JP2008275926A - 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 large-sized and highly-oriented polarizer, without needing a large-sized raw film and a large-sized stretching machine, and by preventing its fracturing. <P>SOLUTION: The method for manufacturing a polarizer includes: a width direction stretching process of stretching a hydrophilic polymer film 1 in the width direction by grasping two ends in the width direction of the film 1 with grasping means, and moving the grasping means in the longitudinal direction of the film 1, and also moving at least one end of the grasping means for grasping the two ends of the film 1 outward in the width direction of the film 1; and a dyeing process for performing dyeing processing for the film 1 with a dichroic material, wherein the width direction stretching process is performed in at least one of the dyeing process and processes other than the dyeing process. The method also includes a slitting process for slitting the edge in the width direction of the film 1 in the longitudinal direction, while the moisture content is 18% or more, after the width direction stretching process. <P>COPYRIGHT: (C)2009,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. Usually, the polarizer is produced by dyeing and uniaxially stretching a polyvinyl alcohol (PVA) film. 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 recent years, the use of LCDs for televisions has increased rapidly, and the screen size has also increased. In connection with this, the polarizer used for the television is also required to be enlarged. As a method for producing such a large polarizer, a method of uniaxially stretching a PVA film in the longitudinal direction has been proposed (see Patent Document 1). However, in this method, it is necessary to prepare a large original film, but the size of the original film is limited. Moreover, in this method, in order to obtain a highly oriented polarizer, there is a problem that the stretching machine becomes large when the stretching ratio of the PVA film is increased.
JP 2001-305347 A

  Then, this invention aims at providing the manufacturing method of the polarizer which can obtain a large sized highly oriented polarizer, without requiring a large sized raw film and a drawing machine.

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, it has a slit process of excising the width direction end of the hydrophilic polymer film in the longitudinal direction,
After the width direction stretching step, the slit step is performed,
The slit process is performed by cutting the widthwise end portion of the hydrophilic polymer film by cutting means under the condition that the water content of the hydrophilic polymer film is 18% or more.

  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 method for producing a polarizer of the present invention, since the hydrophilic polymer film is stretched in the width direction, a large and highly oriented polarizer can be obtained without requiring a large original fabric film and a stretching machine. Further, if the holding means is used for stretching in the width direction, the end portion including the gripped portion of the hydrophilic polymer film becomes unstretched or insufficiently stretched and becomes an unnecessary portion, and therefore needs to be removed in a slit process. There is. However, when a force is applied in the longitudinal direction of the film after the slit, the film is easily broken. In this regard, in the present invention, since the hydrophilic polymer film width direction end portion is slit in a high water content state where the water content is 18% or more, breakage after the slit can be prevented, yield is improved, and production efficiency is improved. It becomes like this. 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.

  In the present invention, the optical characteristics include, for example, a phase difference, a polarization characteristic, and the like.

  In the manufacturing method of the present invention, the cutting means is a cutting blade, and is caused by bringing the cutting blade into contact with the widthwise end of the hydrophilic polymer film in a state in which the hydrophilic polymer film is advanced in the longitudinal direction. It may be an embodiment in which the cutting force is used. Moreover, it is preferable that the said width direction edge part cut off is the both ends of the width direction of the said hydrophilic polymer film.

  As described above, in the production method of the present invention, the water content of the hydrophilic polymer film in the slit step is 18% or more. By considering the moisture content in the above range, the breaking strength of the hydrophilic polymer film is, for example, 7 N / cm or more in consideration of the tension applied to the hydrophilic polymer film in the continuous production process of the polarizer. As a result, breakage of the hydrophilic polymer film after slitting can be prevented, yield is improved, and manufacturing efficiency is improved. The moisture content is preferably in the range of 18 to 35%, more preferably in the range of 19 to 35%. In the present invention, the moisture content means the ratio (%) of the moisture weight in the film to the weight of the hydrophilic polymer film, and can be measured by, for example, the method described in the examples described later.

  In this invention, it is preferable that the draw ratio in the said width direction extending process is the range of 5-6 times the original width direction length of the said hydrophilic polymer film.

