanol or tricyclodecane dimethanol is more preferable from the viewpoint of economy and heat resistance. In particular, containing a structural unit derived from tricyclodecanedimethanol represented by the following formula (II) is most preferable in terms of economy, heat resistance, and balance with optical characteristics.
In addition, 1 type of these other structural units may be contained in polycarbonate resin, and 2 or more types may be contained.

The content ratio of the structural unit derived from the dihydroxy compound having a portion represented by the formula (I) in part of the structure of the polycarbonate resin is the content ratio of the structural unit derived from all the dihydroxy compounds in the polycarbonate resin, The amount is preferably 30 mol% or more, more preferably 40 mol% or more, particularly preferably 50 mol% or more, and preferably 90 mol% or less, more preferably 80 mol% or less.
If the content ratio of the structural unit derived from the dihydroxy compound having a portion represented by the formula (I) in a part of the structure of the polycarbonate resin is the above lower limit or more, the heat resistance is improved by maintaining the glass transition temperature And a film satisfying the high tear strength described later can be obtained. On the other hand, by being below the above upper limit, the coloring derived from the carbonate structure, the coloring derived from the impurities contained in a small amount since the biogenic substance is used as the raw material, etc. can be suppressed, There is a possibility not to lose the sex. In addition, suitable molding processability, mechanical strength, and the like, which are difficult to achieve with a polycarbonate resin or the like consisting of only a structural unit derived from a dihydroxy compound having a portion represented by the formula (I) in part of the structure. Balance of heat resistance etc. can be taken.

  The polycarbonate resin comprises a structural unit derived from a dihydroxy compound having a portion represented by the formula (I) in part of its structure, and a structural unit derived from an aliphatic dihydroxy compound and / or an alicyclic dihydroxy compound It is preferable to be composed of a structural unit derived from the structural unit, but structural units derived from other dihydroxy compounds may be included as long as the object of the present invention is not impaired.

  The polycarbonate resin can be produced by a commonly used polymerization method. The polycarbonate resin may be produced by either the phosgene method or a transesterification method in which a carbonic acid diester is reacted. Among them, in the presence of a polymerization catalyst, a dihydroxy compound having a portion represented by the formula (I) in a part of the structure, an aliphatic and / or an alicyclic dihydroxy compound, and others optionally used The transesterification method which makes the dihydroxy compound of this and carbonic diester react is preferable.

  In the transesterification method, one or two or more of dihydroxy compounds having a portion represented by the above-mentioned formula (I) in a part of the structure, and one or two or more of aliphatic and / or alicyclic dihydroxy compounds A basic catalyst and further an acidic substance that neutralizes the basic catalyst are added to one or two or more of other dihydroxy compounds optionally used, and a diester of carbon to carry out transesterification reaction. It is a manufacturing method to carry out.

  Representative examples of diester carbonates include diphenyl carbonate, ditolyl carbonate, bis (chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, bis (biphenyl) carbonate, diethyl carbonate, dimethyl carbonate, dibutyl carbonate and dicyclohexyl carbonate, etc. Can be mentioned. One of these may be used alone, or two or more may be mixed and used. Among these, diphenyl carbonate is particularly preferably used.

The molecular weight of the polycarbonate resin of the present invention can be represented by a reduced viscosity, and the lower limit of the reduced viscosity is preferably 0.20 dl / g or more, more preferably 0.30 dL / g or more, further 0.35 dL / g or more Preferably, the upper limit of the reduced viscosity is preferably 2.00 dL / g or less.
If the reduced viscosity of the polycarbonate resin is too low, the mechanical strength of the resulting film may be small. If it is too large, the flowability at the time of molding may be reduced, and the productivity and the moldability may be reduced.

