JP7292130B2 - Polarizer manufacturing method and polarizer manufacturing apparatus - Google Patents

Description

The present invention relates to a method for manufacturing a polarizer by wet processing and an apparatus for manufacturing the same.

BACKGROUND ART Conventionally, polarizers have been used as constituent materials for liquid crystal display devices, polarized sunglasses, and the like. Examples of the polarizer include a polyvinyl alcohol film dyed with a dichroic substance such as iodine. Hereinafter, in this specification, polyvinyl alcohol may be abbreviated as PVA.
Such a polarizer can be obtained by immersing a PVA-based film in a dyeing solution containing a dichroic substance and stretching the film.
For example, in Patent Document 1, after a PVA-based film is brought into contact with a dyeing solution containing a dichroic substance and stretched, a draining member (a so-called blade) is brought into contact with the surface of the dyed PVA-based film. It is disclosed that a treatment liquid such as a dyeing liquid adhering to the PVA-based film is removed by allowing the film to be exposed to the water.

JP 2017-003955 A

When the liquid draining member is brought into strong contact with the surface of the PVA-based film, the foreign matter and the processing liquid adhering to the surface of the PVA-based film can be removed by the liquid draining member as if scraped off. A polarizer with few defects can be obtained by removing foreign substances adhering to the surface.

However, foreign matter on the PVA-based film deposits on the draining member over time, so there is a problem that the foreign matter cannot be removed gradually. In addition, the surface of the PVA-based film may be easily damaged by the draining member.
In this regard, it is thought that if the contact pressure of the draining member against the surface of the PVA-based film is reduced, the damage to the surface of the PVA-based film can be suppressed. However, if the contact pressure of the liquid draining member is set to be small, foreign matter adhering to the surface of the PVA-based film cannot be sufficiently removed.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method and an apparatus for producing a polarizer with few optical defects.

In the method for producing a polarizer of the present invention, a long strip -shaped raw film having a support film and a hydrophilic polymer layer laminated on the support film is conveyed in the longitudinal direction, and the raw film is dyed with a dyeing solution. A wet treatment step of dyeing and stretching, and a washing step of washing the wet-treated original film with a washing liquid, and the washing step includes a coating roll on one side of the hydrophilic polymer layer of the original film. and a cleaning liquid applying step of applying the cleaning liquid to the surface of the support film of the original film opposite to the surface in contact with the hydrophilic polymer layer using a coating roll. have.

In a preferred manufacturing method of the present invention, the washing step further includes, between the wet treatment step and the washing liquid coating step, a washing liquid immersion step of immersing the original film in a washing treatment bath containing a washing liquid, and The cleaning liquid for the industrial rolls and the cleaning liquid for the cleaning treatment tank are supplied from the same storage tank.
In a preferred production method of the present invention, the cleaning liquid is water or water containing an iodine compound.
A preferred manufacturing method of the present invention is that, in the cleaning liquid coating step, the hydrophilic polymer layer is coated by applying a cleaning liquid to one surface of the hydrophilic polymer layer with the coating roll and then blowing air onto the hydrophilic polymer layer. Remove the cleaning liquid applied to one side of the
In a preferred manufacturing method of the present invention, the coating roll has a plurality of concave portions filled with the cleaning liquid on the outer peripheral surface thereof, and in the cleaning liquid coating step, the outer peripheral surface of the rotating coating roll is coated with the hydrophilic polymer. By bringing one surface of the layer into contact with the hydrophilic polymer layer, the cleaning liquid filled in the recesses of the coating roll is caused to adhere to the hydrophilic polymer layer .

In a preferred manufacturing method of the present invention, in the washing liquid application step, the washing liquid is applied to the hydrophilic polymer layer while rotating the coating roll in a direction opposite to the conveying direction of the original film.
In a preferred manufacturing method of the present invention, a cleaning liquid film having a thickness of 0.1 μm to 20 μm is formed on one surface of the hydrophilic polymer layer by coating the cleaning liquid with the coating roll in the cleaning liquid coating step .

According to another aspect of the present invention, a polarizer manufacturing apparatus is provided.
The apparatus for manufacturing a polarizer of the present invention includes a conveying device for conveying in the longitudinal direction a long strip -shaped original film having a support film and a hydrophilic polymer layer laminated on the support film, and dyeing the original film. A wet processing device for dyeing and stretching with a liquid, and a cleaning device arranged downstream of the wet processing device and cleaning the original film with a cleaning liquid, wherein the cleaning device is filled with the cleaning liquid. It has a first and second coating roll having a plurality of possible recesses on the outer peripheral surface, and the first coating roll has an outer peripheral surface on one side of the hydrophilic polymer layer of the film raw fabric to be conveyed. The second coating roll is arranged so as to contact, and the outer peripheral surface of the second coating roll is arranged so as to contact the surface opposite to the surface in contact with the hydrophilic polymer layer of the support film of the raw film to be conveyed. are

By using the manufacturing method and manufacturing apparatus of the present invention, a polarizer with few optical defects can be manufactured.

1 is a partially omitted plan view of a polarizer of the present invention; FIG. FIG. 2 is a cross-sectional view of a polarizer according to one embodiment (a cross-sectional view taken along line II-II in FIG. 1); Sectional drawing of the polarizer which concerns on other embodiment. 1 is a cross-sectional view of a laminated polarizing film according to one embodiment; FIG. Sectional drawing of the laminated polarizing film which concerns on other embodiment. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic side view showing an apparatus for manufacturing a polarizer (laminated polarizing film) of the present invention; The reference side view which shows the washing|cleaning apparatus of a manufacturing apparatus. The enlarged side view which shows a 1st coating roll. The enlarged side view which shows a 2nd coating roll. The front view of a coating roll. FIG. 11 is an enlarged plan view of the XI section of FIG. 10 showing a plurality of recesses formed on the outer peripheral surface of the coating roll; FIG. 12 is a cross-sectional view taken along line XII-XII in FIG. 11; The perspective view which shows the liquid removal part which blows air. The enlarged side view which shows the 1st coating roll which concerns on a modification. The enlarged side view which shows the 2nd coating roll which concerns on a modification.

In this specification, the numerical range represented by "lower limit value X to upper limit value Y" means the lower limit value X or higher and the upper limit value Y or lower. When a plurality of numerical ranges are described separately, an arbitrary lower limit value and an arbitrary upper limit value can be selected, and "an arbitrary lower limit value to an arbitrary upper limit value" can be set.
Each figure is for reference only, and it should be noted that the dimensions, scales and shapes of members and the like shown in each figure may differ from the actual ones.

[Polarizer and laminated polarizing film]
FIG. 1 is a partially omitted plan view of a polarizer obtained by the manufacturing method of the present invention.
The polarizer obtained by the production method of the present invention has a long strip shape. This long belt-shaped polarizer is cut into an appropriate shape and used for various purposes.
Further, a long strip-shaped laminated polarizing film can be obtained by laminating an arbitrary film such as a protective film on the long strip-shaped polarizer. Long strip-shaped laminated polarizing films are also cut into appropriate shapes and used for various purposes.

FIG. 2 is a cross-sectional view of the polarizer 1 taken along line II-II in FIG.
Referring to FIG. 2, polarizer 1 according to one embodiment has support film 11 and hydrophilic polymer layer 12 laminated on one surface of support film 11 . The hydrophilic polymer layer 12 is dyed with a dichroic substance. Such a hydrophilic polymer layer 12 has polarizing properties.
FIG. 3 is a cross-sectional view of a polarizer 1 according to another embodiment. This cross-sectional view is also a cross-sectional view of the polarizer 1 of another embodiment taken along the line II-II of FIG.
Referring to FIG. 3, a polarizer 1 of another embodiment is composed of a hydrophilic polymer film 13 dyed with a dichroic substance. Such a hydrophilic polymer film 13 has polarizing properties.

Here, the polarizer is an optical film having a property of transmitting light (polarized light) vibrating only in one specific direction and blocking light vibrating in other directions (this property is a polarization property). say.
In the case of the laminate having the support film 11 and the hydrophilic polymer layer 12 shown in FIG. 2, the hydrophilic polymer layer 12 has polarizing properties as described above, but the support film 11 does not have polarizing properties. There are many. Strictly interpreting the laminate, it can be said that the hydrophilic polymer layer 12 is a polarizer. ing.

