KR102266085B1 - Manufacturing method for polarizing film roll - Google Patents

Abstract

(Project) 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-up dent in a polarizing film edge part.
(Solution) The manufacturing method of the polarizing film roll of this invention includes the process of winding up a polarizing film to a core, The said polarizing film is 100 micrometers or less in thickness and 500 m or more and 4000 m or less in length, In the said process, The polarizing film is wound around the core 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 when the amount becomes 500m or more to the end of winding.
Tension y=a{1-(bx/400000)} (1)
a: Tension at the start of winding (a>30N)
b: Taper rate (%) = {(Tension at the start of winding - Tension at the time of assuming winding of 4000 m)/Tension at the beginning of winding} x 100
x: winding amount (500m≤x≤4000m)

Description

The manufacturing method of a polarizing film roll {MANUFACTURING METHOD FOR POLARIZING FILM ROLL}

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

In various image display apparatuses, a polarizing film is used for image display. For example, in a liquid crystal display device (LCD), it is indispensable to arrange a polarizing film on both sides of a glass substrate which forms the liquid crystal panel surface from its image formation method. Further, in the organic EL display device, a circularly polarizing film in which a polarizing film and a quarter wave plate are laminated is disposed on the visible side of the organic light emitting layer in order to shield the specular reflection of external light at the metal electrode.

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

In recent years, thickness reduction of image display apparatuses, such as a liquid crystal display device, progresses, and thickness reduction is calculated|required also in a polarizing film with it.

A polarizing film is usually manufactured by the so-called roll-to-roll system in which the raw film is subjected to various processes while feeding the raw film from the raw roll, and the obtained elongated polarizing film is wound around a core to form a roll. .

As described above, the polarizing film is manufactured by a roll-to-roll method and stored as a polarizing film roll, but there was a problem in that the polarizing film unwound from the polarizing film roll tends to have defects such as stripes, dents, or curls.

For example, in Patent Document 1, a winding stripe defect (a dent defect of a stripe shape extending in the width direction of the polarizing plate that occurs when the polarizing plate wound on the step portion is pressed, that is, a height difference occurring between the winding start end of the polarizing plate and the outer peripheral surface of the winding core) A winding core having on its outer peripheral surface a first convex portion and a second convex portion extending in the circumferential direction for the purpose of suppression, and a polarizing plate wound around the core, wherein the polarizing plate is laminated on at least one surface of the polarizer The polarizing plate is provided with a protective film used as the polarizing plate, wherein one end region in the width direction of the protective film is located on the first convex portion and the other end region is located on the second convex portion. A polarizing plate roll wound on the is proposed.

Further, in Patent Document 2, for the purpose of preventing the occurrence of reverse curl or wavy curl, the step of adjusting the water content of the raw film used as the raw material of the transparent film, and the raw film after adjusting the water content are applied to one side of the polarizing film or The manufacturing method of a polarizing plate including the process of bonding together on both surfaces is proposed.

Japanese Patent Laid-Open No. 2016-85331 Japanese Patent Laid-Open No. 2014-191155

However, in the technique of Patent Document 1, a winding core having a special structure is required, and there is a problem that a general winding core cannot be used. Moreover, in the technique of patent document 2, it is necessary to adjust the water 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-up dent in a polarizing film edge part.

MEANS TO SOLVE THE PROBLEM As a result of earnest examination, the present inventors discovered that the said subject could be solved with the manufacturing method of the following polarizing film roll, and came to complete this invention.

That is, the present invention is a method for producing a polarizing film roll comprising the step of winding 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 above process, the polarizing film is wound around the core 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 when the amount of winding becomes 500m or more to the end of winding. It relates to the manufacturing method of the polarizing film roll to do.

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 assuming winding of 4000 m)/Tension at the beginning of winding} x 100

x: winding amount (500m≤x≤4000m)

It is preferable that the said polarizing film is 1000-4000 m in length, and it is 35N or more and 145N or less of the said tension|tensile_strength y when a winding amount becomes the said length.

The polarizing film preferably has a protective film on one side or both sides of the polarizer through an adhesive layer.

