TWI559037B - A polarizing plate, a polarizing plate manufacturing method, and a liquid crystal display device - Google Patents

Description

Polarizing plate, manufacturing method of polarizing plate and liquid crystal display device

The present invention relates to a polarizing plate, a method of manufacturing the polarizing plate, and a liquid crystal display device.

In recent years, liquid crystal display devices have been required to be added as liquid crystal displays for portable devices such as smart phones or tablet terminals. The small-sized liquid crystal display device 1 includes, for example, an IPS mode liquid crystal cell 3 on which a touch panel module is mounted, and a pair of polarizing plates 5 and 7 that hold the liquid crystal cell (see FIG. 3). The polarizing plate 5 includes a polarizing mirror 5-1, a protective film 5-3A (F2) disposed on the surface of the liquid crystal cell side, and a protective film 5-3B (F1) disposed on the opposite side. Similarly, the polarizing plate 7 includes a polarizing mirror 7-1, a protective film 7-3A (F3) disposed on the surface of the liquid crystal cell side, and a protective film 7-3B (F4) disposed on the opposite side.

The polarizing plate includes, for example, a polarizer and a two-piece cellulose ester film as a protective film for holding the polarizer, wherein the cellulose ester film disposed on the liquid crystal cell side satisfies 0 nm ≦ Re (630) ≦ 20 nm, Rth (630)| A polarizing plate of a film of 25 nm or the like is known (for example, Patent Document 1). This document discloses that in order to control changes due to humidity or temperature Since the display is uneven, the dimensional change rate of the cellulose ester film disposed on the liquid crystal cell side is reduced as much as possible, specifically, 0.5% or less.

Such a polarizing plate is usually used to make a polarizer and a cellulose ester film. It is obtained by a polyvinyl alcohol-based adhesive (water paste) or the like (for example, Patent Document 1). Recently, the production process of the polarizing plate does not require the use of water, and it can be followed by a short time. Therefore, an active energy ray-curable adhesive may be used instead of the polyvinyl alcohol-based adhesive (water paste).

Prior technical literature Patent literature

Patent Document 1: Japanese Laid-Open Patent Publication No. 2008-217022

Summary of invention

However, as disclosed in Patent Document 1, a polarizing plate in which a protective film and a polarizing mirror are subsequently passed through an active energy ray-curable adhesive has a problem that display unevenness of the liquid crystal display device is likely to occur and visibility is lowered. This problem is particularly noticeable in small liquid crystal display devices.

The reason for the decrease in visibility is still unclear, but it may be for the following reasons. That is, when the inside of the liquid crystal display device 1 is high temperature and high humidity, the polarizing mirror 5-1 or 7-1, particularly the polarizing mirror 7-1, is liable to cause a large dimensional change (shrinkage); the glass substrate of the liquid crystal cell 3 It is not easy to produce dimensional changes. In addition, disposed between the polarizer 7-1 and the glass substrate of the liquid crystal cell 3. The protective film 7-3A (F3) is further strengthened by the active energy ray-curable adhesive and the polarizer 7-1, and the adhesive force of the polarizer 7-1 is easily transmitted. To the protective film 7-3A (F3). At this time, when the dimensional change rate of the protective film 7-3A (F3) is small, the contraction force of the polarizing mirror 7-1 applied to the protective film 7-3A (F3) becomes relatively large, and the protective film 7-3A (F3) Easy to produce strain. When such a strain is generated, optical strain (birefringence) may easily occur, and display unevenness of the display device is liable to occur.

The small liquid crystal display device is exposed to a high temperature environment or a high humidity environment due to the use conditions. Further, the small liquid crystal display device includes not only a rechargeable battery that serves as a heat source, but also a small device. Therefore, especially when it is used during charging or in a high-temperature or high-humidity environment, heat or moisture tends to accumulate in the device, and there is a tendency that optical strain is particularly likely to occur.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a polarizing plate in which a polarizing mirror and a protective film are bonded via an active energy ray-curable adhesive layer, and which can suppress a decrease in visibility of a liquid crystal display device. .

[1] A polarizing plate comprising a polarizing mirror, a protective film A disposed on one surface of the polarizing mirror, and a protective film B disposed on the other surface of the polarizing mirror, wherein at least the protective film A is cured by an active energy ray a cured layer of a subsequent agent, in addition to the polarizing lens, the protective film A contains a cellulose ester and a polyester compound obtained by polycondensing a diol with a dicarboxylic acid, and the content of the polyester compound is relative to the cellulose The ester is 5 to 30% by mass, and the dimensional change rate of the long-side direction α of the film after the protective film A is stored at 80 ° C and 90% RH (relative humidity, the same applies hereinafter) for 100 hours (%) When the dimensional change rate (%) of the short side direction β orthogonal to the longitudinal direction α is A (β), the protective film A satisfies the following formulas (1) and (2). , -1.5≦A( α )≦-0.3...(1)

-1.5 ≦A( β )≦-0.3...(2).

[2] The polarizing plate according to [1], wherein the polyester compound is a dicarboxylic acid selected from the group consisting of an aliphatic dicarboxylic acid and an alicyclic dicarboxylic acid, and an aliphatic diol or an alkyl ether A compound obtained by polycondensation of a diol selected from the group consisting of an alcohol and an alicyclic diol.

[3] The polarizing plate of [1] or [2], wherein the protective film A satisfies the following formulas (3) and (4), -1.5 ≦ A ( α ) < - 0.5 (3)

-1.5 ≦A( β )<-0.5...(4).

[4] The polarizing plate according to any one of [1], wherein the protective film B is passed through a cured layer of an active energy ray-curable adhesive, and the polarizing mirror is followed by the protective film B. The dimensional change rate (%) of the longitudinal direction α of the film after storage at 80 ° C and 90% RH for 100 hours is B (α), and the dimensional change ratio of the short side direction β orthogonal to the longitudinal direction α ( When %) is B(β), the protective films A and B satisfy the following formulas (5) and (6), | A( α )-B( α )|≦0.4 (5)

| A( β )-B( β )|≦0.4...(6).

[5] The polarizing plate according to any one of [1] to [4] wherein the polarizer has a thickness of 3 to 15 μm.

[6] The polarizing plate according to any one of [1] to [5] wherein the protective film A is defined by the following formula (I), and the retardation in the in-plane direction measured at a measuring wavelength of 590 nm is Ro (590), which is defined by the following formula (II), and when the retardation in the thickness direction measured at the measurement wavelength of 590 nm is Rth (590), satisfies |Ro(590)|≦10 nm, |Rth(590)|≦10 nm , formula (I) Ro = (nx-ny) × t (nm)

Formula (II) Rth={(nx+ny)/2-nz}×t(nm) (In the formulas (I) and (II), nx represents the slow axis direction in which the refractive index becomes the largest in the in-plane direction of the film. The refractive index of x; ny represents the refractive index in the direction y orthogonal to the slow axis direction x in the in-plane direction of the film; nz represents the refractive index in the thickness direction z of the film; t (nm) represents the thickness of the film).

[7] The polarizing plate according to any one of [1] to [6] wherein the protective film A further contains a lubricant.

[8] The polarizing plate according to any one of [1] to [7] wherein the protective film B further contains a high hardness agent.

[9] The polarizing plate according to any one of [1] to [8] wherein the protective film A has a thickness of 10 to 60 μm.

[10] The polarizing plate according to any one of [1] to [9] wherein the protective film A is disposed on the liquid crystal cell side.

[11] The method for producing a polarizing plate according to any one of [1] to [10], comprising the steps of: 1) preparing a protective film A; 2) obtaining a polarizing mirror, and passing the active energy ray The cured adhesive layer is laminated on the protective film A on one side of the polarizer and the laminate of the protective film B disposed on the other side of the polarizer via the active energy ray-curable adhesive layer And 3) a step of irradiating the active energy ray to the laminate to cure the active energy ray-curable adhesive layer to obtain a polarizing plate; and 1) preparing the protective film A comprises the following 1A)~ Step 1C): 1A) A polyester compound obtained by polymerizing a cellulose ester and a diol and a dicarboxylic acid, and the content of the polyester compound is 5 to 30% by mass based on the cellulose ester. a step of forming a film; 1B) a step of extending the film in a width direction at a temperature of 110 to 135 ° C at a stretching ratio of 1.03 to 1.06 times; 1 C) Carrying under tension of ~80N/m, while drying at a temperature of 100~120 °C Dry 5~10 minutes.

[12] A liquid crystal display device comprising a first bias in sequence a light plate, a liquid crystal cell, a second polarizing plate, and a backlight, wherein the second polarizing plate is a polarizing plate according to any one of [1] to [10], and the protective film A of the second polarizing plate is disposed in the liquid crystal cell. The polarizing plate according to any one of [1] to [10], the protective film A of the first polarizing plate, and the second polarizing plate are the polarizing plates of the first polarizing plate and the second polarizing plate. The protective film A is disposed on the liquid crystal cell, respectively.

[13] The liquid crystal display device of [12], wherein the liquid crystal cell is a liquid crystal cell of an IPS mode or an FFS mode.

[14] The liquid crystal display device of [12] or [13], which is a small liquid crystal display device including a display portion having a length of 6 inches or less in a diagonal direction and a rechargeable battery.

According to the present invention, it is possible to provide a polarizing plate in which a polarizing mirror and a protective film are bonded via an active energy ray-curable adhesive layer, and it is possible to suppress a decrease in visibility of a liquid crystal display device, in particular, a decrease in visibility of a small liquid crystal display device. Polarizer.

1‧‧‧Liquid crystal display device

3, 50‧‧‧ liquid crystal cell

5, 70‧‧‧ first polarizer

5-1, 71‧‧‧ first polarizer

5-3A, 7-3A, 73A, 93A‧‧‧ Protective film A

5-3B, 7-3B, 73B, 93B‧‧‧ Protective film B

7, 90‧‧‧ second polarizer

7-1, 91‧‧‧ second polarizer

10‧‧‧Polar plate

11‧‧‧ polarizer

13A‧‧‧Protective film A

13B‧‧‧Protective film B

15, 75, 95‧‧‧ hardened layer of active energy ray-curing adhesive

30‧‧‧Small liquid crystal display device

110‧‧‧ Backlight

130‧‧‧protective glass

150‧‧‧Touch Panel

170‧‧‧ rechargeable battery

Fig. 1 is a view showing an example of a configuration of a polarizing plate of the present invention.

Fig. 2 is a schematic diagram showing an example of a small liquid crystal display device.

Fig. 3 is a simplified view showing an example of a basic configuration of a liquid crystal display device. Figure.

Polarizer

The polarizing plate of the present invention represents a polarizing mirror, a protective film A disposed on one surface thereof, and a protective film B disposed on the other surface.

Fig. 1 shows an example of the configuration of a polarizing plate of the present invention. Figure. As shown in FIG. 1, the polarizing plate 10 of the present invention includes a polarizing mirror 11, a protective film 13A (protective film A) disposed on one surface thereof, and a protective film 13B (protective film B) disposed on the other surface. The protective films 13A and 13B are each adhered to the polarizer 11 via the cured layer 15 and 15 of the active energy ray-curable adhesive. Among the protective films 13A and 13B, it is preferable that the protective film 13A is disposed on a liquid crystal cell of a display device to be described later.

1-1. Polarizer 11

The polarizer 11 is an element that transmits only polarized surface light in a certain direction, and a polarizing lens represented by the present invention is a polyvinyl alcohol-based polarizing film. The polyvinyl alcohol-based polarizing film is obtained by dyeing a polyvinyl alcohol-based polarizing film with iodine and dyeing with a dichroic dye.

