Laminated film, polarizing plate, and liquid crystal display device

Abstract

The present application relates to a laminated film comprising a substrate and an optical functional layer, the substrate comprising a cellulose acylate having an acyl substitution degree of 2.6 to 3.0 and a sugar ester in which 70 to 100% of hydroxyl groups are substituted with acyl groups, the optical functional layer containing a polymer containing a polymerization unit of a fumaric acid ester at a proportion of 90% by mole or more, 80 to 100% of the ester portion of the polymerization unit of the fumaric acid ester being isopropyl ester, the laminated film having an out-of-plane phase difference based on a wavelength of 650 nm and a wavelength of 450 nm, and a slope of 0.040 to 0.055, and a ratio of the out-of-plane phase difference based on a wavelength of 450 nm and a wavelength of 550 nm of 1.1 to 1.9.

Description

Technical Field

[0001] This invention relates to multilayer films, polarizers, and liquid crystal display devices. More specifically, this invention relates to multilayer films that provide good interlayer adhesion in retardation films having fumarate resin layers, and to multilayer films that ensure good visual legibility in liquid crystal display devices using such multilayer films, as well as polarizers and liquid crystal display devices incorporating such multilayer films. Background Technology

[0002] Liquid crystal display (LCD) devices have become widely used in society, from televisions to computers and mobile phones, serving as essential equipment. In recent years, various optical compensation films have been used to improve the display characteristics of LCD devices, resulting in increased viewing angles, improved color matching, and enhanced contrast. Among these, films composed of fumarate resins or containing fumarate resin layers have been proposed as retardation films with negative refractive indices (see, for example, Patent Document 1).

[0003] However, it has been found that in liquid crystal display devices with a phase retardation film made of fumarate resin or formed by laminating fumarate resin layers on a substrate on the liquid crystal panel side of the polarizer, there are problems with visual recognition due to uneven color matching when the display device is viewed from an oblique angle. There is a color matching difference when viewed from the left and right, and interlayer delamination occurs in the phase retardation film obtained by laminating fumarate resin layers on a substrate.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent No. 5245109 Summary of the Invention

[0007] The technical problem solved by the invention

[0008] The present invention was made in view of the aforementioned problems and circumstances, and solves the problem by providing a multilayer film with good interlayer adhesion in a phase retardation film having a fumarate resin layer, and a polarizer using the multilayer film in a liquid crystal display device. Furthermore, by using the multilayer film, a liquid crystal display device that ensures good visual clarity is provided.

[0009] Technical means to solve the problem

[0010] In the process of exploring the causes of the aforementioned problems in order to solve them, the inventors discovered that by combining specific cellulose acylates and glycolipids in the constituent materials of the substrate, and by defining a specific range for the value T (the slope of the out-of-plane phase difference in the wavelength range of 450 to 650 nm) obtained by using a specific formula based on the out-of-plane phase difference R650 measured with light at a wavelength of 650 nm and the out-of-plane phase difference R450 measured with light at a wavelength of 450 nm, and by setting the ratio Rth450 / Rth550 of the out-of-plane phase difference Rth450 measured with light at a wavelength of 450 nm and the out-of-plane phase difference Rth550 measured with light at a wavelength of 550 nm in the laminated film containing these substrates and optical functional layers, a laminated film with good interlayer adhesion and good visual recognition in liquid crystal display devices using it is obtained, thus completing the present invention.

[0011] That is, the problem described in this invention is solved by the following means.

[0012] 1. A laminated film comprising a substrate and an optical functional layer, wherein,

[0013] The substrate comprises: a cellulose acylate with an acyl substitution degree in the range of 2.6 to 3.0, and a sugar ester in which 70% to 100% of the hydrogen atoms of the hydroxyl groups are replaced by acyl groups.

[0014] Based on the out-of-plane phase difference R650 measured with light at a wavelength of 650 nm and the out-of-plane phase difference R450 measured with light at a wavelength of 450 nm, the value T obtained based on the following formula (1) is in the range of 0.040 to 0.055.

[0015] Equation (1) T=(R650-R450) / (650-450)

[0016] The optical functional layer contains a polymer of fumarate polymers comprising fumarate polymers at a ratio of 90 mol% or more relative to all polymer units, wherein 80-100% of the ester portion of the fumarate polymer units is isopropyl ester.

[0017] The ratio of the out-of-plane phase difference Rth450 measured with light at a wavelength of 450 nm to the out-of-plane phase difference Rth550 measured with light at a wavelength of 550 nm, Rth450 / Rth550, is in the range of 1.1 to 1.9.

[0018] 2. The laminated film according to claim 1, wherein,

[0019] The out-of-plane phase difference Rth550 of the laminated film, measured with light at a wavelength of 550 nm, is within the range of -30 to -15 nm.

[0020] 3. A polarizer formed by laminating a multilayer film as described in claim 1 or claim 2 with a polarizing lens.

[0021] 4. A liquid crystal display device, comprising:

[0022] The polarizer described in item 3.

[0023] Invention Effects

[0024] By means of the present invention, it is possible to provide: a phase retardation film having good interlayer adhesion in which a fumarate resin layer is formed, and a multilayer film in a liquid crystal display device using the multilayer film that ensures good visual legibility, and a polarizer using the multilayer film. Furthermore, by using the multilayer film, it is possible to provide a liquid crystal display device that ensures good visual legibility.

[0025] Although the mechanism of action or effect of the present invention is not clearly defined, it is speculated as follows.

[0026] Hypothesis: In a liquid crystal display device with a polarizer consisting of a phase retardation film with a fumarate resin layer and a polarizing mirror on the visually observable side of the liquid crystal panel, light transmitted from the backlight through the polarizing mirror and the liquid crystal panel is optically compensated by the phase retardation film of the polarizer, causing interference with internally reflected and surface-reflected light, resulting in color non-uniformity when the liquid crystal display device is viewed at an oblique angle. Therefore, it can be considered that color non-uniformity can be suppressed by controlling the wavelength dispersion of the out-of-plane phase difference (hereinafter, the out-of-plane phase difference of the phase retardation film is denoted as "Rth").

[0027] Therefore, it was discovered that by combining the fumarate resin layer with the substrate, and setting the ratio Rth450 / Rth550 of the out-of-plane phase difference Rth450 measured with light at a wavelength of 450 nm to the out-of-plane phase difference Rth550 measured with light at a wavelength of 550 nm within the range of 1.1 to 1.9, the problem of color inhomogeneity when viewed from an oblique angle can be eliminated.

[0028] Furthermore, in order to adjust the wavelength dispersion of Rth (Rth450 / Rth550) to the aforementioned range, the out-of-plane phase difference (hereinafter, the out-of-plane phase difference of the substrate is referred to as "R") in the substrate combined with the fumarate resin layer is adjusted by the following configuration. Specifically, the constituent material of the substrate is configured as follows: a combination of cellulose acylate with an acyl substitution degree in the range of 2.6 to 3.0 and a sugar ester in which 70% to 100% of the hydrogen atoms of the hydroxyl groups are replaced by acyl groups, wherein the out-of-plane phase difference R650 measured with light at a wavelength of 650 nm and the out-of-plane phase difference R450 measured with light at a wavelength of 450 nm, the value T obtained based on the above formula (1) is in the range of 0.040 to 0.055.

[0029] Furthermore, the adhesion between the fumarate resin layer and the substrate can be achieved by setting the proportion of isopropyl ester in the ester portion of the fumarate polymer unit in the fumarate resin to 80% or more and the proportion of ester substitution of hydroxyl groups in the sugar ester on the substrate side to 70% or more. This is because the aforementioned configuration increases the permeability and interaction between the fumarate resin layer and the substrate. Attached Figure Description

[0030] [ Figure 1 [A cross-sectional view showing an example of the laminated film of the present invention]

[0031] [ Figure 2 [A cross-sectional view showing an example of the polarizer of the present invention]

[0032] [ Figure 3 A top view of an example of the liquid crystal display device of the present invention.

[0033] [ Figure 4 ] Figure 3 Cross-sectional view of the liquid crystal display device at line XX. Detailed Implementation

[0034] The laminated film of the present invention is a laminated film comprising a substrate and an optical functional layer, wherein the substrate comprises: a cellulose acylate with an acyl substitution degree in the range of 2.6 to 3.0, and a glycol ester in which 70% to 100% of the hydrogen atoms of the hydroxyl groups are substituted with acyl groups. Based on the out-of-plane phase difference R650 measured with light at a wavelength of 650 nm and the out-of-plane phase difference R450 measured with light at a wavelength of 450 nm, the value T obtained based on the above formula (1) is 0.040 to 0.05. Within the range of 5, the optical functional layer contains a polymer in which fumarate is contained in a polymeric unit at a proportion of 90 mol% or more relative to all polymeric units, wherein 80 to 100% of the ester portion of the fumarate polymeric unit is isopropyl ester, and the ratio Rth450 / Rth550 of the out-of-plane phase difference Rth450 measured with light at a wavelength of 450 nm and the out-of-plane phase difference Rth550 measured with light at a wavelength of 550 nm is in the range of 1.1 to 1.9. This feature is a common technical feature of the following embodiments.

[0035] As an embodiment of the present invention, from the viewpoint of the performance of the present invention, it is preferable that the out-of-plane phase difference Rth550 measured by light with a wavelength of 550 nm for the stacked film is in the range of -30 to -15 nm.

[0036] The polarizer of the present invention is formed by laminating the multilayer film of the present invention with a polarizing mirror. The liquid crystal display device of the present invention includes the polarizer of the present invention.

[0037] The present invention, its constituent elements, and specific embodiments and forms will be described in detail below. It should be noted that, in this application, "~" means that the numerical values ​​preceding and following it are considered as a lower and upper limit value.

[0038] [Summary of the laminated film of the present invention]

[0039] The laminated film of the present invention is a laminated film comprising a substrate and an optical functional layer, wherein the substrate satisfies (1-1) and (1-2) below, the optical functional layer satisfies (2) below, and the laminated film satisfies (3) below.

[0040] (1-1) The substrate comprises: a cellulose acylate with an acyl substitution degree in the range of 2.6 to 3.0, and a sugar ester in which 70 to 100% of the hydrogen atoms of the hydroxyl groups are replaced by acyl groups.

[0041] (1-2) The value T obtained based on the following formula (1) is in the range of 0.040 to 0.055, according to the out-of-plane phase difference R650 measured with light at a wavelength of 650 nm and the out-of-plane phase difference R450 measured with light at a wavelength of 450 nm.

[0042] Equation (1) T=(R650-R450) / (650-450)

[0043] It should be noted that the value T obtained based on the above equation (1) is: the value of 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 phase difference for the substrate. Hereinafter, the value T obtained based on the above equation (1) based on the out-of-plane phase difference R650 measured with light at a wavelength of 650 nm and the out-of-plane phase difference R450 measured with light at a wavelength of 450 nm is also called "the slope T of the out-of-plane phase difference".

[0044] (2) The optical functional layer contains a polymer of a polymeric unit comprising a fumarate in a proportion of more than 90 mol% relative to all polymeric units, wherein 80 to 100% of the ester portion of the fumarate polymeric unit is isopropyl ester.

[0045] (3) The ratio of the out-of-plane phase difference Rth450 measured with light of wavelength 450 nm to the out-of-plane phase difference Rth550 measured with light of wavelength 550 nm, Rth450 / Rth550, is in the range of 1.1 to 1.9.

[0046] The laminated film of the present invention is a laminated film comprising a substrate and an optical functional layer. The laminated film of the present invention may include layers other than the substrate and the optical functional layer, to the extent that it does not impair the effects of the present invention. Figure 1 A cross-sectional view showing an example of the laminated film of the present invention. Figure 1 The laminated film 10 shown has an optical functional layer 2 on the main surface of one side of the film-shaped substrate 1.

[0047] The laminated film 10 of the present invention may, for example, have an adhesive layer between the substrate 1 and the optical functional layer 2. The substrate 1 may be composed of a single layer (monolayer) or multiple layers; from the viewpoint of less display non-uniformity and thinner profile, a single layer is preferred. Hereinafter, the constituent elements of the laminated film of the present invention will be described in detail.

[0048] (Substrate)

[0049] The substrate comprises a cellulose acylate (hereinafter also referred to as "cellulose acylate (A)") with an acyl substitution degree in the range of 2.6 to 3.0 and a glycol ester (hereinafter also referred to as "glycoester (B)") in which 70% to 100% of the hydrogen atoms of the hydroxyl groups are replaced by acyl groups. The substrate may, as needed and without impairing the effects of the present invention, contain other components besides cellulose acylate (A) and glycol ester (B).

[0050] <Cellulose Acyl (A)>

[0051] The substrate contains cellulose acylate (A). Cellulose acylate (A) is preferably contained as a major component in the substrate. It should be noted that "major component" refers to the presence of cellulose acylate (A) in the substrate at a concentration of 50% by mass or more. The concentration of 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 concentration of cellulose acylate (A) in the substrate is the remaining amount after removing other constituent components, preferably around 99% by mass, more preferably 90% by mass.

[0052] Cellulose acylates are compounds in which the hydrogen atoms of the hydroxyl groups in cellulose are replaced by acyl groups. The degree of substitution is a value representing the average number of hydroxyl groups among the three hydroxyl groups in each β-glucose residue that is a building block of cellulose.

[0053] The acyl group in the cellulose acylated compound (A) is not particularly limited as long as it is represented by RC (=O)- (R is a monovalent hydrocarbon group). For example, R is preferably an aliphatic hydrocarbon group with 1 to 5 carbon atoms, and R is preferably an acetyl group of methyl, a propionyl group of ethyl, or a butyryl group of propyl.

[0054] Cellulose acylate (A) may have one or more acyl groups. Preferably, cellulose acylate (A) has only one acyl group, and this one group is preferably an acetyl group. The degree of substitution of the acyl group in cellulose acylate (A) can be determined based on ASTM-D817-96.

