JP2019211640A - Method for manufacturing polarizing film roll - Google Patents

Abstract

To provide a method for manufacturing a polarizing film roll, capable of suppressing the occurrence of a winding dent in a polarizing film end portion.SOLUTION: The method for manufacturing a polarizing film roll includes the step of winding a polarizing film around a winding core. The polarizing film has a thickness of 100 μm or less and a length of 500 m or more and 4000 m or less; in the process, the polarizing film is wound around the winding core while applying a tension y so that the tension y calculated by the following formula (1) becomes 30 N or more and 150 N or less from when the amount of winding becomes 500 m or more till finishing the winding. The tension y=a{1-(bx/400000)} (1), a: a tension when starting the winding (a>30 N), b: a taper rate(%)={(the tension when starting the winding-a tension when assuming 4000 m winding)/the tension when starting the winding}×100, and x: the amount of winding (500 m≤x≤4000 m).SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a polarizing film roll.

  In various image display devices, a polarizing film is used for image display. For example, in a liquid crystal display device (LCD), it is indispensable to dispose polarizing films on both sides of a glass substrate on which a liquid crystal panel surface is formed because of its image forming method. Further, in the organic EL display device, a circularly polarizing film in which a polarizing film and a quarter wavelength plate are laminated is disposed on the viewing side of the organic light emitting layer in order to shield the specular reflection of external light on the metal electrode.

  As the polarizing film, generally, a polyvinyl alcohol film and a polarizer made of a dichroic material such as iodine are bonded to one or both surfaces with a protective film bonded with a polyvinyl alcohol adhesive or the like. ing.

  In recent years, image display devices such as liquid crystal display devices have become thinner, and accordingly, the polarizing film is also required to be thinner.

  A polarizing film is a so-called roll-to-roll film in which a raw film is usually fed from a raw roll while various processes are applied to the raw film, and the resulting long polarizing film is wound around a core.・ Manufactured by roll method.

  As described above, the polarizing film is manufactured by a roll-to-roll method and stored as a polarizing film roll. However, the polarizing film unwound from the polarizing film roll has defects such as streaks, dents, or curls. There was a problem that it was easy.

  For example, in Patent Document 1, a winding streak defect (a height difference generated between the winding start end of the polarizing plate and the outer peripheral surface of the core, that is, generated by pressing the wound polarizing plate on the stepped portion, For the purpose of suppressing the stripe-shaped dent defect extending in the width direction of the polarizing plate), a winding core provided with a first protrusion and a second protrusion extending in the circumferential direction on the outer peripheral surface, and wound around the winding core. The polarizing plate comprises a polarizer and a protective film laminated on at least one surface thereof, and the polarizing plate has one end in the width direction of the protective film. There has been proposed a polarizing plate roll wound around the core such that a region is located on the first convex portion and the other end region is located on the second convex portion.

  Moreover, in patent document 2, the process of adjusting the moisture content of the raw material film used as the raw material of a transparent film for the purpose of preventing generation | occurrence | production of a reverse curl and a wave curl, and the raw material film after adjusting a moisture content The manufacturing method of a polarizing plate including the process of bonding on the single side | surface or both surfaces of a polarizing film is proposed.

JP, 2006-85331, A JP 2014-191155 A

  However, the technique of Patent Document 1 requires a specially structured core, and there is a problem that a general core cannot be used. Moreover, in the technique of patent document 2, it is necessary to adjust the moisture content of a raw material film, and there exists a problem that manufacture becomes complicated.

  An object of this invention is to provide the manufacturing method of the polarizing film roll which can suppress generation | occurrence | production of the winding dent in the polarizing film edge part.

  As a result of intensive studies, the present inventors have found that the above problems can be solved by the following method for producing a polarizing film roll, and have completed the present invention.

That is, this invention is a manufacturing method of a polarizing film roll including the process of winding up a polarizing film on a core,
The polarizing film has a thickness of 100 μm or less and a length of 500 m or more and 4000 m or less,
In the step, the polarizing film is applied while applying the tension y so that the tension y calculated by the following formula (1) is 30N or more and 150N or less from the time when the winding amount becomes 500 m or more to the end of winding. The present invention relates to a method for producing a polarizing film roll, which is wound around a core.
Tension y = a {1- (bx / 400000)} (1)
a: Tension at the start of winding (a> 30N)
b: Taper ratio (%) = {(Tension at the start of winding--Tension at the time of winding up to 4000 m) / Tension at the start of winding} × 100
x: Winding amount (500 m ≦ x ≦ 4000 m)

  The polarizing film preferably has a length of 1000 to 4000 m, and the tension y when the winding amount reaches the length is preferably 35N or more and 145N or less.

