JP2004078208A - Method for producing polarizing film, and polarizing film and optical film using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polarizing film capable of forming a liquid crystal display device or an electroluminescence display device having less display unevenness and excellent display characteristics.
SOLUTION: In a swelling step of swelling the polymer film by immersing a hydrophilic polymer film in an aqueous solvent in a swelling bath by conveying the film with a guide roll, at least a first guide roll is arranged in the swelling bath. Immersing the polymer film in the aqueous solvent, and, when moving in the aqueous solvent, the polymer film is brought into contact with the first guide roll until swelling is saturated, A polymer film is dyed with a dichroic material, and the polymer film is stretched to produce a polarizing film.
[Selection diagram] Fig. 1

Description

The present invention relates to a method for producing a polarizing film, and a polarizing film and an optical film using the same.

  Liquid crystal display devices (LCDs) are widely used in desktop electronic calculators, electronic watches, personal computers, word processors, instruments for automobiles and machines, and the like. Such a liquid crystal display device usually includes a polarizing plate for visualizing a change in the orientation of liquid crystal, and this polarizing plate has a very large effect on the display characteristics of the liquid crystal display device.

  As the polarizing plate, generally, a protective film such as triacetyl cellulose is provided on both surfaces of a polarizer (polarizing film) such as a polyvinyl alcohol (PVA) film in which a dichroic substance such as iodine or an organic dye is adsorbed and oriented. Laminated materials and the like are used, and in particular, a polarizer that can provide a liquid crystal display device that is bright, has excellent color reproducibility, and has excellent display characteristics is desired.

  However, in the liquid crystal display device, particularly when a backlight that emits polarized light is used, there is a problem that display unevenness occurs and uniformity of contrast is reduced. In particular, when a high contrast is realized in an image display device, display unevenness is conspicuously observed. For example, when the liquid crystal mode is normally black (a state in which no voltage is applied is a black display state), an oblique 30 The display unevenness becomes remarkable at the time of viewing from directions of °, 40 °, and 60 ° or more.

On the other hand, as a method for producing a polarizer, a hydrophilic polymer film (raw material) is immersed in a swelling bath by being conveyed by a guide roll to swell the polymer film, and then to a dyeing bath containing a dichroic substance. It is general to perform immersion for dyeing, and then to stretching while immersing in a crosslinking bath. So far, as the hydrophilic polymer film, a film in which the uniformity of the thickness of a PVA film has been improved has been disclosed. However, even when such a film is used, retardation unevenness is produced in a manufactured polarizer. It may be generated or the content of the dichroic substance may be uneven.
JP-A-2002-28939 JP 2002-31720 A

For the above reasons, an object of the present invention is to provide a polarizing film for use in various display devices, which shows no more display unevenness and shows uniform display characteristics.

た め In order to achieve the above object, the following first and second production methods are mentioned as a method for producing the polarizing film of the present invention.

That is, the first production method of the present invention comprises a swelling step of immersing the hydrophilic polymer film in an aqueous solvent in a swelling bath by transporting the hydrophilic polymer film with a guide roll to swell the polymer film; A dyeing step of dyeing with a substance, a method for producing a polarizing film including a stretching step of stretching the polymer film,
In the swelling step, at least one guide roll (first guide roll) is arranged in the swelling bath;
When the polymer film is immersed in the aqueous solvent and moved in the aqueous solvent, the polymer film is brought into contact with the guide roll (first guide roll) until the swelling is saturated. It is characterized by the following.

In addition, the second production method of the present invention includes a swelling step of immersing the hydrophilic polymer film in a swelling bath of an aqueous solvent by transporting the film with a guide roll, and swelling the film in the solvent. A dyeing step of dyeing with a hydrophilic substance, a method for producing a polarizing film including a stretching step of stretching the film,
In the swelling step, at least one guide roll (first guide roll) is arranged in the swelling bath;
When the film is immersed in the aqueous solvent and moved in the aqueous solvent, the film is brought into contact with the guide roll (first guide roll) after swelling is saturated. It is characterized by.

、 In order to achieve the above object, the present inventors have made intensive studies on the production of polarizing films. As a result, when the PVA film, which is a hydrophilic polymer film, is immersed in the aqueous solvent of the swelling bath, swelling usually occurs rapidly between 15 seconds and 25 seconds, and when the PVA film contacts the guide roll at that time, It has been found that wrinkles are generated on the film on the guide roll surface, which causes unevenness in the phase difference of the PVA film and also causes unevenness in the content of the dichroic substance. Then, by controlling the time of contact with the guide roll according to the swelling state of the polymer film, specifically, after the hydrophilic polymer film contacts the aqueous solvent of the swelling bath, By controlling the time until it comes into contact with the guide roll, it was found that the above-mentioned unevenness of the phase difference and the unevenness of the content of the dichroic material can be reduced, and the first and second polarizing films as described above were found. I came up with a manufacturing method. In addition, it is considered that wrinkles are caused by slack that occurs in the swelling process because the thin part of the polymer film has a larger elongation due to swelling than other parts, but in order to eliminate this, conventional And a stretching treatment. However, when the wrinkles are eliminated by the stretching treatment, for example, the amount of adsorption of the dichroic substance may be reduced, or the dichroic substance may be detached in a subsequent step (crosslinking step or the like). There is a problem that unevenness becomes remarkable. However, according to the method of the present invention, instead of performing the stretching treatment for the purpose of eliminating wrinkles, the generation of the wrinkles themselves is reduced, so that the conventional problems can be avoided. It should be noted that the present inventors have found for the first time that the relationship between the film and the guide roll in the swelling bath greatly affects wrinkling and uneven dyeing of the polarizing film to be produced.

According to the first and second manufacturing methods of the present invention, the obtained polarizing film has suppressed retardation unevenness and unevenness in the content of the dichroic substance. When applied to various image display devices, particularly large or high-contrast display devices, and flat panel displays, there is an effect that display unevenness (particularly display unevenness in black display) can be sufficiently eliminated.

First, a first manufacturing method of the present invention will be described. As described above, in the first production method of the present invention, the hydrophilic polymer film is immersed in an aqueous solvent in a swelling bath by being conveyed by a guide roll to swell the polymer film. A dyeing step of dyeing with a coloring material, a method for producing a polarizing film including a stretching step of stretching the polymer film,
In the swelling step, at least a first guide roll is arranged in the swelling bath,
The polymer film is immersed in the aqueous solvent, and, when moving in the aqueous solvent, the polymer film is brought into contact with the first guide roll until swelling is saturated. I do. In addition, it is preferable that the polymer film is brought into contact with the first guide roll before the swelling of the polymer film is saturated and before the swelling occurs rapidly.

In the first production method of the present invention, the polymer film only needs to be able to contact the first guide roll before the swelling is saturated, and after the polymer film contacts the aqueous solvent, the first guide roll The time (a) required for contact with the swelling bath is not particularly limited, and can be determined as appropriate depending on, for example, the temperature of the swelling bath. Specifically, it is preferably from 0.6 seconds to 12 seconds. As described above, since the swelling of the polymer film generally occurs rapidly between 15 seconds and 25 seconds, if the required time (a) is 0.6 seconds to 12 seconds, after contact with the first guide roll, Since the swelling of the polymer film occurs rapidly and saturates, the generation of wrinkles is suppressed as a result. This is because retardation unevenness and content unevenness of the dichroic substance can be suppressed in the manufactured polarizing film. The required time (a) is preferably in the range of 1.2 seconds to 9 seconds, more preferably 2.5 seconds to 7 seconds.

The required time (a) can be appropriately determined, for example, according to the temperature of the swelling bath. When the temperature of the swelling bath is 40 ° C. to 50 ° C., the required time is in the range of 2.5 seconds to 4 seconds. In particular, when the temperature is 30 ° C to less than 40 ° C, the range is preferably 2.5 seconds to 6 seconds, and when the temperature is 15 ° C to less than 30 ° C, the range is preferably 2.5 seconds to 7 seconds.

In the first production method of the present invention, when a second guide roll is further arranged in the swelling bath, the polymer film is brought into contact with the first guide roll until swelling is saturated, After the swelling is saturated, it is preferable to contact the second guide roll. With this configuration, it is possible to suppress the occurrence of wrinkles or the like caused by the polymer film coming into contact with the first guide roll, and to swell the polymer film after contacting the first guide roll. This is because even if it comes into contact with the next second guide roll, it is not affected. When the polymer film is brought into contact with the second guide roll, it is sufficient that the swelling of the polymer film does not reach the saturated state, but only after the swelling has rapidly occurred.

The time (b) required for any point of the polymer film to contact the first guide roll to contact the second guide roll is, for example, preferably in the range of 13 seconds to 120 seconds, and more preferably. Ranges from 20 seconds to 100 seconds, particularly preferably from 33 seconds to 80 seconds. The total of the required time (a) and the required time (b) is preferably, for example, in the range of 25 seconds to 180 seconds, more preferably 30 seconds to 160 seconds, and particularly preferably 40 seconds. ~ 140 seconds.

Further, the required time (b) can be appropriately determined depending on the temperature of the swelling bath, similarly to the required time (a). When the temperature of the swelling bath is 40 ° C. to 50 ° C., 15 seconds to 80 seconds. Is particularly preferable, and when it is 30 ° C to less than 40 ° C, the range is particularly preferably 20 seconds to 85 seconds, and when it is less than 15 ° C to 30 ° C, the range of 25 seconds to 90 seconds is particularly preferable.

FIG. 1 is a schematic view showing an example of the swelling step in the first production method of the present invention. As shown in the drawing, two guide rolls 41 and 42 are arranged outside the swelling bath 32, and two guide rolls 43 and 44 are arranged inside the swelling bath 32. Is filled with an aqueous solvent 33. The guide rolls are arranged in order in the direction of travel of the polymer film (the direction of the arrow in the figure), and the guide rolls arranged in the swelling bath 32 are first guide rolls 43 in the forward direction of the polymer film, The other is the second guide roll 44. When the polymer film 31 is transported by the guide roll, a distance from a portion where the polymer film 31 contacts the aqueous solvent (that is, a water surface of the aqueous solvent) to a portion where the polymer film 31 contacts the first guide roll 43. Is “a”, and the time required for an arbitrary point on the polymer film 31 to move the distance a is the required time (a). In addition, the distance from the portion where the polymer film 31 contacts the first guide roll 43 to the portion where the polymer film 31 contacts the second guide roll 44 is “b”, and any point on the polymer film 31 defines the distance b. The time required to move is the required time (b). The number of guide rolls is not particularly limited, and may be further provided inside and outside the swelling bath as needed.