In addition, it is preferable that the thickness of the said polarizer is 20 micrometers or less.

(Effects of the Invention)

When the thickness of the polarizing film is 100 μm or less, since the rigidity of the polarizing film is low, when tension is applied to the polarizing film and wound around a core for storage, depression is likely to occur at the end of the rewound polarizing film. In particular, when a one-side drive roll apparatus is used, a difference is easy to generate|occur|produce in winding tension in the width direction of a polarizing film roll. And in the case of storage of a polarizing film roll, in order to eliminate the tension difference, a polarizing film roll is deform|transformed, As a result, it is thought that a depression arises in the edge part of a polarizing film. The polarizing film having such an edge depression has a problem that the roll transportability decreases or the yield decreases because it cannot be used as a product. However, as in the present invention, from when the amount of winding becomes 500 m or more to the end of winding, the polarizing film is wound around the core while adjusting so that the tension y is 30 N or more and 150 N or less, and the thickness is 100 μm or less even if it is a polarizing film at the end of the polarizing film. It is possible to effectively suppress the occurrence of winding depression. In particular, the manufacturing method of the polarizing film roll of this invention is effective, when a single side drive roll apparatus is used. According to the manufacturing method of the polarizing film roll of this invention, since the tension difference in the width direction of a polarizing film roll can be made small at the time of winding-up, generation|occurrence|production of winding-up dent in an edge part of a polarizing film can be suppressed effectively.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows the evaluation method of winding shift.
It is a schematic diagram which shows the manufacturing method of the sample in evaluation of winding-up depression.
It is a schematic diagram which shows the measuring method of the maximum depth in evaluation of winding-up depression.

The manufacturing method of the polarizing film roll of this invention includes the process of winding up a polarizing film to 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 above process, the polarizing film is wound around the core 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 when the amount of winding becomes 500m or more to the end of winding. It relates to the manufacturing method of the polarizing film roll to do.

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 assuming winding of 4000 m)/Tension at the beginning of winding} x 100

x: winding amount (500m≤x≤4000m)

The polarizing film may have a thickness of 100 µm or less and a length of 500 m or more and 4000 m or less, and others are not particularly limited. It is preferable that the thickness of the said polarizing film is 80 micrometers or less, More preferably, it is 70 micrometers or less. The said polarizing film is 10 micrometers or more normally from viewpoints, such as rigidity, mechanical strength, and handleability, Preferably it is 15 micrometers or more. The polarizing film preferably has a length of 700 m or more, more preferably 800 m or more, still more preferably 1000 m or more, still more preferably 1500 m or more, still more preferably 2000 m or more, still more preferably 2500 m or more. to be. Moreover, it is preferable that the said polarizing film is 50-200 cm in width, More preferably, it is 100-150 cm.

The polarizing film preferably has a protective film on one side or both sides of the polarizer through an adhesive layer. The said polarizing film may further contain 1 or more additional layers, such as the following functional layer, an easily adhesive layer, a surface protection film, an adhesive layer, an optical layer, and a separator.

As the polarizer, a known polarizer may be used without particular limitation, but it is preferable that the polarizer has a thickness of 20 μm or less from the viewpoint of reducing the thickness and suppressing the occurrence of cracks. The thickness of the polarizer is more preferably 18 µm or less, still more preferably 16 µm or less, still more preferably 15 µm or less. On the other hand, it is preferable that the thickness of a polarizer is 2 micrometers or more, More preferably, it is 3 micrometers or more.

As for the polarizer, the thing using polyvinyl alcohol-type resin is used. As the polarizer, for example, a dichroic substance such as iodine or a dichroic dye is adsorbed to a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, or an ethylene/vinyl acetate copolymer-based partially saponified film, and the uniaxial and polyene-based oriented films, such as those stretched, dehydrated products of polyvinyl alcohol, and dehydrochlorinated products of polyvinyl chloride. Among these, a polarizer made of a polyvinyl alcohol-based film and a dichroic substance such as iodine is suitable.