[0055] The degree of acyl substitution in the cellulose acylate (A) is 2.6 to 3.0, preferably 2.8 to 3.0. The cellulose acylate can be manufactured, for example, by the method described later. Regarding the cellulose acylate (A), in the cellulose acylate obtained therefrom, two or more cellulose acylates with different degrees of acyl substitution can be mixed and adjusted to 2.6 to 3.0, preferably 2.8 to 3.0.

[0056] From the viewpoint of maintaining the mechanical strength of the substrate under tension, the weight-average molecular weight (Mw) of the cellulose acylate (A) is preferably in the range of 80,000 to 300,000, and more preferably in the range of 120,000 to 250,000. When it is within this range, it is easy to control the phase retardation (phase difference) based on tension during the film formation of the substrate. Therefore, it is easy to satisfy the conditions (1-2) in the substrate.

[0057] The number-average molecular weight (Mn) of the cellulose acylate (A) is preferred from the viewpoint of obtaining a matrix with high mechanical strength, as it ranges from 30,000 to 150,000. Furthermore, a number-average molecular weight of 40,000 to 100,000 is preferred.

[0058] The ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn) of cellulose acylate (A) (Mw / Mn) is preferably in the range of 1.4 to 3.0.

[0059] The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of cellulose acylate (A) can be determined, for example, using gel permeation chromatography (GPC). The determination conditions are as follows.

[0060] Solvent: dichloromethane

[0061] Columns: Shodex K806, K805, K803G (manufactured by Showa Denko Co., Ltd., used for 3-pin connection)

[0062] Column temperature: 25℃

[0063] Sample concentration: 0.1% by mass

[0064] Detector: RI Model 504 (manufactured by GLSCIENCE)

[0065] Pump: L6000 (manufactured by Hitachi, Ltd.)

[0066] Flow rate: 1.0 ml / minute

[0067] Calibration curves: Calibration curves were obtained using 13 samples of standard polystyrene (STK standard polystyrene, manufactured by TOSOH Corporation) with Mw = 1,000,000 to 500. The 13 samples were used at approximately equal intervals.

[0068] The cellulose acylate (A) used in this invention can be derived from wood pulp or cotton linter. The wood pulp can be from coniferous or broadleaf trees, more preferably coniferous trees. From the viewpoint of peelability during film formation, cotton linter is preferred. The cellulose acylates obtained from these can be suitably mixed or used alone.

[0069] For example, it can be used with a ratio of cellulose acylate from cotton lint: cellulose acylate from wood pulp (coniferous trees): cellulose acylate from wood pulp (broadleaf trees) of 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, or 40:30:30.

[0070] The cellulose acylated compound (A) of the present invention can be manufactured by known methods. Generally, cellulose, a given organic acid (acetic acid, propionic acid, etc.), an acid anhydride (acetic anhydride, propionic anhydride, etc.), and a catalyst (sulfuric acid, etc.) are mixed to esterify the cellulose, reacting until a cellulose trimer is obtained. In the trimer, the three hydroxyl groups of the glucose unit are replaced by the acyl groups of the organic acid. When two organic acids are used simultaneously, mixed ester-type cellulose acylated compounds can be prepared, such as cellulose acetate propionate and cellulose acetate butyrate.

[0071] Next, the cellulose triester is hydrolyzed as needed to obtain cellulose acylate (A) with the desired degree of acyl substitution (2.6–3.0). Then, after filtration, precipitation, washing, dehydration, and drying, cellulose acylate (A) is obtained.

[0072] The cellulose acylated product (A) of the present invention is preferably added to 1 g to 20 ml of pure water (with a conductivity of less than 0.1 μS / cm and a pH of 6.8) and stirred at 25°C for 1 hr under a nitrogen atmosphere, with a pH range of 6 to 7 and a conductivity range of 1 to 100 μS / cm.

[0073] The cellulose acylated compound (A) of the present invention can be synthesized by referring to the method described in Japanese Patent Application Publication No. 10-45804.

[0074] <Glycoesters (B)>

[0075] The substrate of the laminated film of the present invention contains sugar esters (B) other than cellulose acylates (A).

[0076] The sugar moiety in the sugar ester (B) of the present invention is preferably a residue of a sugar having at least one of 1 to 12 pyranose rings or furanose rings. That is, the sugar ester (B) is preferably a compound obtained by esterification of a sugar having at least one of 1 to 12 pyranose rings or furanose rings. The esterified sugar can be a monosaccharide or a polysaccharide composed of 2 to 12 linked sugar structures.

[0077] A sugar ester (B) is a sugar ester in which 70% to 100% of the hydrogen atoms of the hydroxyl groups in the sugar are replaced by acyl groups. In other words, a sugar ester (B) is a compound in which at least 70% of the OH groups in the sugar of the raw material have been esterified. Hereinafter, in a sugar ester (B), the proportion in which the hydrogen atoms of the hydroxyl groups in the sugar of the raw material are replaced by acyl groups, that is, the proportion in which the OH groups are esterified, is called the "esterification rate".

[0078] Regarding the esterification rate of the sugar ester (B), it is preferably 75% or more of the OH groups present in the pyranose ring or furanose ring, more preferably 100%. By making the esterification rate of the sugar ester (B) 70% or more, good adhesion is obtained between the substrate and the optical functional layer stacked on the substrate.

[0079] The proportion of sugar ester (B) in the substrate of the present invention is preferably 1 to 30 parts by mass relative to 100 parts by mass of cellulose acylate (A), more preferably 5 to 20 parts by mass. By keeping the proportion of sugar ester (B) within the aforementioned range, the phase retardation value in the substrate is controlled, and the conditions described in (1-2) are easily satisfied.

[0080] Examples of sugars in the raw materials of the sugar ester (B) include: glucose, galactose, mannose, fructose, xylose or arabinose, lactose, sucrose, fructotetraose, 1F-fructofuranosyl naisesose, stachyose, maltitol, lactitol, lactulose, cellobiose, maltose, cellotriose, maltotriose, raffinose, and fructotriose. Furthermore, examples of sugars in the raw materials of the sugar ester (B) also include: gentiobiose, gentiotetraose, xylitol, galactoside sucrose, etc. The sugars in the raw materials of the sugar ester (B) particularly preferably contain both pyranose rings and furanose rings.

[0081] Preferred examples of sugars in the raw materials of the sugar ester (B) are: glucose, sucrose, fructotriose, fructotetraose, 1F-fructofuranosyl naisesose, stachyose, etc., with glucose and sucrose being preferred, and sucrose being even more preferred.

[0082] In sugar esters (B), 70-100% of the hydrogen atoms in the OH group of the raw sugar are replaced by acyl groups. There are no particular limitations on the acyl group, as long as it is represented by RC (=O)- (R is a monovalent hydrocarbon group). R can be an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, or an aromatic hydrocarbon group.

[0083] Sugar esters (B) are, for example, compounds in which a monocarboxylic acid, represented by RC(=O)-OH (R as described above), is esterified to introduce the acyl group into the sugars exemplified above. The monocarboxylic acid used for esterification is not particularly limited; known aliphatic monocarboxylic acids, alicyclic monocarboxylic acids, aromatic monocarboxylic acids, etc., can be used. One monocarboxylic acid can be used alone or in combination of two or more.

[0084] Preferred examples of aliphatic monocarboxylic acids include: acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, 2-ethylhexanecarboxylic acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid, nonadecanoic acid, arachidic acid, benzyl acid, lignochloropic acid, ceric acid, heptadecanoic acid, limonene oleic acid, triacontanoic acid, laccosinate, and other saturated fatty acids; unsaturated fatty acids such as undecenoic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid, and octenic acid.

[0085] Preferred examples of alicyclic monocarboxylic acids include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid, and their derivatives.

[0086] Preferred examples of aromatic monocarboxylic acids include: aromatic monocarboxylic acids having an alkyl or alkoxy group introduced into the benzene ring of benzoic acids such as benzoic acid and toluene, cinnamic acid, diphenylethanolic acid, biphenylcarboxylic acid, naphtholic acid, tetrahydronaphtholic acid, and other aromatic monocarboxylic acids having two or more benzene rings, and their derivatives.

[0087] Examples of aromatic monocarboxylic acids, more specifically, include: xylene, hemellitic acid, xylenecarboxylic acid, 2,3,4-trimethylbenzoic acid, γ-isocyanate, dextrin, 2,4,6-trimethylbenzoic acid, α-isocyanate, cuminic acid, α-toluic acid, hydrogenated atropine, atropine, hydrocinnamic acid, salicylic acid, o-anisinic acid, m-anisinic acid, p-anisinic acid, creosotenic acid, o-homosalicylic acid, m-homosalicylic acid, p-homosalicylic acid, o-pyrocatechinic acid, β-dihydroxybenzoic acid, vanillic acid, isovanillic acid, veratrile acid, o-veratrile acid, gallic acid, asaric acid, mandelic acid, 4-methoxyphenylacetic acid, homovanillic acid, homoveratrile acid, o-homoveratrile acid, 2-(formylcarbonyl)benzoic acid, p-coumaric acid; benzoic acid is particularly preferred.

[0088] As the glycol ester (B) in this invention, an ester compound of oligosaccharide can also be used, provided that the esterification rate is met. Oligosaccharides can be manufactured, for example, by the action of enzymes such as amylase on starch, sucrose, etc. Preferred examples of oligosaccharides include: maltodextrin, isomaltodextrin, fructooligosaccharides, galactooligosaccharides, and xylooligosaccharides.

[0089] Examples of sugar esters (B) include esters of compounds obtained by condensing 1 to 12 of at least one pyranose ring or furanose ring having the structure represented by the following general formula (B).

[0090] [Chemical Formula 1]

[0091]

[0092] R in general formula (B) 11 ~R 15 R 21 ~R 25 This represents an acyl group or hydrogen atom with 2 to 22 carbon atoms. m and n are integers from 0 to 12, and m+n is an integer from 1 to 12. In general formula (B), relative to R... 11 ~R 15 and R 21 ~R 25 The total number of acyl groups is 70% to 100% of the total number of carbon atoms, with acyl groups having 2 to 22 carbon atoms.

[0093] As the acyl group, it is preferably R 26 -C(=O)-(R 26An acyl group representing a structure consisting of an aliphatic saturated hydrocarbon group having 1 to 21 carbon atoms, or an acyl group consisting of a phenyl or benzyl group having 6 to 20 carbon atoms and optionally having substituents. Preferably, R... 26 The acetyl group of methyl, R 26 It is a benzoyl group of phenyl, and is particularly preferably an acetyl group.

[0094] Substituents present in phenyl or benzyl groups include, for example, alkyl, alkenyl, alkoxy, and phenyl groups, and these alkyl, alkenyl, and phenyl groups may also have substituents. Oligosaccharide ester compounds can also be manufactured using the same methods as other glycoesters.

[0095] Specific examples of the sugar esters (B) of the present invention are given below, but the invention is not limited thereto. In the compounds whose structures are indicated below, in compounds where "average degree of substitution" is not shown below the substituent (acyl group), it indicates that 100% of the hydrogen atoms of the OH group of the sugar are substituted by that substituent. Sugar esters (B) in which more than 70% of the hydrogen atoms of the OH group are substituted by acyl groups are also preferred. For example, in compound 1, compounds in which less than 30% of R1 consists of hydrogen atoms also fall into the category of sugar esters (B).

[0096] In compounds whose structures are described below, where "average degree of substitution" is displayed below the substituent (acyl group), it indicates that the hydrogen atoms of the OH group of the sugar are substituted by the substituent (acyl group) to that degree. For example, in compound 3, the average degree of substitution is 7.0, indicating that 7 out of 8 R3 groups are substituted by 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 8 R3 groups are substituted by benzoyl groups. 12 All groups are replaced by benzoyl groups. In this case, the esterification rate is 8 / 8 = 100%.

[0097] [Chemical Formula 2]

[0098]

[0099] [Chemical Formula 3]

[0100]

[0101] [Chemical Formula 4]

[0102]

[0103] [Chemical Formula 5]

[0104]

[0105] [Chemical Formula 6]

[0106]

[0107] [Chemical Formula 7]

[0108]

[0109] [Chemical Formula 8]

[0110]

[0111] [Chemical Formula 9]

[0112]

[0113] The sugar ester (B) of the present invention can be manufactured by reacting the sugar, for example, a sugar having at least one of 1 to 12 pyranose rings or furanose rings, with an acylating agent (also called an esterifying agent). Examples of acylating agents include, for example, acyl halides or anhydrides of the various monocarboxylic acids mentioned above. Specifically, when the acyl group is acetyl, examples include acetyl chloride, acetic anhydride, etc., and when the acyl group is benzoyl, examples include benzyl chloride, benzoic anhydride, etc.

[0114] In the esterification of sugars, the degree of substitution and esterification rate of the resulting sugar esters exhibit slightly different distributions between molecules. The distribution of the degree of substitution and esterification rate of sugar esters can be adjusted by the amount of acylating agent, the timing of its addition, and the esterification reaction time. By mixing sugar esters with different degrees of substitution and esterification rates, or by mixing compounds with purely separated degrees of substitution and esterification rates, sugar esters (B) with a target esterification rate (70–100%) can be prepared. The following example illustrates the esterification of sucrose via benzoic anhydride, and the adjustment of the esterification rate is explained in detail.

[0115] (Synthetic Example: Synthesis of the Glycoester (B) of the Present Invention)

[0116] [Chemical Formula 10]

[0117]

[0118] Exemplary compound A-1

[0119] Exemplary compound A-2

[0120] Exemplary compound A-3

[0121] Exemplary compound A-4

[0122] Exemplary compound A-5

[0123] The esterification reaction of sucrose based on benzoic anhydride proceeds as follows. That is, 34.2 g (0.1 mol) of sucrose, 135.6 g (0.6 mol) of benzoic anhydride, and 284.8 g (3.6 mol) of pyridine are placed in a four-neck flask equipped with a stirring device, a reflux condenser, a thermometer, and a nitrogen inlet tube. While stirring, nitrogen is bubbled through the nitrogen inlet tube and the temperature is raised, and an esterification reaction is carried out at 70 °C for 5 hours.

