Cellulose acylate film containing specific ultraviolet absorber, and polarizing plate and liquid crystal display device using same

Abstract

The present invention provides a cellulose acylate film containing a specific ultraviolet light absorber, a polarizing film using the cellulose acylate film, and a liquid crystal display device, the cellulose acylate film contains more than two ultraviolet light absorbers, at least one of the ultraviolet light absorbers is required to satisfy the following conditions: the absorption capability is mainly concentrated in a 315-400 nm wave band, and the absorption capability of the other one of the ultraviolet light absorbers is not concentrated in a 315-400 nm wave band, and the absorption capability of the other one of the ultraviolet light absorbers is not concentrated in a 315-400 nm wave band. The absorptive amount of the wave band needs to account for 75% or above of the total absorptive amount of the wave band within 250-600 nm, and the wave band has excellent durability such as weather resistance and heat resistance and can block ultraviolet rays with long waves of 380 nm or below. The prepared cellulose acylate film is excellent in spectral absorption performance, little in coloring, excellent in transparency and sufficient in ultraviolet absorption capacity, even if the cellulose acylate film is exposed to high-temperature and high-humidity conditions for a long time, ultraviolet rays can be effectively blocked, and the cellulose acylate film meets the increasing market requirement for use in severe environments.

Description

Technical Field

[0001] This invention belongs to the field of polymer membrane material technology, specifically relating to cellulose acylated membranes containing specific ultraviolet absorbers, polarizers using cellulose acylated membranes, and liquid crystal display devices. Background Technology

[0002] Cellulose acylate films are commonly used as protective films for polarizers in liquid crystal display (LCD) devices. With the increasing demands for thinner, wider, and higher-quality optical films in LCD devices, the requirements for the optical performance and durability of cellulose acylate films are also becoming more stringent. When polarizers and liquid crystal cells are exposed to ultraviolet (UV) light, the polarizer and liquid crystal molecules are decomposed, thus reducing display performance. Therefore, the cellulose acylate films used in LCD devices contain UV absorbers to suppress the performance degradation of polarizers and liquid crystal cells caused by UV light.

[0003] However, for thin polarizer protective films, high concentrations of UV absorbers are required to control UV transmittance, which may cause UV absorber leaching or adversely affect the physical properties of the cellulose acylate membrane. Therefore, there is a need to develop a cellulose acylate membrane that can maintain good UV absorption performance even when thinned.

[0004] The optical film disclosed in the invention patent with publication number CN101490585A is characterized by containing cellulose ester and ultraviolet absorber. However, the ultraviolet absorption capacity is not sufficient. To obtain the desired ultraviolet absorption performance, a large amount of these ultraviolet absorbers must be added. However, when these ultraviolet absorbers are added in large quantities, the compatibility with cellulose resin is insufficient, resulting in insufficient transparency or the film itself turning yellow. Furthermore, the ultraviolet absorption capacity will decrease during long-term storage, making it difficult to achieve practical application as a protective film for polarizers. Summary of the Invention

[0005] In response to the problems raised in the background art, the present invention studies and designs a cellulose acylate film containing a specific ultraviolet absorber, a polarizer using the cellulose acylate film, and a liquid crystal display device. The cellulose acylate film contains a plasticizer and two or more specific ultraviolet absorbers, wherein at least one ultraviolet absorber has high absorption in a specific wavelength range, thereby giving the cellulose acylate film excellent absorption performance, transparency, and long-term lightfastness, making it suitable as an optical film in liquid crystal display devices.

[0006] The technical solution of this invention:

[0007] A cellulose acylated membrane containing a specific ultraviolet absorber, comprising a plasticizer and two or more specific ultraviolet absorbers, wherein at least one of the specific ultraviolet absorbers must satisfy the following requirements: its absorption capacity is mainly concentrated in the 315nm–400nm wavelength band, and the absorption in this band accounts for more than 75% of its total absorption in the 250nm–600nm wavelength band. The specific ultraviolet absorber is hydroxyphenylbenzotriazole (general formula I) and aminobutadiene (general formula II) or a combination thereof, and the compounds are represented by general formulas (I) and (II), respectively. General formula (I):

[0008]

[0009] General formula (II):

[0010]

[0011] R1 to R6 each represent a hydrogen atom, halogen, alkyl, alkoxy, hydroxyl, carboxyl, or amide group, and they may further have substituents;

[0012] R7 and R8 respectively represent -COOH, -COOR9, -COR9, -CN, or -SO2R. 10 ;

[0013] R9 and R 10 Each represents an alkyl or aryl group, wherein the alkyl group optionally contains one or more heteroatoms selected from N, O, Si, and S.

