CN112432431A

CN112432431A - Polarizing film drying device and method

Info

Publication number: CN112432431A
Application number: CN202010869853.4A
Authority: CN
Inventors: 高尾阳; 井上龙一
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2019-08-26
Filing date: 2020-08-26
Publication date: 2021-03-02
Also published as: CN212457623U; JP7377024B2; JP2021033086A

Abstract

The invention provides a polarizing film drying device and a polarizing film drying method, which can prevent the end damage of the polarizing film. The drying device blows warm air to a long strip-shaped polarizing film while conveying the polarizing film in a longitudinal direction, and comprises: a warm air duct (5) having a warm air blowing section (52) disposed so as to face the surface of the polarizing film (2Y); and a cover sheet (7) that covers a region of the warm air blowout part (52) that corresponds to the widthwise end of the polarizing film (2Y).

Description

Polarizing film drying device and method

Technical Field

The present invention relates to a drying apparatus for a polarizing film including a polarizing plate and a drying method thereof.

Background

Conventionally, polarizing films including polarizing plates have been used as constituent materials of liquid crystal display devices, polarized sunglasses, and the like. Examples of the polarizing film include a laminate in which a protective film is laminated on a polarizing plate.

Such a polarizing film composed of a laminate is obtained by attaching a protective film to a polarizing plate using an adhesive after the polarizing plate is manufactured.

For example, patent document 1 discloses that a polarizing film (laminate) is formed by laminating a long strip-shaped polarizing plate and a protective film (cellulose acetate resin film) with an adhesive, and then the polarizing film is dried in a drying oven.

The drying oven is a system in which a long belt-shaped laminate is conveyed while hot air is blown to the laminate. The drying oven of the hot air blowing system generally has a hot air duct in which a hot air blowing unit for blowing hot air to the surface of the polarizing film is formed.

Patent document 1: japanese patent laid-open publication No. 2013-205721

However, when the polarizing film including the polarizing plate is dried by blowing warm air, the end portion of the polarizing film in the width direction may be curled.

When the polarizing film having the curled end portion during drying is dried while being conveyed by using a warm air duct, the curled end portion may come into contact with the warm air blowing unit. If the end of the polarizing film comes into contact with the warm air blowout part, the end of the polarizing film may be chipped off and damaged by the warm air blowout part. Further, the end portion of the polarizing film is shaved off, which may cause generation of film residue, and the film residue may be attached to the end portion of the polarizing film. Such damage of the end portion and adhesion of foreign matter such as film residue reduce the yield of the polarizing film, and improvement thereof is required.

In addition, the polarizing films of various lateral widths are dried according to manufacturing lots. The polarizing film having a large lateral width and the polarizing film having a small lateral width are different in position of the end in the width direction, and therefore are different in position of contact with the warm air blowing unit.

Disclosure of Invention

A first object of the present invention is to provide a polarizing film drying apparatus and a polarizing film drying method capable of preventing damage to an end of a polarizing film.

A second object of the present invention is to provide a polarizing film drying apparatus and a polarizing film drying method that can prevent damage to the ends of polarizing films having different lateral widths even when the polarizing films are dried.

The present invention provides a drying device for a polarizing film, which blows warm air to a long strip-shaped polarizing film while the polarizing film is conveyed in a longitudinal direction, the drying device comprising: a warm air duct having a warm air blowing section disposed to face the surface of the polarizing film; a cover sheet that covers a region corresponding to a widthwise end of the polarizing film in the warm air blowout part.

In a preferred polarizing film drying apparatus of the present invention, one end of the cover sheet is fixed to one side of the warm air blowing section of the warm air duct, the opposite end of the cover sheet is a free end, a rod member is attached to the opposite end of the cover sheet, a locking section capable of locking the rod member is provided on the opposite side of the warm air blowing section of the warm air duct, and the cover sheet covers the area by locking the rod member to the locking section.

In the preferred polarizing film drying device of the present invention, the cover sheet covers the region in a state where tension is applied.

In a preferred polarizing film drying device of the present invention, the cover sheet has two or more sheets, the first cover sheet covers a region corresponding to the widthwise end of the first polarizing film, and the second cover sheet covers the widthwise end of the second polarizing film having a width smaller than that of the first polarizing film.

In a preferred polarizing film drying apparatus of the present invention, the cover sheets are formed as a pair on the left and right sides so as to cover regions corresponding to both ends in the width direction of the polarizing film.

In a preferred drying device for a polarizing film of the present invention, the cover sheet comprises a polyimide resin sheet.

According to another aspect of the present invention, a method of drying a polarizing film is provided.

The method for drying a polarizing film of the present invention is a method for drying a long strip-shaped polarizing film while the polarizing film is being transported in a longitudinal direction, the method comprising: covering, with a cover sheet, a region corresponding to a widthwise end of the polarizing film in a warm air blowout part of a warm air duct having the warm air blowout part disposed opposite to a surface of the polarizing film; the polarizing film is dried by blowing warm air from a warm air duct covered with the cover sheet while being conveyed in the longitudinal direction.

In a preferred method for drying the polarizing film of the present invention, the warm air duct is provided with two or more cover sheets, and the region is covered with a cover sheet selected from the two or more cover sheets depending on the polarizing film having a different transverse width.

According to the drying device and the drying method of the present invention, the polarizing film can be dried while preventing the end of the polarizing film from being damaged.

Further, according to the preferred drying device and drying method of the present invention, it is possible to dry polarizing films having different lateral widths while preventing end damage.

Drawings

Fig. 1 is a partially omitted plan view of the polarizing film of the present invention.

Fig. 2 is a cross-sectional view (cross-sectional view taken along line II-II in fig. 1) of a polarizing film (basic polarizing film) according to an embodiment.

Fig. 3 is a cross-sectional view of a polarizing film (basic polarizing film) of another embodiment.

Fig. 4 is a sectional view of a polarizing film (laminated polarizing film) according to still another embodiment.

Fig. 5 is a sectional view of a polarizing film (laminated polarizing film) according to still another embodiment.

Fig. 6 is a schematic front view showing a polarizing film manufacturing apparatus.

Fig. 7 is a front view of the first warm air duct and the second warm air duct before the warm air blowout part is covered with the cover sheet.

Fig. 8 is a bottom view of the first warm air duct as viewed from the direction of arrow VIII of fig. 7.

Fig. 9 is a left side view of the first warm air duct viewed from the direction of arrow IX of fig. 7.

Fig. 10 is a right side view of the first warm air duct as viewed from the direction of arrow X of fig. 7.

Fig. 11 is a plan view of the first warm air duct as viewed from the direction of arrow XI of fig. 7.

Fig. 12 is an enlarged sectional view taken along line XII-XII of fig. 11.

Fig. 13 is an enlarged sectional view taken along line XIII-XIII of fig. 11.

Fig. 14 is a plan view of the second warm air duct as viewed from the direction of arrow XIV of fig. 7.

Fig. 15 is a front view showing a step of covering the warm air blowout part of the first warm air duct with a cover sheet.

Fig. 16 is an enlarged cross-sectional view showing a state in which the warm air blowout part of the first warm air duct is covered with the first cover sheet.

Fig. 17 is a bottom view as viewed from the direction of arrow XVII of fig. 6.

Fig. 18 is an enlarged sectional view showing a state in which the warm air blowout part of the second warm air duct is covered with the first cover sheet.

Fig. 19 is a plan view as viewed from the direction of arrow XIX in fig. 6.

Fig. 20 is an enlarged sectional view showing a state in which the warm air blowout part of the first warm air duct is covered with the second cover sheet.

Fig. 21 is an enlarged cross-sectional view showing a state in which the warm air blowout part of the first warm air duct is covered with the third cover sheet.

