CN102939550A

CN102939550A - Retardation film and image display device provided with same

Info

Publication number: CN102939550A
Application number: CN2011800270749A
Authority: CN
Inventors: 大西隆司; 中昭夫
Original assignee: Nippon Shokubai Co Ltd
Current assignee: Nippon Shokubai Co Ltd
Priority date: 2010-06-03
Filing date: 2011-06-02
Publication date: 2013-02-20
Anticipated expiration: 2031-06-02
Also published as: WO2011152060A1; KR20130096215A; KR101771768B1; CN102939550B

Abstract

The disclosed retardation film contains a layer comprising a resin composition containing 30-95 wt% of a (meth)acrylate polymer having a ring structure at the backbone, and 5-70 wt% of a cellulose ester polymer. The retardation film has low moisture permeability and a low photoelastic coefficient, and has a high degree of freedom of controlling retardation wavelength dispersion; for example the film exhibits a retardation reverse wavelength dispersion, or has a flat retardation wavelength dispersion. The retardation film is suitable for optical compensation applications in an image display device such as a liquid crystal display (LCD) device.

Description

Phase retardation film and the image display device that possesses this phase retardation film

Technical field

The present invention relates to phase retardation film and the image display device that possesses this film.

Background technology

In the past, used cellulose-based polymkeric substance with the blooming headed by polarizer protection film and the phase retardation film.Different from the phase retardation film that is made of general polymkeric substance such as polycarbonate, the phase retardation film that is made of cellulose-based polymkeric substance demonstrates the less wavelength dispersibility of the shorter then phase differential of light wavelength (the anti-wavelength dispersibility of phase differential) usually at least in the visible region.Thus, can expect to possess the raising of the image display feature in the liquid crystal indicator (LCD) of this phase retardation film.But origin is in the characteristic of cellulose-based polymkeric substance, and this phase retardation film has the problem that moisture-penetrability height, photoelastic coefficient are large, may not necessarily access enough large phase differential.

Different therewith, in phase retardation film, used main chain to have (methyl) acrylate copolymer of ring structure (with reference to patent documentation 1: TOHKEMY 2008-9378 communique).The phase retardation film that is had (methyl) acrylate copolymer formation of ring structure by main chain has high transparent and thermotolerance, and mechanical property, the particularly flexible aspect of guaranteeing have problems on the other hand.The mechanical property of this phase retardation film is improved by interpolation or the stretching of the elastomer particles of rubber and so on.But, in the situation of having added elastomer particles, must suppress the cohesion of the particle that adds, to guarantee the transparency as phase retardation film.In addition, same with the phase retardation film that is made of general polymkeric substance, the phase retardation film that is had (methyl) acrylate copolymer formation of ring structure by main chain demonstrates the larger wavelength dispersibility of the shorter then phase differential of light wavelength (the positive wavelength dispersibility of phase differential) at least in the visible region.

In patent documentation 2 (TOHKEMY 2009-1744 communique), put down in writing: it is useful as the modifier of cellulose ester membrane that main chain has (methyl) acrylate copolymer of ring structure; Add in the cellulose ester membrane by (methyl) acrylate copolymer that main chain is had ring structure, can suppress to be transferred as with horseback shape fault (horseback fault), volume core the distortion fault of this film of representative; Example as cellulose ester membrane has phase retardation film.But, in the TOHKEMY 2009-1744 communique not record (methyl) acrylate copolymer of main chain being had a ring structure with which kind of degree add in the cellulose ester membrane as modifier and get final product, unique example that adds these (methyl) acrylate copolymer 4 weight～12 weight portions in the 100 weight portion cellulose esters of only having put down in writing in an embodiment.

The prior art document

Patent documentation

Patent documentation 1: TOHKEMY 2008-9378 communique

Patent documentation 2: TOHKEMY 2009-1744 communique

Summary of the invention

The problem that invention will solve

The object of the present invention is to provide a kind of phase retardation film, described phase retardation film is the phase retardation film that comprises the layer that is made of resin combination, described resin combination comprises (methyl) acrylate copolymer and the cellulose ester polymer that main chain has ring structure, photoelastic coefficient and the moisture permeability of described phase retardation film are low, the degree of freedom of the control of the wavelength dispersibility of phase differential high (for example, can show that the wavelength dispersibility of the anti-wavelength dispersibility of phase differential or phase differential at least can be smooth in the visible region) simultaneously.

For the scheme of dealing with problems

Phase retardation film of the present invention comprises the layer that is made of resin combination (C), and described resin combination (C) comprises (methyl) acrylate copolymer (A) 30 % by weight that main chain has ring structure～95 % by weight and cellulose ester polymer (B) 5 % by weight～70 % by weight.

Image display device of the present invention possesses the phase retardation film of the invention described above.

The invention effect

Phase retardation film of the present invention comprises the layer that is made of resin combination, described resin combination comprises (methyl) acrylate copolymer (A) and the cellulosic polymer (B) that main chain has ring structure in the scope of certain content, become thus low, the high phase retardation film of degree of freedom of the control of the wavelength dispersibility of phase differential simultaneously of photoelastic coefficient and moisture permeability.

Description of drawings

Fig. 1 is the vertical view of an example of schematically illustrated phase retardation film of the present invention.

Embodiment

[(methyl) acrylate copolymer (A)]

(methyl) acrylate copolymer be have 50 % by weight of entire infrastructure unit above, be preferably 70 % by weight above, more preferably 90 % by weight above, be particularly preferably the polymkeric substance that 95 % by weight are above, most preferably be above (methyl) acrylic ester unit of 99 % by weight.(methyl) acrylate copolymer (A) can be the derivant of (methyl) acrylic ester unit at the ring structure that main chain has.In this case, if more than 50 % by weight that add up to the entire infrastructure unit of (methyl) acrylic ester unit and ring structure, then become (methyl) acrylate copolymer.

(methyl) acrylic ester unit is for passing through for example (methyl) methyl acrylate, (methyl) ethyl acrylate, (methyl) acrylic acid n-propyl, (methyl) n-butyl acrylate, (methyl) tert-butyl acrylate, the just own ester of (methyl) acrylic acid, (methyl) cyclohexyl acrylate, (methyl) acrylic acid-2-ethyl caproite, (methyl) benzyl acrylate, (methyl) acrylic acid two cyclopentyloxy ethyl esters, (methyl) acrylic acid two ring pentyl esters, (methyl) acrylic acid chloromethyl ester, (methyl) acrylic acid-2-chloroethene ester, (methyl) 2-Hydroxy ethyl acrylate, (methyl) acrylic acid-3-hydroxy propyl ester, (methyl) acrylic acid-2,3,4,5, the own ester of 6-penta hydroxy group, (methyl) acrylic acid-2,3,4,5-tetrahydroxy pentyl ester, 2-(hydroxymethyl) methyl acrylate, 2-(hydroxymethyl) ethyl acrylate, 2-(hydroxymethyl) isopropyl acrylate, 2-(hydroxymethyl) n-butyl acrylate, the formed structural unit of polymerization of the monomers such as 2-(hydroxymethyl) tert-butyl acrylate.(methyl) acrylate copolymer can have these two or more structural units.From the aspect of thermal stability, (methyl) acrylate copolymer (A) preferably has methyl methacrylate (MMA) unit.

(methyl) acrylate copolymer (A) preferably has (methyl) acrylic acid alkyl ester units X shown in the following formula (1) as structural unit.

[Chemical formula 1]

In the formula (1), R ¹That carbon number is 2～18 alkyl, R ²H (hydrogen atom) or CH ₃(methyl).R ²During for H, the unit shown in the formula (1) is the acrylic acid alkyl ester units, R ²Be CH ₃The time, the unit shown in the formula (1) is the alkyl methacrylate unit.

If will comprise the resin combination moulding of (methyl) acrylate copolymer and cellulose ester polymer, then the mist degree on surface improves, and the transparency of resulting formed body often reduces.Particularly, when this resin combination was shaped to film, this tendency significantly.The film that the transparency reduces can't use as phase retardation film.(methyl) acrylate copolymer (A) can suppress the rising of this mist degree in the situation that comprises (methyl) acrylic acid alkyl ester units X, obtain the excellent phase retardation film of the transparency.

R ¹So long as that carbon number is 2～18 alkyl is then unqualified.R ¹For example be ethyl (carbon number is 2), propyl group (carbon number is 3), butyl (carbon number is 4), amyl group (carbon number is 5), hexyl (carbon number is 6), heptyl (carbon number is 7), octyl group (carbon number is 8), nonyl (carbon number is 9), decyl (carbon number is 10), undecyl (carbon number is 11) and dodecyl (carbon number is 12) and their constitutional isomer.

The shared ratio of (methyl) acrylic acid alkyl ester units X is different because of the concrete molecular structure of this unit X in the entire infrastructure unit of (methyl) acrylate copolymer (A), for example is more than 5 % by weight.The effect that mist degree rises owing to can positively be inhibited, thereby this ratio is preferably more than 10 % by weight, is preferably more than 15 % by weight.The upper limit to this ratio is not particularly limited, and for example is 50 % by weight.The shared ratio of (methyl) acrylic acid alkyl ester units X is passed through in the entire infrastructure unit of (methyl) acrylate copolymer (A) ¹The H nuclear magnetic resonance ( ¹H-NMR) or infrared spectroscopic analysis (IR) obtain.This ratio can be by the ratio of each monomer that uses in the polymerization of (methyl) acrylate copolymer (A) and as required with reference to obtaining to forming the reaction mechanism of (methyl) acrylate copolymer (A) from monomer.

(methyl) acrylate copolymer (A) can have (methyl) acrylic acid alkyl ester units X more than 2 kinds as structural unit.