[0124] Next, the pressure inside the flask is reduced to 4×10 2 Pa or less, and after distilling off the excess pyridine at 60 °C, the pressure inside the flask is reduced to 1.3×10 Pa or less, the temperature is raised to 120 °C, and most of the benzoic anhydride and the generated benzoic acid are distilled off. And then, 1 L of toluene and 300 g of a 0.5 mass% aqueous sodium carbonate solution are added, stirred at 50 °C for 30 minutes, then allowed to stand, and the toluene layer is separated. Finally, 100 g of water is added to the separated toluene layer, washed with water at room temperature for 30 minutes, the toluene layer is separated, and toluene is distilled off under reduced pressure (4×10 2 Pa or less) at 60 °C to obtain sugar ester 1 as a mixture of compounds A-1, A-2, A-3, A-4, and A-5, etc.

[0125] When analyzing the mixture obtained by high performance liquid chromatography - mass spectrometry (HPLC-MS), A-1 is 1.2 mass%, A-2 is 13.2 mass%, A-3 is 14.2 mass%, A-4 is 35.4 mass%, and A-5, etc. is 40.0 mass%. The average degree of substitution is 5.2, and the esterification rate is 65%.

[0126] It should be noted that A-5, etc. refers to all components with a degree of substitution of 4 or less, that is, a mixture of compounds with a degree of substitution of 4, 3, 2, and 1. In addition, the average degree of substitution and the esterification rate are calculated with A-5, etc. as a degree of substitution of 4. The measurement conditions of HPLC-MS are as follows.

[0127] <HPLC-MS measurement conditions>

[0128] 1) LC section

[0129] Device: Column oven (JASCO CO-965), detector (JASCO UV -970-240nm), pump (JASCO PU-980), degasser (JASCO DG-980-50) manufactured by JASCO Corporation

[0130] Column: Inertsil ODS-3 with a particle size of 5 μm, 4.6×250 mm (manufactured by GL SCIENCES Inc.)

[0131] Column temperature: 40 °C

[0132] Flow rate: 1 ml / min

[0133] Mobile phase: THF (1% acetic acid): H2O (50:50)

[0134] Injection volume: 3μl

[0135] 2) MS Department

[0136] Device: LCQ DECA (manufactured by Thermo Quest Co., Ltd.)

[0137] Ionization method: Electrospray ionization (ESI)

[0138] Spray Voltage: 5kV

[0139] Capillary temperature: 180℃

[0140] Evaporator temperature: 450℃

[0141] 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 anhydride were reacted with equimolar amounts of pyridine to obtain glycoesters 2, 3, and 4, which have the composition, average degree of substitution, and esterification rate described in Table I.

[0142] Table I

[0143]

[0144] The resulting mixture of sugar esters 1 to 4, which are esters with different degrees of substitution, were purified by column chromatography with silica gel to obtain A-1, A-2, A-3, A-4 and A-5 with a purity of 100%.

[0145] In this invention, for example, a sugar ester (sugar ester 2 in Table I) with a desired esterification rate (70-100%) is selected from the sugar esters 1 to 4 prepared therefrom as sugar ester (B). Alternatively, sugar ester (B) with an esterification rate adjusted to 70-100% is obtained by combining and adding the separated A-1 to A-5 as described above.

[0146] (Other ingredients)

[0147] Without impairing the effects of the present invention, the substrate of the laminated film of the present invention may, as needed, contain components other than cellulose acylate (A) and glycol ester (B). Examples of such components include: plasticizers, ultraviolet absorbers, antioxidants, particulates (matting agents), surfactants, polymeric electrolytes, conductive complexes, antistatic agents, anti-blocking agents, lubricants, etc.

[0148] <Plasticizer>

[0149] In the substrate of the present invention, known plasticizers with a molecular weight of 10,000 or less may be used within a range that does not impair the effects of the present invention. There are no particular limitations on the plasticizer, but it is preferably selected from: polycarboxylic acid ester plasticizers, glycolate plasticizers, phthalate plasticizers, fatty acid ester plasticizers, and polyol ester plasticizers, etc.

[0150] The polyol ester is an ester (alcohol ester) of aliphatic polyols with two or more members and a monocarboxylic acid, preferably an aliphatic polyol ester with two to 20 members. The polyol ester preferably has an aromatic ring or a cycloalkyl ring within its molecule.

[0151] Preferred examples of aliphatic polyols include: ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, dibutanediol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, trimethylolpropane, pentaerythritol, trimethylolethane, xylitol, etc. Among these, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, and xylitol are also preferred.

[0152] There is no particular limitation on the monocarboxylic acid; it can be an aliphatic monocarboxylic acid, an alicyclic monocarboxylic acid, or an aromatic monocarboxylic acid, etc. To improve the membrane's moisture permeability and reduce volatility, an alicyclic monocarboxylic acid or an aromatic monocarboxylic acid is preferred. The monocarboxylic acid can be one type or a mixture of two or more. Furthermore, all the OH groups in the aliphatic polyol can be esterified, or some of the OH groups can be retained as is.

[0153] Aliphatic monocarboxylic acids are preferably fatty acids with a straight chain or side chain having 1 to 32 carbon atoms. More preferably, the number of carbon atoms in the aliphatic monocarboxylic acid is 1 to 20, and even more preferably 1 to 10. Examples of aliphatic monocarboxylic acids include: saturated fatty acids such as acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, 2-ethylhexanoic acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid, nonadecanoic acid, arachidic acid, benzyl acid, lignochloropic acid, ceric acid, heptadecanoic acid, linoleic acid, triacontanoic acid, and lacquer wax acid; and unsaturated fatty acids such as undecenoic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid. Among these, to improve compatibility with cellulose acetate, acetic acid or a mixture of acetic acid and other monocarboxylic acids is preferred.

[0154] Examples of alicyclic monocarboxylic acids include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, and cyclooctanecarboxylic acid.

[0155] Examples of aromatic monocarboxylic acids include: benzoic acid; groups to which 1 to 3 alkyl or alkoxy (e.g., methoxy, ethoxy) groups are introduced into the benzene ring of benzoic acid (e.g., tolueneic acid); aromatic monocarboxylic acids having 2 or more benzene rings (e.g., biphenyl carboxylic acid, naphtholic acid, tetrahydronaphtholic acid, etc.), preferably benzoic acid.

[0156] The polycarboxylic acid ester is an ester of an alcohol with a polycarboxylic acid of 2 or more members, preferably 2 to 20 members. The polycarboxylic acid is preferably an aliphatic polycarboxylic acid of 2 to 20 members, or an aromatic polycarboxylic acid of 3 to 20 members, or an alicyclic polycarboxylic acid of 3 to 20 members.

[0157] Examples of polycarboxylic acids include: aromatic polycarboxylic acids or their derivatives such as trimellitic acid, pyromellitic acid, and pyromellitic tetracarboxylic acid with three or more nucleotides; aliphatic polycarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, oxalic acid, fumaric acid, maleic acid, and tetrahydrophthalic acid; and hydroxy polycarboxylic acids such as tartaric acid, hydroxymalonic acid, malic acid, and citric acid. To suppress volatilization from the membrane, hydroxy polycarboxylic acids are preferred.

[0158] Examples of alcohols include: aliphatic saturated alcohols having a straight chain or side chains, aliphatic unsaturated alcohols having a straight chain or side chains, alicyclic alcohols, or aromatic alcohols. The aliphatic saturated alcohols or aliphatic unsaturated alcohols preferably have 1 to 32 carbon atoms, more preferably 1 to 20, and even more preferably 1 to 10. Examples of alicyclic alcohols include: cyclopentanol, cyclohexanol, etc. Examples of aromatic alcohols include: benzyl alcohol, cinnamyl alcohol, etc.

[0159] The molecular weight of polycarboxylic acid esters is not particularly limited, but is preferably in the range of 300 to 1000, and more preferably in the range of 350 to 750. From the viewpoint of inhibiting exudation, the molecular weight of polycarboxylic acid ester plasticizers is preferably larger; from the viewpoint of moisture permeability and compatibility with cellulose acetate, a smaller molecular weight is preferred.

[0160] Examples of polycarboxylic acid esters include: triethyl citrate, tributyl citrate, acetylated triethyl citrate (ATEC), acetylated tributyl citrate (ATBC), benzoyl tributyl citrate, acetylated triphenyl citrate, acetylated tribenzyl citrate, dibutyl tartrate, diacetyl dibutyl tartrate, tributyl trimellitate, tetrabutyl trimellitate, etc.

[0161] Polycarboxylic acid esters can be phthalates. Examples of phthalates include: diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, dicyclohexyl terephthalate, etc.

[0162] Examples of glycolates include: alkyl phthaloyl alkyl glycolates. Examples of alkyl phthaloyl alkyl glycolates include: methyl phthaloyl methyl glycolate, ethyl phthaloyl ethyl glycolate, propyl phthaloyl propyl glycolate, butyl phthaloyl butyl glycolate, octyl phthaloyl octyl glycolate, methyl phthaloyl ethyl glycolate, ethyl phthaloyl methyl glycolate, ethyl phthaloyl propyl glycolate, methyl phthaloyl butyl glycolate, ethyl phthaloyl butyl glycolate, butyl phthaloyl methyl glycolate, butyl phthaloyl ethyl glycolate, propyl phthaloyl butyl glycolate, butyl phthaloyl propyl glycolate, methyl phthaloyl octyl glycolate, ethyl phthaloyl octyl glycolate, octyl phthaloyl methyl glycolate, octyl phthaloyl ethyl glycolate, etc., preferably ethyl phthaloyl ethyl glycolate.

[0163] Ester plasticizers include fatty acid esters, citrate esters, phosphate esters, etc.

[0164] Examples of fatty acid esters include butyl oleate, methyl acetyl castor oil, and dibutyl sebacate. Examples of citrate esters include trimethyl acetylacetonate, triethyl acetylacetonate, and tributyl acetylacetonate. Examples of phosphate esters include triphenyl phosphate, trimethylbenzyl phosphate, tolyl diphenyl phosphate, octyl diphenyl phosphate, biphenyl diphenyl phosphate, trioctyl phosphate, and tributyl phosphate, with triphenyl phosphate being preferred.

[0165] Plasticizers can be used alone or in combination of two or more. The content of the plasticizer relative to 100 parts by weight of cellulose acylate (A) is preferably in the range of 1 to 20 parts by weight, more preferably in the range of 1.5 to 15 parts by weight. When the content of the plasticizer is within the range described above, it can exhibit a plasticizing effect and the plasticizer has excellent resistance to exudation from the substrate.

[0166] <UV absorber>

[0167] In the case of a phase retardation film disposed as a laminated film on the surface side (visible side) of a liquid crystal display device, the substrate of the present invention preferably contains an ultraviolet absorber from the viewpoint of improving lightfastness. The purpose of the ultraviolet absorber is to improve lightfastness by absorbing ultraviolet light at wavelengths below 400 nm, and in particular, the transmittance at a wavelength of 370 nm is preferably 10% or less, more preferably 5% or less, and even more preferably 2% or less.

[0168] The ultraviolet absorbers preferred in this invention are benzotriazole ultraviolet absorbers, benzophenone ultraviolet absorbers, and triazine ultraviolet absorbers, with benzotriazole ultraviolet absorbers and benzophenone ultraviolet absorbers being particularly preferred.

[0169] Examples of suitable products include: 5-chloro-2-(3,5-di-sec-butyl-2-hydroxyphenyl)-2H-benzotriazole, (2-2H-benzotriazole-2-yl)-6-(linear and side-chain dodecyl)-4-methylphenol, 2-hydroxy-4-benzyloxybenzophenone, and 2,4-benzyloxybenzophenone. Examples of suitable products include: TINUVIN109, TINUVIN171, TINUVIN234, TINUVIN326, TINUVIN327, TINUVIN328, and TINUVIN928. These are all commercially available products manufactured by BASF Japan and are preferred. Halogen-free products are preferred.

[0170] In addition, disc-shaped compounds, such as those having 1,3,5-triazine rings, are also preferred for use as ultraviolet absorbers.

[0171] When the substrate of the present invention contains ultraviolet absorbers, it may contain one or more of them, preferably two or more.

[0172] In addition, polymeric ultraviolet absorbers are preferred as ultraviolet absorbers, and polymeric ultraviolet absorbers as described in Japanese Patent Application Publication No. 6-148430 are particularly preferred.

[0173] Regarding the method of adding ultraviolet absorbers, they can be dissolved in organic solvents such as methanol, ethanol, butanol, dichloromethane, methyl acetate, acetone, dioxolane, or mixed solvents thereof, and then added to the dopant described later, or directly added to the doping composition.

[0174] Substances that are insoluble in organic solvents, such as inorganic powders, are dispersed in organic solvents using a dissolver or mill and then added to dopants.

[0175] The amount of ultraviolet absorber used in the substrate varies depending on the type of ultraviolet absorber and the conditions of use. When the dry film thickness of the substrate is 15 to 50 μm, it is preferably in the range of 0.5 to 10% by mass relative to the substrate, and more preferably in the range of 0.6 to 4% by mass.

[0176] Antioxidants

[0177] Antioxidants are also known as deterioration inhibitors. Placing liquid crystal display devices or similar products under high humidity and high temperature conditions can sometimes cause degradation of the substrate.

[0178] Antioxidants, such as those that delay or prevent the decomposition of the substrate due to residual solvents in the substrate, such as halogens or phosphoric acid plasticizers, are preferred to be present in the substrate.

