JP2009209292A - Polyester resin composition for optical use - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin for optical use having a low photoelastic modulus, and an optical base material and an optical film for optical use excellent in wavelength dispersibility suitable for a phase difference film, using the same. <P>SOLUTION: A fluorene polyester resin composition/the optical film for the optical use contains 0.1-30 wt.% of polystyrene fine particle having 0.01-1.0 μm of average particle size. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical polyester resin composition having a small photoelastic coefficient and excellent heat resistance, and relates to an optical film such as an optical substrate or a retardation film using the resin.

  As optical elements, glass having excellent transparency and small birefringence has been used for a long time. However, since it is inferior in moldability and difficult to reduce in weight, recently, polymer materials with excellent moldability, light weight, and easy property control have been used for disc substrates, lenses, cables, various display films, etc. according to their characteristics. Yes.

  Among them, functional optical films such as retardation films and prism sheets are composed of polymethyl methacrylate (hereinafter referred to as PMMA) and cyclic polyolefin (COC), and are used for liquid crystal displays and the like.

  However, PMMA has a large dimensional change due to moisture absorption, is expensive, and film formation is not easy. In addition, when COC is used as a retardation film, it is necessary to bond a plurality of films in order to match the retardation in the entire visible light region, and the bonding cost is high, and there is a limit to reducing the thickness and weight of the display. There's a problem.

  On the other hand, a film made of polyester typified by polyethylene terephthalate (PET) or polyethylene naphthalate (PEN) or polycarbonate (PC) typified by bisphenol A type polycarbonate has high transparency and good moldability. It is used as an optical film. However, these films have very large birefringence and a photoelastic coefficient, and biaxially stretched films are not suitable for retardation films and prism sheets because of insufficient moldability.

  Therefore, a method of modifying these polyesters and polycarbonates by copolymerization has been studied. For example, Patent Document 1 discloses a PET in which a fluorene compound is introduced, and Patent Document 2 discloses a polyester composed of an aliphatic dicarboxylic acid and a fluorene compound. Documents 3 and 4 propose polyesters composed of alicyclic dicarboxylic acids and fluorene compounds.

  However, since the polyester described in Patent Document 1 has a large terephthalic acid ratio, the photoelastic coefficient is large and the optical anisotropy tends to remain. Further, polyesters composed of an aliphatic dicarboxylic acid and a fluorene compound described in Patent Document 2 have low glass transition temperature, have low heat resistance, and are easily colored as a resin, and thus are not suitable as optical resins.

  Moreover, although the polyester which consists of alicyclic dicarboxylic acid and the fluorene compound of patent document 3 and 4 is excellent in isotropic, resin with a small photoelastic coefficient cannot be obtained only by this.

As for the additive to the polyester resin, various studies have been made such as improving the slipperiness of the surface by adding fine particles as in Patent Document 5, but there is no effective effect on reducing the photoelastic coefficient.
JP-A-3-168211 JP-A-7-188401 Japanese Patent Laid-Open No. 9-302077 JP 2004-315676 A JP-A-4-214758

  The present invention provides an optical polyester resin and film that solves the above-described problems of the prior art and has a small photoelastic coefficient and excellent wavelength dispersibility and heat resistance, particularly an optical polyester film suitable for a retardation film. There is.

In order to solve the above problems, the present invention has the following features.
(1) A fluorene polyester resin composition comprising 0.1 to 30% by weight of polystyrene-based fine particles having an average particle diameter of 0.01 to 1.0 μm.
(2) The fluorene polyester resin composition according to (1), wherein the fluorene polyester contains an alicyclic dicarboxylic acid residue and a structural unit represented by the following chemical formula (1).

However, R ¹ in the formula are the same or different alkylene group having 1 to 4 carbon atoms, p is an integer of 0 to 3. R ² and R ³ represent the same or different alkyl groups having 1 to 30 carbon atoms, cycloalkyl groups, and aryl groups, and q and r represent integers of 0 to 4.
(3) The fluorene polyester resin composition according to (1) or (2), wherein the refractive index difference between the fine particles and the fluorene polyester is 0.01 or less.
(4) The film comprising the fluorene polyester resin composition according to any one of (1) to (3), wherein the haze is 20.0% or less.
(5) The retardation film according to (4).
(6) The retardation film according to (5), wherein the photoelastic coefficient is −24 × 10 ⁻¹² Pa ⁻¹ or more and 24 × 10 ⁻¹² Pa ⁻¹ or less.
(7) R (450) (nm) / R (550) (nm) is less than 1.0, where R (λ) (nm) is the retardation in the film plane for light of wavelength λ (nm). The retardation film according to (5) or (6), wherein the retardation film is present.

  According to the present invention, an optical polyester resin having a small photoelastic coefficient, excellent wavelength dispersibility and heat resistance, and a film thereof can be provided. That is, for example, when applied to a phase difference film for a liquid crystal display, there is no phase difference unevenness, and a stable phase difference can be expressed even during production and use. In addition, since the wavelength dispersibility is excellent, it is possible to reduce contrast reduction and hue change at low cost.

  The present invention is described in detail below.

  The present invention is characterized in that the polyester composition contains 0.1 to 30% by weight of polystyrene fine particles having an average particle size of 0.01 to 1.0 μm. By containing this particle | grain, a photoelastic coefficient can be made low compared with the case of resin itself.

  A preferable average particle diameter of the fine particles is 0.01 to 1.0 μm, more preferably 0.05 to 0.5 μm, and still more preferably 0.1 to 0.4 μm. When the particle size is smaller than 0.01 μm, the effect of reducing photoelasticity is not sufficient, and when it is larger than 1.0 μm, the transparency of the resin is remarkably lowered, making it impossible to apply to optical applications.

  The preferable addition amount of the fine particles is 0.1 to 30% by weight, more preferably 0.5 to 20% by weight, and still more preferably 1 to 10% by weight. When the addition amount is less than 0.1% by weight, the effect of reducing the photoelasticity is not sufficient, and when it is more than 30% by weight, the addition of the transparency of the resin is remarkable, making it impossible to apply to optical applications.

  As the fine particles, organic particles or organic polymer particles, for example, vinyl particles such as styrene particles and acrylic particles, particles containing silicone, polytetrafluoroethylene, phenol resin, and the like can be used. Of these, styrenic fine particles are preferred from the viewpoint of the transparency of the resin composition. Styrenic fine particles are fine particles containing a styrene monomer as a homopolymerization component or copolymerization component.

