KR20130096215A - Retardation film and image display device provided with same - Google Patents

Abstract

The retardation film of this invention contains the layer which consists of 30-95 weight% of (meth) acryl polymers which have a ring structure in a principal chain, and the resin composition containing 5-70 weight% of cellulose-ester polymers. The retardation film of the present invention has a low photoelastic coefficient and low water vapor transmission rate, high degree of freedom in controlling the wavelength dispersion of the phase difference, for example, a phase difference in which the reverse wavelength dispersion of the phase difference or the wavelength dispersion of the phase difference is flat. It is a film. This retardation film is suitable for the use of optical compensation in image display apparatuses, such as a liquid crystal display device (LCD).

Description

Retardation film and the image display apparatus provided with the same {RETARDATION FILM AND IMAGE DISPLAY DEVICE PROVIDED WITH SAME}

The present invention relates to a retardation film and an image display device including the film.

Conventionally, a cellulose polymer is used for the optical film including a polarizer protective film and retardation film. Unlike a retardation film made of a general polymer such as polycarbonate, a retardation film made of a cellulose-based polymer generally has a wavelength dispersion (reverse wavelength of phase difference) in which the phase difference becomes smaller as the wavelength of light becomes shorter, at least in the visible region. Acidic). For this reason, improvement of the image display characteristic in the liquid crystal display device (LCD) provided with the said retardation film is anticipated. However, derived from the characteristics of the cellulose polymer, the retardation film has a problem that a sufficiently large retardation of high moisture permeability and a large photoelastic coefficient cannot be obtained.

Apart from this, a (meth) acrylic polymer having a ring structure in the main chain is used for a retardation film (see Patent Document 1: Japanese Patent Laid-Open No. 2008-9378). The retardation film which consists of a (meth) acryl polymer which has a ring structure in a principal chain has high transparency and heat resistance, but securing a mechanical characteristic, especially flexibility is a subject. The mechanical properties of the retardation film are improved by addition or stretching of elastic particles such as rubber. However, when elastic particle is added, aggregation of the added particle should be suppressed and transparency as a retardation film should be ensured. In addition, the retardation film made of a (meth) acrylic polymer having a ring structure in the main chain has a wavelength dispersion (phase-order wavelength) in which the phase difference becomes larger as the wavelength of light becomes shorter, at least in the visible region, like a retardation film made of a general polymer. Dispersibility).

Patent Document 2 (Japanese Patent Laid-Open No. 2009-1744) discloses that a (meth) acryl polymer having a ring structure in the main chain is useful as a modifier of a cellulose ester film, and a (meth) acrylic polymer having a ring structure in the main chain. By adding to a cellulose-ester film, it is described that the deformation | transformation failure of the said film represented by U-shaped failure, core transfer is suppressed, and that there exists a retardation film in an example of a cellulose-ester film. However, Japanese Patent Application Laid-Open No. 2009-1744 does not describe how much a (meth) acrylic polymer having a ring structure in the main chain may be added to the cellulose ester film as a modifier, and only in Examples, The example which added 4-12 weight part of said (meth) acryl polymers to 100 weight part of cellulose esters is only described.

Japanese Patent Publication No. 2008-9378 Japanese Patent Publication No. 2009-1744

The present invention is a retardation film comprising a layer made of a resin composition containing a (meth) acrylic polymer and a cellulose ester polymer having a ring structure in a main chain, and has a low photoelastic coefficient and low moisture permeability, and control the wavelength dispersion of the phase difference. An object of the present invention is to provide a retardation film having a high degree of freedom (for example, exhibiting reverse wavelength dispersion of retardation or having a wavelength dispersion of retardation at least flat in the visible range).

The retardation film of this invention is a layer which consists of 30-95 weight% of (meth) acryl polymers (A) which have a ring structure in a principal chain, and the resin composition (C) containing 5-70 weight% of cellulose ester polymers (B). It includes.

The image display device of the present invention includes the retardation film of the present invention.

The retardation film of this invention contains the (meth) acryl polymer (A) which has a ring structure in a principal chain, and the layer which consists of a resin composition containing a cellulose polymer (B) in the range of a specific content rate, A photoelastic coefficient and water vapor transmission rate In addition to being low, a phase difference film having a high degree of freedom in controlling the wavelength dispersion of the phase difference is obtained.

1: is a top view which shows typically an example of the retardation film of this invention.

[(Meth) acrylic polymer (A)]

The (meth) acrylic polymer has a (meth) acrylic acid ester unit of 50% by weight or more, preferably 70% by weight or more, more preferably 90% by weight or more, particularly preferably 95% by weight or more of the entire structural unit, Most preferably, it is a polymer which has 99 weight% or more. The ring structure of the (meth) acryl polymer (A) in the main chain may be a derivative of the (meth) acrylic acid ester unit. In this case, if the sum total of a (meth) acrylic acid ester unit and a ring structure is 50 weight% or more of all the structural units, it will become a (meth) acryl polymer.

The (meth) acrylic acid ester unit is, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, (meth) N-hexyl acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, benzyl (meth) acrylate, dicyclopentanyl oxyethyl (meth) acrylate, dicyclopentanyl (meth) acrylate, (meth) acrylic acid Chloromethyl, 2-chloroethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2,3,4,5,6-pentahydroxyhexyl (meth) acrylate , (Meth) acrylic acid 2,3,4,5-tetrahydroxypentyl, methyl 2- (hydroxymethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, isopropyl 2- (hydroxymethyl) acrylate, 2 By polymerization of monomers such as-(hydroxymethyl) normal butyl acrylate and t-butyl 2- (hydroxymethyl) acrylate A structural unit property. The (meth) acryl polymer can have two or more types of these structural units. From the viewpoint of thermal stability, the (meth) acryl polymer (A) preferably has a methyl methacrylate (MMA) unit.

It is preferable that the (meth) acryl polymer (A) has the (meth) acrylic-acid alkylester unit X shown to the following formula (1) as a structural unit.

In the formula ^(1), R 1 is an alkyl group having a carbon number of ² ~ 18, R 2 is an H (hydrogen atom) or CH ₃ (a methyl group). When R <^2> is H, the unit shown by Formula (1) is an acrylic acid alkylester unit, and when R <^2> is CH <^3> , the unit shown by Formula (1) is a methacrylic acid alkylester unit.

When the resin composition containing the (meth) acrylic polymer and the cellulose ester polymer is molded, the haze of the surface is increased, and the transparency of the obtained molded article is sometimes lowered. Especially when this resin composition is shape | molded in a film, this tendency is remarkable. The film with reduced transparency cannot be used as a retardation film. When (meth) acryl polymer (A) contains the (meth) acrylic-acid alkylester unit X, such a raise of haze is suppressed and the retardation film excellent in transparency can be obtained.

R ¹ is not limited as long as it is an alkyl group having 2 to 18 carbon atoms. R ¹ is, for example, an ethyl group (2 carbon atoms), a propyl group (3 carbon atoms), a butyl group (4 carbon atoms), a pentyl group (5 carbon atoms), a hexyl group (6 carbon atoms), a heptyl group (7 carbon atoms), or jade. Tyl groups (8 carbon atoms), nonyl groups (9 carbon atoms), decyl groups (10 carbon atoms), undecyl groups (11 carbon atoms), and dodecyl groups (12 carbon atoms), and structural isomers thereof.

Although the ratio of the (meth) acrylic-acid alkylester unit X to all the structural units of a (meth) acryl polymer (A) changes with the specific molecular structure of the said unit X, it is 5 weight% or more, for example. Since the effect which suppresses a raise of a haze can be acquired reliably, 10 weight% or more is preferable and, as for the said ratio, 15 weight% or more is preferable. The upper limit of the said ratio is not specifically limited, For example, 50 weight%. (Meth) the ratio of (meth) acrylic acid alkyl ester unit X which occupies the whole structural units of the acrylic polymer (A) can be determined by ¹ H nuclear magnetic resonance ⁽¹ H-NMR) or infrared spectroscopy (IR). The said ratio can be calculated | required even if it references ratio of each monomer used for superposition | polymerization of a (meth) acryl polymer (A), and the reaction mechanism from a monomer to a (meth) acryl polymer (A) as needed. .

The (meth) acryl polymer (A) can have 2 or more types of (meth) acrylic-acid alkylester unit X as a structural unit.

The (meth) acryl polymer (A) may have structural units other than the (meth) acrylic acid ester unit. The said structural unit is (meth) acrylic acid, styrene, vinyltoluene, (alpha) -methylstyrene, (alpha)-hydroxymethylstyrene, (alpha)-hydroxyethyl styrene, acrylonitrile, methacrylonitrile, methacryl alcohol, for example. , Monomers such as allyl alcohol, ethylene, propylene, 4-methyl-1-pentene, vinyl acetate, 2-hydroxymethyl-1-butene, methyl vinyl ketone, N-vinylpyrrolidone, and N-vinylcarbazole It is a structural unit formed by.

