TWI665476B - Polarizing plate roll - Google Patents

Abstract

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

Description

Polarizing plate roll

The present invention relates to a polarizing plate roll obtained by winding a long polarizing plate around a winding core.

Polarizing plates are used in display devices such as liquid crystal display devices, and in particular, they have been widely used in various mobile devices such as mobile phones in recent years. As a polarizing plate, a protective film is usually bonded to one or both sides of the polarizer. However, with the development of mobile devices, the thickness of the polarizing plate and the protective film constituting the polarizing plate is increasing.

In the manufacture of polarizing plates, a long (belt-shaped) raw material film is generally used. The raw material film is rolled from a roll of a raw material film wound around a core (winding axis), and the rolled raw material film is rolled. Processing is performed to form a long (strip-shaped) polarizing plate, and the obtained polarizing plate is wound on a roll core to become a roll, that is, performed in a roll-to-roll manner. Therefore, a polarizing plate is usually obtained by winding a long-type polarizing plate around a roll of a polarizing plate (for example, Japanese Patent Application Laid-Open No. 2013-029754 (Patent Document 1)).

[Advanced technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open 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 2000m, and the diameter of the winding core is 150mm. At this time, the number of windings of the polarizing plate will reach about 4000 times.

Most of the polarizing plates manufactured in the form of a polarizing plate roll are held until they are further supplied to subsequent steps such as laminating to another film or forming a coating layer, or during continuous periods such as transport to the supply target. The status of the volume.

However, in some continuous periods, the polarizing plate rolled out after being kept in the rolled state is prone to a problem of deformation accompanied by "looseness" at both ends in the width direction. This problem becomes more significant as the polarizer or protective film constituting the polarizing plate becomes thinner. "Looseness" refers to wavy deformation (deformation) generated at both ends in the width direction of the polarizing plate. When the slack is greatly enlarged from the wide end to the inside of the polarizer (central portion side), when it is bonded to another film or forms a coating layer in the subsequent steps, the polarizer is prone to wrinkles or bubbles. In some cases, the quality of the product is reduced, and in some cases, the implementation of the subsequent steps becomes difficult.

Here, an object of the present invention is to provide a polarizing plate roll, which is a polarizing plate roll obtained by winding a polarizing plate around a winding core, and when the polarizing plate is rolled out from the roll, it can be confirmed that the The "looseness" produced by the ends can be suppressed.

When investigating the slack, it was found that the film thickness distribution of the polarizer included in the polarizing plate is the main cause of the slack. That is, a polarizer is generally manufactured through a step of stretching a strip-shaped resin film or the like as a raw material in a longitudinal direction (film length direction) or a lateral direction (film width direction). , The thickness of both ends will increase. A polarizing plate provided with a polarizer containing the film thickness distribution also has a film thickness distribution having the same tendency. When the polarizing plate is wound around a winding core, the polarizing plate is repeatedly wound at both ends in the width direction of the polarizing plate. When the overall thickness of the polarizing plate becomes high, the polarizing plate will be wound again, so the circumferential direction stress at the two end regions of the rolled polarizing plate becomes larger, so that the two end regions become stretched. Coiled. This is the main cause of slack.

Based on the above review results, the present invention provides a polarizing plate roll as shown below as a means to solve the above-mentioned problems.

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

[2] The polarizing plate roll described in [1], wherein the widths of the end regions of the polarizers on the first convex portion and the second convex portion are each 5 mm or more.

[3] The polarizing plate roll according to [1] or [2], 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] to [3], wherein the first convex portion and the second convex portion are made of a resin film attached to the outer peripheral surface.

[5] The polarizing plate roll according to any one of [1] to [4], 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, a polarizing plate roll capable of suppressing slack in both ends of the polarizing plate in the width direction can be provided. By the relaxation suppression, the quality of the polarizing plate itself and the product obtained in the subsequent steps as described above and the yield of the product can be improved, and the ease of implementation of the subsequent steps can be improved.

