TW201625995A - Polarizing plate roll - Google Patents

Abstract

The present invention provides a polarizing plate roll including a roll core having a first projection part and a second projection part extended in a circumferential direction, and a polarizing plate wired on the roll core. The polarizing plate has a polarizer and a protecting film laminated on at least one surface of the polarizer, and is wired on the roll core so as to let a end in the width direction of the polarizer located on the first projection part and the other end is located on the second projection part.

Description

Polarized plate roll

The present invention relates to a polarizing plate roll in which a long polarizing plate is wound around a winding core.

The polarizing plate is used in a display device such as a liquid crystal display device, and in particular, it has been widely used in various mobile devices such as mobile phones in recent years. The polarizing plate is usually formed by laminating a protective film on one surface or both surfaces of a polarizing plate. However, with the development of mobile devices, the thickness of the polarizing plate and the protective film constituting the polarizing plate has been increasing.

In the production of a polarizing plate, a raw material film which is rolled up and rolled out from a roll of a raw material film wound on a winding core (winding axis) is generally used. A polarizing plate which is processed into a long shape (belt shape) is applied, and the obtained polarizing plate is wound up on a winding core to be wound, that is, in a roll to roll manner. Therefore, the polarizing plate is usually obtained by winding a long polarizing plate on a polarizing plate roll of a winding core (for example, JP-A-2013-029754 (Patent Document 1)).

[Advanced technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2013-029754

The polarizing plate as described above is generally manufactured in the form of a polarizing plate roll. For example, the film length of the polarizing plate is 2000 m, and the diameter of the core is 150 mm. At the time, the number of windings of the polarizing plate will reach about 4,000 times.

The polarizing plate manufactured in the form of a polarizing plate roll is mostly supplied until it is attached to another film or a subsequent step of forming a coating layer, or during a continuous period of time between delivery to a supply target, the polarizing plate is mostly maintained. In the state of the volume.

However, in some continuous periods, the polarizing plate which is wound up after being held in the rolled state is liable to have a problem of deformation called "relaxation" at both end portions in the width direction. This problem is more remarkable when the polarizer or the protective film constituting the polarizing plate is thinner. "Slack" refers to a wave-like deformation (deformation) generated at both end portions in the width direction of the polarizing plate. When the slack is greatly increased from the end portion in the width direction to the inner side (center portion side) of the polarizing plate, when the film is bonded to another film or a coating layer is formed in the subsequent step, the polarizing plate is likely to wrinkle or suck bubbles. In the case where the quality of the product is lowered, there are cases in which the implementation of the subsequent steps becomes difficult.

Here, an object of the present invention is to provide a polarizing plate roll in which a polarizing plate is wound around a core of a polarizing plate, and when the polarizing plate is taken out from the roll, it can be confirmed that the width direction of the polarizing plate is two. The "relaxation" produced at the ends can be suppressed.

When the relaxation was investigated, it was found that the film thickness distribution of the polarizer contained in the polarizing plate was the main cause of slack. In other words, since the polarizer is usually produced by a step of extending a strip-shaped resin film or the like as a raw material in the longitudinal direction (film length direction) or the lateral direction (film width direction), the center portion is wider than the width direction. The thickness of both ends will become larger. The polarizing plate having the polarizer having the film thickness distribution also has a similar film thickness distribution, and when the polarizing plate is wound around the core, the both ends of the polarizing plate are repeatedly wound in the width direction. In the state in which the overall thickness is increased, the polarizing plate is wound again, so that the circumferential stress in the both end portions of the wound polarizing plate becomes large, and the both end portions become extended. Winding. This is the main reason for relaxation.

Based on the above findings, the present invention provides a polarizing plate roll as shown below as a means for solving the above problems.

[1] A polarizing plate roll comprising a winding core having a first convex portion and a second convex portion extending in a circumferential direction on an outer peripheral surface, and a polarizing plate wound around the winding core, The polarizing plate includes a polarizing plate and a protective film laminated on at least one surface thereof. The polarizing plate is wound around the winding core such that one end portion of the polarizer in the width direction is located on the first convex portion and the other end portion is located on the second convex portion.

[2] The polarizing plate roll according to [1], wherein the width of the end portion of the polarizer located on the first convex portion and the second convex portion is 5 mm or more.

[3] The polarizing plate roll according to [1], wherein the heights of the first convex portion and the second convex portion are each 50 μm or more.

