JP6508961B2 - Thermoplastic resin composition and optical film using the same - Google Patents

Description

  The present invention relates to a thermoplastic resin composition excellent in optical properties, heat resistance and mechanical strength, and an optical film comprising the thermoplastic resin composition.

  BACKGROUND ART Conventionally, (meth) acrylic polymers represented by polymethyl methacrylate (PMMA) are widely used in optical applications because they are excellent in optical transparency. For optical applications, in addition to use as a bulk body such as a lens, use as a resin film (optical film) composed of a thermoplastic resin containing the polymer is also common. In recent years, optical films have been increasingly used for image display devices such as liquid crystal displays (LCDs) and organic electroluminescent displays (OLEDs).

  Due to the design of the image display device, the optical film can not avoid the arrangement close to the heating element such as the power supply unit, the light emitting unit, and the circuit board. Therefore, the optical film is required to have heat resistance. Therefore, the heat resistance of the optical film can be improved by introducing a ring structure into the main chain of the polymer, or copolymerizing with a monomer having a ring structure located in the main chain when the polymer is formed. (See, for example, Patent Documents 1 to 3). However, the introduction of a ring structure tends to lower the mechanical strength such as flexibility and impact resistance.

  As a method of improving the mechanical strength of an optical film, it is known to mix an acrylic block copolymer with an acrylic resin (see, for example, Patent Documents 4 and 5).

JP, 2006-096960, A Unexamined-Japanese-Patent No. 2006-328334 Unexamined-Japanese-Patent No. 2007-31537 WO 2010/055798 Japanese Patent Application Publication No. 2012-514212

  However, the resin compositions described in Patent Documents 4 and 5 have insufficient heat resistance, and there is a problem that both mechanical strength and heat resistance can not be achieved.

  The present invention has been made in view of the above problems, and provides a thermoplastic resin composition which is excellent in optical properties and heat resistance and has an improved mechanical strength, and an optical film comprising the thermoplastic resin composition. The purpose is to

  The thermoplastic resin composition according to the present invention contains an acrylic polymer (A) having a ring structure in its main chain and an acrylic block copolymer (B) in order to solve the above-mentioned problems, and the mass ratio [ A] / [B] is 70/30 to 99.5 / 0.5.

  According to the said structure, a thermoplastic resin composition can improve mechanical strength, maintaining the optical characteristic and heat resistance of an acryl-type polymer (A). Therefore, according to the said structure, it is effective in the ability to provide the thermoplastic resin composition which was excellent in an optical characteristic and heat resistance, and which mechanical strength improved.

  The thermoplastic resin composition according to the present invention preferably has a glass transition temperature of 110 ° C. or higher.

  The acrylic polymer (A) preferably has in the main chain a ring structure which is at least one selected from the group consisting of a lactone ring structure, a glutarimide structure, and an N-substituted maleimide structure.

Moreover, it is preferable that the thermoplastic resin composition which concerns on this invention is 5.0 * 10 < ^-11 > (1 / Pa) or less of the absolute value of a stress optical coefficient.

  The optical film according to the present invention is characterized by comprising the thermoplastic resin composition according to the present invention in order to solve the above-mentioned problems.

  According to the above configuration, since the thermoplastic resin composition according to the present invention is provided, an optical film excellent in optical properties, heat resistance and mechanical strength can be provided.

  The optical film according to the present invention preferably has an internal haze of 1.0% or less.

  According to the said structure, the optical film excellent in transparency can be provided, and it can use suitably as an optical film.

  The optical film according to the present invention is preferably a stretched film.

  According to the above configuration, the effect of further improving the mechanical strength of the optical film is obtained.

  The optical film according to the present invention preferably has an in-plane retardation Re of 0 nm to 10 nm with respect to light having a wavelength of 589 nm, and a retardation Rth in the thickness direction of the light of −10 nm to 10 nm. Here, the refractive index in the slow axis direction in the film plane is nx, the refractive index in the fast axis direction in the film plane is ny, the refractive index in the film thickness direction is nz, and the film thickness d In this case, the in-plane retardation Re (nm) is a value defined by Re = (nx−ny) × d, and the thickness direction retardation Rth (nm) is Rth = d × {(( It is a value defined by nx + ny) / 2-nz}.

  According to the said structure, it can use suitably as a polarizer protective film in which the small phase difference near zero is calculated | required.

  The polarizer protective film according to the present invention is characterized by comprising the optical film according to the present invention in order to solve the above-mentioned problems.

  According to the above configuration, since the optical film according to the present invention is included, it is possible to provide a polarizer protective film excellent in optical characteristics, heat resistance and mechanical strength.

  Moreover, in order to solve the above-mentioned subject, a polarizing plate concerning the present invention is characterized by consisting of a light polarizer protective film concerning the above-mentioned present invention, and a light polarizer.

  According to the above configuration, since the polarizer protective film according to the present invention is included, it can be suitably used as a polarizing plate.

  Furthermore, an image display apparatus according to the present invention is characterized by including the polarizing plate according to the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the thermoplastic resin composition and optical film which were excellent in optical characteristics and heat resistance and whose mechanical strength was improved can be provided, and it can use for optical films, such as a polarizer protective film.

It is sectional drawing which shows typically an example of the polarizer protective film of this invention. It is sectional drawing which shows typically an example of the polarizing plate of this invention. It is a sectional view showing typically an example of an image display.

Hereinafter, the present invention will be described in detail. In the following description, unless stated otherwise, “%” means “mass%”, “part” means “mass part”, and “A to B” indicating a range is A or more and B or more. It shows that it is the following. Also, "(meth) acrylic acid" means acrylic acid or methacrylic acid.
[Acrylic polymer (A) having a ring structure in the main chain]
The acrylic polymer (A) contained in the thermoplastic resin composition of the present invention is not particularly limited as long as it is an acrylic polymer having a ring structure in its main chain.

  The acrylic polymer (A) having a ring structure in the main chain according to the present invention includes a structure and a ring structure formed by polymerizing a monomer or copolymer component of (meth) acrylic acid and a derivative thereof. And an acrylic polymer having as a structural unit. The content of the structure formed by polymerizing the monomer or copolymer component of (meth) acrylic acid and the derivative thereof in the acrylic polymer (A) is preferably 10% by mass or more, more preferably It is 30% by mass or more, more preferably 50% by mass or more, and particularly preferably 70% by mass or more. In addition, the content of the ring structure in the acrylic polymer (A) is, for example, 1 to 90% by mass, preferably 2 to 80% by mass, more preferably 3 to 70% by mass, and still more preferably 5 to 5%. It is 50% by mass. Furthermore, in the acrylic polymer (A), the total content of a structure and a ring structure formed by polymerizing a single or copolymer component of (meth) acrylic acid and a monomer that is a derivative thereof in the acrylic polymer (A) is preferably It is 50% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, and particularly preferably 90% by mass or more. The glass transition temperature (Tg) of PMMA is usually about 100 ° C., but the Tg of the acrylic polymer (A) can be, for example, 110 ° C. or more depending on the ring structure of the main chain.

  (Meth) acrylic acid and derivative units thereof are, for example, (meth) acrylic acids such as acrylic acid and methacrylic acid; alkylated (meth) acrylic acids such as crotonic acid; 2- (hydroxymethyl) acrylic acid, 2- (hydroxymethyl) acrylic acid Hydroxyalkylated (meth) acrylic acids such as (hydroxyethyl) acrylic acid; methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate ( T) butyl acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, benzyl (meth) acrylate, dicyclopentanyl (meth) acrylate, etc. (Meth) acrylic esters of (meth) acrylic acid such as dicyclopentanyloxyethyl Ether-bond derivative; (meth) acrylic acid chloromethyl, (meth) halogen introduction derivatives such as acrylic acid 2-chloroethyl; include; and hydroxy group-introduced derivatives. Examples of the hydroxy group-introduced derivatives include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2,3,4,5,6-pentahydroxyhexyl (meth) acrylate, (meth) (Meth) acrylic acid hydroxyalkyls such as acrylic acid 2,3,4,5-tetrahydroxypentyl; alkyl 2- (hydroxymethyl) acrylate (eg methyl 2- (hydroxymethyl) acrylate, 2- (hydroxy) Methyl) ethyl acrylate, isopropyl 2- (hydroxymethyl) acrylate, n-butyl 2- (hydroxymethyl) acrylate, t-butyl 2- (hydroxymethyl) acrylate, etc.), 2- (hydroxyethyl) acrylic acid Alkyl (eg, methyl 2- (hydroxyethyl) acrylate etc.) Include; Rokishiarukiru) alkyl acrylate. The acrylic polymer (A) according to the present invention may use only one of these structural units, or two or more of these may be used in combination. The acrylic polymer (A) preferably has a methyl methacrylate (MMA) unit, and in this case, the transparency and heat resistance of the resin are improved.

  The ring structure is, for example, a ring structure having an ester group, an imide group or an acid anhydride group.

  Examples of more specific ring structures include N-substituted maleimide structure, maleic anhydride structure, glutarimide structure, glutaric anhydride structure, lactone ring structure and the like, preferably N-substituted maleimide structure, glutarimide structure , Lactone ring structure. The acrylic polymer (A) having a ring structure in the main chain according to the present invention has at least one selected from the above ring structures, and may have two or more kinds.

  The acrylic polymer (A) having a ring structure in the main chain according to the present invention includes, for example, a (meth) acrylic acid derivative and a monomer having a ring structure located in the main chain when it is made a polymer. Alternatively, after forming an acrylic polymer, the cyclization reaction may be advanced to introduce a ring structure in the main chain of the polymer.

  The following formula (1) shows an N-substituted maleimide structure and a maleic anhydride structure.

R ¹ and R ² in Formula (1) are, independently of each other, 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 ³ is absent, and when X ¹ is a nitrogen atom, R ³ is a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, a cyclopentyl group, a cyclohexyl group, or a substituent Or a benzyl group which may have a substituent. More specifically, it is a unit formed by polymerization of each monomer such as N-methyl maleimide, N-cyclohexyl maleimide, N-phenyl maleimide, N-benzyl maleimide and the like. Among them, N-methyl maleimide, N-cyclohexyl maleimide, N-phenyl maleimide, and N-benzyl maleimide are preferable.

When X ¹ is a nitrogen atom, the ring structure shown in Formula (1) is an N-substituted maleimide structure. The acrylic polymer (A) having an N-substituted maleimide structure in the main chain can be formed, for example, by copolymerizing an N-substituted maleimide and a (meth) acrylic acid ester.

When X ¹ is an oxygen atom, the ring structure shown in Formula (1) is a maleic anhydride structure. The acrylic polymer (A) having a maleic anhydride structure in its main chain can be formed, for example, by copolymerizing maleic anhydride and (meth) acrylic acid ester.

  The following formula (2) shows a glutarimide structure and a glutaric anhydride structure.