[0014] The specific ultraviolet absorber, wherein aminobutadiene (general formula II) is represented by the following general formula (III),

[0015] General formula (III):

[0016]

[0017] Among them, R5, R6, R7 and R 10 As defined in claim 1.

[0018] After being subjected to damp heat aging, the transmittance of the cellulose acylated membrane at a wavelength of 380 nm decreased by less than 10%, and the color value Δb* was less than 0.5.

[0019] More preferably, after the cellulose acylated membrane undergoes damp heat aging, the transmittance at a wavelength of 380 nm decreases by less than 5%, and the color value Δb* is less than 0.3.

[0020] The cellulose acylated membrane has a transmittance of less than 10% at a wavelength of 380 nm, and a chromaticity index b* of 0.1 to 1.5 in L*a*b* color.

[0021] More preferably, the cellulose acylated membrane has a transmittance of less than 5% at a wavelength of 380 nm and a chromaticity index b* of 0.2 to 1.0 in L*a*b* color.

[0022] The cellulose acylated membrane contains one or more plasticizers, preferably polyester, polyol ester, sugar ester, or other plasticizers.

[0023] The content of a specific ultraviolet absorber in the cellulose acylated membrane is 0.01 to 2.5 wt% of the cellulose resin mass.

[0024] More preferably, the content of a specific ultraviolet absorber in the cellulose acylated membrane is preferably 0.02 to 1.0 wt% of the cellulose resin mass.

[0025] More preferably, the content of a specific ultraviolet absorber in the cellulose acylated membrane is preferably 0.05 to 1.0 wt% of the cellulose resin mass.

[0026] The thickness of the cellulose acylated membrane is 10 μm to 60 μm.

[0027] More preferably, the thickness of the cellulose acylated membrane is 15 μm to 40 μm.

[0028] A polarizer comprising at least one cellulose acylated film containing a specific ultraviolet absorber as described above.

[0029] A liquid crystal display device comprising at least one polarizer as described above.

[0030] The beneficial effects of this invention are as follows: This invention provides a stable and efficient ultraviolet absorber that has good compatibility with cellulose resin and excellent heat resistance. The cellulose acylated membrane of this invention incorporates two or more specific ultraviolet absorbers during preparation, with at least one of the absorbers exhibiting high absorption within a specific wavelength range. The resulting cellulose acylated membrane possesses sufficient ultraviolet absorption capacity. As a polarizer protective film, it can effectively block ultraviolet light below 380nm while allowing sufficient transmission of long-wavelength light above 400nm, effectively suppressing the degradation of polarizer and liquid crystal display device performance caused by ultraviolet light. The cellulose acylated membrane exhibits excellent spectral absorption performance, minimal coloration, and superior transparency, possessing ample ultraviolet absorption capacity. Even under prolonged exposure to high temperature and humidity conditions, it effectively blocks ultraviolet rays, thus meeting the growing market demand for use in harsh environments. The cellulose acylated membrane, even when prepared in a thinner form, retains excellent ultraviolet absorption performance without the need for high concentrations of ultraviolet absorbers, thereby avoiding the problem of ultraviolet absorber leakage or adverse effects on membrane physical properties. The cellulose acylated membrane prepared by this invention contains ultraviolet absorbers that can be added at high concentrations and exhibits high resistance to decomposition under high temperature and humidity conditions. Detailed Implementation

[0031] (cellulose resin)

[0032] In the cellulose acylated membrane containing a specific ultraviolet absorber prepared by this invention, the cellulose resin is preferably cellulose acetate, cellulose diacetate, cellulose triacetate, cellulose propylene acetate, cellulose acetate butyrate, cellulose acetate phthalate, polycaprolactone, and grafted cellulose acetate. Among these, acetylated celluloses such as cellulose acetate, cellulose diacetate, and cellulose triacetate are more preferred from the perspective of mechanical properties (tensile strength, flexural strength, and flexural elasticity).

