KR20220152397A - Laminated films, polarizers and liquid crystal displays - Google Patents

Abstract

The laminated film of the present invention includes a substrate and an optical function layer, the substrate includes a cellulose acylate having an acyl group substitution of 2.6 to 3.0 and a sugar ester in which 70 to 100% of the hydroxy groups are substituted with acyl groups, The slope obtained from the out-of-plane retardation at a wavelength of 650 nm and a wavelength of 450 nm is within a range of 0.040 to 0.055, the optical function layer contains a polymer containing fumaric acid ester polymerized units at a ratio of 90 mol% or more, and fumaric acid ester polymerized units 80 to 100% of the ester portion is isopropyl ester, and the value of the ratio of the out-of-plane phase difference between the wavelength of 450 nm and the wavelength of 550 nm of the laminated film is within the range of 1.1 to 1.9.

Description

Laminated films, polarizers and liquid crystal displays

The present invention relates to a laminated film, a polarizing plate and a liquid crystal display device. More specifically, the present invention is a retardation film having a fumaric acid ester-based resin layer, which has good interlayer adhesion and can ensure good visibility in a liquid crystal display device using the same, and a laminated film provided with the laminated film It relates to a polarizing plate and a liquid crystal display.

BACKGROUND OF THE INVENTION [0002] Liquid crystal display devices are widely used in society and are used as important devices, from televisions to personal computers and mobile phones. In recent years, various optical compensation films have been used to improve display characteristics of liquid crystal display devices, thereby expanding a viewing angle, improving color tone, and improving contrast. Among them, as a retardation film having a negative refractive index, a film made of a fumaric acid ester-based resin or containing a fumaric acid ester-based resin layer has been proposed (see Patent Document 1, for example).

However, in a liquid crystal display device comprising a fumaric acid ester-based resin or a retardation film obtained by laminating a fumaric acid ester-based resin layer on a base material on the liquid crystal panel side of a polarizer, color unevenness when viewing the display device from an angle is a cause. It was found that there was a problem in visibility, that there was a color difference when viewed from the left and right, and that peeling between layers occurred in the retardation film in which a fumarate ester-based resin layer was laminated on a base material.

Japanese Patent No. 5245109

The present invention has been made in view of the above problems and circumstances, and the problem to be solved is to provide a phase difference film having a fumaric acid ester-based resin layer, which has good interlayer adhesion and can ensure good visibility in a liquid crystal display device using the same. It is to provide a laminated film and a polarizing plate using the laminated film. Moreover, it is providing the liquid crystal display device which can ensure favorable visibility by using this laminated|multilayer film.

In order to solve the above problems, the present inventors, in the process of examining the cause of the above problems, used a combination of a specific cellulose acylate and a sugar ester as the constituent material of the substrate, and measured out-of-plane retardation with light having a wavelength of 650 nm of the substrate From R650 and out-of-plane retardation R450 measured with light having a wavelength of 450 nm, a value T (slope of out-of-plane retardation in the wavelength range of 450 to 650 nm) obtained based on a specific formula is defined as a specific range, and the optics laminated on the base material About the functional layer, most of the ester moiety is a polymer substantially composed of polymerized units of fumaric acid esters, which are isopropyl esters, and the out-of-plane retardation Rth450 measured with light having a wavelength of 450 nm in a laminated film containing these substrates and an optical functional layer. It was found that, when the value of the ratio Rth450/Rth550 of the out-of-plane retardation Rth550 measured with light having a wavelength of 550 nm is within a specific range, a laminated film having good interlayer adhesion and ensuring good visibility in a liquid crystal display device using the same can be obtained. out to the present invention.

That is, the said subject concerning this invention is solved by the following means.

1. A laminated film comprising a substrate and an optical function layer,

The base material contains a cellulose acylate having an acyl group substitution degree in the range of 2.6 to 3.0, and a sugar ester in which hydrogen atoms in 70 to 100% of the hydroxy groups are substituted with acyl groups,

For the above substrate, the value T obtained based on the following formula (1) from the out-of-plane retardation R650 measured with light with a wavelength of 650 nm and the out-of-plane retardation R450 measured with light with a wavelength of 450 nm is in the range of 0.040 to 0.055,

Equation (1) T=(R650-R450)/(650-450)

The optical function layer contains a polymer containing fumaric acid ester polymerized units in an amount of 90 mol% or more with respect to all polymerized units, and 80 to 100% of the ester portion of the fumaric acid ester polymerized units is isopropyl ester,

The value of the ratio Rth450 / Rth550 of the out-of-plane retardation Rth450 measured with light with a wavelength of 450 nm and the out-of-plane retardation Rth550 measured with light with a wavelength of 550 nm with respect to the laminated film is within the range of 1.1 to 1.9.

2. The laminated film according to claim 1, wherein the out-of-plane retardation Rth550 of the laminated film measured with light having a wavelength of 550 nm is within the range of -30 to -15 nm.

3. The polarizing plate formed by laminating|stacking the laminated|multilayer film of Claim 1 or 2, and a polarizer.

4. A liquid crystal display device provided with the polarizing plate according to claim 3.

According to the above means of the present invention, in the retardation film having a fumaric acid ester-based resin layer, interlayer adhesion is good, and a laminated film capable of securing good visibility in a liquid crystal display device using the same, and a polarizing plate using the laminated film can provide. Moreover, the liquid crystal display device which can ensure favorable visibility can be provided by using this laminated|multilayer film.

Although the expression mechanism or action mechanism of the effects of the present invention has not been clarified, it is estimated as follows.

In a liquid crystal display device provided with a polarizing plate in which a retardation film having a fumaric acid ester-based resin layer is combined with a polarizer on a viewing side of a liquid crystal panel, light passing through the polarizer and the liquid crystal panel from a backlight is transmitted to the retardation film of the polarizing plate as optical light. It was estimated that the compensation caused interference with internal reflection or surface reflection light, and color unevenness occurred when the liquid crystal display was viewed from an angle. Then, it was thought that color unevenness could be suppressed by controlling the wavelength dispersion of the out-of-plane retardation of the retardation film (hereinafter, the out-of-plane retardation of the retardation film is expressed as "Rth").

Therefore, by combining the fumaric acid ester-based resin layer and the substrate, the ratio value Rth450/Rth550 of the wavelength dispersion of Rth between the out-of-plane retardation Rth450 measured with light with a wavelength of 450 nm and the out-of-plane retardation Rth550 measured with light with a wavelength of 550 nm is 1.1 to 1.9, it was found that the problem of color unevenness when viewed from an oblique angle can be solved.

Then, in order to adjust the wavelength dispersion (Rth450/Rth550) of Rth to the above range, the out-of-plane retardation in the base material combined with the fumaric acid ester-based resin layer (hereinafter, the out-of-plane retardation of the base material is denoted by "R") is described below. Adjusted to the composition of. Specifically, as a constituent material of the substrate, a combination of cellulose acylate having an acyl group substitution degree in the range of 2.6 to 3.0 and sugar ester in which hydrogen atoms are substituted with acyl groups in 70 to 100% of the hydroxy groups, wavelength 650 nm From the out-of-plane retardation R650 measured with light of , and the out-of-plane retardation R450 measured with light having a wavelength of 450 nm, the value T obtained based on the above formula (1) was set to be within the range of 0.040 to 0.055.

Further, the adhesion between the fumaric acid ester-based resin layer and the base material is determined by setting the ratio of isopropyl ester in the ester portion to 80% or more in the polymerization unit of the fumaric acid ester in the fumaric acid ester-based resin, and in the sugar ester on the base material side. This could be achieved by setting the ratio of ester-substituted hydroxy groups to 70% or more. It is thought that this is because the permeability and interaction between the fumaric acid ester-based resin layer and the base material are increased by the above configuration.

1 is a cross-sectional view showing an example of a laminated film of the present invention.
Figure 2 is a cross-sectional view showing an example of the polarizing plate of the present invention
3 is a plan view of an example of a liquid crystal display device of the present invention;
Fig. 4 is a cross-sectional view taken along line XX of the liquid crystal display device shown in Fig. 3;

The laminated film of the present invention is a laminated film comprising a base material and an optical function layer, wherein the base material is a cellulose acylate having an acyl group substitution degree in the range of 2.6 to 3.0, and hydrogen atoms in 70 to 100% of the hydroxy groups. A value T obtained based on the above formula (1) from the out-of-plane retardation R650 measured with light having a wavelength of 650 nm and the out-of-plane retardation R450 measured with light having a wavelength of 450 nm with respect to the substrate containing a sugar ester substituted with an acyl group. is within the range of 0.040 to 0.055, the optical function layer contains a polymer containing polymerized units of fumaric acid ester in an amount of 90 mol% or more with respect to all polymerized units, and the ester portion of the polymerized units of fumaric acid ester is 80 to 80%. 100% is isopropyl ester, and the value of the ratio Rth450/Rth550 of the out-of-plane retardation Rth450 measured with light with a wavelength of 450 nm and the out-of-plane retardation Rth550 measured with light with a wavelength of 550 nm with respect to the laminated film is within the range of 1.1 to 1.9 characterized by This feature is a technical feature common to each of the following embodiments.

As an embodiment of the present invention, it is preferable that the out-of-plane retardation Rth550 measured with light having a wavelength of 550 nm with respect to the laminated film is within the range of -30 to -15 nm from the viewpoint of effect expression of the present invention.

The polarizing plate of the present invention is characterized in that the laminated film of the present invention and the polarizer are laminated. The liquid crystal display device of the present invention is characterized by including the polarizing plate of the present invention.

Hereinafter, detailed explanation is given about the form and aspect for implementing this invention, its component, and this invention. In addition, in this application, "to" is used by the meaning which includes the numerical value described before and after that as a lower limit value and an upper limit value.

[Overview of the laminated film of the present invention]

The laminated film of the present invention is a laminated film comprising a substrate and an optical function layer, and the substrate satisfies the following (1-1) and (1-2), and the optical function layer satisfies the following (2), The laminated film is characterized by satisfying the following (3).

(1-1) The base material contains a cellulose acylate having an acyl group substitution degree in the range of 2.6 to 3.0, and a sugar ester in which hydrogen atoms in 70 to 100% of the hydroxy groups are substituted with acyl groups.

(1-2) For the above substrate, the value T obtained based on the following formula (1) from the out-of-plane retardation R650 measured with light with a wavelength of 650 nm and the out-of-plane retardation R450 measured with light with a wavelength of 450 nm is 0.040 to 0.055 are within range.

Equation (1) T=(R650-R450)/(650-450)

In addition, the value T obtained based on the above formula (1) is a value representing the slope in the wavelength range of 450 to 650 nm in the graph showing the relationship between the measured wavelength and the out-of-plane retardation for the base material. Hereinafter, the value T obtained based on the above formula (1) from the out-of-plane retardation R650 measured with light having a wavelength of 650 nm and the out-of-plane retardation R450 measured with light having a wavelength of 450 nm is also referred to as "out-of-plane retardation slope T".

(2) The optical function layer contains a polymer containing fumaric acid ester polymerized units in an amount of 90 mol% or more with respect to all polymerized units, and 80 to 100% of the ester portion of the fumaric acid ester polymerized units is isopropyl ester. to be.

(3) The value Rth450/Rth550 of the ratio of the out-of-plane retardation Rth450 measured with light having a wavelength of 450 nm and the out-of-plane retardation Rth550 measured with light having a wavelength of 550 nm for the laminated film is within the range of 1.1 to 1.9.

The laminated film of the present invention is a laminated film containing a substrate and an optical function layer. The laminated film of the present invention may contain layers other than the substrate and the optical function layer within a range not impairing the effects of the present invention. 1 is a cross-sectional view showing an example of a laminated film of the present invention. The laminated film 10 shown in FIG. 1 has the structure which has the optical function layer 2 on one main surface of the film-like base material 1.

The laminated film 10 of the present invention may have an adhesive layer between the substrate 1 and the optical function layer 2, for example. The base material 1 may be composed of one layer (single layer) or may be composed of a plurality of layers, but it is preferably a single layer in terms of less display unevenness and possible thinning. Hereinafter, the constituent elements of the laminated film of the present invention will be described in detail.

(write)

The base material is a cellulose acylate having an acyl group substitution degree in the range of 2.6 to 3.0 (hereinafter also referred to as "cellulose acylate (A)"), and a sugar ester in which hydrogen atoms in 70 to 100% of the hydroxy groups are substituted with acyl groups (hereinafter, also referred to as "sugar ester (B)") is included. The base material may contain other components other than the cellulose acylate (A) and the sugar ester (B), if necessary, within a range not impairing the effects of the present invention.

<Cellulose acylate (A)>

The substrate contains cellulose acylate (A). Cellulose acylate (A) is preferably contained as a main component in the base material. In addition, a main component means that the content rate of the cellulose acylate (A) in the said base material is 50 mass % or more. The content of the cellulose acylate (A) in the substrate is preferably 55% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more. The upper limit of the content of cellulose acylate (A) in the base material is the remaining amount after excluding components other than cellulose acylate (A), preferably about 99% by mass, and more preferably 90% by mass.

Cellulose acylate is a compound in which the hydrogen atom of the hydroxyl group of cellulose is substituted with an acyl group. The degree of substitution is a value indicating the average number of hydroxy groups of three hydroxyl groups per β-glucose residue, which is a structural unit of cellulose, is substituted.

The acyl group in the cellulose acylate (A) is not particularly limited as long as it is an acyl group represented by R-C(=O)-(R is a monovalent hydrocarbon group). As the acyl group in cellulose acylate (A), for example, R is preferably an aliphatic hydrocarbon group having 1 to 5 carbon atoms, R is methyl group, acetyl group, R is ethyl group, propionyl group, or R is propyl group. A butyryl group is preferred.

The number of acyl groups in the cellulose acylate (A) may be one or two or more. The number of acyl groups in the cellulose acylate (A) is preferably 1 type, and it is preferable that the 1 type is an acetyl group. The substitution degree of the acyl group in cellulose acylate (A) can be measured according to ASTM-D817-96.

