WO2016052015A1 - Liquid crystal display apparatus - Google Patents

Abstract

The present invention addresses the problem of providing a liquid crystal display apparatus in which egg-shaped unevenness does not occur, while achieving good productivity even if the thickness of a glass substrate is less than or equal to 0.6 mm. The liquid crystal display apparatus includes: a backlight light source; a polarizing plate, a liquid crystal cell having a liquid crystal layer sandwiched between a pair of glass substrates; and a polarizing plate, in that order. The liquid crystal display apparatus is characterized in that the thickness of at least one of the glass substrates is less than or equal to 0.6 mm; each of the polarizing plates includes a polarizer, a phase-shift film disposed on one face of the polarizer, and a polarizer protecting film disposed on the other face of the polarizer; and the polarizer protecting film has an elastic modulus at 25 °C and 55% RH (E₁) and an elastic modulus at 25 °C and 95% RH (E₂) that satisfy a specific relationship, and has a moisture permeability falling in a specific range.

Description

Liquid crystal display

The present invention relates to a liquid crystal display device. More specifically, the present invention relates to a liquid crystal display device in which egg unevenness does not occur while improving productivity even if the thickness of the glass substrate is 0.6 mm or less.

Demand for liquid crystal display devices is expanding for applications such as liquid crystal televisions and personal computer liquid crystal displays. In general, a liquid crystal display device is composed of a liquid crystal cell in which a transparent electrode, a liquid crystal layer, a color filter, etc. are sandwiched between glass plates, and two polarizing plates provided on both sides thereof. The optical element (also referred to as a polarizing film) is sandwiched between two optical films (for example, a polarizer protective film, a retardation film, etc.).

However, the recent increase in the size and thickness of LCD TV screens, and the use of LED backlights as the light source, an upper polarizing plate (viewing-side polarizing plate) and a lower polarizing plate (with a liquid crystal cell in between) Depending on the combination of the light source side polarizing plate), the liquid crystal panel, the backlight unit, or both of them are deformed due to the design of the liquid crystal display device, and the members are in contact with each other to locally display unevenness (hereinafter referred to as this Such a circular (egg-shaped) display unevenness generated on the display screen of the liquid crystal display device is also referred to as “egg unevenness”), and there has been a demand for improvement.

Here, the details of the occurrence mechanism of egg unevenness are presumed as follows.
In general, when the polarizer is placed under high temperature and high humidity, it tends to relax the orientation, and thus a shrinkage force acts in the orientation direction.
Until now, since the thickness of the glass substrate used in the liquid crystal panel has been 0.7 mm or more, even if a conventional film (see, for example, Patent Documents 1 to 3) is used as a polarizer protective film, the glass Due to the rigidity, the contraction of the polarizer was suppressed, and the liquid crystal panel did not warp.
However, recently, the thickness of the glass substrate has become 0.6 mm or less due to the need for thinning of the liquid crystal television screen, and the ability of the glass substrate to suppress the contraction of the polarizer has decreased. As a result, the liquid crystal panel warps and swells toward the backlight unit, so that the liquid crystal panel and the backlight unit are partially in contact with each other, and thus egg unevenness is generated.
Thus, conventionally, it has been considered that egg unevenness of a liquid crystal display device is mainly caused by contraction of a polarizer among members of a liquid crystal panel.

However, in recent years, it has been found that there is a cause in the polarizer protective film.
That is, the polarizer protective film having a high elastic modulus under normal temperature and normal humidity has a large decrease in the elastic modulus in a high humidity environment, so that the contraction of the polarizer cannot be suppressed.
In order to suppress the decrease in the elastic modulus under high humidity, a method using a hydrophobic polarizer protective film that hardly contains water is conceivable.
However, in general, a hydrophobic polarizer protective film has poor moisture permeability and poor dryness, so that when glued to the polarizer with water glue, the glue is difficult to dry. As a result, the liquid crystal display device using the polarizer protective film has a problem that productivity is deteriorated.

International Publication No. 2009/047924 JP 2009-1744 A JP 2009-179731 A

The present invention has been made in view of the above-described problems and circumstances, and a solution to the problem is a liquid crystal display in which egg unevenness does not occur while improving productivity even when the thickness of the glass substrate is 0.6 mm or less. Is to provide a device.

In order to solve the above problems, the present inventor, in the process of examining the cause of the above problems, and the like, if the polarizer protective film has a specific elastic modulus and a specific moisture permeability, the thickness of the glass substrate is 0. Even when the thickness is 6 mm or less, the warpage of the liquid crystal panel due to the contraction of the polarizer can be suppressed, so that egg unevenness does not occur, and furthermore, the drying property of the polarizer protective film can be improved. It has been found that a liquid crystal display device having good properties can be provided, and the present invention has been achieved.
That is, the said subject which concerns on this invention is solved by the following means.

1. A liquid crystal display device comprising a backlight source, a polarizing plate, a liquid crystal cell having a liquid crystal layer between a pair of glass substrates, and a polarizing plate in this order,
The thickness of at least one of the glass substrates is 0.6 mm or less,
The polarizing plate has a polarizer, a retardation film disposed on one surface of the polarizer, and a polarizer protective film disposed on the other surface of the polarizer,
The polarizer protective film is
Modulus at 25 ℃ · 55% RH and (E ₁₎ and the elastic modulus at 25 ℃ · 95% RH (E 2) , but satisfy the relationship of the following formula (1),
Equation _{(1): 0.95 ≦ E 1} / E 2 ≦ 1.30
A liquid crystal display device having a moisture permeability measured in a range of 200 to 2000 g / m ² · 24 h measured at 40 ° C. and 90% RH.

2. The polarizer protective film is
Modulus at 25 ℃ · 55% RH and (E ₁₎ and the elastic modulus at 25 ℃ · 95% RH (E 2) , and the equations (2) satisfy the relation of the following formula (2): 1.01 ≦ E ₁ / E ₂ ≦ 1.20
2. A liquid crystal display device according to item 1 above.

3. The polarizer protective film is
3. The liquid crystal display device according to item 1 or 2, wherein the moisture permeability measured at 40 ° C. and 90% RH is in the range of 300 to 1500 g / m ² · 24 h.

4. The polarizer protective film is a cellulose ester film having a total substitution degree of 2.2 or more and a substitution degree by an aromatic acyl group of 0.2 or more. 4. The liquid crystal display device according to any one of items 3 to 3.

By the above means of the present invention, it is possible to provide a liquid crystal display device in which egg unevenness does not occur while improving productivity even when the thickness of at least one glass substrate is 0.6 mm or less.
The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.

Modulus at 25 ℃ · 55% RH (E 1) and the elastic modulus at 25 ℃ · 95% RH and (E _2), but the liquid crystal device a polarizing plate including a polarizer protective film satisfies the relation of the formula (1) If used, the polarizer protective film can suppress the shrinkage of the polarizer, as a result, even if the thickness of at least one glass substrate is 0.6 mm or less, the liquid crystal panel does not warp, As a result, it has been found that a liquid crystal display device in which egg unevenness does not occur can be provided.
Furthermore, it has been found that a polarizer protective film satisfying a specific relationship of moisture permeability at 40 ° C. and 90% RH has a high drying property, so that the paste can be easily dried, and that the productivity of the liquid crystal display device itself can be improved. Invented.
In addition, when the moisture permeability of the polarizer protective film is less than 200 g / m ² · 24 h, drying of water paste used for bonding the film and the polarizer is slow at the time of producing the polarizing plate, so that the production speed of the liquid crystal display device is increased. Moreover, when it is larger than 2000 g / m ² · 24 h, the entry and exit of water into the polarizer cannot be controlled, and hydrolysis of boric acid bridges in the polarizer is promoted. As a result, the orientation of the iodine complex that has been immobilized in the oriented state is lowered, so that the polarization performance of the polarizer is deteriorated, and further, the liquid crystal display device is deteriorated.

In addition, as a specific means for setting the elastic modulus E ₁ and E ₂ and moisture permeability of the polarizer protective film within the above ranges, the present inventor made the hydroxy group of cellulose acetate (polarizer protective film) more hydrophobic. It has also been found that the polarizer protective film according to the present invention can be produced by replacing with a typical substituent.
In addition, since such substitution usually increases hydrophobicity, it is expected that the moisture permeability of the polarizer protective film will decrease.
However, when the present inventors replace the hydroxy group of cellulose acetate with a hydrophobic substituent at a specific ratio, the moisture content can be lowered while maintaining high moisture permeability, and thus the humidity of the elastic modulus. It has been found that the dependency can be greatly reduced and the drying property is also good, so that it can be applied to a liquid crystal display device in which egg unevenness does not occur while improving productivity.

Schematic illustrating an example of a configuration of a liquid crystal display device of the present invention The figure which showed typically an example of the dope preparation process, casting process, and drying process of a solution casting film forming method

The liquid crystal display device of the present invention is a liquid crystal display device comprising a backlight source, a polarizing plate, a liquid crystal cell having a liquid crystal layer between a pair of glass substrates, and a polarizing plate in this order, and comprising at least one glass substrate. The thickness is 0.6 mm or less, the polarizing plate is a polarizer, a retardation film disposed on one surface of the polarizer, and a polarizer protection disposed on the other surface of the polarizer It comprises a film, a, the polarizer protective film, elastic modulus at 25 ℃ · 55% RH (E 1) and the elastic modulus at 25 ℃ · 95% RH and (E _2), but the above formula (1) The moisture permeability measured by satisfying the relationship and measured at 40 ° C. and 90% RH is in the range of 200 to 2000 g / m ² · 24 h. This feature is a technical feature common to the inventions according to claims 1 to 4.