[0033] When the cellulose is acetylated cellulose, the degree of polymerization is preferably in the range of 200 to 500, more preferably in the range of 250 to 400. If the polymerization degree of acetylated cellulose is too high, the viscosity of the acetylated cellulose solution will become too high, making it difficult to produce cellulose acylated films through the casting process, which is therefore not preferred. If the polymerization degree of acetylated cellulose is too low, the strength of the produced cellulose acylated film will decrease, which is also not preferred. The degree of acetylation is preferably in the range of 54.0% to 62.5%, more preferably in the range of 58.0% to 62.5%.

[0034] (Plasticizer)

[0035] In preparing the cellulose acylate membrane containing a specific ultraviolet absorber as described in this invention, the film-forming material preferably contains at least one plasticizer. A plasticizer generally refers to an additive that improves fragility and imparts flexibility by being added to a polymer. Furthermore, the plasticizer also functions as a moisture-permeable barrier, reducing the moisture permeability of the cellulose acylate membrane by filling the free volume of the cellulose acylate and disrupting its water-binding sites.

[0036] The plasticizers that can be used in the cellulose acylated membranes of this invention are not particularly limited. Plasticizers can be used alone or in combination of two or more. Preferably, plasticizers include phthalate-type compounds, polyol ester-type plasticizers, polyester oligomer-type plasticizers, citrate-type plasticizers, sugar ester-type plasticizers, and nitrogen-containing aromatic compound-type plasticizers. More preferably, polyester oligomer-type plasticizers, polyol ester-type plasticizers, and sugar ester-type plasticizers are preferred. These plasticizers have high compatibility with cellulose acylated membranes, can reduce exudation, and cause almost no decomposition of the plasticizer or degradation or deformation of the membrane with changes in temperature, humidity, and time. The amount of plasticizer added is 1% to 25% of the mass of cellulose resin. When the amount of plasticizer added is less than 1%, the effect of reducing the moisture permeability of the cellulose acylated membrane is small. When the amount of plasticizer added exceeds 25%, the physical properties of the cellulose acylated membrane will deteriorate during high temperature and high humidity long-term use. Therefore, the amount of plasticizer added is more preferably 2 to 20 wt%, and more preferably 2 to 10 wt%.

[0037] (UV absorber)

[0038] The cellulose acylated membrane of the present invention preferably contains an ultraviolet absorber.

[0039] The ultraviolet absorber in the cellulose acylated membrane involved in this invention can be selected from hydroxyphenylbenzotriazole (general formula I) and aminobutadiene (general formula II) or combinations thereof, and the compounds are represented by the following general formulas (I) and (II):

[0040] General formula (Ⅰ):

[0041]

[0042] General formula (II):

[0043]

[0044] R1 to R6 each represent a hydrogen atom, halogen, alkyl, alkoxy, hydroxyl, carboxyl, or amide group, and they may further have substituents;

[0045] R7 and R8 respectively represent -COOH, -COOR9, -COR9, -CN, or -SO2R. 10 ;

[0046] R9 and R 10 Each represents an alkyl or aryl group, wherein the alkyl group optionally contains one or more heteroatoms selected from N, O, Si, and S.

[0047] According to general formula (Ⅰ), the molecular formula of the ultraviolet absorber can be obtained as follows, but the present invention is not limited to this.

[0048]

[0049]

[0050] According to general formula (II), the molecular formula of the ultraviolet absorber can be obtained as follows, but the present invention is not limited to this.

[0051]

[0052]

[0053] The cellulose acylated film of the present invention may use the aforementioned specific ultraviolet absorbers (at least two mixed together), or the aforementioned specific ultraviolet absorbers (at least two mixed together) may be used in combination with other ultraviolet light. The required characteristics of the polarizer protective film are: sufficient blocking of ultraviolet light below 380 nm, sufficient transmission of long-wavelength light above 400 nm, particularly preferably a transmittance of 10% or less for wavelengths of 380 nm, more preferably 5% or less.

[0054] There are no particular limitations on other ultraviolet absorbers used in this invention. Triazine ultraviolet absorbers, benzotriazole ultraviolet absorbers, benzophenone ultraviolet absorbers, benzoyl ultraviolet absorbers, benzodisulfide ultraviolet absorbers, benzoxazole ultraviolet absorbers, etc. are preferred. At least one ultraviolet absorber selected from triazine ultraviolet absorbers and benzotriazole ultraviolet absorbers is even more preferred.

