JP2009053492A - Laminated film and polarizing plate with optical compensation layer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated film which is suitable for protection use of a polarizer having retardation, which has a simple manufacturing process and which is suitable as an optical film, and to provide a polarizing plate having retardation. <P>SOLUTION: The laminated film has at least a layer A consisting of an acrylic resin and a layer B, consisting of one or more kinds from among polyamide, polyimide, polyester, polyether ketone, polyamideimide and polyesterimide and satisfies conditions (i) to (iv), at the same time, where (i): in-plane retardation Re(a) of the layer A is 5 nm or smaller, thickness direction retardation Rth(a) is ≥-5 nm and ≤5 nm, (ii) a photoelastic coefficient of the layer A is smaller than 5.0×10<SP>-12</SP>Pa<SP>-1</SP>, (iii) formula: ¾Re(a')-Re(a)¾<5 (nm) is satisfied, when Tg denotes the glass transition temperature of the acrylic resin, constituting the layer A and Re(a') denotes in-plane retardation, when it is stretched to 1.5 times, at Tg-10°C and (iv): the thickness direction retardation Rth(b) of the layer B satisfies the formula: ¾Rth(b)¾>¾Rth(a)¾×50. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a laminated film suitable for optical applications, and a polarizing plate with an optical compensation layer using the same.

  Various optical films are used in liquid crystal display devices for the purpose of optical compensation. For example, a retardation plate that satisfies the following condition (1) is disposed between a liquid crystal cell and a polarizing plate for viewing angle compensation of the liquid crystal display device.

nx ≧ ny> nz (1)
(Nx, ny, and nz are those when the direction showing the maximum refractive index in the film plane is the x direction, the direction perpendicular to the x direction in the film plane is the y direction, and the film thickness direction is the z direction. Represents the refractive index in the direction.)
Such a retardation plate is generally used by stretching a polymer film, but recently, a solution of a polymer such as polyamide, polyimide, polyester, polyetherketone, polyamideimide and polyesterimide, A method of applying an optical film by applying to a substrate having a smooth surface and evaporating and removing the solvent of the solution is used (Patent Documents 1 and 2). When the substrate is an inorganic substrate such as a SUS belt, copper thin plate, Si wafer, or an organic substrate such as PET, the substrate cannot be used for a liquid crystal display device. It was necessary to transfer the optical film to the like.

Moreover, the method of controlling a three-dimensional birefringence by apply | coating to organic base materials, such as TAC (triacetylcellulose), and extending | stretching a coating film | membrane with a base material is disclosed (patent document 3). However, since this method produces a phase difference in the TAC by stretching, in order to accurately measure the phase difference of only the coating film, it can be transferred to a coating film alone or to a film that does not develop a phase difference. It was necessary to measure.
JP 2004-0708203 A Special table 2000-511296 JP 2005-331773 A

  An object of the present invention is to provide a laminated film comprising at least a retardation and a layer having a small change in birefringence due to stress and a layer exhibiting a phase difference, and an optical compensation layer, which are suitable for optical use, particularly for protecting a polarizer with retardation. The object is to provide an attached polarizing plate.

  The present invention for solving the above problems has the following features.

  [1] A layer A containing an acrylic resin and a layer B containing at least one polymer selected from the group consisting of polyamide, polyimide, polyester, polyetherketone, polyamideimide and polyesterimide, and A laminated film that simultaneously satisfies the conditions (i) to (iv).

  (I) The in-plane retardation Re (a) of the layer A is 5 nm or less, and the thickness direction retardation Rth (a) is −5 nm or more and 5 nm or less.

(Ii) The photoelastic coefficient of the layer A is smaller than 5.0 × 10 ⁻¹² Pa ⁻¹ .

  (Iii) When the glass transition temperature of the acrylic resin contained in the layer A is Tg and the in-plane retardation when it is stretched 1.5 times at Tg-10 ° C. is Re (a ′), | Re ( a ′) − Re (a) | <5 (nm) is satisfied.

  (Iv) The thickness direction retardation Rth (b) of the layer B satisfies | Rth (b) |> | Rth (a) | × 50.

  [2] The layer A containing an acrylic resin has an unsaturated carboxylic acid alkyl ester unit a represented by the following structural formula (a), an unsaturated carboxylic acid unit b represented by the structural formula (b), and a structural formula. The laminate according to the above [1], comprising an acrylic polymer B containing the cyclized structural unit c represented by (c) and elastic particles E having an average particle diameter of 10 to 1,000 nm. the film.

(In the above formula, R ¹ and R ² represent hydrogen or an organic residue having 1 to 5 carbon atoms.)

(In the above formula, R ³ represents hydrogen or an organic residue having 1 to 5 carbon atoms.)

(In the ^formula, R 4, ^{R 5} represents. In the formula ^X 1, ^{X 2} hydrogen or an organic residue having 1 to 5 carbon atoms, ^{.R 11} representing C = O at or ^{CH-R 11} is Represents hydrogen or an organic residue having 1 to 5 carbon atoms.)
[3] The laminated film according to [2], wherein the acrylic polymer B contains a glutaric anhydride unit represented by the following structural formula (d).

(In the above formula, R ⁶ and R ⁷ represent hydrogen or an organic residue having 1 to 5 carbon atoms.)
[4] The acrylic polymer B contains an unsaturated carboxylic acid alkyl ester unit and a glutaric anhydride unit, and when the acrylic polymer B is 100 parts by mass, the glutaric anhydride unit is 10 to 25 parts by mass. The laminated film according to [2] or [3], which is contained in a part.

  [5] The laminated film according to any one of [1] to [4], which is used as a polarizer protective film with an optical compensation layer.

  [6] A polarizing plate with an optical compensation layer constituted by using the laminated film according to [5].

  According to the present invention, an optical laminated film comprising at least a retardation, a layer having a small change in birefringence due to stress, and a layer exhibiting a phase difference, and a polarization having a phase difference, which are particularly suitable for protecting a phased polarizer. Since a plate can be provided, it can be used very suitably for a polarizer protective film with an optical compensation layer.

  The present invention has a layer A containing an acrylic resin and a layer B containing at least one polymer selected from the group consisting of polyamide, polyimide, polyester, polyetherketone, polyamideimide and polyesterimide, and It is characterized by a laminated film that simultaneously satisfies the following conditions (i) to (iv).

  (I) The in-plane retardation Re (a) of the layer A is 5 nm or less, and the thickness direction retardation Rth (a) is −5 nm or more and 5 nm or less.

(Ii) The photoelastic coefficient of the layer A is smaller than 5.0 × 10 ⁻¹² Pa ⁻¹ .

  (Iii) When the glass transition temperature of the acrylic resin contained in the layer A is Tg and the in-plane retardation when stretched 1.5 times at Tg-10 ° C. is Re (a ′), | Re ( a ′) − Re (a) | <5 (nm) is satisfied.

  (Iv) The thickness direction retardation Rth (b) of the layer B satisfies | Rth (b) |> | Rth (a) | × 50.

  The layer A is preferably used as a base film for the layer B that expresses a phase difference, and the layer A is more preferable as the birefringence and the change in birefringence due to stress are smaller. Specifically, the in-plane retardation Re (a) is preferably 5 nm or less, and the thickness direction retardation Rth (a) is −5 nm or more and 5 nm or less. More preferably, the in-plane retardation Re (a) is 2 nm or less, and the thickness direction retardation Rth (a) is −2 nm or more and 2 nm or less.

The photoelastic coefficient is preferably smaller than 5.0 × 10 ⁻¹² Pa ⁻¹ and more preferably smaller than 3.0 × 10 ⁻¹² Pa ⁻¹ .

  Further, the thickness direction retardation Rth (b) of the layer B preferably satisfies | Rth (b) |> | Rth (a) | × 50, and | Rth (b) |> | Rth (a) | × 70 is more preferable.