It is preferable that a (meth) acryl polymer (A) has a (meth) acrylic-acid alkylester unit X, an MMA unit, and 2- (hydroxymethyl) acrylic acid ester unit as a structural unit. It is preferable that a (meth) acryl polymer (A) has a (meth) acrylic-acid alkylester unit X, an MMA unit, 2- (hydroxymethyl) acrylic acid ester unit, and an N-vinylcarbazole unit as a structural unit. In these cases, the rise of the haze is further suppressed, and high optical properties can be obtained when the retardation film is used. In these cases, 10-80 weight% is preferable and, as for the content rate of the MMA unit in a (meth) acryl polymer (A), 20-60 weight% is more preferable. 10-60 weight% is preferable and, as for the content rate of the 2- (hydroxymethyl) acrylic acid ester unit, 20-40 weight% is more preferable. 5-70 weight% is preferable and, as for the content rate of the unit X, 10-50 weight% is more preferable. 1-20 weight% is preferable and, as for the content rate of N-vinylcarbazole unit, 3-8 weight% is more preferable. The 2- (hydroxymethyl) acrylic acid ester unit is, for example, 2- (hydroxymethyl) methyl acrylate (MHMA) unit, 2- (hydroxymethyl) acrylic acid ethyl unit, 2- (hydroxymethyl) isoacrylate It is a propyl unit, the normal butyl unit of 2- (hydroxymethyl) acrylate, and the t-butyl unit of 2- (hydroxymethyl) acrylic acid. Especially, MHMA unit and ethyl 2- (hydroxymethyl) acrylic acid unit are preferable, and MHMA unit is especially preferable from a viewpoint of transparency and heat resistance of retardation film.

The (meth) acrylic polymer (A) has a ring structure in the main chain. The (meth) acrylic polymer (A) having a ring structure in the main chain contributes to showing a large in-plane retardation of the retardation film of the present invention and to suppressing the rise of haze.

In addition, the glass transition temperature (Tg) of the (meth) acryl polymer (A) which has a ring structure in a principal chain is high, for example, it is 110 degreeC or more, and 120 degreeC or more and 130 degreeC or more depending on the structure of the said polymer. . Thus, the heat resistance of the retardation film of this invention improves by including the (meth) acryl polymer (A) which has high Tg. Since the retardation film with high heat resistance can be disposed near a heat generating portion such as a light source, it is suitable for use in an image display device such as an LCD.

The content rate of the ring structure in a (meth) acryl polymer (A) becomes like this. Preferably it is 25 to 90 weight%, More preferably, it is 35 to 90 weight%, Especially preferably, it is 40 to 90 weight%. When the content rate of the ring structure in a polymer (A) exceeds 90 weight%, the moldability of the resin composition containing a polymer (A) may fall, and manufacture of retardation film may become difficult.

The ring structure which a (meth) acryl polymer (A) has in a main chain is a ring structure which has an ester group, an imide group, or an acid anhydride group, for example.

Examples of more specific ring structures are at least one selected from lactone ring structures, glutarimide structures, glutaric anhydride structures, N-substituted maleimide structures, and maleic anhydride structures. These ring structures have a large degree of contribution to the large in-plane retardation described above.

The ring structure is preferably at least one selected from a lactone ring structure and a glutarimide structure, and more preferably a lactone ring structure. The (meth) acryl polymer (A) which has a lactone ring structure or a glutarimide structure, especially a lactone ring structure in a principal chain has especially small birefringence wavelength dispersion. For this reason, the freedom degree of control of the wavelength dispersion of the phase difference in the retardation film of this invention becomes higher between flat wavelength dispersion and reverse wavelength dispersion. In addition, the (meth) acryl polymer (A) which has a lactone ring structure in a principal chain has especially high compatibility with a cellulose ester polymer (B). The high compatibility contributes to the suppression of the rise of haze.

The specific lactone ring structure that the (meth) acryl polymer (A) may have in the main chain is not particularly limited, and may be, for example, a 4-8 membered ring. However, since it is excellent in stability as a ring structure, the 5 or 6 membered ring It is preferable and it is more preferable that it is a 6-membered ring. The lactone ring structure which is a 6-membered ring is a structure disclosed by Unexamined-Japanese-Patent No. 2004-168882, for example. Having a high polymerization yield of the precursor ((meth) acryl polymer (A) having a lactone ring structure in the main chain by cyclization condensation of the precursor), and having a high lactone ring content rate by the cyclization condensation reaction of the precursor. The structure represented by following formula (2) is preferable from the reason which can obtain a (meth) acryl polymer (A), and can use the polymer which has an MMA unit as a structural unit for a precursor.

In Formula (2), R <^3> , R <^4> and R <^5> are mutually independent and are a hydrogen atom or an organic residue of the C1-C20 range. The organic residue may contain an oxygen atom.

The organic residue is, for example, an alkyl group having 1 to 20 carbon atoms such as methyl group, ethyl group, or propyl group; unsaturated aliphatic hydrocarbon group having 1 to 20 carbon atoms such as ethenyl group and propenyl group; phenyl group, naphthyl group An aromatic hydrocarbon group having 1 to 20 carbon atoms such as at least one of the alkyl group, the unsaturated aliphatic hydrocarbon group, and the aromatic hydrocarbon group, at least one hydrogen atom selected from hydroxyl, carboxyl, ether and ester groups It is group substituted by the group of;

The lactone ring structure shown in Formula (2) is formed by, for example, copolymerizing a monomer group containing MMA and MHMA, followed by dealcoholization condensation of adjacent MMA units and MHMA units in the obtained copolymer. Can be. At this time, R ³ is H, R ⁴ and R ⁵ is CH ₃ .

When (meth) acryl polymer (A) has a lactone ring structure in a principal chain, the content rate of the lactone ring structure in a polymer (A) is a viewpoint of compatibility with a cellulose ester polymer (B), especially a cellulose acetate polymer, 25-90 weight% is preferable, 25-70 weight% is more preferable, 30-60 weight% is especially preferable, 35-60 weight% is the most preferable. The content rate of the lactone ring structure in a (meth) acryl polymer (A) can be calculated | required by the method of Unexamined-Japanese-Patent No. 2001-151814.

80,000 or more are preferable and, as for the weight average molecular weight (Mw) of the (meth) acryl polymer (A), 100,000 or more are more preferable. 3.5 or less is preferable and, as for the dispersion degree (= weight average molecular weight Mw / number average molecular weight Mn) of the molecular weight in a (meth) acryl polymer (A), 3 or less are more preferable. Mw and dispersion degree of a (meth) acryl polymer (A) can be calculated | required by gel permeation chromatography (GPC). When the (meth) acrylic polymer (A) satisfies the range of Mw and dispersion degree, the branched structure of the polymer (A) is suppressed. This improves the thermal stability of the resin composition containing a polymer (A), and contributes to manufacture of the retardation film which has high intensity | strength and a favorable external appearance.

The (meth) acryl polymer (A) can be manufactured by a well-known method. The (meth) acrylic polymer (A) in which the ring structure of the main chain is glutaric anhydride structure or glutarimide structure can be produced, for example, by the method described in WO2007 / 26659 or WO2005 / 108438. . As for the (meth) acryl polymer (A) whose ring structure of a principal chain is a maleic anhydride structure or N-substituted maleimide structure, For example, Unexamined-Japanese-Patent No. 57-153008, Unexamined-Japanese-Patent No. 2007-31537 It can manufacture by the method as described in a publication. As for the (meth) acryl polymer (A) whose ring structure of a principal chain is a lactone ring structure, For example, Unexamined-Japanese-Patent No. 2006-96960, Unexamined-Japanese-Patent No. 2006-171464, or Unexamined-Japanese-Patent No. 2007-63541 It can manufacture by the method of Unexamined-Japanese-Patent.

As an example, the manufacturing method of the (meth) acryl polymer (A) which has a lactone ring structure in a principal chain is demonstrated. The said polymer (A) can be formed by heating the polymer (a) which has a hydroxyl group and ester group in a molecular chain in presence of arbitrary catalysts, and advances the lactone cyclization condensation reaction with dealcoholization.

The polymer (a) is formed by polymerization of a monomer group containing a monomer represented by the following formula (3), for example. When a polymer (A) has the (meth) acrylic-acid alkylester unit X shown in Formula (1) as a structural unit, the polymer (a) is a monomer represented by following formula (3) and the following formula, for example. It can form by superposition | polymerization of the monomer group containing the monomer shown in (4).

In Formula (3), R <^6> and R <^7> is group mutually independently and exemplified as a hydrogen atom or an organic residue in Formula (2). The monomer shown by Formula (3) gives a hydroxyl group and an ester group in the molecular chain of a polymer (a) by superposition | polymerization.

In Formula (4), R <^8> is the same group as R <^1> of Formula (1). In Formula (4), R ⁹ is H (hydrogen atom) or CH ₃ (methyl group). The monomer ((meth) acrylic-acid alkylester monomer Y) shown by Formula (4) turns into a (meth) acrylic-acid alkylester unit X by superposition | polymerization.

