JP2009134190A - Method of manufacturing polarizing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method and manufacturing equipment of a polarizing plate, in which the occurrence of reverse curl and wave curl is suppressed. <P>SOLUTION: The method of manufacturing the polarizing plate prepared by stacking and adhering protective films 31, 32 respectively on both surfaces of a polarizer 35 comprises: a step of overlapping the polarizer 35 and the protective films 31, 32 via adhesives to obtain a laminate 37; and a subsequent step of adhering the laminate 37 onto a convex curved surface formed in an arcuate shape along the conveyance direction of the laminate 37, preferably on the outer surface of a roller 38 and, at the same time, irradiating an adhesive with active energy rays from active energy ray irradiation devices 39, 40 to polymerize and harden the adhesive. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a polarizing plate useful as one of optical components constituting a liquid crystal display device.

  The polarizing plate is useful as one of the optical components constituting the liquid crystal display device. FIG. 4 shows a structure in which a linearly polarizing film that is one type of polarizing plate is laminated on a liquid crystal cell. On the light source side surface of the liquid crystal cell 10 constituting the liquid crystal display panel, a linearly polarizing film 12 is adhered and laminated with an adhesive layer 11 to constitute a liquid crystal display panel.

  The polarizing plate is usually used by being incorporated in a liquid crystal display device in a state where protective films are laminated on both sides of the polarizer. That is, as shown in FIG. 5, a normal polarizing plate 20 has protective films 22 and 23 laminated on both surfaces of a polarizer 21 via adhesive layers 24 and 25 (Patent Document 1, Patent). Literature 2 etc.).

However, the polarizing plate manufactured in this way is curled so that the side to be attached to the liquid crystal cell is concave (hereinafter referred to as “reverse curling”), or the entire polarizing plate is wavy. (Hereinafter, this is referred to as “wave curl”). Such reverse curl and wave curl are liable to cause bubbles to remain on the adhesive surface when sticking to the liquid crystal cell, thereby causing defects in the liquid crystal panel. For this reason, the polarizing plate does not generate reverse curl and wave curl, does not curl, or is curled so that the side to be attached to the liquid crystal cell becomes convex (hereinafter referred to as “normal curl”). It is hoped to do.
JP 2004-245925 A JP 2005-173216 A

  An object of the present invention is to provide a polarizing plate manufacturing method and manufacturing apparatus in which the occurrence of reverse curling and wave curling is suppressed.

  As a result of intensive studies to achieve the above object, the present inventor has obtained an adhesive in a state in which a laminate in which a protective film is laminated on one or both sides of a polarizer via an adhesive is bent so as to have a positive curl. It was found that the occurrence of reverse curling and wave curling can be suppressed by polymerizing and curing the present invention, thereby completing the present invention.

  That is, the polarizing plate manufacturing method of the present invention is a polarizing plate manufacturing method in which a protective film is laminated and bonded to one or both sides of a polarizer, and the polarizer and the protective film are overlapped with an adhesive. A laminate is obtained, and then the adhesive is polymerized and cured while the laminate is brought into close contact with a convex curved surface formed in an arc shape along the longitudinal direction (conveying direction) of the laminate. For the convex curved surface, for example, the outer peripheral surface of a roll can be used.

  The polarizer is a uniaxially stretched polyvinyl alcohol film in which iodine or dichroic dye is adsorbed and oriented, one of the protective films is an amorphous polyolefin resin film, and the other is a triacetyl cellulose film. However, the present invention is not limited to these examples.

  Although it is preferable to polymerize and cure the active material by irradiating the laminated body in close contact with the convex curved surface, it may be polymerized and cured by heating.

  The polarizing plate manufacturing apparatus of the present invention includes a means for applying an adhesive on one side of the protective film or on both sides of the polarizer, a means for superposing the protective film on both sides of the polarizer via an adhesive layer, A roll manufacturing apparatus for polarizing plates, comprising means for polymerizing and curing the agent, wherein the means for polymerizing and curing the adhesive conveys a polarizer with a protective film superimposed thereon in close contact with the outer peripheral surface. And an active energy ray irradiating device that irradiates active energy rays toward the outer peripheral surface of the roll.