  Further, after forming a birefringent layer on the transparent polymer film layer, the laminate can be stretched to give a difference in refractive index in the plane of the birefringent layer. In this case, the transparent polymer film layer generally has birefringence by stretching. However, when the glass transition temperature of the acrylic resin contained in the layer A is Tg and the in-plane retardation is 1.5 times stretched at Tg−10 ° C. as in the present invention, Re (a ′). , | Re (a ′) − Re (a) | <5 (nm), both in-plane retardation and thickness direction retardation do not cause any practical problems even if stretched, so that peeling from the substrate It is more preferable to satisfy | Re (a ′) − Re (a) | <3 (nm), which is preferable because it can be used in a stacked state without requiring a winding operation.

  Thus, the structure of the layer A is not particularly limited as long as it satisfies the properties required for optical applications such as transparency, heat resistance, and mechanical properties. However, the layer A is not represented by the structural formula (a). Acrylic polymer B containing saturated carboxylic acid alkyl ester unit a, unsaturated carboxylic acid unit b represented by structural formula (b), and cyclized structural unit c represented by structural formula (c), and average particles It is preferable to contain elastic particles E having a diameter of 10 to 1,000 nm in order to reduce retardation and birefringence change due to stress.

  In addition, as the unsaturated carboxylic acid alkyl ester unit a, methyl methacrylate is preferable from the viewpoint of transparency and weather resistance of the resulting film. Further, one or more kinds of other unsaturated carboxylic acid alkyl ester monomers can be used together with methyl methacrylate. Moreover, there is no restriction | limiting in particular as another unsaturated carboxylic acid alkylester monomer, However, (meth) acrylic-acid ethyl, (meth) acrylic-acid n-propyl, (meth) acrylic-acid n-butyl, (meth) acrylic T-butyl acid, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, chloromethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (meth ) 3-hydroxypropyl acrylate, 2,3,4,5,6-pentahydroxyhexyl (meth) acrylate and 2,3,4,5-tetrahydroxypentyl (meth) acrylate.

(In the above formula, R ¹ and R ² represent hydrogen or an organic residue having 1 to 5 carbon atoms.)
In addition, the unsaturated carboxylic acid unit b is preferably acrylic acid or methacrylic acid, and more preferably methacrylic acid, in view of excellent thermal stability. These can be used alone or in combination of two or more thereof.

(In the above formula, R ³ represents hydrogen or an organic residue having 1 to 5 carbon atoms.)
Furthermore, as the cyclized structural unit c, a vinyl monomer that gives the unit is polymerized to form a copolymer, and then the copolymer is heated in the presence or absence of a suitable catalyst, It can be produced by causing an intramolecular cyclization reaction by dealcoholization and / or dehydration. R ³ is particularly preferably hydrogen or a methyl group from the viewpoint of heat resistance, and particularly preferably a methyl group.

(In the ^formula, R 4, ^{R 5} represents. In the formula ^X 1, ^{X 2} hydrogen or an organic residue having 1 to 5 carbon atoms, ^{.R 11} representing C = O at or ^{CH-R 11} is Represents hydrogen or an organic residue having 1 to 5 carbon atoms.)
When acrylic polymer B contains a glutaric anhydride unit represented by the following structural formula (d) (among the structural formula (c), an acrylic polymer having a glutaric anhydride unit represented by structural formula (d) in particular Use of a polymer) is preferable because a film having excellent transparency, heat resistance, and productivity and excellent optical isotropy can be obtained. The glutaric anhydride unit is obtained by polymerizing an unsaturated carboxylic acid monomer and an unsaturated carboxylic acid alkyl ester monomer to form a copolymer, followed by heating in the presence or absence of an appropriate catalyst to remove the glutaric anhydride unit. It can be produced by carrying out an intramolecular cyclization reaction by alcohol and / or dehydration. In this case, 1 unit of the glutaric anhydride unit is obtained by dehydrating the carboxyl group of 2 units of the unsaturated carboxylic acid unit or by eliminating the alcohol from the adjacent unsaturated carboxylic acid unit and unsaturated carboxylic acid alkyl ester unit. Is generated.

(In the above formula, R ⁶ and R ⁷ represent hydrogen or an organic residue having 1 to 5 carbon atoms.)
When the layer A is used as an optical film, the layer A is required to have a small phase difference in optical isotropic applications.

  Here, the optical isotropic application is an application in which optical isotropy is required inside the material, and specific examples include a polarizer protective film, a lens, and an optical waveguide core. In a liquid crystal television, two polarizing plates are used orthogonally or in parallel, but when the polarizer protective film does not exist or is optically isotropic, black is displayed in a state where the two polarizing plates are orthogonal, When two polarizing plates are parallel, white is displayed. On the other hand, when the polarizer protective film is not optically isotropic, for example, dark purple is displayed instead of black when the two polarizing plates are orthogonal to each other, and yellow instead of white is displayed when the two polarizing plates are parallel. . This coloring varies depending on the anisotropy of the polarizer protective film. Ideally, the polarizer protective film does not exist optically, but is indispensable for the purpose of protecting the polarizer from external stress and moisture. In the case of a lens, the lens is intended to refract light at the interface, but it is necessary for light to travel uniformly within the lens. If the inside of the lens is not optically isotropic, there is a problem that the image is distorted. In the case of the optical waveguide core, if it is not optically isotropic, for example, there is a difference in the transmission speed between the horizontal wave signal and the vertical wave signal, which causes noise and interference problems. Other optical isotropic applications include prism sheet substrates, optical disk substrates, flat panel display substrates, and the like.

  As for the resin structure, when an aromatic ring having many π electrons is introduced, the heat resistance is improved more than the introduction of an alicyclic structure, but at the same time, there is a problem that birefringence increases and phase difference is easily developed. For this reason, it is most preferable to contain an alicyclic structure in order to improve heat resistance while maintaining the optical isotropy. Examples of the alicyclic structure include a glutaric anhydride structure, a lactone ring structure, a norbornene structure, and a cyclopentane structure. For optical isotropy and heat resistance, the same effect can be obtained using any structure, but for the introduction of lactone ring structure, norbornene structure, cyclopentane structure, etc., use expensive raw materials having these structures, Alternatively, it is industrially disadvantageous because it is necessary to use an expensive raw material to be a precursor of these structures and to obtain a target structure through several steps of reaction. On the other hand, glutaric anhydride units are industrially very advantageous because they are obtained from a general acrylic raw material by a one-step dehydration and / or dealcoholization reaction.

  When the glass transition temperature (Tg) of the acrylic resin is lower than 120 ° C., processing steps when used for a film for liquid crystal display devices such as a polarizer protective film, various optical disk substrate protective films, etc., or automobile navigation Due to the widespread use of systems, handy cameras, etc., the use range cannot withstand use under harsh use environment conditions that require weather resistance and heat resistance such as outdoors and in automobiles. Moreover, it is preferable that a glass transition temperature (Tg) is 200 degrees C or less. When the temperature is higher than 200 ° C., it is necessary to set a corresponding high temperature during film formation, which may be disadvantageous from the viewpoint of film formation.

  In addition, when the retardation (Re) in the film surface of the thermoplastic resin film exceeds 10 nm, or when the retardation (Rth) in the film thickness direction exceeds 10 nm, the display quality is optically isotropic. It will not be able to withstand use such as lowering.

  Next, although the example of the manufacturing method of the acrylic polymer containing the glutaric anhydride unit represented by Structural formula (d) is demonstrated, this invention is not limited to this.

(In the above formula, R ⁶ and R ⁷ represent hydrogen or an organic residue having 1 to 5 carbon atoms.)
When the acrylic polymer contains an unsaturated carboxylic acid alkyl ester monomer (A), an unsaturated carboxylic acid monomer (B), and other vinyl monomer units, the vinyl polymer that gives the units After the polymer (C) is polymerized to form a copolymer (a), the copolymer (a) is heated in the presence or absence of a suitable catalyst, and a molecule obtained by dealcoholization and / or dehydration. It can be produced by carrying out an internal cyclization reaction. In this case, typically, the carboxyl group of the unsaturated carboxylic acid unit of 2 units is dehydrated by heating the copolymer (a), or the adjacent unsaturated carboxylic acid unit and unsaturated carboxylic acid alkyl ester unit. 1 unit of the glutaric anhydride unit is generated by the elimination of the alcohol.