The embodiments of the present invention, the polarizer protective film, elastic modulus at 25 ℃ · 55% RH (E 1) and the elastic modulus at 25 ℃ · 95% RH and (E _2), but the formula (2) It is preferable to satisfy the above relationship because a liquid crystal display device can be provided in which egg unevenness does not occur even when the thickness of at least one glass substrate is 0.6 mm or less.

In the present invention, the polarizer protective film has a moisture permeability of 300 to 1500 g / m ² · 24 h measured at 40 ° C. and 90% RH. Is preferable.

In the present invention, at least one piece of the polarizer protective film is a cellulose ester film having a total degree of substitution of 2.2 or more and a degree of substitution with an aromatic acyl group of 0.2 or more. Even if the thickness of the glass substrate is 0.6 mm or less, it is preferable because it is possible to provide a liquid crystal display device in which egg unevenness does not occur more while improving productivity.

Hereinafter, the present invention, its constituent elements, and modes and modes for carrying out the present invention will be described in detail. In the present application, “˜” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.

≪Overview of liquid crystal display device≫
The liquid crystal display device of the present invention is a liquid crystal display device comprising a backlight source, a polarizing plate, a liquid crystal cell having a liquid crystal layer between a pair of glass substrates, and a polarizing plate in this order, and comprising at least one glass substrate. The thickness is 0.6 mm or less, the polarizing plate is a polarizer, a retardation film disposed on one surface of the polarizer, and a polarizer protection disposed on the other surface of the polarizer comprises a film, a, the polarizer protective film, elastic modulus at 25 ℃ · 55% RH (E 1) and the elastic modulus at 25 ℃ · 95% RH and (E ₂₎ is the following formula (1) Meet relationships,
Equation _{(1): 0.95 ≦ E 1} / E 2 ≦ 1.30
Further, the moisture permeability measured at 40 ° C. and 90% RH is in the range of 200 to 2000 g / m ² · 24 h.

<Configuration of liquid crystal display device>
As an example of the configuration of a conventional liquid crystal display device, in the direct type, as shown in FIG. 1, from the backlight source side [backlight light source 1a, light source side polarizing plate PL2, liquid crystal cell 9a, and viewing side polarizing plate PL1] This configuration is mainly used for large liquid crystal display devices such as televisions. On the other hand, a small liquid crystal display device for mobile use has a sidelight type (not shown).

The diffusing plate (lower diffusing sheet) 3a is an optical sheet having a strong light diffusing property for mainly reducing in-plane luminance unevenness of the backlight unit (BLU) 6a, and the condensing sheet transmits diffused light to the liquid crystal display device 100. An optical sheet for condensing light in the front direction (normal direction of the display device plane), and the upper diffusion sheet reduces moiré caused by a periodic structure such as a prism sheet as a light condensing sheet and pixels in the liquid crystal cell 9a. It is an optical sheet used for further reducing in-plane luminance unevenness that cannot be removed by the lower diffusion sheet.

The liquid crystal cell 9a usually has a configuration in which a transparent electrode, a liquid crystal layer 7a, a color filter and the like are sandwiched between glass substrates.
As the display method of the liquid crystal cell 9a, modes such as twisted nematic (TN), super twisted nematic (STN), vertical alignment (VA), in-plane switching (IPS), optically compensated bend cell (OCB), etc. The transmissive, reflective or transflective liquid crystal display device 100 can be preferably used.

As the light emitting light source 2a (light emitting body) used for the backlight light source 1a, CCFL (Cold Cathode Fluorescent Lamp), HCFL (Hot Cathode Fluorescent Lamp, hot cathode tube), LED (Light Emitting Diode, light emitting diode) , OLED (Organic
Light-emitting diodes, organic light emitting diodes [organic EL], inorganic EL, and the like can be preferably used.

As shown in FIG. 1, a liquid crystal display device is generally composed of a liquid crystal cell sandwiched between substrates such as a glass plate and two polarizing plates PL1 and PL2 provided on both sides of the liquid crystal cell. Among these polarizing plates, one polarizing plate disposed on the viewing side (upper side) is referred to as a viewing side polarizing plate PL1, and the polarizing plate disposed on the backlight source 1a side (lower side) is referred to as a light source side polarizing plate PL2. These polarizing plates are configured by sandwiching a polarizer (also referred to as a polarizing film) between two optical films. The polarizing plate PL1 is composed of two optical films, a polarizer protective film T1 and a retardation film T2, with a polarizer interposed therebetween. The polarizing plate PL2 is similarly configured by sandwiching a polarizer between optical films of a retardation film T3 and a polarizer protective film T4. Here, the retardation films T2 and T3 are arranged on the liquid crystal cell side.

<Backlight source>
The backlight light source according to the present invention is not particularly limited, and a known light source can be used, and includes, for example, a flat fluorescent lamp, red (R), green (G), and blue (B) light emitting diodes (LEDs). A light emitting diode (LED) backlight, a white backlight using an organic electroluminescence element substrate, or the like can be used.

<Liquid crystal cell>
In the liquid crystal panel constituting the liquid crystal display device of the present invention, the liquid crystal cell is not particularly limited as long as it has a liquid crystal layer between a pair of glass substrates, and any liquid crystal cell can be used. The liquid crystal cell is preferably composed of a glass substrate 8a and a transparent electrode sandwiched between the glass substrates, a liquid crystal layer, a color filter, and the like.

(Glass substrate)
In the liquid crystal display device of the present invention, the thickness of at least one glass substrate is 0.6 mm or less.
In the glass substrate according to the present invention, the average light transmittance in the visible light region is preferably 60% or more, more preferably 70% or more, and further preferably 80% or more.
Examples of the glass material include silica glass, soda lime silica glass, lead glass, borosilicate glass, and alkali-free glass. On the surface of these glass materials, from the viewpoint of adhesion with adjacent layers, durability, and smoothness, a physical treatment such as polishing, a coating made of an inorganic material or an organic material, or these coatings, if necessary. A combined hybrid coating can be formed.
In a liquid crystal cell, a pixel electrode and a counter electrode for applying a voltage to liquid crystal are disposed on one glass substrate of a pair of glass substrates.

(Liquid crystal layer)
The liquid crystal layer is not particularly limited and may be a known one. For example, when the liquid crystal cell display method is an IPS (In-Plane Switching) method, the positive dielectric anisotropy (Δε> 0) or negative It is preferable to include liquid crystal molecules having a dielectric anisotropy (Δε> 0). In this case, the liquid crystal molecules are aligned horizontally with respect to the substrate surface when no voltage is applied.
In the liquid crystal cell configured in this way, an electric field in the horizontal direction is generated between the pixel electrode provided on one glass substrate and the counter electrode, with respect to the glass substrate surface. Thereby, the liquid crystal molecules horizontally aligned with respect to the glass substrate surface are rotated in a plane parallel to the glass substrate surface. Thereby, the liquid crystal molecules are driven, and the image display is performed by changing the transmittance and reflectance of each sub-pixel.

<Polarizing plate>
The polarizing plate is a polarizer, a polarizer disposed on both sides thereof, a retardation film disposed on one surface of the polarizer, a polarizer protective film disposed on the other surface of the polarizer, At least. This polarizing plate has a function of converting natural light or polarized light into arbitrary polarized light such as linearly polarized light, circularly polarized light, and elliptically polarized light.

(Polarizer)
A polarizer, which is a main component of a polarizing plate, is an element that allows only light of a polarization plane in a certain direction to pass through. A typical polarizer currently known (also referred to as a polarizing film) is a polyvinyl alcohol type polarized light. There are two types of films: one obtained by dyeing iodine on a polyvinyl alcohol film and the other obtained by dyeing a dichroic dye.

The polarizer is formed by forming a polyvinyl alcohol aqueous solution into a film and dyeing the film by uniaxial stretching or dyeing or uniaxially stretching, and then performing a durability treatment with a boron compound.

(Polarizer protective film)
The polarizer protective film is disposed on the viewing side in the polarizing plate PL1, and is disposed on the backlight source 1a side in the polarizing plate PL2. In FIG. 1, T1 and T4 are polarizer protective films.
In the present invention, the polarizer protective film is filled elastic modulus at 25 ℃ · 55% RH (E 1) and the elastic modulus at 25 ℃ · 95% RH and (E _2), but the relationship of the following formula (1) ,
Equation _{(1): 0.95 ≦ E 1} / E 2 ≦ 1.30
The moisture permeability measured at 40 ° C. and 90% RH is in the range of 200 to 2000 g / m ² · 24 h.

Incidentally, the polarizer protective film has an elastic modulus at 25 ℃ · 55% RH (E 1) and the elastic modulus at 25 ℃ · 95% RH and (E _2), and the equations (2 satisfy the relation of the following formula (2) ): 1.01 ≦ E ₁ / E ₂ ≦ 1.20
More preferably.

Further, the polarizer protective film preferably has a moisture permeability measured in a range of 300 to 1500 g / m ² · 24 h, measured at 40 ° C. and 90% RH.