A polarizer in which a polyvinyl alcohol-based film is dyed with iodine and uniaxially stretched can be produced by, for example, immersing polyvinyl alcohol in an aqueous solution of iodine, dyeing the polyvinyl alcohol-based film, and stretching to 3 to 7 times the original length. If necessary, boric acid, zinc sulfate, zinc chloride, etc. may be contained, and it can also be immersed in aqueous solutions, such as potassium iodide. Moreover, you may immerse a polyvinyl alcohol-type film in water before dyeing, and may wash with water as needed. By washing the polyvinyl alcohol-based film with water, contamination and blocking agents on the surface of the polyvinyl alcohol-based film can be washed, and by swelling the polyvinyl alcohol-based film, there is also an effect of preventing unevenness such as staining of dyeing. Extending may be performed after dyeing|staining with iodine, may be extended|stretched while dyeing|staining, and may dye|stain with iodine after extending|stretching. It can be extended also in aqueous solutions, such as boric acid and potassium iodide, and a water bath.

It is preferable from the point of extending|stretching stability and humidification reliability that a polarizer contains boric acid. Moreover, it is preferable that it is 22 weight% or less with respect to the polarizer whole quantity from a viewpoint of suppressing generation|occurrence|production of a crack, and, as for content of boric acid contained in a polarizer, it is more preferable that it is 20 weight% or less. It is preferable that it is 10 weight% or more, and, as for boric acid content with respect to the whole amount of polarizer from a viewpoint of extending|stretching stability and humidification reliability, it is more preferable that it is 12 weight% or more.

As a thin polarizer, typically,

Japanese Patent No. 4751486 specification,

Japanese Patent No. 4751481 specification,

Japanese Patent No. 4815544 specification,

Japanese Patent No. 5048120 specification,

International Publication No. 2014/077599 pamphlet,

International Publication No. 2014/077636 pamphlet,

The thin-shaped polarizer described in etc. or the thin-shaped polarizer obtained from the manufacturing method as described in these is mentioned.

The thin polarizer can be stretched at a high magnification among manufacturing methods including a process of stretching and a process of dyeing in the state of a laminate as the thin polarizer, and in terms of improving polarization performance, Japanese Patent No. 4751486, Japanese Patent No. 4751481, It is preferably obtained by a manufacturing method including a step of stretching in an aqueous boric acid solution as described in Japanese Patent No. 4815544, and in particular, before stretching in an aqueous boric acid solution described in Japanese Patent No. 4751481 and Japanese Patent No. 4815544. It is preferable to obtain by the manufacturing method including the process of auxiliary|assistant aerial stretching. These thin polarizers can be obtained by a manufacturing method comprising a step of stretching a polyvinyl alcohol-based resin (hereinafter also referred to as a PVA-based resin) layer and a resin substrate for stretching in the state of a laminate, and a step of dyeing. If it is this manufacturing method, even if the PVA-type resin layer is thin, it becomes possible to extend|stretch without problems, such as fracture|rupture by extending|stretching, by being supported by the resin base material for extending|stretching.

The material of the protective film is preferably excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, and the like. 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, polystyrene or acrylonitrile styrene copolymer Styrenic polymers, such as (AS resin), polycarbonate-type polymer, etc. are mentioned. In addition, polyethylene, polypropylene, polyolefin having a cyclo- or norbornene structure, polyolefin-based polymer such as ethylene/propylene copolymer, vinyl chloride-based polymer, amide-based polymer such as nylon or aromatic polyamide, imide-based polymer, alcohol Phone-based polymer, polyethersulfone-based polymer, polyetheretherketone-based polymer, polyphenylenesulfide-based polymer, vinyl alcohol-based polymer, vinylidene chloride-based polymer, vinyl butyral-based polymer, arylate-based polymer, polyoxymethylene-based polymer, An epoxy-based polymer or a blend of the above-mentioned polymers can also be mentioned as examples of the polymer forming the above-mentioned protective film.

One or more types of arbitrary appropriate additives may be contained in a protective film. As an additive, a ultraviolet absorber, antioxidant, a lubricant, a plasticizer, a mold release agent, a coloring inhibitor, a flame retardant, a nucleating agent, antistatic agent, a pigment, a coloring agent etc. are mentioned, for example.