The polarizer 1 shown in FIGS. 2 and 3 is formed into an appropriate shape as described above and used for various purposes.
In addition, one or two or more arbitrary appropriate films may be further laminated on the polarizer 1 . Any suitable film that is laminated to the polarizer 1 is hereinafter sometimes referred to as an "optional film".
4 and 5 are cross-sectional views of a laminated polarizing film 2 in which an arbitrary film is laminated on a polarizer 1. FIG. 4 and 5 show a protective film as an arbitrary film.
Referring to FIG. 4, a laminated polarizing film 2 according to one embodiment includes a polarizer 1 composed of a support film 11 and a hydrophilic polymer layer 12 having polarizing properties, and the hydrophilic polymer layer 12 of the polarizer 1. , and a protective film 22 laminated via an adhesive layer 21 .
Referring to FIG. 5, a laminated polarizing film 2 according to another embodiment includes a polarizer 1 made of a hydrophilic polymer film 13 having polarizing properties, and a first adhesive layer 23 on one side of the polarizer 1. and a second protective film 26 laminated on the opposite side of the polarizer 1 with a second adhesive layer 25 interposed therebetween.
Although not shown, the laminated polarizing film 2 may be laminated with further protective films independently. Also, the polarizer 1 or the laminated polarizing film 2 may be laminated with optional films such as a retardation film, a brightness enhancement film, and a transparent conductive film independently of each other.

<Optional film>
The protective film is a film for protecting the polarizer. As will be described later, the protective film is laminated to the polarizer after the polarizer is manufactured.
The protective film is a film used for the purpose of protecting an object to be protected, such as a polarizer, from scratches and stains. Examples of protective films include olefin resins such as polyethylene and polypropylene; ester resins such as polyethylene terephthalate; amide resins such as nylon 6; vinyl polymers such as polyvinyl chloride and vinyl chloride-vinyl acetate copolymer; Cellulose-based resins such as cellulose triacetate and cellulose diacetate; acrylic-based resins such as polymethyl methacrylate; styrene-based resins; carbonate-based resins; polyarylate-based resins;
The retardation film is an optical film exhibiting optical anisotropy. Examples of the retardation film include anisotropic films such as 1/2λ plate and 1/4λ plate.
The brightness enhancement film is an optical film that transmits only specific polarized light and reflects other polarized light.

<Adhesive layer>
The adhesive layer is a solidified layer of adhesive that is interposed between and adheres the two films.
The adhesive layer is composed of, for example, an active energy ray-curable adhesive such as an ultraviolet curable adhesive, a solvent volatile adhesive, or the like.

[Production equipment for polarizer and laminated polarizing film]
The polarizer manufacturing apparatus of the present invention includes a conveying device that conveys a long strip-shaped original film containing a hydrophilic polymer in the longitudinal direction, a wet processing device that dyes and stretches the original film with a dyeing solution, a cleaning device arranged downstream of the wet processing device and cleaning the original film with a cleaning liquid. Preferably, the polarizer manufacturing apparatus further includes a drying device arranged downstream of the washing device and drying the original film.

In the present invention, the cleaning device has a coating roll having a plurality of concave portions on the outer peripheral surface thereof which can be filled with a cleaning liquid, and the outer peripheral surface of the coating roll contacts one surface of the transported raw film. The coating roll is arranged as follows.
A film stock has two surfaces, one side of the film stock refers to one of the surfaces, and the opposite side of the film stock refers to the other surface.
Further, the downstream side refers to the direction of transport of the film, and the upstream side refers to the opposite side (the side opposite to the direction of transport of the film).

The apparatus for producing a polarizer of the present invention preferably employs a system in which a series of steps of wet-treating a raw film, washing, and drying to obtain a polarizer are performed on one production line.
Furthermore, in the present invention, after manufacturing the polarizer, an optional film such as a protective film may be adhered to the polarizer to manufacture a laminated polarizing film.
The laminated polarizing film may be manufactured by (a) a method of winding the polarizer on a roll after manufacturing the polarizer, unwinding the polarizer wound on the roll, and laminating and bonding the arbitrary film, or ( b) After manufacturing the polarizer, a method of laminating and adhering the optional film to the polarizer on one manufacturing line may be used.

FIG. 6 shows a preferred configuration example of a laminated polarizing film manufacturing apparatus A (an apparatus for serially manufacturing a polarizer to a laminated polarizing film).
Referring to FIG. 6, a manufacturing apparatus A for a laminated polarizing film containing a polarizer includes a conveying device 3 that conveys a raw film, a polarizer, and an arbitrary film, a polarizer production zone for producing the polarizer, and a a film lamination zone for adhering at least one film to the polarizer.
The polarizer production zone includes a wet processing device 4 for wet-processing the raw film, a cleaning device 5 for cleaning the raw film after the wet processing, a drying device 8 for drying the raw film after cleaning, have
The film lamination zone has a lamination device 9 for laminating an arbitrary film onto the polarizer obtained in the polarizer production zone.

・Polarizer production zone <wet processing equipment>
The wet processing apparatus 4 has, in order from the upstream side, a delivery section 41 around which the original film B is wound, and a wet processing section. The wet processing section has a swelling treatment tank 42, a dyeing treatment tank 43, a cross-linking treatment tank 44, and a stretching treatment tank 45 in order from the upstream side.
In addition, the wet processing section is not limited to being composed of the swelling treatment tank 42, the dyeing treatment tank 43, the cross-linking treatment tank 44, and the stretching treatment tank 45. For example, the wet treatment part may not have the swelling treatment tank 42. Alternatively, the drawing treatment tank 45 may not be provided. If the stretching tank 45 is not provided, the raw film B is stretched in a tank such as the dyeing tank 43 . Also, the wet processing section may have another processing bath such as a conditioning processing bath.
The original film B wound around the feeding section 41 is conveyed to a wet processing section (downstream side) such as a swelling processing tank 42 by a conveying device 3 having guide rolls 31 and the like. The white arrow in FIG. 6 indicates the traveling direction (conveying direction) of the film. The white arrows in FIGS. 7 to 9 and 13 also indicate the advancing direction (transporting direction) of the transported film.

The original film B has a long strip shape. In this specification, a long belt shape refers to a rectangular shape in which the length in the longitudinal direction is sufficiently larger than the length in the lateral direction (direction orthogonal to the longitudinal direction). The longitudinal length of the long strip is, for example, 10 m or longer, preferably 50 m or longer.
A long belt-like film containing a hydrophilic polymer is used as the original film B.
As the original film B, for example, a laminate comprising a long belt-like support film and a hydrophilic polymer layer laminated on one side of the support film, or a hydrophilic polymer film can be used. When the laminate is used as the original film B, the polarizer 1 shown in FIG. 2 is obtained. When the hydrophilic polymer film is used as the original film B, the polarizer 1 shown in FIG. 3 is obtained.

<Film raw fabric made of laminate>
The hydrophilic polymer layer constituting the laminate can be formed by applying a coating liquid containing a hydrophilic polymer to one surface of the support film and drying the coating liquid.
A laminate (original film) comprising a support film and a hydrophilic polymer layer may be stretched. For example, the support film may be auxiliary stretched after or while the coating solution is applied to the support film. The stretching may be performed in one stage or in multiple stages. For example, the laminate may be auxiliary stretched in the air (dry process) to form a film raw fabric, and the film raw fabric may be dyed and stretched in the wet processing step described below.

The support film may be a colorless and transparent resin film, preferably an optically isotropic resin film. Examples of the support film include ester resins such as polyethylene terephthalate resins; cycloolefin resins such as norbornene resins; olefin resins such as polypropylene; amide resins; films. Among these, the support film is preferably a norbornene-based resin or a film formed from an amorphous polyethylene terephthalate-based resin, and in particular, amorphous (not crystallized or hardly crystallized) polyethylene A terephthalate-based resin is more preferable. Specific examples of the amorphous polyethylene terephthalate-based resin include a copolymer further containing isophthalic acid as a dicarboxylic acid, a copolymer further containing cyclohexanedimethanol as a glycol, and the like.
The thickness of the support film is not particularly limited, and is, for example, 20 μm to 300 μm, preferably 50 μm to 200 μm. However, the thickness is the thickness of the support film before wet-processing the original film B (original film B). If the thickness is less than 20 µm, it may be difficult to form the hydrophilic polymer layer. If the thickness exceeds 300 μm, for example, in wet processing, it may take a long time for the support film to absorb water, and an excessive load may be required to stretch the support film.

Hydrophilic polymers include polyvinyl alcohol (PVA) resins and ethylene-vinyl alcohol copolymers. Polyvinyl alcohol (PVA) is obtained by saponifying polyvinyl acetate. An ethylene-vinyl alcohol copolymer is obtained by saponifying an ethylene-vinyl acetate copolymer. The saponification degree of the PVA-based resin is usually 85 mol% to 100 mol%, preferably 95.0 mol% to 99.95 mol%, more preferably 99.0 mol% to 99.93 mol%. be. The degree of saponification can be determined according to JIS K 6726:1994. By using a PVA-based resin having such a degree of saponification, a polarizer having excellent durability can be obtained.

The average degree of polymerization of the PVA-based resin is usually 1,000 to 10,000, preferably 1,200 to 5,000, more preferably 1,500 to 4,500. The average degree of polymerization can be determined according to JIS K 6726-1994.
As a coating liquid containing a hydrophilic polymer, typically, a solution obtained by dissolving the PVA-based resin in a solvent can be used. Examples of the solvent include water, dimethylsulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, polyhydric alcohols such as trimethylolpropane, and amines such as ethylenediamine and diethylenetriamine. These can be used singly or in combination of two or more. Among these, water is preferred. The concentration of the PVA-based resin in the solution is preferably 3 to 20 parts by weight with respect to 100 parts by weight of the solvent. A coating liquid having such a resin concentration can be applied substantially uniformly to the support film.