  It is preferable that the polarizing film has a protective film on one or both sides of the polarizer via an adhesive layer.

  The polarizer preferably has a thickness of 20 μm or less.

  When the thickness of the polarizing film is 100 μm or less, the rigidity of the polarizing film is low. Therefore, when the polarizing film is tensioned and wound around the core and stored, a dent is generated at the end of the unwound polarizing film. Cheap. In particular, when a one-side drive roll device is used, a difference in winding tension tends to occur in the width direction of the polarizing film roll. And it is thought that a polarizing film roll deform | transforms in order to eliminate the tension | tensile_strength at the time of storage of a polarizing film roll, and as a result, a dent will generate | occur | produce at the edge part of a polarizing film. A polarizing film having such an end dent has a problem that the roll transportability is lowered or the yield is lowered because it cannot be used as a product. However, by winding the polarizing film around the core while adjusting the tension y to be 30N or more and 150N or less from the time when the winding amount is 500 m or more to the end of winding as in the present invention, Even if it is a polarizing film with thickness of 100 micrometers or less, generation | occurrence | production of the winding dent in a polarizing film edge part can be suppressed effectively. In particular, the method for producing a polarizing film roll of the present invention is effective when a one-side drive roll device is used. According to the method for producing a polarizing film roll of the present invention, it is possible to reduce the tension difference in the width direction of the polarizing film roll at the time of winding, thereby effectively suppressing the occurrence of dents at the end of the polarizing film. it can.

It is the schematic which shows the evaluation method of winding deviation. It is the schematic which shows the preparation methods of the sample in evaluation of a winding dent. It is the schematic which shows the measuring method of the maximum depth in evaluation of a winding dent.

The method for producing a polarizing film roll of the present invention includes a step of winding the polarizing film around a core,
The polarizing film has a thickness of 100 μm or less and a length of 500 m or more and 4000 m or less,
In the step, the polarizing film is applied while applying the tension y so that the tension y calculated by the following formula (1) is 30N or more and 150N or less from the time when the winding amount becomes 500 m or more to the end of winding. The present invention relates to a method for producing a polarizing film roll, which is wound around a core.
Tension y = a {1- (bx / 400000)} (1)
a: Tension at the start of winding (a> 30N)
b: Taper ratio (%) = {(Tension at the start of winding--Tension at the time of winding up to 4000 m) / Tension at the start of winding} × 100
x: Winding amount (500 m ≦ x ≦ 4000 m)

  The polarizing film is not particularly limited as long as it has a thickness of 100 μm or less and a length of 500 m or more and 4000 m or less. The polarizing film preferably has a thickness of 80 μm or less, more preferably 70 μm or less. The polarizing film is usually 10 μm or more, preferably 15 μm or more from the viewpoints of rigidity, mechanical strength, handleability, and the like. The polarizing film preferably has a length of 700 m or more, more preferably 800 m or more, further preferably 1000 m or more, further preferably 1500 m or more, and further preferably 2000 m or more, and further preferably Is 2500 m or more. Moreover, it is preferable that the said polarizing film is 50-200 cm in width, More preferably, it is 100-150 cm.

  It is preferable that the polarizing film has a protective film on one or both sides of the polarizer via an adhesive layer. The polarizing film may further include one or more additional layers such as the following functional layer, easy adhesion layer, surface protective film, pressure-sensitive adhesive layer, optical layer, and separator.

  As the polarizer, a known one can be used without particular limitation, but the thickness is preferably 20 μm or less from the viewpoint of reducing the thickness and the generation of cracks. The thickness of the polarizer is more preferably 18 μm or less, still more preferably 16 μm or less, and still more preferably 15 μm or less. On the other hand, the thickness of the polarizer is preferably 2 μm or more, and more preferably 3 μm or more.

  A polarizer using a polyvinyl alcohol-based resin is used. Examples of polarizers include dichroic iodine and dichroic dyes on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. Examples thereof include polyene-based oriented films such as those obtained by adsorbing substances and uniaxially stretched, polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, a polarizer composed of a polyvinyl alcohol film and a dichroic substance such as iodine is preferable.

