JP2013083907A - Retardation film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a retardation film having excellent flexibility, small rate of variation in retardation under high temperature environment and good retardation stability.SOLUTION: An acrylic retardation film consists of a resin composition (C) containing: a (meta) acrylic resin (A); and elastic organic fine particles (B) containing a conjugated diene monomer structure unit formed by polymerizing a conjugated diene monomer as an essential component and having a volume mean particle diameter of 0.350 μm or less. Before and after a heat accelerating test at 90°C for 200 hours, a rate of variation in in-plane retardation Re (590) at the wave length of 590 nm is 5% or less.

Description

  The present invention relates to a retardation film used for a liquid crystal display device, an organic electroluminescence display device and the like.

  Optical films using birefringence generated by polymer orientation are widely used in the field of image display. One of such optical films is a retardation film incorporated in an image display device for the purpose of color tone compensation, viewing angle compensation, and the like. For example, in a reflective liquid crystal display device (LCD), a retardation plate (λ / 4 plate) having an optical path length difference (retardation) based on a phase difference caused by birefringence is ¼ of the wavelength is used. . In an organic EL display (OLED), an antireflection plate in which a polarizing plate and a λ / 4 plate are combined may be used for the purpose of preventing reflection of external light (Patent Document 1). These optical films exhibiting birefringence are expected to be further expanded in the future.

  Conventionally, cellulose derivatives typified by triacetylcellulose (TAC), polycarbonate, and polycycloolefin have been mainly used for optical films, but these general polymers are birefringent as the wavelength of light becomes shorter. Shows a wavelength dispersibility that increases (that is, the phase difference increases). However, in order to obtain an image display device with excellent display characteristics, on the contrary, an optical film exhibiting wavelength dispersibility that reduces birefringence (that is, phase difference decreases) as the wavelength of light becomes shorter is desirable. It is. In this specification, the wavelength dispersibility in which birefringence decreases as the wavelength of light becomes shorter at least in the visible light region is opposite to the wavelength dispersibility exhibited by general polymers and optical films formed from the polymers. Based on a certain thing, it is called "reverse wavelength dispersion" which is a common name among those skilled in the art.

  As an optical film having reverse wavelength dispersion, an optical film made of a (meth) acrylic resin having an α, β-unsaturated monomer unit having a heteroaromatic group as a constituent unit is disclosed (Patent Literature). 2).

JP 2007-273275 A JP 2009-175727 A

  However, a film made of a (meth) acrylic resin is generally hard and, for example, a problem such as breakage due to bending or tearing when the film is handled tends to occur. Therefore, attempts have been made to improve flexibility by blending elastic organic fine particles with the resin constituting the film or improving the stretching method.

  By the way, as a general behavior of stretched and oriented resin molecules in a film, the molecular orientation is relaxed under a heating environment, and it tends to be difficult to maintain the obtained optical anisotropy as the initial value. If the phase difference changes with time, the display image deteriorates with the operation of the display device such as a liquid crystal panel, which may seriously affect the commercial value of the display device. In particular, in a resin film blended with elastic organic fine particles, there is a tendency that the fluctuation of the retardation value becomes large under a high temperature environment.

  The present invention has been made paying attention to the circumstances as described above, and its purpose is excellent in flexibility, low change rate of phase difference under high temperature environment, and excellent stability of phase difference. The object is to provide a retardation film.

  The retardation film of the present invention that has achieved the above-mentioned object is composed of a (meth) acrylic resin (A) and a conjugated diene monomer structural unit constructed by polymerizing a conjugated diene monomer as essential components. An acrylic phase difference film comprising a resin composition (C) containing elastic organic fine particles (B) having a volume average particle size of 0.350 μm or less, and before and after a thermal acceleration test held at 90 ° C. for 200 hours, The gist is that the rate of change of the in-plane retardation Re (590) at a wavelength of 590 nm is 5% or less.

  In the retardation film of the present invention, the elastic organic fine particles (B) have a core-shell structure including a core portion and a shell portion having a structure having the conjugated diene monomer structural unit as an essential component. preferable.

  In the retardation film of the present invention, the resin composition (C) preferably contains an antioxidant.

  In the retardation film of the present invention, the rate of change of the in-plane retardation Re (590) at a wavelength of 590 nm is preferably 10% or less before and after the thermal acceleration test held at 90 ° C. for 1000 hours.

  In the retardation film of the present invention, the resin composition (C) is preferably a resin composition having a positive intrinsic birefringence.

  In the retardation film of the present invention, when the in-plane retardation for light having a wavelength of 447 nm is Re (447) and the in-plane retardation for light having a wavelength of 590 nm is Re (590), Re (447) / Re ( 590) <1 is preferred.

  In the retardation film of the present invention, the (meth) acrylic resin (A) is preferably a resin having a ring structure in the main chain.

  In the retardation film of the present invention, the ring structure is preferably a lactone ring structure represented by the following general formula (1).

（式（１）中、Ｒ¹、Ｒ²、Ｒ³は、それぞれ独立に、水素原子または炭素数１〜２０のアルキル基、炭素数２〜２０の不飽和脂肪族炭化水素基、または炭素数６〜２０の芳香族炭化水素基であり、前記アルキル基、前記不飽和脂肪族炭化水素基、前記芳香族炭化水素基は、水素原子の一つ以上が、水酸基、カルボキシル基、エーテル基およびエステル基から選ばれる少なくとも１種類の基により置換されていてもよい。）

(In the formula ^{(1), R 1, R} 2, R 3 are each independently a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, unsaturated aliphatic hydrocarbon group having 2 to 20 carbon atoms or carbon atoms, 6 to 20 aromatic hydrocarbon groups, wherein the alkyl group, the unsaturated aliphatic hydrocarbon group, and the aromatic hydrocarbon group are such that one or more of hydrogen atoms are a hydroxyl group, a carboxyl group, an ether group, and an ester. It may be substituted with at least one group selected from the group)

  ADVANTAGE OF THE INVENTION According to this invention, the retardation film which has the outstanding optical characteristic with few change rates of retardation even in a high temperature environment can be provided.

The retardation film of the present invention is an acrylic retardation film composed of a resin composition (C) containing a (meth) acrylic resin (A) and elastic organic fine particles (B).
In the following description, “%” means “% by mass” and “parts” means “parts by mass” unless otherwise specified. In addition, “A to B” indicating a range indicates that the range is A or more and B or less.

[(Meth) acrylic resin (A)]
The (meth) acrylic resin (A) may be a resin having as a structural unit a single or copolymer component of a (meth) acrylic acid monomer such as (meth) acrylic acid ester or (meth) acrylic acid. Here, the (meth) acrylic acid-based monomer only needs to have a site that can be regarded as a (meth) acrylic acid site, and a compound (derivative) that can be regarded as having an appropriate group (including an alkyl group) bonded to the site. Including. That is, the (meth) acrylic resin (A) of the present invention has a (meth) acrylic acid ester unit and / or a (meth) acrylic acid unit as an essential constituent unit, and the (meth) acrylic acid ester or (meta) ) It may have a structural unit derived from a derivative of acrylic acid. In the present specification, “(meth) acryl” means “acryl” and / or “methacryl”.

  Examples of the (meth) acrylic acid ester or (meth) acrylic acid ester derivative include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, and n-butyl (meth) acrylate. , T-butyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, benzyl (meth) acrylate, dicyclopenta (meth) acrylate Esters of (meth) acrylic acid and hydroxy hydrocarbons such as nyl (alkyl (meth) acrylate, aryl (meth) acrylate, aralkyl (meth) acrylate), dicyclopentanyloxy (meth) acrylate Ether bond-introduced derivatives such as ethyl; chloromethyl (meth) acrylate, (meth) acrylate And halogen-introduced derivatives such as 2-chloroethyl toluate; and hydroxy group-introduced derivatives. The hydroxy group-introduced derivatives include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2,3,4,5,6-pentahydroxyhexyl (meth) acrylate, (meth) Hydroxyalkyl (meth) acrylates such as 2,3,4,5-tetrahydroxypentyl acrylate; 2- (hydroxymethyl) alkyl acrylate (eg, methyl 2- (hydroxymethyl) acrylate, 2- (hydroxy Methyl) ethyl acrylate, 2- (hydroxymethyl) isopropyl acrylate, 2- (hydroxymethyl) acrylate n-butyl, 2- (hydroxymethyl) acrylate t-butyl, etc.), 2- (hydroxyethyl) acrylate 2 of alkyl (such as methyl 2- (hydroxyethyl) acrylate) It includes (hydroxyalkyl) acrylic acid alkyl.

Examples of (meth) acrylic acid or (meth) acrylic acid derivatives include (meth) acrylic acids such as acrylic acid and methacrylic acid; alkylated (meth) acrylic acids such as crotonic acid; 2- (hydroxymethyl) acrylic acid And hydroxyalkylated (meth) acrylic acids such as 2- (hydroxyethyl) acrylic acid. Among these, methyl methacrylate is preferable from the viewpoint of heat resistance and transparency of the film.
Each of the (meth) acrylic acid ester (unit), (meth) acrylic acid (unit), and derivatives (units) thereof may be only one kind or two or more kinds.

  The (meth) acrylic resin (A) may have other structural units introduced by copolymerizing the above-described (meth) acrylic acid monomer with other monomers. Examples of such other monomers include styrene, vinyl toluene, α-methyl styrene, α-hydroxymethyl styrene, α-hydroxyethyl styrene, acrylonitrile, methacrylonitrile, methallyl alcohol, allyl alcohol, ethylene, propylene, Examples thereof include monomers having a polymerizable double bond such as 4-methyl-1-pentene, vinyl acetate, 2-hydroxymethyl-1-butene, methyl vinyl ketone, N-vinyl pyrrolidone, and N-vinyl carbazole. These other monomers (structural units) may have only one type or two or more types.

  Structural units derived from (meth) acrylic acid monomers in all structural units of (meth) acrylic resin (A) (that is, derived from (meth) acrylic acid ester units, (meth) acrylic acid units, and derivatives thereof) From the viewpoint of heat resistance of the film, the total proportion of (structural units) is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 70% by mass or more. There is no particular upper limit, most preferably 100%.

  The positive or negative of the intrinsic birefringence of the (meth) acrylic resin (A) itself is determined by the balance between the actions given by the respective structural units (monomers) constituting the resin with respect to the intrinsic birefringence. For example, polymethyl methacrylate (PMMA), which is a typical (meth) acrylic resin, has a negative intrinsic birefringence, but (meth) acrylic resin (A) has a cyclic structure in the main chain, so It has the intrinsic birefringence. When a structural unit (for example, a styrene unit) having an effect of giving negative intrinsic birefringence to the (meth) acrylic resin (A) having a ring structure in the main chain is contained, an acrylic resin (A The degree of freedom of control of the birefringence in the film comprising the above is improved, and the use of the retardation film in the present invention is expanded.

  Intrinsic birefringence refers to the orientation axis from the refractive index n1 of light in a direction parallel to the direction (orientation axis) in which molecular chains are oriented in a layer (for example, a sheet or film) in which resin molecular chains are uniaxially oriented. Is a value obtained by subtracting the refractive index n2 of light in the direction perpendicular to (i.e., "n1-n2").

  The (meth) acrylic resin (A) preferably has a ring structure in the main chain. When a ring structure is introduced into the main chain, the glass transition temperature (Tg) of the (meth) acrylic resin (A) is increased, and the heat resistance of the formed film can be increased. Thus, the film containing the (meth) acrylic resin (A) having a ring structure in the main chain is suitable for use as an optical member, such as being easy to arrange in the vicinity of a heat generating part such as a light source in an image display device. Can be used.

  The type of the ring structure of the main chain is not particularly limited, but for example, at least one selected from a lactone ring structure, a glutaric anhydride structure, a glutarimide structure, a maleic anhydride structure, and an N-substituted maleimide structure is preferable. More preferred is a lactone ring structure, a glutaric anhydride structure, or a glutarimide structure, and particularly preferred is a lactone ring structure.

  The lactone ring structure is not particularly limited, and may be, for example, any of a 4-membered ring to an 8-membered ring, but is preferably a 5-membered ring or a 6-membered ring because of excellent stability of the ring structure. A 6-membered ring is more preferable. Examples of the lactone ring structure which is a 6-membered ring include the structures disclosed in JP-A No. 2004-168882. The lactone ring structure can be easily introduced. Specifically, the precursor ( (Polymer before lactone cyclization) has a high polymerization yield, the lactone ring content in the cyclization condensation reaction of the precursor can be increased, and a polymer having a methyl methacrylate unit as a constituent unit can be used as a precursor. The structure represented by the following general formula (1) is particularly preferred for reasons such as.

In the general formula (1), R ¹ , R ² and R ³ are each independently a hydrogen atom or an organic residue having 1 to 20 carbon atoms, and the organic residue may contain an oxygen atom. Good.
Examples of the organic residue in the general formula (1) include carbons such as a saturated aliphatic hydrocarbon group having 1 to 20 carbon atoms (such as an alkyl group) such as a methyl group, an ethyl group, and a propyl group, an ethenyl group, and a propenyl group. In addition to unsaturated aliphatic hydrocarbon groups having 2 to 20 carbon atoms (such as alkenyl groups), phenyl groups, naphthyl groups and other aromatic hydrocarbon groups having 6 to 20 carbon atoms (such as aryl groups), these saturated aliphatic hydrocarbons. A group in which one or more hydrogen atoms in a group, an unsaturated aliphatic hydrocarbon group or an aromatic hydrocarbon group are substituted with at least one group selected from a hydroxy group, a carboxyl group, an ether group and an ester group, and the like Can be mentioned.

  For example, the lactone ring structure is obtained by polymerizing (preferably copolymerizing) a (meth) acrylic acid monomer A having a hydroxy group and a (meth) acrylic acid monomer B to form a hydroxy group and an ester group or a carboxyl group in the molecular chain. After introducing a group, it can be formed by causing dealcoholization or dehydration-cyclization condensation between these hydroxy group and ester group or carboxyl group. As the polymerization component, the (meth) acrylic acid monomer A having a hydroxy group is essential, and the (meth) acrylic acid monomer B includes the monomer A. Monomer B may or may not coincide with monomer A. When monomer B coincides with monomer A, monomer A is homopolymerized.