Content of the said polymer in a protective film becomes like this. Preferably it is 50 to 100 weight%, More preferably, it is 50 to 99 weight%, More preferably, it is 60 to 98 weight%, More preferably, it is 70 to 97 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 said protective film, retardation film, a brightness improving film, a diffusion film, etc. can also be used. Examples of the retardation film include those having a retardation of 40 nm or more in front retardation and/or 80 nm or more in thickness direction retardation. The front retardation is usually controlled in the range of 40 to 200 nm, and the thickness direction retardation is usually controlled in the range of 80 to 300 nm. When using retardation film as a protective film, since the said retardation film also functions as a protective film of a polarizer, thickness reduction can be aimed at.

As retardation film, the birefringent film formed by carrying out the uniaxial or biaxial stretching process of a thermoplastic resin film is mentioned. The temperature of the said stretching, a draw ratio, etc. are suitably set according to retardation value, the material of a film, and thickness.

Although the thickness of a protective film can be determined suitably, it is about 1-50 micrometers from points, such as workability|workability, such as intensity|strength and handleability, and thin layer property. The thickness of a protective film becomes like this. Preferably it is 5-50 micrometers, More preferably, it is 10-50 micrometers, More preferably, it is 10-40 micrometers.

A functional layer such as a hard coat layer, an anti-reflection layer, an anti-sticking layer, a diffusion layer or an anti-glare layer may be formed on the surface of the protective film on which the polarizer is not adhered. In addition, the functional layers such as the hard coat layer, the antireflection layer, the antistick layer, the diffusion layer and the antiglare layer can be formed on the protective film itself, and can also be formed separately from the protective film.

The adhesive layer is formed by 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, and various types of adhesives such as water-based, solvent-based, hot-melt-based and active energy ray-curable adhesives are used, but water-based adhesives or active energy ray-curable adhesives are 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-based adhesive, and a water-based polyester. A water-based adhesive is used as an adhesive agent which consists of aqueous solution normally, and contains 0.5 to 60weight% of solid content normally.

The active energy ray-curable adhesive is an adhesive that cures by active energy rays such as electron beams and ultraviolet rays (radical curing type, cation curing type), for example, it can be used in the form of electron beam curing type and ultraviolet curing type. As an active energy ray hardening-type adhesive agent, an optical radical hardening-type adhesive agent can be used, for example. When an active energy ray-curable adhesive of a photoradical curing type is used as an ultraviolet curing type, the adhesive contains a radically polymerizable compound and a photopolymerization initiator.

The coating method of the adhesive agent is appropriately selected according to the viscosity of the adhesive agent or the target thickness. As an example of a coating system, a reverse coater, a gravure coater (direct, reverse or offset), a bar reverse coater, a roll coater, a die coater, a bar coater, a rod coater etc. are mentioned, for example. In addition, methods, such as a dipping method, can be used suitably for coating.

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.

Moreover, in lamination|stacking of a polarizer and a protective film, an easily adhesive layer can be formed between a protective film and an adhesive bond layer. The easily adhesive layer can be formed of various resins having, for example, polyester skeleton, polyether skeleton, polycarbonate skeleton, polyurethane skeleton, silicone system, polyamide skeleton, polyimide skeleton, polyvinyl alcohol skeleton and the like. These polymer resins can be used individually by 1 type or in combination of 2 or more type. In addition, you may add another additive to formation of an easily bonding layer. Specifically, you may further use stabilizers, such as a tackifier, a ultraviolet absorber, antioxidant, and a heat-resistant stabilizer.

An easily adhesive layer is normally formed previously in a protective film, and the easily adhesive layer side of the said protective film and a polarizer are laminated|stacked with an adhesive bond layer. Formation of an easily bonding layer is performed by coating and drying the forming material of an easily bonding layer by a well-known technique on a protective film. The forming material of an easily bonding layer is adjusted normally as the solution diluted to the appropriate density|concentration in consideration of the thickness after drying, smoothness of coating, etc. 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. In addition, although multiple layers of an easily bonding layer can be formed, it is preferable to make the total thickness of an easily bonding layer become the said range also in this case.

The said polarizing film may have an adhesive layer.