  The unsaturated carboxylic acid alkyl ester monomer (A) used in this case is not particularly limited, but preferred examples include those represented by the following structural formula (a).

(In the above formula, R ¹ and R ² represent hydrogen or an organic residue having 1 to 5 carbon atoms.)
Of these, acrylates and / or methacrylates having an aliphatic or alicyclic hydrocarbon group having 1 to 5 carbon atoms or a hydrocarbon group having a substituent are particularly suitable in terms of excellent thermal stability. is there.

  Preferable specific examples of the unsaturated carboxylic acid alkyl ester monomer (B) include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, and n-butyl (meth) acrylate. T-butyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, chloromethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 2- (meth) acrylic acid 2- Hydroxyethyl, 3-hydroxypropyl (meth) acrylate, 2,3,4,5,6-pentahydroxyhexyl (meth) acrylate and 2,3,4,5-tetrahydroxypentyl (meth) acrylate Among them, methyl methacrylate is most preferably used. These can be used alone or in combination of two or more thereof.

  In addition, the unsaturated carboxylic acid monomer (B) used in this case is not particularly limited, and can be copolymerized with another vinyl compound (C). Monomers can be used.

(In the above formula, R ³ represents hydrogen or an organic residue having 1 to 5 carbon atoms.)
In particular, acrylic acid and methacrylic acid are preferable from the viewpoint of excellent thermal stability, and methacrylic acid is more preferable. These can be used alone or in combination of two or more thereof.

  Further, in the production of an acrylic polymer having a ring structure used in the present invention, other vinyl monomers (C) such as styrene, acrylamide, methacrylamide, etc. may be used as long as the effects of the present invention are not impaired. Although it does not matter, monomers that do not contain an aromatic ring can be more preferably used in terms of transparency, birefringence, and chemical resistance. These may be used alone or in combination of two or more.

  As for the polymerization method of the acrylic polymer having a ring structure, a polymerization method such as bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization or the like by radical polymerization can be basically used. Solution polymerization, bulk polymerization, and suspension polymerization are particularly preferred.

  The polymerization temperature is not particularly limited, but from the viewpoint of color tone, a monomer mixture containing an unsaturated carboxylic acid monomer and an unsaturated carboxylic acid alkyl ester monomer is polymerized at a polymerization temperature of 95 ° C. or less. Is preferred. The lower limit of the polymerization temperature is not particularly limited as long as the polymerization proceeds, but is usually 50 ° C. or higher from the viewpoint of productivity considering the polymerization rate. For the purpose of improving the polymerization yield or polymerization rate, it is possible to raise the polymerization temperature as the polymerization proceeds. The polymerization time is not particularly limited as long as it is a sufficient time to obtain the required degree of polymerization, but is preferably in the range of 60 to 360 minutes from the viewpoint of production efficiency.

  In the present invention, a preferred ratio of the monomer mixture used in the production of the acrylic polymer having a ring structure is 5 parts by weight of the unsaturated carboxylic acid monomer (A) based on 100 parts by mass of the monomer mixture. -50 parts by mass, more preferably 9-33 parts by mass, the unsaturated carboxylic acid alkyl ester monomer (B) is preferably 50-95 parts by mass, more preferably 67-91 parts by mass, and can be copolymerized therewith. When using another vinyl-type monomer (C), the preferable ratio is 0-5 mass parts, and a more preferable ratio is 0-3 mass parts.

  When the unsaturated carboxylic acid monomer amount (B) is less than 5 parts by mass, the amount of glutaric anhydride units represented by the structural formula (d) by heating the copolymer (a) is small. Thus, the heat resistance improvement effect of the acrylic film of the present invention tends to be small. On the other hand, when the unsaturated carboxylic acid monomer amount (B) exceeds 50 parts by mass, a large amount of unsaturated carboxylic acid units tend to remain after the cyclization reaction by heating the copolymer (a). , Colorless transparency, residence stability, and dimensional stability after film formation tend to decrease.

  The acrylic polymer having a ring structure used for the acrylic film of the present invention preferably has a mass average molecular weight of 50,000 to 150,000. The acrylic polymer having a ring structure having such a molecular weight is obtained by controlling the copolymer (a) to a desired molecular weight, that is, a mass average molecular weight of 50,000 to 150,000 in advance during the production of the copolymer (a). This can be achieved. When the mass average molecular weight exceeds 150,000, there is a tendency to color during cyclization in the subsequent step. On the other hand, when the mass average molecular weight is less than 50,000, the mechanical strength of the acrylic film tends to decrease.

  The copolymer (a) used for the production of the acrylic polymer having a ring structure preferably used in the present invention is heated and subjected to intramolecular cyclization reaction by (i) dehydration and / or (b) dealcoholization, and glutaric acid There are no particular restrictions on the method for producing an acrylic polymer containing an anhydride unit, but a method for producing it through a heated extruder having a vent, or in an apparatus that can be heated and degassed under an inert gas atmosphere or under reduced pressure. Is preferable from the viewpoint of productivity. Among them, when an intramolecular cyclization reaction is carried out by heating in the presence of oxygen, the yellowness tends to decrease, so that it is preferable to sufficiently substitute the inside of the system with an inert gas such as nitrogen. Moreover, it is more preferable that the apparatus has a structure capable of introducing an inert gas such as nitrogen into them. For example, as a method for introducing an inert gas such as nitrogen into a twin-screw extruder, a method of connecting a pipe of an inert gas stream of about 10 to 100 liters / minute from the upper part and / or the lower part of the hopper can be mentioned. .

  The temperature during cyclization is not particularly limited as long as (i) dehydration and / or (b) dealcoholization causes an intramolecular cyclization reaction, but is preferably in the range of 180 to 300 ° C, particularly 200 to 200 ° C. A range of 280 ° C is preferred.

  Further, the cyclization time at this time is not particularly limited and can be appropriately set according to the desired copolymer composition, but is usually 1 minute to 60 minutes, preferably 2 minutes to 30 minutes, especially 3 to 20 minutes. The range of is preferable. In particular, the length / diameter ratio (L / D) of the extruder screw is preferably 40 or more in order to secure a heating time for allowing sufficient intramolecular cyclization reaction to proceed using an extruder. When an extruder with a short L / D is used, a large amount of unreacted unsaturated carboxylic acid units remain, so that the reaction proceeds again during the heat molding process, and there is a tendency for bubbles to be seen in the molded product and the color tone during molding retention. Tend to drop significantly.

  Furthermore, in the present invention, when the copolymer (a) is heated by the above method or the like, one or more of acid, alkali and salt compounds may be added as a catalyst for promoting the cyclization reaction to glutaric anhydride. it can. The addition amount is not particularly limited, and is preferably about 0.01 to 1 part by mass with respect to 100 parts by mass of the copolymer (a).

  The acrylic polymer having a ring structure preferably has a glass transition temperature (Tg) of 120 ° C. or more in terms of heat resistance. The method for raising the glass transition temperature is not particularly limited, but it is effective to increase the content of the cyclized structural unit represented by, for example, the structural formula (d) in the acrylic polymer having a ring structure. It is.

  As the acrylic polymer having a ring structure of the present invention, a copolymer comprising a glutaric anhydride unit represented by the structural formula (d) and an unsaturated carboxylic acid alkyl ester unit can be preferably used. The content of the unsaturated carboxylic acid alkyl ester unit and the glutaric anhydride unit is not particularly limited, but in general, the unsaturated carboxylic acid alkyl ester unit has negative birefringence and the glutaric anhydride unit has a positive value. Since the birefringence is expressed, when the total of unsaturated carboxylic acid alkyl ester units and glutaric anhydride units is 100 parts by mass, preferably 75 to 90 parts by mass of unsaturated carboxylic acid alkyl ester units and glutaric acid are used. It consists of 10-25 parts by weight of anhydride units, more preferably 80-87 parts by weight of unsaturated carboxylic acid alkyl ester units and 13-20 parts by weight of glutaric anhydride units. When the glutaric anhydride unit is less than 10 parts by mass, the effect of improving heat resistance tends to be small.

