WO2015016286A1 - 光学フィルム、それを用いた偏光板および液晶表示装置 - Google Patents
光学フィルム、それを用いた偏光板および液晶表示装置 Download PDFInfo
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- WO2015016286A1 WO2015016286A1 PCT/JP2014/070135 JP2014070135W WO2015016286A1 WO 2015016286 A1 WO2015016286 A1 WO 2015016286A1 JP 2014070135 W JP2014070135 W JP 2014070135W WO 2015016286 A1 WO2015016286 A1 WO 2015016286A1
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/04—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of organic materials, e.g. plastics
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
- G02B1/14—Protective coatings, e.g. hard coatings
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
- G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
- G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/133528—Polarisers
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K2323/00—Functional layers of liquid crystal optical display excluding electroactive liquid crystal layer characterised by chemical composition
- C09K2323/03—Viewing layer characterised by chemical composition
- C09K2323/035—Ester polymer, e.g. polycarbonate, polyacrylate or polyester
Definitions
- the present invention relates to an optical film, a polarizing plate using the same, and a liquid crystal display device.
- An optical film such as a cellulose acylate film is used in various liquid crystal display devices as an optical member of a liquid crystal display device, for example, a support for an optical compensation film, a protective film for a polarizing plate, and the like.
- liquid crystal display device In addition to being used indoors, such as for TV applications, the liquid crystal display device has been increasingly used outdoors, for example, mainly for portable devices. Therefore, development of a liquid crystal display device that can withstand use at higher temperatures and higher humidity than before has been demanded. In addition, liquid crystal display devices are increasingly required to endure even under severe usage conditions in various applications, and a higher level of durability than ever has been required year by year. In recent years, liquid crystal display devices are becoming larger and thinner mainly for TV applications, and accordingly, optical films as constituent members are also required to be thinner. Conventionally, an optical film has been emphasized from the viewpoint of workability, and appropriate hardness and good cutting properties have been emphasized. However, an optical film having a reduced thickness has been required to be further improved.
- an optical film using a cellulose acylate film it is known that a specific compound is contained in the film in order to further improve the performance and solve various problems in the properties and production as an optical film.
- a specific compound is contained in the film in order to further improve the performance and solve various problems in the properties and production as an optical film.
- an aliphatic or aromatic monocarboxylic acid or organic phosphoric acid having a pKa of 2 to 7 see Patent Document 1
- an iminodiacetic acid type organic carboxylic acid compound having two carboxy groups pKa 5.5 or less
- Patent Documents 1 and 2 improves the durability of the polarizer under high temperature and high humidity and high temperature and low humidity, and supports in solution casting The peelability from the resin was greatly improved.
- the durability of the polarizer and the haze-suppressing effect are insufficient when the evaluation is continued for a longer period of time or under harsher conditions under high temperature and high humidity. I understood.
- the compounds described in these patent documents do not necessarily have sufficient compatibility with cellulose acylate, and will evaporate from the cellulose acylate film under long-term severe environmental conditions, resulting in a decrease in effective concentration and haze. Occurred.
- the present invention can suppress the volatility of the compound from the film even under long and severe conditions under high temperature and high humidity, and can improve the durability of the polarizer, and at the same time includes cellulose acylate. It is an object of the present invention to provide an optical film in which generation of haze in the optical film is suppressed, a polarizing plate using the same, and a liquid crystal display device.
- Patent Documents 1 and 2 show an effect on the durability of the polarizer.
- the compounds described in these patent documents are caused by volatilization from the cellulose acylate film. That is, it has been clarified that the effect of improving the durability of the polarizer accompanying a change with time is reduced by reducing the effective concentration of these compounds in the film.
- the phenomenon of the compounds evaporating from the film is not necessarily sufficiently compatible with the cellulose acylate coexisting with these compounds in the film, or the interaction between the added compound and the cellulose acylate is weak. It was thought to be based on that.
- R 1 represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a heterocyclic group, an acyl group, an alkoxycarbonyl group, a carbamoyl group, an alkylsulfonyl group or an arylsulfonyl group.
- R 2 represents an alkyl group or an aryl group.
- L represents a single bond or a linking group having a valence of 2 or more, n is 1 when L is a single bond, and is an integer having a valence of L-1 when L is a linking group having a valence of 2 or more.
- s and t each independently represent 1, 2 or 3.
- X represents —O— or —N (Ra) —.
- Ra represents a hydrogen atom or an alkyl group.
- ⁇ 2> The optical film according to ⁇ 1>, wherein L is a single bond, an alkylene group, or an alkanetriyl group.
- ⁇ 3> The optical film according to ⁇ 1> or ⁇ 2>, wherein L is an alkylene group.
- ⁇ 4> The optical film according to any one of ⁇ 1> to ⁇ 3>, wherein the compound represented by the general formula (I) is a compound represented by the following general formula (II).
- R 2 represents an alkyl group or an aryl group.
- s, t and u each independently represents 1, 2 or 3.
- X and Y each independently represent —O— or —N (Ra) —.
- Ra represents a hydrogen atom or an alkyl group.
- R 3 represents an alkyl group or an aryl group.
- ⁇ 5> The optical film according to any one of ⁇ 1> to ⁇ 4>, wherein R 2 is an alkyl group which may be substituted with an aryl group or a cycloalkyl group.
- ⁇ 6> R 2 The optical film according to any one of a following general formula (1) or (2) ⁇ 1> to ⁇ 5>.
- l represents an integer of 1 to 5
- Cy, Cy 1 and Cy 2 each independently represents an aryl group or a cycloalkyl group.
- the optical film comprises at least two layers, and further comprises a hard coat layer in a layer containing cellulose acylate and at least one compound represented by the general formula (I).
- a liquid crystal display device having at least the polarizing plate according to ⁇ 12> and a liquid crystal cell.
- a numerical range represented by using “to” means a range including numerical values described before and after that as a lower limit value and an upper limit value.
- alkyl group means an alkyl group which may have a substituent.
- aliphatic group is a linear, branched or cyclic aliphatic group which may be saturated or unsaturated (does not become an aromatic ring).
- substituents and linking groups hereinafter referred to as substituents and the like
- substituents and the like when a plurality of substituents and linking groups (hereinafter referred to as substituents and the like) are specified simultaneously or alternatively, the respective substituents and the like may be the same or different from each other.
- an optical film containing cellulose acylate that can improve the durability of a polarizer under aging under severe conditions such as high temperature and high humidity, suppress volatilization of a compound from the optical film, and suppress haze generation.
- a polarizing plate and a liquid crystal display device using an optical film can be provided.
- FIG. 1 is an example schematically showing the internal structure of the liquid crystal display device of the present invention.
- FIG. 2 is an example schematically showing the internal structure of another liquid crystal display device of the present invention.
- the optical film of the present invention comprises at least one cellulose acylate film containing cellulose acylate and at least one compound represented by the general formula (I).
- the optical film may be composed of a plurality of layers, but the compound represented by the general formula (I) may be contained in any layer, or may be contained in all layers. .
- the cellulose acylate film or layer means that the resin component constituting the film or layer contains 50% by mass or more of cellulose acylate, and the content of cellulose acylate in the resin component is 60 mass% or more is preferable, 70 mass% or more is more preferable, 80 mass% or more is further more preferable, 85 mass% is especially preferable, 90 mass% or more is especially preferable, and 95 mass% or more is the most preferable.
- the optical film of the present invention includes, in addition to the cellulose acylate film as described above, as a resin component, it does not contain cellulose acylate, or even if it contains it, it is a multilayer structure with a layer of less than 50% by mass of the entire resin component May be formed.
- a layer include a layer specialized for a specific function, such as a hard coat layer.
- a hard coat layer for example, an antiglare layer, a clear hard coat layer, an antireflection layer, an antistatic layer, an antifouling layer and the like can be mentioned. In the present invention, these layers are preferably provided on the hard coat layer.
- the optical film of the present invention is useful for various applications such as a polarizing plate protective film and a surface protective film disposed on an image display surface.
- the cellulose acylate film is a film having a cellulose acylate ratio of 50% by mass or more in the resin component, and is a narrowly defined optical film in the present invention.
- the cellulose acylate film may be a single layer or a laminate of two or more layers.
- the layer here does not include a functional layer as described above, and means a layer containing 50% by mass or more of cellulose acylate with respect to the entire resin component.
- the cellulose acylate film is a laminate of two or more layers, a two-layer structure or a three-layer structure is more preferable, and a three-layer structure is preferable.
- the cellulose acylate film of the present invention preferably has a three-layer structure of skin layer B / core layer / skin layer A.
- a laminate can be produced by various known casting methods such as co-casting described later.
- the skin layer B is a layer in contact with a metal support described later when the cellulose acylate film is produced by solution casting, and the skin layer A is an air interface layer on the side opposite to the metal support.
- Skin layer A and skin layer B are also collectively referred to as a skin layer (or surface layer).
- the acyl substitution degree of cellulose acylate in each layer may be uniform, or a plurality of cellulose acylates may be mixed in one layer. However, it is preferable from the viewpoint of adjustment of optical properties that the acyl substitution degree of cellulose acylate in each layer is all constant. In addition, when the cellulose acylate film of the present invention has a three-layer structure, it is preferable from the viewpoint of production cost that the cellulose acylate contained in the surface layers on both sides is a cellulose acylate having the same acyl substitution degree.
- the cellulose acylate film contains cellulose acylate and at least one compound represented by the following general formula (I).
- R 1 represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a heterocyclic group, an acyl group, an alkoxycarbonyl group, a carbamoyl group, an alkylsulfonyl group or an arylsulfonyl group.
- R 2 represents an alkyl group or an aryl group.
- L represents a single bond or a linking group having a valence of 2 or more
- n is 1 when L is a single bond
- s and t each independently represent 1, 2 or 3.
- X represents —O— or —N (Ra) —.
- Ra represents a hydrogen atom or an alkyl group.
- the alkyl group for R 1 preferably has 1 to 30 carbon atoms, more preferably 1 to 24, and still more preferably 1 to 20 carbon atoms.
- the alkenyl group for R 1 preferably has 2 to 30 carbon atoms, more preferably 2 to 24 carbon atoms, and still more preferably 2 to 20 carbon atoms.
- the aryl group for R 1 preferably has 6 to 30 carbon atoms, more preferably 6 to 24, and still more preferably 6 to 20 carbon atoms.
- the heterocyclic group for R 1 is preferably a 5- or 6-membered ring, and this ring may be condensed with a benzene ring.
- the hetero atom constituting the hetero ring is preferably an atom selected from a nitrogen atom, an oxygen atom, and a sulfur atom, and may be an aromatic ring, an unsaturated ring that is not an aromatic ring, or a saturated ring. Absent.
- the number of carbon atoms in the heterocycle is preferably 0-30, more preferably 1-24, and even more preferably 2-20.
- the acyl group in R 1 may be any of an arylcarbonyl group, an alkylcarbonyl group, an alkenylcarbonyl group, a heterocyclic carbonyl group, and a formyl group, and preferably has 1 to 30 carbon atoms, more preferably 2 to 24, 2 to 20 is more preferable.
- the number of carbon atoms of the alkoxycarbonyl group in R 1 is preferably 2 to 30, more preferably 2 to 24, and even more preferably 2 to 20.
- the carbamoyl group in R 1 is any of a carbamoyl group, an N-alkylcarbamoyl group, an N, N-dialkylcarbamoyl group, an N-arylcarbamoyl group, an N, N-diarylcarbamoyl group, and an N-alkyl-N-arylcarbamoyl group.
- the number of carbon atoms may be 1 to 30, preferably 2 to 24, and more preferably 2 to 20.
- the alkylsulfonyl group for R 1 preferably has 1 to 30 carbon atoms, more preferably 1 to 24, and still more preferably 1 to 20.
- the arylsulfonyl group for R 1 preferably has 6 to 30 carbon atoms, more preferably 6 to 24, and still more preferably 6 to 20 carbon atoms.
- Each of the above groups in R 1 may have a substituent.
- a substituent is not particularly limited, and may be an alkyl group (preferably having 1 to 10 carbon atoms such as methyl, ethyl, isopropyl, t-butyl, pentyl, heptyl, 1-ethylpentyl, benzyl, 2-ethoxy Ethyl, 1-carboxymethyl, etc.), alkenyl groups (preferably having 2 to 20 carbon atoms, such as vinyl, allyl, oleyl, etc.), alkynyl groups (preferably having 2 to 20 carbon atoms, such as ethynyl, butadiynyl, phenyl, etc.
- cycloalkyl groups preferably having 3 to 20 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, etc.
- aryl groups preferably having 6 to 26 carbon atoms, such as phenyl, 1 -Naphthyl, 4-methoxyphenyl, 2-chlorophenyl, 3-methylphenyl
- a heterocyclic group preferably a heterocyclic group having 0 to 20 carbon atoms, wherein the ring-constituting hetero atom is preferably an oxygen atom, a nitrogen atom or a sulfur atom, and a 5- or 6-membered ring is condensed with a benzene ring or a heterocyclic ring.
- this ring may be a saturated ring, an unsaturated ring, or an aromatic ring.
- 2-pyridyl, 4-pyridyl, 2-imidazolyl, 2-benzoimidazolyl, 2-thiazolyl, 2-oxazolyl, etc. An alkoxy group (preferably having 1 to 20 carbon atoms such as methoxy, ethoxy, isopropyloxy, benzyloxy, etc.), an aryloxy group (preferably having 6 to 26 carbon atoms such as phenoxy, 1-naphthyloxy, 3 -Methylphenoxy, 4-methoxyphenoxy, etc.),
- alkylthio group preferably having 1 to 20 carbon atoms, such as methylthio, ethylthio, isopropylthio, benzylthio, etc.
- an arylthio group preferably having 6 to 26 carbon atoms, such as phenylthio, 1-naphthylthio, 3-methylphenylthio, etc.
- sulfonyl groups preferably alkyl or aryl sulfonyl groups, preferably having 1 to 20 carbon atoms, such as methylsulfonyl, ethylsulfonyl, benzenesulfonyl, toluenesulfonyl, etc.
- acyl groups Including alkylcarbonyl group, alkenylcarbonyl group, arylcarbonyl group, and heterocyclic carbonyl group, carbon number is preferably 20 or less, for example, acetyl, pivaloyl, acryloyl, metachloroyl, benzoyl, nicotinoyl, etc.
- alkoxy Rubonyl group preferably having 2 to 20 carbon atoms, such as ethoxycarbonyl, 2-ethylhexyloxycarbonyl, etc.
- aryloxycarbonyl group preferably having 7 to
- carbamoyl groups preferably alkyl or aryl carbamoyl groups, preferably having 1 to 20 carbon atoms, eg, N, N-dimethylcarbamoyl, N-phenylcarbamoyl etc.
- acylamino Group
- the above substituent may be further substituted with the above substituent.
- substituents include a perfluoroalkyl group such as trifluoromethyl, an aralkyl group, and an alkyl group substituted with an acyl group.
- substituents include not only substituents that each group of R 1 , R 3 , R 5 , and Ra may have, but also substituents in other compounds described in this specification including L. Applied.
- each said group in R ⁇ 1 > may have, an alkyl group, an alkenyl group, and an aryl group are preferable.
- the alkyl group in R 2 and Ra has the same preferred range as the alkyl group in R 1
- the aryl group in R 2 has the same preferred range as the aryl group in R 1 .
- L represents a single bond or a divalent or higher valent linking group
- the divalent or higher valent linking group is preferably a divalent alkylene group, an arylene group, —O—, —S— or a combination thereof.
- the trivalent group include an alkanetriyl group, an arenetriyl group, and —N ⁇ , and the above divalent linking group may be combined with these groups.
- the tetravalent group include an alkanetetrayl group and an arenetetrayl group.
- the divalent or higher valent linking group in L may have a substituent.
- L is preferably a single bond or a divalent to trivalent linking group, more preferably a single bond, an alkylene group or an alkanetriyl group, and still more preferably an alkylene group or an alkanetriyl group.
- the alkylene group preferably has 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, more preferably 1 or 2, and most preferably 1. Specific examples include an ethylene group, a propylene group, a trimethylene group, and a tetramethylene group.
- R 1 is preferably an acyl group, an alkoxycarbonyl group, a carbamoyl group, an alkylsulfonyl group, or an arylsulfonyl group, and more preferably an alkoxycarbonyl group or a carbamoyl group.
- the alkanetriyl group includes a methylidene group, and examples thereof include ethane-1,2,2-triyl group, propane-1,3,3-triyl group and butane-1,4-triyl group, and L is alkanetriyl group.
- R 1 is preferably a hydrogen atom or an alkyl group, more preferably a hydrogen atom.
- R 1 is preferably an alkyl group, an alkenyl group, an aryl group, a heterocyclic group, an acyl group, an alkoxycarbonyl group, a carbamoyl group, an alkylsulfonyl group, an arylsulfonyl group, an acyl group, an alkoxycarbonyl group, A carbamoyl group, an alkylsulfonyl group, and an arylsulfonyl group are more preferable.
- N is 1 when L is a single bond, and when L is a linking group having a valence of 2 or more, it is an integer having a valence of L-1. That is, when L is divalent, n is 1, and when L is trivalent, n is 2.
- S and t are preferably 1 or 2, and 1 is particularly preferable. Moreover, it is preferable that both s and t are the same integer.