(methyl) acrylate copolymer (A) can have the structural unit except (methyl) acrylic ester unit.This structural unit is the structural unit that the polymerization by monomers such as (methyl) acrylic acid, styrene, vinyltoluene, α-methyl styrene, Alpha-hydroxy methyl styrene, Alpha-hydroxy ethyl styrene, vinyl cyanide, methacrylonitrile, methallyl alcohol, allyl alcohol, ethene, propylene, 4-methyl-1-pentene, vinyl acetate, 2-hydroxymethyl-1-butylene, methyl vinyl ketone, NVP, N-vinylcarbazole forms.

(methyl) acrylate copolymer (A) preferably has (methyl) acrylic acid alkyl ester units X, MMA unit and 2-(hydroxymethyl) acrylic ester unit as structural unit.(methyl) acrylate copolymer (A) preferably has (methyl) acrylic acid alkyl ester units X, MMA unit, 2-(hydroxymethyl) acrylic ester unit and N-vinylcarbazole unit as structural unit.In these situations, further suppress the rising of mist degree, when making phase retardation film, can obtain high optical characteristics simultaneously.In these situations, the content of the MMA unit in (methyl) acrylate copolymer (A) is preferably 10 % by weight～80 % by weight, 20 % by weight～60 % by weight more preferably.The content of 2-(hydroxymethyl) acrylic ester unit is preferably 10 % by weight～60 % by weight, 20 % by weight～40 % by weight more preferably.The content of unit X is preferably 5 % by weight～70 % by weight, 10 % by weight～50 % by weight more preferably.The content of N-vinylcarbazole unit is preferably 1 % by weight～20 % by weight, 3 % by weight～8 % by weight more preferably.2-(hydroxymethyl) acrylic ester unit for example is 2-(hydroxymethyl) methyl acrylate (MHMA) unit, 2-(hydroxymethyl) ethyl acrylate unit, 2-(hydroxymethyl) isopropyl acrylate unit, 2-(hydroxymethyl) n-butyl acrylate unit, 2-(hydroxymethyl) tert-butyl acrylate unit.Wherein, preferred MHMA unit, 2-(hydroxymethyl) ethyl acrylate unit are from the transparency and the stable on heating aspect of phase retardation film, particularly preferably MHMA unit.

(methyl) acrylate copolymer (A) has ring structure at main chain.(methyl) acrylate copolymer (A) has the rising that ring structure helps phase retardation film of the present invention to demonstrate phase differential in the large face and suppress mist degree at main chain.

In addition, main chain has glass transition temperature (Tg) height of (methyl) acrylate copolymer (A) of ring structure, for example is more than 110 ℃, according to the difference of the formation of this polymkeric substance, is more than 120 ℃ and then is more than 130 ℃.By comprising (methyl) acrylate copolymer (A) that has so high Tg, the thermotolerance of phase retardation film of the present invention improves.The phase retardation film that thermotolerance is high can be disposed at light source and so on radiating part near, therefore be suitable for the image display devices such as LCD.

The content of the ring structure in (methyl) acrylate copolymer (A) be preferably 25 % by weight～90 % by weight, more preferably 35 % by weight～90 % by weight, be particularly preferably 40 % by weight～90 % by weight.If the content of the ring structure in the polymkeric substance (A) surpasses 90 % by weight, the mouldability that then comprises the resin combination of polymkeric substance (A) reduces, and sometimes is difficult to make phase retardation film.

The ring structure that (methyl) acrylate copolymer (A) has at main chain is to have for example ring structure of ester group, imide or anhydride group.

The example of ring structure is to be selected from least a in lactonic ring structure, glutarimide structure, glutaric anhydride structure, N-substituted maleimide amine structure and the maleic anhydride structure more specifically.These ring structures are large for the degree of the help of phase differential in the above-mentioned large face.

Ring structure is preferably and is selected from least a in lactonic ring structure and the glutarimide structure, more preferably the lactonic ring structure.The birefringent wavelength dispersibility of (methyl) acrylate copolymer (A) that main chain has lactonic ring structure or glutarimide structure, particularly lactonic ring structure is especially little.Therefore, the degree of freedom of the control of the wavelength dispersibility of the phase differential in the phase retardation film of the present invention is becoming higher from smooth wavelength dispersibility between the anti-wavelength dispersibility.In addition, to have the compatibility of lactonic ring structure (methyl) acrylate copolymer (A) and cellulose ester polymer (B) high especially for main chain.High-compatibility helps to suppress the rising of mist degree.

(methyl) acrylate copolymer (A) is not particularly limited in the concrete lactonic ring structure that main chain can have, for example can be 4～8 yuan of rings, because as the excellent in stability of ring structure, thereby be preferably 5 yuan of rings or 6 yuan of rings, 6 yuan of rings more preferably.The lactonic ring structure example of 6 yuan of rings is as being the disclosed structure of TOHKEMY 2004-168882 communique.Because following reason, the structure shown in the preferred following formula (2): the polymerization yield of precursor (carry out cyclized condensation reaction by making precursor, obtain (methyl) acrylate copolymer (A) that main chain has the lactonic ring structure) is high; Obtain having (methyl) acrylate copolymer (A) of high lactonic ring content by the cyclized condensation reaction of precursor; Can be used for precursor with having the polymkeric substance of MMA unit as structural unit; Etc..

[Chemical formula 2]

In the formula (2), R ³, R ⁴And R ⁵Be hydrogen atom or carbon number independently of each other at organic residue of 1～20 scope.Organic residue can comprise oxygen atom.

Organic residue is such as being that the carbon numbers such as methyl, ethyl, propyl group are the alkyl of 1～20 scope; The carbon number such as vinyl, propenyl is the unsaturated fatty hydrocarbons base of 1～20 scope; The carbon number such as phenyl, naphthyl is the aromatic hydrocarbyl of 1～20 scope; In abovementioned alkyl, above-mentioned unsaturated fatty hydrocarbons base and the above-mentioned aromatic hydrocarbyl, more than one hydrogen atom is selected from the group that at least a group replaced in hydroxyl, carboxyl, ether and the ester group.

Lactonic ring structure example shown in the formula (2) is if after the set of monomers copolymerization that will comprise MMA and MHMA, makes adjacent MMA unit in the resulting multipolymer and MHMA unit dealcoholysis cyclizative condensation and forms.At this moment, R ³Be H, R ⁴And R ⁵Be CH ₃

(methyl) acrylate copolymer (A) has in the situation of lactonic ring structure at main chain, from with the aspect of the compatibility of cellulose ester polymer (B), particularly cellulose acetate polymers, the content of the lactonic ring structure in the polymkeric substance (A) be preferably 25 % by weight～90 % by weight, more preferably 25 % by weight～70 % by weight, be particularly preferably 30 % by weight～60 % by weight, most preferably be 35 % by weight～60 % by weight.The content of the lactonic ring structure in (methyl) acrylate copolymer (A) can be obtained according to the method that TOHKEMY 2001-151814 communique is put down in writing.

The weight-average molecular weight (Mw) of (methyl) acrylate copolymer (A) is preferably more than 80,000, more preferably more than 100,000.The dispersion degree of the molecular weight in (methyl) acrylate copolymer (A) (=weight-average molecular weight Mw/ number-average molecular weight Mn) is preferably below 3.5, more preferably below 3.The Mw of (methyl) acrylate copolymer (A) and dispersion degree can be obtained by gel permeation chromatography (GPC).When (methyl) acrylate copolymer (A) satisfied the scope of above-mentioned Mw and dispersion degree, the branched structure of this polymkeric substance (A) was suppressed.The thermal stability that this has improved the resin combination that comprises polymkeric substance (A) helps to have the manufacturing of the phase retardation film of high strength and desired outward appearance.

(methyl) acrylate copolymer (A) can utilize known method manufacturing.The ring structure of main chain is the method manufacturing that (methyl) acrylate copolymer (A) of glutaric anhydride structure or glutarimide structure for example can utilize WO2007/26659 communique or WO2005/108438 communique to put down in writing.The ring structure of main chain is the method manufacturing that (methyl) acrylate copolymer (A) of maleic anhydride structure or N-substituted maleimide amine structure for example can utilize Japanese kokai publication sho 57-153008 communique, TOHKEMY 2007-31537 communique to put down in writing.The ring structure of main chain is the method manufacturing that lactonic ring structure (methyl) acrylate copolymer (A) for example can utilize TOHKEMY 2006-96960 communique, TOHKEMY 2006-171464 communique or TOHKEMY 2007-63541 communique to put down in writing.

As an example, the manufacture method that main chain is had (methyl) acrylate copolymer (A) of lactonic ring structure describes.The polymkeric substance (a) that has hydroxyl and ester group in to strand in the presence of catalyzer arbitrarily heats, and follows the lactone cyclized condensation reaction of dealcoholysis, thereby can form this polymkeric substance (A).

Polymkeric substance (a) for example polymerization of the set of monomers by comprising the monomer shown in the following formula (3) forms.Polymkeric substance (A) has in the situation of (methyl) acrylic acid alkyl ester units X as structural unit shown in the formula (1), and the polymerization of the set of monomers that polymkeric substance (a) for example can be by comprising the monomer shown in the monomer shown in the following formula (3) and the following formula (4) forms.

[chemical formula 3]

In the formula (3), R ⁶And R ⁷Be hydrogen atom or as the illustrated group of organic residue in the formula (2) independently of each other.Monomer shown in the formula (3) provides hydroxyl and ester group in the strand to polymkeric substance (a) by polymerization.

[chemical formula 4]

In the formula (4), R ⁸The R with formula (1) ¹Same group.In the formula (4), R ⁹Be H (hydrogen atom) or CH ₃(methyl).Monomer shown in the formula (4) ((methyl) alkyl acrylate monomer Y) is (methyl) acrylic acid alkyl ester units X by being polymerized.