  A polarizer obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching it can be produced, for example, by dyeing polyvinyl alcohol in an aqueous solution of iodine and stretching it 3 to 7 times the original length. If necessary, it may contain boric acid, zinc sulfate, zinc chloride or the like, or may be immersed in an aqueous solution of potassium iodide or the like. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol film surface with stains and antiblocking agents by washing the polyvinyl alcohol film with water, the polyvinyl alcohol film is also swollen to prevent unevenness such as uneven coloring. is there. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. The film can be stretched even in an aqueous solution of boric acid or potassium iodide or in a water bath.

  The polarizer preferably contains boric acid from the viewpoint of stretching stability and humidification reliability. The boric acid content contained in the polarizer is preferably 22% by weight or less, more preferably 20% by weight or less, based on the total amount of the polarizer, from the viewpoint of suppressing the occurrence of cracks. From the viewpoint of stretching stability and humidification reliability, the boric acid content with respect to the total amount of the polarizer is preferably 10% by weight or more, and more preferably 12% by weight or more.

As a thin polarizer, typically,
Patent No. 4751486,
Japanese Patent No. 4751481,
Patent No. 4815544,
Patent No. 5048120,
International Publication No. 2014/077599 pamphlet,
International Publication No. 2014/077636 Pamphlet,
Or the thin polarizer obtained from the production method described therein.

  As the thin polarizer, among the production methods including the step of stretching in the state of a laminate and the step of dyeing, Patent No. 4751486, Patent, in that it can be stretched at a high magnification and the polarization performance can be improved. What is obtained by the manufacturing method including the process of extending | stretching in the boric-acid aqueous solution which is described in the 4751481 specification and the patent 4815544 specification is preferable, and especially described in the patent 4751481 specification and the patent 4815544 specification. What is obtained by the manufacturing method including the process of extending | stretching in the air auxiliary before extending | stretching in the boric-acid aqueous solution which has this is preferable. These thin polarizers can be obtained by a production method including a step of stretching a polyvinyl alcohol-based resin (hereinafter also referred to as PVA-based resin) layer and a stretching resin base material in a laminated state and a step of dyeing. With this production method, even if the PVA-based resin layer is thin, it can be stretched without problems such as breakage due to stretching by being supported by the stretching resin substrate.

  As the material for the protective film, a material excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like is preferable. For example, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, styrene such as polystyrene and acrylonitrile / styrene copolymer (AS resin) And polymers based on polycarbonate and polycarbonate. In addition, polyethylene, polypropylene, polyolefins having a cyclo or norbornene structure, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers , Polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy polymer, or the above Polymer blends and the like can also be mentioned as examples of the polymer forming the protective film.

  The protective film may contain one or more arbitrary appropriate additives. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a release agent, a coloring inhibitor, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent.

  The content of the polymer in the protective film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, and still more preferably 70 to 97% by weight. When content of the said polymer in a protective film is less than 50 weight%, there exists a possibility that the high transparency etc. which the said polymer originally has cannot fully be expressed.

  As the protective film, a retardation film, a brightness enhancement film, a diffusion film, and the like can also be used. Examples of the retardation film include those having a front retardation of 40 nm or more and / or a retardation having a thickness direction retardation of 80 nm or more. The front phase difference is usually controlled in the range of 40 to 200 nm, and the thickness direction phase difference is usually controlled in the range of 80 to 300 nm. In the case where a retardation film is used as the protective film, the retardation film functions also as a protective film for the polarizer, so that the thickness can be reduced.

  Examples of the retardation film include a birefringent film formed by uniaxially or biaxially stretching a thermoplastic resin film. The stretching temperature, stretching ratio, and the like are appropriately set depending on the retardation value, film material, and thickness.

  Although the thickness of a protective film can be determined suitably, it is about 1-50 micrometers from points, such as workability | operativity, such as intensity | strength and a handleability, and thin-layer property. The thickness of the protective film is preferably 5 to 50 μm, more preferably 10 to 50 μm, and still more preferably 10 to 40 μm.

  A functional layer such as a hard coat layer, an antireflection layer, an antisticking layer, a diffusion layer or an antiglare layer can be provided on the surface of the protective film to which the polarizer is not adhered. In addition, the hard coat layer, the antireflection layer, the antisticking layer, the diffusion layer, the antiglare layer, and other functional layers can be provided on the protective film itself, or can be provided separately from the protective film. it can.

