JP2008224826A - Method for manufacturing polarizer, polarizer, polarizing plate, optical film and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a polarizer capable of manufacturing the polarizer with the deterioration in the optical characteristics suppressed, even when a hydrophilic polymer film is extended in the width direction by a tenter system, and the like. <P>SOLUTION: In the method for manufacturing the polarizer having a width direction extension process for extending the hydrophilic polymer film 1 in the width direction, by holding both ends of the film 1 in the width direction by a holding means 2, progressing the holding means 2 in the longitudinal direction of the film 1 and transferring both of the holding means 2 for holding both ends of the film 1 also to the outside of the width direction of the film 1 and a dyeing process for dyeing the film 1 by a dichroism substance, contraction of the film 1 in the width direction is suppressed, by releasing the film 1 from the holding means 2 at a releasing position X, transferring the film 1 from the releasing position X to a fixed position Y, and fixing both ends of the film 1 in the width direction by the holding means 2 at the fixed position Y, to restrict the transfer to the inside of the width direction after the width direction extension process. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a polarizer, a polarizer, a polarizing plate, an optical film, and an image display device.

  Polarizers are used in various liquid crystal display devices (LCD) such as televisions, personal computers, and mobile phones. In the LCD, polarizers are arranged on the front and back of a liquid crystal cell so that absorption axes (vibration directions of light that cause absorption) are orthogonal to each other. Usually, the said polarizer is produced by dyeing a polyvinyl alcohol (PVA) film with a dichroic substance, and uniaxially stretching the said PVA film to a longitudinal direction (for example, refer patent document 1). When the PVA film is uniaxially stretched, the dichroic material adsorbed (stained) on the PVA molecules is oriented, so that a polarizer is obtained. In this case, the absorption axis of the polarizer appears in the longitudinal direction.

The polarizer is cut into a predetermined size, and by using a combination of the longitudinal direction and the width direction orthogonal thereto, the orthogonal relationship between the absorption axes on the front and back sides of the liquid crystal cell is achieved. Therefore, in the LCD, the polarizer is used in a relationship rotated by 90 degrees. Here, when obtaining the polarizer of the same size applied to the front and back of the liquid crystal cell, the upper limit of the size of the polarizer is the length in the width direction. In a conventional method for producing a polarizer in which a PVA film is uniaxially stretched in the longitudinal direction, shrinkage occurs in the width direction when the PVA film is stretched. For this reason, the polarizer obtained by the conventional manufacturing method has a limit in the length in the width direction, and there is a problem that it is not possible to meet the demand for an increase in the size of the polarizer in accordance with the enlargement of the LCD screen.
JP 2001-305347 A

  It can be considered that the size of the polarizer is increased by uniaxially stretching the PVA film in the width direction. Examples of means for uniaxially stretching the PVA film in the width direction include a tenter method. However, when the PVA film is stretched uniaxially in the width direction by the tenter method, after the PVA film is released from the tenter clip, shrinkage occurs in the width direction (stretching direction) of the PVA film, and the obtained polarizer is There is a problem that the axiality is strongly expressed and the optical characteristics thereof are deteriorated.

  Accordingly, an object of the present invention is to provide a method for producing a polarizer capable of producing a polarizer in which deterioration of optical properties is suppressed even when a hydrophilic polymer film is stretched in the width direction by a tenter method or the like. .

In order to achieve the above object, the method for producing a polarizer of the present invention comprises:
The both ends of the hydrophilic polymer film that is continuously supplied are gripped by the gripping means, the gripping means is advanced in the longitudinal direction of the hydrophilic polymer film, and the both ends of the hydrophilic polymer film are gripped. A width direction stretching step of stretching the hydrophilic polymer film in the width direction by moving at least one of the gripping means to the outside in the width direction of the hydrophilic polymer film;
A dyeing step of dyeing the hydrophilic polymer film with a dichroic substance,
The method for producing a polarizer, wherein the width direction stretching step is carried out in at least one step different from the dyeing step and the dyeing step,
Furthermore, after the width direction stretching step, an opening step of releasing the hydrophilic polymer film from the gripping means at an open position;
The hydrophilic polymer film is moved from the open position to a fixed position, and both ends in the width direction of the hydrophilic polymer film are fixed by the width direction both-end fixing means at the fixed position to restrict movement inward in the width direction. It has the width direction both ends fixing process which suppresses the shrinkage | contraction of the width direction of the said hydrophilic polymer film.

  The polarizer of the present invention is a polarizer manufactured by the method for manufacturing a polarizer of the present invention.

  The polarizing plate of the present invention is a polarizing plate in which a protective layer is laminated on at least one surface of a polarizer, and the polarizer is the polarizer of the present invention.

  The optical film of the present invention is an optical film in which a retardation plate is laminated on at least one surface of a polarizer or a polarizing plate, wherein the polarizer is the polarizer of the present invention, and the polarizing plate is It is the polarizing plate of the present invention.

  The image display device of the present invention is an image display device including at least one of a polarizer, a polarizing plate and an optical film, wherein the polarizer is the polarizer of the present invention, and the polarizing plate is the book. The polarizing plate of the invention is characterized in that the optical film is the optical film of the invention.

  In the manufacturing method of the polarizer of this invention, after releasing a hydrophilic polymer film from a holding means, the width direction both-ends fixing process is implemented, and the shrinkage | contraction of the width direction of the said hydrophilic polymer film is suppressed in the process. As a result, in the polarizer obtained by the production method of the present invention, the expression of biaxiality is small and the deterioration of optical properties is suppressed. The production method of the present invention is preferably used for the production of a large polarizer, but is not limited thereto, and can be applied to the production of polarizers of various sizes. The problem of shrinkage in the width direction of the hydrophilic polymer film was first discovered by the present inventors. According to the present invention, the problem of shrinkage in the width direction of the hydrophilic polymer film is solved.

  In the present invention, the optical characteristics include, for example, dichroic ratio, single transmittance, polarization degree, and the like.

  In the manufacturing method of the present invention, the width direction both-end fixing means may be a gripping means for gripping both ends in the width direction of the hydrophilic polymer film, for example.

  In the production method of the present invention, the width direction both-end fixing means may be, for example, roll pinching means for pinching the hydrophilic polymer film with two rolls from the vertical direction.

In the manufacturing method of the present invention, in the opening step and the width direction both-end fixing step, the width (W ₁ ) of the hydrophilic polymer film in the opening position in the width direction, and from the opening position to the fixing position. The ratio (L / W ₁ ) to the distance (L) is preferably 0.2 or less.

In the production method of the present invention, in the opening step and the width direction both-end fixing step, the hydrophilic polymer film has a length (W ₁ ) in the width direction of the hydrophilic polymer film at the open position, and the hydrophilic polymer at the fixed position. It is preferable that the width residual ratio (W ₂ / W ₁ ), which is a ratio with the length (W ₂ ) in the width direction of the film, is 0.92 or more.