  Styrene monomers include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, p-ethylstyrene, 2,4-dimethylstyrene, p-methoxystyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, 2,4-dichlorostyrene, pn-butylstyrene, pt-butylstyrene, pn-hexylstyrene, p- Examples include octyl styrene, styrene sulfonic acid, sodium styrene sulfonate, and the like. One or more of these may be used in combination.

  Other monomer components that can be copolymerized with styrene monomers include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and the like. (Meth) acrylic acid esters, acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid, maleic anhydride, and other unsaturated carboxylic acids. In addition, glycidyl (meth) acrylate, vinylbenzylamine, acrylamide, methacrylamide, acrylamide-t-butylsulfonic acid, 2-sulfoethyl methacrylate, 2-methoxyethyl acrylate, chloromethylstyrene, polyethylene oxide side chain modified (meth) acrylate Specific functional group-containing monomers such as can also be mentioned.

  The reason why the photoelastic coefficient of the resin composition is reduced by adding the fine particles is not clear in detail, but even when stress is applied to the resin, relatively soft organic fine particles are deformed to absorb the strain. Therefore, it is considered that this is because deformation and orientation change of the fluorene polyester are suppressed.

  The styrenic fine particles may have a single composition or a multilayer structure of polymers having different compositions. In the case of a multilayer structure of polymers having different compositions, it is sufficient that a styrene monomer is copolymerized in at least one layer. For example, a two-layer structure in which the shell layer is a styrene polymer and the core layer is an acrylic polymer is also a preferable structure. In the present invention, from the viewpoint of transparency and reduction in photoelastic coefficient, the shell layer has a refractive index close to that of the resin, the core layer has an acrylic polymer, etc. The two-layer structure is the most preferable particle structure. Moreover, it is also preferable that it is a crosslinked structure.

  The difference in refractive index between the fine particles and fluorene polyester is preferably 0.1 or less, more preferably 0.03 or less, and most preferably 0.01 or less. When the difference in refractive index is greater than 0.1, transparency is lowered when particles are added to fluorene polyester, making it difficult to apply to optical applications. By reducing the difference in refractive index, transparency can be maintained and the amount of fine particles added can be increased, so that the photoelasticity reduction effect is also increased.

  In general, the refractive index of fluorene polyester is in the range of 1.54 to 1.65. The higher the copolymerization ratio of aromatic monomers such as fluorene and terephthalic acid, and the higher the ester group concentration per unit weight, the higher the refractive index. On the other hand, when the copolymerization ratio of the aromatic monomer is lowered or the ester group concentration is lowered by using a high molecular weight monomer such as decalin dicarboxylic acid, the refractive index can be controlled to be low.

  Similarly, by increasing the high refractive index monomer copolymerization ratio containing aromatics such as styrene in the styrene particles, the high refractive index can be increased, and the low refractive index monomer copolymerization ratio such as acrylate ester can be decreased. It can be controlled to a low refractive index.

  The resin composition preferably has a glass transition temperature of 100 ° C. or higher. When this resin is used in various applications such as retardation films, reflective films, protective films, etc. for LCD televisions, it is heated by the internal heat of the backlight and the external environment, but the characteristics do not change due to this heating. Heat resistance is necessary. When the environmental temperature exceeds Tg, the molecules easily move, and thus the phase difference may change in the case of a dimensional or shape change or a retardation film. As an optical film used for a general liquid crystal television used indoors, it is preferable to have a Tg of 100 ° C. or higher. In order to control Tg high, it is preferable that the resin contains many cyclic molecular structures. Here, the cyclic molecular structure may contain an alicyclic ring, an aromatic ring, or a part of multiple bonds, and atoms other than carbon atoms and oxygen atoms such as hydrogen atoms, nitrogen atoms, silicon atoms, sulfur atoms, phosphorus atoms, etc. It may be contained.

  The haze of the film made of the resin composition of the present invention is preferably 20.0% or less. Preferably it is 3.0% or less, More preferably, it is 2.0% or less. When the haze is higher than 20.0%, the transparency is lowered and the optical film may not be suitable for use.

The film of the present invention preferably has a smaller photoelastic coefficient. For example, when this resin composition is used for a retardation film, a residual stress generated by thermal expansion of other members bonded to the retardation film, contraction of the polarizing film, pressing by a frame, or the like is applied. Here, if the photoelastic coefficient is large, a change in phase difference occurs due to residual stress, and phase difference unevenness occurs, which may cause a reduction in contrast and a change in hue. The smaller the photoelastic coefficient is, the smaller the change in phase difference with respect to the stress is, and it is preferably −32 × 10 ⁻¹² Pa ^{−1 to} 32 × 10 ⁻¹² Pa ⁻¹ , more preferably −24 × 10 ^{−12. Pa -1 ~24 × 10 -12 Pa -1} , still more preferably ^{-18 × 10 -12 Pa -1 ~18 ×} 10 -12 Pa -1. In order to control the photoelastic coefficient low, it is preferable to reduce the photoelastic coefficient of the resin itself by controlling the ratio of π-electron rich functional groups such as aromatic rings, ester groups and carbonate groups in the resin for fluorene polyester. Further, it is preferable to further reduce the photoelastic coefficient by adding styrene-based fine particles.

  The resin of the present invention is a fluorene polyester resin composition. The resin composition can be used for various optical applications such as a disk substrate, a lens, a cable, and various display films, but a retardation film is the most preferable application.

  Here, the fluorene structure gives excellent wavelength dispersion when a resin is used as a retardation film.

  The retardation film is a film that causes a difference between the phase of the fast axis and the phase of the slow axis when light of a certain wavelength passes. In the present invention, the retardation film is, for example, a quarter wavelength. Λ / 4 phase difference film that gives a phase difference of λ / 2, λ / 2 phase difference film that gives a phase difference of ½ wavelength, a viewing angle widening film, an optical compensation film, and all other films that give a phase difference.

  Here, the fast axis is the in-plane direction through which light passes the earliest, and the slow axis is the in-plane direction orthogonal to this.