When such a swelling bath is used, first, the polymer film 31 is transported from the outside of the swelling bath 32 (left side in the figure) into the swelling bath by a guide roll and immersed in the aqueous solvent 33. Then, the distance “a” is moved until the swelling of the polymer film 31 is saturated, and the swelling of the polymer film 31 is saturated until the polymer film 31 reaches the second guide roll 44 from the first guide roll 43. The required time (a) and the required time (b) are as described above.

The distance a from the portion where the polymer film comes into contact with the aqueous solvent 33 of the swelling bath 32 to the portion where it comes into contact with the first guide roll 43 is not particularly limited, but is, for example, in the range of 4 to 2400 mm. Is a distance “b” from a portion contacting the first guide roll 43 to a portion contacting the second guide roll 44, that is, the distance between the first guide roll 43 and the second guide roll 44 is particularly large. Although not limited, for example, it is in the range of 80 to 36000 mm. The transport speed of the film is, for example, 6 to 200 mm / sec.

種類 The type of the guide roll is not particularly limited, and a conventionally known roll can be used. For example, a roll shown in the schematic diagram of FIG. 3 can be used. In the same figure, (a) is a flat roll having no irregularities on the surface, (b) is a crown roll having an effect of extending wrinkles, (c) is an expander roll, (d) is an ear height roll, and (e) is a spiral. Roll. In addition to these, vent rolls and the like can also be used. Among them, as described in JP-A-2000-147252, a spiral roll is preferred to be used in addition to the first guide roll because there is a possibility that the hydrophilic polymer film may have its mark. The same applies to the manufacturing method of (1). In addition, the guide roll preferably has a wrinkle-extending effect. However, for example, it is preferable that the guide roll does not extend in the lateral direction more than elongation due to swelling in the width direction of the film. Specifically, when the length in the width direction of the film stretched by swelling is set to 100%, the stretch ratio by the guide roll is preferably, for example, 20% or less, more preferably 10%. Or less, more preferably 5% or less.

The material of the various rolls is not particularly limited, and includes, for example, metals and polymers. Expander rolls, at least the ear height portion of the ear height roll, and the spiral roll, for example, are treated in a swelling bath. It is preferable that the surface energy is close to the surface energy of the film in the state.

Next, a second manufacturing method of the present invention will be described. The second production method of the present invention is, as described above, a swelling step of immersing the hydrophilic polymer film in a swelling bath of an aqueous solvent by transporting the film with a guide roll, and swelling the film in the solvent, A dyeing step of dyeing with a dichroic material, a method for producing a polarizing film including a stretching step of stretching the film,
In the swelling step, at least a first guide roll is arranged in the swelling bath,
When the film is immersed in the aqueous solvent and moved in the aqueous solvent, the film is brought into contact with the first guide roll after swelling is saturated.

In the second production method of the present invention, the polymer film only needs to be able to contact the first guide roll after swelling is saturated, and the first guide roll is formed after an arbitrary point of the film contacts the aqueous solvent. The time (c) required to contact the roll is not particularly limited, but is preferably, for example, 25 to 180 seconds. As described above, since the swelling of the polymer film generally occurs rapidly between 15 and 25 seconds, if the required time (a) is 25 seconds or more, the polymer film is not allowed to contact the first guide roll until it contacts the first guide roll. This is because the swelling is saturated, and as a result, the generation of wrinkles is suppressed. On the other hand, when the time is 180 seconds or less, the sag of the polymer film is further prevented, and the transport of the film becomes more stable. As a result, it is possible to further suppress the retardation unevenness and the content unevenness of the dichroic substance in the manufactured polarizing film. The required time (c) is preferably in the range of 30 seconds to 160 seconds, more preferably 40 seconds to 140 seconds. In the second manufacturing method, when the polymer film comes into contact with the first guide roll, the swelling does not have to reach a saturated state, as long as the swelling occurs rapidly.

In addition, the required time (c) can be appropriately determined according to the temperature of the swelling bath, similarly to the required times (a) and (b). When the temperature of the swelling bath is 40 ° C to 50 ° C, the required time is 40 to 50 ° C. A range of 140 seconds is particularly preferable, and a range of 45 to 140 seconds is particularly preferable when the temperature is 30 ° C to less than 40 ° C, and a range of 50 to 140 seconds is particularly preferable when the temperature is 15 ° C to less than 30 ° C.

例 An example of the swelling step in the second production method of the present invention is shown in the schematic diagram of FIG. As shown in the figure, two guide rolls 41 and 42 are arranged outside the swelling bath 32, and one guide roll (first guide roll) 45 is arranged inside the swelling bath 32. The inside of the swelling bath 32 is filled with an aqueous solvent 33. Each of the guide rolls is arranged in order in the direction of movement of the polymer film (the direction of the arrow in the figure). When the polymer film 31 is transported by the guide roll, the distance from the portion where the polymer film 31 contacts the aqueous solvent 33 to the portion where the polymer film 31 contacts the first guide roll 45 is “c”. The time required for an arbitrary point of the polymer film to move the distance c is the required time (c). The number of guide rolls is not particularly limited, and may be further provided inside and outside the swelling bath as needed.

When such a swelling bath is used, first, the polymer film 31 is transported from the outside of the swelling bath 32 (left side in the figure) into the swelling bath by a guide roll and immersed in the aqueous solvent 33. Then, the polymer film 31 is swollen while being moved, and the swelling of the polymer film 31 is saturated until the polymer film 31 reaches the second guide roll 44. The required time (c) is as described above.

距離 The distance “c” from the portion where the polymer film comes into contact with the aqueous solvent of the swelling bath 32 to the portion where it comes into contact with the first guide roll is not particularly limited, but is, for example, in the range of 150 to 36000 mm. The transport speed of the film is, for example, 6 to 200 mm / sec.

Next, an example of a series of manufacturing steps of the first and second manufacturing methods of the present invention will be described. Specifically, the hydrophilic polymer film is swollen under the conditions described above, the dichroic substance is dyed in a dye bath, stretched in a cross-linking bath, washed with water and dried to obtain a polarizing film (polarized film). Child).

(1) Hydrophilic polymer film The hydrophilic polymer film is not particularly limited, and a conventionally known film can be used. For example, a PVA film, a partially formalized PVA film, polyethylene terephthalate (PET), ethylene Examples include hydrophilic polymer films such as vinyl acetate copolymer films and partially saponified films thereof. In addition to these, a polyene oriented film such as a PVA dehydrated product or a polyvinyl chloride dehydrochlorinated product, and a stretch-oriented polyvinylene-based film can also be used. Among these, a PVA-based polymer film is preferable because of its excellent dyeability with the dichroic substance iodine. Hereinafter, in the polymer film, the length in the stretching direction is referred to as “length”, and the length in the direction perpendicular to the stretching direction is referred to as “width”.

平均 The average polymerization degree of the PVA film is not particularly limited, but is preferably in the range of 100 to 5000, more preferably 1000 to 4000, from the viewpoint of the solubility of the film in water. The saponification degree is, for example, preferably 75 mol% or more, more preferably 98 to 100 mol%.

The thickness of the polymer film is not particularly limited, but is, for example, 110 μm or less, preferably in the range of 38 to 110 μm, more preferably 50 to 100 μm, and particularly preferably 60 to 80 μm. When the thickness is 110 μm or less, when the manufactured polarizer is mounted on an image display device, the color change of the display panel can be sufficiently suppressed, and when the thickness is in the range of 60 to 80 μm, the stretching process is further easily performed. Because.

The polymer film preferably contains, for example, a plastic material in the polymer film, for example, in order to suppress unevenness in retardation or unevenness in the content of a dichroic substance in the manufactured polarizing film. The content of the plastic material in the polymer film is not particularly limited as long as the effects of the present invention can be achieved. For example, the content of the plastic material is 1 to 17% by mass relative to the total amount of the film (100% by mass). Is preferred. Within the above range, the handleability of the polymer film is sufficiently excellent, the breakage can be further prevented, and the influence on the film formation can be sufficiently avoided.

可塑 The plastic material is not particularly limited as long as it can plasticize the polymer film, and conventionally known materials can be used. Specifically, a water-soluble plastic material is preferable, for example, glycols such as ethylene glycol, diethylene glycol, propylene glycol, and low molecular weight polyethylene glycol (Mw: 200 to 400); glycerin derivatives such as glycerin, diglycerin, and triglycerin And the like. Among these, glycerin derivatives are preferred, and glycerin is particularly preferred, because they have strong interaction with PVA and have high compatibility. Thus, when the polymer film is a PVA film and the water-soluble plastic material is glycerin, the content of glycerin in the total amount of the film (100% by mass) is preferably 3 to 16% by mass, more preferably 5 to 15% by mass. % Range.

、 As the polymer film, for example, it is preferable to use a film that has little swelling variation, that is, a thickness variation due to swelling in the swelling treatment in the next step. This is because variations in retardation, dichroic substance content, transmittance, and the like of the manufactured polarizer can be further reduced. For this reason, for example, it is preferable to use a polymer film having less crystallinity unevenness, thickness unevenness, and variation in moisture content. Further, a polymer film having no variation in glycerin content is also preferable. Even if the thickness varies, the swelling degree is relatively large in relatively thin places and the swelling degree is relatively small in relatively thick places. Therefore, sufficient swelling reduces the problem of thickness variation. It is possible to do.

(2) Swelling treatment The polymer film is immersed in a swelling bath, moved in the swelling bath so as to satisfy the above-mentioned conditions, and subjected to a swelling treatment. In the swelling step, for example, it is preferable to perform a stretching treatment on the polymer film while swelling. This is because, even if the swelling further proceeds by the stretching treatment and wrinkles are slightly generated on the guide roll, this can be solved.