- X represents —O— or —N (Ra) —, preferably —O—.
- R 2 is preferably an alkyl group which may be substituted by an aryl group or a cycloalkyl group, and among them, the following general formula (1) or (2) is preferable.
- l represents an integer of 1 to 5
- Cy, Cy 1 and Cy 2 each independently represents an aryl group or a cycloalkyl group.
- Cy, Cy 1 and Cy 2 are preferably a phenyl group or a cyclohexyl group, and more preferably a phenyl group.
- the compound represented by the general formula (I) preferably has 1 to 5 cyclic groups or cyclic partial structures in the molecule, more preferably 1 to 4 and more preferably 2 to 4 Is more preferable, and it is particularly preferable to have two.
- the cyclic group or the cyclic group in the cyclic partial structure is preferably an arene ring or a cycloalkyl ring, and more preferably a benzene ring or a cyclohexane ring.
- the compound represented by the general formula (I) is preferably a compound represented by the following general formula (II).
- R 2, X , s and t have the general formula (I) have the same meanings as R 2, X, s and t in, and the preferred range is also the same.
- u represents 1, 2 or 3 and the preferred range is the same as s and t.
- R 3 has the same meaning as R 2 , and the preferred range is also the same.
- Y is synonymous with X, and its preferable range is also the same.
- the molecular weight of the compound represented by the general formula (I) is preferably 250 to 800, more preferably 330 to 650.
- the coloring suppression under the light irradiation of a cellulose acylate film, and the adhesive improvement effect at the time of providing a hard-coat layer etc. can also be acquired.
- the detailed mechanism is not clear, the present inventors believe that it is caused by incorporating a precursor of a carboxy group that generates a carboxy group over time.
- the compound represented by the general formula (I) of the present invention can be synthesized, for example, by a method via a monoester form.
- the content of the compound represented by the general formula (I) in the optical film is not particularly limited, but is preferably 0.1 to 20 parts by mass, and 0.5 to 15 parts by mass with respect to 100 parts by mass of cellulose acylate. Part is more preferable, 0.5 to 10 parts by mass is further preferable, and 1.0 to 5 parts by mass is particularly preferable.
- the polarizer durability which is the effect of this invention, and the inhibitory effect of a haze rise will fully express.
- the total amount is preferably within the above range.
- the cellulose acylate used as the main component of a cellulose acylate film, and 2 or more types may be used for it.
- the cellulose acylate may be a cellulose acetate consisting only of an acetyl group as an acyl substituent, or a cellulose acylate having a plurality of different acyl substituents, or a mixture of different cellulose acylates. May be.
- Cellulose acylate raw material cellulose used in the present invention includes cotton linter and wood pulp (hardwood pulp, conifer pulp), and any cellulose obtained from any raw material cellulose can be used, optionally mixed. May be.
- Raw material cellulose is, for example, Marusawa and Uda, “Plastic Materials Course (17) Fibrous Resin”, Nikkan Kogyo Shimbun (published in 1970) and JIII Journal of Technical Publication No. 2001-1745 (page 7). To page 8) can be used.
- acyl group of cellulose acylate may be used, or two or more types of acyl groups may be used.
- the cellulose acylate used in the present invention preferably has an acyl group having 2 or more carbon atoms as a substituent.
- the acyl group having 2 or more carbon atoms may be an aliphatic acyl group or an aromatic acyl group, and is not particularly limited. These are, for example, an alkylcarbonyl group, an alkenylcarbonyl group, an aromatic carbonyl group, an aromatic alkylcarbonyl group or the like of cellulose, and each may further have a substituted group.
- Preferred examples of these include acetyl, propionyl, butanoyl, heptanoyl, hexanoyl, octanoyl, decanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, hexadecanoyl, octadecanoyl, isobutanoyl, tert-butanoyl, cyclohexanecarbonyl, oleoyl, benzoyl , Naphthylcarbonyl, cinnamoyl and the like.
- acetyl, propionyl, butanoyl group, dodecanoyl, octadecanoyl, tert-butanoyl, oleoyl, benzoyl, naphthylcarbonyl, cinnamoyl and the like are more preferable, and acetyl, propionyl and butanoyl are more preferable.
- the cellulose acylate used in the present invention preferably has an acyl group having 2 to 4 carbon atoms as a substituent.
- one of them is preferably an acetyl group, and the remaining acyl group is preferably a propionyl group or a butyryl group.
- the acyl group of cellulose acylate is one kind of acetyl group because the compound represented by formula (I) is excellent in improving the durability of the polarizer.
- the cellulose acylate preferably used in the present invention will be described in detail.
- the ⁇ -1,4-bonded glucose unit constituting cellulose has free hydroxy groups at the 2nd, 3rd and 6th positions.
- Cellulose acylate is a polymer obtained by acylating part or all of these hydroxy groups with an acyl group.
- the degree of acyl substitution indicates the degree of acylation of the hydroxy group of cellulose located at the 2-position, 3-position and 6-position, and all the 2-position, 3-position and 6-position hydroxy groups of all glucose units are When acylated, the total degree of acyl substitution is 3. For example, in all glucose units, when only the 6-position is all acylated, the total acyl substitution degree is 1.
- the total acyl substitution degree is 1 when all of either the 6-position or the 2-position are acylated in each glucose unit in all hydroxy groups of all glucose. That is, the degree of acylation is indicated by 3 when all hydroxy groups in the glucose molecule are all acylated.
- the total acyl substitution degree A of the cellulose acylate used in the present invention is preferably 1.5 or more and 3.0 or less (1.5 ⁇ A ⁇ 3.0), more preferably 2.00 to 2.97. It is more preferably from .50 to less than 2.97, particularly preferably from 2.70 to 2.95.
- the total acetyl substitution degree B is preferably 2.0 or more and 3 or less (2.0 ⁇ B ⁇ 3.0), 2.0 To 2.97 is more preferable, 2.5 to 2.97 is more preferable, 2.55 to less than 2.97 is particularly preferable, 2,60 to 2.96 is particularly preferable, and 2.70 to 2.97. Most preferred is 95.
- the compound represented by the general formula (I) of the present invention is particularly effective for cellulose acylate having a total acetyl substitution degree B exceeding 2.50.
- the cellulose acylate film of the optical film of the present invention is a laminate (multi-layer structure)
- the cellulose acylate film has a plurality of cellulose acylates even if the acyl substitution degree of the cellulose acylate in each layer is uniform.
- the rates may be mixed in one layer.
- acylation of cellulose when an acid anhydride or acid chloride is used as an acylating agent, methylene chloride or an organic acid such as acetic acid is used as an organic solvent as a reaction solvent.
- the catalyst when the acylating agent is an acid anhydride, a protic catalyst such as sulfuric acid is preferably used, and when the acylating agent is an acid chloride (for example, CH 3 CH 2 COCl), Basic compounds are used.
- the most common industrial synthesis method for mixed fatty acid esters of cellulose is to use cellulose mixed fatty acids containing fatty acids (acetic acid, propionic acid, valeric acid, etc.) corresponding to acetyl groups and other acyl groups or anhydrides thereof. This is a method of acylating with components.
- Cellulose acylate can be synthesized, for example, by the method described in JP-A-10-45804.
- the film of the present invention particularly the cellulose acylate film used in the present invention, preferably contains 5 to 99% by mass of cellulose acylate in the total solid content from the viewpoint of moisture permeability, and more preferably 20 to 99% by mass.
- the content is preferably 50 to 95% by mass.
- a polycondensation ester compound (polymer) and a polyhydric alcohol are used as retardation adjusting agents (retardation agents and retardation reducing agents) and plasticizers.
- Additives such as valent esters, phthalic acid esters, phosphoric acid esters, and the like, and ultraviolet absorbers, antioxidants, matting agents and the like can also be added.
- the compound group may be described by incorporating a “system” such as a phosphate ester compound in the above case. Means the same.
- retardation reducing agent a compound other than a phosphate ester compound or a known non-phosphate ester compound as an additive for a cellulose acylate film can be widely used.
- the polymer retardation reducing agent is preferably a polymer selected from a polyester polyester polymer, a styrene polymer, an acrylic polymer, and a copolymer thereof, and more preferably an acrylic polymer and a styrene polymer. Moreover, it is preferable to contain at least one polymer having negative intrinsic birefringence, such as a styrene polymer and an acrylic polymer.
- Examples of the low molecular weight retardation reducing agent for compounds other than non-phosphate ester compounds include the following compounds. These may be solid or oily. That is, the melting point and boiling point are not particularly limited. For example, mixing of an ultraviolet absorbing material at 20 ° C. or lower and 20 ° C. or higher, and a mixture of deterioration preventing agents are also possible. As the infrared absorbing dye, for example, those described in JP-A No. 2001-194522 are preferable. The timing for adding these may be any step in the cellulose acylate solution (dope) preparation step. In addition, a step of adding an additive to the final preparation step of the dope preparation step may be newly added. The amount of each material added is not particularly limited as long as the function is manifested.
- the low molecular weight retardation reducing agent for compounds other than non-phosphate compounds is not particularly limited, but details are described in paragraph numbers 0066 to 0085 of JP-A-2007-272177.
- the compound represented by the general formula (1) described in paragraph Nos. 0066 to 0085 of JP-A-2007-272177 can be obtained by a condensation reaction between a sulfonyl chloride derivative and an amine derivative.
- the compound represented by the general formula (2) described in Japanese Patent Application Laid-Open No. 2007-272177 is a dehydration condensation reaction between a carboxylic acid and an amine using a condensing agent (for example, dicyclohexylcarbodiimide (DCC)). It can be obtained by a substitution reaction between an acid chloride derivative and an amine derivative.
- a condensing agent for example, dicyclohexylcarbodiimide (DCC)
- the retardation reducing agent is more preferably an Rth reducing agent from the viewpoint of realizing a suitable Nz factor.
- Rth means retardation in the film thickness direction of the cellulose acylate film.
- examples of the Rth reducing agent include acrylic polymers and styrene polymers, and low molecular compounds represented by general formulas (3) to (7) described in JP-A-2007-272177. be able to. Among these, acrylic polymers and styrene polymers are preferable, and acrylic polymers are more preferable.
- the retardation reducing agent is preferably added in a proportion of 0.01 to 30% by mass, more preferably 0.1 to 20% by mass, more preferably 0.1 to 10%, relative to the cellulose resin. It is particularly preferable to add at a ratio of mass%. By making the addition amount 30% by mass or less, compatibility with the cellulose resin can be improved, and a film having excellent transparency can be produced. When using two or more types of retardation reducing agents, the total amount is preferably within the above range.
- the optical film of the present invention may contain at least one retardation developer in order to develop a retardation value.
- the retardation developer is not particularly limited, and examples thereof include those composed of rod-like or discotic compounds and compounds exhibiting retardation development among the non-phosphate ester compounds.
- a compound having at least two aromatic rings is preferable as the retardation developer.
- the addition amount of the retardation enhancer composed of a rod-like compound is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the polymer component containing cellulose acylate.
- the discotic compound Since the discotic compound is superior to the rod-shaped compound in Rth retardation expression, it is preferably used when a particularly large Rth retardation is required. Two or more retardation developing agents may be used in combination.
- the retardation developer preferably has a maximum absorption in the wavelength region of 250 to 400 nm, and preferably has substantially no absorption in the visible region. Details of the retardation enhancer are described on page 49 of the published technical bulletin 2001-1745.
- the addition amount of the retardation enhancer composed of a discotic compound is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the polymer component containing cellulose acylate.
- the compound represented by the general formula (I) of the present invention can also be used as a plasticizer by being contained in an optical film, particularly a cellulose acylate film. That is, the durability improvement effect including the control of the glass transition temperature and the reduction of moisture content and moisture permeability as described above can be obtained, and at the same time, the polarizer durability of the cellulose acylate film can be enhanced. Furthermore, the compound represented by the general formula (I) of the present invention can exhibit the effect of improving the durability of the polarizer even when used in combination with other commonly used plasticizers. For this reason, you may make it contain in an optical film and a cellulose acylate film combining several plasticizers.
- polyester plasticizers examples include polycondensation ester compounds (hereinafter referred to as polycondensation ester plasticizers), polyhydric alcohol polyester compounds (hereinafter referred to as polyhydric alcohol ester plasticizers). And carbohydrate compounds (hereinafter referred to as carbohydrate derivative plasticizers). In the present invention, these compounds are excellent in the plasticizer effect described above.
- the plasticizer used in the present invention will be described below.
- the polycondensed ester plasticizer is obtained by polycondensation of a divalent carboxylic acid compound and a diol compound.
- the polycondensation ester plasticizer is preferably obtained by polycondensation of at least one dicarboxylic acid represented by the following general formula (a) and at least one diol represented by the following general formula (b). .
- Xa is a divalent aliphatic group having 2 to 18 carbon atoms, a divalent aromatic group having 6 to 18 carbon atoms, or a divalent heterocyclic ring having 2 to 18 carbon atoms.
- Z represents a divalent aliphatic group having 2 to 8 carbon atoms.
- the divalent aliphatic group having 2 to 8 carbon atoms may be linear or branched.
- Examples of the divalent carboxylic acid compound represented by the general formula (a) include aliphatic carboxylic acids, aromatic or heterocyclic carboxylic acids as described above, preferably aliphatic carboxylic acids or aromatics. Carboxylic acid.
- examples of the diol compound include aromatic or heterocyclic compounds in addition to the aliphatic compound represented by the general formula (b).
- those obtained from at least one dicarboxylic acid having an aromatic ring (also referred to as aromatic dicarboxylic acid) and at least one aliphatic diol having an average carbon number of 2.5 to 8.0 are preferable. Also preferred are those obtained from a mixture of an aromatic dicarboxylic acid and at least one aliphatic dicarboxylic acid and at least one aliphatic diol having an average carbon number of 2.5 to 8.0.
- the number average molecular weight of the polycondensed ester plasticizer is preferably 500 to 2000, more preferably 600 to 1500, and still more preferably 600 to 1200. If the number average molecular weight of the polycondensed ester is 600 or more, the volatility is low, and the film failure and process contamination due to volatilization under high temperature conditions during stretching of the cellulose acylate film are excellent. Moreover, if a number average molecular weight is 2000 or less, compatibility with a cellulose acylate will become high, and it will be excellent in suppression of the bleed-out at the time of film forming and heat-stretching.
- a dicarboxylic acid having an average carbon number of 5.5 to 10.0 in the dicarboxylic acid component is preferable, and more preferably 5.6 to 8.0. If the average carbon number is 5.5 or more, a polarizing plate having excellent durability can be obtained. If the average number of carbon atoms is 10 or less, the compatibility with cellulose acylate is excellent, and the suppression of bleed-out is excellent in the process of forming a cellulose acylate film.
- Aromatic dicarboxylic acids that can be used for the synthesis of the polycondensed ester plasticizer include, for example, phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,8- Examples thereof include naphthalenedicarboxylic acid, 2,8-naphthalenedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid. Of these, phthalic acid, terephthalic acid, and 2,6-naphthalenedicarboxylic acid are preferable, phthalic acid and terephthalic acid are more preferable, and terephthalic acid is more preferable.
- the polycondensation ester obtained from a diol compound and a dicarboxylic acid containing an aliphatic dicarboxylic acid contains an aliphatic dicarboxylic acid residue.
- the aliphatic dicarboxylic acid for synthesizing the polycondensed ester plasticizer include oxalic acid, malonic acid, succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, Examples include dodecanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid.
- the diol for synthesizing the polycondensed ester plasticizer include an aromatic diol and an aliphatic diol. In the present invention, the diol is preferably synthesized using at least an aliphatic diol.
- the polycondensed ester plasticizer preferably contains an aliphatic diol residue having an average carbon number of 2.5 to 7.0, more preferably an aliphatic diol residue having an average carbon number of 2.5 to 4.0. Contains groups. If the average carbon number of the aliphatic diol residue is less than 7.0, the compatibility with cellulose acylate is improved, due to bleeding out, increased heat loss of the compound, and process contamination during drying of the cellulose acylate web. Excellent suppression of occurrence of possible sheet faults. Further, the synthesis is easy if the average carbon number of the aliphatic diol residue is 2.5 or more.
- the aliphatic diol used for synthesizing the polycondensed ester plasticizer is preferably an alkyl diol or an alicyclic diol, such as ethylene glycol, 1,2-propanediol, and 1,3-propanediol. At least one of ethylene glycol and 1,2-propanediol.
- the terminal of the polycondensed ester plasticizer may be left as diol or carboxylic acid without being sealed (that is, the polymer chain length terminal is —OH or CO 2 H), and further, monocarboxylic acids or monoalcohols may be used. You may make it react and may implement what is called terminal sealing.
- the terminal of the polycondensation ester plasticizer by sealing the terminal of the polycondensation ester plasticizer, the cellulose acylate film is obtained that is not easily in a solid state at normal temperature, has good handling, and has excellent humidity stability and polarizer durability. The effect that it can be obtained.
- the polycondensed ester plasticizer is preferably J-1 to J-38 described in paragraph numbers 0062 to 0064 of JP2012-234159A.
- the polyhydric alcohol ester plasticizer used in the present invention is an ester derived from a polyhydric alcohol having an alcohol part having two or more hydroxy groups.