[4] The polarizing plate roll according to any one of [1], wherein the first convex portion and the second convex portion are formed of a resin film attached to the outer circumferential surface.

[5] The polarizing plate according to any one of [1], wherein the thickness of both ends of the polarizing plate in the width direction is 1.01 to 1.2 times the thickness of the central portion in the width direction.

According to the present invention, it is possible to provide a polarizing plate roll capable of suppressing slack in both end portions in the width direction of the polarizing plate. By the suppression of relaxation, the quality of the polarizing plate itself and the article obtained in the subsequent steps as described above and the yield of the article can be improved, and the ease of implementation of the subsequent steps can be improved.

10‧‧‧With convex core

10a‧‧‧1st convex

10b‧‧‧2nd convex

20‧‧‧Polar plate

21‧‧‧ polarizer

22‧‧‧1st protective film

23‧‧‧2nd protective film

30‧‧‧Fixed components

H‧‧‧ Height of the convex part

T ₁ , T ₂ , T ₃ , T ₄ ‧ ‧ end of protective film

W ₁ , W ₂ , W ₃ ‧‧‧ End zone width

Fig. 1 is a schematic view showing an example of a convex core of a polarizing plate used in the present invention.

Fig. 2 is a cross-sectional view showing a portion of a first convex portion having a convex portion winding core shown in Fig. 1.

Fig. 3 is a cross-sectional view schematically showing the positional relationship between the convex portion of the convex portion winding core and the wound polarizing plate in the width direction.

Fig. 4 is a cross-sectional view showing another example of the convex core of the convex portion.

Fig. 5 (a) and (b) are schematic views showing a state in which the end portion of the polarizing plate is wound and fixed to the convex core by a fixing member.

Figure 6 is a schematic view for explaining the problem of curled stripe defects.

In the polarizing plate roll of the present invention, as shown in an example of the first drawing and the second drawing, the winding core is provided with a convex portion core having a first convex portion 10a and a second convex portion 10b extending in the circumferential direction on the outer circumferential surface. 10. A polarizing plate in the form of a roll obtained by winding a long polarizing plate. In order to suppress the occurrence of the above-mentioned "slack", the polarizing plate has a mode in which one end portion in the width direction of the polarizer is located on the first convex portion 10a, and the other end portion is located on the second convex portion 10b. It is wound around the convex core 10 . The positional relationship in the width direction between the convex portions 10a and 10b of the convex portion winding core 10 and the wound polarizing plate will be described in detail in the following item (3).

The polarizing plate is wound in the above-described positional relationship to suppress slack, and the polarizing plate is placed in the wide direction, and both end portions of the polarizing plate having the largest thickness are placed on the convex portion of the convex core 10, so that The aforementioned circumferential stress of the both end portions of the wound polarizing plate is alleviated. Further, as in Comparative Example 1 described below, the degree of relaxation (length) is extremely large, and the number of windings from the start of curling is about 70 to 75 times (although it is affected by the diameter of the core, However, when the distance from the curl start end (curl length) is about 30 to 40 m), when the number of windings becomes larger than this, although it is not obvious, the degree of slack becomes small. The degree (length) of the relaxation referred to herein means the length of the wavy deformation extending from the end portion in the width direction of the polarizing plate toward the inner side (the central portion side) of the polarizing plate.

(1) with a convex core

The convex portion winding core 10 may have the same shape as a conventionally known winding core in addition to the first convex portion 10a and the second convex portion 10b, and the body portion of the winding core other than the convex portion may be, for example, a cylindrical portion. Shaped or cylindrical. The material is not particularly limited, and metals, alloys, and resins (thermoplastic resins, etc.) can be used. The length in the width direction (rotational axis direction) of the convex core 10 is the same as or longer than the width of the wound polarizing plate. The diameter of the convex core 10 when it is cylindrical or cylindrical may be the general diameter of the core, for example, 100 to 200 mm. about.

The installation position of the first convex portion 10a and the second convex portion 10b provided on the outer circumferential surface of the convex portion winding core 10 depends on the width of the wound polarizing plate. Specifically, the first convex portion 10a and the second convex portion 10b are located at positions different from each other on the outer peripheral surface, and the one end portion in the width direction of the polarizer constituting the polarizing plate is located at the first convex portion. The other end portion of the 10a is located on the second convex portion 10b. As shown in Fig. 1, the first convex portion 10a and the second convex portion 10b are usually provided at an end portion (including an end portion) in the width direction (rotational axis direction) of the convex portion winding core 10 or in the vicinity of the end portion.