水性 Examples of the aqueous solvent of the swelling bath include an aqueous solution for swelling treatment containing water, acid, alkali, electrolyte and the like. Acids, alkalis, and types and concentrations of the electrolyte are not particularly limited as long as they do not affect the retardation unevenness of the polarizer to be manufactured or the unevenness of the content of the dichroic substance, and conventionally known ones can be used. . Specific examples include electrolytes such as potassium and sodium, and glycerin. Particularly, when the polymer film is a PVA film, it preferably contains glycerin.

温度 The temperature of the aqueous solvent in the swelling bath is preferably, for example, 15 to 50 ° C. When the temperature is 15 ° C. or higher, the processing time can be shortened, so that the productivity is further improved, and when the temperature is 50 ° C. or lower, sufficiently excellent optical characteristics can be obtained.

The stretch ratio of the polymer film in the swelling treatment is preferably, for example, 1.5 to 4.0 times, more preferably 1.times., The length of the polymer film (raw material) before the swelling treatment. It is 7 to 3.8 times, and more preferably 1.9 to 3.6 times. With such a magnification, the dyeability of the dichroic dye in the next dyeing step is sufficiently improved, and the optical characteristics are sufficiently maintained. In particular, the lower the draw ratio, the more the dyeing unevenness in the dyeing step described later can be reduced, and if it is 4 times or less, the occurrence of uneven streaks can be further suppressed.

に お い て In the swelling step, the time for immersing the polymer film in the swelling bath is preferably 100 seconds or more in total. If it is 100 seconds or more, since the swelling is in a saturated state or close to a saturated state, for example, the draw ratio can be reduced to about 1.1 to 1.5 times, and the dyeing unevenness can be further improved. Because. On the other hand, even when the total immersion time is less than 100 seconds, the stretching treatment described above can reduce uneven dyeing.

(2) Dyeing treatment The polymer film is pulled up from the swelling bath, immersed in, for example, a dyeing bath containing a dichroic substance, and further stretched uniaxially in the dyeing bath. That is, the dichroic substance is adsorbed on the polymer film by the immersion, and the dichroic substance is oriented in one direction by stretching.

  As the dichroic substance, conventionally known substances can be used, and examples thereof include iodine and organic dyes. When using the organic dye, for example, it is preferable to combine two or more types from the viewpoint of neutralizing the visible light region.

  As the solution of the dye bath, an aqueous solution in which the dichroic substance is dissolved in a solvent can be used. As the solvent, for example, water can be used, but an organic solvent compatible with water may be further added. The concentration of the dichroic substance in the solution is not particularly limited, but is usually in the range of 0.1 to 10.0 parts by mass with respect to 100 parts by mass of the solvent (for example, water). The solution may further contain an auxiliary agent such as potassium iodide.

  The conditions for immersing the polymer film in the dye bath are not particularly limited, but the temperature of the dye bath is, for example, in the range of 20 to 70 ° C., and the immersion time is, for example, in the range of 5 to 20 minutes. The stretching magnification in the dyeing treatment is preferably, for example, in the range of 2 to 4 times the length of the polymer film (raw material) before swelling.

(3) Crosslinking treatment The polymer film is pulled out of the dyeing bath, immersed in a crosslinking bath containing a crosslinking agent, and further stretched in the crosslinking bath. The running stability is maintained by performing the crosslinking treatment.

  As the crosslinking agent, a conventionally known substance can be used, and examples thereof include boron compounds such as boric acid, borax, glyoxal, and glutaraldehyde. These may be used alone or in combination of two or more. As the solution of the crosslinking bath, an aqueous solution in which the crosslinking agent is dissolved in a solvent can be used. As the solvent, for example, water can be used, and it may further contain an organic solvent compatible with water.

  The concentration of the crosslinking agent in the solution is not particularly limited, but is usually preferably in the range of 0.1 to 10% by mass relative to 100% by mass of the solvent (for example, water). When the crosslinking agent is boric acid, for example, it is in the range of 1.5 to 8% by weight, preferably 2 to 6% by weight.

  The aqueous solution, in addition to the boric acid compound, for example, potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, iodine An auxiliary agent such as iodide such as lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and titanium iodide may be contained. Among these, a combination of boric acid and potassium iodide is preferred. The content of the auxiliary agent in the solution is usually in the range of 0.05 to 15% by mass.

温度 The temperature of the crosslinking bath is not particularly limited, but is usually in the range of 20 to 70 ° C, preferably in the range of 40 to 60 ° C. The immersion time of the polymer film is not particularly limited, but is usually 1 second to 15 minutes.

  The stretching ratio in this crosslinking treatment is preferably, for example, 5 to 7 times the length of the raw fabric. When stretching the polymer film, the stretching method and the number of stretching are not particularly limited, and may be performed in each step of the dyeing step and the crosslinking step as described above, or may be performed in only one of the steps, Further, it may be performed a plurality of times in the same step.

(4) Washing / drying treatment The polymer film is pulled out of the stretching bath, washed with water and dried to obtain a polarizing film. Drying is not particularly limited, for example, natural drying, air drying, heating drying, etc., but in the case of heating drying, the temperature is usually 20 to 80 ° C., and the processing time is usually in the range of 1 to 10 minutes. .

  Although the thickness of the finally obtained polarizing film of the present invention is not particularly limited, for example, it is generally in the range of 1 to 80 μm, and more preferably 2 to 45 μm. If the thickness is, for example, 1 μm or more, shows even more excellent mechanical strength, and if it is 80 μm or less, for example, when mounted on a liquid crystal display device, the color change of the display panel can be sufficiently suppressed, In addition, the thickness can be easily reduced.

Next, the polarizing film of the present invention is a polarizing film obtained by the first and second production methods of the present invention, and can be used, for example, as a polarizer.

光学 Further, the optical film of the present invention is characterized by containing the polarizing film of the present invention. Examples of such an optical film are shown below.

A first example of the optical film of the present invention includes, for example, a polarizing plate including the polarizing film of the present invention and a transparent protective layer, wherein the transparent protective layer is disposed on at least one surface of the polarizing film. . The transparent protective layer may be disposed on only one side of the polarizing film, or may be disposed on both sides. When laminating on both sides, for example, the same type of transparent protective layer may be used, or different types of transparent protective layers may be used.

  FIG. 4 shows a cross-sectional view of an example of the polarizing plate. As shown in the figure, the polarizing plate 10 includes a polarizing film 1 and two transparent protective layers 2, and the transparent protective layers 2 are disposed on both surfaces of the polarizing film 1.

  The transparent protective layer 2 is not particularly limited, and a conventionally known transparent protective film can be used. For example, those having excellent transparency, mechanical strength, heat stability, moisture barrier properties, isotropy, and the like are preferable. . Specific examples of the material of such a transparent protective layer include cellulose resins such as triacetyl cellulose, polyester, polycarbonate, polyamide, polyimide, polyethersulfone, polysulfone, polystyrene, and acrylic. And transparent resins such as acetate, polyolefin and the like. Further, there may be mentioned a thermosetting resin such as acrylic, urethane, acrylic urethane, epoxy and silicone, or an ultraviolet curable resin. Further, a resin having a low photoelastic coefficient, such as a polynobornene-based resin, is also preferable.

In addition, as described in JP-A-2001-343529 (WO 01/37007) and JP-A-2002-328233, for example, an alternating copolymer comprising isobutene and N-methylmaleimide is used. A film made of a mixed extrudate of a resin composition containing acrylonitrile / styrene copolymer can also be used. Such a film can be manufactured, for example, as described below. First, the alternating copolymer (100 parts by weight) having an N-methylmaleimide content of 50 mol% and 67 parts by weight of the acrylic copolymer having a tolyl content of 27 wt% and a styrene content of 73 wt% were melt-kneaded. The pellets are supplied to a melt extruder equipped with a T die to produce a raw film. This film is subjected to free-end longitudinal uniaxial stretching at a stretching speed of 100 cm / min, a stretching ratio of 1.45 times, and a stretching temperature of 162 ° C. Further, by performing free-end uniaxial stretching in the direction perpendicular to the above stretching direction under the same conditions, a stretched film having a thickness of 49 μm can be obtained. This stretched film has nx = 1548028, ny = 1.548005, nz = 1.547970, an in-plane retardation of 1.1 nm, a thickness direction retardation of 2.8 nm, and an absolute value of the photoelastic coefficient of 1.9 × 10-13 cm ² / dye.

Furthermore, the surfaces of these transparent protective films may be saponified with an alkali or the like, for example. Among these, a TAC film is preferable in terms of polarization characteristics and durability, and more preferably a TAC film whose surface is saponified.

It is preferable that the transparent protective layer has no coloring, for example. Specifically, the retardation value (Rth) in the film thickness direction represented by the following formula is preferably in the range of -90 nm to +75 nm, more preferably -80 nm to +60 nm, and particularly preferably -70 nm. ＋+ 45 nm. When the retardation value is in the range of -90 nm to +75 nm, coloring (optical coloring) of the polarizing plate caused by the protective film can be sufficiently eliminated.
Rth = [{(nx + ny) / 2} -nz] · d
In the above formula, d is the thickness of the transparent protective layer, and nx, ny, and nz indicate the X-, Y-, and Z-axis refractive indexes of the transparent protective layer, respectively. The X axis is an axis direction showing the maximum refractive index in the plane of the transparent protective layer, the Y axis is an axis direction perpendicular to the X axis in the plane, and the Z axis is the X axis. The thickness direction perpendicular to the axis and the Y axis is shown.

  The thickness of the transparent protective layer is not particularly limited, but is, for example, 500 μm or less, preferably 1 to 300 μm, more preferably 5 to 300 μm, for the purpose of reducing the thickness of the polarizing plate. .

  Further, the transparent protective layer may be further subjected to, for example, a hard coat treatment, an antireflection treatment, an anti-sticking treatment, a treatment for the purpose of diffusion, antiglare, or the like. The hard coat treatment is for the purpose of preventing scratches on the surface of the polarizing plate and the like, for example, a process of forming a cured film made of a curable resin and having excellent hardness and slipperiness on the surface of the transparent protective layer. It is. As the curable resin, for example, an ultraviolet curable resin such as a silicone-based, urethane-based, acrylic-based, or epoxy-based resin can be used, and the treatment can be performed by a conventionally known method.