  The adhesive layer is formed of an adhesive. The type of the adhesive is not particularly limited, and various types can be used. The adhesive layer is not particularly limited as long as it is optically transparent. Examples of the adhesive include water-based, solvent-based, hot-melt-based, active energy ray-curable types, and the like. Or an active energy ray hardening-type adhesive agent is suitable.

  Examples of the water-based adhesive include an isocyanate-based adhesive, a polyvinyl alcohol-based adhesive, a gelatin-based adhesive, a vinyl-based latex, and a water-based polyester. The aqueous adhesive is usually used as an adhesive made of an aqueous solution, and usually contains 0.5 to 60% by weight of solid content.

  The active energy ray curable adhesive is an adhesive that cures by an active energy ray such as an electron beam or ultraviolet rays (radical curable type, cationic curable type), for example, in an electron beam curable type or an ultraviolet curable type. Can be used. As the active energy ray curable adhesive, for example, a photo radical curable adhesive can be used. When the photo radical curable active energy ray curable adhesive is used as an ultraviolet curable adhesive, the adhesive contains a radical polymerizable compound and a photo polymerization initiator.

  The adhesive coating method is appropriately selected depending on the viscosity of the adhesive and the target thickness. Examples of coating methods include reverse coaters, gravure coaters (direct, reverse and offset), bar reverse coaters, roll coaters, die coaters, bar coaters, rod coaters and the like. In addition, for coating, a method such as a dapping method can be appropriately used.

  Although the thickness of the said adhesive bond layer can be determined suitably, it is preferable that it is 0.01-5 micrometers, More preferably, it is 0.05-3 micrometers, More preferably, it is 0.05-2 micrometers.

  In addition, in laminating | stacking a polarizer and a protective film, an easily bonding layer can be provided between a protective film and an adhesive bond layer. The easy adhesion layer can be formed of, for example, various resins having a polyester skeleton, a polyether skeleton, a polycarbonate skeleton, a polyurethane skeleton, a silicone-based, a polyamide skeleton, a polyimide skeleton, a polyvinyl alcohol skeleton, and the like. These polymer resins can be used alone or in combination of two or more. Moreover, you may add another additive for formation of an easily bonding layer. Specifically, a stabilizer such as a tackifier, an ultraviolet absorber, an antioxidant, and a heat resistance stabilizer may be used.

  The easy adhesion layer is usually provided in advance on the protective film, and the easy adhesion layer side of the protective film and the polarizer are laminated with an adhesive layer. The easy-adhesion layer is formed by applying and drying a material for forming the easy-adhesion layer on a protective film by a known technique. The material for forming the easy-adhesion layer is usually adjusted as a solution diluted to an appropriate concentration in consideration of the thickness after drying and the smoothness of coating. The thickness after drying of an easily bonding layer becomes like this. Preferably it is 0.01-5 micrometers, More preferably, it is 0.02-2 micrometers, More preferably, it is 0.05-1 micrometer. Note that a plurality of easy-adhesion layers can be provided, but also in this case, the total thickness of the easy-adhesion layers is preferably in the above range.

  The polarizing film may have an adhesive layer.

  In the case of a polarizing film provided with protective films on both sides of the polarizer, the pressure-sensitive adhesive layer is provided on the surface of one protective film directly or via another layer. In addition, you may provide a surface protective film in the surface of the other protective film directly or through another layer.

  In the case of a polarizing film provided with a protective film only on one side of the polarizer, a pressure-sensitive adhesive layer is provided directly or via another layer on the polarizer side. In addition, you may provide a surface protective film in the protective film side directly or through another layer.

  The other layers are not particularly limited, and examples thereof include a known functional layer and an optical layer provided on the polarizing film. Examples of the optical layer include a reflection plate, a semi-transmission plate, a retardation plate (including wavelength plates such as 1/2 and 1/4), a viewing angle compensation film, and a brightness enhancement film. One of the other layers may be provided, or two or more layers may be provided.

  The pressure-sensitive adhesive layer is provided on one side of the polarizing film in order to bond the polarizing film to a cell substrate such as a liquid crystal cell.

  The thickness of the pressure-sensitive adhesive layer is, for example, about 1 to 40 μm, preferably 2 to 40 μm, more preferably 2 to 35 μm, and further preferably 2 to 30 μm.