The acyl group substitution degree in the cellulose acylate (A) is 2.6 to 3.0, preferably 2.8 to 3.0. Cellulose acylate is manufactured, for example, by the method mentioned later. In the cellulose acylate obtained in this way, the cellulose acylate (A) may be a mixture of two or more cellulose acylates having different degrees of acyl group substitution and adjusted to 2.6 to 3.0, preferably 2.8 to 3.0.

The weight average molecular weight (Mw) of the cellulose acylate (A) is preferably within the range of 80000 to 300000, more preferably within the range of 120000 to 250000, from the viewpoint of maintaining the mechanical strength during stretching of the substrate. If it is within the above range, it is easy to control the retardation (phase difference) by stretching at the time of film formation of the base material. Thereby, it is easy to satisfy the condition of (1-2) in the base material.

The number average molecular weight (Mn) of the cellulose acylate (A) is preferably in the range of 30000 to 150000, since the obtained base material has high mechanical strength. Cellulose acylates having a number average molecular weight of 40000 to 100000 are also preferably used.

The value of the ratio (Mw/Mn) of the weight average molecular weight (Mw) and number average molecular weight (Mn) of the cellulose acylate (A) is preferably in the range of 1.4 to 3.0.

The weight average molecular weight (Mw) and number average molecular weight (Mn) of the cellulose acylate (A) can be measured using, for example, gel permeation chromatography (GPC). Measurement conditions are as follows.

Solvent: Methylene chloride

Column: Shodex K806, K805, K803G (three products manufactured by Showa Denko Co., Ltd. are connected and used)

Column temperature: 25°C

Sample concentration: 0.1% by mass

Detector: RI Model 504 (manufactured by GL Science)

Pump: L6000 (manufactured by Hitachi Seisakusho Co., Ltd.)

Flow rate: 1.0ml/min

Calibration curve: standard polystyrene STK standard polystyrene (manufactured by Tosoh Co., Ltd.) A calibration curve by 13 samples of Mw = 1000000 to 500 was used. 13 samples are used at substantially equal intervals.

The raw cellulose of the cellulose acylate (A) used in the present invention may be wood pulp or cotton linter, and the wood pulp may be either coniferous or broad-leaved, but coniferous is more preferable. In terms of peelability during film formation, a cotton linter is preferably used. Cellulose acylates made from these may be appropriately mixed or used alone.

For example, the ratio of cellulose acylate derived from cotton linter: cellulose acylate derived from wood pulp (softwood): cellulose acylate derived from wood pulp (hardwood) is 100:0:0, 90:10:0, 85:15:0 , 50:50:0, 20:80:0, 10:90:0, 0:100:0, 0:0:100, 80:10:10, 85:0:15, 40:30:30. can

Cellulose acylate (A) according to the present invention can be produced by a known method. In general, cellulose as a raw material is mixed with a predetermined organic acid (acetic acid, propionic acid, etc.), an acid anhydride (acetic anhydride, propionic acid anhydride, etc.), and a catalyst (sulfuric acid, etc.) to esterify the cellulose, resulting in cellulose triesters. Let the reaction proceed until In triesters, three hydroxyl groups of glucose units are substituted with acyl groups of organic acids. When two kinds of organic acids are used at the same time, a mixed ester type cellulose acylate such as cellulose acetate propionate or cellulose acetate butyrate can be produced.

Subsequently, a cellulose acylate (A) having a desired acyl group substitution degree (2.6 to 3.0) is synthesized by hydrolyzing the cellulose triester as necessary. Thereafter, cellulose acylate (A) is completed through steps such as filtration, precipitation, washing with water, dehydration, and drying.

Cellulose acylate (A) according to the present invention has a pH of 6 to 7 when 1 g is added to 20 ml of pure water (electric conductivity of 0.1 µS/cm or less, pH 6.8) and stirred at 25 ° C. for 1 hr in a nitrogen atmosphere. range, and it is preferable that the electrical conductivity is in the range of 1 to 100 μS/cm.

Cellulose acylate (A) according to the present invention can be specifically synthesized with reference to the method described in Japanese Unexamined Patent Publication No. 10-45804.

<Sugar ester (B)>

The base material relating to the laminated film of the present invention contains a sugar ester (B) other than the cellulose acylate (A).

The sugar moiety in the sugar ester (B) according to the present invention is preferably a residue of a sugar having 1 to 12 of at least one pyranose ring or furanose ring. That is, the sugar ester (B) is preferably a compound obtained by esterification of a sugar having 1 to 12 of at least one of a pyranose ring or a furanose ring. The sugar to be esterified may be a monosaccharide or a polysaccharide having 2 to 12 linked sugar structures.

The sugar ester (B) is a sugar ester in which hydrogen atoms in 70 to 100% of the hydroxyl groups of the sugar are substituted with acyl groups. In other words, the sugar ester (B) is a compound in which at least 70% of the OH groups of the raw sugar are esterified. Hereinafter, in the sugar ester (B), the ratio in which the hydrogen atoms of the hydroxy groups in the raw material sugar are substituted with acyl groups, that is, the ratio in which the OH groups are esterified is referred to as "esterification rate".

The esterification rate of the sugar ester (B) is preferably 75% or more of the OH groups present in the pyranose ring or furanose ring, and more preferably 100%. When the esterification rate in the sugar ester (B) is 70% or more, good adhesion is obtained between the substrate and the optical function layer laminated on the substrate.

The content of the sugar ester (B) in the description of the present invention is preferably 1 to 30 parts by mass, more preferably 5 to 20 parts by mass, based on 100 parts by mass of the cellulose acylate (A). When the content ratio of the sugar ester (B) is within the above range, the retardation value in the base material is controlled and the condition (1-2) is easily satisfied.

Examples of the sugar of the raw material in the sugar ester (B) include glucose, galactose, mannose, fructose, xylose, or arabinose, lactose, sucrose, nistose, 1F-fructosylnistose, stachyose, maltitol, lactitol, lactulose, cellobiose, maltose, cellotriose, maltotriose, raffinose, and kestose; and the like. Moreover, gentiobiose, gentiotriose, gentiotetraose, xylotriose, galactosylsucrose, etc. are also contained in the example of the sugar of the raw material in sugar ester (B). The sugar of the raw material in the sugar ester (B) preferably contains both a pyranose ring and a furanose ring.

Preferred examples of the sugar of the raw material in the sugar ester (B) are glucose, sucrose, kestose, nistose, 1F-fructosylnistose, stachyose, etc., glucose and sucrose are preferred, more preferably is sucrose.

In the sugar ester (B), 70 to 100% of the hydrogen atoms of the OH groups of the raw sugar are substituted with acyl groups. The acyl group is not particularly limited as long as it is an acyl group represented by R-C(=O)-(R is a monovalent hydrocarbon group). R may be an aliphatic hydrocarbon group, an alicyclic hydrocarbon group or an aromatic hydrocarbon group.

The sugar ester (B) is, for example, ester with a monocarboxylic acid represented by R-C(=O)-OH (R is the same as above) in order to introduce the acyl group into the sugar exemplified above. It is a compound compound. The monocarboxylic acid for esterification is not particularly limited, and known aliphatic monocarboxylic acids, alicyclic monocarboxylic acids, aromatic monocarboxylic acids and the like can be used. Monocarboxylic acid may be used individually by 1 type, and may use 2 or more types together.

Preferred examples of the aliphatic monocarboxylic acid include acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecane Silic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachic acid, behenic acid, lignoceric acid, cerotic acid, heptaco Saturated fatty acids such as acidic acid, montanic acid, melissic acid, and laceric acid, and unsaturated fatty acids such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid, and octenoic acid are included.

Preferred examples of the alicyclic monocarboxylic acid include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid, and derivatives thereof.

Preferable examples of the aromatic monocarboxylic acid include aromatic monocarboxylic acids having an alkyl group or an alkoxy group introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, cinnamic acid, benzilic acid, biphenylcarboxylic acid, naphthalenecarboxylic acid, Aromatic monocarboxylic acids having two or more benzene rings, such as tetralincarboxylic acid, and derivatives thereof are included.

As an aromatic monocarboxylic acid, more specifically, xylylic acid, hemelitic acid, mesitylene acid, prenitylic acid, γ-isodurylic acid, durylic acid, mesitoic acid, α-isodurylic acid, cuminic acid, α- Toluic acid, hydroatropic acid, atropic acid, hydrocinnamic acid, salicylic acid, o-anisic acid, m-anisic acid, p-anisic acid, creosotic acid, o-homosalicylic acid, m-homosalicylic acid, p-homosalicylic acid , o-Pyrocatechuic acid, β-resorcylic acid, vanillic acid, isovanilic acid, veratric acid, o-veratric acid, gallic acid, asaronic acid, mandelic acid, homoanisic acid, homovanillic acid, homoveratric acid , o-homoveratric acid, phthalonic acid, p-coumaric acid; Benzoic acid is particularly preferred.

As the sugar ester (B) in the present invention, an ester compound of an oligosaccharide may also be used as long as the above esterification rate is satisfied. Oligosaccharides are produced by acting enzymes such as amylase on starch, sucrose, etc., for example. Examples of preferred oligosaccharides include maltooligosaccharide, isomaltooligosaccharide, fructooligosaccharide, galactooligosaccharide, and xylooligosaccharide.

Examples of the sugar ester (B) include esterified products of compounds obtained by condensing 1 to 12 of at least one pyranose ring or furanose ring having a structure represented by the following general formula (B). .

R ¹¹ to R ¹⁵ and R ²¹ to R ²⁵ in the general formula (B) represent an acyl group having 2 to 22 carbon atoms or a hydrogen atom. m and n are each an integer of 0 to 12, and m+n is an integer of 1 to 12; In the general formula (B), the ratio of the acyl group having 2 to 22 carbon atoms to the total number of R ¹¹ to R ¹⁵ and R ²¹ to R ²⁵ is 70 to 100%.

As the acyl group, the structure is represented by R ²⁶ -C(=O)-(R ²⁶ is a saturated aliphatic hydrocarbon group having 1 to 21 carbon atoms, or a phenyl group or benzyl group which may have a substituent having 6 to 20 carbon atoms) It is preferably an acyl group. Among these, an acetyl group in which R ²⁶ is a methyl group and a benzoyl group in which R ²⁶ is a phenyl group are preferable, and an acetyl group is particularly preferable.

As a substituent which a phenyl group or a benzyl group has, an alkyl group, an alkenyl group, an alkoxyl group, and a phenyl group are mentioned, for example, Moreover, these alkyl groups, alkenyl groups, and a phenyl group may have a substituent. Oligosaccharide ester compounds can also be produced by the same method as other sugar esters.

Although the specific example of sugar ester (B) concerning this invention is given below, this invention is not limited to this. In the compounds whose structures are shown below, in compounds in which "average degree of substitution" is not shown under the substituent (acyl group), 100% of the hydrogen atoms of the OH group of the sugar are substituted with the substituent. As the sugar ester (B), a sugar ester (B) in which 70% or more of the hydrogen atoms of the OH groups in the following compounds are substituted with acyl groups is also preferable. For example, in compound 1, a compound in which 30% or less of R ₁ is a hydrogen atom is also a category of sugar ester (B) and is preferable.

In the compounds whose structures are shown below, when "average degree of substitution" is shown below the substituent (acyl group), it indicates that the hydrogen atom of the OH group of the sugar is substituted with the substituent (acyl group) at the degree of substitution. For example, in compound 3, the average degree of substitution is 7.0, indicating that 7 out of 8 R ₃ are substituted with benzoyl groups and the remaining 1 is a hydrogen atom. In this case, the esterification rate is 7/8 = 87.5%. On the other hand, in compound 12, the average degree of substitution is 8.0, indicating that all 8 R ₁₂ are substituted with benzoyl groups. In this case, the esterification rate is 8/8 = 100%.

The sugar ester (B) according to the present invention is obtained by reacting an acylating agent (also referred to as an esterifying agent) with the sugar, for example, a sugar having 1 to 12 at least one of a pyranose ring or a furanose ring. it is possible to manufacture Examples of the acylating agent include acid halides or acid anhydrides of various monocarboxylic acids described above. Specifically, when the acyl group is an acetyl group, acetyl chloride, acetic anhydride, and the like are exemplified, and when the acyl group is a benzoyl group, benzyl chloride, benzoic anhydride, and the like are exemplified.

In the esterification of sugars, the degree of substitution and the esterification rate of the sugar esters obtained have slightly different distributions among molecules. The degree of substitution of the sugar ester and the distribution of the esterification rate are determined by adjusting the amount of the acylating agent, the timing of addition, and the esterification reaction time. Sugar esters (B) having a desired esterification rate (70 to 100%) can be prepared by mixing sugar esters having different degrees of substitution and esterification rates, or by mixing purely isolated compounds having different degrees of substitution and esterification rates. . Below, the reaction of esterifying sucrose with benzoic anhydride is exemplified, and the adjustment of the esterification rate is demonstrated concretely.

(Synthesis Example: Synthesis of sugar ester (B) according to the present invention)

The esterification reaction of sucrose with benzoic anhydride was performed as follows. That is, 34.2 g (0.1 mol) of sucrose (sucrose), 135.6 g (0.6 mol) of benzoic acid anhydride, and 284.8 g (3.6 mol) of pyridine were added to a 4-column equipped with a stirring device, a reflux condenser, a thermometer and a nitrogen gas inlet tube. After introducing, the temperature was raised while bubbling nitrogen gas from the nitrogen gas inlet tube under stirring, and an esterification reaction was performed at 70°C for 5 hours.