- the alcohol in the alcohol part includes an ether other than the hydroxy group.
- An alcohol in which two or more hydroxy groups are substituted on a saturated hydrocarbon which may be separated through a bond is preferred.
- the polyhydric alcohol as the raw material for the polyhydric alcohol ester plasticizer is represented by the following general formula (c).
- R ⁇ represents an m-valent organic group, and m represents an integer of 2 or more.
- the number of carbon atoms of the polyhydric alcohol is preferably 5 or more, and more preferably 5 to 20.
- examples of such polyhydric alcohols include sugar alcohols and glycols. Specifically, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, and xylitol are preferable.
- the acid part of the polyhydric alcohol ester (the acyl part of the ester) is preferably an acid part derived from a monocarboxylic acid.
- examples of such acids include aliphatic monocarboxylic acids, alicyclic monocarboxylic acids, and aromatic monocarboxylic acids.
- Carboxylic acid is mentioned. Use of an alicyclic monocarboxylic acid or aromatic monocarboxylic acid is preferred in terms of improving moisture permeability and retention.
- the aliphatic monocarboxylic acid preferably has 1 to 32 carbon atoms, more preferably 1 to 20 carbon atoms, and particularly preferably 1 to 10 carbon atoms.
- acetic acid is contained, the compatibility with the cellulose derivative is increased, and it is also preferable to use a mixture of acetic acid and another monocarboxylic acid.
- Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid, tridecylic acid , Saturated fatty acids such as myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, laccelic acid, undecylenic acid, Examples thereof include unsaturated fatty acids such as oleic acid, sorbic acid, linoleic acid, linolenic acid and arachidonic acid.
- Examples of preferable alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, and derivatives thereof.
- aromatic monocarboxylic acids examples include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenylcarboxylic acid, naphthalenecarboxylic acid, and tetralincarboxylic acid.
- benzoic acid which has or derivatives thereof are mentioned, A benzoic acid is especially preferable.
- the molecular weight of the polyhydric alcohol ester plasticizer is not particularly limited, but is preferably 300 to 3000, and more preferably 350 to 1500. A higher molecular weight is preferable because it suppresses volatilization from the optical film, and a lower molecular weight is preferable in terms of moisture permeability and compatibility with the cellulose derivative.
- the polyhydric alcohol ester plasticizer is preferably, for example, a compound described in paragraph Nos. 0045 to 0049 of JP2012-234159A, and is preferably incorporated as a part of this specification.
- Carbohydrate derivative plasticizer As the carbohydrate derivative plasticizer, monosaccharides or derivatives of carbohydrates containing 2 to 10 monosaccharide units, among which acylated ones are preferable.
- Preferred examples of monosaccharides or carbohydrates containing 2 to 10 monosaccharide units include, for example, ribose, arabinose, xylose, lyxose, glucose, fructose, mannose, galactose, trehalose, maltose, cellobiose, lactose, sucrose, sucralose, ⁇ -cyclodextrin, ⁇ -cyclodextrin, ⁇ -cyclodextrin, ⁇ -cyclodextrin, xylitol, sorbitol, more preferably arabinose, xylose, glucose, fructose, mannose, galactose, maltose, cellobiose, sucrose, ⁇ - Cyclodextrin and ⁇ -cyclodextrin, particularly preferably xylose, glucose, fructose, mannose, galactose, maltose, cellobi Over vinegar, sucrose, xylitol, sorb
- carbohydrate derivative plasticizer examples include maltose octaacetate, cellobiose octaacetate, sucrose octaacetate, xylose tetrapropionate, glucose pentapropionate, fructose pentapropionate, mannose pentapropionate, galactose pentaprote Pionate, maltose octapropionate, cellobiose octapropionate, sucrose octapropionate, xylose tetrabenzoate, glucose pentabenzoate, fructose pentabenzoate, mannose pentabenzoate, galactose pentabenzoate, maltose octabenzoate, cellobiose octabenzoate, sucrose Octabenzoate, xylitol pentabenzoate And sorbitol hexa benzoate is particularly preferred.
- the carbohydrate derivative plasticizer compounds described in paragraph numbers 0030 to 0039 of JP2012-234159A are preferable.
- the plasticizer the contents described in paragraph numbers 0026 to 0068 of JP2012-234159A are preferably applied, and the contents described in these paragraph numbers are part of this specification. Preferably incorporated.
- the addition amount of these plasticizers is preferably 1 to 20% by mass with respect to cellulose acylate. If the content is 1% by mass or more, the effect of improving the durability of the polarizer can be easily obtained, and if the content is 20% by mass or less, bleeding out hardly occurs. A more preferable addition amount is 2 to 15% by mass, and particularly preferably 5 to 15% by mass. Two or more kinds of these plasticizers may be added. Also when adding 2 or more types, the specific example and preferable range of addition amount are the same as the above.
- the timing of adding these plasticizers to the cellulose acylate film is not particularly limited as long as it is added at the time of film formation. For example, you may add at the time of the synthesis
- the optical film of the present invention preferably contains an antioxidant.
- This antioxidant can be added to the cellulose acylate solution.
- known antioxidants such as 2,6-di-tert-butyl-4-methylphenol, 4,4′-thiobis- (6-tert-butyl-3-methylphenol), 1,1 '-Bis (4-hydroxyphenyl) cyclohexane, 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 2,5-di-tert-butylhydroquinone, pentaerythrityl-tetrakis [3- (3 , 5-di-tert-butyl-4-hydroxyphenyl) propionate] or the like can be added.
- a phosphorus-based antioxidant such as -butyl-4-methylphenyl) pentaerythritol diphosphite and bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite.
- the addition amount of the antioxidant is preferably 0.05 to 5.0 parts by mass with respect to 100 parts by mass of cellulose acylate.
- the optical film of the present invention may contain an ultraviolet absorber from the viewpoint of preventing deterioration of a polarizing plate or liquid crystal.
- This ultraviolet absorber can be added to the cellulose acylate solution.
- the ultraviolet absorber those having excellent absorption ability of ultraviolet rays having a wavelength of 370 nm or less and less visible light absorption having a wavelength of 400 nm or more are preferably used from the viewpoint of good liquid crystal display properties.
- the ultraviolet absorber preferably used in the present invention include hindered phenol compounds, hydroxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, and the like. .
- the hindered phenol compounds include 2,6-di-tert-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], N, N′-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamide), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl- 4-hydroxybenzyl) benzene, tris- (3,5-di-tert-butyl-4-hydroxybenzyl) -isocyanurate and the like.
- Benzotriazole compounds include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2,2-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H— Benzotriazol-2-yl) phenol], (2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3,5-triazine, tri Ethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], N, N′-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamide ), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, 2- (2′-hydroxy) Droxy-3 ′, 5′-di-tert-butylphenyl
- a matting agent may be added from the viewpoint of film slipperiness and stable production.
- the matting agent may be an inorganic compound matting agent or an organic compound matting agent.
- the inorganic compound matting agent is an inorganic compound containing silicon (for example, silicon dioxide, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, etc.), titanium oxide, zinc oxide, aluminum oxide, barium oxide. Zirconium oxide, strontium oxide, antimony oxide, tin oxide, tin oxide / antimony, calcium carbonate, talc, clay, calcined kaolin and calcium phosphate are preferred, and inorganic compounds containing silicon and zirconium oxide are more preferred.
- silicon dioxide is particularly preferable because the turbidity of the cellulose acylate film can be reduced.
- the fine particles of silicon dioxide commercially available products having a trade name such as Aerosil R972, R974, R812, 200, 300, R202, OX50, TT600 (manufactured by Nippon Aerosil Co., Ltd.) can be used.
- the fine particles of zirconium oxide for example, those commercially available under trade names such as Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) can be used.
- the organic compound matting agent is preferably a polymer such as a silicone resin, a fluorine resin, and an acrylic resin, and among them, a silicone resin is preferable.
- the silicone resins those having a three-dimensional network structure are particularly preferable.
- Tospearl 103 For example, Tospearl 103, Tospearl 105, Tospearl 108, Tospearl 120, Tospearl 145, Tospearl 3120 and Tospearl 240 (manufactured by Toshiba Silicone Co., Ltd.) A commercial product having a trade name can be used.
- the method is not particularly limited, and any method can be used as long as a desired cellulose acylate solution can be obtained.
- an additive may be contained at the stage of mixing cellulose acylate and a solvent, or an additive may be added after preparing a mixed solution with cellulose acylate and a solvent.
- it may be added and mixed immediately before casting the dope (so-called addition method immediately before).
- the mixing in the immediately preceding addition method is performed by installing screw kneading online.
- a static mixer such as an in-line mixer is preferable, and examples of the in-line mixer include a static mixer SWJ (Toray static type in-pipe mixer Hi-Mixer) (manufactured by Toray Engineering). Is preferred.
- Japanese Patent Application Laid-Open No. 2003-053752 mixes additive liquids having different compositions into the main raw material dope in a method for producing a cellulose acylate film.
- a method is described in which the concentration L, aggregation of matte particles, and the like are eliminated by setting the distance L between the tip of the addition nozzle and the start end of the in-line mixer to 5 times or less of the main raw material pipe inner diameter d.
- the distance (L) between the tip opening of the additive liquid supply nozzle having a composition different from that of the main raw material dope and the start end of the in-line mixer is 10 times or less the inner diameter (d) of the supply nozzle tip opening.
- the in-line mixer is a static unstirred in-tube mixer or a dynamic agitated in-tube mixer.
- the flow rate ratio of the cellulose acylate film main raw material dope / in-line additive solution is 10/1 to 500/1, preferably 50/1 to 200/1.
- Japanese Patent Application Laid-Open No. 2003-014933 has an object to produce a retardation film having little additive bleed-out, no delamination phenomenon between layers, good slipperiness, and excellent transparency.
- the additive may be added to the dissolving kettle, or the solution in which the additive or additive is dissolved or dispersed between the dissolving kettle and the co-casting die is added to the dope being fed.
- a mixing means such as a static mixer in order to improve the mixing property.
- the matting agent is particularly preferably contained in the film in a proportion of 0.05 to 1.0% by mass.
- a proportion of 0.05 to 1.0% by mass By setting it as such a range, the haze of a cellulose acylate film does not become large, and when actually used for a liquid crystal display (LCD), inconveniences such as a decrease in contrast and generation of bright spots are suppressed. In addition, scratch resistance can be realized. From these viewpoints, it is particularly preferable to include them in a proportion of 0.05 to 1.0% by mass.
- the cellulose acylate film exhibits a practically sufficient elastic modulus (tensile elastic modulus).
- the range of the elastic modulus is not particularly limited, but is preferably 1.0 to 7.0 GPa and more preferably 2.0 to 6.5 GPa from the viewpoints of manufacturability and handling properties.
- the compound represented by the general formula (I) of the present invention has an effect of improving the elastic modulus by hydrophobizing the cellulose acylate film by being added to the cellulose acylate film. This is an advantage in the invention.
- the absolute value of the photoelastic coefficient of the cellulose acylate film is preferably 8.0 ⁇ 10 ⁇ 12 m 2 / N or less, more preferably 6 ⁇ 10 ⁇ 12 m 2 / N or less, and even more preferably 5 ⁇ 10 ⁇ 12. m 2 / N or less.
- the photoelastic coefficient is measured and calculated by the following method unless otherwise specified.
- the lower limit value of the photoelastic modulus is not particularly limited, but 0.1 ⁇ 10 ⁇ 12 m 2 / N or more is practical.
- the cellulose acylate film was cut out to 3.5 cm ⁇ 12 cm, and the in-plane retardation (Re) at each load of 250 g, 500 g, 1000 g, and 1500 g with no load was measured using an ellipsometer (M150 [trade name], JASCO Corporation). ) And the photoelastic coefficient is measured by calculating from the slope of the straight line of the Re change with respect to the stress.
- the moisture content of the cellulose acylate film can be evaluated by measuring the equilibrium moisture content at a constant temperature and humidity. Equilibrium moisture content was calculated by measuring the moisture content of the sample that reached equilibrium after standing at the above constant temperature and humidity for 24 hours, and dividing the moisture content (g) by the sample mass (g). It is.
- the moisture content of the cellulose acylate film at 25 ° C. and 80% relative humidity is preferably 5% by mass or less, more preferably 4% by mass or less, and further preferably less than 3% by mass.
- the optical film of the present invention containing a cellulose acylate film is incorporated into a liquid crystal display device as a polarizing plate protective film by reducing the water content of the cellulose acylate film, the display unevenness of the liquid crystal display device under high temperature and high humidity Can be suppressed.
- the lower limit of the moisture content is not particularly limited, but is practically 0.1% by mass or more.
- Moisture permeability of the cellulose acylate film is determined according to the moisture permeability test (cup method) of JIS Z0208 by measuring the mass of water vapor passing through the sample for 24 hours in an atmosphere at a temperature of 40 ° C. and a relative humidity of 90% RH. It can evaluate by converting into the mass of the water vapor
- Moisture permeability of the cellulose acylate film is preferably 500 ⁇ 2000g / m 2 ⁇ day , more preferably 900 ⁇ 1300g / m 2 ⁇ day , particularly preferably 1000 ⁇ 1200g / m 2 ⁇ day .
- the cellulose acylate film preferably has a haze of 1% or less, more preferably 0.7% or less, and particularly preferably 0.5% or less.
- a haze of 1% or less, more preferably 0.7% or less, and particularly preferably 0.5% or less.
- the haze is measured and calculated by the following method.
- the lower limit of haze is not particularly limited, but 0.001% or more is practical.
- a cellulose acylate film of 40 mm ⁇ 80 mm is measured according to JIS K7136 using a haze meter (HGM-2DP, Suga Test Instruments) in an environment of 25 ° C. and a relative humidity of 60%.
- the average film thickness of the cellulose acylate film is preferably 10 to 100 ⁇ m, more preferably 15 to 80 ⁇ m, and even more preferably 15 to 70 ⁇ m.
- the thickness is 15 ⁇ m or more, the handling property when producing a web-like film is improved, which is preferable.
- it by setting it as 70 micrometers or less, it is easy to respond to a humidity change and it is easy to maintain an optical characteristic.
- the film thickness of the core layer is preferably 3 to 70 ⁇ m, more preferably 5 to 60 ⁇ m, and the film thicknesses of the skin layer A and the skin layer B are both 0.5 Is more preferably from 20 to 20 ⁇ m, particularly preferably from 0.5 to 10 ⁇ m, most preferably from 0.5 to 3 ⁇ m.
- the width of the cellulose acylate film is preferably 700 to 3000 mm, more preferably 1000 to 2800 mm, and particularly preferably 1300 to 2500 mm.
- the manufacturing method of the cellulose acylate film of the present invention is not particularly limited, it is preferably manufactured by a melt film forming method or a solution film forming method. Production by a solution casting method (solvent casting method) is more preferable. Examples of production of a cellulose acylate film using a solvent cast method are described in U.S. Pat. Nos. 2,336,310, 2,367,603, 2,492,078, and 2,492. No. 977, No. 2,492,978, No. 2,607,704, No. 2,739,069 and No. 2,739,070, British Patent No. 640731 and Refer to each specification of No. 736892, and Japanese Patent Publication Nos.
- the cellulose acylate film may be subjected to a stretching treatment.
- a stretching treatment refer to, for example, JP-A-62-115035, JP-A-4-152125, 4-284221, 4-298310, and 11-48271. can do.
- a solution casting method As a solution casting method, a method in which the prepared dope is uniformly extruded from a pressure die onto a metal support, and a method using a doctor blade in which the dope once cast on the metal support is adjusted with a blade is used.
- a method using a reverse roll coater that adjusts with a reverse rotating roll
- a method using a pressure die is preferred.
- the pressure die includes a coat hanger type and a T die type, and any of them can be preferably used.
- it can be carried out by various methods for casting a cellulose acylate solution known in the art. By setting, the same effect as the contents described in each gazette can be obtained.
- a lamination casting method such as a co-casting method, a sequential casting method, and a coating method
- the simultaneous co-casting method is used for stable production and production. This is particularly preferable from the viewpoint of cost reduction.
- a cellulose acetate solution (dope) for each layer is prepared.
- the dope for casting of each layer (which may be three layers or more) is simultaneously pressed from another slit or the like on a casting support (band or drum).
- the casting dope for the first layer is first extruded from the casting giusa on the casting support, cast, and dried on the second without drying or drying.
- a casting dope for the layer is extruded from a casting giusa and cast.
- the dope is sequentially cast and laminated to the third layer or more.
- it is a casting method in which the cellulose acylate film is formed by peeling off from the support at an appropriate time and drying.
- the core layer is formed into a film by a solution casting method, a coating solution is prepared to be applied to the surface layer, and the core layer is applied to each side or both sides simultaneously using an appropriate applicator. In this method, a liquid is applied and dried to form a cellulose acylate film having a laminated structure.
- the endlessly running metal support used to manufacture the cellulose acylate film includes a drum whose surface is mirror-finished by chrome plating and a stainless steel belt whose surface is mirror-finished by surface polishing (may be called a band) ) Is used.
- One or more pressure dies are used above the metal support. Preferably 1 or 2 groups. When two or more are installed, the amount of dope to be cast may be divided into various ratios for each die, or the dope may be fed to the dies from each of a plurality of precision quantitative gear pumps.