Additives may be added to the coating liquid. Examples of additives include plasticizers and surfactants. Examples of plasticizers include polyhydric alcohols such as ethylene glycol and glycerin. Surfactants include, for example, nonionic surfactants. These additives can be used for the purpose of further improving the uniformity, dyeability and stretchability of the obtained PVA-based resin layer (hydrophilic polymer layer). Moreover, you may use an easy-adhesion component as an additive, for example. Adhesion between the support film and the PVA-based resin layer (hydrophilic polymer layer) can be improved by using the easy-adhesion component.

Any appropriate method can be adopted as a method for applying the coating liquid. Examples thereof include roll coating, spin coating, wire bar coating, dip coating, die coating, curtain coating, spray coating, and knife coating (comma coating, etc.).
The temperature for applying and drying the coating liquid is preferably 50° C. or higher. The thickness of the PVA-based resin layer (hydrophilic polymer layer) is preferably 3 μm to 40 μm, more preferably 5 μm to 20 μm. However, the thickness is the thickness of the PVA-based resin layer (hydrophilic polymer layer) before wet-processing the original film B (original film B).

<Film raw fabric made of hydrophilic polymer film>
The hydrophilic polymer film is obtained by forming a hydrophilic polymer into a film. Examples of hydrophilic polymers include PVA-based resins and ethylene-vinyl alcohol copolymers, as described above. The thickness of the hydrophilic polymer film is not particularly limited, but is, for example, 15 μm to 110 μm, preferably 20 μm to 100 μm.

<Swelling treatment tank>
The swelling treatment tank 42 is a treatment tank containing a swelling liquid 421 . The swelling liquid 421 causes the original film B to swell. As the swelling liquid 421, for example, water can be used. Furthermore, water to which an appropriate amount of an iodine compound such as glycerin or potassium iodide is added may be used as the swelling liquid. When glycerin is added, its concentration is preferably 5% by weight or less, and when adding an iodine compound such as potassium iodide, its concentration is preferably 10% by weight or less.

<Dyeing tank>
The dyeing treatment tank 43 is a treatment tank containing a dyeing liquid 431 . The dyeing liquid 431 dyes the hydrophilic polymer of the original film B. FIG. Examples of the staining liquid 431 include a solution containing a dichroic substance as an active ingredient. Dichroic substances include iodine and organic dyes. Preferably, a solution of iodine dissolved in a solvent can be used as the staining solution 431 . Water is generally used as the solvent, but an organic solvent compatible with water may be added. The concentration of iodine in the dyeing solution is not particularly limited, but is preferably 0.01% to 10% by weight, more preferably 0.02% to 7% by weight, and 0.025% by weight. More preferably ~5% by weight. In order to further improve the dyeing efficiency, an iodine compound may be added to the dyeing solution, if necessary. The iodine compound is a compound containing iodine and an element other than iodine in the molecule. Barium iodide, calcium iodide, tin iodide, titanium iodide and the like can be mentioned, and potassium iodide is preferably used.

<Cross-linking treatment tank>
The cross-linking treatment tank 44 is a treatment tank containing a cross-linking liquid 441 . The cross-linking liquid 441 cross-links the dyed original film B. FIG. As the cross-linking liquid 441, a solution containing a boron compound as an active ingredient can be used. For example, as the cross-linking liquid 441, a solution in which a boron compound is dissolved in a solvent can be used. Water is generally used as the solvent, but an organic solvent compatible with water may be added. Boron compounds include boric acid and borax. The concentration of the boron compound in the cross-linking solution is not particularly limited, but is preferably 1% to 10% by weight, more preferably 2% to 7% by weight, and 2% to 6% by weight. is more preferred. Furthermore, since a polarizer having uniform optical properties can be obtained, the aforementioned iodine compound may be added to the cross-linking solution, if necessary.

<Stretching tank>
The drawing treatment tank 45 is a treatment tank containing a drawing liquid 451 .
The stretching liquid 451 is not particularly limited, but for example, a solution containing a boron compound as an active ingredient can be used. As the drawing liquid 451, for example, a solution in which a boron compound and, if necessary, various metal salts, a zinc compound, and the like are dissolved in a solvent can be used. Water is generally used as the solvent, but an organic solvent compatible with water may be added. Although the concentration of the boron compound in the drawing liquid is not particularly limited, it is preferably 1 wt % to 10 wt %, more preferably 2 wt % to 7 wt %. From the viewpoint of suppressing the elution of iodine adsorbed on the original film B, an iodine compound may be added to the stretching liquid as necessary.

In the illustrated example, the wet processing section has a swelling treatment tank 42, a dyeing treatment tank 43, a cross-linking treatment tank 44, and a stretching treatment tank 45, but one or two of these treatment tanks may be omitted. . On the other hand, the wet processing section may further have a conditioning processing tank (not shown). The adjustment treatment tank is a treatment tank containing adjustment liquid. Although not shown in FIG. 6, the adjustment treatment tank is provided between the cross-linking treatment tank 44 and the stretching treatment tank 45, or between the stretching treatment tank 45 and the washing treatment tank 51, which will be described later. The adjustment liquid is a solution for adjusting the hue of the film, and may be a solution containing the above-described iodine compound as an active ingredient.

<Washing device>
The washing device 5 is a device for washing the original film B that has been dyed and stretched in the wet processing device 4 . A processing liquid such as a dyeing liquid or a cross-linking liquid (the processing liquid is a general term for each liquid such as a dyeing liquid used in wet processing) and foreign matter are attached to the wet-processed raw film B. . Foreign matter includes film residue, crystallized substances of processing liquid components, and the like. The cleaning device 5 is a device for removing the above-mentioned foreign substances and the like adhering to the original film B. As shown in FIG.
FIG. 7 is a side view showing the vicinity of the cleaning device in the manufacturing apparatus A for reference.
6 and 7, the cleaning device 5 has a coating roll 6 for applying cleaning liquid to the original film B, preferably further has a cleaning treatment tank 51, and more preferably has a cleaning treatment tank 51. It further has a portion 52 .
Specifically, the cleaning apparatus 5 of the preferred embodiment includes a cleaning treatment tank 51 disposed downstream of the wet processing apparatus 4 and a coating apparatus for applying a cleaning liquid to the original film B pulled out from the cleaning treatment tank 51. It has a cleaning roll 6 and a liquid removing section 52 for removing the cleaning liquid adhering to the original film B.

The cleaning processing tank 51 is a processing tank containing a cleaning liquid 511 . The washing liquid 511 washes the raw film B after stretching. The cleaning liquid 511 is a liquid for cleaning the treatment liquid such as the dyeing liquid adhering to the original film B. FIG. As the cleaning liquid, water such as ion-exchanged water, distilled water, and pure water; water containing an iodine compound; and the like can be used. Water containing an iodine compound is preferably used as the cleaning liquid because the polarizing properties of the polarizer do not deteriorate. Water containing an iodine compound is obtained by dissolving an iodine compound in water such as pure water. As the iodine compound, a compound containing iodine and an element other than iodine in the molecule may be used as described above, but potassium iodide is preferably used.
The concentration of the iodine compound in the water (cleaning liquid) containing the iodine compound is not particularly limited, but is preferably 1% to 7% by weight, more preferably 2% to 5% by weight.
The cleaning tank 51 is provided with an inflow path 55 for inflowing the cleaning liquid into the cleaning tank 51 and an outflow path 56 for flowing out the cleaning liquid in the cleaning tank 51 .

A pinch roll 32 included in the conveying device 3 is arranged on the downstream side of the cleaning treatment tank 51 . The original film B pulled out from the cleaning tank 51 is conveyed to the coating roll 6 through the pinch rolls 32 and the guide rolls 31 . A shower unit 53 for spraying a cleaning liquid may be provided between the cleaning tank 51 and the pinch rolls 32 as necessary. The shower unit 53 sprays the cleaning liquid onto one surface and/or the opposite surface of the original film B, for example.

The coating roll 6 is arranged between the cleaning tank 51 and the drying device 8 .
The coating roll 6 is provided to apply a cleaning liquid to one surface of the raw film B after wet processing. Preferably, the coating rolls 6 are provided for applying the cleaning liquid to one surface and the opposite surface of the original film B (the opposite surface is the surface opposite to the one surface).
Hereinafter, the case where two coating rolls are provided will be exemplified, one coating roll being referred to as the "first coating roll" and the other coating roll being referred to as the "second coating roll". , are collectively referred to as "coating rolls".
FIG. 8 is an enlarged side view of the first coating roll 6a, and FIG. 9 is an enlarged side view of the second coating roll 6b.