  For example, it is desirable that a quarter wavelength film has a phase difference of ¼ of each wavelength in the visible wavelength region. Here, the phase difference of the wavelength X (nm) is described as R (X) (nm). For example, R (450) and R (550) in the visible wavelength region will be briefly described. When used as a retardation film of a reflective liquid crystal display, all visible wavelengths are not formed by laminating a plurality of retardation films. In order to obtain a broadband retardation film in which the retardation of the wavelength in the region approaches the ideal value, it is preferable to satisfy the following formula (1).

R (450) / R (550) = (450/4) / (550/4) = 0.818 (1)
On the other hand, ordinary polyester, polycarbonate, cyclic polyolefin and the like are represented by the following formula (2). Regarding the wavelength dispersion of the phase difference, the state of the following expression (2) is called forward dispersion.

R (450) / R (550)> 1 (2)
On the other hand, the state of the following expression (3) that is close to ideal is called inverse dispersion.

R (450) / R (550) <1 (3)
There is a demand for a retardation film that satisfies the above equation (3) with a single sheet because of the reduction in constituent members and the reduction in bonding costs. In the present application, a film exhibiting reverse dispersion is referred to as a film excellent in wavelength dispersion.

  When the resin composition of the present invention is a retardation film, satisfying the above formula (3) is also a preferred form of the present invention.

  As molecular design for obtaining reverse dispersion, the same effect as that obtained when a plurality of retardation films are superposed in the molecule may be used. In the present application, a polymer containing the following chemical formula (1) having a cardo structure exhibits the same effect as two types of retardation films superimposed in the main chain direction and the direction orthogonal to the main chain, and vice versa. It becomes possible to show dispersibility.

  Specifically, the fluorene concentration may be increased and the double bond concentration such as an aromatic ring other than fluorene, an ester group, or a carbonate group may be controlled to be low. If the resin is used as it is, the molecular chain is not oriented and no retardation is developed, but a film satisfying the expression (3) is obtained by developing and orienting at the time of film formation.

However, R ¹ in the formula are the same or different alkylene group having 1 to 4 carbon atoms, p is an integer of 0 to 3. R ² and R ³ represent the same or different alkyl groups having 1 to 30 carbon atoms, cycloalkyl groups, and aryl groups, and q and r represent integers of 0 to 4.

Here, the chemical formula (1) is copolymerized with the polyester as a diol residue, and R ^{1 in the} chemical formula (1) is preferably the same and is an ethyl group, and preferably p = 1. When the number of carbon atoms in the alkyl group is large, Tg may decrease, which is not preferable. When p = 0, polymerization reactivity decreases and mechanical strength decreases, which is not preferable. R ² and R ³ are an alkyl group, a cycloalkyl group, and an aryl group, and q and r may be 0 to 4, respectively, but preferably q = r = 0. When q, r ≧ 1, the polymerization reactivity is lowered and the mechanical strength is lowered, which is not preferable.

  Examples of the derivative of the structural unit represented by the chemical formula (1) include 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3. -Methylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3,5-dimethylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3-ethylphenyl] Fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3,5-diethylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3-propylphenyl] fluorene, 9, 9-bis [4- (2-hydroxyethoxy) -3,5-dipropylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3-isopropyl Ruphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3,5-diisopropylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3-n-butylphenyl] Fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3,5-di-n-butylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3-isobutylphenyl] Fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3,5-diisobutylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3- (1-methylpropyl) phenyl ] Fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3,5-bis (1-methylpropyl) phenyl] fluorene, 9,9-bis 4- (2-hydroxyethoxy) -3-phenylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3,5-diphenylphenyl] fluorene, 9,9-bis [4- (2 -Hydroxyethoxy) -3-benzylphenyl] fluorene, 9,9-bis [4- (2-hydroxyethoxy) -3,5-dibenzylphenyl] fluorene, 9,9-bis [4- (3-hydroxypropoxy) ) Phenyl] fluorene 9,9-bis [4- (4-hydroxybutoxy) phenyl] fluorene and the like. Among these, 9,9-bis (4- (2-Hydroxyethoxy) phenyl) fluorene is preferred. These components may be used alone or in combination of two or more. Moreover, although it does not restrict | limit especially as a preparation composition of these fluorene derivatives, 5 mol% or more and 40 mol% or less of a diol component and the whole dicarboxylic acid monomer are preferable, More preferably, they are 10 mol% or more and 35 mol% or less. If it is smaller than this range, it is insufficient to develop heat resistance and reverse dispersibility, and if it is larger than this range, the polymerization reactivity is lowered and the photoelastic coefficient is also increased. In terms of the expression of reverse dispersion, it is effective to increase the copolymerization ratio of monomers having no double bond atoms such as aromatic rings.

  Hereinafter, the resin and film production method of the present invention will be specifically described.

The method for polymerizing the resin of the present invention is not limited, and a known polymerization method such as an esterification method using a dicarboxylic acid and a glycol as a derivative, or an ester exchange method using a dicarboxylic acid diester and a glycol can be used.
As the diol component, various diols can be used in addition to the fluorene derivative. For example, aliphatic diols such as ethylene glycol, trimethylene glycol, 1,2-propanediol, 1,3-propanediol, butanediol, 2-methyl-1,3-propanediol, hexanediol, neopentyl glycol, Cyclohexanedimethanol, cyclohexanediethanol, decahydronaphthalene diethanol, decahydronaphthalene diethanol, norbornane dimethanol, norbornane diethanol, tricyclodecane dimethanol, tricyclodecane diethanol, tetracyclododecane dimethanol, tetracyclo Saturated alicyclic primary diol such as decanediethanol, decalin dimethanol, decalin diethanol, 2,6-dihydroxy-9-oxabicyclo [3,3, ] Nonane, 3,9-bis (2-hydroxy-1,1-dimethylethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane (spiroglycol), 5-methylol-5-ethyl- Saturated heterocyclic primary diols including cyclic ethers such as 2- (1,1-dimethyl-2-hydroxyethyl) -1,3-dioxane and isosorbide, other cyclohexanediols, bicyclohexyl-4,4′-diols, 2 , 2-bis (4-hydroxycyclohexylpropane), 2,2-bis (4- (2-hydroxyethoxy) cyclohexyl) propane, cyclopentanediol, 3-methyl-1,2-cyclopentanediol, 4-cyclopentene- Various alicyclic diols such as 1,3-diol and adamantanediol, bisphenol A, Phenol S, aromatic diols such as styrene glycol can be exemplified. In addition to diols, polyfunctional alcohols such as trimethylolpropane and pentaerythritol can also be used.

