TW201803720A - Manufacturing method of cellulose acylate film - Google Patents

Abstract

A cellulose acylate film is provided. When the cellulose acylate film is incorporated into a liquid crystal display device, it maintains typical display characteristics (high front contrast, suppression of light leakage in an oblique direction) and is unlikely to produce an uneven display due to condensation. The cellulose acylate film has a thickness of 20 [mu]m~60 [mu]m and contains a cellulose acylate having total acyl substitution degree of 2.0~2.55 and an additive. The cellulose acylate film satisfies the following formula (I) to formula (V). formula (I) 30 nm ≤ Re(590) ≤ 90 nm formula (II) 100 nm ≤ Rth(590) ≤ 150 nm formula (III) 2.0 ≤ Rth(590)/d ≤ 5.0 formula (IV) internal haze ≤ 0.05% formula (V) [Delta]M ≤ 1.0%.

Description

Method for producing bismuth cellulose film

The present invention relates to a deuterated cellulose film, and a polarizing plate and a liquid crystal display device using the same. In particular, there is a deuterated cellulose film which can be preferably used as an optical film such as a polarizing plate protective film or a retardation film.

In recent years, the use of televisions (TVs) for liquid crystal display devices is progressing, and with the increase in the size of screens, higher image quality and lower prices are required. In particular, a liquid crystal display device of a vertical alignment (VA) mode has a relatively high contrast ratio and a high yield of manufacturing. Therefore, it is the most common liquid crystal display device as a liquid crystal display device for TV. A polarizing plate is incorporated in such a liquid crystal display device, and a cellulose oxide film is used as a protective film for such a polarizing plate (Japanese Laid-Open Patent Publication No. 2003-62899).

However, in recent years, the demand for thinning in liquid crystal display devices has been increasing. Therefore, it is advantageous if the polarizing plate which is a component of the liquid crystal display device can be thinned.

As a method of thinning a polarizing plate, it is conceivable to use a thin film made of deuterated cellulose as a protective film of a polarizing plate as a main component (thinized cellulose film). However, there is concern that such a thin film may cause display unevenness caused by condensation. The unevenness of condensation is caused by the fact that water is usually partially adhered to the film, and the portion where water adheres and the portion where water does not adhere are uneven. In particular, as a result of research conducted by the present inventors, it has been found that when the above-described cellulose telluride film is incorporated in a liquid crystal display device as described below, display unevenness of the liquid crystal display device occurs in a short time, and the liquid crystal display device is a glass of a panel. It is a thin liquid crystal display device of 500 μm or less.

The present invention has an object to solve the above problems, and an object of the invention is to provide a cellulose-deposited cellulose film which is a thin silicon carbide film which is maintained when incorporated in a liquid crystal display device. The general display characteristics (high front contrast, light leakage in the oblique direction) are suppressed, and display unevenness caused by condensation is hard to occur.

Here, Japanese Patent Laid-Open Publication No. 2003-62899 discloses a method of increasing the Nz factor in a cellulose ester film having a high degree of substitution of a mercapto group, and as a means thereof, a method of stretching in water is employed. However, as a result of the investigation by the inventors of the present invention, it is known that the cellulose ester film having a high degree of substitution of a thiol group is extended in water, and the obtained film has a slightly higher haze. Further, in order to thin the film and to develop a predetermined retardation (Rth), it is necessary to increase Rth/d (d is the thickness of the film), as described in Japanese Laid-Open Patent Publication No. 2003-62899. A cellulose ester film having a high degree of substitution of a thiol group cannot produce a film having a high Rth/d.

In the present invention, it has been found that by using a cellulose ester having a low thiol group substitution degree and performing water treatment after stretching, even a film can exhibit a desired retardation and can reduce internal haze and can be reduced. The equilibrium water content before and after the impregnation of the pure water is changed, and as a result, it is possible to obtain a cellulose-deposited film which is less likely to become uneven in condensation even if water adheres.

Specifically, the above problem is preferably solved by means <2> to <11> by the following means <1>. <1> A deuterated cellulose film having a film thickness of 20 μm to 60 μm, containing deuterated cellulose having a total thiol substitution degree of 2.0 to 2.55, and an additive satisfying the following formula (I) to formula (IV) ). Formula (I) 30 nm≦Re(590)≦90 nm Formula (II) 100 nm≦Rth(590)≦150 nm Formula (III) 2.0≦Rth(590)/d≦5.0 Formula (IV) Internal haze≦ 0.05% Formula (V) ΔM≦1.0% (wherein, Re(590) represents the retardation (nm) in the in-plane direction at a wavelength of 590 nm, and Rth(590) represents the retardation in the film thickness direction at a wavelength of 590 nm (nm) d represents the film thickness (μm). ΔM represents the 25 ° C, 80% obtained by the Karl Fischer's method after immersing the deuterated cellulose film in pure water at 40 ° C for 24 hours. The balance of the water content and the equilibrium moisture content at 25 ° C and 80% obtained by the Karl Fischer method before the impregnation. <2> The cellulose-deposited film according to <1>, wherein the above additive contains aroma Family of compounds. <3> The cellulose-deposited film according to <2>, which contains at least one selected from the group consisting of a sugar ester compound, a nitrogen-containing cyclic compound, and an ester-based polymer as the aromatic-containing compound. <4> The cellulose-deposited film according to any one of <1> to <3> which has a film thickness of 30 μm to 50 μm, a total thiol substitution degree of 2.4 to 2.55, and a Re(590) of 40. From nm to 90 nm, Rth(590) is from 110 nm to 130 nm, internal haze is 0.03% or less, and ΔM is 0.5% or less. <5> A method for producing a cellulose-deposited film, comprising the step of forming a polymer solution containing deuterated cellulose having a total thiol substitution degree of 2.0 to 2.55, a solvent, and an additive into a film form, And a step of controlling the film to be extended so that the film thickness after stretching becomes 20 μm to 60 μm, and further includes a step of subjecting the stretched film to water treatment. (6) The method for producing a cellulose-deposited film according to the above aspect, wherein the step of performing the water treatment is a step of immersing the deuterated cellulose in water at 25 to 85 ° C for 5 seconds or more, and further comprising The film elongation in the transport direction at the time of the water treatment is adjusted so as to be 1% or less. The method of producing a cellulose-deposited cellulose film according to any one of <1> to <4>, wherein the cellulose-degraded cellulose film is the cellulose-degraded cellulose according to any one of <1> to <4>. membrane. <8> A polarizing plate comprising a polarizing plate, and the cellulose-deposited film according to any one of <1> to <4>. <9> The polarizing plate according to <8>, wherein the polarizing plate further has a protective film on a surface opposite to the deuterated cellulose film, and the protective film is a crucible having a thickness of 20 μm to 60 μm. Cellulose film. <10> A liquid crystal display device comprising the polarizing plate according to <8> or <9>. <11> The liquid crystal display device according to <10>, wherein the liquid crystal display device has a glass substrate having a thickness of 50 μm to 500 μm. [Effects of the Invention]

The present invention can provide a cellulose-deposited cellulose film which is a thin cellulose-deposited film which maintains a high frontal contrast when incorporated in a liquid crystal display device and suppresses light leakage when viewed from an oblique direction. It is also difficult to produce display unevenness caused by condensation.

Hereinafter, the contents of the present invention will be described in detail. The description of the constituent elements described below may be performed based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment. In the specification of the present application, "~" is used in the sense that the numerical values described before and after are included as the lower limit and the upper limit. In addition, in this specification, "front side" means the display surface side, and "rear side" means the backlight side. In addition, in the present specification, "front side" means the normal direction with respect to the display surface, and "front contrast (hereinafter, the contrast is also referred to as CR)" means white measured according to the normal direction of the display surface. Contrast calculated from brightness and black brightness.

<醯化cellulose film>

The cellulose-deposited cellulose film of the present invention is characterized in that the film thickness is 20 μm to 60 μm, and the deuterated cellulose having a total thiol substitution degree of 2.0 to 2.55 and an additive satisfy the following formula (I) to formula (( IV). Formula (I) 30 nm≦Re(590)≦90 nm Formula (II) 100 nm≦Rth(590)≦150 nm Formula (III) 2.0≦Rth(590)/d≦5.0 Formula (IV) Internal haze≦ 0.05% Formula (V) ΔM≦1.0% (wherein, Re(590) represents the retardation (nm) in the in-plane direction at a wavelength of 590 nm, and Rth(590) represents the retardation in the film thickness direction at a wavelength of 590 nm (nm) d represents the film thickness (μm). ΔM represents the equilibrium moisture content and impregnation at 25 ° C, 80% obtained by the Karl Fischer method after immersing the deuterated cellulose film in pure water at 40 ° C for 24 hours. The difference between the equilibrium moisture content at 25 ° C and 80% obtained by the Karl Fischer method)

In the present invention, in the cellulose oxide film having a film thickness of 20 μm to 60 μm and satisfying the above formulas (I) to (III), a cellulose having a predetermined total thiol substitution degree is used, and The internal solution has a haze of 0.05% and a change ΔM of the equilibrium moisture content of 1.0% or less, thereby solving the above problems. Such means are achieved, for example, by water treatment.

Although the reason is not limited to any theory, the following reasons can be considered.

When the deuterated cellulose film is subjected to water treatment, the deuterated cellulose film is hydrated and swollen in water treatment. It is presumed that when the deuterated cellulose film is dried, water is removed, but a part of the portion of the deuterated cellulose film in which water is present becomes a void. In addition, the water-treated deuterated cellulose film has an increased equilibrium moisture content in a high-humidity environment. Therefore, it is considered that water molecules easily enter the above-mentioned voids.

However, if water adheres to the deuterated cellulose film which is not subjected to water treatment, the deuterated cellulose film contains water and swells only at the portion where water adheres. It is considered that although dehydration is carried out by passage of time or drying, the film density of the portion where water exists is lowered and the equilibrium moisture content is increased. Even in the same environment, the equilibrium moisture content is different between the portion where the water droplet is dropped and the portion where the water droplet is not dropped, so that unevenness is observed at the boundary portion.

On the other hand, once water adheres to the deuterated cellulose film subjected to the water treatment, the portion to which the water adheres contains water and swells. However, since the voids in the membrane have increased, the equilibrium moisture content of the membrane after dehydration does not change. Therefore, it is presumed that there is no difference in equilibrium moisture content between the portion where the water adheres to the film and the portion where the water is not adhered, and display unevenness due to unevenness in condensation does not occur.

<Deuterated cellulose>

The deuterated cellulose film of the present invention contains deuterated cellulose having a total thiol substitution degree of 2.0 to 2.55.

The cellulose which is a raw material of the deuterated cellulose used in the present invention may be cotton linter or wood pulp (broadwood pulp, conifer pulp), etc., and cellulose derived from any raw material cellulose may be used, and sometimes Can be mixed. For the detailed description of the raw material cellulose, for example, Maruza and Uda, "Plastic Materials Lecture (17) Cellulose Resin", Nikkan Kogyo Shimbun (issued in 1970), or Invention Association Public Technical Report No. 2001- The cellulose described in the 1745 (page 7 to page 8) is not particularly limited to the cellulose-deposited layered film of the present invention.

First, the cellulose deuterated cellulose which can be preferably used in the present invention will be described in detail. The glucose unit constituting the cellulose having β-1,4 has a free hydroxyl group at the 2, 3 and 6 positions. The deuterated cellulose is a polymer obtained by thiolating a part or all of some of the hydroxyl groups with a mercapto group. The thiol substitution degree refers to the total ratio of the hydroxyl groups of the cellulose at the 2, 3, and 6 positions (the thiolation at each position is the degree of substitution 1).

The mercapto group used in the deuterated cellulose of the present invention may be one type or two or more types of mercapto groups.