Although the material which manufactures a polarizer protective film is not specifically limited, For example, the below-mentioned film material can be used conveniently. Among them, a cellulose ester film composed of a cellulose ester resin having a total substitution degree of 2.2 or more and of which the substitution degree with an aromatic acyl group is 0.2 or more, is preferably 25 ° C. modulus at 55% RH and (E ₁₎ and the elastic modulus at 25 ℃ · 95% RH (E 2) , but satisfy the relationship of formula (1), and were measured at 40 ℃ · 90% RH, a moisture permeability However, it can be in the range of 200 to 2000 g / m ² · 24 h, which is preferable.
The polarizer protective film is more preferably a cellulose ester film having a total degree of substitution of 2.6 or more and a degree of substitution with an aromatic acyl group of 0.6 or more.

(Measurement of elastic modulus)
The elastic modulus (tensile elastic modulus) can be measured according to the method described in JIS K 7127.
Specifically, for example, measurement can be performed using Tensilon RTC-1225A manufactured by Orientec Co., Ltd. and a constant temperature and humidity chamber TLF-R3T-F-HS-W as a tensile tester and a constant temperature and humidity chamber.
As measurement conditions, for example, the film was cut into a size of 70 mm × 10 mm, and held for 1 hour in a constant temperature and humidity chamber maintained at a predetermined temperature and humidity (25 ° C./55% RH or 25 ° C./95% RH), The distance between chucks can be 50 mm and the test speed can be 100 mm / min.

(Measurement of moisture permeability)
The moisture permeability can be measured by allowing the film to be measured to stand for 24 hours under the conditions of a temperature of 40 ° C. and a humidity of 90% RH based on the cup method described in JIS Z 0208.

(Retardation film)
The retardation film according to the present invention is not particularly limited as long as a known film can be used and can be used for viewing angle expansion having a desired retardation. As a material for producing the retardation film, for example, a film material described later can be suitably used as in the case of the polarizer protective film.

(Film material)
The film material used for manufacture of a phase difference film and a polarizer protective film is not specifically limited, For example, an acrylic resin, a cellulose ester resin, a cellulose resin, and a cycloolefin resin are used preferably. These resins are preferable because of their transparency.
In addition, in the following description, when it is not necessary to distinguish especially, polarizer protective film T1 and T4 and retardation film T2 and T3 are put together, and are also called an optical film.

(acrylic resin)
The acrylic resin as the film material according to the present invention includes a methacrylic resin. The resin is not particularly limited, but a resin comprising 50 to 99% by mass of methyl methacrylate units and 1 to 50% by mass of other monomer units copolymerizable therewith is preferable.

As the acrylic resin and the methacrylic resin, a (meth) acrylic monomer alone or a copolymer, or a copolymer of a (meth) acrylic monomer and a copolymerizable monomer can be used. Examples of (meth) acrylic monomers include (meth) acrylic acid; methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, t-butyl (meth) acrylate, ( (Meth) acrylic acid isobutyl, (meth) acrylic acid hexyl, (meth) acrylic acid octyl, (meth) acrylic acid 2-ethylhexyl (meth) acrylic acid C1-10 alkyl; (meth) acrylic acid phenyl etc. ) Aryl acrylate; hydroxyalkyl (meth) acrylates such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate; glycidyl (meth) acrylate; N, N-dialkylaminoalkyl (meth) acrylate; (meth) acrylonitrile; Alicyclic hydrocarbon groups such as tricyclodecane Such as (meth) acrylate can be exemplified. Examples of the copolymerizable monomer include styrene monomers, vinyl ester monomers, maleic anhydride, maleic acid, and fumaric acid. These monomers can be used alone or in combination of two or more.

Examples of (meth) acrylic resins include poly (meth) acrylic esters such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer, methyl methacrylate- (meth) acrylic acid ester copolymer Examples thereof include methyl methacrylate-acrylic acid ester- (meth) acrylic acid copolymer, (meth) acrylic acid ester-styrene copolymer (MS resin, etc.), and the like. Preferable (meth) acrylic resins include C1-6 alkyl poly (meth) acrylates such as poly (meth) methyl acrylate, particularly methyl methacrylate as a main component (50 to 100% by mass, preferably 70 to 100% by mass). % Methyl) resin.

Among these, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, s-butyl acrylate, 2-ethylhexyl acrylate, and the like are preferable from the viewpoint of thermal decomposition resistance and fluidity of the copolymer. n-Butyl acrylate is particularly preferably used.

The acrylic resin as the film material according to the present invention preferably has a weight average molecular weight (Mw) of 80000 or more from the viewpoint of improving brittleness as an optical film. It is preferable for the acrylic resin to have a weight average molecular weight (Mw) of 80000 or more because brittleness can be improved. The weight average molecular weight (Mw) of the acrylic resin is more preferably in the range of 80,000 to 1,000,000, particularly preferably in the range of 100,000 to 600,000, and most preferably in the range of 150,000 to 400,000. Although the upper limit of the weight average molecular weight (Mw) of an acrylic resin is not specifically limited, It is a preferable form that it shall be 1 million or less from a viewpoint on manufacture.

(Cellulose ester resin)
The cellulose ester resin used in the film material according to the present invention is not particularly limited, but the ester group is preferably a linear or branched carboxylic acid ester having about 2 to 22 carbon atoms. A ring may be formed, and an ester of an aromatic carboxylic acid may be used. In addition, these carboxylic acids may have a substituent. The cellulose ester is particularly preferably a lower fatty acid ester having 6 or less carbon atoms.

Specific examples of preferred cellulose ester resins include cellulose acetate, propionate groups or butyrate groups in addition to acetyl groups such as cellulose acetate propionate, cellulose acetate butyrate, and cellulose acetate propionate butyrate. And a mixed fatty acid ester of cellulose.

The weight average molecular weight (Mw) of the cellulose ester resin used in the optical film according to the present invention is 75,000 or more, preferably in the range of 75,000 to 300,000, and more preferably in the range of 100,000 to 24,000, Those of 160000 to 240000 are particularly preferred. If the important average molecular weight (Mw) of a cellulose ester resin is 75000 or more, the self-film-forming property and adhesion improving effect of the cellulose ester resin layer itself are exhibited, which is preferable. In the present invention, two or more kinds of cellulose resins can be mixed and used.

The average molecular weight (Mn, Mw) of the cellulose ester resin can be measured by gel permeation chromatography under the following measurement conditions.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) A calibration curve with 13 samples within the range of Mw = 500 to 2800000 was used. The 13 samples are preferably used at approximately equal intervals.

The film material for producing the polarizer protective films T1 and T4 satisfies the formula (1) and has a moisture permeability of 200 to 2000 g / m ² · 24 h measured at 40 ° C. and 90% RH. It is not particularly limited as long as it is within the range, and for example, an acrylic resin such as polymethyl methacrylate (PMMA) may be used, but a cellulose ester resin is preferable. In particular, the polarizer protective film is particularly preferably a cellulose ester resin (film) having a total substitution degree of 2.2 or more and a substitution degree by an aromatic acyl group of 0.2 or more.
The film material for producing the polarizer protective films T1 and T4 satisfies the formula (1) and has a moisture permeability of 200 to 2000 g / m ² · 24 h measured at 40 ° C. and 90% RH. If it is within the range, a commercially available cellulose ester film (for example, Konica Minoltak KC8UY, KC4UY, KC8UA, KC6UA, KC4UA, KC2UA, KC4AR, KC4CR, KC4DR, KC4FR-3, KC4FR-4, KC4KR, or more Minolta Co., Ltd.) or the like may be used.

(Aromatic acyl group)
The aromatic acyl group (acyl group containing an aromatic group) according to the present invention may be bonded directly to the ester bond portion or may be bonded via a linking group. Direct bonding is preferred. Here, the linking group represents an alkylene group, an alkenylene group or an alkynylene group, and the linking group may have a substituent. The linking group is preferably an alkylene group having 1 to 10 carbon atoms, an alkenylene group and an alkynylene group, more preferably an alkylene group having 1 to 6 carbon atoms and an alkenylene group, most preferably 1 to 4 carbon atoms. Alkylene and alkenylene groups.