[0179] As such antioxidants, hindered phenolic compounds are preferred, such as 2,6-di-tert-butyl-p-cresol, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], triethylene glycol bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and 2,4-bis-(n-octylthio)-6-(4-hydroxy-3,5-di-tert-butylaniline). Examples of its products include 1,3,5-triazine, 2,2-thio-diethylethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxy-hydrogenated cinnamamide), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, and tris(3,5-di-tert-butyl-4-hydroxybenzyl)-isocyanurate.

[0180] Particularly preferred are 2,6-di-tert-butyl-p-cresol, pentaerythritol-tetra[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate]. Furthermore, hydrazine-based metal passivators such as N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine and phosphorus-based processing stabilizers such as tris(2,4-di-tert-butylphenyl)phosphite can be used in combination, for example.

[0181] These antioxidants can be used alone or in combination of two or more. The amount of antioxidant added to the substrate is preferably in the range of 1 ppm to 1.0 % by mass relative to the cellulose acylate (A), more preferably in the range of 10 to 1000 ppm by mass.

[0182] <Particulate Matting Agent>

[0183] The substrate in the laminated film of the present invention may also contain microparticles (matting agents) as needed to improve surface lubricity.

[0184] The particles can be inorganic or organic. Examples of inorganic particles include: silica, titanium dioxide, alumina, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, and calcium phosphate. Among these, silica and zirconium oxide are preferred, and silica is more preferred to reduce the haze increase of the resulting substrate.

[0185] Examples of silica microparticles include: AEROSIL R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600, NAX50 (all manufactured by AEROSIL Corporation of Japan), SEAHOSTA R KE-P10, KE-P30, KE-P50, and KE-P100 (all manufactured by NIPP ON SHOKUBAI Corporation). Among these, AEROSIL R972V, NAX50, and SEAHOSTA R KE-P30 are particularly preferred in order to reduce the coefficient of friction while maintaining a low turbidity of the obtained substrate.

[0186] The primary particle size is preferably in the range of 5–50 nm, more preferably in the range of 7–20 nm. A larger primary particle size improves the lubricity of the resulting substrate, but can easily reduce transparency. Therefore, the particles can be contained as secondary aggregates with a particle size in the range of 0.05–0.3 μm. The size of the primary particles or their secondary aggregates can be determined by observing the primary particles or secondary aggregates at a magnification of 500,000 to 2,000,000,000 magnification using a transmission electron microscope, and by averaging the particle size of 100 primary particles or secondary aggregates.

[0187] These microparticles can be used alone or in combination of two or more. The content of microparticles in the substrate is preferably in the range of 0.05 to 1.0 parts by mass relative to 100 parts by mass of cellulose acylate (A), more preferably in the range of 0.1 to 0.8 parts by mass.

[0188] <Substrate Manufacturing Method>

[0189] The manufacturing method for the substrate of the laminated film of the present invention can be a conventional blow molding method, T-die method, calendering method, cutting method, casting method, emulsion method, hot pressing method, etc. From the viewpoints of suppressing coloration, suppressing foreign matter defects, and suppressing optical defects such as mold lines, the film forming method can be selected from solution casting film forming method and melt casting film forming method, especially solution casting method, which is preferred from the perspective of obtaining a uniform surface.

[0190] Solution casting film production method

[0191] The following describes the manufacture of the substrate of the present invention using a solution casting method.

[0192] 1) Dissolving process

[0193] The dissolution process involves dissolving or dispersing the cellulose acylate (A) and the sugar ester (B) in a dissolution vessel while stirring, using an organic solvent that is primarily a good solvent for cellulose acylate (A) and sugar ester (B), along with other components added as needed, to form a dopant; or, a process involves mixing the sugar ester (B) of the present invention and other components added as needed into a solution of the cellulose acylate (A) to form a solution (dispersion) to form a dopant that serves as the main dissolution solution.

[0194] Organic solvents can be used without limitation as long as they can dissolve cellulose acylates (A) and sugar esters (B), and can dissolve or disperse the other components.

[0195] For example, dichloromethane can be cited as a chlorinated organic solvent, while methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxane, 1,4-dioxane, cyclohexanone, 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, nitrate ethane, etc., are preferred.

[0196] In addition to the organic solvent, the dopant preferably contains 1 to 40% by mass of a straight-chain or branched aliphatic alcohol having 1 to 4 carbon atoms. When the proportion of alcohol in the dopant increases, the web gels and is easily peeled off from the metal support. Furthermore, when the proportion of alcohol is low, it also promotes the dissolution of cellulose acylates (A), sugar esters (B), and other components in non-chlorinated organic solvent systems.

[0197] Particularly preferred are dopants consisting of at least 15 to 45% by mass of cellulose acylate (A), glycol ester (B), and other components dissolved or dispersed in a solvent containing dichloromethane and a straight-chain or branched aliphatic alcohol having 1 to 4 carbon atoms.

[0198] Examples of straight-chain or branched aliphatic alcohols with 1 to 4 carbon atoms include methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, and tert-butanol. Ethanol is preferred due to its stability, relatively low boiling point, and good drying properties.

[0199] In the dissolution of cellulose acylates (A), glycol esters (B), and other components, various dissolution methods can be employed, including methods performed under normal pressure, methods performed below the boiling point of the main solvent, methods performed under pressure above the boiling point of the main solvent, methods described in Japanese Patent Application Publication Nos. 9-95544, 9-95557, or 9-95538 using a cooling dissolution method, and methods performed under high pressure as described in Japanese Patent Application Publication No. 11-21379. Methods performed under pressure above the boiling point of the main solvent are particularly preferred. Preferably, the dopants in or after dissolution are filtered using a filter material, degassed, and then pumped to the next process.

[0200] The preferred filter material for filtration is one with a particle size of 0.5–5 μm and a filtration time of 10–25 sec / 100 ml.

[0201] In this method, agglomerates remaining during particle dispersion and agglomerates generated during the addition of the main dopant can be removed solely by using a filter material with a trapping particle size of 0.5–5 μm and a filtration time of 10–25 sec / 100 ml. In the main dopant, the particle concentration is sufficiently low compared to the added liquid, thus preventing the agglomerates from sticking together during filtration and causing a sharp increase in filtration pressure.

[0202] 2) Casting process

[0203] The process involves conveying the dopant to a pressure mold via a liquid delivery pump (e.g., a pressure-type quantitative gear pump), causing the dopant to be cast from the pressure mold slit to a casting position on a metal support such as an infinitely conveying annular metal strip, a stainless steel strip, or a rotating metal drum.

[0204] A pressure mold that allows for adjustment of the slit shape in the mold head section, thus facilitating uniform film thickness, is preferred. Pressure molds such as coating hanger molds and T-molds are all preferred. The surface of the metal support is mirror-finished. To increase film formation speed, two or more pressure molds can be installed on the metal support to divide the dopant content and create multiple layers. Alternatively, a multilayer film structure can be obtained by simultaneously casting multiple dopants using a co-casting method.

[0205] 3) Solvent evaporation process

[0206] The process involves heating a web material (on which dopants are cast and the resulting doped film is called the web material) on a casting support to evaporate the solvent.

[0207] To achieve solvent evaporation, methods such as blowing air from the web side and / or transferring heat through liquid from the back of the support, or transferring heat from both the front and back sides via radiant heat, are preferred. The back-side liquid heat transfer method offers good drying efficiency. Furthermore, a combination of these methods is also preferred. It is preferable to dry the web on the support in an atmosphere of 20–100°C. To maintain this atmosphere, it is preferable to blow warm air at this temperature onto the web or to heat it using infrared radiation or other means.

[0208] From the perspectives of surface quality, moisture permeability, and peelability, it is preferable to peel the web from the support within 30 to 120 seconds.

[0209] It should be noted that the conditions of the solvent evaporation process can sometimes affect the physical properties of (1-2) when used as a substrate. In the initial stage of the solvent evaporation process, since planar orientation in the web is easier to achieve, reducing the solvent evaporation rate at low temperatures tends to increase the slope T of the out-of-plane phase difference. Conversely, increasing the solvent evaporation rate tends to decrease the slope T of the out-of-plane phase difference.

[0210] Therefore, from the viewpoint of setting the slope T of the out-of-plane phase difference within the range of (1-2), for example, in the initial stage of the solvent evaporation process, a method of performing a heat treatment at a low temperature of about 20 to 50°C for about 20 to 60 seconds, followed by a heat treatment at a high temperature of about 50 to 70°C until the residual solvent amount reaches an appropriate range when the web is peeled off, is preferred.

[0211] It should be noted that the amount of residual solvent in the web when peeling it from the metal support in the following peeling process is preferably in the range of approximately 20-80% by mass, depending on the strength of the drying conditions and the length of the metal support. If peeling is performed with a high amount of residual solvent, and the web is too soft, the flatness during peeling will be compromised, easily resulting in wrinkles and longitudinal streaks caused by peeling tension. Therefore, the amount of residual solvent during peeling should be determined by balancing economic speed and quality. It should be noted that the amount of residual solvent in the web is defined by the following formula.

[0212] Residual solvent content (mass%) = (Mass of the web before heat treatment - Mass of the web after heat treatment) / (Mass of the web after heat treatment) × 100

[0213] It should be noted that the heat treatment for determining the residual solvent amount refers to a heat treatment at 140°C for 1 hour.

[0214] 4) Stripping process

[0215] On a metal support, a web with evaporated solvent is peeled off at a peeling location, wherein the amount of residual solvent in the web reaches a suitable amount, for example, 20-80% by mass, preferably 20-30% by mass. The peeled web is then sent to the next process.

[0216] The peeling tension when peeling the metal support and the web is usually in the range of 160 to 245 N / m. If wrinkles are easily generated during peeling, it is preferable to peel with a tension of less than 190 N / m.

[0217] In this invention, it is preferable that the temperature at the peeling location on the metal support is 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.

[0218] 5) Drying and stretching processes

[0219] After peeling, the web is dried using a drying device that alternately conveys the web through multiple rollers arranged in the drying device and / or a tenter frame that conveys the web by clamping both ends with clips.

[0220] Drying is typically achieved by blowing hot air onto both sides of the fabric, but microwave heating can also be used instead. Overly rapid drying can damage the flatness of the finished substrate. High-temperature drying can begin when the residual solvent content is below approximately 8% by mass. Throughout the process, drying is generally carried out within the range of 40–250°C. Drying within the range of 40–200°C is particularly preferred.

[0221] Regarding the web-like material, stretching is performed in a direction orthogonal to the transport direction (casting direction, MD direction) in a manner that results in a substrate thickness within the range of 10 to 50 μm. When the glass transition temperature of the substrate is set to Tg, stretching is preferably performed within a temperature range of (Tg+15) to (Tg+50) °C. At temperatures below (Tg+15) °C, phase retardation is prone to occur, and due to increased tensile stress, there is a tendency for increased haze. If stretching is performed at temperatures exceeding (Tg+50) °C, fracture or planarity degradation may occur, leading to increased coloration of the substrate itself, and thus sometimes the quality (optical properties) as a retardation film cannot be maintained. Stretching is more preferably performed within a temperature range of (Tg+20) to (Tg+40) °C.

[0222] It should be noted that the glass transition temperature Tg mentioned here is the intermediate glass transition temperature (Tmg) determined by JIS K7121 (1987) using a commercially available differential scanning calorimeter at a heating rate of 20°C / min.

[0223] The specific method for determining the glass transition temperature (Tg) of the substrate was based on JIS K7121 (1987) and was performed using a differential scanning calorimeter (DSC220) manufactured by SEIKOINSTRUMENTS.

[0224] A substrate sample of approximately 10 mg was prepared. Under nitrogen flow rate of 50 ml / min, the temperature was increased from room temperature to 250 °C at a rate of 20 °C / min and held for 10 minutes (first scan). Then, the temperature was decreased to 30 °C at a rate of 20 °C / min and held for 10 minutes (second scan). Finally, the temperature was increased to 250 °C at a rate of 20 °C / min (third scan). A DSC curve was prepared, and the glass transition temperature Tg from the obtained DSC curve of the third scan can be determined.

[0225] In this invention, it is preferable to prepare a sample experimentally using the material constituting the substrate, and to stretch it within the temperature range relative to the measured Tg of the substrate sample.

[0226] When using a tenter frame for stretching, it is preferable to use a device that allows independent control of the holding length (distance from the start to the end of holding) of the web by means of the left and right holding mechanisms of the tenter frame. Furthermore, in the stretching process, it is preferable to intentionally create zones of different temperatures to improve flatness.

[0227] In addition, it is preferable to set a neutral region so that the different regions do not cause interference between different temperature zones.

[0228] It should be noted that the stretching operation can also be carried out in multiple stages, and biaxial stretching in both the casting direction and the width direction is particularly preferred. Furthermore, biaxial stretching can be performed simultaneously or in stages. Regarding the stretch ratio, the sum of the stretch ratios in the casting direction and the width direction is preferably 1.1 to 4 times, more preferably 1.2 to 3 times, relative to the original width of the fabric.

[0229] In this context, the term "staged" can refer to, for example, performing stretching in different directions sequentially, or dividing stretching in the same direction into multiple stages and applying stretching in different directions to any one of those stages. That is, for example, the following stretching steps can be performed.

[0230] • Stretch along the casting direction → Stretch along the width direction → Stretch along the casting direction → Stretch along the casting direction

[0231] • Stretch along the width direction → Stretch along the width direction → Stretch along the casting direction → Stretch along the casting direction

[0232] Furthermore, biaxial stretching also includes stretching in one direction while the other side contracts due to reduced tension. The preferred stretching ratio for biaxial stretching is 1.01 to 1.5 times the original width in both the width and casting directions. Particularly preferred, from the viewpoint of reducing retardation, is stretching in the width direction within the range of 1.01 to 1.2 times the original film width, and more preferably within the range of 1.05 to 1.1 times.

[0233] The residual solvent content of the web material during drying and stretching using the tenter frame stretching device is preferably in the range of 20-30% by mass when it is hung on the tenter frame stretching device. It is more preferably dried while hanging on the tenter frame stretching device until the residual solvent content of the web material is below 15% by mass.