The reduced viscosity of the polycarbonate resin is precisely measured using a Ubbelohde viscometer using a DT-504 automatic viscometer manufactured by Chuo Rika Co., using methylene chloride as a solvent and a polycarbonate resin concentration of 0.60 g / dl. The temperature is adjusted to 20.0 ° C. ± 0.1 ° C. based on the following values.
From the passage time t _{0 of the} solvent and the passage time t of the solution, the following formula:
η _rel = t / t ₀
The relative viscosity η _rel is determined from the relative viscosity η _rel and the following equation:
η _sp = (η- _{0 0} ) / _{0 0} = _rel -1
More specific viscosity sp sp is determined.
The specific viscosity _{sp sp} is divided by the concentration c (g / dl) to obtain the following equation:
η _red = η _sp / c
Thus, the reduced viscosity (converted viscosity) 求_める_red is determined.

The glass transition temperature (Tg), which is an indicator of heat resistance of the polycarbonate resin of the present invention, is preferably 100 ° C. or more, and more preferably 110 ° C. or more. The upper limit of the glass transition temperature (Tg) is not particularly limited, but is usually 160 ° C. or less.
The measuring method of the glass transition temperature of polycarbonate resin is as being described in the term of the below-mentioned Example.

3. Other Components The film of the present invention may contain an ultraviolet absorber. When the ultraviolet absorber is contained, the weather resistance of the film can be improved, and the ultraviolet deterioration of the liquid crystal and the polarizing film can be prevented. As a ultraviolet absorber used for the film of this invention, a well-known thing, for example, various commercially available things can be used without a restriction | limiting especially. Among them, those commonly used for addition to known aromatic polycarbonate resins can be suitably used.

  As a UV absorber, for example, 2- (2'-hydroxy-5'-tert-octylphenyl) benzotriazole, 2- (3-tert-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzo Triazole, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2,2′- Methylenebis (4-cumyl-6-benzotriazolephenyl) and 2,2'-methylenebis [6- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol] And the like; benzotriazole-based ultraviolet light absorbers such as; 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5- (hex) Triazine-based UV absorbers such as (oxy) -phenol; benzoxazine-based UV absorbers such as 2,2'-p-phenylenebis (1,3-benzoxazin-4-one); 2- (4,6-diphenyl) And hydroxyphenyltriazine-based ultraviolet light absorbers such as -1,3,5-triazin-2-yl) -5- (hexyl) oxy-phenol; and the like.

  The melting point of the UV absorber is particularly preferably in the range of 120 ° C. to 250 ° C. By using a UV absorber having a melting point of 120 ° C. or more, the film surface may be stained by a bleed out phenomenon in which the UV absorber coagulates on the film surface with the passage of time, or when film forming using a die or metal roll, Bleed-out prevents them from becoming soiled and makes it easier to reduce and improve film surface haze.

  From these viewpoints, as the UV absorber, 2,2′-methylenebis [6- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol], 2 -(2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- [2'- Hydroxy-3 ′-(3 ′ ′, 4 ′ ′, 5 ′ ′, 6 ′ ′-tetrahydrophthalimidomethyl) -5′-methylphenyl] benzotriazole, 2,2-methylenebis [4- (1,1,3,3-tetra) Benzotriols such as methylbutyl) -6- (2H-benzotriazol-2-yl) phenol and 2- (2-hydroxy-3,5-dicumylphenyl) benzotriazole It is preferable to use a azole based UV absorber and a hydroxyphenyl triazine based UV absorber such as 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5- (hexyl) oxy-phenol. .

Among these, benzotriazole-based and triazine-based ultraviolet absorbers are preferably used from the viewpoint of effectively preventing the compatibility with the polycarbonate resin of the present invention and the ultraviolet deterioration of liquid crystals and polarizing films.
One of these ultraviolet absorbers may be used alone, or two or more thereof may be used in combination.

The ultraviolet absorber is preferably contained in the film of the present invention in a ratio of 0.0001 to 20 parts by weight with respect to 100 parts by weight of the polycarbonate resin, and 0.0005 to 15 parts by weight. It is more preferable to contain in the ratio of weight part or less, and it is still more preferable to contain in the ratio of 0.001 weight part or more and 10 weight parts or less.
By containing the ultraviolet absorber in such a range, the weather resistance of the film of the present invention is improved without causing the bleeding of the ultraviolet absorber on the film surface or the deterioration of the mechanical properties of the film, and the ultraviolet light of the liquid crystal or polarizing film. Deterioration can be prevented.