R ⁴ and R ⁵ in Formula (2) are, independently of each other, 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 ⁶ is absent, and when X ² is a nitrogen atom, R ⁶ is a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, a cyclopentyl group, a cyclohexyl group, or a substituent Or a benzyl group which may have a substituent.

When X ² is a nitrogen atom, the ring structure shown in Formula (2) is a glutarimide structure. The glutarimide structure can be formed, for example, by imidizing a (meth) acrylic acid ester polymer with an imidizing agent such as methylamine, cyclohexylamine, aniline, toluidine or benzylamine.

When X ² is an oxygen atom, the ring structure shown in Formula (2) is a glutaric anhydride structure. The glutaric anhydride structure can be formed, for example, by intramolecular dealcoholization cyclocondensation of a copolymer of (meth) acrylic acid ester and (meth) acrylic acid.

  The lactone ring structure is shown in the following formula (3).

In Formula (3), R ⁷ , R ⁸ and R ⁹ are each independently a hydrogen atom or an organic residue in the range of 1 to 20 carbon atoms. The organic residue may contain an oxygen atom.

  The organic residue is, for example, an alkyl group having a carbon number of 1 to 20, such as methyl, ethyl or propyl; an unsaturated aliphatic carbon having a carbon number of 2 to 20, such as ethenyl or propenyl. Hydrogen group; aromatic hydrocarbon group having a carbon number of 6 to 20, such as phenyl group and naphthyl group; one of hydrogen atoms in the above alkyl group, the above unsaturated aliphatic hydrocarbon group and the above aromatic hydrocarbon group And at least one of the groups is a group substituted by at least one group selected from a hydroxyl group, a carboxyl group, an ether group and an ester group.

The lactone ring structure represented by the formula (3) is obtained, for example, by copolymerizing a monomer group containing methyl methacrylate (MMA) and methyl 2- (hydroxymethyl) acrylate (MHMA), It can be formed by dealcoholization cyclocondensation of adjacent MMA units and MHMA units in coalescence. At this time, R ⁷ is a hydrogen atom, and R ⁸ and R ⁹ are methyl groups.

  The acrylic polymer (A) having a ring structure in the main chain according to the present invention can be produced by a known method. The acrylic polymer (A) whose ring structure is a glutaric anhydride structure or a glutarimide structure can be produced, for example, by the method described in WO 2007/26659 or WO 2005/108438. The acrylic polymer (A) whose ring structure is a maleic anhydride structure or an N-substituted maleimide structure can be produced, for example, by the methods described in JP-A-57-153008 and JP-A-2007-31537. The acrylic polymer (A) whose ring structure is a lactone ring structure can be produced, for example, by the method described in JP-A-2006-96960, JP-A-2006-171464 or JP-A-2007-63541.

  The acrylic polymer (A) having a ring structure in the main chain according to the present invention may have a structural unit other than a (meth) acrylic acid ester unit and a (meth) acrylic acid unit, and such a configuration The unit is, for example, styrene, vinyl toluene, α-methylstyrene, α-hydroxymethylstyrene, α-hydroxyethylstyrene, acrylonitrile, methacrylonitrile, methallyl alcohol, allyl alcohol, ethylene, propylene, 4-methyl-1- It is a structural unit derived from monomers such as pentene, vinyl acetate, 2-hydroxymethyl-1-butene, methyl vinyl ketone, N-vinyl pyrrolidone, N-vinyl carbazole and the like. The said acrylic polymer (A) may have 2 or more types of these structural units.

  It is preferable that the weight average molecular weights (Mw) of styrene conversion by GPC measuring method of the acrylic polymer (A) which has ring structure in the principal chain which concerns on this invention are 3,000-1,000,000. If this weight average molecular weight is 3,000 or more, strength required as a polymer can be expressed. Moreover, if it is 1,000,000 or less, it can be set as a molded object by shaping | molding process. The weight-average molecular weight of the acrylic polymer (A) is more preferably 4,000 to 800,000, still more preferably 5,000 to 500,000, still more preferably 100,000 to 500, It is 000.

  It is preferable that molecular weight distribution (Mw / Mn) by the GPC measurement method of (A) of the acryl-type polymer which has ring structure in the principal chain which concerns on this invention is 1-10. The composition of the said acrylic polymer (A) can adjust molecular weight distribution as needed. The molecular weight distribution (Mw / Mn) is preferably 1.1 to 7.0, more preferably 1.2 to 5.0, and still more preferably 1.5 to 5.0, from the viewpoint of adjusting to the resin viscosity suitable for molding processing. It is 4.0.

The glass transition temperature (Tg) of the acrylic polymer (A) having a ring structure in the main chain according to the present invention is preferably 110 ° C. or more, more preferably 115 ° C. or more, and still more preferably 120 ° C. or more. If the Tg of the acrylic polymer (A) falls within this range, it is possible to increase the Tg of the resin composition and, consequently, the Tg of the optical film also becomes high. It can be made smaller. However, if the Tg of the acrylic polymer (A) is too high, there is a possibility that molding processing such as film molding or stretching may become difficult, so the Tg of the acrylic polymer (A) is 220 ° C. or less Is more preferably 200.degree. C. or less, still more preferably 180.degree. C. or less. Here, the glass transition temperature is a temperature at which a polymer molecule starts micro Brownian motion, and there are various measurement methods, but in the present invention, the starting point method is performed according to JIS K7121 by differential scanning calorimetry (DSC) It is defined as the temperature obtained in Although a plurality of glass transition temperatures may be observed, in the present invention, a main transition temperature having a larger heat absorption amount is adopted.
[Acrylic block copolymer (B)]
As the acrylic block copolymer (B) contained in the thermoplastic resin composition of the present invention, at least a polymer block obtained by polymerizing monomer components containing (meth) acrylic acid and derivatives thereof is used. There is no particular limitation as long as it is an acrylic block copolymer having one type, a polymer block (b1) mainly composed of methacrylic acid ester units and a polymer block (b2) mainly composed of acrylic acid ester units It is preferable to have at least one kind. More preferably, it is an acrylic block copolymer having a triblock represented by (b1)-(b2)-(b1) or (b2)-(b1)-(b2). Here, the molecular weight, the composition and the like of (b1) or (b2) located at both ends of the triblock body may be the same or may be different from each other.

  The molecular chain form of the acrylic block copolymer (B) according to the present invention is not particularly limited, and may be, for example, linear, branched, or radial. The structure of the said acryl-type block copolymer (B) is properly used according to required characteristics, such as a processing characteristic of a thermoplastic resin composition, and a mechanical characteristic. As a commercial item, Kuraray Co., Ltd. Clarity LA4285, LA2250 grade | etc., Are mentioned.

  In the acrylic block copolymer (B) according to the present invention, the polymer block (b1) mainly composed of methacrylic acid ester units is a polymer block mainly composed of methacrylic acid ester units. Examples of methacrylic acid esters for forming the polymer block (b1) include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, and methacrylic acid sec. -Butyl, tert-butyl methacrylate, amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, pentadecyl methacrylate, dodecyl methacrylate, isobornyl methacrylate, phenyl methacrylate, methacrylic Examples thereof include benzyl acid, phenoxyethyl methacrylate, 2-hydroxyethyl methacrylate, 2-methoxyethyl methacrylate and the like. Among these, from the viewpoint of improving the transparency and heat resistance, methacrylic acid such as methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, and isobornyl methacrylate Alkyl esters are preferred, and methyl methacrylate is more preferred. The polymer block (b1) may be composed of one of these methacrylic acid esters, or may be composed of two or more.

  In addition, as long as the object and effects of the present invention are not hindered, the polymer block (b1) is a methacrylic acid ester unit having a reactive group, for example, glycidyl methacrylic acid, allyl methacrylate, or other than methacrylic ester units. A polymerizable monomer unit, for example, the following acrylic acid ester, methacrylic acid, acrylic acid, aromatic vinyl compound, acrylonitrile, methacrylonitrile, a small amount of monomers such as olefin as a copolymerization component, preferably 20% by mass or less, more Preferably, 10 mass% or less may be contained.

  In the acrylic block copolymer (B) according to the present invention, the polymer block (b2) mainly composed of an acrylic ester unit is a polymer block mainly composed of an acrylic ester unit. As an acrylic ester for forming the polymer block (b2), for example, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec acrylic acid -Butyl, tert-butyl acrylate, amyl acrylate, isoamyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, pentadecyl acrylate, dodecyl acrylate, isobornyl acrylate, phenyl acrylate, acrylic Examples thereof include benzyl acid, phenoxyethyl acrylate, 2-hydroxyethyl acrylate, 2-methoxyethyl acrylate and the like. Among these, from the viewpoint of improving the flexibility, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, phenoxyethyl acrylate, 2-methoxy acrylate Preferred are acrylic acid alkyl esters such as ethyl, and more preferred are n-butyl acrylate and 2-ethylhexyl acrylate. The polymer block (b2) may be composed of one of these acrylic esters, or may be composed of two or more.

  In addition, the polymer block (b2) may be an acrylic ester unit having a reactive group, for example, glycidyl acrylate, allyl acrylate or an acrylic ester unit, as long as the object and effect of the present invention are not hindered. A polymerizable monomer unit of, for example, a monomer such as the above-mentioned methacrylic acid ester, methacrylic acid, acrylic acid, aromatic vinyl compound, acrylonitrile, methacrylonitrile or olefin may be contained as a copolymerization component. The amount of the acrylic acid ester unit or other polymerizable monomer unit having such a reactive group is preferably a small amount from the viewpoint of exhibiting the effect of the present invention, preferably 20% by mass or less, more preferably 10% by mass or less is there.

  The composition ratio of the polymer block (b1) mainly composed of methacrylic acid ester units constituting the acrylic block copolymer (B) according to the present invention and the polymer block (b2) mainly composed of acrylic acid ester units is 20 to 90% by mass of the block (b1) and 80 to 10% by mass of the block (b2), preferably 25 to 85% by mass of the block (b1) and 75 to 15% by mass of the block (b2), More preferably, the amount of the block (b1) is 30 to 70% by mass, and the amount of the block (b2) is 70 to 30% by mass. When the proportion of the block (b1) is less than 20% by mass, the compatibility with the acrylic polymer (A) tends to decrease, and when the proportion of the block (b2) is less than 10% by mass, the thermoplastic resin composition Mechanical strength such as bending resistance of the film comprising the

  Insofar as the objects and effects of the present invention are not interfered with, the acrylic block copolymer (B) comprises, as polymer blocks other than these polymer blocks (b1) and (b2), methacrylic acid ester units and You may have the polymer block (c) which has structural units other than an acrylic ester unit. The form of bonding between the polymer block (c) and the polymer block (b1) mainly composed of the above-mentioned methacrylic acid ester unit and the polymer block (b2) mainly composed of the acrylic ester unit is not particularly limited. , (B1)-((b2)-(b1)) n- (c), (c)-(b1)-((b2)-(b1)) n- (c), etc. (n is 1 And an integer of from 20 to 20).