  The production method of the present invention preferably further includes a drying step of drying the hydrophilic polymer film, and the drying step is preferably performed at least after the width direction both-end fixing step.

  In the production method of the present invention, the opening step is omitted, and the width direction both-end fixing step is continued after the width direction stretching process in the width direction stretching step is finished, and the gripping means continues to grip the film width direction both ends. You may implement by moving to the said drying process, keeping the length of the width direction of the said film constant.

In the production method of the present invention, when the length in the width direction of the hydrophilic polymer film immediately before the drying step is W ₃ , and the length in the width direction of the hydrophilic polymer film after the drying step is W ₄ , It is preferable to satisfy the relationship of the following formula (1).

{−0.66 × (L × W ₁ ) +1.05} × (W ₄ / W ₃ ) ≧ 0.92 (1)
W ₁ : Length in the width direction of the hydrophilic polymer film at the open position (mm)
L: Distance from the open position to the fixed position (mm)
W ₃ : Length in the width direction of the hydrophilic polymer film immediately before the drying step (mm)
W ₄ : Length in the width direction of the hydrophilic polymer film after the drying step (mm)

  In the production method of the present invention, the other steps include, for example, a swelling step for swelling the hydrophilic polymer film, and a crosslinking step for crosslinking the hydrophilic polymer film.

  In the production method of the present invention, the liquid is brought into contact with at least one surface of the hydrophilic polymer film in the gas phase in at least one of the swelling step, the dyeing step, the cross-linking step, and the width direction stretching step. It is preferable to make it. In this case, the contact of the liquid is preferably performed by at least one of spraying and applying the liquid.

  In the present invention, the liquid includes, for example, a swelling liquid, a dyeing liquid, a cross-linking liquid, a stretching liquid, and an adjusting liquid described later.

  In the method for producing a polarizer of the present invention, the hydrophilic polymer film is preferably a polyvinyl alcohol film, and the dichroic substance is preferably iodine.

  Next, an example is given and the manufacturing method of the polarizer of this invention is demonstrated below. The production method of the present invention uses a hydrophilic polymer film as a material and has, for example, a series of steps such as a swelling step, a dyeing step, a crosslinking step, an adjustment step, a drying step, etc., and at least one of these steps or separately The width direction stretching step is performed, and after the width direction stretching step, the opening step and the width direction both-end fixing step are performed.

(1) Hydrophilic polymer film The hydrophilic polymer film is not particularly limited, and a conventionally known film can be used. Specifically, for example, hydrophilic polymers such as polyvinyl alcohol (PVA) film, partially formalized PVA film, polyethylene terephthalate (PET) film, ethylene / vinyl acetate copolymer film, and partially saponified films thereof. A film etc. are mentioned. In addition to these, polyene oriented films such as PVA dehydrated products and polyvinyl chloride dehydrochlorinated products, stretched and oriented polyvinylene films, and the like can also be used. Among these, since it is excellent in the dyeability by the iodine which is a dichroic substance mentioned later, a PVA-type polymer film is preferable.

  As a raw material polymer of the PVA polymer film, for example, saponified after polymerizing vinyl acetate, or a small amount of a copolymerizable monomer such as unsaturated carboxylic acid or unsaturated sulfonic acid with respect to vinyl acetate. Examples thereof include a copolymerized polymer. The polymerization degree of the PVA polymer is not particularly limited, but is preferably in the range of 500 to 10,000, more preferably in the range of 1000 to 6000, from the viewpoint of solubility in water. The saponification degree of the PVA polymer is preferably 75 mol% or more, more preferably in the range of 98 to 100 mol%.

  The hydrophilic polymer film (for example, PVA film) is preferably in the form of a raw film wound on a roll. The thickness of the hydrophilic polymer film (for example, PVA film) is not particularly limited, but is, for example, in the range of 15 to 110 μm, preferably in the range of 38 to 110 μm, and more preferably in the range of 50 to 100 μm. It is a range, More preferably, it is the range of 60-80 micrometers.

(2) Width Direction Stretching Step First, the width direction stretching step for stretching in the film width direction will be described. In addition, it is common to manufacture a polarizer in order of a swelling process, a dyeing process, a bridge | crosslinking process, an adjustment process, and a drying process, for example. As described above, the width direction stretching step may be performed in each of these steps, or may be performed separately. FIG. 1 schematically shows an example of this process. As shown in the figure, in this step, the both ends of the hydrophilic polymer film 1 that is continuously supplied are gripped by the gripping means 2 in the width direction (left-right direction in the figure). Then, as indicated by an arrow A, the gripping means 2 is advanced in the longitudinal direction of the hydrophilic polymer film 1 (upward in the figure). Thereby, as the arrow B shows, the said hydrophilic polymer film 1 is conveyed in the longitudinal direction (upward direction in the figure). At the same time, as indicated by an arrow C, both the gripping means 2 that grips both ends of the hydrophilic polymer film 1 are also moved in the width direction of the hydrophilic polymer film 1, thereby the hydrophilic polymer film 1. Is stretched in the width direction. FIG. 1 shows that the hydrophilic polymer film 1 is moved in the width direction by moving both of the gripping means 2 that grip both ends of the hydrophilic polymer film 1 to the outside in the width direction of the hydrophilic polymer film 1. The case of extending | stretching is shown. However, the present invention is not limited to this, and by moving only one of the gripping means 2 that grips both ends of the hydrophilic polymer film 1 to the outside in the width direction of the hydrophilic polymer film 1. The hydrophilic polymer film 1 may be stretched in the width direction.

  A state in which the hydrophilic polymer film 1 is gripped by the gripping means 2 is shown in FIG. As shown in FIG. 2A, the gripping means 2 includes a rotating shaft 21, an upper gripping portion 22, and a lower gripping portion 23. The upper gripping portion 22 can be moved to the inside (left side in the figure) of the gripping means 2 by the rotating shaft 21. In this state, as shown in FIG. 2 (B), one end in the width direction of the hydrophilic polymer film 1 is placed on the lower gripping portion 23, and the upper gripping portion 22 is placed on the upper surface of the hydrophilic polymer film 1. The hydrophilic polymer film 1 is gripped by moving it to the outside of the gripping means 2 (on the right side in the figure) until it comes into contact.

  FIG. 3 is an enlarged view of a part of FIG. The length (a) in the figure where the hydrophilic polymer film 1 is gripped by the gripping means 2 is not particularly limited, but is, for example, in the range of 10 to 100 mm, preferably 10 It is in the range of ˜75 mm, more preferably in the range of 25 to 75 mm, and the width of the grip (b in the figure) is not particularly limited, but is in the range of, for example, 5 to 50 mm, preferably It is the range of 10-30 mm, More preferably, it is the range of 10-20 mm. The distance between the gripping means 2 adjacent in the longitudinal direction of the hydrophilic polymer film 1 (c in the figure) is preferably as short as possible, but is, for example, in the range of 1 to 20 mm, preferably 3 to It is the range of 10 mm, More preferably, it is the range of 3-6 mm.