10‧‧‧ with raised core

10a‧‧‧1st protrusion

10b‧‧‧ 2nd protrusion

20‧‧‧ polarizing plate

21‧‧‧Polarizer

22‧‧‧The first protective film

23‧‧‧Second protective film

30‧‧‧Fixed components

H‧‧‧ height of protrusion

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

W ₁ 、 W ₂ 、 W ₃ ‧‧‧End area width

FIG. 1 is a schematic diagram showing an example of a roll core with a convex portion used in the polarizing plate roll of the present invention.

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

FIG. 3 is a cross-sectional view schematically showing a positional relationship between the convex portion of the core with the convex portion and the wound polarizer in the wide direction.

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

Fig. 5 (a) and (b) are schematic diagrams showing a state in which the end of the polarizing plate at which winding is started is fixed to the core with a convex portion using a fixing member.

FIG. 6 is a schematic diagram for explaining curled streak defects.

The polarizing plate roll of the present invention is as shown in an example of FIG. 1 and FIG. 2, and the winding core is a winding core with convex portions provided on the outer peripheral surface with the first convex portion 10 a and the second convex portion 10 b. 10. A polarizing plate in the form of a roll formed by winding a long polarizing plate. In the present invention, in order to suppress the occurrence of the “slackness” described above, the polarizing plate is configured such that one side end portion of the polarizing plate constituting the polarizing plate 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 winding core 10 with a convex part. The positional relationship between the convex portions 10a, 10b of the core 10 with convex portions 10 and the wound polarizing plate in the width direction will be described in detail in the item (3) below.

The polarizing plate is wound in the above-mentioned positional relationship to suppress slack. It is because the two ends of the polarizer with the largest thickness in the width direction of the polarizing plate are placed on the convex portions of the core 10 with convex portions, so that The above-mentioned stresses in the circumferential direction of the regions of both ends of the rolled polarizer are alleviated. In addition, as in Comparative Example 1 described below, the degree of slack (length) is generally extremely large, and it is about 70 to 75 times from the number of windings at the start of curling (although it is also affected by the diameter of the winding core, However, from the distance (curling length) at the end of the curling start (approximately 30 to 40 m), when the number of windings becomes more than this, although not obvious, the degree of slacking becomes smaller. The degree of slackness (length) herein refers to the length that the wavy deformation extends from the widthwise end portion of the polarizing plate to the inside (central portion side) of the polarizing plate.

(1) Core with convex part

The core 10 with convex portions may have the same shape as the conventionally known core except the first convex portion 10a and the second convex portion 10b. The main body of the core excluding the convex portions may be, for example, a cylinder. Shaped or cylindrical. The material is not particularly limited, and metals, alloys, and resins (such as thermoplastic resins) can be used. The length in the width direction (rotation axis direction) of the core 10 with raised portions is the same as or longer than the width of the rolled polarizer. The diameter of the roll core 10 with a convex portion when it is cylindrical or cylindrical, can be the general diameter of the roll 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 peripheral surface of the core core 10 with convex portions depends on the width of the rolled polarizer. 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 an end portion of one side in the wide direction of the polarizer constituting the polarizing plate is located at the first convex portion. 10a, the other end part is provided so that it may be located on the 2nd convex part 10b. As shown in FIG. 1, the first convex portion 10 a and the second convex portion 10 b are generally provided in an end region (including an end portion) or near the end portion in the width direction (rotation axis direction) of the core 10 with the convex portion.

The first convex portion 10a and the second convex portion 10b are provided on the outer peripheral surface of the roll core 10 with convex portions, and are provided so as to extend in the circumferential direction of the roll core 10 with convex portions. The circumferential direction of the core 10 extends in parallel (vertical direction with respect to the rotation axis direction of the roll core 10 with a convex portion). As shown in FIG. 2, the first convex portion 10 a and the second convex portion 10 b are preferably band-shaped, and are preferably looped around the entire periphery or almost the entire periphery of the outer peripheral surface of the core 10 with the convex portion. Shape setting.