Specific examples of the monomer represented by the formula (3) include 2- (hydroxymethyl) methyl acrylate, 2- (hydroxymethyl) ethyl acrylate, 2- (hydroxymethyl) isopropyl acrylate and 2- (hydroxymethyl) Normal butyl acrylate and t-butyl 2- (hydroxymethyl) acrylate. Especially, methyl 2- (hydroxymethyl) acrylate and ethyl 2- (hydroxymethyl) acrylate are preferable, and 2- (hydroxymethyl) methyl acrylate (MHMA) is especially preferable from a viewpoint of transparency and heat resistance.

Specific examples of the monomer represented by formula (4) include ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, and (meth) acrylate. Octyl acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, and dodecyl (meth) acrylate.

The content rate of the monomer shown in Formula (3) and (4) in the monomer group used for formation of a polymer (a) can be adjusted with the molecular structure of a desired (meth) acryl polymer (A).

The monomer group used for formation of a polymer (a) can contain 2 or more types of monomers shown by Formula (3). The said monomer group can contain 2 or more types of monomers shown by Formula (4).

The monomer group used for formation of a polymer (a) can contain monomers other than the monomer shown to Formula (3), (4). Such monomer is not specifically limited as long as it is a monomer copolymerizable with the monomer shown to Formula (3), (4). The said monomer is (meth) acrylic acid ester other than the monomer shown, for example in Formula (3) and (4).

The said (meth) acrylic acid ester is acrylic acid esters, such as methyl acrylate, cyclohexyl acrylate, and benzyl acrylate; methacrylic acid ester, such as methyl methacrylate, cyclohexyl methacrylate, and benzyl methacrylate; In terms of transparency and heat resistance, MMA is preferred.

The monomer group used for formation of a polymer (a) can contain 2 or more types of these (meth) acrylic acid esters.

The monomer group used for formation of a polymer (a) is 1 type or 2 monomers, such as (meth) acrylic acid, styrene, vinyltoluene, (alpha) -methylstyrene, acrylonitrile, methylvinyl ketone, ethylene, propylene, and vinyl acetate. It may contain more than one species. However, 30 weight% or less is preferable, as for the content rate of (meth) acrylic acid in the said monomer group, 20 weight% or less is more preferable, 10 weight% or less is especially preferable, and 5 weight% or less is the most preferable. . When the content rate of (meth) acrylic acid exceeds 30 weight%, gelation may advance in the superposition | polymerization process of a monomer group.

At the time of formation of the polymer (a) by superposition | polymerization of a monomer group, a polymerization initiator can be used as needed. The polymerization initiator is, for example, cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-t-butyl peroxide, lauroyl peroxide, benzoyl peroxide, t-butylperoxy isopropyl carbonate, t-amyl Organic peroxides such as peroxy-2-ethylhexanoate; 2,2'-azobis (isobutyronitrile), 1,1'-azobis (cyclohexanecarbonitrile), 2,2'-azobis ( 2,4-dimethylvaleronitrile) and dimethyl 2,2'-azobisisobutyrate; A polymerization initiator can use 2 or more types together. The usage-amount of a polymerization initiator can be set suitably according to the combination of the monomer contained in a monomer group, and superposition | polymerization conditions.

It is preferable to use a well-known cyclization catalyst for lactone cyclization condensation reaction with dealcoholization in a polymer (a). The cyclization catalyst is, for example, an esterification catalyst or a transesterification catalyst such as p-toluenesulfonic acid. Organic carboxylic acids such as acetic acid, propionic acid, benzoic acid, acrylic acid and methacrylic acid can be used as the cyclization catalyst. For example, as disclosed in Japanese Patent Laid-Open No. 61-254608 and Japanese Patent Laid-Open No. 61-261303, a basic compound; an organic carboxylate such as zinc acetate; Can be used as

The cyclization catalyst may be an organophosphorus compound. The organophosphorus compound may be, for example, alkylaphosphonic acid or arylaphosphonic acid such as methylaphosphonic acid, ethylaphosphonic acid, or phenylaphosphonic acid (however, these are alkylphosphinic acid or arylphosphine which are tautomers). And monoesters or diesters thereof; dialkylphosphinic acid, diarylphosphinic acid or alkyl such as dimethylphosphinic acid, diethylphosphinic acid, diphenylphosphinic acid, phenylmethylphosphinic acid, phenylethylphosphinic acid, and the like; Arylphosphinic acid and esters thereof; alkylphosphonic acids or arylphosphonic acids such as methylphosphonic acid, ethylphosphonic acid, trifluoromethylphosphonic acid, and phenylphosphonic acid and monoesters or diesters thereof; methylaphosphinic acid and ethylafo Alkyl aphosphinic acid or aryl aphosphinic acid, such as spinic acid and phenyl aphosphinic acid, and esters thereof; methyl phosphite, ethyl phosphite, phenyl phosphite, dimethyl phosphite, Phosphite monoesters, diesters or triesters such as diethyl phosphate, diphenyl phosphite, trimethyl phosphite, triethyl phosphite, and prephenyl phosphite; methyl phosphate, ethyl phosphate, 2-ethylhexyl phosphate, isodecyl phosphate, lauryl phosphate, Stearyl phosphate, isostearyl phosphate, phenyl phosphate, dimethyl phosphate, diethyl phosphate, di-2-ethylhexyl phosphate, octyl phosphate, diisodecyl phosphate, dilauryl phosphate, distearyl phosphate, diisostearyl phosphate, Phosphoric acid monoesters, diesters or triesters such as diphenyl phosphate, trimethyl phosphate, triethyl phosphate, triisodecyl phosphate, trilauryl phosphate, tristearyl phosphate, triisostearyl phosphate and triphenyl phosphate; methylphosphine; Mono, di, or such as ethylphosphine, phenylphosphine, dimethylphosphine, diethylphosphine, diphenylphosphine, trimethylphosphine, triethylphosphine, triphenylphosphine, or the like. Li-alkyl (aryl) phosphine; alkyl (aryl) halogen phosphine, such as methyl dichloro phosphine, ethyl dichloro phosphine, phenyl dichloro phosphine, dimethyl chloro phosphine, diethyl chloro phosphine, diphenyl chloro phosphine; Methyl phosphine oxide, ethyl phosphine oxide, phenyl phosphine oxide, dimethyl phosphine oxide, diethyl phosphine oxide, diphenyl phosphine oxide, trimethyl phosphine oxide, triethyl phosphine oxide, triphenyl phosphine oxide, etc. Mono-, di-, or tri-alkyl (aryl) phosphines; halogenated tetraalkyl (aryl) phosphoniums such as tetramethyl phosphonium chloride, tetraethyl phosphonium chloride, and tetraphenyl phosphonium chloride; Two or more types of these organophosphorus compounds can be used together. Especially, since catalyst activity is high and colorability is low, alkyl (aryl) aphosphonic acid, phosphorous acid monoester or diester, phosphoric acid monoester or diester, and alkyl (aryl) phosphonic acid are preferable, and alkyl (aryl) apo Sonic acid, phosphorous acid monoester or diester, phosphoric acid monoester or diester is more preferable, and alkyl (aryl) aphosphonic acid, phosphoric acid monoester or diester is especially preferable.

It is also possible to use a basic cyclization catalyst. The cyclization catalyst is, for example, a compound of a Group 12 element described in JP2009-144112A, and a zinc compound is particularly preferable. The zinc compound is, for example, an organic zinc compound such as zinc acetate, zinc propionate or zinc octylate; an inorganic zinc compound such as zinc oxide, zinc chloride or zinc sulfate; an organic containing fluorine such as zinc trifluoromethanesulfonate Zinc compound;

When shape | molding the resin composition containing the obtained (meth) acryl polymer (A) to a film by the unreacted reactive group which remains in trace amounts even after lactone cyclization condensation reaction, foaming or crosslinking between polymers may generate | occur | produce. This phenomenon can be suppressed by adding the deactivator of a cyclization catalyst after a cyclization condensation reaction. Addition of a deactivator is effective also in order to suppress deterioration of the cellulose-ester polymer (B) which the said resin composition contains. As the cyclization catalyst, an acidic substance or a basic substance is often used. When the cyclization catalyst is an acidic substance, a basic deactivator is used, and when the cyclization catalyst is a basic substance, it is preferable to use an acidic deactivator. A basic deactivator is a metal carbonate, a metal complex, a metal oxide, a metal carbonate and a metal oxide are preferable, and a metal carboxylate is more preferable. The metal used for the deactivator is not limited so long as the physical properties of the resin composition are not impaired, and examples thereof include alkali metals such as lithium, sodium and potassium; alkaline earth metals such as magnesium, calcium, strontium and barium; zinc; Zirconium. The carboxylic acid constituting the metal carboxylate is, for example, a base acid, acetic acid, propionic acid, butyric acid, gil acetic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, lauric acid, myristic acid, and palmitic acid. , Stearic acid, vihenic acid, tridecanoic acid, pentadecanoic acid, heptadecanoic acid, lactic acid, malic acid, citric acid, suuric acid, malonic acid, succinic acid, fmaric acid, maleic acid, adipic acid. The organic component in a metal complex is acetylacetone, for example. The metal oxide is, for example, zinc oxide, calcium oxide, or magnesium oxide, and zinc oxide is preferable. Acidic deactivators are organic phosphoric acid compounds and carboxylic acids, for example. A deactivator can use 2 or more types together. The form of the deactivator is not limited, and may be in the form of a solid, powder, dispersion, suspension, aqueous solution, or the like.