The mercapto group of the deuterated cellulose in the present invention may be an aliphatic group or an allyl group, and is not particularly limited. These may be, for example, an alkylcarbonyl ester, an alkenylcarbonyl ester or an aromatic carbonyl ester of cellulose, an aromatic alkylcarbonyl ester or the like, and each may have a further substituted group. Preferred examples of such a group include an ethyl group, a propyl group, a butyl group, a butyl group, a hexyl group, a decyl group, a decyl group, a fluorenyl group, a fluorenyl group, a thirteenth fluorenyl group, and a tetradecyl group. , hexadecanyl, octadecyl, isobutyl decyl, tributyl decyl, cyclohexanecarbonyl, oleoyl, benzhydryl, naphthylcarbonyl, cinnamyl and the like. More preferably, it is an ethyl group, a propyl group, a butyl group, a fluorenyl group, a decyl group, a tributyl sulfonyl group, an oil fluorenyl group, a benzamyl group, a naphthylcarbonyl group, a cinnamyl group, and the like. Particularly preferred are an ethyl fluorenyl group, a propyl fluorenyl group, and a butyl fluorenyl group (in the case where the fluorenyl group has 2 to 4 carbon atoms), and particularly preferably an acetyl group (when the cellulose fluorene is cellulose acetate).

That is, examples of the above-mentioned deuterated cellulose include Triacetyl Cellulose (TAC), Diacetyl Cellulose (DAC), Cellulose Acetate Propionate (CAP), and Acetic Acid. Cellulose Acetate Butyrate (CAB), cellulose acetate phthalate, and the like. From the viewpoint of delaying the developability or cost, it is preferred that the cellulose-deposited film of the present invention is cellulose acetate.

The film of the present invention contains deuterated cellulose having a total thiol substitution degree of 2.0 to 2.55. The total thiol substitution degree of the above deuterated cellulose is preferably from 2.4 to 2.55, more preferably from 2.4 to 2.5.

Further, the degree of substitution of the thiol group can be determined in accordance with the method specified in ASTM-D817-96. The moiety that is not substituted with a thiol group is usually present as a hydroxyl group.

In a preferred embodiment of the present invention, even a cellulose-deposited cellulose film containing deuterated cellulose having a low degree of substitution of a mercapto group can simultaneously improve the retardation change under wet heat conditions and the reverse wavelength of the wavelength dispersion. The disperse (ΔRe is positive) is improved, and the deuterated cellulose film containing deuterated cellulose having a low degree of substitution of a mercapto group can be produced.

These deuterated celluloses can be synthesized by a known method, and can be synthesized, for example, by the method described in JP-A-10-45804.

In the thiolation of cellulose, when an acid anhydride or hydrazine chloride is used as the oximation agent, an organic solvent (for example, acetic acid), dichloromethane or the like is used as the organic solvent of the reaction solvent.

As the catalyst, when the oxime agent is an acid anhydride, a protonic catalyst such as sulfuric acid can be preferably used, and when the oximation agent is ruthenium chloride (for example, CH ₃ CH ₂ COCl), a basic compound can be used.

The most common industrial synthesis method of mixed fatty acid esters of cellulose is a method of using a mixed organic compound containing a fatty acid (acetic acid, propionic acid, valeric acid, etc.) corresponding to an ethyl hydrazide group and other mercapto groups or an acid anhydride thereof. An acid component that thiolates cellulose.

The molecular weight of the above deuterated cellulose is preferably from 40,000 to 200,000, more preferably from 100,000 to 200,000, in terms of number average molecular weight (Mn). The Mw/Mn of the deuterated cellulose used in the present invention is preferably 4.0 or less, more preferably 1.4 to 2.3.

In the present invention, the average molecular weight and molecular weight distribution of deuterated cellulose and the like can be calculated by Gel Permeation Chromatography (GPC) to calculate the number average molecular weight (Mn) and the weight average molecular weight (Mw), and The method described in WO2008-126535 is disclosed to calculate the ratio of the two.

In the film of the present invention, the content of the above-mentioned deuterated cellulose in the film is preferably 85% by mass or more, more preferably more than 85% by mass, particularly preferably 86% by mass or more, based on the mass of the film. In addition, the higher the total thiol substitution degree of the deuterated cellulose, the more the content of deuterated cellulose in the above film can be reduced, and the lower the degree of total thiol substitution, the more the content of deuterated cellulose in the film can be increased.

<additive>

The deuterated cellulose film of the present invention contains an additive, and as an additive, an aromatic compound is preferable. By using a compound containing an aromatic compound, Re and Rth of the additive have high developability and are easily thinned.

The additive is preferably selected from the group consisting of an ester polymer, a sugar ester compound, and a nitrogen-containing ring compound, more preferably an aromatic ester-based polymer, an aromatic sugar-containing ester compound, or an aromatic nitrogen-containing compound. Ring compound.

(ester polymer)

In the present invention, an ester polymer may be contained as an additive. When such an ester type polymer is blended, the retardation developability is high, and even if moisture intrudes into the film, it is difficult to move in the film, so that the change in retardation before and after the water treatment can be reduced. Further, the ester polymer preferably contains an aromatic group.

Further, it is preferred that both ends of the above ester-based polymer used in the present invention are independently selected from the group consisting of -OH groups, -OC(=O)-R ¹ groups, and -C(=O)-OR ² groups. Any one of a group consisting of -OR ³ groups and -COOH groups (wherein R ¹ to R ³ each independently represent an aliphatic group).

In the present specification, the residue of the ester-based polymer means a partial structure of the ester-based polymer, and indicates a partial structure having a characteristic of a monomer forming an ester-based polymer. For example, the dicarboxylic acid residue formed from the dicarboxylic acid HOOC-R-COOH is -OC-R-CO-, and the diol residue formed from the diol HO-R'-OH is -O-R'- O-.

In the above ester polymer, an aromatic dicarboxylic acid residue and an aliphatic dicarboxylic acid residue can be used as the dicarboxylic acid residue.

The above ester-based polymer used in the present invention preferably contains at least one aromatic dicarboxylic acid residue.

Further, the ratio of the aromatic dicarboxylic acid residue to all the dicarboxylic acid residues in the ester polymer used in the present invention is preferably 50 mol% or more.

By setting the ratio of the aromatic dicarboxylic acid residue to 50 mol% or more, it is possible to obtain sufficient optical display properties (especially, the value of Rth per unit film thickness is large) even when the film thickness is small. The tendency to cellulose membranes.

In the present specification, the above aromatic dicarboxylic acid residue means a dicarboxylic acid residue containing at least one exoaryl group. That is, the above aromatic dicarboxylic acid residue in the present specification includes, for example, -OC-Ar'-L-CO- or -OC-L' in addition to the -OC-Ar-CO-residue. a dicarboxylic acid residue of the structure -Ar''-CO-, or -OC-L''-Ar'''-L''-CO- (the above Ar, Ar', Ar'' and Ar''' Each of the above-mentioned L, L' and L'' independently represents a divalent linking group other than an extended aryl group, respectively. Examples of the divalent linking group other than the above-mentioned aryl group include an aliphatic group or an atomic linking group, and specific examples thereof include an alkylene group, an alkylene group, an oxygen atom, and a sulfur atom.

Among them, from the viewpoint of compatibility with deuterated cellulose, the aromatic dicarboxylic acid residue is preferably a structure of a -OC-Ar-CO- residue.

The Ar is preferably a aryl group having 6 to 16 carbon atoms, more preferably an aryl group having 6 to 12 carbon atoms, particularly preferably a phenyl or anthracene group, and particularly preferably a phenyl group. In addition, the Ar may further have a substituent or may have no substituent, and preferably has no substituent. Examples of the substituent include a hydroxyl group, a mercapto group, and a carbonyl group.

Specific examples of the aromatic dicarboxylic acid residue include a phthalic acid residue, a terephthalic acid residue, an isophthalic acid residue, a 1,5-naphthalene dicarboxylic acid residue, and 1,4. a naphthalene dicarboxylic acid residue, a 1,8-naphthalene dicarboxylic acid residue, a 2,8-naphthalene dicarboxylic acid residue or a 2,6-naphthalene dicarboxylic acid residue. Among these examples, preferred are phthalic acid residues, terephthalic acid residues, 2,6-naphthalenedicarboxylic acid residues, more preferably phthalic acid residues and terephthalic acid residues. More preferably, it is a terephthalic acid residue.

In the above ester polymer, an aromatic dicarboxylic acid residue is formed by an aromatic dicarboxylic acid to be mixed.

When the above ester-based polymer contains a terephthalic acid residue as an aromatic dicarboxylic acid residue, it has better compatibility with deuterated cellulose, and can be produced during film formation and heating of a deuterated cellulose film. It is also difficult to produce a bleed-out cellulose film when it is stretched.

Further, the ester-based polymer may contain only one type of aromatic dicarboxylic acid residue, and may contain two or more types. When two kinds of aromatic dicarboxylic acid residues are contained in the above ester polymer, it is preferred to contain a phthalic acid residue and a terephthalic acid residue.

In addition to the aromatic dicarboxylic acid residue, the above ester polymer may contain an aliphatic dicarboxylic acid residue as a dicarboxylic acid residue.

Specific examples of the aliphatic dicarboxylic acid residue include an oxalic acid residue, a malonic acid residue, a succinic acid residue, a maleic acid residue, a fumaric acid residue, and a pentane. Diacid residue, adipic acid residue, pimelic acid residue, suberic acid residue, sebacic acid residue, sebacic acid residue, dodecanedicarboxylic acid residue or 1,4-cyclohexane An alkanedicarboxylic acid residue or the like.

In the above ester polymer, an aliphatic dicarboxylic acid residue is formed from the aliphatic dicarboxylic acid used for mixing.

The average carbon number of the aliphatic dicarboxylic acid residue is preferably from 5.5 to 10.0, more preferably from 5.5 to 8.0, still more preferably from 5.5 to 7.0. When the average carbon number of the aliphatic diol is 7.0 or less, the heating loss of the compound can be lowered, and the occurrence of a planar failure can be prevented, and the cause of the planar failure can be considered as the bleed out when the ceriumized cellulose mesh is dried. The resulting steps are contaminated. In addition, when the average carbon number of the aliphatic diol is 2.5 or more, the compatibility is excellent, and precipitation of the ester polymer is less likely to occur, which is preferable.

Specifically, when the above-mentioned polymerizable ester contains the above aliphatic dicarboxylic acid residue, it preferably contains a succinic acid residue or an adipic acid residue, and more preferably contains a succinic acid residue.

The ester-based polymer may contain only one aliphatic dicarboxylic acid residue or two or more kinds. When two aliphatic dicarboxylic acid residues are contained in the above ester polymer, it is preferred to contain a succinic acid residue and an adipic acid residue. When one of the aliphatic dicarboxylic acid residues is contained in the above ester polymer, it is preferred to contain a succinic acid residue. By adopting such a form, the average carbon number of the diol residue can be adjusted to the above preferred range, and the compatibility with the cellulose fluorite becomes good.

In the above ester polymer, an aromatic diol residue and an aliphatic diol residue can be used as the diol residue.

The above ester-based polymer used in the present invention contains at least one aliphatic diol residue as a diol residue.

The aliphatic diol used in the present invention may, for example, be an alkyl diol or an alicyclic diol such as ethylene glycol, 1,2-propanediol, 1,3-propanediol or 1,2-butane. Alcohol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dihydroxymethylpentane), 2-n-butyl-2-ethyl-1,3-propanediol ( 3,3-dimethylol heptane), 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol , 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-nonanediol, 1,12-octadecane A diol, a diethylene glycol, a cyclohexane dimethanol, etc. are used, and it is preferable to use it as one type or a mixture of two or more types together with ethylene glycol.

In the present invention, in terms of improving the compatibility of the deuterated cellulose with the ester polymer or increasing the solubility of the ester polymer to the solvent, it is preferred that the above ester polymer is relative to The ratio of the ratio of the aliphatic diol residue having a carbon number of 3 or more in all of the diol residues (hereinafter also referred to as the ratio of the aliphatic diol having a carbon number of 3 or more) is 30 mol% or more.