Next, the pressure inside the colben is reduced to 4×10 ² Pa or less, excess pyridine is distilled off at 60° C., the pressure inside the colben is reduced to 1.3×10 Pa or less, and the temperature is raised to 120° C. to obtain benzoic acid anhydride and the produced benzoic acid Most of it was distilled off. And next, 1 L of toluene and 300 g of 0.5 mass % sodium carbonate aqueous solution were added, and it left still after stirring at 50 degreeC for 30 minutes, and the toluene layer was fractionated. Finally, 100 g of water was added to the fractionated toluene layer, and after washing with water for 30 minutes at room temperature, the toluene layer was fractionated, and toluene was distilled off at 60° C. under reduced pressure (4 × 10 ² Pa or less) to obtain compound A- A sugar ester 1 was obtained which was a mixture of 1, A-2, A-3, A-4 and A-5.

When the obtained mixture was analyzed by high-performance liquid chromatography mass spectrometry (HPLC-MS), A-1 was 1.2 mass%, A-2 was 13.2 mass%, A-3 was 14.2 mass%, and A-4 was 35.4 mass%. , A-5 and the like were 40.0% by mass. The average degree of substitution was 5.2, and the esterification rate was 65%.

Further, A-5 and the like mean all components having a degree of substitution of 4 or less, that is, a mixture of compounds having degrees of substitution of 4, 3, 2, and 1. In addition, the average degree of substitution and esterification rate were calculated as substitution degree 4 for A-5 and the like. The measurement conditions of HPLC-MS are as follows.

<Measurement conditions of HPLC-MS>

1) LC part

Apparatus: Nippon Bunco Co., Ltd. column oven (JASCO CO-965), detector (JASCO UV-970-240nm), pump (JASCO PU-980), degasser (JASCO DG-980-50)

Column: Inertsil ODS-3 particle size 5 μm 4.6 × 250 mm (manufactured by GL Science Co., Ltd.)

Column temperature: 40°C

Flow Rate: 1ml/min

Mobile phase: THF (1% acetic acid): H ₂ O (50:50)

Injection volume: 3 μl

2) MS Division

Device: LCQ DECA (manufactured by Thermo Quest Co., Ltd.)

Ionization method: electro spray ionization (ESI) method

Spray Voltage: 5kV

Capillary Temperature: 180℃

Vaporizer temperature: 450℃

Similarly, 158.2 g (0.70 mol), 146.9 g (0.65 mol), 135.6 g (0.60 mol), and 124.3 g (0.55 mol) of benzoic acid anhydride were reacted with pyridine of the sugar mole, and the composition and average substitution as shown in Table I Also, sugar ester 2, sugar ester 3 and sugar ester 4 were obtained, respectively, in the esterification ratio.

Sugar esters 1 to 4 as a mixture of sugar esters having different degrees of substitution thus obtained are purified by column chromatography using silica gel to obtain 100% purity A-1, A-2, A-3 and A-4, respectively. and A-5, etc. are obtained.

In the present invention, for example, sugar ester (sugar ester 2 in Table I) having a desired esterification rate (70 to 100%) is selected from sugar esters 1 to 4 prepared in this way, and sugar ester (B) do it with Alternatively, sugar ester (B) adjusted to an esterification rate of 70 to 100% is obtained by adding A-1 to A-5 isolated above in combination.

(other ingredients)

The base material relating to the laminated film of the present invention may contain other components other than the cellulose acylate (A) and the sugar ester (B), if necessary, within a range not impairing the effects of the present invention. Examples of other components include plasticizers, ultraviolet absorbers, antioxidants, fine particles (mat agent), surfactants, polymer electrolytes, conductive complexes, antistatic agents, antiblocking agents, and lubricants.

<Plasticizer>

A known plasticizer having a molecular weight of 10000 or less can also be used in the substrate according to the present invention within a range that does not impair the effects of the present invention. The plasticizer is not particularly limited, but is preferably selected from polyhydric carboxylic acid ester plasticizers, glycolate plasticizers, phthalic acid ester plasticizers, fatty acid ester plasticizers, and polyhydric alcohol ester plasticizers.

The polyhydric alcohol ester is an ester (alcohol ester) of a dihydric or higher aliphatic polyhydric alcohol and a monocarboxylic acid, and is preferably a divalent to 20-hydric aliphatic polyhydric alcohol ester. The polyhydric alcohol ester preferably has an aromatic ring or a cycloalkyl ring in the molecule.

Preferred examples of the aliphatic polyhydric alcohol include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, and 1,2-butanediol. , 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, trimethylolpropane, pentaerythritol, trimethylolethane, xylitol and the like are included. Especially, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, xylitol, etc. are preferable.

The monocarboxylic acid is not particularly limited, and may be an aliphatic monocarboxylic acid, an alicyclic monocarboxylic acid, or an aromatic monocarboxylic acid. An alicyclic monocarboxylic acid or an aromatic monocarboxylic acid is preferable in order to improve the moisture permeability of the film and make it difficult to volatilize. 1 type may be sufficient as a monocarboxylic acid, and 2 or more types of mixtures may be sufficient as it. In addition, all of the OH groups contained in the aliphatic polyhydric alcohol may be esterified, or a part may be left as OH groups.

It is preferable that an aliphatic monocarboxylic acid is a C1-C32 linear or branched fatty acid. The number of carbon atoms of the aliphatic monocarboxylic acid is more preferably 1 to 20, still more preferably 1 to 10. Examples of aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanoic acid, undecylic acid, lauric acid, Tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachic acid, behenic acid, lignoceric acid, cerotic acid, heptacosanoic acid, montanic acid, mellitus Saturated fatty acids, such as axeric acid and lacteric acid; and unsaturated fatty acids such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid. Especially, in order to improve compatibility with cellulose acetate, acetic acid or a mixture of acetic acid and another monocarboxylic acid is preferable.

Examples of the alicyclic monocarboxylic acid include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, and cyclooctanecarboxylic acid.

Examples of aromatic monocarboxylic acids include benzoic acid; What introduced 1 to 3 alkyl groups or alkoxy groups (for example, a methoxy group and an ethoxy group) to the benzene ring of benzoic acid (for example, toluic acid etc.); Aromatic monocarboxylic acids having two or more benzene rings (for example, biphenylcarboxylic acid, naphthalenecarboxylic acid, tetralincarboxylic acid, etc.) are included, and benzoic acid is preferred.

The polyhydric carboxylic acid ester is an ester of a divalent or higher, preferably 2 to 20, polyhydric carboxylic acid and an alcohol. It is preferable that polyhydric carboxylic acid is 2-20 valent aliphatic polyhydric carboxylic acid, 3-20 valent aromatic polyhydric carboxylic acid, or 3-20 valent alicyclic polyhydric carboxylic acid.

Examples of polyhydric carboxylic acids include trivalent or higher aromatic polyhydric carboxylic acids such as trimellitic acid, trimesic acid, and pyromellitic acid, or derivatives thereof, succinic acid, adipic acid, azelaic acid, sebacic acid, oxalic acid, fumaric acid, and maleic acid. acids, aliphatic polyhydric carboxylic acids such as tetrahydrophthalic acid, tartaric acid, tartronic acid, malic acid, and oxypolycarboxylic acids such as citric acid; and the like, in order to suppress volatilization from the film, an oxypolycarboxylic acid is preferable.

Examples of the alcohol include linear or branched aliphatic saturated alcohols, linear or branched aliphatic unsaturated alcohols, alicyclic alcohols or aromatic alcohols. The number of carbon atoms in the aliphatic saturated alcohol or aliphatic unsaturated alcohol is preferably 1 to 32, more preferably 1 to 20, still more preferably 1 to 10. Cyclopentanol, cyclohexanol, etc. are contained in the example of alicyclic alcohol. Benzyl alcohol, cinnamyl alcohol, etc. are contained in the example of aromatic alcohol.

The molecular weight of the polyhydric carboxylic acid ester is not particularly limited, but is preferably in the range of 300 to 1000, and more preferably in the range of 350 to 750. As for the molecular weight of a polyhydric carboxylic acid ester type plasticizer, the larger one is preferable from a viewpoint of suppressing bleed-out; From the viewpoint of moisture permeability and compatibility with cellulose acetate, the smaller one is preferable.

Examples of polyhydric carboxylic acid esters include triethyl citrate, tributyl citrate, acetyl triethyl citrate (ATEC), acetyl tributyl citrate (ATBC), benzoyl tributyl citrate, acetyl triphenyl citrate, acetyl Tribenzyl citrate, dibutyl tartrate, diacetyl dibutyl tartrate, tributyl trimellitate, tetrabutyl pyromellitate and the like are included.

Polyhydric carboxylic acid ester may be phthalic acid ester. Examples of phthalic acid esters include diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, dicyclohexyl terephthalate, and the like. included

Examples of glycolates include alkyl phthalylalkyl glycolates. Examples of alkyl phthalylalkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl ethyl Glycolate, Ethylphthalylmethylglycolate, Ethylphthalylpropylglycolate, Methylphthalylbutylglycolate, Ethylphthalylbutylglycolate, Butylphthalylmethylglycolate, Butylphthalylethylglycolate, Propylphthalylbutylglycol rate, butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl methyl glycolate, octyl phthalyl ethyl glycolate, etc. are included, preferably ethyl phthalyl ethyl glycolate to be.

Ester plasticizers include fatty acid esters, citric acid esters and phosphoric acid esters.

Examples of the fatty acid ester include butyl oleate, methylacetyl ricinoleate, and dibutyl sebacate. Examples of citric acid esters include acetyl trimethyl citrate, acetyl triethyl citrate, and acetyl tributyl citrate. Examples of the phosphoric acid ester include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, biphenyl diphenyl phosphate, trioctyl phosphate, tributyl phosphate and the like, preferably triphenyl phosphate. .

A plasticizer may be used individually by 1 type, and may use 2 or more types together. The content of the plasticizer is preferably in the range of 1 to 20 parts by mass, and more preferably in the range of 1.5 to 15 parts by mass with respect to 100 parts by mass of the cellulose acylate (A). When the content of the plasticizer is within the above range, the effect of imparting plasticity can be exhibited, and the resistance to exudation of the plasticizer from the substrate is also excellent.

<Ultraviolet absorber>

When the base material according to the present invention is used as a retardation film to be disposed on the surface side (visible side) of a liquid crystal display device as a laminated film, it is preferable to contain an ultraviolet absorber from the viewpoint of improving light resistance. The ultraviolet absorber aims to improve light resistance by absorbing ultraviolet rays of 400 nm or less, and in particular, the transmittance at a wavelength of 370 nm is preferably 10% or less, more preferably 5% or less, still more preferably 2% or less. to be.

The ultraviolet absorbers preferably used in the present invention are benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, and triazine-based ultraviolet absorbers, and particularly preferably benzotriazole-based ultraviolet absorbers and benzophenone-based ultraviolet absorbers.

For example, 5-chloro-2-(3,5-di-sec-butyl-2-hydroxylphenyl)-2H-benzotriazole, (2-2H-benzotriazol-2-yl)-6- (straight-chain and branched-chain dodecyl)-4-methylphenol, 2-hydroxy-4-benzyloxy benzophenone, 2,4-benzyloxy benzophenone, etc.; also Tinuvin 109, Tinuvin 171, Tinuvin 234, There are Tinuvin types, such as Tinuvin 326, Tinuvin 327, Tinuvin 328, and Tinuvin 928, all of which are commercially available products from BASF Japan, and can be preferably used. Among these, it is preferable that it is halogen-free.

In addition, discoid compounds such as compounds having 1,3,5 triazine rings are also preferably used as ultraviolet absorbers.

When the base material according to the present invention contains a UV absorber, it may contain one or two or more of them, preferably two or more.

Moreover, as a ultraviolet absorber, a polymeric ultraviolet absorber can also be used suitably, and especially the polymer type ultraviolet absorber of Unexamined-Japanese-Patent No. 6-148430 is used preferably.

The addition method of the ultraviolet absorber is to dissolve the ultraviolet absorber in an alcohol such as methanol, ethanol, or butanol, or an organic solvent such as methylene chloride, methyl acetate, acetone, or dioxolane, or a mixed solvent thereof, and then add it to a dope described later, or You may directly add during dope composition.

Those that do not dissolve in the organic solvent, such as inorganic powder, are dispersed in the organic solvent using a dissolver or sand mill, and then added to the dope.

The amount of the ultraviolet absorber used in the substrate is not uniform depending on the type of ultraviolet absorber, conditions of use, etc., but when the dry film thickness of the substrate is 15 to 50 μm, the range of 0.5 to 10% by mass is preferable with respect to the substrate. , more preferably in the range of 0.6 to 4% by mass.

<Antioxidant>

Antioxidants are also called anti-deterioration agents. When a liquid crystal display device or the like is placed in a high-humidity, high-temperature state, deterioration of the substrate may occur.

Antioxidant has a role of delaying or preventing decomposition of the substrate by, for example, halogen of residual solvent amount in the substrate or phosphoric acid of a phosphoric acid-based plasticizer, so it is preferable to include it in the substrate.

As such an antioxidant, a hindered phenolic compound is preferably used, and examples thereof include 2,6-di-t-butyl-p-cresol and pentaerythrityl-tetrakis[3-(3,5-di). -t-butyl-4-hydroxyphenyl)propionate], triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6- Hexanediol-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 2,4-bis-(n-octylthio)-6-(4-hydroxy- 3,5-di-t-butylanilino)-1,3,5-triazine, 2,2-thio-diethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl ) propionate], octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, N,N'-hexamethylenebis(3,5-di-t-butyl -4-hydroxy-hydrocinnamamide), 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, tris-(3, 5-di-t-butyl-4-hydroxybenzyl)-isocyanurate; and the like.

In particular, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], triethylene Glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate] is preferred. In addition, for example, hydrazine-type metal deactivators such as N,N'-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl]hydrazine and tris(2,4-di -You may use together phosphorus processing stabilizers, such as t-butylphenyl) phosphite.