  The production method of the present invention further includes a longitudinal shrinkage step of shrinking the hydrophilic polymer film in the longitudinal direction, and the longitudinal shrinkage step is performed after the width direction stretching step and before the slit step. It is preferred that The reason for this is as follows. That is, first, in the method of stretching the hydrophilic polymer film in the width direction, the direction (longitudinal direction) perpendicular to the stretching direction (width direction) of the hydrophilic polymer film is usually fixed. The longitudinal shrinkage of the film is limited. As a result, the polarizer obtained by this method may develop biaxiality. Then, if the longitudinal direction contraction process which contracts the said hydrophilic polymer film to a longitudinal direction is implemented after the width direction extending | stretching process, expression of biaxiality can be suppressed.

  In the longitudinal shrinking step, for example, after the hydrophilic polymer film is released from the gripping means, the hydrophilic polymer film is transported by two or more rolls in the longitudinal direction, and the traveling direction of the hydrophilic polymer film You may implement by making the rotational speed of the said roll of the downstream side slow with respect to the rotational speed of the said roll of the upstream.

  In the longitudinal shrinking step, for example, while moving both ends of the hydrophilic polymer film in the width direction with the gripping means, the moving speed of the gripping means in the longitudinal direction of the hydrophilic polymer film is set in the traveling direction of the film. You may carry out by delaying sequentially as it goes downstream.

  The longitudinal direction shrinking step may be performed, for example, by reducing the water content of the hydrophilic polymer film. In this case, the water content of the hydrophilic polymer film can be reduced, for example, by subjecting the hydrophilic polymer film to a heat drying treatment.

  The shrinkage ratio of the hydrophilic polymer film in the longitudinal shrinking step is not particularly limited, but is, for example, in the range of 1 to 60%, preferably in the range of 3 to 30%, and more preferably in the range of 5 to 5%. The range is 20%.

  In the manufacturing method of this invention, it is preferable to make a liquid contact at least one surface of the said hydrophilic polymer film in a gaseous phase in the said width direction extending | stretching process. In this case, the contact of the liquid is preferably performed by at least one of spraying and applying the liquid.

  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, in at least one of the swelling process, the dyeing process, and the crosslinking process, it is preferable that a liquid is brought into contact with at least one surface of the hydrophilic polymer film in a gas phase. 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 production method 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 cross-linking step, an adjustment step, and a drying step, and at least one of these steps or separately The width direction stretching step is performed, and after the width direction stretching step, the slit step is performed. The slit process is preferably performed before the drying process. In addition, as described above, it is preferable to perform the longitudinal direction shrinking step after the width direction stretching step and before the slit step. That is, it is preferable to implement the manufacturing method of the polarizer of this invention in order of a swelling process, a dyeing process, a bridge | crosslinking process, the width direction extending process, an adjustment process, a longitudinal direction shrinkage process, a slit process, and a drying process, for example. However, the present invention is not limited to this order.

(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.

(1) Swelling step The raw hydrophilic polymer film is first 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, means and conditions for spraying or applying the swelling liquid onto the hydrophilic polymer film when the width direction stretching step is performed are as described in the width direction stretching step described later.

  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.

(3) 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, dyeing efficiency and the like 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 spraying or applying the dyeing liquid onto the hydrophilic polymer film when the width direction stretching step is performed are as described in the width direction stretching step described later.

  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.

(4) 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 spraying or applying the crosslinking liquid to the hydrophilic polymer film when the width direction stretching step is performed are as described in the width direction stretching step described later.

  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.

(5) Width Direction Stretching Step Next, 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 to bring the liquid into contact with at least one surface of the hydrophilic polymer film 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 spray nozzle and the hydrophilic polymer film can be appropriately determined according to the spray 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. 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, preferably 3 to the length of the film (raw fabric) before stretching. The range is 10 times, more preferably 4 to 8 times, and particularly preferably 5 to 6 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.

(6) Adjustment process Next, the said hydrophilic polymer film is made to contact iodide containing aqueous solution (conditioning liquid).

  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 spraying or applying the adjusting liquid onto 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.