The ratio of the aliphatic diol having 3 or more carbon atoms is more preferably 30 mol% or more, and particularly preferably 50 mol% to 80 mol%.

Examples of the aliphatic diol residue having 3 or more carbon atoms include a 1,2-propanediol residue, a 1,3-propanediol residue, a 1,2-butanediol residue, and a 1,3-butyl group. Alcohol residue, 2-methyl-1,3-propanediol residue, 1,4-butanediol residue, 1,5-pentanediol residue, 2,2-dimethyl-1,3-propanediol (neopentyl glycol) residue, 1,4-hexanediol residue, 1,4-cyclohexanediol residue, and the like. Among them, the aliphatic diol residue having a carbon number of 3 or more which can be preferably used in the present invention is a 1,2-propanediol residue, a 1,3-propanediol residue, a 1,2-butanediol residue, 1,3-butanediol residue, 2-methyl-1,3-propanediol residue, 1,4-butanediol residue, 1,5-pentanediol residue, 2,2-dimethyl At least one of -1,3-propanediol (neopentyl glycol) residues, more preferably 1,2-propanediol residue, 1,3-propanediol residue, 1,2-butanediol residue, 1, At least one of a 3-butanediol residue, a 2-methyl-1,3-propanediol residue, and a 1,4-butanediol residue is particularly preferably a 1,2-propanediol residue.

Crystallization of the ester polymer can be prevented by using a 1,2-propanediol residue or a 1,3-propanediol residue.

When an aliphatic diol residue is used, an ethylene glycol residue or the like can be used as the diol residue other than the aliphatic diol having 3 or more carbon atoms.

In the above ester-based polymer, an aliphatic diol residue is formed by an aliphatic diol for mixing.

In addition to the aliphatic diol residue, the above ester polymer may contain an aromatic diol residue as a diol residue.

Specific examples of the aromatic diol residue include a bisphenol A residue, a 1,2-hydroxybenzene residue, a 1,3-hydroxybenzene residue, and a 1,4-hydroxybenzene residue. , 4-benzenedimethanol residue, and the like.

In the above ester-based polymer, only one type of aliphatic diol residue may be contained, or two or more types may be contained. When two aliphatic diol residues are contained in the above ester polymer, it is preferred to contain a 1,2-propanediol residue and an ethylene glycol residue.

In the above ester-based polymer, an aromatic diol acid residue is formed from an aromatic diol to be mixed.

The terminal of the above-mentioned ester-based polymer may be directly blocked by an -OH group derived from a diol or a -COOH group derived from a dicarboxylic acid, or may be reacted with a monocarboxylic acid or a monohydric alcohol to carry out a so-called The terminal end is blocked to become -OC(=O)-R ¹ group, -C(=O)-OR ² group, and -OR ³ group (wherein R ¹ to R ³ each independently represent an aliphatic group).

In the case where the both ends of the above ester-based polymer are not blocked, from the viewpoint of suppressing hydrolysis of the ester group, the -OH group at both ends is superior to -COOH at both ends. That is, when both ends of the above ester-based polymer are not blocked, the ester-based polymer is preferably a polyester polyol.

In the case where both ends of the above ester polymer are blocked, both ends are preferably -OC(=O)-R ¹ group, -C(=O)-OR ² group or -OR ³ group. More preferably above both ends -OC (= O) -R ¹ group, i.e., the reaction is more preferably carried out so that the both ends of ester-based polymer and an aliphatic monocarboxylic acid for capping.

At this time, both ends of the ester polymer become an aliphatic monocarboxylic acid residue.

Here, each of R ¹ to R ³ independently represents an aliphatic group. The aliphatic group represented by the above R ¹ to R ³ may be a saturated aliphatic group or an unsaturated aliphatic group as long as the aliphatic group does not contain an aromatic ring. Further, the aliphatic group represented by the above R ¹ to R ³ may be any of a chain aliphatic group and a cyclic aliphatic group (for example, a cycloalkyl group), and the above R ¹ to R ³ When the aliphatic group represented by the chain is a chain aliphatic group, it may be a linear aliphatic group or a branched aliphatic group. The aliphatic group represented by the above R ¹ to R ³ may further have a substituent as long as it does not contradict the gist of the present invention, and the substituent is not particularly limited as long as it does not contain an aromatic ring, but it is preferably not The aliphatic group of the substituent. Further, the number of carbon atoms of the aliphatic group represented by the above R ¹ to R ³ is preferably from 1 to 21, more preferably from 1 to 5, particularly preferably from 1 to 3, still more preferably 1 or 2, and still more preferably 1.

In particular, the aliphatic group represented by the above R ¹ to R ³ is preferably a chain saturated aliphatic group, more preferably a chain alkyl group, and particularly preferably a linear alkyl group.

In other words, when both ends of the ester polymer are blocked, the both ends of the ester polymer are preferably a fluorenyl group having 2 to 22 carbon atoms, more preferably a fluorenyl group having 2 to 6 carbon atoms. Particularly preferred is a fluorenyl group having 2 to 4 carbon atoms (i.e., an ethyl fluorenyl group, a propyl fluorenyl group or a butyl group), and particularly preferably a fluorenyl group having 2 or 3 carbon atoms (i.e., an ethyl group or a propyl group). Further, it is more preferably a fluorenyl group having a carbon number of 2 (i.e., an ethyl group). Further, the thiol group described herein contains an aromatic fluorenyl group (so-called aryl fluorenyl group) in addition to the aliphatic fluorenyl group, but is preferably an aliphatic fluorenyl group. When the carbon number of the thiol group at both ends of the ester-based polymer is 3 or less, the volatility is lowered, and the amount of reduction of the ester-based polymer by heating is not increased, and the occurrence of step contamination or surface failure can be reduced. The production.

In this case, the monocarboxylic acid used for blocking is preferably an aliphatic monocarboxylic acid having 2 to 22 carbon atoms, more preferably an aliphatic monocarboxylic acid having 2 to 6 carbon atoms, particularly preferably carbon. The aliphatic monocarboxylic acid having 2 to 4 is particularly preferably an aliphatic monocarboxylic acid having 2 or 3 carbon atoms, and more preferably an aliphatic monocarboxylic acid having 2 carbon atoms.

On the other hand, when both ends of the above ester polymer are blocked, the both ends of the ester polymer may be -C(=O)-OR ² group or -OR ³ group.

In this case, as the monohydric alcohol to be blocked, methanol, ethanol, propanol, isopropanol, butanol, isobutanol or the like is preferred, and methanol is preferred.

From the viewpoint of controlling the compatibility with respect to deuterated cellulose, it is more preferred that both ends of the above ester-based polymer are independently -OH groups or -OC(=O)-R ¹ groups (wherein, when present) A plurality of the above R ¹ each independently represent an aliphatic group). Further, the both ends may be the same group or different groups, and from the viewpoint of ease of synthesis, they are preferably the same groups.

More preferably, the ester-based polymer has an -OH group at both ends or is blocked by acetic acid or propionic acid.

In view of the fact that the ester-based polymer is difficult to be in a solid state at a normal temperature, the operation of the cellulose-deposited cellulose film is good, and a cellulose-deposited cellulose film having excellent humidity stability and polarizing plate durability can be obtained. Both ends of the ester polymer of the present invention are preferably blocked by acetic acid to cause the two ends to become acetamidine residues (sometimes referred to as ethyl hydrazino residues).

The number average molecular weight of the above ester polymer is preferably from 500 to 2,000, more preferably from 700 to 1,500, still more preferably from 700 to 1200. The number average molecular weight of the ester polymer is preferably 500 or more from the viewpoint of enhancing optical developability. In addition, when the number average molecular weight of the ester polymer is 2,000 or less, the compatibility with the cellulose fluorene becomes high, and it is difficult to cause bleed out during film formation and during heat extension.

The number average molecular weight of the ester polymer of the present invention can be measured and evaluated by gel permeation chromatography. Further, in the case of a polyester polyol which is not terminated at the end, it may be calculated from the amount of hydroxyl groups per unit weight (hereinafter, a hydroxyl value). The hydroxyl value is the amount (mg) of potassium hydroxide required to neutralize excess acetic acid after the polyester polyol is acetylated.

Further, the ester polymer of the present invention can be used as a plasticizer.

The content of the above ester-based polymer in 100 parts by mass of the cellulose-deposited cellulose in the deuterated cellulose film of the present invention is preferably 5 parts by mass to 25 parts by mass, more preferably 8 parts by mass to 20 parts by mass, most preferably Preferably, it is 8 parts by mass to 15 parts by mass.

The dicarboxylic acid residue, the diol residue, and the type and ratio of each residue contained in the above ester-based polymer used in the present invention can be measured by a usual method using H-NMR. In general, deuterated chloroform can be used as a solvent.

The number average molecular weight of the above ester-based polymer can be measured by GPC (Gel Permeation Chromatography) by a usual method, and polystyrene can usually be used as a standard sample.

The acetic acid method described in Japanese Industrial Standard JIS K3342 (obsolete) can be used for the measurement of the hydroxyl value of the above ester polymer. When the polycondensate is a polyester polyol, the hydroxyl value is preferably from 50 to 190, more preferably from 50 to 130.

Specific examples of the above ester-based polymer are described in the following tables, but the present invention is not limited to the following specific examples.

[Table 1]

(Synthesis method of ester polymer)

The synthesis of the above ester-based polymer used in the present invention can be easily synthesized by any of the following methods: thermal melting by polyesterification reaction or transesterification reaction of a diol with a dicarboxylic acid by a conventional method The condensation method or the interfacial condensation method of the ruthenium chloride and the diol of the acid. In addition, the ester-based polymer of the present invention is described in detail in "The Theory and Application of Plasticizer" by Mr. Takashi Murai (editor) (Kyosuke Co., Ltd., first edition of the first edition on March 1, 1973) . In addition, Japanese Patent Laid-Open No. Hei 05-155809, Japanese Patent Laid-Open No. Hei 05-155810, Japanese Patent Laid-Open No. Hei No. Hei No. Hei No. Hei No. Hei No. Hei No. Hei No. Hei. Raw materials described in Japanese Laid-Open Patent Publication No. Hei. No. 2006-342227, and Japanese Patent Laid-Open Publication No. 2007-003679.

(sugar ester)

In the present invention, at least one sugar ester compound may be contained. As the sugar ester compound, it is preferred to contain an aromatic group.

The sugar ester compound is a compound obtained by ester-bonding at least one substituent (for example, a hydroxyl group or a carboxyl group) of a polysaccharide constituting the compound to at least one substituent. That is, the sugar ester compound described herein also includes a generalized sugar derivative, and for example, a compound containing a sugar residue as a structure such as gluconic acid. That is, the above-mentioned sugar ester compound also includes an ester of glucose and a carboxylic acid, and also includes an ester of gluconic acid and an alcohol.

The substituent which is substituted in the polysaccharide constituting the above sugar ester compound is preferably a hydroxyl group.

The sugar ester compound contains a structure derived from a polysaccharide constituting the sugar ester compound (hereinafter also referred to as a sugar residue). The structure of each monosaccharide of the above sugar residue is referred to as a structural unit of a sugar ester compound. The structural unit of the above sugar ester compound preferably contains a pyranose structural unit or a furanose structural unit, and more preferably all sugar residues are pyranose structural units or furanose structural units. Further, when the above sugar ester contains a polysaccharide, it is preferred to contain a pyranose structural unit or a furanose structural unit together.

The sugar residue of the above sugar ester compound may be derived from a pentose or a hexose, but is preferably derived from a hexose.

The number of the structural units contained in the above sugar ester compound is preferably from 2 to 4, more preferably from 2 to 3, particularly preferably 2. In other words, the sugar constituting the sugar ester compound is preferably a disaccharide to a tetrasaccharide, more preferably a disaccharide to a trisaccharide, and particularly preferably a disaccharide.