  Among these, cyclic diols are preferable from the viewpoint of heat resistance, and saturated heterocyclic diols and alicyclic diols are preferable from the viewpoints of reducing photoelastic coefficient and improving wavelength dispersion (reducing double bond atom concentration). For example, spiro glycol, cyclohexane dimethanol, tricyclodecane dimethanol, decalin dimethanol and the like are preferable. In particular, spiroglycol is preferable as a low cost.

  Two or more kinds can be combined within a range not impairing the object of the present invention. For example, heat resistance, photoelastic coefficient and stretchability can be adjusted by a combination of spiroglycol and ethylene glycol.

  The dicarboxylic acid component of the polyester of the present invention is not particularly limited, and general ester forming derivatives of carboxylic acids can be used. As ester-forming derivatives, acid anhydrides such as terephthalic anhydride, acid halides such as acid chlorides corresponding to dicarboxylic acids, lower alkyl esters such as dimethyl terephthalate, and the like can be used. Here, for convenience, unless otherwise specified, dicarboxylic acid includes an ester-forming derivative of dicarboxylic acid. Specifically, although not limited to these, examples of the aromatic dicarboxylic acid include phthalic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, diphenylether-4,4′-dicarboxylic acid, 4,4′-diphenylmethanedicarboxylic acid, benzylmalonic acid and the like. Examples of chain aliphatic dicarboxylic acids include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, methylmalonic acid, ethylmalonic acid, 2,2-dimethylsuccinic acid, 2,3- Examples include dimethyl succinic acid, 2,3-dimethyl succinic acid, 3-methyl glutaric acid, and 3,3-dimethyl glutaric acid. Examples of alicyclic dicarboxylic acids include 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, cyclopentanedicarboxylic acid, 1,4-cyclohexanedione-2,5-dicarboxylic acid. 2,6-decalin dicarboxylic acid, 1,5-decalin dicarboxylic acid, 1,6-decalin dicarboxylic acid, 2,7-decalin dicarboxylic acid, 2,3-decalin dicarboxylic acid, 2,3-norbornane dicarboxylic acid, bicyclo Saturated alicyclic dicarboxylic acids such as [2,2,1] heptane-3,4-dicarboxylic acid, cis-5-norbornene-endo-2,3-dicarboxylic acid, methyl-5-norbornene-2,3 -Dicarboxylic acid, cis-1,2,3,6-tetrahydrophthalic acid, methyltetrahydrophthalic acid, 3 4,5,6-tetrahydrophthalic acid, unsaturated aliphatic dicarboxylic acids such as exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic acid can be exemplified. In addition to dicarboxylic acid, polyfunctional carboxylic acid components such as trimellitic acid and pyromellitic acid can also be used as the polyfunctional component.

  Among these, cyclic dicarboxylic acids are preferable from the viewpoint of heat resistance, and alicyclic dicarboxylic acids are preferable from the viewpoint of reducing the photoelastic coefficient and improving wavelength dispersibility. Specifically, for example, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 2,6-decalindicarboxylic acid, more preferably 2,6-decalindicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, Most preferred is 2,6-decalin dicarboxylic acid. In the range that does not impair the object of the present invention, it can be used alone or in combination of two or more. For example, by using terephthalic acid and 2,6-decalin dicarboxylic acid together, the photoelastic coefficient, heat resistance, and retardation are adjusted. can do.

The catalyst for producing the polyester of the present invention is not particularly limited, and various catalysts can be used. For example, effective catalysts for transesterification include alkali metal or alkaline earth metal compounds such as calcium acetate, magnesium acetate, lithium acetate, sodium acetate, manganese acetate, cobalt acetate, zinc acetate, tin acetate, alkoxide titanium, etc. Can be used. As the polymerization catalyst, various titanium compounds such as antimony trioxide, germanium dioxide, titanium alkoxide, and the like, and composite oxides of aluminum and silica can be used. Moreover, it is preferable to add various phosphorus compounds such as phosphoric acid, phosphorous acid, dimethyltrimethyl phosphate as a stabilizer. The phosphorus compound is preferably added at the beginning of the polycondensation reaction after the esterification reaction or after the transesterification reaction.

If polymerization is an ester exchange method, for example, 2,6-decalin dicarboxylic acid dimethyl, 9,9-bis (4- (2-hydroxyethoxy) phenyl) fluorene, tricyclo [5,2,1,0 ^2,6] When decanedimethanol or ethylene glycol is used, dimethyl 2,6-decalindicarboxylate, 9,9-bis (4- (2-hydroxyethoxy) phenyl) fluorene, tricyclo [5,2,1,0 ^2,6 ] Charge decanedimethanol and ethylene glycol into a reaction vessel so as to have a predetermined polymer composition. At this time, the reactivity is improved by adding 1.7 to 2.3 moles of ethylene glycol to the total dicarboxylic acid component. After melting these at about 150 ° C., manganese acetate is added as a catalyst and stirred. At 150 ° C., these monomer components become a homogeneous molten liquid. Subsequently, methanol is distilled while gradually raising the temperature to 235 ° C., and a transesterification reaction is performed. After completion of the ester reaction, trimethyl phosphoric acid is added and water is evaporated after stirring. Furthermore, after adding an ethylene glycol solution of germanium dioxide, the reaction product is charged into a polymerization apparatus, and while the temperature inside the apparatus is gradually raised to 285 ° C., the pressure inside the apparatus is reduced from normal pressure to 133 Pa or less, Distill. As the polymerization reaction proceeds, the viscosity of the reaction product increases. When the predetermined stirring torque is reached, the reaction is terminated, and the resin is discharged from the polymerization apparatus into a water tank in a strand shape. The discharged resin is rapidly cooled in a water tank, and after winding it is made into chips with a cutter. The obtained resin is put into a water tank filled with 95 ° C. warm water and subjected to water treatment for 5 hours. After water treatment, use a dehydrator to remove moisture from the resin and remove fines. Although the resin of the present invention can be obtained in this way, it is not limited to the above method.

  Next, the method for producing the retardation film of the present invention will be described.

