CN106199810B - Manufacturing method of polarizing plate - Google Patents

Abstract

The present invention relates to a method for producing a polarizing plate in which protective films (31, 32) are laminated on both sides of a polarizing plate (35) and adhered respectively. The laminated body (37) is obtained by superimposing, and then the above-mentioned laminated body (37) is adhered to a convex curved surface formed in an arc shape, preferably the outer surface of the roller (38), along the conveying direction of the laminated body (37). , and simultaneously irradiate the active energy ray from the active energy ray irradiation device (39, 40) to polymerize and solidify the adhesive.

Description

Manufacturing method of polarizing plate

This application is a divisional application of the application number 200810191091.6 and the invention title is "Manufacturing Method of Polarizing Plate" filed by the applicant on November 24, 2008.

technical field

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

Background technique

A polarizing plate is practical as one of the optical components constituting a liquid crystal display device. FIG. 4 shows a structure in which a linear polarizing film, which 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 linear polarizing film 12 is bonded and laminated with an adhesive layer 11, thereby constituting a liquid crystal display panel.

The polarizing plate is generally used in a liquid crystal display device in a state where protective films are laminated on both surfaces of the polarizing plate. That is, as shown in FIG. 5 , in a normal polarizing plate 20, protective films 22 and 23 are laminated on both sides of the polarizing plate 21 via adhesive layers 24 and 25 (Japanese Patent Laid-Open No. 2004-245925, Japanese Patent Laid-Open Bulletin No. 173216).

However, in the polarizing plate produced as described above, the side attached to the liquid crystal cell may be curled into a depression (hereinafter, referred to as "reverse curl"), and the entire polarizing plate may be wavy (hereinafter referred to as "reverse curl"). wavy curl"). Such reverse curling and wavy curling are likely to cause air bubbles to remain on the bonding surface when the polarizing plate is bonded to the liquid crystal cell, which causes the liquid crystal panel to be rejected. Therefore, it is desirable that the polarizing plate does not generate reverse curling and wavy curling, and even if curling does not occur, it is desired that the polarizing plate curls to form protrusions on the side attached to the liquid crystal cell (hereinafter referred to as "positive curling").

SUMMARY OF THE INVENTION

The objective of this invention is to provide the manufacturing method and manufacturing apparatus of the polarizing plate which suppress reverse curl and wave curl.

The inventors of the present invention have conducted many intensive studies to achieve the above-mentioned object, and as a result found that the occurrence of reverse curling and wavy curling can be suppressed by polymerizing and curing the adhesive in a state where the following laminate is bent in a forward curling manner, Since the completion of the present invention, the laminate is formed by laminating a protective film on one side or both sides of a polarizing plate via an adhesive.

That is, a method for producing a polarizing plate of the present invention, wherein the polarizing plate is a polarizing plate in which a protective film is laminated on one side or both sides of the polarizing plate respectively, wherein the polarizing plate and the protective film are passed through The adhesives are superimposed to obtain a laminate, and then the adhesive is polymerized and cured while adhering the laminate to a convex curved surface formed in an arc shape along the longitudinal direction (conveying direction) of the laminate. As the above-mentioned convex curved surface, for example, the outer peripheral surface of a roll can be used.

Examples of the polarizer include polyvinyl alcohol films in which uniaxially stretched iodine or dichroic dyes are adsorbed and oriented, and examples of the protective films include amorphous polyolefin-based resin films. The other side of the film includes a triacetyl cellulose film, but it is not limited thereto.

It is preferable to irradiate an active energy ray to the laminated body adhered to the above-mentioned convex curved surface to polymerize and cure it, and it is also possible to heat it to polymerize and cure it.

In addition, the polarizing plate manufacturing apparatus of the present invention has a mechanism for applying an adhesive to one side of the protective film or both sides of the polarizer; a mechanism for superimposing the protective film on both sides of the polarizer via an adhesive layer; and a mechanism for polymerizing and curing the adhesive The mechanism, wherein, the mechanism for polymerizing and curing the adhesive comprises: the polarizer after overlapping the protective film is adhered to the outer peripheral surface and conveyed at the same time to the roller, and the outer peripheral surface of the roller is irradiated with active energy rays of active energy rays Line irradiation device.