The first convex portion 10a and the second convex portion 10b can be connected to the attached convex portion. The main body portion of the roll core 10 is integrally formed, and may be formed using other members different from the main body portion. The method of forming the convex portion by using another member may be exemplified by forming the first convex portion 10a and the second convex portion on the outer peripheral surface of the cylindrical or cylindrical core which is the main body portion of the core 10 with the convex portion. 10b method of a resin film (such as a film tape from a thermoplastic resin). In order to adhere to the outer peripheral surface of the roll core, the resin film may be an adhesive layer on one side. According to the method of attaching the resin film using an adhesive, since it can be reattached, it is easy to adjust or change the position of the convex portion. The method of forming the convex portion by attaching the resin film is advantageous in terms of both the production cost and the simplicity of production of the roll core 10 with the convex portion, and it is also possible to obtain the roll with the convex portion having sufficient strength.芯 10。 Core 10. The resin film may be attached to the outer peripheral surface of the core using an adhesive.

(2) Polarizer

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

As the polarizer, a dichroic dye is adsorbed and aligned on a uniaxially stretched resin film. The resin film may be a polyvinyl alcohol-based resin film. As the dichroic pigment, iodine or a dichroic dye can be used. As the polyvinyl alcohol-based resin constituting the polarizer, a saponified polyvinyl acetate-based resin can be used. Polyacetic acid Except for polyvinyl acetate which is a homopolymer of vinyl acetate, the olefin ester resin is exemplified by copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers that can be copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated fluoric acids, and (meth) acrylamidoamines having an ammonium group. In this specification, "(meth) acrylic" means at least one selected from acrylic and methacrylic. The same applies to "(meth) acrylic acid".

The saponification degree of the polyvinyl alcohol-based resin is usually about 85 to 100 mol%, and preferably 98 mol% or more. The polyvinyl alcohol-based resin can be modified. For example, polyvinyl formaldehyde and polyvinyl acetal modified with aldehydes can be used. The degree of polymerization of the polyvinyl alcohol resin is usually about 1,000 to 10,000, preferably about 1500 to 5,000.

The polarizer can be produced by a method including the following steps: a step of uniaxially extending the raw material film made of the polyvinyl alcohol-based resin described above (typically, extending uniaxially in the longitudinal direction of the film); and A step of dyeing a resin film with a dichroic pigment to adsorb a dichroic pigment; a step of treating a polyvinyl alcohol-based resin film having a dichroic pigment adsorbed with a boric acid aqueous solution; and washing with a boric acid aqueous solution step. Before the dyeing treatment, a swelling step of applying a dipping treatment to water may be provided.

The uniaxial extension of the polyvinyl alcohol-based resin film may be performed before, during, or after the dichroic dye is dyed. When the uniaxial extension is performed after dyeing, the uniaxial extension may be performed before or during the boric acid treatment. In addition, uniaxial extension may be performed in a plurality of such stages.

The thickness (average thickness of the full width) of the polarizer is, for example, 40 μ m or less, preferably 25 μm or less, and particularly in the case of a polarizing plate for a mobile device, the thickness is preferably 10 μm or less. The thickness of the polarizer is usually 2 μm or more. According to the present invention, even if such a thin-film polarizer is used, slack can be effectively suppressed.

As mentioned above, polarizers are usually manufactured by extending a polyvinyl alcohol resin film in the longitudinal direction (length direction of the film). Therefore, the polarizer has a larger film thickness distribution at both end portions than the central portion in the wide direction. . The polarizing plates accompanying this usually have the same thickness distribution. The thickness of both ends of the polarizing plate in the width direction 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 when there is such a large difference in film thickness, slack can be effectively suppressed.

The protective film attached to the polarizer may be a film made of a thermoplastic resin having translucency (preferably optically transparent). The thermoplastic resin is, for example, a chain polyolefin resin (polypropylene resin, etc.). Polyolefin resins such as cyclic polyolefin resins (norbornene resins, etc.); cellulose triacetate, cellulose diacetate-like cellulose ester resins; polyester resins; polycarbonate resins; (Meth) acrylic resins; polystyrene resins; or mixtures and copolymers thereof. When a protective film is attached to both sides of the polarizer, these may be protective films made of the same kind of resins, or protective films made of different kinds of resins.