Examples of the (meth) acrylic acid monomer A having a hydroxy group include hydroxy group-introduced derivatives of the above (meth) acrylic acid esters, hydroxyalkylated (meth) acrylic acids, and the like, and preferably a monomer having a hydroxyallyl moiety Is included. Specific examples of the (meth) acrylic acid monomer A having a hydroxy group include 2- (hydroxymethyl) acrylic acid, 2- (hydroxyethyl) acrylic acid, and alkyl 2- (hydroxymethyl) acrylate (for example, 2- (Hydroxymethyl) methyl acrylate, 2- (hydroxymethyl) ethyl acrylate, 2- (hydroxymethyl) isopropyl acrylate, 2- (hydroxymethyl) acrylate n-butyl, 2- (hydroxymethyl) acrylate t- Butyl), 2- (hydroxyethyl) alkyl acrylate (for example, 2- (hydroxyethyl) methyl acrylate, 2- (hydroxyethyl) ethyl acrylate), and the like, preferably a monomer having a hydroxyallyl moiety. Some 2- (hydroxymethyl) acrylic acid and 2- ( Rokishimechiru) include alkyl acrylate. Particularly preferred are methyl 2- (hydroxymethyl) acrylate and ethyl 2- (hydroxymethyl) acrylate. As the (meth) acrylic acid monomer B, a monomer having a vinyl group and an ester group or a carboxyl group is preferable. For example, (meth) acrylic acid, alkyl (meth) acrylate (for example, methyl (meth) acrylate, (Meth) ethyl acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, cyclohexyl (meth) acrylate, preferably methyl methacrylate), (meth) Aryl acrylate (eg phenyl (meth) acrylate, benzyl (meth) acrylate), 2- (hydroxyalkyl) alkyl acrylate (eg methyl 2- (hydroxymethyl) acrylate, 2- (hydroxymethyl) Ethyl acrylate, 2- (hydroxymethyl) isopropyl acrylate, -2- (hydroxyethyl) such as n-butyl (hydroxymethyl) acrylate, 2- (hydroxymethyl) alkyl acrylate such as t-butyl 2- (hydroxymethyl) acrylate, and 2- (hydroxyethyl) methyl acrylate ) Alkyl acrylate, etc.).
More specifically, the (meth) acrylic resin having a lactone ring structure in the main chain is obtained by the method described in, for example, JP-A-2006-96960, JP-A-2006-171464, or JP-A-2007-63541. Can be manufactured.

  When the (meth) acrylic resin has a lactone ring structure in the main chain, the content of the lactone ring structure in the resin is not particularly limited, but is preferably, for example, 5 to 90% by mass, and more preferably 10 -80 mass%, More preferably, it is 10-70 mass%, Most preferably, it is 20-60 mass%. If the content of the lactone ring structure is too low, it is difficult to obtain the effect of introducing the ring structure (improvement effects such as solvent resistance and surface hardness in addition to the heat resistance of the film), while if too high, the moldability of the film In addition, the mechanical properties may be deteriorated.

In addition, the content rate of the lactone ring structure in the (meth) acrylic resin is that of the monomers involved in the lactone cyclization (the (meth) acrylic acid monomer A and the (meth) acrylic acid monomer B having a hydroxy group). It can be determined from the copolymerization amount and the lactone cyclization rate. That is, assuming that the lactone cyclization reaction was performed by the amount of the lactone cyclization rate, the content of the following formula lactone ring structure (mass%) = Z ₁ × Z ₂ × M _R / M _m
(Wherein Z ₁ is a raw material monomer involved in lactone cyclization in the polymer before lactone cyclization ((meth) acrylic acid monomer A and (meth) acrylic acid monomer B having a hydroxy group)) the mass content of the structural unit derived from the formula weight of the lactone ring structural units M _R of generating (specifically, a lactone ring-forming elements, the total formula weight of groups other than the main chain which binds to the lactone ring) M _m is the molecular weight (total) of raw material monomers (hydroxy group-containing (meth) acrylic acid monomer A and (meth) acrylic acid monomer B) involved in lactone cyclization, and Z ₂ is Lactone cyclization rate)
Can be calculated.

The lactone cyclization rate is based on, for example, the weight loss that occurs when all hydroxy groups are dealcoholated or dehydrated as alcohol or water from the polymer composition obtained by polymerization, and weight loss starts in dynamic TG measurement. It can be determined from the weight loss due to the dealcoholization reaction from the previous 150 ° C. to 300 ° C. before the polymer starts to decompose. That is, in the dynamic TG measurement of the polymer having a lactone ring structure, the weight reduction rate between 150 ° C. and 300 ° C. is measured, and the obtained actual weight reduction rate is defined as (X). On the other hand, from the composition of the polymer, the theoretical weight loss rate when assuming that all the hydroxyl groups contained in the polymer composition are dealcoholized or dehydrated because they are involved in the formation of the lactone ring (that is, 100% on the composition) The weight reduction rate calculated on the assumption that dealcoholization or dehydration has occurred is defined as (Y). The theoretical weight reduction rate (Y) is more specifically the molar ratio of raw material monomers having a structure (hydroxy group) involved in dealcoholization or dehydration reaction in the polymer, that is, in the polymer composition. It can be calculated from the content of the raw material monomer. These values (X, Y) are expressed by the formula: 1- (actual weight reduction rate (X) / theoretical weight reduction rate (Y))
Substituting into, the value is obtained and expressed in%, and the lactone cyclization rate (dealcoholization or dehydration rate) is obtained.

As the glutaric anhydride structure or the glutarimide structure, for example, a structure represented by the following general formula (2) (in the following general formula (2), when X ¹ is an oxygen atom, a glutaric anhydride structure is obtained, When X ¹ is a nitrogen atom, a glutarimide structure is preferred.

In the general formula (2), R ⁴ and R ⁵ are each independently a hydrogen atom or a methyl group, and X ¹ is an oxygen atom or a nitrogen atom. When X ¹ is an oxygen atom, R ⁶ is not present, and when X ¹ is a nitrogen atom, R ⁶ is a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms (methyl group, ethyl group, propyl group) Butyl group, pentyl group, hexyl group), cyclopentyl group, cyclohexyl group or phenyl group.

The glutaric anhydride structure in which X ¹ in the general formula (2) is an oxygen atom is obtained by, for example, subjecting a copolymer of (meth) acrylic ester and (meth) acrylic acid to dealcoholization cyclocondensation in the molecule. Can be formed.
The glutarimide structure in which X ¹ in the general formula (2) is a nitrogen atom can be formed, for example, by imidizing a (meth) acrylic acid ester polymer with an imidizing agent such as methylamine.
More specifically, a (meth) acrylic resin having a glutaric anhydride structure or a glutarimide structure in the main chain can be produced, for example, by the method described in WO2007 / 26659 and WO2005 / 108438.

  When the (meth) acrylic resin has a glutaric anhydride structure or a glutarimide structure in the main chain, the content of the glutaric anhydride structure or the glutarimide structure in the resin is not particularly limited, but for example, 5 to 90% by mass More preferably, it is 10-70 mass%, More preferably, it is 10-60 mass%, Most preferably, it is 20-50 mass%. If the content of the glutaric anhydride structure or glutarimide structure is too low, it is difficult to obtain the effect of introducing a ring structure into the main chain. On the other hand, if it is too high, the moldability and mechanical properties of the film may be reduced. .

  In addition, the content rate of the glutaric anhydride structure and glutarimide structure in (meth) acrylic-type resin can be calculated | required by the method as described in Unexamined-Japanese-Patent No. 2006-131589, for example.

As the maleic anhydride structure or the N-substituted maleimide structure, for example, a structure represented by the following general formula (3) (in the general formula (3) below, when X ² is an oxygen atom, a maleic anhydride structure) And when X ² is a nitrogen atom, an N-substituted maleimide structure is preferred.

In the general formula (3), R ⁷ and R ⁸ are each independently a hydrogen atom or a methyl group, and X ² is an oxygen atom or a nitrogen atom. When X ² is an oxygen atom, R ⁹ is not present, and when X ² is a nitrogen atom, R ⁹ is a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms (methyl group, ethyl group, propyl group) Butyl group, pentyl group, hexyl group), cyclopentyl group, cyclohexyl group, benzyl group or phenyl group.

The maleic anhydride structure in which X ² in the general formula (3) is an oxygen atom can be formed, for example, by subjecting maleic anhydride to polymerization together with a (meth) acrylic acid ester or the like.
The N-substituted maleimide structure in which X ² in the general formula (3) is a nitrogen atom can be formed, for example, by subjecting an N-substituted maleimide such as phenylmaleimide to polymerization together with a (meth) acrylic ester or the like.
More specifically, a (meth) acrylic resin having a maleic anhydride structure or an N-substituted maleimide structure in the main chain can be obtained, for example, by the method described in JP-A-57-153008 and JP-A-2007-31537. Can be manufactured.

  When the (meth) acrylic resin has a maleic anhydride structure or an N-substituted maleimide structure in the main chain, the content of the maleic anhydride structure or the N-substituted maleimide structure in the resin is not particularly limited. It is preferable that it is -90 mass%, More preferably, it is 10-70 mass%, More preferably, it is 10-60 mass%, Most preferably, it is 20-50 mass%. If the content of the maleic anhydride structure or N-substituted maleimide structure is too low, it is difficult to obtain the effect of introducing a ring structure into the main chain. On the other hand, if the content is too high, the moldability and mechanical properties of the film may be reduced. There is.

  The content of the maleic anhydride structure or N-substituted maleimide structure in the (meth) acrylic resin can be determined from the copolymerization amount of maleic anhydride or N-substituted maleimide.

  The (meth) acrylic resin (A) is preferably (i) further having a ring structure in the side chain, or (ii) forming a polymer alloy with a resin having a ring structure in the side chain. . Due to the ring structure of the side chain, the intrinsic birefringence of the resin composition can be shifted to the negative side, and the degree of freedom in controlling the birefringence of the formed film is increased.

  When a ring structure is introduced into the side chain of the (meth) acrylic resin (A) (in the case of (i) above), for example, a vinyl monomer having a ring structure (for example, styrene, vinyl toluene, α-methylstyrene) , Α-hydroxymethylstyrene, α-hydroxyethylstyrene, N-vinylpyrrolidone, N-vinylcarbazole, etc.) may be copolymerized with a (meth) acrylic acid monomer.

  When the (meth) acrylic resin (A) constitutes a polymer alloy with a resin having a ring structure in the side chain (in the case of (ii) above), for example, it comprises a vinyl monomer having the ring structure described above. What is necessary is just to mix resin with (meth) acrylic-type resin (A).

  The ring introduced into the side chain is preferably a heteroaromatic ring. When a heteroaromatic ring is introduced into the side chain and a ring structure is introduced into the main chain, a film exhibiting reverse wavelength dispersion with positive intrinsic birefringence (phase difference) can be easily formed. In order to make the side chain ring a heteroaromatic ring, N-vinylcarbazole or the like may be used as the vinyl monomer having the ring structure described above.

  The (meth) acrylic resin (A) may have ultraviolet absorbing ability as long as the heat resistance, physical properties, and optical properties are not impaired. In order to impart ultraviolet absorbing ability, specifically, a method using an ultraviolet absorbing monomer and / or an ultraviolet stable monomer as a monomer component when producing the (meth) acrylic resin (A). In addition, there is a method of blending a (meth) acrylic resin (A) with an ultraviolet absorber and / or an ultraviolet stabilizer. Moreover, as long as there is no trouble in the retardation film containing the (meth) acrylic resin (A), these methods may be used in combination. Further, in order to maintain the ultraviolet absorbing ability, it is preferable to use an ultraviolet absorbing monomer and an ultraviolet stabilizing monomer in combination or an ultraviolet absorber and an ultraviolet stabilizer in combination. It is also preferable to use an ultraviolet absorber and / or an ultraviolet stabilizer in combination with the ultraviolet absorbing monomer and / or the ultraviolet stable monomer. These may be used alone or in combination of two or more.

Examples of the ultraviolet absorbing monomer include those in which a polymerizable unsaturated group is bonded to a benzotriazole compound, a benzophenone compound, or a triazine compound.
Examples of the benzotriazole compounds include 2- [2′-hydroxy-5 ′-(meth) acryloyloxymethylphenyl] -2H-benzotriazole, 2- [2′-hydroxy-5 ′-(meth) acryloyloxy. Ethylphenyl] -2H-benzotriazole, 2- [2′-hydroxy-5 ′-(meth) acryloyloxypropylphenyl] -2H-benzotriazole, 2- [2′-hydroxy-5 ′-(meth) acryloyloxy Hexylphenyl] -2H-benzotriazole, 2- [2′-hydroxy-3′-tert-butyl-5 ′-(meth) acryloyloxyethylphenyl] -2H-benzotriazole, 2- [2′-hydroxy-5 '-(Β- (Meth) acryloyloxyethoxy) -3'-tert-butylphenyl] -5-t ert-butyl-2H-benzotriazole, 2- [2′-hydroxy-3′-methacrylaminomethyl-5 ′-(1 ″, 1 ″, 3 ″, 3 ″ -tetramethyl) butylphenyl] -2H-benzo Triazole or the like can be used.
Examples of the benzophenone compounds include 2-hydroxy-4- [2- (meth) acryloyloxy] ethoxybenzophenone, 2-hydroxy-4- [2- (meth) acryloyloxy] butoxybenzophenone, and 2,2′-dihydroxy. -4- [2- (meth) acryloyloxy] ethoxybenzophenone, 2-hydroxy-4- [2- (meth) acryloyloxy] ethoxy-4 ′-(2-hydroxyethoxy) benzophenone, and the like can be used.
Examples of the triazine compound include 4-diphenyl-6- [2-hydroxy-4- (2-acryloyloxyethoxy)]-s-triazine, 2,4-bis (2-methylphenyl) -6- [2 -Hydroxy-4- (2-acryloyloxyethoxy)]-s-triazine, 2,4-bis (2-methoxyphenyl) -6- [2-hydroxy-4- (2-acryloyloxyethoxy)]-s- Triazine or the like can be used.
When using an ultraviolet-absorbing monomer, the content thereof is preferably 0.1 to 25% by mass, more preferably 1 in the total monomer components constituting the (meth) acrylic resin (A). ˜15 mass%. If the content is small, the contribution of improving weather resistance is low, and if the content is too large, the hot water resistance and solvent resistance may be lowered or yellowing may be caused.