  The antireflection treatment is intended to prevent reflection of external light on the surface of the polarizing plate, and can be performed by forming a conventionally known antireflection film or the like. The purpose of the anti-sticking treatment is to prevent adhesion between adjacent layers.

  The anti-glare treatment is to reflect external light on the surface of the polarizing plate, to prevent obstruction of light transmitted through the polarizing plate, and the like.For example, by a conventionally known method, the surface of the transparent protective layer is finely divided. This can be performed by forming an uneven structure. Examples of the method of forming such a concavo-convex structure include a method of forming a surface by sandblasting or embossing, and a method of forming the transparent protective layer by blending transparent fine particles with the transparent resin as described above. Can be

The transparent fine particles include, for example, silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, and solid solutions thereof. The average particle size of such transparent fine particles is not particularly limited, but is, for example, in the range of 0.5 to 50 μm. In addition, inorganic fine particles having conductivity, organic fine particles composed of crosslinked or uncrosslinked polymer particles, and the like can also be used. The blending ratio of the transparent fine particles is not particularly limited, but is generally preferably in the range of 2 to 50 parts by mass, more preferably in the range of 5 to 25 parts by mass per 100 parts by mass of the transparent resin as described above.

The anti-glare layer containing the transparent fine particles can be used, for example, as the transparent protective layer itself, or may be formed as a coating layer on the surface of the transparent protective layer. Further, the anti-glare layer may also serve as a diffusion layer for diffusing light transmitted through the polarizing plate to increase the viewing angle.

  In addition, the antireflection film, the diffusion layer, the antiglare layer, and the like can be provided on the polarizing plate separately from the transparent protective layer, for example, as an optical layer including a sheet provided with these layers.

方法 The method of bonding the polarizer and the transparent protective layer is not particularly limited, and can be performed by a conventionally known method. Generally, an adhesive or other adhesive is used, and the type can be appropriately determined depending on the type of the polarizing film or the transparent protective layer. Specific examples include adhesives and pressure-sensitive adhesives composed of PVA-based, modified PVA-based, and urethane-based polymers. These adhesives and the like, for the purpose of improving durability, for example, a vinyl alcohol-based polymer such as boric acid, borax, glutaraldehyde, melamine, oxalic acid, chitin, chitosan, metal salts, alcohol-based solvents, etc. A water-soluble crosslinking agent for crosslinking may be added. When the polarizer is, for example, a PVA-based film, a PVA-based adhesive is preferable from the viewpoint of the stability of the bonding treatment and the like. The thickness of such an adhesive layer is not particularly limited, but is, for example, 1 nm to 500 nm, preferably 10 nm to 300 nm, and more preferably 20 nm to 100 nm.

When the polarizer and the transparent protective layer are adhered by the adhesive, for example, a drying treatment is performed to prevent the polarizer from peeling off due to the influence of humidity or heat and to obtain a polarizing plate having excellent light transmittance and degree of polarization. Is preferably applied. The drying temperature is not particularly limited, and can be appropriately determined according to the type of the adhesive or the pressure-sensitive adhesive used. When the pre-adhesive is a water-soluble adhesive such as a PVA-based, modified PVA-based, or urethane-based adhesive described above, for example, the drying temperature is preferably from 60 to 70 ° C, more preferably from 60 to 75 ° C, The drying time is preferably about 1 to 10 minutes.

  Further, for example, the polarizing plate of the present invention preferably further has a pressure-sensitive adhesive layer as the outermost layer, since it can be easily laminated on a liquid crystal cell or the like. FIG. 5 shows a cross-sectional view of a polarizing plate having such an adhesive layer. As shown, the polarizing plate 20 includes the polarizing plate 10 and the pressure-sensitive adhesive layer 3 shown in FIG. 4, and the pressure-sensitive adhesive layer 3 is further disposed on the surface of one of the transparent protective layers 2 of the polarizing plate 10. .

The formation of the pressure-sensitive adhesive layer on the surface of the transparent protective layer, for example, by directly adding a solution or melt of the pressure-sensitive adhesive to a predetermined surface of the transparent protective layer by a developing method such as casting or coating. It can be carried out by a method of forming a layer, a method of forming an adhesive layer on a separator similarly described later, and transferring the pressure-sensitive adhesive layer to a predetermined surface of the transparent protective layer. In addition, such an adhesive layer may be formed on any one surface of the polarizing plate as shown in FIG. 5, but is not limited thereto, and may be arranged on both surfaces as needed. .

  The pressure-sensitive adhesive layer can be formed by appropriately using, for example, a conventionally known pressure-sensitive adhesive such as an acrylic, silicone, polyester, polyurethane, polyether, or rubber. In particular, from the viewpoint of preventing foaming and peeling phenomena due to moisture absorption, preventing deterioration of optical characteristics due to a difference in thermal expansion and preventing warpage of a liquid crystal cell, and forming a high-quality and durable liquid crystal display device, the moisture absorption rate is high. It is preferable to use an adhesive which is low and has excellent heat resistance. Examples of such an adhesive include acrylic, silicone, acrylic silicone, polyester, and heat-resistant rubber adhesives. Further, it may be an adhesive layer containing fine particles and exhibiting light diffusibility.

  When the surface of the pressure-sensitive adhesive layer provided on the polarizing plate is exposed, the surface is preferably covered with a separator for the purpose of preventing contamination and the like until the pressure-sensitive adhesive layer is put to practical use. The separator may be provided with a release coat using a release agent such as a silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide, as necessary, on an appropriate thin film such as the transparent protective film. Can be formed.

The thickness of the pressure-sensitive adhesive layer is not particularly limited, but is preferably, for example, 5 to 35 μm, more preferably 10 to 25 μm, and particularly preferably 15 to 25 μm. By setting such a range, for example, even if the dimensions of the polarizing plate change, the stress generated at that time can be reduced.

  The polarizing plate of the present invention can be used for forming a liquid crystal cell, a liquid crystal display device, or the like. For example, in a state where a transparent protective layer or the like is laminated on the polarizer, cutting is performed according to the size of the liquid crystal cell or the like. (Chip cutting), or the polarizer may be cut in advance, and then a transparent protective layer may be attached.

  Next, a second example of the optical film of the present invention is a laminate including the polarizer of the present invention or the polarizing plate of the first example, and at least one of a polarization conversion element and a retardation film.

  The polarization conversion element is not particularly limited, and examples thereof include those generally used for forming a liquid crystal display device and the like, such as an anisotropic reflection type polarization element and an anisotropic scattering type polarization element. These polarization conversion elements may be, for example, one layer or two or more layers. When two or more layers are used, the same kind or different kinds of layers may be used.

  Among the polarization conversion elements, the anisotropic reflection-type polarizing element is, for example, a composite of a cholesteric liquid crystal layer and a retardation plate, and the retardation plate has a reflection property of the anisotropic reflection polarizer. It is preferable to show a phase difference of 0.2 to 0.3 times the wavelength included in the band. More preferably, it is 0.25 times. As the cholesteric liquid crystal layer, in particular, an oriented film of a cholesteric liquid crystal polymer, such as one in which the oriented liquid crystal layer is supported on a film substrate, or the like, reflects either left-handed or right-handed circularly polarized light. In addition, it is preferable that other light transmit the light. As such an anisotropic reflective polarizer, for example, a PCF series manufactured by Nitto Denko or the like can be used. The wavelength may be any wavelength as long as it is included in the reflection band of the anisotropic reflective polarizer. The cholesteric liquid crystal layer transmits linearly polarized light having a predetermined polarization axis and reflects other light, such as a multilayer thin film of a dielectric or a multilayer laminate of thin films having different refractive index anisotropies. It may be one that shows the characteristics of As such an anisotropic reflective polarizing element, for example, DBEF series manufactured by 3M Company or the like can be used.

  As the anisotropic reflection-type polarizing element, a reflection-type grid polarizer is also preferable, and as a specific example, MicroWires (trade name, manufactured by Moxtek) can be used.

  On the other hand, as the anisotropic scattering type polarizing element, for example, a trade name DRPF manufactured by 3M can be used.

  Next, a third example of the optical film of the present invention includes, for example, the polarizer of the present invention, the polarizing plate of the first example, or the laminate of the second example, and various optical layers. Various polarizing plates which are laminates are exemplified. The optical layer is not particularly limited. For example, a retardation plate including a λ plate such as a reflector, a semi-transmissive reflector, a 波長 wavelength plate, a 波長 wavelength plate, or the like, as described below, a viewing angle Examples include optical layers used for forming liquid crystal display devices and the like, such as compensation films and brightness enhancement films. One kind of these optical layers may be used, or two or more kinds may be used in combination. As the polarizing plate including such an optical layer, in particular, a reflective polarizing plate, a transflective polarizing plate, an elliptically polarizing plate, a circular polarizing plate, a polarizing plate on which a viewing angle compensation film or a brightness enhancement film is laminated, and the like are preferable. .

  Hereinafter, these polarizing plates will be described.

  First, an example of the reflective polarizing plate or the transflective polarizing plate of the invention will be described. The reflective polarizing plate is, for example, a reflective plate is further laminated on the polarizing plate of the first example as described above, the semi-transmissive reflective polarizing plate, the semi-transmissive reflective plate further has a semi-transmissive reflective plate. It is laminated.

The reflective polarizer is usually disposed on the back side of a liquid crystal cell, and can be used for a liquid crystal display device (reflective liquid crystal display device) that reflects incident light from the viewing side (display side) to display. Such a reflective polarizer can omit the incorporation of a light source such as a backlight, for example, and thus has advantages such as enabling the liquid crystal display device to be thinner.

  The reflection type polarizing plate can be manufactured by a conventionally known method such as a method of forming a reflection plate made of metal or the like on one surface of the polarizing plate after the heat treatment. Specifically, for example, one surface (exposed surface) of the transparent protective layer in the polarizing plate is subjected to a mat treatment as necessary, and a metal foil or a vapor-deposited film made of a reflective metal such as aluminum is coated on the surface. And the like.