(6) Longitudinal contraction step After the adjusting step, the hydrophilic polymer film is contracted in the longitudinal direction. The implementation time of the longitudinal direction shrinking step is not particularly limited as long as it is after the width direction stretching step. The longitudinal direction shrinking step may be performed immediately after the width direction stretching step. In addition, after the width direction stretching step, another step may be included before the longitudinal direction shrinking step is performed. However, when including the said another process, it is preferable that the both ends of the said hydrophilic polymer film are continuously hold | gripped by the said holding means, while the said another process is implemented.

  As described above, in this step, for example, after the hydrophilic polymer film is released from the gripping means, the hydrophilic polymer film proceeds while the hydrophilic polymer film is conveyed by two or more rolls in the longitudinal direction. You may implement by making the rotational speed of the said roll of the downstream side slow with respect to the rotational speed of the said roll of the upstream of a direction (longitudinal direction). In this case, the number of the said rolls is the range of 2-20, for example, Preferably, it is the range of 2-10, More preferably, it is the range of 2-5. When the number of the rolls is three or more, the rotational speed of the rolls is sequentially decreased as going to the downstream side in the traveling direction (longitudinal direction) of the hydrophilic polymer film. The shorter the distance between the rolls adjacent in the traveling direction (longitudinal direction) of the hydrophilic polymer film, the better. However, the length in the width direction of the hydrophilic polymer film after the width direction stretching step is W (mm). ), For example, a range of 0.025 W to 0.5 Wmm, preferably a range of 0.025 W to 0.25 Wmm, and more preferably a range of 0.025 W to 0.125 Wmm. The difference in rotational speed between the adjacent rolls in the traveling direction (longitudinal direction) of the hydrophilic polymer film is not particularly limited, but is, for example, in the range of 1 to 10 m / min, preferably 1 to 5 m / min. It is a range, More preferably, it is the range of 1-2 m / min. Further, the difference in rotational speed between the roll having the highest rotational speed and the roll having the slowest rotational speed is not particularly limited, and is, for example, in the range of 0.4 to 9.9 m / min. It is in the range of 4 to 4.95 m / min, and more preferably in the range of 0.4 to 1.98 m / min.

  As described above, in this step, for example, while the both ends of the hydrophilic polymer film in the width direction are held by the holding means, the moving speed of the holding means in the longitudinal direction of the hydrophilic polymer film is increased. You may carry out by delaying sequentially as it goes downstream of a direction (longitudinal direction). In this case, the moving speed of the gripping means before the slowing is, for example, in the range of 1 to 10 m / min, preferably in the range of 1 to 5 m / min, and more preferably in the range of 1 to 2 m. The moving speed of the gripping means after the slowing is, for example, in the range of 0.4 to 9.9 m / min, and preferably in the range of 0.4 to 4.95 m / min. The range is more preferably 0.4 to 1.98 m / min.

  As described above, this step may be performed, for example, by reducing the water content of the hydrophilic polymer film in addition to the two methods. In this case, the water content of the hydrophilic polymer film after the decrease is, for example, in the range of 10 to 50%, and preferably in the range of 15 to 45%.

  The water content of the hydrophilic polymer film can be reduced, for example, by subjecting the hydrophilic polymer film to a heat drying treatment. In the heat drying treatment, the treatment temperature is, for example, in the range of 25-60 ° C, preferably in the range of 30-50 ° C, more preferably in the range of 30-45 ° C, and the treatment time is For example, it is in the range of 0.5 to 5 minutes, preferably in the range of 0.5 to 3 minutes, and more preferably in the range of 0.5 to 1.5 minutes.

  This step may be performed only by a method based on the rotation speed ratio of the roll, or may be performed only by a method of slowing the moving speed of the gripping means. Furthermore, you may implement the method by the reduction | decrease of the moisture content of the said hydrophilic polymer film in these methods. This step is a combination of a method based on the rotational speed ratio of the roll and a method based on a decrease in the moisture content of the hydrophilic polymer film, or a method of slowing the moving speed of the gripping means and the moisture content of the hydrophilic polymer film. It is preferably carried out in combination with the method by reduction. Moreover, you may implement this process combining the method by the rotational speed ratio of the said roll, and the method of making the moving speed of the said holding means slow. In this case, both ends of the hydrophilic polymer film are held by the holding means. Further, this step may be performed by combining all the three methods.