Description of the reference numerals

1. 2, 1Y, 2Y polarizing film

2Y-1, 2Y-2 laminated polarizing film (polarizing film) with widthwise side edges

5. 5A, 5B warm air pipeline

52 warm air blowing part

6 Bar part

7 cover sheet

71 one end of the cover sheet

72 opposite ends of the cover sheet

7a first covering sheet

7b second cover sheet

7c third cover sheet

8 holding part

9 locking part

Detailed Description

In the present specification, the numerical range represented by "lower limit value X to upper limit value Y" means not less than lower limit value X and not more than upper limit value Y. When a plurality of the numerical ranges are described individually, an arbitrary lower limit value and an arbitrary upper limit value may be selected and "an arbitrary lower limit value to an arbitrary upper limit value" may be set.

In the present specification, "first" and "second" may be added to the beginning of terms, but the first term and the second term are added only for distinguishing the terms, and there is no particular meaning such as order or merits.

[ polarizing plate and laminated polarizing film ]

Fig. 1 is a partially omitted plan view of a polarizing film 1 of the present invention.

The polarizing film 1 obtained by the drying method (production method) of the present invention is in the form of a long strip. The long strip-shaped polarizing film is cut into an appropriate shape and used for various purposes.

In the present invention, the polarizing film to be dried (manufactured) is a film including a polarizing plate. Here, the polarizing plate is an optical element having a property (this property is a polarization characteristic) of transmitting light (polarized light) vibrating only in one specific direction and blocking light vibrating in the other direction.

The polarizing film may include a polarizing plate. The polarizing film of the present invention conceptually includes a polarizing plate itself, a film in which a polarizing plate and a support film are laminated, a film in which an arbitrary film such as a protective film is laminated with a polarizing plate, an arbitrary film such as a protective film, a film in which a polarizing plate and a support film are laminated, and the like.

Fig. 2 is a cross-sectional view of the polarizing film 1 taken along line II-II of fig. 1.

Referring to fig. 2, a polarizing film 1 of one embodiment includes a support film 11 and a polarizing plate 12 laminated on one surface of the support film. The polarizing plate 12 is composed of a hydrophilic polymer layer dyed with a dichroic substance. The hydrophilic polymer layer has polarizing properties.

Fig. 3 is a cross-sectional view of a polarizing film 1 of another embodiment. This cross-sectional view is also obtained by cutting the polarizing film 1 of the other embodiment at the same position as the line II-II in fig. 1.

Referring to fig. 3, a polarizing film 1 of another embodiment is constituted by a polarizing plate 13 itself. The polarizing plate 13 is composed of a hydrophilic polymer film dyed with a dichroic substance. The hydrophilic polymer film has polarizing properties.

Hereinafter, the polarizing film composed of the support film 11 and the polarizing plate 12 shown in fig. 2 and the polarizing film 1 composed of only the polarizing plate 13 shown in fig. 3 are collectively referred to as "basic polarizing film 1".

Further, one, two or more arbitrary films may be further laminated on the basic polarizing film 1. Hereinafter, the arbitrary film is referred to as an "arbitrary film", and a polarizing film in which the arbitrary film is laminated on the basic polarizing film 1 is collectively referred to as a "laminated polarizing film".

Fig. 4 and 5 are cross-sectional views of several laminated polarizing films 2.

Referring to fig. 4, a laminated polarizing film 2 of one embodiment has a basic polarizing film 1 and a first optional film 21, the basic polarizing film 1 has a support film 11 and a polarizing plate 12, and the first optional film 21 is laminated to the polarizing plate 12 of the basic polarizing film 1 via an adhesive layer 211.

Referring to fig. 5, a laminated polarizing film 2 according to another embodiment includes a basic polarizing film 1, a first arbitrary film 21, and a second arbitrary film 22, the basic polarizing film 1 is composed of only a polarizing plate 13, the first arbitrary film 21 is laminated on one surface of the basic polarizing film 1 via an adhesive layer 211, and the second arbitrary film 22 is laminated on the opposite surface of the basic polarizing film 1 via an adhesive layer 221.

< random Membrane >

Examples of the optional film include a protective film, a retardation film, a brightness enhancement film, and a transparent conductive film. Any film laminated on the basic polarizing film 1 may be appropriately selected from among them.

For example, as the first arbitrary film 21, a protective film is used. For example, as the second arbitrary film 22, a protective film is used. For example, as the third arbitrary film 23, a protective film or a retardation film is used.

The protective film is a film for protecting a polarizing plate. As described later, the protective film is laminated on the basic polarizing film after the basic polarizing film is produced.

The protective film is used for the purpose of protecting a polarizing plate or the like as a protected object from damage or contamination. Examples of the protective film include olefin resins such as polyethylene and polypropylene; a film composed of an ester resin such as polyethylene terephthalate, an amide resin such as nylon 6, a vinyl polymer such as polyvinyl chloride or a vinyl chloride-vinyl acetate copolymer, a cellulose resin such as triacetylcellulose or diacetylcellulose, an acrylic resin such as polymethyl methacrylate, a styrene resin, a carbonate resin, a polyarylate resin, an imide resin, or the like.

The phase difference film is an optical film exhibiting optical anisotropy. Examples of the retardation film include anisotropic films such as 1/2 λ sheet and 1/4 λ sheet.

The brightness enhancement film is an optical film that transmits only a specific polarized light and reflects other polarized light.

< adhesive layer >

The adhesive layer is a cured layer of an adhesive, and is a layer which is interposed between and bonds two films.

The pressure-sensitive adhesive layer is composed of, for example, an active energy ray-curable pressure-sensitive adhesive such as an ultraviolet-curable pressure-sensitive adhesive, a solvent-volatile pressure-sensitive adhesive, or the like.

[ basic polarizing film and apparatus for producing laminated polarizing film ]

The manufacturing device of the present invention includes a basic polarizing film manufacturing area for manufacturing a long strip-shaped basic polarizing film and a laminated polarizing film manufacturing area for manufacturing a long strip-shaped laminated polarizing film.

The basic polarizing film manufacturing area is used for manufacturing the basic polarizing film by performing wet processing on a long strip-shaped film raw material. The primary polarizing film production area is preferably a system in which a series of steps up to obtaining a primary polarizing film by wet-treating a film material and drying the film material are performed on one production line.

The laminated polarizing film production region produces a laminated polarizing film by laminating a long strip-shaped arbitrary film on a long strip-shaped basic polarizing film. The laminated polarizing film production area is preferably a system in which a series of steps is performed on a single production line until an arbitrary film is laminated on a basic polarizing film via an adhesive and dried to obtain a laminated polarizing film.

The manufacturing apparatus of the present invention may be a system in which the basic polarizing film manufacturing region and the laminated polarizing film manufacturing region are independent from each other, or the basic polarizing film manufacturing region and the laminated polarizing film manufacturing region are connected and arranged in a single production line.

Specifically, production of a laminated polarizing film: the method may be (a) in which the basic polarizing film is temporarily wound into a roll after the production of the basic polarizing film, and the wound-up basic polarizing film is sent out and laminated with an arbitrary film; alternatively, the method (b) may be such that after the production of the basic polarizing film, an arbitrary film is laminated and bonded on the basic polarizing film in one production line. From the viewpoint of production efficiency, the above-mentioned method (b) is preferable.

The manufacturing apparatus of the above-described (b) system is a system in which a basic polarizing film manufacturing region and a laminated polarizing film manufacturing region are connected and arranged on one production line (a system in which a series of steps until obtaining a laminated polarizing film from a basic polarizing film is performed on one production line).