[Cellulose ester polymer (B)]

A cellulose ester polymer (B) is not limited, For example, it is a cellulose aromatic carboxylic acid ester polymer and a cellulose fatty acid ester polymer. Since a retardation film excellent in optical characteristics can be obtained, the cellulose polymer (B) is preferably a cellulose lower fatty acid ester polymer. Lower fatty acid means a fatty acid having 5 or less carbon atoms. The cellulose lower fatty acid ester polymers are, for example, cellulose acetate, cellulose propionate, cellulose butyrate, and cellulose pivalate. The cellulose ester polymer (B) may be a cellulose mixed fatty acid ester polymer such as cellulose acetate propionate and cellulose acetate butyrate. In this case, both the film-forming property of the resin composition (C) containing the said cellulose polymer (B), and the mechanical property of the retardation film finally obtained are aimed at. From the viewpoint of compatibility with the (meth) acryl polymer (A), the cellulose ester polymer (B) is preferably cellulose acetate, in particular cellulose triacetate or cellulose acetate propionate.

50,000-150,000 are preferable, as for Mn of a cellulose-ester polymer (B), 5.50,000-120,000 are more preferable, and 60,000-100,000 are more preferable. 100,000-300,000 are preferable, as for Mw of a cellulose-ester polymer (B), 100,000-250,000 are more preferable, and 120,000-200,000 are more preferable. 1.3-5.5 are preferable, as for dispersion degree (= Mw / Mn) of the molecular weight in a cellulose-ester polymer (B), 1.5-5.0 are more preferable, 1.7-4.0 are more preferable, 2.0-3.5 are especially preferable Do.

A cellulose ester polymer (B) can be manufactured by a well-known method. For example, the hydroxyl group of a raw material cellulose can be manufactured by substituting an acetyl group, a propionyl group, and / or a butyl group by a conventional method using acetic anhydride, propionic anhydride, and / or butyric anhydride. In that case, the method of Unexamined-Japanese-Patent No. 10-45804 and Unexamined-Japanese-Patent No. 6-501040 is referred to. In addition, a raw material cellulose is not specifically limited, For example, it is a wood pulp and a cotton linter. The wood pulp may be a coniferous pulp or a broadleaf pulp, but the coniferous pulp is preferred. From a viewpoint of peelability at the time of forming into a film into a film, a cotton linter is preferable. Two or more types can be used for a cellulose-ester polymer (B).

[Resin composition (C)]

Resin composition (C) contains 30-95 weight% of (meth) acryl polymers (A) which have a ring structure in a principal chain, and 5-70 weight% of cellulose ester polymers (B). Resin composition (C), Preferably it contains 50 to 90 weight% of (meth) acrylic polymer (A) and 10 to 50 weight% of cellulose-ester polymer (B), More preferably, it is (meth) acryl polymer (A ) 70 to 90% by weight and 10 to 30% by weight of the cellulose ester polymer (B).

When the content rate of the (meth) acryl polymer (A) in a resin composition (C) becomes excessively large, the freedom degree of control of the wavelength dispersion property of the phase difference in the retardation film finally obtained falls. On the other hand, when the content rate of the cellulose-ester polymer (B) in a resin composition (C) becomes excessively large, the photoelastic coefficient and water vapor transmission rate of the retardation film finally obtained will become high.

Resin composition (C) can contain 2 or more types of (meth) acryl polymer (A) and / or 2 or more types of cellulose ester polymers (B).

As long as the resin composition (C) can acquire the effect of this invention, 40 weight is used for polymers other than a (meth) acryl polymer (A) and a cellulose-ester polymer (B) as a content rate in a resin composition (C). % Or less, preferably 10% by weight or less.

Examples of the polymer include olefin polymers such as polyethylene, polypropylene, ethylene-propylene copolymers, and poly (4-methyl-1-pentene); halogen-containing polymers such as vinyl chloride and chlorinated vinyl resins; polystyrene and styrene- Styrene polymers such as methyl methacrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene block copolymer; polyesters such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate; Polyamide, such as 6, nylon 66, nylon 610; polyacetal; polycarbonate; polyphenylene oxide; polyphenylene sulfide: polyether ether ketone; polyether nitrile; polysulfone; polyether sulfone; polyoxyphenziene; poly Amideimide;

In these polymers, since it is excellent in compatibility with the (meth) acryl polymer (A), especially the (meth) acryl polymer (A) which has a lactone ring structure in a principal chain, the structural unit derived from a vinyl cyanide monomer, and an aromatic vinyl monomer Copolymers containing a structural unit derived from the above, for example, a styrene-acrylonitrile copolymer are preferable.

Resin composition (C) can contain arbitrary materials as long as the effect of this invention can be acquired. Examples of the material include ultraviolet absorbers; antioxidants; light stabilizers, weather stabilizers, and heat stabilizers; stabilizers such as glass fibers and carbon fibers; near infrared absorbers; tris (dibromopropyl) phosphate and triallyl phosphate. Flame retardants, such as antimony oxide; antistatic agents represented by anionic, cationic, and nonionic surfactants; colorants such as inorganic pigments, organic pigments, and dyes; organic fillers, inorganic fillers; resin modifiers; antiblocking agents; mats Agent; acid supplement; metal deactivator; plasticizer; lubricant; rubber mass such as ASA and ABS. The content rate of these materials in a resin composition (C) is 0-5 weight%, for example, Preferably it is 0-2 weight%, More preferably, it is 0-0.5 weight%.

A ultraviolet absorber is a benzophenone type compound, a salicylate type compound, a benzoate type compound, a triazole type compound, and a triazine type compound, for example. The benzophenone compound is, for example, 2,4-dihydroxybenzophenone, 4-n-octyloxy-2-hydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxy Benzophenone, 2-hydroxy-4-n-octyloxybenzophenone, bis (5-benzoyl-4-hydroxy-2-methoxyphenyl) methane, 1,4-bis (4-benzoyl-3-hydroxy Phenone) -butane. The salicylate compound is, for example, p-t-butylphenyl salicylate. The benzoate compound is, for example, 2,4-di-t-butylphenyl-3 ', 5'-di-t-butyl-4'-hydroxybenzoate. The triazole-based compound is, for example, 2,2'-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol], 2 -(3,5-di-t-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-t-butylphenol, 2- [ 5-chloro (2H) -benzotriazol-2-yl] -4-methyl-6- (t-butyl) phenol, 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-tetrahydrophthalimylmethyl) phenol, methyl3- (3- (2H-benzotriazol-2-yl) -5-t-butyl-4-hydride Reaction product of oxyphenyl) propionate / polyethyleneglycol 300, 2- (2H-benzotriazol-2-yl) -6- (chain and branched dodecyl) -4-methylphenol, 2- (5-methyl- 2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5- Bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 3- (2H-benzotriazol-2-yl) -5- (1,1-dimethylethyl) -4-hydroxy-C7 -9 branched and straight chain alkyl esters. The triazine-based compound is, for example, 2,4-diphenyl-6- (2-hydroxy-4-methoxy phenyl) -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-butoxyphenyl) -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-bis (2,4-dimethylphenyl) -6- [2-hydroxy-4- (3-alkyloxy-2-hydroxypropyloxy) -5-α-cumylphenyl ] -S-tree Qin is a compound having a triazine skeleton and each, alkyloxy, e.g. octyloxy, nonyl oxy, di-hexyloxy-like long-chain alkyl-oxy group in. `` Cinuvin 1577 '' `` Cinubin 460 '' `` Cinubin 477 '' (all made by Chiba Specialty Chemicals) are marketed as a triazine-based ultraviolet absorber, and `` adecasuta LA-31 '' (product made by Asahi Telephone Co., Ltd.) as a triazole ultraviolet absorber ) Is commercially available.

Resin composition (C) can contain 2 or more types of ultraviolet absorbers. When a resin composition (C) contains a ultraviolet absorber, the content rate of the ultraviolet absorber in a resin composition (C) is not specifically limited. In the retardation film state, 0.01-25 weight% is preferable and, as for the content rate, 0.05-10 weight% is more preferable. When the content rate of an ultraviolet absorber becomes large too much, the mechanical property of the finally obtained retardation film may fall, or the retardation film may yellow.