In the present invention, the sugar ester compound is more preferably a sugar ester compound containing two to four at least one hydroxyl group-esterified pyranose structural unit or a furanose structural unit, and more preferably two or more a saccharide esterified pyranose structural unit or a sugar ester compound of a furanose structural unit.

Examples of the monosaccharide or the saccharide containing two to four monosaccharide units include erythroglucose, threose, ribose, arabinose, xylose, lyxose, allose, and altrose. Glucose, fructose, mannose, gulose, idose, galactose, telaxose, trehalose, iso-trehalose, new trehalose, trehalose, bismuth, sugar, maltose, maltitol, Isomaltose, sucrose, kelp disaccharide, cellobiose, gentiobiose, lactose, lactosamine, lactitol, lactulose, melibiose, primrose, sucrose, sucrose, sucrose, sucrose , pine disaccharide, pod disaccharide, cellotriose, potato trisaccharide, gentian trisaccharide, isomaltotriose, isoglucosyl maltose, maltotriose, mannose triose, pine trisaccharide, pan Noose, psyllium, raffinose, eggplant trisaccharide, umbelliferous sugar, lycopene, maltotetraose, stachyose, maltopentaose, mullein, maltohexaose, xylitol, Sorbitol and the like.

Preferred are ribose, arabinose, xylose, lyxose, glucose, fructose, mannose, galactose, trehalose, maltose, cellobiose, lactose, sucrose, sucralose, xylitol, sorbitol, etc. Good arabinose, xylose, glucose, fructose, mannose, galactose, maltose, cellobiose, sucrose, especially xylose, glucose, fructose, mannose, galactose, maltose, cellobiose, sucrose, Xylitol, sorbitol.

Preferable examples of the substituent of the above-mentioned sugar ester compound include an alkyl group (preferably having 1 to 22 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably an alkyl group having 1 to 8 carbon atoms). a group such as a methyl group, an ethyl group, a propyl group, a hydroxyethyl group, a hydroxypropyl group, a 2-cyanoethyl group or a benzyl group, or an aryl group (preferably having a carbon number of 6 to 24, more preferably 6 to 6) 18, particularly preferably an aryl group of 6 to 12, such as a phenyl group, a naphthyl group, or a fluorenyl group (preferably having a carbon number of 1 to 22, more preferably a carbon number of 2 to 12, particularly preferably a carbon number of 2) a fluorenyl group of ～8, such as an ethyl group, a propyl group, a propyl group, a butyl group, a pentamidine group, a hexyl group, a octyl group, a benzamidine group, a tolylmethyl group, a phthalic acid group, etc.), an amidino group ( Preferably, the carbon number is from 1 to 22, more preferably from 2 to 12 carbon atoms, particularly preferably from 2 to 8 carbon atoms, such as formazanylamine, etidamine, and the like. a base (preferably having a carbon number of 4 to 22, more preferably a carbon number of 4 to 12, particularly preferably a carbon number of 4 to 8 quinone imine groups, such as amber quinone imine, orthophthalic acid Amine, etc.). More preferably, it is an alkyl group or a mercapto group, and more preferably a methyl group, an ethyl group, a propyl group, a butyl group (preferably, an isobutyl group), a benzamidine group, and particularly preferably an ethyl group. It is particularly preferable that at least one of the butyl groups contain only an ethyl fluorenyl group or a fluorenyl group and a butyl group.

The sugar ester compound used in the present invention includes the compounds shown below. However, the sugar ester compound which can be used in the present invention is not limited to these compounds. Further, in the following structural formulae, R independently represents an arbitrary substituent, and a plurality of R's may be the same or different.

[Table 2]

[table 3]

[Table 4]

[table 5]

In addition, as the above-mentioned sugar ester compound, Japanese Patent Laid-Open No. 2001-247717, Japanese Patent Laid-Open Publication No. 2005-515285, International Publication No. WO2007/125764, International Publication WO2009/011228, International Publication WO2009 A sugar ester compound described in Japanese Laid-Open Patent Publication No. 031464.

As a method for obtaining the above-mentioned sugar ester compound, a commercially available product can be obtained commercially from Tokyo Chemical Co., Ltd., Aldrich, or the like, or a known ester can be obtained from a commercially available carbohydrate. The synthesis is carried out by a derivatization method (for example, the method described in JP-A-8-245678).

The above sugar ester compound suitably has a number average molecular weight of preferably from 200 to 3,500, more preferably from 420 to 3,000, particularly preferably from 450 to 2,000.

The sugar ester compound is preferably contained in an amount of 2% by mass to 35% by mass, more preferably 5% by mass to 20% by mass, based on the fluorinated cellulose, and particularly preferably 10% by mass to 15% by mass. % by mass of the above sugar ester compound.

(nitrogen-containing ring compound)

The film of the present invention may contain at least one nitrogen-containing ring compound. As the nitrogen-containing cyclic compound, it is preferred to contain an aromatic group. The retardation value can be more effectively exhibited by containing a nitrogen-containing cyclic compound.

The nitrogen-containing cyclic compound is a compound having any one of pyridine, pyrimidine, triazine, and hydrazine as a nucleus, and having an alkyl group, an alkenyl group, an alkynyl group at any position at which the nucleus can be substituted. An amine group, a guanamine group (a structure in which an arbitrary fluorenyl group is bonded via a guanamine bond), an aryl group, an alkoxy group, a thioalkoxy group, an alkylthio group or an arylthio group (linked via a sulfur atom) A group having an alkyl group or an aryl group or a heterocyclic group as a substituent. However, the substituent of the parent core of the above nitrogen-containing cyclic compound may be further substituted by another substituent, and the other substituents are not particularly limited. For example, when the above-mentioned mother nucleus is substituted with an amine group, the amine group may be substituted by an alkyl group (further, the alkyl groups may be bonded to each other to form a ring) or -SO ₂ R' (where R' represents an arbitrary substituent).

In the film of the present invention, the content of the nitrogen-containing cyclic compound is preferably less than 7% by mass, more preferably from 1% by mass to 5% by mass, even more preferably from 1% by mass to 3% by mass based on the fluorinated cellulose. %.

The film of the present invention may also contain a previously known so-called retardation-developing agent as the above nitrogen-containing ring compound. By using a delayed developing agent, high retardation developability can be obtained at a low stretching ratio. On the other hand, the film of the present invention is produced by the method for producing the above-described cellulose-deposited cellulose film, and even when the delayed-developing agent is not contained, the delayed developability is good.

The retardation-developing agent is not particularly limited, and examples thereof include those having a rod-like compound or a compound having a cyclic structure such as a cycloalkane or an aromatic ring, or a compound having a non-phosphate ester-based compound. a developing compound. As the compound having a cyclic structure, a nitrogen-containing ring compound is preferred. As the rod-like compound or the nitrogen-containing ring compound, a compound having at least two aromatic rings can be preferably used as the retardation-developing agent.

Further, two or more kinds of retardation developing agents may be used in combination.

The delayed developing agent preferably has substantially no absorption in the visible region.

As the retardation-developing agent, a compound described in JP-A-2004-51648, JP-A-2007-86748, and a compound described in JP-A-2010-46834 can be used. The invention is not limited to these compounds.

As the nitrogen-containing ring compound, for example, a compound described in the specification of the European Patent Application Publication No. 0911656A2, a triazine compound described in JP-A-2003-344655, and Japanese Patent Laid-Open No. 2008- The co-triphenyl compound described in Japanese Patent Publication No. 150592 [0097] to [0108].

Further, the compounds described in [0062] to [0081] of JP-A-2012-144627 may be preferably used.

The nitrogen-containing ring compound can be synthesized by a known method such as the method described in JP-A-2003-344655, and the method described in JP-A-2005-134884.

In addition to the above-mentioned nitrogen-containing cyclic compound, a rod-like compound having a linear molecular structure can be preferably used. For example, a rod described in JP-A-2008-150592 [0110] to [0127] can be preferably used. Compound.

Specific examples of the nitrogen-containing cyclic compound are listed below, but the present invention is not limited by the following specific examples.

<Other additives>

The deuterated cellulose film used in the present invention may contain, in addition to the above, an additive which can be usually added to the cellulose-deposited film.

Examples of such additives include additives having negative intrinsic birefringence, fine particles, retardation developers, antioxidants, heat deterioration inhibitors, colorants, and ultraviolet absorbers.

As the other additives described above, the compound described in WO 2008-126535 can be preferably used.

(Inner birefringence is a negative additive)

The film of the present invention may also contain an additive having a negative intrinsic birefringence. Hereinafter, a compound having a negative intrinsic birefringence which can be used as an additive having a negative intrinsic birefringence as described above can be used.

The above-mentioned compound having a negative intrinsic birefringence means a material which exhibits a negative intrinsic birefringence in a specific direction of the film in the deuterated cellulose film. In the present specification, the term "negative intrinsic birefringence" means a property in which the birefringence is negative. In addition, whether or not it has a negative intrinsic birefringence can be known, for example, by measuring a birefringence of a film in a system to which the compound is added and a system in which the compound is not added, using a birefringence meter, and comparing the two difference.

The compound having a negative intrinsic birefringence of the present invention is not particularly limited, and a known compound or the like which exhibits a negative intrinsic birefringence can be used. For example, [0036] of JP-A-2010-46834 can be preferably used. The compound disclosed in [0092] and the like.

Examples of the compound having a negative intrinsic birefringence include a polymer having a negative intrinsic birefringence or a needle-like fine particle having a negative intrinsic birefringence (acicular fine particles containing a polymer having a negative intrinsic birefringence). Wait. Hereinafter, a polymer having negative intrinsic birefringence which can be used in the present invention will be described.

The above-mentioned polymer having a negative intrinsic birefringence refers to a polymer in which the refractive index of the light in the alignment direction becomes larger than the above alignment when light is incident on a layer formed by uniaxial alignment of the molecules. The refractive index of the light in the direction orthogonal to the direction is small.

Examples of such a polymer having a negative intrinsic birefringence include a polymer having a specific cyclic structure (a disc-shaped ring such as an aliphatic aromatic ring or a heteroaromatic ring) in a side chain (for example, polystyrene, a (meth)acrylic polymer such as poly(4-hydroxy)styrene or a styrene-based polymer such as a styrene-maleic anhydride copolymer or polyvinylpyridine or a polymethyl methacrylate; A cellulose ester-based polymer (excluding a positive birefringence), a polyester-based polymer (excluding a positive birefringence), an acrylonitrile-based polymer, an alkoxyalkylene-based polymer, or a plurality of these Meta-system, ternary system, etc.) copolymerized polymer. These polymers may be used alone or in combination of two or more. Further, in the case of a copolymer, it may be a block copolymer or a random copolymer.

Among them, a polymer having a specific cyclic structure, a (meth)acrylic polymer, and an alkoxyalkylalkyl polymer are more preferred, and polystyrene, polyhydroxystyrene, polyvinylpyridine and (Meth)acrylic polymer.

When the above-mentioned polymer having a specific cyclic structure is added, the Rth visibility of the cellulose-deposited cellulose film after film formation can be improved, and it is preferable.

As the polymer having a specific cyclic structure, a polymer having an aliphatic aromatic ring in a side chain described in JP-A-2010-46834 can be preferably used. Among them, polystyrene and poly(4-hydroxy)styrene are preferred, and a copolymer of polystyrene and poly(4-hydroxy)styrene is more preferred. The copolymerization ratio (mol ratio) of the copolymer of the above polystyrene and poly(4-hydroxy)styrene is preferably from 10/90 to 100/0, more preferably from 20/80 to 90/10.

On the other hand, as the polymer having a specific cyclic structure, a polymer having a heteroaromatic ring such as polyvinylpyridine in a side chain can also be preferably used.

When the (meth)acrylic polymer is added, the cellulose-deposited cellulose film after the film formation is excellent in transparency and extremely low in moisture permeability, and exhibits excellent performance as a protective film for a polarizing plate. The compound described in Japanese Laid-Open Patent Publication No. 2009-1696 and International Publication No. WO2008-126535 can be preferably used for the above (meth)acrylic polymer. Further, the (meth)acrylic polymer may have an aliphatic aromatic ring or a heteroaromatic ring in the side chain.