The polyvinyl alcohol-based polarizing film may be a polyvinyl alcohol-based film After performing the one-axis stretching, the obtained film is dyed with iodine or a dichroic dye (preferably, the film after the durability treatment is further applied with a boron compound); after the polyvinyl alcohol-based polarizing film is dyed with iodine or a dichroic dye, After one axis extension The film (preferably, the film after the durability treatment with the boron compound).

The thickness of the polarizer 11 is not only made possible by making the polarizing plate It is thinner and can reduce the shrinkage force due to heat or humidity, and is preferably 2 to 30 μm, more preferably 3 to 15 μm.

As described above, the polarizer and the protective film pass through the active energy ray When the cured layer of the hardening type adhesive is followed, the dimensional change rate of the protective film disposed between the polarizer and the liquid crystal cell due to heat or humidity is small, and the display device is liable to cause display unevenness (reduced visibility). In view of the above, the present inventors have found that the dimensional change rate of the protective film 13A (protective film A) disposed between the polarizer and the liquid crystal cell is moderately increased, thereby suppressing display unevenness of the display device (reducing visibility) ).

Although the reason is not clear, it is presumed to be the following reason. By setting the dimensional change rate of the protective film 13A (protective film A) disposed between the polarizer and the glass substrate of the liquid crystal cell to be constant or more, the contraction force of the protective film 13A can be increased. As a result, the contraction force applied to the polarizing mirror 11 of the protective film 13A is relatively reduced, and the strain generated by the protective film 13A can be eliminated. Thereby, the optical strain (birefringence) of the protective film 13A can be reduced, and display unevenness can be reduced.

That is, the present invention is disposed between the polarizer and the liquid crystal cell In the protective film 13A, the dimensional change rate (%) of the longitudinal direction α of the film after storage for 100 hours at 80 ° C and 90% RH is A (α), and the short side direction β orthogonal to the longitudinal direction α is β. When the dimensional change ratio (%) is A (β), the protective film A preferably satisfies the following formulas (1) and (2).

-1.5≦A( α )≦-0.3...(1)

-1.5≦A( β )≦-0.3...(2)

In order to further reduce the strain generated by the protective film 13A, More preferably, the protective film 13A satisfies the following formulas (3) and (4).

-1.5≦A( α )<-0.5...(3)

-1.5≦A( β )<-0.5...(4)

The dimensional change rate of the film means that it is stored at 80 ° C and 90% RH. The ratio of the film after 100 hours to the amount of change in the size of the film before storage. The longitudinal direction α of the protective film 13A indicates a long-length direction (MD direction) or a direction orthogonal thereto (TD direction) in the roll body of the elongated polarizing plate; preferably, the length direction Orthogonal direction (TD direction). When the protective film 13A is a square single film (SHEET FILM), the longitudinal direction α of the protective film 13A may be one of two sides orthogonal to each other. The length direction (MD direction) of the polarizing plate is orthogonal or coincident with the absorption axis direction of the polarizer, and preferably coincides with the absorption axis direction of the polarizer.

The dimensional change rate of the protective film 13A is in the above range For example, it is preferred to lower the alignment of the cellulose ester molecules constituting the protective film 13A. The alignment of the cellulose ester molecules can be adjusted by the composition of the protective film A and the production conditions (extension conditions, drying conditions after stretching, and transport conditions). In order to increase the dimensional change rate of the protective film 13A, for example, 1) the content of the polyester compound is made constant or less; 2) the extension condition is set to be applied. The condition that the stretching tension of the film is lowered is low; and 3) the conveying tension is preferably lowered, and in addition to the above 1) to 3), it is more preferable that the drying condition after the stretching of 4) is moderated.

1-2. Protective film 13A

As described above, the protective film 13A is disposed in contact with the liquid crystal cell directly or via another layer, and may have a phase difference adjustment function. The protective film A contains a cellulose ester main component.

(cellulose ester)

The cellulose ester is a compound obtained by esterifying at least one of cellulose and at least one of an aliphatic carboxylic acid and an aromatic carboxylic acid having 2 to 22 carbon atoms.

Examples of cellulose esters include cellulose triacetate, cellulose Diacetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate, cellulose benzoate, cellulose acetate benzoic acid Ester and the like. Among them, the phase difference exhibitability is preferably low, and cellulose triacetate is preferred.

The total substitution degree of the thiol group of cellulose ester is 2.0~3.0 left Right, preferably 2.5 to 3.0, more preferably 2.7 to 3.0, and even more preferably 2.8 to 2.95. In order to reduce the phase difference exhibitability, it is preferred to increase the total substitution degree of the sulfhydryl group.

The number of carbon atoms of the thiol group contained in the cellulose ester is preferably 2~7, more preferably 2~4. In order to obtain good heat resistance and the like, the mercapto group contained in the cellulose ester preferably contains an ethyl group. The degree of substitution of the fluorenyl group having 3 or more carbon atoms is preferably 0.9 or less, and more preferably 0.

The degree of substitution of the thiol group of the cellulose ester can be measured by the method specified in ASTM-D817-96.

The weight average molecular weight of the cellulose ester is preferably from 5.0 × 10 ⁴ to 5.0 × 10 ⁵ , more preferably from 1.0 × 10 ⁵ to 3.0 × 10 ⁵ , still more preferably 1.5 × 10 in order to obtain a certain mechanical strength or more. ⁵ ~ 2.8 × 10 ⁵ . The molecular weight distribution (weight average molecular weight Mw / number average molecular weight Mn) of the cellulose ester is preferably from 1.0 to 4.5.

The weight average molecular weight and molecular weight distribution of the cellulose ester can be measured by gel permeation chromatography (GPC). The measurement conditions are as follows.

Solvent: dichloromethane

Pipe column: It is connected by three joints of Shodex K806, K805, and K803G (manufactured by Showa Denko Co., Ltd.).

Column temperature: 25 ° C

Sample concentration: 0.1% by mass

Detector: RI Model 504 (manufactured by GL Scientific)

Pump: L6000 (manufactured by Hitachi, Ltd.)

Flow rate: 1.0ml/min

Calibration curve: A calibration curve of 13 samples of standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) Mw = 1.0 × 10 ⁶ to 5.0 × 10 ² was used. It is preferred that 13 samples are selected at substantially equal intervals.

(polyester compound)

The protective film 13A preferably further contains a polyester compound in order to easily adjust the dimensional change rate, the phase difference, and the like.

Polyester compound is a polycondensation of a dicarboxylic acid and a diol The resulting compound. The dicarboxylic acid may be one or more selected from the group consisting of an aliphatic dicarboxylic acid, an alicyclic dicarboxylic acid, and an aromatic dicarboxylic acid. The diol may be one or more selected from the group consisting of an aliphatic diol, an alkyl ether diol, an alicyclic diol, and an aromatic diol. Among them, since the phase difference is not easily exhibited, and the dimensional change rate does not become too small, etc., it is preferred to select a dicarboxylic acid selected from the group consisting of an aliphatic dicarboxylic acid and an alicyclic dicarboxylic acid and an aliphatic second. A polyester compound (aliphatic polyester compound) obtained by polycondensation of a diol selected from the group consisting of an alcohol, an alkyl ether diol, and an alicyclic diol.

That is, the polyester compound is preferably represented by the general formula (1) or (2). By.

General formula (1): B ₁ -(GA-)mG-B ₁

G of the general formula (1) represents a group derived from an aliphatic diol or an alkyl ether diol. The carbon number of the aliphatic diol is preferably from 2 to 12. Examples of the aliphatic diol include ethylene glycol, diethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, and 1,4-butane Alcohol, 1,5-pentanediol (Pentadiol), 1,6-hexanediol, 1,5-pentanediol (Pentylene glycol), etc., preferably ethylene glycol, 1,2-propanediol, 1,3 - propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol.

The alkyl ether diol preferably has a carbon number of 4 to 12. Examples of alkyl ether glycols include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene Alcohol, etc.

The general formula (1) A represents an aliphatic dicarboxylic acid or an alicyclic ring. a base of a dicarboxylic acid. The carbon number of the aliphatic dicarboxylic acid is preferably from 4 to 12. Examples of the aliphatic dicarboxylic acid include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid, dodecane two Carboxylic acid, etc.

B _{1 of the} general formula (1) represents a group derived from an aliphatic monocarboxylic acid or an alicyclic monocarboxylic acid. The number of carbon atoms of the aliphatic monocarboxylic acid is preferably from 1 to 12. Examples of the aliphatic monocarboxylic acid include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, capric acid, capric acid, 2-ethyl-heptanoic acid, and undecylic acid. , lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid, nineteen acid, arachidic acid, behenic acid, tetracosanoic acid, hexadecane Saturated fatty acids such as acid, heptacosanoic acid, octadecanoic acid, tridecanoic acid, and tridecanoic acid, undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, peanut dipping Acetic acid such as an unsaturated acid such as an olefinic acid has good compatibility with a cellulose ester, and is preferably acetic acid.

In general, B ₁ , G and A of the formula (1) preferably do not contain an aromatic ring in order to make it difficult to exhibit a phase difference or the like. m represents the number of repetitions, preferably 1 or more and 170 or less.

An example of a polyester compound represented by the general formula (1), including Table 1 Shown.

General formula (2): B ₂ -(AG-)nA-B ₂

G and A of the general formula (2) are each defined similarly to G and A of the general formula (1). B _{2 of the} general formula (2) represents a group derived from an aliphatic monool or an alicyclic monool. The number of carbon atoms of the aliphatic monool is preferably from 1 to 12. Examples of the aliphatic monool include methanol, ethanol, propanol, isopropanol and the like; and examples of the alicyclic monool include cyclohexanol and the like.

In general, B ₂ , G and A of the formula (2) preferably do not contain an aromatic ring in order to make it difficult to exhibit a phase difference or the like. n represents the number of repetitions, preferably 1 or more and 170 or less.

Examples of the polyester compound represented by the general formula (2) include those shown in Table 2.

The weight average molecular weight Mw of the polyester compound, from the fiber The viewpoint of good compatibility of the vitamin ester is preferably 20,000 or less, more preferably 5,000 or less, and most preferably 3,000 or less. In addition, the weight average molecular weight Mw of the polyester compound is 400 or more, preferably 700 or more, and most preferably 1,000 or more from the viewpoint of suppressing volatilization of the polyester compound in the film formation.

The content of the polyester compound, from the plastic effect of the film, From the viewpoint of a preferable phase difference, it is preferably from 1 to 40% by mass, more preferably from 5 to 30% by mass, still more preferably from 5 to 20% by mass, most preferably from 10% to the cellulose ester. 18% by mass.

a polyester compound represented by the general formula (1) or (2), compared to the aromatic Since the aromatic polyester compound has a small effect of aligning the cellulose ester molecules, the dimensional change rate of the protective film 13A due to heat or humidity does not become too small. Further, the polyester compound represented by the general formula (1) or (2) can lower the phase difference of the protective film 13A, particularly Rth.

The protective film 13A may further contain a release aid, if necessary Various additives such as an ultraviolet absorber, a matting agent (fine particles) for imparting slip properties, a lubricant, a high hardness agent to be described later, and a punching and reinforcing material for improving toughness.