According to the present invention, the laminated body formed by superimposing the polarizing plate and the protective film through the adhesive agent is formed into an arc-shaped convex surface along the longitudinal direction (transportation direction) of the laminated body adhered to the laminated body, and active energy rays are irradiated at the same time. The adhesive is polymerized and cured, and thus, when the polarizing plate is bonded to the liquid crystal cell, the occurrence of reverse curling and wavy curling can be suppressed, and the generation of reverse curling and wavy curling causes air bubbles to remain on the bonding surface and cause the liquid crystal panel to occur. cause of deterioration.

Description of drawings

FIG. 1 is a schematic side view showing an embodiment of an apparatus for producing a polarizing plate of the present invention.

Fig. 2(A)(B) is an explanatory schematic diagram showing an evaluation method of wavy generated on a polarizing plate.

3 is an explanatory diagram showing a method of polymerizing and curing the adhesive by irradiation of active energy rays in Comparative Examples 1 and 2. FIG.

FIG. 4 is an explanatory diagram illustrating a structure in which a linear polarizing film, which is one type of polarizing plate, is laminated on a liquid crystal cell.

FIG. 5 is an explanatory diagram illustrating the structure of a polarizing plate.

Symbol Description

30: Manufacturing device of polarizing plate

31, 32: Protective film

33, 34: Adhesive coating device

35: Polarizer

36: Pinch Roller

37: Laminate

38: Roller

39, 40, 41: Active energy ray irradiation device

42: Pinch roller for conveying

50: Polarizing plate

51: wavelength

52: Amplitude

60: Laminate

61: Ultraviolet irradiation device

Detailed ways

Hereinafter, an embodiment of the present invention will be described. The polarizing plate in this embodiment is formed of a polarizing plate and a protective film laminated on both surfaces via an adhesive. As the polarizing plate, conventionally used in the production of polarizing plates (for example, the polarizing plate described in Japanese Unexamined Patent Application Publication No. 2004-245925) can be used, and there can be used iodine commonly used for uniaxially stretched polyvinyl alcohol. Or a thin film formed by dyeing with a dichroic dye followed by boric acid treatment. The thickness of the polarizer is preferably in the range of 5 to 50 μm.

The protective films laminated on both sides of the polarizing plate may be of the same type or different types. When using different types of protective films, use an amorphous polyolefin resin film, polyester resin film, acrylic resin film, polycarbonate resin film, polysulfone resin film, alicyclic polyimide resin film for one of the protective films Resin film with low moisture permeability. Amorphous polyolefin resin films include, for example, "TOPAS" manufactured by German Ticona Corporation, "ARTON" manufactured by JSR (Co., Ltd.), "Zeonor" and "ゼオネックス" manufactured by ZEON (Japan) Corporation. ZEONEX)", "Apel (APPEL)" manufactured by Mitsui Chemicals Co., Ltd., etc. As the other protective film, acetyl cellulose ester-based films such as triacetyl cellulose films and diacetyl cellulose films are used in addition to the above-mentioned films. Triacetyl cellulose films include, for example, "FUJITAC TD80", "FUJITAC TD80UF" and "FUJITAC TD80UZ" manufactured by FUJIFILM Corporation, "KC8UX2M" and "KC8UY" manufactured by UNIKA Corporation.

Before bonding the protective film to the polarizer, the bonding surface may be subjected to an easy-adhesion treatment such as alkali treatment, corona discharge treatment, primer treatment, and anchor coating treatment. Moreover, you may have various processing layers, such as a hard-coat layer, an antireflection layer, and an antiglare layer, on the surface on the opposite side of the surface to which the polarizer is bonded 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.

From the viewpoints of weather resistance, refractive index, cationic polymerizability, etc., for the adhesive, for example, as described in JP2004-245925A, a ring having no aromatic ring in the molecule can be used in the adhesive. Oxygen resin is not limited to this, and various adhesives conventionally used in the production of polarizing plates can be used. As said epoxy resin, hydrogenated epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin, etc. are used, for example. Polymerization initiators such as photocationic polymerization initiators for polymerization by active energy ray irradiation, thermal cationic polymerization initiators for polymerization by heating, and other additives (activators, etc.) can be added to the epoxy resin component to prepare Adhesive composition for coating.