  Examples of the structural unit of the polymer block (c) include olefins such as ethylene, propylene, 1-butene, isobutylene and 1-octene; conjugated diene compounds such as 1,3-butadiene, isoprene and myrcene; styrene, α- Aromatic vinyl compounds such as methylstyrene, p-methylstyrene and m-methylstyrene; vinyl acetate, vinyl pyridine, acrylonitrile, methacrylonitrile, vinyl ketone, vinyl chloride, vinylidene chloride, vinylidene fluoride, acrylamide, methacrylamide, ε- And caprolactone and valerolactone.

The acrylic block copolymer (B) according to the present invention may optionally have a functional group such as a hydroxyl group, a carboxyl group, an acid anhydride or an amino group in the molecular chain or at the molecular chain terminal. .

  The weight average molecular weight (Mw) in terms of styrene by the GPC measurement method of the acrylic block copolymer (B) according to the present invention is not particularly limited, but preferably 10,000 to 100,000, more preferably It is 30,000-80,000, More preferably, it is 50,000-70,000. If this weight average molecular weight is less than 10,000, sufficient melt tension can not be maintained in melt extrusion molding, and a good sheet-like molded product is difficult to obtain, and the breaking strength of the obtained sheet-like molded product, etc. The mechanical properties are inferior. On the other hand, when it is larger than 100,000, the viscosity of the molten resin becomes high, and foreign particles caused by fine bumps and dips and unmelted substance (polymeric polymer) are generated on the surface of the sheet-like molded product obtained by melt extrusion molding There is a tendency that it is difficult to obtain a good sheet-like molded product.

  The molecular weight distribution (Mw / Mn) of the acrylic block copolymer (B) according to the present invention as measured by GPC is preferably 1 to 10. The molecular weight distribution (Mw / Mn) is more preferably 1.1 to 7.0, further preferably 1.2 to 5.0, and still more preferably 1. from the viewpoint of adjusting the resin viscosity suitable for molding processing. 5 to 4.0.

  The glass transition temperature (Tg) of the acrylic block copolymer (B) according to the present invention is preferably -100 ° C or more and -10 ° C or less, more preferably -90 ° C or more and -20 ° C or less, and still more preferably -80 It is more than -30 degreeC.

There is no restriction | limiting in particular in the manufacturing method of the acryl-type block copolymer (B) which concerns on this invention, The method according to a well-known method is employable. For example, a method of living polymerizing a monomer which is a constituent unit of each block is generally used. As a method of such living polymerization, for example, in the presence of a mineral acid salt such as an alkali metal or alkaline earth metal salt using an organic alkali metal compound as a polymerization initiator described in Japanese Patent Publication No. 7-25859. A method of anionically polymerizing by the method, a method of anionic polymerization in the presence of an organic aluminum compound using an organic alkali metal compound as a polymerization initiator which is a method described in JP-A-11-335432, a method described in JP-A-6-93060 A method of polymerizing an organic rare earth metal complex as a polymerization initiator which is a method, Macromol. Chem. Phys. 201, pp. 1108 to 1114 (2000), which includes the method of radical polymerization in the presence of a copper compound using an α-halogenated ester compound as an initiator. Also, a method of producing a mixture containing the acrylic block copolymer (B) according to the present invention by polymerizing the monomers constituting each block using a polyvalent radical polymerization initiator or a polyvalent radical chain transfer agent Etc. Among these methods, in particular, since an acrylic block copolymer is obtained with high purity, and control of molecular weight and composition ratio is easy and economical, an organic alkali metal compound is used as a polymerization initiator. Anionic polymerization in the presence of an organoaluminum compound is recommended.
[Thermoplastic resin composition]
The thermoplastic resin composition of the present invention comprises an acrylic polymer (A) having a ring structure in the main chain and an acrylic block copolymer (B), and the mass ratio [A] / [B] is 70. There is no particular limitation as long as it is / 30 to 99.5 / 0.5. According to the above configuration, the thermoplastic resin composition can improve mechanical strength while maintaining the optical properties and heat resistance of the acrylic polymer (A), and preferably the mass ratio [A] / [B] is 85/15 to 99/1, more preferably, the mass ratio [A] / [B] is 90/10 to 99/1, and more preferably, the mass ratio [A] / [B] is 90/10 to 10 It is 98/2.

  The thermoplastic resin composition of the present invention is a range other than the acrylic polymer (A) having a ring structure in the main chain and the acrylic block copolymer (B) as long as the effects of the present invention are not impaired. It may contain a polymer.

  Other polymers include, for example, olefin polymers such as polyethylene, polypropylene, ethylene-propylene polymer, poly (4-methyl-1-pentene); halogen-containing polymers such as vinyl chloride and chlorinated vinyl resin Acrylic polymers such as polymethyl methacrylate; polystyrenes such as polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene block copolymer, etc .; polymer polyethylene terephthalate, Polybutylene terephthalate, polyester such as polyethylene naphthalate; Polyamide such as nylon 6, nylon 66, nylon 610, etc .; Polyacetal; Polycarbonate; Polyphenylene oxide; Polyphenylene sulfide; Teruketon; polysulfone; polyether sulfone; polyoxyethylene Penji alkylene; polyamideimide; polybutadiene rubber, rubber-like polymer such as ABS resin or ASA resin containing an acrylic rubber; and the like.

  The thermoplastic resin composition of the present invention may contain other additives as long as the effects of the present invention are not impaired. As other additives, for example, antioxidants such as hindered phenol type, phosphorus type and sulfur type; Stabilizers such as light resistance stabilizer, weather resistance stabilizer, heat stabilizer, etc. Reinforcing material such as glass fiber and carbon fiber UV absorbers; near infrared absorbers; flame retardants such as tris (dibromopropyl) phosphate, triallyl phosphate, antimony oxide, etc .; phase difference raising agents, phase difference reducing agents, phase difference stabilizers, etc .; Antistatic agents including surface-active agents of cationic, cationic and nonionic types; colorants such as inorganic pigments, organic pigments and dyes; organic fillers and inorganic fillers; resin modifiers; organic fillers and inorganic fillers; It can be mentioned. The content ratio of the other additives in the thermoplastic resin composition of the present invention is preferably in the range of 0 to 5% by mass, more preferably 0 to 2% by mass, and still more preferably 0 to 1% by mass.

  Examples of the ultraviolet absorber include benzophenone compounds, salicylate compounds, benzoate compounds, triazole compounds and triazine compounds. Examples of benzophenone compounds include 2,4-dihydroxybenzophenone, 4-n-octyloxy-2-hydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-n-octyloxy Benzophenone, bis (5-benzoyl-4-hydroxy-2-methoxyphenyl) methane, 1,4-bis (4-benzoyl-3-hydroxyphenone) -butane and the like can be mentioned. Examples of salicylicate compounds include p-t-butylphenyl salicylate and the like. Examples of benzoate compounds include 2,4-di-t-butylphenyl-3 ', 5'-di-t-butyl-4'-hydroxybenzoate and the like. Moreover, as a triazole type-compound, 2, 2'- methylene bis [4- (1, 1, 3, 3- tetramethyl butyl) -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-Tetrahydrophthalimidyl methyl) phenol, reaction product of methyl 3- (3- (2H-benzotriazol-2-yl) -5-t-butyl-4-hydroxyphenyl) propionate / polyethylene glycol 300 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-benzotriazole-2-) Le) -5- (1,1-dimethylethyl) -4-hydroxy -C7-9-side and straight chain alkyl esters. Furthermore, as the triazine compounds, 2-mono (hydroxyphenyl) -1,3,5-triazine compounds, 2,4-bis (hydroxyphenyl) -1,3,5-triazine compounds, 2,4,6- And 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- (2-hydroxy-4-butoxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-butoxy) Phenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-hexyloxyphenyl) -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- 4- (4-hydroxy-4-butoxyphenyl)) Me Xyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4-ethoxyphenyl) -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-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, 2,4,4,6 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-tris (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-oxopropane-2-) Ruoxy) 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, 2,4,6-tris (2-hydroxy-3-methyl-4-benzyloxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-ethoxy) Ethoxyphenyl) -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-methoxycarbonylpropyl) oxy Ciphenyl) -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 can be mentioned. Commercially available products include, for example, “Tinubin 1577”, “Tinubin 460”, “Tinubin 477” (manufactured by BASF Japan) “Adekastab LA-F70” (manufactured by ADEKA) as a triazine ultraviolet absorber, “Adekastab LA” as a triazole ultraviolet absorber -31 "(made by ADEKA) etc. are mentioned. These may be used alone or in combination of two or more.

  The method for preparing the thermoplastic resin composition of the present invention is not particularly limited, and the acrylic polymer (A) having a ring structure in the main chain and the acrylic block copolymer (B) are mixed by a known mixing method. It can be prepared. The mixing can be carried out, for example, by preblending with a mixer such as an omnimixer and then kneading the obtained mixture. In this case, the kneader is not particularly limited, and, for example, a known kneader such as an extruder such as a single screw extruder or a twin screw extruder or a pressure kneader can be used.

  Other polymers and additives may be mixed when mixing the acrylic polymer (A) having a ring structure in the main chain and the acrylic block copolymer (B), or in the main chain The acrylic polymer (A) and / or the acrylic block copolymer (B) having a ring structure may be mixed in advance and then mixed with the other polymer.

  110 degreeC or more is preferable, as for the glass transition temperature (Tg) of the thermoplastic resin composition of this invention, More preferably, it is 115 degreeC or more, More preferably, it is 120 degreeC or more. When the Tg of the thermoplastic resin composition is in this range, the Tg of the retardation film is also high, so that the rate of change in retardation under a high temperature environment can be reduced. However, if the Tg of the thermoplastic resin composition is too high, there is a possibility that molding processing such as film molding or stretching may become difficult, so the Tg of the thermoplastic resin composition is preferably 220 ° C. or less, and more preferably Preferably it is 200 degrees C or less, More preferably, it is 180 degrees C or less.

Moreover, it is preferable that the thermoplastic resin composition of this invention is 5.0 * 10 < ^-11 > (1 / Pa) or less of the absolute value of stress optical coefficient (Cr). The stress optical coefficient (Cr) means that the original film obtained by molding the resin composition is stretched at a temperature above its Tg to form a retardation film, and in that case, the stress σ applied to the original film for stretching is It is the slope of the change in retardation of the obtained retardation film with respect to the stress σ when it is changed. The stress optical coefficient (Cr) is measured at a temperature equal to or higher than the Tg of the resin composition, and thus is an indicator of how much retardation is developed in the film by the stretching of the original film. The absolute value of Cr is more preferably 4.0 × 10 ⁻¹¹ (1 / Pa) or less, and still more preferably 3.0 × 10 ⁻¹¹ (1 / Pa) or less. When the absolute value of Cr is 5.0 × 10 ⁻¹¹ (1 / Pa) or less, an optical film showing a small retardation even after stretching is obtained, and as a polarizer protective film for which a small retardation near zero is required It can be used suitably. In addition, since the fluctuation of the retardation in the optical film is reduced, the control of the retardation after stretching becomes easy.