[0234] In the stretching device of the tenter frame, the residual solvent content of the web material at the start of stretching is preferably 1 to 15% by mass, more preferably 2 to 10% by mass. Furthermore, it is preferable to dry the web material until the residual solvent content in the winding process is 2% by mass or less, more preferably 0.4% by mass or less.

[0235] In the tenter frame stretching device, from the viewpoint of improving the uniformity of the substrate, it is preferable that the temperature distribution in the width direction of the atmosphere is less. The temperature distribution in the width direction of the tenter frame stretching device is preferably within ±5℃, more preferably within ±2℃, and most preferably within ±1℃.

[0236] 6) Embossing process

[0237] The substrate of this invention is preferably a film with a thickness in the range of 10 to 50 μm. Therefore, when the substrate is stored in a roll shape, there is a risk of winding misalignment or deterioration of optical quality, but these can be effectively prevented by embossing. It should be noted that embossing is an optional process.

[0238] Embossing refers to a pattern of a certain width, consisting of tiny, continuous raised and recessed areas, added to the substrate before winding the long strip of film to prevent the back and front surfaces of the wound films from completely adhering to each other. When one side of the substrate (e.g., the upper surface) is made convex, a corresponding concave shape is formed on the other side of the substrate (e.g., the lower surface). This prevents the wound substrates from completely or partially adhering to each other, which could affect the surface condition of the substrate and cause malfunctions.

[0239] 7) Winding process

[0240] This process involves winding the web material using a winding machine after the residual solvent content is reduced to 2% by mass or less. By reducing the residual solvent content to 0.4% by mass or less, a substrate with good dimensional stability can be obtained. Winding in the range of 0.00% to 0.10% by mass is particularly preferred.

[0241] The winding method can be any commonly used method, such as constant torque method, constant tension method, taper tension method, and programmed tension control method with constant internal stress. Appropriate use of these methods is sufficient.

[0242] According to the method described above, the substrate of the present invention is obtained, for example, as a long strip film. Specifically, rolls of approximately 100m to 10,000m are examples, and rolls of substrate with a length of 5,000m or more are particularly preferred. Furthermore, the width of the substrate is preferably 1 to 4m, more preferably 1.4 to 3m. Additionally, the thickness of the substrate of the present invention is in the range of 10 to 50μm, more preferably in the range of 20 to 40μm.

[0243] <Substrate Characteristics>

[0244] (Phase difference (phase delay value))

[0245] The substrate of the present invention is preferably measured with light of wavelength 590 nm at an environment of temperature 23°C and relative humidity, and the in-plane phase difference Ro590 defined by the following formula (i) is in the range of 0 to 10 nm, and the out-of-plane phase difference R590 defined by the following formula (ii) is in the range of -20 to 20 nm.

[0246] Formula (i): Ro=(n x -n y )×d(nm)

[0247] Equation (ii): R = {(n x +n y ) / 2-n z}×d(nm)

[0248] In equations (i) and (ii), n x This represents the refractive index along the x-axis, where the refractive index is greatest in the in-plane direction of the film. y This represents the refractive index of the film in the in-plane direction, along the direction y, which is orthogonal to the x-direction. z d represents the refractive index along the z-direction of the film's thickness. d represents the film's thickness (nm).

[0249] These phase differences (phase delay values) can be measured using an automated birefringence meter KOBRA-WPR (Prince Measurement Instruments).

[0250] In the substrate of the present invention, regarding the out-of-plane phase difference, the conditions (1-2) are satisfied. That is, the value T (the slope T of the out-of-plane phase difference) obtained based on the formula (1) is in the range of 0.040 to 0.055, according to the out-of-plane phase difference R650 obtained by measuring the substrate with light of wavelength 650 nm and the out-of-plane phase difference R450 obtained by measuring the substrate with light of wavelength 450 nm. The slope T of the out-of-plane phase difference is preferably in the range of 0.045 to 0.050.

[0251] It should be noted that, in the out-of-plane phase difference R590, apart from the different measurement wavelengths, the same method can also be used to measure the out-of-plane phase difference R650 and the out-of-plane phase difference R450.

[0252] By making the slope T of the out-of-plane phase difference of the substrate within the range described, when fabricating the laminated film of the present invention, which is laminated with the optical functional layer, the optical properties described in (3) (1.1≤Rth450 / Rth550≤1.9) can be achieved.

[0253] (Total fog)

[0254] The total haze of the substrate of the present invention is preferably less than 1%, more preferably less than 0.5%, and even more preferably less than 0.2%. If the haze is less than 1%, the transparency of the substrate will not decrease, and when the laminated film of the present invention is formed by laminating with the optical functional layer, it fully functions as an optical (phase retardation) film.

[0255] The total haze of the substrate can be measured using a haze meter NDH-2000 (manufactured by Nippon Denshoku Kogyo Co., Ltd.) according to JIS K-7136. The light source of the haze meter can be a 5V 9W halogen bulb, and the light-receiving part can be a silicon photoelectric element (with a photometric function filter). Haze measurement can be performed at 23°C and 55% RH.

[0256] (Total light transmittance)

[0257] The total light transmittance of the substrate of the present invention is preferably 90% or more, more preferably 93% or more. Furthermore, as a practical upper limit, it is approximately 99%. To achieve excellent transparency as represented by this total light transmittance, it is effective to avoid introducing additives or copolymers that absorb visible light, or to remove foreign matter from the raw materials, such as dopants, through high-precision filtration, thereby reducing light diffusion and absorption within the substrate. Furthermore, reducing the surface roughness of the substrate surface by decreasing the surface roughness of the substrate contact portions (cooling rollers, calendering rollers, drums, belts, coating substrates in solution film preparation, conveyor rollers, etc.) during film formation, thereby effectively reducing light diffusion and reflection on the substrate surface.

[0258] (Optical functional layer)

[0259] The optical functional layer contains a polymer in which fumarate polymeric units are contained in a proportion of 90 mol% or more relative to all polymeric units. In this polymer, 80 to 100% of the ester portion of the fumarate polymeric units is isopropyl ester. Hereinafter, a polymer in which fumarate polymeric units are contained in a proportion of 90 mol% or more relative to all polymeric units and 80 to 100% of the ester portion of the fumarate polymeric units is isopropyl ester is also referred to as "polymer (F)".

[0260] The optical functional layer may contain other components besides polymer (F) as needed, without compromising the effectiveness of the invention.

[0261] (Polymer(F))

[0262] The optical functional layer comprises a polymer (F). The optical functional layer is composed of a polymer (F), except for other optional components. The proportion of polymer (F) in the optical functional layer is preferably 90% by mass or more, more preferably 95% by mass or more, and particularly preferably 100% by mass.

[0263] The polymer (F) used in this invention is a polymer in which fumarate ester polymeric units are contained in a proportion of 90 mol% or more relative to all polymeric units, and in which 80 to 100% of the ester portion of the fumarate ester polymeric units is isopropyl ester. Here, "polymeric unit" refers to a unit derived from the monomers constituting the polymer, and specifically refers to a unit composed of residues of the raw material monomers used to prepare the polymer in the polymer.

[0264] In polymer (F), the proportion of fumarate polymer units relative to all polymer units is preferably 95 mol% or more, more preferably 98 mol% or more, and particularly preferably 100 mol%. Furthermore, in polymer (F), the proportion of isopropyl ester in the ester portion of the fumarate polymer units is preferably 85-100%, more preferably 90-100%, and particularly preferably 100%.

[0265] In the fumarate polymerization unit, the fumarate monomer, which serves as the basis of the polymerization unit, can be a monoester in which only one of the two carboxyl groups of fumaric acid is esterified, or a diester in which both carboxyl groups are esterified. In polymer (F), a fumarate diester is preferred. The ester portion of the fumarate used as a monomer contains isopropyl ester, and the monomers are used in combination throughout polymer (F) in such a manner that the proportion of isopropyl ester in the ester portion of the fumarate polymerization unit is within the aforementioned range.

[0266] As the polymerization unit of fumarate in polymer (F), fumarate diester polymerization unit (a) represented by the following general formula (a) is preferred, for example.

[0267] [Chemical Formula 11]

[0268]

[0269] In general formula (a), R1 and R2 independently represent alkyl groups having 1 to 12 carbon atoms. In the polymer (F), 80 to 100% of the total number of R1 and R2 is isopropyl.

[0270] Hereinafter, the monomer that forms the basis of the fumarate diester polymerization unit (a) will be referred to as "fumarate diester (a)", and R1 and R2 will be referred to as "ester groups". The polymer (F) can be defined as a polymer formed by combining and polymerizing fumarate diesters (a1) to (a3) ​​classified as follows in fumarate diester (a) in such a way that 80% to 100% of the ester groups are isopropyl. The proportion of isopropyl groups in the ester groups is preferably 85% to 100%, more preferably 90% to 100%, and particularly preferably 100%.

[0271] Fumarate diester (a1); R1 and R2 are both isopropyl.

[0272] Fumarate diester (a2); one of R1 and R2 is isopropyl, and the other is an alkyl group with 1 to 12 carbon atoms other than isopropyl.

[0273] Fumarate diester (a3); R1 and R2 are alkyl groups with 1 to 12 carbon atoms, excluding isopropyl.

[0274] Here, alkyl groups having 1 to 12 carbon atoms (excluding isopropyl) in R1 and R2 can be exemplified by: straight-chain alkyl groups such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, and n-hexyl; branched-chain alkyl groups such as sec-butyl, tert-butyl, sec-pentyl, tert-pentyl, sec-hexyl, and tert-hexyl; and cyclopropyl, cyclopentyl, and cyclohexyl. Without impairing the effects of the present invention, these alkyl groups can be substituted with halogen groups such as fluorine and chlorine; ether groups; ester groups; or amino groups.

[0275] When polymer (F) is obtained by combining fumarate diesters (a1) to (a3), from the viewpoint of ease of manufacture, it is preferable to combine fumarate diester (a1), i.e., diisopropyl fumarate and fumarate diester (a3), to obtain polymer (F). In the polymerization of polymer (F), when diisopropyl fumarate and fumarate diester (a3) ​​are used as monomers, the molar percentage of diisopropyl fumarate relative to the total molar amount of diisopropyl fumarate and fumarate diester (a3) ​​can be 80 to 100 mol%, and 80 to 100% of the ester portion of the fumarate ester polymerization unit in polymer (F) can be set as isopropyl ester.

[0276] Examples of the fumarate diester (a3) ​​include: dimethyl fumarate, diethyl fumarate, di-n-propyl fumarate, di-n-butyl fumarate, di-n-pentyl fumarate, di-n-hexyl fumarate, di-n-butyl fumarate, di-tert-butyl fumarate, di-second-pentyl fumarate, di-tert-pentyl fumarate, di-second-hexyl fumarate, di-tert-hexyl fumarate, dicyclopropyl fumarate, dicyclopentyl fumarate, dicyclohexyl fumarate, etc., with dimethyl fumarate and diethyl fumarate being preferred.

[0277] In polymer (F), polymeric units other than fumarate polymeric units, which may be contained in a proportion of less than 10 mol% relative to all polymeric units, can be exemplified by polymeric units based on monomers such as "monomer (b)". In polymer (F), the monomers that form the basis of polymeric units other than fumarate polymeric units are also referred to below as "monomer (b)".

[0278] Examples of monomers (b) include, for instance, styrene-based monomers such as styrene and α-methylstyrene; (meth)acrylic acid; (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 3-ethyl-3-oxetane butyl (meth)acrylate, and tetrahydrofurfuryl (meth)acrylate; vinyl esters such as vinyl acetate and vinyl propionate; acrylonitrile; methacrylonitrile; and one or more olefins such as ethylene and propylene. It should be noted that "(meth)acrylic acid" refers to one or both of acrylic acid and methacrylic acid.

[0279] The polymer (F) used in this invention preferably has a number-average molecular weight (Mn) of 1 × 10⁻⁶, calculated from the dissolution profile determined by gel permeation chromatography (GPC) and converted to standard polystyrene. 3 From the above, especially from the viewpoint of creating an optical functional layer with excellent mechanical properties and excellent processability during film formation, 2×10 is preferred. 4 Above 2×10 5 the following.

[0280] As for the method of manufacturing the polymer (F) used in this invention, it can be manufactured by any method as long as the polymer (F) can be obtained. For example, it can be manufactured by free radical polymerization or free radical copolymerization using a fumarate selected such that 80-100% of the ester portion of the fumarate polymer unit in the obtained polymer (F) is isopropyl ester and monomer (b) of less than 10 mol% of all monomers as needed. It should be noted that, as the fumarate, a mixture of 80-100 mol% diisopropyl fumarate and 0-20 mol% diester fumarate (a3) ​​is preferred.

[0281] Furthermore, the free radical polymerization method used can be any of the known polymerization methods, such as bulk polymerization, solution polymerization, suspension polymerization, precipitation polymerization, emulsion polymerization, etc.

[0282] Examples of polymerization initiators used in free radical polymerization include: benzoyl peroxide, lauryl peroxide, octanoyl peroxide, acetyl peroxide, di-tert-butyl peroxide, tert-butylisopropylphenyl peroxide, diisopropylphenyl peroxide, tert-butyl peroxyacetate, tert-butyl peroxybenzoate, tert-butyl peroxypentanoate, and other organic peroxides; and azo initiators such as 2,2'-azobis(2,4-dimethylpentanonitrile), 2,2'-azobis(2-butanonitrile), 2,2'-azobisisobutanonitrile, dimethyl-2,2'-azobis(isobutyric acid), and 1,1'-azobis(cyclohexane-1-carboxynitrile).

[0283] Furthermore, there are no particular limitations on the solvents that can be used in solution polymerization, suspension polymerization, precipitation polymerization, and emulsion polymerization. Examples include: aromatic solvents such as benzene, toluene, and xylene; alcohol solvents such as methanol, ethanol, propanol, and butanol; cyclohexane; dioxane; tetrahydrofuran (THF); acetone; methyl ethyl ketone; dimethylformamide; isopropyl acetate; water, and mixed solvents thereof.