  As described above, in this step, it is preferable that at least one surface of the hydrophilic polymer film is brought into contact with the liquid in the gas phase. The contact of the liquid is preferably carried out by at least one of spraying and applying the liquid.

  Any appropriate spraying device is used as means for spraying the liquid onto the hydrophilic polymer film. Examples of the spraying device include a product name “MK series” manufactured by Fuso Seiki Co., Ltd., a product name “T-AFPV” manufactured by DeVILBISS, and a product name “56 series” manufactured by ACCUSPLAY. In the spray device, the number of spray nozzles is, for example, in the range of 1 to 10, preferably in the range of 1 to 8, more preferably in the range of 1 to 4, and the spray. The nozzle diameter of the nozzle is, for example, in the range of 0.3 to 2 mm, preferably in the range of 0.5 to 1.5 mm, more preferably in the range of 0.75 to 1 mm. The flow rate per nozzle is, for example, in the range of 10 to 1200 mL / second, preferably in the range of 10 to 700 mL / second, more preferably in the range of 50 to 400 mL / second, and the atomizing air pressure. Is, for example, in the range of 0.03 to 3 MPa, preferably in the range of 0.1 to 1 MPa, more preferably in the range of 0.2 to 0.5 MPa, and the spray angle is, for example, 45 In the range of ° to 135 ° Preferably, it is the range of 60 degrees-120 degrees, More preferably, it is the range of 80 degrees-100 degrees.

  In spraying the liquid, the distance between the spraying nozzle of the spraying device and the hydrophilic polymer film can be appropriately determined according to the spraying air pressure or the like, but is preferably in the range of 15 cm or less. By setting the distance within the above range, the liquid can be reliably brought into contact with the hydrophilic polymer film without loss.

The time for spraying the liquid is not particularly limited, but is preferably in the range of 20 seconds or more, more preferably in the range of 30 to 120 seconds, and still more preferably in the range of 40 to 60 seconds. Moreover, the spray amount of the liquid onto the hydrophilic polymer film is not particularly limited, but is preferably in the range of 0.06 to 0.19 mL / 1 cm ² . And although the temperature of the said liquid is not restrict | limited in particular, For example, it is the range of 40-70 degreeC, Preferably, it is the range of 50-70 degreeC, More preferably, it is the range of 60-70 degreeC.

  As means for applying the liquid to the hydrophilic polymer film, conventionally known means such as a roll coater, a die coater, a bar coater, a slide coater, and a curtain coater can be used. In the contact of the liquid, spraying and application of the liquid may be used in combination.

  The stretching process in the width direction of the hydrophilic polymer film can be performed using, for example, a conventionally known tenter stretching machine, hand stretching machine, or the like. The total draw ratio of the hydrophilic polymer film in this width direction drawing step is, for example, in the range of 2 to 12 times, for example, 3 to 12 times the length of the film (raw fabric) before stretching, The range is 10 times, and more preferably 4 to 8 times.

  As described above, the width direction stretching step may be performed in each step such as a swelling step, a dyeing step, a crosslinking step, and an adjustment step, or may be performed independently. When the width direction stretching step is performed separately and independently, for example, the hydrophilic polymer film is stretched while being in contact with a stretching solution.

  Although it does not restrict | limit especially as said extending | stretching liquid, For example, the solution containing a boric acid, potassium iodide, various metal salts, other iodide compounds, a zinc compound, etc. can be used. As a solvent of this solution, for example, water, ethanol or the like can be used. Specifically, for example, it is preferable to contain boric acid and potassium iodide, and the content of both is, for example, in the range of 2 to 18% by weight in total, preferably 4 to 17% by weight in total. More preferably, the total content is in the range of 6 to 15% by weight. The content ratio (A: B (weight ratio)) of the boric acid (A) and potassium iodide (B) is, for example, in the range of 1: 0.1 to 1: 4, preferably 1 : 0.2 to 1: 3.5, and more preferably 1: 0.5 to 1: 3.

(3) Opening step and width direction both-end fixing step After the width direction stretching step, the hydrophilic polymer film is released from the gripping means at the opening position. Next, the hydrophilic polymer film is moved from the open position to the fixed position, and both ends in the width direction of the hydrophilic polymer film are fixed at the fixed position by the width direction both ends fixing means to restrict the movement inward in the width direction. To do. Thereby, the shrinkage | contraction of the width direction of the said hydrophilic polymer film is suppressed. When the hydrophilic polymer film is released from the gripping means after the width direction stretching step, the hydrophilic polymer film contracts in the width direction as it is. The production method of the present invention is characterized in that the shrinkage in the width direction of the hydrophilic polymer film is suppressed, thereby suppressing a decrease in optical properties of the obtained polarizer.

  FIG. 4 schematically shows an example of this process. In this example, the width direction fixing means is a gripping means for gripping both ends of the hydrophilic polymer film. In addition, in the same figure, unlike FIG. 1, the left-right direction is made into the longitudinal direction of the said hydrophilic polymer film, and the up-down direction is made into the width direction of the said hydrophilic polymer film for convenience. As shown in the drawing, after the width direction stretching step, first, the hydrophilic polymer film 1 is released from the gripping means 2 at the opening position X. Next, the hydrophilic polymer film 1 is moved from the open position X to the fixed position Y (arrow A), and the both ends of the hydrophilic polymer film 1 in the width direction are gripped by the second gripping means 2 at the fixed position Y. To do. Thereby, the movement to the inner side in the width direction of the hydrophilic polymer film 1 is limited. As the second gripping means 2, the gripping means used in the width direction stretching step may be used again. Further, the second gripping means 2 may be a gripping means different from that used in the width direction stretching step.

The width W ₁ in the width direction of the hydrophilic polymer film 1 at the open position X is not particularly limited, but is, for example, in the range of 1500 to 3000 mm, preferably in the range of 1800 to 2500 mm, more preferably. Is in the range of 2000-2200 mm. The distance L from the open position X to the fixed position Y is preferably as short as possible, for example, in the range of 100 to 500 mm, preferably in the range of 100 to 300 mm, and more preferably in the range of 100 to 200 mm. It is a range. Here, as described above, the L / W ₁ is preferably 0.2 or less. By setting the L / W ₁ to 0.2 or less, the shrinkage in the width direction of the hydrophilic polymer film 1 can be more suitably suppressed. The L / W ₁ is more preferably in the range of 0.03 to 0.15, and still more preferably in the range of 0.03 to 0.1.

The width direction of the length _{W 2} of the hydrophilic polymer film 1 in a fixed position Y is, for example, in the range of 1425～2850Mm, preferably in the range of 1710～2375Mm, more preferably, 1900～2090Mm Range. Further, as described above, the width remaining ratio (W ₂ / W ₁ ) is preferably 0.92 or more. With the width remaining rate (W 2 _{/ W 1)} 0.92 or more, the deterioration of the optical properties of the polarizer obtained photons, can be more appropriately suppressed. The width remaining ratio (W ₂ / W ₁ ) is more preferably in the range of 0.93 to 0.98, and still more preferably in the range of 0.95 to 0.98.