  About the film forming method, it can form into a film using a well-known film forming method. That is, a production method such as an inflation method, a T-die method, a calendar method, a cutting method, a casting method, an emulsion method, or a hot press method can be used. The elongation method and the hot press method can be preferably used. In the case of a production method using an inflation method or a T-die method, an extruder melt extrusion apparatus equipped with a single-screw or twin-screw extruder can be used. A biaxial kneading extruder with L / D = 25 or more and 120 or less is preferable in order to prevent coloring. Moreover, when melt-kneading using a melt-extrusion apparatus, it is preferable to perform the melt-kneading under reduced pressure or the melt-kneading under nitrogen stream from a viewpoint of coloring suppression. In particular, since the polyester resin film of the present invention is amorphous and difficult to dry, the vent type extruder is preferably used because it can be melt-extruded without drying.

  In order to make a laminated film, it can be produced by using two or more extruders and directly laminating and extruding polyester with a laminated die or a feed block.

The casting method is to measure the molten resin with a gear pump and then discharge it from the T-die die. Then, in the cooled drum shape, electrostatic application method, air chamber method, air knife method, press roll method etc It is preferable to cool and solidify in close contact with a cooling medium such as a drum and rapidly cool to room temperature to obtain an unstretched film. The extrusion temperature can be any temperature in the range of (Tg + 40) ° C. to (Tg + 220) ° C. Since the resin film of the present invention requires good flatness, uniform thickness, and optical characteristics, an electrostatic application method is particularly preferably used.
In the case of producing an unstretched film by the casting method, solvents such as tetrahydrofuran, acetone, methyl ethyl ketone, dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, etc. can be exemplified, and among these, those that do not completely dissolve the fine particles are appropriately selected. It is preferable to use it. The film is obtained by dissolving the optical resin of the present invention in one or more solvents as described above, and using the solution as a heat-resistant film such as polyethylene terephthalate using a bar coater, a T die, a T die with a bar, a die coat, and the like. It can be produced by casting on a flat plate or curved plate (roll) such as a steel belt or metal foil and using a dry method in which the solvent is removed by evaporation or a wet method in which the solution is solidified with a coagulating liquid.

  By stretching the unstretched film produced by the film-forming method described above by a method such as uniaxial stretching or biaxial stretching at any temperature within the range of (Tg-40) ° C to (Tg + 40) ° C. A film imparted with a phase difference can be obtained. The stretching method of biaxial stretching is not particularly limited, and methods such as sequential biaxial stretching and simultaneous biaxial stretching can be used. The stretching temperature is preferably in the range of (Tg-30) ° C to (Tg + 30) ° C, more preferably in the range of (Tg-10) ° C to (Tg + 20) ° C. If the stretching temperature is too high, a sufficient phase difference may not be obtained, and if it is too low, film tearing tends to occur, which is not preferable. The draw ratio can be determined according to the intended phase difference. For example, in order to obtain a resin film having a thickness of 50 μm or less and a retardation of 137.5 nm or more in light having a wavelength of 550 nm, it is important that the draw ratio is 1.5 times or more. The stretching speed is not particularly limited, but 50 to 10,000% / min is preferable. If the stretching speed is too slow, a sufficient phase difference cannot be obtained and productivity is lowered, and if it is too fast, film tearing may occur.

  It is preferable that the film thickness after extending | stretching the film of this invention is 5-300 micrometers. More preferably, it is 7-150 micrometers, More preferably, it is 10-80 micrometers. If the thickness is less than 5 μm, handling of the film may be difficult, and if it exceeds 300 μm, the light transmittance may be lowered. Also, the liquid crystal display using the retardation film of the present invention may be thin and light. It is not preferable from the viewpoint.

In addition to the styrene-based fine particles, the optical film of the present invention includes a surface forming agent, processability improver, antioxidant, ultraviolet absorber, light stabilizer, antistatic agent, lubricant, antiblocking agent, nucleating agent, Additives such as a plasticizer, an antifogging agent, a colorant, a dispersant, and an infrared absorber can be added.
The additive may be colorless or colored, but is preferably colorless and transparent so as not to impair the characteristics of the optical film. Examples of additives for surface formation include inorganic particles such as SiO ₂ , TiO ₂ , Al ₂ O ₃ , CaSO ₄ , BaSO ₄ , CaCO ₃ , carbon black, carbon nanotubes, fullerene, zeolite, and other metal fine powders. Etc. Examples of preferable organic particles include particles made of an organic polymer such as acrylic fine particles, silicone fine particles, phenol resin fine particles, polyimide fine particles, and fluorine resin fine particles in addition to styrene fine particles, or the surface is coated with the above organic polymer. Inorganic particles that have been subjected to treatments such as As a method for adding these additives including styrene-based fine particles, any of addition during polymerization, melt kneading, and solution kneading can be preferably applied. Among these, melt kneading is most preferable from the viewpoint of ease of polymerization control and cost.

  Moreover, as long as reverse dispersibility is not impaired, it may be an alloy with another transparent resin. In the case of a resin, examples of the alloy component include various acrylics, polyesters, polycarbonates, cyclic olefins, and the like.

  The optical polyester film of the present invention described above may be a laminated film with another light-transmitting film. Besides using as a retardation film, a dichroic dye can be added to the film to form a polarizing plate.

  The resin is also preferably used for prism sheets and lens sheets, but when these are produced, it is preferably produced by a hot press method. As a manufacturing method, a mold to be molded is prepared, heated to about Tg + 10 to + 50 ° C., and pressed onto a polyester sheet or film that has not been stretched or has been stretched. After pressing, the pressure is continuously applied for about 1 minute, and the temperature is cooled to Tg or less as it is. When the mold becomes Tg or less of the resin, the mold and the film are peeled off.

  The present invention will be described more specifically with reference to the following examples.

In addition, the measuring method of a physical property and the evaluation method of an effect were performed in accordance with the following method.
(1) Glass transition temperature (Tg)
It measured using the following measuring device.

Apparatus: Differential scanning calorimeter RDC220 Robot DSC (manufactured by Seiko Instruments Inc.)
Measurement conditions: Under nitrogen atmosphere Measurement range: 25-300 ° C
Temperature rising rate: 20 ° C./min According to the method for determining the midpoint glass transition temperature in 9.3 of JIS-K7121 (Control 1987), equidistant from the extended straight line of each baseline to the measurement char to the vertical axis It was set as the temperature at the point where a certain straight line and the curve of the step change portion of the glass unit intersect.
(2) Photoelastic coefficient (Cσ)
It measured using the following measuring device.