In the case of the polarizing film which provided the protective film on both surfaces of the polarizer, an adhesive layer is formed in the surface of one protective film directly or through another layer. Moreover, you may form a surface protection film on the surface of the other protective film directly or through another layer.

In the case of a polarizing film in which the protective film is formed on only one side of the polarizer, the pressure-sensitive adhesive layer is formed on the polarizer side directly or through another layer. Moreover, you may form a surface protection film directly on the protective film side or through another layer.

The said other layer in particular is not restrict|limited, A well-known functional layer, an optical layer, etc. which are formed in a polarizing film are mentioned. Examples of the optical layer include a reflecting plate, a transflective plate, a retardation plate (including a 1/2 or 1/4 wave plate), a visual compensation film, and a luminance enhancing film. One layer of said other layer may be formed, and two or more layers may be formed.

The said adhesive layer is formed in the single side|surface of a polarizing film in order to bond a polarizing film to cell substrates, 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, still more preferably 2 to 30 µm.

A suitable adhesive can be used for formation of the said adhesive layer, and there is no restriction|limiting in particular with respect to the kind. Examples of the pressure-sensitive adhesive include a rubber pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive, a silicone pressure-sensitive adhesive, a urethane pressure-sensitive adhesive, a vinyl alkyl ether pressure-sensitive adhesive, a polyvinyl alcohol-based pressure-sensitive adhesive, a polyvinylpyrrolidone pressure-sensitive adhesive, a polyacrylamide pressure-sensitive adhesive, and a cellulose pressure-sensitive adhesive.

Among these pressure-sensitive adhesives, those which are excellent in optical transparency, exhibit moderate wettability, cohesiveness, and adhesive properties, and are excellent in weather resistance, heat resistance, and the like are preferably used. As what shows these characteristics, an acrylic adhesive is used preferably.

As a method of forming the pressure-sensitive adhesive layer, for example, a method of transferring the pressure-sensitive adhesive to a polarizing film after applying the pressure-sensitive adhesive to a peeling-treated separator or the like, drying and removing the polymerization solvent, etc. to form the pressure-sensitive adhesive layer, or applying the pressure-sensitive adhesive and polymerization The method etc. which dry and remove a solvent etc. and form an adhesive layer in a polarizing film are mentioned. In addition, in application|coating of an adhesive, you may newly add 1 or more types of solvents other than a polymerization solvent suitably.

As the separator subjected to the release treatment, a silicone release liner is preferably used. As a method of drying the pressure-sensitive adhesive in the step of applying and drying the pressure-sensitive adhesive on the liner to form the pressure-sensitive adhesive layer, an appropriate method may be employed depending on the purpose. Preferably, a method of overheating 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 making heating temperature into the said range, the adhesive which has the outstanding adhesive characteristic can be obtained.

As the drying time, an appropriate time may be employed. The drying time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 10 minutes, particularly preferably 10 seconds to 5 minutes.

Various methods are used as a formation method of an adhesive layer. Specifically, for example, roll coating, kiss roll coating, gravure coating, reverse coating, roll brush coating, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, die coater, etc. Methods, such as an extrusion coating method, are mentioned.

When the pressure-sensitive adhesive layer is exposed, the pressure-sensitive adhesive layer may be protected with a peeling-treated sheet (separator) until it is put to practical use.

As a constituent material of the separator, for example, plastic films such as polyethylene, polypropylene, polyethylene terephthalate, polyester film, porous materials such as paper, cloth, and nonwoven fabrics, nets, foam sheets, metal foils, laminates thereof, etc. Although a suitable thin leaf body etc. are mentioned, A plastic film is used suitably from the point which is excellent in surface smoothness.

The plastic film is not particularly limited as long as it is a film capable of protecting the pressure-sensitive adhesive layer, and 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 film. A copolymer film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, an ethylene-vinyl acetate copolymer film, etc. are mentioned.

If necessary, the separator may be subjected to release and antifouling treatment with a silicone-based, fluorine-based, long-chain alkyl- or fatty acid amide-based release agent, silica powder, or the like, or antistatic treatment such as coating, kneading or vapor deposition. In particular, the peelability from the pressure-sensitive adhesive layer can be further improved by appropriately performing peeling treatment such as silicone treatment, long-chain alkyl treatment, or fluorine treatment on the surface of the separator.