As the UV-stable monomer, a monomer in which a polymerizable unsaturated group is bonded to a hindered amine compound can be used.
Examples of hindered amine compounds include 4- (meth) acryloyloxy-2,2,6,6-tetramethylpiperidine, 4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 4- (meta ) Acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4- (meth) acryloylamino-1,2,2,6,6-pentamethylpiperidine, 4-cyano-4- (meth) acryloyl Amino-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, 4-crotonoylamino-2,2,6,6-tetramethylpiperidine, 1- (meth) acryloyl-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 1- (meth) acryloyl- - cyano-4- (meth) acryloyl amino-2,2,6,6-tetramethylpiperidine, 1-crotonoyl-4-crotonoyloxy-2,2,6,6-tetramethylpiperidine and the like.
In the case of using an ultraviolet stable monomer, the content thereof is preferably 0.1 to 25% by mass, more preferably 1 in the total monomer components constituting the (meth) acrylic resin (A). ˜15 mass%. If the content is small, the contribution of improving weather resistance is low, and if the content is too large, the hot water resistance and solvent resistance may be lowered or yellowing may be caused.

Examples of ultraviolet absorbers include benzophenone compounds, salicinate compounds, benzoate compounds, triazole compounds, and triazine compounds.
Examples of the benzophenone compounds include 2,4-dihydroxybenzophenone, 4-n-octyloxy-2-hydroxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, 2-hydroxy-4-n-octyloxy. Examples include benzophenone, bis (5-benzoyl-4-hydroxy-2-methoxyphenyl) methane, 1,4-bis (4-benzoyl-3-hydroxyphenone) -butane and the like.
Examples of the silicate compound include pt-butylphenyl silicate.
Examples of the benzoate compound include 2,4-di-t-butylphenyl-3 ′, 5′-di-t-butyl-4′-hydroxybenzoate.
Examples of triazole compounds include 2,2′-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol], 2- (3,5 -Di-tert-butyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (2H-benzotriazol-2-yl) -p-cresol, 2- (2H-benzotriazol-2-yl) -4 , 6-Bis (1-methyl-1-phenylethyl) phenol, 2-benzotriazol-2-yl-4,6-di-tert-butylphenol, 2- [5-chloro (2H) -benzotriazole-2- Yl] -4-methyl-6-t-butylphenol, 2- (2H-benzotriazol-2-yl) -4,6-di-t-butylphenol, 2- (2H- Benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol, 2- (2H-benzotriazol-2-yl) -4-methyl-6- (3,4,5 , 6-Tetrahydrophthalimidylmethyl) phenol, methyl 3- (3- (2H-benzotriazol-2-yl) -5-tert-butyl-4-hydroxyphenyl) propionate / polyethylene glycol 300 reaction product, 2 -(2H-benzotriazol-2-yl) -6- (linear and side chain dodecyl) -4-methylphenol, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy- 3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 3- (2H-benzotriazol-2-yl) -5 -(1,1-dimethylethyl) -4-hydroxy-C7-9 side chain and linear alkyl esters.
Examples of triazine compounds include 2-mono (hydroxyphenyl) -1,3,5-triazine compounds, 2,4-bis (hydroxyphenyl) -1,3,5-triazine compounds, 2,4,6-tris ( Hydroxyphenyl) -1,3,5-triazine compounds, specifically 2,4-diphenyl-6- (2-hydroxy-4-methoxyphenyl) -1,3,5-triazine, 2, 4-diphenyl-6- (2-hydroxy-4-ethoxyphenyl) -1,3,5-triazine, 2,4-diphenyl- (2-hydroxy-4-propoxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-butoxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-hexyloxy) Phenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-octyloxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2- Hydroxy-4-dodecyloxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-benzyloxyphenyl) -1,3,5-triazine, 2,4-diphenyl -6- (2-hydroxy-4-butoxyethoxy) -1,3,5-triazine, 2,4-bis (2-hydroxy-4-butoxyphenyl) -6- (2,4-dibutoxyphenyl)- 1,3-5-triazine, 2,4,6-tris (2-hydroxy-4-methoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4-ethoxyphene) ) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4-propoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4) -Butoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4-hexyloxyphenyl) -1,3,5-triazine, 2,4,6-tris (2- Hydroxy-4-octyloxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4-dodecyloxyphenyl) -1,3,5-triazine, 2,4,6- Tris (2-hydroxy-4-benzyloxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4-ethoxyethoxyphenyl) -1,3,5-triazine, 2, 4,6-G Lis (2-hydroxy-4-butoxyethoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4-propoxyethoxyphenyl) -1,3,5-triazine, 2, 4,6-tris (2-hydroxy-4-methoxycarbonylpropyloxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4-ethoxycarbonylethyloxyphenyl) -1, 3,5-triazine, 2,4,6-tris (2-hydroxy-4- (1- (2-ethoxyhexyloxy) -1-oxopropan-2-yloxy) phenyl) -1,3,5-triazine 2,4,6-tris (2-hydroxy-3-methyl-4-methoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy 3-methyl-4-ethoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-propoxyphenyl) -1,3,5-triazine, 2, 4,6-tris (2-hydroxy-3-methyl-4-butoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-butoxyphenyl)- 1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-hexyloxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy) -3-methyl-4-octyloxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-dodecyloxyphenyl) -1,3,5-triazine , 2, 4, -Tris (2-hydroxy-3-methyl-4-benzyloxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-ethoxyethoxyphenyl) -1 , 3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-butoxyethoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy- 3-methyl-4-propoxyethoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-methoxycarbonylpropyloxyphenyl) -1,3,5- Triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-ethoxycarbonylethyloxyphenyl) -1,3,5-triazine, 2,4,6-tris (2 -Hydroxy-3-methyl-4- (1- (2-ethoxyhexyloxy) -1-oxopropan-2-yloxy) phenyl) -1,3,5-triazine and the like. Among these, 2,4-bis (2,4-dimethylphenyl) -6- [2-hydroxy-4-] has high compatibility with the (meth) acrylic resin (A) and excellent absorption characteristics. Preferred are UV absorbers having (3-alkyloxy-2-hydroxypropyloxy) -5-α-cumylphenyl] -s-triazine skeleton (alkyloxy; long-chain alkyloxy groups such as octyloxy, nonyloxy, decyloxy). It is done. An ultraviolet absorber having a 2,4,6-tris (hydroxyphenyl) -1,3,5-triazine skeleton is also preferably used, and 2,4,6-tris (2-hydroxy-4-long chain alkyloxy) Group-substituted phenyl) -1,3,5-triazine skeleton and 2,4,6-tris (2-hydroxy-3-alkyl-4-long-chain alkyloxy group-substituted phenyl) -1,3,5-triazine skeleton The ultraviolet absorber having is particularly preferable. Examples of commercially available products include “TINUVIN 1577”, “TINUVIN 460” and “TINUVIN 477” manufactured by BASF Japan as triazine UV absorbers, and “ADEKA STAB LA-31” manufactured by ADEKA as triazole UV absorbers. Can be mentioned.

  When using an ultraviolet absorber, the content is preferably 0.01 to 25% by mass, more preferably 0.05 to 10% by mass, in the finally obtained film. If the content is small, the contribution to improving the weather resistance is low, and if the content is too large, the mechanical strength may be lowered or yellowing may be caused.

Examples of the ultraviolet stabilizer include hindered amine compounds exemplified as the ultraviolet stable monomer.
When using an ultraviolet stabilizer, the content thereof is preferably 0.01 to 25% by mass, and more preferably 0.05 to 10% by mass in the finally obtained film. If the content is small, the contribution to improving the weather resistance is low, and if the content is too large, the mechanical strength may be lowered or yellowing may be caused.

The (meth) acrylic resin (A) may form a polymer alloy with other resins as long as the effects of the present invention are not impaired. In that case, the content of other resins is preferably 0 to 50% by mass, more preferably 0 to 25% by mass, and still more preferably 0 to 10% by mass.
Examples of other resins include olefin polymers such as polyethylene, polypropylene, ethylene-propylene copolymer, and poly (4-methyl-1-pentene); halogen-containing polymers such as vinyl chloride and chlorinated vinyl resins; polystyrene Styrene polymers such as styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene block copolymer; polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate; polylactic acid, poly Biodegradable polyester such as butylene succinate; polyamide such as nylon 6, nylon 66, nylon 610; polyacetal: polycarbonate; cellulose triacetate, cellulose acetate Cellulose polymers such as pionate and cellulose acetate butyrate; polyphenylene oxide; polyphenylene sulfide: polyether ether ketone; polyether nitrile; polysulfone; polyether sulfone: polyoxybenzylene; polyamideimide; And rubber polymers such as ABS resin and ASA resin. From the viewpoint of compatibility, a styrene-acrylonitrile copolymer is preferable. Moreover, it is preferable that a rubber-like polymer has a graft part of the composition compatible with (meth) acrylic-type resin (A) on the surface.

  The glass transition temperature (Tg) of the (meth) acrylic resin (A) is preferably 110 ° C. or higher, more preferably 115 ° C. or higher, further preferably 120 ° C. or higher, and particularly preferably 130 ° C. or higher. If the Tg of the (meth) acrylic resin (A) is within this range, the Tg as the resin composition can be increased, and the Tg of the retardation film is also increased. The rate can be reduced. However, if the Tg of the (meth) acrylic resin (A) is too high, the molding process such as film molding or stretching may be difficult, so the Tg of the (meth) acrylic resin (A) is 220. C. or lower is preferable, more preferably 200 ° C. or lower, and still more preferably 180 ° C. or lower. Note that Tg of polymethyl methacrylate (PMMA) which is a typical acrylic resin is 105 ° C. The (meth) acrylic resin (A) is preferably amorphous.

  The weight average molecular weight of the (meth) acrylic resin (A) is preferably, for example, in the range of 1,000 to 300,000, more preferably 5,000 to 250,000, and still more preferably 10,000 to 200,000. Especially preferably, it is 50,000-200,000.

[Elastic organic fine particles (B)]
The elastic organic fine particles (B) in the present invention have, as an essential component, a conjugated diene monomer structural unit (hereinafter also referred to as “conjugated diene structural unit”) constructed by polymerizing a conjugated diene monomer. And as long as it is a volume average particle diameter of 0.350 micrometer or less, it does not specifically limit. By containing such elastic organic fine particles (B), the retardation film of the present invention formed of the resin composition (C) has good flexibility. One type of elastic organic fine particles (B) may be contained in the resin composition (C), or two or more types may be contained.

  Examples of the conjugated diene monomer constituting the conjugated diene structural unit include 1,3-butadiene (hereinafter sometimes simply referred to as “butadiene”), isoprene, 1,3-pentadiene, and 2,3-dimethyl-1. , 3-butadiene, 2-chloro-1,3-butadiene, myrcene, and the like. Among these, butadiene and isoprene are preferable. Only one type of conjugated diene monomer may be used, or two or more types may be used.

  In the elastic organic fine particles (B), the conjugated diene structural unit is preferably present in the soft polymer layer. The soft polymer layer has a glass transition temperature of a polymer obtained by polymerizing the monomer composition constituting the layer (hereinafter sometimes referred to as “glass transition temperature of the soft polymer layer”). It is a part (usually a layered part) that becomes less than ° C. A soft polymer layer contains a conjugated diene structural unit normally 50 mass% or more, Preferably it is 70 mass% or more, More preferably, it contains 90 mass% or more.

  The glass transition temperature of the soft polymer layer is more preferably −140 ° C. to −40 ° C., further preferably −130 ° C. to −55 ° C., and particularly preferably −125 ° C. to −70 ° C. When the glass transition temperature of the soft polymer layer is −40 ° C. or lower, the flexibility can be improved by adding a small amount of elastic organic fine particles (B).

The glass transition temperature of the soft polymer layer is calculated according to the following FOX formula for determining the glass transition temperature of the polymer (where wi is the mass ratio of monomer i and Tgi is the monomer i alone). It is the glass transition temperature (° C.) of the polymer).
1 / (Tg + 273) = Σ [wi / (Tgi + 273)]
The Tg of the homopolymer of the monomer used for the FOX formula is, for example, “POLYMER HANDBOOK THIRD EDITION” (J. BRANDRUUP, EH IMMERGUT, 1989, John Wiley & Sons, Inc., page: VI / 209 to VI / 277) (the lowest value when a plurality of glass transition temperatures are described) may be employed. For monomers not described in “POLYMER HANDBOOK THIRD EDITION”, commercially available glass transition temperature calculation software (for example, “MATERIALS STUDIO”, version: 4.0.0.0, manufactured by Accelrys Software Inc., module: : Synthia, conditions: calculated with a polymerization average molecular weight of 100,000), and a value obtained by a computer can be used. If it cannot be calculated using the software, the monomer is removed from the monomer composition, and the glass transition temperature of the soft polymer layer is determined. The glass transition temperature of typical monomers is as follows.

1,3-butadiene: -109 ° C
Isoprene (2-methyl-1,3-butadiene): -73 ° C
Chloroprene (2-chloro-1,3-butadiene): -40 ° C

The soft polymer layer can be formed by polymerizing a monomer composition containing the conjugated diene monomer described above and, if necessary, a component (monomer) other than the conjugated diene monomer. .
As the components other than the conjugated diene monomer, those having a glass transition temperature on the low temperature side of the obtained soft polymer layer of −40 ° C. or less are preferably used. Examples of such other components include silicone components such as dimethylsiloxane and phenylmethylsiloxane; styrene components such as styrene and α-methylstyrene; nitrile components such as acrylonitrile and methacrylonitrile; urethane components; ethylene components; Component; isobutene component; alkyl acid ester component such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, benzyl acrylate, and the like. These other components may use only 1 type and may use 2 or more types together.