The concrete example of the monomer shown in the formula (3) is 2-(hydroxymethyl) methyl acrylate, 2-(hydroxymethyl) ethyl acrylate, 2-(hydroxymethyl) isopropyl acrylate, 2-(hydroxymethyl) n-butyl acrylate, 2-(hydroxymethyl) tert-butyl acrylate.Wherein, preferred 2-(hydroxymethyl) methyl acrylate, 2-(hydroxymethyl) ethyl acrylate are from the transparency and stable on heating aspect, particularly preferably 2-(hydroxymethyl) methyl acrylate (MHMA).

The concrete example of the monomer shown in the formula (4) is (methyl) ethyl acrylate, (methyl) propyl acrylate, (methyl) butyl acrylate, (methyl) acrylic acid pentyl ester, (methyl) Hexyl 2-propenoate, (methyl) acrylic acid heptyl ester, (methyl) acryllic acid monooctyl ester, (methyl) acrylic acid ester in the ninth of the ten Heavenly Stems, (methyl) decyl acrylate, (methyl) acrylic acid undecyl ester, (methyl) dodecylacrylate.

The formula (3), the content of the monomer shown in (4) of set of monomers that is used for the formation of polymkeric substance (a) can be adjusted according to the molecular structure of desired (methyl) acrylate copolymer (A).

The set of monomers that is used for the formation of polymkeric substance (a) can comprise the monomer shown in the formula (3) more than 2 kinds.This set of monomers can comprise the monomer shown in the formula (4) more than 2 kinds.

The set of monomers that is used for the formation of polymkeric substance (a) can comprise the monomer except the monomer shown in formula (3), (4).Such monomer so long as can with the monomer of the monomer copolymerization shown in formula (3), (4), then be not particularly limited.This monomer for example is (methyl) acrylate except the monomer shown in formula (3), (4).

Be somebody's turn to do (methyl) acrylate such as being the acrylate such as methyl acrylate, cyclohexyl acrylate, benzyl acrylate; The methacrylates such as methyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate.From the transparency and stable on heating aspect, be preferably MMA.

The set of monomers that is used for the formation of polymkeric substance (a) can comprise these (methyl) acrylate more than 2 kinds.

The set of monomers that is used for the formation of polymkeric substance (a) can comprise the one kind or two or more of the monomers such as (methyl) acrylic acid, styrene, vinyltoluene, α-methyl styrene, vinyl cyanide, methyl vinyl ketone, ethene, propylene, vinyl acetate.Wherein, (methyl) the acrylic acid content in this set of monomers be preferably 30 % by weight following, more preferably 20 % by weight following, be particularly preferably 10 % by weight following, most preferably be below 5 % by weight.If (methyl) acrylic acid content surpasses 30 % by weight, then in the polymerization process of set of monomers, carry out sometimes gelation.

When forming polymkeric substance (a) in the polymerization that utilizes set of monomers, as required, can use polymerization initiator.Polymerization initiator is such as being cumene hydroperoxide, di-isopropylbenzene hydroperoxide, di-tert-butyl peroxide, lauroyl peroxide, benzoyl peroxide, tert-butylperoxy isopropyl carbonate, the peroxidating tertiary pentyl-organic peroxides such as 2 ethyl hexanoic acid ester; 2,2 '-azo two (isobutyronotrile), 1,1 '-azo two (cyclohexane formonitrile HCN), 2,2 '-azo two (2,4-methyl pentane nitrile), 2,2 '-azo-bis-iso-dimethyl.Polymerization initiator can share more than 2 kinds.The consumption of polymerization initiator can be according to combination and the suitable setting of polymerizing condition of the contained monomer of set of monomers.

Follow and preferably in the lactone cyclized condensation reaction of the dealcoholysis in the polymkeric substance (a) use known cyclization catalyst.Cyclization catalyst is such as being esterification catalyst or the ester exchange catalysts such as p-toluenesulfonic acid.Can use the organic carboxyl acid classes such as acetic acid, propionic acid, benzoic acid, acrylic acid, methacrylic acid as cyclization catalyst.In addition, for example, as disclosed in Japanese kokai publication sho 61-254608 communique and the Japanese kokai publication sho 61-261303 communique, can use alkali compounds; The organic carboxylates such as zinc acetate; Carbonate is as cyclization catalyst.

Cyclization catalyst can be organic phosphorus compound.This organic phosphorus compound for example is, phostonic acid or aryl phosphonous acid (wherein, these can be alkyl phosphinic acid or arylphosphinic acid as dynamic isomer) and their monoesters or the diester such as methyl phosphonous acid, ethyl phosphonous acid, phenyl-phosphonite; Dialkyl phosphinic acid, diaryl phosphinic acids or alkylaryl phosphinic acids and their esters such as dimethyl phosphinic acids, diethyl phosphinic acids, diphenyl phosphonic acid, phenyl methyl phosphinic acids, phenylethyl phosphinic acids; Alkyl phosphonic acid or arylphosphonic acid and their monoesters or the diester such as methylphosphonic acid, ethylphosphonic acid, trifluoromethyl phosphonic acids, phenyl-phosphonic acid; The inferior phosphinic acids of alkyl or the inferior phosphinic acids of aryl and their ester of the inferior phosphinic acids of methyl, the inferior phosphinic acids of ethyl, the inferior phosphinic acids of phenyl etc.; Phosphorous acid monoesters, diester or three esters such as methyl phosphite, phosphorous acid ethyl ester, phenyl-phosphite, dimethylphosphite, diethyl phosphite, diphenyl phosphite, Trimethyl phosphite, triethyl phosphite, triphenyl phosphite; Methyl orthophosphoric acid, etherophosphoric acid, phosphoric acid-2-Octyl Nitrite, phosphoric acid isodecyl ester, lauryl phosphate, the phosphoric acid stearyl ester, the different stearyl ester of phosphoric acid, phenyl phosphate, dimethyl phosphate, diethyl phosphate, di(2-ethylhexyl)phosphate-2-Octyl Nitrite, octyl phosphate, di(2-ethylhexyl)phosphate isodecyl ester, didodecyl phosphate, the di(2-ethylhexyl)phosphate stearyl ester, the different stearyl ester of di(2-ethylhexyl)phosphate, diphenyl phosphate, trimethyl phosphate, triethyl phosphate, tricresyl phosphate isodecyl ester, the tricresyl phosphate lauryl, the tricresyl phosphate stearyl ester, the different stearyl ester of tricresyl phosphate, the phosphate monoesters such as triphenyl phosphate, diester or three esters; Methylphosphine, ethyl phosphine, Phenylphosphine, dimethyl phosphine, diethyl phosphine, diphenylphosphine, trimethyl-phosphine, triethyl phosphine, triphenylphosphine etc. are single, two or trialkyl (aryl) phosphine; Alkyl (aryl) the halogen phosphines such as methyl dichloro phosphine, ethyl dichloro phosphine, phenyl dichloro phosphine, dimethyl chloride phosphine, diethyl chlorine phosphine, chlorophosphonazo diphenylurea; The oxidations such as oxidation methyl phosphine, ethyl oxide phosphine, oxidation Phenylphosphine, cacodyl oxide base phosphine, oxidation diethyl phosphine, oxidation diphenylphosphine, trimethylphosphine oxide, oxidation triethyl phosphine, triphenylphosphine oxide are single, two or trialkyl (aryl) phosphine; Halogenation tetraalkyl (aryl) phosphorus such as tetramethyl phosphonium chloride phosphorus, chlorination tetraethyl phosphorus, tetraphenylphosphonium chloride.Can share these organic phosphorus compounds more than 2 kinds.Wherein, because catalytic activity is high, coloring is low, thereby preferred alkyl (aryl) phosphonous acid, phosphorous acid monoesters or diester, phosphate monoester or diester, alkyl (aryl) phosphonic acids, more preferably alkyl (aryl) phosphonous acid, phosphorous acid monoesters or diester, phosphate monoester or diester, particularly preferably alkyl (aryl) phosphonous acid, phosphate monoester or diester.

Can also use the cyclization catalyst of alkalescence.The compound of 12 family's elements that this cyclization catalyst is for example put down in writing for TOHKEMY 2009-144112 communique is particularly preferably zinc compound.Zinc compound is such as being the organic zinc compounds such as zinc acetate, zinc propionate, zinc octoate; The inorganic zinc compounds such as zinc paste, zinc chloride, zinc sulfate; Trifluoromethane sulfonic acid zinc etc. contains the organic zinc compound of fluorine.

Because also micro-remaining unreacted reactive group behind the lactone cyclized condensation reaction, when the resin combination with resulting comprising of (methyl) acrylate copolymer (A) is shaped to film, produce sometimes foam or polymkeric substance between crosslinked.By behind cyclized condensation reaction, adding the deactivator of cyclization catalyst, can suppress this phenomenon.The interpolation of deactivator is for suppressing the deteriorated also effective of cellulose ester polymer (B) that this resin combination comprises.Cyclization catalyst uses acidic materials or alkaline matter more.Be in the situation of acidic materials at cyclization catalyst, the preferred deactivator that uses alkalescence is in the situation of alkaline matter at cyclization catalyst, preferably uses acid deactivator.The deactivator of alkalescence is metal carboxylate, metal complex, metal oxide for example, is preferably metal carboxylate and metal oxide, more preferably metal carboxylate.Only otherwise suppress the physical property of resin combination, then unqualified to the metal that is used for this deactivator, such as being the alkaline metal such as lithium, sodium, potassium; The earth alkali metal such as magnesium, calcium, strontium, barium; Zinc; Zirconium.The carboxylic acid that consists of metal carboxylate for example is formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, sad, n-nonanoic acid, capric acid, lauric acid, tetradecylic acid, palmitic acid, stearic acid, docosanoic acid, tridecanoic acid, pentadecanoic acid, Heptadecanoic acide, lactic acid, malic acid, citric acid, oxalic acid, malonic acid, succinic acid, fumaric acid, maleic acid, hexane diacid.Organic principle in the metal complex for example is diacetone.Metal oxide is zinc paste, calcium oxide, magnesium oxide for example, is preferably zinc paste.Acid deactivator for example is organic phosphoric acid compound, carboxylic acid.Deactivator can share more than 2 kinds.Form to deactivator is unqualified, can have the forms such as solid-state, Powdered, dispersion, suspending liquid, aqueous solution.