  According to the present invention, a laminate in which a polarizer and a protective film are overlapped with an adhesive is brought into close contact with a convex curved surface formed in an arc shape along the longitudinal direction (conveying direction) of the laminate. By irradiating active energy rays and polymerizing and curing the adhesive, when the polarizing plate is bonded to the liquid crystal cell, bubbles on the bonding surface remain and cause defects in the liquid crystal panel. Occurrence is suppressed.

  Hereinafter, an embodiment of the present invention will be described. The polarizing plate according to this embodiment includes a polarizer and a protective film laminated on both surfaces of the polarizer via an adhesive. As the polarizer, those conventionally used for the production of polarizing plates (for example, the polarizer described in Patent Document 1 described above) can be used, and generally iodine or bicolor on a uniaxially stretched polyvinyl alcohol film. And a film formed by dyeing with a sexual dye and then boric acid treatment. The thickness of the polarizer is preferably about 5 to 50 μm.

  The protective films laminated on both sides of the polarizer may be the same or different types. When using different types of protective films, one of the protective films is amorphous polyolefin resin film, polyester resin film, acrylic resin film, polycarbonate resin film, polysulfone resin film, alicyclic polyimide film A resin film with low moisture permeability such as a resin film is used. Examples of the amorphous polyolefin-based resin film include “Topas” manufactured by Ticona of Germany, “Arton” manufactured by JSR Co., Ltd., and “ZEONOR” manufactured by Nippon Zeon Co., Ltd. And “ZEONEX” and “Appel” manufactured by Mitsui Chemicals, Inc. As the other protective film, in addition to these films, for example, a cellulose acetate resin film such as a triacetyl cellulose film or a diacetyl cellulose film is used. Examples of the triacetyl cellulose film include “Fujitack TD80”, “Fujitack TD80UF” and “Fujitack TD80UZ” manufactured by Fuji Photo Film Co., Ltd., “KC8UX2M” and “KC8UY” manufactured by Konica Corporation.

  Prior to bonding to the polarizer, the protective film may be subjected to easy adhesion treatment such as saponification treatment, corona treatment, primer treatment, and anchor coating treatment on the bonding surface. Moreover, you may have various process layers, such as a hard-coat layer, an antireflection layer, and a glare-proof layer, in the surface on the opposite side to the bonding surface to the polarizer of a protective film. The thickness of the protective film is usually in the range of about 5 to 200 μm, preferably 10 to 120 μm, and more preferably 10 to 85 μm.

  As an adhesive, from the viewpoint of weather resistance, refractive index, cationic polymerization, and the like, an epoxy resin that does not contain an aromatic ring in the molecule as described in Patent Document 1, for example, can be used. It is not limited to these, and various adhesives conventionally used for the production of polarizing plates can be employed. Examples of the epoxy resin include hydrogenated epoxy resins, alicyclic epoxy resins, and aliphatic epoxy resins. Add a polymerization initiator to the epoxy resin component, for example, a photocationic polymerization initiator for polymerization by irradiation with active energy rays, a thermal cationic polymerization initiator for polymerization by heating, and other additives (sensitizers, etc.). To prepare a coating adhesive composition.

  Next, the manufacturing apparatus and manufacturing method of the polarizing plate of this invention are demonstrated, referring drawings. FIG. 1 is a schematic view showing an embodiment of a polarizing plate production apparatus of the present invention.

  The polarizing plate manufacturing apparatus 30 shown in FIG. 1 overlaps the protective film 31, 32, and the polarizer 35 with the adhesive coating apparatuses 33, 34 for applying an adhesive to one side of the protective films 31, 32. Nip roll 36, a roll 38 for closely attaching the laminate 37 on which the protective films 31, 32 and the polarizer 35 are bonded, and a first face disposed at a position facing the outer peripheral surface of the roll 38. Active energy ray irradiating devices 39 and 40, a second active energy ray irradiating device 41 installed further downstream in the conveying direction, and a nip roll 42 for conveying are sequentially provided along the conveying direction.