Fig. 6 shows a preferred configuration example of the polarizing film (basic polarizing film and laminated polarizing film) manufacturing apparatus 10 of the above (b) mode.

Referring to fig. 6, the manufacturing apparatus 10 includes at least a transport apparatus 101 for transporting each of the film material Y, the basic polarizing film 1Y, the laminated polarizing film 2Y, and the

optional films

21Y and 22Y, a basic polarizing film manufacturing area 3, and a laminated polarizing film manufacturing area 4 for bonding at least one of the films to the basic polarizing film 1Y. The conveying device 101 includes various rollers such as guide rollers.

The primary polarizing film production region 3 includes a wet processing device 31 for wet processing the film material Y and a drying device 32 for drying the primary polarizing film 1Y.

The laminated polarizing film formation region 4 includes a laminating device 41 for laminating an arbitrary film to the basic polarizing film formation region 3 with an adhesive to obtain the basic polarizing film 1Y, and a drying device 42 for drying the laminated polarizing film 2Y laminated with the arbitrary film.

The drying device 32 of the primary polarizing film formation region 3 blows warm air to the primary polarizing film 1Y in the form of a long strip while conveying the primary polarizing film 1Y (polarizing film) in the longitudinal direction.

The drying device 42 of the laminated polarizing film fabrication region 4 blows warm air to the laminated polarizing film 2Y (polarizing film) in a long strip shape while conveying the laminated polarizing film 2Y in the longitudinal direction.

The present invention is characterized in that a drying device for blowing warm air to a long strip-shaped polarizing film while conveying the polarizing film in a longitudinal direction is used, the drying device including a cover sheet for covering a region corresponding to an end in a width direction of the polarizing film in a warm air blowing section of a warm air duct.

The drying device having the cover sheet may be applied to the drying device 32 of the basic polarizing film fabrication region 3 and/or may also be applied to the drying device 42 of the laminated polarizing film fabrication region 4.

In the configuration example of fig. 6, a case where a drying apparatus (a drying apparatus having a cover sheet) which is characteristic of the present invention is adopted as the drying apparatus 42 of the laminated polarizing film production region 4 is exemplified.

< basic polarizing film formation region >

The primary polarizing film formation area 3 includes a wet processing device 31 for obtaining the primary polarizing film 1Y by wet processing the film material Y, and a drying device 32 for drying the primary polarizing film 1Y obtained by wet processing.

The wet processing apparatus 31 can have a conventionally known structure.

For example, the wet processing apparatus 31 includes a swelling processing tank 311, a dyeing processing tank 312, a crosslinking processing tank 313, a stretching processing tank 314, and a cleaning processing tank 315 in this order from the upstream side. The wet processing apparatus 31 is not limited to the above configuration, and for example, the wet processing apparatus 31 may not have the swelling treatment tank 311 or may not have the stretching treatment tank 314. In the case where the stretching treatment tank 314 is not provided, the film material Y is subjected to a stretching treatment in a tank such as the dyeing treatment tank 312. The wet processing apparatus 31 may have another processing bath such as an adjustment processing bath.

Note that in this specification, the downstream side refers to the conveying direction side of the film (the traveling direction side of the film), and the upstream side refers to the opposite side thereof (the side opposite to the conveying direction of the film).

The untreated film material Y is conveyed to the downstream side of the swelling treatment tank 311 and the like by a conveying device 101 provided with guide rollers and the like. The hollow arrow in fig. 6 indicates the traveling direction (conveying direction) of the film.

The film material Y is a long strip. In the present specification, the long strip-like shape refers to a rectangular shape having a length in the longitudinal direction sufficiently larger than a length in the width direction (direction orthogonal to the longitudinal direction). The length of the long strip in the longitudinal direction is, for example, 10m or more, preferably 50m or more.

The film material Y may be a long strip-shaped film containing a hydrophilic polymer.

As the film material Y, for example, a laminate of a long strip-shaped support film and a hydrophilic polymer layer laminated on one surface of the support film, or a hydrophilic polymer film can be used. In the case of using the laminate as the film stock Y, the basic polarizing film shown in fig. 2 can be obtained. In the case of using the hydrophilic polymer film as the film stock Y, the basic polarizing film shown in fig. 3 can be obtained.

The film material Y may be a conventionally known untreated film.

In short, the hydrophilic polymer layer of the laminate can be formed by applying a coating liquid containing a hydrophilic polymer to one surface of a support film and drying the coating liquid. The support film may be a colorless and transparent resin film, for example, an ester resin film such as polyethylene terephthalate resin.

Examples of the hydrophilic polymer include polyvinyl alcohol (PVA) resins and ethylene-vinyl alcohol copolymers.

The hydrophilic polymer film can be obtained by forming a hydrophilic polymer into a film shape. As the hydrophilic polymer, as described above, PVA-based resins, ethylene-vinyl alcohol copolymers, and the like can be cited.

The swelling treatment tank 311 is a treatment tank containing a swelling solution. The swelling solution swells the membrane material Y. As the swelling liquid, for example, water or an aqueous solution containing an iodine compound such as potassium iodide can be used.

The dyeing tank 312 is a tank for storing a dyeing solution. The staining solution stains the hydrophilic polymer of the membrane material Y. As the staining solution, for example, an aqueous solution containing a dichroic substance can be used, and an aqueous solution containing a dichroic substance and an iodine compound such as potassium iodide can be preferably used. Examples of the dichroic substance include iodine and an organic dye.

The crosslinking treatment tank 313 is a treatment tank in which a crosslinking liquid is stored. The crosslinking liquid crosslinks the dyed film stock Y. As the crosslinking liquid, for example, an aqueous solution containing a boron compound such as boric acid can be used, and an aqueous solution containing a boron compound and an iodine compound such as potassium iodide can be preferably used.

The stretching treatment tank 314 is a treatment tank that contains a stretching liquid. For example, an aqueous solution containing a boron compound can be used as the stretching liquid, and an aqueous solution containing a boron compound and an iodine compound such as potassium iodide can be preferably used. The film stock Y is dyed and stretched to become the basic polarizing film 1Y.

The cleaning treatment tank 315 is a treatment tank that contains a cleaning liquid. The cleaning liquid cleans the basic polarizing film 1Y (the dyed stretched film raw material Y). As the cleaning liquid, for example, water or an aqueous solution containing an iodine compound such as potassium iodide can be used.

On the downstream side of the cleaning treatment tank 315, a spraying section 316 that sprays the cleaning liquid on the base polarizing film 1Y drawn out from the cleaning treatment tank 315, and a blowing section 317 (liquid cut-off section) that removes the cleaning liquid adhering to the film are provided as necessary.

The drying device 32 of the basic polarizing film formation region 3 is provided on the downstream side of the cleaning treatment tank 315. The drying device 32 is provided to dry the cleaned basic polarizing film 1Y. One drying device 32 may be provided, or two or more drying devices may be provided in parallel in the transport direction of the primary polarizing film 1Y. The drying device 32 is preferably a system for blowing warm air to the primary polarizing film 1Y to dry the film. The drying device 32 includes, for example, a chamber 321 and a warm air duct (not shown) having a warm air blowing unit that blows warm air, and the warm air duct is disposed in the chamber 321.

< laminated polarizing film formation region >

The laminated polarizing film formation region 4 includes a laminating device 41 for laminating an arbitrary film to the basic polarizing film 1Y obtained through the basic polarizing film formation region 3 using an adhesive, and a drying device 42 for drying the laminated polarizing film 2Y laminated with the arbitrary film.