In addition, a proton nuclear magnetic resonance ( ¹ H-NMR) measuring instrument is used for quantification of each component unit in the acrylic polymer having a ring structure of the present invention. ^{In the 1} H-NMR method, for example, in the case of a copolymer consisting of a glutaric anhydride unit, methacrylic acid, and methyl methacrylate, the spectral assignment in a dimethyl sulfoxide heavy solvent is 0.5 to 1.5 ppm peak. Is hydrogen of α-methyl group of methacrylic acid, methyl methacrylate and glutaric anhydride ring compound, peak of 1.6 to 2.1 ppm is hydrogen of methylene group of polymer main chain, peak of 3.5 ppm is methyl methacrylate The carboxylic acid ester (—COOCH ₃ ) of hydrogen, the peak at 12.4 ppm can determine the copolymer composition from the carboxylic acid hydrogen of methacrylic acid and the integral ratio of the spectrum. In addition to the above, in the case of a copolymer containing styrene as another copolymer component, hydrogen of an aromatic ring of styrene is seen at 6.5 to 7.5 ppm, and the copolymer is similarly obtained from the spectral ratio. The composition can be determined.

  In addition, the acrylic polymer having a ring structure of the present invention may have other unsaturated carboxylic acid units and / or other copolymerizable copolymer in the acrylic polymer having a ring structure as long as the refractive index is within a predetermined range. A vinyl-type monomer unit can be contained.

  The amount of other unsaturated carboxylic acid units contained in 100 parts by mass of the acrylic polymer is preferably 10 parts by mass or less, that is, 0 to 10 parts by mass, more preferably 0 to 5 parts by mass, and most preferably 0. -1 part by mass. When the unsaturated carboxylic acid unit exceeds 10 parts by mass, the colorless transparency and the residence stability tend to decrease.

  Further, the amount of other copolymerizable vinyl monomer units is preferably 5 parts by mass or less, ie, 0 to 5 parts by mass, more preferably 0 to 3 parts by mass, in 100 parts by mass of the acrylic polymer. Part. In particular, when an aromatic vinyl monomer unit such as styrene is contained and the content exceeds the above range, colorless transparency, optical isotropy, and chemical resistance tend to decrease.

  In the present invention, elastic particles E having an average particle diameter of 10 to 1,000 nm can be used as long as the effects of the present invention are not impaired. The elastic particles E are composed of a layer containing one or more rubbery polymers and one or more layers composed of different polymers, and these layers are adjacent to each other. A so-called core-shell type multilayer structure polymer (E-1) can be preferably used.

  As the core-shell type multilayer structure polymer (E-1) used in the present invention, the number of layers constituting the core-shell type polymer (E-1) is not particularly limited, and may be two or more, or three or more. Although it may be four layers or more, it is preferably a multilayer structure polymer having at least one rubber layer inside.

  In the multilayer structure polymer (E-1) of the present invention, the type of the rubber layer is not particularly limited as long as it is composed of a polymer component having rubber elasticity. For example, a rubber composed of a polymer obtained by polymerizing an acrylic component, a silicone component, a styrene component, a nitrile component, a conjugated diene component, a urethane component or an ethylene component, a propylene component, an isobutene component, and the like can be given. Preferred rubbers include, for example, acrylic components such as ethyl acrylate units and butyl acrylate units, silicone components such as dimethylsiloxane units and phenylmethylsiloxane units, styrene components such as styrene units and α-methylstyrene units, acrylonitrile units, A rubber composed of a nitrile component such as a methacrylonitrile unit and a conjugated diene component such as a butanediene unit or an isoprene unit. A rubber composed of a combination of two or more of these components is also preferable. For example, (1) acrylic components such as ethyl acrylate units and butyl acrylate units and silicones such as dimethylsiloxane units and phenylmethylsiloxane units. Rubber composed of components, (2) rubber composed of acrylic components such as ethyl acrylate units and butyl acrylate units, and styrene components such as styrene units and α-methylstyrene units, (3) ethyl acrylate units and Rubber composed of acrylic components such as butyl acrylate units and conjugated diene components such as butanediene units and isoprene units, and (4) acrylic components such as ethyl acrylate units and butyl acrylate units, dimethylsiloxane units and phenylmethylsiloxanes Unit etc. Rubber composed of styrene component such as silicone component and styrene units and α- methyl styrene units and the like. In addition to these components, a rubber obtained by crosslinking a copolymer composed of a crosslinking component such as a divinylbenzene unit, an allyl acrylate unit, and a butylene glycol diacrylate unit is also preferable.

  In the above multilayer structure polymer (E-1), the type of layer other than the rubber layer is not particularly limited as long as it is composed of a polymer component having thermoplasticity, but it is more than the rubber layer. A polymer component having a high glass transition temperature is preferred. Polymers having thermoplastic properties include unsaturated carboxylic acid alkyl ester units, unsaturated carboxylic acid units, unsaturated glycidyl group-containing units, unsaturated dicarboxylic acid anhydride units, aliphatic vinyl units, and aromatic vinyls. Examples include polymers containing at least one unit selected from system units, vinyl cyanide units, maleimide units, unsaturated dicarboxylic acid units and other vinyl units. Among them, unsaturated carboxylic acids A polymer containing at least one unit selected from an alkyl ester unit, an unsaturated glycidyl group-containing unit, and an unsaturated dicarboxylic acid anhydride unit is preferable, and further, an unsaturated glycidyl group-containing unit and an unsaturated dicarboxylic acid A polymer containing at least one unit selected from anhydride-based units is more preferable.

  Although it does not specifically limit as a monomer used as the raw material of the said unsaturated carboxylic-acid alkylester type | system | group unit, (meth) acrylic-acid alkylester is used preferably. Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, (meth) acrylic N-hexyl acid, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, stearyl (meth) acrylate, octadecyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, ( Chloromethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2,3,4,5,6 (meth) acrylic acid -Pentahydroxyhexyl, 2,3,4,5-tetrahydroxypentyl (meth) acrylate, amino acid acrylate Examples include ethyl, propylaminoethyl acrylate, dimethylaminoethyl methacrylate, ethylaminopropyl methacrylate, phenylaminoethyl methacrylate, and cyclohexylaminoethyl methacrylate, and from the viewpoint that the effect of improving impact resistance is large ( Methyl methacrylate is preferably used. These units can be used alone or in combination of two or more.

  The unsaturated carboxylic acid monomer is not particularly limited, and examples thereof include acrylic acid, methacrylic acid, maleic acid, and further a hydrolyzate of maleic anhydride. Acrylic acid is particularly excellent in terms of thermal stability. Methacrylic acid is preferable, and methacrylic acid is more preferable. These can be used alone or in combination.

  The monomer used as the raw material for the unsaturated glycidyl group-containing unit is not particularly limited, and is glycidyl (meth) acrylate, glycidyl itaconate, diglycidyl itaconate, allyl glycidyl ether, styrene-4-glycidyl ether. And 4-glycidylstyrene, and glycidyl (meth) acrylate is preferably used from the viewpoint that the effect of improving impact resistance is great. These units can be used alone or in combination of two or more.

  Examples of the monomer used as a raw material for the unsaturated dicarboxylic acid anhydride unit include maleic anhydride, itaconic anhydride, glutaconic anhydride, citraconic anhydride, and aconitic anhydride, and the effect of improving impact resistance. From the standpoint of large, maleic anhydride is preferably used. These units can be used alone or in combination of two or more.