[cellulose ester polymer (B)]

(B) is unqualified to cellulose ester polymer, for example is cellulose aromatic carboxylic acid ester polymer, cellulose fatty acid ester polymkeric substance.Owing to can obtain the phase retardation film of optical characteristics excellence, thereby cellulosic polymer (B) is preferably cellulose lower fatty acid ester polymer.Lower fatty acid refers to that carbon number is the fatty acid below 5.Cellulose lower fatty acid ester polymer for example is cellulose acetate, cellulose propionate, cellulose butyrate, neopentanoic acid cellulose.Cellulose ester polymer (B) can be the cellulose fatty acid mixed ester polymers such as cellulose-acetate propionate, cellulose acetate-butyrate.In this case, can realize comprising the taking into account of mechanical property of film forming and the final phase retardation film that obtains of the resin combination (C) of this cellulosic polymer (B).From with the aspect of the compatibility of (methyl) acrylate copolymer (A), cellulose ester polymer (B) is preferably cellulose acetate, is particularly preferably cellulose triacetate or cellulose-acetate propionate.

The Mn of cellulose ester polymer (B) is preferably 50,000～150,000, more preferably 5.5 ten thousand～120,000, more preferably 60,000～100,000.The Mw of cellulose ester polymer (B) is preferably 100,000～300,000, more preferably 100,000～250,000, more preferably 120,000～200,000.The dispersion degree of the molecular weight in the cellulose ester polymer (B) (=Mw/Mn) be preferably 1.3～5.5, more preferably 1.5～5.0, more preferably 1.7～4.0, be particularly preferably 2.0～3.5.

Cellulose ester polymer (B) can utilize known method manufacturing.For example, use acetic anhydride, propionic andydride and/or butyric anhydride, by conventional method the hydroxyl of raw cellulose is substituted by acetyl group, propiono and/or butyl, thereby can makes.At this moment, the method for putting down in writing with reference to Japanese kokai publication hei 10-45804 communique and the flat 6-501040 communique of Japanese Unexamined Patent Application Publication.Need to prove, raw cellulose is not particularly limited, for example is timber slurry, cotton cotton linters.The timber slurry can be acerose slurry, can be the slurry of broad leaf tree also, is preferably acerose slurry.The aspect of the fissility during from the formation film is preferably the cotton cotton linters.Cellulose ester polymer (B) can use more than 2 kinds.

[resin combination (C)]

Resin combination (C) comprises (methyl) acrylate copolymer (A) 30 % by weight that main chain has ring structure～95 % by weight and cellulose ester polymer (B) 5 % by weight～70 % by weight.Resin combination (C) preferably comprises (methyl) acrylate copolymer (A) 50 % by weight～90 % by weight and cellulose ester polymer (B) 10 % by weight～50 % by weight, more preferably comprises (methyl) acrylate copolymer (A) 70 % by weight～90 % by weight and cellulose ester polymer (B) 10 % by weight～30 % by weight.

If the content of (methyl) acrylate copolymer (A) in the resin combination (C) is excessive, the degree of freedom of the control of the wavelength dispersibility of the phase differential in the phase retardation film that then finally obtains reduces.On the other hand, if the content of the cellulose ester polymer (B) in the resin combination (C) is excessive, the photoelastic coefficient of the phase retardation film that then finally obtains and moisture permeability raise.

Resin combination (C) can comprise (methyl) acrylate copolymer (A) and/or the cellulose ester polymer more than 2 kinds (B) more than 2 kinds.

As long as can obtain effect of the present invention, then resin combination (C) can comprise with the content in resin combination (C) and counts below 40 % by weight, is preferably the polymkeric substance except (methyl) acrylate copolymer (A) and cellulose ester polymer (B) below 10 % by weight.

This polymkeric substance is such as being tygon, polypropylene, ethylene-propylene copolymer, poly-olefin polymers such as (4-methyl-1-pentenes); The halogen-containing polymkeric substance such as vinyl chloride, chlorinated ethylene resin; The styrenics such as polystyrene, styrene-methylmethacrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene (ABS) segmented copolymer; The polyester such as polyethylene terephthalate, polybutylene terephthalate, PEN; The polyamide such as nylon 6, nylon 66, NYLON610; Polyacetal; Polycarbonate; Polyphenylene oxide; Polyphenylene sulfide: polyetheretherketone; The polyethers nitrile; Polysulfones; Polyethersulfone; The polyoxy benzene methyl; Polyamidoimide.

In these polymkeric substance, comprise from the structural unit of vinyl cyanide base monomer with from multipolymer, for example styrene-acrylonitrile copolymer of the structural unit of aromatic vinyl monomer from having the aspect of compatibility excellence of (methyl) acrylate copolymer (A) of lactonic ring structure with (methyl) acrylate copolymer (A), particularly main chain, being preferably.

As long as can obtain effect of the present invention, then resin combination (C) can comprise arbitrarily material.This material for example is ultraviolet light absorber; Antioxidant; The stabilizing agents such as fast light stabilizing agent, weather-proof stabilizing agent, thermal stabilizer; The reinforcing material such as glass fibre, carbon fiber; Near infrared ray absorption; The fire retardants such as three (dibromopropyl) phosphate, triallyl phosphate, antimony oxide; The antistatic agent of the surfactant representative of anionic, cationic, nonionic; The colorants such as inorganic pigment, organic pigment, dyestuff; Organic filler, inorganic filler; Modifier; Anti blocking agent; The dumb light agent; The acid replenishers; Metal deactivation agent; Plastifier; Lubricant; The rubber mass such as ASA or ABS polymers.The content of these materials in the resin combination (C) for example is 0 % by weight～5 % by weight, be preferably 0 % by weight～2 % by weight, 0 % by weight～0.5 % by weight more preferably.

Ultraviolet light absorber for example is benzophenone based compound, salicylate based compound, benzoic ether based compound, three azole compounds and triazine based compound.The benzophenone based compound for example is 2; 4-dihydroxy benaophenonel, 4-n-octyloxy-2-dihydroxy benaophenonel, 2; 2 '-dihydroxy-4; 4 '-dimethoxy-benzophenone, Octabenzone, two (5-benzoyl-4-hydroxyl-2-methoxyphenyl) methane, Isosorbide-5-Nitrae-two (4-benzoyl-3-oxybenzone)-butane.The salicylate based compound for example is salicylic acid-4-tert-butyl group phenyl ester.The benzoic ether based compound for example is 2,4-di-tert-butyl-phenyl-3 ', 5 '-di-t-butyl-4 '-hydroxybenzoate.Three azole compounds for example are 2, [4-(1 for 2 '-di-2-ethylhexylphosphine oxide, 1,3, the 3-tetramethyl butyl)-6-(2H-benzotriazole-2-yl) phenol], 2-(3,5-di-t-butyl-2-hydroxyphenyl)-the 5-chlorobenzotriazole, 2-(2H-benzotriazole-2-yl)-paracresol, 2-(2H-benzotriazole-2-yl)-4, two (1-methyl isophthalic acid-phenylethyl) phenol of 6-, 2 benzotriazole-2-base-4, the 6-DI-tert-butylphenol compounds, 2-[5-chlorine (2H)-benzotriazole-2-yl]-4-methyl-6-(tert-butyl group) phenol, 2-(2H-benzotriazole-2-yl)-4, the 6-DI-tert-butylphenol compounds, 2-(2H-benzotriazole-2-yl)-4-(1,1,3, the 3-tetramethyl butyl) phenol, 2-(2H-benzotriazole-2-yl)-4-methyl-6-(3,4,5,6-tetrahydric phthalimide ylmethyl) phenol, the reaction product of methyl 3-(3-(2H-benzotriazole-2-the yl)-5-tert-butyl group-4-hydroxyphenyl) propionic ester/Liquid Macrogol, 2-(2H-benzotriazole-2-yl)-6-(straight chain and side chain dodecyl)-4-methylphenol, 2-(5-methyl-2-hydroxyphenyl) benzotriazole, 2-[2-hydroxyl-3, two (the α of 5-, α-dimethylbenzyl) phenyl]-the 2H-benzotriazole, 3-(2H-benzotriazole-2-yl)-5-(1,1-dimethyl ethyl)-4-hydroxyl-C7-9 side chain and straight chained alkyl ester.The triazine based compound is for example for having 2,4-diphenyl-6-(2-hydroxyl-4-methoxyphenyl)-1,3, the 5-triazine, 2,4-diphenyl-6-(2-hydroxyl-4-ethoxyl phenenyl)-1,3, the 5-triazine, 2,4-diphenyl-(2-hydroxyl-4-propoxyl group phenyl)-1,3, the 5-triazine, 2,4-diphenyl-(2-hydroxyl-4-butoxy phenyl)-1,3, the 5-triazine, 2,4-diphenyl-6-(2-hydroxyl-4-butoxy phenyl)-1,3,5-triazines, 2,4-diphenyl-6-(the own oxygen base of 2-hydroxyl-4-phenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxyl-4-octyloxyphenyl)-1,3, the 5-triazine, 2,4-diphenyl-6-(2-hydroxyl-4-dodecyl oxygen base phenyl)-1,3, the 5-triazine, 2,4-diphenyl-6-(2-hydroxyl-4-benzyloxy phenyl)-1,3,5-triazines, 2,4-diphenyl-6-(2-hydroxyl-4-butoxy ethoxy)-1,3,5-triazine, two [2-hydroxyl-4-the butoxy phenyl]-6-(2 of 2,4-, 4-dibutoxy phenyl)-1, the 3-5-triazine, two (2,4-the 3,5-dimethylphenyl)-6-[2-hydroxyl-4-(3-alkoxy-2-hydroxyl propoxyl group) of 2,4--5-α-cumyl phenyl]-each triazine skeleton of s-triazine and alkoxy octyloxy for example, the ninth of the ten Heavenly Stems oxygen base, the compound of the isometric chain alkoxy of oxygen base in the last of the ten Heavenly stems.Be ultraviolet light absorber as triazine, " Tinuvin 1577 ", " Tinuvin 460 ", " Tinuvin 477 " (being the different chemicals manufacturing of vapour Bart) have commercially available, be ultraviolet light absorber as triazole, " ADKSTAB LA-31 " (rising sun electrochemical industry manufacturing) has commercially available.