The laminating device 41 can have a conventionally known structure. Referring to fig. 6 for briefly explaining the laminating device 41, the laminating device 41 includes

adhesive application sections

412 and 413 for applying an adhesive to the first arbitrary film 21Y and the second arbitrary film 22Y, and a bonding section 414 for bonding the basic polarizing film 1Y to the arbitrary films. The adhesive coating section can be formed by a suitable coater, for example, a gravure roll can be used as shown in the figure. The applying portion 414 may be a nip roller, for example.

Note that, in the case where the adhesive is an active energy ray-curable adhesive, the active energy ray irradiation device 415 is disposed after the bonding portion.

The laminating device 41 illustrated in the figure is a double-sided lamination type in which the first arbitrary film 21Y and the second arbitrary film 22Y are laminated on one surface and the opposite surface of the basic polarizing film 1Y. In the case of using this lamination device 41, for example, a laminated polarizing film shown in fig. 5 can be obtained. Note that the laminating device 41 may be a single-side lamination type in which an arbitrary film is laminated only on one surface of the basic polarizing film 1Y. When this single-side lamination type lamination device 41 is used, a lamination polarizing film shown in fig. 4, for example, can be obtained.

After a surface protective film (not shown) is attached to the obtained laminated polarizing film, the laminated polarizing film is wound.

[ drying apparatus of the present invention ]

The drying device 42 for laminating the polarizing film formation region 4 is provided downstream of the laminating device 41. The drying device 42 is provided to dry the laminated polarizing film 2Y (a laminate in which a basic polarizing film and an arbitrary film are laminated). One drying device 42 may be provided, or two or more drying devices may be provided in parallel in the transport direction of the laminated polarizing film 2Y.

In the illustrated example, the laminated polarizing film 2Y is transported substantially horizontally, and two drying devices 42 are disposed during the transport.

The drying device 42 includes: a warm air duct 5 having a warm air blowing unit disposed to face the surface of the basic polarizing film 1Y; a cover sheet 7 that covers a region corresponding to the width direction end of the laminated polarizing film 2Y in the warm air blowing section; the drying device 42 also has a chamber 421 as necessary.

The chamber 421 is a casing that surrounds the outside of the warm air duct 5 equipped with the cover sheet 7. The warm air duct 5 is housed in the chamber 421 in a sealed state.

A resin sheet having flexibility and excellent smoothness can be used for the cover sheet 7. The material of the resin sheet is not particularly limited, and examples thereof include resins selected from polyester resins such as polyethylene terephthalate, olefin resins such as polypropylene; styrene resins such as polystyrene and styrene-butadiene copolymers, cyclic olefin resins, vinyl chloride copolymers, polyamide resins, polyimide resins, polycarbonate resins, fluorine resins, and the like.

Since the cover sheet 7 is used for the warm air duct 5, the cover sheet 7 is preferably a resin sheet having excellent heat resistance. The resin sheet having excellent heat resistance is preferably a resin having a glass transition temperature of 100 ℃ or higher, more preferably a resin having a glass transition temperature of 200 ℃ or higher, and examples thereof include a polyimide-based resin sheet, a polycarbonate-based resin sheet, and a fluorine-based resin sheet. Among them, a polyimide-based resin sheet having a glass transition temperature of 216 ℃ is preferable. Note that when a polypropylene sheet having a glass transition temperature of about 0 ℃ or a polyethylene terephthalate sheet having a glass transition temperature of less than 100 ℃ is used, the sheet may be stretched or wrinkled due to heat.

The thickness of the cover sheet 7 is not particularly limited, and is, for example, 50 μm to 200 μm.

The cover sheet 7 is formed in a belt shape.

The transverse width of the cover sheet 7 is not particularly limited, but if it is too small, the cover width of the region corresponding to the widthwise end of the laminated polarizing film 2Y (polarizing film) is too small, whereas if it is too large, the warm air blowout part is blocked over a wide range, and the blowout amount of the warm air is excessively limited. From this viewpoint, the transverse width W7 of the cover sheet 7 is preferably 30mm to 150mm, more preferably 50mm to 100 mm. Note that, in this specification, the lateral width refers to the length in the width direction.

As for the belt shape and the transverse width W7 of the cover sheet 7, for example, fig. 17 can be referred to.

The warm air ducts 5 provided with the cover sheets 7 are disposed on both surfaces (one surface and the opposite surface) of the laminated polarizing film 2Y. In the present specification, the warm air duct 5 disposed on one surface side of the laminated polarizing film 2Y (polarizing film) is referred to as a "first warm air duct 5A", and the warm air duct 5 disposed on the opposite surface side of the laminated polarizing film 2Y (polarizing film) is referred to as a "second warm air duct 5B", and the whole is collectively referred to as a "warm air duct 5".

The number of the first warm air ducts 5A and the number of the second warm air ducts 5B may be 1 independently, but preferably 2 or more ducts are arranged in parallel in the longitudinal direction of the laminated polarizing film 2Y, and more preferably 3 or more ducts are arranged in parallel in the longitudinal direction of the laminated polarizing film 2Y. The upper limit of the number of the first warm air duct 5A and the second warm air duct 5B is not particularly limited, but is, for example, 15 or less, preferably 12 or less, independently.

In the example of the figure, a case where 3 first warm air ducts 5A and 3 second warm air ducts 5B are provided in parallel in the longitudinal direction for each drying device 42 is illustrated as a reference.

When a plurality of the first warm air ducts 5A and the second warm air ducts 5B are provided in parallel, the interval between the warm air ducts 5 adjacent to each other in the longitudinal direction is not particularly limited and can be set as appropriate.

< first warm air duct >

Fig. 7 is a front view of the drying device 42 with one warm air duct 5A and one warm air duct 5B taken out. Fig. 7 shows the first warm air duct 5A and the second warm air duct 5B in a state before the warm air blowout part is covered with the cover sheet 7 (a state where the cover sheet 7 is stored). The thin broken line in fig. 7 indicates a transport path of the laminated polarizing film 2Y.

Fig. 8 is a bottom view of the first warm air duct 5A in a state before the warm air blowout part is covered with the cover sheet 7, fig. 9 is a left side view of the first warm air duct 5A, fig. 10 is a right side view of the first warm air duct 5A, fig. 11 is a plan view of the first warm air duct 5A, and fig. 12 and 13 are enlarged cross-sectional views in which a widthwise middle part of the first warm air duct 5A is cut in a direction orthogonal to the widthwise direction and enlarged.

Note that, in fig. 8 to 11, and 14, the width direction intermediate portions continuing to have the same configuration are omitted.

Referring to fig. 7 to 13, the first warm air duct 5A is constituted by an elongated hollow body extending in the width direction. The elongated first warm air duct 5A is disposed such that the long axis thereof is substantially parallel to the width direction of the laminated polarizing film 2Y.

The first warm air duct 5A has: a warm air blowing unit 52 having an opening 51 (nozzle portion); a side surface portion 53 disposed on one side portion of the warm air blowing portion 52; another side surface portion 54 disposed on the opposite side of the warm air blowing portion 52; and a top surface portion 55 disposed between the one side surface portion 53 and the other side surface portion 54. The warm air blowing-out portion 52, the one side surface portion 53, the top surface portion 55, and the other side surface portion 54 are connected to each other, thereby constituting a hollow first warm air duct 5A.

The warm air blowing unit 52 is disposed opposite to the laminated polarizing film 2Y (polarizing film).

The warm air blowing unit 52 is provided with an opening 51 through which warm air is blown. The opening 51 is formed as a slit-like opening extending in the width direction (the longitudinal direction of the first warm air duct 5A). A pair of the openings 51 is formed, for example. Note that the opening 51 is not limited to a slit-shaped opening, and may be a plurality of small holes (not shown) arranged in the width direction, for example. Warm air is supplied from a warm air supply device not shown into the first warm air duct 5A, and the warm air is blown out from the warm air blowing unit 52 to the laminated polarizing film 2Y through the opening 51.