  Examples of the monomer that is a raw material for the aliphatic vinyl-based unit include ethylene, propylene, and butadiene. Examples of the monomer that is a raw material for the aromatic vinyl-based unit are styrene, α-methylstyrene, 1 -Vinyl naphthalene, 4-methyl styrene, 4-propyl styrene, 4-cyclohexyl styrene, 4-dodecyl styrene, 2-ethyl-4-benzyl styrene, 4- (phenylbutyl) styrene, halogenated styrene, etc. Acrylonitrile, methacrylonitrile, ethacrylonitrile, etc. are used as the raw material for the vinyl-based unit, and maleimide, N-methylmaleimide, N-ethylmaleimide are used as the monomer for the maleimide-based unit. N-propylmaleimide, N-isopropylmaleimide, Examples of monomers that can be used as raw materials for the unsaturated dicarboxylic acid units include maleic acid and maleic acid such as -cyclohexylmaleimide, N-phenylmaleimide, N- (p-bromophenyl) maleimide, and N- (chlorophenyl) maleimide. Monoethyl ester, itaconic acid, phthalic acid, and the like, which are monomers used as raw materials for the other vinyl units, include acrylamide, methacrylamide, N-methylacrylamide, butoxymethylacrylamide, N-propylmethacrylamide, N- Vinyldiethylamine, N-acetylvinylamine, allylamine, methallylamine, N-methylallylamine, p-aminostyrene, 2-isopropenyl-oxazoline, 2-vinyl-oxazoline, 2-acryloyl-oxazoline, and 2-styrene Examples include ril-oxazoline, and these monomers can be used alone or in combination of two or more.

  In the multilayer structure polymer (E-1) containing the rubber polymer, the type of the outermost layer is not particularly limited, and is an unsaturated carboxylic acid alkyl ester unit, an unsaturated carboxylic acid unit, Unsaturated glycidyl group-containing units, aliphatic vinyl units, aromatic vinyl units, vinyl cyanide units, maleimide units, unsaturated dicarboxylic acid units, unsaturated dicarboxylic anhydride units, and other vinyl units And at least one selected from polymers containing, for example, unsaturated carboxylic acid alkyl ester units, unsaturated carboxylic acid units, unsaturated glycidyl group-containing units, and unsaturated dicarboxylic anhydrides At least one selected from polymers containing units is preferred, and further, unsaturated carboxylic acid alkyl ester units, unsaturated polymers. Polymers containing carbon acid units are more preferable.

  Furthermore, in the present invention, when the outermost layer in the multilayer polymer (E-1) is a polymer containing an unsaturated carboxylic acid alkyl ester unit and an unsaturated carboxylic acid unit, by heating, In the same manner as in the production of the thermoplastic copolymer (A) of the present invention described above, the intramolecular cyclization reaction proceeds to produce a glutaric anhydride unit represented by the general formula (d). Therefore, a multilayer structure polymer (E-1) having a polymer containing an unsaturated carboxylic acid alkyl ester unit and an unsaturated carboxylic acid unit in the outermost layer is blended with the thermoplastic copolymer (A), In the thermoplastic copolymer (A) that becomes a continuous phase (matrix phase) by heating and melt-kneading under such conditions, the glutaric acid represented by the above general formula (d) in the outermost layer is practically used. By dispersing the multilayer structure polymer (E-1) having a polymer containing an anhydride unit, a good dispersion state is possible without agglomeration, and with improved mechanical properties such as impact resistance, It is considered that extremely high transparency can be expressed.

  The monomer used as the raw material for the unsaturated carboxylic acid alkyl ester unit herein is not particularly limited, but (meth) acrylic acid alkyl ester is preferred, and methyl (meth) acrylate is more preferred. Preferably used.

  Further, the monomer used as a raw material for the unsaturated carboxylic acid unit is not particularly limited, but (meth) acrylic acid is preferable, and methacrylic acid is more preferably used.

  As a preferable example of the multilayer structure polymer (E-1) of the present invention, the core layer is butyl acrylate / styrene polymer, the outermost layer is methyl methacrylate / glutaric acid anhydride represented by the above general formula (d). A copolymer consisting of a product unit, or methyl methacrylate / glutaric anhydride unit represented by the above general formula (d) / methacrylic acid polymer, and the core layer is a dimethylsiloxane / butyl acrylate polymer. The outer layer is a methyl methacrylate polymer, the core layer is a butanediene / styrene polymer and the outermost layer is a methyl methacrylate polymer, and the core layer is a butyl acrylate polymer and the outermost layer is a methyl methacrylate polymer ("/" Indicates copolymerization). Furthermore, a preferable example is one in which either one or both of the rubber layer and the outermost layer is a polymer containing a glycidyl methacrylate unit. Among them, the core layer is butyl acrylate / styrene polymer, and the outermost layer is methyl methacrylate / a copolymer of glutaric anhydride units represented by the above general formula (d), or methyl methacrylate / the above general formula. The glutaric anhydride unit represented by (d) / methacrylic acid polymer approximates the refractive index with the acrylic resin (A) that is the continuous phase (matrix phase), and in the resin composition It is possible to obtain a good dispersion state with the above, and in recent years, since transparency that can satisfy the demand for higher level is developed, it can be preferably used.

  As a method of forming the film, any conventionally known method can be used. Examples thereof include a solution casting method and a melt extrusion method, and any of them can be employed. For example, when trying to obtain a film using the solution casting method, an acrylic polymer having a ring structure is stirred and mixed in a good solvent to form a uniform mixed solution, and cast on a support film or drum to provide self-supporting properties. After pre-drying until it has, it can be obtained by peeling off from the support film or drum and drying. In the melt extrusion method, a film having an arbitrary thickness can be obtained by extruding an acrylic polymer having a ring structure while heating and melting it from an extruder equipped with a T-type die and the like, and taking out the resulting film.

  As thickness of the film of this invention, 1-100 micrometers is preferable from a viewpoint of making the in-plane retardation value of the film obtained, and thickness retardation value low. More preferably, it is 5-50 micrometers.

  The film of the present invention may be unstretched as a final product in terms of simplification of the manufacturing process, cost reduction, etc., but using a known stretching method for improving the strength of the film or reducing the film thickness. Further, at least one axis may be stretched.

  Moreover, the above-mentioned thermoplastic resin film of the present invention can be used for various uses as a final product as it is or after being subjected to various processing. Utilizing particularly excellent transparency, low birefringence, etc., it is suitably used for known optical applications such as optical films, that is, optical isotropic films, polarizer protective films, transparent conductive films, and the like around liquid crystal display devices. be able to. In this case, it is preferable to use an optical film configured to include one or more layers of the thermoplastic resin film.

  Furthermore, the film of the present invention can be subjected to surface treatment on one side or both sides of the film, if necessary. Examples of the surface treatment method include corona treatment, plasma treatment, and ultraviolet irradiation. In particular, when surface processing such as coating is applied to the film surface, or when another film is laminated with an adhesive, surface treatment of the film is performed as a means for improving mutual adhesion. Is preferred.

  In addition, a coating layer such as a hard coat layer can be formed on the surface of the stretched film as necessary. Moreover, the film of this invention may form a transparent conductive layer by sputtering method etc. through or without a coating layer.

  Further, the structure of the layer B is not particularly limited as long as it satisfies optical properties such as optical properties, coating properties, and stability, but polyamide, polyimide, polyester, polyetherketone, polyamideimide, and polyesterimide are not limited. It is desirable to include at least one polymer selected from the group consisting of, and it is preferable that the polymer is composed of these polymers. Especially, it is preferable that in-plane orientation is high and it is soluble in an organic solvent.

  Specifically, as an example of polyamide, for example, a condensation polymerization product of 9,9-bis (aminoaryl) fluorene and aromatic tetracarboxylic dianhydride disclosed in JP 2000-511296 A is disclosed. Including polymers can be used.

  The layer B is preferably formed as a birefringent layer by applying a polymer solution constituting the layer B on the layer A in the form of a film and evaporating and removing the solvent. The solvent of the solution to be applied is not particularly limited, and examples thereof include halogenated hydrocarbons such as chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, trichloroethylene, tetrachloroethylene, chlorobenzene, and orthodichlorobenzene; phenol and parachlorophenol. Phenols such as benzene, toluene, xylene, methoxybenzene, 1,2-dimethoxybenzene and other aromatic hydrocarbons; acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, 2-pyrrolidone, N-methyl- Ketone solvents such as 2-pyrrolidone; ester solvents such as ethyl acetate and butyl acetate; t-butyl alcohol, glycerin, ethylene glycol, triethylene glycol, ethylene glycol Alcohol solvents such as monomethyl ether, diethylene glycol dimethyl ether, propylene glycol, dipropylene glycol and 2-methyl-2,4-pentanediol; amide solvents such as dimethylformamide and dimethylacetamide; nitrile systems such as acetonitrile and butyronitrile Solvents; ether solvents such as diethyl ether, dibutyl ether, tetrahydrofuran; carbon disulfide, ethyl cellosolve, butyl cellosolve, and the like. One type of these solvents may be used, or two or more types may be used in combination.