  That is, the adhesive is applied to one side of the protective films 31 and 32 that are continuously drawn out from the state wound in a roll shape by the adhesive application devices 33 and 34. Then, the protective films 31 and 32 are superimposed on both surfaces of the polarizer 35 continuously drawn out in the same manner as the protective films 31 and 32 by the nip roll 36 via an adhesive, thereby forming a laminate 37. In the process of transporting the laminated body 37 in close contact with the outer peripheral surface of the roll 38, the active energy rays are irradiated from the first active energy ray irradiating devices 39, 40 toward the outer peripheral surface of the roll 38 to polymerize the adhesive. Harden. In addition, the 2nd active energy ray irradiation apparatus 41 arrange | positioned in a conveyance direction downstream is an apparatus for superposing | polymerizing and hardening an adhesive agent, and can be abbreviate | omitted as needed.

  Although the coating method of the adhesive agent to the protective films 31 and 32 is not specifically limited, For example, various coating systems, such as a doctor blade, a wire bar, a die coater, a comma coater, a gravure coater, can be utilized. Among these, in consideration of the thin film coating, the degree of freedom of the pass line, the correspondence to the width, etc., gravure rolls are preferable as the adhesive coating devices 33 and 34.

  When the adhesive is applied using the gravure roll as the adhesive coating devices 33 and 34, the thickness of the adhesive layer is adjusted by the draw ratio which is the speed ratio of the gravure roll to the line speed. The line speed of the protective films 31 and 32 is 15 to 50 m / min, the gravure roll is rotated in the direction opposite to the conveying direction of the protective films 31 and 32, and the speed of the gravure roll is 5 to 500 m / min (draw ratio 1 to 1 10), the coating thickness of the adhesive layer is adjusted to about 1 to 10 μm.

The roll 38 forms a convex curved surface having a mirror-finished outer peripheral surface. The roll 38 is conveyed while the laminate 37 is in close contact with the surface, and the adhesive is polymerized and cured by the active energy ray irradiation devices 39 and 40 in the process. . The diameter of the roll 38 is not particularly limited when the adhesive is polymerized and cured and the laminated body 37 is sufficiently adhered, but the active energy rays are applied while the laminated body 37 with the adhesive layer being uncured passes through the roll 38. Is preferably irradiated at 30 mJ / cm ² in terms of the cumulative amount of ultraviolet light. The roll 38 may be driven or rotated in accordance with the line movement of the laminated body 37, or may be fixed so that the laminated body 37 slides on the surface. Further, the roll 38 may act as a cooling roll in order to make it difficult for heat to be applied to the laminate 37 at the time of polymerization and curing by irradiation with active energy rays. In this case, the surface temperature of the cooling roll is preferably 20 to 25 ° C.

When polymerization curing is performed by irradiation with active energy rays, the light source used is not particularly limited, but has a light emission distribution at a wavelength of 400 nm or less, for example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a chemical lamp, a black light. A lamp, a microwave excitation mercury lamp, a metal halide lamp, or the like can be used. The light irradiation intensity to the epoxy resin composition is determined for each target composition and is not particularly limited, but the irradiation intensity in the wavelength region effective for activation of the initiator is 0.1 to It is preferably 100 mJ / cm ² . When the light irradiation intensity in the resin composition is less than 0.1 mJ / cm ^2, too long reaction time exceeds 100 mJ / cm ^2, the polymerization time of heat generation of the heat and compositions radiated from the lamp In addition, yellowing of the epoxy resin composition and deterioration of the polarizer may occur.

The irradiation time of the active energy ray to the composition is controlled for each composition to be cured and is not particularly limited, but the integrated light amount expressed as the product of the irradiation intensity and the irradiation time is 10 to 5, It is preferably set to be 000 mJ / cm ² . When the integrated light amount to the epoxy resin composition is less than 10 mJ / cm ² , the generation of active species derived from the initiator is not sufficient, and the resulting protective film may be insufficiently cured, If the integrated light quantity exceeds 5,000 mJ / cm ² , the irradiation time becomes very long, which is disadvantageous for improving productivity.