The first convex portion 10a and the second convex portion 10b are provided on the outer circumferential surface of the convex portion winding core 10, and are provided to extend in the circumferential direction of the convex portion winding core 10, preferably with respect to the convex portion. The circumferential direction of the core 10 extends in parallel (vertical direction with respect to the direction of the rotation axis of the convex portion winding core 10). As shown in Fig. 2, the first convex portion 10a and the second convex portion 10b are preferably belt-shaped, and preferably have a ring around the entire circumference or almost the entire circumference of the outer peripheral surface of the convex portion winding core 10. Shape setting.

The first convex portion 10a and the second convex portion 10b may be attached to the convex portion The body portion of the core 10 is integrally formed, and may be formed using other members than the body portion. In the method of forming the convex portion by using another member, the first convex portion 10a and the second convex portion are attached to the outer circumferential surface of the cylindrical or cylindrical core as the main portion of the convex portion winding core 10 A method of a resin film of 10b (for example, a film tape from a thermoplastic resin). In order to attach to the outer peripheral surface of the core, the resin film may be one on the one side with an adhesive layer. According to the method of attaching the resin film using an adhesive, since the reattachment becomes possible, the position adjustment or the positional change of the convex portion becomes easy. The method of forming the convex portion by the attachment of the resin film is advantageous from the manufacturing cost surface of the convex portion winding core 10 and the surface of the manufacturing ease, and the convex portion having the sufficient strength can also be obtained. Core 10. The resin film may be attached to the outer peripheral surface of the core by using an adhesive.

(2) Polarizer

The polarizing plate wound around the convex portion winding core 10 includes a polarizing plate and a protective film laminated on at least one surface thereof. The film can also be protected on the two-layer layer of the polarizer. The protective film is usually adhered to the polarizer through the adhesive layer. As the subsequent agent, an active energy ray-curable adhesive such as an ultraviolet curable adhesive or a water-based adhesive such as a vinyl alcohol resin aqueous solution can be used. The overall thickness of the polarizing plate is generally about 30 to 300 μm.

The polarizer can be suitably used in the case where a dichroic dye is adsorbed to a resin film which is uniaxially stretched. The resin film is a polyvinyl alcohol resin film. As the dichroic dye, iodine or a dichroic dye can be used. As the polyvinyl alcohol-based resin constituting the polarizer, those obtained by saponifying a polyvinyl acetate-based resin can be used. Polyacetate B The ethylenic resin is exemplified by a copolymer of vinyl acetate and another monomer copolymerizable therewith, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated decanoic acids, and (meth) acrylamides having ammonium groups. In the present specification, "(meth)acrylic" means at least one selected from the group consisting of acrylic acid and methacrylic acid. "(Methyl) propylene oxime" is also the same.

The degree of saponification of the polyvinyl alcohol-based resin is usually from about 85 to 100 mol%, preferably from 98 mol% or more. The polyvinyl alcohol-based resin can be modified, and for example, aldehyde-modified polyvinyl-based formaldehyde, polyvinyl acetal, or the like can be used. The degree of polymerization of the polyvinyl alcohol-based resin is usually from about 1,000 to 10,000, preferably from about 1,500 to 5,000.

The polarizer can be produced by a method comprising the steps of: subjecting a raw material film made of the above polyvinyl alcohol-based resin to a uniaxial stretching (typically, a longitudinal uniaxial extension to the longitudinal direction of the film); a step of dyeing a dichroic dye by a dichroic dye to adsorb a dichroic dye; a step of treating a polyvinyl alcohol-based resin film having a dichroic dye adsorbed thereon with a boric acid aqueous solution; and washing with a boric acid aqueous solution step. A swelling step of applying an immersion treatment in water may also be provided before the dyeing treatment.

The uniaxial stretching of the polyvinyl alcohol-based resin film can be carried out simultaneously with dyeing or after dyeing before dyeing of the dichroic dye. When the uniaxial extension is carried out after dyeing, the uniaxial stretching can be carried out before the boric acid treatment or in the boric acid treatment. In addition, uniaxial stretching can be performed at a plurality of stages.