Resin combination (C) can comprise the ultraviolet light absorber more than 2 kinds.Resin combination (C) comprises in the situation of ultraviolet light absorber, and the content of the ultraviolet light absorber in the resin combination (C) is not particularly limited.Under the state of phase retardation film, its content is preferably 0.01 % by weight～25 % by weight, 0.05 % by weight～10 % by weight more preferably.If the content of ultraviolet light absorber is excessive, the mechanical property of the phase retardation film that then finally obtains reduces sometimes, perhaps phase retardation film xanthochromia sometimes.

Antioxidant for example is hindered phenol based compound, phosphorus series compound and chalcogenide compound.Resin combination (C) can comprise the antioxidant more than 2 kinds.

Antioxidant can be phenol system compound; for example be n-octadecane base-3-(3; 5-di-t-butyl-4-hydroxyphenyl) propionic ester; n-octadecane base-3-(3; 5-di-t-butyl-4-hydroxyphenyl) acetic acid esters; n-octadecane base-3; 5-di-tert-butyl-4-hydroxybenzoic acid ester; n-hexyl-3; 5-di-t-butyl-4-hydroxyphenyl benzoic ether; dodecyl-3; 5-di-t-butyl-4-hydroxyphenyl benzoic ether; new dodecyl-3-(3; 5-di-t-butyl-4-hydroxyphenyl) propionic ester; dodecyl-β-(3; 5-di-t-butyl-4-hydroxyphenyl) propionic ester; ethyl-α-(4-hydroxyl-3; the 5-di-tert-butyl-phenyl) isobutyrate; octadecyl-α-(4-hydroxyl-3; the 5-di-tert-butyl-phenyl) isobutyrate; octadecyl-α-(4-hydroxyl-3; 5-di-t-butyl-4-hydroxyphenyl) propionic ester; 2-(positive hot sulfenyl) ethyl-3; 5-di-tert-butyl-4-hydroxybenzoic acid ester; 2-(positive hot sulfenyl) ethyl-3; 5-di-t-butyl-4-hydroxyphenyl acetic acid esters; 2-(n-octadecane base sulfenyl) ethyl-3; 5-di-t-butyl-4-hydroxyphenyl acetic acid esters; 2-(n-octadecane base sulfenyl) ethyl-3; 5-di-tert-butyl-4-hydroxybenzoic acid ester; 2-(2-hydroxyl ethylmercapto group) ethyl-3; 5-di-tert-butyl-4-hydroxybenzoic acid ester; diethylene glycol-ether two-(3; 5-di-t-butyl-4-hydroxyl-phenyl) propionic ester; 2-(n-octadecane base sulfenyl) ethyl-3-(3; 5-di-t-butyl-4-hydroxyphenyl) propionic ester; stearmide-N; N-is two, and [ethylene-3-(3; 5-di-t-butyl-4-hydroxyphenyl) propionic ester]; normal-butyl imino group-N; N-is two, and [ethylene-3-(3; 5-di-t-butyl-4-hydroxyphenyl) propionic ester]; 2-(2-stearoyl-oxy ethylmercapto group) ethyl-3; 5-di-tert-butyl-4-hydroxybenzoic acid ester; 2-(2-stearoyl-oxy ethylmercapto group) ethyl-7-(the 3-methyl-5-tert-butyl group-4-hydroxyphenyl) heptanoate; 1; the 2-propylene glycol is two, and [3-(3; 5-di-t-butyl-4-hydroxyphenyl) propionic ester]; [3-(3 for ethylene glycol bis; 5-di-t-butyl-4-hydroxyphenyl) propionic ester]; neopentyl glycol is two, and [3-(3; 5-di-t-butyl-4-hydroxyphenyl) propionic ester]; ethylene glycol bis-(3; 5-di-t-butyl-4-hydroxyphenyl acetic acid esters); glycerine-1-positive stearate-2; 3-two-(3; 5-di-t-butyl-4-hydroxyphenyl acetic acid esters); pentaerythrite four-[3-(3 '; 5 '-di-t-butyl-4 '-hydroxyphenyl) propionic ester]; 1; 1; the 1-trimethylolethane trimethacrylate-[3-(3; 5-di-t-butyl-4-hydroxyphenyl) propionic ester]; D-sorbite six-[3-(3; 5-di-t-butyl-4-hydroxyphenyl) propionic ester]; 2-hydroxyethyl-7-(the 3-methyl-5-tert-butyl group-4-hydroxyphenyl) propionic ester; 2-stearoyl-oxy ethyl-7-(the 3-methyl-5-tert-butyl group-4-hydroxyphenyl) heptanoate; 1; the positive hexanediol of 6-two [(3 '; 5 '-di-t-butyl-4-hydroxyphenyl) propionic ester]; pentaerythrite four (3; 5-di-t-butyl-4-hydroxyl hydrogenated cinnamate); 3; 9-two [1; 1-dimethyl-2-[β-(3-tertiary butyl-4-hydroxy-5-aminomethyl phenyl) propiono oxygen base] ethyl]-2; 4; 8; 10-four oxaspiros [5,5]-undecane.

The antioxidant (phenol is antioxidant) that is made of phenol system compound is that antioxidant or phosphoric acid are that antioxidant combination is used with thioether preferably.Content about the antioxidant of the both sides in the resin combination (C), take the weight of (methyl) acrylate copolymer (A) as benchmark, for example, phenol is that antioxidant and thioether are that antioxidant is respectively more than 0.01 % by weight, and phenol is that antioxidant and phosphoric acid are that antioxidant is respectively more than 0.025 % by weight.

Thioether is that antioxidant for example is pentaerythrite four (3-lauryl thiopropionate), dilauryl-3,3 '-thiodipropionate, myristyl-3,3 '-thiodipropionate, distearyl-3,3 '-thiodipropionate.

Phosphoric acid is that antioxidant for example is three (2, the 4-di-tert-butyl-phenyl) phosphite ester, 2-[[2,4,8,10-four (1,1-dimethyl ethyl) dibenzo [d, f] [1,3,2] dioxa phospha English in heptan-6-yl] the oxygen base]-N, N-two [2-[[2,4,8,10-four (1,1-dimethyl ethyl) dibenzo [d, f] [1,3,2] dioxa phospha English in heptan-6-yl] the oxygen base]-ethyl] ethamine, diphenyl tridecyl phosphite ester, the triphenyl phosphite ester, 2,2-di-2-ethylhexylphosphine oxide (4,6-di-tert-butyl-phenyl) octyl group phosphite ester, two (2,6-di-t-butyl-4-aminomethyl phenyl) pentaerythritol diphosphites, distearyl pentaerythrityl diphosphite, two (2, the 6-di-t-butyl-4-aminomethyl phenyl) phosphite esters of pentaerythrite.

Content to the antioxidant in the resin combination (C) is not particularly limited, and for example, is 0 % by weight～10 % by weight, is preferably 0 % by weight～5 % by weight, more preferably 0.01 % by weight～2 % by weight, 0.05 % by weight～1 % by weight more preferably.If the content of antioxidant is excessive, then when melt extruding by resin combination (C) moulding phase retardation film, antioxidant occurs sometimes ooze out, perhaps can produce crazing.

[phase retardation film]

Fig. 1 shows an example of phase retardation film of the present invention.Phase retardation film of the present invention 1 shown in Figure 1 is made of the layer that resin combination (C) forms, and described resin combination (C) comprises (methyl) acrylate copolymer (A) 30 % by weight that main chain has ring structure～95 % by weight and cellulose ester polymer (B) 5 % by weight～70 % by weight.As required, phase retardation film of the present invention can possess the arbitrarily layer except the layer that is formed by resin combination (C), in order to obtain more reliably effect of the present invention, as shown in Figure 1, the layer that is preferably formed by resin combination (C) consists of, that is, consisted of by resin combination (C).But this layer can have functional coat on its surface.

The absolute value for the photoelastic coefficient of the light of wavelength 590nm in the phase retardation film of the present invention for example is 5 * 10 ^-12Pa ^-1Below.The content of (resin combination (C) comprises) (methyl) acrylate copolymer (A) that phase retardation film according to the present invention comprises and the kind of cellulose ester polymer (B) and (methyl) acrylate copolymer (A) in the phase retardation film of the present invention and cellulose ester polymer (B) different, this absolute value is 4 * 10 ^-12Pa ^-1Below so be 3 * 10 ^-12Pa ^-1Below.

Phase differential Re is different because of the extended state of this film in the shown face of phase retardation film of the present invention, for the light of wavelength 590nm, in the value of per 100 μ m thickness, for example is more than the 50nm.The content of (methyl) acrylate copolymer (A) that phase retardation film according to the present invention comprises and the kind of cellulose ester polymer (B) and (methyl) acrylate copolymer (A) in the phase retardation film of the present invention and cellulose ester polymer (B) different, phase differential Re is in the value of per 100 μ m thickness in the face, for more than the 140nm and then be more than the 150nm and below the 500nm.