(UV absorber)

Examples of the ultraviolet absorber include a benzotriazole-based compound, a 2-hydroxybenzophenone-based compound, and a phenyl salicylate-based compound. Specific examples are 2-(5-methyl-2-hydroxyphenyl)benzotriazole, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H - triazoles such as benzotriazole, 2-(3,5-di-t-butyl-2-hydroxyphenyl)benzotriazole, 2-hydroxy-4-methoxybenzophenone, 2 a benzophenone such as hydroxy-4-octyloxybenzophenone or 2,2'-dihydroxy-4-methoxybenzophenone.

The ultraviolet absorber may be a commercially available product, and examples thereof include BASF Japan's Tinuvin 109, Tinuvin 171, Tinuvin 234, Tinuvin 326, Tinuvin 327, Tinuvin 328, Tinuvin 928, etc. Tinuvin series or 2,2-methylene bis[6-(2H-benzotriazole-2- 4-(1,1,3,3-tetramethylbutyl)phenol] (molecular weight 659; an example of a commercial product is LA31 manufactured by the company ADEKA).

When the protective film is disposed on the surface of the liquid crystal cell side of the polarizer (made When it is used for the protective film F2 or F3 mentioned later, the ultraviolet-ray inhibitor is not essential, and the content of the ultraviolet absorber is about 0-0.5 mass % with respect to a cellulose ester. When the protective film is disposed on the surface opposite to the liquid crystal cell of the polarizer (when used as a protective film F1 or F4 to be described later), the content of the ultraviolet light preventive agent may be about 1 ppm to 5.0% by mass based on the cellulose ester. Preferably, it is about 0.5 to 3.0%.

(slip agent)

It is preferable that the protective film 13A further contains a lubricant. The protective film 13A is manufactured at a low conveyance tension in order to set the dimensional change rate due to heat or humidity to a certain level or more. However, when the conveyance tension is lowered, the protective film and the transfer roller are in poor contact, and the surface of the protective film is easily damaged, and the haze tends to increase. Therefore, the protective film 13A can suppress the contact failure with the roller by further containing a lubricant, and can suppress the increase in haze caused by the film.

The slip agent can be polydimethyl siloxane or polydiethyl decane. Such as polyorganosiloxane or higher fatty acid, higher aliphatic alcohol, higher fatty acid decylamine, higher fatty acid metal salt, ester of higher fatty acid and higher aliphatic alcohol, and the like. Among these, a compound represented by the following general formula (3) is preferred.

[Chemical 1] R ₁ -LR ₂ (3)

The general formula (3) L represents a valence of at least an ester bond (-C(=O)O-), a guanamine bond (-C(=O)NH-) or a carbonyl group (-C(=O)-) base. These carbonyl groups impart a good affinity to the cellulose ester to the compound represented by the general formula (3). Specifically, L represents an ester bond, a guanamine bond, a carbonyl group, or an "ester bond, a guanamine bond or a carbonyl group and a group consisting of an alkyl group, a nitrogen atom, an oxygen atom, a sulfur atom, a zinc atom, a calcium atom, and a magnesium atom. One or more selected two-valent groups"; since a good affinity with a cellulose ester can be obtained, it is preferably an "ester bond, a guanamine bond or a carbonyl group and an alkyl group, a nitrogen atom, an oxygen atom, Group of sulfur, zinc, calcium and magnesium atoms A combination of one or more of the two valence groups.

An example of "a divalent group in which an ester bond, a guanamine bond, or a carbonyl group is combined with one or more selected from the group consisting of an alkyl group, a nitrogen atom, an oxygen atom, a sulfur atom, a zinc atom, a calcium atom, and a magnesium atom", -C(=O)-OR ₃ -OC(=O)-, -C(=O)-NH-R ₃ -NH-C(=O)-(R ₃ is an alkylene group having 1 to 5 carbon atoms ); -C(=O)-OMOC(=O)-(M is a zinc atom, a calcium atom or a magnesium atom); -C(=O)-R ₄ -OR ₄ -C(=O)-, -C (=O)-R ₄ -SR ₄ -C(=O)-, -C(=O)-R ₄ -NH-R ₄ -C(=O)-(R ₄ is a carbon number of 1~5 Alkyl); and -C(=O)-R ₅ -C(=O)-(R ₅ is an alkylene group having 1 to 5 carbon atoms).

R _{1 in the} general formula (3) represents an alkyl group having 8 or more and 26 or less carbon atoms or an alkenyl group having 8 or more and 26 or less carbon atoms. The number of carbon atoms of the alkyl group and the alkenyl group is more preferably 10 or more and 26 or less from the viewpoint of easily obtaining good slipperiness. The alkyl group and the alkenyl group may be linear or branched, and are preferably linear in terms of easy to obtain good slipperiness.

R _{2 in the} general formula (3) represents a hydrogen atom, an alkyl group having 8 or more and 26 or less carbon atoms, or an alkenyl group having 8 or more and 26 or less carbon atoms; and in order to obtain good slipperiness, it is preferably 8 or more carbon atoms. An alkyl group of 26 or less or an alkenyl group having 8 or more and 26 or less carbon atoms. The number of carbon atoms of the alkyl group and the alkenyl group is more preferably 10 or more and 26 or less from the viewpoint of easily obtaining good slipperiness. The alkyl group and the alkenyl group may be linear or branched, and are preferably linear in terms of easy to obtain good slipperiness.

When R ₂ is a hydrogen atom, -LR ₂ may be -C(=O)OH or -C(=O)NH ₂ or the like.

When necessary, R ₁ and R ₂ may further contain a substituent such as an OH group. Further, R ₁ and R ₂ may be the same or different.

Examples of the compound represented by the general formula (3) include the following.

The content of the lubricant is preferably relative to the protective film 13A. It is 0.05 to 5% by mass, more preferably 0.1 to 3% by mass. When the content of the lubricant is more than a certain amount, the slipperiness of the film at the time of film formation is improved, and the increase in haze due to the surface damage of the film can be suppressed. When the content of the lubricant is not more than a certain amount, there is no doubt that leakage may occur.

(matting agent)

The matting agent imparts slip properties to the protective film 13A. The matting agent may be a fine particle composed of an inorganic compound or an organic compound which does not impair the transparency of the obtained film and which has heat resistance in the film forming step.

An example of an inorganic compound constituting a matting agent, including dioxide Silica, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium citrate, water and calcium citrate, aluminum citrate, magnesium citrate and calcium phosphate. Among them, cerium oxide or zirconium oxide is preferred, and in order to reduce the increase in haze of the obtained film, cerium oxide is more preferable.

Specific examples of cerium oxide include AEROSIL 200V, AEROSIL R972 V, AEROSIL R972, R974, R812, 200, 300, R202, OX50, TT600, NAX50 (above is Japan AEROSIL), SEAHOSTAR KEP-10, SEAHOSTAR KEP-30, SEAHOSTAR KEP-50 (above (shared in Japan), Sylophobic 100 (manufactured by Fuji Silysia), Nipseal E220A (manufactured by Japan Silica Co., Ltd.), ADMAFINE SO (manufactured by Admatechs), and the like.

The particle shape of the matting agent is amorphous, needle-like, flat or A spherical shape, a viewpoint that the transparency of the obtained film is good, etc., preferably a ball shape.

The matting agents may be used alone or in combination of two or more. also, By using particles having different particle diameters or shapes (for example, needle-like and spherical shapes), it is also possible to have high transparency and slipperiness.

The size of the particles of the matting agent is close to visible light. At the wavelength, light is scattered and the transparency is deteriorated, so that it is preferably smaller than the wavelength of visible light, and more preferably 1/2 or less of the wavelength of visible light. However, when the size of the particles is too small, the effect of improving the slip property may not be exhibited. Therefore, the size of the particles is preferably in the range of 80 to 180 nm. The size of the particles refers to the case where the particles are aggregates of primary particles, and refers to the size of the aggregates. When the particles are non-spherical, the size of the particles means the diameter of a circle corresponding to the projected area thereof.

The matting agent content is relative to the cellulose ester, which can be It is about 0.05 to 1.0% by mass, preferably 0.1 to 0.8% by mass.

Protective film 13A physical properties (size change)

As described above, in order to reduce the optical strain of the protective film 13A due to changes in heat or humidity, the high temperature of the protective film 13A is obtained. It is preferable to set the dimensional change rate after storage under high humidity to be more than a certain value. Specifically, the dimensional change ratio (%) of the longitudinal direction α of the film after the protective film 13A is stored at 80 ° C and 90% RH for 100 hours is A (α), which is short orthogonal to the longitudinal direction α. When the dimensional change ratio (%) of the side direction β is A (β), the protective film A preferably satisfies the following formulas (1) and (2).

-1.5≦A( α )≦-0.3...(1)

-1.5 ≦A( β )≦-0.3...(2).

The strain generated by the protective film 13A can be reduced, so The protective film 13A more preferably satisfies the following formulas (3) and (4).

-1.5≦A( α )<-0.5...(3)

-1.5≦A( β )<-0.5...(4)

The dimensional change rate of the protective film 13A can be as follows measuring.

1) The protective film 13A was cut into a size of 10 × 10 cm ^{2 to} prepare a sample film. In the TD direction (for example, direction α) of the sample film, a mark is made at a distance of 2 mm from the point of 100 mm. Similarly, the MD direction (direction β) orthogonal to the TD direction of the sample film is marked at two points of a distance of 100 mm. After the film was allowed to stand at 23 ° C and 55% RH for 24 hours, the distance D0 between two points was measured in each direction.

2) Next, the sample film was stored in an oven at 80 ° C, 90% RH for 100 hours. Then, the sample film was taken out from the oven, and after being conditioned for 24 hours at 23 ° C and 55% RH, the distance D1 between the two points marked in each direction was measured.

3) Next, the dimensional change rate (%) was calculated by using D0 measured in the above 1) and D1 measured in the above 2) in the respective directions by the following formula. A negative value indicates that the film is shrinking.

Dimensional change rate (%) = (D1-D0) / D0 × 100

As described above, the dimensional change rate of the protective film 13A is to be made. When the amount is more than or equal to, for example, 1) the content of the polyester compound (preferably the compound represented by the general formula (1) or (2)) is set to be a certain value or less; and 2) the extension condition is set such that the extension tension applied to the film is changed. Low conditions; and 3) it is preferable to reduce the transfer tension; more preferably, 4) to 3) to relax the drying conditions after the extension.

Specifically, in order to increase the MD side of the protective film 13A In the case of a dimensional change rate (preferably in the short-side direction β), it is preferred to contain a predetermined amount of the polyester compound, and the transport tension of the film is preferably a certain amount or less; to contain a predetermined amount of the polyester compound, and to transfer the film tension After the extension, it is preferable to carry out the roll conveyance so that the drying temperature and the drying time at the time of drying are all equal to or less than a certain value. In order to increase the dimensional change rate of the protective film 13A in the TD direction (preferably, the short-side direction β), it is preferred to contain a predetermined amount of the polyester compound, and the elongation temperature is preferably a certain amount or less; Further, both the extension temperature and the stretching ratio are more preferably equal to or less than a certain value.

(delay)

The retardation R _{0 of the} protective film 13A measured in the in-plane direction under the conditions of the measurement wavelength of 590 nm and 23 ° C of 55% RH is preferably -20 nm or more and 20 nm or less, more preferably -10 nm or more and 10 nm or less. The retardation Rth in the thickness direction measured under the conditions of the measurement wavelength of 590 nm and 23 ° C of 55% RH of the protective film 13A is preferably -20 nm or more and 20 nm or less, more preferably -10 nm or more and 10 nm or less. The protective film 13A having such a retardation value is suitable as, for example, a phase difference protective film (F2 or F3) of a liquid crystal display device of an IPS mode.