The coating roll 6 (the first coating roll 6a and the second coating roll 6b) has a plurality of recesses 61 that can be filled with a cleaning liquid on its outer peripheral surface. The coating roll 6 is attached with a supply unit 7 for supplying a cleaning liquid to the concave portions 61 thereof.
The coating roll 6 has a columnar shape with a plurality of recesses 61 on its outer peripheral surface, and has a rotation support shaft at the center of the column. The coating roll 6 is rotatable around a rotation support shaft 63 . The coating roll 6 is arranged so that the outer peripheral surface of the coating roll 6 is in contact with the surface of the raw film B being transported.

The coating roll 6 may rotate in the forward direction of the original film B and apply the cleaning liquid to the original film B. Alternatively, the coating roll 6 may rotate in the opposite direction to the conveying direction of the original film B and apply the cleaning liquid to the original film B. A method in which the original fabric B is coated with a cleaning liquid may also be used. Since the foreign matter adhering to the surface of the original film B can be removed by scraping it off, the coating roll 6 can also be rotated in the direction opposite to the transport direction of the original film B to apply the cleaning liquid to the original film B. good. Hereinafter, the method of rotating in the opposite direction is referred to as a reverse method.
8 and 9 show a coating roll 6 of reverse type. A thin arrow attached to the coating roll 6 in FIGS. 8 and 9 indicates the direction of rotation of the coating roll 6 .

10 to 12 are detailed views of the coating rolls 6 (the first coating roll 6a and the second coating roll 6b). The coating roll 6 shown in FIGS. 10 to 12 is a so-called gravure roll, and has a plurality of recesses 61 (so-called cells) formed on its outer peripheral surface. The recess 61 is a recessed portion that can be filled with cleaning liquid. A protrusion 62 is formed at the boundary between the adjacent recesses 61 . In addition, the convex portion 62 means a portion that protrudes relatively in relation to the concave portion 61 .
By bringing the outer peripheral surface of the coating roll 6, in which a plurality of recesses 61 are densely arranged, into contact with the original film B, the cleaning liquid stored in each of the recesses 61 is transferred to the surface of the original film B. .
The planar view shape of the recess 61 is, for example, a substantially regular hexagonal shape (substantially honeycomb shape) as shown in FIG. 11 . However, the planar view shape of the concave portion 61 is not limited to this, and may be a planar view approximately rhombus (including approximately square), approximately circular shape, or the like.
FIG. 11 shows an example in which recesses 61 that are approximately regular hexagons in a plan view are arranged approximately evenly at an angle of 60 degrees. Although not shown, the recesses 61 may be arranged substantially evenly at an angle of 30 degrees or 45 degrees. The angle is defined as the angle (minimum angle) between the line connecting the center points of two adjacent recesses 61 and the axial direction of the rotation support shaft 63 of the coating roll 6 .

The opening width and depth of the recess 61 are not particularly limited and can be set as appropriate.
The number of lines of the concave portions 61 (the number of lines of the cells of the gravure roll) is not particularly limited, and is, for example, 250 lines/inch to 2500 lines/inch, preferably 400 lines/inch to 2000 lines/inch, More preferably 500 lines/inch to 1700 lines/inch, and still more preferably 700 lines/inch to 1400 lines/inch.
In the present invention, by using the coating roll 6 having the concave portions 61 formed with a relatively large number of lines, a relatively small amount of cleaning agent can be applied to the surface of the original film B substantially evenly.
The volume of the concave portion 61 is inversely proportional to the number of lines, and the larger the number of lines, the smaller the volume of each concave portion 61 . There is a correlation between the volume of the concave portion 61 and the number of lines, and the volume of the concave portion 61 is generally determined by the number of lines.

Referring to FIG. 7, a pair of tension rolls 33 are arranged on both sides of the coating roll 6 (first coating roll 6a and second coating roll 6b). The raw film B to be conveyed is pressed toward the coating roll 6 by the pair of tension rolls 33 and comes into contact with the outer peripheral surface of the coating roll 6 . Since it is sufficient that the cleaning liquid can be applied to the surface of the original film B by the coating roll 6, the original film B is brought into contact with the outer peripheral surface of the coating roll 6 with a relatively small contact pressure.
In the illustrated example, the pair of tension rolls 33 are arranged horizontally. In this case, the original film B is conveyed substantially horizontally between the pair of tension rolls 33, and the cleaning liquid is applied to the original film B being conveyed substantially horizontally. However, it is not limited to the case where the cleaning liquid is applied using the coating roll 6 to the film material B that is conveyed substantially horizontally, and the film is conveyed in a vertical direction or in a direction inclined at an acute angle with respect to the horizontal. The cleaning liquid may be applied to the raw film B using the coating roll 6 .

7 to 9, supply unit 7 fills a plurality of concave portions 61 of coating roll 6 (first coating roll 6a and second coating roll 6b) with cleaning liquid.
The supply unit 7 attached to the first coating roll 6a includes, for example, an open chamber 71a that supplies the cleaning liquid to the outer peripheral surface of the first coating roll 6a, and a It has a doctor blade 72a in contact with the convex portion 62, an inflow path 73a for inflowing the cleaning liquid into the chamber 71a, and an outflow path 74a for outflowing the cleaning liquid from the chamber 71a.
The supply unit 7 attached to the second coating roll 6b includes, for example, an open chamber 71b that supplies the cleaning liquid to the outer peripheral surface of the second coating roll 6b, and a It has a doctor blade 72b in contact with the convex portion 62, an inflow path 73b for inflowing the cleaning liquid into the chamber 71b, and an outflow path 74b for outflowing the cleaning liquid from the chamber 71b.

The chambers 71a and 71b are arranged on the rear side in the rotation direction of the coating roll 6 with reference to the portion where the cleaning liquid is applied to the original film B. As shown in FIG.
The chambers 71a and 71b are open on the coating roll 6 side. By rotating the first coating roll 6a and the second coating roll 6b (coating rolls 6) while immersed in the cleaning liquid in the chambers 71a and 71b, the cleaning liquid is supplied to the concave portions 61 of the rolls 6a and 6b. It has become. That is, the chambers 71a and 71b are configured to supply the cleaning liquid to the outer peripheral surface of the coating roll 6 from the open portions while filling the interior with the cleaning liquid. Such chambers 71a and 71b are generally called open chambers.
In addition, in FIGS. 8 and 9, for the sake of convenience, the portions where the cleaning liquid is present are indicated by thin oblique lines (the same applies to FIGS. 14 and 15).
After the coating roll 6 comes into contact with the surface of the original film B, foreign matter attached to the surface of the original film B may transfer to the outer peripheral surface of the coating roll 6 . Even in such a case, as the coating roll 6 rotates, the outer peripheral surface to which the foreign matter is transferred is immersed in the cleaning liquid in the chambers 71a and 71b and comes into contact with the doctor blades 72a and 72b. , 71b.

8 and 9, the chambers 71a and 71b attached to the first coating roll 6a and the second coating roll 6b respectively have a double structure consisting of an inner container 711 and an outer container 712. there is The cleaning liquid overflows from the upper end of the inner container 711 , and the overflowed cleaning liquid is stored in the outer container 712 .
Referring to FIG. 7, an outflow path 74a of chamber 71a is connected to storage tank 75 . The cleaning liquid flowing out from the chamber 71a of the first coating roll 6a is stored in the storage tank 75 through the outflow path 74a. Also, the outflow path 56 of the cleaning treatment tank 51 is connected to the storage tank 75 . The cleaning liquid flowing out of the cleaning tank 51 is stored in the storage tank 75 through the outflow path 56 .

The storage tank 75 has a supply path 751 for feeding the cleaning liquid and a replenishment path 752 for replenishing the storage tank 75 with the cleaning liquid. The supply path 751 is provided with a pump 753 for pressurizing and sending the cleaning liquid, and a filter 754 for removing foreign substances contained in the cleaning liquid. The supply path 751 is connected to the inflow path 73a of the chamber 71a and the inflow path 55 of the cleaning treatment bath 51 via branch paths. The cleaning liquid in the storage tank 75 is supplied to the inner container 711 of the chamber 71a through the supply path 751, the branch path and the inflow path 73a, and is supplied to the cleaning tank 51 through the supply path 751, the branch path and the inflow path 55. . Therefore, the cleaning liquid for the first coating roll 6a and the cleaning liquid for the cleaning treatment tank 51 are supplied from the same storage tank 75. As shown in FIG. In other words, the first coating roll 6a and the cleaning tank 51 clean the original film B using the same cleaning liquid.