The thickness of the polarizer (the average thickness of the full width) is, for example, 40 μ In the polarizing plate for a mobile device, it is preferably not more than 10 μm, and more preferably 10 μm or less from the viewpoint of reducing the thickness of the polarizing plate. The thickness of the polarizer is usually 2 μm or more. According to the present invention, even if a polarizer of such a film is used, slack can be effectively suppressed.

In the above-described manner, the polarizer is usually produced by the step of extending the polyvinyl alcohol resin film in the longitudinal direction (the film length direction), so that the film thickness distribution at the both end portions is large with respect to the central portion in the width direction. . The polarizing plates accompanying this generally have the same tendency to have a film thickness distribution. The thickness of both end portions in the width direction of the polarizing plate may be about 1.01 to 1.2 times the thickness of the central portion in the width direction, may be about 1.04 to 1.2 times, and may be as large as about 1.1 to 1.2 times. According to the present invention, even in the case of such a large difference in film thickness, slack can be effectively suppressed.

The protective film to be bonded to the polarizer may be a film made of a translucent (preferably optically transparent) thermoplastic resin, for example, a chain polyolefin resin (polypropylene resin, etc.). a polyolefin-based resin such as a cyclic polyolefin resin (such as a decene-based resin); a cellulose acetate-like resin such as cellulose triacetate or cellulose diacetate; a polyester resin; and a polycarbonate resin; (Meth)acrylic resin; polystyrene resin; or mixtures, copolymers, and the like. When the protective film is bonded to both surfaces of the polarizer, the protective film may be a resin of the same kind as the resin, or may be a protective film made of a different type of resin.

The protective film may be a protective film having a phase difference film and a brightness enhancement film-like optical function. For example, a film formed of the above thermoplastic resin may be formed by stretching (uniaxial stretching or biaxial stretching, etc.) or forming a liquid crystal layer on the film. And so on, it becomes a retardation film which gives an arbitrary phase difference.

The chain-like polyolefin resin may be a homopolymer of a chain olefin such as a polyethylene resin or a polypropylene resin, or a copolymer of two or more kinds of chain olefins.

The cyclic polyolefin resin is a general term for a resin obtained by polymerizing a cyclic olefin as a polymerization unit. Specific examples of the cyclic polyolefin-based resin include a ring-opening (co)polymer of a cyclic olefin, an addition polymer of a cyclic olefin, a copolymer of a cyclic olefin and an ethylene-like olefin-like chain olefin (represented by Random copolymers), and graft polymers which have been modified with unsaturated carboxylic acids or derivatives thereof, and such hydrides and the like. Among them, a norbornene-based resin which is a norbornene-based monomer such as a norbornene or a polycyclic norbornene-based monomer is preferably used as the cyclic olefin.

The cellulose ester resin is an ester of cellulose and a fatty acid. Specific examples of the cellulose ester-based resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. In addition, such copolymers may be used, or one of the hydroxyl groups may be modified by other substituents. Among these, triacetyl cellulose (TAC) is particularly preferred.

The polyester resin is ester-bonded, and is a resin other than the above cellulose ester-based resin, and is generally composed of a polycondensate of a polyvalent carboxylic acid or a derivative thereof and a polyhydric alcohol. As the polyvalent carboxylic acid or a derivative thereof, a dicarboxylic acid or a derivative thereof can be used, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalene dicarboxylate. A diol may be used for the polyhydric alcohol, and examples thereof include ethylene glycol, propane diol, butane diol, neopentyl glycol, and cyclohexane dimethanol.

Specific examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, and polybutylene terephthalate. , polybutyl naphthalate, polycyclohexane dimethyl terephthalate, polycyclohexane dimethyl naphthalate.

The polycarbonate resin is a polymer which is bonded to a monomer unit through a carbonate group. The polycarbonate resin may be a resin called a modified polycarbonate or a copolymerized polycarbonate modified with a polymer skeleton.