  For the formation of the pressure-sensitive adhesive layer, an appropriate pressure-sensitive adhesive can be used, and the type thereof is not particularly limited. Adhesives include rubber adhesives, acrylic adhesives, silicone adhesives, urethane adhesives, vinyl alkyl ether adhesives, polyvinyl alcohol adhesives, polyvinyl pyrrolidone adhesives, polyacrylamide adhesives, Examples thereof include cellulose-based pressure-sensitive adhesives.

  Among these pressure-sensitive adhesives, those having excellent optical transparency, suitable wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and excellent weather resistance and heat resistance are preferably used. An acrylic pressure-sensitive adhesive is preferably used as one exhibiting such characteristics.

  As a method for forming the pressure-sensitive adhesive layer, for example, a method of applying the pressure-sensitive adhesive to a release-treated separator and the like, drying and removing the polymerization solvent and the like to form a pressure-sensitive adhesive layer, and then transferring to a polarizing film, or the above Examples include a method of applying a pressure-sensitive adhesive, drying and removing a polymerization solvent, and forming a pressure-sensitive adhesive layer on a polarizing film. In applying the pressure-sensitive adhesive, one or more solvents other than the polymerization solvent may be added as appropriate.

  As the release-treated separator, a silicone release liner is preferably used. In the step of forming a pressure-sensitive adhesive layer by applying and drying a pressure-sensitive adhesive on such a liner, an appropriate method can be appropriately employed as a method for drying the pressure-sensitive adhesive according to the purpose. Preferably, a method of heating and drying the coating film is used. The heat drying temperature is preferably 40 ° C to 200 ° C, more preferably 50 ° C to 180 ° C, and particularly preferably 70 ° C to 170 ° C. By setting the heating temperature within the above range, an adhesive having excellent adhesive properties can be obtained.

  As the drying time, an appropriate time can be adopted as appropriate. The drying time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 10 minutes, and particularly preferably 10 seconds to 5 minutes.

  Various methods are used as a method of forming the pressure-sensitive adhesive layer. Specifically, for example, by roll coat, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, dip roll coat, bar coat, knife coat, air knife coat, curtain coat, lip coat, die coater, etc. Examples thereof include an extrusion coating method.

  When the pressure-sensitive adhesive layer is exposed, the pressure-sensitive adhesive layer may be protected with a sheet (separator) that has been subjected to a release treatment until practical use.

  Examples of the constituent material of the separator include, for example, plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films, porous materials such as paper, cloth, and nonwoven fabric, nets, foam sheets, metal foils, and laminates thereof. A thin film can be used, but a plastic film is preferably used because of its excellent surface smoothness.

  The plastic film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer. For example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, and a vinyl chloride co-polymer are used. Examples thereof include a polymer film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, and an ethylene-vinyl acetate copolymer film.

  For the separator, if necessary, mold release and antifouling treatment with a silicone type, fluorine type, long chain alkyl type or fatty acid amide type release agent, silica powder, etc., coating type, kneading type, vapor deposition type It is also possible to carry out antistatic treatment such as. In particular, the release property from the pressure-sensitive adhesive layer can be further improved by appropriately performing a release treatment such as silicone treatment, long-chain alkyl treatment, or fluorine treatment on the surface of the separator.

  The said surface protection film has a base film and an adhesive layer normally, and protects a polarizing film through the said adhesive layer.

  As the base film of the surface protective film, a film material having isotropic property or close to isotropic property is selected from the viewpoints of inspection property and manageability. Examples of the film material include polyester resins such as polyethylene terephthalate film, cellulose resins, acetate resins, polyether sulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, and acrylic resins. Examples thereof include transparent polymers such as resins. Of these, polyester resins are preferred. The base film can be used as a laminate of one kind or two or more kinds of film materials, and a stretched product of the film can also be used. The thickness of the base film is preferably 10 to 150 μm, more preferably 20 to 150 μm.

  Examples of the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer of the surface protective film include pressure-sensitive adhesives based on (meth) acrylic polymers, silicone-based polymers, polyesters, polyurethanes, polyamides, polyethers, fluorine-based and rubber-based polymers. An agent can be appropriately selected and used. From the viewpoints of transparency, weather resistance, heat resistance and the like, an acrylic pressure-sensitive adhesive having an acrylic polymer as a base polymer is preferable. The thickness (dry film thickness) of the pressure-sensitive adhesive layer is preferably 1 to 40 μm, more preferably 1 to 30 μm.