Antioxidant is a hindered phenol type compound, a phosphorus type compound, and a sulfur type compound, for example. Resin composition (C) can contain 2 or more types of antioxidant.

The antioxidant may be a phenol-based compound, for example n-octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate or n-octadecyl-3- (3 , 5-di-t-butyl-4-hydroxy phenyl) acetate, n-octadecyl-3,5-di-t-butyl-4-hydroxybenzoate, n-hexyl-3,5-di-t -Butyl-4-hydroxyphenylbenzoate, n-dodecyl-3,5-di-t-butyl-4-hydroxyphenylbenzoate, neododecyl-3- (3,5-di-t-butyl 4-hydroxyphenyl) propionate, dodecyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, ethyl-α- (4-hydroxy-3,5 -Di-t-butylphenyl) isobutylate, octadecyl-α- (4-hydroxy-3,5-di-t-butylphenyl) isobutylate, octadecyl-α- (4-hydroxy-3 , 5-di-t-butyl-4-hydroxyphenyl) propionate, 2- (n-octylthio) ethyl-3,5-di-t-butyl-4-hydroxybenzoate, 2- (n -Octylthio) ethyl-3,5-di-t-butyl-4-hydroxyphenylacetate, 2- (n-octadecylthio) ethyl-3, 5-di-t-butyl-4-hydroxyphenylacetate, 2- (n-octadecylthio) ethyl-3,5-di-t-butyl-4-hydroxybenzoate, 2- (2-hydroxy Ethylthio) ethyl-3,5-di-t-butyl-4-hydroxybenzoate, diethylglycolbis- (3,5-di-t-butyl-4-hydroxy-phenyl) propionate, 2 -(n-octadecylthio) ethyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, stearamide-N, N-bis- [ethylene-3- (3 , 5-di-t-butyl-4-hydroxyphenyl) propionate], n-butylimino-N, N-bis- [ethylene-3- (3,5-di-t-butyl-4- Hydroxyphenyl) propionate], 2- (2-steloyloxyethylthio) ethyl-3,5-di-t-butyl-4-hydroxybenzoate, 2- (2-steloyloxyethyl Thio) ethyl-7- (3-methyl-5-t-butyl-4-hydroxyphenyl) heptanoate, 1,2-propylene glycol bis- [3- (3,5-di-t-butyl-4 -Hydroxyphenyl) propionate], ethylene glycol bis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) prop Cypionate], neopentyl glycol bis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], ethylene glycol bis- (3,5-di-t-butyl-4 -Hydroxyphenyl acetate), glycerin-1-n-octadecanoate 2,3-bis- (3,5-di-t-butyl-4-hydroxyphenylacetate), pentaerythritol tetrakis- [3 -(3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate], 1,1,1-trimethyrolethanetris [3- (3,5-di-t-butyl -4-hydroxyphenyl) propionate], sorbitol hexa- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2-hydroxyethyl-7- (3 -Methyl-5-t-butyl-4-hydroxyphenyl) propionate, 2-stealoyloxyethyl-7- (3-methyl-5-t-butyl-4-hydroxyphenyl) heptanoate, 1,6-n-hexanediolbis [(3 ', 5'-di-t-butyl-4-hydroxyphenyl) propionate], pentaerythritol tetrakis (3,5-di-t-butyl-4 Hydroxyhydrocinnamate), 3, 9-bis [1,1-dimethyl-2- [β- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] ethyl] -2,4,8,10-tetraoxaspiro [ 5, 5]-Undecan.

It is preferable to use the antioxidant (phenolic antioxidant) which consists of phenolic compounds in combination with a thioether antioxidant or a phosphoric acid antioxidant. The content rate of both antioxidants in a resin composition (C) is 0.01 weight% of each of a phenolic antioxidant and a thioether antioxidant based on the weight of a (meth) acryl polymer (A), for example. As mentioned above, each of a phenolic antioxidant and a phosphoric acid antioxidant is 0.025 weight% or more.

Thioether type antioxidant is pentaerythryl tetrakis (3-lauryl thio propionate), dilauryl-3,3'- thiodipropionate, dimyristyl-3,3'-, for example. Thiodipropionate and distearyl-3,3′-thiodipropionate.

Phosphoric acid antioxidants are, for example, tris (2,4-di-t-butylphenyl) phosphite, 2-[[2,4,8,10-tetrakis (1,1-dimethylethyl) dibenzo [D, f] [1,3,2] dioxaphosphine-6-yl] oxy] -N, N-bis [2-[[2,4,8,10-tetrakis (1,1dimethylethyl ) Dibenzo [d, f] [1,3,2] dioxaphosphine-6-yl] oxy] -ethyl] ethanamine, diphenyltridecyl phosphite, triphenyl phosphite, 2,2-methylene bis (4,6-di-t-butylphenyl) octylphosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritoldiphosphite, distearylpentaerythritoldiphosphite, cyclic neopentane Tetraylbis (2,6-di-t-butyl-4-methylphenyl) phosphite.

The content rate of the antioxidant in a resin composition (C) is not specifically limited, For example, it is 0 to 10 weight%, Preferably it is 0 to 5 weight%, More preferably, it is 0.01 to 2 weight%, More preferably, it is 0.05-1 weight%. If the content of the antioxidant is excessively large, the antioxidant may bleed out or silver streaks may occur when the retardation film is molded from the resin composition (C) by melt extrusion.

[Retardation film]

An example of the retardation film of this invention is shown in FIG. The retardation film (1) of this invention shown in FIG. 1 contains 30-95 weight% of (meth) acryl polymers (A) which have a ring structure in a principal chain, and 5-70 weight% of cellulose ester polymers (B) It consists of a layer which consists of a resin composition (C). Although the retardation film of this invention can be equipped with arbitrary layers other than the layer which consists of a resin composition (C) as needed, in order to acquire the effect of this invention more reliably, as shown in FIG. 1, a resin composition ( It is preferable that it consists of the layer which consists of C), ie, it consists of a resin composition (C). However, the layer may have a functional coating layer on its surface.

In the retardation film of this invention, the absolute value of the photoelastic coefficient with respect to the light of wavelength 590nm is 5x10 <^-12> Pa <^-1> or less, for example. The kind of the (meth) acryl polymer (A) and cellulose ester polymer (B) which the retardation film of this invention contains (the resin composition (C) contains), and the (meth) acryl polymer in the retardation film of this invention Depending on the content of (A) and the cellulose ester polymer (B), the absolute value is 4 × 10 ⁻¹² Pa ⁻¹ or less, and 3 × 10 ⁻¹² Pa ⁻¹ or less.

Although the in-plane phase difference Re which the retardation film of this invention shows depends on the extending | stretching state of the said film, it is 50 nm or more as a value per 100 micrometers in thickness of a film with respect to the light of wavelength 590nm. The kind of (meth) acrylic polymer (A) and cellulose ester polymer (B) which the retardation film of this invention contains, and the (meth) acrylic polymer (A) and cellulose ester polymer (B) in the retardation film of this invention. Depending on the content rate of, in-plane retardation Re is set to a value per 100 μm in thickness of the film, and is 140 nm or more, and 150 nm or more and 500 nm or less.

The degree of freedom of control of the wavelength dispersion of the retardation in the retardation film of the present invention is high, and for example, a retardation film showing the reverse wavelength dispersion of the retardation or the wavelength dispersion of the retardation is flat. As a specific example, the in-plane retardation Re (447), Re (590) and Re (750) for each light having a wavelength of 447, 590, and 750 nm is expressed by Equation 0.8≤Re (447) / Re (590) ≤1.2, And a phase difference film satisfying a relationship of 0.8 ≦ Re (750) / Re (590) ≦ 1.2. In the retardation film of the present invention, Re (447), Re (590) and Re (750) are represented by formula 0.8≤Re (447) / Re (590) ≤1.1, and 0.9≤Re (750) / Re (590). It is preferable to satisfy the relationship of ≤ 1.2, and more preferably to satisfy the relationship of Expressions 0.8 ≤ Re (447) / Re (590) ≤ 1.0 and 1.0 ≤ Re (750) / Re (590) ≤ 1.2.

The water vapor transmission rate per 100 micrometers in thickness of the retardation film of this invention is 300 g / m <2> * 24 hours or less as a value measured based on JISZ0208. The kind of (meth) acrylic polymer (A) and cellulose ester polymer (B) which the retardation film of this invention contains, and the (meth) acrylic polymer (A) and cellulose ester polymer (B) in the retardation film of this invention. Depending on the content of, the value is 250 g / m 2 · 24 hours or less, 200 g / m 2 · 24 hours or less, 150 g / m 2 · 24 hours or less, 130 g / m 2 · 24 hours or less, and 120 g / m 2 · 24 hours or less Becomes

The retardation film of this invention shows high heat resistance based on the (meth) acryl polymer (A) which has a ring structure in a principal chain, and the Tg is 110 degreeC or more, for example. The kind of (meth) acrylic polymer (A) and cellulose ester polymer (B) which the retardation film of this invention contains, and the (meth) acrylic polymer (A) and cellulose ester polymer (B) in the retardation film of this invention. Depending on the content rate of, Tg becomes 120 degreeC or more, 125 degreeC or more, and 130 degreeC or more.