In addition, the aromatic group in the aromatic acyl group may have a substituent, and the substituent substituted with the aromatic and the substituent substituted with the above-described linking group include, for example, an alkyl group (preferably The number of carbon atoms is 1 to 20, more preferably 1 to 12, and particularly preferably 1 to 8. For example, methyl, ethyl, propyl, isopropyl, tert-butyl, n-butyl, n- Octyl group, n-decyl group, n-hexadecyl group, cyclopropyl group, cyclopentyl, cyclohexyl group and the like), alkenyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, particularly preferably 2). -8, for example, vinyl group, allyl group, 2-butenyl group, 3-pentenyl group, etc.), alkynyl group (preferably having 2-20 carbon atoms, More preferably, it is 2 to 12, particularly preferably 2 to 8, and examples thereof include a propargyl group, 3-pentynyl group and the like, an aryl group (preferably having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly Preferably, it is 6 to 12, and examples thereof include a phenyl group, a biphenyl group, a naphthyl group, and the like, an amino group (preferably having 0 to 20 carbon atoms, more preferably 0 to 10, and particularly preferably 0 to 6). For example, an amino group, a methylamino group, a dimethylamino group, a diethylamino group, a dibenzylamino group, etc.), an alkoxy group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 12 carbon atoms). 8 such as a methoxy group, an ethoxy group, and a butoxy group), an aryloxy group (preferably having 6 to 2 carbon atoms) More preferably 6 to 16, particularly preferably 6 to 12, for example, phenyloxy group, 2-naphthyloxy group and the like, acyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 2 carbon atoms). 16, particularly preferably 1 to 12, for example, acetyl group, benzoyl group, formyl group, pivaloyl group and the like, alkoxycarbonyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly Preferably, it is 2 to 12, for example, methoxycarbonyl group, ethoxycarbonyl group, etc.), aryloxycarbonyl group (preferably having 7 to 20, more preferably 7 to 16, particularly preferably 7 to 10 carbon atoms). Yes, such as a phenyloxycarbonyl group), an acyloxy group (preferably the number of carbon atoms) 2 to 20, more preferably 2 to 16, particularly preferably 2 to 10, and examples thereof include an acetoxy group and a benzoyloxy group), an acylamino group (preferably having 2 to 20 carbon atoms, and more preferably 2 to 2 carbon atoms). 16, particularly preferably 2 to 10, for example, an acetylamino group, a benzoylamino group, etc.), an alkoxycarbonylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 and particularly preferably 2). To 12 and includes, for example, a methoxycarbonylamino group), an aryloxycarbonylamino group (preferably having 7 to 20 carbon atoms, more preferably 7 to 16 carbon atoms, particularly preferably 7 to 12 carbon atoms such as phenyloxy Carbonylamino group), sulfonylamino group (preferably the number of carbon atoms) -20, more preferably 1-16, particularly preferably 1-12, such as methanesulfonylamino group, benzenesulfonylamino group, etc.), sulfamoyl group (preferably having 0-20 carbon atoms, more preferably 0 to 16, particularly preferably 0 to 12, and examples thereof include a sulfamoyl group, a methylsulfamoyl group, a dimethylsulfamoyl group, and a phenylsulfamoyl group), a carbamoyl group (preferably having a carbon number of 1 to 20, more preferably 1 to 16, particularly preferably 1 to 12, and examples thereof include a carbamoyl group, a methylcarbamoyl group, a diethylcarbamoyl group, a phenylcarbamoyl group, and the like, an alkylthio group (preferably having 1 to 20 carbon atoms). More preferably 1 to 16, particularly preferably 1 to 12. For example, a methylthio group, an ethylthio group, etc.), an arylthio group (preferably 6-20 carbon atoms, more preferably 6-16, particularly preferably 6-12, such as a phenylthio group). A sulfonyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 and particularly preferably 1 to 12 such as mesyl group and tosyl group), sulfinyl group (preferably having 1 carbon atom) -20, more preferably 1-16, particularly preferably 1-12, such as methanesulfinyl group, benzenesulfinyl group, etc., ureido group (preferably having 1-20 carbon atoms, more preferably 1-20 carbon atoms). 16, particularly preferably 1 to 12, and examples thereof include a ureido group, a methylureido group, and a phenylureido group. Phosphoric acid amide group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 and particularly preferably 1 to 12 such as diethyl phosphoric acid amide and phenylphosphoric acid amide), Hydroxy group, mercapto group, halogen atom (eg fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxy group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, heterocyclic ring A group (preferably having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms, and examples of the hetero atom include a nitrogen atom, an oxygen atom, and a sulfur atom, specifically, for example, an imidazolyl group, a pyridyl group, a quinolyl group, and a furyl group. Group, piperidyl group, morpholino group, benzoxazolyl group, benzimidazolyl group, benzthiazolyl group, etc. And a silyl group (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, particularly preferably 3 to 24 carbon atoms such as a trimethylsilyl group and a triphenylsilyl group). . These substituents may be further substituted. Moreover, when there are two or more substituents, they may be the same or different. If possible, they may be linked together to form a ring.

The aromatic group possessed by the aromatic acyl group according to the present invention may be an aromatic hydrocarbon group or an aromatic heterocyclic group, more preferably an aromatic hydrocarbon group.
The aromatic hydrocarbon group preferably has 6 to 24 carbon atoms, more preferably 6 to 12, and most preferably 6 to 10. Specific examples of the aromatic hydrocarbon group include a phenyl group, a naphthyl group, an anthryl group, a biphenyl group, a terphenyl group, and the like, and more preferably a phenyl group. As the aromatic hydrocarbon group, a phenyl group, a naphthyl group, and a biphenyl group are particularly preferable. As the aromatic heterocyclic group, those containing at least one of an oxygen atom, a nitrogen atom or a sulfur atom are preferred. Specific examples of the heterocycle include, for example, furan, pyrrole, thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiazoline, thiadiazole, oxazoline, oxazole, oxadiazole, quinoline. , Isoquinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzthiazole, benzotriazole, tetrazaindene and the like. As the aromatic heterocyclic group, a pyridyl group, a triazinyl group, and a quinolyl group are particularly preferable.

Preferred as the aromatic acyl group are phenylacetyl group, hydrocinnamoyl group, diphenylacetyl group, phenoxyacetyl group, benzyloxyacetyl group, O-acetylmandelyl group, 3-methoxyphenylacetyl group, 4-methoxyphenylacetyl group 2,5-dimethoxyphenylacetyl group, 3,4-dimethoxyphenylacetyl group, 9-fluorenylmethylacetyl group, cinnamoyl group, 4-methoxy-cinnamoyl group, benzoyl group, phenylbenzoyl group, ortho-toluoyl group, Meta-toluoyl group, para-toluoyl group, m-anisoyl group, p-anisoyl group, phenylbenzoyl group, 4-ethylbenzoyl group, 4-propylbenzoyl group, 4-t-butylbenzoyl group, 4-butylbenzoyl group, 4-pentylbenzo Group, 4-hexylbenzoyl group, 4-heptylbenzoyl group, 4-octylbenzoyl group, 4-vinylbenzoyl group, 4-ethoxybenzoyl group, 4-butoxybenzoyl group, 4-hexyloxybenzoyl group, 4-heptyl Roxybenzoyl group, 4-pentyloxybenzoyl group, 4-octyloxybenzoyl group, 4-nonyloxybenzoyl group, 4-decyloxybenzoyl group, 4-undecyloxybenzoyl group, 4-dodecyloxybenzoyl group, 4-isopropyl Oxybenzoyl group, 2,3-dimethoxybenzoyl group, 2,5-dimethoxybenzoyl group, 3,4-dimethoxybenzoyl group, 2,6-dimethoxybenzoyl group, 2,4-dimethoxybenzoyl group, 3,5-dimethoxybenzoyl group Group, 3,4,5-trimethoxybenzoyl group, 2 4,5-trimethoxybenzoyl group, 1-naphthoyl group, 2-naphthoyl group, 2-biphenylcarbonyl group, 4-biphenylcarbonyl group, 4'-ethyl-4-biphenylcarbonyl group, 4'-octyloxy-4-biphenyl Carbonyl group, piperonyl group, diphenylacetyl group, triphenylacetyl group, phenylpropionyl group, hydrocinnamoyl group, α-methylhydrocinnamoyl group, 2,2-diphenylpropionyl group, 3,3-diphenylpropionyl group, 3, 3,3-triphenylpropionyl group, 2-phenylbutyryl group, 3-phenylbutyryl group, 4-phenylbutyryl group, 5-phenylvaleryl group, 3-methyl-2-phenylvaleryl group, 6- Phenylhexanoyl group, α-methoxyphenylacetyl group, phenoxy Acetyl group, 3-phenoxypropionyl group, 2-phenoxypropionyl group, 11-phenoxydecanoyl group, 2-phenoxybutyryl group, 2-methoxyacetyl group, 3- (2-methoxyphenyl) propionyl group, 3- (p -Toluyl) propionyl group, (4-methylphenoxy) acetyl group, 4-isobutyl-α-methylphenylacetyl group, 4- (4-methoxyphenyl) butyryl group, (2,4-di-t-pentylphenoxy)- Acetyl group, 4- (2,4-di-t-pentylphenoxy) -butyryl group, (3,4-dimethoxyphenyl) acetyl group, 3,4- (methylenedioxy) phenylacetyl group, 3- (3 4-dimethoxyphenyl) propionyl group, 4- (3,4-dimethoxyphenyl) butyryl group, (2,5-dimethoxy) Phenyl) acetyl group, (3,5-dimethoxyphenyl) acetyl group, 3,4,5-trimethoxyphenylacetyl group, 3- (3,4,5-trimethoxyphenyl) -propionyl group, acetyl group, 1- Naphthylacetyl group, 2-naphthylacetyl group, α-trityl-2-naphthalene-propionyl group, (1-naphthoxy) acetyl group, (2-naphthoxy) acetyl group, 6-methoxy-α-methyl-2-naphthaleneacetyl group 9-fluoreneacetyl group, 1-pyreneacetyl group, 1-pyrenebutyryl group, γ-oxo-pyrenebutyryl group, styreneacetyl group, α-methylcinnamoyl group, α-phenylcinnamoyl group, 2-methylcinnamoyl group, 2-methoxycinnamoyl group, 3-methoxycinnamoyl group, 2,3-dimethoxycinnamoy Group, 2,4-dimethoxycinnamoyl group, 2,5-dimethoxycinnamoyl group, 3,4-dimethoxycinnamoyl group, 3,5-dimethoxycinnamoyl group, 3,4- (methylenedioxy) cinnamoyl group, 3,4,5-trimethoxycinnamoyl group, 2,4,5-trimethoxycinnamoyl group, 3-methylidene-2-carbonyl group, 4- (2-cyclohexyloxy) benzoyl group, 2,3-dimethylbenzoyl Group, 2,6-dimethylbenzoyl group, 2,4-dimethylbenzoyl group, 2,5-dimethylbenzoyl group, 2,4,6-trimethylbenzoyl group, 3-methoxy-4-methylbenzoyl group, 3,4- Diethoxybenzoyl group, α-phenyl-O-toluyl group, 2-phenoxybenzoyl group, 2-benzoylbenzoyl group, 3-benzoy Rubenzoyl group, 4-benzoylbenzoyl group, 2-ethoxy-1-naphthoyl group, 9-fluorenecarbonyl group, 1-fluorenecarbonyl group, 4-fluorenecarbonyl group, 9-anthracenecarbonyl group, 1-pyrenecarbonyl group, etc. Can be mentioned.
Among these, more preferably, benzoyl group, 2,4,6-trimethylbenzoyl group, phenylbenzoyl group, 4-heptylbenzoyl group, 2,4,5-trimethoxybenzoyl group or 3,4,5-trimethoxy It is a benzoyl group.