  The surface protective film can be provided with a release treatment layer on the surface opposite to the surface on which the pressure-sensitive adhesive layer is provided on the base film, using a low adhesion material such as silicone treatment, long-chain alkyl treatment, or fluorine treatment. .

  The polarizing film roll is manufactured by winding the long polarizing film around a winding core. As the winding device, a single-side drive roll device may be used, or a double-side drive roll device may be used, but it is preferable to use a single-side drive roll device.

  The outer diameter of the winding core is not particularly limited, but is preferably 100 to 500 mm, more preferably 150 to 400 mm. What is necessary is just to adjust the width | variety of the said winding core suitably according to the width | variety of the said polarizing film.

In the winding process, the polarization is applied while applying the tension y so that the tension y calculated by the following formula (1) is 30N or more and 150N or less from the time when the winding amount becomes 500 m or more to the end of winding. Wind the film on the core.
Tension y = a {1- (bx / 400000)} (1)
a: Tension at the start of winding (a> 30N)
b: Taper ratio (%) = {(Tension at the start of winding--Tension at the time of winding up to 4000 m) / Tension at the start of winding} × 100
x: Winding amount (500 m ≦ x ≦ 4000 m)

  When the tension y is less than 30N, winding deviation occurs, causing a conveyance failure at the next feeding. On the other hand, when the tension y exceeds 150 N, a winding dent is generated at the end of the polarizing film.

  The tension y when the winding amount reaches 500 m is preferably 40 N or more, more preferably 50 N or more, further preferably 90 N or more, and preferably 130 N or less, more preferably 120 N or less, still more preferably. 110 N or less.

  When the length of the polarizing film is 1000 to 4000 m, the tension y when the winding amount reaches the length (that is, when all the polarizing film is wound) is preferably 35 N or more. More preferably, it is 40N or more, More preferably, it is 45N or more, It is preferable that it is 145N or less, More preferably, it is 140N or less, More preferably, it is 135N or less.

  Moreover, when the length of the polarizing film is 2000 to 3000 m, the tension y when the winding amount reaches the length (that is, when all the polarizing film is wound) is 40 N or more. More preferably, it is 50N or more, More preferably, it is 60N or more, It is preferable that it is 135N or less, More preferably, it is 120N or less, More preferably, it is 110N or less.

  The tension at the start of winding is more than 30N, preferably 35N or more, preferably 300N or less, more preferably 280N or less, further preferably 270N or less, more preferably 200N or less. More preferably, it is 150 N or less.

  As shown in the above formula, the taper rate is a value calculated from the tension at the start of winding and the tension at the time of 4000 m winding. Even when the length of the polarizing film to be actually wound is less than 4000 m, the taper ratio is determined by setting the tension when it is assumed that the film is wound by 4000 m.

  The taper rate is not particularly limited, but is preferably 1% or more, more preferably 5% or more, further preferably 10% or more, further preferably 20% or more, and preferably 99%. Or less, more preferably 90% or less, further preferably 85% or less, further preferably 80% or less, further preferably 75% or less, further preferably 60% or less, Preferably it is 50% or less, More preferably, it is 40% or less.

  The maximum depth of the dent at the end of the polarizing film is preferably 2.5 mm or less, more preferably less than 2.0 mm.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In addition, all the parts and% in each example are based on weight.

(Production of polarizer)
A polyvinyl alcohol film (PVA resin film) having an average polymerization degree of 2400, a saponification degree of 99.9 mol%, and a thickness of 30 μm is immersed in warm water at 30 ° C. and swollen while the length of the PVA resin film is the original length. Uniaxial stretching was performed so as to be 2.0 times the length. Then, it is immersed in an iodine solution at 30 ° C. of 0.3 wt% (weight ratio: iodine / potassium iodide = 0.5 / 8), and the length of the PVA resin film is 3.0 times the original length. Dyeing was performed while uniaxially stretching. Thereafter, the PVA-based resin film was stretched in an aqueous solution of 4% by weight of 6 boric acid and 5% by weight of potassium iodide so that the length of the PVA resin film was 6 times the original length. Further, after an iodine ion impregnation treatment with an aqueous solution (iodine impregnation bath) of 3% by weight of potassium iodide, it was dried in an oven at 60 ° C. for 4 minutes to obtain a polarizer having a thickness of 12 μm.