The surface protection film usually has a base film and a pressure-sensitive adhesive layer, and protects the polarizing film through the pressure-sensitive adhesive layer.

As a base film of the said surface protection film, the film material which has isotropy or isotropic is selected from viewpoints, such as inspection property and manageability. Examples of the film material include polyester-based resins such as polyethylene terephthalate film, cellulose-based resins, acetate-based resins, polyethersulfone-based resins, polycarbonate-based resins, polyamide-based resins, polyimide-based resins, and polyolefin-based resins. and transparent polymers such as resins and acrylic resins. Among these, polyester-type resin is preferable. A base film may be used as a laminated body of 1 type(s) or 2 or more types of film materials, and also the stretched material of the said film may be used. The thickness of a base film becomes like this. Preferably it is 10-150 micrometers, More preferably, it is 20-150 micrometers.

As the pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer of the surface protection film, a (meth)acrylic-based polymer, silicone-based polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer as the base polymer may be appropriately selected and used. can An acrylic pressure-sensitive adhesive having an acrylic polymer as a base polymer is preferable from the viewpoints of transparency, weather resistance, heat resistance, and the like. The thickness (dry film thickness) of an adhesive layer becomes like this. Preferably it is 1-40 micrometers, More preferably, it is 1-30 micrometers.

In addition, in the surface protection film, the peeling process layer can be formed with low adhesive material, such as silicone treatment, a long-chain alkyl treatment, a fluorine treatment, on the opposite surface of the surface on which the adhesive layer in the base film was formed.

A polarizing film roll is manufactured by winding up the said polarizing film of long shape to a core. As a winding-up apparatus, although a single side drive roll apparatus may be used and both sides drive roll apparatus may be used, it is preferable to use a single side drive roll apparatus.

Although the outer diameter in particular of the said winding core is not restrict|limited, Preferably it is 100-500 mm, More preferably, it is 150-400 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 polarizing film is wound around the core 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 amount of winding becomes 500m or more to the end of winding.

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 assuming winding of 4000 m)/Tension at the beginning of winding} x 100

x: winding amount (500m≤x≤4000m)

When the tension y is less than 30N, a winding misalignment occurs, resulting in poor conveyance at the time of the next repetition. On the other hand, when the tension y exceeds 150N, winding depression occurs at the end of the polarizing film.

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

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

In addition, when the length of the polarizing film is 2000 to 3000 m, the tension y when the amount of winding becomes the above length (that is, when all the polarizing films are wound) is preferably 40N or more, more preferably 50N or more It is more preferably 60N or more, and 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, more preferably 300N or less, more preferably 280N or less, still more preferably 270N or less, still more preferably 200N or less, further Preferably it is 150N or less.

A taper rate is a value computed from the tension|tensile_strength at the time of the tension|tensile_strength at the time of winding-up start, and the tension|tensile_strength at the time of 4000m winding-up assumption, as shown by the said Formula. Even if it is a case where the length of the polarizing film to actually wind up is less than 4000 m, the tension|tensile_strength at the time of supposing that it winds up 4000 m is set, and a taper rate is determined.

Although the said taper rate is not specifically limited, Preferably it is 1 % or more, More preferably, it is 5 % or more, More preferably, it is 10 % or more, More preferably, it is 20 % or more, More preferably, it is 99 %. or less, more preferably 90% or less, still more preferably 85% or less, still more preferably 80% or less, still more preferably 75% or less, still more preferably 60% or less, still more preferably Preferably it is 50% or less, More preferably, it is 40% or less.

It is preferable that the maximum depth of the winding-up dent in an edge part of a polarizing film is 2.5 mm or less, More preferably, it is less than 2.0 mm.

(Example)

Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples. In addition, all parts and % in each example are based on weight.