The outer surface of the warm air blowout part 52 is a substantially flat plane except for the opening 51.

The first warm air duct 5A including the warm air blowout part 52 is generally formed of metal such as iron or stainless steel.

The first warm air duct 5A is provided with a cover sheet 7. The cover sheet 7 covers a region corresponding to the width direction end of the laminated polarizing film 2Y in the warm air blowout part 52.

One cover sheet 7 covering the region of the warm air blowing unit 52 corresponding to the widthwise end of the laminated polarizing film 2Y may be provided for one first warm air duct 5A, but it is preferable to provide two or more cover sheets 7 for one first warm air duct 5A.

Here, the width of the laminated polarizing film 2Y (polarizing film) to be dried is various. That is, normally, the laminated polarizing film 2Y (polarizing film) of various lateral widths is manufactured using one manufacturing apparatus 10. The laminated polarizing film 2Y (polarizing film) having a transverse width of, for example, 500mm to 4000mm can be manufactured by one manufacturing apparatus 10. Therefore, the drying device 42 can also dry the laminated polarizing film 2Y of various lateral widths. In general, in view of manufacturing the laminated polarizing film 2Y having the largest lateral width (the laminated polarizing film having the largest lateral width), the widthwise length of the first warm air duct 5A is designed to be larger than the largest lateral width. Therefore, the regions of the warm air blowing unit 52 corresponding to the width-direction ends of the laminated polarizing film 2Y are different between the case of drying the wide laminated polarizing film 2Y and the case of drying the narrow laminated polarizing film 2Y. When the wide laminated polarizing film 2Y is dried while being conveyed, the widthwise end of the laminated polarizing film 2Y passes outward in the width direction of the warm air blowing unit 52. When the laminated polarizing film 2Y having a relatively small width is dried while being conveyed, the widthwise end of the laminated polarizing film 2Y passes through the laminated polarizing film 2Y having a relatively large width at a position inward in the width direction of the warm air blowing unit 52.

It is desirable that even when the laminated polarizing films 2Y (polarizing films) having different lateral widths are dried in this manner, the end portions of these laminated polarizing films 2Y can be prevented from being damaged. Therefore, it is preferable to provide a plurality of cover sheets 7 that cover different regions in the width direction of the warm air blowout part 52.

The plurality of cover sheets 7 include, for example, a first cover sheet 7a and a second cover sheet 7b, the first cover sheet 7a covering a region corresponding to a widthwise end of a first laminated polarizing film (first polarizing film) having a predetermined transverse width, and the second cover sheet 7b covering a region corresponding to a widthwise end of a second laminated polarizing film (second polarizing film) having a width smaller than that of the first laminated polarizing film. As shown in the drawing, the cover sheet 7 further includes a third cover sheet 7c, and the third cover sheet 7c covers a region corresponding to a widthwise end of a third laminated polarizing film (third polarizing film) having a width smaller than that of the second laminated polarizing film 2Y.

The first, second, and third laminated polarizing films satisfy a relationship of a transverse width of the first laminated polarizing film > a transverse width of the second laminated polarizing film > a transverse width of the third laminated polarizing film. In the illustrated example, the first warm air duct 5A includes the first cover sheet 7a, the second cover sheet 7b, and the third cover sheet 7c corresponding to the laminated polarizing films (polarizing films) having the three kinds of lateral widths, and therefore, even when any of the laminated polarizing films is dried, damage to the end portions thereof can be prevented. Note that the cover sheet 7 is not limited to the case of being provided so as to correspond to the laminated polarizing films (polarizing films) having three kinds of transverse widths, respectively, and four or more sheets may be provided so as to correspond to the laminated polarizing films having four or more kinds of transverse widths, respectively.

From another perspective, there is a pair of left and right widthwise ends of the laminated polarizing film in the widthwise direction. Therefore, from the viewpoint of preventing damage to each of the right and left ends (both ends in the width direction) in the width direction of the laminated polarizing film, it is preferable that the cover sheet 7 is formed of a pair of left and right sheets corresponding to the right and left ends in the width direction of one laminated polarizing film (polarizing film) having a predetermined lateral width. In this case, a pair of cover sheets 7 is provided on the left and right of one laminated polarizing film (polarizing film) having a predetermined transverse width.

Therefore, in a more preferable embodiment, the first cover sheets 7a are provided on both the left and right sides of the first warm air duct 5A in the width direction so as to cover the regions corresponding to the right and left ends of the first laminated polarizing film (first polarizing film) in the width direction.

The second cover sheets 7b are provided on the left and right sides in the width direction of the first warm air duct 5A so as to cover the regions corresponding to the right and left ends in the width direction of the second laminated polarizing film (second polarizing film).

The third cover sheets 7c are provided on the left and right sides in the width direction of the first warm air duct 5A so as to cover the regions corresponding to the right and left ends in the width direction of the third laminated polarizing film (second polarizing film), respectively.

The pair of left and right first covering sheets 7a are disposed on the outermost sides in the width direction of the first warm air duct 5A, the pair of left and right second covering sheets 7b are disposed on the inner side in the width direction than the first covering sheets 7a, and the pair of left and right third covering sheets 7c are disposed on the inner side in the width direction than the second covering sheets 7 b.

The first covering sheet 7a, the second covering sheet 7b, and the third covering sheet 7c (the plurality of covering sheets 7) are arranged with a gap in the width direction so as not to overlap each other.

The cover sheet 7 may be provided in the first warm air duct 5A separately from the first warm air duct 5A, or may be provided in the first warm air duct 5A in a state of being partially connected to the first warm air duct 5A. From the viewpoint of enabling the attachment work of the cover sheet 7 to be performed efficiently, it is preferable that one end portion of the cover sheet 7 is fixed to one side portion of the warm air blowing portion 52 of the first warm air duct 5A, and the opposite end portion of the cover sheet 7 is a free end (see fig. 12 and 13). Further, it is more preferable that the bar member 6 is attached to the opposite end portion of the cover sheet 7 as the free end. As a method of attaching the rod member 6 to the opposite end of the cover sheet 7, an attachment method using a fastener such as a threaded rod or a bolt and nut may be mentioned.

The rod member 6 is, for example, a metal cylinder, and may be solid or hollow (tubular). The rod member 6 is preferably hollow as shown in the drawing from the viewpoint of a small weight and an improved workability. Note that the rod member 6 is not limited to a cylindrical shape, and may have another shape such as a quadrangular prism.

As shown in fig. 12 and 13, the cover sheet 7 in a state of covering the front of the warm air blowout part 52 (the cover sheet 7 in a housed state) is wound around the periphery of the rod member 6 and held by the holding part 8.

The holding portion 8 is provided at one side portion 53 that is one side portion of the warm air blowing portion 52. The holding portion 8 is fixed to a side surface portion 53 of the first warm air duct 5A. As a method of fixing the holding portion 8 to the one side surface portion 53, an attachment method using a fastener such as a threaded rod or a bolt and nut, welding, or the like can be mentioned. The holding portions 8 are provided in a pair in the width direction. The holding portion 8 includes a fixing portion 81 for fixing one end portion of the cover sheet 7 and a receiving portion 82 for holding the rod member 6. The fixing portion 81 is composed of a main rod provided in the holding portion 8 and a sub-rod detachably attached to the main rod. The secondary rod is smaller than the primary rod. As a method of attaching the sub-lever to the main lever, an attachment method using a fastener such as a threaded rod or a bolt and nut may be mentioned. One end of the cover sheet 7 is held between the primary lever and the secondary lever, so that the one end of the cover sheet 7 is fixed to the fixing portion 81 of the holding portion 8. The receiving portion 82 is open on the upper side in the vertical direction (the vertical direction is a direction perpendicular to the horizontal direction), and has a substantially U-shape in front view as shown in fig. 13. The receiving portion 82 is provided at a plurality of positions, and in the illustrated example, at three different positions in the front view.