When ultraviolet rays are used as active energy rays, the line speed of the laminate 37 is not particularly limited, and the longitudinal direction (conveying direction) is under a tension of 100 to 800 N, and the irradiation intensity is at least 30 mJ / cm ² and the irradiation time is at least. It is preferable to irradiate the laminated body 37 with active energy rays under a condition of 0.3 seconds or longer. In addition, when the accumulated amount of light is insufficient due to the irradiation of the active energy rays by the active energy ray devices 39 and 40, the second active energy ray device 41 is supplementarily provided, and the active energy rays are additionally irradiated to laminate 33. The polymerization of the adhesive may be completed.

  The polarizing plate thus obtained has a reverse curl and wave curl as compared with the conventional case where the plate is passed under the active energy ray device horizontally with a predetermined tension (see FIG. 3). Since generation | occurrence | production is suppressed, when sticking to a liquid crystal cell, a bubble does not remain on an adhesion surface, Therefore Therefore, generation | occurrence | production of the defect of a liquid crystal panel can be reduced.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to the following examples.

  A 75 μm-thick amorphous polyolefin resin film “ZEONOR” (manufactured by Zeon Corporation) and a 80 μm-thick triacetyl cellulose film “KC8UX2MW” (manufactured by Konica Minolta) were prepared. Micro chamber doctor (manufactured by Fuji Machinery Co., Ltd.) which is an adhesive coating device with an epoxy resin composition “KRX492-30” (manufactured by ADEKA) as an adhesive on each side of an amorphous polyolefin resin film and a triacetyl cellulose film Was used for coating. The line speed of the laminate was 11 m / min, the gravure roll was rotated in the direction opposite to the conveying direction of the laminate, and the gravure roll speed was 22 m / min, so that the thickness of the adhesive layer was about 2 μm.

  Next, the amorphous polyolefin resin film and the triacetyl cellulose film were overlapped by nip rolls on both surfaces of a polyvinyl alcohol film on which iodine having a thickness of 25 μm was adsorbed and oriented via the epoxy resin composition.

The triacetyl of the polarizing plate is irradiated with ultraviolet rays from two EHAN1700NAL high-pressure mercury lamps, which are ultraviolet lamps provided in an ultraviolet irradiation device (manufactured by GS-YUSASA) under a tension of 600 N in the longitudinal direction. The surface on which the cellulose film was laminated was passed at a line speed of 11 m / min while being in close contact with the outer peripheral surface of the cooling roll at 23 ° C. At that time, the integrated light quantity of ultraviolet rays was 110 (mJ / cm ² ). The integrated light quantity of ultraviolet rays was measured based on irradiation in the UVB region having a wavelength range of 280 to 320 nm. Then, after cutting the laminated body whose width direction is 1330 mm at 600 mm in the longitudinal direction, the degree of wave curl was evaluated by the following method.

  That is, as shown in FIG. 2 (A), the wave number, wavelength, and amplitude values of the polarizing plate 50 with the surface on which the triacetyl cellulose film was bonded down were measured. The wave number is the number of wave peaks lined up in the width direction of the polarizing plate 50. As shown in FIG. Further, as shown in FIG. 6A, the amplitude 52 is obtained by measuring the lengths of the peaks and valleys at the respective positions a to e where the polarizing plate 50 is equally divided into 5 in the width direction, and taking the half value thereof. . The measurement results are shown in Table 1.

A polarizing plate was obtained in the same manner as in Example 1 except that the cumulative amount of ultraviolet light was 143 (mJ / cm ² ). The results are shown in Table 1.