The (meth)acrylic resin is a resin having a compound having a (meth)acryl fluorenyl group as a main constituent monomer. Specific examples of the (meth)acrylic resin include, for example, polymethyl methacrylate-like poly(meth)acrylate; methyl methacrylate-(meth)acrylic acid copolymer; methyl methacrylate-( Methyl) acrylate copolymer; methyl methacrylate-acrylate-(meth)acrylic acid copolymer; methyl (meth) acrylate-styrene copolymer (MS resin, etc.); methyl methacrylate and A copolymer of a compound of an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate-methyl (meth) acrylate thioglycolate copolymer, etc.). Preferably, a polymer having a poly(methyl) acrylate-like poly(meth)acrylic acid C _1-6 alkyl ester as a main component is used, and more preferably, methyl methacrylate is used as a main component. (50 to 100% by weight, preferably 70 to 100% by weight) of a methyl methacrylate-based resin.

The thickness of the protective film is preferably 90 μm or less, more preferably 50 μm or less, and still more preferably 30 μm or less from the viewpoint of reducing the thickness of the polarizing plate. The thickness of the protective film is usually 5 μm or more from the viewpoint of strength and workability. According to the present invention, even if such a film is used When the film is protected, the relaxation can be effectively suppressed.

The ease of occurrence of slack is also known to be related to the moisture permeability of the protective film to be used, and it is easier to cause slack when a protective film having a large moisture permeability is used. It is believed that this is because the film with high moisture permeability is also prone to dimensional changes. For example, the polarizing plate is made of TAC and the polarizing plate is made of a protective film/polarizer made of a cyclic polyolefin resin or a (meth)acrylic resin/protective film made of TAC. The protective film/polarizer/protective film made of TAC is more likely to cause slack. Therefore, the present invention is particularly advantageous when the polarizing plate used contains a protective film having a high moisture permeability like TAC.

The polarizing plate may include a film or layer other than the protective film. Specific examples of the film or layer other than the protective film include: an adhesive layer; a separation film (release film) for protecting the outer surface of the adhesive layer; a protective film (surface protective film) for protecting the surface of the protective film; Functional surface treatment layer (coating layer); various optical functional films.

As the adhesive to be used for the adhesive layer, a conventionally known suitable adhesive can be used, and examples thereof include a (meth)acrylic resin adhesive, a urethane adhesive, a polyoxygen adhesive, a polyester adhesive, and a poly A guanamine-based adhesive, a polyether-based adhesive, a fluorine-based adhesive, a rubber-based adhesive, or the like. Among them, a (meth)acrylic resin adhesive is preferably used from the viewpoints of transparency, adhesion, reliability, reworkability and the like. The thickness of the adhesive layer may generally be from 1 to 40 μm (for example, from 3 to 25 μm).

The constituent material of the separation membrane may be a polyethylene-based polyethylene resin, a polypropylene-like polypropylene resin, or a polyethylene terephthalate-like polyester resin. Among them, it is preferred to extend the polyethylene terephthalate Stretch film.

The constituent material of the protective film may be a polyethylene-based polyethylene resin, a polypropylene-like polypropylene resin, or a polyethylene terephthalate-like polyester resin, among which moisture permeability and mechanical strength. From the viewpoint of the above, a stretch film of polyethylene terephthalate is preferred.

The surface treatment layer may be a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer, or an antifouling layer.

The optical functional film may be a reflective polarizing film that transmits a certain polarized light and causes a polarized light having an opposite property to be displayed; an anti-glare functional film having a concave-convex shape on the surface; a film with a surface reflection preventing function; and a surface having a reflection Functional reflective film; semi-transmissive reflective film with both reflective and transmissive functions; viewing angle compensation film.

The width of the polarizing plate wound around the convex core 10 is not particularly limited, but is usually about 300 to 2,500 mm, and more typically about 500 to 2,000 mm. Further, the length of the polarizing plate is not particularly limited, but is usually about several hundred m to 3,000 m (for example, about 2000 m), and more typically about 1,500 to 2,500 m. The width of the polarizer and the width of the protective film to which it is attached may be the same or different, but generally wider than the width of the protective film, and both ends of the protective film in the width direction (both ends) are located in the polarizer. The protective film is bonded to the outer end portions (both end surfaces) in the width direction.

(3) Positional relationship between the convex portion of the convex core and the wound polarizing plate in the width direction

Fig. 3 is a view schematically showing a convex portion and a warp for the convex core 10 A cross-sectional view of the positional relationship between the polarizing plates 20 in the width direction. Fig. 3 shows an example in which the polarizing plate 20 composed of the polarizing film 21, the first protective film 22 bonded to one surface thereof, and the second protective film 23 bonded to the other surface thereof is used. The layer structure of the plate is not limited to this. In addition, in the third drawing, only the first convex portion 10a of the convex portion winding core 10 is discussed. However, the following description applies to the positional relationship of the second convex portion 10b.