The degree of freedom of the control of the wavelength dispersibility of the phase differential in the phase retardation film of the present invention is high, for example, becomes the anti-wavelength dispersibility of demonstration phase differential or the smooth phase retardation film of wavelength dispersibility of phase differential.As concrete example, become for phase differential Re (447), Re (590) and Re (750) in the face of each light of wavelength 447nm, 590nm and 750nm and satisfy formula 0.8＜=Re (447)/Re (590)＜=1.2 and 0.8＜=Re (750)/Re (phase retardation film of the relation of 590)＜=1.2.The preferred Re of phase retardation film of the present invention (447), Re (590) and Re (750) satisfy formula 0.8＜=Re (447)/Re, and ((relation of 590)＜=1.2 more preferably satisfies formula 0.8＜=Re (447)/Re (590)＜=1.0 and 1.0＜=Re (750)/Re (relation of 590)＜=1.2 to 590)＜=1.1 and 0.9＜=Re (750)/Re.

In the value of measuring according to JIS Z0208, the moisture permeability of the per 100 μ m thickness in the phase retardation film of the present invention for example is 300g/m ²Below 24 hours.The content of (methyl) acrylate copolymer (A) that phase retardation film according to the present invention comprises and the kind of cellulose ester polymer (B) and (methyl) acrylate copolymer (A) in the phase retardation film of the present invention and cellulose ester polymer (B) different, this value is 250g/m ²Below 24 hours, 200g/m ²Below 24 hours, 150g/m ²Below 24 hours, 130g/m ²Below 24 hours and then be 120g/m ²Below 24 hours.

Phase retardation film of the present invention demonstrates the high-fire resistance that has (methyl) acrylate copolymer (A) of ring structure based on main chain, and its Tg for example is more than 110 ℃.The content of (methyl) acrylate copolymer (A) that phase retardation film according to the present invention comprises and the kind of cellulose ester polymer (B) and (methyl) acrylate copolymer (A) in the phase retardation film of the present invention and cellulose ester polymer (B) different, Tg is more than 120 ℃, more than 125 ℃ and then is more than 130 ℃.

Thickness to phase retardation film of the present invention is not particularly limited, and for example, is 10 μ m～500 μ m, is preferably 20 μ m～300 μ m, is particularly preferably 30 μ m～100 μ m.

The shown Nz coefficient of phase retardation film of the present invention is in the value for the light of wavelength 590nm, preferably less than 1.20, more preferably below 1.15, more preferably below 1.10 and more than 0.95.In with the face of phase retardation film phase differential be made as Re, when the phase differential of thickness direction is made as Rth, the Nz coefficient is by the represented value of formula Nz=(Rth/Re)+0.5.

In the value of measuring according to JIS K7361-1, total light penetration of phase retardation film of the present invention is preferably more than 85%, more preferably more than 90%, more preferably more than 91%.

Value during in the thickness 50 μ m that measures according to JIS 7165, the mist degree of phase retardation film of the present invention be preferably below 5%, more preferably below 3%, more preferably below 1%.

In the phase retardation film of the present invention, as required, the surface of the layer that is made of resin combination (C) can form various functional coats.Functional coat for example is antistatic layer; The adhesive linkages such as adhesive phase, cement layer; Easy adhesive linkage; Anti-dazzle (anti-dazzle) layer; The stain-proofing layers such as photocatalyst layer; Anti-reflecting layer; Hard conating; Ultraviolet screener layer, heat ray shielding layer, electromagnetic wave shielding; Gas-barrier layer.

Purposes to phase retardation film of the present invention is not particularly limited, and can be used in the purposes same with existing phase retardation film.Phase retardation film of the present invention is suitable for the optical compensation in the image display devices such as LCD.In addition, except LCD, can also be used for various image display devices, optical devices.

As required, phase retardation film of the present invention can make up with other optics, for example uses with the state that is bonded with each other.

Phase retardation film of the present invention can utilize known film forming method and film drawing process to make by resin combination (C) or by making front (methyl) acrylate copolymer (A) of resin combination (C) and cellulose ester polymer (B).Specifically, for example, resin combination (C) is shaped to film and makes former film (unstretching film), and resulting former film is stretched.

The film forming method for example is solution casting method (solution casting method), extrusion by melting, rolling process, extrinsion pressing.Wherein, be preferably solution casting method, extrusion by melting.

The drawing process of former film can be suitable for known unilateral stretching gimmick or two-way stretch gimmick.

Extrusion by melting for example is T modulus method and inflation method.In the T modulus method, at the front-end configuration T of melt extruder mould, and coiling obtains being wound into the former film of web-like thus from the film that this T mould melt extrudes.At this moment, can also adjust temperature and the speed of coiling, apply stretching (unilateral stretching) in the direction of extruding of film.

When melt extruding, preferably carry out the devolatilization of volatile ingredient from the exhaust oral area of melt extruder.In addition, when melt extruding, preferably share the filtration based on the resin combination of polymer filter.

The solution casting method generally has (1) dissolution process, (2) curtain coating operation and (3) drying process.Each operation can be suitable for known gimmick.

To have the solution of (methyl) acrylate copolymer (A) of ring structure and cellulose ester polymer (B) then unqualified as long as the detailed process of dissolution process can obtain comprising main chain.Make the solvent of both sides' polymer dissolution can use the good solvents such as methylene chloride, methyl acetate, dioxolanes, simultaneously, can share the poor solvents such as methyl alcohol, ethanol, butanols.As long as dissolving cellulos ester polymer (B) then can use the polymer solvent that uses when polymerization (methyl) acrylate copolymer (A).

The curtain coating operation can be suitable for known solution coat method.The method is to have used the coating process that is coated with machine, knife type coater, roll coater, comma coating machine, lip coating machine etc. such as mould.

The drying that the detailed process of drying process needs only by the coated film that is formed by the curtain coating operation forms film, then is not particularly limited.

[image display device]

Image display device of the present invention possesses phase retardation film of the present invention.Thus, form the image display device image display feature excellence, for example high-contrast and wide visible angle.

Image display device of the present invention for example is LCD.

Embodiment

Below, illustrate in greater detail the present invention by embodiment.The present invention is not limited to embodiment shown below.

[mean molecular weight]

Weight-average molecular weight (Mw) and number-average molecular weight (Mn) use gel permeation chromatography (GPC) to be obtained by polystyrene conversion according to following condition determination.

The mensuration system: eastern Cao makes the HLC-8220 of GPC system

Developing solvent: chloroform (already make with the pure pharmaceutical worker of light, superfine)

Solvent flux: 0.6mL/ minute

Standard sample: TSK polystyrene standard (eastern Cao makes, PS-oligomer kit)

The mensuration lateral column consists of: eastern Cao makes, and 6.0 * 150,2 of TSK-GEL super HZM-M are connected in series

East Cao make, 4.6 * 35,1 of TSK-GEL super HZ-L

The reference lateral column consists of: eastern Cao makes, and TSK-GEL SuperH-RC 6.0 * 150,2 are connected in series

Column temperature: 40 ℃

[glass transition temperature]

Glass transition temperature (Tg) is obtained according to JIS K7121.Specifically, (Rigaku makes, and DSC-8230), sample that will about 10mg under nitrogen atmosphere is warming up to 200 ℃ (programming rate is 20 ℃/minute) from normal temperature to use differential scanning calorimeter, obtain the DSC curve, estimated according to the initial point method by this DSC curve.Reference uses Alpha-alumina.

[melt flow rate (MFR)]

About MFR, according to JIS K6874, test temperature is made as 240 ℃, test load is made as 10kg and obtains.

[optical characteristics of phase retardation film]

About the phase differential Rth for phase differential Re and thickness direction in the face of the light of wavelength 590nm in the phase retardation film of made, use phase retardation film optical material testing fixture RETS-100 (Da mound electronics to make) estimate with the condition of 40 ° of incident angles.Phase differential Re is defined by formula Re=(nx-ny) * d in the face, and the phase differential Rth of thickness direction is by formula Rth=[(nx+ny)/2-nz] * d defined.Herein, nx is the refractive index of the slow-axis direction in the face, and ny is in the face and the refractive index of nx vertical direction, and nz is the refractive index of the thickness direction of film, and d is the thickness (nm) of film.Slow-axis direction is the direction of refractive index maximum in the face.About the Nz coefficient of the phase retardation film of made, by the value of the Re that obtains as mentioned above and Rth, according to formula Nz coefficient=(Rth/Re)+0.5 calculate.

Additionally, to similarly estimating for phase differential Re (447) and Re (750) in the face of the light of wavelength 447nm and 750nm in the phase retardation film of making, get and the above-mentioned ratio for phase differential Re (590) in the face of the light of wavelength 590nm of obtaining, obtain thus the value of Re (447)/Re (590) and Re (750)/Re (590).

[the photoelastic coefficient Cd of phase retardation film]

About the photoelastic coefficient for the light of wavelength 590nm in the phase retardation film of made, (JASCO makes, and M-150) estimates to use ellipsometer.Specifically, 20mm * 50mm that the phase retardation film of made is cut into take draw direction as long limit makes the mensuration sample, attach it to the photoelasticity instrumentation unit of ellipsometer, apply abreast on one side mechanical load 3 birefringences of instrumentation on one side of 5N～25N with draw direction, with use wavelength 590nm light time, birefringence with respect to the slope of stress as photoelastic coefficient.

[moisture permeability]

About the moisture permeability of the phase retardation film of made, under 40 ℃ condition determination, obtain according to JIS Z0208.The value that thickness with the phase retardation film of per 100 μ m converts has been shown in the following table.

[mist degree]

The mist degree of the phase retardation film of made uses nephelometer (Japanese electric look industry manufacturing, NDH5000) to estimate.Need to prove, utilize this nephelometer enforcement based on the mensuration of JIS K7165.The value of per 50 μ m thickness has been shown in the following table.