[0055] The method for adding the ultraviolet absorber involves dissolving it in alcohols or organic solvents such as methanol, ethanol, butanol, dichloromethane, methyl acetate, and acetone, or mixtures thereof, to form an ultraviolet absorber solution. This ultraviolet absorber solution is then mixed with a cellulose solution. The delivery pipes for both solutions are connected at a manifold, and the mixture is simultaneously mixed using an online mixer. A static mixer is preferred, and two or more online mixers can be arranged in series. Alternatively, the ultraviolet absorber solution can be added directly to the cellulose solution at the source.

[0056] In terms of less coloring of the cellulose acylated membrane and better UV absorption, the amount of UV absorber added is preferably 0.01 wt% to 2.5 wt% relative to the mass of the cellulose resin, more preferably 0.02 wt% to 1.0 wt%, and even more preferably 0.05 wt% to 1.0 wt%.

[0057] (particle)

[0058] The cellulose acylated membrane involved in this invention contains microparticles, which preferably contain inorganic microparticles such as silica, titanium dioxide, alumina, zirconium oxide, calcium carbonate, kaolin, talc, sintered calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, and calcium phosphate. The content of microparticles relative to the cellulose resin is preferably 0.005 wt% to 0.3 wt%. In most cases, silica microparticles are surface-treated with organic substances, which can reduce the turbidity of the membrane and are therefore preferred. These microparticles are preferably present as aggregates in the cellulose acylated membrane, forming an unevenness of 0.01 to 1.0 μm on the surface of the cellulose acylated membrane. Examples of silica microparticles include: AEROSIL 200, AEROSIL 200V, 300, R972, R972V, R974, R202, R812, OX50, and TT600 (manufactured by Nippon Aerosil Co., Ltd.). The preferred materials are AEROSIL 200V, R972, R972V, R974, R202, and R812. Two or more of these particles can be used together, and when two or more are used together, they can be mixed in any proportion.

[0059] (Functional additives)

[0060] The cellulose acylated membrane of this invention can incorporate various additives (such as plasticizers, ultraviolet absorbers, anti-deterioration agents, stripping agents, infrared absorbers, wavelength dispersion modifiers, etc.), which can be solids or oils; that is, their melting point and boiling point are not particularly limited. Other additives can be added at any time during the cellulose solution preparation process. Furthermore, the amount of each raw material added is not particularly limited as long as it demonstrates its function.

[0061] (Preparation method of cellulose acylate membrane)

[0062] In this invention, the cellulose acylated membrane is typically prepared using a solution casting method, with a preferred thickness of 10 μm to 60 μm, more preferably 15 μm to 40 μm. Cellulose resin is dissolved in an organic solvent, which can be a mixture of two or more organic solvents. The prepared cellulose solution is filtered and then discharged onto a casting support through a casting mold. Once the cast film on the support has acquired support properties, it is peeled off from the casting support to form a wetted film. The wetted film is further dried, formed into a film, and then wound up to obtain a cellulose acylated membrane with uniform thickness and optical isotropic properties.

[0063] In the manufacturing method of cellulose acylate membranes, a stretching step after membrane formation is preferred. The stretching direction of the cellulose acylate membrane is preferably along the longitudinal (MD) direction (Machine Direction) or orthogonal to the longitudinal (TD) direction (Transverse Direction). During MD stretching, the speed of the guide rollers can be adjusted to make the winding speed of the cellulose acylate membrane faster than its peeling speed, thus achieving MD stretching. During TD stretching, the cellulose acylate membrane is gradually stretched by maintaining its width using a stretching machine while being conveyed.

[0064] TD-direction stretching is preferably 5% to 100%, more preferably 5% to 80%, and particularly preferably 5% to 40%. Here, "unstretched" means 0% stretching. The stretching treatment can be performed during the film-making process, with the film containing residual solvent. Preferably, the stretching is performed when the residual solvent content = (mass of residual volatile components / mass of film after heat treatment) × 100% is 0.05% to 50%. Particularly preferably, the stretching is performed at 5% to 80% with a residual solvent content of 0.05% to 5%. Stretching the cellulose acylated film further improves its mechanical properties.

[0065] (Polarizing filter)

[0066] The polarizer of the present invention is characterized by comprising a polarizer and at least one layer of cellulose acylate film containing a specific ultraviolet absorber of the present invention.