- the temperature of the dope (resin solution) used for casting is preferably ⁇ 10 to 55 ° C., more preferably 25 to 50 ° C.
- all solution temperatures in the process may be the same or different at different points in the process.
- the solution temperature may be a desired temperature just before casting.
- limiting in particular about the material of the said metal support body However
- the manufacturing method of a cellulose acylate film includes the process of peeling off the said dope film
- peeling method there is no restriction
- Extension process In the manufacturing method of a cellulose acylate film, it is preferable to include the process of extending
- the stretching direction of the cellulose acylate film is preferably either the cellulose acylate film transport direction (MD direction) or the direction orthogonal to the transport direction (TD direction), but the direction orthogonal to the cellulose acylate film transport direction (TD direction). It is particularly preferable from the viewpoint of the subsequent polarizing plate processing process using the cellulose acylate film.
- Methods for stretching in the TD direction are described in, for example, JP-A-62-115035, JP-A-4-152125, JP-A-2842211, JP-A-298310, and JP-A-11-48271. Yes.
- the cellulose acylate film winding speed is made faster than the cellulose acylate film stripping speed.
- the acylate film is stretched.
- the cellulose acylate film can also be stretched by conveying while holding the width of the cellulose acylate film with a tenter and gradually increasing the width of the tenter. After the cellulose acylate film is dried, it can be stretched using a stretching machine (preferably uniaxial stretching using a long stretching machine).
- the transmission axis of the polarizer and the in-plane slow axis of the cellulose acylate film are used to suppress light leakage when the polarizing plate is viewed from an oblique direction. Need to be placed in parallel.
- the transmission axis of a roll film-like polarizer produced continuously is generally parallel to the width direction of the roll film.
- the in-plane slow axis of the roll film-like protective film is cellulose acylate. It is necessary to be parallel to the width direction of the film. Therefore, it is preferable to stretch more in the TD direction.
- the stretching process may be performed in the middle of the film forming process, or the original fabric that has been formed and wound may be stretched.
- the stretching in the TD direction is preferably 5 to 100% stretching, more preferably 5 to 80% stretching, and particularly preferably 5 to 40% stretching.
- unstretched means that stretching is 0%.
- the stretching process may be performed in the middle of the film forming process, or the original fabric that has been formed and wound may be stretched. In the former case, stretching may be performed in a state containing a residual solvent.
- the amount of residual solvent (mass of residual volatile matter / film mass after heat treatment) ⁇ 100% is 0.05 to 50%
- the film can be preferably stretched. It is particularly preferable to perform 5 to 80% stretching in a state where the residual solvent amount is 0.05 to 5%.
- the method for producing a cellulose acylate film includes a step of drying the cellulose acylate film and a step of stretching the dried cellulose acylate film at a glass transition temperature (Tg) of ⁇ 10 ° C. or higher. It is preferable from the viewpoint of expression of the foundation.
- the drying of the dope on the metal support involved in the production of the cellulose acylate film is generally applied with hot air from the surface side of the metal support (drum or belt), that is, the surface of the web on the metal support.
- Method, method of applying hot air from the back of the drum or belt contact the temperature-controlled liquid from the back of the belt or drum opposite the dope casting surface, and heat the drum or belt by heat transfer to control the surface temperature
- the back surface liquid heat transfer method is preferable.
- the surface temperature of the metal support before casting may be any temperature as long as it is not higher than the boiling point of the solvent used for the dope. However, in order to accelerate drying and lose fluidity on the metal support, it is preferable to set the temperature 1 to 10 ° C. lower than the boiling point of the lowest boiling solvent among the solvents used. . However, this is not the case when the casting dope is cooled and peeled off without drying.
- the thickness of the cellulose acylate film can be adjusted by adjusting the solid content concentration in the dope, the slit gap of the die cap, the extrusion pressure from the die, the metal support speed, etc. That's fine.
- the length of the cellulose acylate film is preferably wound at 100 to 10000 m per roll, more preferably 500 to 7000 m, and further preferably 1000 to 6000 m.
- the knurling width is preferably 3 mm to 50 mm, more preferably 5 mm to 30 mm, and the height is preferably 0.5 to 500 ⁇ m, more preferably 1 to 200 ⁇ m. This may be a single push or a double push.
- the film width is preferably set to 1470 mm or more.
- the polarizing plate protective film of the present invention is produced not only in the form of a film piece cut into a size that can be incorporated into a liquid crystal display device as it is, but also in a long shape by continuous production. The film of the aspect wound up in the shape is also included. The polarizing plate protective film of the latter mode is stored and transported in that state, and is cut into a desired size and used when it is actually incorporated into a liquid crystal display device or bonded to a polarizer or the like.
- the hard coat layer optionally provided on the cellulose acylate film is a layer for imparting hardness and scratch resistance to the optical film of the present invention.
- a hard coat layer having high adhesion to the cellulose acylate film in combination with the compound represented by the general formula (I) of the present invention by applying and curing the coating composition on the cellulose acylate film. Can be formed.
- mechanical properties such as mechanical, electrical and optical physical performance and chemical performance such as water repellency and oil repellency can be imparted to the hard coat layer itself.
- the thickness of the hard coat layer is preferably from 0.1 to 6 ⁇ m, more preferably from 3 to 6 ⁇ m.
- the hard coat layer is preferably formed by curing the curable composition.
- the curable composition is preferably prepared as a liquid coating composition.
- An example of a coating composition contains a monomer or oligomer for matrix-forming binder, polymers and an organic solvent.
- a hard coat layer can be formed by curing the coating composition after coating. For curing, a crosslinking reaction or a polymerization reaction can be used.
- Examples of available matrix-forming binder monomers or oligomers include ionizing radiation curable polyfunctional monomers and polyfunctional oligomers.
- the polyfunctional monomer or polyfunctional oligomer is preferably a monomer capable of crosslinking reaction or polymerization reaction.
- As the functional group of the ionizing radiation-curable polyfunctional monomer or polyfunctional oligomer those which are polymerized by light, electron beam or radiation are preferable, and among them, the photopolymerizable functional group is preferable.
- photopolymerizable functional group examples include unsaturated polymerizable functional groups such as (meth) acryloyl group, vinyl group, styryl group, and allyl group, and ring-opening polymerizable functional groups such as epoxy compounds. Of these, a (meth) acryloyl group is preferred.
- photopolymerizable polyfunctional monomer having a photopolymerizable functional group examples include (meth) alkylene glycols such as neopentyl glycol acrylate, 1,6-hexanediol (meth) acrylate, and propylene glycol di (meth) acrylate.
- Acrylic acid diesters (Meth) acrylic acid diesters of polyoxyalkylene glycols such as triethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate; (Meth) acrylic acid diesters of polyhydric alcohols such as pentaerythritol di (meth) acrylate; (Meth) acrylic acid diesters of ethylene oxide or propylene oxide adducts such as 2,2-bis ⁇ 4- (acryloxy-diethoxy) phenyl ⁇ propane and 2,2-bis ⁇ 4- (acryloxy-polypropoxy) phenyl ⁇ propane And the like.
- polyoxyalkylene glycols such as triethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth)
- urethane (meth) acrylates polyester (meth) acrylates, isocyanuric acid acrylates, and epoxy (meth) acrylates are also preferably used as the photopolymerizable polyfunctional monomer.
- esters of polyhydric alcohol and (meth) acrylic acid are preferable, and polyfunctional monomers having three or more (meth) acryloyl groups in one molecule are more preferable.
- (meth) acrylate represents “acrylate or methacrylate”, “acrylic acid or methacrylic acid”, and “acryloyl or methacryloyl”, respectively.
- resins having three or more (meth) acryloyl groups such as relatively low molecular weight polyester resins, polyether resins, acrylic resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyenes.
- examples thereof include oligomers or prepolymers such as resins and polyfunctional compounds such as polyhydric alcohols.
- polyfunctional acrylate compounds having three or more (meth) acryloyl groups paragraph No. 0096 of JP-A-2007-256844 can be referred to.
- urethane (meth) acrylates for example, alcohols, polyols, and / or hydroxyl group-containing compounds such as hydroxyl group-containing (meth) acrylates are reacted with isocyanates or, if necessary, obtained by these reactions. Mention may be made of urethane (meth) acrylate compounds obtained by esterifying a polyurethane compound with (meth) acrylic acid. As specific examples of specific compounds, the description in paragraph No. 0017 of JP-A No. 2007-256844 can be referred to.
- isocyanuric acid (meth) acrylates because curling can be further reduced.
- examples include isocyanuric acid diacrylates and isocyanuric acid triacrylates, and examples of specific compounds can be referred to paragraphs 0018 to 0021 of JP-A No. 2007-256844.
- an epoxy compound can be further used for reducing shrinkage due to curing.
- monomers having an epoxy group monomers having two or more epoxy groups in one molecule are used, and examples thereof include JP-A Nos. 2004-264563, 2004-264564, and 2005-37737. No. 2005-37738, No. 2005-140862, No. 2005-140862, No. 2005-140863, No. 2002-322430, and the like. It is also preferable to use a compound having both epoxy and acrylic functional groups such as glycidyl (meth) acrylate.
- the hard coat layer may contain a polymer compound.
- a polymer compound By adding a polymer compound, curing shrinkage can be reduced, and the viscosity of the coating solution relating to the dispersion stability (cohesiveness) of the resin particles can be adjusted more preferentially.
- the polarity of the solidified product in the drying process can be controlled to change the aggregation behavior of the resin particles, and drying unevenness in the drying process can be reduced, which is preferable.
- the polymer compound has already formed a polymer when added to the coating solution.
- a polymer compound examples include cellulose esters (for example, cellulose triacetate, cellulose diacetate, cellulose propionate, cellulose acetate propionate, cellulose acetate butyrate, cellulose nitrate), urethanes, and polyesters.
- (Meth) acrylic acid esters for example, methyl methacrylate / (meth) methyl acrylate copolymer, methyl methacrylate / (meth) ethyl acrylate copolymer, methyl methacrylate / butyl (meth) acrylate
- Polymers methyl methacrylate / styrene copolymers, methyl methacrylate / (meth) acrylic acid copolymers, polymethyl methacrylate, etc.
- resins such as polystyrene are preferably used.
- curable composition An example of the curable composition that can be used for forming the hard coat layer is a curable composition containing a (meth) acrylate compound.
- the curable composition preferably contains a photoradical polymerization initiator or a thermal radical polymerization initiator together with the (meth) acrylate compound, and further contains a filler, a coating aid, and other additives as desired. May be. Curing of the curable composition can be carried out by allowing the polymerization reaction to proceed by irradiation with ionizing radiation or heating in the presence of a photo radical polymerization initiator or a thermal radical polymerization initiator. Both ionizing radiation curing and thermal curing can be performed.
- the curable composition that can be used for forming the hard coat layer is a curable composition containing an epoxy compound.
- the curable composition preferably contains, together with the epoxy compound, a photoacid generator that generates cations by the action of light, and further contains a filler, a coating aid, and other additives as desired. May be. Curing of the curable composition can be performed by advancing a polymerization reaction by light irradiation in the presence of a photoacid generator.
- photoacid generators include ionic compounds such as triarylsulfonium salts and diaryliodonium salts, and nonionic compounds such as nitrobenzyl esters of sulfonic acids.
- Various known photoacid generators such as compounds described in “Organic Materials for Imaging” published by Bunshin Publishing Co., Ltd. (1997) can be used.
- an initiator uses a photoradical polymerization initiator or a thermal radical polymerization initiator, and a photocationic polymerization initiator together.
- a curable composition particularly suitable for the formation of the hard coat layer is a composition containing a (meth) acrylate compound as used in Examples described later.
- the curable composition is preferably prepared as a coating solution.
- the coating liquid can be prepared by dissolving and / or dispersing the above-described components in an organic solvent.
- the hard coat layer formed on the cellulose acylate film of the optical film of the present invention has high adhesion to the cellulose acylate film.
- the hard coat layer formed of the above-mentioned suitable curable composition on the cellulose acylate film containing the compound represented by the general formula (I) of the present invention has the curable composition of the present invention.
- a cellulose acylate film is formed with higher adhesion. Therefore, the optical film of the present invention having such a cellulose acylate film and a hard coat layer maintains the adhesion between the cellulose acylate film and the hard coat layer even by light irradiation or the like, and is excellent in light durability.
- the hard coat layer is preferably excellent in scratch resistance. Specifically, it is preferable to achieve 3H or higher when a pencil hardness test that is an index of scratch resistance is performed.
- the polarizing plate of the present invention has at least a polarizer and the optical film of the present invention.
- the optical film of the present invention is preferably used as a polarizing plate protective film because it is excellent in the effect of suppressing the coloring of the film by light.
- the polarizing plate of the present invention preferably has a polarizer and the optical film of the present invention on one or both surfaces of the polarizer.
- the polarizer include an iodine polarizer, a dye polarizer using a dichroic dye, and a polyene polarizer.
- the iodine polarizer and the dye polarizer are generally produced using a polyvinyl alcohol film.
- the preparation methods of a polarizing plate are not specifically limited, It can manufacture by a general method.
- the cellulose acylate film of the optical film of the present invention is treated with an alkali and bonded to both sides of a polarizer prepared by immersing and stretching a polyvinyl alcohol film in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution.
- alkali treatment easy adhesion processing as described in JP-A-6-94915 and JP-A-6-118232 may be performed.
- Examples of the adhesive used to bond the treated surface of the cellulose acylate film and the polarizer include polyvinyl alcohol adhesives such as polyvinyl alcohol and polyvinyl butyral, vinyl latexes such as butyl acrylate, and the like. .
- the optical film of the present invention is preferably bonded to the polarizer so that the transmission axis of the polarizer and the slow axis of the optical film of the present invention are substantially orthogonal, parallel or 45 °.
- the transmission axis of the polarizing plate and the slow axis of the optical film of the present invention are substantially orthogonal.
- being substantially orthogonal and parallel includes a range of errors allowed in the technical field to which the present invention belongs. For example, it means that it is within a range of less than ⁇ 10 ° from strict angles regarding parallel and orthogonal, and the error from the strict angle is preferably 5 ° or less, and more preferably 3 ° or less.
- Parallel to the transmission axis of the polarizer layer and the slow axis of the polarizing plate protective film means that the direction of the main refractive index nx of the polarizing plate protective film and the direction of the transmission axis of the polarizing plate intersect at an angle of ⁇ 10 °. Means that This angle is preferably within 5 °, more preferably within 3 °, even more preferably within 1 °, and most preferably within 0.5 °.
- the orthogonality of the transmission axis of the polarizer layer and the slow axis of the polarizing plate protective film means that the direction of the main refractive index nx of the polarizing plate protective film and the direction of the transmission axis of the polarizing plate are 90 ° ⁇ 10 °. Means crossing at an angle. This angle is preferably 90 ° ⁇ 5 °, more preferably 90 ° ⁇ 3 °, still more preferably 90 ° ⁇ 1 °, and most preferably 90 ° ⁇ 0.5 °. By setting it as the said range, the light omission under polarizing plate cross Nicol can be reduced more.
- the slow axis can be measured by various known methods, for example, using a birefringence meter (KOBRADH, manufactured by Oji Scientific Instruments).
- the polarizing plate of the present invention is produced not only in the form of a film piece cut into a size that can be incorporated into a liquid crystal display device as it is, but also in a long shape by continuous production and wound up into a roll.
- the polarizing plate of the aspect (for example, roll length 2500m or more or 3900m or more aspect) is also included.
- the width of the polarizing plate is preferably 1470 mm or more.
- the specific configuration of the polarizing plate of the present invention is not particularly limited, and a known configuration can be adopted. For example, the configuration shown in FIG. 6 of JP-A-2008-262161 can be adopted.
- the liquid crystal display device of the present invention has at least a liquid crystal cell and the polarizing plate of the present invention.
- the polarizing plate, the first polarizing plate and the second polarizing plate are included, at least one of them is the IPS, OCB or VA mode liquid crystal display device which is the polarizing plate of the present invention.
- the liquid crystal display device of the present invention preferably has a liquid crystal cell (liquid crystal layer) and a polarizing plate which is laminated on both sides of the liquid crystal cell and has an optical film on the surface opposite to the liquid crystal cell side. .
- the liquid crystal display device of the present invention has a first polarizing plate, a liquid crystal cell, and a second polarizing plate, and the optical film of the present invention is disposed on the opposite surface of the polarizing plate sandwiched between the polarizing plate and the liquid crystal cell. It is preferable to have.
- the liquid crystal display device having such a configuration is excellent in suppressing display unevenness and exhibits high display performance.
- the polarizing plate disposed on the viewing side has an optical film, particularly a cellulose acylate film, having a hard coat layer on the viewing-side optical film surface.
- the liquid crystal display device having such a configuration exhibits excellent scratch resistance and light durability in addition to high display performance excellent in suppressing display unevenness.
- FIG. 1 shows a liquid crystal display device having polarizing plates 21A and 21B in which optical films 31a and 31b of the present invention made of a cellulose acylate film are disposed on both surfaces of a polarizer 32.
- FIG. 2 shows a liquid crystal display device in which a polarizing plate 21B arranged on the viewing side includes an optical film 31a ′ having a hard coat layer 311b on the viewing side surface of the polarizer 32 via a cellulose acylate film 311a. It is shown in the figure.