  FIG. 5 schematically shows another example of this process. In this example, the width direction fixing means is a roll pinch means, and at the fixing position Y, the hydrophilic polymer film 1 is pinched (sandwiched) with two rolls 3 from the vertical direction thereof. The movement of the hydrophilic polymer film 1 in the width direction is restricted. The larger the diameter of the roll 3, the better. As long as the diameter of the roll 3 is large, both ends of the hydrophilic polymer film 1 can be held by the holding means 2 to a position closer to the roll 3 (from the open position X to the fixed position Y). This is because the distance L can be made shorter. That is, if the diameter of the roll 3 is increased, the central axis of the roll 3 can be further away from the surface of the hydrophilic polymer film 1. As a result, the gripping means 2 and the roll 3 are prevented from colliding without removing the gripping means 2 from the surface (both ends in the width direction) of the hydrophilic polymer film 1 to a position closer to the roll 3. be able to. The diameter of the roll 3 is, for example, in the range of 200 to 500 mm, preferably in the range of 300 to 400 mm, and more preferably in the range of 300 to 350 mm.

  In the production method of the present invention, the opening step can be omitted. In this case, after completion of the width direction stretching process in the width direction stretching step, the gripping means continues to grip both ends in the film width direction in the width direction both-end fixing step. Thereby, the said width direction both ends fixing process is implemented, keeping the length of the width direction of the said film constant. Thereafter, in the state as it is, the process proceeds to a drying step described later. Also by doing in this way, the movement of the hydrophilic polymer film to the inner side in the width direction can be restricted, and the shrinkage in the width direction can be suppressed.

(4) Swelling step First, the hydrophilic polymer film is swollen by contacting with a swelling liquid.

  As said swelling liquid, water, glycerol aqueous solution, potassium iodide aqueous solution etc. can be used, for example.

  In this step, the means and conditions for bringing the swelling liquid into contact with the hydrophilic polymer film when the width direction stretching step is performed are as described in the width direction stretching step.

  In this step, when the width direction stretching step is not performed (for example, non-stretching treatment, the same applies hereinafter), the swelling liquid is contacted by, for example, immersing the hydrophilic polymer film in the swelling liquid. It may be broken. In this case, a swelling bath is used. The immersion time of the hydrophilic polymer film in the swelling liquid (swelling bath) in this case is not particularly limited, but is, for example, in the range of 20 to 300 seconds, preferably in the range of 30 to 200 seconds, More preferably, it is in the range of 30 to 120 seconds, and the temperature of the swelling liquid (swelling bath) is, for example, in the range of 20 to 45 ° C, preferably in the range of 25 to 40 ° C, more preferably. 27 to 37 ° C.

(5) Dyeing process Next, the hydrophilic polymer film after swelling is brought into contact with a dyeing solution containing a dichroic substance.

  A conventionally known substance can be used as the dichroic substance, and examples thereof include iodine and organic dyes. When using the said organic dye, it is preferable to combine 2 or more types from the point which aims at neutralization of the visible region, for example.

  As the staining solution, a 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. Although the density | concentration of the dichroic substance in the said solution is not restrict | limited in particular, For example, it is the range of 0.005-0.40 weight%, Preferably, it is the range of 0.01-0.30 weight%.

  In addition, when iodine is used as the dichroic substance, it is preferable to further add iodide as an auxiliary agent in addition to iodine because solubility and dyeing efficiency can be further improved. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and iodide. Examples include titanium. The addition ratio of these iodides is preferably in the range of 0.05 to 10% by weight, and more preferably in the range of 0.10 to 5% by weight in the dyeing solution.

  For example, when iodine and potassium iodide are used in combination, the ratio (A: B (weight ratio)) of iodine (A) and potassium iodide (B) in the solution is, for example, 1: 5 to 1: The range is 100, preferably 1: 7 to 1:50, and more preferably 1:10 to 1:30.

  In this step, the means and conditions for bringing the dyeing liquid into contact with the hydrophilic polymer film when the width direction stretching step is performed are as described in the width direction stretching step.

  In this step, when the width direction stretching step is not performed, the contact with the staining solution may be performed, for example, by immersing the hydrophilic polymer film in the staining solution. In this case, a dyeing bath is used. The immersion time of the hydrophilic polymer film in the dyeing liquid (dyeing bath) in this case is not particularly limited, but is, for example, in the range of 10 to 90 seconds, preferably in the range of 15 to 60 seconds, More preferably, it is in the range of 20 to 45 seconds, and the temperature of the dyeing solution (dyeing bath) is, for example, in the range of 5 to 42 ° C, preferably in the range of 10 to 35 ° C, more preferably. , In the range of 12-30 ° C.

(6) Crosslinking step Next, the hydrophilic polymer film after the dyeing treatment is brought into contact with a crosslinking solution containing a crosslinking agent.

  A conventionally known substance can be used as the crosslinking agent, and examples thereof include boron compounds such as boric acid and borax. These may be used alone or in combination of two or more. As the crosslinking liquid, a solution in which the crosslinking agent 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 included.

  The concentration of the crosslinking agent in the solution is not particularly limited, but is preferably in the range of 0.1 to 10 parts by weight, more preferably 1.5 to 100 parts by weight with respect to 100 parts by weight of the solvent (for example, water). It is the range of 8 weight part, More preferably, it is the range of 2-6 weight part.

  In addition to the boron compound, for example, potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, iodine, and the like can be used for the cross-linking liquid in view of obtaining uniform characteristics in the plane of the polarizer. An assistant such as iodide such as lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide and titanium iodide may be included. Among these, a combination of boric acid and potassium iodide is preferable. The content of the auxiliary agent in the solution is, for example, in the range of 0.05 to 15% by weight, and preferably in the range of 0.5 to 8% by weight.

  In this step, the means and conditions for bringing the crosslinking liquid into contact with the hydrophilic polymer film when the width direction stretching step is performed are as described in the width direction stretching step.

  In this step, when the width direction stretching step is not performed, the cross-linking liquid may be contacted by, for example, immersing the hydrophilic polymer film in the cross-linking liquid. In this case, a crosslinking bath is used. The immersion time of the hydrophilic polymer film in the crosslinking liquid (crosslinking bath) in this case is not particularly limited, but is, for example, in the range of 5 to 150 seconds, preferably in the range of 10 to 90 seconds, More preferably, it is the range of 20-40 seconds, and the temperature of the said crosslinking liquid (crosslinking bath) is the range of 20-70 degreeC, for example, Preferably, it is the range of 40-60 degreeC.

(7) Preparation / Drying Step Finally, the hydrophilic polymer film is brought into contact with an iodide-containing aqueous solution (conditioning solution) and then dried to obtain the polarizer of the present invention.