These antioxidants may be used individually by 1 type, or may use 2 or more types together. The addition amount of the antioxidant in the substrate is preferably in the range of 1 ppm by mass to 1.0 mass %, more preferably in the range of 10 to 1000 ppm by mass, in terms of mass ratio with respect to the cellulose acylate (A).

<fine particles (mat agent)>

The base material in the laminated film of the present invention may further contain fine particles (mat agent) as needed in order to improve the slipperiness of the surface.

The fine particles may be inorganic fine particles or organic fine particles. Examples of inorganic fine particles include silicon dioxide (silica), titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate and calcium phosphate, etc. do. Among them, silicon dioxide and zirconium oxide are preferable, and silicon dioxide is more preferable in order to reduce the increase in the haze of the base material obtained.

Examples of fine particles of silicon dioxide include Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600, NAX50 (above, manufactured by Nippon Aerosil Co., Ltd.), Seahosta KE-P10, KE -P30, KE-P50, KE-P100 (manufactured by Nippon Shokubai Co., Ltd.) and the like are included. Among them, Aerosil R972V, NAX50, Seahosta KE-P30 and the like are particularly preferred in order to reduce the coefficient of friction while maintaining low turbidity of the base material obtained.

The primary particle size of the fine particles is preferably in the range of 5 to 50 nm, and more preferably in the range of 7 to 20 nm. The larger the primary particle diameter, the greater the effect of improving the slipperiness of the obtained base material, but the transparency tends to decrease. Therefore, the fine particles may be contained as secondary aggregates with a particle diameter in the range of 0.05 to 0.3 µm. The size of the primary particles or secondary aggregates of fine particles can be obtained as the average value of the particle diameters of 100 primary particles or secondary aggregates by observing the primary particles or secondary aggregates with a transmission electron microscope at a magnification of 50 to 2 million times. have.

These fine particles may be used individually by 1 type, or may use 2 or more types together. The content of the fine particles in the substrate is preferably in the range of 0.05 to 1.0 parts by mass, more preferably in the range of 0.1 to 0.8 parts by mass, based on 100 parts by mass of the cellulose acylate (A).

<Method for manufacturing base material>

As the method for producing the base material of the laminated film of the present invention, a normal inflation method, T-die method, calender method, cutting method, casting method, emulsion method, hot press method or the like can be used. From the viewpoints of suppression of coloration, suppression of foreign material defects, suppression of optical defects such as die lines, etc., the solution casting method and the melt casting method can be selected as the film forming method, and the solution casting method is particularly preferable in order to obtain a uniform surface. do.

(Solution casting method)

Hereinafter, a case in which the base material according to the present invention is produced by a solution casting method will be described.

1) Melting process

In the dissolution step, the cellulose acylate (A) and sugar ester (B) are dissolved in an organic solvent mainly serving as a good solvent for the cellulose acylate (A) and the sugar ester (B) in a dissolution pot, and others added as necessary. A step of dissolving or dispersing the components while stirring to form a dope, or a solution (dispersion) of the sugar ester (B) according to the present invention and other components added as necessary to a solution of the cellulose acylate (A) This is a process of mixing the dope, which is the main solution.

The organic solvent can be used without limitation as long as it can dissolve the cellulose acylate (A) and the sugar ester (B) and dissolve or disperse the above other components.

For example, methylene chloride as the chlorine-based organic solvent, and methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, and cyclohexanone as the non-chlorine-based organic solvent. , ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3 3,3-hexafluoro-2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro -1-propanol, nitroethane, etc. are mentioned, and methylene chloride, methyl acetate, ethyl acetate, and acetone can be used preferably.

It is preferable to make dope contain 1-40 mass % of C1-C4 linear or branched aliphatic alcohol other than the said organic solvent. When the ratio of alcohol in the dope is high, the web is gelled and peeling from the metal support is facilitated, and when the ratio of alcohol is low, cellulose acylate (A), sugar ester (B) and other It also has a role in accelerating the dissolution of the components of

In particular, a cellulose acylate (A), a sugar ester (B) and other components are dissolved in a total amount of at least 15 to 45% by mass in a solvent containing methylene chloride and a linear or branched aliphatic alcohol having 1 to 4 carbon atoms, or It is preferable that it is dope disperse|distributed.

Examples of straight or branched aliphatic alcohols having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol and tert-butanol. Ethanol is preferable in terms of dope stability, relatively low boiling point, and good drying property.

The dissolution of cellulose acylate (A) and sugar ester (B) and the dissolution or dispersion of other components are carried out under normal pressure, under the boiling point of the main solvent, under pressure above the boiling point of the main solvent, Japan A method performed by a cooling melting method as described in Japanese Unexamined Patent Publication No. 9-95544, Japanese Unexamined Patent Publication No. 9-95557, or Japanese Unexamined Patent Publication No. 9-95538, described in Japanese Unexamined Patent Publication No. Hei 11-21379 Although various melting methods can be used, such as a method performed at a high pressure, a method performed by applying pressure above the boiling point of the main solvent is particularly preferable. It is preferable to filter the dope during or after dissolution of each component with a filter medium, degas it, and send it to the next step with a liquid feeding pump.

For filtration, it is preferable to use a filter medium having a collection particle diameter of 0.5 to 5 μm and a filtering time of 10 to 25 sec/100 ml.

In this method, only the aggregates can be removed by using a filter medium with a collection particle size of 0.5 to 5 μm and a free water time of 10 to 25 sec / 100 ml for aggregates remaining during particle dispersion and aggregates generated during main dope addition. In the main dope, since the concentration of the particles is sufficiently light compared to that of the additive solution, the aggregates do not adhere to each other during filtration and the filtration pressure rises rapidly.

2) Flexible process

The dope is fed to a pressurizing die through a liquid feeding pump (eg, a pressurizing metering gear pump), and endlessly conveyed by a metal belt, for example, a stainless steel belt, or a lead on a metal support such as a rotating metal drum. It is the process of casting the dope from the pressurized die slit into position.

A pressure die that can adjust the slit shape of the mouthpiece portion of the die and easily makes the film thickness uniform is preferable. The pressure die includes a coating hanger die, a T die, and the like, and all are preferably used. The surface of the metal support is mirror-finished. In order to increase the film forming speed, two or more pressure dies may be provided on the metal support, and the dope amount may be divided and layered. Alternatively, it is also preferable to obtain a film having a laminated structure by a covalent casting method in which a plurality of dopes are simultaneously casted.

3) Solvent evaporation process

This is a step in which a web (a dope film formed by casting dope on a casting support body is referred to as a web) is heated on a casting support body to evaporate the solvent.

Evaporation of the solvent includes a method of blowing air from the web side, a method of transferring heat with liquid from the back side of the support, a method of transferring heat from the front and back by radiant heat, etc. desirable. Moreover, the method of combining these is also used preferably. It is preferable to dry the web on a support body after casting|flow_spreading on a support body in the atmosphere of 20-100 degreeC. To maintain in an atmosphere of 20 to 100°C, it is preferable to apply warm air at this temperature to the upper surface of the web or to heat it by means such as infrared rays.

From the viewpoint of cotton quality, moisture permeability, and peelability, it is preferable to peel the web from the support within 30 to 120 seconds.

In addition, the conditions of the solvent evaporation step may affect the physical properties of the above (1-2) when used as a base material. Since planar orientation tends to proceed in the web at the beginning of the solvent evaporation step, the inclination T of the out-of-plane retardation tends to increase by lowering the speed of solvent evaporation at low temperatures. Conversely, when the speed of solvent evaporation is increased, the slope T of the out-of-plane retardation tends to decrease.

Therefore, for example, in the initial stage of the solvent evaporation step, after performing a heat treatment for about 20 to 60 seconds at a low temperature of about 20 to 50 ° C., the amount of residual solvent at the time of peeling the web at a high temperature of about 50 to 70 ° C. A method of performing heat treatment until it reaches an appropriate range is preferable from the viewpoint of setting the slope T of the out-of-plane retardation within the range of (1-2) above.

In addition, the amount of residual solvent in the web at the time of peeling the web from the metal support in the following peeling step is preferably in the range of about 20 to 80% by mass depending on the strength and weakness of the drying conditions, the length of the metal support, and the like. do. In the case of peeling at the time when the amount of residual solvent is greater, if the web is too soft, flatness is damaged during peeling, and friction or vertical stripes due to peeling tension are likely to occur. It is decided. In addition, the residual solvent amount of a web is defined by the following formula.

Residual solvent amount (% by mass) = (mass of web before heat treatment - mass of web after heat treatment) / (mass of web after heat treatment) × 100

In addition, heat treatment at the time of measuring the amount of residual solvent means performing heat treatment at 140 degreeC for 1 hour.

4) Peeling process

On a metal support, until the amount of residual solvent in the web becomes the above appropriate amount, for example, 20 to 80% by mass, preferably 20 to 30% by mass, the web in which the solvent is evaporated is removed from the peeling position. It is a peeling process. The peeled web is sent to the next process.

The peeling tension at the time of peeling the metal support and the web is usually in the range of 160 to 245 N/m, but when wrinkles tend to occur during peeling, it is preferable to peel at a tension of 190 N/m or less.

In the present invention, the temperature at the peeling position on the metal support is preferably in the range of -50 to 40°C, more preferably in the range of 10 to 40°C, and most preferably in the range of 15 to 30°C. desirable.

5) Drying and stretching process

After peeling, the web is dried using a drying device that conveys the web by alternately passing it through a plurality of rollers arranged in a drying device, and/or a tenter stretching device that clips both ends of the web with a clip and conveys the web.

As a drying means, it is common to blow hot air on both sides of the web, but there is also a means to heat by applying microwaves instead of wind. Too rapid drying tends to damage the flatness of the finished substrate. It is preferable to perform drying by high temperature from about 8 mass % or less of residual solvents. The whole is passed through, and drying is performed generally within the range of 40-250 degreeC. It is preferable to dry especially within the range of 40-200 degreeC.

When the glass transition temperature of the web is Tg of the substrate in a direction (width direction, TD direction) orthogonal to the conveying direction (spreading direction, MD direction) so that the thickness as a substrate after stretching is in the range of 10 to 50 μm, It is preferable to stretch in the temperature range of (Tg+15) to (Tg+50) degreeC. At a temperature lower than (Tg+15)°C, retardation tends to occur and the stretching stress increases, so the haze tends to increase. When stretching is performed at a temperature exceeding (Tg + 50) ° C., breakage occurs, flatness deteriorates, and furthermore, the color of the base material itself becomes stronger, so the quality (optical properties) as a retardation film cannot be maintained in some cases. . As for the extending|stretching temperature, it is more preferable to carry out in the range of (Tg+20) - (Tg+40) degreeC.

Note that the glass transition temperature Tg referred to herein is a midpoint glass transition temperature (Tmg) measured using a commercially available differential scanning calorimeter at a heating rate of 20°C/min and determined according to JIS K7121 (1987).

The specific method for measuring the glass transition temperature Tg of the substrate is measured according to JIS K7121 (1987) using a differential scanning calorimeter DSC220 manufactured by Seiko Instruments Co., Ltd.

About 10 mg of substrate sample was set, the temperature was raised from room temperature to 250 °C at 20 °C/min under the condition of a nitrogen flow rate of 50 ml/min, maintained for 10 minutes (1st scan), and then heated to 30 °C at a rate of 20 °C/min. The temperature is lowered and held for 10 minutes (2nd scan), and the temperature is raised to 250°C at 20°C/min (3rd scan) to create a DSC curve, and the glass transition temperature Tg can be obtained from the DSC curve of the obtained 3rd scan.

In the present invention, it is preferable to prepare a sample experimentally in advance using a material constituting the substrate, and stretch it in the above temperature range with respect to the measured Tg of the substrate sample.

When using a tenter stretching device for stretching, it is preferable to use a device capable of independently controlling the gripping length of the web (the distance from the start of gripping to the end of gripping) from the left and right sides by the left and right gripping means of the tenter stretching device. . In addition, in the stretching process, it is also desirable to intentionally create sections having different temperatures in order to improve flatness.

Moreover, it is also preferable to provide a neutral zone between different temperature zones so that each zone may not cause interference.

Further, the stretching operation may be divided into multiple stages and performed, and it is particularly preferable to perform biaxial stretching in the casting direction and the width direction. In addition, when performing biaxial stretching, simultaneous biaxial stretching may be performed, and you may carry out stepwise. The stretching ratio is preferably within a range of 1.1 to 4 times, preferably 1.2 to 3 times the original width of the web, including the casting direction and the width direction.

In this case, stepwise means, for example, that stretching in different stretching directions can be sequentially performed, or stretching in the same direction can be divided into multiple stages, and stretching in different directions can be added to any stage. That is, for example, the following stretching step is also possible.

Stretching in the casting direction→stretching in the width direction→stretching in the casting direction→stretching in the casting direction

Stretching in the width direction → Stretching in the width direction → Stretching in the softening direction → Stretching in the softening direction

In addition, simultaneous biaxial stretching also includes a case where stretching is performed in one direction and the other side is contracted by relieving the tension. A preferred draw ratio in simultaneous biaxial stretching is in the range of 1.01 to 1.5 times the original width in both the width direction and the casting direction. Particularly preferably, from the viewpoint of reducing the retardation value, stretching in the width direction is preferably in the range of 1.01 to 1.2 times the original width of the film, and more preferably in the range of 1.05 to 1.1 times.

The amount of residual solvent of the web in the case of drying and stretching with a tenter stretching device is preferably in the range of 20 to 30% by mass when applied to a tenter stretching device, until the residual solvent amount of the web is 15% by mass or less It is preferable to dry while hanging on a tenter stretching device.

In the tenter stretching device, the residual solvent amount of the web at the start of stretching is preferably 1 to 15% by mass, and more preferably 2 to 10% by mass. Further, it is preferable to dry the web until the amount of residual solvent in the coiling step is 2% by mass or less, more preferably 0.4% by mass or less.