The polarizing plate production apparatus and production method of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic diagram showing an example of an apparatus for producing a polarizing plate of the present invention.

In the polarizing plate manufacturing apparatus 30 shown in FIG. 1, there are sequentially provided along the conveying direction: adhesive coating devices 33, 34 for coating adhesive on one side of the protective films 31, 32; for overlapping the protective films 31, 32 32. A nip roll 36 for the polarizer 35; a roll 38 for adhering the laminate 37 on which the protective films 31, 32 and the polarizer 35 are adhered; The first active energy ray irradiation devices 39 and 40 ; the second active energy ray irradiation device 41 provided on the downstream side in the above-mentioned conveyance direction;

That is, the protective films 31 and 32 continuously drawn out from the state of being wound in a roll shape are coated with an adhesive on one side thereof by the adhesive coating apparatuses 33 and 34 . Like the above-mentioned protective films 31 and 32 , the protective films 31 and 32 are superimposed on both sides of the continuously drawn polarizer 35 with the nip roll 36 via an adhesive, respectively, thereby forming a laminated body 37 . In the process of conveying the laminated body 37 while adhering to the outer peripheral surface of the roller 38 , the outer peripheral surface of the roller 38 is irradiated with active energy rays from the first active energy ray irradiation devices 39 and 40 to polymerize and cure the adhesive. Furthermore, the second active energy ray irradiation device 41 arranged on the downstream side in the conveying direction is a device for completely polymerizing and curing the adhesive, and can be omitted as necessary.

The method of applying the adhesive to the protective films 31 and 32 is not particularly limited, and for example, a doctor blade, a wire bar, a die coater, a comma coater, or a gravure can be used. Various coating methods such as printing coating. Among them, in the film coating, the adhesive coating devices 33 and 34 are preferably gravure rolls in consideration of the degree of freedom with respect to the pass line, the correspondence with the width, and the like.

When the gravure roll is used as the adhesive coating device 33, 34 for adhesive coating, the thickness of the adhesive layer is adjusted according to the ratio of the speed of the gravure roll to the linear speed, that is, the draw ratio. The line speed of the protective films 31 and 32 is set to 15 to 50 m/min, the gravure roll is rotated in the opposite direction of the conveying direction of the protective films 31 and 32, and the speed of the gravure roll is set to 5 to 500 m/min. (draw ratio 1 to 10), thereby adjusting the coating thickness of the adhesive layer to about 1 to 10 μm.

The outer peripheral surface of the roller 38 has a mirror-finished convex curved surface, and the laminated body 37 is adhered and conveyed on this 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 roller 38 is not particularly limited as long as the laminated body 37 is sufficiently adhered when the adhesive is polymerized and cured. ² cumulative ultraviolet rays are irradiated with active energy rays. The roller 38 may be driven to rotate following the linear motion of the laminated body 37, or may be fixed so that the laminated body 37 slides on the surface thereof. In addition, the roll 38 may function as a cooling roll so as not to easily add heat to the laminated body 37 during polymerization and solidification by irradiation with active energy rays. The surface temperature of the cooling roll at this time is preferably 20 to 25°C.

When polymerizing and curing by irradiation with active energy rays, the light source used is not particularly limited, and those having a light emission distribution with a wavelength of 400 nm or less can be used, for example, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, chemical lamps, ultraviolet lamps, Microwave excitation mercury lamps, metal halide lamps, etc. The light irradiation intensity to the epoxy resin composition is not particularly limited depending on the intended composition, but the irradiation intensity in the wavelength region effective for activation of the initiator is preferably 0.1 to 100 mJ/cm ² . If the light irradiation intensity to the resin composition is less than 0.1 mJ/cm ² , the reaction time will be too long, and if it exceeds 100 mJ/cm ² , the epoxy resin composition may be generated due to the heat radiated from the lamp and the heat generated during polymerization of the composition. yellowing of objects and deterioration of polarizers.