Specifically, one end of each of the first cover sheet 7a, the second cover sheet 7b, and the third cover sheet 7c is fixed to one side surface portion 53 which is one side portion of the warm air blowout part 52. In the illustrated example, one end portion of each of the first covering sheet 7a, the second covering sheet 7b, and the third covering sheet 7c is fixed to the fixing portion 81 of the holding portion 8. Therefore, the first cover sheet 7a, the second cover sheet 7b, and the third cover sheet 7c are fixed at one end portion thereof to the one side surface portion 53 via the holding portion 8.

Opposite end portions of the first covering sheet 7a, the second covering sheet 7b and the third covering sheet 7c are set as free ends. The rod member 6 is attached to each of opposite end portions of the first covering sheet 7a, the second covering sheet 7b, and the third covering sheet 7 c. Both end portions of the rod member 6 are made larger in diameter for easy gripping.

The pair of left and right first covering sheets 7a are wound around the rod member 6 attached to the opposite end portions thereof. The rod member 6 wrapped with the first covering sheet 7a is placed on the receiving portion 82 of the holding portion 8 and held by the holding portion 8.

The pair of left and right second covering sheets 7b are wound around the rod member 6 attached to the opposite end portions thereof. The rod member 6 wrapped with the second covering sheet 7b is placed on the other receiving portion 82 of the holding portion 8 and held by the holding portion 8.

The pair of left and right third covering sheets 7c are wound around the rod member 6 attached to the opposite end portions thereof. The rod member 6 around which the third covering sheet 7c is wound is placed on the further receiving portion 82 of the holding portion 8 and held by the holding portion 8.

On the other hand, the other side surface portion 54, which is the opposite side portion of the warm air blowing portion 52, is provided with the locking portion 9 that can lock the rod member 6. The locking portion 9 is fixed to the other side surface portion 54 of the first warm air duct 5A. As a method of fixing the locking portion 9 to the other side surface portion 54, an attachment method using a fastener, welding, or the like can be cited. The locking portion 9 is provided in a pair of left and right in the width direction. The locking portion 9 has a groove portion 91 for receiving the rod member 6 and a columnar portion 92 for bringing the cover sheet 7 into contact. The groove 91 is open on the upper side in the vertical direction (the vertical direction is a direction perpendicular to the horizontal direction), and has a substantially U-shape in front view as shown in fig. 13. The cylindrical portion 92 extends in the width direction. The columnar portion 92 may be fixedly provided to the locking portion 9, or may be rotatably supported by the locking portion 9. Preferably, the cylindrical portion 92 is rotatably provided.

The groove 91 is disposed closer to the other side surface 54, and the columnar portion 92 is disposed outside the groove 91.

Note that the holding portion 8 and the locking portion 9 are made of metal, for example.

< second warm air duct >

Fig. 14 is a plan view of the second warm air duct 5B in a state before the warm air blowout part 52 is covered with the cover sheet 7.

Referring to fig. 7 and 14, the second warm air duct 5B is formed of an elongated hollow body extending in the width direction, and has a warm air blowing unit 52 disposed opposite to the laminated polarizing film (polarizing film), as in the first warm air duct 5A.

As can be seen by comparing fig. 7 and 14 showing the second warm air duct 5B and fig. 7 to 13 showing the first warm air duct 5A, the second warm air duct 5B: (a) the warm air blowing unit 52 is disposed on the upper side in the vertical direction; (b) the locking portion 9 is not provided. The details of the second warm air duct 5B are the same as the above-described < first warm air duct > column except for the above-described (a) and (B). Therefore, in the description of the second warm air duct 5B, the "first warm air duct 5A" in the column of < first warm air duct > is changed to the "second warm air duct 5B", and a specific example of the second warm air duct 5B will be described here.

Note that, the other side surface portion 54 of the second warm air duct 5B may be provided with an engagement portion (not shown) for engaging the rod member 6.

< first warm air duct and second warm air duct in which warm air blowing part is covered with covering sheet >

As described above, the first warm air duct 5A shown in fig. 7 to 13 and the second warm air duct 5B shown in fig. 7 and 14 are not covered with the covering sheet 7 and the covering sheet 7 is held by the holding portion 8, without covering the warm air blowing portion 52. That is, the first warm air duct 5A and the second warm air duct 5B are in a state before the drying device 42 is operated and before the cover sheet 7 is attached. When the drying device 42 is operated, the cover sheet 7 covers the area of the warm air blowing unit 52 of the first warm air duct 5A corresponding to the widthwise end of the laminated polarizing film 2Y (polarizing film). Similarly, the cover sheet 7 covers the area corresponding to the widthwise end of the laminated polarizing film 2Y (polarizing film) in the warm air blowing section 52 of the second warm air duct 5B.

Fig. 15 is a front view showing a step of covering the warm air blowing portion 52 of the first warm air duct 5A with the cover sheet 7.

As shown in fig. 15 (a), the cover sheet 7 is taken out from the holding portion 8. In the illustrated example, the first covering sheet 7a is taken out. Since the rod member 6 is attached to the opposite end of the cover sheet 7 and the cover sheet 7 is wound around the rod member 6, the rod member 6 is detached from the holding portion 8 and the cover sheet 7 is pulled out while the cover sheet 7 is paid out from the rod member 6. Since one end portion of the cover sheet 7 is fixed to the holding portion 8, the cover sheet 7 that is pulled out does not fall off from the first warm air duct 5A. Next, as shown in fig. 15 (b), the cover sheet 7 is inverted in the columnar portion 92 of the locking portion 9 while being mounted on the warm air blowing portion 52. Finally, as shown in fig. 15 (c), the rod member 6 is inserted into the groove 91 of the locking portion 9. The cover sheet 7 extends from the holding portion 8 (one side portion of the warm air blowing portion 52) to the locking portion 9 (the opposite side portion of the warm air blowing portion 52), and spans over a portion including the warm air blowing portion 52.

By simply detaching the rod member 6 from the holding portion 8 and locking the rod member 6 to the locking portion 9 in this manner, the cover sheet 7 can be attached to the warm air blowing portion 52 extremely easily.

Fig. 16 is a cross-sectional enlarged view showing a state where the first cover sheet 7a is attached to the warm air blowing section 52 of the first warm air duct 5A. Fig. 16 is an enlarged sectional view of the first warm air duct 5A in the state of fig. 15 (c) taken at a position of the covering sheet 7 in the vertical direction. The thin broken line in fig. 16 indicates a transport path of the laminated polarizing film 2Y.

Referring to fig. 16, the rod member 6 inserted into the groove portion 91 is suspended. One end 71 of the cover sheet 7 is fixed to one side surface 53 (holding portion 8) which is one side portion of the warm air blowing portion 52, and the rod member 6 attached to the opposite end 72 of the cover sheet 7 is in a suspended state, so that the cover sheet 7 is in a state in which tension is applied by the weight of the rod member 6. In particular, the cover sheet 7 is applied with the tension and is brought into close contact with the warm air blowout part 52. In this way, since the cover sheet 7 covers the area of the warm air blowout part 52 in a tensioned state, the cover sheet 7 is less likely to separate from the warm air blowout part 52. As a method of putting the cover sheet 7 in a tensioned state when covering the area of the warm air blowout part 52, for example, a method of pulling the cover sheet 7 using an elastic member such as a spring can be employed. In this regard, as described above, if the cover sheet 7 is tensioned by the weight of the rod member 6 (the weight of the rod member 6), the structure is extremely simple. The bar member 6 can be used as an operation portion when taking out the cover sheet 7 from the holding portion 8 or storing the cover sheet 7 in the holding portion 8.