Furthermore, the amount of foaming generated when the thermoplastic resin composition of the present invention is heated at 290 ° C. for 20 minutes is preferably 20 pieces / g or less, more preferably 10 pieces / g or less, still more preferably 5 pieces / g. g or less. When the amount of foaming generated when heated at 290 ° C. for 20 minutes is more than 20 pieces / g, the foaming phenomenon may occur when the thermoplastic resin is thermally processed, and the appearance of the molded product may be poor. In addition, the measurement of the amount of foaming shall be performed using the melt indexer prescribed | regulated to JIS-K7210. More specifically, the foaming amount is determined by filling the dried thermoplastic resin composition in a cylinder of a melt indexer and holding it at 290 ° C. for 20 minutes, and then extruding it into a strand and obtaining the top mark of the obtained strand The generated number of bubbles present between the line and the lower reference line is counted and represented by the number per 1 g of the thermoplastic resin composition.
[Optical film]
The optical film of the present invention can be obtained by forming the above-described thermoplastic resin composition into a film. Alternatively, a stretched film may be obtained by stretching.

  Examples of the film forming method include known film forming methods such as a solution casting method (solution casting method), a melt extrusion method, a calendar method, and a compression molding method. Among these, the solution casting method (solution casting method) and the melt extrusion method are preferable.

  Examples of the solvent used in the solution casting method (solution casting method) include chlorinated solvents such as chloroform and dichloromethane; aromatic solvents such as toluene, xylene, benzene, and mixed solvents thereof; methanol, ethanol, isopropanol Alcohol solvents such as n-butanol and 2-butanol; methyl cellosolve, ethyl cellosolve, butyl cellosolve, dimethylformamide, dimethyl sulfoxide, dioxane, cyclohexanone, tetrahydrofuran, acetone, ethyl acetate, diethyl ether; These solvents may be used alone or in combination of two or more.

  As an apparatus for performing the solution casting method (solution casting method), for example, a drum-type casting machine, a band-type casting machine, a spin coater and the like can be mentioned.

  The melt extrusion method includes a T-die method, an inflation method, etc., and the temperature (molding temperature) of melt extrusion molding of the film at that time is preferably in the range of 150 to 350 ° C., more preferably 200 to 300 ° C. Within the scope of

  According to the T-die method, a film wound on a roll can be obtained by winding up a film extruded from an extruder equipped with a T-die at its tip. At this time, the temperature and speed of winding can be controlled to add stretching (uniaxial stretching) in the extrusion direction of the film.

  When using an extruder for melt extrusion, the type of extruder is not particularly limited, and may be single-screw, twin-screw and multi-screw. The L / D value of the extruder (L is the length of the cylinder of the extruder, D is the inner diameter of the cylinder), in order to sufficiently plasticize the thermoplastic resin composition according to the present invention to obtain a good kneading state, Preferably it is 10 or more and 100 or less, more preferably 15 or more and 80 or less, and still more preferably 20 or more and 60 or less. When L / D value is less than 10, the said thermoplastic resin composition can not fully be plasticized, and a favorable kneading | mixing state may not be obtained. When the L / D value exceeds 100, shear heat generation is excessively applied to the thermoplastic resin composition, whereby the components contained in the thermoplastic resin composition are easily thermally decomposed.

  In this case, the set temperature of the cylinder is preferably 200 ° C. or more and 350 ° C. or less, more preferably 250 ° C. or more and 320 ° C. or less. When the set temperature is less than 200 ° C., the melt viscosity of the thermoplastic resin composition of the present invention becomes excessively high, and the productivity of the film is lowered. When the set temperature exceeds 350 ° C., components contained in the thermoplastic resin composition may be thermally decomposed.

  When using an extruder for melt extrusion molding, the shape of the extruder is not particularly limited. It is preferred that the extruder have one or more open vents. By using such an extruder, the decomposition gas can be sucked from the open vent. This reduces the amount of volatile components remaining in the obtained film. In order to suck decomposition gas from the open vent part, for example, the open vent part is put in a reduced pressure state. The degree of pressure reduction in this case is preferably 1.3 hPa or more and 931 hPa or less, more preferably 13.3 hPa or more and 798 hPa or less, in terms of the pressure (absolute pressure) of the open vent portion. When the pressure of the open vent portion is higher than 931 hPa, monomers generated by the decomposition of volatile components and / or components contained in the thermoplastic resin composition of the present invention tend to remain in the obtained film. On the other hand, it is industrially difficult to keep the pressure of the open vent lower than 1.3 hPa.

  In melt extrusion, the thermoplastic resin composition of the present invention, which is in a molten state, is preferably melt filtered using a polymer filter. Melt filtration removes foreign matter present in the thermoplastic resin composition. This reduces the amount of optical defects and appearance defects in the finally obtained optical film. Melt filtration at excessively high temperatures causes the resulting film to suffer from defects such as perforations, flow patterns and flow streaks. These disadvantages are particularly likely to occur during continuous forming of the film. Taking these into consideration, the temperature of melt extrusion molding is, for example, 200 ° C. or more and 350 ° C. or less in order to shorten the residence time of the composition in the polymer filter by lowering the melting temperature of the thermoplastic resin composition. Preferably it is 250 degreeC or more and 320 degrees C or less.

  The configuration of the polymer filter is not particularly limited. A polymer filter in which a large number of leaf disc type filters are disposed in the housing can be suitably used. As a filter medium of the leaf disk type filter, any of a type in which a metal fiber non-woven fabric is sintered, a type in which metal powder is sintered, a type in which several metal nets are laminated, or a hybrid type in which these are combined. The sintered type of metal fiber non-woven fabric is most preferred.

  The filtration accuracy of the polymer filter is not particularly limited. The filtration accuracy 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 retention time of the thermoplastic resin composition in the polymer filter becomes long, and the thermal deterioration of the thermoplastic resin composition becomes large. Also, the productivity of the film is reduced. If the filtration accuracy exceeds 15 μm, removal of foreign matter contained in the thermoplastic resin composition tends to be insufficient.

  The shape of the polymer filter is not particularly limited. The polymer filter has, for example, a plurality of resin flow openings and an inner flow type having a resin flow path in the center pole; the cross section contacts the inner circumferential surface of the leaf disc filter at a plurality of apexes or planes; It is an external flow type having a resin flow path on the outer surface. The use of the outer flow type is preferred because there are few retention points of the resin.

  The residence time of the thermoplastic resin composition of the present invention in the polymer filter is preferably 20 minutes or less, more preferably 10 minutes or less, and still more preferably 5 minutes or less. The inlet pressure of the polymer filter and the outlet pressure of the filter in melt filtration are, for example, 3 MPa or more and 15 MPa or less and 0.3 MPa or more and 10 MPa, respectively. The pressure loss in melt filtration (the pressure difference between the inlet pressure and the outlet pressure of the polymer filter) is preferably 1 MPa or more and 15 MPa or less. When the pressure loss is 1 MPa or less, deviation tends to occur in the flow path through which the thermoplastic resin composition passes through the polymer filter. The deviation of the flow path is the cause of deterioration of the quality of the obtained film. When the pressure drop exceeds 15 MPa, the polymer filter is easily broken.

  Melt filtration with a polymer filter may be performed at any time such as formation of the thermoplastic resin composition of the present invention other than melt extrusion molding.

  In melt-filtering the thermoplastic resin composition of the present invention, the pressure of the thermoplastic resin composition in the polymer filter is stabilized by installing a gear pump between the extruder and the polymer filter. preferable.

  The optical film of the present invention may be a stretched film by stretching. Stretching produces an effect of further improving the mechanical strength of the optical film.

  A conventionally known stretching method can be applied as a stretching method for obtaining the stretched film. For example, uniaxial stretching such as free-width uniaxial stretching, fixed-width uniaxial stretching, etc .; biaxial stretching such as sequential biaxial stretching, simultaneous biaxial stretching, etc .; shrink film is adhered to one side or both sides when stretching film; A birefringence film in which molecular groups oriented in the stretching direction and the thickness direction are mixed is formed by forming the laminate and subjecting the film to a shrinkage force in the direction orthogonal to the stretching direction by heat stretching treatment. And the like. Biaxial stretching is preferable in that mechanical strength such as folding resistance is improved. Furthermore, simultaneous biaxial stretching is preferable in that mechanical strength such as folding resistance in any two orthogonal directions in the film plane is improved. Examples of any two orthogonal directions in the plane include a direction parallel to the slow axis in the plane of the film and a direction perpendicular to the slow axis in the plane of the film. The stretching conditions such as the stretching ratio, the stretching temperature and the stretching speed may be appropriately set according to the desired retardation value and the desired mechanical strength, and the stretching conditions are not particularly limited.

  As an apparatus for performing drawing etc., for example, a roll drawing machine, a tenter type drawing machine, a tensile tester as a small experimental drawing apparatus, a uniaxial drawing machine, a sequential biaxial drawing machine, a simultaneous biaxial drawing machine, etc. may be mentioned. The stretched film according to the present invention can be obtained using any of these devices.

  The stretching temperature is preferably in the vicinity of the glass transition temperature of the film raw material polymer. Specifically, it is preferable to carry out in the range of (glass transition temperature -30) ° C to (glass transition temperature +50) ° C, more preferably (glass transition temperature -20) ° C to (glass transition temperature +20) ° C It is in the range, more preferably in the range of (glass transition temperature -10) ° C to (glass transition temperature +10) ° C. When the temperature is lower than (glass transition temperature -30) ° C, it is not preferable because a sufficient draw ratio can not be obtained. When the temperature is higher than (glass transition temperature + 50) ° C, it is not preferable because resin flow (flow) occurs and stable stretching can not be performed.

  The stretching ratio defined by the area ratio is preferably in the range of 1.1 to 25 times, more preferably in the range of 1.2 to 10 times, and still more preferably in the range of 1.3 to 5 times. If it is smaller than 1.1 times, it is not preferable because it does not lead to an improvement in mechanical strength accompanying stretching. If it is more than 25 times, it is not preferable because the effect on the increase in the draw ratio is reduced.

  When stretching in a certain direction, the stretching ratio in one direction is preferably in the range of 1.05 to 10 times, more preferably in the range of 1.1 to 5 times, and still more preferably 1.2 to 3 times. It takes place within the scope. If it is smaller than 1.05 times, it is not preferable because it does not lead to an improvement in mechanical strength accompanying stretching. If it is more than 10 times, the effect on the increase of the draw ratio becomes small, and breakage of the film may occur during drawing, which is not preferable.