Apparatus: Cell gap inspection apparatus RETS-1200 (manufactured by Otsuka Electronics Co., Ltd.)
Sample size: 30mm x 50mm
Measurement spot diameter: φ5mm
Light source: 589nm
The thickness of the sample was d (nm), both ends in the longitudinal direction were sandwiched, and a stress σ (Pa ⁻¹ ) of 9.8 × 10 ⁶ Pa was applied in the longitudinal direction. In this state, the phase difference R (nm) was measured. The photoelastic coefficient Cσ (Pa ⁻¹ ) was calculated using the following equation, where R ₁ was the phase difference before applying tension and R ₂ was the applied phase difference.

Cσ = (R ₂ −R ₁ ) / (σ × d).
(3) Reverse dispersibility (R (450) / R (550))
It measured using the following measuring device.

Apparatus: Automatic birefringence meter KOBRA-21ADH / DSP (manufactured by Oji Scientific Instruments)
Measurement diameter: φ5mm
Measurement wavelength: 480.4 nm, 548.3 nm, 628.2 nm, 752.7 nm
The phase difference at the wavelength x (nm) was described as R (x) (nm).

  The values of R (450) (nm) and R (550) (nm) were calculated using the following Cauchy equation. There are four wavelengths used for calculation of a to d in the equation: 480.4 nm, 548.3 nm, 628.2 nm, and 752.7 nm.

R (λ) = a + b / λ ² + c / λ ⁴ + d / λ ⁶
R (450) (nm) / R (550) (nm) was calculated from the calculated R (450) (nm) and R (550) (nm), and the following ranking was performed.

○: R (450) (nm) / R (550) <1
X: R (450) (nm) / R (550) ≧ 1
(4) Haze The measurement was performed using the following measuring device and conditions.

Apparatus: Direct reading haze meter HGM-2DP (for C light source) (manufactured by Suga Test Instruments Co., Ltd.)
Light source: halogen lamp 12V, 50W
Light receiving characteristics: 395 to 745 nm
Optical conditions: Based on JIS-K7105-1981 Five films were measured, and the average value was calculated with two significant digits.
(5) Average particle diameter A part was cut out from the center of the sheet, an ultrathin section was prepared using a microtome, and observed with a transmission electron microscope (TEM) H-7100 manufactured by Hitachi, Ltd. at a magnification of 20,000 times. The primary particle diameter was measured for any 100 dispersed particles, and the average value was taken as the dispersed particle diameter.
Production Example 1
(Polyester resin A)
Methyl 1,4-cyclohexanedicarboxylate 40.1 parts by mass, 9,9-bis (4- (2-hydroxyethoxy) phenyl) fluorene 70.2 parts by mass Ethylene glycol 24.9 parts by mass (double the dicarboxylic acid component) Each was measured at a ratio of (mol) and charged into a transesterification reactor, and the contents were melted at 150 ° C., and then 0.06 parts by mass of manganese acetate tetrahydrate was added as a catalyst and stirred.

  The temperature was raised to 205 ° C. over 30 minutes, and methanol was distilled while raising the temperature to 235 ° C. over 60 minutes. After distillation of a predetermined amount of methanol, an ethylene glycol solution containing 0.02 parts by mass of trimethylphosphoric acid was added as a catalyst deactivator and stirred for 5 minutes to stop the transesterification reaction.

  After adding an ethylene glycol solution containing 0.04 parts by mass of germanium dioxide, the reaction product is charged into the polymerization apparatus, and the apparatus internal pressure is increased to 290 ° C. over 90 minutes while the apparatus internal temperature is increased to normal pressure. The pressure is reduced to vacuum and ethylene glycol is distilled off. The reaction is terminated when the viscosity of the reaction product increases with the progress of the polymerization reaction and reaches a predetermined stirring torque. At the end of the reaction, the inside of the polymerization apparatus was returned to normal pressure with nitrogen gas, the valve at the bottom of the polymerization apparatus was opened, and gut-shaped polyester was discharged into the water tank. The discharged polyester resin was quenched in a water tank and then cut with a cutter to form a chip.

A polyester chip was thus obtained.
(Polyester water treatment)
The obtained polyester chip was put into a water tank filled with 95 ° C. ion exchange water and water-treated for 5 hours. The chip after the water treatment was separated from the water by a dehydrator. Fines contained in the polyester chips were also removed by this water treatment.
Production Example 2
(Polyester resin B)
Methyl 2,6-decalin dicarboxylate 46.3 parts by mass, spiroglycol 33.3 parts by mass, 9,9-bis (4- (2-hydroxyethoxy) phenyl) fluorene 32.0 parts by mass ethylene glycol 22.6 parts by mass Parts (2 times mole of dicarboxylic acid component) were weighed and charged into a transesterification reactor, and then a polyester chip was obtained in the same manner as in Production Example 1. The obtained polyester was treated with water in the same manner as in Production Example 1.

  The polyester resin characteristics are shown in Table 1.

Example 1
After the polyester resin A is dried under reduced pressure, the styrenic fine particles B are dry blended with the polyester resin A so as to have a content of 0.5 wt%, and the extrusion temperature is 260 using a twin-screw extruder (KZW15TW-45HG manufactured by Technobel). Melting and kneading was carried out at 0 ° C. The polyester resin containing styrene-based fine particles was discharged from the extruder into a water tank, quenched, and then made into chips with a cutter.

The obtained resin chip was dried under reduced pressure, and then formed into a film using the following hot press method. A polyimide film was stacked on a metal plate, and a metal frame having an inner frame of 36 cm square was stacked on the polyimide film. A 2.5 g chip was placed in the center of the metal frame. Further, the polyimide film and the metal plate were overlapped, preheated at 270 ° C. for 2 minutes, and then pressed at a pressure of 10 kgf / cm ² for 10 seconds.

  After the press, the metal plate with the film sandwiched in water was cooled and solidified, and the film was cut out from the metal frame. Further, the cut film is cut into a rectangle, and both ends in the longitudinal direction are held, and in a 125 ° C. oven, uniaxial stretching is performed at a stretching rate of 200% / min and a stretching ratio of 2.7 times to obtain a retardation film. Obtained.

  The stretched film was measured for Tg, photoelastic coefficient, melt viscosity, retardation, and wavelength dispersibility, and are shown in Table 3.