  The shrinkage ratio of the hydrophilic polymer film in this step is as described above.

(8) Slit process Next, the edge part of the said hydrophilic polymer film is excised. The excision is preferably performed by excision means, for example, while transporting the hydrophilic polymer film with two or more rolls. As the excision means, a known cutting means such as a cutting blade or a laser can be used. The excision can be performed, for example, as shown in FIG. As shown in the drawing, the hydrophilic polymer film 1 is transported by two rolls R1 and R2, and in this state, the two cutting blades S1 and S2 are respectively connected to each end in the width direction of the hydrophilic polymer film. The both ends of the hydrophilic polymer film 1 are excised with the cutting force generated by the conveyance. The hydrophilic polymer film 1 after excision is conveyed to the next step such as a drying step described later. On the other hand, both the cut ends (chips) are removed by, for example, separately winding or sucking on a roll. The cutting blade is not particularly limited, and for example, a round blade, a dish blade, or the like can be used. Further, the width of each end portion in the width direction to be cut is not particularly limited, and is appropriately determined depending on the length of the hydrophilic polymer film 1 in the width direction, the draw ratio, the length of the gripping width of the gripping means, and the like. The width | variety of each edge part of the said width direction to cut | disconnect is the range of 50-300 mm, for example, Preferably, it is the range of 100-200 mm. The water content of the hydrophilic polymer film in the slitting process is as described above. Thus, by performing the slit process in a state where the water content of the hydrophilic polymer film is high, it becomes possible to prevent breakage after the slit process (for example, in the state of a polarizer).

(9) Drying process Finally, a polarizer can be obtained by drying the hydrophilic polymer film.

  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 25-70 degreeC is preferable, More preferably, it is the range of 30-65 degreeC, More preferably, it is the range of 45-60 degreeC. The water content of the hydrophilic polymer film after the drying step is, for example, in the range of 10 to 30%, and preferably in the range of 15 to 20%.

  The swelling process, the dyeing process, the crosslinking process, the width direction stretching process, the adjusting process, the longitudinal direction shrinking process, the slit process, and the 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 process and a drying process for every process completion | finish.

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

(10) 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.

(11) 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. 4, sectional drawing of an example of the polarizing plate of this invention is shown. As shown in the figure, the polarizing plate 40 has protective layers 42 laminated on both sides of the polarizer 41.

  The protective layer 42 is not particularly limited, and a conventionally known protective film can be used. For example, a 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, as described in JP-A-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 also 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. FIG. 5 shows a cross-sectional view of a polarizing plate having such an adhesive layer. In FIG. 5, the same parts as those in FIG. As shown in the figure, the polarizing plate 50 has a configuration in which an adhesive layer 51 is further disposed on the surface of one protective layer 42 of the polarizing plate 40.

  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. 5, 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.

(12) 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, and the like.

  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.

  The retardation plate may be made by itself or a commercially available product may be used.

(13) 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 the 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 for 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 together with comparative examples. The present invention is not limited or restricted by the following examples and comparative examples. Further, various properties and physical properties in Examples and Comparative Examples were measured by the following methods.

(1) Moisture content The moisture content of the PVA film was obtained by drying the PVA film at 120 ° C. for 2 hours and changing the weight before and after the drying.

(2) Breaking strength The obtained polarizer was pulled in the tensile strength measuring device (manufactured by KYOWA, trade name: LUB-50KB Capacity 500N) in the direction perpendicular to the stretching direction in the width direction. did. The measurement of the breaking strength was carried out for 20 samples in both the examples and the comparative examples, and the average value thereof was taken as the breaking strength.

[Example 1]
(Preparation of PVA film)
An original fabric PVA film (trade name “VF-PS”, manufactured by Kuraray Co., Ltd.) wound around a roll having a thickness of 75 μm, a width of 0.13 m and a length of 50 m made of PVA having a polymerization degree of 2400 was prepared. The raw fabric PVA film was successively fed out, both ends in the width direction of the PVA film were gripped by gripping means (tenter clips), and conveyed in the longitudinal direction of the PVA film at a speed of 1 m / min with a tenter stretching machine. At this time, the length of the gripping margin by the gripping means (tenter clip) was 15 mm, and the width was 50 mm. Moreover, the distance between the said holding means (tenter clip) adjacent to the longitudinal direction of the said PVA film was 5 mm.