Unless the function as an optical film is impaired, the optical film which concerns on this invention may contain resin and additives other than a cellulose ester resin, and may be comprised.
When the resin other than the cellulose ester resin is contained, the resin to be added may be mixed without being dissolved even if the resin is in a compatible state.

The total mass of the cellulose ester resin in the optical film according to the present invention is preferably 55% by mass or more of the optical film, more preferably 60% by mass or more, and particularly preferably 70% by mass or more.

When using resins and additives other than cellulose ester resin, it is preferable to adjust the addition amount within a range not impairing the function of the optical film according to the present invention.

(Cycloolefin resin)
The cycloolefin resin as the film material according to the present invention is made of a polymer resin containing an alicyclic structure.

A preferred cycloolefin-based resin is a resin obtained by polymerizing or copolymerizing a cyclic olefin. Examples of the cyclic olefin include norbornene, dicyclopentadiene, tetracyclododecene, ethyltetracyclododecene, ethylidenetetracyclododecene, tetracyclo [7.4.0.110, 13.02,7] trideca-2,4, Polycyclic unsaturated hydrocarbons such as 6,11-tetraene and derivatives thereof; cyclobutene, cyclopentene, cyclohexene, 3,4-dimethylcyclopentene, 3-methylcyclohexene, 2- (2-methylbutyl) -1-cyclohexene, cyclo Examples thereof include monocyclic unsaturated hydrocarbons such as octene, 3a, 5,6,7a-tetrahydro-4,7-methano-1H-indene, cycloheptene, cyclopentadiene, cyclohexadiene, and derivatives thereof. These cyclic olefins may have a polar group as a substituent. Examples of the polar group include a hydroxy group, a carboxy group, an alkoxyl group, an epoxy group, a glycidyl group, an oxycarbonyl group, a carbonyl group, an amino group, an ester group, and a carboxylic acid anhydride group. Or a carboxylic anhydride group is preferred.

Preferred cycloolefin resins may be those obtained by addition copolymerization of monomers other than cyclic olefins. Examples of addition copolymerizable monomers include ethylene, α-olefins such as ethylene, propylene, 1-butene and 1-pentene; 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl- And dienes such as 1,4-hexadiene and 1,7-octadiene.

The cyclic olefin is obtained by an addition polymerization reaction or a metathesis ring-opening polymerization reaction. The polymerization is carried out in the presence of a catalyst. Examples of the addition polymerization catalyst include a polymerization catalyst composed of a vanadium compound and an organoaluminum compound. As a catalyst for ring-opening polymerization, a polymerization catalyst comprising a metal halide such as ruthenium, rhodium, palladium, osmium, iridium, platinum, nitrate or acetylacetone compound, and a reducing agent; or titanium, vanadium, zirconium, tungsten, molybdenum And a polymerization catalyst composed of a metal halide such as acetylacetone compound and an organoaluminum compound. The polymerization temperature, pressure and the like are not particularly limited, but the polymerization is usually carried out at a polymerization temperature of −50 to 100 ° C. and a polymerization pressure of 0 to 490 N / cm ² .

The cycloolefin resin as a film material is preferably a resin obtained by polymerizing or copolymerizing a cyclic olefin and then hydrogenating it to change the unsaturated bond in the molecule to a saturated bond. The hydrogenation reaction is performed by blowing hydrogen in the presence of a known hydrogenation catalyst. Examples of hydrogenation catalysts include cobalt acetate / triethylaluminum, nickel acetylacetonate / triisobutylaluminum, transition metal compounds such as titanocene dichloride / n-butyllithium, zirconocene dichloride / sec-butyllithium, tetrabutoxytitanate / dimethylmagnesium / alkyl. Homogeneous catalyst composed of a combination of metal compounds; heterogeneous metal catalyst such as nickel, palladium, platinum; nickel / silica, nickel / diatomaceous earth, nickel / alumina, palladium / carbon, palladium / silica, palladium / diatomaceous earth And a heterogeneous solid-supported catalyst in which a metal catalyst such as palladium / alumina is supported on a carrier.

Alternatively, the following norbornene-based polymers may also be mentioned as cycloolefin-based resins. The norbornene-based polymer preferably has a norbornene skeleton as a repeating unit, and specific examples thereof include JP-A-62-252406, JP-A-62-2252407, and JP-A-2-133413. JP-A-63-145324, JP-A-63-264626, JP-A-1-240517, JP-B-57-8815, JP-A-5-39403, JP-A-5-43663 JP-A-5-43834, JP-A-5-70655, JP-A-5-279554, JP-A-6-206985, JP-A-7-62028, JP-A-8-176411, Although what was described in Kaihei 9-241484 etc. can be utilized preferably, it is not limited to these. Moreover, these may be used individually by 1 type and may use 2 or more types together.

In the present invention, among the norbornene-based polymers, those having a repeating unit represented by any of the following structural formulas (I) to (IV) are preferable.

In the structural formulas (I) to (IV), A, B, C and D each independently represent a hydrogen atom or a monovalent organic group.

Among the norbornene-based polymers, a polymer obtained by metathesis polymerization of at least one compound represented by the following structural formula (V) or (VI) and an unsaturated cyclic compound copolymerizable therewith. A hydrogenated polymer obtained by hydrogenating is also preferred.

In the structural formula, A, B, C and D each independently represent a hydrogen atom or a monovalent organic group. Here, A, B, C and D are not particularly limited, but preferably an organic group may be linked via a hydrogen atom, a halogen atom, a monovalent organic group or at least a divalent linking group, May be the same or different. A or B and C or D may form a monocyclic or polycyclic structure. Here, the at least divalent linking group includes a hetero atom typified by an oxygen atom, a sulfur atom, and a nitrogen atom, and examples thereof include ether, ester, carbonyl, urethane, amide, thioether, and the like. It is not limited. In addition, the organic group may be further substituted via the linking group.

Other monomers copolymerizable with the norbornene monomer include, for example, ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, Α-olefins having 2 to 20 carbon atoms such as 1-hexadecene, 1-octadecene, 1-eicosene and derivatives thereof; cyclobutene, cyclopentene, cyclohexene, cyclooctene, 3a, 5,6,7a-tetrahydro-4,7- Cycloolefins such as methano-1H-indene and derivatives thereof; non-conjugated dienes such as 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 1,7-octadiene Etc. are used. Of these, α-olefins, particularly ethylene, are preferred.

These other monomers copolymerizable with the norbornene-based monomer can be used alone or in combination of two or more. In the case of addition copolymerization of a norbornene monomer and another monomer copolymerizable therewith, the ratio of the structural unit derived from the norbornene monomer and the structural unit derived from the other monomer copolymerizable in the addition copolymer However, it is appropriately selected so that the mass ratio is usually 30:70 to 99: 1, preferably 50:50 to 97: 3, and more preferably 70:30 to 95: 5.

When the unsaturated bond remaining in the molecular chain of the synthesized polymer is saturated by a hydrogenation reaction, the hydrogenation rate is 90% or more, preferably 95% or more, particularly from the viewpoint of light resistance deterioration, weather resistance deterioration, etc. Preferably it is 99% or more.

In addition, examples of the cycloolefin resin used in the present invention include thermoplastic saturated norbornene resins described in paragraph Nos. [0014] to [0019] of JP-A-5-2108, and paragraph Nos. Of JP-A-2001-277430. [0031] Thermoplastic norbornene polymers described in [0031] to [0031], paragraphs [0008] to [0045] thermoplastic norbornene resins described in JP-A-2003-14901, paragraph numbers [0014] in JP-A-2003-139950 The norbornene-based resin composition described in [0028], the norbornene-based resin described in paragraph Nos. [0029] to [0037] of JP-A No. 2003-161832, and the paragraph numbers [0027] to [0036] of JP-A No. 2003-195268. The norbornene resin described in JP-A-2003-2158 Paragraph Nos. [0009] to [0023] cycloaliphatic structure-containing polymer resin, norbornene polymer resin or vinyl alicyclic hydrocarbon described in JP-A-2003-212588, paragraph Nos. [0008] to [0024] Polymer resin etc. are mentioned.

Specifically, ZEONEX manufactured by Nippon Zeon Co., Ltd., ZEONOR (ZEONOR23, ZEONOR40), Arton manufactured by JSR Co., Ltd., Apel manufactured by Mitsui Chemicals, Inc. (APL8008T, APL6509T, APL6013T, APL5014DP, APL6015T) and the like are preferably used. .

The molecular weight of the cycloolefin resin used in the present invention is appropriately selected according to the purpose of use, but is measured by a gel permeation chromatography method using a cyclohexane solution (or a toluene solution when the polymer resin is not dissolved). When the polyisoprene or polystyrene equivalent weight average molecular weight is usually in the range of 5,000 to 500,000, preferably 8,000 to 200,000, more preferably 10,000 to 100,000, the mechanical strength and molding processability of the molded body are highly balanced. Being preferred.