  As the iodide in the iodide-containing aqueous solution, those described above can be used, and among them, for example, potassium iodide and sodium iodide are preferable. With this iodide-containing aqueous solution, the remaining boric acid used in the widthwise stretching step can be washed away from the hydrophilic polymer film.

  When the aqueous solution is an aqueous potassium iodide solution, the concentration thereof is, for example, in the range of 0.5 to 20% by weight, preferably in the range of 1 to 15% by weight, more preferably 1.5 to It is in the range of 7% by weight.

  In this step, the means and conditions for bringing the adjustment liquid into contact with the hydrophilic polymer film when the width direction stretching step is performed are as described in the width direction stretching step.

  In this step, when the width direction stretching step is not performed, the contact with the adjustment liquid may be performed, for example, by immersing the hydrophilic polymer film in the adjustment liquid. In this case, a conditioning bath is used. The immersion time of the hydrophilic polymer film in the adjustment liquid (conditioning bath) in this case is not particularly limited, but is, for example, in the range of 2 to 15 seconds, preferably in the range of 3 to 12 seconds, The temperature of the adjusting liquid (adjusting bath) is, for example, in the range of 15 to 40 ° C, and preferably in the range of 20 to 35 ° C.

  The drying may be performed by a conventionally known method such as natural drying, air drying, and heat drying. In the case of heat drying, although it does not restrict | limit, the range of temperature 25-60 degreeC is preferable, More preferably, it is the range of 30-50 degreeC, More preferably, it is the range of 30-45 degreeC.

  As described above, in the production method of the present invention, it is preferable to carry out this drying step at least after fixing both ends in the width direction. This drying process will be described by taking the case shown in FIG. 5 as an example. In this example, the drying step D is performed immediately after restricting the movement of the hydrophilic polymer film 1 in the width direction at the fixed position Y. Moreover, in this example, the drying process D is implemented, conveying the said hydrophilic polymer film 1 in the longitudinal direction (the right direction in the figure) using the three conveyance rolls 4. FIG.

The length W ₃ in the width direction of the hydrophilic polymer film 1 immediately before the drying step D is, for example, in the range of 1425 to 2850 mm, preferably in the range of 1710 to 2375 mm, and more preferably 1900 to 2090 mm. Range. As described above, in this example, since the drying step D is performed immediately after restricting the movement of the hydrophilic polymer film 1 in the width direction at the fixed position Y, the W ₃ is fixed at the fixed position Y. This is the same as the length W ₂ in the width direction of the hydrophilic polymer film 1 in FIG. The width W ₄ in the width direction of the hydrophilic polymer film after the drying step D is, for example, in the range of 1380-2760 mm, preferably in the range of 1656-2300 mm, and more preferably in the range of 1840-2024 mm. It is a range. Moreover, in the manufacturing method of this invention, it is preferable to satisfy | fill the relationship of following formula (1) as above-mentioned. By satisfy | filling the relationship of following formula (1), the fall of the optical characteristic of the polarizer obtained can be suppressed more suitably.

{−0.66 × (L / W ₁ ) +1.05} × (W ₄ / W ₃ ) ≧ 0.92 (1)
W ₁ : Length in the width direction of the hydrophilic polymer film at the open position (mm)
L: Distance from the open position to the fixed position (mm)
W ₃ : Length in the width direction of the hydrophilic polymer film immediately before the drying step (mm)
W ₄ : Length in the width direction of the hydrophilic polymer film after the drying step (mm)

When α = {− 0.66 × (L / W ₁ ) +1.05} × (W ₄ / W ₃ ), α is more preferably in the range of 0.93 to 0.98. Yes, and more preferably in the range of 0.95 to 0.98.

  The swelling process, the dyeing process, the crosslinking process, the width direction stretching process, the opening process, the width direction both-end fixing process, and the adjustment / drying process have been described above. These steps may be performed separately, but the steps that can be combined into one step may be performed collectively. Moreover, you may implement an adjustment and a drying process after completion | finish of each process.

  A polarizer can be manufactured through such a series of steps. The polarizer is usually used after being cut into a predetermined size.

(8) Polarizer The thickness of the polarizer of the present invention is not particularly limited, but is, for example, in the range of 5 to 40 μm, preferably in the range of 10 to 37 μm, and more preferably in the range of 15 to 35 μm. is there.

(9) Polarizing plate Next, the polarizing plate of the present invention has a configuration in which a protective layer is laminated on at least one surface of the polarizer of the present invention. The protective layer may be laminated only on one side of the polarizer or may be laminated on both sides. When laminating on both surfaces, for example, the same type of protective layer may be used, or different types of protective layers may be used.

  In FIG. 6, sectional drawing of an example of the polarizing plate of this invention is shown. As shown in the figure, the polarizing plate 60 has protective layers 62 laminated on both surfaces of the polarizer 61.

  The protective layer 62 is not particularly limited, and a conventionally known protective film can be used. For example, a protective layer having excellent transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, and the like is preferable. Specific examples of the material of such a protective layer include cellulose resins such as triacetylcellulose (TAC), polyester-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, polysulfone-based, polystyrene-based, Examples thereof include acrylic resins, acetate resins, polyolefin resins, and the like. Further, examples thereof include thermosetting resins such as acrylic, urethane, acrylic urethane, epoxy, and silicone, or ultraviolet curable resins.

  In addition to this, as described in JP-A No. 2001-343529 and WO 01/37007, for example, an alternating copolymer composed of isobutene and N-methylmaleimide, an acrylonitrile / styrene copolymer, A film made of a mixed extrudate of a resin composition containing bismuth can be used.

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

  The thickness of the protective layer can be determined as appropriate, but is, for example, in the range of 1 to 500 μm from the viewpoints of workability such as strength and handleability, and thinning. When the thickness of the protective layer is within the above range, the polarizer is mechanically protected, and even when exposed to high temperature and high humidity, the polarizer is prevented from contracting and stable optical characteristics can be maintained. The thickness of the protective layer is preferably in the range of 5 to 200 μm, and more preferably in the range of 10 to 150 μm.

  As the protective layer, it is preferable to use a layer having an optimized retardation value. If such a protective layer is used, the viewing angle characteristics of the image display device are not affected.

  As the retardation value of the protective layer, the in-plane retardation value (Re) is preferably in the range of 0 to 5 nm, more preferably in the range of 0 to 3 nm, and still more preferably 0. The thickness direction retardation value (Rth) is preferably in the range of 0 to 15 nm, more preferably in the range of 0 to 12 nm, and still more preferably in the range of 0 to 5 nm. And most preferably in the range of 0 to 3 nm.

  The protective layer can be appropriately formed by a conventionally known method such as a method of applying the various transparent resins to a polarizer, a method of laminating the resin film or the like on the polarizer, and a commercially available product is used. You can also.