Specifically, referring to FIGS. 7 and 8, the cleaning liquid flowing out from the inner container 711 of the chamber 71a is temporarily stored in the outer container 712 and sent to the storage tank 75 through the outflow path 74a. Also, the cleaning liquid flowing out of the cleaning treatment tank 51 is sent to the storage tank 75 through the outflow path 56 . In the storage tank 75, the concentration of the cleaning liquid is adjusted by adding new cleaning liquid sent from the replenishment path 752 to the returned cleaning liquid (the cleaning liquid returned from the cleaning tank 51 and the chamber 71a). . After that, the cleaning liquid in the storage tank 75 is supplied to the inner container 711 of the chamber 71a and the cleaning tank 51 through the supply path 751 and the inflow path 73a and the inflow path 55 by the action of the pump 753 . At this time, the filter 754 removes impurities such as foreign substances and crystals in the cleaning liquid. In this manner, both the cleaning liquid in the cleaning tank 51 and the first coating roll 6a are circulated through the storage tank 75. As shown in FIG.

As the pump 753, for example, conventionally known pumps such as gear pumps, diaphragm pumps, plunger pumps, and snake pumps can be used. As the filter 754, one having a performance of filtering out impurities such as foreign matter is used. By providing the filter 754, a clean cleaning liquid is sent to the cleaning tank 51 and the first coating roll 6a. Note that the outflow path 74a and the outflow path 56 may also be provided with a filter and/or a pump, if necessary.
The first coating roll 6a and the cleaning tank 51 are not limited to being supplied with the cleaning liquid from the same storage tank 75, and the first coating roll 6a and the cleaning tank 51 are stored independently and separately. The cleaning liquid may be supplied from a tank.

On the other hand, referring to FIGS. 7 and 9, the outflow path 74b of the chamber 71b of the second coating roll 6b (not connected to the storage tank 75) is connected to a drainage facility (not shown). The cleaning liquid overflowing from the upper end of the inner container 711 is sent from the outer container 712 to the drainage facility through the outflow path 74b. Also, an inflow path 73b of the chamber 71b is connected to a cleaning liquid supply source (not shown).
In FIGS. 7 to 9, the flows of the cleaning liquid in the inflow paths 55, 73a, 73b, the outflow paths 56, 74a, 74b, and the supply path 751 are indicated by thick arrows superimposed on each path.

As described above, the first coating roll 6a applies the cleaning liquid to one surface of the original film B, and the second coating roll 6b applies the cleaning liquid to the opposite side of the original film B. When a laminate consisting of a support film and a hydrophilic polymer layer is used as the original film B, one surface of the original film B becomes one surface of the hydrophilic polymer layer, and the opposite surface of the original film B is This is the opposite side of the support film. One surface of the hydrophilic polymer layer is the surface opposite to the surface in contact with the support film, and the opposite surface of the support film is the surface opposite to the surface in contact with the hydrophilic polymer layer.
FIGS. 8 and 9 show an example of using a laminate composed of a support film B11 and a hydrophilic polymer layer B12 as the original film B. FIG.
For example, the cleaning liquid is applied to one surface of the hydrophilic polymer layer B12 by the first coating roll 6a (see FIG. 8). Further, the cleaning liquid is applied to the opposite surface of the support film B11 by the second coating roll 6b (see FIG. 9).
The 1st coating roll 6a and the 2nd coating roll 6b are arranged side by side in the conveyance direction of the film original fabric B in order. After the cleaning liquid is applied by the first coating roll 6a to one side of the original film B conveyed through the guide roll 31, the cleaning liquid is applied to the opposite side of the original film B by the second coating roll 6b. be.
The first coating roll 6a applies the cleaning liquid to the opposite surface of the original film B (the opposite surface of the support film B11), and the second coating roll 6b applies the cleaning liquid to one surface of the original film B (hydrophilic polymer layer B12). (one side) may be changed so that the cleaning liquid is applied. Alternatively, the first coating roll 6a and the second coating roll 6b may apply the cleaning liquid to one surface and the opposite surface of the original film B at the same time.

As the washing liquid applied by the coating roll 6, water such as ion-exchanged water, distilled water, and pure water; water containing an iodine compound; Pure water is suitable for cleaning because it does not contain impurities. On the other hand, if water is allowed to adhere to the hydrophilic polymer layer or hydrophilic polymer film, the polarizing properties of the finally obtained polarizer may deteriorate. For this reason, for the original film B comprising the hydrophilic polymer layer B12 and the support film B11 described above, water containing an iodine compound is used as a cleaning liquid to be applied to one surface of the hydrophilic polymer layer B12, and the opposite surface of the support film B11 is used. It is preferable to use pure water as a cleaning liquid to be applied to the substrate. In this preferred example, water containing an iodine compound is applied to one side of the original film B (one side of the hydrophilic polymer layer B12) by the first coating roll 6a, and water such as pure water is applied to the second coating roll. 6b is applied to the opposite surface of the raw film B (opposite surface of the support film B11).
For example, by using water containing an iodine compound as the cleaning liquid in the storage tank 75, the water containing the iodine compound (cleaning liquid) is used to clean the hydrophilic polymer of the original film B in the cleaning tank 51 and the first coating roll 6a. Layer B12 can be washed. On the other hand, the support film B11 of the original film B can be washed by using water such as pure water as the washing liquid for the second coating roll 6b.

In addition, when the original film B is made of a hydrophilic polymer film, the cleaning liquid applied to one side and the opposite side of the original film B both contain an iodine compound so as not to reduce the polarization characteristics. Water is preferred. In this case, it is preferable to connect the inflow path 73b and the outflow path 74b of the chamber 71b of the second coating roll 6b shown in FIGS. 7 and 9 to the storage tank 75 in the same manner as the first coating roll 6a.
The concentration of the iodine compound in the water containing the iodine compound (washing liquid for the coating roll 6) is not particularly limited, but is preferably 1 wt% to 7 wt%, more preferably 2 wt% to 5 wt%. .
When the cleaning liquid for the coating roll 6 is water containing an iodine compound, the cleaning liquid may be the same as that used in the cleaning tank 51, or may be different from that used in the cleaning tank 51. . As described above, it is preferable to use water containing the same iodine compound for the coating roll 6 and the cleaning treatment tank 51 because of ease of management.

The liquid removing section 52 of the cleaning device 5 is provided mainly for removing the cleaning liquid adhering to the surface of the original film B. As shown in FIG. By removing the cleaning liquid by the liquid removing section 52, it is difficult for the cleaning liquid component to remain on the surface of the original film B, and a polarizer having excellent polarization characteristics can be obtained.
The liquid removing unit 52 is preferably of a non-contact type (a method in which members do not directly contact the original film B). For example, air is used as the removing means of the liquid removing section 52 .
FIG. 13 shows a configuration example of the liquid removing section 52 using air. FIG. 13 shows the vicinity of the second liquid removing section 52b of FIG. 7 for reference.

Referring to FIG. 13, the liquid removing unit 52 is composed of a blower unit 522 having a slit-shaped discharge port 521 for blowing air, and a blower (not shown) that supplies air to the blower unit 522 through a duct 523. Configured. 13 and 7 indicate the direction of the air.
The slit-shaped discharge port 521 extends over the entire width of the raw film B. As shown in FIG. The discharge port 521 is arranged substantially parallel to the axis of the guide roll 31, but may be arranged so as to be inclined with respect to the axis. The slit width of the ejection port 521 is not particularly limited, and is, for example, 0.03 mm to 3 mm, preferably 0.1 mm to 1 mm.

The liquid removing section 52 is provided at an appropriate location, preferably at least downstream of the coating roll 6, more preferably between the cleaning tank 51 and the coating roll 6 and between the coating roll 6 and the coating roll 6. and the drying device 8.
Referring to FIG. 7, a first liquid removing portion 52a is arranged in the nip roll 32. As shown in FIG. The first liquid removing section 52a blows air to the outer peripheral surface on one side and the outer peripheral surface on the other side of the nip roll 32 . The surface of the original film B pulled out from the cleaning tank 51 is coated with a cleaning liquid, and the cleaning liquid adheres to the nip roll 32. Blow away with . The first liquid removing portion 52a can prevent the cleaning liquid from reattaching to the original film B from the nip roll 32 .

The second liquid removing section 52b is arranged corresponding to the guide roll 31 on the downstream side of the nip roll 32, and removes the cleaning liquid adhering to one surface of the original film B by blowing it off with air.
The third liquid removing section 52c and the fourth liquid removing section 52d are arranged corresponding to each guide roll 31 between the first coating roll 6a and the second coating roll 6b. A cleaning liquid is applied to one surface of the original film B by the first coating roll 6a. Blow off the cleaning liquid adhering to the surface with air to remove it.