  The stretching speed (one direction) is preferably in the range of 10 to 20,000% / min, more preferably in the range of 100 to 10,000% / min. If it is slower than 10% / min, it takes time to obtain a sufficient draw ratio, which is not preferable because the production cost is high. If it is earlier than 20,000% / min, it is not preferable because the stretched film may be broken or the like.

  After stretching, heat treatment (annealing) may be performed as needed to stabilize the optical properties and mechanical properties of the optical film.

  The thickness of the optical film such as the stretched film of the present invention is preferably in the range of 5 to 350 μm, more preferably in the range of 20 to 200 μm, and still more preferably in the range of 25 to 150 μm. If the film thickness is less than 5 μm, the mechanical strength is poor. When the film thickness is greater than 350 μm, it is disadvantageous for thinning the liquid crystal display device.

  An optical film such as the stretched film of the present invention has a high light transmittance. For example, the total light transmittance is preferably 85% or more, more preferably 90% or more, and still more preferably 91% or more.

  The optical film such as the stretched film of the present invention preferably has a haze of 3.0% or less. More preferably, it is 2.0% or less, more preferably 1.5% or less. Moreover, as for optical films, such as a stretched film of this invention, it is preferable that internal haze is 1.0% or less. More preferably, it is 0.8% or less. When the haze is more than 3.0% and the internal haze is more than 1.0%, the transparency is reduced and it is not suitable as an optical film.

  The optical film such as the stretched film of the present invention preferably has an in-plane retardation Re of 0 nm to 10 nm with respect to light having a wavelength of 589 nm, and a retardation Rth in the thickness direction of -10 nm to 10 nm. More preferably, Re is 0 nm or more and 5 nm or less, Rth is -5 nm or more and 5 nm or less, and still more preferably, Re is 0 nm or more and 3 nm or less, and Rth is -3 nm or more and 3 nm or less. The optical film of the present invention exhibiting such small in-plane retardation Re and thickness-direction retardation Rth is particularly suitable for use in an image display apparatus including an LCD, and has a good viewing angle characteristic and contrast. Characteristics are obtained.

  "Phase difference" is also called retardation. Here, the in-plane retardation (Re) is defined by Re = (nx−ny) × d, and the retardation in the thickness direction (Rth) is defined by Rth = d × {(nx + ny) / 2−nz} Ru. Here, nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the film plane in the direction perpendicular to nx, nz is the refractive index in the film thickness direction, and d is the film thickness (nm) . The slow axis direction is the direction in which the refractive index in the film plane is maximum.

  The optical film such as the stretched film of the present invention can be further controlled in optical properties by being used by being laminated with the same type optical material and / or different type optical material, in addition to the use by itself. Although it does not specifically limit as an optical material laminated | stacked in this case, For example, a polarizing plate, the stretching orientation film made from polycarbonate, the stretching orientation film made from cyclic | annular polyolefin etc. are mentioned.

  Various functional coating layers may be formed on the surface of the optical film such as the stretched film of the present invention, as necessary. The functional coating layer is, for example, an antistatic layer, a pressure-sensitive adhesive layer, an adhesive layer, an easily adhesive layer, an antiglare (non-glare) layer, an antifouling layer such as a photocatalyst layer, an antireflective layer, a hard coat layer, an ultraviolet shielding Layer, heat ray shielding layer, electromagnetic wave shielding layer, gas barrier layer.

The application of the optical film such as the stretched film of the present invention is not particularly limited. The optical film of the present invention is suitable for the following applications because of its small retardation, high transparency and high heat resistance. The application is, for example, a protective film for optics, specifically, a protective film for a substrate of various optical disks (VD, CD, DVD, MD, LD, etc.), a polarization used for a polarizing plate provided in an image display device such as LCD Child protective film. Viewing angle compensation film, light diffusion film, reflection film, antireflection film, antiglare film, brightness enhancement film, conductive film for touch panel, retardation film (wherein in-plane retardation Re with respect to light of wavelength 589 nm is 0 nm or more and 10 nm or less) The optical film of the present invention can be used as an optical film having a thickness direction retardation Rth of −10 nm or more and 10 nm or less. The optical film of the present invention is particularly suitable for use as a polarizer protective film.
[Polarizer Protective Film and Polarizing Plate]
An example of the polarizer protective film of this invention is shown in FIG. The polarizer protective film 1 shown in FIG. 1 is comprised by the optical film of this invention. That is, the polarizer protective film 1 contains an acrylic polymer (A) having a ring structure in the main chain and an acrylic block copolymer (B), and the mass ratio [A] / [B] is 70/30. There is no particular limitation as long as it is ~ 99.5 / 0.5.

  An example of the polarizing plate of this invention is shown in FIG. The polarizing plate 2 shown in FIG. 2 includes the polarizer protective film 1 of the present invention and the polarizer 3. The polarizer 3 is sandwiched by a pair of polarizer protective films 1. The polarizer 3 and the polarizer protective film 1 are in contact with each other.

  The polarizer 3 is not limited, and any appropriate polarizer can be adopted according to the function required for the polarizing plate 2. The polarizer 3 is, for example, a hydrophilic polymer film such as a polyvinyl alcohol (PVA) -based film, a partially formalized PVA-based film, or a partially saponified film of ethylene-vinyl acetate copolymer (EVA), iodine or two. A film obtained by adsorbing a dichroic substance such as a color dye and uniaxially stretching it; a polyene-based oriented film using a dehydrated product of PVA or a dehydrochlorinated product of polyvinyl chloride. Among them, a film in which a dichroic substance is adsorbed to a PVA-based film and uniaxially stretched is preferable as the polarizer 3. This polarizer exhibits a high polarization dichroic ratio. The thickness of the polarizer 3 is not limited and is generally about 1 to 80 μm.

  The polarizing plate 2 is typically manufactured by laminating the polarizer protective film 1 and the polarizer 3 via an adhesive layer. Specifically, for example, after applying an adhesive composition that becomes an adhesive layer after drying on any one surface selected from the polarizer 3 or the polarizer protective film 1, both are bonded and dried. The method of applying the adhesive composition is, for example, a roll method, a spray method, or an immersion method. When the adhesive composition contains a metal compound colloid, the adhesive composition is applied such that the thickness of the adhesive layer after drying is larger than the average particle size of the metal compound colloid particles. The drying temperature is typically 5 ° C. or more and 150 ° C. or less, preferably 30 ° C. or more and 120 ° C. or less. The drying time is typically 120 seconds or more, preferably 300 seconds or more.

  The polarizing plate of the present invention may include at least one polarizer protective film 1.

The polarizer protective film and the polarizing plate of the present invention are suitable for use in an image display device. The image display device is, for example, an electroluminescence (EL) display panel, a plasma display panel (PDP), a field emission display (FED), or an LCD. The LCD includes a liquid crystal cell and a polarizing plate disposed on at least one of the main surfaces of the liquid crystal cell. The polarizing plate of the present invention is suitable for the polarizing plate.
[Image display device]
The image display apparatus of the present invention comprises the polarizing plate of the present invention. The image display device is, for example, an EL display panel, a PDP, an FED, or an LCD.

  The configuration of the image display apparatus (image display apparatus of the present invention) including the polarizing plate of the present invention is not particularly limited, and members such as a power source, a backlight unit, and an operation unit may be appropriately provided as needed.

  An example of the structure of the image display part in the image display apparatus of this invention is shown in FIG. The image display unit 11 shown in FIG. 3 is an image display unit of an LCD, and includes a liquid crystal cell 4 and a pair of polarizing plates 2a and 2b disposed so as to sandwich the liquid crystal cell 4, the liquid crystal cell 4 and the polarizing plate 2a. , 2b, and a backlight 8 disposed on one side of the laminate. Each of the polarizing plates 2a and 2b includes the polarizers 3a and 3b, and a pair of polarizer protective films 1a, 1b, 1c, and 1d arranged to sandwich the polarizers. The liquid crystal cell 4 has a known structure, and includes, for example, a liquid crystal layer, a glass substrate, a transparent electrode, an alignment film, and the like. The backlight 8 has a known structure, and includes, for example, a light source, a reflection sheet, a light guide plate, a diffusion plate, a diffusion sheet, a prism sheet, a brightness enhancement film, and the like.

  In the image display unit 11, for example, at least one selected from the four polarizer protective films 1a to 1d is the optical film of the present invention. All polarizer protective films can be the optical film of the present invention. The image display unit 11 may further include an optional optical film such as a retardation film or an optical compensation film and an optical member, as necessary. The optical film may be the optical film of the present invention. The optical member may comprise the optical film of the present invention.

In addition, the specific method of each analysis quoted by description in embodiment mentioned above is demonstrated in the following Example.

Hereinafter, the present invention will be described in more detail by way of examples. The present invention is not limited to the following examples. First, evaluation methods of the polymer, the resin, and the optical film produced in this example will be shown.