  Moreover, as a component other than the conjugated diene monomer, a polyfunctional crosslinkable monomer or a polyfunctional graft monomer can be used. Examples of the polyfunctional crosslinkable monomer or polyfunctional graft monomer include ethylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, divinylbenzene, Examples include allyl (meth) acrylate, allyl maleate, allyl fumarate, diallyl fumarate, triallyl cyanurate, and the like. These polyfunctional crosslinking monomers or polyfunctional graft monomers may be used alone or in combination of two or more.

  When the monomer composition forming the soft polymer layer contains a component (monomer) other than the conjugated diene monomer, the content of the conjugated diene monomer in the total amount of the monomer composition is The content ratio is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 90% by mass or more.

  The elastic organic fine particles (B) preferably have a portion other than the soft polymer layer having a glass transition temperature of 20 ° C. or higher together with the soft polymer layer. Thereby, the dispersibility of the elastic organic fine particles (B) in the (meth) acrylic resin (A) is improved, so that the transparency of the film is improved and the elastic organic fine particles (B) are aggregated. Since by-products of foreign matter can be further suppressed, productivity can be improved, for example, the filtration process during film formation can be performed in a short time. However, in this case, the proportion of the soft polymer layer in the elastic organic fine particles (B) is preferably 20 to 80% by mass, more preferably 30 to 70% by mass, and further preferably 40 to 60% by mass. .

  The portion of the elastic organic fine particles (B) other than the soft polymer layer (the portion having a glass transition temperature of 20 ° C. or higher) is not particularly limited, but is a monomer composition containing acrylonitrile (AN) and styrene (St). The (meth) acrylic resin (A) is a structure constructed by polymerizing a monomer composition or a structure constructed by polymerizing a monomer composition mainly composed of a methacrylic acid ester such as methyl methacrylate. It is preferable at the point which can improve compatibility in. In particular, when the (meth) acrylic resin (A) has a ring structure in the main chain, a structure constructed by polymerizing a monomer composition containing at least acrylonitrile and styrene is preferable.

  The elastic organic fine particles (B) preferably have a multilayer structure, and more specifically, particles having a so-called core-shell structure having a core part and a shell part are more preferable. The multilayer structure may have any number of layers, but two or three layers are preferable in terms of ease of synthesis.

  In particular, the elastic organic fine particles (B) preferably have a core-shell structure including a core portion and a shell portion having a structure having the conjugated diene structural unit as an essential component, and further, an elastic structure having a core-shell structure. The organic fine particles (B) have a structure (preferably a soft polymer layer) having a conjugated diene structural unit as an essential component in the central part (core), and (meta) in the part (shell) surrounding the central part. It is preferable to have a structure having high compatibility with the acrylic resin (A). When the shell part has two or more layers, it is preferable that the outermost layer has a structure with high compatibility with the (meth) acrylic resin (A). Accordingly, the dispersibility of the elastic organic fine particles (B) in the (meth) acrylic resin (A) is improved, so that the transparency of the film is improved and the elastic organic fine particles (B) are aggregated. Since by-products of foreign matter can be further suppressed, productivity can be improved, for example, the filtration process during film formation can be performed in a short time.

  As a structure having high compatibility with the (meth) acrylic resin (A), for example, when the (meth) acrylic resin (A) has a ring structure in the main chain, 2- (hydroxymethyl) acrylic A structure constructed by polymerizing a monomer composition composed of methyl acrylate (MHMA) and methyl methacrylate (MMA) (hereinafter referred to as MHMA / MMA structure), composed of cyclohexyl methacrylate (CHMA) and MMA A structure constructed by polymerizing a monomer composition (hereinafter referred to as C HMA / MMA structure), a structure constructed by polymerizing a monomer composition composed of benzyl methacrylate (BzMA) and MMA ( Hereinafter, a structure (hereinafter referred to as HEM) constructed by polymerizing a monomer composition composed of 2-hydroxyethyl methacrylate (HEMA) and MMA. / Referred to as MMA structure), acrylonitrile (AN) and styrene (St) and consisting of the monomer composition polymerized are constructed structure (hereinafter referred to as AN / St structure), and the like. Among these, in particular, the CHMA / MMA structure is difficult to reduce the positive birefringence (positive phase difference) expressed by introducing a ring structure into the main chain of the (meth) acrylic resin (A). , BzMA / MMA structure and MHMA / MMA structure are preferable, and more preferably, after forming MHMA / MMA structure, a part or all of the structure is lactone cyclized.

  When the structure having high compatibility with the (meth) acrylic resin (A) is an MHMA / MMA structure, the ratio of MHMA to MMA is preferably 5:95 to 50:50, preferably 10 : 90-40: 60 is more preferable. In the case of a CHMA / MMA structure, the mass ratio of CHMA and MMA is preferably 5:95 to 50:50, more preferably 10:90 to 40:60. In the case of a BzMA / MMA structure, the ratio of BzMA and MMA is preferably 10:90 to 60:40, more preferably 20:80 to 50:50, in terms of mass ratio. In the case of the HEMA / MMA structure, the mass ratio of HEMA and MMA is preferably 2:98 to 50:50, and more preferably 5:95 to 40:60. In the case of the AN / St structure, the mass ratio of AN to St is preferably 5:95 to 50:50, and more preferably 10:90 to 40:60. When the proportion of each structure is within the above range, the compatibility in the (meth) acrylic resin (A) is further increased, and the elastic organic fine particles (B) are uniformly dispersed in the (meth) acrylic resin (A). Can be made.

  When the elastic organic fine particles (B) have a core-shell structure, the ratio of the core part to the shell part is preferably a mass ratio of 20:80 to 80:20, and 40:60 to 60:40. Is more preferable. When the core part is less than 20% by mass, the bending resistance of the film formed from the obtained elastic organic fine particles (B) tends to deteriorate, whereas when it exceeds 80% by mass, the hardness and formability of the film. Tends to decrease. The shell portion of the elastic organic fine particles (B) may have a crosslinked structure, but more preferably does not have a crosslinked structure.

  The production method of the elastic organic fine particles (B) is not particularly limited. For example, the above-described simple organic polymer fine particles (B) may be produced by the conventionally known emulsion polymerization method, emulsion-suspension polymerization method, suspension polymerization method, bulk polymerization method or solution polymerization method. A method of polymerizing the monomer composition in one stage or multiple stages can be employed. Among these, the emulsion polymerization method is more preferable.

  In the case of producing elastic organic fine particles (B) having a core / shell structure, for example, the constituent components of the soft polymer layer are first polymerized, and the reactive functionalities remaining without reacting during the polymerization of the soft polymer layer. It can be obtained by graft polymerization of a component (monomer composition) that forms a structure other than the soft polymer layer using a group (double bond) as a graft crossing point.

  When the elastic organic fine particles (B) are polymerized, conventionally known initiators such as organic peroxides, inorganic peroxides, and azo compounds can be used as polymerization initiators. Specifically, for example, t-butyl hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, succinic acid peroxide, peroxymaleic acid-t-butyl ester, cumene hydroperoxide, benzoyl Organic peroxides such as peroxides, inorganic peroxides such as potassium persulfate and sodium persulfate, 2,2′-azobis (2-methylpropionamidine) dihydrochloride, 2,2′-azobisisobuty 1 type, or 2 or more types, such as azo compounds, such as a ronitrile, are mentioned. These polymerization initiators include reducing agents such as sodium sulfite, sodium thiosulfate, sodium formaldehyde sulfoxylate, ascorbic acid, hydroxyacetone acid, ferrous sulfate, ferrous sulfate and a complex of ethylenediaminetetraacetic acid disodium. It may be used as a normal redox initiator in combination with In particular, the organic peroxide can be added by a known addition method such as a method of adding it to the polymerization system as it is, a method of adding it mixed with a monomer, a method of adding it dispersed in an emulsifier aqueous solution, etc. From this point, it is preferable to use it by a method of adding it by mixing with a monomer or a method of adding it by dispersing in an aqueous emulsifier solution. Organic peroxides are inorganic reducing agents (divalent iron salts, etc.) and / or organic reducing agents (formaldehyde sulfoxylate sodium, reducing sugar, ascorbine from the viewpoint of polymerization stability and particle size control. It is preferably used as a redox initiator in combination with an acid or the like.

  When the elastic organic fine particles (B) are produced by emulsion polymerization, a conventionally known surfactant for emulsion polymerization can be used. Specifically, for example, anionic surfactants such as sodium alkyl sulfonate, sodium alkyl benzene sulfonate, sodium dioctyl sulfosuccinate, sodium lauryl sulfate, sodium fatty acid, etc .; alkylphenols, aliphatic alcohols and propylene oxide, Preferred examples include nonionic surfactants such as reaction products with ethylene oxide. Furthermore, you may use cationic surfactants, such as an alkylamine salt, as needed. These surfactants may be used alone or in combination of two or more.

  The latex of the elastic organic fine particles (B) generated by the polymerization reaction is separated and recovered by a known isolation operation such as coagulation, washing, drying (in addition to normal heat drying, spray drying, freeze drying, etc.). be able to. For example, when producing the elastic organic fine particles (B) by emulsion polymerization, the elastic organic fine particles (B) are aggregated by salting out or reprecipitating the polymer solution after the emulsion polymerization, followed by filtration, washing, and drying. do it.

  The volume average particle diameter of the elastic organic fine particles (B) is 0.350 μm or less, preferably 0.010 to 0.350 μm, more preferably 0.050 to 0.300 μm. When the particle diameter of the elastic organic fine particles (B) exceeds 0.350 μm, the transparency of the film formed from the resin composition (C) becomes insufficient, or the filter is elastic organic in the filtration process during film production. There is a tendency that the fine particles (B) are easily clogged. On the other hand, when the particle diameter of the elastic organic fine particles (B) is too small, the flexibility of the film formed from the obtained resin composition is lowered. The particle diameter of the elastic organic fine particles (B) can be measured using, for example, a commercially available particle size distribution measuring apparatus (for example, “Submicron Particle Sizer NICOM 380” manufactured by NICOMP).

[Resin composition (C)]
The resin composition (C) in the present invention contains the (meth) acrylic resin (A) and the elastic organic fine particles (B).

  The content ratio of the (meth) acrylic resin (A) in the resin composition (C) is preferably 50 to 95% by mass, more preferably 60% by mass or more, and further preferably 70% by mass or more. More preferably, it is 90 mass% or less, More preferably, it is 85 mass% or less.

  The content of the elastic organic fine particles (B) in the resin composition (C) is preferably 5 to 50% by mass, more preferably 10% by mass or more, still more preferably 15% by mass or more, and more preferably It is 40 mass% or less, More preferably, it is 30 mass% or less. If the content ratio of the elastic organic fine particles (B) is less than 5% by mass, desired flexibility may not be obtained. On the other hand, when the content of the elastic organic fine particles (B) exceeds 50% by mass, the transparency may decrease due to aggregation of the elastic organic fine particles, or foreign substances may be generated as a by-product.

  The resin composition (C) is preferably a resin composition having a positive intrinsic birefringence. The means for developing positive intrinsic birefringence is not particularly limited. For example, by introducing a ring structure into the main chain of (meth) acrylic resin (A), positive intrinsic birefringence may be exhibited, and elasticity Positive intrinsic birefringence may be expressed by the organic fine particles (B).

  As a method for producing the resin composition (C), for example, each component constituting the resin composition (C) is pre-blended with a mixer such as an omni mixer, and then the obtained mixture is extruded and kneaded from a kneader. Etc. can be adopted. Here, the kneader used for extrusion kneading is not particularly limited, and for example, a known kneader such as a single-screw extruder, a twin-screw extruder, or a pressure kneader can be used.

  Moreover, it is not necessary to mix each component mentioned above which comprises a resin composition, after isolating. For example, after the elastic organic fine particles (B) obtained by emulsion polymerization are washed and not dried, the resulting elastic organic fine particles (B) cake is redispersed in an organic solvent (for example, methyl isobutyl ketone), The (meth) acrylic resin (A) is dissolved in the redispersed liquid, or the redispersed liquid and the (meth) acrylic resin (A) solution ((meth) acrylic resin (A) are dissolved in an organic solvent. And a method of devolatilizing water and / or an organic solvent, and the like.

  Resin composition (C) comprises (meth) acrylic resin (A) and elastic organic fine particles (B), as well as an anti-oxidant, an anti-ozone anti-oxidant or an anti-aging agent (particularly preferably an anti-oxidant). ), And more preferably an antioxidant. By containing a deterioration inhibitor (particularly an antioxidant), deterioration of the resin composition (C) can be prevented, and the stability of optical properties as a retardation film can be improved. In particular, the change in phase difference under a high-temperature environment can be reduced, and specifically, the Re change rate before and after a thermal acceleration test (to be described later) (particularly, the change rate for 200 hours) can be controlled within the above-described range. As a result, excellent optical performance can be maintained for a long time when an image display device is provided.