The fifth liquid removing section 52e, the sixth liquid removing section 52f and the seventh liquid removing section 52g are arranged corresponding to each guide roll 31 between the second coating roll 6b and the drying device 8. As shown in FIG. The cleaning liquid is applied to the opposite side of the original film B by the second coating roll 6b. Blow off the cleaning liquid adhering to the surface with air to remove it.
In particular, it is preferable that a plurality of liquid removing units 52 be arranged immediately upstream of the drying device 8 . In the illustrated example, two liquid removing sections 52 (sixth and seventh liquid removing sections 52f and 52g) are arranged immediately upstream of the drying device 8. As shown in FIG. By densely arranging a plurality of liquid removing sections 52 immediately before entering the drying device 8 , the original film B to which almost no cleaning liquid is adhered can be introduced into the drying device 8 .
The direction of the air blown onto the raw film B (blowing direction) may be a direction substantially orthogonal to the surface (one side and the opposite side) of the raw film B, or an acute angle to the surface of the raw film B. It may be in the direction of Preferably, the direction of the air is opposite to the conveying direction of the original film B and forms an acute angle with the surface of the original film B, as shown in the illustrated example.

<Drying device>
A drying device 8 is provided downstream of the washing device 5 . The drying device 8 is provided to dry the raw film B after washing.
One drying device 8 may be provided, or two or more drying devices may be provided side by side in the transport direction of the original film B. The drying device 8 has, for example, a heating unit that applies heat to the raw film B after washing to dry it. The heating unit has, for example, a housing 81 and a heat source (not shown). For example, hot air can be used as the heat source.
The original film B dried by the drying device 8 is the polarizer 1 .

- Film Lamination Zone The film lamination zone has a lamination device 9 for laminating an arbitrary film to the polarizer obtained in the polarizer production zone.
The stacking device 9 will be briefly described with reference to FIG.
The lamination device 9 includes a transport device that transports the polarizer 1 and the optional film 14, an adhesive coating unit 91 that applies an adhesive to the polarizer 1, and an adhesive coating unit that applies an adhesive to the optional film 14. 91 and a bonding portion 92 for bonding the polarizer 1 and the arbitrary film 14 together.
A gravure roll, for example, can be used as the adhesive coating portion 91 . A nip roll, for example, is used for the bonding portion 92 .
When the adhesive is active energy ray-curable, an active energy ray irradiation device 93 is arranged after the bonding portion 92 .

[Method for producing polarizer]
<Wet treatment process>
With reference to FIG. 6, the original film B is pulled out from the delivery unit 41 and conveyed to the swelling treatment tank 42 by the conveying device 3 . The original film B is swelled by being immersed in the swelling liquid while being conveyed by the guide rolls in the swelling treatment tank 42 . Although the temperature of the swelling liquid is not particularly limited, it is, for example, 20°C to 45°C. The time for immersing the original film B in the swelling liquid is not particularly limited, but is, for example, 5 seconds to 300 seconds. Next, the raw film B after swelling is immersed in the dyeing solution in the dyeing treatment bath 43, so that the raw film B is dyed with the dichroic substance. The temperature of the dyeing solution is not particularly limited, but is, for example, 20°C to 50°C. The time for immersing the original film B in the dyeing solution is not particularly limited, but is, for example, 5 seconds to 300 seconds. By immersing the raw film B after dyeing in the cross-linking liquid in the cross-linking tank 44, the dichroic substance of the raw film B is cross-linked. The temperature of the cross-linking liquid is not particularly limited, but is, for example, 25°C or higher, preferably 40°C to 70°C. The time for immersing the original film B in the cross-linking solution is not particularly limited, but is, for example, 5 seconds to 800 seconds.
The raw film B after cross-linking is stretched while being transported in the stretching liquid of the stretching treatment tank 45 . Although the temperature of the drawing liquid is not particularly limited, it is, for example, 40°C to 90°C. The draw ratio can be appropriately set depending on the purpose, and the total draw ratio is, for example, 2 to 7 times, preferably 4.5 to 6.8 times. The total draw ratio means the final draw ratio of the original film B.

<Washing process>
The washing step includes a washing liquid application step of applying a washing liquid to the original film B using the coating roll 6, preferably a washing liquid immersion step of immersing the original film B in a washing treatment tank 51 containing the washing liquid; and the cleaning liquid applying step.
The original film B, which has undergone wet processing such as dyeing and stretching, is washed with a washing liquid.
The raw film B after stretching is washed by immersing the raw film B in the washing liquid in the washing tank 51 . The temperature of the cleaning liquid is, for example, 5°C to 50°C. The cleaning time is, for example, 1 second to 300 seconds.

With reference to FIGS. 6 and 7, the original film B pulled out from the cleaning tank 51 is passed through the nip rolls 32 and then conveyed through the guide rolls 31 to the first coating roll 6a. The washing liquid adhering to the original film B is removed to some extent by passage through the nip rolls 32 and the second liquid removing section 52b.
Next, the original film B is conveyed to the first coating roll 6a, and the washing liquid is applied to one surface of the original film B using the first coating roll 6a. A thin film of cleaning liquid (cleaning liquid film) is formed on one surface of the original film B by the first coating roll 6a. The thickness of the cleaning liquid film is not particularly limited, but if it is too small, the cleaning liquid may not be sufficiently cleaned. From this point of view, the thickness of the cleaning liquid film is preferably 0.1 μm to 20 μm, more preferably 0.3 μm to 15 μm. The thickness of the cleaning liquid film can be adjusted by setting the volume of the concave portion 61 of the first coating roll 6a, the transport speed of the original film B, and the like.
When the first coating roll 6a applies the cleaning liquid to one surface of the hydrophilic polymer layer B12 as shown in FIG. 8, it is preferable to use water containing an iodine compound as the cleaning liquid as described above. The temperature of the cleaning liquid is, for example, 5°C to 50°C.

The first coating roll 6a of the reverse type can form a cleaning liquid film with an appropriate thickness on one side of the original film B while scraping off foreign matter adhering to one side of the original film B. As shown in FIG.
The raw film B that has passed through the first coating roll 6a is transported, and the cleaning liquid adhering to one surface of the raw film B is removed by the liquid removing section 52 (the third and fourth liquid removing sections 52c and 52d). do.

Next, the raw film B is conveyed to the second coating roll 6b, and the cleaning liquid is applied to the opposite surface of the raw film B using the second coating roll 6b. A thin film of cleaning liquid (cleaning liquid film) is formed on the opposite side of the original film B by the second coating roll 6b. For the same reason as above, the thickness of the cleaning liquid film is preferably 0.1 μm to 20 μm, more preferably 0.3 μm to 15 μm. The thickness of the cleaning liquid film can be adjusted by setting the volume of the concave portion 61 of the second coating roll 6b, the transport speed of the original film B, and the like.
As shown in FIG. 9, when the second coating roll 6b applies the cleaning liquid to the opposite surface of the support film B11, it is preferable to use water as the cleaning liquid as described above. The temperature of the cleaning liquid is, for example, 5°C to 50°C.
The reverse-type second coating roll 6b can form a cleaning liquid film with an appropriate thickness on the opposite surface of the original film B while scraping off foreign matter adhering to the opposite surface of the original film B. As shown in FIG.
The original film B that has passed through the second coating roll 6b is transported, and the cleaning liquid adhering to the opposite surface of the original film B is removed by the liquid removing section 52 (fifth to seventh liquid removing sections 52e, 52f, 52g). remove by

When the cleaning liquid is applied using the coating roll 6, the conveying speed of the original film B is not particularly limited. If it is slow, production efficiency will decrease. Taking this point into account, the conveying speed of the original film B when the coating roll 6 is used to apply the cleaning liquid is set.

<Drying process>
The raw film B after washing is dried by the drying device 8 .
Since the raw film B subjected to wet processing and washing processing contains a relatively large amount of water, it is dried by the drying device 8 .
It is preferable to dry the raw film B so that the moisture content of the polarizer 1 obtained after drying is as small as possible. For example, the moisture content of the dried polarizer 1 (original film B after drying in the drying step) is preferably 18% by weight or less, more preferably 17% by weight or less, and even more preferably 16% by weight or less. Since it is preferable that the moisture content is as small as possible, the lower limit is not particularly limited. and is 12% by weight or more.
The drying temperature (atmospheric temperature in the housing 81 of the drying device 8) in the drying step is set to, for example, 40°C to 100°C, preferably 50°C to 90°C.

<Lamination process>
The long strip-shaped polarizer 1 obtained through the drying process may be wound up on a roll as it is. In addition, an optional film may be subsequently laminated on the polarizer 1 .
As shown in FIG. 6 , the long belt-shaped polarizer 1 after drying is conveyed to the bonding section 92 by the conveying device 3 . In the transporting process, an adhesive is applied to one surface of the polarizer 1 (for example, one surface of the dyed hydrophilic polymer layer B12) by the adhesive coating unit 91 . On the other hand, a long belt-shaped arbitrary film 14 (for example, a protective film) is pulled out from the delivery unit 94, and adhesive is applied to one surface of the arbitrary film 14 by the adhesive coating unit 91, and then the arbitrary film 14 is removed. It is conveyed to the bonding section 92 . The polarizer 1 and the optional film 14 on which an adhesive layer (uncured adhesive) is formed by applying an adhesive are passed through the nip rolls 92 and the adhesive is cured. When an active energy ray-curable adhesive is used, the adhesive is cured by irradiating the adhesive layer with an active energy ray to form a laminate consisting of a polarizer/adhesive layer/arbitrary film. A polarizing film 2 is obtained. When the raw film B is a laminate composed of the support film B11 and the hydrophilic polymer layer B12, a laminated polarizing film as shown in FIG. 4 is obtained.
The obtained laminated polarizing film 2 is wound on the winding section 95 .