When the above compound having a negative intrinsic birefringence is a polymer having a negative intrinsic birefringence, the weight average molecular weight thereof is preferably from 500 to 100,000, more preferably from 700 to 50,000, particularly preferably from 700 to 100,000.

When the molecular weight is 500 or more, the volatilization property is good, and when the molecular weight is 100,000 or less, the compatibility with the deuterated cellulose resin is good, and therefore the film forming property of the deuterated cellulose film is also good, and both are preferable.

In the film of the present invention, it is preferable to add 0% by mass to 20% by mass of the compound having a negative intrinsic birefringence with respect to the above-mentioned deuterated cellulose, and more preferably 0% by mass to 15% by mass of the above. The compound having a negative intrinsic birefringence is particularly preferably a compound having a negative intrinsic birefringence as described above in which 0% by mass to 10% by mass is added.

On the other hand, the film of the present invention is produced by a method for producing the above-described cellulose-deposited cellulose film, and the reverse wavelength dispersion property is contained even in the case where the relatively expensive compound having negative intrinsic birefringence is not contained. Also large. Therefore, from the viewpoint of reducing the production cost, the film of the present invention preferably has a small amount of a compound having a negative intrinsic birefringence.

(microparticles)

Examples of the fine particles used in the present invention include cerium oxide, titanium oxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium citrate, calcium citrate hydrate, and the like. Aluminum citrate, magnesium citrate and calcium phosphate.

From the viewpoint of lowering the haze, the fine particles are preferably fine particles containing cerium, and particularly preferably cerium oxide.

The average particle diameter of the primary particles of the microparticles is preferably from 5 nm to 50 nm, more preferably from 7 nm to 20 nm. These fine particles are preferably mainly contained as secondary aggregates having a particle diameter of 0.05 nm to 0.3 μm.

The fine particles of cerium oxide can be used, for example, Aerosil R972, Aerosil R972V, Aerosil R974, Aerosil R812, Aerosil 200, Aerosil 200V, Aerosil 300, Aerosil R202, Aerosil OX50, Aerosil TT600, Aerosil NAX50 (above is Japan's Erosil ( The seller of the trade name of Aerosil).

As the fine particles of zirconia, for example, those sold under the trade names of Aerosil R976 and Aerosil R811 (above, manufactured by Erosil, Japan) can be used.

Examples of the polymer include an anthrone resin, a fluororesin, and an acrylic resin. It is preferably an anthrone resin, particularly preferably a three-dimensional network structure, for example, Tospearl 103, Tospearl 105, Tospearl 108, Tospearl 120, Tospearl 145, Tospearl 3120 and Tospearl 240 (above toshiba ketone (Toshiba) The seller of the trade name of Silicone).

Among these, Aerosil 200V and Aerosil R972V are particularly preferably used because the haze of the cellulose derivative film is kept low and the friction coefficient is lowered.

The content of the fine particles in the cellulose film of the present invention is preferably from 0.05% by mass to 1% by mass, particularly preferably from 0.1% by mass to 0.5% by mass. In the case of a cellulose derivative film having a multilayer structure formed by a co-casting method, it is preferred to contain the added amount of fine particles on the surface.

(antioxidant, anti-heat deterioration agent)

In the present invention, as the antioxidant and the heat-resistant deterioration agent, an antioxidant or a heat-resistant deterioration agent which is generally known can be used. In particular, a lactone-based, sulfur-based, phenol-based, double-bonded, hindered amine-based, phosphorus-based compound antioxidant, and heat-resistant deterioration agent can be preferably used. As the above-mentioned antioxidant and heat-resistant deterioration agent, the compound described in International Publication WO2008-126535 can be preferably used.

(Colorant)

In the present invention, a coloring agent can also be used. The coloring agent refers to a dye or a pigment, but in the present invention, it means an effect of changing the color tone of a liquid crystal screen to a blue hue, or adjusting a yellowness index and reducing haze. As the coloring agent, a compound described in WO 2008-126535 can be preferably used.

(peeling accelerator)

In the present invention, a release accelerator may be used, and as the release accelerator, a compound described in [0030] to [0041] of JP-A-2011-183759 may be preferably used.

(Layer structure of bismuth cellulose film)

The film of the present invention may be a single layer film or may have a laminated structure of two or more layers, but is preferably a single layer film.

(film thickness)

The film of the present invention has a film thickness of 20 μm to 60 μm. By forming such a thin bismuth cellulose film, a thin polarizing plate and a thin liquid crystal display device can be obtained. The film thickness of the film of the present invention is preferably from 30 μm to 55 μm, more preferably from 30 μm to 50 μm. When the film of the present invention is a laminated film, the range of the total film thickness of the film is in the above preferred range. The film thickness in the present invention means an average film thickness.

(film width)

The film width of the film of the present invention is preferably 1000 mm or more, more preferably 1500 mm or more, and particularly preferably 1800 mm or more.

(ΔM)

The difference between the equilibrium moisture content at 25 ° C and 80% after immersing the deuterated cellulose film of the present invention in pure water at 40 ° C for 24 hours, and the equilibrium moisture content at 25 ° C and 80% before immersion is 1.0%. Hereinafter, it is preferably 0.5% or less. By making the difference in equilibrium water content small as described above, even if water adheres, unevenness due to condensation does not occur, and appropriate display performance can be obtained. The equilibrium moisture content refers to a value measured by the Karl Fischer method.

(Re, Rth)

The retardation in the in-plane and film thickness directions at a wavelength of 590 nm of the film of the present invention satisfies the following formulas (I) and (II). Formula (I) 30 nm ≦Re(590) ≦ 90 nm (In equation (I), Re(590) represents the retardation in the in-plane direction at a wavelength of 590 nm) Formula (II) 100 nm ≦Rth(590)≦150 Nm (in equation (II), Rth(590) represents the retardation in the film thickness direction at a wavelength of 590 nm)

From the viewpoint of improving the contrast or black tone change of the liquid crystal display device, it is preferable to exhibit a retardation in such a range.

The above Re(590) is preferably from 40 nm to 90 nm, more preferably from 45 nm to 60 nm.

The above Rth (590) is preferably from 100 nm to 200 nm, more preferably from 110 nm to 130 nm.

(Rth/d)

The film of the present invention preferably satisfies the formula (III) 2.0 < Rth (590) / d ≦ 5.0. Here, d represents a film thickness (μm). By setting it as such a range, even if a bismuth cellulose film is thinned, it shows the predetermined delay. Rth(590)/d is preferably from 2.5 to 4.0, more preferably from 2.8 to 3.5.

In the present specification, Re(λ) and Rth(λ) respectively represent the in-plane retardation at the wavelength λ and the retardation in the thickness direction. In the specification of the present application, when not specifically described, the wavelength λ is set to 590 nm. Re(λ) was measured by injecting light having a wavelength of λ nm into the normal direction of the film in KOBRA 21ADH (manufactured by Oji Scientific Instruments, Inc.). Rth(λ) is calculated as a tilt axis (rotation axis) with respect to the slow axis in the plane (determined by KOBRA 21ADH) (when there is no slow axis, any direction in the film plane is set as The normal direction of the film of the rotating shaft) is incident on the light of the wavelength λ nm from the oblique direction every 10 degrees from the normal direction to 50 degrees on one side, and the above-mentioned Re(λ) of all six points is measured, and then The KOBRA 21ADH calculates Rth(λ) from the measured retardation value and the assumed value of the average refractive index and the input film thickness value. Further, the slow axis may be used as the tilt axis (rotation axis) (when there is no slow axis, any direction in the film surface is used as the rotation axis), and the delay value is measured from any two directions, and based on the value The assumed value of the average refractive index and the input film thickness value are calculated from the following formulas (A) and (B). Here, the assumed value of the average refractive index may be a value in a catalogue of a polymer handbook (JOHN WILEY & SONS, INC), various optical films. For those whose average refractive index value is unknown, the measurement can be performed using an Abbe refractometer. The values of the average refractive index of the main optical film are exemplified below: deuterated cellulose (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), polystyrene ( 1.59). Nx, ny, and nz were calculated from KOBRA 21ADH by inputting the assumed values of the average refractive indices and the film thickness. Further, Nz = (nx - nz) / (nx - ny) is calculated from the calculated nx, ny, and nz.

Here, Re (θ) represents a retardation value in a direction from the normal direction oblique angle θ, and nx, ny, and nz represent refractive indices of respective major axis directions of the refractive index ellipsoid, and d represents a film thickness. Rth=((nx+ny)/2-nz)×d (B)

In this case, the average refractive index n is required as a parameter, and a value measured by an Abbe refractometer (Abbé refractometer 2-T manufactured by Atago Co., Ltd.) is used.

(internal haze)

The internal haze of the deuterated cellulose film of the present invention is 0.05% or less.

The haze indicates the haze value (%) measured in accordance with JIS K7136.

The internal haze of the film of the present invention is a value (%) obtained by subtracting a haze measured in a state where a few drops of glycerin are dropped between two sheets of glass, from the haze value (%) as follows, and the haze The value (%) is obtained by adding a few drops of glycerin to both sides of the obtained cellulose-deposited cellulose film, and using two glass plates (microscopic slides (MICRO SLIDE GLASS) model S9213 having a thickness of 1.3 mm, MATSUNAMI) Manufactured) The value measured in the state of being clamped from both sides.

The haze of the deuterated cellulose film of the present invention is in a film which is left in an environment of 23 ° C and a relative humidity of 55% for 24 hours in a same environment using a haze meter (NDH2000, Nippon Denshoku Industries Co., Ltd.). The measurement was carried out.

The internal haze of the deuterated cellulose film of the present invention is preferably 0.035% or less, more preferably 0.03% or less, still more preferably 0.025% or less.

Generally, it is preferred that the haze is low. Further, the low total haze is not sufficient for improving the front contrast, and from the viewpoint of improving the front contrast of the liquid crystal display device, the internal haze is preferably adjusted to the above range.

[Method for producing bismuth cellulose film]

The cellulose fluorite film of the present invention can be produced according to a known method.

Further, in the present invention, there is disclosed a method for producing a cellulose-deposited film, which comprises polymerizing a deuterated cellulose, a solvent, and a compound containing an aromatic compound having a total thiol substitution degree of 2.0 to 2.55. The step of forming the solution into a film shape and the step of controlling the film to be extended so that the film thickness after stretching becomes 20 μm to 60 μm further includes a step of subjecting the stretched film to water treatment. The details of these steps are explained below.

The method for producing a deuterated cellulose film can form a film containing cellulose deuterated cellulose by a solution casting film forming method or a melt film forming method. From the viewpoint of improving the surface of the film, the method for producing a cellulose-deposited film preferably includes a step of forming a film of a film containing cellulose deuterated by a solution casting film forming method.

Hereinafter, a method of producing a cellulose-deposited cellulose film will be described by taking a case of using a solution casting film forming method as an example. However, the method for producing a cellulose-deposited cellulose film is not limited to the solution casting film forming method. Further, a known method can be used as the method for producing the above-described cellulose-deposited cellulose film by using the above-described melt film formation method.

<Polymer solution>

In the solution casting film forming method, a polymer solution (deuterated cellulose solution) containing the above-described deuterated cellulose or various additives as needed is used to form a web. In the present invention, an additive is usually formulated, and a compound containing an aromatic compound is preferably formulated as an additive. Hereinafter, a polymer solution (hereinafter, also referred to as a deuterated cellulose solution or a dope) which can be used in a solution casting film forming method will be described.

(solvent)

The deuterated cellulose used in the present invention is dissolved in a solvent to form a dope, and the dope is cast on a substrate to form a film. At this time, it is necessary to extrude or evaporate the solvent after casting, and therefore it is preferred to use a volatile solvent.