(Production Example 1)

Drop into methyl methacrylate (MMA) 6000g, 2-(hydroxymethyl) methyl acrylate (MHMA) 3000g, n-BMA (BMA) 1000g in the reaction unit of the internal volume 30L (liter) that possesses stirring apparatus, temperature sensor, cooling tube and nitrogen ingress pipe and as the methyl isobutyl ketone (MIBK) of polymer solvent and mixed solvent (weight ratio 9:1) 6667g of methyl ethyl ketone (MEK), to wherein logical nitrogen on one side be warming up to 105 ℃ on one side.After beginning with the backflow together that heats up, (Arkema YOSHITOMI makes as the different n-nonanoic acid tert-pentyl ester of the peroxidating of the 6.0g of polymerization initiator in interpolation, trade name: Luperox 570), the solution that dripped dissolving above-mentioned peroxidating different n-nonanoic acid tert-pentyl ester 12.0g in above-mentioned mixed solvent 3315g with 3 hours on one side simultaneously and obtain, under about 95 ℃～110 ℃ backflow, carry out solution polymerization on one side, and then carry out 4 hours slaking.The polyreaction rate is 90.5%, and the content of the MHMA unit in the resulting polymkeric substance is 29.7 % by weight.

Then, the octyl phosphate of adding 20g/dioctyl ester potpourri (make by the Sakai chemistry in resulting polymeric solution, trade name: Phoslex A-8) as the catalyzer (cyclization catalyst) of cyclized condensation reaction, under about 85 ℃～100 ℃ backflow, carry out 2 hours cyclized condensation reactions.And then, in be forced into the autoclave of the highest about 2MPa in gauge pressure with 240 ℃ of heating after 90 minutes, with the devolatilization in vented twin-screw extruder of resulting polymeric solution, extrude, obtain transparent (methyl) acrylate copolymer (A-1) that main chain has the lactonic ring structure.The weight-average molecular weight of polymkeric substance (A-1) is that 13.4 ten thousand, MFR are 14.5g/10 minute, and Tg is 130 ℃.

(embodiment 1)

Polymkeric substance (A-1) 90 weight portions and cellulose-acetate propionate (B-1) [degree of substitution with acetyl group 2.5 % by weight, hydroxyl degree of substitution 1.8 % by weight, propiono degree of substitution 46 % by weight, number-average molecular weight Mn=6.3 ten thousand, weight-average molecular weight Mw=17.5 ten thousand] 10 weight portions made in the Production Example 1 are dissolved in the methylene chloride; stir resulting solution, polymkeric substance (A-1) and cellulose-acetate propionate (B-1) are evenly mixed.Then, resulting mixed solution under reduced pressure in 120 ℃ of dryings 1 hour, is obtained solid-state resin combination 100 weight portions.

Then, utilize compression molding forming machine with 220 ℃ of compression moldings resulting resin combination, make the film that thickness is 126 μ m (unstretching film).Then, utilize cupping machine (INSTRON manufacturing) to carry out unilateral stretching with 133 ℃ of 2 times of draw ratios and draft temperatures in the MD direction film of made, obtain the stretched film that thickness is 85 μ m (F1).The evaluation result of stretched film (F1) is listed in the table below 1.

(embodiment 2)

Polymkeric substance (A-1) 70 weight portions and cellulose-acetate propionate (B-1) 30 weight portions are dissolved in the methylene chloride, and making thickness is the former film of 120 μ m, obtains similarly to Example 1 in addition the stretched film that thickness is 82 μ m (F2).The evaluation result of stretched film (F2) is listed in the table below 1.

(embodiment 3)

Polymkeric substance (A-1) 50 weight portions and cellulose-acetate propionate (B-1) 50 weight portions are dissolved in the methylene chloride, and making thickness is the former film of 118 μ m, obtains similarly to Example 1 in addition the stretched film that thickness is 83 μ m (F3).The evaluation result of stretched film (F3) is listed in the table below 1.

(comparative example 1)

Polymkeric substance (A-1) 10 weight portions and cellulose-acetate propionate (B-1) 90 weight portions are dissolved in the methylene chloride, and making thickness is the former film of 104 μ m, and making draft temperature is 135 ℃, obtains similarly to Example 1 in addition the stretched film that thickness is 72 μ m (F4).The evaluation result of stretched film (F4) is listed in the table below 1.

[table 1]

As shown in table 1, to compare with the stretched film of comparative example 1, moisture permeability and the photoelastic coefficient of the stretched film of embodiment 1～3 are low, obtain phase differential in the large face, and the Nz coefficient is little simultaneously.In addition, the phase differential in the stretched film of embodiment 1～3 demonstrates smooth wavelength dispersibility or anti-wavelength dispersibility.

(Production Example 2)

Drop into methyl methacrylate (MMA) 52 weight portions, 2-(hydroxymethyl) methyl acrylate (MHMA) 30 weight portions, n-BMA (BMA) 18 weight portions in the reaction unit of the internal volume 30L (liter) that possesses stirring apparatus, temperature sensor, cooling tube and nitrogen ingress pipe and as the methyl isobutyl ketone (MIBK) of polymer solvent and mixed solvent (weight ratio 9:1) 67 weight portions of methyl ethyl ketone (MEK), to wherein logical nitrogen on one side be warming up to 105 ℃ on one side.After beginning with the backflow together that heats up, (Arkema YOSHITOMI makes as the different n-nonanoic acid tert-pentyl ester of the peroxidating of 0.06 weight portion of polymerization initiator in interpolation, trade name: Luperox 570), the solution that dripped dissolving different n-nonanoic acid tert-pentyl ester 0.12 weight portion of above-mentioned peroxidating in above-mentioned mixed solvent 33 weight portions with 3 hours on one side simultaneously and obtain, under about 95 ℃～110 ℃ backflow, carry out solution polymerization on one side, and then carry out 4 hours slaking.

Then, the octyl phosphate of adding 0.2 weight portion/dioctyl ester potpourri (make by the Sakai chemistry in resulting polymeric solution, trade name: Phoslex A-8) as the catalyzer (cyclization catalyst) of cyclized condensation reaction, under about 85 ℃～100 ℃ backflow, carry out 2 hours cyclized condensation reactions.And, and then in be forced into the autoclave of the highest about 2MPa in gauge pressure with 240 ℃ of heating 90 minutes.Then, with resulting polymeric solution take amount of resin be scaled 2.0kg/ hour processing speed import barrel zone temperature as 260 ℃, rotating speed as 100rpm, vacuum tightness as 13.3hPa～400hPa (10mmHg～300mmHg), rear exhaust port number as 1, front-seat gas port number in 4 vented twin-screw extruder (φ=30mm, L/D=40), in this extruder, implement further carrying out and devolatilization of cyclized condensation reaction., from this extruder extrude the polymkeric substance that be in molten condition, obtain main chain and have the lactonic ring structure, have a particle of (methyl) acrylate copolymer (A-2) of BMA unit of 18 % by weight of entire infrastructure unit simultaneously thereafter.The weight-average molecular weight of polymkeric substance (A-2) is that 12.6 ten thousand, Tg are 123 ℃.Need to prove that the BMA unit is the ester units of (methyl) acrylic acid alkyl shown in the formula (1), is R ¹Be normal-butyl, R ²Be CH ₃The structural unit of (methyl).

(Production Example 3)

Making the amount that drops into each monomer in the reaction unit is MMA60 weight portion, MHMA30 weight portion and BMA10 weight portion, similarly obtains main chain with Production Example 2 in addition and has the lactonic ring structure, has a particle of (methyl) acrylate copolymer (A-3) of BMA unit of 10 % by weight of entire infrastructure unit simultaneously.The weight-average molecular weight of polymkeric substance (A-3) is that 13.4 ten thousand, Tg are 130 ℃.

(Production Example 4)

In reaction unit, do not drop into BMA, making the amount of the MMA in the input reaction unit be 70 weight portions, making the amount of MHMA is 30 weight portions, similarly obtains the particle that main chain has the lactonic ring structure, do not have (methyl) acrylate copolymer (C-1) of the structural unit shown in the formula (1) simultaneously with Production Example 2 in addition.The weight-average molecular weight of polymkeric substance (C-1) is that 17.0 ten thousand, Tg are 122 ℃.

(Production Example 5)

Drop into MMA24.5 weight portion, MHMA26 weight portion, β-dimethyl-aminoethylmethacrylate (EMA) 45 weight portions, N-vinylcarbazole (NVCz) 4.5 weight portions in the reaction unit of the internal volume 30L (liter) that possesses stirring apparatus, temperature sensor, cooling tube and nitrogen ingress pipe and as toluene 86.5 weight portions of polymer solvent and the mixed solvent of methyl alcohol 3.5 weight portions, to wherein lead to nitrogen on one side be warming up to 95 ℃ on one side.After beginning with the backflow together that heats up, (Arkema YOSHITOMI makes as the peroxidating of 0.01 weight portion of polymerization initiator-2 ethyl hexanoic acid tert-pentyl ester in interpolation, trade name: Luperox 575), the solution that dripped dissolving above-mentioned peroxidating-2 ethyl hexanoic acid tert-pentyl ester 0.10 weight portion in toluene 10 weight portions with 8 hours on one side simultaneously and obtain, under about 90 ℃～100 ℃ backflow, carry out solution polymerization on one side, and then carry out 12 hours slaking.

Then, the octyl phosphate of adding 0.2 weight portion/dioctyl ester potpourri (make by the Sakai chemistry in resulting polymeric solution, trade name: Phoslex A-8) as the catalyzer (cyclization catalyst) of cyclized condensation reaction, under about 80 ℃～100 ℃ backflow, carry out 2 hours cyclized condensation reactions.And, and then in be forced into the autoclave of the highest about 2MPa in gauge pressure with 240 ℃ of heating 90 minutes.Then, resulting polymeric solution under reduced pressure in 240 ℃ of dryings 1 hour, is obtained main chain and has the lactonic ring structure, has (methyl) acrylate copolymers (A-4) of EMA unit of 45 % by weight of entire infrastructure unit simultaneously.The weight-average molecular weight of polymkeric substance (A-4) is that 17.0 ten thousand, Tg are 122 ℃.Need to prove that the EMA unit is (methyl) acrylic ester unit shown in the formula (1), is R ¹Be ethyl, R ²Be CH ₃The structural unit of (methyl).