(Protective film)
<Protective film 1>
25 μm TAC film with HC: TJ25UL (Fuji Film, raw material: triacetyl cellulose polymer) with acrylic resin hard coat coating 40 μm TAC film: KC4UYW (Konica Minolta, raw material: triacetyl cellulose polymer)
37 μmλ / 4TAC with HC: KC2UGR-HC (manufactured by Konica Minolta, raw material: triacetyl cellulose-based polymer) with an acrylic resin hard coat coating <Protective film 2>
25 μm TAC film: KC2UA (manufactured by Konica Minolta, raw material: triacetyl cellulose polymer)
13 μm COP film: ZF-014 (manufactured by Nippon Zeon, raw material: cycloolefin polymer)
Manufacture of 30 μm acrylic film In a 30-liter kettle reactor equipped with a stirrer, temperature sensor, cooling pipe, nitrogen introduction pipe, 8,000 g of methyl methacrylate (MMA), 2,000 g of 2- (hydroxymethyl)
Methyl acrylate (MHMA), 10,000 g of 4-methyl-2-pentanone (methyl isobutyl ketone, MIBK), and 5 g of n-dodecyl mercaptan were charged, and the mixture was heated to 105 ° C. and refluxed while passing nitrogen. By the way, 5.0 g of t-butylperoxyisopropyl carbonate (Kaya-Carbon BIC-7, manufactured by Kayaku Akzo Co., Ltd.) was added as a polymerization initiator, and at the same time, 10.0 g of t-butylperoxyisopropyl carbonate and 230 g of While dropping a solution of MIBK over 4 hours, solution polymerization was performed at about 105 to 120 ° C. under reflux, followed by further aging for 4 hours.
To the obtained polymer solution, 30 g of stearyl phosphate / distearyl phosphate mixture (Phoslex A-18, manufactured by Sakai Chemical Industry Co., Ltd.) was added and cyclized at about 90-120 ° C. for 5 hours under reflux. A condensation reaction was performed. Next, the obtained polymer solution was a vent type screw twin screw extruder having a barrel temperature of 260 ° C., a rotation speed of 100 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1, and a forevent number of 4. (Φ = 29.75 mm, L / D = 30) is introduced at a processing rate of 2.0 kg / h in terms of resin amount, and is further subjected to cyclization condensation reaction and devolatilization in this extruder and extruded. As a result, transparent pellets of the lactone ring-containing polymer were obtained.
The obtained lactone ring-containing polymer was measured for dynamic TG, and a mass loss of 0.17% by mass was detected. The lactone ring-containing polymer had a weight average molecular weight of 133,000, a melt flow rate of 6.5 g / 10 min, and a glass transition temperature of 131 ° C.
The obtained pellets and acrylonitrile-styrene (AS) resin (Toyo AS AS20, manufactured by Toyo Styrene Co., Ltd.) are kneaded and extruded at a mass ratio of 90/10 using a single screw extruder (screw 30 mmφ). Thus, a transparent pellet was obtained. The obtained pellet had a glass transition temperature of 127 ° C.
This pellet was melt-extruded from a coat hanger type T die having a width of 400 mm using a 50 mmφ single-screw extruder to prepare a 120 μm-thick film. This was subjected to a temperature condition of 150 ° C. using a biaxial stretching apparatus. The film was stretched 2.0 times to obtain an acrylic film having a thickness of 30 μm. When the optical properties of the stretched film were measured, the total light transmittance was 93%, the in-plane retardation Δnd was 0.8 nm, and the thickness direction retardation Rth was 1.5 nm.

(Preparation of aqueous adhesive)
A polyvinyl alcohol-based resin containing acetoacetyl groups (average polymerization degree: 1200, saponification degree: 98.5 mol%, acetoacetylation degree: 5 mol%) is dissolved in pure water under a temperature condition of 30 ° C., A water-based adhesive was obtained by adjusting the solid content concentration to 4%.

Example 1
The protective film 1 (25 μm TAC film with HC) and protective film 2 (25 μm TAC film) are each coated on one side with the aqueous adhesive so that the thickness of the adhesive layer after drying is 80 nm. Films 1 and 2 were obtained. Next, under a temperature condition of 23 ° C., the protective film 1 with an adhesive is bonded to one side of the polarizer and the protective film 2 with an adhesive is bonded to the other side of the polarizer by a roll machine, and then 55 ° C. And dried for 6 minutes to produce a polarizing film (thickness 69 μm). And using the one side drive roll apparatus, the produced polarizing film was wound up on the winding core, and the polarizing film roll was produced. The conditions at the time of winding are as shown in Table 1.