The thickness of the retardation film of this invention is not specifically limited, For example, it is 10-500 micrometers, 20-300 micrometers is preferable and 30-100 micrometers is especially preferable.

As a value with respect to the light of wavelength 590nm, the Nz coefficient which the retardation film of this invention shows is less than 1.20, 1.15 or less are more preferable, 1.10 or less and 0.95 or more are more preferable. The Nz coefficient is a value represented by the formula Nz = (Rth / Re) + 0.5 when the in-plane retardation of the retardation film is Re and the retardation in the thickness direction is Rth.

As a value measured based on JISK7361-1, 85% or more is preferable, 90% or more is more preferable, and 91% or more of the total light transmittance of the retardation film of this invention is more preferable.

The haze of the retardation film of the present invention is preferably 5% or less, more preferably 3% or less, even more preferably 1% or less, as a value when the thickness is 50 μm measured according to JIS 7165.

In the retardation film of this invention, various functional coating layers can be formed in the surface of the layer which consists of a resin composition (C) as needed. The functional coating layer may be, for example, an antistatic layer; an adhesive layer such as an adhesive layer or an adhesive layer; an antiadhesive layer; an antiglare (nonglare) layer; an antifouling layer such as a photocatalytic layer; an antireflection layer; a hard coat layer; an ultraviolet ray shielding layer, a heat ray shielding Layer, electromagnetic wave shielding layer; gas barrier layer.

The use of the retardation film of this invention is not specifically limited, It can be used for the same use as the conventional retardation film. The retardation film of this invention is suitable for the optical compensation in image display apparatuses, such as LCD. In addition to the LCD, it can be used for various image display devices and optical devices.

The retardation film of this invention can be used in the state which bonded together, for example in combination with another optical member as needed.

Retardation film of this invention from a (meth) acryl polymer (A) and a cellulose ester polymer (B) before making it into a resin composition (C) or a resin composition (C) to a well-known film forming method and a film extending method It can manufacture. Specifically, for example, the resin composition (C) is molded into a film to form an original film (unstretched film), and the obtained original film is stretched.

The film molding method is, for example, a solution casting method (solution casting method), a melt extrusion method, a calender method, or a compression molding method. Especially, the solution casting method and the melt extrusion method are preferable.

The well-known uniaxial stretching method or the biaxial stretching method can be applied to the stretching method of an original film.

The melt extrusion method is, for example, a T-die method and an inflation method. In the T-die method, an original film wound in a roll shape can be obtained by arranging a T-die at the tip of the melt extruder and winding the film melt-extruded from the T-die. At this time, it is also possible to adjust the temperature and speed of winding, and to add extending | stretching (uniaxial stretching) to the extrusion direction of a film.

At the time of melt extrusion, it is preferable to devolatilize a volatile component from the vent part of a melt extruder. Moreover, at the time of melt extrusion, it is preferable to use together filtration of the resin composition by a polymer filter.

The solution cast method generally has (1) melting process, (2) softening process, and (3) drying process. A well-known method can be applied to each process.

The specific procedure of the dissolution step is not limited as long as a solution containing a (meth) acryl polymer (A) and a cellulose ester polymer (B) having a ring structure in the main chain can be obtained. Good solvents, such as methylene chloride, methyl acetate, dioxolane, can be used for the solvent in which both polymers are dissolved, and poor solvents, such as methanol, ethanol, butanol, can be used together. As long as it melt | dissolves a cellulose ester polymer (B), the polymerization solvent used at the time of superposing | polymerizing a (meth) acryl polymer (A) can be used.

A well-known solution coating method can be applied to a casting | flow_spread process. The said method is a coating method using a die coater, a doctor blade coater, a roll coater, a comma coater, a lip coater etc., for example.

The specific procedure of the drying step is not particularly limited as long as the film is formed by drying of the coating film formed by the casting step.

[Image display device]

The image display device of the present invention includes the retardation film of the present invention. For this reason, it becomes the image display apparatus which is excellent in image display characteristics, for example, high contrast and wide viewing angle.

The image display device of the present invention is, for example, an LCD.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples. This invention is not limited to the Example shown below.

[Average molecular weight]

The weight average molecular weight (Mw) and the number average molecular weight (Mn) were calculated | required by polystyrene conversion according to the following measurement conditions using gel permeation chromatography (GPC).

Measurement system: Plasticizer GPC system HLC-8220

Development solvent: Chloroform (made by Wako Pure Chemical Industries, Limited Express)

Solvent Flow Rate: 0.6mL / min

Standard sample: TSK standard polystyrene (plasticizer, PS- oligomer kit)

Measurement column configuration: plasticizer, TSK-GEL super HZM-M 6.0 × 150, 2 series connection

        Dosing agent, TSK-GEL super HZ-L 4.6 x 35, 1

Reference column configuration: plasticizer, TSK-GEL SuperH-RC 6.0 × 150, 2 serial connections

Column temperature: 40 ° C

[Glass transition temperature]

Glass transition temperature (Tg) was calculated | required based on JISK7121. Specifically from a DSC curve obtained by using a differential scanning calorimeter (manufactured by Rigaku, DSC-8230) and heating a sample of about 10 mg from room temperature to 200 ° C. under a nitrogen gas atmosphere, the temperature rising rate of 20 ° C./min. It evaluated by the viewpoint method. Α-alumina was used as a reference.

[Melt flow rate (MFR)]

MFR was calculated | required based on JISK6874, the test temperature was 240 degreeC, and the test load was 10 kg.

[Optical Properties of Retardation Film]

In-plane phase difference Re with respect to the light of wavelength 590nm in the produced retardation film, and phase difference Rth of the thickness direction used the retardation film and optical material inspection apparatus RETS-100 (made by Otsuka Electronics), Incident angle 40 It evaluated on condition of °. The in-plane phase difference Re is defined by the formula Re = (nx-ny) × d, and the phase difference Rth in the thickness direction is defined by the formula Rth = [(nx + ny) / 2-nz] × d, respectively. Here, nx is the refractive index of the slow-axis direction in a film plane, ny is the refractive index of the direction perpendicular | vertical to nx in a film surface, nz is the refractive index of the film thickness direction, d is the thickness (nm) of a film. The slow axis direction is a direction in which the refractive index is maximum in the film plane. The Nz coefficient of the produced retardation film was computed by the formula Nz coefficient = (Rth / Re) +0.5 from the value of Re and Rth calculated | required as mentioned above.

Apart from this, the in-plane retardation Re (447) and Re (750) with respect to the light of wavelength 447 nm and 750 nm in the produced retardation film were evaluated similarly, and the in-plane phase difference Re with respect to the light of the wavelength of 590 nm calculated | required above. By taking the ratio with 590, the values of Re (447) / Re (590) and Re (750) / Re (590) were obtained.

[Photoelastic coefficient Cd of retardation film]

The photoelastic coefficient with respect to the light of wavelength 590nm in the produced retardation film was evaluated using the lipsomator (made by JASCO, M-150). Specifically, the produced retardation film was cut into 20 mm x 50 mm with the stretching direction as the long side to be a measurement sample, and this was attached to the photoelastic measuring unit of the lipometa, and 5 to 25 N in parallel with the stretching direction. The three-point birefringence was measured while applying a stress load, and the slope of the birefringence with respect to the stress when light with a wavelength of 590 nm was used as the photoelastic coefficient.

[Moisture permeability]

The water vapor transmission rate of the produced retardation film was calculated | required based on JISZ0208 under the measurement conditions of 40 degreeC. In the following table | surfaces, the value converted into per 100 micrometers in thickness of retardation film is shown.

[Haze]

The haze of the produced retardation film was evaluated using the turbidity meter (made by Japan Coloring Industry, NDH5000). In addition, in the said turbidimeter, the measurement based on JISK7165 is performed. In the following tables, the value per 50 micrometers in thickness of a film is shown.

(Production Example 1)

6000 g of methyl methacrylate (MMA), 3000 g of 2- (hydroxymethyl) methyl acrylate (MHMA), meta in a 30 L (liter) reaction device equipped with a stirring device, a temperature sensor, a cooling tube, and a nitrogen inlet tube. 1000 g of normal butyl methacrylate (BMA) and 6667 g of a mixed solvent (weight ratio 9: 1) of methyl isobutyl ketone (MIBK) and methyl ethyl ketone (MEK) are added as a polymerization solvent, and it is made into nitrogen, and it makes it pass through nitrogen, and to 105 degreeC. It heated up. At the start of reflux at elevated temperature, 6.0 g of t-amylperoxyisononanoate (Arkema Yoshitomi, trade name: Leperox 570) was added as a polymerization initiator, and the t-amyl was added to 3315 g of the mixed solvent. While the solution which melt | dissolved 12.0 g of peroxy isonanoate was dripped over 3 hours, solution polymerization advanced under reflux of about 95-110 degreeC, and also aged for 4 hours. The polymerization reaction rate was 90.5% and the content rate of the MHMA unit in the obtained polymer was 29.7 weight%.