- FIG. 1 and 2 show the configuration of an example of the liquid crystal display device of the present invention
- the specific configuration of the liquid crystal display device of the present invention is not particularly limited, and a known configuration can be adopted. Further, the configuration shown in FIG. 2 of JP-A-2008-262161 can also be preferably employed.
- the reaction solution was cooled to room temperature, 2 L of ethyl acetate, 1 L of 15% sodium chloride aqueous solution and 60 mL of concentrated hydrochloric acid were added, and the aqueous phase was removed. The remaining organic layer was washed three times with a 15% aqueous sodium chloride solution and dried over magnesium sulfate. Ethyl acetate was removed under reduced pressure to obtain 87.9 g of a crude product. Thereafter, hexane / ethyl acetate (200 ml / 200 ml) was added, an aqueous sodium hydrogen carbonate solution was added with stirring, and the organic layer was removed after liquid separation.
- Example 1 (Preparation of cellulose acylate) A cellulose acylate having a total acetyl substitution degree B of 2.87 was prepared. In this, sulfuric acid (7.8 parts by mass with respect to 100 parts by mass of cellulose) was added as a catalyst, a carboxylic acid serving as a raw material for the acyl substituent was added, and an acylation reaction was performed at 40 ° C. In addition, aging was performed at 40 ° C. after acylation. Further, the low molecular weight component of the cellulose acylate was removed by washing with acetone.
- Monopet (registered trademark) SB manufactured by Daiichi Kogyo Kagaku is benzoic acid ester of sucrose
- SAIB-100 manufactured by Eastman Chemical Co. is acetic acid and isobutyric acid ester of sucrose.
- composition of matting agent solution ⁇ Silica particles having an average particle size of 20 nm (AEROSIL R972, Nippon Aerosil Co., Ltd.) 2.0 parts by weight Methylene chloride (first solvent) 69.3 parts by weight Methanol (second solvent) 17.5 parts by weight n-butanol (third solvent) 0.9 parts by weight Cellulose reed Rate solution 101 0.9 parts by mass ⁇
- UV absorber solution 103 Composition of UV absorber solution 103 ⁇
- the following ultraviolet absorber (UV-1) 20.0 parts by mass Methylene chloride (first solvent) 61.0 parts by mass Methanol (second solvent) 15.4 parts by mass n-butanol (third solvent) 0.8 parts by mass Cellulose acylate solution 101 12.8 parts by mass ⁇
- 1.3 parts by mass of the matting agent solution 102 and 3.4 parts by mass of the UV absorber solution 103 are mixed using an in-line mixer after filtration, and 95.3 parts by mass of the cellulose acylate solution 101 is added. Then, they were mixed using an in-line mixer to prepare a surface layer solution.
- the base layer dope prepared as described above and the surface layer dope on both sides of the dope for the stainless steel casting support (support temperature ⁇ 9 ° C.) are uniformly formed from the casting port. It was cast into. Stripped in a state where the residual solvent amount in the dope of each layer is about 70% by mass, fixed both ends in the width direction of the film with a pin tenter, and 1.28 in the TD direction in a state where the residual solvent amount was 3-5% by mass. The film was dried while being stretched twice (28%). Thereafter, the film is further dried by conveying between rolls of a heat treatment apparatus, and a comparative optical film No. 101 was obtained. The obtained optical film No. The thickness of 101 was 60 ⁇ m and the width was 1480 mm.
- Optical film No. In 101, instead of the comparative compound (0-1) used in any of the cellulose acylate solutions for the surface layer and the base layer, the type and amount of addition of the compound in each cellulose acylate solution are as shown in Table 1 described later.
- the optical film no. In the same manner as in 101, the comparative optical film No. 102, 103, 106 and the optical film of the present invention. 104 and 105 were produced, respectively.
- these optical films are also referred to as polarizing plate protective films hereinafter.
- Haze is less than 0.1%
- Optical film No. 101 to 106 were used as polarizing plate protective films, and each of these polarizing plate protective films was immersed in a 2.3 mol / L sodium hydroxide aqueous solution at 55 ° C. for 3 minutes. It wash
- a polarizer was produced by adsorbing iodine to a stretched polyvinyl alcohol film. Each polarizing plate protective film subjected to saponification treatment was attached to one side of a polarizer using a polyvinyl alcohol-based adhesive.
- Commercially available cellulose triacetate film (Fujitac TD80UF, manufactured by Fuji Film Co., Ltd.) is also subjected to the same saponification treatment, and the side opposite to the side where the saponified polarizing plate protective film is pasted using a polyvinyl alcohol adhesive.
- a commercially available cellulose triacetate film subjected to saponification treatment was attached to the surface of the polarizer.
- the polarizer was arranged so that the transmission axis of the polarizer and the slow axis of the saponified polarizing plate protective film were parallel to each other. Further, the transmission axis of the polarizer and the slow axis of the commercially available cellulose triacetate film after saponification treatment were also arranged so as to be orthogonal to each other. In this way, the optical film No.
- Each polarizing plate corresponding to 101 to 106 was prepared.
- the polarizer durability test was performed as follows in a form in which a polarizing plate was bonded to glass via an adhesive. Two samples (about 5 cm ⁇ 5 cm) in which a polarizing plate was bonded onto glass so that the cellulose acylate film of the present invention was on the air interface side were prepared. In the measurement of the single plate orthogonal transmittance, the film of this sample was set with the cellulose acylate film side of the present invention facing the light source. Two samples were measured respectively, and the average value was taken as the orthogonal transmittance of the polarizing plate in the present invention.
- the orthogonal transmittance of the polarizing plate was measured in the range of 380 nm to 780 nm using an automatic polarizing film measuring device VAP-7070 manufactured by JASCO Corporation, and the measured value at 410 nm was adopted. Thereafter, each polarizing plate was stored over time under the following conditions, and then the orthogonal transmittance was measured by the same method.
- the change rate of the orthogonal transmittance before and after aging was determined by [(difference between orthogonal transmittance before aging and orthogonal transmittance after aging) / (orthogonal transmittance before aging)] ⁇ 100, and this was determined as the durability of the polarizer. Evaluation was made according to the following criteria.
- the relative humidity in an environment without humidity control was in the range of 0 to 20%.
- Evaluation Method-Aging Condition- It was stored for 250 hours in an environment of 80 ° C. and 90% relative humidity.
- Comparative Compounds 0-1 and 0-3 are the organic acids A and B described in paragraph No. 0133 of JP2011-118135A.
- Comparative compound 0-2 is a compound described in JP-A No. 2012-72348.
- the compounds represented by the general formula (I) of the present invention are all excellent in the volatility suppression effect from the film, and the optical film of the present invention (polarizing plate protective film) containing these is:
- the haze reduction effect of the film was also good.
- the polarizing plate protective film of the present invention containing the compound represented by the general formula (I) of the present invention has excellent polarizer durability over time, and can effectively suppress deterioration of the polarizer. there were. Since the volatility suppression effect of the compounds and the compatibility with cellulose acylate were good, it was possible to maintain the effective concentration of these compounds in the film, and it was thought that the durability of the polarizer was improved with time It is done.
- the polarizing plate protective film containing the comparative compounds (0-2) and (0-3) had a large haze value, and it was difficult to guarantee the durability of the polarizer over time. It is considered that these performances were deteriorated because the volatility suppressing effect of the comparative compound (0-2) and the compatibility with the cellulose acylate were insufficient.
- the polarizing plate protective film containing the comparative compound (0-1) showed compatibility with cellulose acylate, but the effect of suppressing volatility was insufficient.
- the comparative polarizing plate protective film film No.
- Example 2 (Preparation of optical film with hard coat layer) The hard coat layer solution of the following cured composition was applied to the surface of each optical film prepared in Example 1 before preparation of the polarizing plate, and cured by irradiating with ultraviolet rays to form a hard coat layer having a thickness of 6 ⁇ m. A layered optical film was prepared. In Table 2 below, a single-layer optical film No. And corresponding optical film No. 1 with a hard coat layer. Common film No. It is indicated with
- Curing composition of hard coat layer solution ⁇ Monomer Pentaerythritol triacrylate / Pentaerythritol tetraacrylate (mixing mass ratio 3/2) 53.5 parts by weight UV polymerization initiator Irgacure TM 907 (BASF Co., Ltd.) 1.5 parts by mass Ethyl acetate 45 parts by mass ⁇ -
- Optical film with hard coat layer of the present invention No. 104 and 105 are excellent in adhesiveness as compared with an optical film using a comparative compound. This is presumably because the absorption wavelength in the film is shortened and the degradation of cellulose acetate due to light irradiation is suppressed.
- Example 3 Optical film: Preparation and evaluation of cellulose acylate film