  The protective layer may be further subjected to, for example, a hard coat treatment, an antireflection treatment, an antisticking treatment, a treatment for diffusion, antiglare, or the like.

  The adhesion method between the polarizer and the protective layer is not particularly limited, and can be performed by a conventionally known method. In general, a pressure-sensitive adhesive, other adhesives, and the like are used, and the type can be appropriately determined depending on the type of the polarizer and the protective layer. Specific examples include adhesives and pressure-sensitive adhesives composed of PVA-based, modified PVA-based, and urethane-based polymers. These adhesives and pressure-sensitive adhesives are used for improving durability, for example, vinyl alcohol type such as boric acid, borax, glutaraldehyde, melamine, oxalic acid, chitin, chitosan, metal salt, alcoholic solvent, etc. A water-soluble crosslinking agent that crosslinks the polymer may be added. In the case where the polarizer is, for example, a PVA film, a PVA adhesive or pressure-sensitive adhesive is preferable from the viewpoint of the stability of the adhesion treatment. These adhesives and pressure-sensitive adhesives may be applied to the surface of the polarizer or the protective layer as they are, for example, as an aqueous solution of the adhesive or pressure-sensitive adhesive to form an adhesive layer or pressure-sensitive adhesive layer. An adhesive layer such as a tape or sheet made of an adhesive or an adhesive layer may be disposed on the surface. In addition, when apply | coating the said adhesive agent or an adhesive, you may mix | blend another additive and catalysts, such as an acid, with the said aqueous solution, for example. The thickness of such an adhesive layer or pressure-sensitive adhesive layer is not particularly limited, but is, for example, in the range of 1 to 500 nm, preferably in the range of 10 to 300 nm, and more preferably in the range of 20 to 100 nm. .

  When the polarizer and the protective layer are bonded by the adhesive, for example, a drying process is performed to prevent peeling due to the influence of humidity and heat, and to obtain a polarizing plate excellent in light transmittance and degree of polarization. It is preferable to apply. It does not restrict | limit especially as drying temperature, For example, it is the range of 20-90 degreeC, Preferably, it is the range of 30-60 degreeC. The drying time is not particularly limited, but is, for example, in the range of 1 to 20 minutes, and preferably in the range of 3 to 20 minutes.

  Moreover, since the polarizing plate of this invention becomes easy to laminate | stack to a liquid crystal cell etc., for example, it is preferable to have an adhesive layer in the outermost layer further. In FIG. 7, sectional drawing of the polarizing plate which has such an adhesive layer is shown. 7, the same parts as those in FIG. 6 are denoted by the same reference numerals. As shown in the drawing, the polarizing plate 70 has a configuration in which an adhesive layer 71 is further disposed on the surface of one protective layer 62 of the polarizing plate 60.

  The pressure-sensitive adhesive layer is formed on the surface of the protective layer by, for example, adding a solution or a melt of the pressure-sensitive adhesive directly to a predetermined surface of the protective layer by a developing method such as casting or coating. It can be performed by a method of forming, a method of forming a pressure-sensitive adhesive layer on a separator, which will be described later, and transferring it to a predetermined surface of the protective layer. In addition, although such an adhesive layer may be formed in any one surface of a polarizing plate like the said FIG. 7, it is not limited to this, You may arrange | position 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 acrylic, silicone, polyester, polyurethane, polyether, or rubber. In particular, the moisture absorption rate is low in terms of preventing foaming and peeling due to moisture absorption, reducing optical characteristics due to thermal expansion differences, preventing warping of liquid crystal cells, and forming liquid crystal display devices with high quality and durability. It is preferable to use an adhesive having excellent heat resistance. Examples of such an adhesive include acrylic, silicone, acrylic silicone, polyester, and heat resistant rubber adhesives. The pressure-sensitive adhesive layer may be a pressure-sensitive adhesive layer containing fine particles and exhibiting light diffusibility.

  The surface of the pressure-sensitive adhesive layer is preferably covered with a separator for the purpose of preventing contamination. This separator can be formed by, for example, a method of providing a release coat with a release agent such as a silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide on a thin film such as the protective film.

  Although the thickness of the said adhesive layer is not restrict | limited in particular, For example, it is the range of 5-35 micrometers, Preferably, it is the range of 10-25 micrometers, More preferably, it is the range of 15-25 micrometers.

(10) Optical Film Next, the optical film of the present invention has a configuration in which a retardation plate is laminated on at least one surface of the polarizer of the present invention or the polarizing plate of the present invention.

  Examples of the retardation plate include various wavelength plates such as a 1 / 2λ plate and a 1 / 4λ plate, and those for the purpose of visual compensation such as coloring compensation due to birefringence of the liquid crystal layer and viewing angle expansion, etc. It may have a phase difference according to the purpose of use, or may be a tilted alignment film in which the refractive index in the thickness direction is controlled. Further, a laminate or the like in which two or more kinds of retardation plates are laminated and optical characteristics such as retardation are controlled may be used.

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

  The tilted orientation film is, for example, a method in which a heat-shrinkable film is bonded to a polymer film, and the polymer film is subjected to stretching treatment or shrinkage treatment under the action of the shrinkage force by heating, or a liquid crystal polymer is obliquely oriented. It can obtain by the method of making it.

(11) Applications The polarizer, polarizing plate and optical film of the present invention can be preferably used for various image display devices such as a liquid crystal display (LCD) and an EL display (ELD). The liquid crystal display device of the present invention has the same configuration as the conventional liquid crystal display device except that at least one of the polarizer, the polarizing plate and the optical film of the present invention is used. In the liquid crystal display device of the present invention, for example, a liquid crystal cell, an optical member such as the polarizer of the present invention, and various components such as an illumination system (backlight or the like) are appropriately assembled to incorporate a drive circuit. Etc. can be manufactured.

  In the present invention, the configuration of the liquid crystal display device is not particularly limited, and a liquid crystal display device in which an optical member such as a polarizer of the present invention is disposed on one side or both sides of a liquid crystal cell, or a backlight or a reflector is used in an illumination system. Liquid crystal display devices. When optical members such as the polarizer of the present invention are arranged on both sides of the liquid crystal cell, they may be the same or different. Furthermore, in the liquid crystal display device of the present invention, for example, optical members and optical components such as a diffusion plate, an antiglare layer, an antireflection layer, a protective plate, a prism array, and a lens array sheet may be disposed.

  The image display device of the present invention is used for any appropriate application. Applications include, for example, OA equipment such as desktop personal computers, notebook personal computers, and copiers, mobile phones, watches, digital cameras, personal digital assistants (PDAs), portable devices such as portable game machines, video cameras, televisions, microwave ovens, etc. Household electrical equipment, back monitor, car navigation system monitor, car audio and other in-vehicle equipment, display equipment for commercial store information monitors, security equipment such as monitoring monitors, nursing care monitors, medical monitors, etc. Nursing care / medical equipment.

  Next, examples of the present invention will be described. The present invention is not limited or restricted by the following examples. In addition, various characteristics and physical properties in the examples were measured by the following methods.