[Comparative Example 1]
A laminate 60 in which an amorphous polyolefin resin film and a triacetyl cellulose film are laminated on both surfaces of a polyvinyl alcohol film by using an epoxy resin composition “KRX492-32” (manufactured by ADEKA) as an adhesive. As shown in FIG. 3, the ultraviolet light irradiated from one LH10-60UV electrodeless lamp, which is an ultraviolet lamp provided in the ultraviolet irradiation device 61 (manufactured by Fusion), is brought into close contact with the roller under a tension of 600 N. Without passing through, the polymer was cured by passing it in the horizontal direction at a line speed of 11 m / min. In this case, the cumulative amount of ultraviolet light was 119 (mJ / cm ² ). Other than that was carried out similarly to Example 1, and obtained the polarizing plate. The results are shown in Table 1.

[Comparative Example 2]
The same procedure as in Comparative Example 1 was performed except that the accumulated light amount of ultraviolet rays was 27 (mJ / cm ² ) polarized. The results are shown in Table 1.

  As shown in Table 1, both the polarizing plates of Comparative Example 1 and Comparative Example 2 have wave curls, and the polarizing plate of Comparative Example 1 having a larger cumulative amount of ultraviolet light than that of Comparative Example 2 has stronger wave curls. It was. On the other hand, the wave number of the polarizing plate obtained in Example 1 and Example 2 is 0, and it can be seen that the occurrence of reverse curl and wave curl is suppressed. In Example 1 and Example 2, the obtained film was cut into a 20 cm × 30 cm rectangle and placed on a flat plate to check the warping situation (curl) at the four corners, but no curl was seen. .

It is a schematic side view which shows one Embodiment of the manufacturing apparatus of the polarizing plate concerning this invention. (A), (B) is a schematic explanatory drawing which shows the evaluation method of the wave curl which arose in the polarizing plate. It is explanatory drawing which shows the polymerization hardening method of the adhesive agent by irradiation of the active energy ray in the comparative examples 1 and 2. FIG. FIG. 6 is an explanatory view illustrating a structure in which a linearly polarizing film that is a kind of polarizing plate is laminated on a liquid crystal cell. It is explanatory drawing which illustrates the structure of a polarizing plate.

Explanation of symbols

30: Polarizing plate manufacturing apparatus 31, 32: Protective film 33, 34: Adhesive coating apparatus 35: Polarizer 36: Nip roll 37: Laminate 38: Roll 39, 40, 41: Active energy ray irradiation apparatus 42: Conveyance Nip roll 50: Polarizing plate 51: Wavelength 52: Amplitude 60: Laminate 61: Ultraviolet irradiation device

Claims (6)

  A method of manufacturing a polarizing plate in which a protective film is laminated and bonded to one or both sides of a polarizer, and the polarizer and the protective film are overlapped with an adhesive to obtain a laminated body. A method for producing a polarizing plate, characterized in that the adhesive is polymerized and cured while the laminate is in close contact with a convex curved surface formed in an arc shape along a longitudinal direction.   The manufacturing method of the polarizing plate of Claim 1 whose said convex curved surface is an outer peripheral surface of a roll. The polarizer is a uniaxially stretched polyvinyl alcohol film in which iodine or dichroic dye is adsorbed and oriented, one of the protective films is an amorphous polyolefin resin film, and the other is a triacetylcellulose film. Item 3. The method for producing a polarizing plate according to Item 1 or 2.   The manufacturing method of the polarizing plate in any one of Claims 1-3 which irradiates an active energy ray to the laminated body closely_contact | adhered to the said convex curved surface, and carries out polymerization hardening.   Means for applying an adhesive on one side of the protective film or both sides of the polarizer, means for overlaying the protective film on one side or both sides of the polarizer via an adhesive layer, and means for polymerizing and curing the adhesive A polarizing plate manufacturing apparatus comprising: a roll for transporting the polarizer with the protective film superposed on the outer peripheral surface while the means for polymerizing and curing the adhesive is adhered to the outer peripheral surface; and toward the outer peripheral surface of the roll An active energy ray irradiating device for irradiating active energy rays.   The manufacturing apparatus of the polarizing plate of Claim 5 whose said active energy ray irradiation apparatus is an ultraviolet irradiation device.

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