Examples 2-11, Comparative Examples 1-5
A polarizing film roll was produced in the same manner as in Example 1 except that the types of the protective films 1 and 2, the thickness and length of the polarizing film, and the winding conditions were changed as shown in Table 1.

  The following evaluation was performed about the polarizing film roll produced by the Example and the comparative example. The results are shown in Table 1.

<Evaluation of winding deviation>
The polarizing film roll produced by the Example and the comparative example was stored for 7 days in 25 degreeC55% environment. Thereafter, with reference to the inner peripheral end of the polarizing film roll, as shown in FIG. 1, the height difference between the inner peripheral end 1 and the outermost peripheral end 2 is measured with a metal scale, and the difference is wound. The amount. The case where the amount of winding deviation was 200 mm or less was evaluated as ◯, and the case where the amount of winding deviation was more than 200 mm was evaluated as x.

<Evaluation of winding dent>
The polarizing film rolls produced in Examples and Comparative Examples were stored for 7 days in an environment of 25 ° C. and 55% and on a bearing carriage. Then, as shown in FIG. 2, the polarizing film was rewound from the polarizing film roll 3, and the polarizing film 4 (length 3 m) of a 3 to 6 m portion was cut off from the start of rewinding. Then, two samples 5 having a width of 200 mm were cut from both ends of the polarizing film 4. As shown in FIG. 3, all the dents 6 were cut from the two samples 5, and the dents 6 were cut in half in the width direction of the polarizing film so as to pass through the center 7. And the winding recessed part 6 cut | disconnected in half was put on the flat plate, the maximum depth D from a plane was measured, and the following reference | standard evaluated. In addition, when there exist multiple winding dent parts 6, the average value of the maximum depth D was employ | adopted.
A: Less than 2.0 mm O: 2.0-2.5 mm
×: More than 2.5mm

  From Table 1, in Examples 1-11 which concern on the manufacturing method of the polarizing film roll of this invention, it turns out that the amount of winding shift is small and the depth of the winding dent part of a polarizing film is also small. On the other hand, in Comparative Examples 1-3, since the tension y at the end of winding exceeds 150N, it turns out that the depth of the winding dent part of a polarizing film is large. In Comparative Example 4, since the taper ratio is 0% and the tension y at the end of winding exceeds 150 N, it can be seen that the depth of the winding recess portion of the polarizing film is large. In Comparative Example 5, the taper rate is 0%, and the tension at the start of winding is 30 N. Therefore, it can be seen that the amount of winding deviation is large.

  The polarizing film of the present invention is used alone or in an image display device such as a liquid crystal display device (LCD) or an organic EL display device as an optical film obtained by laminating the polarizing film.

1: Inner peripheral edge part 2: Outermost peripheral edge part 3: Polarizing film roll 4: Polarizing film 5: Sample 6: Winding dent part 7: Center part D: Maximum depth

Claims (4)

A method for producing a polarizing film roll comprising a step of winding a polarizing film around a core,
The polarizing film has a thickness of 100 μm or less and a length of 500 m or more and 4000 m or less,
In the step, the polarizing film is applied while applying the tension y so that the tension y calculated by the following formula (1) is 30N or more and 150N or less from the time when the winding amount becomes 500 m or more to the end of winding. A method for producing a polarizing film roll, which is wound around a winding core.
Tension y = a {1- (bx / 400000)} (1)
a: Tension at the start of winding (a> 30N)
b: Taper ratio (%) = {(Tension at the start of winding--Tension at the time of winding up to 4000 m) / Tension at the start of winding} × 100
x: Winding amount (500 m ≦ x ≦ 4000 m)   2. The method for producing a polarizing film roll according to claim 1, wherein the polarizing film has a length of 1000 to 4000 m, and the tension y when the winding amount reaches the length is 35 N or more and 145 N or less.   The method for producing a polarizing film roll according to claim 1, wherein the polarizing film has a protective film on one side or both sides of a polarizer via an adhesive layer.   The method for producing a polarizing film roll according to claim 3, wherein the polarizer has a thickness of 20 μm or less.