  In addition, as described above, a reflective polarizing plate and the like, in which a reflective plate reflecting the fine uneven structure is formed on a transparent protective layer having a fine uneven structure on the surface by incorporating fine particles in various transparent resins as described above, may also be used. Can be A reflector having a fine uneven structure on its surface has an advantage that, for example, incident light is diffused by irregular reflection, directivity and glare can be prevented, and uneven brightness can be suppressed. Such a reflection plate, for example, on the uneven surface of the transparent protective layer, a vacuum deposition method, an ion plating method, a deposition method such as a sputtering method or a plating method, a conventionally known method, directly, the metal foil or It can be formed as a metal deposition film.

  Further, instead of a method in which the reflective plate is directly formed on the transparent protective layer of the polarizing plate as described above, a reflective sheet or the like provided with a reflective layer on an appropriate film such as the transparent protective film is used as the reflective plate. May be. Since the reflection layer in the reflection plate is usually made of metal, for example, to prevent a decrease in reflectance due to oxidation, and thus a long-lasting initial reflectance, and in order to avoid separately forming a transparent protective layer, It is preferable that the mode of use is such that the reflection surface of the reflection layer is covered with the film, the polarizing plate, or the like.

  On the other hand, the transflective polarizing plate has a transflective reflecting plate in place of the reflecting plate in the reflecting type polarizing plate. Examples of the semi-transmissive reflection plate include a half mirror that reflects light on a reflection layer and transmits light.

  The transflective polarizing plate is usually provided on the back side of a liquid crystal cell. When a liquid crystal display device or the like is used in a relatively bright atmosphere, it reflects incident light from the viewing side (display side) to form an image. In a relatively dark atmosphere for display, the present invention can be used for a liquid crystal display device or the like that displays images using a built-in light source such as a backlight built in the back side of a transflective polarizing plate. That is, the transflective polarizing plate can save energy for use of a light source such as a backlight in a bright atmosphere, and can be used with the built-in light source even in a relatively dark atmosphere. It is useful for formation of etc.

  Next, an example of the elliptically polarizing plate or the circularly polarizing plate of the present invention will be described. In these polarizing plates, for example, a retardation plate or a λ plate is further laminated on the polarizing plate of the first example as described above.

When the elliptically polarizing plate compensates (prevents) coloring (blue or yellow) caused by birefringence of a liquid crystal layer of a super twisted nematic (STN) type liquid crystal display device, for example, to provide a monochrome display without coloring. It is effectively used for such purposes. Further, an elliptically polarizing plate having a controlled three-dimensional refractive index is preferable because, for example, coloring that occurs when a screen of a liquid crystal display device is viewed from an oblique direction can be compensated (prevented). On the other hand, the circularly polarizing plate is effective for, for example, displaying an image in color, adjusting the color tone of an image of a reflective liquid crystal display device, and has an antireflection function.

The retardation plate is used for converting linearly polarized light to elliptically polarized light or circularly polarized light, for converting elliptically polarized light or circularly polarized light to linearly polarized light, or for polarizing the direction of linearly polarized light. In particular, as a retardation plate for converting linearly polarized light into elliptically polarized light or circularly polarized light and elliptically polarized light or circularly polarized light into linearly polarized light, for example, a quarter-wave plate (also referred to as “λ / 4 plate”) or the like is used. In the case where the polarization direction of the linearly polarized light is used, a 波長 wavelength plate (also referred to as a “λ / 2 plate”) is usually used.

As the material of the retardation plate, for example, polycarbonate, PVA, polystyrene, polymethyl methacrylate, polypropylene and other polyolefins, polyarylate, polyamide, birefringent film obtained by stretching a polymer film such as polynorbornene, a liquid crystal polymer Examples include an alignment film and a laminate in which an alignment layer of a liquid crystal polymer is supported by a film.

  Types of the retardation plate include, for example, various wavelength plates such as the １ ／ and ４, and those for the purpose of compensating for coloring due to birefringence of a liquid crystal layer and compensating for a viewing angle such as expansion of a viewing angle. A film having a phase difference according to the purpose may be used, or an obliquely oriented film having a controlled refractive index in the thickness direction may be used. Further, a laminated body in which two or more kinds of retardation plates are laminated and optical characteristics such as retardation are controlled may be used.

  For example, a method of applying a heat-shrinkable film to a polymer film and subjecting the polymer film to a stretching process or a shrinking process under the action of the shrinkage force by heating, or a method of obliquely aligning a liquid crystal polymer, And the like.

  Next, an example of a polarizing plate in which a viewing angle compensation film is further laminated on the polarizing plate of the first example will be described.

The viewing angle compensation film is a film for widening the viewing angle so that an image can be seen relatively clearly even when the screen of the liquid crystal display device is viewed not in a direction perpendicular to the screen but in a slightly oblique direction. As such a viewing angle compensation film, for example, a film obtained by coating a discotic liquid crystal on a triacetyl cellulose film or the like, or a retardation plate is used. As a normal retardation plate, for example, a uniaxially stretched in the plane direction, a polymer film having birefringence is used, while as the viewing angle compensation film, for example, biaxially stretched in the plane direction Retardation of bidirectionally stretched polymer film such as a polymer film having birefringence or a biaxially stretched film such as a uniaxially stretched film in a plane direction and also a film stretched in a thickness direction and having a controlled refractive index in a thickness direction. A board is used. Examples of the inclined alignment film include, for example, a film obtained by bonding a heat shrinkable film to a polymer film and subjecting the polymer film to a stretching treatment or a shrinking treatment under the action of the contraction force by heating, or a liquid crystal polymer obliquely oriented. And the like. In addition, as the raw material of the polymer film, the same material as the polymer material of the retardation plate extended above can be used.

Next, an example of a polarizing plate in which a brightness enhancement film is further laminated on the polarizing plate of the first example will be described.

偏光 This polarizing plate is usually used by being arranged on the back side of a liquid crystal cell. The brightness enhancement film is, for example, a backlight of a liquid crystal display device or the like, and reflects natural polarized light or linearly polarized light of a predetermined polarization axis or circularly polarized light of a predetermined direction when natural light is incident thereon, and transmits other light. It shows the characteristics of Light from a light source such as a backlight is incident to obtain transmitted light in a predetermined polarization state, and light other than the predetermined polarization state is reflected without transmitting. The light reflected on the surface of the brightness enhancement film is further inverted through a reflector or the like provided on the rear side thereof, and re-entered on the brightness enhancement film, and a part or all of the light is transmitted as light of a predetermined polarization state. In addition to increasing the amount of light transmitted through the brightness enhancement film, the polarization film (polarizer) is supplied with polarized light that is hardly absorbed, thereby increasing the amount of light that can be used for liquid crystal image display and the like, thereby improving the brightness. Things. Without using the brightness enhancement film, when light is incident through the polarizer from the back side of the liquid crystal cell with a backlight or the like, light having a polarization direction that does not match the polarization axis of the polarizer is almost absorbed by the polarizer. And does not pass through the polarizer. That is, although it depends on the characteristics of the polarizer used, about 50% of the light is absorbed by the polarizer, and accordingly, the amount of light that can be used for liquid crystal image display and the like decreases, and the image becomes darker. The brightness enhancement film, light having a polarization direction as absorbed by the polarizer, without being incident on the polarizer, once reflected by the brightness enhancement film, further provided a reflector provided on the back side And then re-enter the brightness enhancement film. Then, the polarization direction of the light reflected and inverted between the two passes through only the polarized light having a polarization direction that can pass through the polarizer, and supplies the polarized light to the polarizer. The light can be efficiently used for displaying an image on the liquid crystal display device, and the screen can be brightened.

Further, a diffusion plate may be provided between the brightness enhancement film and the reflection layer or the like. In this case, the light in the polarization state reflected by the brightness enhancement film is directed to the reflection layer, but the diffuser provided uniformly diffuses the passing light, and at the same time, eliminates the polarization state and changes the non-polarization state. And That is, it returns to the original natural light state. The light in the non-polarized state, that is, the light in the natural light state is repeatedly directed to the reflection layer or the like, reflected through the reflection layer, passed through the diffusion plate again, and re-enters the brightness enhancement film. As described above, by providing the diffusion plate that returns to the original natural light state, for example, while maintaining the brightness of the display screen, simultaneously reducing unevenness in the brightness of the display screen and providing a uniform bright screen. Can be. Further, it is considered that the diffusion plate appropriately increases the number of repetitions of reflection of the first incident light, and can provide a uniform bright display screen in combination with the diffusion function of the diffusion plate.

  The brightness enhancement film is not particularly limited, for example, a multilayer thin film of a dielectric, such as a multilayer laminate of thin film having different refractive index anisotropy, transmitting linearly polarized light of a predetermined polarization axis, Other light that shows a characteristic of reflecting light can be used. Specifically, for example, D-BEF (trade name, manufactured by 3M) can be used. In addition, such as a cholesteric liquid crystal layer, especially an alignment film of cholesteric liquid crystal polymer, or a film in which the alignment liquid crystal layer is supported on a film substrate, reflects either left or right circularly polarized light and transmits other light. May be indicated. As such a film, for example, “PCF350” (trade name, manufactured by Nitto Denko Corporation), and “Transmax” (trade name, manufactured by Merck) can be used.

  Therefore, in the case of a brightness enhancement film of a type that transmits linearly polarized light having a predetermined polarization axis, for example, the transmitted light is directly incident on the polarization plate with the polarization axis aligned, thereby suppressing absorption loss by the polarization plate. In addition, the light can be efficiently transmitted. On the other hand, a brightness enhancement film that transmits circularly polarized light, such as a cholesteric liquid crystal layer, can be directly incident on the polarizer.However, from the viewpoint of suppressing absorption loss, the transmitted circularly polarized light is transmitted through a retardation film. It is preferable that the light is converted into linearly polarized light through the polarizing plate and is incident on the polarizing plate. In addition, a circularly polarized light can be converted into a linearly polarized light by using, for example, a 波長 wavelength plate as the retardation plate.