In the tenter stretching device, a smaller temperature distribution in the width direction of the atmosphere is preferable from the viewpoint of improving the uniformity of the substrate, and the temperature distribution in the width direction in the tenter stretching device is preferably within ±5 ° C., and ±2 Within °C is more preferred, and within ±1 °C is most preferred.

6) Emboss processing process

Since the base material according to the present invention is a thin film with a preferred thickness in the range of 10 to 50 μm, there is a risk of winding deviation and deterioration of optical quality when the base material is stored in a roll shape, but these can be effectively prevented by embossing. . In addition, embossing is an arbitrary process.

The embossing portion is a pattern in which a pattern of a certain width consisting of continuous minute concavities and convexities is applied to the base material in order to prevent the back and surface of the rolled films from being completely in close contact with each other before winding a long film. When one surface (eg, upper surface) of the substrate is protruded in a convex shape, a relatively concave shape is formed on the other surface (eg, lower surface) of the substrate corresponding to the convex shape. This serves to prevent the wound substrates from being completely adhered or partially adhered to each other to affect the state of the surface of the substrates and cause failure.

7) winding process

This is a step of winding the web as a substrate after the amount of residual solvent in the web is 2% by mass or less, and by setting the amount of residual solvent to 0.4% by mass or less, a substrate having good dimensional stability can be obtained. It is preferable to wind in the range of 0.00-0.10 mass % especially.

As the winding method, a generally used one may be used, and there are constant torque method, constant tension method, taper tension method, program tension control method with constant internal stress, and the like, and these may be used separately.

According to the above method, the substrate according to the present invention is obtained as a long film, for example. Specifically, those of about 100 m to 10000 m are exemplified, and a roll body of a base material having a winding length of 5000 m or more is particularly preferred. Moreover, it is preferable that it is 1-4 m, and, as for the width|variety of a base material, it is more preferable that it is 1.4-3 m. The thickness of the substrate according to the present invention is preferably in the range of 10 to 50 μm, and more preferably in the range of 20 to 40 μm.

<Characteristics of Substrate>

(Phase difference (retardation value))

In the substrate according to the present invention, the in-plane retardation Ro590 defined by the following formula (i), measured with light having a wavelength of 590 nm in an environment of a temperature of 23 ° C. and a relative humidity of 55%, is within the range of 0 to 10 nm, and the following formula It is preferable that the out-of-plane retardation R590 defined by (ii) is in the range of -20 to 20 nm.

Equation (i): Ro=(n _x -n _y )×d (nm)

Equation (ii): R={(n _x +n _y )/2-n _z }×d (nm)

[In the formulas (i) and (ii), n _x represents the refractive index in the direction x where the refractive index becomes the maximum in the in-plane direction of the film. n _y represents the refractive index in the direction y orthogonal to the direction x in the in-plane direction of the film. n _z represents the refractive index in the thickness direction z of the film. d represents the thickness (nm) of the film.]

These phase differences (retardation values) can be measured using an automatic birefringence meter KOBRA-WPR (Oji Keisoku Kiki).

The description of the present invention satisfies the above (1-2) with respect to out-of-plane retardation. That is, the value T (slope T of the out-of-plane retardation) obtained based on the above formula (1) from the out-of-plane retardation R650 measured with light having a wavelength of 650 nm and the out-of-plane retardation R450 measured with light having a wavelength of 450 nm with respect to the substrate is 0.040 to 0.055. The slope T of the out-of-plane retardation is preferably in the range of 0.045 to 0.050.

In addition, out-of-plane retardation R650 and out-of-plane retardation R450 can be measured by the same method as for out-of-plane retardation R590, except that the measurement wavelength is different.

When the inclination T of the out-of-plane retardation of the substrate is within the above range, when the laminated film of the present invention is laminated with the optical function layer, the laminated film can achieve the optical properties (1.1≤Rth450/Rth550≤1.9) of (3) above. can

(full haze)

In the substrate according to the present invention, the total haze is preferably less than 1%, more preferably 0.5% or less, and more preferably 0.2% or less. When the haze is less than 1%, there is no decrease in transparency of the base material, and when it is set as a laminated film of the present invention laminated with an optical function layer, it functions sufficiently as an optical (retardation) film.

The total haze of the substrate can be measured with a haze meter NDH-2000 (manufactured by Nippon Denshoku Kogyo Co., Ltd.) in accordance with JIS K-7136. The light source of the haze meter is a 5V9W halogen bulb, and the light receiving unit can be a silicon photo cell (equipped with a non-visibility filter). The haze can be measured under conditions of 23°C and 55% RH.

(total light transmittance)

The substrate according to the present invention preferably has a total light transmittance of 90% or more, more preferably 93% or more. Moreover, as a realistic upper limit, it is about 99%. In order to achieve excellent transparency represented by such a total light transmittance, additives and copolymerization components that absorb visible light are not introduced, and foreign substances in the raw materials, for example, in the dope, are removed by high-precision filtration, and the inside of the substrate It is effective to reduce diffusion or absorption of light. In addition, by reducing the surface roughness of substrate contacting parts (cooling roller, calender roller, drum, belt, coated substrate in solution film forming, transport roller, etc.) during film formation to reduce the surface roughness of the substrate surface, diffusion of light on the surface of the substrate and It is effective to reduce the reflection.

(optical functional layer)

The optical function layer contains a polymer containing fumaric acid ester polymerized units in an amount of 90 mol% or more with respect to all polymerized units. 80 to 100% of the ester portion of the fumaric acid ester polymerization unit in the polymer is isopropyl ester. Hereinafter, a polymer containing fumaric acid ester polymerized units at a ratio of 90 mol% or more with respect to all polymerized units and in which 80 to 100% of the ester portion of the fumaric acid ester polymerized units is isopropyl ester is also referred to as "polymer (F)". .

The optical function layer may contain other components other than the polymer (F) as needed within a range not impairing the effect of the present invention.

(Polymer (F))

The optical function layer contains polymer (F). An optical function layer is comprised from polymer (F) other than the other component contained arbitrarily. The content ratio of the polymer (F) in the optical function layer is, for example, preferably 90% by mass or more, more preferably 95% by mass or more, and particularly preferably 100% by mass.

The polymer (F) used in the present invention is a polymer containing fumaric acid ester polymerized units in an amount of 90 mol% or more with respect to all polymerized units, and 80 to 100% of the ester portion of the fumaric acid ester polymerized units is isopropyl ester. is a phosphorus polymer. Here, a "polymerized unit" is a unit derived from a monomer constituting a polymer, and refers to a unit constituted by residues in the polymer of raw material monomers used to produce the polymer.

In the polymer (F), the ratio of fumaric acid ester polymerized units to all polymerized units is preferably 95 mol% or more, more preferably 98 mol% or more, and particularly preferably 100 mol%. Further, in the polymer (F), the ratio of isopropyl ester in the ester portion of the fumaric acid ester polymerization unit is preferably 85 to 100%, more preferably 90 to 100%, particularly preferably It is 100%.

In the polymerized unit of fumaric acid ester, the fumaric acid ester as the monomer underlying the polymerized unit may be a monoester in which only one of the two carboxy groups in fumaric acid is esterified, or a diester in which both of the two carboxy groups in fumaric acid are esterified. may be In the polymer (F), it is preferable to use a fumaric acid diester. The ester portion of the fumaric acid ester used as the monomer contains isopropyl ester, and the monomers are combined so that the ratio of the isopropyl ester in the ester portion of the fumaric acid ester polymerization unit in the entire polymer (F) falls within the above range. and use it

As the fumaric acid ester polymerized unit in the polymer (F), a fumaric acid diester polymerized unit (a) represented by the following general formula (a) is preferable, for example.

In the general formula (a), R ₁ and R ₂ each independently represent an alkyl group having 1 to 12 carbon atoms. However, 80 to 100% of the total number of R ₁ and R ₂ in the polymer (F) is an isopropyl group.

The monomer that forms the basis of the fumaric acid diester polymerization unit (a) is hereinafter referred to as "fumaric acid diester (a)", and R ₁ and R ₂ are also referred to as "ester groups". The polymer (F) can be a polymer obtained by combining the fumaric acid diesters (a1) to (a3) classified as follows in the fumaric acid diester (a) so that 80 to 100% of the ester groups are isopropyl groups. . The ratio of the isopropyl group in the ester group is preferably 85 to 100%, more preferably 90 to 100%, and particularly preferably 100%.

fumaric acid diesters (a1); Both R ₁ and R ₂ are isopropyl groups.

fumaric acid diesters (a2); One of R ₁ and R ₂ is an isopropyl group, and the other is an alkyl group having 1 to 12 carbon atoms other than an isopropyl group.

fumaric acid diesters (a3); Both of R ₁ and R ₂ are alkyl groups having 1 to 12 carbon atoms other than an isopropyl group.

Examples of the alkyl group having 1 to 12 carbon atoms other than the isopropyl group in R ₁ and R ₂ include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, and an n-hexyl group. branched alkyl groups such as straight-chain alkyl groups, s-butyl groups, t-butyl groups, s-pentyl groups, t-pentyl groups, s-hexyl groups and t-hexyl groups, cyclopropyl groups, cyclopentyl groups, and cyclohexyl groups Cyclic alkyl groups, such as these, are mentioned. In addition, these alkyl groups are halogen groups, such as fluorine and chlorine, within the range which does not impair the effect of this invention; ether group; It may be substituted by an ester group or an amino group.

When polymer (F) is obtained by combining fumaric acid diesters (a1) to (a3), from the viewpoint of ease of production, fumaric acid diester (a1), that is, fumaric acid diisopropyl and fumaric acid diester (a3) is combined to obtain polymer (F). It is desirable to obtain (F). In the polymerization of polymer (F), when diisopropyl fumarate and diester fumarate (a3) are used as monomers, the mole percentage of diisopropyl fumarate relative to the total molar amount of diisopropyl fumarate and diester fumarate (a3) By setting 80 to 100 mol%, 80 to 100% of the ester portion of the polymerized unit of the fumaric acid ester in the polymer (F) can be made into an isopropyl ester.

As the fumaric acid diester (a3), dimethyl fumarate, diethyl fumarate, di-n-propyl fumarate, di-n-butyl fumarate, di-n-pentyl fumarate, di-n-hexyl fumarate, di-s-butyl fumarate , di-t-butyl fumarate, di-s-pentyl fumarate, di-t-pentyl fumarate, di-s-hexyl fumarate, di-t-hexyl fumarate, dicyclopropyl fumarate, dicyclopentyl fumarate, dicyclohexyl fumarate These etc. are mentioned, Dimethyl fumarate, diethyl fumarate, etc. are preferable.

Polymer units other than fumaric acid ester polymer units that may be contained in the polymer (F) in an amount of 10 mol% or less with respect to all polymer units include, for example, polymer units based on the following monomers. In the polymer (F), a monomer serving as a basis for polymerization units other than the fumaric acid ester polymerization unit is also referred to as "monomer (b)" below.

As said monomer (b), For example, Styrene, such as styrene and (alpha)-methylstyrene; (meth)acrylic acid; (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 3-ethyl-3-oxetanylmethyl (meth)acrylate, and tetrahydrofurfuryl (meth)acrylate; vinyl esters such as vinyl acetate and vinyl propionate; acrylonitrile; methacrylonitrile; olefins such as ethylene and propylene; 1 type, or 2 or more types of etc. are mentioned. In addition, "(meth)acrylic acid" represents one or both of acrylic acid and methacrylic acid.

As the polymer (F) used in the present invention, those having a number average molecular weight (Mn) in terms of standard polystyrene obtained from an elution curve measured by gel permeation chromatography (GPC) of 1×10 ³ or more are preferable, and particularly mechanical It is preferable that it is 2×10 ⁴ or more and 2×10 ⁵ or less from the point of becoming an optical function layer having excellent characteristics and excellent molding processability at the time of film formation.

As a method for producing the polymer (F) used in the present invention, any method may be used as long as the polymer (F) is obtained. It can manufacture by carrying out radical polymerization or radical copolymerization using the fumaric acid ester selected so that 100% may become isopropyl ester, and monomer (b) of 10 mol% or less of all monomers as needed. Further, as the fumaric acid ester, it is preferable to use a mixture of 80 to 100% by mol of diisopropyl fumarate and 0 to 20% by mol of a fumaric acid diester (a3).

In addition, as a radical polymerization method to be used, it is possible to carry out by a known polymerization method, and for example, any of bulk polymerization, solution polymerization, suspension polymerization, precipitation polymerization, emulsion polymerization, etc. can be employed.

Examples of the polymerization initiator in the radical polymerization method include benzoyl peroxide, lauryl peroxide, octanoyl peroxide, acetyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, and dicumyl peroxide. , organic peroxides such as t-butyl peroxyacetate, t-butyl peroxybenzoate, and t-butyl peroxypivalate; 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-butyronitrile), 2,2'-azobisisobutyronitrile, dimethyl-2,2 and azo-based initiators such as '-azobisisobutyrate and 1,1'-azobis(cyclohexane-1-carbonitrile).

In addition, the solvent usable in the solution polymerization method, suspension polymerization method, precipitation polymerization method, and emulsion polymerization method is not particularly limited, and examples thereof include aromatic solvents such as benzene, toluene, and xylene; Alcohol solvents, such as methanol, ethanol, propyl alcohol, and butyl alcohol; cyclohexane; dioxane; tetrahydrofuran (THF); acetone; methyl ethyl ketone; dimethylformamide; isopropyl acetate; Water etc. are mentioned, These mixed solvents are also mentioned.

In addition, the polymerization temperature at the time of carrying out radical polymerization can be set suitably according to the decomposition temperature of a polymerization initiator, and it is preferable to carry out generally in the range of 40-150 degreeC.

(other ingredients)

The optical function layer concerning the laminated|multilayer film of this invention may contain other components other than the polymer (F) as needed within the range which does not impair the effect of this invention. Examples of other components include ultraviolet absorbers, antioxidants, fine particles (mat agent), surfactants, polymer electrolytes, conductive complexes, antistatic agents, antiblocking agents, and lubricants.