(1) Width remaining ratio As shown by the arrow in FIG. 8A, the PVA film 1 was stretched in the width direction (vertical direction in the figure) by the gripping means 2 of the hand stretching machine. Thereafter, as shown in FIG. 8B, the gripping means 2 at both ends in the width direction of the PVA film 1 was removed, and immediately after that, the length W1 in the width direction of the PVA film ₁ was measured. Next, both ends in the longitudinal direction of the PVA film 1 were gripped by the gripping means 2 using another hand stretching machine. Thereby, the movement to the inner side in the width direction of the PVA film 1 was restricted, and the shrinkage in the width direction was suppressed. At this time, the distance between the gripping means 2 at both ends in the longitudinal direction of the PVA film 1 was L. That is, the distance between the grip means 2 at both ends in the longitudinal direction of the PVA film 1 was assumed to be the distance from the open position to the fixed position. In this state, the length W ₂ in the width direction of the PVA film 1 was measured. Based on W ₁ and W ₂ measured in this way, the width remaining ratio (W ₂ / W ₁ ) was calculated.

(2) Single transmittance and degree of polarization The single transmittance is a two-degree field defined in JIS Z 8701-1982 using an ultraviolet-visible spectrophotometer (trade name “V-7100” manufactured by JASCO Corporation). The Y value subjected to visibility correction was measured and obtained by (C light source). In addition, the degree of polarization is measured by measuring the parallel transmittance (H ₀ ) and orthogonal transmittance (H ₉₀ ) of the polarizer using the ultraviolet-visible spectrophotometer, and the formula: degree of polarization (%) = {(H _{0 -H 90) / (H 0 +} H 90)} was determined from ^1/2 × 100. The parallel transmittance (H ₀ ) is a transmittance value of a parallel laminated polarizer prepared by superposing two polarizers of the same type so that their absorption axes are parallel to each other. The orthogonal transmittance (H ₉₀ ) is a value of the transmittance of an orthogonal laminated polarizer produced by superposing two polarizers of the same type so that their absorption axes are orthogonal to each other. In addition, these transmittance | permeability is Y value which performed visibility correction | amendment by the 2 degree visual field (C light source) prescribed | regulated to JISZ8701-1982.

(3) Dichroic ratio The dichroic ratio was calculated by the following formulas (I) to (III) using the parallel transmittance (H ₀ ) and orthogonal transmittance (H ₉₀ ) of the polarizer at a wavelength of 550 nm. In the following formula (III), DR is a dichroic ratio. The measurement method of the parallel transmittance _{(H 0)} and perpendicular transmittance _{(H 90)} is as described above.

[Example 1]
(Preparation of PVA film)
A raw PVA film (trade name “VF-PS”, manufactured by Kuraray Co., Ltd.) was cut so that the length in the longitudinal direction was 180 mm and the length in the width direction was 50 mm to obtain a sample PVA film. The thickness of this PVA film was 75 μm.

(Production of polarizer)
(1) Swelling step and width direction stretching step While spraying water (swelling liquid) at 30 ° C. for 30 seconds in the gas phase on both sides of the PVA film, using a hand stretching machine, Uniaxial stretching was performed in the width direction so that the length was 2.2 times the length.

(2) Dyeing step and width direction stretching step 30 ° C. aqueous solution (dye solution) containing water, iodine and potassium iodide in a gas phase in a ratio of 92: 7: 1 on one side of the PVA film. Was sprayed for 47 seconds using a hand stretching machine, and uniaxial stretching was performed in the width direction so as to be 1.5 times the length of the PVA film after the swelling step.

(3) Crosslinking step and width direction stretching step A 30 ° C. aqueous solution (crosslinking solution) containing 3% by weight of boric acid and 3% by weight of potassium iodide in a gas phase on one side of the PVA film for 52 seconds. While spraying, using a hand stretching machine, uniaxial stretching was performed in the width direction so as to be 1.1 times the length of the PVA film after the dyeing step.

(4) Width Direction Stretching Step While spraying a 30 ° C. aqueous solution (stretching solution) containing 4% by weight boric acid and 5% by weight potassium iodide on one side of the PVA film in the gas phase for 58 seconds. Using a hand stretching machine, uniaxial stretching was performed in the width direction so as to be 1.6 times as long as the length of the PVA film after the crosslinking step.

(5) Adjustment process An aqueous solution (conditioning solution) containing 30% by weight of potassium iodide containing 4% by weight of potassium iodide was sprayed for 10 seconds on one side of the PVA film after the widthwise stretching treatment in the gas phase.

(6) Opening step and width direction both-end fixing step After the adjusting step, the PVA film was released from the gripping means in accordance with the method for measuring the width remaining rate, and then the movement of the PVA film inward in the width direction was restricted.

(7) Drying step After the measurement of the width residual ratio, the PVA film was dried in an oven at 60 ° C. for 4 minutes. In this way, the polarizer of this example was obtained. With respect to this polarizer, the single transmittance, the degree of polarization, and the dichroic ratio were measured.

The relationship between L / W ₁ and the remaining width ratio (W ₂ / W ₁ ) was determined by changing L shown in FIG. The result is shown in the graph of FIG. In addition, the graph of FIG. 10 shows the relationship between the remaining width ratio (W ₂ / W ₁ ) and the dichroic ratio. Furthermore, the graph of FIG. 11 shows the relationship between the single transmittance and the degree of polarization at different width residual ratios.

As can be seen from FIG. 9, when L / W ₁ was 0.2 or less, the width remaining ratio (W ₂ / W ₁ ) was 0.92 or more. Further, as can be seen from FIG. 10, when the width residual ratio (W ₂ / W ₁ ) is 0.92 or more, a polarizer having excellent optical characteristics with a dichroic ratio of 134.8 or more was obtained. Further, as can be seen from the graph of FIG. 11, when the width residual ratio (W ₂ / W ₁ ) is 0.92 or more, the obtained polarizer has excellent optical characteristics.

In the graph shown in FIG. 9, the relationship between L / W ₁ and the remaining width ratio (W ₂ / W ₁ ) is the relationship of the following formula (2) obtained by least square approximation.

(W ₂ / W ₁ ) = − 0.66 (L / W ₁ ) +1.05 (2)

Here, when the length in the width direction of the PVA film immediately before the drying step is W ₃ , and the length in the width direction of the PVA film after the drying step is W ₄ , the relationship of the formula (1) is satisfied. It is preferable to satisfy. Satisfies the relationship of formula (1), and the width residual ratio of the PVA film after the drying step _{(W 2 / W 1) ×} (W 4 / W 3) is 0.92 or more. As a result, it is possible to more suitably suppress deterioration of the characteristics of the obtained polarizer.

[Comparative Example 1]
A polarizer of this comparative example was obtained in the same manner as in Example 1 except that the width direction both-end fixing step was not performed. This polarizer contracted in the width direction and wrinkled.