- the following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acetate solution.
- the cellulose acetate solution was cast using a band casting machine, dried at 100 ° C. to a residual solvent content of 40%, and then the film was peeled off. The peeled film was further dried at an ambient temperature of 140 ° C. for 20 minutes.
- the film thickness of the obtained optical film was 25 ⁇ m.
- cellulose acylate film No. 204 except that the types and addition amounts of the exemplified compounds to be added and the types and addition amounts of the plasticizer were changed as shown in Table 3 below.
- the comparative cellulose acylate film No. 201 and the cellulose acylate film no. 202, 203, 205 to 211 were prepared.
- the volatility of the additive and the haze of the cellulose acylate film were evaluated in the same manner as in Example 1.
- a polarizing plate was prepared in the same manner as in Example 1 using 201, and the durability of the polarizer was evaluated.
- the durability of the polarizer was evaluated under the following aging conditions, and the obtained results were evaluated according to the following evaluation criteria.
- Evaluation criteria for polarizer durability A: Change rate of orthogonal transmittance before and after aging is less than 0.3% B: Change rate of orthogonal transmittance before and after aging is 0.3% or more and less than 0.5% C: Before and after time The change rate of the orthogonal transmittance of 0.5% to less than 0.7% D: The change rate of the orthogonal transmittance before and after aging is 0.7% or more
- Polarizing plates using 202 to 211 are comparative cellulose acylate film Nos. With respect to the polarizing plate using 201, the change rate of the orthogonal transmittance before and after aging was reduced, and the deterioration of the polarization performance was suppressed.
- Example 4 Cellulose acylate film No. 1 in Example 3 202, 204, 211
- the following plasticizer P was used in the same manner as in Example 3 except that the following blending amounts were used.
- 302, 304, and 311 were prepared, and each polarizing plate was prepared and evaluated in the same manner as in Example 1.
- Plasticizer P Phthalic acid / ethanediol polycondensate terminal is acetate group and number average molecular weight is 800 10.0 parts by mass
- the polarizing plates using 302, 304, and 311 were the cellulose acylate film No. 1 of the present invention in Example 3. Similar to the polarizing plates produced using 201, 204, and 211, the rate of change of the orthogonal transmittance before and after aging was reduced, and deterioration of the polarization performance was suppressed. Moreover, the haze of the film was not seen and it was favorable.
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Abstract
Description
しかも、液晶表示装置は益々多様な用途で過酷な使用条件でも耐えることに対する要求が高まり、年々、従来よりも高いレベルの耐久性が求められるようになってきている。
また、近年、TV用途を中心に液晶表示装置の大型化・薄型化が進んでおり、これに伴って構成部材である光学フィルムも薄型化が必要とされている。従来より、光学フィルムは加工性の観点からも適切な硬度、良好な裁断性が重要視されてきたが、薄型化した光学フィルムにはさらにその向上が求められるようになった。
例えば、光学フィルムのレターデーションが環境湿度による変動を抑制するために、pKaが2~7の脂肪族もしくは芳香族のモノカルボン酸や有機リン酸(特許文献1参照)を、また、溶液製膜による樹脂フィルム製造時の支持体からの得られたフィルムの剥離の改良と偏光子の耐久性改良のために、カルボキシ基を2個有するイミノジ酢酸型の有機カルボン酸化合物(pKa5.5以下)を光学フィルムに含有させることが提案(特許文献2参照)されている。
しかも、これらの特許文献に記載の化合物は、セルロースアシレートとの相溶性が必ずしも十分でなく、長期の過酷な環境条件では、セルロースアシレートフィルムから揮散して、実効濃度が低下し、またヘイズが発生したりした。
従って、本発明は、高温高湿下での長期で過酷な条件下においてもフィルム中からの化合物の揮散性を抑制し、かつ偏光子耐久性が改善可能であり、同時に、セルロースアシレートを含む光学フィルムにおけるヘイズの発生を抑制した光学フィルム、それを使用した偏光板および液晶表示装置を提供することを課題とする。
このようにフィルムから化合物が揮散する現象は、フィルム中でこれらの化合物と共存するセルロースアシレートとの相溶性が必ずしも十分でないこと、または、加えられた化合物とセルロースアシレートとの相互作用が弱いことに基づくものと考えられた。
このために、pKaを高くした有機酸の添加によって初期の偏光子耐久性を改善し、セルロースアシレートとの相溶性を向上させ、本発明に至った。
<1>セルロースアシレートおよび少なくとも1種の下記一般式(I)で表される化合物を含有する光学フィルム。
<2>Lが、単結合、アルキレン基またはアルカントリイル基である<1>に記載の光学フィルム。
<3>Lが、アルキレン基である<1>または<2>に記載の光学フィルム。
<4>一般式(I)で表される化合物が、下記一般式(II)で表される化合物である<1>~<3>のいずれか1つに記載の光学フィルム。
<5>R2が、アリール基またはシクロアルキル基が置換してもよいアルキル基である<1>~<4>のいずれか1つに記載の光学フィルム。
<6>R2が、下記一般式(1)または(2)である<1>~<5>のいずれか1つに記載の光学フィルム。
<10>可塑剤の少なくとも1種を含有する<1>~<9>のいずれか1つに記載の光学フィルム。
<11>光学フィルムが、少なくとも2層からなり、セルロースアシレートおよび少なくとも1種の一般式(I)で表される化合物を含む層に、さらにハードコート層を有する<1>~<10>のいずれか1つに記載の光学フィルム。
<12>偏光子と、この偏光子の少なくとも一方の面に<1>~<11>のいずれか1つに記載の光学フィルムを有する偏光板。
<13> <12>に記載の偏光板と液晶セルを少なくとも有する液晶表示装置。
本発明の上記及び他の特徴及び利点は、適宜添付の図面を参照して、下記の記載からより明らかになるであろう。
本発明の光学フィルムは、セルロースアシレートおよび少なくとも1種の一般式(I)で表される化合物を含有する少なくとも1層のセルロースアシレートフィルムからなる。また、光学フィルムは、複数の層で構成されていてもよいが、一般式(I)で表される化合物はいずれの層に含まれていてもよく、全ての層に含まれていてもよい。
ハードコート層以外には、例えば、防眩層、クリアハードコート層、反射防止層、帯電防止層、防汚層等が挙げられる。これらの層は、ハードコート層上に設けるのが本発明においては好ましい態様である。
本発明において、セルロースアシレートフィルムは上記のように、樹脂構成成分に占めるセルロースアシレートの割合が50質量%以上のフィルムからなるもので、本発明における狭義の光学フィルムである。
セルロースアシレートフィルムは、単層であっても、2層以上の積層体であってもよい。ただし、ここでの層は上述したような機能層を含まず、樹脂成分全体に対してセルロースアシレートを50質量%以上含む層を意味する。セルロースアシレートフィルムが2層以上の積層体である場合は、2層構造または3層構造であることがより好ましく、3層構造であることが好ましい。3層構造の場合は、1層のコア層(すなわち、最も厚い層であり、以下、基層とも言う)と、コア層を挟むスキン層Aおよびスキン層Bとを有することが好ましい。すなわち、本発明のセルロースアシレートフィルムはスキン層B/コア層/スキン層Aの3層構造であることが好ましい。このような積層体は後述する共流延など、各種公知の流延法によって製造することができる。スキン層Bは、セルロースアシレートフィルムが溶液製膜で製造される際に、後述する金属支持体と接する層であり、スキン層Aは金属支持体とは逆側の空気界面の層である。なお、スキン層Aとスキン層Bを総称してスキン層(または表層)とも言う。
R1におけるアルケニル基は、炭素数が2~30が好ましく、2~24がより好ましく、2~20がさらに好ましい。
R1におけるアリール基は、炭素数が6~30が好ましく、6~24がより好ましく、6~20がさらに好ましい。
R1におけるヘテロ環基は、5または6員環が好ましく、この環はベンゼン環が縮環していてもよい。またヘテロ環を構成するヘテロ原子は、窒素原子、酸素原子、硫黄原子から選択された原子が好ましく、芳香環であっても芳香環でない不飽和環であっても、飽和環であっても構わない。ヘテロ環の炭素数は、0~30が好ましく、1~24がより好ましく、2~20がさらに好ましい。
R1におけるアルコキシカルボニル基の炭素数は2~30が好ましく、2~24がより好ましく、2~20がさらに好ましい。
R1におけるカルバモイル基は、カルバモイル基、N-アルキルカルバモイル基、N,N-ジアルキルカルバモイル基、N-アリールカルバモイル基、N,N-ジアリールカルバモイル基、N-アルキル-N-アリールカルバモイル基のいずれであってもよく、炭素数は1~30が好ましく、2~24がより好ましく、2~20がさらに好ましい。
R1におけるアルキルスルホニル基は、炭素数が1~30が好ましく、1~24がより好ましく、1~20がさらに好ましい。
R1におけるアリールスルホニル基は、炭素数が6~30が好ましく、6~24がより好ましく、6~20がさらに好ましい。
このような置換基としては、特に制限はなく、アルキル基(好ましくは炭素数1~10で、例えばメチル、エチル、イソプロピル、t-ブチル、ペンチル、ヘプチル、1-エチルペンチル、ベンジル、2-エトキシエチル、1-カルボキシメチル等)、アルケニル基(好ましくは炭素数2~20で、例えば、ビニル、アリル、オレイル等)、アルキニル基(好ましくは炭素数2~20で、例えば、エチニル、ブタジイニル、フェニルエチニル等)、シクロアルキル基(好ましくは炭素数3~20で、例えば、シクロプロピル、シクロペンチル、シクロヘキシル、4-メチルシクロヘキシル等)、アリール基(好ましくは炭素数6~26で、例えば、フェニル、1-ナフチル、4-メトキシフェニル、2-クロロフェニル、3-メチルフェニル等)、ヘテロ環基(好ましくは炭素数0~20のヘテロ環基で、環構成ヘテロ原子が酸素原子、窒素原子、硫黄原子が好ましく、5または6員環でベンゼン環やヘテロ環で縮環していてもよく、この環が飽和環、不飽和環、芳香環であってもよく、例えば、2-ピリジル、4-ピリジル、2-イミダゾリル、2-ベンゾイミダゾリル、2-チアゾリル、2-オキサゾリル等)、アルコキシ基(好ましくは炭素数1~20で、例えば、メトキシ、エトキシ、イソプロピルオキシ、ベンジルオキシ等)、アリールオキシ基(好ましくは炭素数6~26で、例えば、フェノキシ、1-ナフチルオキシ、3-メチルフェノキシ、4-メトキシフェノキシ等)、
なお、これらの置換基は、R1、R3、R5、Ra各基が有してもよい置換基のみでなく、Lを含め、本明細書に記載の他の化合物における置換基にも適用される。
R2、Raにおけるアルキル基は、R1におけるアルキル基と好ましい範囲は同じであり、R2におけるアリール基は、R1におけるアリール基と好ましい範囲は同じである。
4価の基としては、アルカンテトライル基、アレーンテトライル基が挙げられる。
Lにおける2価以上の連結基は、置換基を有していてもよい。
ここで、アルキレン基は、炭素数1~6が好ましく、1~4が好ましく、1または2がさらに好ましく、1が中でも好ましい。具体的にはエチレン基、プロピレン基、トリメチレン基、テトラメチレン基が挙げられる。
Lがアルキレン基の場合、R1はアシル基、アルコキシカルボニル基、カルバモイル基、アルキルスルホニル基、アリールスルホニル基が好ましく、アルコキシカルボニル基、カルバモイル基がより好ましい。
Lが単結合の場合、R1はアルキル基、アルケニル基、アリール基、ヘテロ環基、アシル基、アルコキシカルボニル基、カルバモイル基、アルキルスルホニル基、アリールスルホニル基が好ましく、アシル基、アルコキシカルボニル基、カルバモイル基、アルキルスルホニル基、アリールスルホニル基がより好ましい。
Cy、Cy1およびCy2はフェニル基またはシクロヘキシル基が好ましく、フェニル基がさらに好ましい。
uは1、2または3を表し、好ましい範囲はsおよびtと同じである。
R3はR2と同義であり、好ましい範囲も同じである。YはXと同義であり、好ましい範囲も同じである。
また、一般式(I)で表される化合物の25℃における、THF/H20=6/4の体積比の混合溶媒中でのpKaが、5.5を超えるものが好ましく、5.5を超え7.0未満、好ましくは6.5未満が好ましい。
カルボキシ基とアミノ基の1分子中における存在比率を調整することでこのような値とすることが可能となる。pKaを調製した一般式(I)で表される化合物を光学フィルムに組み込むことで、偏光子耐久性改良効果、ヘイズ抑制効果がより優れたものとなる。さらに、セルロースアシレートフィルムの光照射下での着色抑制や、ハードコート層などを設けた場合の密着性の改善効果も得ることができる。詳細な機構は定かではないが、本発明者らは、経時で、カルボキシ基が生じるカルボキシ基のプレカーサーを組み込むことが起因していると考えている。
このような含有量とすることで、本発明の効果である偏光子耐久性およびヘイズ上昇の抑制効果が十分に発現することとなる。
また、光学フィルム中に一般式(I)で表される化合物を2種類以上含有させる場合も、その合計量が、上記の範囲内であることが好ましい。
本発明において、セルロースアシレートフィルムの主成分となるセルロースアシレートは、1種を用いてもよいし、2種以上を用いてもよい。例えば、セルロースアシレートは、アシル置換基としてアセチル基のみからなるセルロースアセテートであっても、複数の異なったアシル置換基を有するセルロースアシレートを用いてもよく、異なったセルロースアシレートの混合物であってもよい。
本発明では、特に、セルロースアシレートのアシル基はアセチル基1種であるものが、一般式(I)で表される化合物による偏光子耐久性の改善効果に優れる点で、好ましい。
セルロースを構成するβ-1,4結合しているグルコース単位は、2位、3位および6位に遊離のヒドロキシ基を有している。セルロースアシレートは、これらのヒドロキシ基の一部または全部をアシル基によりアシル化した重合体(ポリマー)である。
アシル置換度は、2位、3位および6位に位置するセルロースのヒドロキシ基のアシル化の度合いを示すものであり、全てのグルコース単位の2位、3位および6位のヒドロキシ基がいずれもアシル化された場合、総アシル置換度は3である。例えば、全てのグルコース単位で、6位のみが全てアシル化された場合、総アシル置換度は1である。同様に、全グルコースの全ヒドロキシ基において、各々のグルコース単位で、6位か、2位のいずれか一方の全てがアシル化された場合も、総アシル置換度は1である。
すなわち、グルコース分子中の全ヒドロキシ基が全てアシル化された場合を3として、アシル化の度合いを示すものである。
アシル置換度の測定方法の詳細については、手塚他,Carbohydrate.Res.,273,83-91(1995)に記載の方法やASTM-D817-96に規定の方法に準じて測定することができる。
なお、本発明の一般式(I)で表される化合物は、総アセチル置換度Bが2.50を超えたセルロースアシレートに対して、特に効果が発現される。
本発明の光学フィルム中、特にセルロースアシレートフィルム中には、レターデーション調整剤(レターデーション発現剤およびレターデーション低減剤)や、可塑剤として、重縮合エステル化合物(ポリマー)、多価アルコールの多価エステル、フタル酸エステル、リン酸エステルなど、さらには、紫外線吸収剤、酸化防止剤、マット剤などの添加剤を加えることもできる。
なお、本明細書では、化合物群を標記するのに、例えば、リン酸エステル系化合物のように、「系」を組み込んで記載することがあるが、これは、上記の場合、リン酸エステル化合物と同じ意味である。
本発明ではレターデーション低減剤として、リン酸エステル系化合物や、セルロースアシレートフィルムの添加剤として公知の非リン酸エステル系の化合物以外の化合物を広く採用することができる。
これらを添加する時期は、セルロースアシレート溶液(ドープ)作製工程のどの工程でもよい。また、ドープ調製工程の最後の調製工程に、添加剤を添加して調製する工程を新たに加えてもよい。
各素材の添加量は機能が発現する限りにおいて特に限定されない。
本発明の光学フィルムは、レターデーション値を発現するために、少なくとも1種のレターデーション発現剤を含有してもよい。
レターデーション発現剤としては、特に制限はないが、棒状または円盤状化合物からなるものや、上記非リン酸エステル系の化合物のうちレターデーション発現性を示す化合物を挙げることができる。棒状または円盤状化合物では、少なくとも二つの芳香環を有する化合物がレターデーション発現剤として好ましい。
レターデーション発現剤は、250~400nmの波長領域に最大吸収を有することが好ましく、可視領域に実質的に吸収を有していないことが好ましい。
レターデーション発現剤の詳細は公開技報2001-1745の49頁に記載されている。
円盤状化合物からなるレターデーション発現剤の添加量は、セルロースアシレートを含むポリマー成分100質量部に対して0.1~30質量部が好ましく、0.5~20質量部がさらに好ましい。
光学フィルム、特にセルロースアシレートフィルムでは、可塑剤をセルロースアシレートに含有させると、セルロースアシレートフィルムの含水率や透湿度が低下し、セルロースアシレートフィルム中の水分によるセルロースアシレートの加水分解反応が抑制される。さらに、可塑剤は、高温高湿条件下におけるセルロースアシレートフィルム中から偏光子層への添加剤の拡散を抑制し、偏光子性能の劣化を改良することができる。
以下に本発明に用いられる可塑剤について説明する。
重縮合エステル系可塑剤は、2価のカルボン酸化合物とジオール化合物を重縮合して得られる。
重縮合エステル系可塑剤は、下記一般式(a)で表される少なくとも1種のジカルボン酸および下記一般式(b)で表される少なくとも1種のジオールを重縮合して得られるものが好ましい。
一方、ジオール化合物も、上記一般式(b)で表される脂肪族化合物以外にも、芳香族もしくはヘテロ環の化合物が挙げられる。
また、数平均分子量が2000以下であればセルロースアシレートとの相溶性が高くなり、製膜時および加熱延伸時のブリードアウトの抑制に優れる。
炭素数の平均が5.5以上であれば耐久性に優れた偏光板を得ることができる。炭素数の平均が10以下であればセルロースアシレートへの相溶性に優れ、セルロースアシレートフィルムの製膜過程でブリードアウトの抑制に優れる。
ジオール化合物と、脂肪族ジカルボン酸を含むジカルボン酸とから得られた重縮合エステルには、脂肪族ジカルボン酸残基が含まれる。
重縮合エステル系可塑剤を合成する脂肪族ジカルボン酸は、例えば、シュウ酸、マロン酸、コハク酸、マレイン酸、フマル酸、グルタル酸、アジピン酸、ピメリン酸、スベリン酸、アゼライン酸、セバシン酸、ドデカンジカルボン酸、1,2-シクロヘキサンジカルボン酸または1,4-シクロヘキサンジカルボン酸等が挙げられる。
重縮合エステル系可塑剤を合成するジオールとしては、芳香族ジオールおよび脂肪族ジオールが挙げられ、本発明においては、少なくとも脂肪族ジオールを用いて合成されることが好ましい。