Further, the solvent is one which does not react with a reactive metal compound or a catalyst, and does not dissolve the substrate for casting. Further, two or more solvents may be used in combination.

Further, the deuterated cellulose and the reactive metal compound capable of undergoing hydrolysis polycondensation may be separately dissolved in a different solvent and then mixed.

Here, an organic solvent having good solubility to the above-described deuterated cellulose is referred to as a good solvent, and further, a main effect is exhibited in dissolution, and an organic solvent widely used therein is referred to as a main (organic). Solvent or primary (organic) solvent.

Examples of the above good solvent include ketones such as acetone, methyl ethyl ketone, cyclopentanone, and cyclohexanone, tetrahydrofuran (THF), 1,4-dioxane, and 1,3-dioxolane. And ethers such as 1,2-dimethoxyethane, methyl formate, ethyl formate, methyl acetate, ethyl acetate, amyl acetate, γ-butyrolactone, etc. Fiber, dimethylimidazolidinone, dimethylformamide, dimethylacetamide, acetonitrile, dimethyl hydrazine, cyclobutyl hydrazine, nitroethane, dichloromethane, methyl acetate And the like, preferably 1,3-dioxolane, THF, methyl ethyl ketone, acetone, methyl acetate and dichloromethane.

It is preferable that the concentrated liquid contains 1% by mass to 40% by mass of an alcohol having 1 to 4 carbon atoms in addition to the above organic solvent.

These solvents can be used as a gelling solvent which is obtained by casting a dope on a metal support, and then the solvent starts to evaporate and the ratio of the alcohol is increased to cause the net to be deuterated. a method in which a dope of a cellulose is cast on a support, and the dope film is referred to as a gelation to make a gelation solvent which is easily peeled off from the metal support, or when the solvent is used When the ratio is small, the non-chlorine-based organic solvent also has a function of promoting the dissolution of the deuterated cellulose, and also has an effect of suppressing gelation, precipitation, and viscosity increase of the reactive metal compound.

Examples of the alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, isopropanol, n-butanol, second butanol, third butanol, and propylene glycol monomethyl ether.

Among these, ethanol is preferred in terms of excellent stability of the dope, a relatively low boiling point, good dryness, and no toxicity. These organic solvents have no solubility to deuterated cellulose alone and are called poor solvents.

In the present invention, the deuterated cellulose constituting the deuterated cellulose film contains a hydroxyl group, a ketone or the like, and has a hydrogen bond property, thereby reducing the peeling load on the cast support. The amount of the alcohol is preferably from 5% by mass to 30% by mass, more preferably from 7% by mass to 25% by mass, even more preferably from 10% by mass to 20% by mass, based on the total solvent.

By adjusting the alcohol content, the reproducibility of Re or Rth of the deuterated cellulose film produced by the above-described method for producing a deuterated cellulose film can be easily adjusted. Specifically, by increasing the alcohol content or setting the drying temperature (heat treatment temperature) before stretching in the method for producing a cellulose-deuterated film to be described later to be relatively low, the reach range of Re or Rth can be further increased. .

Further, in the present invention, the presence of a small amount of water is also effective for increasing the viscosity of the solution or the film strength of the wet film state at the time of drying, or for increasing the strength of the dope of the roll method, for example, 0.1% by mass based on the entire solution. ～5% by mass of water, more preferably 0.1% by mass to 3% by mass of water, and particularly preferably 0.2% by mass to 2% by mass of water.

An example of a combination of organic solvents which can be preferably used as a solvent of the polymer solution in the present invention is exemplified in Japanese Patent Laid-Open Publication No. 2009-262551.

Further, a non-halogen-based organic solvent may be used as a main solvent as needed, and is described in detail in the Inventor's Association Technical Publication (publication number 2001-1745, issued on March 15, 2001, the Invention Association).

The concentration of deuterated cellulose in the polymer solution of the present invention is preferably from 5% by mass to 40% by mass, more preferably from 10% by mass to 30% by mass, most preferably from 15% by mass to 30% by mass.

The concentration of the deuterated cellulose can be adjusted so that the concentration of the deuterated cellulose in the solvent is at a predetermined concentration. Further, after a solution having a low concentration (for example, 4% by mass to 14% by mass) is prepared in advance, it may be concentrated by evaporating a solvent or the like. Further, it is also possible to perform dilution after preparing a high concentration solution in advance. In addition, the concentration of deuterated cellulose can also be lowered by adding an additive.

The period in which the additive is added can be appropriately determined depending on the kind of the additive.

As a solvent which satisfies such conditions and dissolves deuterated cellulose which is a preferable polymer compound at a high concentration, an optimum solvent is a mixed solvent of a ratio of dichloromethane:ethanol of 95:5 to 80:20. Alternatively, a mixed solvent of methyl acetate:ethanol of 60:40 to 95:5 may also be preferably used.

<Details of each step>

(1) Dissolution step

The dissolving step is a step of dissolving the deuterated cellulose and the additive in a dissolution vessel, and dissolving the solution in an organic solvent mainly for a good solvent for deuterated cellulose to form a dope, or The step of mixing the additive solution in the cellulose solution to form a dope.

In the dissolution of deuterated cellulose, a method for dissolving at normal pressure can be dissolved at a boiling point or lower of the main solvent, and a method of dissolving at a boiling point or higher of the main solvent to perform dissolution, such as a Japanese patent A method of dissolving by a cooling and dissolving method as described in Japanese Laid-Open Patent Publication No. Hei 9-95549, or Japanese Patent Laid-Open No. Hei 9-95538, for example, Japanese Patent Laid-Open No. Hei 11-21379 Various methods of dissolving such as a method of dissolving at a high pressure as described in the publication, but particularly preferably a method of performing pressure by boiling at a boiling point or higher of the main solvent.

The concentration of the deuterated cellulose in the dope is preferably from 10% by mass to 35% by mass. The additive is added to the dope during or after the dissolution to dissolve and disperse, and then filtered with a filter material, defoamed, and sent to the next step by a liquid feeding pump.

(2) Casting step

The casting step is a step of feeding the dope into a pressurizing mold by a liquid feeding pump (for example, a pressurized quantitative gear pump), and then applying a slit from the pressure die slit to the infinitely conveyed ring. Casting is performed at a casting position on a metal support such as a metal belt (for example, a stainless steel belt) or a rotating metal drum.

It is preferably a press mold which can adjust the slit shape of the metal port portion of the mold and which is easy to make the film thickness uniform. The press mold may be a coat mold or a T-shaped mold, and any mold may be preferably used. The surface of the metal support becomes a mirror surface. In order to increase the film forming speed, two or more pressurizing dies may be provided on the metal support, and the amount of the concentrated liquid may be divided to form a plurality of layers. Alternatively, it is preferable to obtain a film having a laminated structure by a co-casting method in which a plurality of dopes are simultaneously cast.

(3) Solvent evaporation step

The solvent evaporation step is to heat the mesh on the metal support (the state before the finished product of the cellulose-deposited cellulose film, and still contains a lot of solvent), and evaporate the solvent to the mesh. The step of peeling off the support.

When the solvent is evaporated, there is a method of blowing air from the mesh side and/or a method of transferring heat from the back surface of the metal support by a liquid, a method of transferring heat from the front surface by radiant heat, etc., but heat transfer of the back surface liquid The drying efficiency of the method is good and preferred. Further, a method of combining the methods is also preferred. In the case of heat transfer of the back liquid, it is preferred to heat the boiling point of the main solvent of the organic solvent used in the dope or the organic solvent having the lowest boiling point.

(4) Stripping step

The stripping step is a step of stripping the web from which the solvent has evaporated at the peeling position on the metal support. The stripped web is sent to the next step. In addition, if the amount of residual solvent (the following formula) of the net at the time of peeling is too large, peeling is difficult, and conversely, if it is excessively dried on the metal support and then peeled off, part of the net will be Peeling off the middle.

Here, as a method of raising the film forming speed (the peeling is performed in a period in which the amount of residual solvent is as much as possible, thereby increasing the film forming speed), there is gel-casting. For example, there is a method in which a poor solvent for deuterated cellulose is added to the dope, a method of gelation after casting the dope, and a method of reducing the temperature of the metal support to gel. Gelation is performed on the metal support to increase the strength of the film at the time of peeling, thereby speeding up the peeling and increasing the film forming speed.

The amount of the residual solvent in the peeling of the mesh on the metal support is preferably in the range of 5 to 150% by mass based on the strength of the drying conditions, the length of the metal support, etc., but the amount of residual solvent is more When the peeling is performed at the time point, the amount of residual solvent at the time of peeling is determined by the combination of economic speed and quality. In the present invention, the temperature at the peeling position on the metal support is preferably from -50 ° C to 40 ° C, more preferably from 10 ° C to 40 ° C, and most preferably from 15 ° C to 30 ° C.

Moreover, it is preferable that the residual solvent amount of the net at the peeling position is 10% by mass to 150% by mass, and more preferably 10% by mass to 120% by mass.

The amount of residual solvent can be expressed by the following formula. Residual solvent amount (% by mass) = [(M-N) / N] × 100

Here, M is the mass at any time point of the net, and N is the mass at 110 ° C when the mass is M for 3 hours.

(5) drying or heat treatment step, extension step

The method for producing a cellulose-deposited film of the present invention is characterized in that the film after peeling is subjected to an extending step. Further, from the viewpoint of improving the optical developability of the obtained cellulose halide film with respect to the film thickness, it is preferred to carry out the above-described stretching step at a temperature of from Tg to 20 ° C to Tg ° C. Further, Tg represents the glass transition temperature (unit: ° C) of the cellulose-deposited cellulose film of the present invention, and means that tan δ is exhibited when the dynamic viscoelasticity tan δ of the cellulose-desulfated film is 0% when the residual volatile component is measured. The temperature of the peak.

Preferably, after the peeling step, a drying device that transports the net alternately through a plurality of rolls arranged in the drying device, and/or both ends of the net are held by the jig and transported while being stretched The tenter device is used to dry the net.

In the method for producing a cellulose-deposited film, the web may be subjected to heat treatment before the stretching, or may not be subjected to heat treatment.

Further, the drying or heat treatment time is preferably 30 minutes or shorter, more preferably 20 minutes or shorter, and particularly preferably about 10 minutes.

The means of drying and heat treatment usually blow hot air on both sides of the net, but there are also means for contacting the microwave instead of the wind for heating. The temperature, the amount of air, and the time may vary depending on the solvent to be used, and may be appropriately selected depending on the type and combination of the solvent to be used.

In the method for producing a cellulose-deposited film, the film may be stretched in any direction (hereinafter, also referred to as a "longitudinal direction") and a direction orthogonal to the film transport direction (hereinafter, also referred to as a lateral direction), but From the standpoint of rendering the desired delay appearing, it is preferred to extend at least in the lateral direction. The extension can be implemented in one stage, and can also be implemented in multiple stages.

The stretching ratio at the time of extending in the film transport direction is preferably 0 to 20%, more preferably 0 to 15%, particularly preferably 0 to 10%. The stretching ratio (elongation) of the deuterated cellulose web at the time of extension can be achieved by the difference in the peripheral speed between the metal support speed and the stripping speed (stripping roll). For example, when a device having two nip rolls is used, the bismuth cellulose film can be transported in the transport direction (longitudinal direction) by making the nip roller on the outlet side rotate faster than the nip roller on the inlet side. Extension is preferably carried out. By performing such extension, the visibility of the delay can be adjusted.

In addition, the "stretching magnification (%)" as used herein means the one obtained by the following formula. Extension ratio (%) = 100 × {(length after extension) - (length before extension)} / length before extension

The stretching ratio at the time of extending in a direction orthogonal to the film conveying direction is preferably more than 20%, more preferably more than 20%, and is 60% or less, particularly preferably 25% to 55%, and particularly preferably 25%. ~50%.

Further, in the present invention, it is preferable to use a tenter to perform stretching as a method of extending in a direction orthogonal to the film transport direction.