Next, 20 g of an octyl phosphate / dioctyl mixture (manufactured by Sakai Chemical, trade name: Phoslex A-8) was added to the obtained polymerization solution as a catalyst (cyclization catalyst) for the cyclization condensation reaction, and the mixture was refluxed at about 85 to 100 ° C. In the course of 2 hours, the cyclocondensation reaction proceeded. Further, after heating at 240 ° C. for 90 minutes in an autoclave pressurized at a maximum of about 2 MPa as a gauge pressure, the obtained polymerization solution was devolatilized and extruded in a vent type screw twin screw extruder to have a lactone ring structure in the main chain. A transparent (meth) acrylic polymer (A-1) was obtained. The weight average molecular weight of the polymer (A-1) was 13.4 million, MFR was 14.5 g / 10min, and Tg was 130 degreeC.

(Example 1)

90 parts by weight of the polymer (A-1) produced in Production Example 1, cellulose acetate propionate (B-1) [acetyl group substitution degree 2.5 wt%, hydroxyl group substitution degree 1.8 wt%, propionyl group substitution degree 46 weight%, number average molecular weight Mn = 6.3 million, 10 weight part of weight average molecular weight Mw = 17.5 million] are melt | dissolved in methylene chloride, and the obtained solution is stirred, and a polymer (A-1) and cellulose acetate propionate (B- 1) was mixed uniformly. Next, the obtained mixed solution was dried at 120 degreeC under reduced pressure for 1 hour, and 100 weight part of solid resin compositions were obtained.

Next, the obtained resin composition was press-molded at 220 degreeC with the press molding machine, and it was set as the film (unstretched film) of 126 micrometers in thickness. Next, the produced film was uniaxially stretched in the MD direction at a draw ratio twice and a draw temperature of 133 ° C by a tensile tester (manufactured by Instron) to obtain a stretched film (F1) having a thickness of 85 µm. The evaluation results of the stretched film (F1) are shown in Table 1 below.

(Example 2)

70 parts by weight of the polymer (A-1), 30 parts by weight of cellulose acetate propionate (B-1) were dissolved in methylene chloride, and a raw film having a thickness of 120 µm was prepared in the same manner as in Example 1. And stretched film (F2) with a thickness of 82 µm. The evaluation results of the stretched film (F2) are shown in Table 1 below.

(Example 3)

50 parts by weight of the polymer (A-1), 50 parts by weight of cellulose acetate propionate (B-1) were dissolved in methylene chloride, and an original film having a thickness of 118 µm was prepared in the same manner as in Example 1. And the stretched film (F3) with a thickness of 83 µm were obtained. The evaluation results of the stretched film (F3) are shown in Table 1 below.

(Comparative Example 1)

10 weight part of polymer (A-1), 90 weight part of cellulose acetate propionate (B-1) were melt | dissolved in methylene chloride, the original film of 104 micrometers in thickness, and extending | stretching temperature were made into 135 degreeC. A stretched film (F4) having a thickness of 72 µm was obtained in the same manner as in Example 1 except for the above. The evaluation results of the stretched film (F4) are shown in Table 1 below.

As shown in Table 1, compared with the stretched film of the comparative example 1, the stretched film of Examples 1-3 had low water vapor transmission rate and a photoelastic coefficient, the big in-plane phase difference was obtained, and the Nz coefficient was small. Moreover, the phase difference in the stretched film of Examples 1-3 showed flat wavelength dispersion or reverse wavelength dispersion.

(Production Example 2)

52 parts by weight of methyl methacrylate (MMA) and 2- (hydroxymethyl) methyl acrylate (MHMA) 30 to an internal 30 L (liter) reactor equipped with a stirring device, a temperature sensor, a cooling tube and a nitrogen inlet tube. Part by weight, 18 parts by weight of normal butyl methacrylate (BMA), and 67 parts by weight of a mixed solvent of methyl isobutyl ketone (MIBK) and methyl ethyl ketone (MEK) (weight ratio 9: 1) as a polymerization solvent were added thereto. It heated up to 105 degreeC, making it pass. When reflux with elevated temperature started, 0.06 parts by weight of t-amylperoxyisononanoate (manufactured by Arkema Yoshitomi, trade name: Leperox 570) was added as a polymerization initiator, and 33 parts by weight of the mixed solvent was used. While the solution which melt | dissolved 0.12 weight part of t-amyl peroxy isonano nanoate was dripped over 3 hours, solution polymerization was advanced under reflux of about 95-110 degreeC, and also aged for 4 hours.

Next, 0.2 weight part of an octyl phosphate / dioctyl mixture (made by Sakai Chemical, brand name: Phoslex A-8) is added to the obtained polymerization solution as a catalyst (cyclization catalyst) of a cyclization condensation reaction, and it is reflux of about 85-100 degreeC Under 2 hours, cyclization condensation reaction was performed. And it heated further at 240 degreeC for 90 minutes in the autoclave pressurized to the maximum about 2 Mpa as gauge pressure. Next, the obtained polymerization solution was subjected to a barrel temperature of 260 ° C, a rotational speed of 100 rpm, a reduced pressure of 13.3 to 400 hPa (10 to 300 mmHg), one number of rear vents, and four vent type screw twin screw extruders (φ = 30 mm and L / D = 40) were introduced at a processing rate of 2.0 kg / hr in terms of resin amount, and further the progress and devolatilization of the cyclization condensation reaction were further performed in the extruder. Thereafter, the polymer in the molten state was extruded from the extruder to obtain a pellet of the (meth) acrylic polymer (A-2) having a lactone ring structure in the main chain and having 18% by weight of the BMA unit as the precursor unit. . The weight average molecular weight of the polymer (A-2) was 12,600,000, and Tg was 123 degreeC. In addition, BMA units, the alkyl (meth) acrylate units represented by the formula (1), R ¹ is an n- butyl group, and a structural unit R ² are CH ₃ (methyl group).

(Production Example 3)

Except having made the amount of each monomer put into a reaction apparatus into 60 weight part of MMA, 30 weight part of MHMA, and 10 weight part of BMA, it carried out similarly to manufacture example 2, and has a lactone ring structure in a principal chain, The pellet of the (meth) acryl polymer (A-3) which has 10 weight% of was obtained. The weight average molecular weight of the polymer (A-3) was 13.4 million, and Tg was 130 degreeC.

(Production Example 4)

In the same manner as in Production Example 2 except that the amount of MMA in the reaction apparatus was 70 parts by weight and the amount of MHMA was 30 parts by weight without adding BMA to the reactor, the main chain had a lactone ring structure. The pellet of the (meth) acryl polymer (C-1) which does not have a structural unit shown to was obtained. The weight average molecular weight of the polymer (C-1) was 170,000, and Tg was 122 degreeC.

(Production Example 5)

Into a 30 L (liter) internal reactor equipped with a stirring device, a temperature sensor, a cooling tube and a nitrogen introduction tube, 24.5 parts by weight of MMA, 26 parts by weight of MHMA, 45 parts by weight of ethyl methacrylate (EMA), and N-vinyl 4.5 parts by weight of carbazole (NVCz) and a mixed solvent of 86.5 parts by weight of toluene and 3.5 parts by weight of methanol were added as a polymerization solvent, and the mixture was heated to 95 ° C while allowing nitrogen to pass through. When reflux with elevated temperature started, 0.01 part by weight of t-amylperoxy-2-ethylnucleoanoate (manufactured by Arkema Yoshitomi, trade name: Leperox 575) was added as a polymerization initiator, and 10 parts by weight of toluene was added. While the solution which dissolved 0.10 weight part of said t-amyl peroxy 2- hetylhexanoates was dripped over 8 hours, solution polymerization was advanced under reflux of about 90-100 degreeC, and also aged for 12 hours.

Next, 0.2 weight part of an octyl phosphate / dioctyl mixture (made by Sakai Chemical, brand name: Phoslex A-8) is added to the obtained polymerization solution as a catalyst (cyclization catalyst) of a cyclization condensation reaction, and it is reflux of about 80-100 degreeC Under 2 hours, cyclization condensation reaction was performed. And it heated further at 240 degreeC for 90 minutes in the autoclave pressurized to the maximum about 2 Mpa as gauge pressure. Next, the obtained polymerization solution is dried at 240 ° C. under reduced pressure for 1 hour, has a lactone ring structure in the main chain, and has a (meth) acrylic polymer (A-4) having EMA units of 45% by weight of all structural units. ) The weight average molecular weight of the polymer (A-4) was 170,000, and Tg was 122 degreeC. Further, EMA units, and (meth) acrylic acid ester units represented by formula (1), and R ¹ is an ethyl group, and the structural units R ² are CH ₃ (methyl group).