[0284] In addition, the polymerization temperature during free radical polymerization can be appropriately set according to the decomposition temperature of the polymerization initiator, and it is generally preferred to carry it in the range of 40 to 150°C.

[0285] (Other ingredients)

[0286] As needed, the optical functional layer of the laminated film of the present invention may contain components other than polymer (F) to a extent that does not impair the effects of the present invention. Examples of such components include ultraviolet absorbers, antioxidants, particulates (matting agents), surfactants, polymeric electrolytes, conductive complexes, antistatic agents, anti-blocking agents, lubricants, etc.

[0287] To improve thermal stability, the optical functional layer of the present invention preferably incorporates an antioxidant. Examples of such antioxidants include, for instance, the same hindered phenolic antioxidants, phosphorus antioxidants, and other antioxidants described in the substrate description; these antioxidants can be used individually or in combination.

[0288] In the optical functional layer, from the viewpoint of synergistically enhancing the antioxidant effect, it is preferable to use a combination of hindered phenolic antioxidants and phosphorus antioxidants. In this case, it is particularly preferable, for example, to use a mixture of phosphorus antioxidants in 100 to 500 parts by mass relative to 100 parts by mass of hindered phenolic antioxidants. Furthermore, the amount of antioxidant added in the optical functional layer is preferably 0.01 to 10 parts by mass relative to 100 parts by mass of polymer (F), and particularly preferably 0.5 to 1 part by mass.

[0289] Regarding the ultraviolet absorbers and microparticles (matting agents) that may be contained in the optical functional layer, examples can be made of substances that are the same as the ultraviolet absorbers and microparticles (matting agents) that may be contained in the substrate.

[0290] <Manufacturing Methods of Optical Functional Layers and Laminated Films>

[0291] In this invention, the optical functional layer is laminated with the substrate to form the laminated film of this invention. The optical functional layer can be formed as a film on its own or as a layer on the substrate. When the optical functional layer is formed on its own, the lamination of the optical functional layer and the substrate is performed, for example, using an adhesive. When the optical functional layer is formed as a layer on the substrate, the manufacturing of the optical functional layer and the lamination of the optical functional layer and the substrate are performed simultaneously.

[0292] As a manufacturing method for forming the optical functional layer into a film separately, the same manufacturing methods as the substrate manufacturing methods can be used, such as blow molding, T-die molding, calendering, cutting, casting, emulsion, hot pressing, etc. From the viewpoint of obtaining a uniform surface, solution casting and melt casting are preferred methods, and solution casting is particularly preferred.

[0293] Solution casting is a method of obtaining a film by dissolving a polymer (F) and other components added as needed in a solvent to form a solution (dopant), casting it onto a support, and then removing the solvent by heating or other means. In solution casting, the viscosity of the dopant solution is an extremely important factor when manufacturing films with high transparency, excellent thickness accuracy, and superior surface smoothness; it is preferably 700–30000 cps, and particularly preferably 1000–10000 cps.

[0294] Methods for casting dopants onto a support include, for example, T-die casting, doctor blade casting, bar coating, roll coating, and lip coating. In particular, the most common industrial method is to continuously extrude the dopant from a die onto a strip or drum-shaped support. Examples of supports used include glass substrates; metal supports such as stainless steel or iron molds; and plastic supports such as polyethylene terephthalate (PET) and triacetyl cellulose (TAC).

[0295] The dopant extruded onto a support is used to form a film by removing the solvent through heating or other means. This yields a film-like optical functional layer containing polymer (F). The film is then peeled off the support for use.

[0296] In addition, melt casting film forming is a forming method in which a mixture of components of an optical functional layer containing polymer (F) is melted in an extruder, extruded from the slit of a T-die into a film, and then cooled and drawn out by rollers or air.

[0297] As a method for producing a laminated optical functional layer and a substrate, one example is the bonding method using a known adhesive. As described above, when the film-like optical functional layer is manufactured as a roll using a solution casting method, and the substrate is manufactured as a roll as described above, bonding can be performed, for example, using a continuous roll-to-roll process and a known adhesive.

[0298] When the optical functional layer is formed in a layered manner on the substrate, the optical functional layer can be manufactured by coating the substrate with a liquid composition for forming the optical functional layer and drying it. At the same time, the optical functional layer and the substrate are laminated to obtain the laminated film of the present invention.

[0299] In this method, a solution (coating solution) is first prepared by dissolving the polymer (F) and other components to be added as needed in a solvent. The viscosity of the coating solution is an extremely important factor in obtaining an optical functional layer with high transparency, excellent thickness accuracy, and superior surface smoothness; it is preferably 10–10000 cps, and particularly preferably 10–5000 cps.

[0300] Coating methods include, for example, blade coating, bar coating, gravure coating, trench coating, lip coating, and corner wheel coating. In industrial applications, gravure coating is generally used for film coating, while corner wheel coating is typically used for thick film coating.

[0301] After being coated onto a substrate, the solvent is removed by heating or other means, thereby obtaining an optical functional layer on the substrate. It should be noted that in the melt casting film-forming method, a laminated film can also be formed by using a substrate as a support and forming a film as an optical functional layer on the substrate.

[0302] It should be noted that before the substrate and the optical functional layer are stacked, the stacked layers of the substrate and the optical functional layer can be pre-treated with plasma treatment, corona discharge treatment or other easy-to-bond treatments.

[0303] The thickness of the optical functional layer in the laminated film of the present invention is determined by the phase difference in the thickness direction of the optical functional layer, preferably 1 to 30 μm, more preferably 2 to 20 μm, and particularly preferably 2 to 10 μm.

[0304] <Characteristics of laminated membranes>

[0305] (Phase difference (phase delay value))

[0306] In the multilayer film of the present invention, regarding the out-of-plane phase difference, the condition described in (3) is satisfied. That is, for the multilayer film, the ratio Rth450 / Rth550 of the out-of-plane phase difference Rth450 measured with light at a wavelength of 450 nm and the out-of-plane phase difference Rth550 measured with light at a wavelength of 550 nm is in the range of 1.1 to 1.9. Rth450 / Rth550 is preferably in the range of 1.2 to 1.7.

[0307] It should be noted that, apart from the different measurement wavelengths, the out-of-plane phase difference Rth450 and out-of-plane phase difference Rth550 can be measured using the same method as the method for measuring the out-of-plane phase difference of the substrate.

[0308] Furthermore, in the multilayer film of the present invention, the out-of-plane phase difference Rth550 is preferably in the range of -30 to -15 nm, more preferably in the range of -25 to -18 nm. Furthermore, the out-of-plane phase difference Rth450 of the multilayer film is preferably in the range of -40 to -15 nm, more preferably in the range of -30 to -18 nm.

[0309] (Total fog)

[0310] The total haze of the laminated film of the present invention, measured using the same method as that for the substrate, is preferably less than 1%, more preferably less than 0.5%, and even more preferably less than 0.2%. If the haze is less than 1%, the transparency of the laminated film will not decrease, and it can fully function as an optical (phase reversal) film.

[0311] (Total light transmittance)

[0312] The total light transmittance of the laminated film of the present invention, measured using the same method as that for the substrate, is preferably 90% or more, more preferably 93% or more. Furthermore, a realistic upper limit is approximately 99%.

[0313] <Other functional layers>

[0314] In the laminated film of the present invention, functional layers such as antistatic layer, back coating layer, antireflective layer, slip-resistant layer, adhesive layer, anti-glare layer and barrier layer may be provided according to its application and as needed.

[0315] [Polarizing filter]

[0316] The polarizer of the present invention is characterized in that it is formed by stacking the multilayer film of the present invention and a polarizing lens. The polarizer of the present invention, having the multilayer film of the present invention, ensures good visual legibility when used in a liquid crystal display device.

[0317] The polarizer of the present invention, for example, has a polarizer and the laminated film of the present invention disposed on one side of the polarizer. Alternatively, a structure may have a protective film on the other side of the polarizer. Furthermore, a polarizer may have the laminated film of the present invention on both sides of the polarizer.

[0318] Figure 2 This is a cross-sectional view showing an example of the structure of the polarizer of the present invention. For example... Figure 2 As shown, the polarizer 20 includes a polarizer 11, a laminated film 10 disposed on one side of the polarizer 11, and a protective film 12 disposed on the other side. The laminated film 10 is formed by laminating a substrate 1 and an optical functional layer 2, and is disposed with the side of the substrate 1 facing the side of the polarizer 11. The polarizer 11, the laminated film 10, and the protective film 12 are bonded together via an arbitrary adhesive layer (not shown).

[0319] <Polarizing filter>

[0320] The polarizer, a key component of polarizers, is an element that allows light to pass through only the polarization plane in a specific direction. Currently known representative polarizers are polyvinyl alcohol (PVA) polarizing films. Among PVA polarizing films, there are films obtained by dyeing PVA with iodine and films obtained by dyeing with dichroic dyes.

[0321] As a polarizer, a polarizer can be obtained by: preparing a film using an aqueous solution of polyvinyl alcohol, uniaxially stretching and dyeing the film, or dyeing and then uniaxially stretching the film, preferably by a durability treatment with a boron compound. The film thickness of the polarizer is preferably in the range of 5 to 30 μm, and particularly preferably in the range of 5 to 15 μm.

[0322] As a polarizer, an ethylene-modified polyvinyl alcohol (PVC) film with an ethylene unit content of 1-4 mol%, a degree of polymerization of 2000-4000, and a degree of saponification of 99.0-99.99 mol%, as described in Japanese Patent Application Publication Nos. 2003-248123 and 2003-342322, is preferred. Among these, an ethylene-modified PVC film with a hot water cut-off temperature in the range of 66-73°C is particularly preferred. Polarizers using this ethylene-modified PVC film not only exhibit excellent polarization performance and durability but also have fewer color spots, making them especially preferred for large-scale liquid crystal display devices.

[0323] In addition, it is also preferable to manufacture a coated polarizer by means of the methods described in Japanese Patent Application Publication No. 2011-100161, Japanese Patent No. 4691205, Japanese Patent No. 4751481, and Japanese Patent No. 4804589, and to bond it with the laminated film of the present invention to manufacture a polarizer.

[0324] <Protective film>

[0325] The protective film that can be used in the polarizer of the present invention is, for example, available as a commercially available product. As a protective film, commercially available cellulose acylate films are preferred, for example (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, all manufactured by Konica Minolta (Co., Ltd.)).

[0326] The thickness of the protective film is not particularly limited and can be set to 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.

[0327] Depending on the requirements, the protective film may contain other layers besides the main film such as a cellulose acylate film. Examples of other layers include antireflective layers, antistatic layers, phase retardation layers, and brightness-enhancing layers.

[0328] <Adhesive Layer>

[0329] The adhesive layer can be a layer obtained by drying a fully saponified polyvinyl alcohol aqueous solution (water paste), or it can be a cured layer of an active energy ray curable adhesive.

[0330] <Methods for manufacturing polarizing filters>

[0331] The polarizer of the present invention can be manufactured by bonding the laminated film of the present invention and a polarizer. The method for bonding the laminated film and the polarizer is not particularly limited; it can be performed by using a fully saponified polyvinyl alcohol adhesive after saponifying the laminated film. Alternatively, the bonding of the laminated film and the polarizer can also be performed using an active energy radiation-curable adhesive. From the viewpoints of high elastic modulus of the resulting adhesive layer, easy suppression of polarizer deformation, and high resistance to changes in the external environment (heat, humidity, etc.), bonding with an active energy radiation-curable adhesive is preferred.

[0332] As active energy ray curable adhesives for polarizers, known types include: photoradical polymer compositions utilizing photoradical polymerization, photocationic polymer compositions utilizing photocationic polymerization, and hybrid compositions combining photoradical polymerization and photocationic polymerization.

[0333] As photoradical polymerizable compositions, those known include compositions containing, in a specific proportion, free radical polymerizable compounds containing polar groups such as hydroxyl and carboxyl groups and free radical polymerizable compounds without polar groups, as described in Japanese Patent Application Publication No. 2008-009329.

[0334] In particular, the free radical polymerizable compound is preferably a compound having an olefinic unsaturated bond capable of free radical polymerization. Preferred examples of compounds having an olefinic unsaturated bond capable of free radical polymerization include compounds having a (meth)acryloyl group. Examples of compounds having a (meth)acryloyl group include N-substituted (meth)acrylamide compounds, (meth)acrylate compounds, etc. "(meth)acryloyl group" refers to one or both of an acryloyl group and a methacryloyl group. The same applies to (meth)acrylamides and (meth)acrylates.

[0335] Furthermore, as a photocationic polymerization type composition, an active energy-curable adhesive disclosed in Japanese Patent Application Publication No. 2011-028234, comprising an (α) cationic polymerizable compound, a (β) photocationic polymerization initiator, a (γ) photosensitizer exhibiting high absorption of light with wavelengths greater than 380 nm, and a (δ) naphthalene-based photosensitizing aid, can be cited. However, other active energy-curable adhesives may also be used.

[0336] The following describes an example of a method for manufacturing a polarizer using an active energy radiation-curable adhesive. The polarizer can be manufactured by a method comprising the following steps: (1) a pretreatment step of easily bonding the surface of a polarizer to which an adhesive laminate is bonded; (2) an adhesive coating step of applying the active energy radiation-curable adhesive to at least one of the bonding surfaces of the polarizer and the laminate; (3) a bonding step of bonding the polarizer and the optical film with the obtained adhesive layer; and (4) a curing step of curing the adhesive layer while the polarizer and the optical film are bonded together with the adhesive layer. The pretreatment step (1) can be performed as needed.