The optical function layer according to the present invention preferably contains an antioxidant in order to improve thermal stability. Examples of the antioxidant include hindered phenolic antioxidants, phosphorus antioxidants, and other antioxidants similar to those described above, and these antioxidants may be used alone or in combination, respectively.

In the optical function layer, it is preferable to use a hindered phenol-based antioxidant and a phosphorus-based antioxidant in combination from the viewpoint that the antioxidant action is improved synergistically. In that case, for example, 100 parts by mass of the hindered phenol-based antioxidant It is particularly preferable to use a phosphorus antioxidant in an amount of 100 to 500 parts by mass. Moreover, as addition amount of antioxidant in an optical function layer, 0.01-10 mass parts is preferable with respect to 100 mass parts of polymers (F), and 0.5-1 mass part is especially preferable.

As for the ultraviolet absorber and microparticles (matting agent) that can be contained in the optical function layer, the same ones as the ultraviolet absorber and microparticles (matting agent) that the substrate may contain can be exemplified.

<Method of manufacturing optical functional layer and laminated film>

In the present invention, the optical function layer is laminated with the substrate to form the laminated film of the present invention. The optical function layer may be formed singly into a film form, or may be formed into a layer form on a base material. When the optical function layer is molded alone, the optical function layer and the substrate are laminated using, for example, an adhesive agent or the like. When an optical function layer is formed layer by layer on a substrate, manufacture of the optical function layer and lamination of the optical function layer and the substrate are performed simultaneously.

As the manufacturing method in the case of forming the optical function layer alone into a film form, for example, the same inflation method as the manufacturing method of the base material, T-die method, calender method, cutting method, casting method, emulsion method, hot press Manufacturing methods such as a method can be applied, and a solution casting method and a melt casting method can be selected as preferred methods, and a solution casting method is particularly preferable for obtaining a uniform surface.

The solution cast film forming method is a method in which a solution (dope) in which a polymer (F) and other components added as necessary are dissolved in a solvent is cast on a support, and then the solvent is removed by heating or the like to obtain a film. In the solution cast film forming method, when forming a film having high transparency and excellent thickness accuracy and surface smoothness, the solution viscosity of the dope is an extremely important factor, preferably 700 to 30000 cps, and particularly preferably 1000 to 10000 cps. do.

As a method of casting dope on a support, for example, a T die method, a doctor blade method, a bar coater method, a roll coater method, a lip coater method, etc. are used. In particular, industrially, a method of continuously extruding dope from a die to a belt-shaped or drum-shaped support is the most common. As a support body used, it is a glass substrate, for example; metal supports such as stainless steel and ferrotype; and plastic supports such as polyethylene terephthalate (PET) and triacetyl cellulose (TAC).

The dope extruded on the support is made into a film by removing the solvent by heating or the like. In this way, a film-like optical function layer containing the polymer (F) is obtained. The said film is used by peeling from a support body.

In the melt cast film forming method, a mixture of constituent components of the optical function layer containing the polymer (F) is melted in an extruder, extruded into a film form through a slit of a T die, and then held while cooling with a roll, air, or the like. It is a pulling molding method.

As a method of laminating the film-like optical function layer and the base material, a method of bonding using a known adhesive agent is exemplified. In the case where the film-like optical function layer is produced as a roll body by the solution casting method as described above and the base material is manufactured as a roll body as described above, for example, a known adhesive is used in a roll-to-roll continuous process. can be joined

When the optical function layer is molded in a layer form on the substrate, the optical function layer can be prepared by applying a liquid composition for forming the optical function layer onto the substrate and drying it. At the same time, the optical function layer and the base material are laminated to obtain the laminated film of the present invention.

In this method, first, a solution (coating solution) in which the polymer (F) and other components added as necessary are dissolved in a solvent is prepared. In order to obtain an optical functional layer having high transparency and excellent in thickness precision and surface smoothness, the viscosity of the coating solution is an extremely important factor, preferably 10 to 10000 cps, and particularly preferably 10 to 5000 cps.

As a coating method, a doctor blade method, a bar coater method, a gravure coater method, a slot die coater method, a lip coater method, a comma coater method, etc. are used, for example. Industrially, the gravure coater method is common for thin film coating, and the comma coater method is common for thick film coating.

After application on the substrate, the optical function layer is obtained on the substrate by removing the solvent by heating or the like. In addition, also in the said melt-casting film forming method, it can be set as a laminated|multilayer film by forming a film as an optical function layer on a base material by using a base material as a support body.

In addition, prior to lamination of the base material and the optical function layer, it is also possible to subject the lamination surface of the base material to the optical function layer to an adhesion-facilitating treatment such as plasma treatment or corona discharge treatment.

The thickness of the optical function layer in the laminated film of the present invention is determined by the retardation in the thickness direction of the optical function layer, and is preferably 1 to 30 µm, more preferably 2 to 20 µm, and particularly preferably 2 µm. to 10 μm.

<Characteristics of laminated film>

(Phase difference (retardation value))

The laminated film of the present invention satisfies the above (3) with respect to out-of-plane retardation. That is, for the laminated film, the value Rth450/Rth550 of the ratio of the out-of-plane retardation Rth450 measured with light with a wavelength of 450 nm and the out-of-plane retardation Rth550 measured with light with a wavelength of 550 nm is within the range of 1.1 to 1.9. Rth450/Rth550 is preferably in the range of 1.2 to 1.7.

In addition, the out-of-plane retardation Rth450 and the out-of-plane retardation Rth550 can be measured by the same method as the method for measuring the out-of-plane retardation in the base material, except that the measurement wavelength is different.

Further, the laminated film of the present invention preferably has an out-of-plane retardation Rth550 within the range of -30 to -15 nm, more preferably within the range of -25 to -18 nm. Further, the out-of-plane retardation Rth450 of the laminated film is preferably in the range of -40 to -15 nm, and more preferably in the range of -30 to -18 nm.

(full haze)

It is preferable that the total haze of the laminated|multilayer film of this invention measured by the method similar to a base material is less than 1 %, it is more preferable that it is 0.5 % or less, and it is more preferable that it is 0.2 % or less. When the haze is less than 1%, there is no decrease in transparency of the laminated film, and it sufficiently functions as an optical (retardation) film.

(total light transmittance)

The laminated film of the present invention preferably has a total light transmittance of 90% or more, more preferably 93% or more, as measured by the same method as that of the base material. Moreover, as a realistic upper limit, it is about 99%.

<Other functional layers>

Functional layers such as an antistatic layer, a backcoating layer, an antireflection layer, an activation facilitating layer, an adhesive layer, an antiglare layer, and a barrier layer can be provided on the laminated film of the present invention as needed depending on its use.

[Polarizer]

The polarizing plate of the present invention is characterized in that the laminated film of the present invention and the polarizer are laminated. When the polarizing plate of the present invention is provided with the laminated film of the present invention and is used for a liquid crystal display device, good visibility can be ensured.

The polarizing plate of the present invention has, for example, a polarizer and a laminated film of the present invention arranged on one surface of the polarizer. In that case, the structure which has a protective film on the other surface of a polarizer may be sufficient. Moreover, the polarizing plate which has the laminated|multilayer film of this invention on both surfaces of a polarizer may be sufficient.

2 is a cross-sectional view showing a configuration example of the polarizing plate of the present invention. As shown in FIG. 2 , the polarizing plate 20 has a polarizer 11, a laminated film 10 disposed on one surface of the polarizer 11, and a protective film 12 disposed on the other surface. The laminated film 10 is formed by laminating the base material 1 and the optical function layer 2, and the base material 1 side is disposed so as to face one side of the polarizer 11. The polarizer 11, the laminated film 10, and the protective film 12 are bonded via an arbitrary adhesive layer (not shown).

<Polarizer>

A polarizer, which is a main component of a polarizing plate, is an element that transmits only light of a polarization plane in a certain direction, and a typical polarizer currently known is a polyvinyl alcohol-based polarizing film. Polyvinyl alcohol-based polarizing films include those obtained by dyeing iodine on polyvinyl alcohol-based films and those obtained by dyeing dichroic dyes.

As the polarizer, a polarizer obtained by forming a polyvinyl alcohol aqueous solution into a film, uniaxially stretching it to be dyed, or uniaxially stretching it after dyeing, and preferably performing durability treatment with a boron compound may be used. The film thickness of the polarizer is preferably within a range of 5 to 30 µm, and particularly preferably within a range of 5 to 15 µm.

As the polarizer, the ethylene-modified poly having an ethylene unit content of 1 to 4 mol%, a polymerization degree of 2000 to 4000, and a saponification degree of 99.0 to 99.99 mol% described in Japanese Patent Laid-Open No. 2003-248123 and Japanese Patent Laid-Open No. 2003-342322, etc. A vinyl alcohol film is also preferably used. Among them, an ethylene-modified polyvinyl alcohol film having a hot water cutting temperature in the range of 66 to 73°C is preferably used. A polarizer using this ethylene-modified polyvinyl alcohol film has excellent polarization performance and durability performance, and also has little color unevenness, and is particularly preferably used for a large-sized liquid crystal display device.

In addition, by the method described in Japanese Patent Laid-Open No. 2011-100161, Japanese Patent No. 4691205, Patent No. 4751481, and Japanese Patent No. 4804589, an application type polarizer was prepared and bonded to the laminated film of the present invention to form a polarizing plate. It is also desirable to produce.

<Protective Film>

The protective film usable in the polarizing plate of the present invention can be obtained as a commercial item, for example. Examples of protective films include commercially available cellulose acylate films (e.g., Konica Minolta Tac KC8UX, KC5UX, KC4UX, KC8UCR3, KC4SR, KC4BR, KC4CR, KC4DR, KC4FR, KC4KR, KC8UY, KC6UY, KC4UY, KC4UE, KC8UE, KC8UY-HA, KC2UA, KC4UA, KC6UA, KC2UAH, KC4UAH, KC6UAH, as above, manufactured by Konica Minolta Co., Ltd.) is preferably used.

The thickness of the protective film is not particularly limited, but may be about 10 to 100 μm, preferably in the range of 10 to 80 μm, more preferably in the range of 10 to 60 μm, and particularly preferably in the range of 10 to 40 μm. is in the range of μm.

The protective film may further have other layers as needed, in addition to the main body of the film, such as a cellulose acylate film, for example. Examples of the other layers include an antireflection layer, an antistatic layer, a retardation layer, and a brightness enhancing film layer.

<Adhesive layer>

The adhesive layer may be a layer obtained by drying a completely saponified polyvinyl alcohol aqueous solution (water paste), or may be a layer of a cured product of an active energy ray-curable adhesive.

<Method for producing polarizing plate>

The polarizing plate of the present invention can be manufactured by bonding the laminated film of the present invention and a polarizer. The method of bonding the laminated|multilayer film of this invention and a polarizer is not specifically limited, After the said laminated|multilayer film is saponified, it can be performed using a completely saponified polyvinyl alcohol-type adhesive agent. Moreover, the method of bonding the laminated|multilayer film of this invention and a polarizer can also be performed using an active energy ray-curable adhesive agent etc. Bonding using an active energy ray-curable adhesive is preferable because the resulting adhesive layer has a high modulus of elasticity, easily suppresses deformation of the polarizing plate, and is highly resistant to fluctuations in the external environment (such as heat and humidity).

As active energy ray-curable adhesives for polarizing plates, photo-radical polymerization-type compositions using photo-radical polymerization, photo-cationic polymerization-type compositions using photo-cationic polymerization, and hybrid-type compositions using both photo-radical polymerization and photocationic polymerization are known.

Examples of the radically photopolymerizable composition include a composition containing a radically polymerizable compound containing a polar group such as a hydroxyl group or a carboxy group and a radically polymerizable compound not containing a polar group in a specific ratio described in Japanese Patent Laid-Open No. 2008-009329. It is known.

In particular, it is preferable that the radically polymerizable compound is a compound having an ethylenically unsaturated bond capable of radical polymerization. Preferable examples of the compound having an ethylenically unsaturated bond capable of radical polymerization include a compound having a (meth)acryloyl group. Examples of the compound having a (meth)acryloyl group include N-substituted (meth)acrylamide-based compounds, (meth)acrylate-based compounds, and the like. "(meth)acryloyl" means one or both of acryloyl and methacryloyl. The same applies to (meth)acrylamide and (meth)acrylate.

Further, as the photocationic polymerization type composition, as disclosed in Japanese Unexamined Patent Publication No. 2011-028234, (α) a cationically polymerizable compound, (β) a photocationic polymerization initiator, (γ) light with a wavelength longer than 380 nm an active energy ray-curable adhesive containing each component of a photosensitizer exhibiting maximum absorption and (δ) a naphthalene-based photosensitizer adjuvant. However, active energy ray-curable adhesives other than this may be used.

Hereinafter, an example of the manufacturing method of the polarizing plate using an active energy ray-curable adhesive agent is demonstrated. The polarizing plate is (1) a pre-treatment step in which the surface to which the polarizer of the laminated film is bonded is subjected to an adhesion-facilitating treatment, and (2) an adhesive application in which the active energy ray-curable adhesive is applied to at least one of the adhesive surfaces of the polarizer and the laminated film. Process, (3) a bonding process of bonding the polarizer and the optical film through the obtained adhesive layer, and 4) a manufacturing method including a curing process of curing the adhesive layer in a state in which the polarizer and the optical film are bonded through the adhesive layer can do. What is necessary is just to implement the pretreatment process of (1) as needed.

(pretreatment process)

In the pretreatment step, an adhesion-facilitating treatment is performed on the adhesive surface of the laminated film with the polarizer, for example, the surface of the laminated film on the substrate side. When bonding a laminated film and a protective film to both surfaces of the polarizer, respectively, an adhesion-facilitating treatment is performed on the adhesive surface of the protective film with the polarizer together with the laminated film. Examples of the adhesion-facilitating treatment include corona discharge treatment and plasma treatment.