  For example, the coating solution may further contain various additives such as a stabilizer, a plasticizer, and metals as necessary.

  The coating solution may contain other different resins. Examples of the other resin include various general-purpose resins, engineering plastics, thermoplastic resins, and thermosetting resins.

  Examples of the general-purpose resin include polyethylene (PE), polypropylene (PP), polystyrene (PS), polymethyl methacrylate (PMMA), ABS resin, and AS resin. Examples of the engineering plastic include polyacetate (POM), polycarbonate (PC), polyamide (PA: nylon), polyethylene terephthalate (PET), and polybutylene terephthalate (PBT). Examples of the thermoplastic resin include polyphenylene sulfide (PPS), polyethersulfone (PES), polyketone (PK), polyimide (PI), polycyclohexanedimethanol terephthalate (PCT), polyarylate (PAR), and liquid crystal polymer. (LCP) and the like. Examples of the thermosetting resin include an epoxy resin and a phenol novolac resin.

  Thus, when said other resin etc. are mix | blended with the said coating solution, the compounding quantity is 0-50 mass% with respect to the said polymer material, Preferably, it is 0-30 mass%. is there.

  Examples of the solution coating method include spin coating, roll coating, flow coating, printing, dip coating, casting film formation, bar coating, and gravure printing. Moreover, in the case of coating, the superposition | polymerization method of a polymer layer is also employable as needed.

  After the coating, for example, the solvent in the solution is evaporated and removed by natural drying, air drying, or heat drying (for example, 60 to 250 ° C.) to form a film-like birefringent layer. This birefringent layer satisfies the condition of the formula (1). The thickness of the birefringent layer is not particularly limited, but is, for example, 0.1 to 50 μm, preferably 0.5 to 30 μm, more preferably from the viewpoint of thinning the liquid crystal display device, viewing angle compensation, film homogeneity, and the like. Is in the range of 1-20 μm.

  The above laminated film can be used as a polarizer protective film by being bonded to a polarizer to form a polarizing plate with an optical compensation layer. Here, as a polarizer, conventionally well-known arbitrary polarizers, such as what made iodine contain in the stretched polyvinyl alcohol, can be used, for example. The polarizer protective film is laminated on one side or both sides of the polarizer.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to this Example. Each characteristic value was measured as follows.

1. Film thickness Five points were measured using a micro thickness gauge (manufactured by Anritsu), and an average value was obtained.

2. Glass transition temperature (Tg)
Using a differential scanning calorimeter (DSC-7 manufactured by Perkin Elmer), the measurement was performed at a temperature increase rate of 20 ° C./min in a nitrogen atmosphere. The sample amount was 5 mg.

The glass transition temperature here was measured at a rate of temperature increase of 20 ° C./min using a differential scanning calorimeter (DSC-7 manufactured by Perkin Elmer) and determined according to JIS K7121 (1987). The midpoint glass transition temperature (T _mg ).

3. Transparency (total light transmittance, haze value)
Using a direct reading haze meter manufactured by Toyo Seiki Co., Ltd., the total light transmittance (%) and haze value (%) at 23 ° C. were measured three times, and transparency was evaluated with an average value. A halogen lamp (12V50W) was used as the light source, the total light transmittance was measured according to JIS-K7361-1997, and the haze was measured according to JIS-K7136-2000.

4). In-plane retardation Re and thickness direction retardation Rth
The in-plane retardation is determined by using an automatic birefringence meter (KOBRA-21ADH) manufactured by Oji Scientific Co., Ltd., and in a chromatic dispersion measurement mode, a phase difference for a light beam having a wavelength of 480.4 nm and a phase difference for a light beam having a wavelength of 548.3 nm , The phase difference with respect to the light beam having a wavelength of 628.2 nm, and the phase difference with respect to the light beam with a wavelength of 752.7 nm were measured, and the Cauchy wavelength dispersion formula (R (λ) = a + b / λ2 + c / λ4 + d / λ6) coefficients a to d were determined, and the maximum in-plane phase difference was determined by substituting the wavelength 550 nm (λ = 550) into the Cauchy wavelength dispersion formula. The measurement was performed once.

  The retardation Rth in the thickness direction is determined by using an automatic birefringence meter (KOBRA-21ADH) manufactured by Oji Scientific Co., Ltd., the refractive index in the orthogonal axis direction in the acrylic resin film plane with respect to light having a wavelength of 590 nm, nx, ny (However, nx ≧ ny), the refractive index nz in the thickness direction of the acrylic resin film with respect to light having a wavelength of 590 nm was measured, and the thickness was determined from the following formula when the thickness of the acrylic resin film was d (nm). The measurement was performed once.

Thickness direction retardation Rth (nm) = d × {(nx + ny) / 2−nz}
5). Photoelastic coefficient A sample having a short side of 1 cm and a long side of 7 cm was cut out. Using this sample, TRANSDUCER U3C1-5K manufactured by Shimadzu Corp., the upper and lower sides were sandwiched by 1 cm each, and a tension (F) of 1 kg / mm ² (9.81 × 10 ⁶ Pa) was applied in the long side direction. In this state, Re (nm) was measured using a polarizing microscope 5892 manufactured by Nikon Corporation. Sodium D line (589 nm) was used as a light source. These numerical values were applied to photoelastic coefficient = Re / (d × F) to calculate the photoelastic coefficient. The measurement was performed once.

6). Each component composition The sample was melt | dissolved in acetone, this solution was centrifuged at 9,000 rpm for 30 minutes, and it isolate | separated into the acetone soluble component and the acetone insoluble component. The acetone-soluble component was dried under reduced pressure at 60 ° C. for 5 hours, and each component unit was quantified to identify each component composition of the acrylic resin.

Quantification of each component unit was performed by a proton nuclear magnetic resonance ( ¹ H-NMR) method. ^{In the 1} H-NMR method, for example, in the case of a copolymer consisting of a glutaric anhydride unit, methacrylic acid, and methyl methacrylate, the spectral assignment in a dimethyl sulfoxide heavy solvent is 0.5 to 1.5 ppm peak. Is hydrogen of α-methyl group of methacrylic acid, methyl methacrylate and glutaric anhydride ring compound, peak of 1.6 to 2.1 ppm is hydrogen of methylene group of polymer main chain, peak of 3.5 ppm is methyl methacrylate The carboxylic acid ester (—COOCH ₃ ) of hydrogen, the peak at 12.4 ppm can determine the copolymer composition from the carboxylic acid hydrogen of methacrylic acid and the integral ratio of the spectrum. In addition to the above, in the case of a copolymer containing styrene as another copolymer component, hydrogen of the aromatic ring of styrene is seen at 6.5 to 7.5 ppm, and the copolymer composition is similarly determined from the spectral ratio. Can be determined.

7). Average particle diameter of elastic particles The film was made into an ultra-thin section of about 100 to 800 nm in the thickness direction, dyed with ruthenic acid, and then used with a transmission electron microscope (JEM-1200EX manufactured by JEOL Ltd.) at a magnification of 100,000 times. The equivalent circle diameter was determined for 100 particles while changing the location, and the average value was taken as the average particle diameter. For core-shell type and graft copolymer type acrylic elastic particles, the average particle size of the rubbery polymer portion was measured.