(Production of polarizer)
(1) Swelling step and width direction stretching step Using a spraying device (spray) that reciprocates in the width direction of the PVA film at 30 m / min, on both sides of the PVA film in the gas phase at a flow rate of 16 mL / min. Then, 30 ° C. water (swelling liquid) was sprayed for 30 seconds. Under the present circumstances, the said PVA film was extended | stretched in the width direction so that it might become 2.2 times the length of an original fabric with the said holding means (tenter clip).

(2) Dyeing step and width direction stretching step A 30 ° C. aqueous solution containing 0.2 wt% iodine in a gas phase on one side of the swollen PVA film using the spraying device (spray) (dyeing) Liquid) was sprayed for 25 seconds. Under the present circumstances, the said PVA film was extended | stretched in the width direction so that it might become 3.3 times the length of an original fabric with the said holding means (tenter clip).

(3) Crosslinking step and width direction stretching step Using the spraying device (spray), 3% by weight boric acid and 3% by weight iodination are performed on one side of the PVA film after the dyeing treatment in the gas phase. A 30 ° C. aqueous solution (crosslinking solution) containing potassium was sprayed for 10 seconds. Under the present circumstances, the said PVA film was extended | stretched in the width direction so that it might become 3.6 times the length of an original fabric with the said holding means (tenter clip).

(4) Width Direction Stretching Step Using the spray device (spray), a 60 ° C. aqueous solution containing 4% by weight boric acid and 5% by weight potassium iodide on one side of the crosslinked PVA film ( (Stretching solution) was sprayed for 60 seconds. Under the present circumstances, the said PVA film was extended | stretched in the width direction so that it might become 5.9 times the length of an original fabric with the said holding means (tenter clip).

(5) Adjustment process Using the spraying device (spray), a 30 ° C. aqueous solution (conditioning solution) containing 4% by weight of potassium iodide was sprayed on one side of the stretched PVA film for 10 seconds.

(6) Longitudinal contraction step At the same time that the PVA film is released from the gripping means (tenter clip), the PVA film is heated and dried for 1 minute in an atmosphere at 45 ° C. while being transported by a roll in the longitudinal direction. Then, the moisture content of the PVA film was reduced, and the length in the longitudinal direction of the PVA film was shrunk to 85% as compared to immediately after the opening (shrinkage rate 15%). A total of four rolls were used, and the rotational speed of the rolls was sequentially decreased as going to the downstream side in the traveling direction of the PVA film. The distance between the rolls adjacent in the traveling direction (longitudinal direction) of the PVA film was 60 mm. The rotational speeds of the rolls were 1.00 m / min, 0.9 m / min, 0.875 m / min, and 0.85 m / min, respectively, from the upstream side in the traveling direction of the PVA film.

(7) Slit process As shown in FIG. 6, while transporting the PVA film 1 after the longitudinal contraction process using two rolls R1, R2, each end in the width direction of the film 1 is cut. Using the blades S1 and S2, the film 1 was cut in the longitudinal direction. The water content of the PVA film 1 at the time of excision is 21%. The width of each cut end was 150 mm.

(8) Drying process The PVA film after shrinkage was subjected to a drying treatment at 60 ° C. for 1 minute to adjust the moisture content of the PVA film to 11%. A continuous polarizer was obtained by winding the dried polarizer with polyethylene terephthalate as interleaving paper.

[Example 2]
A continuous polarizer was obtained in the same manner as in Example 1 except that the moisture content of the PVA film at the time of cutting in the slit process was 19%.

[Example 2]
A continuous polarizer was obtained in the same manner as in Example 1 except that the water content of the PVA film at the time of cutting in the slit process was 18%.

[Comparative Example 1]
A continuous polarizer was obtained in the same manner as in Example 1 except that the moisture content of the PVA film at the time of cutting in the slit process was 17%.

[Comparative Example 2]
A continuous polarizer was obtained in the same manner as in Example 1 except that the moisture content of the PVA film at the time of cutting in the slit process was 14%.