The delays R ₀ and Rth are each defined by the following formula.

Formula (1): R ₀ = (nx - ny) × d (nm)

Formula (II): Rth={(nx+ny)/2-nz}×d(nm) (In the formulae (I) and (II), nx represents the refractive index of the slow axis direction x in which the refractive index becomes the largest in the in-plane direction of the film; ny represents the in-plane direction of the film, which is orthogonal to the slow axis direction x described above. The refractive index of the direction y; nz represents the refractive index of the thickness direction z of the film; d (nm) represents the thickness of the film).

The delays R ₀ and Rth can be obtained, for example, by the following method.

1) The protective film 13A was conditioned at 23 ° C and 55% RH. The average refractive index of the protective film 13A after the humidity adjustment is measured using an Abbe refractometer or the like.

2) The protective film 13A after the humidity control is made parallel to the normal to the surface of the film, and R ₀ when light having a wavelength of 590 nm is incident is measured using KOBRA21ADH and prince measurement.

3) The slow axis in the plane of the protective film 13A is measured by KOBRA21ADH as the tilt axis (rotation axis), and the angle from the normal to the surface of the film is θ (incident angle (θ)), and the incident measurement wavelength is 590 nm. The retardation value R(θ) at the time of the light. The delay value R(θ) can be measured in the range of 0° to 50° θ, and 6 points per 10°. The in-plane slow axis of the protective film 13A means protection Among the film faces of the film 13A, the refractive index became the largest axis, which was confirmed by KOBRA21ADH.

4) From the measured R ₀ and R (θ) and the average refractive index and film thickness, nx, ny, and nz were calculated by KOBRA21ADH, and Rth at a measurement wavelength of 590 nm was calculated. The measurement of the delay can be carried out at 23 ° C, 55% RH.

(haze)

The haze of the protective film 13A is preferably 1.0% or less, more preferably 0.5% or less, still more preferably 0.3% or less. The haze of the protective film 13A is a full haze, and it is measured by a haze meter (turbidity meter) (type: NDH 2000, manufactured by Nippon Denshoku Co., Ltd.) in accordance with JIS K-7136.

In order to make the haze below a certain level, for example, adding a slip agent, It is better to reduce the external haze. By adding a lubricant, it is possible to suppress the contact failure between the film in the film formation and the conveyance roller, and it is possible to suppress an increase in the external haze due to the surface damage of the film.

(thickness)

The thickness of the protective film 13A is preferably 10 to 60 μm, more preferably 15 to 45 μm, still more preferably 15 to 30 μm, and particularly preferably 15 to 28 μm in order to reduce the thickness of the polarizing plate.

Manufacturing method of protective film 13A

The protective film 13A uses a solution flow in order to reduce streaky failure or the like. Cast manufacturing is preferred. That is, the protective film 13A is preferably produced by the following steps: 1) a step of obtaining a cellulose ester-containing dope, 2) a step of casting the dope onto a support, and drying to obtain a film. 3) a step of peeling off the obtained film material from the support, 4) a step of drying and stretching the film, and 5) a step of winding the obtained film.

1) Dissolution step

The organic solvent for preparing the dope liquid is not particularly limited as long as it can sufficiently dissolve the above components such as cellulose ester. An example of the chlorine-based organic solvent contains dichloromethane. Examples of the non-chlorine organic solvent include 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 Alcohol, nitroethane, and the like. Among them, dichloromethane is preferred.

In addition to the above organic solvent, the dope preferably contains 1 to 40% by mass of a linear or branched aliphatic alcohol having 1 to 4 carbon atoms. By including an alcohol in the dope, the film is gelated, and the peeling from the metal support becomes easy.

The linear or branched aliphatic alcohol having 1 to 4 carbon atoms may, for example, be methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol or tert-butanol. Among them, methanol and ethanol are preferred in view of stability of the cement, low boiling point, and good drying property.

Dissolving cellulose ester or the like, and the method is carried out under normal pressure, A method in which the boiling point of the main solvent is not more than the boiling point of the main solvent, a method of pressurizing, or the like, and a method in which the boiling point of the main solvent is equal to or higher than the boiling point of the main solvent.

2) Casting step

The slurry is supplied to the pressurizing mold through a liquid feeding pump (for example, a pressurized quantitative gear pump). The mortar is then cast by a press die to a casting position on an endless metal support that is infinitely transferred (for example, a stainless steel belt or a rotating metal drum, etc.).

The shape of the slit of the metal part of the mold can be adjusted, and it is easy to make A pressurizing die having a uniform film thickness is preferred. The press mold can be used with a coat hanger die or a T die. The surface of the metal support becomes a mirror surface.

3) Solvent evaporation and stripping steps

The dope is cast onto the metal slurry to heat the metal support, and the solvent in the slurry is evaporated to obtain a film.

When the solvent is to be evaporated, there is a side that is blown from the side of the slurry. The method, the method of transferring heat from the inner surface of the support by liquid, the method of transferring heat from the surface by radiant heat, etc., but the inner liquid heat transfer method is preferable because of high drying efficiency. It is preferred to dry the support on the metal support in an atmosphere in the range of 40 to 100 ° C. When it is desired to maintain an atmosphere in the range of 40 to 100 ° C, the hot air of this temperature is brought into contact with the surface of the metal slurry on the metal support, or it is preferably heated by means of infrared rays or the like.

a film obtained by evaporating a solvent on a metal support Peel off at the peeling position. The temperature at the peeling position on the metal support is preferably in the range of 10 to 40 ° C, more preferably in the range of 11 to 30 ° C.

Residual solvent for the film on the metal support during peeling The amount can be, for example, in the range of 50 to 120% by mass. The residual solvent amount of the film is defined by the following formula.

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

The heat treatment at the time of measuring the amount of residual solvent means heat treatment at 140 ° C for 1 hour.

Peeling tension when peeling metal support and film, usually It is in the range of 196 to 245 N/m, but when wrinkles are likely to occur during peeling, it is preferably peeled at a tension of 190 N/m or less, and more preferably at a tension of 80 N/m or less.

5) Extension step

The extension of the film is preferably performed in at least one of a width direction (TD direction), a conveyance direction (MD direction), or an oblique direction of the film, and more preferably in a width direction (TD direction). When extending in both the width direction (TD direction) and the transport direction (MD direction) of the film, the extension of the film in the width direction (TD direction) and the extension of the transport direction (MD direction) may be performed successively or simultaneously.

As mentioned above, the extension of the film in order to obtain dimensional changes When the protective film 13A has a predetermined value or more, it is preferably carried out under the conditions (elongation ratio, elongation temperature) at which the stretching tension applied to the film is lowered. Specifically, the dimensional change rate in the width direction (TD direction) is set to be equal to or lower than the extension temperature in the step of extending the width direction (TD direction); preferably, both the extension temperature and the extension ratio are set. It is a certain amount below and can be moderately improved.

The extension ratio is set to be lower, preferably in each direction. 1.01 to 1.06 times, more preferably 1.03 to 1.06 times. When both the width direction (TD direction) and the conveyance direction (MD direction) of the film are extended, the direction is preferably 1.01 to 1.06 times, more preferably 1.03 to 1.06 times.

The extension temperature is also set to be lower preferably. Extension temperature When the glass transition temperature of the cellulose ester is Tg, it may range from (Tg-40) to (Tg+20) °C. Specifically, when the main component of the film is cellulose triacetate, the stretching temperature is preferably from 100 to 135 ° C, more preferably from 110 to 135 ° C.

In order to sufficiently remove the solvent in the extended film, and adjust The dimensional change rate of the entire film, etc., is preferably such that the film is dried again.

Drying of the film, for example, by transferring the film to a drying device while carrying a plurality of rolls, it is preferred to carry out film drying.

Drying of the film in order to obtain a dimensional change rate of more than a certain When the protective film 13A is used, it is preferably carried out under mild conditions (temperature, time). Specifically, the dimensional change rate in the transport direction (MD direction) is set to at least a predetermined value by the transport tension of the film; All of the drying temperature and the drying time in the drying step after the transfer tension and the stretching are set to be equal to or less, and can be appropriately increased.

The drying temperature is preferably 90 to 125 ° C, more preferably 100 to 120 ° C, and more preferably 100 to 115 ° C. The drying time varies depending on the drying temperature, and is 5 to 15 minutes, preferably 5 to 10 minutes, more preferably 5 to 8 minutes.

In order to obtain a protective film having a dimensional change of more than a certain At 13 A, the transport tension of the film is preferably set to a low transport tension. Specifically, the transport tension of the film is preferably 50 to 100 N/m, more preferably 70 to 80 N/m.

Therefore, in order to increase the width direction (TD direction) and the transport direction In the case of the dimensional change rate of both of the (MD directions), it is preferable to set the stretching ratio and the stretching temperature when the film material containing the predetermined polyester compound is extended in the width direction (TD direction) to be constant or less. Further, it is preferable to set the drying tension of the film, the drying temperature and the drying time when the roll is dried while being stretched, to be equal to or less than a certain value. Specifically, the extension temperature is 110 to 135 ° C; the stretching ratio is 1.03 to 1.06 times; the conveying tension of the film is 70 to 80 N/m; the drying temperature is 100 to 120 ° C; and the drying time is 5 to 10 minutes. .

In the present invention, by further slipping in the protective film The agent can improve the slipperiness of the film during film formation. Thereby, even if the conveyance tension is lowered, the contact failure between the protective film and the conveyance roller can be suppressed, and the surface damage of the film can be suppressed. As a result, an increase in the haze of the obtained protective film 13A can be suppressed.

5) Winding step

The resulting protective film can be provided in the form of a strip. The long protective film is usually wound into a roll shape in the long-hand direction (MD direction) to form a wound body. The length of the long strip of protective film can range from 100 to 10,000 m. The strip-shaped protective film has a width of 1 to 4 m, preferably 1.4 to 3 m.

1-3. Protective film 13B

The protective film 13B is not particularly limited, and it is preferable to contain a cellulose ester as a main component in view of high heat resistance. The cellulose ester is defined similarly to the cellulose ester in the protective film 13A, and is preferably cellulose triacetate.

The protective film 13B can be further contained and protected as necessary The film 13A is the same polyester compound or various additives. Examples of the various additives contained in the protective film 13B include not only the same additives as the protective film 13A but also high hardness agents and the like.

(high hardness agent)

The high hardness agent is preferably a polymer containing a repeating unit derived from a monomer represented by the following general formula (4) or a compound represented by the following general formulas (5) to (8). These high hardness agents increase the density of the protective film 13B and reduce the diffusion path of boric acid in the polarizer. Thereby, deterioration of the polarizer can be suppressed.

R ^{1 of the} general formula (4) represents a hydrogen atom or an aliphatic group having 1 to 4 carbon atoms. Examples of the aliphatic group represented by R ¹ include a methyl group, an ethyl group and the like. R ² represents an aliphatic group or an aromatic group. Examples of the aliphatic group represented by R ² include an alkyl group, an alkenyl group, an alkynyl group, and a cycloalkyl group, preferably an alkyl group having 1 to 6 carbon atoms, more preferably a methyl group or a t-butyl group. Examples of the aromatic group include a phenyl group, a naphthyl group, and a biphenyl group, and a phenyl group is preferred. (A) indicates an aromatic ring of 5 or 6 members. The aromatic ring system contains an aromatic ring containing no hetero atoms and a saturated. unsaturated hetero ring containing a hetero atom. n represents an integer of 0 to 4, preferably 0 to 2, more preferably 0 to 1.