<Additives>
(Plasticizer)
In the optical film according to the present invention, a plasticizer can be used in combination in order to improve the fluidity and flexibility of the composition. Examples of the plasticizer include phthalate ester, fatty acid ester, trimellitic ester, phosphate ester, polyester, and epoxy.

Of these, polyester-based and phthalate-based plasticizers are preferably used. Polyester plasticizers are superior in non-migration and extraction resistance compared to phthalate ester plasticizers such as dioctyl phthalate, but are slightly inferior in plasticizing effect and compatibility.

Therefore, it can be applied to a wide range of uses by selecting or using these plasticizers according to the use.

The polyester plasticizer is a reaction product of a monovalent or tetravalent carboxylic acid and a monovalent or hexavalent alcohol, and is mainly obtained by reacting a divalent carboxylic acid with a glycol. . Representative divalent carboxylic acids include glutaric acid, itaconic acid, adipic acid, phthalic acid, azelaic acid, sebacic acid and the like.

In particular, when adipic acid, phthalic acid, or the like is used, those having excellent plasticizing properties can be obtained. Examples of the glycol include glycols such as ethylene, propylene, 1,3-butylene, 1,4-butylene, 1,6-hexamethylene, neopentylene, diethylene, triethylene, and dipropylene. These divalent carboxylic acids and glycols may be used alone or in combination.

The ester plasticizer may be any of ester, oligoester, and polyester types, and the molecular weight is preferably in the range of 100 to 10,000, and preferably in the range of 600 to 3000, which has a large plasticizing effect.

Also, the viscosity of the plasticizer has a correlation with the molecular structure and molecular weight, but in the case of an adipic acid plasticizer, the range of 200 to 5000 MPa · s (25 ° C.) is preferable because of compatibility and plasticization efficiency. Furthermore, some polyester plasticizers may be used in combination.

The plasticizer is preferably added in an amount of 0.5 to 30 parts by mass with respect to 100 parts by mass of the optical film according to the present invention. If the added amount of the plasticizer exceeds 30 parts by mass, the surface becomes sticky, which is not preferable for practical use.

(UV absorber)
The optical film according to the present invention preferably contains an ultraviolet absorber, and examples of the ultraviolet absorber used include benzotriazole, 2-hydroxybenzophenone, and salicylic acid phenyl ester. For example, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (3 Triazoles such as 5-di-t-butyl-2-hydroxyphenyl) benzotriazole, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone And benzophenones.

Here, among ultraviolet absorbers, ultraviolet absorbers having a molecular weight of 400 or more are less likely to volatilize at a high boiling point and are difficult to disperse even during high-temperature molding, so that the weather resistance is effectively improved with a relatively small amount of addition. be able to.

Examples of the ultraviolet absorber having a molecular weight of 400 or more include 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2-benzotriazole, 2,2-methylenebis [4- (1, 1,3,3-tetrabutyl) -6- (2H-benzotriazol-2-yl) phenol], bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis ( Hindered amines such as 1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and 2- (3,5-di-tert-butyl-4-hydroxybenzyl) -2-n-butylmalonic acid Bis (1,2,2,6,6-pentamethyl-4-piperidyl), 1- [2- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] Such as til] -4- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6-tetramethylpiperidine The hybrid type | system | group which has both structures is mentioned, These can be used individually or in combination of 2 or more types. Among these, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2-benzotriazole and 2,2-methylenebis [4- (1,1,3,3- Tetrabutyl) -6- (2H-benzotriazol-2-yl) phenol] is particularly preferred.

(Other additives)
Furthermore, various antioxidants can also be added to the optical film according to the present invention in order to improve the thermal decomposability and thermal colorability during molding. It is also possible to add an antistatic agent to give the optical film antistatic performance.

For the optical film according to the present invention, a flame retardant acrylic resin composition containing a phosphorus flame retardant may be used.

Phosphorus flame retardants used here include red phosphorus, triaryl phosphate ester, diaryl phosphate ester, monoaryl phosphate ester, aryl phosphonate compound, aryl phosphine oxide compound, condensed aryl phosphate ester, halogenated alkyl phosphorus. Examples thereof include one or a mixture of two or more selected from acid esters, halogen-containing condensed phosphate esters, halogen-containing condensed phosphonate esters, halogen-containing phosphite esters, and the like.

Specific examples include triphenyl phosphate, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, phenylphosphonic acid, tris (β-chloroethyl) phosphate, tris (dichloropropyl) Examples thereof include phosphate and tris (tribromoneopentyl) phosphate.

<Method for forming polarizer protective film>
Although the example of the film forming method of a polarizer protective film is demonstrated, this invention is not limited to this. As a method for forming a polarizer protective film according to the present invention, production methods such as an inflation method, a T-die method, a calendar method, a cutting method, a casting method, an emulsion method, and a hot press method can be used. From the viewpoints of suppressing foreign matter defects and optical defects such as die lines, solution casting by casting is preferred.
In addition, the film forming method of this polarizer protective film can also be suitably applied as a film forming method of a retardation film.

(Organic solvent)
The organic solvent useful for forming the dope when the polarizer protective film according to the present invention is produced by the solution casting method is used without limitation as long as it dissolves the cellulose ester resin and other additives simultaneously. Can do.

For example, as a chlorinated organic solvent, methylene chloride, as a non-chlorinated organic solvent, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 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, nitroethane, etc. Methylene chloride, methyl acetate, ethyl acetate and acetone can be preferably used.

In addition to the organic solvent, the dope preferably contains 1 to 40% by mass of a linear or branched aliphatic alcohol having 1 to 4 carbon atoms. When the proportion of alcohol in the dope increases, the web gels, facilitating peeling from the metal support, and when the proportion of alcohol is small, the dissolution of the cellulose ester resin in a non-chlorine organic solvent system is promoted. There is also a role.

In particular, a dope composition in which at least 15 to 45 mass% in total of a cellulose ester resin is dissolved in a solvent containing methylene chloride and a linear or branched aliphatic alcohol having 1 to 4 carbon atoms is preferable. .

Examples of the linear or branched aliphatic alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and tert-butanol. Ethanol is preferred because of the stability of these dopes, the relatively low boiling point, and good drying properties.

Hereinafter, the preferable film forming method of the polarizer protective film according to the present invention will be described.
(1) Dissolving step A step of dissolving a cellulose ester resin in an organic solvent, mainly a good solvent for the cellulose ester resin, and optionally dissolving other additives while stirring to form a dope, or a cellulose ester resin This is a step of mixing the solution with other additive solutions as necessary to form a dope that is a main solution.

For dissolving the cellulose ester resin, a method carried out at normal pressure, a method carried out below the boiling point of the main solvent, a method carried out under pressure above the boiling point of the main solvent, JP-A-9-95544, JP-A-9-95557 Alternatively, various dissolution methods such as a method of cooling and dissolving as described in JP-A-9-95538 and a method of performing at high pressure as described in JP-A-11-21379 can be used. A method in which pressure is applied at a boiling point or higher is preferred.

The total amount of cellulose ester resin in the dope is preferably in the range of 15 to 45% by mass. An additive is added to the dope during or after dissolution to dissolve and disperse, then filtered through a filter medium, defoamed, and sent to the next step with a liquid feed pump.

For the filtration, it is preferable to use a filter medium having a collected particle diameter of 0.5 to 5 μm and a drainage time of 10 to 25 sec / 100 mL.

In this method, the aggregate remaining at the time of particle dispersion and the aggregate generated when the main dope is added are aggregated by using a filter medium having a collected particle diameter of 0.5 to 5 μm and a drainage time of 10 to 25 sec / 100 mL. Can only be removed. In the main dope, the concentration of particles is sufficiently thinner than that of the additive solution, so that aggregates do not stick together at the time of filtration and the filtration pressure does not increase suddenly.

FIG. 2 is a diagram schematically showing an example of a dope preparation step, a casting step, and a drying step of a solution casting film forming method preferable for the present invention.

Next, the main dope solution is sent to the main filter 3 by the pump 2, filtered, and sent to the stock tank 4. Thereafter, an ultraviolet absorbent additive solution is added in-line as necessary.

In many cases, the main dope may contain about 10 to 50% by weight of recycled material. The return material may contain acrylic particles. In that case, it is preferable to control the addition amount of the acrylic particle addition liquid in accordance with the addition amount of the return material.

The additive solution containing acrylic particles preferably contains 0.5 to 10% by mass of acrylic particles, more preferably 1 to 10% by mass, and more preferably 1 to 5% by mass. Most preferably.

Within the above range, the additive solution is preferable because it has a low viscosity and is easy to handle and can be easily added to the main dope.

The return material is a product obtained by finely pulverizing the polarizer protective film, which is generated when the polarizer protective film is formed. A protective film original is used.

In addition, an acrylic resin, a cellulose ester resin, and optionally an acrylic particle kneaded into pellets can be preferably used.
(2) Casting process In this casting process, the dope is fed to the pressurizing die 30 through the filter 6 by the liquid feed pump 5 (for example, pressurization type metering gear pump), and the endless metal belt is transferred infinitely. 31 is a step of casting a dope from a pressure die slit to a casting position on a metal support such as a stainless steel belt or a rotating metal drum.