[Modification]
In the above embodiment, the chambers 71a and 71b (open chambers) in which the side of the coating roll 6 is open are exemplified as the chambers of the supply unit 7 attached to the coating roll 6, but the chambers are not limited to this.
For example, as shown in FIGS. 14 and 15, chambers 76a and 76b closed in close contact with the first coating roll 6a and the second coating roll 6b (coating roll 6) may be used.
Specifically, referring to FIG. 14, the supply unit 7 attached to the first coating roll 6a includes, for example, a closed chamber 76a that supplies the cleaning liquid to the outer peripheral surface of the first coating roll 6a. , a doctor blade 77a in contact with the convex portion 62 on the outer peripheral surface of the first coating roll 6a, an inflow path 73a for inflowing the cleaning liquid into the chamber 76a, and an outflow path 74a for outflowing the cleaning liquid from the chamber 76a. .
The supply unit 7 attached to the second coating roll 6b includes, for example, a closed chamber 76b that supplies the cleaning liquid to the outer peripheral surface of the second coating roll 6b, and a It has a doctor blade 77b in contact with the convex portion 62, an inflow path 73b for inflowing the cleaning liquid into the chamber 76b, and an outflow path 74b for outflowing the cleaning liquid from the chamber 76b.

14 and 15, the chambers 76a and 76b are configured to supply the outer peripheral surface of the coating roll 6 with a cleaning liquid. The chambers 76a and 76b are formed in a hollow shape with openings on the supply destination side of the cleaning liquid. The chambers 76a and 76b are configured to supply the cleaning liquid to the outer peripheral surface of the coating roll 6 from the opening on the supply destination side while filling the inner space with the cleaning liquid. Such chambers 76a and 76b are generally called closed chambers. The chambers 76a and 76b may be filled with the cleaning liquid without any gaps, or may be filled with the cleaning liquid with a partial cavity (for example, the chambers 76a and 76b may be filled with the cleaning liquid in a partially hollow state. There may be cavities below the doctor blades 77a, 77b).
The chambers 76 a and 76 b are arranged so that the openings on the supply destination side are along the outer peripheral surface of the coating roll 6 .

As the coating roll 6 rotates, the cleaning liquid adheres to the outer peripheral surface of the coating roll 6 (the first coating roll 6a and the second coating roll 6b) including the concave portions 61 from the openings of the chambers 76a and 76b on the supply side. . The coating roll 6 rotates while the outer peripheral surface of the coating roll 6 is in contact with the tips of the doctor blades 77a and 77b. As the coating roll 6 rotates, the doctor blades 77a and 77b come into contact with the protrusions 62 on the outer peripheral surface of the coating roll 6, so that excess cleaning liquid attached to the outer peripheral surface of the coating roll 6 is discharged into the chambers 76a and 76b. scraped off. Substantially only the recesses 61 of the coating roll 6 are filled with cleaning liquid after passing the doctor blades 77a, 77b. A thin film of the cleaning liquid is formed on the surface of the original film B by rotating the coating roll 6 in which the concave portions 61 are filled with the cleaning liquid and coming into contact with the surface of the original film B. As shown in FIG.

The chambers 76a and 76b are configured to store the cleaning liquids flowing from the inflow paths 73a and 73b, respectively. Further, each of the chambers 76a and 76b has a sealing member (not shown) in a portion adjacent to the outer peripheral surface of the coating roll 6 so that the cleaning liquid does not leak out. The chambers 76a and 76b are each configured to supply part of the cleaning liquid stored therein to the outer peripheral surface of the coating roll 6 while suppressing leakage of the cleaning liquid by means of sealing members.
One side of the inflow paths 73a and 73b is connected to storage tanks 78 and 79, and the other side is connected to chambers 76a and 76b. The inflow paths 73 a and 73 b each have a pump 753 and a filter 754 . The inflow paths 73a, 73b are configured to send the cleaning liquid in the storage tanks 78, 79 to the chambers 76a, 76b by pumps 753, respectively. Storage tanks 78 and 79 have replenishment paths 782 and 792, respectively. New cleaning liquid is replenished into the storage tanks 78 and 79 from the replenishment paths 782 and 792, and the concentration of the cleaning liquid in the storage tanks 78 and 79 is adjusted.
The outflow paths 74a and 74b are respectively connected to the chambers 76a and 76b on one side and to the storage tanks 78 and 79 on the other side. Outflow paths 74a, 74b are configured to deliver cleaning liquid from chambers 76a, 76b to reservoir tanks 78, 79, respectively.
Incidentally, the inflow path 55 and the outflow path 56 of the cleaning treatment tank 51 may be connected to the storage tank 78 as in the above-described embodiment.

Further, in the above embodiment, the cleaning device 5 has two coating rolls 6 (the first coating roll 6a and the second coating roll 6b), but has three or more coating rolls 6. may Furthermore, the cleaning device 5 may have one coating roll 6 .
Furthermore, in the present invention, the cleaning device 5 may include a liquid draining member (a so-called blade) that contacts the surface of the original film B in order to remove the cleaning liquid adhering to the surface of the original film B. . However, if the draining member is applied to the raw film B with a relatively strong contact pressure, the surface of the raw film B will be damaged. The draining member is provided.

[Advantages of the present invention]
In the present invention, one surface of the original film B is coated with the cleaning liquid using a coating roll.
Even if foreign matter adheres to one side (surface) of the film material after wet processing, the foreign matter can be removed by the cleaning liquid applied to the one side (surface) of the film material by the coating roll.
In particular, the reverse-type coating roll can apply the cleaning liquid after removing foreign matter adhering to the original film to some extent by scraping it off. Foreign matter on the surface of the original film can be effectively removed by using such a reverse-type coating roll.
In addition, even if foreign matter remains on the original film after the cleaning liquid has been applied by the coating roll, a liquid removing section composed of air is provided downstream of the coating roll. Therefore, the temporarily remaining foreign matter can be removed from the surface of the original film together with the cleaning liquid without damaging the surface of the original film.
By using the manufacturing method (manufacturing apparatus) of the present invention, which can reduce the amount of foreign substances adhering to the surface of the original film, it is possible to obtain a polarizer with few optical defects.

[Uses of laminated polarizing film, etc.]
The polarizer and laminated polarizing film of the present invention are typically used as optical films for displays such as liquid crystal displays and organic displays.
In addition, the polarizer and laminated polarizing film of the present invention are not limited to being used in the displays described above, and can be used in applications other than displays. Applications other than displays include optical equipment, buildings, medical and food fields, and the like. When the polarizer and laminated polarizing film are used in an optical device, the polarizer and laminated polarizing film are processed into, for example, polarizing lenses, transparent radio wave blocking films, and the like. When the polarizer and laminated polarizing film are used in an electronic device, the polarizer and laminated polarizing film are processed, for example, into a film for a light control window. When the polarizer and the laminated polarizing film are used in the medical and food fields, the polarizer and the laminated polarizing film are processed into, for example, a photodegradation prevention film.

Examples and Comparative Examples are described below to further describe the present invention. However, the present invention is not limited to the following examples.

[Example]
<Manufacturing equipment>
As shown in FIGS. 6 to 9, a manufacturing apparatus having a wet processing apparatus, a washing apparatus and a drying apparatus in this order (however, a manufacturing apparatus without a film lamination zone) was used.
<Wet processing equipment>
The wet treatment apparatus of the manufacturing apparatus has a swelling treatment tank, a dyeing treatment tank, a cross-linking treatment tank, and a stretching treatment tank in this order. Pure water at 30° C. was used as the swelling liquid in the swelling treatment tank. A 30° C. aqueous solution containing 1% by weight of iodine and 7% by weight of potassium iodide was used as the dyeing solution in the dyeing tank. A 40° C. aqueous solution containing 3% by weight of potassium iodide and 4.5% by weight of boric acid was used as the crosslinking liquid in the crosslinking treatment bath. A 60° C. aqueous solution containing 5% by weight of potassium iodide and 4% by weight of boric acid was used as the stretching liquid in the stretching tank.