Containing repeating units derived from the monomer represented by the general formula (4) The polymer is preferably a copolymer represented by the following general formula (4-1).

R ²¹ , R ²² , R ²³ and R ^{24 of the} general formula (4-1) each independently represent a substituent. x, y, and z represent the molar ratio of the total repeating unit contained in the polymer, x represents 1 to 40%, y represents 5 to 95%, and z represents 1 to 70%. M1 and m2 each independently represent an integer of 0 to 4. M3 represents an integer from 0 to 2. M4 represents an integer from 0 to 5. R ¹⁰¹ , R ¹⁰² and R ¹⁰³ independently represent a hydrogen atom or an aliphatic group having 1 to 4 carbon atoms.

Containing repeating units derived from the monomer represented by the general formula (4) Specific examples of the polymer include the following.

The weight average molecular weight of the above polymer is preferably 200~10000, more preferably 300~8000, and even better 400~4000. When the weight average molecular weight is at least a certain value, the density of the protective film 13B can be favorably improved. Thereby, the diffusion of boric acid by the polarizer is suppressed, and deterioration of the polarizer can be suppressed. When the weight average molecular weight is at most a certain value, the compatibility with the cellulose ester is not easily impaired.

R ^{26 of the} general formula (5) represents an aryl group; preferably an aryl group having 6 to 12 carbon atoms, more preferably a phenyl group. R ²⁷ and R ²⁸ each independently represent a hydrogen atom, an alkyl group or an aryl group; preferably a hydrogen atom, an alkyl group having 1 to 12 carbon atoms (including a cycloalkyl group) or an aryl group having 6 to 12 carbon atoms; more preferably It is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms (including a cycloalkyl group) or a phenyl group. R ²⁶ and R ²⁷ each may have a substituent. Examples of the substituent which R ²⁶ may have include a halogen atom or an alkyl group having 1 to 6 carbon atoms. An example in which R ²⁷ may have a substituent includes an aryl group having 6 to 12 carbon atoms.

Specific examples of the compound represented by the general formula (5) include the following By.

The weight average molecular weight of the compound represented by the general formula (5), It is preferably 200 to 1000, more preferably 250 to 800.

R ^{1 of the} general formula (6) represents a hydrogen atom or a substituent. R ² represents a substituent represented by the following general formula (6-1). N1 represents an integer of 0 to 4, and when n1 is 2 or more, the plural R ^{1 's} may be the same or different from each other. N2 represents an integer of 1 to 5, and when n2 is 2 or more, the plural R ² may be the same or different from each other.

A of the general formula (6-1) represents a substituted or unsubstituted aromatic ring. The aromatic ring is preferably a benzene ring. R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a substituent represented by the general formula (6-2). R ⁵ represents a single bond or an alkylene group having 1 to 5 carbon atoms. X represents a substituted or unsubstituted aromatic ring. The aromatic ring is preferably a benzene ring. N3 represents an integer of 0 to 10, and when n3 is 2 or more, the plural R ⁵ and X may be the same or different from each other.

The X of the general formula (6-2) represents a substituted or unsubstituted aromatic ring. The aromatic ring is preferably a benzene ring. R ⁶ to R ⁹ each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. N5 represents an integer of 1 to 11, and when n5 is 2 or more, the plural R ⁶ to R ⁹ and X may be the same or different from each other.

Specific examples of the compound represented by the general formula (6) include the following By.

The weight average molecular weight of the compound represented by the general formula (6), It is preferably 200 to 1200, more preferably 250 to 1000.

R _{1 of the} general formula (7) represents a formazan group or a substituted or unsubstituted alkylcarbonyl group having 2 to 15 carbon atoms. R ₂ , R ₃ and R ₄ each independently represent an alkyl group having 1 to 4 carbon atoms. m and n each independently represent an integer of 0 or more, but are not 0 at the same time. When R ₁ , R ₂ , R ₃ and R ₄ are plural, they may be the same or different.

The compound represented by the general formula (7) is also known as a thiol-modified phenolic aldehyde. A varnish (novolac) type phenol resin. Thiol-based denature refers to a hydroxy group of a novolak-type phenol resin. The fluorenyl group is preferably a fluorenyl group or a substituted or unsubstituted alkylcarbonyl group having 2 to 15 carbon atoms, and particularly preferably an ethyl fluorenyl group, a propyl fluorenyl group, a butyl fluorenyl group or a trimethyl ethane group.

Preferred examples of the compound represented by the general formula (7) include the following By.

R ^{1 of the} general formula (8) represents a nitrogen atom or an oxygen atom. R ² represents a -COOH or -OH group. R ³ represents an alkyl group having 1 to 10 carbon atoms, and examples thereof include a methyl group and an ethyl group. R ⁴ represents a substituent such as an alkyl group having 1 to 10 carbon atoms.

Specific examples of the compound represented by the general formula (8) include the following By.

The contents of the compounds represented by the general formulae (4) to (8) are relative to The cellulose ester is 0.1 to 15% by mass, preferably 0.5 to 10% by mass, and more preferably 0.5 to 3% by mass. When the content of the above compound is at least a certain level, the density of the film can be sufficiently increased. When the content of the above compound is at most a certain value, the increase in bleeding or haze can be suppressed.

The protective film 13B can be used in the same manner as the protective film 13A. By.

Physical properties of the protective film 13B (dimension change rate)

When the dimensional change rate of the protective film 13B is greatly different from the dimensional change rate of the protective film 13A, strain is also generated inside the polarizing plate 10, and the polarizing plate 10 is liable to be curled (warped). When such a polarizing plate 10 is curled, display unevenness due to the curl is easily regenerated.

Therefore, the dimensional change rate and the protective film of the protective film 13B The difference in dimensional change rate of the film 13A is preferably as low as possible. That is, the dimensional change rate (%) of the longitudinal direction α of the film after the protective film 13B is stored at 80 ° C and 90% RH for 100 hours is B (α), and the short side direction β orthogonal to the direction α When the dimensional change rate (%) is B (β), the protective films A and B satisfy the following formulas (5) and (6).

| A( α )-B( α )|≦0.4...(5)

| A( β )-B( β )|≦0.4...(6)

In order to further suppress the curl of the polarizing plate, |A(α)-B(α)| |A(β)-B(β)| is preferably 0.2 or less, and particularly preferably 0.

(delay)

The in-plane direction retardation R0 and the thickness direction retardation Rth measured under the conditions of the measurement wavelength of 590 nm and 23 ° C of 55% RH of the protective film 13B may be in the same range as the protective film 13A.

(thickness)

The thickness of the protective film 13B is preferably 10 to 60 μm, more preferably 15 to 40 μm, in view of reducing the thickness of the polarizing plate.

1-4. Hardened layer 15 of active energy ray-curable adhesive

The cured layer 15 of the active energy ray-curable adhesive may be composed of a cured product of an active energy ray-curable adhesive. The active energy ray-curable adhesive may be a radical polymerization type active energy ray-curable adhesive using photo-radical polymerization, a cationic polymerization type active energy ray-curable adhesive using photocationic polymerization, or a combination thereof. A hybrid active energy ray-curable adhesive.

Free radical polymerization type active energy ray-curing adhesive JP-A-2008-009329 discloses a radically polymerizable compound containing a polar group such as a hydroxyl group or a carboxyl group, and a radical polymerizable compound containing no polar group, and a composition contained in a specific ratio. The radically polymerizable compound is preferably a compound having a radically polymerizable ethylenically unsaturated bond. Preferred examples of the compound having a radically polymerizable ethylenically unsaturated bond include a compound having a (meth) acrylonitrile group. Examples of the compound having a (meth)acryl fluorenyl group include an N-substituted (meth) acrylamide-based compound, a (meth) acrylate-based compound, and the like. (Meth) acrylamide refers to acrylamide or methacrylamide.

Further, the cationic polymerization type active energy ray hardening type is followed by The agent may be (α) a cationically polymerizable compound, (β) a photocationic polymerization initiator, or (γ), as disclosed in Japanese Laid-Open Patent Publication No. 2011-028234. A light having a longer wavelength of 380 nm, which shows a composition of each component of the highly absorbing light sensitizer and the (δ) naphthalene light sensitizer.

Among these, from the point of view of good adhesion or durability And the like, preferably a radical polymerization type active energy ray-curable adhesive. The radical polymerization type active energy ray-curable adhesive contains a radical polymerizable compound and a photoradical polymerization initiator, and may further contain a photosensitizer or the like if necessary.

The radically polymerizable compound preferably contains an unsaturated compound having one or more ethylenically unsaturated bonds in the molecule. Examples of such an unsaturated compound include a vinyl compound such as a (meth)acrylic compound; N-vinyl-2-pyrrolidone, divinyl adipate, and divinyl sebacate; a triene Isopropyl isocyanurate, triallylamine, tetraallyl pyromellitate, N,N,N ' ,N ' -tetraallyl-1,4-diaminobutyrate An allyl compound such as an alkane, a tetraallyl ammonium salt or an allylamine; an unsaturated carboxylic acid such as maleic acid or econazole, or the like is preferably a (meth)acrylic compound.

An example of a (meth)acrylic compound containing (meth) propylene An acid ester, a (meth) acrylamide, (meth)acrylic acid, (meth) propylene hydrazino morpholine, (meth) acrolein, etc.

An example of a (meth) acrylate comprising methyl (meth) propylene An alkyl (meth) acrylate such as an acid ester, an ethyl (meth) acrylate or a propyl (meth) acrylate; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl ( A hydroxyalkyl (meth) acrylate such as a methyl acrylate; an alicyclic ring such as a cyclohexyl (meth) acrylate or an isodecyl (meth) acrylate; (meth) acrylates of the formula (meth) acrylates such as benzyl (meth) acrylates having aromatic rings; (meth) acrylates such as tripropylene glycol diacrylate Wait. An example of (meth)acrylamide is hydroxyethyl acrylamide.

Photo-radical polymerization initiator of the embodiment, comprising 4 '- phenoxy-2,2-dichloro-acetophenone, 4' -tert- Butyl-2,2-dichloro-acetophenone, 2,2- Dimethoxy-2-phenylacetophenone, 2-methyl-1-(4-methylthiophenyl)-2-morpholinylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, Acetophenone photopolymerization initiators such as α,α-diethoxyacetophenone and 2-hydroxy-2-methyl-1-phenylpropan-1-one; benzoin and benzoin A a benzoin ether photopolymerization initiator of phenyl ether and benzoin ethyl ether; benzophenone, methyl o-benzoylbenzoate, benzophenone of 4-phenylbenzophenone a photopolymerization initiator; a thioxanthone photopolymerization initiator of a thioxanthone photopolymerization initiator such as 2-isopropylthioxanthone or 2,4-diethylthioxanthone; A sulfhydryl phosphide-based photopolymerization initiator of 4,6-trimethylbenzimidyl phenylphosphine oxide.

The radical polymerization type active energy ray-curable adhesive may further contain a photosensitizer. By containing a photosensitizer, the reactivity can be improved, and the mechanical strength or the strength of the cured product can be improved. The photosensitizer includes, for example, a carbonyl compound, an organic sulfur compound, a persulfide compound, a reduced oxidation compound, an azo or a diazo compound, a halogen compound, a photoreductive dye, and the like.

Examples of the photosensitizer include a benzoin derivative such as benzoin methyl ether, benzoin isopropyl ether or α,α-dimethoxy-α-phenylacetophenone; a benzophenone derivative such as benzophenone, 2,4-dichlorobenzophenone or methyl o-benzoylbenzoate; 2-chlorothioxanthone, 2-isopropylthioxanthone, etc. Thiophenone derivatives and the like.