  As described above, according to the method for producing a polarizer of the present invention, it is possible to produce a polarizer in which a decrease in optical properties is suppressed. Applications of the polarizer of the present invention and polarizing plates, optical films, and image display devices using the polarizer are, for example, OA devices such as desktop personal computers, notebook personal computers, and copiers, mobile phones, watches, digital cameras, and portable information terminals ( PDAs), portable devices such as portable game machines, household electric devices such as video cameras, televisions, and microwave ovens, back monitors, car navigation system monitors, car audio and other in-vehicle devices, commercial store information monitors, etc. Examples include exhibition equipment, security equipment such as monitoring monitors, nursing care / medical equipment such as nursing care monitors, medical monitors, etc. The use thereof is not limited and can be applied to a wide range of fields.

FIG. 1 is a schematic diagram showing an example of the width direction stretching step of the present invention. FIG. 2 is a view for explaining gripping of the hydrophilic polymer film by the gripping means of the present invention. FIG. 3 is an enlarged view of a part of FIG. FIG. 4 is a schematic diagram illustrating an example of the opening process and the width direction both-end fixing process of the present invention. FIG. 5 is a schematic diagram illustrating another example of the opening process and the width direction both-end fixing process of the present invention, and an example of the drying process of the present invention. FIG. 6 is a cross-sectional view showing an example of the configuration of the polarizing plate of the present invention. FIG. 7 is a cross-sectional view showing another example of the configuration of the polarizing plate of the present invention. FIG. 8 is a diagram for explaining a method for measuring the width remaining ratio in the embodiment of the present invention. FIG. 9 is a graph showing the relationship between L / W ₁ and the remaining width ratio (W ₂ / W ₁ ) in the example of the present invention. FIG. 10 is a graph showing the relationship between the remaining width ratio (W ₂ / W ₁ ) and the dichroic ratio in the example of the present invention. FIG. 11 is a graph showing the relationship between the single transmittance and the degree of polarization at different width residual ratios in the examples of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hydrophilic polymer film 2 Gripping means 3 Roll 4 Transport roll 21 Rotating shaft 22 Upper grip part 23 Lower grip part 60, 70 Polarizing plate 61 Polarizer 62 Protective layer 71 Adhesive layer A, B, C Arrow D Drying process X Open Position Y Fixed position

Claims (16)

The both ends of the hydrophilic polymer film that is continuously supplied are gripped by the gripping means, the gripping means is advanced in the longitudinal direction of the hydrophilic polymer film, and the both ends of the hydrophilic polymer film are gripped. A widthwise stretching step of stretching the hydrophilic polymer film in the width direction by moving at least one of the gripping means to the outside in the width direction of the hydrophilic polymer film;
A dyeing step of dyeing the hydrophilic polymer film with a dichroic substance,
The method for producing a polarizer, wherein the width direction stretching step is carried out in at least one step different from the dyeing step and the dyeing step,
Furthermore, after the width direction stretching step, an opening step of releasing the hydrophilic polymer film from the gripping means at an open position;
The hydrophilic polymer film is moved from the open position to a fixed position, and both ends in the width direction of the hydrophilic polymer film are fixed by the width direction both-end fixing means at the fixed position to restrict movement inward in the width direction. And a width direction both-end fixing step for suppressing shrinkage in the width direction of the hydrophilic polymer film. The method for producing a polarizer according to claim 1, wherein the width direction both-end fixing means is a gripping means for gripping both ends in the width direction of the hydrophilic polymer film. The method for producing a polarizer according to claim 1, wherein the width direction both-end fixing means is a roll pinch means for pinching the hydrophilic polymer film with two rolls from above and below. In the opening step and the width direction both-end fixing step, the ratio between the length (W ₁ ) of the hydrophilic polymer film in the opening position in the width direction and the distance (L) from the opening position to the fixing position (L / W ₁₎ a method for producing a polarizer according to any one of claims 1 to 3, 0.2 or less. In the opening step and the width direction both-end fixing step, the length (W ₁ ) of the hydrophilic polymer film in the opening position and the width direction of the hydrophilic polymer film in the fixing position _{(W 2)} and method for producing a polarizer according to any one of claims 1 to 4, the width remaining rate is a ratio of _(W 2 / W _1), and 0.92 or more. Furthermore, it has a drying process which dries the said hydrophilic polymer film, The manufacturing method of the polarizer as described in any one of Claim 1 to 5 which implements the said drying process at least after the said width direction both ends fixing process. The opening step is omitted, and the width direction both ends fixing step is performed after the width direction stretching process in the width direction stretching step is completed, and the film width direction length of the film is continuously held by the gripping means. The method for producing a polarizer according to claim 6, wherein the method is carried out by shifting to the drying step while keeping the thickness constant. When the length in the width direction of the hydrophilic polymer film immediately before the drying step is W ₃ , and the length in the width direction of the hydrophilic polymer film after the drying step is W ₄ , the relationship of the following formula (1) The manufacturing method of the polarizer of Claim 6 which satisfy | fills.

{−0.66 × (L / W ₁ ) +1.05} × (W ₄ / W ₃ ) ≧ 0.92 (1)
W ₁ : Length in the width direction of the hydrophilic polymer film at the open position (mm)
L: Distance from the open position to the fixed position (mm)
W ₃ : Length in the width direction of the hydrophilic polymer film immediately before the drying step (mm)
W ₄ : Length in the width direction of the hydrophilic polymer film after the drying step (mm)
The polarizer according to any one of claims 1 to 8, wherein the another step includes at least one of a swelling step for swelling the hydrophilic polymer film and a crosslinking step for crosslinking the hydrophilic polymer film. Production method. The polarized light according to claim 9, wherein in at least one of the swelling process, the dyeing process, the crosslinking process, and the width direction stretching process, a liquid is brought into contact with at least one surface of the hydrophilic polymer film in a gas phase. Child manufacturing method. The method for producing a polarizer according to claim 10, wherein the contact of the liquid is performed by at least one of spraying and applying the liquid. The method for producing a polarizer according to any one of claims 1 to 11, wherein the hydrophilic polymer film is a polyvinyl alcohol film, and the dichroic substance is iodine. The polarizer manufactured by the manufacturing method as described in any one of Claims 1-12. The polarizing plate which is the polarizing plate by which the protective layer was laminated | stacked on the at least one surface of the polarizer, Comprising: The said polarizer is a polarizer of Claim 13. An optical film in which a retardation plate is laminated on at least one surface of a polarizer or a polarizing plate, wherein the polarizer is the polarizer according to claim 13, and the polarizing plate is a polarization according to claim 14. An optical film that is a plate. It is an image display apparatus containing at least one of a polarizer, a polarizing plate, and an optical film, Comprising: The said polarizer is a polarizer of Claim 13, and the said polarizing plate is a polarizing plate of Claim 14. The image display device, wherein the optical film is the optical film according to claim 15.

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