  To the extent that the object of the present invention is not impaired, the film of the present invention may also contain other additives such as a silane coupling agent, an antioxidant, a weathering stabilizer, etc. as an additive component other than an ultraviolet absorber. You may contain. Moreover, you may contain resin other than polycarbonate resin of this invention in the range which does not impair the objective of this invention.

4. Method for Producing Film The method for producing a film of the present invention uses the polycarbonate resin of the present invention as a main component, and produces three-dimensional birefringence (Nx, Ny, Nz), in-plane retardation (Re), and thickness retardation Any method may be used as long as it can produce a film in which (Rth) satisfies the above conditions (1) to (3), and there is no particular limitation. For example, a raw material containing the polycarbonate resin of the present invention as a main component The method of biaxially stretching the film obtained by forming into a film on specific conditions is mentioned. The method for producing this film will be described below.

4-1. Film forming method of film The film forming method of the film of the present invention includes known methods, for example, melt mixing equipment such as solution flow method, single screw extruder, multi-screw extruder, Banbury mixer, kneader, An extrusion casting method using a T-die, a calendar method, etc. can be adopted, and there is no particular limitation, but in the present invention, an extrusion casting method using a T-die is preferable in terms of handling properties and productivity. Used for The molding temperature in the extrusion casting method using a T-die is appropriately adjusted depending on the flow characteristics and film forming properties of the polycarbonate resin used, but it is generally 80 ° C. or higher, preferably 100 ° C. or higher, more preferably 120 ° C. or higher, and more Preferably, the temperature is 140 ° C. or higher, and generally 320 ° C. or lower, preferably 300 ° C. or lower, more preferably 280 ° C. or lower, and still more preferably 260 ° C. or lower. It is preferable to lower the molding temperature in order to suppress an increase in resin pressure and an increase in fish eyes. Various additives such as a silane coupling agent, an antioxidant, an ultraviolet light absorber, and a weathering stabilizer may be dry-blended with a polycarbonate resin in advance and then supplied to the hopper, or all materials such as a polycarbonate resin may be pre-blended. The mixture may be melt mixed to prepare pellets and then supplied, or a master batch may be prepared and supplied, in which only the additive is previously concentrated on a resin such as polycarbonate resin.

4-2. Film Stretching Method The film of the present invention in which the three-dimensional birefringence (Nx, Ny, Nz), the in-plane retardation (Re), and the thickness retardation (Rth) satisfy the above conditions (1) to (3) Further, the film obtained as described above can be obtained by drawing. A general biaxial stretching method such as the following (1) to (4) can be adopted as a film stretching treatment method, and the method is not particularly limited, but in the present invention, the film transport direction It is preferable from the viewpoint of productivity to perform sequential biaxial stretching in which tenter stretching is performed in a direction perpendicular to the film transport direction after roll stretching.
(1) Sequential biaxial stretching in which tenter stretching is performed in the direction orthogonal to the film transport direction after roll stretching is performed in the film transport direction
(2) Sequential biaxial stretching in which roll stretching is performed in the film transport direction after tenter stretching is performed in the direction orthogonal to the film transport direction
(3) After carrying out tenter stretching in the direction orthogonal to the film transport direction, successive biaxial stretching in which the film itself is at right angle and tenter drawing is carried out again
(4) Simultaneous biaxial stretching

In the biaxial stretching method carried out in the present invention, uniaxial stretching is carried out so that the in-plane retardation (Re) and thickness retardation (Rth) obtained particularly satisfy the conditions of (2) and (3). It is preferable that the eye drawing temperature (T1), the drawing ratio (V1), the drawing temperature for biaxial drawing (T2), and the drawing ratio (V2) satisfy the following conditions (4) and (5), in particular It is preferable to satisfy the following conditions (4A) and (5A).
(4) 10 ° C <T2-T1 <20 ° C
(5) 0.2 times <V2-V1 <1.0 times (4A) 12 ° C. ≦ T2-T1 ≦ 18 ° C.
(5A) 0.3 times ≦ V2-V1 ≦ 0.9 times

  In addition, the unit of extending | stretching temperature (T1) and (T2) is "degreeC" here, and extending ratio (V1) and (V2) are "double."