Example 2
After drying the polyester resin A under reduced pressure, the styrene fine particles B are dry blended with the polyester resin A so as to have a content of 1.0 wt%, and the extrusion temperature is 260 using a twin-screw extruder (KZW15TW-45HG manufactured by Technobel). Melting and kneading was carried out at 0 ° C. The polyester resin containing styrene-based fine particles was discharged from the extruder into a water tank, quenched, and then made into chips with a cutter.

  Thereafter, a film was obtained in the same manner as in Example 1, and then uniaxially stretched in an oven at 125 ° C. at a stretching rate of 200% / min and a stretching ratio of 2.7 times to obtain a retardation film.

  The stretched film was measured for Tg, photoelastic coefficient, melt viscosity, retardation, and wavelength dispersibility, and are shown in Table 3.

Example 3
After the polyester resin A is dried under reduced pressure, the styrene fine particles C are dry blended with the polyester resin A so as to have a content of 20.0 wt%, and an extrusion temperature of 260 is used using a twin screw extruder (KZW15TW-45HG manufactured by Technobel). Melting and kneading was carried out at 0 ° C. The polyester resin containing styrene-based fine particles was discharged from the extruder into a water tank, quenched, and then made into chips with a cutter.

Thereafter, a film was obtained in the same manner as in Example 1, and then uniaxially stretched in an oven at 125 ° C. at a stretching rate of 200% / min and a stretching ratio of 2.7 times to obtain a retardation film.

  The stretched film was measured for Tg, photoelastic coefficient, melt viscosity, retardation, and wavelength dispersibility, and are shown in Table 3.

Example 4
After the polyester resin A is dried under reduced pressure, the styrene fine particles C are dry blended with the polyester resin A so as to have a content of 5.0 wt%, and an extrusion temperature of 260 is used using a twin screw extruder (KZW15TW-45HG manufactured by Technobel). Melting and kneading was carried out at 0 ° C. The polyester resin containing styrene-based fine particles was discharged from the extruder into a water tank, quenched, and then made into chips with a cutter.

  Thereafter, a film was obtained in the same manner as in Example 1, and then uniaxially stretched in an oven at 125 ° C. at a stretching rate of 200% / min and a stretching ratio of 2.7 times to obtain a retardation film.

  The stretched film was measured for Tg, photoelastic coefficient, melt viscosity, retardation, and wavelength dispersibility, and are shown in Table 3.

Example 5
After drying the polyester resin B under reduced pressure, the styrene fine particles D are dry blended with the polyester resin B so as to have a content of 5.0 wt%, and an extrusion temperature of 260 is used using a twin-screw extruder (KZW15TW-45HG manufactured by Technobel). Melting and kneading was carried out at 0 ° C. The polyester resin containing styrene-based fine particles was discharged from the extruder into a water tank, quenched, and then made into chips with a cutter.

  Thereafter, a film was obtained in the same manner as in Example 1, and then uniaxially stretched in an oven at 130 ° C. at a stretching rate of 200% / min and a stretching ratio of 2.7 times to obtain a retardation film.

  The stretched film was measured for Tg, photoelastic coefficient, melt viscosity, retardation, and wavelength dispersibility, and are shown in Table 3.

Example 6
After the polyester resin B is dried under reduced pressure, the styrene fine particles D are dry blended with the polyester resin B so as to have a content of 20.0 wt%, and an extrusion temperature of 260 is used using a twin screw extruder (KZW15TW-45HG manufactured by Technobel). Melting and kneading was carried out at 0 ° C. The polyester resin containing styrene-based fine particles was discharged from the extruder into a water tank, quenched, and then made into chips with a cutter.

Thereafter, a film was obtained in the same manner as in Example 1, and then uniaxially stretched in an oven at 125 ° C. at a stretching rate of 200% / min and a stretching ratio of 2.7 times to obtain a retardation film.

  The stretched film was measured for Tg, photoelastic coefficient, melt viscosity, retardation, and wavelength dispersibility, and are shown in Table 3.

Example 7
After drying the polyester resin B under reduced pressure, the styrene fine particles E are dry blended with the polyester resin B so as to have a content of 5.0 wt%, and an extrusion temperature of 260 is used using a twin screw extruder (KZW15TW-45HG manufactured by Technobel). Melt mixing was performed at 0 ° C. A polyester resin containing styrene-based fine particles was discharged from an extruder into a water tank, quenched, and then made into chips with a cutter.

  Thereafter, a film was obtained in the same manner as in Example 1, and then uniaxially stretched in an oven at 130 ° C. at a stretching rate of 200% / min and a stretching ratio of 2.7 times to obtain a retardation film.

  The stretched film was measured for Tg, photoelastic coefficient, melt viscosity, retardation, and wavelength dispersibility, and are shown in Table 3.

Reference example 1
(Blank without styrenic fine particles)
After the polyester resin A was dried under reduced pressure, melt kneading was performed at an extrusion temperature of 260 ° C. using a twin-screw extruder (KZW15TW-45HG manufactured by Technobel). The polyester resin was discharged from the extruder into a water tank, quenched, and then made into chips with a cutter.

  Thereafter, a film was obtained in the same manner as in Example 1, and then uniaxially stretched in an oven at 125 ° C. at a stretching rate of 200% / min and a stretching ratio of 2.7 times to obtain a retardation film.

  The stretched film was measured for Tg, photoelastic coefficient, melt viscosity, retardation, and wavelength dispersibility, and are shown in Table 3.

Reference example 2
(Blank without styrenic fine particles)
After the polyester resin B was dried under reduced pressure, melt kneading was performed at an extrusion temperature of 260 ° C. using a twin screw extruder (KZW15TW-45HG manufactured by Technobel). The polyester resin was discharged from the extruder into a water tank, quenched, and then made into chips with a cutter.

  Thereafter, a film was obtained in the same manner as in Example 1, and then uniaxially stretched in an oven at 130 ° C. at a stretching rate of 200% / min and a stretching ratio of 2.7 times to obtain a retardation film.

  The stretched film was measured for Tg, photoelastic coefficient, melt viscosity, retardation, and wavelength dispersibility, and are shown in Table 3.