In the above method for producing a cellulose-deposited film, the elongation temperature is preferably from Tg to 20 ° C to Tg.

Further, in a more preferred embodiment of the method for producing a cellulose-deuterated film, cellulose acetate having a low degree of substitution with a vinylidene group (especially cellulose acetate having a degree of substitution of an ethylene group of 2.0 to 2.5) is used. The elongation is carried out within the range of the above extension temperature, whereby the haze caused by the above extension can also be suppressed. Although not limited to any theory, it is expected that if cellulose acetate having a low ethyl mercapto degree of substitution is used as the above-described deuterated cellulose, the cellulose acetate having a low ethylation degree substitution and the above-mentioned aliphatic dicarboxylic acid residue Since the ester-based polymer of the base and the aliphatic diol residue has a high refractive index difference, scattering in the film is less likely to occur. Further, as the above-mentioned ester-based polymer, compatibility with cellulose acetate having a low ethylation group substitution degree is selected, whereby the haze can be further suppressed. As a result, the internal haze of the film obtained by the above-described method for producing a cellulose-deposited cellulose film can be easily controlled to the above preferred range.

In the method for producing a film of the present invention, in order to suppress the occurrence of cracks and to prevent the internal haze from appearing, it is preferred to carry out the stretching at Tg - 10 ° C to Tg + 40 ° C. More preferably, it is Tg-5 ° C - Tg + 30 ° C, and particularly preferably Tg - Tg + 20 °C. By setting the extension temperature to the above temperature range, the internal haze rise can be suppressed.

Further, drying may be performed after the self-expansion step and before the wet heat treatment step described later. When the drying step is performed before the wet heat treatment step to be described later, the drying temperature, the drying air volume, and the drying time may be different depending on the solvent to be used, and the drying conditions may be appropriately selected in accordance with the type and combination of the solvent to be used. . In the present invention, from the viewpoint of improving the front contrast when the film assembly of the present invention is incorporated in a liquid crystal display device, it is preferred that the drying temperature before the wet heat treatment step after the stretching step is lower than the stretching temperature of the stretching step. .

(6) Water treatment steps

In the present invention, the extended deuterated cellulose film is subjected to water treatment. As the water treatment, it is preferred to be immersed in water after stretching. The temperature of the water is preferably from 25 ° C to 85 ° C, more preferably from 35 ° C to 80 ° C. The immersion time in water is preferably 5 seconds or longer, more preferably 5 seconds to 12 hours. By setting it as 5 second or more, the effect of this invention can exhibit more effectively, and it is set as 12 hours or less, and productivity improves. In addition, when the temperature of the water to be immersed is increased, the effect of the present invention tends to be obtained even if the immersion time is short. However, if the temperature is excessively increased, wrinkles tend to occur more frequently during transportation. Further, by setting the water treatment temperature to 85 ° C or lower, display unevenness due to dew condensation can be suppressed exceptionally.

In the present invention, the elongation in the transport direction of the film during the water treatment is preferably 1% or less, and more preferably the elongation in the transport direction of the film during the water treatment is 0.5% or less. Make adjustments.

The water used for the impregnation may be substantially water. The term "substantially water" means a water containing 60% by mass or more, and may contain, in addition to water, an organic solvent, a plasticizer, a surfactant, and the like described below. As a preferable organic solvent, a water-soluble organic solvent having a carbon number of 1 to 10 can be mentioned. However, in the present invention, the water to be immersed is more preferably 90% by mass or more, more preferably 95% by mass or more, and most preferably pure water. The water used in the following description is not limited to pure water as long as it is substantially water.

(7) Drying step

The water-treated deuterated cellulose film can be directly cooled to approximately room temperature, or the amount of contact gas molecules remaining in the film can be adjusted and then transferred to the dry region. When transporting to a dry area, the bismuth cellulose film conveyed by the roll group or the bismuth cellulose film conveyed by the tenter while being sandwiched at both ends is blown with hot air or warm air or a gas having a low gas concentration. The method, the method of irradiating infrared rays, the method of contacting with a heated roll, etc. are preferable, but it is a method of blowing the wind of a hot air, a warm air, or a low gas density.

(8) Reeling

The coiler for taking up the obtained film can use a coiler which is generally used, and can be wound by a winding method such as a constant tension method, a constant torque method, a taper tension method, or an internal stress fixed program tension control method. take. The optical film obtained in the above manner preferably has a slow axis direction of the film of ±2 degrees, more preferably ±1 degree with respect to the winding direction (longitudinal direction of the film). Alternatively, it is preferable that the slow axis direction of the film is ±2 degrees with respect to the direction perpendicular to the winding direction (the width direction of the film), and more preferably within ±1 degree. It is particularly preferable that the slow axis direction of the film is within ±0.1 degrees with respect to the winding direction (length direction of the film). Alternatively, it is preferred that the slow axis direction of the film is within ±0.1 degrees with respect to the width direction of the film.

It is preferred that the film obtained by the above method has a length of from 100 m to 10,000 m per roll, more preferably from 500 m to 7,000 m, and still more preferably from 1,000 m to 6000 m. The width of the film is preferably from 0.5 m to 5.0 m, more preferably from 1.0 m to 3.0 m, and still more preferably from 1.0 m to 2.5 m. Preferably, at least one end is provided with a embossing when the winding is performed, and the width of the knurling is preferably from 3 mm to 50 mm, more preferably from 5 mm to 30 mm, and the height is preferably from 0.5 μm to 500 μm, more preferably 1 Mm ~ 200 μm. It can be single-sided or double-sided.

The film of the present invention is particularly suitable for use in large-screen liquid crystal display devices. When used as an optical compensation film for a liquid crystal display device for large screens, for example, it is preferable to form a film having a film width of 1470 mm or more. Further, the optical compensation film of the present invention includes not only a film which is cut into a film form which can be directly incorporated into a liquid crystal display device, but also a form in which a strip shape is formed by continuous production and wound into a roll shape. membrane. In the latter state, the optical compensation film is stored and transported in this state, and when it is actually incorporated in a liquid crystal display device or bonded to a polarizer or the like, it is cut into a desired size and used. In addition, after bonding to a polarizing plate or the like including a polyvinyl alcohol film or the like which is formed into a strip shape in the form of a strip, the liquid crystal display device is actually assembled, and is cut into a desired size and used. One aspect of the optical compensation film wound in a roll shape is a form in which a roll having a roll length of 2,500 m or more is wound.

The mesh obtained in the above manner can be taken up to obtain a cellulose oxide film as a final product.

In the method for producing the above-described cellulose-deposited cellulose film, it is preferable to produce it in a range of a preferable film thickness of the above-described deuterated cellulose film from the viewpoint of production cost or optical characteristics.

The film thickness may be adjusted so that the solid content concentration contained in the dope, the slit gap of the metal port of the mold, the extrusion pressure from the mold, the metal support speed, and the like may be adjusted so as to have a desired thickness.

<Polarizing plate>

The deuterated cellulose film of the present invention functions as a retardation film, and is preferably assembled by a protective film as a polarizing plate.

That is, the polarizing plate of the present invention comprises a polarizer, and at least one sheet of the cellulose fluorite film of the present invention is contained on at least one side of the polarizer. Hereinafter, the polarizing plate of the present invention will be described.

Like the film of the present invention, the form of the polarizing plate of the present invention includes not only a polarizing plate which is cut into a film form which can be directly incorporated into a liquid crystal display device, but also a strip which is formed into a continuous strip by continuous production. A polarizing plate wound in a roll form (for example, a roll having a roll length of 2500 m or more or 3900 m or more). For the large-screen liquid crystal display device, as described above, it is preferable to set the width of the polarizing plate to 1470 mm or more.

In the polarizing plate of the present invention, the film thickness of the polarizer is preferably from 3 μm to 20 μm, more preferably from 5 μm to 20 μm.

In the polarizing plate of the present invention, at least one side of the polarizing plate protective film contains the deuterated cellulose film of the present invention, and as the other polarizing plate protective film, a known deuterated cellulose film can be used. The thickness of the polarizing plate protective film on the other side is preferably from 10 μm to 40 μm, more preferably from 20 μm to 40 μm.

Further, the total thickness of the polarizing plate of the present invention is preferably from 40 μm to 100 μm, more preferably from 50 μm to 100 μm, particularly preferably from 65 μm to 95 μm. The term "total thickness" herein is intended to include a polarizer, a polarizer protective film bonded to both sides of the polarizer, and an adhesive layer for bonding the polarizer protective film.

The specific configuration of the polarizing plate of the present invention is not particularly limited, and a known configuration can be employed. For example, the configuration described in FIG. 6 of JP-A-2008-262161 can be employed.

<Liquid crystal display device>

The liquid crystal display device of the present invention comprises at least one sheet of the polarizing plate of the present invention. The liquid crystal display device of the present invention remarkably improves the contrast in the front direction and the hue change in the viewing direction by including the polarizing plate of the present invention comprising the deuterated cellulose film of the present invention.

In the liquid crystal display device of the present invention, the thickness of the glass constituting the liquid crystal cell is preferably from 50 μm to 500 μm. By using such a glass, the thickness of the liquid crystal display device can be made thin.

The liquid crystal display device of the present invention is preferably an In-Plane Switching (IPS), Optically Compensated Bend (OCB) or VA mode liquid crystal display device having a liquid crystal cell and a configuration A liquid crystal display device of a pair of polarizing plates on both sides of the liquid crystal cell, characterized in that at least one of the polarizing plates is a polarizing plate 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 employed. For example, an example of the configuration described in FIG. 1 can be employed. Further, the configuration described in Fig. 2 of Japanese Laid-Open Patent Publication No. 2008-262161 can also be preferably used. Example

Hereinafter, the present invention will be more specifically described by way of examples. The materials, the amounts, the ratios, the processing contents, the processing procedures, and the like shown in the following examples can be appropriately changed without departing from the gist of the invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.

In the present invention, the measurement of the film properties is carried out by the following measurement method.

(optical properties)

Re and Rth were measured at a wavelength of 590 nm by the above method using KOBRA 21ADH (manufactured by Oji Scientific Instruments Co., Ltd.).

(internal haze)

The value (%) obtained by subtracting the haze value obtained by dropping a few drops of glycerin into the two sheets of glass is set as the internal haze, and the haze value is a few drops. Glycerin was added dropwise to both sides of the obtained bismuth cellulose film sample of 40 mm × 80 mm, and was sandwiched by two glass plates (MICRO SLIDE GLASS model S9213, manufactured by Matsuo) having a thickness of 1.3 mm from both sides. The obtained value was measured by a haze meter (HGM-2DP, Suga Test Instruments) in accordance with JIS K-6714 at 25 ° C and a relative humidity of 60%. The results are shown in the following table.

(Production of bismuth cellulose film)

(1) Preparation of concentrated liquid

The following composition was placed in a mixing tank, stirred to dissolve each component, and further heated to 90 ° C for about 10 minutes, and then subjected to a filter paper having an average pore diameter of 34 μm and a sintered metal filter having an average pore diameter of 10 μm. filter. ———————————————————————————— 醯化cellulose solution —————————————————— ――――――――――― The total amount of deuterated cellulose described in the following table is 100.0 parts by mass. The additive described below is the amount of the following: The amount of the component described in the following table: mass parts of the additive B described below The unit of measurement described in the table: parts by mass KV37 (peeling accelerator) The unit of quantity described in the following table: parts by mass of dichloromethane 403.0 parts by mass of methanol 60.2 parts by mass ———————————— ——————————————

[Table 6]

Additive A is a reaction in which AA (adipic acid) is reacted with EG (ethylene glycol) and the end is blocked by OAc (Ac is an ethylene group).

The additive B is a compound which reacts TPA (terephthalic acid), SA (succinic acid), EG (ethylene glycol), PG (1,2-propanediol), and terminates the terminal by Ac.

Additive 2:

It is synthesized according to the description of Japanese Patent Laid-Open Publication No. 2012-31313.