When the difference T2-T1 in the drawing temperature is 10 or less, the rate of increase in three-dimensional birefringence Nx, Ny, Nz at the time of drawing is high, and the difference between Nx and Ny, Nz becomes too large, and a predetermined in-plane retardation is obtained. (Re) and the thickness retardation (Rth) can not be contained, and when T2-T1 is 20 or more, the difference between Nx and Ny decreases and the predetermined in-plane retardation (Re) It can not fit in the range.
In addition, when the difference V2-V1 in the draw ratio is 0.2 or less, the difference between the three-dimensional birefringence Nx, Ny, and Nz becomes too large to be within the predetermined thickness retardation (Rth). When V1−V2 is 1.0 or more, the difference between Nx and Ny is small, and the difference can not be within the predetermined thickness retardation (Rth).

  In addition, the stretching temperature (T1), stretching ratio (V1), and stretching temperature (T2) and stretching ratio (V2) of the biaxial stretching in the biaxial stretching process are the above (4) and (B). The conditions of 5), preferably those satisfying the conditions of (4A) and (5A) may be used, but as specific stretching conditions, the stretching temperature (T1) of uniaxial stretching is (Tg-10) to (Tg-10) In the range of Tg + 20) ° C., the draw ratio (V1) is in the range of 1.1 to 2.5 times, and in the biaxial stretching direction, the draw temperature (T2) is in the range of (Tg + 10) to (Tg + 40) ° C., the draw ratio It is preferable that (V2) be set to satisfy the above condition in the range of 1.3 to 3.5 times. Here, "Tg" is the glass transition temperature (Tg) of the film-forming raw material of the film which has polycarbonate resin as a main component.

5. Liquid Crystal Display Device The film of the present invention is excellent in transparency, dimensional stability, moisture and heat resistance, and excellent in optical properties, and therefore, the retardation film of the present invention using such a film of the present invention is a television or personal computer. A high quality display screen can be realized as a member of a liquid crystal display device such as a digital camera or a mobile phone, and the workability at the time of manufacturing the liquid crystal display device is also excellent.

  As described above, when the display side is the front side and the opposite side (backlight side) is the rear side, the liquid crystal display has a configuration of front side polarizing plate / liquid crystal / rear side polarizing plate. Further, depending on the liquid crystal system, the retardation film is sandwiched to prevent light leakage of the liquid crystal device. For example, in the VA liquid crystal system, it is called front side polarizing plate / retardation film / liquid crystal / retardation film / rear side polarizing plate It becomes composition.

  In the film of the present invention, a polarizing film is adhered on one film surface side via an adhesive layer, and on the other film surface side, a liquid crystal or another functional film or a transparent substrate via an adhesive layer. It can be glued. The other functional films are not particularly limited, but, for example, high refractive index films, low refractive index films, antireflection films obtained by laminating them, optical films such as color correction films, hard coat films, antifouling films, An electromagnetic wave shield film, an infrared ray absorption film, an ultraviolet ray absorption film etc. are mentioned. Moreover, as a transparent base material, glass as a support substrate and various transparent films are mentioned.

  EXAMPLES Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited by these examples and comparative examples. In addition, below, the conveyance direction at the time of extending | stretching of a film is described as MD, and the right angle direction is described as TD.

[Evaluation method]
In the following, measurement and evaluation of various physical properties and the like were performed as follows.

<Glass transition temperature (Tg)>
Using a differential scanning calorimeter (manufactured by PerkinElmer Co., Ltd., trade name: Pyris 1 DSC), heat up about 10 mg of the sample from room temperature to 250 ° C. at a heating rate of 10 ° C./min according to JIS K7122 After holding at 5 ° C for 5 minutes, the temperature is lowered to room temperature at a cooling rate of 10 ° C / min, and the glass transition temperature (Tg) is measured from the thermogram measured when the temperature is raised again to 250 ° C at a heating rate of 10 ° C / min. Was read.