(Manufacture of Polarizer)

A polyvinyl alcohol film (PVA-based resin film) having an average degree of polymerization of 2400, a degree of saponification of 99.9 mol%, and a thickness of 30 μm is immersed in hot water at 30° C. and uniaxially so that the length of the PVA-based resin film becomes 2.0 times the original length while swelling. stretching was performed. Then, it was immersed in an iodine solution at 30°C of 0.3% by weight (weight ratio: iodine/potassium iodide = 0.5/8), and dyed while uniaxially stretching so that the length of the PVA-based resin film was 3.0 times the original length. Then, it extended|stretched so that the length of a PVA-type resin film might become 6 times of the original length in the aqueous solution of 4 weight% of hexaboric acid and 5 weight% of potassium iodide. Furthermore, after performing the iodine ion impregnation process with the aqueous solution (iodine impregnation bath) of 3 weight% of potassium iodide, it dried in 60 degreeC oven for 4 minutes, and obtained the 12-micrometer-thick polarizer.

(protective film)

<Protective film 1>

25 µm TAC film with HC: TJ25UL (manufactured by FUJIFILM CORPORATION, raw material: triacetyl cellulose polymer) coated with an acrylic resin hard coat

40㎛ TAC film: KC4UYW (manufactured by Konica Minolta, Inc., raw material: triacetyl cellulose polymer)

HC-attached 37㎛λ/4TAC: KC2UGR-HC (manufactured by Konica Minolta, Inc., raw material: triacetyl cellulose polymer) coated with an acrylic resin hard coat

<Protection film 2>

25㎛ TAC film: KC2UA (manufactured by Konica Minolta, Inc., raw material: triacetyl cellulose polymer)

13 µm COP film: ZF-014 (manufactured by Zeon Corporation, raw material: cycloolefin polymer)

Preparation of 30㎛ acrylic film

8,000 g of methyl methacrylate (MMA), 2,000 g of 2-(hydroxymethyl) methyl acrylate (MHMA), 10,000 g 4-methyl-2-pentanone (methyl isobutyl ketone, MIBK) and 5 g of n-dodecyl mercaptan were added, and the temperature was raised to 105° C. while passing nitrogen thereto and refluxed to 5.0 as a polymerization initiator g of t-butylperoxyisopropyl carbonate (Kayacarbon BIC-7, manufactured by Kayaku Akzo Corporation) was added, and a solution consisting of 10.0 g of t-butylperoxyisopropyl carbonate and 230 g of MIBK was added for 4 hours. Solution polymerization was performed at about 105 to 120°C under reflux while being added dropwise, and further aging was performed over 4 hours.

To the obtained polymer solution, 30 g of a stearyl phosphate/distearyl phosphate mixture (Phoslex A-18, manufactured by SAKAI CHEMICAL INDUSTRY CO., LTD.) was added, and a cyclization condensation reaction was performed at about 90 to 120° C. under reflux for 5 hours. . Next, the obtained polymer solution was subjected to a barrel temperature of 260° C., a rotation speed of 100 rpm, a pressure reduction degree of 13.3 to 400 hPa (10 to 300 mmHg), a vent type screw twin-screw extruder with one rear vent and four four vents (φ=29.75 mm, L /D = 30) in terms of the amount of resin, introduced at a processing rate of 2.0 kg/h, further subjected to cyclization condensation reaction and devolatilization in this extruder, and extruded to obtain transparent pellets of a lactone ring-containing polymer.

As a result of measuring the dynamic TG about the obtained lactone ring containing polymer, the mass decrease of 0.17 mass % was detected. Moreover, this lactone ring containing polymer had a weight average molecular weight of 133,000, a melt flow rate of 6.5 g/10min, and a glass transition temperature of 131 degreeC.

Transparent pellets were obtained by kneading and extruding the obtained pellets and acrylonitrile-styrene (AS) resin (TOYO AS AS20, manufactured by TOYO STYRENE CO., LTD.) at a mass ratio of 90/10 using a single screw extruder (screw 30 mmφ). The glass transition temperature of the obtained pellets was 127 degreeC.