Additive 3:

The additive 4 (ester oligomer) was synthesized in the following manner.

The oligomer mixture was prepared by reacting PG and TPA in such a manner as to have the following composition. After stirring, mBA was added dropwise, and the prepared oligomer was blocked.

mBA-(PG-TPA)n-PG-mBA: where n is 0-2.

mBA represents methyl benzoate, PG represents propylene glycol, TPA represents terephthalic acid, and BA represents a benzoate.

Peeling accelerator: K-37V (Poem K-37V, manufactured by Riken Vitamin)

<1-2> matting agent dispersion

Then, the following composition containing the deuterated cellulose solution prepared by the above method was placed in a dispersing machine to prepare a matting agent dispersion. ———————————————————————————— Matting agent dispersion —————————————————— ——————————·Materials (Aerosil R972) 0.2 parts by mass · 72.4 parts by mass of methylene chloride · 10.8 parts by mass of methanol · 10.3 parts by mass of cellulose solution ———————— ————————————————————

100 parts by mass of the above-described deuterated cellulose solution and inorganic fine particles were mixed with a matting agent dispersion in an amount of 0.02 parts by mass based on the deuterated cellulose resin to prepare a dope for film formation.

(2) Casting

The above dope was cast using a belt casting machine. Furthermore, the belt is made of SUS.

(3) Drying

After the web (film) obtained by casting was peeled off, the tenter apparatus which carried out the conveyance of the both ends of the net by the clamp was carried out, and it dried in this tenter apparatus for 20 minutes. Further, the drying temperature as referred to herein means the film surface temperature of the film.

(4) Extension

The obtained web (film) was peeled off from the tape, and then held in a jig, and in a state where the amount of residual solvent with respect to the mass of the entire film was 30% by mass, under the condition of uniaxially extending at the fixed end The film was stretched in a direction (lateral direction) orthogonal to the film transport direction by a tenter using the stretching temperature and the stretching ratio described in the following table. At this time, the cast film thickness was adjusted such that the film thickness after the extension became the film thickness (unit: μm) described in the table.

(5) Water immersion method

The film was immersed in the water tank at the temperature and time shown in the following table with respect to the extended film. The immersion was performed so that the elongation in the conveyance direction of the film was 1% or less. After water immersion, water droplets on the surface of the film were removed and dried with a warm air of 100 °C.

Thereafter, the film was wound up after cooling to room temperature, and in order to judge the manufacturing suitability, a minimum of 24 rolls having a roll width of 1280 mm and a roll length of 2600 mm were produced under the above conditions. A sample of length 1 m (width 1280 mm) was cut at intervals of 100 m for one of the 24 rolls manufactured continuously.

The cellulose-deposited cellulose film 2 to the cellulose-deposited film 11 were produced in the same manner as described above except that the degree of substitution of the deuterated cellulose, the composition of the dope solution, and the production conditions were changed as shown in the following Table.

(Measurement of equilibrium moisture content)

The equilibrium moisture content was measured by the Karl Fischer method as follows.

(1) Weigh the sample (0.9 m × 4.5 cm, 2 pieces). When the sample is wet, quickly wipe off the surface moisture. Immediately after sampling, it was added to a glass bottle with a sanding plug and transported to the moisture meter, and was measured within 3 minutes after sampling.

(2) Measurement was carried out using the following moisture meter. · Vaporizer: Using VA-05 type manufactured by Mitsubishi Chemical, the water in the sample was volatilized at 150 ° C and introduced into the moisture meter. Moisture meter: The measurement was performed using a Karl Fischer moisture meter (Model CA-03 manufactured by Mitsubishi Chemical Corporation).

(3) The moisture content (μg) indicated by the moisture meter is set to W, the amount of the sample to be weighed is set to F (mg), and the equilibrium moisture content is calculated according to the following formula. Equilibrium water content (%) = 100 × (W / 1000F) = 0.1 × (W / F)

(Equilibrium water content change (ΔM) before and after water immersion)

The obtained film was cut into 10 cm × 10 cm, and immersed in pure water at 40 ° C for 24 hours. Thereafter, the surface water was wiped off and dried with a warm air of 100 ° C for 5 minutes, and humidity-conditioned at 25 ° C and 80% relative humidity for 24 hours, and then the membrane equilibrium moisture content was measured by the Karl Fischer method described above. Further, the equilibrium moisture content at 25 ° C and 80% after water immersion was compared with the equilibrium moisture content at 25 ° C and 80% before water immersion, and the equilibrium moisture content change was calculated.

(Production of polarizing plate sample)

The surface of the deuterated cellulose film of each of the examples and the comparative examples produced above was subjected to alkali saponification treatment. The mixture was immersed in a 1.5 N aqueous sodium hydroxide solution at 55 ° C for 2 minutes, then washed in a water bath at room temperature, and neutralized at 30 ° C using 0.1 N sulfuric acid. The mixture was again washed in a water bath at room temperature, and further dried by a warm air of 100 °C.

Then, the rolled polyvinyl alcohol film was continuously extended to 5 times in an aqueous iodine solution, and then dried to obtain a polarizer. The 3% aqueous solution of polyvinyl alcohol (PVA-117H manufactured by Kuraray) was used as an adhesive, and the first polarizing plate protective film and the second polarizing plate of each of the examples and the comparative examples in which the alkali saponification treatment was performed were prepared. The protective film is bonded to the polarizer by sandwiching the saponified surface of the film so as to be on the side of the polarizer, and the first polarizing plate protective film of each of the examples and the comparative examples is bonded in this order. Polarizing plate, polarizing plate of the second polarizing plate protective film. At this time, the MD direction of the first polarizer protective film and the second polarizer protective film is attached so as to be parallel to the absorption axis of the polarizer.

[Table 7] In the table, Ac represents an ethyl group and Pr represents a propyl group.

The film of Comparative Example 3 could not be peeled off from the support.

(Production of liquid crystal display device)

A polarizing plate and a retardation plate on the front and back of a VA mode liquid crystal television (LC-46LV3, manufactured by Sharp (SHARP) Co., Ltd.) were peeled off and used as a liquid crystal cell. As shown in Fig. 1 (the front side is the front side), the outer protective film (not shown), the polarizer 11, and the films 14 of the respective examples and comparative examples described in the following table (the back side 醯) were used. The cellulose film (the cellulose film), the liquid crystal cell 13 (the VA liquid crystal cell), the film 15 of the respective examples and comparative examples described in the following table (the front side fluoridation film), the polarizer 12, and the outer protective film ( The liquid crystal display device 1 to the liquid crystal display device 11 of each of the examples and the comparative examples were produced by laminating in order. At this time, the upper and lower polarizing plates are bonded to each other so that the absorption axes thereof are orthogonal to each other.

(front contrast evaluation)

Using a measuring device (BM5A, manufactured by TOPCON), the brightness values of the black display and the white display in the front direction of the panel were measured in a dark room, and the front contrast (white brightness/black brightness) was calculated.

The observed contrast was evaluated according to the following criteria. A: 6500 or more. B: 5000 or more, less than 6500 C: less than 5000

(Evaluation criteria for light leakage)

In the liquid crystal display device produced, the sensory evaluation of light leakage and color shift in the oblique direction when the black display was performed in the dark room was evaluated by the following criteria. A: No light leakage was observed in all polar directions and azimuth directions. B: Light leakage was slightly observed in a region where the polar angle was greater than 60 degrees. C: Light leakage was slightly observed in a region where the polar angle was less than 60 degrees.

(conformation unevenness evaluation)

500 μL of pure water was added to the surface of the polarizing plate on the viewing side of the liquid crystal display device, and Saran Wrap (registered trademark) (made by Asahi Kasei Home Products Co., Ltd.) was cut out to 10 cm × 10 cm and tape the four sides. The liquid crystal display device was continuously lit for 24 hours, then the Saran Wrap was removed and the water droplets on the surface were wiped off. Thereafter, after the liquid crystal display device was further turned on for 24 hours, the unevenness in black display was evaluated from the front side and the tilt direction.

[Front unevenness] A: I can't see it at all B: Slightly seen C: Obviously see

[Slanted unevenness] A: Can't see at all B: Slightly seen C: Obviously seen

[Table 8]

According to the table, the liquid crystal display device of the liquid crystal display device 1 to the liquid crystal display device 6 using the deuterated cellulose film of the present invention is excellent in front contrast, light leakage in the oblique direction, and unevenness in condensation. On the other hand, it is understood that any of the liquid crystal display device 7 to the liquid crystal display device 11 using the film of the comparative example has poor front surface contrast, light leakage in the oblique direction, and unevenness in condensation.

11‧‧‧ polarizer
12‧‧‧ polarizer
13‧‧‧Liquid Crystal Unit
14, 15‧ ‧ film

Fig. 1 is a schematic cross-sectional view showing an example of a liquid crystal display device of the present invention.

11‧‧‧ polarizer

12‧‧‧ polarizer

13‧‧‧Liquid Crystal Unit

14, 15‧ ‧ film

Claims (7)

A method for producing a cellulose-deposited film, comprising: forming a polymer solution containing deuterated cellulose, a solvent, and an additive having a total thiol substitution degree of 2.0 to 2.55 into a film, and extending The step of controlling the film to be stretched so as to have a film thickness of 20 μm to 60 μm; and further comprising the step of subjecting the film stretched to the above to water treatment. The method for producing a cellulose-deposited cellulose film according to the first aspect of the invention, wherein the step of performing the water treatment is a step of immersing the deuterated cellulose in water at 25 to 85 ° C for 5 seconds or more, and further comprising The film elongation in the transport direction during the water treatment is adjusted to be 1% or less. The method for producing a deuterated cellulose film according to claim 1, wherein the deuterated cellulose film has a film thickness of 20 μm to 60 μm and contains a deuterated fiber having a total thiol substitution degree of 2.0 to 2.55. And additives, and satisfy the following formula (I) to formula (V): Formula (I) 30 nm≦Re(590)≦90 nm Formula (II) 100 nm≦Rth(590)≦150 nm Formula (III) 2.0≦Rth(590)/d≦5.0 Equation (IV) Internal haze ≦0.05% Formula (V) ΔM≦1.0% Where Re(590) represents the retardation (nm) in the in-plane direction at a wavelength of 590 nm, Rth (590) represents a retardation (nm) in the film thickness direction at a wavelength of 590 nm, d represents a film thickness (μm), and ΔM represents a cadmium film which is immersed in pure water at 40 ° C for 24 hours. The equilibrium moisture content at 25 ° C and 80% obtained by the Fisher method was different from the equilibrium moisture content at 25 ° C and 80% obtained by the Karl Fischer method before impregnation. The method for producing a deuterated cellulose film according to claim 3, wherein the additive contains a compound containing an aromatic compound. The method for producing a cellulose-deposited cellulose film according to the third aspect of the invention, wherein the cellulose-degraded cellulose film contains at least one selected from the group consisting of a sugar ester compound, a nitrogen-containing cyclic compound, and an ester-based polymer as the above-mentioned inclusion Aromatic compound. The method for producing a bismuth cellulose film according to the third aspect of the invention, wherein the bismuth cellulose film has a thickness of 30 μm to 50 μm, a total thiol substitution degree of 2.4 to 2.55, and Re(590) is 40 nm to 90 nm, Rth (590) is 110 nm to 130 nm, internal haze is 0.03% or less, and ΔM is 0.5% or less. The method for producing a bismuth cellulose film according to the third aspect of the invention, wherein the bismuth cellulose film has a thickness of 30 μm to 50 μm, a total thiol substitution degree of 2.4 to 2.55, and Re(590) is 40 nm to 90 nm, Rth (590) is 110 nm to 130 nm, internal haze is 0.03% or less, ΔM is 0.5% or less, and is selected from the group consisting of a sugar ester compound, a nitrogen-containing ring compound, and an ester polymer. At least one of them is the above-mentioned aromatic-containing compound.