The protective film may be a protective film having optical functions such as a retardation film and a brightness enhancement film. For example, a film made of the above-mentioned thermoplastic resin can be formed by stretching (uniaxial or biaxial stretching, etc.) or forming a liquid crystal layer on the film. Etc., and it becomes a retardation film which gives arbitrary retardation value.

The chain 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 chain olefins.

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

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, it is also possible to use these copolymers or those in which a part of the hydroxyl group is modified with another substituent. Among these, particularly preferred is triacetylcellulose (TAC).

The polyester resin is a resin other than the cellulose ester resin having an ester bond, and is generally a polycondensate of a polycarboxylic acid or a derivative thereof and a polyhydric alcohol. As the polycarboxylic 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 naphthalate. As the polyol, a diol can be used, and examples thereof include ethylene glycol, propanediol, butanediol, neopentylethylene glycol, and cyclohexanedimethanol.

Specific examples of the polyester-based resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, and polytrimethylene terephthalate. , Polypropyl naphthalate, polycyclohexane dimethyl terephthalate, polycyclohexane dimethyl naphthalate.

Polycarbonate resin is a polymer formed by a carbonate group and a monomer unit. The polycarbonate-based resin may be a resin called a modified polycarbonate or a copolymerized polycarbonate with a modified polymer skeleton.

The (meth) acrylic resin is a resin mainly composed of a compound having a (meth) acrylfluorenyl group as a monomer. Specific examples of the (meth) acrylic resin include, for example, poly (meth) acrylate such as polymethyl methacrylate; methyl methacrylate- (meth) acrylic copolymer; and methyl methacrylate- ( (Meth) acrylate copolymer; methyl methacrylate-acrylate- (meth) acrylic copolymer; methyl (meth) acrylate-styrene copolymer (MS resin, etc.); methyl methacrylate and having Copolymers of alicyclic hydrocarbon-based compounds (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate-norbornyl (meth) acrylate copolymer, etc.). Preferably, a polymer containing poly (meth) acrylic acid C _1-6 alkyl ester as poly (meth) acrylate 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) a methyl methacrylate resin.

From the viewpoint of reducing the thickness of the polarizing plate, 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. The thickness of the protective film is usually 5 μm or more from the viewpoints of strength and workability. According to the present invention, even when using such a film When the film is protected, the sag can still be effectively suppressed.

The easiness of sag is also known to be related to the moisture permeability of the protective film used, and it is easier to produce slack when using a protective film with a large moisture permeability. It is believed that this film is also prone to dimensional changes due to the high moisture permeability of the film. For example, compared with a polarizing plate made of a cyclic polyolefin resin or a (meth) acrylic resin made of a protective film / polarizer / protective film made of TAC, the polarizing plate is 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 to be used includes a protective film having high moisture permeability such as TAC.

The polarizing plate may include a film or layer other than a protective film. Specific examples of the film or layer other than the protective film include: an adhesive layer; a separation film (peel-off film) that protects the outside of the adhesive layer; a protective film (surface protective film) that protects the surface of the protective film; Functional surface treatment layer (coating layer); various optical functional films.

As the adhesive used in the adhesive layer, conventionally known suitable adhesives can be used, and examples thereof include (meth) acrylic resin adhesives, polyurethane adhesives, polysiloxane adhesives, polyester adhesives, and polymer adhesives. Phenylamine-based adhesives, polyether-based adhesives, fluorine-based adhesives, rubber-based adhesives, and the like. Among these, 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 be generally 1 to 40 μm (for example, 3 to 25 μm).

The constituent material of the separation membrane may be a polyethylene-based resin such as polyethylene, a polypropylene-based resin such as polypropylene, or a polyester-based resin such as polyethylene terephthalate. Among them, the extension of polyethylene terephthalate is preferred Stretch the membrane.