[Constitution ratio of block of acrylic block copolymer]
The composition ratio (molar ratio) of each block in the acrylic block copolymer was determined by 1H-NMR (1H-nuclear magnetic resonance) measurement.
Device: Nuclear magnetic resonance device "AV-300M" manufactured by Bruker Biospin Co., Ltd.
Heavy solvent: deuterated chloroform [weight average molecular weight]
System: Tosoh GPC system HLC-8220
Measurement side column configuration-Guard column: Tosoh, TSKguardcolumn SuperHZ-L
-Separation column: Tosoh Corporation, TSKgel Super HZM-M 2 series connection in series reference column configuration-Reference column: Tosoh Corporation, TSKgel SuperH-RC
Development solvent: Chloroform (Wako Pure Chemical Industries, special grade)
Flow rate of developing solvent: 0.6 mL / min Standard sample: TSK standard polystyrene (Tosoh, PS-oligomer kit)
Column temperature: 40 ° C
[Glass transition temperature (Tg)]
The Tg of the polymer was determined by the starting point method in accordance with the definition of JIS K7121. Specifically, a differential scanning calorimeter (manufactured by RIGAKU, DSC-8230) is used to obtain about 10 mg of a sample from normal temperature to 200 ° C. (heating rate 20 ° C./min) in a nitrogen gas atmosphere. It evaluated from the DSC curve. As a reference, α-alumina was used.
[Stress optical coefficient Cr]
The thermoplastic resin composition was melt press-molded at 270 ° C. for 5 minutes using a manual heating press (IMC-180C type manufactured by Imoto Machinery Co., Ltd.) to produce an unstretched film (original film). The original film was cut out to 60 mm × 20 mm, and a weight was selected so that a stress of 1 N / mm ² or less was applied to the film when attached to the original film, which was attached to one of the short sides of the cut out original film . Next, the whole was accommodated in a constant temperature dryer (manufactured by As One, DOV-450A) maintained at Tg + 3 ° C of the original film, and the original film was left for 30 minutes. When housed in a constant temperature dryer, one side of the original film opposite to the side on which the weight is attached is fixed using a chuck, stress is applied to the original film by the weight, and the original film has a free end uniaxially in the vertical direction. It was made to be stretched. The distance between the chuck and the portion where the weight was attached was 40 mm. After about 30 minutes, the heater of the drier is turned off and the temperature in the drier is allowed to reach Tg-40 ° C of the original film, and then the film is taken out and its film length, thickness, in-plane for light of wavelength 589 nm The phase difference and the weight of the weight used were measured. The measurement was performed at three to four points while changing the weight of the weight. Next, the measured in-plane retardation was divided by the thickness of the film to determine the birefringence Δn (= nx-ny, measurement wavelength: 589 nm) of the film, and this was added to the y-axis and to the original film The stress σ (Pa) is determined from the weight of the weight, and this is plotted on the x-axis, and the slope of the straight line of the plot is calculated by the least squares method to obtain the stress optical coefficient Cr of the thermoplastic resin composition.
[Effervescent]
The dried thermoplastic resin composition is loaded into a cylinder of a melt indexer defined in JIS-K 7210, held at 290 ° C. for 20 minutes, and extruded into a strand, and the upper marked line of the obtained strand is obtained. The number of bubbles generated between the lower reference line and the lower reference line was counted and represented by the number per 1 g of the thermoplastic resin composition.
○: 0 to 5 Δ: 6 to 20 ×: 21 or more [film thickness]
The thickness of the film was measured using a Digimatic micrometer (manufactured by Mitutoyo). Samples for measuring and evaluating the physical properties of the film, including physical properties showing evaluation methods hereinafter, were obtained from the central part in the width direction of the film.
[Bending resistance]
The folding strength of the film was measured in accordance with JIS P8115. Specifically, a test film with a length of 90 mm and a width of 15 mm, the longitudinal direction of which is the MD direction, is allowed to stand in a state of 23 ° C. and 50% RH for 12 hours or more and used. Using BE-201 type), and test that the bending line is parallel to the flow direction of the film at the time of film formation under the condition of load 200g, and the number of times until the film of five samples breaks The average value was determined and used as the bending resistance in each direction. The average value of the bending resistance in each direction determined was taken as the bending resistance of the optical film.
[Phase difference]
The in-plane retardation (Re) of the film and the retardation in the thickness direction (Rth) at a wavelength of 589 nm were measured using KOBRA-WR manufactured by Oji Scientific Instruments. The phase difference (Rth) in the thickness direction is the average refractive index of the film measured with an Abbe refractometer, the film thickness d, the slow axis as the tilt central axis, and the incident angle 40 °, and the in-plane retardation ( Re) Retardation in the thickness direction (Rth), Retardation (Re (40 °)) measured by tilting at 40 ° with the slow axis as tilt axis, and three-dimensional refractive index nx, ny, nz values were obtained After, it asked from the following formula.
Thickness direction retardation Rth (nm) = d x {(nx + ny) / 2- nz}
[Total light transmittance]
The total light transmittance of the film was measured according to JIS K7361-1 using the above-mentioned turbidimeter.
[Haze]
The haze and the internal haze were measured using NDH-1001DP manufactured by Nippon Denshoku Industries Co., Ltd. When measuring the internal haze, 1,2,3,4-tetrahydronaphthalene (tetralin) was used.
Adhesive strength
The polarizing plate was fixed on a polypropylene resin plate with a double-sided tape. Subsequently, the adhesive strength was evaluated by the following five steps, using a cutter and putting a blade in the boundary between the polarizer and the protective film.
Evaluation 1: When the end of the film is held and peeled off, it peels easily.
Evaluation 2: When the cutter blade is inserted, it peels off.
Evaluation 3: Insert a blade and peel off when force is applied.
Evaluation 4: Even if it inserts a blade, only a small piece peels off.
Evaluation 5: The blade does not enter the interface.
[Moisture resistant]
The polarizing plate was cut into 2.5 × 5 cm and immersed in warm water at 60 ° C. for 4 hours, and then peeling at the boundary between the polarizer and the protective film was examined to evaluate moist heat resistance in the following three stages.
○: no peeling.
Fair: some peeling.
X: The entire surface is peeled off.
Production Example 1 Production of Acrylic Polymer (A-1) In a reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe and a nitrogen introducing pipe, 229.6 parts of methyl methacrylate (MMA), 2- (hydroxy) 33 parts of methyl methyl acrylate (MHMA), 248.6 parts of toluene, and 0.19 parts of n-dodecyl mercaptan were charged, and the temperature was raised to 105 ° C. while passing nitrogen through it. When refluxing accompanied by temperature rise is started, 0.28 parts of t-amyl peroxy isononanoate ("RUPEROX (registered trademark) 570" manufactured by Arkema Yoshitomi Co., Ltd.) is added as a polymerization initiator, and the above t-amyl pero is added. Solution polymerization is allowed to proceed under reflux at about 105 to 110 ° C. while 0.56 parts of oxyisononanoate and 12.4 parts of styrene are added dropwise over 2 hours, and after completion of the addition, aging is carried out for another 4 hours at the same temperature Did.

  Next, 0.21 part of stearyl phosphate ("Phoslex A-18" manufactured by Sakai Chemical Industry Co., Ltd.) is added to the obtained polymerization solution as a catalyst for the cyclization condensation reaction (cyclization catalyst), and about 90 to 110 The cyclization condensation reaction was allowed to proceed to form a lactone ring structure under reflux for 2 hours.

  Next, the resulting polymerization solution is passed through a multi-tubular heat exchanger heated to 240 ° C. to complete the cyclization condensation reaction, and the barrel temperature is 250 ° C., and one rear vent, four A fore-vent (referred to as first, second, third and fourth vents from the upstream side) and a side feeder between the third and fourth vents, and a leaf disk type polymer filter at the tip (filtration accuracy It was introduced at a processing speed of 31.2 parts / hour (resin amount conversion) into a vent type screw twin screw extruder (L / D = 52) in which 5 μm) was disposed. At that time, ion-exchanged water is injected from behind the second vent at an injection rate of 0.47 parts / hour, 0.66 parts of an ultraviolet absorber ("ADEKA STAB (registered trademark) LA-F70" manufactured by ADEKA) in toluene The solution dissolved in 1.23 parts is charged from behind the third vent at a charging rate of 0.59 parts / hour, and the ion-exchanged water is added from behind the fourth vent at a charging speed of 0.47 parts / hour. It was thrown in.

After completion of the volatilization, the resin composition in the hot-melted state left in the extruder is discharged from the tip of the extruder while filtering it with a polymer filter, and after passing through a equipped die, a filter with a pore diameter of 1 μm (Organo Co., Ltd. Product name: Micropore filter 1EU)) The strand is cooled by a water tank filled with cooling water kept at a temperature in the range of 30 ± 10 ° C, and introduced into a cutter (pelletizer), the main chain An acrylic polymer (A-1) having a lactone ring structure was obtained. The glass transition temperature of the acrylic polymer (A-1) was 122 ° C., and Cr was + 3.0 × 10 ⁻¹¹ (1 / Pa).

Production Example 2 Production of Acrylic Polymer (A-2) 320 parts of commercially available polymethyl methacrylate resin (Sumipex EX manufactured by Sumitomo Chemical Co., Ltd.) and 480 parts of toluene are introduced into an autoclave with a stirrer, and the reaction is carried out at 100 ° C. for 30 minutes. The mixture was heated to dissolve, and after cooling, 130 parts of a 40% methanol solution in methylamine was added, followed by heating at 200 ° C. for 30 minutes. Here, 3.0 parts of a UV absorber ("ADEKA STAB (registered trademark) LA-F70" manufactured by ADEKA) was uniformly dissolved. The resin solution thus obtained was dried under reduced pressure for 1 hour in a vacuum dryer at 200 ° C., crushed, and melt-kneaded using a twin-screw extruder set at 250 ° C. to form pellets into a glutarimide ring structure in the main chain The acrylic polymer (A-2) which has these was obtained. The glass transition temperature of the acrylic polymer (A-2) was 119 ° C., and Cr was + 0.7 × 10 ⁻¹¹ (1 / Pa).

Production Example 3 Production of Acrylic Polymer (A-3) In a reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe and a nitrogen introducing pipe, 325 parts of methyl methacrylate (MMA), N-phenylmaleimide (PMI) 25 parts, 15 parts of N-cyclohexyl maleimide (CHMI), 0.1 parts of n-dodecyl mercaptan, and 541 parts of toluene were charged, and the temperature was raised to 100 ° C. while passing nitrogen through it. When refluxing accompanied by the temperature rise is started, 0.3 parts of t-butylperoxyisopropyl carbonate (Kayacaron (registered trademark) bic-75 manufactured by Kayaku Akzo Co., Ltd.) as a polymerization initiator is added, and the above-mentioned t- Solution polymerization was allowed to proceed under reflux at about 100 to 115 ° C. while 0.3 part of butylperoxyisopropyl carbonate was added dropwise over 4 hours, and after completion of the addition, aging was carried out for 2 hours at the same temperature.

  Next, the obtained polymerization solution has a barrel temperature of 260 ° C., and is equipped with one rear vent and four forward vents (referred to as first, second, third and fourth vents from the upstream side), It was introduced at a processing speed of 31.2 parts / hour (resin amount conversion) into a vent type screw twin screw extruder (L / D = 52) in which a leaf disk type polymer filter (filtration accuracy 5 μm) was arranged at the tip. . At this time, a third vent is used at a charging rate of 0.59 parts / hour of a solution prepared by dissolving 0.66 parts of an ultraviolet absorber ("ADEKA STAB (registered trademark) LA-F 70" manufactured by ADEKA) in 1.23 parts of toluene. The ion exchange water was further injected from the back of the fourth vent at an injection rate of 0.47 parts / hour.

Subsequently, the resin composition in a hot-melted state left in the extruder is discharged from the tip of the extruder while filtering it with a polymer filter, pelletized by a pelletizer, and an acrylic heavy material having a maleimide ring structure in the main chain It obtained union (A-3). The glass transition temperature of the acrylic polymer (A-3) was 134 ° C., and Cr was + 1.0 × 10 ⁻¹¹ (1 / Pa).

Production Example 4 Production of Polarizer (G) A polyvinyl alcohol (PVA) film having a degree of saponification of 99% and a thickness of 75 μm is dipped in an aqueous solution consisting of 0.5% by mass of iodine and 5% by mass of potassium iodide did. Then, it was immersed in an aqueous solution containing 4% by mass of boric acid and 3% by mass of potassium iodide, stretched to 5 times, and then immersed in a 5% by mass aqueous solution of potassium iodide. Thereafter, the resultant was dried in an oven at 40 ° C. for 3 minutes to obtain a polarizer with a thickness of 30 μm.