Fig. 17 is a bottom view of the first warm air duct 5A in a state where the first cover sheet 7a is attached to the warm air blowing unit 52, as viewed from the vertical direction. Fig. 17 is a view seen from the direction of arrow XVII of fig. 6. Note that, in fig. 17, the width-direction intermediate portions that continue to have the same configuration are omitted (the same applies to fig. 19 to 21).

Referring to fig. 17, the cover sheet 7 covers a region corresponding to the widthwise end of the laminated polarizing film 2Y (polarizing film) in the warm air blowout part 52. In the figure, both width-direction side edges 2Y-1 and 2Y-2 of the laminated polarizing film 2Y (polarizing film) are indicated by virtual lines, i.e., two-dot chain lines. Note that the width direction end of the laminated polarizing film 2Y (polarizing film) refers to a side edge vicinity portion including a width direction side edge.

Preferably, the cover sheet 7 is disposed so that the widthwise side edges of the laminated polarizing film 2Y are positioned at the substantially central portion in the widthwise direction of the cover sheet 7. One end portion of the cover sheet 7 is fixed in such an arrangement.

In the illustrated example, the outermost first cover sheets 7a cover the regions corresponding to both widthwise ends of the laminated polarizing film 2Y. The first cover sheet 7a is a cover sheet 7 disposed so as to be able to cover regions corresponding to both widthwise ends of the first laminated polarizing film (first polarizing film), respectively. Accordingly, fig. 17 is an example of a case where the first laminated polarizing film having the widest width is dried. Note that the transverse width W1 of the first laminated polarizing film is the length between both widthwise edges.

Since the area of the warm air blowout part 52 is covered with the first cover sheet 7a, even if the widthwise end portion thereof curls when the first laminated polarizing film is dried while being conveyed, the warm air blowout part 52 is not directly contacted. Since the end of the first laminated polarizing film is in contact with the cover sheet 7 even if the end is curled, damage to the end can be prevented.

Fig. 18 is a cross-sectional enlarged view showing a state where the first cover sheet 7a is attached to the warm air blowing section 52 of the second warm air duct 5B. The thin broken line in fig. 18 indicates a transport path of the laminated polarizing film 2Y.

Referring to fig. 18, similarly to the first warm air duct 5A, the rod member 6 is detached from the holding portion 8 in the second warm air duct 5B, and the area of the warm air blowing portion 52 is covered with the first cover sheet 7a, and the rod member 6 is taken to the other side surface portion 54. By simply moving the rod member 6 to the other side surface portion 54 in this manner, the cover sheet 7 can be attached to the warm air blowing portion 52 extremely easily. In the illustrated example, the case where the first cover sheet 7a is attached is exemplified.

In the second warm air duct 5B, the covering sheet 7 covers the area of the warm air blowing unit 52 in a state where tension is applied by the weight of the rod member 6, as in the first warm air duct 5A.

Fig. 19 is a bottom view of the second warm air duct 5B in a state where the first cover sheet 7a is attached to the warm air blowing unit 52, as viewed from the vertical direction. Fig. 19 is a view seen from the direction of arrow XIX of fig. 6.

Referring to fig. 19, the cover sheet 7 also covers the second warm air duct 5B, similarly to the first warm air duct 5A, in a region corresponding to the widthwise end of the laminated polarizing film 2Y (polarizing film) in the warm air blowing unit 52. In the figure, both width-direction side edges 2Y-1 and 2Y-2 of the laminated polarizing film 2Y (polarizing film) are indicated by virtual lines, i.e., two-dot chain lines.

In the illustrated example, the first cover sheets 7a disposed outermost cover regions corresponding to both ends in the width direction of the laminated polarizing film 2Y.

Since the second warm air duct 5B is also covered with the first cover sheet 7a in the area of the warm air blowout part 52, the widthwise end portion thereof does not come into direct contact with the warm air blowout part 52 even if it curls when the first laminated polarizing film is dried while being conveyed. Thus, damage to the end of the first laminated polarizing film can be prevented.

[ basic polarizing film and method for producing laminated polarizing film ]

< step of covering the warm air blowing part with the cover sheet >

Before the drying device 42 is operated, a predetermined cover sheet 7 is taken out from the first warm air duct 5A and the second warm air duct 5B in the state shown in fig. 7, and is attached to the warm air blowing unit 52. The step of covering the warm air blowout part 52 with the cover sheet 7 and the structure of the first warm air duct 5A and the second warm air duct 5B after covering with the cover sheet 7 can be referred to as the column of < the first warm air duct and the second warm air duct in which the warm air blowout part is covered with the cover sheet > described above.

For example, as shown in fig. 16 to 19, a first warm air duct 5A and a second warm air duct 5B in which regions corresponding to both widthwise ends of the first laminated polarizing film are covered with the first cover sheet 7a are prepared.

< basic polarizing film and Process for producing laminated polarizing film >

The manufacturing apparatus 10 having the drying apparatus 42 provided with the cover sheet 7 was operated to manufacture a basic polarizing film and a laminated polarizing film.

The production of the basic polarizing film and the production of the laminated polarizing film can be carried out by conventionally known methods. The following description is made for simplicity.

Referring to fig. 6, the untreated film material Y is pulled out from the feeding portion, and the film material Y is conveyed to the swelling treatment tank 311 by the conveying device 101 to swell the film material Y. After that, the film material Y is dyed in the dyeing tank 312, and then crosslinked in the crosslinking tank 313. The crosslinked film material Y is stretched while being conveyed in the stretching liquid in the stretching treatment tank 314. After the dyed and stretched film raw material Y is washed in the washing treatment tank 315, it is dried by the drying device 32, thereby obtaining the basic polarizing film 1Y.

An arbitrary film is laminated on the long strip-shaped basic polarizing film 1Y thus obtained.

As shown in fig. 6, an adhesive is applied to one surface of a first arbitrary film 21Y (e.g., a protective film) in a long strip shape by an adhesive applying section 412. An adhesive is applied to one surface of the second arbitrary film 22Y (for example, a protective film) in a long strip shape by the adhesive applying section 413. So that they are applied to one side and the opposite side of the basic polarizing film 1Y and passed through the nip roller. The adhesive of the laminated body bonded together is cured. In the case of using an active energy ray-curable adhesive, the adhesive is irradiated with active energy rays so that the adhesive is cured, and a laminated polarizing film 2Y composed of a first arbitrary film/adhesive layer/basic polarizing film/adhesive layer/second arbitrary film is obtained.

< drying Process >

The laminated polarizing film 2Y is introduced into a drying device 42. In the drying device 42, warm air is blown out from the warm air blowing portions 52 of the first warm air duct 5A and the second warm air duct 5B. The volume and temperature of the warm air are not particularly limited, and may be set in the same manner as in the conventional art. The laminated polarizing film 2Y (polarizing film) is dried by blowing warm air from the first warm air duct 5A and the second warm air duct 5B covered with the cover sheet 7 and conveying the laminated polarizing film 2Y in the longitudinal direction. The warm air from the first warm air duct 5A is blown in a direction substantially orthogonal to, for example, one surface of the laminated polarizing film 2Y, and the warm air from the second warm air duct 5B is blown in a direction substantially orthogonal to, for example, the opposite surface of the laminated polarizing film 2Y. After blowing warm air and drying, the laminated polarizing film 2Y is wound up.