Thickness of the hardened layer 15 of the active energy ray-curable adhesive The degree is usually 0.01 to 10 μm, preferably 0.5 to 5 μm.

1-5. Method of Manufacturing Polarizing Plate 10

The polarizing plate 10 of the present invention is produced by a step of bonding the polarizing mirror 11 and the protective film 13A or 13B with an adhesive. The bonding of the polarizer 11 and the protective film 13A or 13B can be carried out by using a completely saponified polyvinyl alcohol-based adhesive, an ethylene-acetylated polyvinyl alcohol-based adhesive, an active energy ray-curable adhesive, or the like. In the present invention, it is not necessary to use water, and the polarizing mirror 11 and the protective film 13A or 13B can be well adhered to each other in a short time, and therefore, an active energy ray-curable adhesive is preferable. That is, the polarizing plate protective film and the polarizer are preferably followed by a cured layer of an active energy ray-curable adhesive.

That is, the polarizing plate 10 is manufactured by the following steps: 1) a step of facilitating the subsequent treatment with the bonding surface of the polarizing film of the protective film 13A or 13B, and 2) a step of applying at least one of the active energy ray-curable adhesive to the bonding surface of the polarizing mirror and the polarizing plate protective film, 3) a step of bonding the polarizer 11 and the protective film 13A or 13B via the obtained adhesive layer, and 4) passing the polarizer 11 and the protective film 13A or 13B via the adhesive layer, and then proceeding The step of hardening the layer. The steps of 1) can be carried out as necessary.

Examples of the easy processing in the steps of the above 1) can be enumerated Corona treatment, plasma treatment, etc.

In the step of the above 4), the hardened active energy ray is hard The adhesive layer is irradiated with an active energy ray to harden an adhesive layer containing an epoxy compound or an oxetane compound. Thereby, the polarizer and the polarizing plate protective film are bonded via the cured layer of the active energy ray-curable adhesive.

Active energy lines can use visible light, ultraviolet light, X-ray Wires, electronic wires, etc. are easy to handle, and the curing speed is sufficient. Generally, it is suitable to use electronic wires or ultraviolet rays.

Irradiation conditions of the electron wire, as long as it can harden the adhesive Any suitable conditions can be used when the conditions are met. For example, electron beam irradiation, the acceleration voltage is preferably 5 to 300 kV, and more preferably 10 to 250 kV. When the accelerating voltage is less than 5kV, the electron beam does not reach the adhesive, and there is a concern that the hardening is insufficient. When the accelerating voltage exceeds 300kV, the penetration force of the sample is too strong, the electron beam rebounds, and sometimes the polarizing plate protection film or the polarizer is damaged. Doubt. The amount of illumination line is in the range of 5 to 100 kGy, and more preferably in the range of 10 to 75 kGy. When the amount of the irradiation line is less than 5 kGy, the adhesive hardening is insufficient, and when it exceeds 100 kGy, damage to the polarizing plate protective film or the polarizer is caused, and mechanical strength is lowered or yellowed.

The ultraviolet irradiation conditions may be any suitable conditions as long as the conditions for curing the adhesive are used. The amount of ultraviolet light is expressed by the integrated light amount, preferably 50 to 1500 mJ/cm ² , and more preferably 100 to 500 mJ/cm ² .

2. Liquid crystal display device

The liquid crystal display device of the present invention comprises a first polarizing plate, a liquid crystal cell, a second polarizing plate and a backlight in sequence. Then, at least a second polarizing plate, or both of the first polarizing plate and the second polarizing plate can be used as the polarizing plate of the present invention. The polarizing plate-based protective film A of the present invention is preferably disposed on the liquid crystal cell side.

The liquid crystal display device of the present invention can be a television or a notebook type A large-sized liquid crystal display device, such as a personal computer, or a small liquid crystal display device such as a smart phone. In view of the fact that the effect of the present invention is easily obtained, the liquid crystal display device of the present invention is a small liquid crystal having a length of 10 Å or less in the diagonal direction of a display region (not shown) such as a smart phone or the like, preferably 6 inches or less. The display device is preferred.

Fig. 2 is a schematic view showing an example of a small liquid crystal display device. As shown in FIG. 2, the small liquid crystal display device 30 includes a liquid crystal cell 50, a first polarizing plate 70 and a second polarizing plate 90 that hold the liquid crystal cell, and a backlight 110. The small liquid crystal display device 30 further includes a cover glass 130 disposed on a side of the first polarizing plate 70 on the viewing side, a touch panel portion 150 disposed between the first polarizing plate 70 and the liquid crystal cells 50, and a touch panel portion 150 The rechargeable battery 170 on the back side of the backlight 110.

The display mode of the liquid crystal cell 50 can be, for example, STN, TN, Various display modes such as OCB, HAN, VA (MVA, PVA), IPS, FFS (Fringe Field Switching), etc., in view of a wide viewing angle, etc., are preferably IPS mode or FFS mode.

The first polarizing plate 70 is disposed on the liquid crystal cell 50 The surface of the side surface includes a first polarizer 71, a protective film 73B (F1) disposed on a surface opposite to the liquid crystal cell 50 of the first polarizer 71, and a liquid crystal cell 50 side disposed on the first polarizer 71. The protective film 73A (F2) on the surface. The second polarizing plate 90 is disposed on the backlight side of the liquid crystal cell 50, and includes a second polarizing mirror 91, a protective film 93A (F3) disposed on the surface of the second polarizing mirror 91 on the liquid crystal cell 50 side, and configured The protective film 93B (F4) on the surface opposite to the liquid crystal cell 50 of the second polarizer 91. In FIG. 2, both the first polarizing plate 70 and the second polarizing plate 90 are the polarizing plates of the present invention; the protective film 73A (F2) and the protective film 93A (F3) are the aforementioned protective film A (or protective film 13A). The cured layer 75 and 95 of the active energy ray-curable adhesive are the cured layer 15 of the active energy ray-curable adhesive described above.

The touch panel portion 150 is disposed on the liquid crystal cell 50 and the first The polarizing plate 70 (on-cell). However, the position of the touch panel portion 150 is not limited to the embodiment shown in FIG. 2, and the touch panel portion 150 may be integrally disposed on the cover glass 130 (protective glass integrated type); or may be disposed inside the liquid crystal cell 50 ( Built-in (in-cell).

The rechargeable battery 170 can be, for example, a lithium ion secondary battery or the like.

In a liquid crystal display device, usually due to the heat of the backlight or the outer ring The influence of the environment, heat or humidity is easy to change. In particular, the small liquid crystal display device 30 shown in FIG. 2 further includes not only the rechargeable battery 170 that generates heat during charging and discharging, but also has a small volume, so that heat or moisture tends to stay in the device. Therefore, the first polarizer 71 or the second polarizer 91 is also prone to dimensional changes due to changes in heat or humidity in the apparatus.

In the present invention, the protective films 73A (F2) and 93A (F3) are The dimensional change rate is moderately enlarged. Thereby, although the protective film 73A (F2) and the first polarizer 71 are firmly adhered to the cured layer 75 of the active energy ray-curable adhesive, the first polarizer 71 applied to the protective film 73A (F2) can be applied. The contraction force is relatively reduced. Similarly, although the protective film 93A (F3) and the second polarizer 91 are firmly adhered to the cured layer 95 of the active energy ray-curable adhesive, the second polarizer 91 applied to the protective film 93A (F3) can be applied. The contraction force is relatively reduced. As a result of this, the strain of the protective films 73A (F2) and 93A (F3) can be reduced, and optical strain can be suppressed.

In addition, the dimensional change rate and protection of the protective film 73B (F1) The difference in dimensional change ratio of the film 73A (F2) and the difference in dimensional change ratio between the protective film 93A (F3) and the dimensional change rate of the protective film 93B (F4) can be set to be equal to or less than a certain value. Thereby, curling (warping) of the first polarizing plate 70 and the second polarizing plate 90 can be suppressed, and display unevenness due to the same can be further suppressed.

Example

The present invention will be specifically described below by way of examples, but the invention is not limited thereto.

1. Protective film material <Cellulose ester>

Cellulose triacetate (acetamyl substitution degree 2.85, Mw285000)

<polyester compound>

<slip agent>

<High hardness agent>

2. Production of polarizing plate (1) Production of cellulose ester film <Cellulose ester film 101>

The following components were placed in a sealed container, heated to 70 ° C, and the cellulose triacetate was completely dissolved while stirring. The time required for dissolution was 4 hours. The resulting solution was filtered to obtain a dope.

(composition of glue)

Cellulose triacetate (acetamyl substitution degree 2.85, Mw285000): 100 parts by mass

Polyester compound K1: 3 parts by mass

Dichloromethane: 475 parts by mass

Methanol: 50 parts by mass

TINUVIN 928: 2 parts by mass

The above-obtained dope was uniformly cast on a stainless steel belt support of 22 ° C at a dope temperature of 35 ° C using a belt casting apparatus. Then, after drying to a range in which the paste on the support can be peeled off, the film is peeled off from the stainless steel belt support to obtain a film. The amount of residual solvent of the dope at the time of peeling was 25%.

After the obtained film was stretched by a tenter, it was dried while extending in the width direction (TD direction) under the conditions of an extension temperature of 125 ° C and a stretching ratio of 1.05. Next, the width was kept relaxed, and it was conveyed by a plurality of rolls while drying at 110 ° C for 8 minutes. The conveying tension is 70 N/m. Then, embossing was applied to both ends of the film to a width of 10 mm and a height of 5 μm to prepare a cellulose ester film 101 having a film thickness of 25 μm. The film has a width of 1300 mm and a winding length of 3000 m. The winding tension was 150 N/1300 mm in initial tension and 100 N/1300 mm in final winding tension.

<Cellulose ester film 102~107>

The cellulose ester films 102 to 107 were produced in the same manner as in the cellulose ester film 101 except that the content of the polyester compound K1 was changed as shown in Table 4.

<Cellulose ester film 108~114>

The content of the polyester compound K1 was changed to 12 parts by mass, and the film was The cellulose ester film 108 to 114 was produced in the same manner as the cellulose ester film 101, except that the transfer tension, the stretching conditions (extension temperature, stretching ratio), and the drying conditions (drying temperature, drying time) were changed as shown in Table 4.

<Cellulose ester film 115~117>

A cellulose ester film 115 to 117 was produced in the same manner as the cellulose ester film 111 except that the lubricant shown in Table 4 was added.

<Cellulose ester film 118~120>

The cellulose ester film 118 to 120 was produced in the same manner as the cellulose ester film 101 except that the polyester compound K1 was not added and the high hardness agent shown in Table 4 was added, and the production conditions were changed as shown in Table 4.

<Cellulose ester film 121~123>

The cellulose ester film 121 to 123 was produced in the same manner as the cellulose ester film 105 except that the type of the polyester compound was changed as shown in Table 4.

<Cellulose ester film 124>

Further, referring to paragraphs 0161 to 0165 of JP-A-2008-217022, a film corresponding to the transparent film 104 of the publication is produced by the following procedure.

Dissolve the following ingredients to obtain deuterated cellulose (cellulose) Acylate) solution.