A pressure die that can adjust the slit shape of the die base portion and can easily make the film thickness uniform is preferable. Examples of the pressure die include a coat hanger die and a T die, and any of them is preferably used. The surface of the metal support is a mirror surface. In order to increase the film forming speed, two or more pressure dies may be provided on the metal support, and the dope amount may be divided and stacked. Or it is also preferable to obtain the film of a laminated structure by the co-casting method which casts several dope simultaneously.
(3) Solvent evaporation step In this step, the web (the dope is cast on the casting support and the formed dope film is called a web) is heated on the casting support to evaporate the solvent.

To evaporate the solvent, there are a method of blowing air from the web side and / or a method of transferring heat from the back side of the support by a liquid, a method of transferring heat from the front and back by radiant heat, and the like. If it is, drying efficiency is good and preferable. A method of combining them is also preferably used. The web on the support after casting is preferably dried on the support in an atmosphere of 40 to 100 ° C. In order to maintain the atmosphere at 40 to 100 ° C., it is preferable to apply hot air at this temperature to the upper surface of the web or to heat by means such as infrared rays.

From the viewpoint of surface quality, moisture permeability, and peelability, the web is preferably peeled from the support within 30 to 120 seconds.
(4) Peeling step In this step, the web in which the solvent has evaporated on the metal support is peeled off at the peeling position 33. The peeled web is sent to the next process.

The temperature at the peeling position 33 on the metal support is preferably 10 to 40 ° C., more preferably 11 to 30 ° C. The amount of residual solvent at the time of peeling of the web on the metal support at the time of peeling is preferably 50 to 120% by mass depending on the strength of drying conditions, the length of the metal support, and the like. When peeling at a higher residual solvent amount, if the web is too soft, the flatness at the time of peeling is impaired, and slippage and vertical stripes are likely to occur due to the peeling tension. The amount of solvent is determined.

The amount of residual solvent in the web is defined by the following formula.

Residual solvent amount (%) = (mass before web heat treatment−mass after web heat treatment) / (mass after web heat treatment) × 100
Note that the heat treatment for measuring the residual solvent amount represents performing heat treatment at 115 ° C. for 1 hour.

The peeling tension at the time of peeling the metal support and the film is usually 196 to 245 N / m. However, when wrinkles easily occur at the time of peeling, it is preferable to peel with a tension of 190 N / m or less. It is preferable to peel at a minimum tension of ˜166.6 N / m, and then peel at a minimum tension of ˜137.2 N / m, and particularly preferable to peel at a minimum tension of ˜100 N / m.

In the present invention, the temperature at the peeling position 33 on the metal support is preferably −50 to 40 ° C., more preferably 10 to 40 ° C., and most preferably 15 to 30 ° C.
(5) Drying and stretching step After peeling, a drying device 35 that alternately conveys the web 32 through a plurality of rolls 36 arranged in the drying device, and / or a tenter stretching device that clips and conveys both ends of the web with clips. 34 is used to dry the web 32.

As the drying means, hot air is generally blown on both sides of the web 32, but there is also a means of heating by applying microwaves instead of the wind. Too rapid drying tends to impair the flatness of the finished film. Drying at a high temperature is preferably performed from about 8% by mass or less of the residual solvent. Throughout, drying is generally carried out at 40-250 ° C. In particular, drying at 40 to 160 ° C. is preferable.

When using the tenter stretching apparatus 34, it is preferable to use an apparatus that can independently control the film gripping length (distance from the start of gripping to the end of gripping) left and right by the left and right gripping means of the tenter. In the tenter process, it is also preferable to intentionally create sections having different temperatures in order to improve planarity.

It is also preferable to provide a neutral zone between different temperature zones so that each zone does not cause interference.

The stretching operation may be performed in multiple stages, and it is also preferable to perform biaxial stretching in the casting direction and the width direction. When biaxial stretching is performed, simultaneous biaxial stretching may be performed or may be performed stepwise.

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

-Stretch in the casting direction-Stretch in the width direction-Stretch in the casting direction-Stretch in the casting direction-Stretch in the width direction-Stretch in the width direction-Stretch in the casting direction-Stretch in the casting direction Simultaneous biaxial stretching includes stretching in one direction and contracting the other while relaxing the tension. The preferred draw ratio of simultaneous biaxial stretching can be in the range of 1.01 to 1.5 times in both the width direction and the longitudinal direction.

When the tenter is used, the amount of residual solvent in the web is preferably 20 to 100% by mass at the start of the tenter, and drying is preferably performed while applying the tenter until the amount of residual solvent in the web is 10% by mass or less. More preferably, it is 5% by mass or less.

When the tenter is used, the drying temperature is preferably 30 to 160 ° C, more preferably 50 to 150 ° C, and most preferably 70 to 140 ° C.

In the tenter process, it is preferable that the temperature distribution in the width direction of the atmosphere is small from the viewpoint of improving the uniformity of the film. The temperature distribution in the width direction in the tenter process is preferably within ± 5 ° C, and within ± 2 ° C. Is more preferable, and within ± 1 ° C. is most preferable.
(6) Winding step This is a step of winding the web by the winder 37 as a polarizer protective film after the residual solvent amount in the web is 2% by mass or less, and the residual solvent amount is 0.4% by mass or less. Thus, a film having good dimensional stability can be obtained. It is particularly preferable to wind up at 0.00 to 0.10% by mass.

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

The polarizer protective film according to the present invention is preferably a long film. Specifically, the polarizer protective film has a thickness of about 100 to 5000 m and is usually provided in a roll shape. The width of the film is preferably 1.3 to 4 m, and more preferably 1.4 to 3 m.

The thickness of the polarizer protective film according to the present invention is not particularly limited, but is preferably 15 to 150 μm, more preferably 20 to 80 μm, and particularly preferably 25 to 60 μm.

<Preparation method of polarizing plate>
The polarizing plate according to the present invention can be produced by a general method. For example, a completely saponified polyvinyl alcohol aqueous solution (water) is formed on at least one surface of a polarizer prepared by subjecting the polarizer side of the polarizer protective film according to the present invention to alkali saponification treatment and immersion drawing in an iodine solution. Paste using glue. Similarly, a retardation film subjected to alkali saponification treatment is bonded to the other surface of the polarizer using water paste. The optical film made of acrylic resin and cycloolefin resin is preferably subjected to corona discharge treatment before saponification treatment.
The corona discharge treatment is a treatment performed by applying a high voltage of 1 kV or higher between the electrodes under atmospheric pressure and discharging. By the corona treatment, oxygen-containing polar groups (hydroxy group, carbonyl group, carboxylic acid group, etc.) are generated on the resin surface of the retardation film, and the surface is hydrophilized.

Corona discharge treatment can be performed using a device commercially available from Kasuga Electric Co., Ltd., Toyo Electric Co., Ltd., or the like. The intensity of the corona discharge treatment depends on the distance between the electrodes, the output per unit area, and the generator frequency. As one electrode (A electrode) of the corona discharge treatment apparatus, a commercially available one can be used, but the material can be selected from aluminum, stainless steel and the like. The other is an electrode (B electrode) for holding a plastic film, and is a roll electrode installed at a certain distance from the A electrode so that the corona discharge treatment is carried out stably and uniformly. . A commercially available one can also be used, and the material is preferably a roll made of ceramic, silicon, EPT rubber, hyperon rubber or the like on a roll made of aluminum, stainless steel, or a metal thereof. It is done.

<Liquid crystal display device>
By incorporating a polarizing plate with the polarizer protective film according to the present invention into a liquid crystal display device, it is possible to produce various liquid crystal display devices with excellent visibility, but particularly large liquid crystal display devices and digital signage. It is preferably used for a liquid crystal display device for outdoor use. The polarizing plate according to the present invention is bonded to a liquid crystal cell via the adhesive layer or the like.

The polarizing plate according to the present invention is a reflective type, transmissive type, transflective LCD or TN type, STN type, OCB type, HAN type, VA type (PVA type, MVA type), IPS type (including FFS type), etc. It is preferably used in LCDs of various driving methods. In particular, in a large-screen liquid crystal display device having a screen of 30 or more types, particularly 30 to 54 types, display unevenness does not occur and the effect is maintained for a long time.

Note that embodiments to which the present invention can be applied are not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit of the present invention.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "mass part" or "mass%" is represented.

<Method for Manufacturing Polarizing Plate 101>
<Preparation of polarizer protective film>
(Preparation of dope solution)
The total degree of substitution is 2.9, of which the degree of substitution with the benzoyl group which is an aromatic acyl group is 1.2, the degree of substitution with the acetyl group which is an aliphatic acyl group is 1.7, and the weight average molecular weight (MW) 100 parts by mass of cellulose ester resin of 160000 was dissolved in a mixed solvent of 352 parts by mass of methylene chloride and 48 parts by mass of ethanol.
The degree of substitution in acetylcellulose was determined by the method prescribed in ASTM-D817-96.

The dope solution prepared with the above composition was uniformly cast on a stainless steel band support at a temperature of 22 ° C. and a width of 2 m using a belt casting apparatus. With the stainless steel band support, the solvent was evaporated until the residual solvent amount reached 100% by mass, and the film was peeled from the stainless steel band support with a peeling tension of 162 N / m.