Reference Example (1) Acrylic polymer (A1)
A methyl methacrylate / acrylamide copolymer suspension (prepared by the following method) in a stainless steel autoclave having a volume of 5 liters and equipped with a baffle and a foudra type stirring blade. 20 parts by mass of methyl methacrylate and 80 parts by mass of acrylamide , 0.3 parts by weight of potassium persulfate and 1,500 parts by weight of ion-exchanged water were charged into the reactor and maintained at 70 ° C. while replacing the reactor with nitrogen gas. The resulting solution is obtained as an aqueous solution of methyl acrylate and acrylamide copolymer (using the obtained aqueous solution as a suspending agent), and a solution obtained by dissolving 0.05 part by mass in 165 parts by mass of ion-exchanged water is supplied. The mixture was stirred at 400 rpm and the system was replaced with nitrogen gas. Next, the following mixed substances were added while stirring the reaction system, and the temperature was raised to 70 ° C. The time when the internal temperature reached 70 ° C. was set as the start of polymerization, and kept for 180 minutes to complete the polymerization. Thereafter, the reaction system was cooled, the polymer was separated, washed and dried according to the usual method to obtain a bead-shaped copolymer (a-1). The polymerization rate of this copolymer (a-1) was 98%, and the weight average molecular weight was 68,000.

Methacrylic acid: 20 parts by weight Methyl methacrylate: 80 parts by weight t-dodecyl mercaptan: 1.5 parts by weight 2,2′-azobisisobutyronitrile: 0.6 parts by weight The obtained copolymer (a-1 ) Using a twin-screw extruder (TEX30 (manufactured by Nippon Steel Co., Ltd., L / D = 44.5)) while purging nitrogen from the hopper at an amount of 10 L / min. / H, an intramolecular cyclization reaction was carried out at a cylinder temperature of 270 ° C. to obtain a pellet-shaped acrylic resin (A1) The composition ratio of glutaric anhydride units in 100 parts by mass of the acrylic resin (A1) is 13 mass parts and the weight average molecular weight were 100,000.

Reference Example (2) Acrylic polymer (A2)
An acrylic resin (A2) was obtained in the same manner as in Reference Example 1 except that the substance used was changed to the following.

Methacrylic acid: 27 parts by weight Methyl methacrylate: 73 parts by weight t-dodecyl mercaptan: 1.5 parts by weight 2,2′-azobisisobutyronitrile: 0.4 parts by weight This acrylic resin (A2) 100 parts by weight The composition ratio of glutaric anhydride units in the mixture was 17 parts by mass, and the weight average molecular weight was 100,000.

Reference Example (3) Acrylic Elastic Particle (E1)
The core-shell polymer obtained by the following was used.

  A nitrogen container is charged with 120 parts by mass of deionized water, 0.5 parts by mass of potassium carbonate, 0.5 parts by mass of dioctyl sulfosuccinate, and 0.005 parts by mass of potassium persulfate in a glass container with a condenser (capacity 5 liters). After stirring under, 53 parts by mass of butyl acrylate, 17 parts by mass of styrene, and 1 part by mass of allyl methacrylate (crosslinking agent) were charged. These mixtures were reacted at 70 ° C. for 30 minutes to obtain a core layer polymer. Next, a mixture of 21 parts by weight of methyl methacrylate, 9 parts by weight of methacrylic acid, and 0.005 parts by weight of potassium persulfate was continuously added over 90 minutes, and further maintained for 90 minutes to polymerize the shell layer. The polymer latex was coagulated with sulfuric acid, neutralized with caustic soda, washed, filtered, and dried to obtain acrylic elastic particles (E1) having a two-layer structure. The average particle diameter of the polymer particles measured with an electron microscope was 155 nm.

Reference Example (4) Formation of Polymer Film (A1F) Made of Acrylic Resin Pellets of acrylic polymer (A1) obtained in the above Reference Example (1) were dried at 100 ° C. for 3 hours, and uniaxial extrusion of 45 mmφ Using a machine (set temperature 250 ° C.), the sheet was extruded through a T die (set temperature 250 ° C.). This film was cooled so that one surface was completely adhered to a 130 ° C. cooling roll to obtain an unstretched acrylic resin film. At this time, the speed of the cooling roll was adjusted so that the lip gap of the T die / film thickness = 15. The characteristics of the obtained film are as follows.

Thickness (μm): 40
Glass transition temperature (Tg) (° C.): 127
Total light transmittance (%): 93
Haze (%): 0.4
Phase difference (nm): 0.3
Thickness direction retardation (nm): 0.4
Photoelastic coefficient (10 ⁻¹² Pa ⁻¹ ): 1.0
Reference Example (5) Film Formation of Polymer Film (A2E1F) Consisting of Acrylic Resin 80 parts by mass of acrylic polymer (A2) obtained in Reference Example (2) above and acrylic elasticity obtained in Reference Example (3) The body particles (E1) were blended at a composition ratio of 20 parts by mass and kneaded using a twin screw extruder (TEX30 (manufactured by Nippon Steel Co., Ltd., L / D = 44.5) at a screw speed of 150 rpm and a cylinder temperature of 280 ° C. As a result, a pellet-shaped acrylic polymer (A2E1) was obtained.

  Subsequently, the unstretched acrylic resin film was obtained by the same method as Example 1 except having used the pellet-shaped acrylic polymer (A2E1). The characteristics of the obtained film are as follows.

Thickness (μm): 40
Glass transition temperature (Tg) (° C.): 135
Total light transmittance (%): 93
Haze (%): 0.4
Phase difference (nm): 0.4
Thickness direction retardation (nm): 0.6
Photoelastic coefficient (10 ⁻¹² Pa ⁻¹ ): 1.1
Reference Example (6) Preparation of Polyamide Solution (B1) First, 44′DDS (4,4′-diamino) corresponding to 50 mol% as an aromatic diamine component was added to NMP (N-methyl-2-pyrrolidone) as a polymerization solvent. Diphenylsulfone) and 33′DDS (3,3′-diaminodiphenylsulfone) corresponding to 50 mol% are dissolved, and CTPC (2-chloroterephthalic acid dichloride) corresponding to 99 mol% is added thereto as an acid chloride component. Added and stirred for 2 hours to complete the polymerization. This solution was neutralized with lithium carbonate and then reprecipitated in water to obtain a polyamide resin.

  Next, the obtained polyamide resin was dissolved in DMAC (dimethylacetamide) at 5% by mass and prepared.

Reference Example (7) Optical Property Measurement of Polyamide Solution (B1) The polyamide solution prepared in Reference Example (6) was applied as a uniform solution film with a bar coater on a glass plate with dimensions of 30 × 30 mm and a thickness of 1.1 mm. Then, it was dried in a hot air oven heated to 120 ° C. for 20 minutes to obtain a uniform coating film. The characteristics of the obtained coating film are as follows:
Thickness (μm): 5 (not including glass plate thickness)
Phase difference (nm): 0.7
Thickness direction retardation (nm): -90.3
Example 1
A solution having a uniform film thickness of 5 μm of the polyamide solution (B1) obtained in Reference Example (6) on the polymer film (A1F) made of the acrylic resin obtained in Reference Example (4) using a bar coater After coating as a film, it was dried in a hot air oven heated to 120 ° C. for 20 minutes to obtain a uniform laminated film.

  Two samples having a width of 50 mm and a length of 150 mm were cut out from the obtained laminated film. Among them, the in-plane retardation of one sheet was 0.9 nm, and the thickness direction retardation was −89.5 nm.

Next, the in-plane retardation and thickness direction retardation were measured by removing the polyamide layer on the polymer film (A1F) made of acrylic resin by wiping with a gauze soaked in DMAC (dimethylacetamide). They were 3 nm and 0.4 nm. The photoelastic coefficient was 1.0 × 10 ⁻¹² Pa ⁻¹ . The thickness retardation of the layer B is -89.9 nm, which satisfies | Rth (b) |> | Rth (a) | × 50. (Here, the thickness direction retardation of the polymer film (A1F) made of acrylic resin is Rth (a), and the thickness direction retardation of the coating film of the polyamide solution (B1) is Rth (b).)
When another cut sample was stretched 1.5 times at 117 ° C., a homogeneous stretch-oriented film was obtained. The obtained film had an in-plane retardation of 35.0 nm and a thickness direction retardation of −72.5 nm.