The laminated polarizing film 2Y is dried by warm air, but at this time, the end of the laminated polarizing film 2Y in the width direction may curl. In particular, since the laminated polarizing film 2Y (polarizing film) includes a polarizing plate, end curl is likely to occur during drying.

Conventionally, the curled end portion contacts the hot air blowing portion having the unevenness, the end portion of the polarizing film is damaged, and the film is slightly chipped off, resulting in generation of film residue. This causes a vicious circle in which the film residue is accumulated on the warm air blowout part and adheres to the curled end.

In this regard, according to the present invention, the area of the warm air blowout part 52 corresponding to the widthwise end of the laminated polarizing film 2Y (polarizing film) is covered by the cover sheet 7, and therefore the curled end contacts the surface of the cover sheet 7. Since the cover sheet 7 has excellent surface smoothness, the end of the laminated polarizing film 2Y is less likely to be damaged, and the generation of film residue due to the polarizing film can be prevented.

Fig. 16 to 19 show a case where the first laminated polarizing film is manufactured and dried, and the cover sheet 7 is replaced in a case where the laminated polarizing film having a transverse width different therefrom is manufactured.

Specifically, the first covering sheet 7a is removed from the first warm air duct 5A in a reverse step to that in fig. 15, and the first covering sheet 7a is temporarily returned to the state shown in fig. 8 to 13. Next, the second cover sheet 7b is removed, and the second cover sheet 7b is attached to the warm air blowing portion 52 of the first warm air duct 5A in accordance with the procedure described in fig. 15. The second warm air duct 5B is also replaced with the second cover sheet 7B from the first cover sheet 7a, similarly to the first warm air duct 5A.

Fig. 20 is a bottom view of the first warm air duct 5A in a state where the second cover sheet 7b is attached to the warm air blowing unit 52, as viewed from the vertical direction.

Referring to fig. 20, the second cover sheet 7b covers the area corresponding to the widthwise end of the second laminated polarizing film in the warm air blowout part 52. In the figure, both side edges in the width direction of the laminated polarizing film (polarizing film) are indicated by two-dot chain lines, which are virtual lines. The transverse width W2 of the second laminated polarizing film is smaller than the transverse width W1 of the first laminated polarizing film.

The first warm air duct 5A and the second warm air duct 5B covered with the second cover sheet 7B are prepared, and the second laminated polarizing film is dried while being conveyed, whereby the second laminated polarizing film can be prevented from being damaged at the end portions in the width direction.

Similarly, the third cover sheet 7c may be attached to the warm air blowing portions 52 of the first warm air duct 5A and the second warm air duct 5B.

Fig. 21 is a bottom view of the first warm air duct 5A in a state where the third cover sheet 7c is attached to the warm air blowing unit 52, as viewed from the vertical direction.

Referring to fig. 21, the third cover sheet 7c covers the area corresponding to the widthwise end of the third laminated polarizing film in the warm air blowout part 52. The transverse width W3 of the third laminated polarizing film is smaller than the transverse width W2 of the second laminated polarizing film.

The first warm air duct 5A and the second warm air duct 5B covered with the third cover sheet 7c are prepared, and the third laminated polarizing film is dried while being conveyed, whereby damage to the end portions in the width direction of the third laminated polarizing film can be prevented.

The drying method of the present invention is a method in which two or more cover sheets 7 (first cover sheet 7a, second cover sheet 7B, and third cover sheet 7c) are provided on the first warm air duct 5A and the second warm air duct 5B, and the area of the warm air blowout part 52 is covered with a cover sheet 7 selected from these cover sheets 7, depending on the laminated polarizing film (polarizing film) having different lateral widths.

Therefore, according to the drying method and the drying apparatus of the present invention, it is possible to dry laminated polarizing films (polarizing films) having various lateral widths, and to prevent damage to their ends.

In addition, since the plurality of cover sheets 7 are provided on the warm air duct 5 in accordance with the type (difference in lateral width) of the laminated polarizing film to be dried, the cover sheets 7 can be easily replaced.

In particular, since one end portion of the cover sheet 7 is fixed and the rod member 6 is attached to the opposite end portion, the cover sheet 7 can be attached and stored by operating the rod member 6. Therefore, the replacement work of the cover sheet 7 can be easily performed.

[ modified examples ]

Note that the drying device 42 is provided with a first warm air duct 5A and a second warm air duct 5B corresponding to the laminated polarizing film 2Y that is transported substantially horizontally (in other words, the transport path of the polarizing film is substantially horizontal). However, the present invention is not limited to the case where the first warm air duct 5A and the second warm air duct 5B are disposed in the polarizing film which is transported substantially horizontally, and for example, the first warm air duct 5A and the second warm air duct 5B may be disposed in the polarizing film which is transported in a meandering manner, or the first warm air duct 5A and the second warm air duct 5B may be disposed in the polarizing film which is transported in a direction inclined with respect to the vertical direction or the horizontal direction.

[ uses of polarizing film, etc. ]

The polarizing film (basic polarizing film and laminated polarizing film) of the present invention is typically used as an optical film for displays such as liquid crystal display devices and organic display devices.

The polarizing film of the present invention is not limited to the case of being used in the display, and can be used in applications other than displays. Applications other than displays include optical devices, buildings, medical and food fields, and the like. When the polarizing film is used in an optical device, the polarizing film is processed into, for example, a polarizing lens, a transparent radio wave blocking film, or the like. When the polarizing film is used in an electronic device, the polarizing film is processed into, for example, a film for a light control window. When the polarizing film is used in the medical/food field, the polarizing film is processed into, for example, a light degradation prevention film.

Claims

1. A polarizing film drying apparatus for blowing warm air to a long strip-shaped polarizing film while the polarizing film is being conveyed in a longitudinal direction, comprising:

a warm air duct having a warm air blowing section disposed to face the surface of the polarizing film;

a cover sheet that covers a region corresponding to a widthwise end of the polarizing film in the warm air blowout part.

2. The drying device for a polarizing film according to claim 1,

one end portion of the cover sheet is fixed to one side portion of a warm air blowing portion of the warm air duct, and an opposite end portion of the cover sheet is set to be a free end,

a rod member is attached to an opposite end portion of the cover sheet, a locking portion capable of locking the rod member is provided on an opposite side portion of the warm air blowing portion of the warm air duct,

the covering sheet covers the region by locking the rod member to the locking portion.

3. The drying device for a polarizing film according to claim 1 or 2,

the cover sheet covers the region in a state in which tension is applied.

4. The drying device for a polarizing film according to claim 1 or 2,

the covering sheet has more than two pieces of cloth,

the first cover sheet covers a region corresponding to the widthwise end of the first polarizing film,

the second cover sheet covers the widthwise end of the second polarizing film having a narrower width than the first polarizing film.

5. The drying device for a polarizing film according to claim 3,

the covering sheet has more than two pieces of cloth,

6. The drying device for a polarizing film according to claim 1 or 2,

the cover sheets are formed of a pair of left and right sheets so as to cover regions corresponding to both ends in the width direction of the polarizing film, respectively.

7. The drying device for a polarizing film according to claim 1 or 2,

the cover sheet includes a polyimide-based resin sheet.

8. A method for drying a long strip-shaped polarizing film while the polarizing film is being conveyed in a longitudinal direction, comprising:

covering, with a cover sheet, a region corresponding to a widthwise end of the polarizing film in a warm air blowout part of a warm air duct having the warm air blowout part disposed opposite to a surface of the polarizing film;

the polarizing film is dried by blowing warm air from a warm air duct covered with the cover sheet while being conveyed in the longitudinal direction.

9. The method for drying a polarizing film according to claim 8,

the warm air pipeline is provided with more than two covering sheets,

covering the region with a cover sheet selected from among the two or more cover sheets according to a polarizing film having a different transverse width.