As the antioxidant, for example, a known antioxidant such as a phenol-based antioxidant, a phosphorus-based antioxidant, and a sulfur-based (thioether-based) antioxidant can be used.
Examples of phenolic antioxidants include n-octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, n-octadecyl-3- (3,5-di-t-butyl). -4-hydroxyphenyl) acetate, n-octadecyl-3,5-di-t-butyl-4-hydroxybenzoate, n-hexyl-3,5-di-t-butyl-4-hydroxyphenylbenzoate, n-dodecyl 3,5-di-t-butyl-4-hydroxyphenylbenzoate, neododecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, dodecyl-β- (3,5-di- t-butyl-4-hydroxyphenyl) propionate, ethyl-α- (4-hydroxy-3,5-di-t-butylphenyl) isobutyrate Octadecyl-α- (4-hydroxy-3,5-di-t-butylphenyl) isobutyrate, octadecyl-α- (4-hydroxy-3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2- (n-octylthio) ethyl-3,5-di-t-butyl-4-hydroxybenzoate, 2- (n-octylthio) ethyl-3,5-di-t-butyl-4-hydroxyphenyl acetate, 2 -(N-octadecylthio) ethyl-3,5-di-t-butyl-4-hydroxyphenyl acetate, 2- (n-octadecylthio) ethyl-3,5-di-t-butyl-4-hydroxybenzoate, 2- (2-hydroxyethylthio) ethyl-3,5-di-t-butyl-4-hydroxybenzoate, diethyl glycol bis- (3,5 -Di-t-butyl-4-hydroxy-phenyl) propionate, 2- (n-octadecylthio) ethyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, stearamide-N, N -Bis- [ethylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], n-butylimino-N, N-bis- [ethylene-3- (3,5-di-t -Butyl-4-hydroxyphenyl) propionate], 2- (2-stearoyloxyethylthio) ethyl-3,5-di-t-butyl-4-hydroxybenzoate, 2- (2-stearoyloxyethylthio) ethyl- 7- (3-Methyl-5-tert-butyl-4-hydroxyphenyl) heptanoate, 1,2-propylene glycol bis- [3- (3,5 Di-t-butyl-4-hydroxyphenyl) propionate], ethylene glycol bis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], neopentyl glycol bis- [3- (3 , 5-di-t-butyl-4-hydroxyphenyl) propionate], ethylene glycol bis- (3,5-di-t-butyl-4-hydroxyphenyl acetate), glycerin-1-n-octadecanoate- 2,3-bis- (3,5-di-t-butyl-4-hydroxyphenyl acetate), pentaerythritol tetrakis- [3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) Propionate], 1,1,1-trimethylolethanetris- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) Lopionate], sorbitol hexa- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2-hydroxyethyl-7- (3-methyl-5-t-butyl-4-hydroxyphenyl) ) Propionate, 2-stearoyloxyethyl-7- (3-methyl-5-t-butyl-4-hydroxyphenyl) heptanoate, 1,6-n-hexanediol bis-[(3 ', 5'-di-t -Butyl-4-hydroxyphenyl) propionate], pentaerythritol tetrakis- (3,5-di-tert-butyl-4-hydroxyhydrocinnamate), 1,3,5-trimethyl-2,4,6-tris ( 3,5-di-t-butyl-4-hydroxybenzyl) benzene, 3,9-bis [1,1-dimethyl-2- [β- (3-t-butyl) Ru-4-hydroxy-5-methylphenyl) propionyloxy] ethyl] 2,4,8,10-tetraoxaspiro [5,5] -undecane, 2,4-di-t-amyl-6- [1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl] phenyl acrylate, 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl An acrylate etc. are mentioned.

  Examples of phosphorus antioxidants include tris (2,4-di-t-butylphenyl) phosphite, 2-[[2,4,8,10-tetrakis (1,1-dimethylethyl) dibenzo [d. , F] [1,3,2] dioxaphosphin-6-yl] oxy] -N, N-bis [2-[[2,4,8,10-tetrakis (1,1 dimethylethyl) dibenzo [D, f] [1,3,2] dioxaphosphin-6-yl] oxy] -ethyl] ethanamine, diphenyltridecyl phosphite, triphenyl phosphite, 2,2-methylenebis (4,6- Di-t-butylphenyl) octyl phosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, distearyl pentaerythritol diphosphite DOO, cyclic neopentanetetraylbis (2,6-di -t- butyl-4-methylphenyl) phosphite, and the like.

  Examples of the thioether-based antioxidant include pentaerythrityl tetrakis (3-laurylthiopropionate), dilauryl-3,3′-thiodipropionate, dimyristyl-3,3′-thiodipropionate, distearyl. -3,3'-thiodipropionate and the like.

Examples of the ozone deterioration preventing agent include N-isopropyl-N′-phenyl-p-phenylenediamine, N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine, and N- (1-methyl). N-alkyl-N′-phenyl-p-phenylenediamine and the like such as heptyl) -N′-phenyl-p-phenylenediamine.
Examples of the anti-aging agent include 4,4′-bis (α, α′-dimethylbenzyl) diphenylamine, N, N′-di-2-naphthyl-p-phenylenediamine, and the like.

  The content of the deterioration inhibitor (especially antioxidant) is preferably 0.05% by mass or more, more preferably 0.10% by mass or more, relative to 100% by mass of the solid content of the resin composition (C). 15 mass% or more is further more preferable, and 0.20 mass% or more is particularly preferable. The upper limit is not particularly limited, but is preferably 2% by mass or less, more preferably 1% by mass or less, because there is a possibility of bleeding out during production of the film.

  The deterioration inhibitor (especially antioxidant) may be contained by mixing (extrusion kneading) together when the (meth) acrylic resin (A) and the elastic organic fine particles (B) are mixed, You may mix with those structural components (monomer) at the time of preparation of a (meth) acrylic-type resin (A) and / or elastic organic fine particles (B). In particular, the antioxidant is desirably added to the monomer component during the synthesis of the (meth) acrylic resin (A).

  The resin composition (C) may contain other additives other than the deterioration inhibitor. The content of other additives is preferably 0 to 5% by mass, more preferably 0 to 2% by mass, and still more preferably 0 to 0.5% by mass with respect to 100% by mass of the (meth) acrylic resin (A). %. Other additives include, for example, stabilizers such as UV stabilizers (light-resistant stabilizers), weather-resistant stabilizers, UV absorbers, and heat stabilizers; retardation improvers, retardation reducers, retardation stabilizers, etc. Retardation adjusting agents; Reinforcing materials such as glass fibers and carbon fibers; Near infrared absorbing agents; Flame retardants such as tris (dibromopropyl) phosphate, triallyl phosphate and antimony oxide; Anionic, cationic and nonionic surfactants Antistatic agents such as inorganic pigments, organic pigments, dyes and other colorants; organic fillers and inorganic fillers; resin modifiers; plasticizers;

  Other additives may be contained by mixing together the (meth) acrylic resin (A) and the elastic organic fine particles (B) which are essential components, for example, (meth) acrylic. When synthesizing the system resin (A) and / or the elastic organic fine particles (B), they may be preliminarily contained in any one of the essential components such as being mixed together with their constituent components.

[Production method]
The retardation film of the present invention is obtained by forming the resin composition (C) described above into a film (forming a film) and, if necessary, stretching the obtained resin film uniaxially or biaxially in a predetermined direction. It is obtained by. In order to develop the retardation performance, it is important to orient the molecular chains in the film. For example, it is desirable to orient the molecular chains by various methods such as stretching, rolling, and take-up. In particular, in terms of production efficiency, it is preferable to develop retardation performance by stretching.

  As a method for forming a film, there is an extrusion molding method. As a specific example, each component constituting the resin composition (C) may be pre-blended with a mixer such as an omni mixer, and then the resulting mixture may be extrusion kneaded from a kneader. The kneader used for the extrusion kneading is not particularly limited, and for example, a known kneader such as a single screw extruder, a twin screw extruder, or a pressure kneader can be used.

  When an extruder is used for extrusion molding, the type is not particularly limited and may be uniaxial, biaxial, or multiaxial, but its L / D value is (L is the value of the extruder) In order to sufficiently plasticize the resin composition (C) and obtain a good kneaded state, the length of the cylinder, D is the cylinder inner diameter) is preferably 10 or more and 100 or less, more preferably 15 or more and 80 or less. More preferably, it is 20 or more and 60 or less. When the L / D value is less than 10, the resin composition (C) cannot be sufficiently plasticized and a good kneaded state may not be obtained. On the other hand, if the L / D value exceeds 100, the resin in the composition may be thermally decomposed due to excessive generation of shearing heat with respect to the resin composition (C).

  In this case, the set temperature of the cylinder is preferably 200 ° C. or higher and 300 ° C. or lower, and more preferably 250 ° C. or higher and 300 ° C. or lower. If setting temperature is less than 200 degreeC, the melt viscosity of a resin composition (C) will become high too much, and the productivity of a resin film will fall. On the other hand, if the set temperature exceeds 300 ° C., the (meth) acrylic resin (A) may be thermally decomposed.

  When an extruder is used for extrusion molding, the shape is not particularly limited, but the extruder preferably has one or more open vent portions. By using such an extruder, the decomposition gas can be sucked from the open vent portion, and the amount of volatile components remaining in the obtained resin film can be reduced. In order to suck the decomposition gas from the open vent portion, for example, the open vent portion may be in a reduced pressure state, and the degree of pressure reduction is preferably in the range of 931 to 1.3 hPa as the pressure of the open vent portion, 798 A range of ˜13.3 hPa is more preferable. When the pressure in the open vent portion is higher than 931 hPa, volatile components or monomer components generated by decomposition of the resin tend to remain in the resin. On the other hand, it is industrially difficult to keep the pressure of the open vent part lower than 1.3 hPa.

  A melt extrusion method can also be employed as a method for forming a film. Examples of the melt extrusion method include a T-die method and an inflation method. In this case, the film forming temperature is preferably 200 ° C. to 350 ° C., more preferably 250 ° C. to 300 ° C., and further preferably 255 ° C. to 300 ° C, particularly preferably 260 ° C to 300 ° C.

  When the T-die method is used, a resin film wound into a roll can be obtained by attaching a T-die to the tip of the extruder and winding up the resin film extruded from the T-die. At this time, it is also possible to control the temperature and speed of winding and to stretch (uniaxial stretching) in the extrusion direction of the film.

  In the case of melt extrusion, a method of forming a film by bringing at least one surface of the obtained film-like material into contact with a roll or a belt is preferable in that a film having good surface properties can be obtained. Furthermore, from the viewpoint of improving the surface smoothness and surface glossiness of the film, a film-like product obtained by melt extrusion molding the resin composition (C) is brought into contact with the roll surface or belt surface to form a film. The method is preferred. In addition, although the said roll may be called a "touch roll" or a "cooling roll", the term "roll" in this specification includes both these meanings.

The temperature of the film-like material when the film-like material is first brought into contact with the roll or belt surface is a temperature equal to or higher than the glass transition temperature of the film-like material, preferably about 20 ° C. higher than the glass transition temperature. .
The temperature of the roll or belt surface at the time of contacting with the film-like material is not particularly limited, but it is preferably maintained at a constant temperature from the viewpoint that it can be easily formed into a film.

  The material of the roll or belt surface is preferably a metal because of its good cooling efficiency and the ease of obtaining a film with excellent smoothness. Specific examples include stainless steel and steel. In the case of using steel, the surface thereof may be subjected to a treatment such as chrome plating. Further, the roll is preferably one having a mirror surface. The number of rolls to be used is not particularly limited, but it is desirable to use 3 to 4 rolls and adjust the film thickness and surface state in multiple stages.

  When the roll surface or the belt surface is brought into contact with one side of the film-like material, it may be performed stepwise by contacting the other surface after contacting the one surface of the film-like material, but the both surfaces are simultaneously contacted. It is preferable to make it.

  The film thus obtained has sufficient thickness accuracy and surface smoothness, but in order to further improve the thickness accuracy and surface smoothness, both surfaces or one surface thereof are in contact with the roll surface or belt surface. You may heat in the state made to cool, and it may cool in the state which contacted the roll surface or the belt surface.

  Furthermore, when a film-like material extruded from a T die or the like is sandwiched between two rolls and cooled to form a film, one of the two rolls is a rigid metal roll having a smooth surface. One is preferably a flexible roll provided with an elastically deformable metal elastic outer cylinder having a smooth surface. By sandwiching a film-like material extruded from a T-die or the like with a rigid roll and a flexible roll and cooling to form a film, fine irregularities on the surface and die lines are corrected, and the surface is smooth. A film with little thickness unevenness can be obtained.

  In addition, it is preferable to pre-dry film raw materials, such as an acrylic polymer to be used, before forming into a film. The preliminary drying can be performed, for example, using the hot air dryer or the like in the form of pellets or the like of the resin composition (C). Pre-drying is very useful because it can prevent foaming of the extruded resin.

  The raw materials (resin composition or each component constituting the resin composition) used for film formation are preferably filtered in advance with a polymer filter and then subjected to film formation. Since the foreign matter present in the resin composition can be removed by the polymer filter, defects in the appearance of the obtained film can be reduced. In addition, at the time of filtration with a polymer filter, a resin composition will be in a high temperature molten state. For this reason, when passing through the polymer filter, the resin composition deteriorates, gas components and colored deterioration products formed by the deterioration flow into the composition, and the resulting resin film has holes, flow patterns, Defects such as flow streaks may be observed. This defect is particularly easily observed during continuous molding of a resin film. For this reason, when the resin composition filtered through the polymer filter is molded, the molding temperature is set to, for example, 255 to 320 ° C. in order to reduce the melt viscosity of the resin and shorten the residence time of the resin in the polymer filter. It is preferable and it is more preferable to set it as 260-300 degreeC.

  The configuration of the polymer filter is not particularly limited, but a polymer filter in which a large number of leaf disk filters are arranged in a housing can be suitably used. The filter material of the leaf disk type filter may be any of a type in which a metal fiber nonwoven fabric is sintered, a type in which metal powder is sintered, a type in which several metal meshes are laminated, or a hybrid type in which they are combined. The sintered type is most preferred.

  The filtration accuracy by the polymer filter is not particularly limited, but is usually 15 μm or less, preferably 10 μm or less, more preferably 5 μm or less. When the filtration accuracy is 1 μm or less, the residence time of the resin becomes long, so that the thermal degradation of the composition increases, and the productivity of the resin film may decrease. On the other hand, when the filtration accuracy exceeds 15 μm, it is difficult to remove foreign substances in the resin composition.