(combination of deuterated cellulose solution)

Cellulose triacetate Ce-1 (ethylidene substitution degree 2.94): 100 parts by mass

Dichloromethane: 480.0 parts by mass

Methanol: 71.7 parts by mass

Separation liquid of cerium oxide particles having an average particle diameter of 16 nm: 0.15 parts by mass

Compound A-19 (KI) which reduces optical anisotropy: 9.0 parts by mass

Wavelength dispersion adjusting agent UV-105 (HB): 0.1 parts by mass

Citric acid ester mixture (citric acid, monoethyl ester, diethyl ester, triethyl ester mixture): 0.01 parts by mass

The above deuterated cellulose solution is carried out using a ribbon casting machine Casting. When the amount of the residual solvent was 30%, the film was peeled off from the belt, and it was conveyed by a conveyance roll, and dried at 130 ° C for 40 minutes to prepare a cellulose-deposited film 124. The amount of residual solvent of the deuterated cellulose film obtained by conveying a tension of 100 N/m was 0.1%, and the film thickness was 80 μm.

The following method was used to measure the rule of the obtained cellulose ester film. Inch change rate (MD, TD direction), phase difference (Ro, Rth) and haze.

(dimension change rate)

1) The obtained film was cut into a size of 10 cm × 10 cm to prepare a sample film. The MD direction (direction β) of the sample film was marked at two points of a distance of 100 mm. Similarly, the TD direction (direction α) orthogonal to the MD direction of the sample film is marked at two points of a distance of 100 mm. After the film was allowed to stand at 23 ° C and 55% RH for 24 hours, the distance D0 between two points was measured in each direction.

2) Next, the film was stored in an oven at 80 ° C, 90% RH for 100 hours. Then, it was taken out in the oven, and after being conditioned for 24 hours at 23 ° C and 55% RH, the distance D1 between the two points marked in each direction was measured.

3) Next, the measured value D0 of the above 1) and the measured value D1 of the above 2) are applied to the following formula, and the ratio (%) of the dimensional change before and after storage in the oven is calculated. A negative value indicates that the film is shrinking.

Ratio of dimensional change (%) = (D1-D0) / D0 × 100

(phase difference R0, Rth)

1) The obtained film was conditioned at 23 ° C and 55% RH. The average refractive index of the film after the humidity adjustment is measured using an Abbe refractometer or the like.

2) For the film after humidity control, parallel to the normal to the surface of the film, R ₀ when incident light having a wavelength of 590 nm is incident, measured using KOBRA21ADH, prince measurement (strand).

3) The slow axis in the plane of the film is measured by KOBRA21ADH as the tilt axis (rotation axis), and the angle from the normal to the surface of the film is θ (It incident angle (θ)) A retardation value R(θ) when incident light having a wavelength of 590 nm is incident. The delay value R(θ) can be measured in the range of 0° to 50° θ, and 6 points per 10°. The in-plane slow axis of the film was confirmed by KOBRA21ADH.

4) From the measured R ₀ and R (θ) and the average refractive index and film thickness, nx, ny, and nz were calculated by KOBRA21ADH, and Rth at a measurement wavelength of 590 nm was calculated. The measurement of the delay was carried out at 23 ° C, 55% RH.

(haze)

The obtained film was cut into 5 cm squares as a sample film. The haze of this sample film was measured in accordance with JIS K-7136 using a haze meter (turbidity meter) (type: NDH 2000, manufactured by Nippon Denshoku Co., Ltd.).

The evaluation results of the obtained films 101 to 123 are shown in Table 4.

As shown in Table 4, it contains a specific range of polyester compounds. The film sizes 102 to 106 have a moderate dimensional change rate at 80 ° C and 90% RH, and the phase difference (especially Rth) can also be lowered. Further, the film 101 having a too small content of the polyester compound has a large dimensional change rate or a large phase difference. Further, the internal haze of the film 107 having an excessive content of the polyester compound increases.

By contrast of films 108 and 109, or films 110-112 In contrast, it was found that the dimensional change rate (MD direction, TD direction) of the obtained film was increased by lowering the transport tension, the stretching ratio, and the temperature.

Further, from the comparison of the films 113 and 114, it was found that the dimensional change rate (MD direction, TD direction) of the obtained film was increased by lowering the drying temperature.

By comparing the film 111 with 115~117, it is known that The addition of a slip agent reduces the haze of the resulting film. Since the film containing the lubricant is excellent in slipperiness, even if the conveyance tension is small, contact failure with the conveyance roller is less likely to occur. As a result, the film containing the slip agent can suppress an increase in external haze due to the surface damage of the film.

By contrast of films 105, 121 and 122 with film 123, It was found that the films 105, 121 and 122 using the aromatic ring-free polyester compounds K1, K6 and K5 have a moderately large dimensional change ratio compared to the film 123 using the aromatic ring-containing polyester compound K14.

The measurement method equivalent to the patent document 1 is measured by the above measurement method. As a result of the dimensional change rate of the film 124 of the example, it was found that the dimensional change rate in the MD direction was -0.05%, and the dimensional change rate in the TD direction was -0.05%, which was remarkably small.

<Production of polarizer>

A polyvinyl alcohol film having a thickness of 30 μm was swollen with water at 35 °C. The obtained film was immersed in an aqueous solution composed of 0.075 g of iodine, 5 g of potassium iodide and 100 g of water, and immersed in an aqueous solution of 45 g of potassium iodide, 7.5 g of boric acid and 100 g of water. The obtained film was uniaxially stretched under the conditions of an extension temperature of 55 ° C and a stretching ratio of three times. The uniaxially stretched film was washed with water and dried to obtain a polarizer having a thickness of 5 μm. Similarly, the thickness or elongation conditions of the raw film were adjusted to prepare polarizers having thicknesses of 2 μm, 3 μm, 10 μm, 15 μm, and 20 μm, respectively.

<Production of polarizing plate> (Example 1) 1) Preparation of active energy ray-curable adhesive liquid 1 (radical polymerization type)

After mixing the following components, the radical energy-curable adhesive liquid 1 of the radical polymerization type was prepared by defoaming.

(Active energy ray-curable adhesive solution 1)

Radical polymerizable compound 1: hydroxyethyl acrylamide (HEA, homopolymer Tg123 ° C, manufactured by Xingren Co., Ltd.): 39.1% by mass

Radical polymerizable compound 2: tripropylene glycol diacrylate (Aronix M-220, homopolymer Tg 69 ° C, manufactured by Toagosei Co., Ltd.): 19.0% by mass

Radical polymerizable compound 3: acryloyl morpholine (ACMO, homopolymer Tg 150 ° C, manufactured by Xingren Co., Ltd.): 39.1% by mass

Free radical polymerization initiator 1: diethyl thioxanthone (KAYACURE DETX-S, manufactured by Nippon Kayaku Co., Ltd.): 1.4% by mass

Radical polymerization initiator 2: 2-methyl-1-(4-methylthiophenyl)-2-morpholinylpropan-1-one (IRGACURE 907, manufactured by BASF Corporation): 1.4% by mass

2) Production of polarizing plate

First, the film 102 prepared as the protective film A described above was prepared, and the surface thereof was subjected to a corona discharge treatment. The conditions of the corona discharge treatment were a corona output intensity of 2.0 kW and a line speed of 18 m/min. Next, the above-described prepared radical polymerization type active energy ray-curable adhesive liquid 1 was applied to the corona discharge treated surface of the film by using a coating bar, and the film thickness after curing was about 3 μm to form an activity. An energy line hardening type adhesive layer. The polarizer having a thickness of 5 μm prepared as described above was bonded to the obtained active energy ray-curable adhesive layer.

Next, the thin film prepared as the protective film B is prepared. The film 102 was subjected to a corona discharge treatment under the same conditions as described above. Then, on the corona discharge treatment surface of the film, the radical energy polymerization type active energy ray-curable adhesive liquid 1 prepared as described above was applied in the same manner as described above to form an active energy ray-curable adhesive layer.

Attaching a film to the active energy ray-curable adhesive layer 102 polarizer, laminated film 102 (protective film A) / active energy ray-curable adhesive layer / polarizer / active energy ray-curable adhesive layer / A laminate of film 102 (protective film B).

One side of the laminate was irradiated with a UV irradiation device (Fusion UV Systems, Inc., Light HAMMER 10 valve: V valve peak illuminance: 1600 mW/cm ² ), and ultraviolet rays (a metal halide lamp sealed with gallium). The integrated irradiation amount is 1000 mJ/cm ² (wavelength: 380 to 440 nm), and ultraviolet rays are irradiated to cure the active energy ray-curable adhesive layer to obtain a polarizing plate 202.

(Examples 2 to 13 and 29 to 31, and Comparative Examples 1 to 5)

The polarizing plates 201, 203 to 217, and 233 to 236 were obtained in the same manner as in the first embodiment except that the protective films A and B were changed as shown in Table 5 or Table 7.

(Examples 14 to 18)

The polarizing plates 218 to 222 were obtained in the same manner as in Example 8 except that the thickness of the polarizer was changed as shown in Table 6.

(Embodiment 19)

Modulation of active energy ray-curable adhesive 2 (cationic polymerization type)

After mixing the following components, the active energy ray-curable adhesive liquid 2 was prepared by defoaming. Further, the triarylphosphonium hexafluorophosphate was formulated in a 50% propylene carbonate solution, and the solid content of the triarylsulfonium hexafluorophosphate was shown below.

(Active energy ray-curing adhesive 2)

3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate: 45 parts by mass

EPOLEAD GT-301 (alicyclic epoxy resin manufactured by Daicel Chemical Co., Ltd.): 40 parts by mass

1,4-butanediol diepoxypropyl ether: 15 parts by mass

Triarylsulfonium hexafluorophosphate: 2.3 parts by mass

9,10-dibutoxyanthracene: 0.1 parts by mass

1,4-diethoxynaphthalene: 2.0 parts by mass

Similarly to the above, the film 111 prepared as the protective film A and the protective film B described above was prepared, and the surface thereof was subjected to corona discharge treatment. Next, on the corona discharge treated surface of the film, the above-described prepared radical polymerization type active energy ray-curable adhesive liquid 2 was applied by using a coating bar, and the film thickness after curing was about 3 μm to form an activity. An energy line hardening type adhesive layer. Then, a laminate in which a film 111 (protective film A) / an active energy ray-curable adhesive layer / a polarizer / an active energy ray-curable adhesive layer / a film 111 (protective film B) are laminated is obtained.

One of the laminates was irradiated with a UV irradiation device (Fusion UV Systems, Inc., Light HAMMER 10 valve: V valve), and the total amount of ultraviolet rays (a metal halide lamp sealed with gallium) was 750 mJ/cm. ² (wavelength: 380 to 440 nm), ultraviolet rays are irradiated, and the active energy ray-curable adhesive layer is cured to obtain a polarizing plate 223.

(Examples 20 to 25)

The polarizing plates 224 to 229 were obtained in the same manner as in Example 8 except that the types of the protective film B were changed as shown in Table 6.

(Examples 26 to 28)

The polarizing plates 230 to 232 were obtained in the same manner as in Example 17 except that the types of the protective film B were changed as shown in Table 6.

The obtained polarizing plate was evaluated for curling using the following method.

(curl of polarizing plate)

The polarizing plate was cut into a size of 100 mm × 100 mm as a polarizing plate sample. The obtained polarizing plate sample was stored in an environment of 80 ° C and 90% RH for 300 hours, and then the polarizing plate sample was statically placed on a flat surface, and the protective film A was placed underneath. Then, the height from the plane of the four corners of the polarizing plate sample was measured, and the average value thereof was calculated as the "curl value".

◎: The height of the warped part is less than 2mm

○: The height of the warped portion is 2 mm or more and less than 4 mm.