  A retardation plate that functions as a quarter-wave plate in a wide wavelength range such as a visible light region is, for example, a retardation layer that functions as a quarter-wave plate with respect to monochromatic light such as light having a wavelength of 550 nm, and other layers. It can be obtained by laminating a retardation layer exhibiting retardation characteristics (for example, a retardation layer functioning as a half-wave plate). Therefore, the retardation plate disposed between the polarizing plate and the brightness enhancement film may be a laminate including one or two or more retardation layers. Note that the cholesteric liquid crystal layer can also have a stacked structure in which two or three or more layers are stacked by combining those having different reflection wavelengths. Thus, a polarizing plate that reflects circularly polarized light in a wide wavelength range such as a visible light region can be obtained, and based on that, transmitted circularly polarized light in a wide wavelength range can be obtained.

  The various polarizing plates in the third example as described above may be, for example, an optical film in which the polarizing plate and two or three or more optical layers are laminated. Specifically, for example, a reflective elliptically polarizing plate or a semi-transmissive elliptically polarizing plate obtained by combining the above-mentioned reflective polarizing plate or semi-transmissive polarizing plate with a retardation plate can be used.

  As described above, an optical film in which two or more optical layers are laminated can be formed, for example, by a method of sequentially and separately laminating in a manufacturing process of a liquid crystal display device or the like. However, there is an advantage that, for example, the stability of quality and the workability of assembling are excellent, and the manufacturing efficiency of a liquid crystal display device or the like can be improved. In addition, various bonding means, such as an adhesive layer, can be used for lamination similarly to the above.

  Each layer such as a polarizing film, a transparent protective layer, an optical layer and a pressure-sensitive adhesive layer forming the optical film of the present invention as described above is, for example, a salicylate compound, a benzophenone compound, a benzotriazole compound, a cyanoacrylate compound. Alternatively, those having an ultraviolet absorbing ability by appropriately treating with an ultraviolet absorbing agent such as a nickel complex compound may be used.

  Next, the liquid crystal panel of the present invention includes at least one of the polarizer and the optical film of the present invention (hereinafter, also referred to as “optical film”), which is disposed on at least one surface of the liquid crystal cell.

  The type of the liquid crystal cell is not particularly limited, and a conventionally known liquid crystal cell can be appropriately used. However, the polarizer and the like of the present invention are useful for a liquid crystal display device that displays light by causing polarized light to enter the liquid crystal cell. For this reason, among others, for example, a liquid crystal cell using a TN (Twisted Nematic) liquid crystal or an STN (Super Twisted Nematic) liquid crystal is preferable. In addition to these, a liquid crystal cell of IPS (In-Plane Switching), VA (Vertical Aligned), OCB (Optically Compensated Birefringence) mode using a non-twist type liquid crystal, or the dichroic dye is incorporated in the liquid crystal. It can also be used for a liquid crystal cell using a dispersed guest-host liquid crystal or a ferroelectric liquid crystal. Note that there is no particular limitation on the driving method of the liquid crystal.

  The optical film such as the polarizing plate may be disposed on only one surface of the liquid crystal cell, or may be disposed on both surfaces. When the optical films are arranged on both surfaces, the types of the optical films may be the same or different. When a polarizing plate or an optical member is provided on both sides of the liquid crystal cell, they may be the same or different.

  Further, ordinary components such as a prism array sheet, a lens array sheet, and a light diffusion plate may be provided at appropriate positions, and one or more of these components may be arranged.

  6 to 8 show examples of a liquid crystal panel on which the optical film of the present invention is arranged. These figures are cross-sectional views showing the state of lamination of a liquid crystal cell and an optical film, and are hatched to distinguish components. In the respective drawings, the same parts are denoted by the same reference numerals. Note that the liquid crystal panel of the present invention is not limited to these.

  The liquid crystal panel of FIG. 6 has a liquid crystal cell 12 and a polarizing plate 11, and the polarizing plates 11 are arranged on both surfaces of the liquid crystal cell 12, respectively. The structure (not shown) of the liquid crystal cell is not particularly limited, and is generally a structure in which liquid crystal is held between an array substrate and a filter substrate.

  The liquid crystal panel of FIG. 7 includes a liquid crystal cell 12, a polarizing plate 11, and a phase difference plate 13, and the polarizing plates 11 are laminated on both sides of the liquid crystal cell 12 with the phase difference plate 13 interposed therebetween. Note that the retardation plate 13 and the polarizing plate 11 may be disposed on both surfaces of the liquid crystal cell 12 as an integrated optical film of the present invention.

  The liquid crystal panel shown in FIG. 8A includes a liquid crystal cell 12, a polarizing plate 11, and a polarization conversion element 14. The polarizing plates 11 are laminated on both surfaces of the liquid crystal cell 12, respectively. The elements 14 are stacked. As the polarization conversion element 14, the above-described element can be used. For example, as shown in FIG. 1B, a composite of a quarter-wave plate 15 and a cholesteric liquid crystal 16 or the same in FIG. The anisotropic multiple thin film reflective polarizing element 17 shown in FIG. Note that the polarizing plate 11 and the polarization conversion element 14 may be disposed on one surface of the liquid crystal cell 12 as an integrated optical film of the present invention.

  Next, a liquid crystal display device of the present invention is a liquid crystal display device including a liquid crystal panel, wherein the liquid crystal panel is the liquid crystal panel of the present invention.

  The liquid crystal display device may further include a light source. The light source is not particularly limited, but is preferably, for example, a planar light source that emits polarized light, because light energy can be used effectively.

  In the liquid display device of the present invention, for example, a diffusion plate, an anti-glare layer, an antireflection film, a protective layer or a protective plate is further disposed on an optical film (polarizing plate) on the viewing side, or a liquid crystal cell in a liquid crystal panel. A compensating retardation plate or the like may be appropriately disposed between the polarizing plate and the polarizing plate.

  Next, an electroluminescent (EL) display device of the present invention is a display device having at least one of the polarizer of the present invention and the optical film of the present invention. This EL device may be either an organic EL or an inorganic EL.

In recent years, in an EL display device, it has been proposed to use an optical film such as a polarizer or a polarizing plate together with a λ / 4 plate to prevent reflection from an electrode in a black state. The polarizer or the optical film of the present invention is particularly suitable for the case where any one of linearly polarized light, circularly polarized light or elliptically polarized light is emitted from the EL layer, or even when natural light is emitted in the front direction, This is very useful when the emitted light in the direction is partially polarized.

First, a general organic EL display device will be described. The organic EL display device generally has a light-emitting body (organic EL light-emitting body) in which a transparent electrode, an organic light-emitting layer, and a metal electrode are stacked in this order on a transparent substrate. The organic light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer made of a triphenylamine derivative or the like and a light emitting layer made of a fluorescent organic solid such as anthracene, Various combinations such as a stacked body of a light emitting layer and an electron injection layer made of a perylene derivative or the like, and a stacked body of the hole injection layer, the light emitting layer, and the electron injection layer are given.

  In such an organic EL display device, by applying a voltage to the anode and the cathode, holes and electrons are injected into the organic light emitting layer, and the holes and electrons are recombined. The emitted energy emits light on the principle that it excites the phosphor and emits light when the excited phosphor returns to the ground state. The mechanism of the recombination of holes and electrons is the same as that of a general diode, and the current and the emission intensity show strong nonlinearity with rectification with respect to the applied voltage.

In the organic EL display device, at least one electrode is required to be transparent in order to extract light emitted from the organic light emitting layer. Therefore, the organic EL display device is usually formed of a transparent conductor such as indium tin oxide (ITO). A transparent electrode is used as the anode. On the other hand, in order to facilitate electron injection and increase luminous efficiency, it is important to use a material having a small work function for the cathode, and usually a metal electrode such as Mg-Ag or Al-Li is used.

In the organic EL display device having such a configuration, it is preferable that the organic light emitting layer is formed of, for example, an extremely thin film having a thickness of about 10 nm. This is because light is transmitted almost completely in the organic light emitting layer as in the case of the transparent electrode. As a result, when light is not emitted, light that enters from the surface of the transparent substrate, passes through the transparent electrode and the organic light emitting layer, and is reflected by the metal electrode exits to the surface of the transparent substrate again. Therefore, when viewed from the outside, the display surface of the organic EL display device looks like a mirror surface.

  The organic EL display device of the present invention includes, for example, an organic EL display device including a transparent electrode on a front surface side of the organic light emitting layer and the organic EL light emitting body including a metal electrode on a back surface side of the organic light emitting layer. The optical film of the present invention (such as a polarizing plate) is preferably disposed on the surface of the transparent electrode, and a λ / 4 plate is preferably disposed between the polarizing plate and the EL element. Thus, by arranging the optical film of the present invention, an organic EL display device has an effect of suppressing reflection of the outside world and improving visibility. Further, it is preferable that a retardation plate is further disposed between the transparent electrode and the optical film.

  Since the retardation plate and the optical film (such as a polarizing plate) have a function of, for example, polarizing light incident from the outside and reflected by the metal electrode, the mirror effect of the metal electrode is visually recognized by the polarizing function. It has the effect of not letting it. In particular, if a quarter-wave plate is used as the phase difference plate and the angle between the polarization direction of the polarizing plate and the phase difference plate is adjusted to π / 4, the mirror surface of the metal electrode is completely shielded. can do. That is, only linearly polarized light components of the external light incident on the organic EL display device are transmitted by the polarizing plate. The linearly polarized light is generally converted into elliptically polarized light by the retardation plate. In particular, when the retardation plate is a quarter-wave plate and the angle is π / 4, the linearly polarized light becomes circularly polarized light.

This circularly polarized light, for example, passes through a transparent substrate, a transparent electrode, an organic thin film, is reflected by a metal electrode, again passes through an organic thin film, a transparent electrode, a transparent substrate, and is again linearly polarized by the retardation plate. Become. And, since this linearly polarized light is orthogonal to the polarization direction of the polarizing plate, it cannot pass through the polarizing plate, and as a result, the mirror surface of the metal electrode can be completely shielded as described above. .

  Further, the in-house manufacturing method for a liquid crystal display device and an EL display device according to the present invention includes the polarizer according to the present invention, which includes a surface protection film on the display surface side, and an adhesive layer and a release layer on the opposite surface. A manufacturing method including a step of bonding at least one of the optical films of the present invention to the display device immediately after chip cutting.