The material of the protective film can be polyethylene-based polyethylene resin, polypropylene-based polypropylene resin, or polyethylene terephthalate-based polyester resin. Among them, moisture permeability and mechanical strength From the viewpoint, a stretched film of polyethylene terephthalate is preferred.

The surface treatment layer may be a hard coating layer, an anti-glare layer, an anti-reflection layer, an anti-static layer, or an anti-fouling layer.

Examples of optical functional films are: reflective polarizing films that transmit a certain type of polarized light and reflect polarized light of the opposite property; reflective films with anti-glare functions on the surface with uneven shapes; films with anti-glare functions on the surface; 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 core core 10 with raised portions is not particularly limited, but it is usually about 300 to 2500 mm, and more typically about 500 to 2000 mm. In addition, the length of the polarizing plate is not particularly limited, but it is usually about several hundred meters to about 3,000 meters (for example, about 2,000 meters), and more typically about 1,500 to 2500 meters. The width of the polarizer and the width of the protective film to which it is attached may be the same or different, but it is generally larger than the width of the protective film, and the two ends (both ends) in the width direction of the protective film are located more than the polarizer. The protective film is attached to both ends (both end faces) in the width direction so as to be more outward.

(3) Position relationship between the convex part of the core with convex part and the wound polarizer in the wide direction

FIG. 3 is a schematic view showing the convex portion and the warp of the core 10 with convex portions. A cross-sectional view of the positional relationship between the wound polarizers 20 in the wide direction. Figure 3 shows an example of using a polarizing plate 20 composed of a polarizer 21, a first protective film 22 bonded on one side, and a second protective film 23 bonded on the other side, but the polarized light is as described above. The layer structure of the plate is not limited to this. In addition, in FIG. 3, only the first convex portion 10a of the core 10 with convex portions is discussed. However, the content described below also 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 with one end portion (end surface, T ₁ in FIG. 3) of one side in the width direction of the polarizing plate 21, although not shown in the third In the figure, the other end portion (end surface) is wound around the core core 10 with a convex portion so as to be positioned on the second convex portion 10b. The end portion (end surface) T ₁ of the polarizer 21 is located on the first convex portion 10 a. Referring to FIG. 3, it means that the end portion T ₁ of the polarizer 21 is located on the outside end portion T ₂ and the inside of the first convex portion 10 a. Between the ends T ₃ (including the case where T ₁ matches T ₂ or T _3. ). Thereby, a sufficient slack suppressing effect can be obtained. When the end portion T ₁ of the polarizer 21 is located more outward than the end portion (end surface) T _{2 on the} outer side of the first convex portion 10 a, or more inward than the inner end portion (end surface) T _{3 of the} first convex portion 10 a, the charging cannot be obtained. Slack-suppressing effect. Preferably, the end portion T ₁ of the polarizer 21 is located further outside than the inner end portion T _{3 of the} first convex portion 10 a.

The width W ₂ (the overlapping width of the polarizer 21 and the first convex portion 10a) of the end portion area (the area including the end portion T ₁ ) of the polarizer 21 located on the first convex portion 10a is preferably 5 mm. The above is more preferably 10 mm or more. Referring to FIG. 3, the overlap width W ₂ corresponds to a distance from the end portion T _{1 of the} polarizer 21 to the inner end portion T ₃ of the first convex portion 10 a. When the overlap width W _{2 is} too small, it is difficult to obtain a sufficient slack suppressing effect. The upper limit of the overlap width W ₂ is not particularly limited, but may be, for example, about 30 mm. The width W _{1 of the} first convex portion 10 a is preferably set to 5 mm or more to obtain the above-mentioned 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 and the position of the end portion T _{2 on} the outer side of the first convex portion 10a may be the same or nearly the same (W ₁ and W _{2 are the} same or nearly the same) The full width or almost full width of the end region of the polarizer 21 and the first convex portion 10a is overlapped (loaded).