  The shape of the polymer filter is not particularly limited. For example, an inner flow type having a plurality of resin flow ports and a resin flow path in the center pole; the inner peripheral surface of the leaf disk filter at a plurality of vertices or faces And an external flow type having a resin flow path on the outer surface of the center pole. In particular, it is preferable to use an external flow type in which the resin stays are small.

  Although there is no restriction | limiting in particular in the residence time of the resin in a polymer filter, Preferably it is 20 minutes or less, More preferably, it is 10 minutes or less, More preferably, it is 5 minutes or less. Further, the filter inlet pressure and the filter outlet pressure during filtration are, for example, 3 to 15 MPa and 0.3 to 10 MPa, respectively, and the pressure loss (the pressure difference between the filter inlet pressure and the outlet pressure) is 1 MPa to 15 MPa. A range is preferred. When the pressure loss is 1 MPa or less, the flow path through which the resin passes through the filter tends to be biased, and the quality of the obtained resin film tends to deteriorate. On the other hand, when the pressure loss exceeds 15 MPa, the polymer filter is easily damaged.

  What is necessary is just to set suitably the temperature of resin introduce | transduced into a polymer filter according to the melt viscosity, for example, it is 250-300 degreeC, Preferably it is 255-300 degreeC, More preferably, it is 260-300 degreeC.

  The specific process for obtaining a retardation film with few foreign substances and colored substances by filtration using a polymer filter is not particularly limited. For example, (1) a process in which a resin composition is formed and filtered in a clean environment, and then the resin composition is molded in a clean environment; (2) a resin composition having foreign matters or colored substances is cleaned A process in which the resin composition is subsequently molded in a clean environment after being filtered in an environment; (3) a process in which a resin composition having a foreign substance or a colored product is simultaneously filtered and molded in a clean environment; Etc. You may perform the filtration process of the resin composition by a polymer filter in multiple times for each process. Moreover, when filtering a resin composition with a polymer filter, it is preferable to install a gear pump between the extruder and the polymer filter to stabilize the pressure of the resin in the filter.

The resin film obtained by forming the resin composition into a film is preferably uniaxially or biaxially stretched in order to orient the molecular chains in the film and develop retardation performance. As a method of uniaxial stretching or biaxial stretching, a known method may be adopted, and it is not particularly limited.
Uniaxial stretching may be longitudinal stretching (stretching in the film winding direction) or transverse stretching (stretching in the film width direction). In the case of longitudinal stretching, it is typically free end uniaxial stretching in which the change in the width direction of the film is free. Fixed-end uniaxial stretching is also possible in which the change in the width direction of the film is fixed. Biaxial stretching is typically sequential biaxial stretching, but simultaneous biaxial stretching in which longitudinal and transverse stretching are simultaneously performed can also be suitably used. Furthermore, it is also possible to extend in an oblique direction with respect to the stretching in the thickness direction or the film roll. Biaxial stretching is preferred for improving mechanical strength and film performance.

  The stretching temperature at the time of stretching (uniaxial or biaxial) is preferably in the vicinity of the glass transition temperature of the resin film, and specifically, (glass transition temperature −30 ° C.) to (glass transition temperature + 100 ° C.). Within the range, the range of (glass transition temperature−20 ° C.) to (glass transition temperature + 80 ° C.) is more preferable. If the stretching temperature is less than (glass transition temperature-30 ° C.), there is a possibility that a sufficient stretching ratio cannot be obtained. On the other hand, when the stretching temperature exceeds (glass transition temperature + 100 ° C.), the resin composition may flow and may not be stably stretched. Moreover, the draw ratio defined by area ratio becomes like this. Preferably it is 1.1-25 times, More preferably, it is 1.3-10 times. There exists a possibility that it may not lead to the improvement of the toughness accompanying extending | stretching that a draw ratio is less than 1.1 times. On the contrary, when the draw ratio exceeds 25 times, there is a possibility that the effect of increasing the draw ratio is not recognized. The stretching speed is unidirectional, preferably 10 to 20,000% / min, more preferably 100 to 10,000% / min. If the stretching speed is less than 10% / min, it takes time to obtain a sufficient stretching ratio, and the production cost may increase. On the other hand, when the stretching speed exceeds 20,000% / min, the stretched film may be broken.

  The stretched film is preferably subjected to heat treatment (annealing) or the like after the stretching treatment in order to stabilize its optical isotropy and mechanical properties. The conditions for the heat treatment may be appropriately set according to the stretching conditions and the physical properties of the resin, but are preferably Tg-30 ° C. or higher of the resin composition and Tg + 20 ° C. or higher of the resin composition.

  Moreover, as a means for orienting molecular chains in the resin film to develop the retardation performance, a method such as rolling or taking-up can be employed. In order to orient the molecular chain by rolling, for example, when forming into a film by a calendar method or the like, the melt temperature of the resin composition, the roll diameter and the number of rotations are controlled to stretch in the film extrusion direction (uniaxial stretching). Can be added. In order to orient the molecular chain by pulling, for example, when forming a film by the T-die method, a T-die is attached to the tip of the extruder, and the resin film extruded from the T-die is wound into a roll. The film may be stretched (uniaxially stretched) in the film extrusion direction by controlling the temperature and speed of winding at this time.

[Phase difference film]
The retardation film of the present invention may be referred to as the rate of change of in-plane retardation Re (590) at a wavelength of 590 nm (hereinafter referred to as “200 hours Re change rate”) before and after the thermal acceleration test held at 90 ° C. for 200 hours. Is 5% or less, more preferably 4% or less, still more preferably 2% or less, and particularly preferably 1% or less. When the 200-hour Re change rate is within the above range, it is possible to suppress aged deterioration of display quality when applied to a heat generating part in a liquid crystal display device or an organic EL display. The details of the thermal acceleration test held at 90 ° C. for a predetermined time are as described later in the examples.

  Further, in the retardation film of the present invention, the rate of change of the in-plane retardation Re (590) at a wavelength of 590 nm (hereinafter referred to as “1000 hours Re change rate”) before and after the thermal acceleration test held at 90 ° C. for 1000 hours. May be 10% or less, more preferably 8% or less, still more preferably 6% or less, and particularly preferably 5% or less. When the 1000-hour Re change rate is within the above range, it is possible to suppress deterioration over time in display quality when applied to a heat generation site in a liquid crystal display device or an organic EL display for a longer period. The details of the thermal acceleration test held at 90 ° C. for a predetermined time are as described later in the examples.

  The retardation change rate (200 hour Re change rate and 1000 hour Re change rate) before and after the thermal acceleration test was determined as Re (0 hr) as the in-plane retardation of the retardation film, and after performing the 200 hour thermal acceleration test. When the in-plane phase difference is Re (200 hr) and the in-plane phase difference after the 1000-hour thermal acceleration test is Re (1000 hr), the formula: Re (200 hr) / Re (0 hr) × 100-100, And the absolute value of the value defined by the formula: Re (1000 hr) / Re (0 hr) × 100-100.

  In the present invention, the in-plane retardation Re is the refractive index in the slow axis direction in the film plane nx, the refractive index in the fast axis direction in the film plane ny, and the refractive index in the thickness direction of the film. nz, where d is the thickness of the film, the value is defined by the formula: Re = (nx−ny) × d, and the thickness direction retardation Rth is the formula: Rth = [(nx + ny) / 2 −nz] × d, which is a defined value. Further, a film having a large refractive index in the stretching direction is said to have positive intrinsic birefringence, and a film having a large refractive index in the direction perpendicular to the stretching direction in the film plane is said to have negative intrinsic birefringence.

  Examples of the method of setting the 200-hour Re change rate to 5% or less include a method of blending a deterioration inhibitor such as an antioxidant, an ozone deterioration inhibitor, or an antiaging agent. Thereby, oxygen can be captured, and a decrease in retardation and orientation relaxation due to the elastic organic fine particles (B) are suppressed, so that the 200 hour Re change rate can be within the above range.

As the antioxidant, the above-mentioned phenol-based antioxidant, phosphorus-based antioxidant, thioether-based antioxidant, and the like are preferably used, and commercially available products such as “Nauguard (registered trademark) EX-1” manufactured by Shiraishi Calcium Co., Ltd. Can be used.
Examples of the ozone deterioration preventing agent include the above-described N-alkyl-N′-phenyl-p-phenylenediamine, and commercially available products include “Ozonon (registered trademark) EX” and “Ozonone ( (Registered trademark) EX-3 "is preferably used.
Examples of the antioxidant include the above-mentioned compounds (4,4′-bis (α, α′-dimethylbenzyl) diphenylamine, N, N′-di-2-naphthyl-p-phenylenediamine, etc.).

  As the deterioration inhibitor, an antioxidant is preferable, and it is particularly preferable to use a phenol-based antioxidant in combination with a thioether-based antioxidant and / or a phosphorus-based antioxidant. By using two kinds of antioxidants in combination, the 200-hour Re change rate, and further the 1000-hour Re change rate can be significantly reduced.

  In particular, as the phenolic antioxidant, those having two or more phenol groups in the molecule are more preferable, and those having three or more phenol groups in the molecule are more preferable. The two or more phenol groups are preferably bonded with a hydrocarbon group. The molecular weight of the phenolic antioxidant is more preferably 600 or more, and even more preferably 700 or more. When the molecule has two or more phenol groups in the molecule and the molecular weight is 600 or more, there is little volatilization of the antioxidant during melt molding, and the effect of reducing the rate of change in retardation after heat treatment is greater.

  As a method of setting the 200-hour Re change rate to 5% or less, as described in JP 2010-26098 A, after stretching, a specific temperature condition (Tg-30 ° C. or higher of the main constituent resin of the film) In addition, a method of heat setting with Tg + 20 ° C. or less of the main constituent resin of the film is also effective. Thereby, the orientation relaxation is fixed and the change of the phase difference can be suppressed. However, the phase difference itself tends to decrease during heat setting, and in particular, an elastic organic material having a relatively small particle diameter having a (meth) acrylic resin (A) and a conjugated diene monomer structural unit as in the present invention. In the case of a film containing fine particles (B), the influence is great. Therefore, in the present invention, in addition to the above-described blending of the deterioration preventing agent, it is preferable to perform heat setting at a specific temperature.

  Further, as a method of setting the 200 hour Re change rate to 5% or less, it is also effective to increase the glass transition temperature of the retardation film.

  In the retardation film of the present invention, when the 200-hour Re change rate and the 1000-hour Re change rate are obtained, the change value of the retardation defined by the formula: ΔRe = Re (200hr) −Re (0hr) is −10 It is preferably 10 nm, more preferably −5 to 5 nm, and even more preferably −2 to 2 nm.

  In the retardation film of the present invention, when the in-plane retardation for light having a wavelength of 447 nm is Re (447) and the in-plane retardation for light having a wavelength of 590 nm is Re (590), Re (447) / Re ( 590) <1 is preferred. If Re (447) / Re (590) <1, the film exhibits reverse wavelength dispersion. The value of Re (447) / Re (590) is more preferably 0.70 to 0.99, further preferably 0.75 to 0.97, and particularly preferably 0.80 to 0.93. . Since the retardation film of the present invention has a small retardation change rate after the heat treatment, it is also possible to reduce the time-dependent change in wavelength dispersion defined by Re (447) / Re (590). In addition, Re (447) and Re (590) can be calculated | required by the method mentioned later in an Example, for example.

  In order to set the value of Re (447) / Re (590) within the above range, for example, (meth) acrylic resin (A) has a ring structure in the main chain, and (i) (meth) It shall have a heteroaromatic ring structure (preferably a structure derived from vinyl carbazole) in the side chain of the acrylic resin (A), or (ii) a heteroaromatic group in the side chain of the (meth) acrylic resin (A). A resin having a group ring structure (preferably a structure derived from vinyl carbazole) and a polymer alloy may be formed.

  The in-plane retardation (Re (590)) with respect to light having a wavelength of 590 nm in the retardation film of the present invention may be appropriately set depending on the application, and is not particularly limited. For example, when the retardation film of the present invention is used as a λ / 2 plate, Re at 590 nm is preferably 200 to 360 nm, more preferably 240 to 320 nm, and particularly preferably 260 to 300 nm. On the other hand, when the retardation film of the present invention is used as a λ / 4 plate, Re at 590 nm is preferably 100 to 200 nm, more preferably 120 to 180 nm, particularly preferably 130 to 160 nm, and most preferably. Is 135 to 155 nm.

In addition, Re (590) of a film can be adjusted with the manufacturing method (especially stretching method etc.) of a film. For example, when the retardation film of the present invention is a uniaxially stretched film, the in-plane retardation Re at a wavelength of 590 nm can be 50 to 300 nm, and the thickness direction retardation Rth is 10 to 300 nm. For a thickness of 100 μm, the in-plane retardation Re at a wavelength of 590 nm can be 50 to 500 nm, and the thickness direction retardation Rth is 10 to 500 nm.
On the other hand, when the retardation film of the present invention is a biaxially stretched film, the in-plane retardation Re at 590 nm can be 20 to 70 nm, and the retardation value Rth is 70 to 400 nm. When the thickness is about 100 μm, the in-plane retardation Re at a wavelength of 590 nm can be 20 to 110 nm, and the thickness direction retardation Rth is 70 to 800 nm.

  The “in-plane retardation at a wavelength of 590 nm per 100 μm thickness” is a value at d = 100 × 1000 nm in the above formula for obtaining the in-plane retardation Re. The “thickness direction retardation at a wavelength of 590 nm per thickness of 100 μm” is a value at d = 100 × 1000 nm in the above equation for obtaining the thickness direction retardation (Rth).

  The retardation film of the present invention has a high light transmittance. The total light transmittance measured according to JIS K7361-1 is preferably 80% or more, more preferably 85% or more, still more preferably 90% or more, and particularly preferably 92% or more.

  The retardation film of the present invention has an internal haze measured according to JIS K7136, preferably 5% or less, more preferably 3% or less, still more preferably 1% or less, and particularly preferably 0. .5% or less. A film having a haze exceeding 5% may have low transmittance and may not be suitable for optical applications.