The polarizing plate 20 in the polarizing plate roll of the present invention is located on the first convex portion 10a at one end portion (end surface, T ₁ in FIG. 3) in the width direction of the polarizing plate 21, although not shown in the third portion. In the figure, the other end portion (end surface) is wound around the convex portion winding core 10 so as to be positioned on the second convex portion 10b. The end portion (end surface) T ₁ of the polarizing plate 21 is located on the first convex portion 10a. Referring to Fig. 3, the end portion T ₁ of the polarizing plate 21 is located at the outer end portion T ₂ and the inner side of the first convex portion 10a. T ₃ between the end portion (comprising ₂ or T T _{T. 1} and ₃ of the same case.). Thereby, a sufficient relaxation suppressing effect can be obtained. When the end portion T ₁ of the polarizer 21 is located outside the outer end portion (end surface) T _{2 of the} first convex portion 10a or is located inside the inner end portion (end surface) T _{3 of the} first convex portion 10a, charging cannot be obtained. The relaxation inhibition effect of the part. Preferably, the end portion T ₁ of the polarizer 21 is located outside the inner end portion T _{3 of the} first convex portion 10a.

Located (contained in) the end region of the upper polarizing plate 10a of the first protrusion 21 (including the region of the end of T ₁₎ of the width W ₂ (first polarizer 21 and the projection 10a overlap width portion) is preferably 5mm More preferably, it is 10 mm or more. Referring to Fig. 3, the overlapping width W ₂ corresponds to the distance from the end portion T _{1 of the} polarizer 21 to the inner end portion T ₃ of the first convex portion 10a. When the overlap width W _{2 is} too small, it is difficult to obtain a sufficient relaxation suppressing effect. The upper limit of the overlap width W ₂ is not particularly limited, but may be, for example, about 30 mm. It is preferable that the width W _{1 of the} first convex portion 10a is 5 mm or more which can obtain the above-described preferable overlapping width W ₂ . The upper limit of the width W ₁ is not particularly limited, and is, for example, 100 mm. In a preferred embodiment, the position of the end portion T ₁ of the polarizer 21 may be identical or nearly identical to the position of the outer end portion T ₂ of the first convex portion 10a (W ₁ and W _{2 are the} same or nearly the same). The end region of the polarizer 21 and the full width or almost the entire width of the first convex portion 10a are overlapped (multiplied).

In order to obtain the relaxation suppressing effect more effectively, referring to Fig. 3, the height H of the first convex portion 10a is preferably 50 μm or more, more preferably 120 μm or more, and still more preferably 500 μm or more. The higher the height H, the higher the tendency of the relaxation inhibition effect. The upper limit of the height H may be 1500 μm (for example, 1000 μm). For example, when a convex portion is formed by attaching a resin film, as shown in Fig. 4, in order to increase the height H, the resin film may be crimped and overlapped with a plurality of layers. FIG 4 based on the first resin film by t ₁ wrapping overlaid on the second resin film and t ₂ of the first embodiment of the projection portion 10a is formed.

As described above, generally, the width of the protective film is made larger, and the protective film is bonded so that both end portions in the width direction of the protective film are located outside the both end portions in the width direction of the polarizer. Referring to FIG. 3, The first protective film 22 and the second protective film 23 may have a width W ₃ (the distance from the end portion T _{4 of the} protective films 22 and 23 to the end portion T ₁ of the polarizer 21) of about 1 to 100 mm (for example, 5). Up to 60mm).

(4) Suppression of the winding and curling strip defects of the polarizing plate with the convex core

The convex portion winding core 10 winds up the polarizing plate 20 by rotating its central axis of rotation. At this time, as shown in Fig. 5, before the start of winding, it is preferable to fix the curl start end (longitudinal direction start end) of the polarizing plate 20 to the convex portion by using the fixing member 30 [Fig. 5(a)]. The outer peripheral surface of the winding core 10 [Fig. 5(b)]. Since the polarizing plate 20 can be easily fixed, it is preferable to use a double-sided tape as the fixing member 30. For example, the fixing member 30 of the double-sided tape is attached to the outer circumferential surface of the convex core 10 in parallel with the rotation axis of the convex core 10, and the curling start end of the polarizing plate 20 is provided thereon. The short side direction of the polarizing plate 20 is attached in parallel to the rotation axis of the convex core 10 . By fixing the curl start end of the polarizing plate 20 to the convex portion winding core 10, the winding of the polarizing plate 20 can be smoothly performed particularly at the initial stage.