  Thus, according to the in-house manufacturing method of cutting the polarizer or the optical film and producing various display devices by consistently performing bonding to a liquid crystal cell or the like, for example, in order to detect a defective area, Measurements must be made immediately, and marking decisions must be made by setting limit samples or measuring inline. According to the manufacturing method of the present invention, the polarizer or the optical film of the present invention is marked on a portion not satisfying the above condition (1), and immediately after punching, is bonded to a liquid crystal panel or an EL display element to perform various displays. The device can be manufactured. In this way, the processes from punching, sorting, and bonding of the polarizer and optical film can be performed consistently, and the inspection time can be simplified, so that manufacturing is simplified and cost reduction is achieved. You can also plan. Note that, in-house generally refers to an integrated line from punching of a roll of a polarizing plate to inspection and bonding to a LCD.

  Next, the present invention will be further described with reference to the following Examples and Comparative Examples. Note that the present invention is not limited to only these examples. Unless otherwise specified, “%” means “% by mass”.

(Example 1)
As shown in FIG. 1, two guide rolls (flat rolls) were previously arranged in a swelling bath, and pure water was put in the bath as a swelling solvent and kept at 25 ° C. A 75 μm-thick PVA film (trade name: VF-PS # 7500; manufactured by Kuraray Co., Ltd.) is transferred to the swelling bath by a guide roll, and the film is swelled in the swelling bath. Stretching was performed so that the ratio became 2.5 times. The time (a) from when the film comes into contact with the solvent in the swelling bath until it comes into contact with the first guide roll by transport is 3.5 seconds, and the time (a) after the film comes into contact with the first guide roll and the second time comes. (B) until contact with the guide roll was 60 seconds. The total time during which any point of the film was immersed in the swelling bath was 92 seconds.

This film is immersed in a mixed solution of 0.04% of iodine and 0.4% of potassium iodide (a dyeing bath, the same applies hereinafter) so that the length of the film in the dyeing bath is three times the length of the raw material. While stretching the film, the film was dyed. This film was further immersed in a 3.5% boric acid aqueous solution (stretching bath) and stretched so as to be 6 times as large as the original, thereby producing a polarizing film (thickness: 27 μm). Then, after a TAC film (trade name: TD-80U; manufactured by Fuji Photo Film Co., Ltd.) having a thickness of 80 μm was saponified, the polarizing film was bonded to both surfaces of the polarizing film with a 1% PVA aqueous solution, and dried to prepare a polarizing plate. .

(Example 2)
In the swelling process, the time (a) from the time when the film comes into contact with the solvent in the swelling bath until it comes into contact with the first guide roll by transport is 2 seconds, and the second guide after coming into contact with the first guide roll. A polarizing film and a polarizing plate were produced in the same manner as in Example 1 except that the time (b) until the contact with the roll was 35 seconds. The total time during which any point of the film was immersed in the swelling bath was 63 seconds.

(Example 3)
In the swelling process, the time (a) from when the film comes into contact with the solvent in the swelling bath until it comes into contact with the first guide roll by conveyance is 11 seconds, and further, after the film comes into contact with the first guide roll, the second guide is reached. A polarizing film and a polarizing plate were produced in the same manner as in Example 1 except that the time (b) until contact with the roll was 110 seconds. The total time during which any point of the film was immersed in the swelling bath was 130 seconds.

(Example 4)
As shown in FIG. 2, one guide roll is arranged in the swelling bath, and the time (c) from when the film comes into contact with the solvent in the swelling bath until it comes into contact with the first guide roll by conveyance is 70 seconds. A polarizing film and a polarizing plate were produced in the same manner as in Example 1 except that the above conditions were satisfied. The total time during which any point of the film was immersed in the swelling bath was 75 seconds.

(Example 5)
In advance, as shown in FIG. 1, two guide rolls were arranged in a swelling bath, water was introduced into the bath as a swelling solvent, and the temperature was maintained at 32 ° C. A 75 μm-thick PVA film (trade name: OPL-M; manufactured by Nippon Synthetic Chemical Co., Ltd.) is transferred to the swelling bath by a guide roll, and the film is swelled in the swelling bath. Stretching was performed so that the ratio became 1.9 times. The time (a) from when the film comes into contact with the solvent of the swelling bath until it comes into contact with the first guide roll by transport is 5 seconds, and further, after the film comes into contact with the first guide roll, The time (b) until the contact with the substrate was 77 seconds. The total time during which any point of the film was immersed in the swelling bath was 121 seconds.

This film is immersed in a mixed solution of 0.04% iodine and 0.4% potassium iodide (dye bath), and is 2.8 times the length of the raw fabric in the dye bath. The film was dyed while stretching. This film was further immersed in a 3.5% boric acid aqueous solution (stretching bath) and stretched so as to have a length six times the length of the raw fabric, thereby producing a polarizing film (thickness: 30 μm). Then, the saponified TAC film was bonded to both sides of the polarizing film with a 1% PVA aqueous solution, and dried to prepare a polarizing plate.

(Example 6)
Using the same PVA film as in Example 5, replacing the guide roll with a spiral roll, the time (a) from contact of the film with the solvent of the swelling bath to contact with the first guide roll by transport was 11 seconds, Further, a polarizing film and a polarizing plate were produced in the same manner as in Example 1 except that the time (b) from contact with the first guide roll to contact with the second guide roll was 110 seconds. In the spiral roll, the width of the groove (recess) was 1 cm, and the depth of the groove was 1 cm. The total time during which any point of the film was immersed in the swelling bath was 128 seconds.

(Example 7)
Using the same PVA film as in Example 5, replacing the guide roll with a crown roll, the stretching ratio in the swelling bath was 2.1 times the length of the raw fabric, and the stretching ratio in the dyeing bath was the length of the raw fabric. The time (a) from the contact of the film with the solvent of the swelling bath to the contact with the first guide roll by conveyance is 2.9 times, and the time (a) is 2 seconds. A polarizing film and a polarizing plate were produced in the same manner as in Example 1 except that the time (b) until the contact with the guide roll of No. 2 was 35 seconds. The total time during which any point of the film was immersed in the swelling bath was 63 seconds.

(Example 8)
Using the same PVA film as in Example 5, the swelling bath temperature was 42 ° C., and in the swelling treatment, the time from contact of the film with the solvent of the swelling bath to contact with the first guide roll by transport was 6 seconds ( a) Further, except that the time (b) from contact with the first guide roll to contact with the second guide roll (b) was set to 60 seconds, the polarizing film and the polarizing plate were removed in the same manner as in Example 1 above. Produced. The total time during which any point of the film was immersed in the swelling bath was 95 seconds.

(Example 9)
As shown in FIG. 2, one guide roll (crown roll) was placed in the swelling bath, and the same PVA film as in Example 5 was used. A polarizing film and a polarizing plate were produced in the same manner as in Example 4 except that the time (c) until the contact with the guide roll was changed to 170 seconds. The total time during which any point of the film was immersed in the swelling bath was 173 seconds.

(Comparative Example 1)
In the swelling process, the time (a) from the time when the film comes into contact with the solvent in the swelling bath until it comes into contact with the first guide roll by transport is 14 seconds, and the second time after the film comes into contact with the first guide roll. A polarizing film and a polarizing plate were produced in the same manner as in Example 1 except that the time (b) until contact with the guide roll was 75 seconds. The total time during which any point of the film was immersed in the swelling bath was 94 seconds.

(Comparative Example 2)
In the swelling process, the time (a) from when the film comes into contact with the solvent in the swelling bath until it comes into contact with the first guide roll by transport is 0.3 seconds, and after the film comes into contact with the first guide roll, A polarizing film and a polarizing plate were produced in the same manner as in Example 1 except that the time (b) until the contact with the guide roll No. 2 was set to 4 seconds. The total time during which any point of the film was immersed in the swelling bath was 15 seconds.

(Comparative Example 3)
In the swelling treatment, except that the time (c) from the time when the film comes into contact with the solvent in the swelling bath to the time when the film comes into contact with the first guide roll by conveyance was set to 22 seconds, the same procedure as in Example 4 was carried out. A polarizing plate was manufactured. The total time during which any point of the film was immersed in the swelling bath was 24 seconds.

(Comparative Example 4)
Using the same PVA film as in Example 5, replacing the guide roll with a spiral roll (same as in Example 6), setting the swelling temperature to 38 ° C., and increasing the stretching ratio in the swelling bath to 2.5 times the length of the raw material. The stretching ratio in the dyeing bath was 3.2 times the length of the raw fabric, and the time (c) from when the film contacted the solvent of the swelling bath until it contacted the first guide roll was 188 seconds. Except for the above, a polarizing film was produced in the same manner as in Example 4. The total time during which any point of the film was immersed in the swelling bath was 191 seconds. However, in Comparative Example 4, the running property of the film was poor and a polarizing film could not be produced.

(Comparative Example 5)
Using the same PVA film as in Example 5, the swelling bath temperature was 32 ° C., the stretching ratio in the swelling bath was 2.8 times the length of the raw fabric, and the stretching ratio in the dyeing bath was 2.8 times the length of the raw fabric. The time (a) from the time when the film comes into contact with the solvent of the swelling bath to the time when the film comes into contact with the first guide roll by 3.5 times is 15 seconds. A polarizing film and a polarizing plate were produced in the same manner as in Example 1 except that the time (b) until the contact with the guide roll of No. 2 was 5 seconds. The total time during which any point of the film was immersed in the swelling bath was 21 seconds.

(Evaluation method of display unevenness)
Each of the polarizing plates obtained in Examples 1 to 9 and Comparative Examples 1 to 3 and 5 was cut into a length of 25 cm × a width of 20 cm, and an adhesive was applied to the surface (light source side) of a high-contrast IPS liquid crystal cell. Then, SEG1425DU (trade name, manufactured by Nitto Denko) was bonded to the other surface (viewing side) of the liquid crystal cell. The obtained liquid crystal panel was placed on various backlights (A to D) to be described later such that the polarizing plate on the light source side (the prepared polarizing plate) faced down. Then, on the viewing side of the liquid crystal panel, observation was made from the front and oblique directions (30 °, 45 °, 60 °), and unevenness during black display was evaluated based on the following evaluation criteria. In the following evaluation criteria, 7 to 6 show excellent effects, 5 to 3 are practical, and 2-1 are practically impossible.