脂肪族ジオール残基の平均炭素数が7.0より小さいとセルロースアシレートとの相溶性が改善され、ブリードアウト、化合物の加熱減量の増大、およびセルロースアシレートウェブ乾燥時の工程汚染が原因と考えられる面状故障の発生の抑制に優れる。また、脂肪族ジオール残基の平均炭素数が2.5以上であれば合成が容易である。
重縮合エステル系可塑剤は、特開2012-234159号公報の段落番号0062~0064に記載されているJ-1~J-38が好ましい。
本発明に用いられる多価アルコールエステル系可塑剤は、アルコール部が2個以上のヒドロキシ基を有する多価アルコールから導かれるエステルであり、アルコール部のアルコールとしては、ヒドロキシ基以外の部分が、エーテル結合を介して分断されてもよい飽和炭化水素にヒドロキシ基が2個以上置換したアルコールが好ましい。
多価アルコールエステル系可塑剤の原料の多価アルコールは下記一般式(c)で表される。
Rα-(OH)m
このような多価アルコールとしては、糖アルコールやグリコール類が挙げられる。
具体的には、トリエチレングリコール、テトラエチレングリコール、ジプロピレングリコール、トリプロピレングリコール、ソルビトール、トリメチロールプロパン、キシリトールが好ましい。
炭水化物誘導体系可塑剤としては、単糖あるいは2~10個の単糖単位を含む炭水化物の誘導体、中でもアシル化されたものが好ましい。
炭水化物誘導体系可塑剤はピラノース構造あるいはフラノース構造を有することが好ましい。
なお、本発明では、可塑剤は、特開2012-234159号公報の段落番号0026~0068に記載の内容が好ましく適用され、これらの段落番号に記載の内容は、本明細書の一部に、好ましく取り込まれる。
本発明の光学フィルムは、酸化防止剤を含むことが好ましい。この酸化防止剤はセルロースアシレート溶液に添加されることができる。本発明において、公知の酸化防止剤、例えば、2,6-ジ-tert-ブチル-4-メチルフェノール、4,4'-チオビス-(6-tert-ブチル-3-メチルフェノール)、1,1'-ビス(4-ヒドロキシフェニル)シクロヘキサン、2,2'-メチレンビス(4-エチル-6-tert-ブチルフェノール)、2,5-ジ-tert-ブチルヒドロキノン、ペンタエリスリチル-テトラキス[3-(3,5-ジ-tert-ブチル-4-ヒドロキシフェニル)プロピオネート]などのフェノール系あるいはヒドロキノン系酸化防止剤を添加することができる。さらに、トリス(4-メトキシ-3,5-ジフェニル)ホスファイト、トリス(ノニルフェニル)ホスファイト、トリス(2,4-ジ-tert-ブチルフェニル)ホスファイト、ビス(2,6-ジ-tert-ブチル-4-メチルフェニル)ペンタエリストールジホスファイト、ビス(2,4-ジ-tert-ブチルフェニル)ペンタエリスリトールジホスファイトなどのリン系酸化防止剤を用いることが好ましい。
酸化防止剤の添加量は、セルロースアシレート100質量部に対して、0.05~5.0質量部が好ましい。
本発明の光学フィルムは、偏光板または液晶等の劣化防止の観点から、紫外線吸収剤を含んでいてもよい。この紫外線吸収剤はセルロースアシレート溶液に添加されることができる。本発明において、紫外線吸収剤としては、波長370nm以下の紫外線の吸収能に優れ、かつ良好な液晶表示性の観点から、波長400nm以上の可視光の吸収が少ないものが好ましく用いられる。本発明に好ましく用いられる紫外線吸収剤は、例えばヒンダードフェノール系化合物、ヒドロキシベンゾフェノン系化合物、ベンゾトリアゾール系化合物、サリチル酸エステル系化合物、ベンゾフェノン系化合物、シアノアクリレート系化合物、ニッケル錯塩系化合物などが挙げられる。
これらの紫外線吸収剤の添加量は、セルロースアシレートフィルムの全固形分中に質量割合で1~1.0%が好ましく、10~1000ppmがさらに好ましい。
本発明の光学フィルムは、フィルムのすべり性、および安定製造の観点からマット剤を加えてもよい。マット剤は、無機化合物のマット剤であっても、有機化合物のマット剤であってもよい。
無機化合物のマット剤は、ケイ素を含む無機化合物(例えば、二酸化ケイ素、焼成ケイ酸カルシウム、水和ケイ酸カルシウム、ケイ酸アルミニウム、ケイ酸マグネシウムなど)、酸化チタン、酸化亜鉛、酸化アルミニウム、酸化バリウム、酸化ジルコニウム、酸化ストロンチウム、酸化アンチモン、酸化スズ、酸化スズ・アンチモン、炭酸カルシウム、タルク、クレイ、焼成カオリンおよびリン酸カルシウム等が好ましく、ケイ素を含む無機化合物や酸化ジルコニウムがより好ましい。このうち、セルロースアシレートフィルムの濁度を低減できることから、二酸化ケイ素が特に好ましい。
有機化合物のマット剤は、例えば、シリコーン樹脂、弗素樹脂およびアクリル樹脂等のポリマーが好ましく、中でも、シリコーン樹脂が好ましい。シリコーン樹脂の中でも、特に三次元の網状構造を有するものが好ましく、例えば、トスパール103、トスパール105、トスパール108、トスパール120、トスパール145、トスパール3120およびトスパール240(以上東芝シリコーン(株)製)等の商品名を有する市販品が使用できる。
さらには、ドープを流延する直前に添加混合(いわゆる直前添加方法)してもよい。直前添加方法での混合は、スクリュー式混練をオンラインで設置して行われる。具体的には、インラインミキサーのような静的混合機が好ましく、また、インラインミキサーとしては、例えば、スタチックミキサーSWJ(東レ静止型管内混合器Hi-Mixer)(東レエンジニアリング製)のようなものが好ましい。
特開2003-014933号公報には、添加剤ブリードアウトが少なく、かつ層間の剥離現象もなく、しかも滑り性が良好で、透明性に優れた位相差フィルムを作製することを目的とし、添加剤の添加方法が記載されている。これによれば、添加剤を溶解釜中に添加してもよいし、溶解釜~共流延ダイまでの間で、添加剤や添加剤を溶解または分散した溶液を、送液中のドープに添加してもよいが、後者の場合は混合性を高めるため、スタチックミキサー等の混合手段を設けることが好ましいことが記載されている。
〔弾性率(引張り弾性率)〕
セルロースアシレートフィルムは実用上十分な弾性率(引張り弾性率)を示す。弾性率の範囲は特に限定されないが、製造適性およびハンドリング性という観点から1.0~7.0GPaが好ましく、2.0~6.5GPaがより好ましい。本発明の一般式(I)で表される化合物は、セルロースアシレートフィルム中に添加されることにより、セルロースアシレートフィルムを疎水化することで弾性率を向上させる作用があり、その点も本発明における利点である。
セルロースアシレートフィルムの光弾性係数の絶対値は、好ましくは8.0×10-12m2/N以下、より好ましくは6×10-12m2/N以下、さらに好ましくは5×10-12m2/N以下である。セルロースアシレートフィルムの光弾性係数を小さくすることにより、セルロースアシレートフィルムを含む本発明の光学フィルムを偏光板保護フィルムとして液晶表示装置に組み込んだ際に、高温高湿下におけるムラ発生を抑制できる。光弾性係数は、特に断らない限り、以下の方法により測定し算出するものとする。
光弾性率の下限値は特に限定されないが、0.1×10-12m2/N以上が実際的である。
セルロースアシレートフィルムの含水率は一定温湿度における平衡含水率を測定することにより評価することができる。平衡含水率は上記の一定温湿度に24時間放置した後に、平衡に達した試料の水分量をカールフィッシャー法で測定し、水分量(g)を試料質量(g)で除して算出したものである。
セルロースアシレートフィルムの25℃、相対湿度80%における含水率は5質量%以下であることが好ましく、4質量%以下がさらに好ましく、3質量%未満がさらに好ましい。セルロースアシレートフィルムの含水率を小さくすることにより、セルロースアシレートフィルムを含む本発明の光学フィルムを偏光板保護フィルムとして液晶表示装置に組み込んだ際に、高温高湿下における液晶表示装置の表示ムラの発生を抑制することができる。含水率の下限値は特に限定されないが、0.1質量%以上であることが実際的である。
セルロースアシレートフィルムの透湿度は、JIS Z0208の透湿度試験(カップ法)に準じ、温度40℃、相対湿度90%RHの雰囲気中、試料を24時間に通過する水蒸気の質量を測定し、試料面積1m2あたりの24時間に通過する水蒸気の質量に換算することにより評価することができる。
セルロースアシレートフィルムの透湿度は、500~2000g/m2・dayが好ましく、900~1300g/m2・dayがより好ましく、1000~1200g/m2・dayが特に好ましい。
セルロースアシレートフィルムは、ヘイズが1%以下が好ましく、0.7%以下がより好ましく、0.5%以下が特に好ましい。ヘイズを上記上限値以下とすることにより、セルロースアシレートフィルムの透明性がより高くなり、光学フィルムとしてより用いやすくなるという利点がある。ヘイズは、特に断らない限り、下記方法により測定し算出するものとする。ヘイズの下限値は特に限定されないが、0.001%以上が実際的である。
セルロースアシレートフィルム40mm×80mmを、25℃、相対湿度60%の環境下で、ヘイズメーター(HGM-2DP、スガ試験機)を用いて、JIS K7136に従って測定する。
セルロースアシレートフィルムの平均膜厚は、10~100μmが好ましく、15~80μmがより好ましく、15~70μmがさらに好ましい。15μm以上とすることにより、ウェブ状のフィルムを作製する際のハンドリング性が向上し、好ましい。また、70μm以下とすることにより、湿度変化に対応しやすく、光学特性を維持しやすい。
セルロースアシレートフィルムが3層以上の積層構造を有する場合、コア層の膜厚は3~70μmが好ましく、5~60μmがより好ましく、スキン層Aおよびスキン層Bの膜厚は、ともに0.5~20μmがより好ましく、0.5~10μmが特に好ましく、0.5~3μmが最も好ましい。
セルロースアシレートフィルムの幅は、700~3000mmが好ましく、1000~2800mmがより好ましく、1300~2500mmが特に好ましい。
本発明のセルロースアシレートフィルムの製造方法は、特に限定されるものではないが、溶融製膜法または溶液製膜法により製造することが好ましい。溶液製膜法(ソルベントキャスト法)による製造がより好ましい。ソルベントキャスト法を利用したセルロースアシレートフィルムの製造例については、米国特許第2,336,310号、同第2,367,603号、同第2,492,078号、同第2,492,977号、同第2,492,978号、同第2,607,704号、同第2,739,069号および同第2,739,070号の各明細書、英国特許第640731号および同第736892号の各明細書、並びに特公昭45-4554号、同49-5614号、特開昭60-176834号、同60-203430号および同62-115035号等の各公報を参考にすることができる。また、セルロースアシレートフィルムは、延伸処理を施されていてもよい。延伸処理の方法および条件については、例えば、特開昭62-115035号、特開平4-152125号、同4-284211号、同4-298310号、同11-48271号等の各公報を参考にすることができる。
溶液の流延方法としては、調製されたドープを加圧ダイから金属支持体上に均一に押し出す方法、一旦金属支持体上に流延されたドープをブレードで膜厚を調節するドクターブレードによる方法、逆回転するロールで調節するリバースロールコーターによる方法等があり、本発明では、加圧ダイによる方法が好ましい。加圧ダイにはコートハンガータイプやTダイタイプ等があり、いずれも好ましく用いることができる。また、ここで挙げた方法以外にも、従来知られているセルロースアシレート溶液を流延製膜する種々の方法で実施することができ、用いる溶媒の沸点等の違いを考慮して各条件を設定することにより、それぞれの公報に記載の内容と同様の効果が得られる。
セルロースアシレートフィルムの形成においては共流延法、逐次流延法、塗布法などの積層流延法を用いることが好ましく、同時共流延法を用いることが、安定製造および生産コスト低減の観点から特に好ましい。
共流延法および逐次流延法により製造する場合には、先ず、各層用のセルロースアセテート溶液(ドープ)を調製する。共流延法(重層同時流延)は、流延用支持体(バンドまたはドラム)の上に、各層(3層あるいはそれ以上でもよい)各々の流延用ドープを別のスリットなどから同時に押出す流延用ギーサからドープを押出して、各層同時に流延し、適当な時期に支持体から剥ぎ取って、乾燥しフィルムを成形する流延法である。
また、上記金属支持体の材質については特に制限はないが、SUS製(例えば、SUS316)が好ましい。
セルロースアシレートフィルムの製造方法は、上記ドープ膜を金属支持体から剥ぎ取る工程を含むことが好ましい。セルロースアシレートフィルムの製造方法における剥離の方法については特に制限はなく、公知の方法でも剥離性を改善することができる。
セルロースアシレートフィルムの製造方法では、製膜された延伸する工程を含むことが好ましい。セルロースアシレートフィルムの延伸方向はセルロースアシレートフィルム搬送方向(MD方向)と搬送方向に直交する方向(TD方向)のいずれでも好ましいが、セルロースアシレートフィルム搬送方向に直交する方向(TD方向)であることが、後に続く、セルロースアシレートフィルムを用いた偏光板加工プロセスの観点から特に好ましい。
セルロースアシレートフィルムの製造方法では、セルロースアシレートフィルムを乾燥する工程と、乾燥後のセルロースアシレートフィルムをガラス転移温度(Tg)-10℃以上の温度で延伸する工程とを含むことが、レターデーション発現性の観点から好ましい。
本発明の光学フィルムにおいて、セルロースアシレートフィルム上に所望により設けられるハードコート層は、本発明の光学フィルムに硬度や耐傷性を付与するための層である。例えば、塗布組成物をセルロースアシレートフィルム上に塗布し、硬化させることによって、本発明の一般式(I)で表される化合物と相俟ってセルロースアシレートフィルムと密着性の高いハードコート層を形成することができる。ハードコート層にフィラーや添加剤を加えることで、機械的、電気的、光学的な物理的な性能や撥水・撥油性などの化学的な性能をハードコート層自体に付与することもできる。ハードコート層の厚みは0.1~6μmが好ましく、3~6μmがさらに好ましい。このような範囲の薄いハードコート層を有することで、脆性やカール抑制などの物性改善、軽量化および製造コスト低減がなされたハードコート層を含む光学フィルムになる。
利用可能なマトリックス形成バインダー用モノマーまたはオリゴマーの例には、電離放射線硬化性の多官能モノマーおよび多官能オリゴマーが含まれる。多官能モノマーや多官能オリゴマーは架橋反応、または、重合反応可能なモノマーであるのが好ましい。電離放射線硬化性の多官能モノマーや多官能オリゴマーの官能基としては、光、電子線、放射線で重合するものが好ましく、中でも光重合性官能基が好ましい。
トリエチレングリコールジ(メタ)アクリレート、ジプロピレングリコールジ(メタ)アクリレート、ポリエチレングリコールジ(メタ)アクリレート、ポリプロピレングリコールジ(メタ)アクリレート等のポリオキシアルキレングリコールの(メタ)アクリル酸ジエステル類;
ペンタエリスリトールジ(メタ)アクリレート等の多価アルコールの(メタ)アクリル酸ジエステル類;
2,2-ビス{4-(アクリロキシ・ジエトキシ)フェニル}プロパン、2,2-ビス{4-(アクリロキシ・ポリプロポキシ)フェニル}プロパン等のエチレンオキシドあるいはプロピレンオキシド付加物の(メタ)アクリル酸ジエステル類;等が挙げられる。
具体的には、(ジ)ペンタエリスリトールトリ(メタ)アクリレート、(ジ)ペンタエリスリトールテトラ(メタ)アクリレート、(ジ)ペンタエリスリトールペンタ(メタ)アクリレート、(ジ)ペンタエリスリトールヘキサ(メタ)アクリレート、トリペンタエリスリトールトリアクリレート、トリペンタエリスリトールヘキサトリアクリレート、トリメチロールプロパントリ(メタ)アクリレート、トリメチロールエタントリ(メタ)アクリレート、ジトリメチロールプロパンテトラ(メタ)アクリレート、EO変性トリメチロールプロパントリ(メタ)アクリレート、PO変性トリメチロールプロパントリ(メタ)アクリレート、EO変性リン酸トリ(メタ)アクリレート、1,2,4-シクロヘキサンテトラ(メタ)アクリレート、ペンタグリセロールトリアクリレート、1,2,3-クロヘキサンテトラメタクリレート、ポリエステルポリアクリレート、カプロラクトン変性トリス(アクリロキシエチル)イソシアヌレート、等が挙げられる。
3個以上の(メタ)アクリロイル基を有する多官能アクリレート系化合物類の具体化合物としては、特開2007-256844号公報の段落番号0096等を参考にすることができる。
具体的な化合物の具体例としては特開2007-256844号公報の段落番号0017等の記載を参考にすることができる。
ハードコート層は、高分子化合物を含有していてもよい。高分子化合物を添加することで、硬化収縮を小さくでき、また、樹脂粒子の分散安定性(凝集性)に関わる塗布液の粘度調整をより優位に行うことができる。これに加えて、乾燥過程での固化物の極性を制御して樹脂粒子の凝集挙動を変えたり、乾燥過程での乾燥ムラを減じたりすることもでき、好ましい。
ハードコート層の形成に利用可能な硬化性組成物の一例は、(メタ)アクリレート系化合物を含む硬化性組成物である。硬化性組成物は、(メタ)アクリレート系化合物とともに、光ラジカル重合開始剤または熱ラジカル重合開始剤を含有するのが好ましく、所望により、さらにフィラー、塗布助剤、その他の添加剤を含有していてもよい。硬化性組成物の硬化は、光ラジカル重合開始剤または熱ラジカル重合開始剤の存在下、電離放射線の照射または加熱により重合反応を進行させることで実行できる。電離放射線硬化と熱硬化の双方を実行することもできる。光および熱重合開始剤としては市販の化合物を利用することができ、それらは、「最新UV硬化技術」(p.159,発行人;高薄一弘,発行所;(株)技術情報協会,1991年発行)や、BASF(株)のカタログに記載されている。
本発明の光学フィルムのセルロースアシレートフィルム上に形成されるハードコート層は、セルロースアシレートフィルムと高い密着性を有している。特に、本発明の一般式(I)で表される化合物を含有するセルロースアシレートフィルム上に上述の好適な硬化性組成物で形成されたハードコート層は、その硬化性組成物が、本発明の一般式(I)で表される化合物と相俟って、セルロースアシレートフィルムとさらに高い密着性で形成される。従って、このようなセルロースアシレートフィルムおよびハードコート層を有する本発明の光学フィルムは、光照射等によってもセルロースアシレートフィルムとハードコート層との密着性を維持し、光耐久性に優れる。
本発明の偏光板は、偏光子と本発明の光学フィルムとを少なくとも有する。本発明の光学フィルムは光によるフィルムの着色抑制効果に優れるため、偏光板保護膜として用いることが好ましい。本発明の偏光板は、偏光子と、この偏光子の片面または両面に本発明の光学フィルムを有することが好ましい。偏光子には、ヨウ素系偏光子、二色性染料を用いる染料系偏光子やポリエン系偏光子がある。ヨウ素系偏光子および染料系偏光子は、一般にポリビニルアルコール系フィルムを用いて製造する。本発明の光学フィルムを偏光板保護膜として用いる場合、偏光板の作製方法は特に限定されず、一般的な方法で作製することができる。例えば、本発明の光学フィルムのセルロースアシレートフィルムをアルカリ処理し、ポリビニルアルコールフィルムをヨウ素溶液中に浸漬延伸して作製した偏光子の両面に完全ケン化ポリビニルアルコール水溶液を用いて貼り合わせる方法がある。アルカリ処理の代わりに特開平6-94915号公報、特開平6-118232号公報に記載されているような易接着加工を施してもよい。セルロースアシレートフィルムの処理面と偏光子を貼り合わせるのに使用される接着剤としては、例えば、ポリビニルアルコール、ポリビニルブチラール等のポリビニルアルコール系接着剤や、ブチルアクリレート等のビニル系ラテックス等が挙げられる。
偏光子層の透過軸と偏光板保護フィルムの遅相軸についての平行とは、偏光板保護フィルムの主屈折率nxの方向と偏光板の透過軸の方向とが±10°の角度で交わっていることを意味する。この角度は、5°以内が好ましく、より好ましくは3°以内、さらに好ましくは1°以内、最も好ましくは0.5°以内である。
また、偏光子層の透過軸と偏光板保護フィルムの遅相軸についての直交とは、偏光板保護フィルムの主屈折率nxの方向と偏光板の透過軸の方向とが90°±10°の角度で交わっていることを意味する。この角度は、90°±5°が好ましく、より好ましくは90°±3°、さらに好ましくは90°±1°、最も好ましくは90°±0.5°である。上記範囲とすることで、偏光板クロスニコル下での光抜けをより低減することができる。遅相軸の測定は、公知の種々の方法で測定することができ、例えば、複屈折計(KOBRADH、王子計測機器(株)製)を用いて行うことができる。
本発明の液晶表示装置は、液晶セルと本発明の偏光板とを少なくとも有する。本発明の液晶表示装置において、偏光板、第一偏光板および第二偏光板を有する場合には、少なくとも一方が、本発明の偏光板であるIPS、OCBまたはVAモードの液晶表示装置であることが好ましい。
本発明の液晶表示装置は、好ましくは、液晶セル(液晶層)と、液晶セルの両側に積層され、液晶セル側とは反対側の面に光学フィルムを具備する偏光板とを有している。すなわち、本発明の液晶表示装置は、第一偏光板、液晶セルおよび第二偏光板を有し、偏光板それぞれと液晶セルとで挟持される偏光板面と反対面に本発明の光学フィルムを具備しているのが好ましい。このような構成を有する液晶表示装置は、表示ムラの抑制に優れ、高い表示性能を発揮する。
また、本発明の液晶表示装置は、好ましくは、視認側に配置された偏光板が視認側の光学フィルム表面上にハードコート層を有する光学フィルム、特にセルロースアシレートフィルムを有している。このような構成を有する液晶表示装置は、表示ムラの抑制に優れた高い表示性能に加えて、優れた耐擦傷性と光耐久性を発揮する。
なお、図1および図2に、本発明の液晶表示装置の一例についての構成を示したが、本発明の液晶表示装置の具体的な構成としては特に制限はなく公知の構成を採用できる。また、特開2008-262161号公報の図2に記載の構成も好ましく採用することができる。
本発明の一般式(I)で表される化合物を以下のようにして合成した。
代表的な化合物の合成例を以下に示す。
なお、得られた化合物の構造は、1H-NMRスペクトル(300MHz)、マススペクトル(MALDI-TOF-MS)で確認した。
以下の反応スキームで例示化合物(1-1)を合成した。
MS(MALDI) Exact mass calculated for[C20H21NO6+H+]371.1 Found 371.2
得られた例示化合物のpKaの測定は、25℃で、THF(テトラヒドロフラン)/H20(水)=6/4の体積比の混合溶媒中でアルカリ滴定法により、電位差自動滴定測定〔AT-610:京都電子工業(株)製〕を用いて行った。