(Production Example 6)

The amount of each monomer to be added to the reaction apparatus was 44.5 parts by weight of MMA, 26 parts by weight of MHMA, 25 parts by weight of EMA and 4.5 parts by weight of NVCz. The (meth) acryl polymer (A-5) which has a unit 25weight% of all the structural units was obtained. The weight average molecular weight of the polymer (A-5) was 170,000, and Tg was 129 degreeC.

(Production Example 7)

A lactone ring structure was formed in the main chain in the same manner as in Production Example 5, except that 69.5 parts by weight of MMA, 26 parts by weight of MHMA, and 4.5 parts by weight of NVCz were used without adding EMA to the reactor. In addition, the (meth) acryl polymer (C-2) which does not have a structural unit shown in Formula (1) was obtained. The weight average molecular weight of polymer (C-2) was 16.3 million, and Tg was 138 degreeC.

(Preparation Example 8)

70 parts by weight of the polymer (A-2) produced in Production Example 2, cellulose acetate propionate (B-1) [acetyl group substitution degree 2.5 wt%, hydroxyl group substitution degree 1.8 wt%, propionyl group substitution degree 46 weight%, number average molecular weight Mn = 6.3 million, 30 weight part of weight average molecular weight Mw = 17.5 million] are melt | dissolved in methylene chloride, and the obtained solution is stirred, and a polymer (A-2) and cellulose acetate propionate (B- 1) was mixed uniformly. Next, the obtained mixed solution was dried at 120 degreeC under reduced pressure for 1 hour, and 100 weight part of solid resin compositions were obtained.

Next, the obtained resin composition was press-molded at 220 degreeC with the press molding machine, and the unstretched film which is 50 micrometers in thickness was obtained. The evaluation results of the obtained film are shown in Table 2 below.

(Preparation Example 9)

Unstretched film was obtained like manufacture example 8 except 50 weight part of polymers (A-2) and 50 weight part of cellulose acetate propionate (B-1) being mixed uniformly. The evaluation results of the obtained film are shown in Table 2 below.

(Preparation Example 10)

An unstretched film was obtained in the same manner as in Production Example 8 except that the polymer (A-3) produced in Production Example 3 was used instead of the polymer (A-2). The evaluation results of the obtained film are shown in Table 2 below.

(Preparation Example 11)

An unstretched film was obtained in the same manner as in Production Example 8 except that the polymer (C-1) produced in Production Example 4 was used instead of the polymer (A-2). The evaluation results of the obtained film are shown in Table 2 below.

(Production Example 12)

A non-stretched film was obtained in the same manner as in Production Example 8 except that the polymer (A-4) produced in Production Example 5 was used instead of the polymer (A-2). The evaluation results of the obtained film are shown in Table 2 below.

(Preparation Example 13)

A non-stretched film was obtained in the same manner as in Production Example 12 except that 50 parts by weight of the polymer (A-4) and 50 parts by weight of cellulose acetate propionate (B-1) were mixed uniformly. The evaluation results of the obtained film are shown in Table 2 below.

(Preparation Example 14)

An unstretched film was obtained in the same manner as in Production Example 8 except that the polymer (A-5) produced in Production Example 6 was used instead of the polymer (A-2). The evaluation results of the obtained film are shown in Table 2 below.

(Preparation Example 15)

A film was obtained in the same manner as in Production Example 8 except that the Polymer (C-2) produced in Production Example 7 was used instead of the polymer (A-2). The evaluation results of the obtained film are shown in Table 2 below.

As shown in Table 2, the film of the manufacture examples 8-10 and the manufacture examples 12-14 was small in haze, and was excellent in transparency compared with the film of manufacture examples 11 and 15. And the tendency for the haze of the produced film to become small was so large that the content rate of the BMA unit or EMA unit in a (meth) acryl polymer was large. In addition, depending on the composition of the (meth) acryl polymer (A) in the film of manufacture examples 8-10 and manufacture examples 12-14, and the content rate of the (meth) acryl polymer (A) in the produced film, The water vapor transmission rate and the photoelastic coefficient of the said film were lower than the water vapor transmission rate and the photoelastic coefficient of the films of manufacture examples 11 and 15.

(Example 4)

The unstretched film produced in Production Example 8 (however, the thickness of the film was 120 µm) was uniaxially in the MD direction at a draw ratio twice and a draw temperature of 128 ° C using a tensile tester (made by Instron). It extended and obtained the stretched film (retardation film) of 87 micrometers in thickness. The evaluation results of the obtained retardation film are shown in Table 3 below.

(Example 5)

A stretched film (retardation film) having a thickness of 85 µm was obtained in the same manner as in Example 4, except that the unstretched film produced in Production Example 9 (the thickness of the film was 120 µm). The evaluation results of the obtained retardation film are shown in Table 3 below.

(Example 6)

A stretched film having a thickness of 82 µm was produced in the same manner as in Example 4 except for using the unstretched film produced in Production Example 10 (the thickness of the film was 120 µm) and the stretching temperature of 133 ° C. Retardation film). The evaluation results of the obtained retardation film are shown in Table 3 below.

(Example 7)

A stretched film having a thickness of 86 µm was prepared in the same manner as in Example 4 except that the unstretched film produced in Production Example 12 (the thickness of the film was 123 µm) and the stretching temperature was 127 ° C. Retardation film). The evaluation results of the obtained retardation film are shown in Table 3 below.

(Example 8)

A stretched film (retardation film) having a thickness of 84 µm was obtained in the same manner as in Example 4, except that the unstretched film produced in Production Example 13 (the thickness of the film was 121 µm). The evaluation results of the obtained retardation film are shown in Table 3 below.

(Example 9)

A stretched film (retardation film) with a thickness of 87 µm was obtained in the same manner as in Example 4 except that the unstretched film produced in Production Example 14 (the thickness of the film was 126 µm). The evaluation results of the obtained retardation film are shown in Table 3 below.

As shown in Table 3, each retardation film produced in Examples 4-9 shows a large in-plane retardation Re and the positive retardation Rth of the thickness direction, and also has reverse wavelength dispersion with respect to the in-plane retardation Re. Indicated.

In addition, the haze which the retardation film produced in Examples 4-9 shows, and the haze which the stretched film produced by extending | stretching the unstretched film produced in Manufacturing Examples 11 and 15 like Example 4 and produced are the same film thickness. In conversion, it was the same as the haze which the unstretched film (production examples 8-15) before corresponding stretching is shown. Moreover, the stretched film which the photoelastic coefficient which the retardation film produced in Examples 4-9 shows, the moisture permeability per 100 micrometers in thickness, and the unstretched film produced in Production Examples 11 and 15 draw like Example 4 and produce The photoelastic coefficient and the water vapor transmission rate per 100 micrometers in thickness were the same as the photoelastic coefficient and water vapor transmission rate which the unstretched film (production examples 8-15) before a corresponding extending | stretching shows.

The present invention can be applied to other embodiments without departing from the intent and essential features thereof. Embodiment disclosed in this specification is explanatory at all points, and is not limited to this. The scope of the present invention is shown not by the above description but by the attached claim, and all the changes equivalent to a claim and an equivalent are included in it.

[Industrial Availability]

The retardation film of this invention can be used for various uses, such as a conventional retardation film, for example, various image display apparatuses and optical devices, including LCD.

Claims (9)

30-95 weight% of (meth) acrylic polymer (A) which has ring structure in a principal chain,
Retardation film containing the layer which consists of resin composition (C) containing 5-70 weight% of cellulose-ester polymers (B). The method according to claim 1,
Retardation film in which the said (meth) acryl polymer (A) has a (meth) acrylic-acid alkylester unit represented by following formula (1) as a structural unit.
[Formula 1]

In the formula ^(1), R 1 is an alkyl group having a carbon number of ² ~ 18, R 2 is H or CH _3. The method according to claim 2,
The retardation film in which the said (meth) acryl polymer (A) has the methyl methacrylate unit and 2- (hydroxymethyl) acrylic acid ester unit. The method according to claim 2,
The retardation film in which the said (meth) acryl polymer (A) has a methyl methacrylate unit, 2- (hydroxymethyl) acrylic acid ester unit, and N-vinylcarbazole unit. The method according to claim 1,
The retardation film in which the said (meth) acryl polymer (A) has a methyl methacrylate unit. The method according to claim 1,
The retardation film whose absolute value of the photoelastic coefficient with respect to the light of wavelength 590nm is 5 * 10 <^-12> Pa <^-1> or less. The method according to claim 1,
In-plane retardation Re (447), Re (590) and Re (750) for the respective light of wavelengths 447, 590 and 750 nm,
0.8 ≦ Re (447) / Re (590) ≦ 1.2, and
0.8≤Re (750) / Re (590) ≤1.2
Retardation film that satisfies the relationship. The method according to claim 1,
The retardation film whose haze at the time of 50 micrometers in thickness measured based on JISK7165 is 5% or less. The image display apparatus provided with the retardation film of any one of Claims 1-8.

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