The stress optical coefficient (Cr) of the retardation film of the present invention is preferably 0.30 × 10 ⁻⁹ Pa ⁻¹ or more. When Cr is less than 0.30 × 10 ⁻⁹ Pa ⁻¹ , the stress for inducing the required birefringence increases, and the film is likely to be broken, which is not preferable. Although an upper limit does not have a restriction | limiting in particular, Usually, it is 6.50 * 10 <^-9> Pa <^-1> or less. In addition, the stress optical coefficient of a film can be calculated | required by the method of Unexamined-Japanese-Patent No. 2011-111466, for example.

  The retardation film of the present invention is less colored and has a b value of preferably 5 or less, more preferably 3 or less, still more preferably 1 or less, and particularly preferably 0.5 or less. In addition, b value of a film shows the value of b * by the display of the hue based on JISZ8729, and can be measured using a colorimetric color difference meter, for example.

  The retardation film of the present invention preferably has a glass transition temperature of 110 ° C to 200 ° C. More preferably, it is 115 degreeC-200 degreeC, More preferably, it is 120 degreeC-200 degreeC, Especially preferably, it is 125 degreeC-190 degreeC, Most preferably, it is 130 degreeC-180 degreeC. When the temperature is lower than 110 ° C, the heat resistance is insufficient with respect to the harsh use environment, and the film may be deformed to cause uneven retardation. On the other hand, when the temperature exceeds 200 ° C, the film is obtained. There is a possibility that the moldability of the film is poor or the flexibility of the film is greatly reduced.

  The thickness of the retardation film of the present invention is 1-1000 μm, preferably 5-350 μm, more preferably 10-150 μm, and further preferably 20-100 μm. When the thickness is less than 1 μm, the strength as a film may be insufficient, and there is a risk of breakage or the like when performing post-processing.

  Various functional coating layers may be formed on the surface of the retardation film of the present invention, if necessary, as long as the effects of the present invention are not impaired. Examples of the functional coating layer include an antistatic layer, an adhesive layer, an adhesive layer, an easy-adhesion layer, an antiglare (non-glare) layer, an antifouling layer such as a photocatalyst layer, an antireflection layer, a hard coat layer, and an ultraviolet ray. Examples thereof include a shielding layer, a heat ray shielding layer, an electromagnetic wave shielding layer, and a gas barrier layer. These functional coating layers may be formed before stretching of the long film or may be formed after stretching.

  Although the use of the retardation film of the present invention is not particularly limited, it can be preferably used as a λ / 4 plate for an elliptically polarizing plate. The elliptically polarizing plate obtained from the retardation film of the present invention can be preferably used as an antireflection film for liquid crystal display devices and organic electroluminescent display devices.

  When the retardation film of the present invention is an elliptically polarizing plate, it may be bonded to a polarizing plate having a polarizer protective film on both sides, or the retardation film of the present invention may be used on one side of the polarizer protective film. Good. When using the retardation film of this invention for the single side | surface of a polarizer protective film, it is preferable to form an easily bonding layer on the surface of the retardation film of this invention.

  Since the retardation film of the present invention has high transparency and heat resistance, it can be suitably used as various optical members. As the optical member, for example, an optical protective film (specifically, a protective film for various optical disk (VD, CD, DVD, MD, LD, etc.) substrates, an image display device such as a liquid crystal display device (LCD)) is provided. And a polarizer protective film used for a polarizing plate. Further, the retardation film of the present invention may be used as an optical film such as a retardation film, a viewing angle compensation film, a light diffusion film, a reflection film, an antireflection film, an antiglare film, a brightness enhancement film, and a conductive film for a touch panel. Good.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In the following description, “%” represents “mass%” and “part” represents “part by mass” unless otherwise specified. In the embodiments, the following abbreviations will be used for convenience.
MMA: methyl methacrylate MHMA: 2- (hydroxymethyl) methyl acrylate MA: methyl acrylate NVCz: N-vinylcarbazole

Measurement and evaluation of various physical properties in the following examples were performed by the following methods.
[Weight average molecular weight and number average molecular weight of resin]
The weight average molecular weight (Mw) and number average molecular weight (Mn) of the resin were determined according to the following measurement conditions using gel permeation chromatography (GPC).
Measurement system: “GPC system HLC-8220” manufactured by Tosoh Corporation
Developing solvent: Chloroform (Wako Pure Chemical Industries, special grade)
Solvent flow rate: 0.6 mL / min Standard sample: TSK standard polystyrene (“PS-oligomer kit” manufactured by Tosoh Corporation)
Measurement side column configuration: guard column (“TSK guardcolumn SuperHZ-L” manufactured by Tosoh Corporation), separation column (“TSK Gel Super HZM-M” manufactured by Tosoh Corporation), two in series Reference side column configuration: reference column (Tosoh Corporation) "TSK gel SuperH-RC")

[Glass transition temperature of resin and film]
The glass transition temperature (Tg) of the resin and film was measured in accordance with JIS K7121 regulations. Specifically, using a differential scanning calorimeter (“Thermo plus EVO DSC-8230” manufactured by Rigaku Corporation), a sample of about 10 mg was heated from room temperature to 200 ° C. under a nitrogen gas atmosphere (heating rate 20 ° C./min). ) From the DSC curve obtained by the above method. Α-alumina was used as a reference.

[Volume average particle diameter of elastic organic fine particles]
The volume average particle diameter of the elastic organic fine particles was measured using a particle size distribution measuring apparatus (“Submicron Particle Sizer NICOM 380” manufactured by NICOMP).

[In-plane retardation Re of film, wavelength dispersibility of film and intrinsic birefringence (refractive index anisotropy) of resin composition]
The in-plane retardation Re (590) of the film with respect to light having a wavelength of 590 nm was measured using a retardation measuring device (“KOBRA-WR” manufactured by Oji Scientific Instruments). Specifically, the incident angle dependency (single N calculation) is selected as the measurement item, the average refractive index of the film measured with an Abbe refractometer, with the tilt axis as the slow axis and the incident angle as 40 °. And the film thickness d (nm) of the film measured with a Digimatic Micrometer (Mitutoyo) is input, and the slow axis direction in the plane of the film (the direction showing the maximum refractive index in the plane of the film) And the refractive index ny in the fast axis direction (direction perpendicular to nx in the film plane) in the plane of the film. And the in-plane retardation Re of the film was computed based on the following formula.

      Re = (nx−ny) × d

  The wavelength dispersion of the film was measured in the in-plane retardation Re (447) for light having a wavelength of 447 nm in the same manner as Re (590) except that the wavelength was changed to 447 nm. The value of Re (447) / Re (590) was calculated from Re (447). If this value is less than 1, it can be said that it has reverse wavelength dispersion.

  The positive / negative of the intrinsic birefringence of the resin composition constituting the retardation film was evaluated based on the orientation angle of a film obtained by uniaxially stretching the resin composition. Specifically, when the measured orientation angle is 0 ° or more and less than 45 ° with respect to the stretching direction (the slow axis is substantially parallel), the intrinsic birefringence of the resin composition is positive, and the measured orientation angle is In the case of 45 ° or more and 90 ° or less (the slow axis is substantially vertical), the intrinsic birefringence of the resin composition was negative.

[Re change rate in thermal acceleration test (phase difference durability)]
The retardation films obtained in each Example and Comparative Example were subjected to a thermal acceleration test in which the films were held in a hot air dryer set at 90 ° C. Then, after 200 hours and 1000 hours from the start of the thermal acceleration test, the in-plane retardation Re (590) of the film with respect to light having a wavelength of 590 nm was measured. Then, the value after 200 hours is Re (200 hr), the value after 1000 hours is Re (1000 hr), and Re (590) before being subjected to the thermal acceleration test (that is, the above-mentioned [in-plane retardation Re of film]). ΔRe (200) and ΔRe (1000) were obtained based on the following formula, where Re (0hr) was the value obtained in (1).
ΔRe (200) = Re (200hr) −Re (0hr)
ΔRe (1000) = Re (1000 hr) −Re (0 hr)
Further, a value of (ΔRe / Re (0hr)) × 100 was calculated from each ΔRe, and the absolute value was defined as the Re change rate (%).

(Production Example 1) [Production of acrylic resin (A-1)]
MHMA 15 parts, MMA 26.8 parts, MA 10 parts, NVCz 6.4 parts, toluene 37 parts and methanol 2 parts were charged into a reaction vessel equipped with a stirrer, temperature sensor, cooling pipe, nitrogen introduction pipe and dropping funnel. While introducing nitrogen gas into the reaction vessel, the temperature was raised to 95 ° C. and refluxing was started. As a polymerization initiator, t-amylperoxy-2-ethylhexanoate (“Lupelox (registered trademark)” manufactured by Arkema Yoshitomi Co., Ltd. was used. 575 ") 0.06 part was added and simultaneously dropwise addition of a mixture of 15 parts MHMA, 26.8 parts MMA, 28 parts toluene and 0.15 part t-amylperoxy-2-ethylhexanoate. While this mixture was added dropwise over 8 hours, solution polymerization was performed at about 90 ° C. to 100 ° C. under reflux. At this time, from 5 hours after the start of polymerization (start of dropping of the mixture), 13.3 parts of toluene was separately added dropwise over 3 hours to dilute the polymerization solution.

  Next, 0.2 parts of stearyl phosphate (“Phoslex A-18” manufactured by Sakai Chemical Industry Co., Ltd.) as a cyclization catalyst was added to the obtained copolymer solution, and refluxed at 80 ° C. to 105 ° C. for 2 hours. A cyclization condensation reaction was performed. Thereafter, 16.6 parts of methyl isobutyl ketone (MIBK) was added to dilute the resulting copolymer solution.

  Next, the obtained copolymer solution was heated to 240 ° C. through a heat exchanger, barrel temperature 240 ° C., degree of vacuum 13.3 to 400 hPa (10 to 300 mmHg), rear vent number 1 and fore vent number 4 Vent type screw twin screw extruder (L / L), each of which is called a first, second, third and fourth vent from the upstream side, and a leaf disk type polymer filter (filtration accuracy 5 μm) is arranged at the tip. D = 52) was introduced at a treatment rate of 100 parts / hour in terms of resin amount, and devolatilization was performed. At that time, a separately prepared mixed solution of antioxidant / cyclization catalyst deactivator was added at a rate of 1.86 parts / hour from the back of the second vent, and 0.5 parts / hour of ion-exchanged water. Each was added from behind the third vent at a charging speed of. The antioxidant / cyclization catalyst deactivator mixed solution was 1.35 parts of pentaerythritol tetrakis- [3- (3 ′, 5′-di-t-butyl-4′-) as a phenolic antioxidant. Hydroxyphenyl) propionate] ("Irganox (registered trademark) 1010" manufactured by BASF Japan) and 1.35 parts of pentaerythrityltetrakis (3-laurylthiopropionate) (made by ADEKA) as a thioether-based antioxidant ADEKA STAB (registered trademark) AO-412S ") and 9.7 parts of zinc octylate (" Nikka Octix Zinc 18% "manufactured by Nippon Kagaku Kogyo Co., Ltd.) as a cyclization catalyst deactivator. ("Irganox 1010" and "AO-412S" contained 0.025% each in the resin). After the devolatilization step, the resulting resin (intramolecular cyclized methacrylic copolymer) was pelletized to obtain an acrylic resin (A-1) pellet. The obtained acrylic resin (A-1) had a weight average molecular weight (Mw) of 87,000, a number average molecular weight (Mn) of 37,000, and a glass transition temperature (Tg) of 130 ° C.

(Production Example 2) [Production of elastic organic fine particles (B-1)]
In a pressure-resistant reaction vessel equipped with a stirrer, 70 parts of deionized water, 0.5 part of sodium pyrophosphate, 0.2 part of potassium oleate, 0.005 part of ferrous sulfate, 0.2 part of dextrose, p-menthane hydro A mixture comprising 0.1 part of peroxide and 28 parts of 1,3-butadiene was added, the temperature was raised to 65 ° C., and a polymerization reaction was carried out for 2 hours. Next, 0.2 parts of p-menthane hydroperoxide was added to the obtained reaction mixture, and then a mixture of 72 parts of 1,3-butadiene, 1.33 parts of potassium oleate and 75 parts of deionized water was added for 2 hours. It was dripped continuously over the time. The reaction was continued for 21 hours from the start of polymerization to obtain a butadiene rubber polymer latex having a volume average particle size of 0.240 μm.

  Next, in a polymerization vessel equipped with a cooler and a stirrer, 120 parts of deionized water, 50 parts of the above butadiene rubber polymer latex as a solid content, 1.5 parts of potassium oleate, sodium formaldehyde sulfoxylate ( (SFS) 0.6 part was added, and the inside of the polymerization vessel was sufficiently replaced with nitrogen gas. Subsequently, after raising the internal temperature to 70 ° C., a mixed monomer solution consisting of 36.5 parts of styrene and 13.5 parts of acrylonitrile, 0.27 parts of cumene hydroxyperoxide, and 20 parts of deionized water are polymerized. Polymerization was carried out while continuously dropping the initiator solution separately over 2 hours. After completion of the dropwise addition, the internal temperature was raised to 80 ° C. and polymerization was continued for 2 hours. Next, after cooling to an internal temperature of 40 ° C., the mixture was passed through a 300 mesh wire net to obtain an emulsion polymerization liquid of elastic organic fine particles. The obtained emulsion polymerization liquid of elastic organic fine particles was salted out and coagulated with calcium chloride, washed with water and dried to obtain powdered elastic organic fine particles (B-1). The volume average particle diameter of the elastic organic fine particles was 0.260 μm.