The solvent was evaporated from the peeled web at 35 ° C., slit to 1.6 m width, and then dried at a drying temperature of 135 ° C. while being stretched 1.1 times in the width direction by a tenter. At this time, the residual solvent amount when starting stretching with a tenter was 10% by mass. After stretching with a tenter, relaxation was performed at 130 ° C. for 5 minutes, and then drying was completed while transporting a drying zone of 110 ° C. and 120 ° C. with many rolls, slitting to a width of 1.5 m, and a width of 10 mm at both ends of the film. A knurling process having a thickness of 5 μm was performed, and the film was wound around a core having an inner diameter of 6 inches with an initial tension of 220 N / m and a final tension of 110 N / m to obtain a polarizer protective film.

The draw ratio in the MD direction calculated from the rotational speed of the stainless steel band support and the operating speed of the tenter was 1.1 times. This polarizer protective film had a residual solvent amount of 0.1% by mass, a thickness of 40 μm, and a winding number of 4000 m.

<Preparation of Polarizing Plate 101>
A 120 μm-thick long roll polyvinyl alcohol film was immersed in 100 parts by mass of an aqueous solution containing 1 part by mass of iodine and 4 parts by mass of boric acid, and stretched in the transport direction 5 times at 50 ° C. to prepare a polarizer.

Next, on one surface of the polarizer, the polarizer protective film prepared above was used as an adhesive with a 5% by weight aqueous solution of polyvinyl alcohol (trade name “Poval PVA203”, manufactured by Kuraray Co., Ltd.). The film was bonded so that the transmission axis and the in-plane slow axis of the polarizer protective film were parallel, and dried at 60 ° C. for 5 minutes.
In addition, on the other surface of the polarizer, as a retardation film, one surface of a film made of norbornene polymer (ZEONOR, manufactured by Nippon Zeon Co., Ltd., film thickness 50 μm) is set so that the wetting index is 56 mN / m. Corona discharge treatment was performed, a 5% by weight aqueous solution of polyvinyl alcohol was bonded as an adhesive, and then dried at 60 ° C. for 5 minutes, followed by aging at 35 ° C. for 24 hours to produce polarizing plate 101.

<Production Method of Polarizing Plates 102 to 105>
Polarizers 102 to 105 were produced in the same manner except that the total degree of substitution, the degree of substitution with a benzoyl group, the degree of substitution with an acetyl group, and the degree of substitution with a propyl group were as shown in Table 1. .

<Method for Producing Polarizing Plate 201>
In the production of the polarizer protective film of the production method of the polarizing plate 101, polyethylene terephthalate (A-PET manufactured by Teijin Chemicals Ltd., described as PET in Table 2) was used as the film material instead of using acetylcellulose. .
In the production of the polarizer protective film in the production method of the polarizing plate 101, the draw ratio and the conveyance tension were controlled so that the thickness of the polarizer protective film was not 40 μm but 75 μm.
Other than that, the polarizing plate 201 was manufactured in the same manner as the manufacturing method of the polarizing plate 101.

<Method for Manufacturing Polarizing Plate 202>
In the production of the polarizer protective film of the production method of the polarizing plate 101, polymethyl methacrylate (Technoloy S001 manufactured by Sumitomo Chemical Co., Ltd., described as PMMA in Table 2) was used as a film material instead of using acetylcellulose. .
Moreover, in preparation of the polarizer protective film of the manufacturing method of the polarizing plate 101, the draw ratio and the conveyance tension were controlled so that the thickness of the polarizer protective film was not 40 μm but 80 μm.
Other than that, the polarizing plate 202 was manufactured in the same manner as the manufacturing method of the polarizing plate 101.

<Production Method of Polarizing Plates 203 to 208>
In the production of the polarizer protective film of the production method of the polarizing plate 103, the draw ratio and the transport tension were controlled so that the thickness of the polarizer protective film was as shown in Table 2.
Other than that, polarizing plates 203 to 208 were manufactured in the same manner as the manufacturing method of the polarizing plate 103.

<Production Method of Polarizing Plates 301 to 316>
In the production of the polarizer protective film of the production method of the polarizing plate 101, the total substitution degree of acetyl cellulose, the substitution degree with the acetyl group, the substitution degree with the propyl group, the kind of the substituted aromatic acyl group, and the substitution with the aromatic acyl group Polarizers 301 to 316 were produced in the same manner except that acetylcellulose as shown in Table 3 was used as the film material.

(Measurement of elastic modulus)
The elastic modulus (tensile elastic modulus) of each of the polarizer protective films of the polarizing plates 101 to 105, 201 to 208, and 301 to 316 was measured according to the method described in JIS K 7127.
Specifically, Tensilon tester “RTC-1225A” manufactured by Orientec Co., Ltd. and constant temperature and humidity chamber “TLF-R3T-F-HS-W” are used as a tensile tester and a constant temperature and humidity chamber. Is cut into a size of 70 x 10 mm and held for 1 hour in a constant temperature and humidity chamber maintained at the specified temperature and humidity (25 ° C, 55% RH and 25 ° C, 95% RH). Each was measured with a machine at a tensile speed of 100 mm / min. The measured values (E ₁ , E ₂ ) and E ₁ / E ₂ are as shown in Tables 1 to 3.

(Measurement of moisture permeability)
The moisture permeability is based on the cup method described in JIS Z 0208. The polarizer protective films 101 to 105, 201 to 208, and 301 to 316 are allowed to stand for 24 hours under conditions of a temperature of 40 ° C. and a humidity of 90% RH. Each was measured. The measured values are shown in Tables 1 to 3.

<Characteristic evaluation as a liquid crystal display device>
Both of the previously bonded polarizing plates of the 42-inch TV “LEDREGZA42RE1” (glass substrate thickness: 0.5 mm) manufactured by Toshiba, which is an IPS type liquid crystal display device, are peeled off, and the polarizing plates 101- 105, 201 to 208 and 301 to 316 were bonded so that the absorption axis was in the same direction as the previously bonded polarizing plate, and the polarizing plates 101 to 105, 201 to 208, and 301 to 316 were used. Each liquid crystal display device was produced.

(Egg Mura)
Thereafter, the liquid crystal display device is exposed to an environment of 50 ° C. and 80% RH for 72 hours, and then left in an environment of 23 ° C. and 55% RH for 2 hours, and then the power source (backlight light source) is turned on. The display unevenness (egg unevenness) after 24 hours was observed with black display and evaluated according to the following criteria. In the following evaluation, the more uniform the image display, the better.

◎: Image display is uniform ○: Image display is almost uniform △: There is a slight outline at the center and the periphery ×: There is a clear outline at the center and the periphery

(Productivity evaluation method)
After drying at 60 ° C. for 1 minute, the strength of adhesion between the polarizer protective films of the polarizing plates 101 to 105, 201 to 208, and 301 to 316 and polyvinyl alcohol was evaluated. The evaluation is described below. In addition, the following evaluation shall be so good that it does not peel off.

A: 10 samples out of 10 samples are not peeled off (productivity is very good)
○: 8 or more of 10 samples are not peeled off (productivity is good)
Δ: 5 or more of 10 samples peeled off (practical)
X: 8 or more samples out of 10 samples are peeled off (unusable)

As described above, the present invention is suitable for providing a liquid crystal display device in which egg unevenness does not occur while improving the productivity even when the thickness of the glass substrate is 0.6 mm or less.

1a Backlight light source 2a Luminous light source 3a Diffusion plate (lower diffusion sheet)
4a Light collecting sheet (prism sheet, lens sheet)
5a Upper diffusion sheet 6a Backlight unit 7a Liquid crystal layer 8a Glass substrate 9a Liquid crystal cell 10a Polarizer 12a Liquid crystal panel PL1 Viewing side polarizing plate PL2 Light source side polarizing plate 1 Dissolution kettle 3, 6 Filter 4 Stock tank 5 Liquid feed pump 8 Conduit 30 Pressure Die 31 Metal Belt 32 Web 33 Peeling Position 34 Tenter Stretching Device 35 Roll Drying Device 37 Winder 41 Particle Charger 42 Stock Kettle 43 Pump 44 Filter T1, T4 Polarizer Protective Film T2, T3 Phase Difference Film

Claims (4)

1. A liquid crystal display device comprising a backlight source, a polarizing plate, a liquid crystal cell having a liquid crystal layer between a pair of glass substrates, and a polarizing plate in this order,
   The thickness of at least one of the glass substrates is 0.6 mm or less,
   The polarizing plate has a polarizer, a retardation film disposed on one surface of the polarizer, and a polarizer protective film disposed on the other surface of the polarizer,
   The polarizer protective film is
   Modulus at 25 ℃ · 55% RH and (E ₁₎ and the elastic modulus at 25 ℃ · 95% RH (E 2) , but satisfy the relationship of the following formula (1),
   Equation _{(1): 0.95 ≦ E 1} / E 2 ≦ 1.30
   A liquid crystal display device having a moisture permeability measured in a range of 200 to 2000 g / m ² · 24 h measured at 40 ° C. and 90% RH.
2. The polarizer protective film is
   Modulus at 25 ℃ · 55% RH and (E ₁₎ and the elastic modulus at 25 ℃ · 95% RH (E 2) , and the equations (2) satisfy the relation of the following formula (2): 1.01 ≦ E ₁ / E ₂ ≦ 1.20
   The liquid crystal display device according to claim 1.
3. The polarizer protective film is
   3. The liquid crystal display device according to claim 1, wherein the moisture permeability measured at 40 ° C. and 90% RH is in the range of 300 to 1500 g / m ² · 24 h.
4. The polarizer protective film is a cellulose ester film having a total degree of substitution of 2.2 or more and a degree of substitution by an aromatic acyl group of 0.2 or more. Item 4. The liquid crystal display device according to any one of Items 3 to 3.

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