However, when a crimping start end of a polarizing plate is fixed to a general core winding without a convex portion and a polarizing plate is wound using a fixing member such as a double-sided tape, a defect called "curl stripe defect" is particularly caused. Referring to Fig. 6, "curl stripe defect" means the difference between the curl start end of the polarizing plate fixed on the fixing member and/or the outer peripheral surface of the fixing member and the core, that is, the step portion, which is wound. The polarizing plate has a stripe-shaped recessed defect which is generated by extrusion in the width direction of the polarizing plate. The curled stripe defect has a defect K ₁ (a defect originating from a corner portion of the curl start end extruded from the polarizing plate) from a corner portion (a short corner of the end portion) of the curl start end of the polarizing plate, and The defect K ₂ of the corner portion of the fixing member like a double-sided tape (defect from the corner portion of the pressing fixing member) (Fig. 6).

The curling stripe defect is caused by the polarizing plate inside the polarizing plate roll (the polarizing plate at the beginning of the curling), and the more the polarizing plate roll The side is weaker, but it can be generated within a few tens of meters from the length of the length of the polarizing plate. When a polarizing plate including a crimped stripe defect is used for an image display device such as a liquid crystal display device, visibility is reduced.

The polarizing plate roll of the present invention is advantageous for suppressing such curled stripe defects. In general, the smaller the height H of the convex portion, the higher the effect of suppressing the curl streak defect. Therefore, in order to obtain a sufficient relaxation suppressing effect and to obtain an effect of suppressing curling defects, the height H is preferably less than 500 μm, preferably 400 μm or less. In order to obtain the effect of suppressing the curl fringe defect, the height H is preferably 50 μm or more (for example, 100 μm or more).

[Examples

Hereinafter, the present invention will be further illustrated by way of examples and comparative examples, but the invention is not limited to the examples.

<Comparative Example 1>

The layer is formed by a first protective film [thickness 40 μm] made of triacetyl cellulose (TAC), an adhesive layer/dichroic dye, and a polyvinyl alcohol-based resin film which is longitudinally uniaxially stretched. Polarized sheet [thickness 28 μm] / adhesive layer / TAC made of a second protective film [thickness 40 μm] / extended polyethylene terephthalate protective film [thickness 62 μm] made of long polarized light The plate was continuously produced in a roll-to-roll manner while being wound around a cylindrical core (without a convex portion) to obtain a polarizing plate roll. The specific conditions for making a polarizing plate roll are as follows. Further, the curl start end (starting end in the longitudinal direction) of the polarizing plate was fixed to the outer peripheral surface of the core by a double-sided tape having a thickness of 176 μm.

[1] cylindrical core (no protrusion)

‧Material: FRP (fiber reinforced plastic), ‧width direction (rotation axis direction) length: 1480mm, ‧ diameter: 167mm ,

[2] Polarizer

‧The width of the protective film: 1330mm, the width of the polarizer: 1270mm, ‧ in the third figure W ₃ : 30mm (both at both ends), ‧ the length of the polarizing plate: about 2000m, ‧ the tension when taking the polarizing plate : 250N.

<Example 1>

A polarizing plate roll was produced in the same manner as in Comparative Example 1, except that the convex portion winding core similar to that of Fig. 1 was used, and the specific conditions at the time of producing the polarizing plate roll were as follows. The polarizing plate is wound such that one end portion of the polarizer in the width direction is located on the first convex portion and the other end portion is located on the second convex portion. The first and second convex portions with the convex core are attached to the resin film tape having a certain width of the adhesive layer on one side, and are attached to the outer peripheral surface of the core body portion in a nearly full circumference as shown in Fig. 2 . And formed.