(Production Example 3) [Production of Acrylic Resin (A-2)]
MHMA 15 parts, MMA 27 parts, MA 10 parts, NVCz 6 parts, toluene 37 parts and methanol 2 parts were charged into a reaction vessel equipped with a stirrer, temperature sensor, cooling pipe, nitrogen introduction pipe and dropping funnel. While introducing nitrogen gas into the reaction vessel, the temperature was raised to 95 ° C. and refluxing was started. As a polymerization initiator, t-amylperoxy-2-ethylhexanoate (“Lupelox (registered trademark)” manufactured by Arkema Yoshitomi Co., Ltd. was used. 575 ") 0.029 parts was added and simultaneously dropwise addition of a mixture of 15 parts MHMA, 27 parts MMA, 17 parts toluene and 0.082 parts t-amylperoxy-2-ethylhexanoate. While this mixture was added dropwise over 8 hours, solution polymerization was performed at about 90 ° C. to 100 ° C. under reflux. At this time, from 5 hours after the start of polymerization (start of dropping of the mixture), 23.3 parts of toluene was separately added dropwise over 3 hours to dilute the polymerization solution.

  Next, 0.24 part of an octyl phosphate / dioctyl mixture as a cyclization catalyst was added to the obtained copolymer solution, and a cyclization condensation reaction was performed at 80 ° C. to 105 ° C. under reflux for 2 hours. Thereafter, 21.4 parts of methyl isobutyl ketone (MIBK) was added to dilute the resulting copolymer solution.

  Next, the obtained copolymer solution was heated to 240 ° C. through a heat exchanger, barrel temperature 250 ° C., degree of vacuum 13.3 to 400 hPa (10 to 300 mmHg), rear vent number 1 and fore vent number 4 Vent type screw twin screw extruder (L / L), each of which is called a first, second, third and fourth vent from the upstream side, and a leaf disk type polymer filter (filtration accuracy 5 μm) is arranged at the tip. D = 52) was introduced at a treatment rate of 100 parts / hour in terms of resin amount, and devolatilization was performed. At that time, a separately prepared mixed solution of antioxidant / cyclization catalyst deactivator was added at a rate of 3.8 parts / hour from the back of the second vent, and 0.5 parts / hour of ion-exchanged water. Each was added from behind the third vent at a charging speed of. The antioxidant / cyclization catalyst deactivator mixed solution was 0.65 parts of pentaerythritol tetrakis- [3- (3 ′, 5′-di-t-butyl-4′-) as a phenolic antioxidant. Hydroxyphenyl) propionate] ("Irganox (registered trademark) 1010" manufactured by BASF Japan) and 0.65 parts of pentaerythrityltetrakis (3-laurylthiopropionate) (made by ADEKA) as a thioether-based antioxidant ADEKA STAB (registered trademark) AO-412S ") and 9.9 parts of zinc octylate (" Nikka Octix Zinc 18% "manufactured by Nippon Chemical Industry Co., Ltd.) as a cyclization catalyst deactivator. ("Irganox 1010" and "AO-412S" contained 0.025% each in the resin). After the devolatilization step, the resulting resin (intramolecular cyclized methacrylic copolymer) was pelletized to obtain an acrylic resin (A-2) pellet. The obtained acrylic resin (A-2) had a weight average molecular weight (Mw) of 110,000 and a glass transition temperature (Tg) of 132 ° C.

Example 1
83.91 parts of acrylic resin (A-1) produced in Production Example 1, 16 parts of elastic organic fine particles (B-1) produced in Production Example 2, and pentaerythritol tetrakis- [3, which is a phenolic antioxidant -(3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] (“Irganox (registered trademark) 1010” manufactured by BASF Japan Ltd.) 0.03 part and bis which is a phosphorus antioxidant Using 0.06 part of (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite (“ADEKA STAB (registered trademark) PEP-36” manufactured by ADEKA) using a twin screw extruder Were kneaded at 240 ° C. to obtain resin composition pellets (C-1).

The obtained pellet (C-1) was press-molded at 240 ° C. by a press molding machine to obtain an original film having a thickness of about 140 μm. Next, the original film was uniaxially stretched at a free end using an autograph (manufactured by Shimadzu Corporation) at a stretching temperature of 135 ° C. and a speed of 40 mm / min so as to double the distance between the chucks of 40 mm to a thickness of A 100 μm retardation film (F-1) was obtained.
The obtained retardation film has an in-plane retardation Re (590) for light having a wavelength of 590 nm of 166 nm, a wavelength dispersion of 0.97, and the intrinsic birefringence of the resin composition (C-1) is positive. The glass transition temperature (Tg) of the film was 128 ° C. The Re change rate in the thermal acceleration test of the obtained retardation film (F-1) was as shown in Table 1.

(Example 2)
83.7 parts of the acrylic resin (A-1) produced in Production Example 1, 16 parts of elastic organic fine particles (B-1) produced in Production Example 2, and the phenolic antioxidant used in Example 1 0.1 part of “Irganox 1010”) and 0.2 part of “Adekastab PEP-36”, which is a phosphorus-based antioxidant used in Example 1, were kneaded at 240 ° C. using a twin-screw extruder, Resin composition pellets (C-2) were obtained.

A retardation film (F-2) was obtained in the same manner as in Example 1 except that the obtained pellet (C-2) was used.
The obtained retardation film has an in-plane retardation Re (590) of 152 nm and wavelength dispersion of 0.97 for light with a wavelength of 590 nm, and the intrinsic birefringence of the resin composition (C-2) is positive. The glass transition temperature (Tg) of the film was 128 ° C. The Re change rate in the thermal acceleration test of the obtained retardation film (F-2) was as shown in Table 1.

(Example 3)
83.7 parts of the acrylic resin (A-1) produced in Production Example 1, 16 parts of elastic organic fine particles (B-1) produced in Production Example 2, and the phenolic antioxidant used in Example 1 0.1 part of “Irganox 1010”) and 0.2 part of distearyl-3,3′-thiodipropionate (“Sumilyzer (registered trademark) TPS” manufactured by Sumitomo Chemical Co., Ltd.), which is a thioether antioxidant, The mixture was kneaded at 240 ° C. using a twin screw extruder to obtain resin composition pellets (C-3).

A retardation film (F-3) was obtained in the same manner as in Example 1 except that the obtained pellet (C-3) was used.
The in-plane retardation Re (590) for the light of wavelength 590 nm of the obtained retardation film is 166 nm, the wavelength dispersion is 0.97, and the intrinsic birefringence of the resin composition (C-3) is positive, The glass transition temperature (Tg) of the film was 128 ° C. The Re change rate in the thermal acceleration test of the obtained retardation film (F-3) was as shown in Table 1.

(Comparative Example 1)
84 parts of acrylic resin (A-1) produced in Production Example 1 and 16 parts of elastic organic fine particles (B-1) produced in Production Example 2 were kneaded at 240 ° C. using a twin screw extruder, and the resin A composition pellet (C-4) was obtained.

A retardation film (F-4) was obtained in the same manner as in Example 1 except that the obtained pellet (C-4) was used.
The in-plane retardation Re (590) of the obtained retardation film for light having a wavelength of 590 nm is 158 nm, the wavelength dispersion is 0.97, and the intrinsic birefringence of the resin composition (C-4) is positive. The glass transition temperature (Tg) of the film was 128 ° C. The Re change rate in the thermal acceleration test of the obtained retardation film (F-4) was as shown in Table 1.

Example 4
80.5 parts of acrylic resin (A-2) produced in Production Example 3, 13.9 parts of elastic organic fine particles (B-1) produced in Production Example 2, and a styrene-acrylonitrile copolymer (AS resin: styrene) Unit / acrylonitrile unit ratio of 73% by mass / 27% by mass, weight average molecular weight 220,000) 5 parts, phenolic antioxidant used in Example 1, “Irganox 1010”) 0.2 part, Examples 0.4 part of “Adeka Stub PEP-36”, which is a phosphorus-based antioxidant used in No. 1, was kneaded at 240 ° C. using a twin screw extruder to obtain a resin composition pellet (C-5). .
A retardation film (F-5) was obtained in the same manner as in Example 1 except that the obtained pellet (C-5) was used.
The obtained retardation film has an in-plane retardation Re (590) for light having a wavelength of 590 nm of 142 nm, a wavelength dispersion of 0.93, and the intrinsic birefringence of the resin composition (C-5) is positive. The glass transition temperature (Tg) of the film was 128 ° C. The Re change rate in the thermal acceleration test of the obtained retardation film (F-5) was as shown in Table 2.

(Example 5)
80.5 parts of acrylic resin (A-2) produced in Production Example 3, 13.9 parts of elastic organic fine particles (B-1) produced in Production Example 2, and 5 parts of AS resin used in Example 4 In addition, 0.2 part of “Irganox 1010”, which is a phenolic antioxidant used in Example 1, and 0.4 part of “Sumilyzer TPS”, which is a thioether-based antioxidant used in Example 3, were subjected to biaxial extrusion. The mixture was kneaded at 240 ° C. using a machine to obtain resin composition pellets (C-6).
A retardation film (F-6) was obtained in the same manner as in Example 1 except that the obtained pellet (C-6) was used.
The in-plane retardation Re (590) of the obtained retardation film for light having a wavelength of 590 nm is 143 nm, the wavelength dispersion is 0.92, and the intrinsic birefringence of the resin composition (C-6) is positive. The glass transition temperature (Tg) of the film was 128 ° C. The Re change rate in the thermal acceleration test of the obtained retardation film (F-6) was as shown in Table 2.

(Example 6)
80.5 parts of acrylic resin (A-2) produced in Production Example 3, 13.9 parts of elastic organic fine particles (B-1) produced in Production Example 2, and 5 parts of AS resin used in Example 4 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene (“Irganox (registered trademark)” manufactured by BASF Japan Ltd., which is a phenolic antioxidant ) 1330 ") 0.2 part and 0.4 part of" Adeka Stub PEP-36 "), which is the phosphorus-based antioxidant used in Example 1, were kneaded at 240 ° C using a twin screw extruder, Resin composition pellets (C-7) were obtained.
A retardation film (F-7) was obtained in the same manner as in Example 1 except that the obtained pellet (C-7) was used.
The obtained retardation film has an in-plane retardation Re (590) with respect to light having a wavelength of 590 nm of 140 nm, wavelength dispersion of 0.93, and the intrinsic birefringence of the resin composition (C-7) is positive. The glass transition temperature (Tg) of the film was 128 ° C. The Re change rate in the thermal acceleration test of the obtained retardation film (F-7) was as shown in Table 2.

(Example 7)
80.5 parts of acrylic resin (A-2) produced in Production Example 3, 13.9 parts of elastic organic fine particles (B-1) produced in Production Example 2, and 5 parts of AS resin used in Example 4 0.2 parts of “Irganox 1330”, which is a phenolic antioxidant used in Example 6, and 0.4 part of “Sumilyzer TPS”, which is a thioether-based antioxidant used in Example 3. It knead | mixed at 240 degreeC using the extruder, and obtained the resin composition pellet (C-8).
A retardation film (F-8) was obtained in the same manner as in Example 1 except that the obtained pellet (C-8) was used.
The in-plane retardation Re (590) of the obtained retardation film for light having a wavelength of 590 nm is 144 nm, the wavelength dispersion is 0.92, and the intrinsic birefringence of the resin composition (C-8) is positive. The glass transition temperature (Tg) of the film was 128 ° C. The Re change rate in the thermal acceleration test of the obtained retardation film (F-8) was as shown in Table 2.

(Comparative Example 2)
Biaxially, 81 parts of acrylic resin (A-2) produced in Production Example 3, 14 parts of elastic organic fine particles (B-1) produced in Production Example 2, and 5 parts of AS resin used in Example 4 were biaxial. It knead | mixed at 240 degreeC using the extruder, and obtained the resin composition pellet (C-9).
A retardation film (F-9) was obtained in the same manner as in Example 1 except that the obtained pellet (C-9) was used.
The in-plane retardation Re (590) of the obtained retardation film for light having a wavelength of 590 nm is 141 nm, the wavelength dispersion is 0.93, and the intrinsic birefringence of the resin composition (C-9) is positive. The glass transition temperature (Tg) of the film was 128 ° C. The Re change rate in the thermal acceleration test of the obtained retardation film (F-9) was as shown in Table 2.

  The retardation film of the present invention can be widely used for image display devices such as a liquid crystal display device (LCD) and an organic EL display, similarly to the conventional retardation film. Display characteristics in an image display device can be improved by an elliptically polarizing plate using the retardation film.

Claims (8)

Elastic organic fine particles (B) having a volume average particle diameter of 0.350 μm or less having (meth) acrylic resin (A) and a conjugated diene monomer structural unit constructed by polymerizing a conjugated diene monomer as essential components An acrylic retardation film comprising a resin composition (C) containing
A retardation film having a change rate of in-plane retardation Re (590) at a wavelength of 590 nm of 5% or less before and after a thermal acceleration test held at 90 ° C. for 200 hours.   The retardation film according to claim 1, wherein the elastic organic fine particles (B) have a core-shell structure including a core portion and a shell portion having a structure having the conjugated diene monomer structural unit as an essential component.   The retardation film according to claim 1, wherein the resin composition (C) contains an antioxidant.   The retardation film according to any one of claims 1 to 3, wherein the rate of change of the in-plane retardation Re (590) at a wavelength of 590 nm is 10% or less before and after the thermal acceleration test held at 90 ° C for 1000 hours. .   The retardation film according to claim 1, wherein the resin composition (C) is a resin composition having a positive intrinsic birefringence.   2. Re (447) / Re (590) <1 where Re (447) is an in-plane phase difference for light having a wavelength of 447 nm and Re (590) is an in-plane phase difference for light having a wavelength of 590 nm. The retardation film according to any one of 5 to 5.   The retardation film according to claim 1, wherein the (meth) acrylic resin (A) is a resin having a ring structure in the main chain. The retardation film according to claim 7, wherein the ring structure is a lactone ring structure represented by the following general formula (1).

(In the formula ^{(1), R 1, R} 2, R 3 are each independently a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, unsaturated aliphatic hydrocarbon group having 2 to 20 carbon atoms or carbon atoms, 6 to 20 aromatic hydrocarbon groups, wherein the alkyl group, the unsaturated aliphatic hydrocarbon group, and the aromatic hydrocarbon group are such that one or more of hydrogen atoms are a hydroxyl group, a carboxyl group, an ether group, and an ester. It may be substituted with at least one group selected from the group)