(Evaluation criteria)
7: No unevenness is observed.
6: Unevenness is slightly visible in a dark room, but no unevenness is seen under a fluorescent lamp.
5: Unevenness is visible in a dark room, but no unevenness is seen under a fluorescent lamp.
4: Unevenness is clearly visible in a dark room, but no unevenness is seen under a fluorescent lamp.
3: Slight unevenness is seen under fluorescent light.
2: Unevenness is visible under fluorescent light.
1: Unevenness is clearly visible under fluorescent light.

(Backlight A)
FIG. 9 is a cross-sectional view schematically showing the backlight A. As shown in the figure, this backlight 6 is provided with a cold cathode tube 26 and a lamp house 27 on a wedge-type light guide plate 22 having a printed back surface, a diffusion plate 21 on the upper surface, and a diffuse reflection plate on the lower surface. 23 were arranged respectively.

(Backlight B)
FIG. 10 is a cross-sectional view schematically showing the backlight B. As shown in the drawing, this backlight 7 has a laminated body of a cholesteric layer and a λ / 4 plate layer arranged on the backlight 6 shown in FIG. At this time, the laminate was arranged such that the cholesteric surface (16) was on the backlight 6 side and the λ / 4 plate (15) was on the viewer side. When the liquid crystal cell is arranged on the backlight 7 as described above, the amount of transmitted light is maximized. In addition, as the laminate of the cholesteric layer and the λ / 4 plate layer, a laminate obtained by removing only the polarizing plate portion from PCF400TEG (trade name, manufactured by Nitto Denko Corporation) was used.

(Backlight C)
FIG. 11 is a cross-sectional view schematically showing the backlight C. As shown in the drawing, the backlight 8 has an anisotropic multiple thin-film reflective polarizer (trade name: DBEF; manufactured by 3M) 17 disposed on the backlight 6 shown in FIG. When the liquid crystal cell is arranged on the backlight 8 as described above, the amount of transmitted light is maximized.

(Backlight D)
FIG. 12A is a cross-sectional view schematically showing a backlight D, and FIG. 12B is a diagram schematically showing a partial outline of the above-mentioned (A). As shown in the figure, the backlight 9 is provided with a cold cathode tube 26 and a lamp house 27 on a wedge-type light guide plate 25 having a prism formed on a light exit surface, and a diffuse reflection plate 23 on the lower surface of the light guide plate 25. The prism sheet 24 is disposed on the upper surface of the light guide plate 25. The prism sheet 24 was disposed so that its prism face faced the prism face of the light guide plate 25, as shown in a partially enlarged view (B) of FIG. Then, the diffusion plate 21 is further disposed on the upper surface of the prism sheet 24.

　表１から明らかなように、実施例１〜９の偏光板は、比較例１〜３および５の偏光板と比べて、正面および斜めから視認した際の表示ムラが少ないという優れた結果となった。以上の結果から、本発明の製造方法によれば、優れた偏光フィルムが製造できるため、表示ムラが抑制された各種画像表示装置を得ることができる。

As is clear from Table 1, the polarizing plates of Examples 1 to 9 have excellent results that display unevenness is less when viewed from the front and obliquely than the polarizing plates of Comparative Examples 1 to 3 and 5. Was. From the above results, according to the manufacturing method of the present invention, since an excellent polarizing film can be manufactured, various image display devices in which display unevenness is suppressed can be obtained.

As described above, if the polarizer obtained by the production method of the present invention is used for a liquid crystal panel or a liquid crystal display device as an optical film such as a polarizing plate, there is no display unevenness and excellent display characteristics. Can be achieved. Further, according to the present invention, since the polarizer, the polarizing plate, and the like can be marked by in-line measurement, for example, an off-line process such as an appearance inspection or packing immediately after the polarizer is chip-cut becomes unnecessary, and a liquid crystal display device or the like is consistently provided. In-house manufacturing for bonding to an EL display device becomes possible. Thus, for example, the cost of the display device can be reduced, and the manufacturing process can be easily managed, so that the industrial value is great.

It is a schematic diagram showing an example of a swelling process in a manufacturing method of an optical film of the present invention. It is the schematic which shows the other example of the swelling process in the manufacturing method of the optical film of this invention. It is the schematic which shows the example of the guide roll used for the manufacturing method of this invention. FIG. 2 is a cross-sectional view illustrating an example of the optical film of the present invention. It is sectional drawing which shows the other example of the optical film of this invention. It is sectional drawing which shows the example of the liquid crystal panel of this invention. It is sectional drawing which shows the other example of the liquid crystal panel of this invention. (A) is a sectional view showing still another example of the liquid crystal panel of the present invention, and (B) and (C) are partial sectional views of the above (A). FIG. 2 is a cross-sectional view illustrating an example of a backlight according to the embodiment of the present invention. FIG. 9 is a cross-sectional view of another example of the backlight in the embodiment of the present invention. It is sectional drawing of the further another example of the backlight in the said Example. (A) is a sectional view of still another example of the backlight in the embodiment, and (B) is a partial schematic view of (A).

Explanation of reference numerals

REFERENCE SIGNS LIST 1 polarizing film 2 transparent protective layer 3 pressure-sensitive adhesive layer 10, 11, 20 polarizing plate 12 liquid crystal cell 13 retardation plate 14 polarization conversion element 15 quarter-wave plate 16 cholesteric liquid crystal layer 17 anisotropic multiple thin-film reflective polarizing element 21 Diffusion plate 22 Light guide plate 23 Reflector plate 24 Prism sheet 25 Light guide plate with prism 31 Hydrophilic polymer film 32 Swelling bath 33 Aqueous solvent 41, 42, 43, 44, 45 Guide roll

Claims (30)

A hydrophilic polymer film is immersed in an aqueous solvent in a swelling bath by being conveyed by a guide roll, and a swelling step of swelling the polymer film, a dyeing step of dyeing the polymer film with a dichroic substance, and stretching the polymer film A method for producing a polarizing film comprising a stretching step of:
In the swelling step, at least a first guide roll is arranged in the swelling bath,
The polymer film is immersed in the aqueous solvent, and, when moving in the aqueous solvent, the polymer film is brought into contact with the first guide roll until swelling is saturated. Manufacturing method. A second guide roll is further arranged in the swelling bath,
The method according to claim 1, wherein the polymer film is brought into contact with the first guide roll until the swelling becomes saturated, and further contacted with the second guide roll after the swelling becomes saturated. 3. The method according to claim 1, wherein a required time (a) from when the polymer film comes into contact with the aqueous solvent to when the polymer film comes into contact with the first guide roll is 0.6 to 12 seconds. 4. 4. The method according to claim 2, wherein a required time (b) from when the polymer film contacts the first guide roll to when the polymer film contacts the second guide roll is 13 to 120 seconds. 5. The manufacturing method according to claim 4, wherein a total of the required time (a) and the required time (b) is in a range of 25 to 180 seconds. A hydrophilic polymer film is immersed in a swelling bath of an aqueous solvent by being conveyed by a guide roll, a swelling step of swelling the polymer film in the solvent, a dyeing step of dyeing the polymer film with a dichroic substance, A method for producing a polarizing film including a stretching step of stretching the film,
In the swelling step, at least a first guide roll is arranged in the swelling bath,
The polymer film is immersed in the aqueous solvent, and, when moving in the aqueous solvent, the polymer film is brought into contact with the first guide roll after the swelling is saturated. Manufacturing method. 7. The method according to claim 6, wherein a required time (c) from the contact of the polymer film with the aqueous solvent to the contact with the first guide roll is 25 to 180 seconds. The method according to any one of claims 1 to 7, wherein a time for immersing the polymer film in the swelling bath is 100 seconds or more. The method according to any one of claims 1 to 8, wherein the thickness of the hydrophilic polymer film before the swelling treatment is 110 µm or less. The method according to any one of claims 1 to 9, wherein the hydrophilic polymer film is a polyvinyl alcohol-based film. The method according to any one of claims 1 to 10, wherein the hydrophilic polymer film contains 1 to 17% by weight of a plastic material. The method according to any one of claims 1 to 11, wherein the guide roll is at least one kind of roll selected from a crown roll, a vent roll, and an ear height roll. The manufacturing method according to any one of claims 1 to 12, wherein the guide rolls other than the first guide roll include a spiral roll. The method according to any one of claims 1 to 13, wherein the temperature of the swelling bath is in a range of 15 to 50 ° C. The method according to any one of claims 1 to 14, wherein in the swelling step, the polymer film is further subjected to a stretching treatment in the swelling bath. The production method according to any one of claims 1 to 15, wherein a stretching magnification in the stretching treatment is in a range of 1.5 to 4.0 times the length of the polymer film before being subjected to a swelling step. . The method according to any one of claims 1 to 16, wherein the dichroic substance is at least one of iodine and an organic dye. The method according to claim 17, wherein the dichroic substance is two or more kinds of organic dyes. A polarizing film obtained by the production method according to claim 1. An optical film comprising the polarizing film according to claim 19. The optical film according to claim 20, further comprising a transparent protective layer, wherein the transparent protective layer is disposed on at least one surface of the polarizer. 22. The polarizing plate according to claim 20, wherein an adhesive layer is disposed on at least one outermost layer. The optical film according to any one of claims 20 to 22, further comprising at least one of a polarization conversion element and a retardation film. The optical film according to claim 23, wherein the polarization conversion element is an anisotropic reflection-type polarization element or an anisotropic scattering-type polarization element. A liquid crystal panel, wherein at least one of the polarizing film according to claim 19 and the optical film according to any one of claims 20 to 24 is disposed on at least one surface of a liquid crystal cell. A liquid crystal display device comprising the liquid crystal panel according to claim 25. The liquid crystal display device according to claim 26, further comprising a plane light source that emits polarized light. An image display device comprising at least one of the polarizing film according to claim 19 and the optical film according to any one of claims 20 to 24. 29. The image display device according to claim 28, which is an electroluminescence display device. An in-house manufacturing method for an image display device according to claim 28, wherein at least one of the polarizing film according to claim 19 and the optical film according to any one of claims 20 to 24 is cut immediately after chip cutting. And an in-house manufacturing method including a step of bonding to the display device.

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