<Three-dimensional birefringence (Nx, Ny, Nz), in-plane retardation (Ro) and thickness retardation (Rth)>
Each film was measured using a retardation measurement apparatus (manufactured by Oji Scientific Co., Ltd., trade name: KOBRA-WR). Rth was calculated from the phase difference when the incident angle was 0 ° and when it was 40 °. From the measurement results, it was evaluated as follows.
<Three-dimensional birefringence (Nx, Ny, Nz)>
○: Nx>Ny> Nz is satisfied.
X: Nx>Ny> Nz is not satisfied.
<In-plane retardation (Re)>
○: 30 nm ≦ Re ≦ 100 nm.
X: Re <30 nm or 100 nm <Re.
<Thickness phase difference (Rth)>
○: 100 nm ≦ Rth ≦ 180 nm.
X: Rth <100 nm or 180 nm <Rth.
<Overall evaluation>
:: Three-dimensional birefringence (Nx, Ny, Nz), in-plane retardation (Re), and thickness retardation (Rth) are all ○
X: Any one or more of three-dimensional birefringence (Nx, Ny, Nz), in-plane retardation (Re), and thickness retardation (Rth) is x

[Polycarbonate resin]
The polycarbonate resin used for preparation of a film is a molar ratio of a structural unit derived from isosorbide which is a dihydroxy compound and a structural unit derived from tricyclodecane dimethanol, obtained by the method according to JP 2008-024919A. Is a isosorbide / tricyclodecanedimethanol = 6/4, and has a glass transition temperature (Tg) of 132 ° C.

Example 1
The above polycarbonate resin is charged into a φ65 mm single screw extruder, melt-kneaded at a barrel setting temperature of 220 to 240 ° C., extruded from a die having a width of 1350 mm and a lip gap of 0.5 mm (setting temperature 240 ° C.), and then 100 ° C. It wound up with the cast roll temperature-controlled, and produced the single-layer film with a film thickness of 100 micrometers.

  This single-layer film was roll stretched to MD, and then stretched by sequential biaxial stretching method in which tenter stretching was performed to TD. The stretching temperature (T1), stretching ratio (V1), stretching temperature (T2) and stretching ratio (V2) of biaxial stretching at that time are as shown in Table 1, and the relationship is T2-T1. It was = 16 and V2-V1 = 0.5. Moreover, the film thickness of the obtained stretched film was 35 micrometers.

Example 2
After the single-layer film of Example 1 was roll stretched to MD, stretching was performed by a sequential biaxial stretching method in which tenter stretching was performed to TD. The stretching temperature (T1), stretching ratio (V1), stretching temperature (T2) and stretching ratio (V2) of biaxial stretching at that time are as shown in Table 1, and the relationship is T2-T1. It was = 12 and V2-V1 = 0.9. Moreover, the film thickness of the obtained stretched film was 25 micrometers.

Comparative Example 1
After the single-layer film of Example 1 was roll stretched to MD, stretching was performed by a sequential biaxial stretching method in which tenter stretching was performed to TD. The stretching temperature (T1), stretching ratio (V1), stretching temperature (T2) and stretching ratio (V2) of biaxial stretching at that time are as shown in Table 1, and the relationship is T2-T1. It was = 0 and V2-V1 = 0.4. Moreover, the film thickness of the obtained stretched film was 51 micrometers.

Comparative Example 2
After the single-layer film of Example 1 was roll stretched to MD, stretching was performed by a sequential biaxial stretching method in which tenter stretching was performed to TD. The stretching temperature (T1), stretching ratio (V1), stretching temperature (T2) and stretching ratio (V2) of biaxial stretching at that time are as shown in Table 1, and the relationship is T2-T1. It was = 16 and V2-V1 = 1.1. Moreover, the film thickness of the obtained stretched film was 24 micrometers.

  The evaluation results of the films of Examples and Comparative Examples are shown in Table 1.