Subsequently, the in-plane retardation and the thickness direction retardation were measured by removing the polyamide layer on the homogeneous stretch-oriented film by wiping with gauze soaked in DMAC (dimethylacetamide). It was 3 nm. The photoelastic coefficient was 1.0 × 10 ⁻¹² Pa ⁻¹ . The thickness retardation of the layer B is -72.8 nm, which satisfies | Rth (b) |> | Rth (a) | × 50. (Here, the thickness direction retardation of the polymer film (A1F) made of acrylic resin is Rth (a), and the thickness direction retardation of the coating film of the polyamide solution (B1) is Rth (b).)
Therefore, even if the layer A is subjected to a stretching treatment, the phase difference does not change. Therefore, as an alternative to measuring the phase difference of only the polyamide layer, it was possible to measure the phase difference of the laminated film.

Example 2
A laminated film was obtained in the same manner as in Example 1 except that the polymer film made of the acrylic resin used was A2E1F obtained in Reference Example (5).

  Two samples having a width of 50 mm and a length of 150 mm were cut out from the obtained laminated film. Among them, the in-plane retardation of one sheet was 0.8 nm, and the thickness direction retardation was −88.0 nm.

Subsequently, the polyamide layer on the polymer film (A2E1F) made of an acrylic resin was removed by wiping with a gauze soaked in DMAC (dimethylacetamide), and the in-plane retardation and the thickness direction retardation were measured. They were 3 nm and 0.3 nm. The photoelastic coefficient was 1.1 × 10 ⁻¹² Pa ⁻¹ . The thickness retardation of the layer B is -88.3 nm, which satisfies | Rth (b) |> | Rth (a) | × 50. (Here, the thickness direction retardation of the polymer film (A2E1F) made of acrylic resin is Rth (a), and the thickness direction retardation of the coating film of the polyamide solution (B1) is Rth (b).)
When another cut sample was stretched 1.5 times at 125 ° C., a homogeneous stretch-oriented film was obtained. The in-plane retardation of the obtained film was 32.0 nm, and the thickness direction retardation was −74.0 nm.

Subsequently, the in-plane retardation and the thickness direction retardation were measured by removing the polyamide layer on the homogeneous stretch-oriented film by wiping with gauze soaked in DMAC (dimethylacetamide). It was 3 nm. The photoelastic coefficient was 1.1 × 10 ⁻¹² Pa ⁻¹ . The thickness retardation of the layer B is -74.3 nm, which satisfies | Rth (b) |> | Rth (a) | × 50. (Here, the thickness direction retardation of the polymer film (A2E1F) made of acrylic resin is Rth (a), and the thickness direction retardation of the coating film of the polyamide solution (B1) is Rth (b).)
Therefore, even if the layer A is subjected to a stretching treatment, the phase difference does not change. Therefore, as an alternative to measuring the phase difference of only the polyamide layer, it was possible to measure the phase difference of the laminated film.

Comparative Example 1
Using PMMA (“Delpet (registered trademark) 80N” (manufactured by Asahi Kasei Corporation)), a film was formed in the same manner as in Reference Example 4. ^When confirmed by ¹ H-NMR method, the ring structure could not be confirmed. The characteristics of the obtained PMMA film are as follows.

Thickness (μm): 40
Glass transition temperature (Tg) (° C.): 110
Total light transmittance (%): 90
Haze (%): 1.0
Phase difference (nm): 1.8
Thickness direction retardation (nm): 1.2
Photoelastic coefficient (10 ⁻¹² Pa ⁻¹ ): 5.0
A laminated film was obtained in the same manner as in Example 1 except that this film was used.

  Two samples having a width of 50 mm and a length of 150 mm were cut out from the obtained laminated film. Among them, the in-plane retardation of one sheet was 2.5 nm, and the thickness direction retardation was −83.0 nm.

Subsequently, the polyamide layer on the PMMA film was removed by wiping with a gauze soaked in DMAC (dimethylacetamide), and the in-plane retardation and thickness direction retardation were measured to be 1.8 nm and 1.2 nm, respectively. . The photoelastic coefficient was 5.0 × 10 ⁻¹² Pa ⁻¹ . The thickness retardation of the layer B is -84.2 nm, which satisfies | Rth (b) |> | Rth (a) | × 50. (Here, the thickness direction retardation of the PMMA film is Rth (a), and the thickness direction retardation of the coating film of the polyamide solution (B1) is Rth (b).)
When another cut sample was stretched 1.5 times at 100 ° C., a homogeneous stretch-oriented film was obtained. The obtained film had an in-plane retardation of 102.0 nm and a thickness direction retardation of -39.5 nm.

Subsequently, the in-plane retardation and the thickness direction retardation were measured by removing the polyamide layer on the homogeneous stretch-oriented film by wiping with gauze soaked in DMAC (dimethylacetamide). 0.5 nm. The photoelastic coefficient was 5.0 × 10 ⁻¹² Pa ⁻¹ . The thickness retardation of the layer B is -81.0 nm, and does not satisfy | Rth (b) |> | Rth (a) | × 50. (Here, the thickness direction retardation of the PMMA film is Rth (a), and the thickness direction retardation of the coating film of the polyamide solution (B1) is Rth (b).)
Since the layer A made of PMMA undergoes a change in phase difference when subjected to the stretching treatment, it was impossible to measure the phase difference of the laminated film as an alternative to measuring the phase difference of only the polyamide layer.

  The film of the present invention is an optical laminated film comprising a layer that exhibits retardation, a birefringence change due to stress, and a small retardation change due to stretching orientation, and a layer that exhibits a retardation, and a polarizer protective film with an optical compensation layer Can be used very suitably.

Claims (6)

A layer A containing an acrylic resin and a layer B containing at least one polymer selected from the group consisting of polyamide, polyimide, polyester, polyetherketone, polyamideimide and polyesterimide, and the following conditions ( A laminated film satisfying i) to (iv) at the same time.
(I) The in-plane retardation Re (a) of the layer A is 5 nm or less, and the thickness direction retardation Rth (a) is −5 nm or more and 5 nm or less.
(Ii) The photoelastic coefficient of the layer A is smaller than 5.0 × 10 ⁻¹² Pa ⁻¹ .
(Iii) When the glass transition temperature of the acrylic resin contained in the layer A is Tg and the in-plane retardation when it is stretched 1.5 times at Tg-10 ° C. is Re (a ′), | Re ( a ′) − Re (a) | <5 (nm) is satisfied.
(Iv) The thickness direction retardation Rth (b) of the layer B satisfies | Rth (b) |> | Rth (a) | × 50. The layer A containing an acrylic resin has an unsaturated carboxylic acid alkyl ester unit a represented by the following structural formula (a), an unsaturated carboxylic acid unit b represented by the structural formula (b), and a structural formula (c). The laminated film of Claim 1 containing the acryl-type polymer B containing the cyclic structure unit c represented by these, and the elastic body particle E whose average particle diameter is 10-1,000 nm.

(In the above formula, R ¹ and R ² represent hydrogen or an organic residue having 1 to 5 carbon atoms.)

(In the above formula, R ³ represents hydrogen or an organic residue having 1 to 5 carbon atoms.)

(In the ^formula, R 4, ^{R 5} represents. In the formula ^X 1, ^{X 2} hydrogen or an organic residue having 1 to 5 carbon atoms, ^{.R 11} representing C = O at or ^{CH-R 11} is Represents hydrogen or an organic residue having 1 to 5 carbon atoms.) The laminated film according to claim 2, wherein the acrylic polymer B contains a glutaric anhydride unit represented by the following structural formula (d).

(In the above formula, R ⁶ and R ⁷ represent hydrogen or an organic residue having 1 to 5 carbon atoms.) The acrylic polymer B contains an unsaturated carboxylic acid alkyl ester unit and a glutaric anhydride unit, and when the acrylic polymer B is 100 parts by mass, the glutaric anhydride unit is contained in an amount of 10 to 25 parts by mass. The laminated film according to claim 2 or 3. The laminated film according to any one of claims 1 to 4, which is used as a polarizer protective film with an optical compensation layer. The polarizing plate with an optical compensation layer comprised using the laminated | multilayer film of Claim 5.