以下に、代表的な化合物のpKa値を示す。
例示化合物(1-1) 6.0
例示化合物(1-7) 6.4
例示化合物(4-1) 6.5, 8.1
(セルロースアシレートの調製)
総アセチル置換度Bが2.87のセルロースアシレートを調製した。これは、触媒として硫酸(セルロース100質量部に対し7.8質量部)を添加し、アシル置換基の原料となるカルボン酸を添加し、40℃でアシル化反応を行った。またアシル化後に40℃で熟成を行った。さらにこのセルロースアシレートの低分子量成分をアセトンで洗浄し除去した。
・セルロースアシレート溶液の調製
下記の組成物をミキシングタンクに投入し、攪拌して各成分を溶解し、セルロースアシレート溶液101を調製した。
セルロースアシレート溶液101の組成
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総アセチル置換度(B)2.87、重合度370のセルロースアセテート
100.0質量部
下記表1に示す比較化合物(0-1) 4.0質量部
第一工業化学社製モノペット(登録商標)SB(可塑剤)
9.0質量部
イーストマン・ケミカル社製SAIB-100(可塑剤) 3.0質量部
メチレンクロライド(第1溶媒) 353.9質量部
メタノール(第2溶媒) 89.6質量部
n-ブタノール(第3溶媒) 4.5質量部
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下記の組成物を分散機に投入し、攪拌して各成分を溶解し、マット剤溶液102を調製した。
マット剤溶液102の組成
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平均粒子サイズ20nmのシリカ粒子(AEROSIL R972、
日本アエロジル(株)製) 2.0質量部
メチレンクロライド(第1溶媒) 69.3質量部
メタノール(第2溶媒) 17.5質量部
n-ブタノール(第3溶媒) 0.9質量部
セルロースアシレート溶液101 0.9質量部
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下記の組成物をミキシングタンクに投入し、加熱しながら攪拌して、各成分を溶解し、紫外線吸収剤溶液103を調製した。
紫外線吸収剤溶液103の組成
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下記紫外線吸収剤(UV-1) 20.0質量部
メチレンクロライド(第1溶媒) 61.0質量部
メタノール(第2溶媒) 15.4質量部
n-ブタノール(第3溶媒) 0.8質量部
セルロースアシレート溶液101 12.8質量部
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・セルロースアシレート溶液の調製
下記の組成物をミキシングタンクに投入し、攪拌して各成分を溶解し、基層用ドープを調製した。
セルロースアシレート溶液201の組成
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総アセチル置換度(B)2.87、重合度370のセルロースアセテート
100.0質量部
第一工業化学社製モノペット(登録商標)SB(可塑剤)
9.0質量部
イーストマン・ケミカル社製SAIB-100(可塑剤) 3.0質量部
下記表1に示す比較化合物(0-1) 4.0質量部
紫外線吸収剤(UV-1) 2.0質量部
メチレンクロライド(第1溶媒) 297.7質量部
メタノール(第2溶媒) 75.4質量部
n-ブタノール(第3溶媒) 3.8質量部
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ドラム流延装置を用い、上記のように調製した基層用ドープと、その両側に表層用ドープとを3層同時にステンレス製の流延支持体(支持体温度-9℃)に流延口から均一に流延した。各層のドープ中の残留溶媒量が略70質量%の状態で剥ぎ取り、フィルムの幅方向の両端をピンテンターで固定し、残留溶媒量が3~5質量%の状態で、TD方向に1.28倍(28%)延伸しつつ乾燥した。その後、熱処理装置のロール間を搬送することにより、さらに乾燥し、比較の光学フィルムNo.101を得た。得られた光学フィルムNo.101の厚みは60μm、幅は1480mmであった。
ここで、これらの光学フィルムは、以後において偏光板保護フィルムとも称す。
このようにして得られた各光学フィルム中のヘイズを測定し、下記A+~Cの基準で評価した。
ヘイズの測定は、各光学フィルムをヘイズメーター“HGM-2DP”(商品名、スガ試験機(株)製)を用い、JIS K-7136に従って測定した。
A+:ヘイズが0.1%未満
A :ヘイズが0.1%以上0.3%未満
B :ヘイズが0.3%以上0.7%未満
C :ヘイズが0.7%以上
光学フィルムNo.101~106を偏光板保護フィルムとして使用し、これらの各偏光板保護フィルムを、2.3mol/Lの水酸化ナトリウム水溶液に、55℃で3分間浸漬した。室温の水洗浴槽中で洗浄し、30℃で0.05mol/Lの硫酸を用いて中和した。再度、室温の水洗浴槽中で洗浄し、さらに100℃の温風で乾燥した。このようにして、各偏光板保護フィルムに対して表面の鹸化処理を行った。
延伸したポリビニルアルコールフィルムにヨウ素を吸着させて偏光子を作製した。
鹸化処理した各偏光板保護フィルムを、ポリビニルアルコール系接着剤を用いて、偏光子の片側に貼り付けた。市販のセルローストリアセテートフィルム(フジタックTD80UF、富士フイルム(株)製)も同様の鹸化処理を行い、ポリビニルアルコール系接着剤を用いて、鹸化処理した偏光板保護フィルムが貼り付けてある側とは反対側の偏光子の面に、鹸化処理した市販のセルローストリアセテートフィルムを貼り付けた。
この際、偏光子の透過軸と、鹸化処理済みの偏光板保護フィルムの遅相軸とが平行になるように配置した。また、偏光子の透過軸と鹸化処理済みの市販のセルローストリアセテートフィルムの遅相軸についても、直交するように配置した。
このようにして光学フィルムNo.101~106に対応する各偏光板を作製した。
偏光子耐久性試験は偏光板をガラスに粘着剤を介して貼り付けた形態で次のように行った。
ガラスの上に偏光板を本発明のセルロースアシレートフィルムが空気界面側になるように貼り付けたサンプル(約5cm×5cm)を2つ作製した。
単板直交透過率の測定ではこのサンプルのフィルムの本発明のセルロースアシレートフィルムの側を光源に向けてセットして測定した。
2つのサンプルをそれぞれ測定し、その平均値を本発明における偏光板の直交透過率とした。
偏光板の直交透過率は、日本分光(株)製、自動偏光フィルム測定装置VAP-7070を用いて380nm~780nmの範囲で測定し、410nmにおける測定値を採用した。
その後、下記の条件で各偏光板を経時保存した後に同様の方法で直交透過率を測定した。
経時前後の直交透過率の変化率を、[(経時前の直交透過率と経時後の直交透過率の差分)/(経時前の直交透過率)]×100で、求め、これを偏光子耐久性として、下記基準で評価した。
なお、調湿なしの環境下での相対湿度は、0~20%の範囲であった。
-経時条件-
80℃、相対湿度90%の環境下で250時間保存した。
A :経時前後の直交透過率の変化率が0.7%未満
B :経時前後の直交透過率の変化率が0.7%以上0.8%未満
C :経時前後の直交透過率の変化率が0.8%以上1.0%未満
D :経時前後の直交透過率の変化率が1.0%以上
TG/DTA測定装置(エスアイアイ・ナノテクノロジー株式会社製TG/DTA7200)を用い、本発明の一般式(I)で表される化合物を室温から140℃に昇温し、140℃で1時間保持した時の各化合物の質量の変化率(昇温前の質量に対する変化率)を測定し、下記の基準で評価した。
A :質量の変化率が0.2%以下
B :質量の変化率が0.2%以上0.5%未満
C :質量の変化率が0.5%以上
一般式(I)で表される化合物の合成で測定した方法と同じ方法であり、以下のようにして測定した。
本発明の化合物および比較化合物に対して、25℃で、THF(テトラヒドロフラン)/H20(水)=6/4の体積比の混合溶媒中でのpKaを、アルカリ滴定法により、電位差自動滴定測定(AT-610:京都電子工業株式会社)を用いて行った。
一方、比較化合物(0-1)を含有する偏光板保護フィルムは、セルロースアシレートとの相溶性は示したが、揮散性抑制効果が不十分であった。
本発明の一般式(I)で表される化合物も比較の化合物も含まない比較の偏光板保護フィルム(フィルムNo.106)では、本発明の光学フィルムである偏光板保護フィルムと比較して、偏光子耐久性において劣っていた。この結果からも、本発明の一般式(I)で表される化合物がヘイズを上昇させることなく、偏光子耐久性を改善できることがわかった。
(ハードコート層付き光学フィルムの作製)
実施例1で作製した偏光板作製前の各光学フィルムの表面に下記の硬化組成物のハードコート層溶液を塗布し、紫外線を照射して硬化させ、厚み6μmのハードコート層を形成したハードコート層付き光学フィルムを作製した。
なお、下記表2では、単層の光学フィルムNo.と、これに対応するハードコート層付き光学フィルムNo.に共通のフィルムNo.を付けて表している。
ハードコート層溶液の硬化組成
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モノマー ペンタエリスリトールトリアクリレート/
ペンタエリスリトールテトラアクリレート(混合質量比3/2)
53.5質量部
UV重合開始剤 IrgacureTM907
(BASF(株)製) 1.5質量部
酢酸エチル 45質量部
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上記で作製した各ハードコート層付き光学フィルムNo.101~106について、JIS K 5600に準処した碁盤目試験を行った。具体的には、硬化済みハードコート層付き光学フィルムをXeで48時間照射した。Xeの照射後のハードコート層に1mm間隔で縦横に11本の切れ込みを入れて1mm角の碁盤目を100個作った。この上にセロハンテープおよびマイラーテープを貼り付け、素早く剥がし剥がれた箇所を目視観察により密着評価した。なお、Xeの照射はスガ試験機株式会社製のスーパーキセノンウェザーメーターSX75を用いた。
密着性は下記基準で評価した。評価が「B」以上であると、セルロースアセテートフィルムとハードコート層との密着性が高く、優れた光耐久性を発揮する。
A :剥がれ箇所0~30マス
B :剥がれ箇所31~50マス
C :剥がれ箇所51~80マス
D :剥がれ箇所81マス以上
(光学フィルム:セルロースアシレートフィルムの作製および評価)
下記の組成物をミキシングタンクに投入し、攪拌して各成分を溶解し、セルロースアセテート溶液を調製した。
セルロースアセテート溶液の組成
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総アセチル置換度(B)2.87、重合度370のセルロースアセテート
100.0質量部
例示化合物(1-7) 4.0質量部
下記紫外線吸収剤(UV-2) 2.0質量部
第一工業化学(株)製モノペット(登録商標)SB(可塑剤)
9.0質量部
イーストマン・ケミカル社製SAIB-100(可塑剤) 3.0質量部
メチレンクロライド(第1溶媒) 78.3質量部
メタノール(第2溶媒) 11.7質量部
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本発明のセルロースアシレートフィルムNo.202~211および比較のセルロースアシレートフィルムNo.201を使用して、実施例1と同様にして、偏光板を作製し、偏光子の耐久性を評価した。
なお、偏光子の耐久性の評価は、下記の経時条件で行い、得られた結果を下記の評価基準により評価した。
60℃、相対湿度95%の環境下で650時間
A :経時前後の直交透過率の変化率が0.3%未満
B :経時前後の直交透過率の変化率が0.3%以上0.5%未満
C :経時前後の直交透過率の変化率が0.5%以上0.7%未満
D :経時前後の直交透過率の変化率が0.7%以上
実施例3におけるセルロースアシレートフィルムNo.202、204、211における可塑剤のモノペットSBおよびSAIB-100に変えて、下記可塑剤Pを、下記配合量用いて以外は実施例3と同様にして、対応するセルロースアシレートフィルムNo.302、304、311を作製し、実施例1と同様にして各偏光板を作製し、評価した。
フタル酸/エタンジオールの重縮合物
末端は酢酸エステル基で数平均分子量は800 10.0質量部
22 カラーフィルタ基板
23 液晶層(液晶セル)
24 アレイ基板
25 導光板
26 光源
31a、31a’、31b 光学フィルム(偏光板保護フィルム)
311a セルロースアシレートフィルム
311b ハードコート層
32 偏光子
R 偏光方向
Claims (13)
- 前記Lが、単結合、アルキレン基またはアルカントリイル基である請求項1に記載の光学フィルム。
- 前記Lが、アルキレン基である請求項1または2に記載の光学フィルム。
- 前記R2が、アリール基またはシクロアルキル基が置換してもよいアルキル基である請求項1~4のいずれか1項に記載の光学フィルム。
- 前記セルロースアシレートの総アシル置換度Aが下記式を満足する請求項1~6のいずれか1項に記載の光学フィルム。
1.5≦A≦3.0 - 前記セルロースアシレートのアシル基がアセチル基であり、総アセチル置換度Bが下記式を満足する請求項1~7のいずれか1項に記載の光学フィルム。
2.0≦B≦3.0 - 前記総アセチル置換度Bが、2.5以上2.97未満である請求項8に記載の光学フィルム。
- 可塑剤の少なくとも1種を含有する請求項1~9のいずれか1項に記載の光学フィルム。
- 前記光学フィルムが、少なくとも2層からなり、前記セルロースアシレートおよび少なくとも1種の前記一般式(I)で表される化合物を含む層に、さらにハードコート層を有する請求項1~10のいずれか1項に記載の光学フィルム。
- 偏光子と、該偏光子の少なくとも一方の面に請求項1~11のいずれか1項に記載の光学フィルムを有する偏光板。
- 請求項12に記載の偏光板と液晶セルを少なくとも有する液晶表示装置。
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CN201480042862.9A CN105452913B (zh) | 2013-07-30 | 2014-07-30 | 光学膜、使用该光学膜的偏振片及液晶显示装置 |
JP2015529606A JP6238419B2 (ja) | 2013-07-30 | 2014-07-30 | 光学フィルム、それを用いた偏光板および液晶表示装置 |
US15/008,990 US10001584B2 (en) | 2013-07-30 | 2016-01-28 | Optical film, and polarizing plate and liquid crystal display device that use this optical film |
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JP2013158278 | 2013-07-30 | ||
JP2013-158278 | 2013-07-30 |
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US15/008,990 Continuation US10001584B2 (en) | 2013-07-30 | 2016-01-28 | Optical film, and polarizing plate and liquid crystal display device that use this optical film |
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WO2015016286A1 true WO2015016286A1 (ja) | 2015-02-05 |
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US (1) | US10001584B2 (ja) |
JP (1) | JP6238419B2 (ja) |
CN (1) | CN105452913B (ja) |
WO (1) | WO2015016286A1 (ja) |
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CN114966933A (zh) * | 2021-02-26 | 2022-08-30 | 京东方科技集团股份有限公司 | 偏光组件及其制备方法、显示面板、显示设备 |
Citations (3)
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JPS53114857A (en) * | 1977-03-17 | 1978-10-06 | Dainichi Seika Kogyo Kk | Additive for rigid pvc resin |
JP2004148811A (ja) * | 2002-10-08 | 2004-05-27 | Fuji Photo Film Co Ltd | セルロースアシレートフイルムの製造方法、セルロースアシレートフイルム、並びにそれを用いた光学機能性シート、偏光板、液晶表示装置及びハロゲン化銀写真感光材料 |
JP2012072348A (ja) * | 2010-03-12 | 2012-04-12 | Fujifilm Corp | 樹脂フィルムとその製造方法、偏光板および液晶表示装置 |
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JP2006053429A (ja) * | 2004-08-13 | 2006-02-23 | Fuji Photo Film Co Ltd | 光学補償フイルム及び液晶表示装置 |
JP2008052041A (ja) * | 2006-08-24 | 2008-03-06 | Fujifilm Corp | 光学フィルム、偏光板、液晶表示装置 |
US7704675B2 (en) * | 2006-11-09 | 2010-04-27 | Fujifilm Corporation | Planographic printing plate precursor and stack thereof |
JP2008255340A (ja) * | 2007-03-14 | 2008-10-23 | Fujifilm Corp | セルロースアシレートフィルム、偏光板及びそれを用いた液晶表示装置 |
JP2008268938A (ja) * | 2007-03-29 | 2008-11-06 | Fujifilm Corp | 保護フィルム、偏光板、及び液晶表示装置 |
JP2011069922A (ja) * | 2009-09-24 | 2011-04-07 | Fujifilm Corp | 液晶表示装置 |
JP5437780B2 (ja) | 2009-12-03 | 2014-03-12 | 富士フイルム株式会社 | 偏光板保護フィルム、偏光板および液晶表示装置 |
US9040129B2 (en) * | 2010-04-26 | 2015-05-26 | Fujifilm Corporation | Protective film of polarizer, polarizer and method for producing it, and liquid crystal display device |
US20120258263A1 (en) * | 2011-04-11 | 2012-10-11 | Fujifilm Corporation | Cellulose acylate film, polarizing plate using the same and liquid crystal display device |
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2014
- 2014-07-30 JP JP2015529606A patent/JP6238419B2/ja not_active Expired - Fee Related
- 2014-07-30 WO PCT/JP2014/070135 patent/WO2015016286A1/ja active Application Filing
- 2014-07-30 CN CN201480042862.9A patent/CN105452913B/zh not_active Expired - Fee Related
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2016
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Patent Citations (3)
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JPS53114857A (en) * | 1977-03-17 | 1978-10-06 | Dainichi Seika Kogyo Kk | Additive for rigid pvc resin |
JP2004148811A (ja) * | 2002-10-08 | 2004-05-27 | Fuji Photo Film Co Ltd | セルロースアシレートフイルムの製造方法、セルロースアシレートフイルム、並びにそれを用いた光学機能性シート、偏光板、液晶表示装置及びハロゲン化銀写真感光材料 |
JP2012072348A (ja) * | 2010-03-12 | 2012-04-12 | Fujifilm Corp | 樹脂フィルムとその製造方法、偏光板および液晶表示装置 |
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JP6238419B2 (ja) | 2017-11-29 |
US10001584B2 (en) | 2018-06-19 |
CN105452913A (zh) | 2016-03-30 |
US20160187537A1 (en) | 2016-06-30 |
CN105452913B (zh) | 2017-10-27 |
JPWO2015016286A1 (ja) | 2017-03-02 |
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