This pellet was melt-extruded from a coat hanger type T-die with a width of 400 mm using a 50 mm φ single screw extruder to produce a film with a thickness of 120 μm. The thickness was obtained by stretching this to 2.0 times under a temperature condition of 150° C. using a biaxial stretching device. A 30-micrometer acrylic film was obtained. As a result of measuring the optical properties of the stretched film, 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 water-based adhesive)

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

Example 1

Protective film 1 (25 µm TAC film with HC) and protective film 2 (25 µm TAC film) were coated with the water-based adhesive on each side so that the thickness of the adhesive layer after drying was 80 nm, and protective films 1 and 2 with adhesive were applied. got it Next, the protective film 1 with adhesive on one side of the polarizer and the protective film 2 with adhesive on the other side of the polarizer are bonded by a roll machine under a temperature condition of 23° C., and then dried at 55° C. for 6 minutes to make a polarizing film (69 micrometers in thickness) was produced. And the polarizing film produced using the single side drive roll apparatus was wound up to the core, and the polarizing film roll was produced. In addition, the conditions at the time of winding are shown in Table 1.

Examples 2 to 11, Comparative Examples 1 to 5

The polarizing film roll was produced by the method similar to Example 1 except having changed the kind of protective films 1 and 2, the thickness and length of a polarizing film, and the conditions at the time of winding up as Table 1 was described.

The following evaluation was performed about the polarizing film roll produced by the Example and the comparative example. A result is 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 the environment of 25 degreeC 55%. Then, as shown in FIG. 1 on the basis of the inner peripheral edge part of a polarizing film roll, the height difference between the inner peripheral edge part 1 and the outermost peripheral edge part 2 was measured with a gold scale, and the difference was made into the winding shift amount. The case where the amount of deviation was 200 mm or less was evaluated as (circle), and the case where the amount of deviation was greater than 200 mm was evaluated as ×.

<Evaluation of winding depression>

The polarizing film rolls produced in Examples and Comparative Examples were stored for 7 days under an environment of 25°C and 55% and on a bearing trolley. Then, as shown in FIG. 2, the polarizing film was rewound from the polarizing film roll 3, and the polarizing film 4 (length 3m) of a 3-6m part was cut out from a rewind start. Then, two samples 5 having a width of 200 mm were cut out from both ends of the polarizing film 4 . As shown in FIG. 3 , all the winding depressions 6 are cut out from the two samples 5 , and the winding depressions 6 are cut in half in the width direction of the polarizing film so as to pass through the central portion 7 . did. And the winding recessed part 6 cut in half was placed on a flat plate, the maximum depth D from a plane was measured, and the following reference|standard evaluated. In addition, when there are two or more winding depressions 6, the average value of the maximum depth D was employ|adopted.

◎: less than 2.0mm

○: 2.0~2.5mm

×: more than 2.5 mm

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

(industrial applicability)

The polarizing film of this invention is used for image display apparatuses, such as a liquid crystal display device (LCD) and an organic electroluminescent display, as this alone or as an optical film which laminated|stacked this.

1 Inner peripheral end 2 Outermost peripheral end
3 polarizing film roll 4 polarizing film
5 Sample 6 Winding depression
7 Core D Max Depth

Claims (4)

A method for producing a polarizing film roll comprising the step of winding a polarizing film to a core using a one-side drive roll device, the method comprising:
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 above process, the polarizing film is wound around the core while applying the tension y so that the tension y calculated by the following formula (1) becomes 30N or more and 150N or less from the time the amount of winding becomes 500m or more until the end of winding. The manufacturing method of the polarizing film roll to do.
Tension y=a{1-(bx/400000)} (1)
a: Tension at the start of winding (a>30N)
b: Taper rate (%) = {(Tension at the start of winding - Tension at the time of assuming winding of 4000 m)/Tension at the beginning of winding} x 100
x: winding amount (500m≤x≤4000m) The method of claim 1,
The said polarizing film is 1000-4000 m in length, The manufacturing method of the polarizing film roll whose said tension|tensile_strength y when a winding amount became the said length is 35N or more and 145N or less. 3. The method according to claim 1 or 2,
The polarizing film is a method of manufacturing a polarizing film roll having a protective film through an adhesive layer on one side or both sides of the polarizer. 4. The method of claim 3,
The thickness of the polarizer is 20 μm or less of the manufacturing method of the polarizing film roll.

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