(Adhesive application process)

In the adhesive application step, the active energy ray-curable adhesive is applied to at least one of the adhesive surfaces of the polarizer and the laminated film. When applying an active energy ray-curable adhesive directly to the surface of a polarizer or a laminated film, there is no particular limitation on the application method. For example, various coating methods such as doctor blade, wire bar, die coater, comma coater, and gravure coater can be used. Moreover, after cast|flow_spreading an active energy ray-curable adhesive agent between a polarizer and laminated|multilayer film, the method of pressurizing with a roller etc. and spreading it uniformly can also be used. Moreover, when a polarizing plate has a protective film, the said active energy ray-curable adhesive agent is similarly applied to at least one of the adhesive surfaces of a polarizer and a protective film.

(joining process)

After applying the active energy ray-curable adhesive in this way, it is applied to the bonding step. In this bonding process, for example, when an active energy ray-curable adhesive is applied to the surface of the polarizer in the previous application process, the laminated film is superimposed there. When the active energy ray-curable adhesive is applied to the surface of the laminated film in the previous application step, the polarizer is superposed thereon. Moreover, when cast|flow_spreading an active energy ray-curable adhesive agent between a polarizer and laminated|multilayer film, a polarizer and laminated|multilayer film overlap in the state.

In the case of bonding the laminated film and the protective film to both sides of the polarizer, when the active energy ray-curable adhesive is used on both sides, the laminated film and the protective film are superimposed on both sides of the polarizer via the active energy ray-curable adhesive, respectively. And usually, in this state, both sides (when the laminated film is superimposed on one side of the polarizer, the polarizer side and the laminated film side, and when the laminated film and the protective film are superimposed on both sides of the polarizer, the laminated film on both sides and protective film side) is picked up with a roller or the like and pressed. As for the material of the roller, it is possible to use metal, rubber, or the like. The rollers disposed on both surfaces may be of the same material or of different materials.

(curing process)

In the curing step, the uncured active energy ray-curable adhesive is irradiated with active energy rays to cure the adhesive layer to form an adhesive layer composed of a cured product of the active energy ray-curable adhesive. Thereby, the superimposed polarizer, the laminated film, and any protective film are bonded through the active energy ray-curable adhesive. When bonding laminated|multilayer film on one side of a polarizer, you may irradiate an active energy ray from either the polarizer side or the laminated|multilayer film side. Moreover, when bonding laminated|multilayer film and a protective film on both surfaces of a polarizer, respectively, in the state which laminated|stacked film and a protective film were superimposed on both surfaces of a polarizer via active energy ray-curable adhesives, respectively, an active energy ray was emitted from either film side. It is advantageous to simultaneously cure the active energy ray-curable adhesive on both sides by irradiation.

As the active energy ray, visible light, ultraviolet ray, X-ray, electron beam, etc. can be used, and since handling is easy and the curing speed is sufficient, electron beam or ultraviolet ray is generally preferably used.

As the irradiation conditions of the electron beam, any appropriate conditions can be employed as long as the adhesive can be cured. For example, electron beam irradiation has an accelerating voltage that is preferably in the range of 5 to 300 kV, more preferably in the range of 10 to 250 kV. When the accelerating voltage is less than 5 kV, the electron beam does not reach the adhesive and there is a risk of insufficient curing. When the accelerating voltage exceeds 300 kV, the penetrating force passing through the sample is too strong and the electron beam is repelled, causing damage to the laminated film, protective film and polarizer. There is a risk of giving damage. The irradiation dose is preferably in the range of 5 to 100 kGy, more preferably in the range of 10 to 75 kGy. When the irradiation dose is less than 5 kGy, the adhesive becomes insufficiently cured, and when it exceeds 100 kGy, damage is given to the laminated film, protective film and polarizer to cause a decrease in mechanical strength or yellowing, and predetermined optical properties cannot be obtained. There are cases.

As the irradiation conditions of the ultraviolet rays, any appropriate conditions can be employed as long as the conditions can cure the adhesive. The irradiation amount of the ultraviolet rays is preferably in the range of 50 to 1500 mJ/cm ² in terms of integrated light amount, and more preferably in the range of 100 to 500 mJ/cm ² .

In the polarizing plate obtained as described above, the thickness of the adhesive layer is not particularly limited, but is usually in the range of 0.01 to 10 μm, and preferably in the range of 0.5 to 5 μm.

[liquid crystal display device]

The liquid crystal display device of the present invention is characterized by comprising the polarizing plate of the present invention. The liquid crystal display device of the present invention can ensure good visibility by providing the polarizing plate of the present invention using the laminated film of the present invention.

The liquid crystal display device of the present invention has a configuration shown in Figs. 3 and 4, for example. Fig. 3 is a plan view of an example of the liquid crystal display device of the present invention, and Fig. 4 is a cross-sectional view taken along line X-X of the liquid crystal display device shown in Fig. 3 . The liquid crystal display device 100 shown in FIGS. 3 and 4 includes a liquid crystal panel 30, a first polarizing plate 20a disposed on the surface Sa on the viewing side of the liquid crystal panel 30, and the liquid crystal panel 30. It has a second polarizing plate 20b disposed on the surface Sb on the backlight side. The first polarizing plate 20a and the second polarizing plate 20b are polarizing plates of the present invention each having laminated films 10a and 10b of the present invention.

In addition, in the liquid crystal display device of the present invention, for example, it is preferable that at least the first polarizing plate of the first polarizing plate 20a and the second polarizing plate 20b is the polarizing plate of the present invention, and that both are polarizing plates of the present invention. more preferable

The liquid crystal panel 30 has two glass substrates G and a liquid crystal cell L arranged therebetween. The liquid crystal panel 30 has TN (Twisted Nematic) mode, STN (Super Twisted Nematic) mode, IPS (In-Plane Switching) mode, OCB (Optically Compensated Birefringence) mode, ECB (Electrically Controlled Birefringence) mode, VA (Vertical Alignment) mode (including MVA; Multi-domain Vertical Alignment or PVA; Patterned Vertical Alignment), HAN (Hybrid Aligned Nematic) mode, etc. can be preferably used. In order to increase contrast, VA (MVA, PVA) mode or IPS mode is preferable.

In a TN mode liquid crystal panel, when no voltage is applied, rod-shaped liquid crystalline molecules are substantially horizontally aligned and twisted at an angle of 60 to 120°. A TN mode liquid crystal panel is most often used as a color TFT liquid crystal display device, and is described in many literatures.

In a VA mode liquid crystal panel, rod-shaped liquid crystalline molecules are aligned substantially vertically when no voltage is applied.

In the VA-mode liquid crystal panel, (1) a VA-mode liquid crystal panel in a narrow sense in which rod-shaped liquid crystal molecules are aligned substantially vertically when no voltage is applied and substantially horizontally when voltage is applied (Japanese Patent Laid-Open Publication No. 2-176625), (2) a multi-domain (MVA mode) liquid crystal panel (SID97, Digest of Tech. Papers (preliminary collection) 28 (1997) 845 for widening the viewing angle) ), (3) a liquid crystal panel in a mode (n-ASM mode) in which rod-shaped liquid crystalline molecules are substantially vertically aligned when no voltage is applied and twisted multi-domain orientated when voltage is applied (Preliminary Collections 58 to 59 of the Japanese Liquid Crystal Discussion Society) (1998)) and (4) liquid crystal panels in SURVAIVAL mode (published at LCD International 98).

The OCB mode liquid crystal panel is a bend alignment mode liquid crystal panel in which rod-shaped liquid crystal molecules are aligned in substantially opposite directions (symmetrically) at the top and bottom of the liquid crystal panel, and are disclosed in U.S. Patent Nos. 4583825 and 5410422 respectively. disclosed in the specification. Since the rod-shaped liquid crystalline molecules are symmetrically aligned at the top and bottom of the liquid crystal panel, the liquid crystal panel in bend orientation mode has a magneto-optical compensation function. Therefore, this liquid crystal mode is called OCB (Optically Compensatory Bend) liquid crystal mode. A liquid crystal display device in a bend alignment mode has an advantage of a fast response speed.

The liquid crystal panel of the IPS mode is switched by applying a transverse electric field to the nematic liquid crystal, and in detail, Proc. IDRC (Asia Display 1995), p. 577-580 and i. p. 707-710.

In an ECB mode liquid crystal panel, rod-shaped liquid crystalline molecules are substantially horizontally aligned when no voltage is applied. The ECB mode is one of the liquid crystal display modes having the simplest structure, and details are described in, for example, Japanese Unexamined Patent Publication No. 5-203946.

The 1st polarizing plate 20a has the 1st laminated film 10a, the 1st polarizer 11a, and the 1st protective film 12a in order from the surface Sa on the visual side of the liquid crystal panel 30. The 1st laminated|multilayer film 10a has the base material 1 and the optical function layer 2, and the optical function layer 2 is bonded to the surface Sa of the visual recognition side of the liquid crystal panel 30.

The second polarizing plate 20b has a second laminated film 10b, a second polarizer 11b, and a second protective film 12b in order from the surface Sb on the backlight side of the liquid crystal panel 30. The 2nd laminated|multilayer film 10b has the base material 1 and the optical function layer 2, and the optical function layer 2 is bonded to the surface Sb of the backlight side of the liquid crystal panel 30.

It is preferable that the absorption axis of the first polarizer 11a and the absorption axis of the second polarizer 11b are orthogonal (cross nicol).

The liquid crystal panel 30 of the liquid crystal display device 100 has two glass substrates G and a liquid crystal cell L arranged therebetween. The liquid crystal cell L has, for example, a pair of alignment films between a pair of transparent electrodes, a liquid crystal layer between the alignment films, and a color filter inside the glass substrate G on the viewing side. .

The thickness of the glass substrate G is preferably in the range of 0.3 to 0.7 mm, and more preferably in the range of 0.3 to 0.5 mm. Since the polarizing plate of the present invention has a small dimensional change due to temperature and humidity, it is particularly preferably used for thin glass suitable for small and medium-sized mobile electronic devices.

In the liquid crystal display device 100, the surface Sa of the optical function layer 2 of the first laminated film 10a and the visual side surface Sa of the liquid crystal panel 30 and the optical function layer of the second laminated film 10b ( Bonding between the surface of 2) and the surface Sb on the backlight side of the liquid crystal panel 30 can be performed by a known method. In some cases, they may be bonded through an adhesive layer (not shown). As the adhesive layer, an adhesive layer obtained by the same active energy ray-curable adhesive as used in the production of the polarizing plate described above is preferable.

In the liquid crystal display device of the present invention, the effect of the present invention is more remarkable and preferable when it is an IPS mode type. A liquid crystal display device in which the polarizing plate of the present invention is used is a liquid crystal display device having excellent viewing angle characteristics and excellent visibility in which color unevenness and the like are suppressed by the action of the laminated film of the present invention.

Example

Hereinafter, the present invention will be described in detail with examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, "part by mass" or "mass %" is shown unless otherwise specified.

[Production of laminated film]

(1) Fabrication of base material

(1-1) Synthesis of cellulose acylate

As cellulose acylates, three types of cellulose acylates 1 to 3 having acyl groups, degree of acyl group substitution, and number average molecular weight (Mn) shown in Table 2 are prepared by the method described in Japanese Patent Laid-Open No. 10-45804 synthesized according to Further, cellulose acylates 1 and 2 are cellulose acylates corresponding to cellulose acylate (A), and cellulose acylate 3 is a cellulose acylate outside the scope of cellulose acylate (A).

(1-2) Synthesis of sugar esters

Sugar esters 1 to 5 in which the hydroxy group hydrogen atoms of the sugars shown in Table 3 were substituted with the acyl groups shown in Table 3 in the ratios shown in Table 3 were synthesized according to the above synthesis example (esterification reaction of sucrose with benzoic anhydride). Specifically, sugar esters 1, 2, and 5 were prepared by changing benzoic acid anhydride to acetic anhydride in the above synthesis example, performing an esterification reaction, and adjusting the esterification rate by a method similar to the above. Sugar ester 3 was prepared in the same manner as in the synthesis example above. Sugar ester 4 was prepared by changing sucrose to glucose and changing benzoic anhydride to acetic anhydride in the above Synthesis Example, performing an esterification reaction, and adjusting the esterification rate by the same method as described above.

Further, sugar esters 1 to 4 are sugar esters corresponding to sugar ester (B), and sugar ester 5 is a sugar ester outside the range of sugar ester (B).

(1-3) Fabrication of substrate

The base material for the laminated film was produced by the solution cast film forming method as follows.

(Preparation of dope)

Dope 1-9 of the composition shown in Table 4 was prepared. Specifically, first, solvent methylene chloride and ethanol were added to a pressurized dissolution tank. Cellulose acylate, sugar ester, and matting agent were added while stirring to a pressurized dissolution tank containing a solvent, and were completely dissolved and dispersed while heating and stirring. The mat agents shown in Table 4 are all 12% ethanol dispersions of Aerosil R812 (manufactured by Nippon Aerosil Co., Ltd.).

The obtained liquid was mixed with Azumi filter paper No. manufactured by Azumi filter paper. 244 to obtain dopes 1 to 9.

(production of base material 1)

Dope 1 prepared above was uniformly cast on a stainless steel band support at a temperature of 22°C and a width of 1.8 m using a belt casting apparatus. From the stainless band support body, the solvent was evaporated at 40 ° C. for 1 minute and then at 60 ° C. until the amount of residual solvent reached 20%, and peeled from the stainless steel band support body as Web 1 at a peel tension of 162 N / m.