Production Example 5 Production of Coating Composition (H-1) A polymerization apparatus equipped with a stirrer, thermometer, condenser, dropping funnel, nitrogen introducing pipe, 200 parts of toluene and 100 parts of isopropyl alcohol as a solvent, As a monomer, 80 parts of butyl methacrylate, 25 parts of BA, 75 parts of MMA and 20 parts of MAA were added, and the temperature was raised to 85 ° C. with stirring while introducing nitrogen gas.

  A mixture consisting of 0.005 part of 2,2'-azobisisobutyronitrile (trade name: ABN-R, manufactured by Nippon Hydrazine Industry Co., Ltd.) and 10 parts of toluene as a polymerization initiator was charged in portions over 7 hours. Furthermore, aging was carried out at 85 ° C. for 3 hours, and then cooled to room temperature to obtain a polymer having a weight average molecular weight of 90,000.

  Next, the temperature of the above flask is raised to 40 ° C., 20 parts of ethyleneimine is added dropwise over 1 hour, and the same temperature is maintained for 1 hour, then the internal temperature is raised to 75 ° C. and aging is carried out for 4 hours Did. The distillation apparatus was set in the polymerization apparatus, and heating was performed under reduced pressure to flow out isopropyl alcohol and unreacted ethyleneimine together out of the system to completely remove residual ethyleneimine. Finally, the non-volatile content was adjusted to 10% by mass with toluene to obtain an easily adhesive layer coating composition (H-1) containing an ethyleneimine-modified acrylic resin.

Production Example 6 Production of Adhesive (H-2) While introducing nitrogen gas into a polymerization apparatus equipped with a stirrer, thermometer, cooler, dropping funnel, nitrogen introducing pipe, 1,4-butanediol 367 .2 parts, 166 parts of isophthalic acid and 0.05 parts of dibutyltin oxide were melted while being heated and stirred, and a condensation reaction was carried out at 200 ° C for 8 hours until the acid value became 1.1. After cooling to 120 ° C., 584 parts of adipic acid and 268 parts of 2,2-dimethylol propionic acid are added, the temperature is raised again to 170 ° C., and the reaction is performed for 23 hours, and the hydroxyl value is 102.0, the acid value is 93. 5 polyester polyols were obtained. 55 parts of the obtained polyester is dewatered at 100 ° C. under reduced pressure, then cooled to 60 ° C., 6.58 parts of 1,4-butanediol is added, sufficiently stirred and mixed, and then hexamethylene diisocyanate 35. 17 parts were added and heated at 100 ° C. and reacted at this temperature for 4.5 hours to obtain an NCO-terminated urethane prepolymer. After completion of the reaction, the reaction solution was cooled to 40 ° C. and diluted with 96.75 parts of acetone to obtain a prepolymer solution. The prepolymer solution was gradually poured into an aqueous amine solution obtained by previously dissolving 7.04 parts of piperazine and 10.19 parts of triethylamine in 245.19 parts of water, and chain elongation and neutralization were simultaneously performed. After removing acetone from this reaction product at 50 ° C. under reduced pressure, water is added to make an aqueous dispersion of polyester-based ionomer type urethane resin having a nonvolatile content of 30%, viscosity 60 mPa · s / 25 ° C., pH 7.1. Obtained. An adhesive (H-2) having a non-volatile content of 20% by dispersing 20 parts of the obtained aqueous dispersion of polyester ionomer type urethane resin and 1.2 parts of a self-emulsifying type polyisocyanate in 14.8 parts of deionized water I got
Example 1
Acrylic triblock weight of 97.5 parts of the acrylic polymer (A-1) obtained in Production Example 1 and methyl methacrylate (MMA) / butyl acrylate (BA) = 55/45 (mol / mol) By dry blending 2.5 parts of combined (B-1, MMA / BA / MMA), melt kneading at a barrel temperature of 260 ° C. using a twin screw extruder having a 20 mmφ screw, and cutting with a pelletizer, Pellets of a resin composition (D-1) of an acrylic polymer having a ring structure in the main chain and an acrylic block copolymer were obtained. The glass transition temperature of the resin composition (D-1) was 122 ° C., and Cr was + 2.8 × 10 ⁻¹¹ (1 / Pa). Moreover, the foamability evaluation was ○.
(Example 2)
Main chain in the same manner as in Example 1 except that 95.0 parts of the acrylic polymer (A-1) obtained in Production Example 1 and 5.0 parts of the acrylic triblock polymer (B-1) are used. Pellets of a resin composition (D-2) of an acrylic polymer having a ring structure and an acrylic block copolymer were obtained. The glass transition temperature of the resin composition (D-2) was 122 ° C., and Cr was + 2.6 × 10 ⁻¹¹ (1 / Pa). Moreover, the foamability evaluation was ○.
(Example 3)
Main chain in the same manner as in Example 1 except that 90.0 parts of the acrylic polymer (A-1) obtained in Production Example 1 and 10.0 parts of the acrylic triblock polymer (B-1) are used. Pellets of a resin composition (D-3) of an acrylic polymer having a ring structure and an acrylic block copolymer were obtained. The glass transition temperature of the resin composition (D-3) was 122 ° C., and Cr was + 2.0 × 10 ⁻¹¹ (1 / Pa). Moreover, the foamability evaluation was ○.
(Example 4)
Main chain in the same manner as in Example 1 except that 97.5 parts of the acrylic polymer (A-2) obtained in Production Example 2 and 2.5 parts of the acrylic triblock polymer (B-1) are used. Pellets of a resin composition (D-2) of an acrylic polymer having a ring structure and an acrylic block copolymer were obtained. The glass transition temperature of the resin composition (D-4) was 119 ° C., and Cr was + 0.8 × 10 ⁻¹¹ (1 / Pa). Moreover, the foamability evaluation was ○.
(Example 5)
Main chain in the same manner as in Example 1 except that 97.5 parts of the acrylic polymer (A-3) obtained in Production Example 3 and 2.5 parts of the acrylic triblock polymer (B-1) are used. Pellets of a resin composition (D-5) of an acrylic polymer having a ring structure and an acrylic block copolymer were obtained. The glass transition temperature of the resin composition (D-5) was 134 ° C., and Cr was + 1.0 × 10 ⁻¹¹ (1 / Pa). Moreover, the foamability evaluation was ○.
(Example 6)
Acrylic triblock weight of 97.5 parts of the acrylic polymer (A-1) obtained in Production Example 1 and methyl methacrylate (MMA) / butyl acrylate (BA) = 35/65 (mol / mol) A resin composition of an acrylic polymer having a ring structure in the main chain and an acrylic block copolymer in the same manner as in Example 1 except that the combined amount (B-2, MMA / BA / MMA) is 2.5 parts. The pellet of thing (D-6) was obtained. The glass transition temperature of the resin composition (D-6) was 122 ° C., and Cr was + 2.8 × 10 ⁻¹¹ (1 / Pa). Moreover, the foamability evaluation was ○.
(Comparative example 1)
In the same manner as in Example 1 except that 95.0 parts of the acrylic polymer (A-1) obtained in Production Example 1 and 5.0 parts of polymethyl methacrylate resin (Sumipex EX manufactured by Sumitomo Chemical Co., Ltd.) are used. Pellets of a resin composition (D-7) of an acrylic polymer having a ring structure in its main chain and a polymethyl methacrylate resin were obtained. The glass transition temperature of the resin composition (D-7) was 118 ° C., and Cr was + 1.0 × 10 ⁻¹¹ (1 / Pa). In addition, the foamability evaluation was Δ.
(Comparative example 2)
An acrylic polymer and an acrylic block copolymer are the same as in Example 1 except that the commercially available polymethyl methacrylate resin (Sumipex EX manufactured by Sumitomo Chemical Co., Ltd.) and the acrylic triblock polymer (B-1) are used in 2.5 parts. Pellets of a resin composition (D-8) with a polymer were obtained. It was 105 degreeC when the glass transition temperature of a resin composition (D-8) was measured, and Cr was -15.0 * 10 < ^-11 > (1 / Pa). The foamability evaluation was x.

  The results are summarized in Table 1.

As shown in Table 1, by using the acrylic polymer having a ring structure in the main chain and the acrylic block copolymer in the combination of Examples 1 to 6, the phase difference expression is small, and foaming due to heating hardly occurs. That is, it was possible to obtain a thermoplastic resin composition suitable for melt molding at high temperature.
(Example 7)
A pellet of the resin composition (D-1) prepared in Example 1 was melt-extrusion molded using a single-screw extruder (cylinder diameter 20 mm) under the following conditions, and a 160 μm-thick unstretched film (original film) Was produced. The unstretched film obtained is in the form of a roll, and the width direction of the roll in the film is taken as the TD direction, and the stretching direction of the roll (the direction perpendicular to the TD direction in the film plane) is taken as the MD direction.