(Production Example 6)

Making the amount that drops into each monomer in the reaction unit is MMA44.5 weight portion, MHMA26 weight portion, EMA25 weight portion and NVCz4.5 weight portion, similarly obtains main chain with Production Example 5 in addition and has the lactonic ring structure, has (methyl) acrylate copolymers (A-5) of EMA unit of 25 % by weight of entire infrastructure unit simultaneously.The weight-average molecular weight of polymkeric substance (A-5) is that 17.0 ten thousand, Tg are 129 ℃.

(Production Example 7)

In reaction unit, do not drop into EMA, making the amount of the MMA in the input reaction unit be 69.5 weight portions, making the amount of MHMA be 26 weight portions, make the amount of NVCz is 4.5 weight portions, similarly obtains (methyl) acrylate copolymer (C-2) that main chain has the lactonic ring structure, do not have the structural unit shown in the formula (1) simultaneously with Production Example 5 in addition.The weight-average molecular weight of polymkeric substance (C-2) is that 16.3 ten thousand, Tg are 138 ℃.

(Production Example 8)

Polymkeric substance (A-2) 70 weight portions and cellulose-acetate propionate (B-1) [degree of substitution with acetyl group is that 2.5 % by weight, hydroxyl degree of substitution are that 1.8 % by weight, propiono degree of substitution are 46 % by weight, number-average molecular weight Mn=6.3 ten thousand, weight-average molecular weight Mw=17.5 ten thousand] 30 weight portions made in the Production Example 2 are dissolved in the methylene chloride; stir resulting solution, polymkeric substance (A-2) and cellulose-acetate propionate (B-1) are evenly mixed.Then, resulting mixed solution under reduced pressure in 120 ℃ of dryings 1 hour, is obtained solid-state resin combination 100 weight portions.

Then, utilize compression molding forming machine with 220 ℃ of compression moldings resulting resin combination, make the unstretching film that thickness is 50 μ m.The evaluation result of resulting film is listed in the table below 2.

(Production Example 9)

Polymkeric substance (A-2) 50 weight portions and cellulose-acetate propionate (B-1) 50 weight portions are evenly mixed, similarly obtain unstretching film with Production Example 8 in addition.The evaluation result of resulting film is listed in the table below 2.

(Production Example 10)

Replace polymkeric substance (A-2) and use the polymkeric substance (A-3) of making in the Production Example 3, similarly obtain unstretching film with Production Example 8 in addition.The evaluation result of resulting film is listed in the table below 2.

(Production Example 11)

Replace polymkeric substance (A-2) and use the polymkeric substance (C-1) of making in the Production Example 4, similarly obtain unstretching film with Production Example 8 in addition.The evaluation result of resulting film is listed in the table below 2.

(Production Example 12)

Replace polymkeric substance (A-2) and use the polymkeric substance (A-4) of making in the Production Example 5, similarly obtain unstretching film with Production Example 8 in addition.The evaluation result of resulting film is listed in the table below 2.

(Production Example 13)

Polymkeric substance (A-4) 50 weight portions and cellulose-acetate propionate (B-1) 50 weight portions are evenly mixed, similarly obtain unstretching film with Production Example 12 in addition.The evaluation result of resulting film is listed in the table below 2.

(Production Example 14)

Replace polymkeric substance (A-2) and use the polymkeric substance (A-5) of making in the Production Example 6, similarly obtain unstretching film with Production Example 8 in addition.The evaluation result of resulting film is listed in the table below 2.

(Production Example 15)

Replace polymkeric substance (A-2) and use the polymkeric substance (C-2) of making in the Production Example 7, similarly obtain film with Production Example 8 in addition.The evaluation result of resulting film is listed in the table below 2.

[table 2]

※ MMA: methyl methacrylate, MHMA:2-(hydroxymethyl) methyl acrylate

BMA: n-BMA, EMA: β-dimethyl-aminoethylmethacrylate, NVCz:N-vinylcarbazole

As shown in table 2, to compare with Production Example 11,15 film, the mist degree of the film of Production Example 8～10 and Production Example 12～14 is little, and the transparency is excellent.And, confirm the less tendency of mist degree of film of the larger then made of content of BMA unit in (methyl) acrylate copolymer or EMA unit.In addition, different according to the content of (methyl) acrylate copolymer (A) in the film of the composition of (methyl) acrylate copolymer (A) in the film of Production Example 8～10 and Production Example 12～14 and made, the moisture permeability of this film and photoelastic coefficient are lower than moisture permeability and the photoelastic coefficient of Production Example 11,15 film.

(embodiment 4)

Use cupping machine (INSTRON manufacturing), with the unstretching film made in the Production Example 8 (wherein, the thickness of this film is 120 μ m) carry out unilateral stretching with 128 ℃ of 2 times of draw ratios and draft temperatures in the MD direction, obtain the stretched film that thickness is 87 μ m (phase retardation film).The evaluation result of resulting phase retardation film is listed in the table below 3.

(embodiment 5)

Use the unstretching film (wherein, the thickness of this film is 120 μ m) of making in the Production Example 9, obtain similarly to Example 4 in addition the stretched film that thickness is 85 μ m (phase retardation film).The evaluation result of resulting phase retardation film is listed in the table below 3.

(embodiment 6)

Use the unstretching film (wherein, the thickness of this film is 120 μ m) of making in the Production Example 10, making simultaneously draft temperature is 133 ℃, obtains similarly to Example 4 in addition the stretched film that thickness is 82 μ m (phase retardation film).The evaluation result of resulting phase retardation film is listed in the table below 3.

(embodiment 7)

Use the unstretching film (wherein, the thickness of this film is 123 μ m) of making in the Production Example 12, making simultaneously draft temperature is 127 ℃, obtains similarly to Example 4 in addition the stretched film that thickness is 86 μ m (phase retardation film).The evaluation result of resulting phase retardation film is listed in the table below 3.

(embodiment 8)

Use the unstretching film (wherein, the thickness of this film is 121 μ m) of making in the Production Example 13, obtain similarly to Example 4 in addition the stretched film that thickness is 84 μ m (phase retardation film).The evaluation result of resulting phase retardation film is listed in the table below 3.

(embodiment 9)

Use the unstretching film (wherein, the thickness of this film is 126 μ m) of making in the Production Example 14, obtain similarly to Example 4 in addition the stretched film that thickness is 87 μ m (phase retardation film).The evaluation result of resulting phase retardation film is listed in the table below 3.

[table 3]

As shown in table 3, each phase retardation film of making among the embodiment 4～9 demonstrates the positive phase differential Rth of the interior phase differential Re of large face and thickness direction, and, about phase differential Re in the face, demonstrate anti-wavelength dispersibility.

Need to prove, about the shown mist degree of the phase retardation film of making among the embodiment 4～9 and similarly to Example 4 the unstretching film of making in the Production Example 11,15 is stretched and the shown mist degree of stretched film made, be converted into identical thickness, the mist degree shown with the unstretching film (Production Example 8～15) before the corresponding stretching is identical.In addition, about the moisture permeability of the shown photoelastic coefficient of the phase retardation film of making among the embodiment 4～9 and per 100 μ m thickness and similarly to Example 4 the unstretching film of making in the Production Example 11,15 is stretched and the shown photoelastic coefficient of the stretched film of making and the moisture permeability of per 100 μ m thickness, photoelastic coefficient and the moisture permeability shown with the unstretching film (Production Example 8～15) before the corresponding stretching are identical.

The present invention only otherwise break away from its intention and internal feature then can be applicable to other embodiment.The disclosed embodiment of this instructions is the embodiment that illustrates in all respects, but is not limited thereto.Scope of the present invention is illustrated by the claim of above-mentioned unaccounted institute apposition, with the implication of claim equalization and in the scope all the change all within the scope of the present invention.

Industrial applicibility

Phase retardation film of the present invention can be used in the same purposes of existing phase retardation film in, for example can be used in various image display devices and optical devices headed by the LCD.

Claims

1. phase retardation film, it comprises the layer that is made of resin combination (C), and described resin combination (C) is included in (methyl) acrylate copolymer (A) 30 % by weight that main chain has ring structure～95 % by weight and cellulose ester polymer (B) 5 % by weight～70 % by weight.

2. phase retardation film as claimed in claim 1, wherein, described (methyl) acrylate copolymer (A) has (methyl) acrylic acid alkyl ester units shown in the following formula (1) as structural unit,

[Chemical formula 1]

In the formula (1), R ¹That carbon number is 2～18 alkyl, R ²H or CH ₃

3. phase retardation film as claimed in claim 2, wherein, described (methyl) acrylate copolymer (A) has methyl methacrylate units and 2-(hydroxymethyl) acrylic ester unit.

4. phase retardation film as claimed in claim 2, wherein, described (methyl) acrylate copolymer (A) has methyl methacrylate units, 2-(hydroxymethyl) acrylic ester unit and N-vinylcarbazole unit.

5. phase retardation film as claimed in claim 1, wherein, described (methyl) acrylate copolymer (A) has methyl methacrylate units.

6. phase retardation film as claimed in claim 1, wherein, the absolute value for the photoelastic coefficient of the light of wavelength 590nm of described phase retardation film is 5 * 10 ^-12Pa ^-1Below.

7. phase retardation film as claimed in claim 1, wherein, described phase retardation film satisfy following relation for phase differential Re (447), Re (590) and Re (750) in the face of each light of wavelength 447nm, 590nm and 750nm:

0.8＜=Re (447)/Re (590)＜=1.2, and

0.8≦Re(750)/Re(590)≦1.2。

8. phase retardation film as claimed in claim 1, wherein, the mist degree during the thickness 50 μ m that measures according to JIS K7165 of described phase retardation film is below 5%.

9. image display device, it possesses each described phase retardation film of claim 1～8.