△: The height of the warped portion is 4 mm or more and less than 6 mm.

×: The height of the warped portion is 6 mm or more

Further, using the obtained polarizing plate, a liquid crystal display device was produced by the following method, and evaluation unevenness was evaluated.

(display uneven) 1) Production of display device

Prepare i-phone5s made by Apple as the display area An IPS mode liquid crystal display device having an angular length of 4 Å, from which two polarizing plates are peeled off. Next, two polarizing plates (polar plates of the same number) produced under the same manufacturing conditions were prepared, and one of them was attached to both sides of the touch panel integrated liquid crystal cell to obtain a display device. The protective film A attached to the polarizing plate is placed in contact with the liquid crystal cell, respectively. The absorption axis of the polarizing plate is made the same as the absorption axis of the pre-adhered polarizing plate.

2) Evaluation

The display unevenness of the obtained display device was evaluated by the following method.

That is, the obtained display device was stored at 50 ° C and 80% RH for 3 hours. Then, the display device was stored in a dark room at 23° C. and 80% RH for a certain period of time, and then the color (black) uniformity of the screen at the time of black display was subjected to sensory evaluation.

◎: There is no unevenness in all

○: There is a slight unevenness, but it is practically within the tolerance range.

△: Unevenness can be seen, there are doubts

×: Obviously observed unevenness

The evaluation results of Examples 1 to 13 and Comparative Examples 1 to 5 are shown in Table 5; the evaluation results of Examples 14 to 28 are shown in Table 6; and the evaluation results of Examples 29 to 31 are shown in Table 7.

As shown in Tables 5 to 7, the protective film A (F2 or F3) is known. The display devices of Examples 1 to 31 having a dimensional change ratio of -0.3% to -1.5% showed less unevenness in display and good visibility. Further, it was found that the polarizing plates of Examples 1 to 28 had less curl.

In contrast, the size of the protective film A (F2 or F3) is known. The display device of Comparative Example 3 whose change rate is too small is large in display unevenness. This is a polarizer and a protective film A (F2 or F3) which is firmly adhered by an active energy ray-curable adhesive, and therefore, a large amount of the contraction force of the polarizer is generated, and optical strain (birefringence) is generated.

In addition, the dimensional change of the protective film A (F2 or F3) is known. The display devices of Comparative Examples 1 and 4 whose ratio is too large have large display unevenness. This is because the dimensional change rate of the protective film is too large, and therefore, the protective film generates unnecessary birefringence. Further, the polarizing plates of Comparative Examples 1 and 4 produced a number of curls. This is because the dimensional change rate of the protective film A is excessively large, and strain occurs between the glass substrate and the liquid crystal cell.

The display device of Comparative Example 2 produces display unevenness protection The content of the polyester compound in the film A (F2 or F3) is too large, and it does not uniformly dissolve with the cellulose ester, and the internal haze rises. Moreover, the comparison of the display device of Comparative Example 2 was also low.

Further, the display of Comparative Example 5 using the film 124 was known. The device produces uneven display. This is because the dimensional change rate of the film 124 is too small, and is mainly caused by the uneven display of the optical strain.

The display device of the seventh embodiment in which the absolute value of the dimensional change rate of the protective film A (F2 or F3) is 0.5% or more is known. The display device of Example 6 having a smaller absolute value of the dimensional change rate than 0.5% is particularly excellent in visibility.

Further, as shown in Table 7, the protective film A (F2 or F3) was known. The polyester compound is a display device of Examples 4 and 29 which does not contain an aromatic ring, and is a display device or polyester of Example 31 containing an aromatic ring as compared with the polyester compound in the protective film A (F2 or F3). The display device of Example 30 having a large molecular weight of the compound showed less unevenness in display. This suggests that the polyester compound having no aromatic ring and having a molecular weight of at least a certain amount tends to moderately increase the dimensional change rate of the protective film A as compared with a polyester compound having an aromatic ring and having a molecular weight of at least a certain value.

In addition, it is known that the thickness of the polarizer is 15 μm or less. The display devices of Examples 15 to 17 were better in visibility than the display device of Example 18 having a thickness of 20 μm. This is because when the thickness of the polarizer is small, the contraction force of the polarizer is also small, and the strain generated by the protective film is also small. In the display device of the fourteenth embodiment in which the thickness of the polarizer is 2 μm, the low visibility is estimated to cause deterioration of the polarizer due to moisture or the like.

Further, the center of the display screen of the display device of the twenty-fifth embodiment In the part, the unevenness was not seen, but the end of the screen was displayed, and uneven light amount was observed. This is the display device of Example 25, which is not caused by the unevenness of the optical strain of the protective film A, but the unevenness caused by the curl of the polarizing plate was observed.

In addition, the dimensional change rate of the protective films A and B is known. The polarizing plates of Examples 22 to 23 and 26 to 28 having a difference of 0.34% or less were compared In the polarizing plates of Examples 20 to 21 and 24 to 25 in which the difference in dimensional change ratio was 0.4% or more, curling was more preferably suppressed.

This application is based on Japan applied for on March 4, 2014. The special wish 2014-041830 claims priority. The contents of this prospectus and the contents described in the drawings are all used in this manual.

Industrial availability

According to the present invention, it is possible to provide a polarizing plate in which the polarizing plate and the protective film are followed by the polarizing plate via the active energy ray-curable adhesive layer, and the visibility of the liquid crystal display device can be suppressed.

11‧‧‧ polarizer

13A‧‧‧Protective film A

13B‧‧‧Protective film B

15‧‧‧ hardened layer of active energy ray-curing adhesive

Claims (14)

A polarizing plate comprising a polarizing mirror, a protective film A disposed on one surface of the polarizing mirror, and a protective film B disposed on the other surface of the polarizing mirror, wherein at least the protective film A is via an active energy ray-curable adhesive a cured layer, wherein the protective film A contains a cellulose ester and a polyester compound obtained by polycondensing a diol with a dicarboxylic acid, and the content of the polyester compound is relative to the cellulose ester. 5 to 30% by mass, the dimensional change rate (%) of the longitudinal direction α of the film after the protective film A is stored at 80 ° C and 90% RH (relative humidity) for 100 hours is A (α), When the dimensional change rate (%) of the short side direction β orthogonal to the longitudinal direction α is A (β), the protective film A satisfies the following formulas (1) and (2), -1.5 ≦ A ( α). ≦-0.3 (1) -1.5 ≦ A ( β ) ≦ - 0.3 (2) The dimensional change rate of the protective film A is measured by the following method: 1) The protective film A is cut into a size of 10 × 10 cm ² , As the sample film, the TD direction (for example, the direction α ) of the sample film is marked at two points of a distance of 100 mm. Similarly, the MD direction (direction β direction) orthogonal to the TD direction of the sample film was marked at two points of a distance of 100 mm, and the film was allowed to stand at 23 ° C, 55% RH (relative humidity) for 24 hours. , measure the distance D0 between the two points in each direction; 2) Next, after the sample film is stored in an oven at 80 ° C, 90% RH (relative humidity) for 100 hours, the sample film is taken out from the oven at 23 ° C, 55 After adjusting the humidity for 24 hours under %RH (relative humidity), measure the distance D1 between the two points in each direction; 3) Next, D0 measured in the above 1) in each direction and D1 measured in the above 2) are applied as follows. In the formula, the dimensional change rate (%) is calculated, and the negative value indicates that the film shrinks, and the dimensional change rate (%) = (D1 - D0) / D0 × 100. The polarizing plate of claim 1, wherein the polyester compound is a dicarboxylic acid selected from the group consisting of an aliphatic dicarboxylic acid and an alicyclic dicarboxylic acid, and an aliphatic diol or an alkyl ether. A compound obtained by polycondensation of a diol selected from the group consisting of an alcohol and an alicyclic diol. The polarizing plate of claim 1, wherein the protective film A satisfies the following formulas (3) and (4), -1.5≦A( α )<-0.5...(3) -1.5≦A( β ) <-0.5...(4). The polarizing plate of claim 1, wherein the protective film B is passed through a cured layer of an active energy ray-curable adhesive, and the polarizing film is followed by the protective film B at 80 ° C, 90% RH (relative The dimensional change rate (%) of the longitudinal direction α of the film after storage for 100 hours under humidity is B (α), and the dimensional change rate (%) of the short side direction β orthogonal to the longitudinal direction α is B ( In the case of β), the protective films A and B satisfy the following formulas (5) and (6), | A( α )-B( α ) | ≦ 0.4 (5) | A( β )-B( β ) | ≦0.4...(6). The polarizing plate of claim 1, wherein the polarizer has a thickness of 3 to 15 μm. The polarizing plate of claim 1, wherein the protective film A is defined by the following formula (I), and the retardation in the in-plane direction measured at a measuring wavelength of 590 nm is Ro (590), and is represented by the following formula (II) As defined, and when the retardation in the thickness direction measured at the measurement wavelength of 590 nm is Rth (590), |Ro(590)|≦10 nm, |Rth(590)|≦10 nm, and (I)Ro=(nx) are satisfied. -ny) × t (nm) Formula (II) Rth = {(nx + ny) / 2 - nz} × t (nm) (in the formulas (I) and (II), nx represents the in-plane direction of the film, The refractive index becomes the refractive index of the largest slow axis direction x; ny represents the refractive index in the direction y orthogonal to the slow axis direction x in the in-plane direction of the film; nz represents the refractive index in the thickness direction z of the film; t ( Nm) indicates the thickness of the film). The polarizing plate of claim 1, wherein the protective film A further contains a lubricant. The polarizing plate of claim 1, wherein the protective film B further contains a high hardness agent. The polarizing plate of claim 1, wherein the protective film A has a thickness of 10 to 60 μm. The polarizing plate of claim 1, wherein the protective film A is disposed on the liquid crystal cell side. A method for producing a polarizing plate according to the first aspect of the invention, comprising the steps of: 1) preparing a protective film A, 2) obtaining a polarizing mirror, and bonding the layer via an active energy ray-curable adhesive layer. a protective film A on one side of the polarizer, a layer of a protective film B disposed on the other surface of the polarizer via an active energy ray-curable adhesive layer, and 3) an active energy ray The step of irradiating the laminate to cure the active energy ray-curable adhesive layer to obtain a polarizing plate, and the step of preparing the protective film A in the above 1) includes the following steps 1A) to 1C): 1A) a cellulose ester and a polyester compound obtained by polycondensing a diol with a dicarboxylic acid, and the content of the polyester compound is a film of 5 to 30% by mass based on the cellulose ester, and 1B) The film is carried out at a temperature of 110 to 135 ° C at a stretching ratio of 1.03 to 1.06 times in a width direction, and 1 C) is carried out under a tension of 70 to 80 N/m. Dry at a temperature of 100~120 °C Step 5 to 10 minutes. A liquid crystal display device comprising a first polarizing plate in sequence, a liquid crystal cell, a second polarizing plate and a backlight, wherein the second polarizing plate is a polarizing plate of claim 1 or 2, and the protective film A of the second polarizing plate is disposed on the liquid crystal cell or the first polarizing plate The two polarizing plates are the polarizing plates of the first aspect of the patent application, and the protective film A of the first polarizing plate and the protective film A of the second polarizing plate are respectively disposed on the liquid crystal cell. The liquid crystal display device of claim 12, wherein the liquid crystal cell is a liquid crystal cell of an IPS mode or an FFS mode. A liquid crystal display device according to claim 12, which is a small liquid crystal display device comprising a display portion having a length of 6 inches or less in a diagonal direction and a rechargeable battery.