Comparative Example 1
After drying the polyester resin B under reduced pressure, the styrenic fine particles A are dry blended with the polyester resin B so as to have a content of 1.0 wt%, and the extrusion temperature is 260 using a twin-screw extruder (KZW15TW-45HG manufactured by Technobel). Melting and kneading was carried out at 0 ° C. The polyester resin containing styrene-based fine particles was discharged from the extruder into a water tank, quenched, and then made into chips with a cutter.

  Thereafter, a film was obtained in the same manner as in Example 1, and then uniaxially stretched in an oven at 130 ° C. at a stretching rate of 200% / min and a stretching ratio of 2.7 times to obtain a retardation film.

  The stretched film was measured for Tg, photoelastic coefficient, melt viscosity, retardation, and wavelength dispersibility, and are shown in Table 3.

Comparative Example 2
After the polyester resin B is dried under reduced pressure, the styrene fine particles A are dry blended with the polyester resin B so as to have a content of 10.0 wt%, and an extrusion temperature of 260 is used using a twin screw extruder (KZW15TW-45HG manufactured by Technobel). Melting and kneading was carried out at 0 ° C. The polyester resin containing styrene-based fine particles was discharged from the extruder into a water tank, quenched, and then made into chips with a cutter.

Thereafter, a film was obtained in the same manner as in Example 1, and then uniaxially stretched in an oven at 130 ° C. at a stretching rate of 200% / min and a stretching ratio of 2.7 times to obtain a retardation film.

  The stretched film was measured for Tg, photoelastic coefficient, melt viscosity, retardation, and wavelength dispersibility, and are shown in Table 3. Since the haze was large, it was impossible to measure both wavelength dispersion and photoelastic coefficient.

Comparative Example 3
After drying the polyester resin A under reduced pressure, the styrenic fine particles B are dry blended with the polyester resin A so as to have a content of 5.0 wt%, and an extrusion temperature of 260 is used using a twin screw extruder (KZW15TW-45HG manufactured by Technobel). Melting and kneading was carried out at 0 ° C. The polyester resin containing styrene-based fine particles was discharged from the extruder into a water tank, quenched, and then made into chips with a cutter.

  Thereafter, a film was obtained in the same manner as in Example 1, and then uniaxially stretched in an oven at 125 ° C. at a stretching rate of 200% / min and a stretching ratio of 2.7 times to obtain a retardation film.

  The stretched film was measured for Tg, photoelastic coefficient, melt viscosity, retardation, and wavelength dispersibility, and are shown in Table 3. Since the haze was large, it was impossible to measure both wavelength dispersion and photoelastic coefficient.

Comparative Example 4
After drying polyester resin A under reduced pressure, styrene-based fine particles F are dry blended with polyester resin A so as to have a content of 1.0 wt%, and using twin screw extruder (KZW15TW-45HG Technobel), extrusion temperature 260 Melting and kneading was carried out at 0 ° C. The polyester resin containing styrene-based fine particles was discharged from the extruder into a water tank, quenched, and then made into chips with a cutter.

  Thereafter, a film was obtained in the same manner as in Example 1, and then uniaxially stretched in an oven at 125 ° C. at a stretching rate of 200% / min and a stretching ratio of 2.7 times to obtain a retardation film.

  The stretched film was measured for Tg, photoelastic coefficient, melt viscosity, retardation, and wavelength dispersibility, and are shown in Table 3. Since the haze was large, it was impossible to measure both wavelength dispersion and photoelastic coefficient.

Comparative Example 5
After the polyester resin B is dried under reduced pressure, the styrene fine particles D are dry blended with the polyester resin B so as to have a content of 45.0 wt%, and an extrusion temperature of 260 is used using a twin screw extruder (KZW15TW-45HG manufactured by Technobel). Melting and kneading was carried out at 0 ° C. The polyester resin containing styrene-based fine particles was discharged from the extruder into a water tank, quenched, and then made into chips with a cutter.

Thereafter, a film was obtained in the same manner as in Example 1, and then uniaxially stretched in an oven at 125 ° C. at a stretching rate of 200% / min and a stretching ratio of 2.7 times to obtain a retardation film.

  The stretched film was measured for Tg, photoelastic coefficient, melt viscosity, retardation, and wavelength dispersibility, and are shown in Table 3. Since the haze was large, it was impossible to measure both wavelength dispersion and photoelastic coefficient.

Comparative Example 6
After drying the polyester resin B under reduced pressure, the styrene fine particles D are dry blended with the polyester resin B so as to have a content of 0.05 wt%, and an extrusion temperature of 260 is used using a twin-screw extruder (KZW15TW-45HG manufactured by Technobel). Melting and kneading was carried out at 0 ° C. The polyester resin containing styrene-based fine particles was discharged from the extruder into a water tank, quenched, and then made into chips with a cutter.

Thereafter, a film was obtained in the same manner as in Example 1, and then uniaxially stretched in an oven at 130 ° C. at a stretching rate of 200% / min and a stretching ratio of 2.7 times to obtain a retardation film. Table 3 shows the measured Tg, photoelastic coefficient, melt viscosity, phase difference, and wavelength dispersibility of the stretched film.

  Table 2 is a fine particle characteristic table used in Examples and Comparative Examples.

Claims (7)

  A fluorene polyester resin composition comprising 0.1 to 30% by weight of polystyrene-based fine particles having an average particle diameter of 0.01 to 1.0 μm. The fluorene polyester resin composition according to claim 1, wherein the fluorene polyester contains an alicyclic dicarboxylic acid residue and a structural unit represented by the following chemical formula (1).

However, R ¹ in the formula are the same or different alkylene group having 1 to 4 carbon atoms, p is an integer of 0 to 3. R ² and R ³ represent the same or different alkyl groups having 1 to 30 carbon atoms, cycloalkyl groups, and aryl groups, and q and r represent integers of 0 to 4.   The fluorene polyester resin composition according to claim 1 or 2, wherein the refractive index difference between the fine particles and the fluorene polyester is 0.01 or less.   The film comprising the fluorene polyester resin composition according to any one of claims 1 to 3, wherein the haze is 20.0% or less.   The retardation film according to claim 4. The retardation film according to claim 5, wherein the photoelastic coefficient is −32 × 10 ⁻¹² Pa ⁻¹ or more and 32 × 10 ⁻¹² Pa ⁻¹ or less.   R (450) (nm) / R (550) (nm) is less than 1.0, where R (λ) (nm) is the retardation in the film plane for light of wavelength λ (nm). The retardation film according to claim 5, wherein the retardation film is a film.