<Washing equipment>
The cleaning device has a cleaning tank, a first coating roll, a second coating roll, and first to seventh liquid removing sections.
A 27° C. aqueous solution containing 3.9% by weight of potassium iodide was used as the cleaning liquid for the cleaning tank.
A 3.9% by weight potassium iodide aqueous solution was used as the cleaning liquid applied by the first coating roll, and pure water was used as the cleaning liquid applied by the second coating roll. The cleaning liquid in the first coating roll and the cleaning tank is the same cleaning liquid sent from the storage tank.
The following gravure rolls were used as the first coating roll and the second coating roll, respectively.
Gravure roll: A gravure roll having an outer peripheral surface made of chromium oxide formed by chromium oxide thermal spraying was laser-engraved to uniformly form concave portions (cells) at 1000 lines/inch on the outer peripheral surface. The planar view shape of the cells was a substantially honeycomb shape, and the angle was set to 60 degrees. The diameter of the gravure roll (the diameter of the outer peripheral surface) was 100 mm, and the length of the outer peripheral surface in the axial direction was 1800 mm.
Air was used for the first to seventh liquid removers. Air was blown from a slit-shaped ejection port with a slit width of 1 mm, and the air velocity in each of the first to seventh liquid removing sections was 30 m/sec. The direction of the air in the first liquid removing section is perpendicular to the tangential line of the outer peripheral surface of the pinch roll, and the direction of the air in the second to seventh liquid removing sections is each with respect to the surface of the original film. The direction is set to form an acute angle.

<Drying device>
A drying apparatus was used in which warm air was blown into the housing and the ambient temperature inside the housing was set to about 60°C. The drying device dries the original film while the original film is conveyed by a plurality of guide rolls arranged in the housing.

<Film raw fabric>
As a support film, an amorphous polyethylene terephthalate film (manufactured by Mitsubishi Chemical Corporation, trade name "Novaclear") having a water absorption rate of 0.6%, a Tg of 80°C and an elastic modulus of 2.5 GPa was prepared. This film was in the form of a long belt with a width of 1600 mm and a length of 1000 m, and the thickness of the film was 100 µm.
One surface of this support film is subjected to corona treatment (treatment conditions: 55 W·min/m ² ), and the corona-treated surface is coated with an aqueous PVA solution at 60° C. and dried to form a PVA-based resin layer having a thickness of 10 μm. formed. The PVA aqueous solution contains 90 parts by weight of polyvinyl alcohol (degree of polymerization: 4200, degree of saponification: 99.2 mol%) and 10 parts by weight of acetoacetyl-modified PVA (degree of polymerization: 1200, degree of acetoacetyl modification: 4.6%, It is an aqueous solution containing a degree of saponification of 99.0 mol % or more, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOSEFIMER Z200"). The resulting laminate (laminate of PVA-based resin layer and support film) was uniaxially stretched at the free end by 1.8 times in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds in an oven at 20°C ( aerial auxiliary stretch). Then, the laminated body subjected to the in-air auxiliary stretching was used as a raw film.

<Production of polarizer>
The raw film was set in a manufacturing apparatus, and the raw film was wet-processed, washed, and dried to produce a long band-shaped polarizer as shown in FIGS. 1 and 2 .
Specifically, the original film is immersed in the swelling liquid in the swelling treatment tank for about 30 seconds, immersed in the dyeing liquid in the dyeing treatment tank for about 60 seconds, immersed in the cross-linking liquid in the cross-linking treatment tank for about 30 seconds, and stretched. It was stretched and wet-processed in a processing tank. The maximum draw ratio of the original film was 6.0 times.
Subsequently, the wet-processed raw film is immersed in the cleaning liquid in the washing treatment tank, pulled out from the washing treatment tank, and a first coating roll is applied to one side of the raw film (one side of the PVA-based resin layer). A cleaning solution (3.9% by weight aqueous solution of potassium iodide) was applied using a cleaning solution. A washing liquid film having a thickness of about 0.4 μm is formed on one side of the original film by the first coating roll. Furthermore, a cleaning liquid (pure water) was applied to the opposite side of the original film (opposite side of the support film) using a second coating roll. A washing liquid film having a thickness of about 0.4 μm is formed on the opposite side of the original film by this second coating roll. During the production, each liquid removal section was operated to blow air to remove the liquid from the pinch rolls in the cleaning tank and the surface of the original film.
A long belt-shaped polarizer (a laminate of a support film and a dyed PVA-based resin layer) was continuously produced by introducing the washed raw film into a drying apparatus and drying it.

[Comparative example]
A long belt-shaped polarizer was produced in the same manner as in Examples, except that a draining member was used instead of the first coating roll and the second coating roll of the manufacturing apparatus used in Examples.
Specifically, the draining member is made of a stainless steel plate (1800 mm wide) with a sharp tip. In the conveying path of the raw film between the washing processing tank and the drying device, the tip of the liquid draining member is pressed against one surface of the raw film, and the liquid is applied to the opposite side of the raw film on the downstream side. The tip of the cutting member was pressed against it.
A long band-shaped polarizer was continuously produced by operating the manufacturing apparatus in a state in which a draining member was pressed in place of the coating roll.

[Presence or absence of defects in polarizer]
A laminated polarizing film as shown in FIG. 4 was produced by laminating an acrylic resin-based protective film to each of the polarizers obtained in Examples and Comparative Examples using an ultraviolet curable adhesive.
It was confirmed whether or not the laminated polarizing film had in-plane defects.
Specifically, an imaging device equipped with an illumination and a camera was used, and a transmission inspection was performed by arranging a laminated polarizing film and another polarizing film for inspection between the illumination and the camera.
The number of defects was counted from the captured image of the camera obtained by the transmission inspection.

As a result, the polarizer of the example had an average of 0.08 defects/m, and the polarizer of the comparative example had an average of 0.18 defects/m. The number/m means the number of defective portions per 1 m of the length of the polarizer in the longitudinal direction.

1 Polarizer 3 Conveying Device 4 Wet Processing Device 5 Cleaning Device 51 Cleaning Processing Tank 52, 52a, 52b, 52c, 52d, 52e, 52f, 52g Liquid Removal Unit for Spraying Air 6, 6a, 6b Coating Roll 8 Drying Device A Polarizer manufacturing equipment (manufacturing equipment for laminated polarizing film including polarizer)
B Original film B11 Support film of original film B12 Hydrophilic polymer layer of original film

Claims (8)

A wet processing step of conveying a long strip -shaped original film having a support film and a hydrophilic polymer layer laminated on the support film in the longitudinal direction, dyeing the original film with a dyeing solution and stretching,
a cleaning step of cleaning the wet-processed raw film with a cleaning liquid;
The washing step includes a washing liquid applying step of applying a washing liquid to one surface of the hydrophilic polymer layer of the raw film using a coating roll, and a surface of the support film of the raw film that is in contact with the hydrophilic polymer layer. and a cleaning liquid applying step of applying a cleaning liquid to the opposite surface of the polarizer using a coating roll . The cleaning step further comprises a cleaning liquid immersion step of immersing the original film in a cleaning tank containing a cleaning liquid between the wet treatment step and the cleaning liquid application step,
2. The method for manufacturing a polarizer according to claim 1, wherein the cleaning liquid for the coating roll and the cleaning liquid for the cleaning treatment tank are supplied from the same storage tank. 3. The method of manufacturing a polarizer according to claim 1, wherein the cleaning liquid is water or water containing an iodine compound. In the cleaning liquid coating step, the cleaning liquid is coated on one side of the hydrophilic polymer layer by applying the cleaning liquid to one side of the hydrophilic polymer layer with the coating roll and then blowing air onto the hydrophilic polymer layer. The method for manufacturing a polarizer according to any one of claims 1 to 3, wherein the is removed. The coating roll has a plurality of recesses filled with the cleaning liquid on the outer peripheral surface,
In the cleaning liquid applying step, the cleaning liquid filled in the recesses of the coating roll is caused to adhere to the hydrophilic polymer layer by bringing the outer peripheral surface of the rotating coating roll into contact with one surface of the hydrophilic polymer layer . The method for manufacturing a polarizer according to any one of claims 1 to 4. 6. The cleaning liquid coating step according to any one of claims 1 to 5, wherein the cleaning liquid is applied to the hydrophilic polymer layer while the coating roll is rotated in a direction opposite to the conveying direction of the original film. method for manufacturing a polarizer. 7. The cleaning liquid film according to any one of claims 1 to 6, wherein in the cleaning liquid applying step, a cleaning liquid film having a thickness of 0.1 μm to 20 μm is formed on one surface of the hydrophilic polymer layer by applying the cleaning liquid with the coating roll. A method for producing the polarizer according to item 1. A conveying device for conveying in the longitudinal direction a long strip -shaped original film having a support film and a hydrophilic polymer layer laminated on the support film ;
A wet processing device for dyeing and stretching the film raw fabric with a dyeing solution,
a cleaning device arranged downstream of the wet processing device and cleaning the original film with a cleaning liquid;
The cleaning device has first and second coating rolls having a plurality of recesses on the outer peripheral surface that can be filled with a cleaning liquid,
The first coating roll is arranged so that its outer peripheral surface is in contact with one surface of the hydrophilic polymer layer of the film raw fabric to be conveyed,
The second coating roll is arranged such that its outer peripheral surface is in contact with the surface opposite to the surface in contact with the hydrophilic polymer layer of the support film of the raw film to be transported. Production of a polarizer Device.

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