As is clear from Table 1, the films of Examples 1 and 2 are made of polycarbonate resin, and by sequential biaxial stretching under specific stretching conditions, three-dimensional birefringence (Nx, Ny, Nz), in-plane position The phase difference (Re) and the thickness phase difference (Rth) satisfy predetermined conditions, and the optical properties of the retardation film are excellent.
On the other hand, in Comparative Example 1, since T2-T1 at the time of successive biaxial stretching does not satisfy the condition (4), both in-plane retardation (Re) and thickness retardation (Rth) are optical characteristics outside the scope of the present invention. In Comparative Example 2, the thickness retardation (Rth) is out of the range of the present invention because V2-V1 does not satisfy the condition (5) at the time of successive biaxial stretching, and the optical is unsuitable for the retardation film. It became a characteristic.

Claims (10)

It is a film having a polycarbonate resin as a main component and having the following characteristics (1) to (3),
The polycarbonate resin contains a structural unit derived from a dihydroxy compound represented by the following formula (I), and is further derived from a dihydroxy compound having no aromatic ring other than the dihydroxy compound represented by the following formula (I) contains a structural unit,
The dihydroxy compound having no aromatic ring other than the dihydroxy compound represented by the following formula (I) is an alicyclic dihydroxy compound containing a 5- or 6-membered ring structure,
Film glass transition temperature of the polycarbonate resin is characterized der Rukoto 160 ° C. or less.
(1) Three-dimensional birefringence (Nx, Ny, Nz) is Nx>Ny> Nz.
(2) In-plane retardation (Re) is 30 nm ≦ Re ≦ 100 nm.
(3) Thickness retardation (Rth) is 100 nm ≦ Rth ≦ 180 nm.

A structural unit derived from a dihydroxy compound having no aromatic ring other than the dihydroxy compound represented by the above formula (I) is a structural unit derived from tricyclodecane dimethanol represented by the following formula (II) The film according to claim 1.

  The retardation film which consists of a film of Claim 1 or 2.   The polarizing plate produced using the film of Claim 1 or 2.   The liquid crystal display device provided with the polarizing plate of Claim 4. It is a method for producing a film having the following characteristics (1) to (3) by biaxially stretching a film obtained by film-forming a raw material containing a polycarbonate resin as a main component, and the biaxial The stretching temperature (T1) of the uniaxially stretched eye in stretching, the stretching ratio (V1), and the stretching temperature (T2) of the biaxially stretched eye, the stretching ratio (V2) are the following conditions (4) and (5): Meet
The polycarbonate resin contains a structural unit derived from a dihydroxy compound represented by the following formula (I), and is further derived from a dihydroxy compound having no aromatic ring other than the dihydroxy compound represented by the following formula (I) contains a structural unit,
The dihydroxy compound having no aromatic ring other than the dihydroxy compound represented by the following formula (I) is an alicyclic dihydroxy compound containing a 5- or 6-membered ring structure,
Method of producing a film having a glass transition temperature of the polycarbonate resin is characterized der Rukoto 160 ° C. or less.
(1) Three-dimensional birefringence (Nx, Ny, Nz) is Nx>Ny> Nz.
(2) In-plane retardation (Re) is 30 nm ≦ Re ≦ 100 nm.
(3) Thickness retardation (Rth) is 100 nm ≦ Rth ≦ 180 nm.
(4) 10 ° C <T2-T1 <20 ° C
(5) 0.2 times <V2-V1 <1.0 times

A structural unit derived from a dihydroxy compound having no aromatic ring other than the dihydroxy compound represented by the above formula (I) is a structural unit derived from tricyclodecane dimethanol represented by the following formula (II) The manufacturing method of the film of Claim 6.

  The manufacturing method of the retardation film which manufactures retardation film by the manufacturing method of the film of Claim 6 or 7. The manufacturing method of the polarizing plate which manufactures a polarizing plate using the film manufactured by the manufacturing method of the film of Claim 6 or 7.   The manufacturing method of the liquid crystal display device which provides a polarizing plate manufactured by the manufacturing method of the polarizing plate of Claim 9, and manufactures a liquid crystal display device.