[0337] (Pretreatment process)

[0338] In the pretreatment process, the bonding surface of the laminated film to the polarizer, such as the substrate side of the laminated film, is treated for easy bonding. When a laminated film and a protective film are bonded to both sides of the polarizer respectively, the bonding surface of the protective film to the polarizer is treated for easy bonding along with the laminated film. Examples of easy bonding treatments include corona discharge treatment and plasma treatment.

[0339] (Adhesive coating process)

[0340] In the adhesive coating process, the active energy X-ray curable adhesive is applied to at least one of the bonding surfaces of the polarizer and the laminated film. When the active energy X-ray curable adhesive is applied directly to the surface of the polarizer or the laminated film, the coating method is not particularly limited. For example, various coating methods such as doctor blades, wire bars, die coaters, corner roller coaters, and gravure coaters can be used. Alternatively, the active energy X-ray curable adhesive can be cast between the polarizer and the laminated film, then pressed and evenly spread using rollers or the like. Furthermore, when the polarizer has a protective film, the active energy X-ray curable adhesive is similarly applied to at least one of the bonding surfaces of the polarizer and the protective film.

[0341] (Lamination process)

[0342] After applying the active energy radiation-curable adhesive, it is supplied to the bonding process. In this bonding process, for example, if the active energy radiation-curable adhesive has been applied to the surface of the polarizer in the previous coating process, the laminated film is overlapped there. Alternatively, if the active energy radiation-curable adhesive has been applied to the surface of the laminated film in the previous coating process, the polarizer and the laminated film are overlapped in this state.

[0343] When bonding a laminated film and a protective film to both surfaces of a polarizer, i.e., when using an active energy radiation-curable adhesive on both surfaces, the laminated film and the protective film are overlapped on both surfaces of the polarizer using the active energy radiation-curable adhesive, respectively. Furthermore, typically in this state, pressure is applied from both surfaces (polarizer side and laminated film side if the laminated film is overlapped on one side of the polarizer, and laminated film and protective film side if both surfaces of the polarizer have the laminated film and protective film overlapped) using rollers or similar devices. The rollers can be made of metal, rubber, or other materials. The rollers positioned on both surfaces can be made of the same material or different materials.

[0344] (Curing process)

[0345] In the curing process, the uncured active energy X-ray curable adhesive is irradiated with active energy rays, causing the adhesive layer to cure and forming an adhesive layer composed of the cured active energy X-ray curable adhesive. This bonds the polarizer, which is overlapped by the active energy X-ray curable adhesive, to the laminated film and optionally a protective film. When the laminated film is laminated on one side of the polarizer, the active energy rays can irradiate from either the polarizer side or the laminated film side. Furthermore, when the laminated film and protective film are laminated on both sides of the polarizer respectively, it is advantageous to irradiate the laminated film and protective film on both sides of the polarizer, with the active energy X-ray curable adhesive overlapping on both sides, from either film side, simultaneously curing the active energy X-ray curable adhesive on both sides.

[0346] As active energy rays, visible light, ultraviolet light, X-rays, electron beams, etc. can be used. From the perspective of ease of operation and sufficient curing speed, electron beams or ultraviolet light are generally preferred.

[0347] The electron beam irradiation conditions can be any suitable conditions, as long as they are sufficient to cure the adhesive. For example, the accelerating voltage for electron beam irradiation is preferably in the range of 5 to 300 kV, more preferably in the range of 10 to 250 kV. If the accelerating voltage is less than 5 kV, the electron beam may not reach the adhesive, resulting in insufficient curing. If the accelerating voltage exceeds 300 kV, the penetration force through the sample is too strong, causing the electron beam to bounce back and potentially damaging the laminated film, protective film, and polarizer. 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 will not cure sufficiently. When it exceeds 100 kGy, it may damage the laminated film, protective film, and polarizer, resulting in reduced mechanical strength, yellowing, and failure to obtain the desired optical properties.

[0348] The ultraviolet irradiation conditions can be any suitable conditions that allow the adhesive to cure. The ultraviolet irradiation dose, measured in cumulative light intensity, is preferably between 50 and 1500 mJ / cm². 2 More preferably, it is within the range of 100–500 mJ / cm. 2 Within the range.

[0349] In the polarizer obtained as described above, the thickness of the adhesive layer is not particularly limited, and is usually in the range of 0.01 to 10 μm, preferably in the range of 0.5 to 5 μm.

[0350] Liquid crystal display device

[0351] The liquid crystal display device of the present invention includes the polarizer of the present invention. By including the polarizer of the present invention, which utilizes the laminated film of the present invention, the liquid crystal display device of the present invention can ensure good visual clarity.

[0352] The liquid crystal display device of the present invention, for example, has Figure 3 and Figure 4 The structure shown. Figure 3 This is a top view of an example of the liquid crystal display device of the present invention. Figure 4 yes Figure 3 The cross-sectional view of the liquid crystal display device shown at line XX. Figure 3 and Figure 4 The liquid crystal display device 100 shown includes a liquid crystal panel 30, a first polarizer 20a disposed on the surface Sa of the liquid crystal panel 30 on the side visible to the naked eye, and a second polarizer 20b disposed on the surface Sb of the liquid crystal panel 30 on the backlight side. The first polarizer 20a and the second polarizer 20b are polarizers of the present invention that respectively possess the laminated films 10a and 10b of the present invention.

[0353] It should be noted that, in the liquid crystal display device of the present invention, for example, at least the first polarizer 20a and the second polarizer 20b are polarizers of the present invention, and more preferably both are polarizers of the present invention.

[0354] The liquid crystal panel 30 has two glass substrates G and liquid crystal cells L disposed between them. The liquid crystal panel 30 can preferably be used in: 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 (also including MVA; Multi-domain Vertical Alignment, PVA; Patterned Vertical Alignment), HAN (Hybrid Aligned Nematic) mode, etc. To improve contrast, VA (MVA, PVA) mode or IPS mode is preferred.

[0355] In TN mode liquid crystal panels, when no voltage is applied, the rod-shaped liquid crystal molecules are essentially horizontally aligned, and then twisted to an alignment of 60–120°. TN mode liquid crystal panels are most commonly used as color TFT liquid crystal display devices, and are documented in numerous publications.

[0356] In VA mode liquid crystal panels, bar-shaped liquid crystal molecules are substantially vertically oriented when no voltage is applied.

[0357] In addition to (1) a narrow VA mode liquid crystal panel in which the rod-shaped liquid crystal molecules are substantially vertically oriented when no voltage is applied and substantially horizontally oriented when a voltage is applied (as described in Japanese Patent Application Publication No. 2-176625), there are also: (2) a liquid crystal panel in which the VA mode is multi-domain oriented (MVA mode) in order to expand the viewing angle (as described in SID97, Digest of Tech. Papers (Draft Collection) 28 (1997) 845), (3) a liquid crystal panel in which the rod-shaped liquid crystal molecules are substantially vertically oriented when no voltage is applied and twisted multi-domain orientation when a voltage is applied (n-ASM mode) (as described in the draft collections 58-59 (1998) of the Japan Liquid Crystal Conference), and (4) a SURVAIVAL mode liquid crystal panel (published in LCD International 98).

[0358] An OCB (Optically Compensatory Bend) liquid crystal panel is a liquid crystal panel with a bent-alignment mode in which rod-shaped liquid crystal molecules are oriented in substantially opposite directions (symmetrically) at the top and bottom of the liquid crystal panel, as disclosed in U.S. Patent Nos. 4,583,825 and 5,410,422. Because the rod-shaped liquid crystal molecules are symmetrically aligned at the top and bottom of the liquid crystal panel, the bent-alignment mode liquid crystal panel has self-optical compensation functionality. Therefore, this liquid crystal mode is called an OCB liquid crystal mode. Liquid crystal display devices with bent-alignment modes have the advantage of fast response speed.

[0359] The IPS mode LCD panel is a switching method that applies a lateral electric field to the nematic liquid crystal, which is described in detail in Proc. IDRC (Asia Display 1995), pp. 577-580 and 707-710.

[0360] In ECB mode liquid crystal panels, the rod-shaped liquid crystal molecules are substantially horizontally aligned when no voltage is applied. ECB mode is one of the liquid crystal display modes with the simplest structure, as detailed in Japanese Patent Application Publication No. 5-203946.

[0361] The first polarizer 20a has a first laminated film 10a, a first polarizing lens 11a, and a first protective film 12a sequentially on the surface Sa of the liquid crystal panel 30 that is visible to the naked eye. The first laminated film 10a has a substrate 1 and an optical functional layer 2, which is attached to the surface Sa of the liquid crystal panel 30 that is visible to the naked eye.

[0362] The second polarizer 20b has a second laminated film 10b, a second polarizing lens 11b, and a second protective film 12b sequentially on the backlight side surface Sb of the liquid crystal panel 30. The second laminated film 10b has a substrate 1 and an optical functional layer 2, which is attached to the backlight side surface Sb of the liquid crystal panel 30.

[0363] Preferably, the absorption axis of the first polarizer 11a is orthogonal to the absorption axis of the second polarizer 11b (forming a cross-niche).

[0364] The liquid crystal display device 100 has a liquid crystal panel 30 having two glass substrates G and a liquid crystal cell L disposed therebetween. The liquid crystal cell L is configured, for example, to have a pair of alignment films between a pair of transparent electrodes, a liquid crystal layer between the alignment films, and a color filter on the inner side of the glass substrate G on the side visible to the naked eye.

[0365] 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. The polarizer of the present invention exhibits minimal dimensional changes due to temperature and humidity, making it particularly suitable for use as a thin glass film in small to medium-sized mobile electronic devices.

[0366] In the liquid crystal display device 100, the bonding of the surface of the optical functional layer 2 of the first laminated film 10a to the surface 2a of the liquid crystal panel 30 (visible to the naked eye) and the bonding of the surface of the optical functional layer 2 of the second laminated film 10b to the surface 2b of the liquid crystal panel 30 (backlight side) can be achieved by known methods. In some cases, bonding can be achieved by an adhesive layer (not shown). As the adhesive layer, it is preferable to use an adhesive layer obtained by the same active energy ray curable adhesive used in the fabrication of the polarizer.

[0367] The liquid crystal display device of the present invention is more effective in an IPS-type configuration and is therefore preferred. The liquid crystal display device using the polarizer of the present invention achieves excellent viewing angle characteristics and suppresses color inhomogeneity, resulting in superior visual discernibility, thanks to the effect of the laminated film of the present invention.

[0368] Example

[0369] The present invention is illustrated below with specific examples, but the present invention is not limited thereto. It should be noted that the use of "parts" or "%" in the examples, unless otherwise specified, indicates "parts by mass" or "% by mass".

[0370] [Fabrication of laminated films]

[0371] (1) Fabrication of the substrate

[0372] (1-1) Synthesis of cellulose acylates

[0373] Three cellulose acylated compounds 1 to 3, having the types of acyl groups and degrees of acyl substitution as shown in Table II, and number-average molecular weight (Mn), were synthesized according to the method described in Japanese Patent Application Publication No. 10-45804. It should be noted that cellulose acylated compounds 1 and 2 are cellulose acylated compounds equivalent to cellulose acylated compound (A), while cellulose acylated compound 3 is a cellulose acylated compound outside the range of cellulose acylated compound (A).

[0374] Table II

[0375] serial number degree of acyl substitution Acyl groups Molecular weight (Mn) 1 2.9 Acetyl 70000 2 2.6 Acetyl 70000 3 2.5 Acetyl 70000

[0376] (1-2) Synthesis of sugar esters

[0377] According to the synthetic example (esterification reaction of sucrose based on benzoic anhydride), sugar esters 1 to 5, in the proportions shown in Table III, with acyl groups replacing the hydrogen atoms of the hydroxyl groups of the sugars shown in Table III, were synthesized. Specifically, sugar esters 1, 2, and 5 were prepared by changing the benzoic anhydride to acetic anhydride in the synthetic example, and adjusting the esterification rate using the same method as described above. Sugar ester 3 was prepared as in the synthetic example. Sugar ester 4 was prepared by changing sucrose to glucose and benzoic anhydride to acetic anhydride in the synthetic example, and adjusting the esterification rate using the same method as described above.

[0378] It should be noted that sugar esters 1 to 4 are sugar esters equivalent to sugar ester (B), while sugar ester 5 is a sugar ester outside the range of sugar ester (B).

[0379] Table III

[0380]

[0381] (1-3) Preparation of substrate

[0382] The substrates used for laminated films are manufactured using a solution casting method.

[0383] (Preparation of adulterants)

[0384] Dopants 1-9 with the compositions shown in Table IV were prepared. Specifically, firstly, dichloromethane and ethanol were added as solvents to a pressurized dissolving vessel. Cellulose acylates, sugar esters, and matting agents were added to the pressurized dissolving vessel containing the solvents while stirring, and the mixture was completely dissolved and dispersed while heating and stirring. All matting agents shown in Table IV were 12% ethanol dispersions of AEROSIL R812 (manufactured by AEROSIL Co., Ltd., Japan).

[0385] The obtained liquid was filtered using Anji Filter Paper No. 244 manufactured by Anji Filter Paper Co., Ltd., and impurities 1 to 9 were obtained.

[0386] Table IV

[0387]

[0388] (Preparation of substrate 1)

[0389] The dopant 1 prepared above was uniformly cast onto a stainless steel strip support at a temperature of 22°C with a width of 1.8 m using a tape casting apparatus. The stainless steel strip support was then evaporated at 40°C for 1 minute, and then the solvent was evaporated at 60°C until the residual solvent content reached 20%. The resulting web was then peeled off from the stainless steel strip support with a peel tension of 162 N / m.

[0390] Next, the stripped web 1 was allowed to evaporate the solvent at 35°C, cut into 1.6m wide pieces, and then stretched 1.05 times in the width direction (TD direction) relative to the original width using a tenter frame with the glass transition temperature of the substrate 1 set to Tg (as described above, Tg measured from a substrate sample pre-made using the material constituting the substrate 1) at a temperature of (Tg+20)°C. At this point, the residual solvent amount at the start of stretching using the tenter frame was 4% by mass. Then, drying was completed while conveying the substrate through drying zones at 120°C and 140°C using multiple rollers, thus producing substrate 1. The substrate thickness was 40μm.