In order to obtain the sag suppression 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 even more preferably 500 μm or more. The greater the height H, the higher the relaxation suppression effect tends to be. 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 curled to overlap 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, the width of the protective film is generally made larger, and the protective film is bonded in such a manner that both ends in the width direction of the protective film are positioned more outward than both ends in the width direction of the polarizer, but referring to FIG. 3, The first protective film 22 and the second protective film 23 have an exposed 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 To about 60mm).

(4) Suppression of coiling and curling streak defect of polarizing plate with convex core

The winding core 10 with a convex portion rotates the center of the rotation axis to wind up the polarizing plate 20. At this time, as shown in Fig. 5, it is preferable to use a fixing member 30 [Fig. 5 (a)] to fix the curling start end (starting end in the longitudinal direction) of the polarizing plate 20 to the projection before the winding is started. The outer peripheral surface of the partial 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 affixed to the outer peripheral surface of the core core 10 with protrusions in a manner parallel to the rotation axis of the core core 10 with protrusions, and the curling start end of the polarizing plate 20 is placed above it. The short side direction of the polarizing plate 20 is attached in a manner parallel to the rotation axis of the roll core 10 with the convex portion. By fixing the curling start end of the polarizing plate 20 to the roll core 10 with convex portions, the winding of the polarizing plate 20 can be smoothly performed particularly in the initial stage.

However, when using a fixing member such as a double-sided tape to fix the start of curling of a polarizing plate to a general core without a convex portion, and then taking up the polarizing plate, a defect called a “curly streak defect” occurs. Referring to Fig. 6, "curly streak defect" refers to the height difference between the start of curling of the polarizing plate fixed on the fixed member and / or the fixed member and the outer peripheral surface of the core, that is, the stepped portion, Stripe-shaped depression defects extending in the width direction of the polarizing plate due to the pressing of the polarizing plate. The curl streak defects are defects K ₁ (defects generated from the corners of the curl start end of the polarizing plate that is pressed against the curl start end of the polarizer), and from Defect K ₂ of the corner of the fixing member like a double-sided tape (defect caused by pressing the corner of the fixing member) (Fig. 6).

The curl streak defect is a polarizing plate (polarizing plate at the beginning of curling) which is seriously generated on the inner side of the polarizing plate roll, and is more and more out of the polarizing plate roll. The side becomes weaker, but it can occur within tens of meters across the length from the beginning of the curling of the polarizing plate. When a polarizing plate containing a curled streak defect is used in an image display device such as a liquid crystal display device, visibility may be reduced.

The polarizing plate roll of the present invention is advantageous for suppressing such curling streak 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 sag suppression effect and to obtain a curl streak defect suppression effect, the height H is preferably less than 500 μm, and more preferably 400 μm or less. In order to obtain the effect of suppressing curl streaks, the height H is preferably 50 μm or more (for example, 100 μm or more).

[Example

Hereinafter, the present invention will be described more specifically by showing examples and comparative examples, but the present invention is not limited to these examples.

<Comparative example 1>

The layer is constituted by a first protective film [thickness 40 μm] made of triacetyl cellulose (TAC) / adhesive layer / dichroic dye adsorbed and aligned on a polyvinyl alcohol-based resin film extending in a longitudinal uniaxial direction. Polarizer [thickness 28μm] / adhesive layer / second protective film made of TAC [thickness 40μm] / long protective film made of stretched polyethylene terephthalate [thickness 62μm] The plate is continuously produced in a roll-to-roll manner, and is wound around a cylindrical roll core (without convex portions) to obtain a polarizing plate roll. The specific conditions when making a polarizing plate roll are as follows. In addition, the curling start end (starting end in the longitudinal direction) of the polarizing plate was fixed to the outer peripheral surface of the core using a double-sided tape having a thickness of 176 μm.