Cylinder temperature: 240 ° C
Die: coat hanger type, width 150 mm, temperature 250 ° C
Casting: Two rolls with gloss, first and second rolls held at 115 ° C. The unstretched film is formed by solidifying the resin composition extruded from the T-die on the casting roll, but the unstretched film The condition of the surface of the casting roll was visually confirmed after the production of No. 2. However, no deposit was observed. The obtained original film consisting of D-1 is cut out to 97 mm × 97 mm, and then (glass transition temperature +23 of resin composition D-1) using a sequential biaxial stretching machine (manufactured by Toyo Seiki Seisakusho, X-6S) 1) Stretch the first stage so that it is 2.0 times in the longitudinal direction (MD direction) at a speed of 300% / min at a temperature of ° C, then go straight with the first stage at a speed of 300% / min The second stage stretching was performed so as to be 2.0 times in the direction (TD direction). At this time, it did not shrink | contract in the direction orthogonal to extending | stretching.
After stretching, the film was quickly taken out of the test apparatus and cooled to obtain a biaxially stretched film (F-1) having a thickness of 40 μm. The in-plane retardation Re of the obtained stretched film (F-1) is 0.8 nm, the retardation Rth in the thickness direction is 1.2 nm, the total light transmittance is 92.2%, and the haze is 0.6%. And the internal haze was 0.1%. In addition, the bending strength was 677 times.
(Example 8)
The pellet of the resin composition (D-2) produced in Example 2 was melt-extruded in the same manner as in Example 7 to produce an unstretched film (original film) having a thickness of 160 μm. Then, the original film consisting of D-2 was biaxially stretched in the same manner as in Example 7 to obtain a 40 μm thick biaxially stretched film (F-2). The in-plane retardation Re of the obtained stretched film (F-2) is 0.6 nm, the retardation Rth in the thickness direction is 1.0 nm, the total light transmittance is 92.0%, and the haze is 0.8%. There was an internal haze of 0.4%. Moreover, the bending strength was 796 times.
(Example 9)
The pellet of the resin composition (D-3) produced in Example 3 was melt-extruded in the same manner as in Example 7 to produce an unstretched film (original film) having a thickness of 160 μm. Subsequently, the original film consisting of D-3 was biaxially stretched in the same manner as in Example 7 to obtain a 40 μm thick biaxially stretched film (F-3). The in-plane retardation Re of the obtained stretched film (F-3) is 0.2 nm, the retardation Rth in the thickness direction is 0.4 nm, the total light transmittance is 91.2%, and the haze is 1.4%. There was an internal haze of 0.6%. Moreover, the bending strength was 1190 times.
(Example 10)
The pellet of the resin composition (D-4) produced in Example 4 was melt-extruded in the same manner as in Example 7 to produce an unstretched film (original film) having a thickness of 160 μm. Subsequently, the original film consisting of D-4 was subjected to biaxial stretching in the same manner as in Example 7 to obtain a biaxially stretched film (F-4) having a thickness of 40 μm. The in-plane retardation Re of the obtained stretched film (F-4) is 0.3 nm, the retardation Rth in the thickness direction is 1.0 nm, the total light transmittance is 92.2%, and the haze is 0.6%. And the internal haze was 0.1%. In addition, the bending strength was 701 times.
(Example 11)
The pellet of the resin composition (D-5) produced in Example 5 was melt-extruded in the same manner as in Example 7 to produce an unstretched film (original film) having a thickness of 160 μm. Then, the original film consisting of D-5 was biaxially stretched in the same manner as in Example 7 to obtain a 40 μm thick biaxially stretched film (F-5). The in-plane retardation Re of the obtained stretched film (F-5) is 0.4 nm, the retardation Rth in the thickness direction is 0.8 nm, the total light transmittance is 92.2%, and the haze is 0.6%. And the internal haze was 0.1%. In addition, the bending strength was 552 times.
(Example 12)
The pellet of the resin composition (D-6) produced in Example 6 was melt-extruded in the same manner as in Example 7 to produce an unstretched film (original film) having a thickness of 160 μm. Then, the original film consisting of D-6 was biaxially stretched in the same manner as in Example 7 to obtain a 40 μm thick biaxially stretched film (F-6). The in-plane retardation Re of the obtained stretched film (F-6) is 0.8 nm, the retardation Rth in the thickness direction is 1.3 nm, the total light transmittance is 91.8%, and the haze is 0.9%. There was an internal haze of 0.2%. In addition, the bending strength was 762 times.
(Comparative example 3)
The pellet of the resin composition (D-7) produced in Comparative Example 1 was melt-extruded in the same manner as in Example 7 to produce an unstretched film (original film) having a thickness of 160 μm. Then, the original film consisting of D-7 was subjected to biaxial stretching in the same manner as in Example 7 to obtain a biaxially stretched film (F-7) having a thickness of 40 μm. The in-plane retardation Re of the obtained stretched film (F-7) is 0.4 nm, the retardation Rth in the thickness direction is 0.7 nm, the total light transmittance is 91.8%, and the haze is 0.9%. There was an internal haze of 0.4%. Moreover, the bending strength was 510 times.
(Comparative example 4)
The pellet of the acrylic polymer (A-1) having a ring structure in the main chain prepared in Production Example 1 is melt-extruded in the same manner as in Example 7 to produce an unstretched film (original film) having a thickness of 160 μm. did. Subsequently, the original film consisting of A-1 was biaxially stretched in the same manner as in Example 7 to obtain a 40 μm thick biaxially stretched film (F-8). The in-plane retardation Re of the obtained stretched film (F-8) is 0.6 nm, the retardation Rth in the thickness direction is 1.0 nm, the total light transmittance is 92.3%, and the haze is 0.4%. And the internal haze was 0.1%. Moreover, the bending strength was 505 times.
(Comparative example 5)
The pellet of the acrylic polymer (A-2) having a ring structure in the main chain prepared in Production Example 2 is melt-extruded in the same manner as in Example 7 to produce an unstretched film (original film) having a thickness of 160 μm. did. Then, the original film consisting of A-2 was biaxially stretched in the same manner as in Example 7 to obtain a 40 μm thick biaxially stretched film (F-9). The in-plane retardation Re of the obtained stretched film (F-9) is 0.6 nm, the retardation Rth in the thickness direction is 0.8 nm, the total light transmittance is 92.2%, and the haze is 0.4%. And the internal haze was 0.1%. In addition, the bending strength was 526 times.
(Comparative example 6)
The pellet of the acrylic polymer (A-3) having a ring structure in the main chain prepared in Production Example 3 is melt-extruded in the same manner as in Example 7 to produce an unstretched film (original film) having a thickness of 160 μm. did. Then, the original film consisting of A-3 was biaxially stretched in the same manner as in Example 7 to obtain a biaxially stretched film (F-10) having a thickness of 40 μm. The in-plane retardation Re of the obtained stretched film (F-10) is 0.5 nm, the retardation Rth in the thickness direction is 0.9 nm, the total light transmittance is 92.3%, and the haze is 0.5%. And the internal haze was 0.1%. In addition, the bending strength was 440 times.
(Comparative example 7)
Pellets of the resin composition (D-8) produced in Comparative Example 2 were melt-extruded in the same manner as in Example 7 to produce an unstretched film (original film) having a thickness of 160 μm, and then the obtained original film was carried out The biaxial stretching was performed in the same manner as in Example 7 to obtain a biaxially stretched film (F-11) having a thickness of 40 μm. The in-plane retardation Re of the obtained stretched film (F-11) is 5.3 nm, the retardation Rth in the thickness direction is −11.0 nm, the total light transmittance is 92.0%, and the haze is 0.8% The internal haze was 0.4%. Moreover, the bending strength was 885 times.

  The above results are shown in Table 2.

  As shown in Table 2, it was found that the film obtained in the present example was well balanced in strength with the excellent optical properties such as low haze and low retardation.

  In Examples 7 to 9 and 12, the haze resistance, the internal haze, the Re, and the Rth were low, and the bending resistance was improved relative to Comparative Example 4 while satisfying the requirements as an optical film. In Example 10, the haze resistance, the internal haze, the Re, and the Rth were low, and the bending resistance was improved relative to Comparative Example 5 while satisfying the requirements as an optical film. In Example 11, the haze resistance, the internal haze, the Re, and the Rth were low, and the bending resistance was improved relative to Comparative Example 6 while satisfying the requirements as an optical film. On the other hand, a film made of a resin composition using a polymethyl methacrylate resin as in Comparative Example 3 and Comparative Example 7 was not effective for improving the bending resistance while maintaining the optical properties.

(Example 13) Production of Polarizing Plate Obtained in Production Example 5 on the surfaces of the stretched film F-1 obtained in Example 7 and the stretched film F-2 obtained in Example 8 bonded to the respective polarizers. The easy adhesion layer coating composition H-1 was applied by a bar coater and placed in a hot air dryer at 100 ° C. to remove the solvent and dry the composition. Next, the adhesive H-2 obtained in Production Example 6 is applied, and the extra adhesive is extruded using a pressure roller such that the polarizer (G) obtained in Production Example 4 is sandwiched between these films. While being bonded by wet lamination. The obtained laminated film was dried in a hot air drier at 60 ° C. for 10 minutes. Subsequently, it was dried and cured in an oven at 50 ° C. for 15 hours to produce a polarizing plate. The thickness of the adhesive layer after drying was 50 nm. The adhesiveness and the heat and moisture resistance were evaluated on the obtained polarizing plate. The evaluation results are shown in Table 3.

(Examples 14 to 20, Comparative Example 8) Production of Polarizing Plate In the same manner as in Example 13, a combination of stretched films shown in Table 3 in which one side of the polarizer (G) is A side and the other side is B side. Made a polarizer. The evaluation results are shown in Table 3.

  As shown in Table 3, the polarizing plate of Examples 13-20 was able to implement | achieve the outstanding adhesive strength and the heat-and-moisture resistance. The polarizing plate of Comparative Example 8 was poor in heat and humidity resistance. In addition, the polarizer protective film bonded to the A surface of the polarizer is all the polarizer protective film of the present invention, and the acrylic polymer constituting each film has a ring structure in the main chain, so The polarizing plates prepared in Examples 13 to 20 have high heat resistance and optical properties.

  According to the present invention, the mass ratio [A] / [B] of the acrylic polymer (A) having a ring structure in the main chain and the acrylic block copolymer (B) is 70/30 to 99.5 / 0. The thermoplastic resin contained in P.5 has excellent optical properties and heat resistance, and can improve mechanical strength.

  Therefore, it can be suitably used for applications requiring optical properties, heat resistance, mechanical strength, such as optical films such as a polarizer protective film, and further, various image display devices (liquid crystal display devices, organic EL display Equipment, PDP, etc.).

DESCRIPTION OF SYMBOLS 1, 1a, 1b, 1c, 1d Polarizer protective film 2, 2a, 2b Polarizer 3, 3a, 3b Polarizer 4 Liquid crystal cell 8 Backlight 11 Image display apparatus

Claims (9)

A thermoplastic resin composition comprising an acrylic polymer (A) having a ring structure in the main chain and an acrylic block copolymer (B), and an acrylic polymer (A) having a ring structure in the main chain The mass ratio [A] / [B] of the acrylic block copolymer (B) is 70/30 to 99.5 / 0.5, and the absolute value of the stress optical coefficient is 5.0 × 10 ⁻¹¹ (1 / Pa) Ri der hereinafter the ring structure, a lactone ring structure is at least one selected from the group consisting of glutarimide structure, and N- substituted maleimide structure, the thermoplastic having a glass transition temperature of 110 ° C. or higher Resin composition.
However, the acrylic polymer (A) having a ring structure in the main chain excludes the acrylic block copolymer.   The content of the structure formed by polymerizing a monomer of a (meth) acrylic acid and a derivative thereof monomer or copolymer component in the acrylic polymer (A) having a ring structure in the main chain is 30% by mass or more The thermoplastic resin composition according to claim 1, which is   The acrylic block copolymer (B) has at least one polymer block (b1) containing a methacrylic acid ester unit and at least one polymer block (b2) containing an acrylic acid ester unit. The thermoplastic resin composition as described in 1 or 2.   An optical film comprising the thermoplastic resin composition according to any one of claims 1 to 3.   The optical film according to claim 4, which is a stretched film.   The optical film according to claim 4 or 5, wherein an in-plane retardation Re with respect to light having a wavelength of 589 nm is 0 nm or more and 10 nm or less, and a retardation Rth in the thickness direction with respect to the light is -10 nm or more and 10 nm or less.
[The refractive index in the slow axis direction in the film plane is nx, the refractive index in the fast axis direction in the film plane is ny, the refractive index in the film thickness direction is nz, and the film thickness is d Sometimes, the in-plane retardation Re (nm) is a value defined by Re = (nx−ny) × d, and the thickness direction retardation Rth (nm) is Rth = d × {(nx + ny) It is a value defined by / 2- nz}. ]   The polarizer protective film which consists of an optical film in any one of Claims 4-6.   A polarizing plate comprising the polarizer protective film according to claim 7 and a polarizer.   The image display apparatus provided with the polarizing plate of Claim 8.

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