[0391] (Preparation of substrates 2-9)

[0392] In the above, except that dopant 1 is changed to dopant 2 to 9, substrates 2 to 9 with a thickness of 40 μm are also fabricated in the same way.

[0393] (Fabrication of substrate 10)

[0394] Using a tape casting apparatus, the dopant 1 prepared above was uniformly cast onto a stainless steel tape support at a temperature of 22°C and a width of 1.8 m. The stainless steel tape support was then evaporated at 65°C for 1 minute, followed by solvent evaporation at 40°C until the residual solvent content reached 20%. This was then peeled off from the stainless steel tape support as web 10 with a peel tension of 162 N / m. Subsequently, in the fabrication of the substrate 1, the web 10 was stretched and dried in the same manner as the web 1, to produce a substrate 10 with a thickness of 40 μm.

[0395] <Optical properties of the substrate>

[0396] For the obtained base materials 1 to 10, the value T (the slope T of the out-of-plane phase difference) was obtained according to the formula (1) based on the out-of-plane phase difference R650 measured with light of wavelength 650 nm and the out-of-plane phase difference R450 measured with light of wavelength 450 nm. The results are shown in Table V together with the composition of the materials contained in each base material. It should be noted that in the table, the addition amount of the sugar ester is the addition amount relative to 100 parts by mass of the cellulose acylate.

[0397]

[0398] (2) Synthesis of the material for the optical functional layer

[0399] As the material for the optical functional layer, fumarate polymers 1 to 3 were manufactured.

[0400] <Synthesis Example 1>

[0401] In a 30 L 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(isobutyric acid) as a polymerization initiator were added, and suspension radical polymerization was carried out under the conditions of a polymerization temperature of 50 °C and a polymerization time of 24 hours. After filtering the obtained particles, they were thoroughly washed with methanol and dried at 80 °C to obtain a diisopropyl fumarate homopolymer. The number average molecular weight of the obtained diisopropyl fumarate homopolymer was 160,000. The diisopropyl fumarate homopolymer is a fumarate polymer in which 100% of the ester part is isopropyl ester. The diisopropyl fumarate homopolymer was used as fumarate polymer 1.

[0402] <Synthesis Example 2>

[0403] In a 1 L reactor equipped with a stirrer, a cooling tube, a nitrogen inlet tube, and a thermometer, 600 g of distilled water, 3.4 g of hydroxypropyl methylcellulose (manufactured by Shin-Etsu Chemical Co., Ltd., trade name METOLOS E 60SH-50) as a dispersant, 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 tert-butyl peroxyneopentanoate as an oil-soluble radical initiator were added. After nitrogen bubbling for 1 hour, radical suspension polymerization was carried out by stirring at 400 rpm and maintaining at 50 °C for 28 hours. After the polymerization reaction was completed, the content was recovered from the reactor, the polymer was filtered, washed twice with distilled water, washed twice with methanol, and then dried under reduced pressure at 80 °C (yield: 75%).

[0404] The number average molecular weight of the obtained fumarate copolymer was 138,000. By 1¹H-NMR analysis confirmed that the obtained fumarate copolymer was a diisopropyl fumarate-diethyl fumarate copolymer with a diisopropyl fumarate polymer unit / diethyl fumarate polymer unit ratio of 87 / 13 (mol%). That is, the obtained fumarate copolymer was a fumarate copolymer in which 87% of the ester portion was isopropyl ester. This fumarate copolymer was designated as fumarate polymer 2.

[0405] <Synthesis example 3>

[0406] In Synthesis Example 2, polymerization was carried out in the same manner as described above, except that the molar ratio of diisopropyl fumarate to diethyl fumarate used in the polymerization was changed from diisopropyl fumarate:diethyl fumarate to 7:3, to obtain a diisopropyl fumarate-diethyl fumarate copolymer with a number average molecular weight of 140,000 and a diisopropyl fumarate polymer unit / diethyl fumarate polymer unit ratio of 70 / 30 (mol%). That is, the obtained fumarate copolymer is a fumarate copolymer in which 70% of the ester portion is isopropyl ester. This fumarate copolymer is designated as fumarate polymer 3.

[0407] (3) Preparation of laminated membranes

[0408] Using the substrates 1-10 and fumarate polymers 1-3 prepared above, a laminated film is prepared as follows.

[0409] (Fabrication of laminated membrane 1)

[0410] The fumarate polymer 1 obtained in Synthesis Example 1 was dissolved in a toluene:methyl ethyl ketone solution at a mass ratio of 1:1 to prepare a 10% solution for coating. The coating solution was then applied to the substrate 1 using a doctor blade method to achieve a dried layer thickness of 2 μm, followed by drying to form an optical functional layer, resulting in a laminated film 1.

[0411] (Preparation of laminated films 2-16)

[0412] In the fabrication of laminated film 1, laminated films 2 to 16 are fabricated in the same manner as described above, except that the type of substrate, the type of fumarate polymer, and the thickness of the optical functional layer are changed as shown in Table VI.

[0413] [Evaluation of laminated membranes]

[0414] For the obtained laminated films 1–16, the optical properties and interlayer adhesion were evaluated as follows. The results are shown in Table VI, which illustrates the types of substrates and optical functional layers used in their manufacture. It should be noted that in the table, “isopropyl%” indicates the percentage (%) of isopropyl ester in the ester portion of the fumarate polymer.

[0415] (1) Optical properties

[0416] Calculate the ratio Rth450 / Rth550, which is the out-of-plane phase difference Rth450 measured with light at a wavelength of 450 nm and the out-of-plane phase difference Rth550 measured with light at a wavelength of 550 nm. The table shows Rth450 / Rth550 and Rth550.

[0417] (2) Fit

[0418] Using an NT cutter, 11 longitudinal and 11 transverse cuts were made at 1mm intervals on the optical functional layer of the laminated film, forming a 100-grid pattern. Transparent tape (CELLOTAPE (registered trademark) No. 405, 24mm wide, manufactured by NICHIBAN Co., Ltd.) was then applied, and a rapid stretching peel test was performed in the vertical (90°) direction. Adhesion was then evaluated based on the number of peeled grid lines, as per the evaluation criteria below. It should be noted that the test was conducted at 23°C and 55% RH.

[0419] (Evaluation Criteria)

[0420] ◎: 100 squares remain.

[0421] ○: The remaining quantity is between 90 and 99 squares.

[0422] ×: 89 or fewer grids remaining

[0423] Table VI

[0424]

[0425] [Preparation of Polarizing Filters]

[0426] Using laminated films 1 to 16, a polarizer is fabricated having a polarizer, a laminated film on one side of the polarizer, and a protective film on the other side. It should be noted that an active energy-curable adhesive is used to bond the polarizer, the laminated film, and the protective film.

[0427] (Making a polarizing filter)

[0428] A 75 μm thick polyvinyl alcohol film with an average degree of polymerization of 2400 and a saponification degree of 99.9 mol% was immersed in warm water at 30°C for 60 seconds to allow it to swell. Next, the resulting film was immersed in a 0.3% aqueous solution of iodine / potassium iodide (mass ratio = 0.5 / 8) and stretched to 3.5 times while being dyed. Then, the resulting film was stretched in a borate ester aqueous solution at 65°C to a total stretch ratio of 6 times. Finally, the resulting film was dried in an oven at 40°C for 3 minutes to obtain a polarizing mirror with a thickness of 25 μm.

[0429] (Protective film)

[0430] As a protective film, KC2UA (product name, manufactured by Konica Minolta (Co., Ltd.), a cellulose acylate membrane) is prepared.

[0431] (Adhesive 1; Photoradical polymerized active energy line curing adhesive)

[0432] 50 parts by weight of HEAA (hydroxyethyl acrylamide, manufactured by KOHJIN Corporation), 50 parts by weight of HEA (2-hydroxyethyl acrylate, manufactured by KOHJIN Corporation), and 3 parts by weight of BASF IRGACURE819 (manufactured by BASF Japan Corporation) as photoradioactive polymerization initiator were mixed and stirred at 50°C for 1 hour to obtain adhesive 1.

[0433] (Fabrication of Polarizer 1)

[0434] Corona discharge treatment was performed on the substrate side of the laminated film 1 and one surface of the protective film (KC2UA). The conditions for the corona discharge treatment were a corona output intensity of 2.0 kW and a linear velocity of 18 m / min. Next, the adhesive 1 prepared as described above was applied to the corona-treated surfaces of the laminated film 1 and the protective film using a bar coater to achieve a cured adhesive layer thickness of 0.5 μm.

[0435] The adhesive coating surfaces of the laminated film 1 and the protective film are bonded to the two surfaces of the polarizer fabricated as described above, resulting in a laminate of laminated film 1 / adhesive coating layer / polarizer / adhesive coating layer / protective film (KC2UA). From both sides of this laminate, an ultraviolet irradiation device with a conveyor belt (using a D-valve lamp manufactured by FUSION UV SYSTEMS) is used to irradiate the laminate with a cumulative light intensity of 750 mJ / cm². 2 The polarizer 1 is obtained by irradiating it with ultraviolet light to cure the coating layer of adhesive 1, which then acts as an adhesive layer.

[0436] (Fabrication of polarizers 2-16)

[0437] Except that the laminated films 2 to 16 are used instead of the laminated film 1, the polarizers 2 to 16 are made in the same way as the polarizer 1.

[0438] [Fabrication of Liquid Crystal Display Devices]

[0439] A liquid crystal display device was fabricated using polarizers 1 to 16 prepared above. Specifically, a Hitachi IPS-mode LCD TV, Wooo W32-L7000, was prepared. The outline cross-section of the LCD TV is shown below. Figure 4The structure shown in this LCD TV involves peeling off the polarizers on both the visually inspectable side and the backlight side of the glass substrate surface of the LCD panel. Two polarizers 1 fabricated as described above are prepared, and the optical functional layers of the laminated film of each polarizer 1 are respectively bonded to the visually inspectable side and the backlight side of the glass substrate surface of the LCD panel to fabricate the LCD display device 1. It should be noted that during bonding, the absorption axes of the two polarizers 1 and the absorption axes of the two polarizers bonded to the LCD TV are bonded in the same direction on both the visually inspectable side and the backlight side to fabricate the LCD display device 1. LCD display devices 2-16 are fabricated using polarizers 2-16 in the same manner as described above.

[0440] [evaluate]

[0441] For the obtained liquid crystal display devices 1 to 16, the power supply of the liquid crystal display devices was turned on, and the color uniformity and left-right color difference when displaying white images were evaluated as follows, and the visual recognition from the oblique direction was evaluated. The results are shown in Table VII.

[0442] (1) Uneven color matching

[0443] The white image was viewed from 45° to the right and 45° to the left of the LCD display device to confirm the color matching. The left and right sides were evaluated according to the following criteria.

[0444] (Evaluation Criteria)

[0445] ◎: No unevenness can be observed at all.

[0446] ○: Although thin unevenness can be observed, there is no problem with visual recognition.

[0447] ×: Unevenness was observed and there were problems with visual recognition.

[0448] (2) Color difference between left and right

[0449] The left and right color difference when visually observing the white image from the right 45° and left 45° angles toward the LCD device is evaluated based on the following criteria.

[0450] (Evaluation Criteria)

[0451] ◎: There is no difference in color scheme between the left and right sides.

[0452] ○: Although there are some differences in color scheme between the left and right sides, I don't mind.

[0453] ×: The color scheme is different (for example, blue is seen when viewed from the right 45° and red is seen when viewed from the left 45°).

[0454] Table VII

[0455]

[0456] As can be seen from Tables VI and VII, the interlayer adhesion of the laminated film of the present invention is good, and the liquid crystal display device using the polarizer having the laminated film can ensure good visual recognition.

[0457] Industrial applicability

[0458] According to the present invention, a multilayer film having good interlayer adhesion in a retardation film having a fumarate resin layer and ensuring good visual legibility in a liquid crystal display device using the multilayer film, and a polarizer using the multilayer film, can be provided. Furthermore, by using the multilayer film, a liquid crystal display device that ensures good visual legibility can be provided.

[0459] Symbol Explanation

[0460] 10, 10a, 10b laminated membranes

[0461] 1. Substrate

[0462] 2. Optical functional layer

[0463] Polarizing filters 20, 20a, and 20b

[0464] Polarizing mirrors 11, 11a, and 11b

[0465] 12, 12a, 12b protective films

[0466] 100 LCD display devices

[0467] 30 LCD panel

[0468] G glass plate

[0469] L liquid crystal unit

Claims

1. A laminated film comprising a substrate and an optical functional layer, wherein, The substrate comprises: a cellulose acylate with an acyl substitution degree in the range of 2.6 to 3.0, and a sugar ester in which 70% to 100% of the hydrogen atoms of the hydroxyl groups are replaced by acyl groups. Based on the out-of-plane phase difference R650 measured with light at a wavelength of 650 nm and the out-of-plane phase difference R450 measured with light at a wavelength of 450 nm, the value T obtained based on the following formula (1) is in the range of 0.040 to 0.

055. Equation (1) T=(R650-R450) / (650-450) The optical functional layer contains a polymer of units comprising fumarate at a ratio of 90 mol% or more relative to all polymer units, wherein 80-100% of the ester portion of the fumarate polymer units is isopropyl ester. The ratio of the out-of-plane phase difference Rth450 measured with light at a wavelength of 450 nm to the out-of-plane phase difference Rth550 measured with light at a wavelength of 550 nm, Rth450 / Rth550, is in the range of 1.2 to 1.

9.

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

3. A polarizer, which is formed by laminating the multilayer film as described in claim 1 or 2 with a polarizing mirror.

4. A liquid crystal display device, comprising: The polarizer according to claim 3.

Images