[0067] The cellulose acylated film of the present invention is suitable as a protective film for polarizers. Polarizers are formed by laminating a protective film onto at least one surface of a polarizer. Polarizers include iodine-containing polarizers and dye-containing polarizers. Iodine-containing polarizers and dye-containing polarizers are typically manufactured using polyvinyl alcohol-based films. When the cellulose acylated film of the present invention containing a specific UV absorber is used as a protective film for a polarizer, the polarizer can be manufactured by any general method without particular limitation. For example, the resulting cellulose acylated film can be treated with alkali, and then the treated film can be bonded to both surfaces of a polarizer manufactured by impregnating a polyvinyl alcohol film in an iodine solution and stretching it. The adhesive used to bond the protective film and the polarizer can be a polyvinyl alcohol adhesive, such as polyvinyl alcohol and polyvinyl butyral; or a latex of a vinyl polymer (e.g., polybutylene acrylate). A particularly preferred adhesive is an aqueous solution of fully saponified polyvinyl alcohol.

[0068] (LCD display)

[0069] The specific configuration of the liquid crystal display device of the present invention is not particularly limited, and a known configuration may be adopted.

[0070] The liquid crystal display device of the present invention is characterized by comprising a cellulose acylate film containing a specific ultraviolet absorber, specifically, a polarizer disposed on at least one layer of liquid crystal cells comprises the cellulose acylate film containing a specific ultraviolet absorber of the present invention, and the film on the liquid crystal cell side of the polarizer is the cellulose acylate film containing a specific ultraviolet absorber of the present invention. The cellulose acylate film containing a specific ultraviolet absorber and the polarizer of the present invention can be used in liquid crystal display devices with various driving systems, such as STN, TN, OCB, HAV, VA, IPS, and OCB. In particular, it is preferably used in VA-type liquid crystal display devices. Specifically, even when used in liquid crystal display devices with large screens of 30 inches or larger, it can reduce coloration during black display due to light leakage and improve visibility such as front contrast. As described above, the liquid crystal display device of the present invention exhibits excellent visibility characteristics.

[0071] Example 1

[0072] Preparation of cellulose solution:

[0073] Cellulose resin: 100 parts by weight

[0074] Sugar ester plasticizer (TZ-1): 8.0 parts by weight

[0075] Ultraviolet absorber (I-1): 0.7 parts by weight

[0076] Ultraviolet absorber (Ⅱ-1): 0.05 parts by weight

[0077] Dichloromethane: 300 parts by weight

[0078] Methanol: 50 parts by weight

[0079] Silica microparticles (R972): 0.1 parts by weight

[0080] The process involves mixing the above-mentioned raw materials to prepare a cellulose solution, filtering it, and then discharging the cellulose solution onto a casting support through a casting mold. Once the cast film on the support has the necessary support properties, the cast film is peeled off from the casting support to form a wetted film. The wetted film is then dried, formed into a film, and wound up to obtain a cellulose acylated film with a thickness of 40 μm.

[0081] Other embodiments were prepared in the same manner as in Example 1, except that the plasticizer and ultraviolet absorber in the cellulose solution were different. Specific embodiments are shown in Table 1 below, and Examples 2-10 and Comparative Examples 1-5 were prepared.

[0082] Table 1 Examples 2-10 and Comparative Examples 1-5

[0083]

[0084]

[0085] Note: FLEX-80, FLEX-290, and FLEX-314 are polyol ester plasticizers; 6510A and 6540A are polyester plasticizers; TZ-1 and TZ-2 are sugar ester plasticizers; UV360, UV928, UV-P, and UV234 are benzotriazole UV absorbers; UV400, UV405, and UV1164 are triazine UV absorbers.

[0086] The cellulose acylated membranes prepared in Examples 1 to 10 and Comparative Examples 1 to 5 were evaluated using the following methods:

[0087] 1. Transmittance

[0088] The transmittance of the prepared cellulose acylated membrane at different wavelengths was measured using a spectrophotometer (model: UV1700) from Shimadzu Corporation.

[0089] 2. Transparency

[0090] The chromaticity index b* of the prepared cellulose acylated membrane was determined using a spectrophotometer (model: UV1700) of Shimadzu Corporation.

[0091] 3. Light transmittance / haze

[0092] The prepared cellulose acylated membrane was subjected to transmittance / haze testing using a transmittance / haze meter (model: WGT-S) from Shanghai Precision Scientific Instruments.