Next, the peeled web 1 was evaporated at 35 ° C. to slit the solvent to a width of 1.6 m, and then, using a tenter stretching machine, the glass transition temperature of the substrate 1 was set to Tg (material constituting the substrate 1 as described above). Assuming Tg) measured by a substrate sample prepared in advance using , it was stretched 1.05 times the original width in the width direction (TD direction) at a temperature of (Tg + 20) ° C. At this time, the amount of residual solvent when the stretching by the tenter stretching machine was started was 4% by mass. Thereafter, drying was terminated while conveying the drying zone at 120°C and 140°C with a large number of rollers, and base material 1 was produced. The thickness of the substrate was 40 μm.

(Production of Substrates 2 to 9)

In the above, substrates 2 to 9 each having a thickness of 40 μm were prepared in the same manner except that dope 1 was changed to dopes 2 to 9.

(production of base material 10)

The prepared dope 1 was uniformly cast on a stainless steel band support at a temperature of 22°C and a width of 1.8 m using a belt casting apparatus. From the stainless band support body, the solvent was evaporated at 65 ° C. for 1 minute and then at 40 ° C. until the amount of residual solvent reached 20%, and the web 10 was peeled from the stainless steel band support body at a peeling tension of 162 N / m. Thereafter, in the production of the substrate 1, the web 10 was stretched and dried in the same manner as the web 1 was stretched and dried to produce a substrate 10 having a thickness of 40 μm.

<Optical characteristics of substrate>

For the substrates 1 to 10 obtained, a value T (slope T of the out-of-plane retardation) was calculated from the out-of-plane retardation R650 measured with light having a wavelength of 650 nm and the out-of-plane retardation R450 measured with light having a wavelength of 450 nm based on the above formula (1). saved The results are shown in Table 5 together with the composition of the material contained in each substrate. In addition, in the table|surface, the addition amount of sugar ester is the addition amount with respect to 100 mass parts of cellulose acylates.

(2) Synthesis of material for optical function layer

As the material for the optical function layer, fumaric acid ester polymers 1 to 3 were prepared.

<Synthesis Example 1>

In a 30 liter autoclave, 18 kg of distilled water containing 0.2% by mass of partially saponified polyvinyl alcohol, 3 kg of diisopropyl fumarate, and 7 g of dimethyl-2,2'-azobis isobutyrate as a polymerization initiator were charged, and the polymerization temperature was 50°C. , A suspension radical polymerization reaction was performed under conditions of a polymerization time of 24 hours. After filtration, the obtained particles were sufficiently washed with methanol and dried at 80°C to obtain diisopropyl fumarate homopolymer. The number average molecular weight of the obtained diisopropyl fumarate homopolymer was 160000. The diisopropyl fumarate homopolymer is a fumaric acid ester polymer in which 100% of the ester portion is isopropyl ester. The homopolymer of diisopropyl fumarate was referred to as fumaric acid ester polymer 1.

<Synthesis Example 2>

In a 1-liter reactor equipped with an agitator, cooling tube, nitrogen inlet tube and thermometer, 600 g of distilled water, 3.4 g of hydroxypropylmethylcellulose (Shin-Etsu Chemical Co., Ltd., trade name Metolose 60SH-50) as a dispersing agent, 350.9 g of diisopropyl fumarate , 49.1 g of diethyl fumarate (14.0 parts by mass relative to 100 parts by mass of diisopropyl fumarate) and 8.3 g of t-butylperoxypivalate as an oil-soluble radical initiator were added, followed by nitrogen bubbling for 1 hour, stirring at 400 rpm. Radical suspension polymerization was performed by holding at 50°C for 28 hours. After completion of the polymerization reaction, the contents were collected from the reactor, and the polymer was separated by filtration, washed twice with distilled water and twice with methanol, and dried under reduced pressure at 80°C (yield: 75%).

The number average molecular weight of the obtained fumaric acid ester copolymer was 138000. It was confirmed by 1H-NMR measurement that the obtained fumarate ester copolymer was a diisopropyl fumarate/diethyl fumarate copolymer having a diisopropyl fumarate polymerized unit/diethyl fumarate polymerized unit = 87/13 (mol%). That is, the obtained fumaric acid ester copolymer is a fumaric acid ester copolymer in which 87% of the ester portion is isopropyl ester. This fumaric acid ester copolymer was referred to as fumaric acid ester polymer 2.

<Synthesis Example 3>

In Synthesis Example 2, polymerization was carried out in the same manner as above except that the molar ratio of diisopropyl fumarate and diethyl fumarate used in the polymerization was changed to 7:3 as diisopropyl fumarate:diethyl fumarate, A diisopropyl fumarate/diethyl fumarate copolymer having a number average molecular weight of 140000 and a diisopropyl fumarate polymerized unit/diethyl fumarate polymerized unit = 70/30 (mol%) was obtained. That is, the obtained fumaric acid ester copolymer is a fumaric acid ester copolymer in which 70% of the ester portion is isopropyl ester. This fumaric acid ester copolymer was referred to as fumaric acid ester polymer 3.

(3) Production of laminated film

Using the substrates 1 to 10 and the fumaric acid ester polymers 1 to 3 prepared above, laminated films were produced as follows.

(Production of laminated film 1)

A coating solution was prepared as a 10% solution in which the fumaric acid ester polymer 1 obtained in Synthesis Example 1 was dissolved in a solution having a toluene:methylethylketone mass ratio of 1:1. The coating solution obtained on the substrate 1 was applied by a doctor blade method so that the layer thickness after drying was 2 μm, and dried to form an optical function layer to obtain laminated film 1.

(Preparation of Laminated Films 2 to 16)

In production of laminated film 1, laminated films 2 to 16 were produced in the same manner as above except that the type of base material, the type of fumaric acid ester polymer, and the thickness of the optical function layer were changed as shown in Table 6.

[Evaluation of laminated film]

About the obtained laminated films 1-16, the optical characteristic and interlayer adhesiveness were evaluated as follows. The results are shown in Table 6 together with the types of substrates and optical function layers used for production. In addition, in a table|surface, "isopropyl %" shows the ratio (%) occupied by the isopropyl ester in the ester part in a fumaric acid ester polymer.

(1) Optical properties

The ratio value Rth450/Rth550 of the out-of-plane retardation Rth450 measured with light having a wavelength of 450 nm and the out-of-plane retardation Rth550 measured with light having a wavelength of 550 nm was determined. In the table, Rth450/Rth550 and Rth550 are shown.

(2) Adhesion

The optical function layer in the laminated film was scratched with 11 vertical and horizontal scratches at intervals of 1 mm using an NT cutter to form a lattice pattern of 100 squares. On this, a cellophane adhesive tape (Cellotape (registered trademark) No. 405, 24 mm width, manufactured by Nichiban Co., Ltd.) was pasted, and a peeling test was conducted by pulling it quickly in the vertical (90°) direction. At this time, adhesion was evaluated according to the number of peeled lattice patterns according to the following evaluation criteria. In addition, the test was implemented in 23 degreeC and 55% RH environment.

(Evaluation standard)

◎: 100 squares left

○: The remaining number is 90 or more and 99 or less

×: Less than 89 squares left

[Production of Polarizing Plate]

Using the laminated films 1 to 16, a polarizer and a polarizing plate having a configuration having a laminated film on one side of the polarizer and a protective film on the other side were produced. In addition, the polarizer, the laminated film, and the protective film were bonded together using an active energy ray-curable adhesive.

(Production of polarizer)

A polyvinyl alcohol film having an average degree of polymerization of 2400 and a degree of saponification of 99.9 mol% and a thickness of 75 µm was immersed in 30°C warm water for 60 seconds to swell. Next, the obtained film was immersed in an aqueous solution of iodine/potassium iodide (mass ratio = 0.5/8) at a concentration of 0.3%, and dyed while stretching up to 3.5 times. Thereafter, the obtained film was stretched in a boric acid ester aqueous solution at 65°C so that the total draw ratio was 6 times. Then, the obtained film was dried in a 40 degreeC oven for 3 minutes, and a polarizer with a thickness of 25 micrometers was obtained.

(protective film)

As a protective film, KC2UA (product name, Konica Minolta Co., Ltd. product, cellulose acylate film) was prepared.

(Adhesive 1; Photo-radical polymerization type active energy ray-curable adhesive)

50 parts by mass of HEAA (hydroxyethyl acrylamide, manufactured by Koujin Co., Ltd.) and 50 parts by mass of HEA (2-hydroxyethyl acrylate, manufactured by Koujin Co., Ltd.) and 3 parts by mass of IRGACURE819, manufactured by BASF Japan, as an optical radical polymerization initiator. Partially mixed and stirred at 50°C for 1 hour to obtain adhesive 1.

(Production of polarizer 1)

Corona discharge treatment was performed on the surface of the substrate side of laminated film 1 and one surface of the protective film (KC2UA). The corona discharge treatment conditions were a corona output intensity of 2.0 kW and a line speed of 18 m/min. Next, the adhesive 1 prepared as described above was applied to the corona discharge treated surfaces of the laminated film 1 and the protective film with a bar coater so that the thickness of the adhesive layer after curing was 0.5 μm.

The laminated film 1 and the adhesive coated surface of the protective film are bonded to both surfaces of the polarizer produced as described above, and the laminated film 1/coated layer of adhesive 1/polarizer/coated layer of adhesive 1/protective film (KC2UA) A laminate was obtained. Using an ultraviolet irradiation device with a belt conveyor (the lamp uses a D valve manufactured by Fusion UV Systems Co., Ltd.) from both sides of the laminated body, ultraviolet rays are irradiated so that the integrated light amount is 750 mJ/cm ² , and the adhesive 1 is coated. The layer was cured to obtain Polarizer 1 as an adhesive layer.

(Production of polarizers 2 to 16)

Except having used the laminated films 2-16 instead of the laminated film 1, it carried out similarly to the polarizing plate 1, and produced the polarizing plates 2-16.

[Production of liquid crystal display device]

A liquid crystal display device was produced using the polarizing plates 1 to 16 prepared above. Specifically, Hitachi IPS mode liquid crystal television Wooo W32-L7000 was prepared. A schematic cross-section of the liquid crystal television has the configuration shown in FIG. 4, and in the liquid crystal television, polarizers on both the viewer side and the backlight side bonded to the glass substrate surface of the liquid crystal panel were peeled off. Two polarizing plates 1 produced as described above were prepared, and the optical function layer surface of the laminated film of each polarizing plate 1 was bonded to the glass substrate surface on the viewer side and backlight side of the liquid crystal panel, respectively, to prepare a liquid crystal display device 1. . In the case of bonding, the absorption axes of the two polarizing plates 1 are bonded so that the absorption axes of the two polarizing plates bonded to the used liquid crystal television and the visual side and the backlight side are in the same direction, respectively, so that the liquid crystal display device 1 was produced. It carried out similarly to the above using the polarizing plates 2-16, and produced the liquid crystal display devices 2-16.

[evaluation]

Regarding the obtained liquid crystal display devices 1 to 16, when the power supply of the liquid crystal display device was turned on and a white image was projected, color unevenness and left and right color difference were evaluated as follows, and visibility from an angle was evaluated. The results are shown in Table 7.

(1) Uneven color

The color was confirmed by visually observing the screen of the white image from 45° right and 45° left toward the viewing side of the liquid crystal display device. Each of the left and right was evaluated according to the following criteria.

(Evaluation standard)

◎: No unevenness was observed at all.

○: Although slight unevenness is observed, there is no problem in visibility.

x: Non-uniformity is seen and there is a problem in visibility.

(2) Left and right color difference

The left and right color difference when the color was confirmed by visually observing the screen of a white image from 45° right and 45° left toward the viewing side of the liquid crystal display device was evaluated according to the following criteria.

(Evaluation standard)

◎: There is no left or right difference in color.

○: There is a slight left-right difference in color, but it is not bothered.

×: There is a difference in color tone (for example, it appears blue when viewed from the right 45°, and appears red when viewed from the left 45°).

From Table 6 and Table 7, while the laminated|multilayer film of this invention has favorable interlayer adhesiveness, it turns out that the liquid crystal display device using the polarizing plate provided with this can ensure good visibility.

According to the present invention, in the retardation film having a fumaric acid ester-based resin layer, it is possible to provide a laminated film having good interlayer adhesion and ensuring good visibility in a liquid crystal display using the same, and a polarizing plate using the laminated film. can Moreover, the liquid crystal display device which can ensure good visibility can be provided by using this laminated|multilayer film.

10, 10a, 10b: laminated film
1: Substrate
2: optical functional layer
20, 20a, 20b: polarizer
11, 11a, 11b: polarizer
12, 12a, 12b: protective film
100: liquid crystal display
30: liquid crystal panel
G: glass plate
L: liquid crystal cell

Claims (4)

A laminated film comprising a substrate and an optical function layer,
The base material contains a cellulose acylate having an acyl group substitution degree in the range of 2.6 to 3.0, and a sugar ester in which hydrogen atoms in 70 to 100% of the hydroxy groups are substituted with acyl groups,
For the above substrate, the value T obtained based on the following formula (1) from the out-of-plane retardation R650 measured with light with a wavelength of 650 nm and the out-of-plane retardation R450 measured with light with a wavelength of 450 nm is in the range of 0.040 to 0.055,
Equation (1) T=(R650-R450)/(650-450)
The optical function layer contains a polymer containing fumaric acid ester polymerized units in an amount of 90 mol% or more with respect to all polymerized units, and 80 to 100% of the ester portion of the fumaric acid ester polymerized units is isopropyl ester,
The value of the ratio Rth450 / Rth550 of the out-of-plane retardation Rth450 measured with light with a wavelength of 450 nm and the out-of-plane retardation Rth550 measured with light with a wavelength of 550 nm with respect to the laminated film is within the range of 1.1 to 1.9. According to claim 1,
A laminated film in which an out-of-plane retardation Rth550 measured with light having a wavelength of 550 nm for the laminated film is within a range of -30 to -15nm. A polarizing plate formed by laminating the laminated film according to claim 1 or 2 and a polarizer. A liquid crystal display device provided with the polarizing plate according to claim 3.

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