  Table 1 below shows the breaking strength of the polarizers of Examples 1 to 3 and Comparative Examples 1 and 2. As described below, in Examples 1 to 3 in which the PVA film was slit at a moisture content of 18% or more, the breaking strength was high. On the other hand, in Comparative Examples 1 and 2 where the PVA film was slit at a moisture content of less than 18%, the breaking strength was low.

(Table 1)
Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2
Moisture content at slit (%) 21 19 18 17 14
Breaking strength (N / cm) 11.2 12.0 8.0 5.1 6.2

  As described above, according to the method for producing a polarizer of the present invention, a large and highly oriented polarizer can be obtained without requiring a large original film and a stretching machine, and after the slitting. It is possible to manufacture a polarizer while preventing breakage. Applications of the polarizer of the present invention, a polarizing plate using the polarizer, and an image display device include, for example, desktop computers, notebook computers, copiers and other office automation equipment, mobile phones, watches, digital cameras, personal digital assistants (PDAs), Mobile devices such as portable game machines, household electrical 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 and other display devices, Security equipment such as a monitor for monitoring, nursing care / medical equipment such as a care monitor, medical monitor, and the like can be mentioned, and its use 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 cross-sectional view showing an example of the configuration of the polarizing plate of the present invention. FIG. 5 is a cross-sectional view showing another example of the configuration of the polarizing plate of the present invention. FIG. 6 is a schematic view showing an example of a slitting process in the method for producing a polarizer of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hydrophilic polymer film 2 Grasp means 21 Rotating shaft 22 Upper grip part 23 Lower grip part 40, 50 Polarizing plate 41 Polarizer 42 Protective layer 51 Adhesive layer A, B, C Arrow R1, R2 Roll S1, S2 Cutting blade

Claims (15)

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, it has a slit process of excising the width direction end of the hydrophilic polymer film in the longitudinal direction,
After the width direction stretching step, the slit step is performed,
The slit process is performed by cutting the widthwise end of the hydrophilic polymer film with a cutting means under the condition that the water content of the hydrophilic polymer film is 18% or more. Manufacturing method. The cutting means is a cutting blade, and is implemented by a cutting force generated by bringing the cutting blade into contact with the widthwise end of the hydrophilic polymer film in a state in which the hydrophilic polymer film is advanced in the longitudinal direction. Item 2. A method for producing a polarizer according to Item 1. The method for producing a polarizer according to claim 1 or 2, wherein a moisture content of the hydrophilic polymer film in the slit step is in a range of 18 to 35%. 4. The polarizer according to claim 1, wherein a stretching ratio in the width direction stretching step is in a range of 5 to 6 times an original width direction length before stretching of the hydrophilic polymer film. 5. Production method. Furthermore, it has a longitudinal direction shrinking process which shrinks the said hydrophilic polymer film to a longitudinal direction, and the said longitudinal direction shrinking process is implemented after the said width direction extending process and before the said slit process. The manufacturing method of the polarizer as described in any one of these. The method for producing a polarizer according to any one of claims 1 to 5, wherein in the stretching in the width direction, a liquid is brought into contact with at least one surface of the hydrophilic polymer film in a gas phase. The method for producing a polarizer according to claim 6, wherein the contact of the liquid is performed by at least one of spraying and applying the liquid. The polarizer according to any one of claims 1 to 7, wherein the another step includes at least one step of a swelling step of swelling the hydrophilic polymer film and a crosslinking step of crosslinking the hydrophilic polymer film. Production method. The method for producing a polarizer according to claim 8, wherein in at least one of the swelling step, the dyeing step, and the crosslinking step, a liquid is brought into contact with at least one surface of the hydrophilic polymer film in a gas phase. The method for producing a polarizer according to claim 9, 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 10, 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 Claim 1 to 11. The polarizing plate according to claim 12, wherein the polarizing plate has a protective layer laminated on at least one surface of the polarizing plate. 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 12, and the polarizing plate is a polarization according to claim 13. 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 12, and the said polarizing plate is a polarizing plate of Claim 13. The image display device, wherein the optical film is the optical film according to claim 14.

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