[1]With the convex core (body part: cylindrical)

‧Material: FRP (fiber reinforced plastic), ‧width direction (rotation axis direction) length: 1480mm, ‧body part diameter:167mm ‧ The width of the first and second convex portions (W ₁ in Fig. 3): 10 mm, the height of the first and second convex portions (H in Fig. 3): 720 μm,

[2] Polarizer

‧Protection film width: 1330mm, ‧Polar film width: 1270mm, ‧Protection film width (W ₃ in Figure ₃ ): 30mm (both ends), ‧Polar plate length: about 2000m,‧ Tension when the polarizing plate is taken up: 250N,

[3] Positional relationship between polarizer and convex core

‧ The width of the polarizer and the first and second convex portions are overlapped (W _{2 in} Fig. 3): 10 mm.

<Example 2>

A polarizing plate roll was produced in the same manner as in Example 1 except that the heights of the first and second convex portions (H in FIG. 3) were 360 μm.

<Example 3>

A polarizing plate roll was produced in the same manner as in Example 1 except that the heights of the first and second convex portions (H in FIG. 3) were 180 μm.

<Example 4>

A polarizing plate roll was produced in the same manner as in Example 1 except that the width of the polarizer and the width of the first and second convex portions (W ₂ in FIG. 3) was 2 mm.

<Example 5>

A polarizing plate roll was produced in the same manner as in Example 2 except that the first protective film was changed from a TAC film to a cyclic polyolefin resin (COP) film having a thickness of 20 μm.

<Comparative Example 2>

The overlap width (W ₂ in FIG. 3) of the polarizer and the first and second convex portions is 0 mm, that is, the end portion T ₁ of the polarizer is located at the inner end portion of the first and second convex portions. T ₃ is wound more than manner inside the polarizer, as in Example 1 was produced polarizing plate roll.

The main manufacturing conditions of the polarizing plate rolls of Examples 1 to 5 and Comparative Examples 1 to 2 are summarized in Table 1. The produced polarizing plate was stored in an environment of 25 ° C and 50% RH for 15 days, and then the following items were evaluated. The results are shown in Table 1.

(a) degree of relaxation

The polarizing plate after the storage was wound up, and the degree (length) of the slack was measured, and it was evaluated based on the following criteria. The degree of slack (length) refers to the length of the slack (wavy deformation) extending from the end portion in the width direction of the polarizing plate to the inner side (center portion side) of the polarizing plate (more preferably, the protective film). When the polarizing plate was wound from the polarizing plate of Comparative Example 1 using the winding core having no convex portion, the degree of slack from the start of winding to 70 to 75 times was the greatest.

A: The maximum value of the slack length is less than 60 mm, B: the maximum value of the slack length is 60 mm or more and less than 120 mm, and the maximum value of the C: slack length is 120 mm or more.

(b) degree of curling stripe defects

The polarizing plate after the storage was wound up, and the length of the curl streak defect from the curl of the polarizing plate was measured based on the following criteria, and the degree of the curl streak defect was evaluated.

A: The length of the severe curling stripe defect was observed to be less than 10 m. B: The length of the severe curling stripe defect was visually observed to be 10 m or more and less than 15 m. C: The length of the severe curling stripe defect was visually observed to be 15 m or more. .

10‧‧‧With convex core

10a‧‧‧1st convex

20‧‧‧Polar plate

21‧‧‧ polarizer

22‧‧‧1st protective film

23‧‧‧2nd protective film

H‧‧‧ Height of the convex part

T ₁ , T ₂ , T ₃ , T ₄ ‧ ‧ end of protective film

W ₁ , W ₂ , W ₃ ‧‧‧ End zone width

Claims (5)

A polarizing plate roll includes a winding core having a first convex portion and a second convex portion extending in a circumferential direction on an outer peripheral surface, and a polarizing plate wound around the winding core, wherein the polarizing plate includes a polarizing plate and a laminate a protective film on at least one side of the polarizing plate, wherein the one end portion in the width direction of the polarizer is positioned on the first convex portion, and the other end portion is located on the second convex portion Core. The polarizing plate roll according to the first aspect of the invention, wherein the width of the end portion of the polarizer located on the first convex portion and the second convex portion is 5 mm or more. The polarizing plate roll according to the first or second aspect of the invention, wherein the height of each of the first convex portion and the second convex portion is 50 μm or more. The polarizing plate roll according to any one of the first aspect, wherein the first convex portion and the second convex portion are formed of a resin film attached to the outer circumferential surface. The polarizing plate roll according to any one of the first to fourth aspects, wherein the thickness of both ends of the polarizing plate in the width direction is 1.01 to 1.2 times the thickness of the central portion in the width direction.