[0093] 4. Damp heat durability assessment

[0094] After the cellulose acylated membrane was placed in a high-temperature and high-humidity environment of 85°C and 85%RH for 1000 hours, the transmittance and color index b* at different wavelengths were measured using a spectrophotometer (model: UV1700) from Shimadzu Corporation.

[0095] The degree of transmittance reduction at 380nm = (Transmittance at 380nm after damp heat resistance - Transmittance at 380nm before damp heat resistance) / Transmittance at 380nm before damp heat resistance × 100%

[0096] △b* = b* after damp heat resistance - b* before damp heat resistance

[0097] The cellulose acylated membranes prepared in Examples 1 to 10 and Comparative Examples 1 to 5 were evaluated according to the above evaluation method, and the evaluation results are shown in Table 2:

[0098] Table 2 Evaluation results of the cellulose acylated membranes prepared in Examples 1 to 10 and Comparative Examples 1 to 5

[0099]

[0100] Table 2 shows that when a specific UV absorber with a particular structure is added to the cellulose acylated membrane and used in combination with other UV absorbers, it can effectively block UV rays below 380nm. The chromaticity index b* in the L*a*b* color is also relatively small, indicating a mild degree of yellowing. After damp heat aging, the transmittance at 380nm and the change in b* value are small, indicating that the sample can still effectively block UV rays after damp heat aging and maintain good transparency. Comparative Examples 1-5 also show that when the amount of UV absorber added is small, it cannot effectively block UV rays below 380nm. When the amount added increases, the chromaticity index b* increases, indicating that the cellulose acylated membrane yellows, and the transmittance at 380nm decreases significantly after damp heat aging, indicating that it cannot effectively block UV rays.

Claims

1. A cellulose acylated membrane containing a specific ultraviolet absorber, characterized in that... It contains plasticizers and two or more specific ultraviolet absorbers, at least one of which must meet the following requirements: its absorption capacity is mainly concentrated in the 315nm-400nm wavelength band, and the absorption in this band accounts for more than 75% of its total absorption in the 250nm-600nm wavelength band. The specific ultraviolet absorbers are hydroxyphenylbenzotriazole (general formula I) and aminobutadiene (general formula II) or a combination thereof, and the compounds are represented by general formulas (I) and (II), respectively. General formula (I): General formula (II): R1 to R6 each represent a hydrogen atom, halogen, alkyl, alkoxy, hydroxyl, carboxyl, or amide group, and they may further have substituents; R7 and R8 respectively represent -COOH, -COOR9, -COR9, -CN, or -SO2R. 10 ; R9 and R 10 Each represents an alkyl or aryl group, wherein the alkyl group optionally contains one or more heteroatoms selected from N, O, Si, and S.

2. The cellulose acylated membrane containing a specific ultraviolet absorber as described in claim 1, characterized in that... The specific ultraviolet absorber, wherein aminobutadiene (general formula II) is represented by the following general formula (III): Among them, R5, R6, R7 and R 10 As defined in claim 1.

3. The cellulose acylated membrane containing a specific ultraviolet absorber as described in claim 1, characterized in that... After being subjected to damp heat aging, the transmittance of the cellulose acylated membrane at a wavelength of 380 nm decreased by less than 10%, and the color value Δb* was less than 0.

5.

4. The cellulose acylated membrane containing a specific ultraviolet absorber as described in claim 1, characterized in that... The cellulose acylated membrane has a transmittance of less than 10% at a wavelength of 380 nm, and a chromaticity index b* of 0.1 to 1.5 in L*a*b* color.

5. The cellulose acylated membrane containing a specific ultraviolet absorber as described in claim 1, characterized in that... The cellulose acylated membrane contains one or more plasticizers, preferably polyester, polyol ester, or glycol ester plasticizers.

6. The cellulose acylated membrane containing a specific ultraviolet absorber as described in claim 1, characterized in that... The content of a specific ultraviolet absorber in the cellulose acylated membrane is 0.01 to 2.5 wt% of the cellulose resin mass.

7. The cellulose acylated membrane containing a specific ultraviolet absorber as described in claim 1, characterized in that... The thickness of the cellulose acylated membrane is 10 μm to 60 μm.

8. A polarizer, characterized in that... It comprises at least one cellulose acylated membrane containing a specific ultraviolet absorber as described in any one of claims 1 to 7.

9. A liquid crystal display device, characterized in that... It contains at least one polarizer as described in claim 8.

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