[1] Cylindrical roll core (without protrusions)

‧Material: FRP (fiber-reinforced plastic), ‧Width (direction of rotation axis) Length: 1480mm, ‧Diameter: 167mm ,

[2] Polarizer

‧Width of the protective film: 1330mm, ‧Width of the polarizer: 1270mm, ‧W 3 in Figure ₃ : 30mm (this is the case at both ends), ‧Polarizer length: about 2000m, ‧Tension when winding the polarizer : 250N.

<Example 1>

A polarizing plate roll was produced in the same manner as in Comparative Example 1 except that the same roll core with convex portions as in FIG. 1 was used, and the specific conditions when producing the polarizing plate roll were set forth below. The polarizing plate is wound such that one end portion in the width direction of the polarizer is located on the first convex portion, and the other end portion is wound on the second convex portion. The first and second convex portions of the core with the convex portion are a resin film tape having a certain width with an adhesive layer on one side, and are attached on the outer peripheral surface of the core body portion in a nearly all-around manner as shown in FIG. And formed.

[1] Roll core with convex part (body part: cylindrical)

‧Material: FRP (fiber-reinforced plastic), ‧Wide direction (rotation axis direction) length: 1480mm, ‧Diameter of the body part: 167mm ‧ the width of the first and second protrusions (W ₁ in Figure 3): 10mm, the height of the first and second protrusions (H in Figure 3): 720 μm,

[2] Polarizer

‧The width of the protective film: 1330mm, The width of the polarizer: 1270mm, The exposed width of the protective film (W ₃ in Figure ₃ ): 30mm (this is true at both ends), The length of the polarizer: about 2000m Tension at the time of winding of polarizing plate: 250N,

[3] Polarity between polarizer and core with convex part

‧Polar width of the polarizer and the first and second convex parts (W _{2 in} Figure ₃ ): 10mm.

<Example 2>

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

<Example 3>

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

<Example 4>

A polarizing plate roll was produced in the same manner as in Example 1 except that the overlapping width of the polarizer and 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>

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

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

(a) Degree of relaxation

The polarizer after the storage was rolled out, and the degree (length) of slack was measured, and evaluated based on the following criteria. The degree of slack (length) refers to the length that the slack (wave-like deformation) extends from the wide end of the polarizing plate to the inner side (central portion side) of the polarizing plate (more precisely, the protective film). When the polarizing plate was rolled out from the polarizing plate of Comparative Example 1 using a winding core having no convex portion, the degree of slack was greatest at the number of windings from 70 to 75 times from the start of curling.

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 C: The maximum value of the slack length is 120 mm or more.

(b) Degree of curl streak defect

The polarizer after the storage was rolled out, and the curl streak defect from the curling of the polarizer was measured based on the following criteria to evaluate the degree of the curl streak defect.

A: The length of the serious curled streak defect is not more than 10m visually, B: The length of the serious curled streak defect is visually observed from 10m to 15m, and the C: The length of the serious curled streak defect is visually observed is 15m or more .

Claims (9)

A polarizing plate roll includes a winding core including 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 polarizer and a laminated layer. On at least one side of the protective film, the polarizing plate is wound on the first convex portion such that one end portion in the width direction of the polarizer is on the first convex portion, and the other end portion is on the second convex portion. Core. The polarizing plate roll according to item 1 of the scope of patent application, wherein the widths of the end regions of the polarizers located on the first convex portion and the second convex portion are each 5 mm or more. The polarizing plate roll according to item 1 or 2 of the scope of patent application, wherein the heights of the first convex portion and the second convex portion are each 50 μm or more. The polarizing plate roll according to item 1 or 2 of the scope of patent application, wherein the first convex portion and the second convex portion are made of a resin film attached to the outer peripheral surface. The polarizing plate roll according to item 3 of the scope of patent application, wherein the first convex portion and the second convex portion are made of a resin film attached to the outer peripheral surface. The polarizing plate roll according to item 1 or 2 of the scope of the patent application, 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. The polarizing plate roll as described in item 3 of the scope of patent application, 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. The polarizing plate roll according to item 4 of the scope of patent application, wherein the thickness of the two 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. The polarizing plate roll according to item 5 of the scope of patent application, wherein the thickness of the two 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.