The time for irradiating the composition with active energy rays is controlled for each polymerized composition and is not particularly limited, but is preferably set so that the cumulative light amount expressed as the product of irradiation intensity and irradiation time is 10 to 5000 mJ/cm ² . For example, if the cumulative light amount to the epoxy resin composition is less than 10 mJ/cm ² , the generation of activating species from the initiator may be insufficient, and the resulting protective film may be insufficiently cured. On the other hand, if the cumulative light amount exceeds 10 mJ/cm 2 At 5000 mJ/cm ² , the irradiation time is very long, which is disadvantageous for improving productivity.

When ultraviolet rays are used as the active energy rays, the linear speed of the laminate 37 is not particularly limited, but is preferably a tension of 100 to 800 N in the longitudinal direction (conveying direction), an irradiation intensity of at least 30 mJ/cm ² or more, and a time of 0.3 seconds or more. The laminate 37 is irradiated with active energy rays under the conditions of the irradiation time. In addition, when the cumulative light intensity of the active energy ray irradiation by the active energy ray devices 39 and 40 is insufficient, an auxiliary second active energy ray device 41 may be provided to additionally irradiate the active energy ray to complete the polymerization of the adhesive of the laminate 37 .

The polarizing plate thus obtained suppresses the occurrence of reverse curling and wavy curling, as compared with the conventional case in which the polarizing plate is horizontally transported and passed under the active energy ray device with a predetermined tension (see FIG. 3 ). When sticking to a liquid crystal cell, air bubbles do not remain on the adhesive surface, and the occurrence of defects in the liquid crystal panel can be reduced.

Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to the following Example.

Example 1

An amorphous polyolefin resin film [ZEONOR] (manufactured by Nippon Zeon Co., Ltd.) with a thickness of 75 μm, and a triacetyl cellulose film [KC8U2MW] (manufactured by Nippon Konica Minolta Co., Ltd.) with a thickness of 80 μm were prepared. An epoxy resin composition [KRX492] as an adhesive was applied to one side of each of the amorphous polyolefin resin film and the triacetyl cellulose film using a microchamber coater (manufactured by Fuji Machine Co., Ltd.) as an adhesive coating device. -30] (manufactured by ADEKA Corporation). By setting the linear speed of the laminate to 11 m/min, rotating the gravure roll in the opposite direction to the conveying direction of the laminate, and setting the speed of the gravure roll to 22 m/min, the thickness of the adhesive layer was approximately is 2 μm.

Next, on both sides of the polyvinyl alcohol-based film in which iodine having a thickness of 25 μm was adsorbed and oriented, the above-mentioned amorphous polyolefin resin film and the above-mentioned triacetyl cellulose film were separated by a nip roll through the above-mentioned epoxy resin composition. coincide.

The polarizing plate was passed through at a linear speed of 11 m/min while adhering the surface on which the triacetyl cellulose film of the polarizing plate was laminated to the outer peripheral surface of a cooling roll at 23°C under a tension of 600 N in the longitudinal direction. Among the ultraviolet rays irradiated by the EHAN1700NAL high-pressure mercury lamp 2, which is an ultraviolet lamp provided in an ultraviolet irradiation device (manufactured by GS-YUASA). The cumulative amount of ultraviolet rays at this time was 110 (mJ/cm ² ). The cumulative amount of ultraviolet rays was measured based on irradiation in the UVB region of the wavelength range of 280 to 320 nm. Then, the laminated body whose width direction is 1330 mm was cut|disconnected by 600 mm in the longitudinal direction, and the degree of wave curl was evaluated by the following method.

That is, as shown in FIG. 2 , the wave number, wavelength, and amplitude of the downward-facing polarizing plate 50 to which the triacetyl cellulose film was bonded were measured, respectively. The wave number is the number of wave crests aligned in the width direction of the polarizing plate 50 , and as shown in FIG. In addition, as shown in FIG. (A), the amplitude 52 is measured as the length between the peaks of the peaks and the troughs at positions a to e dividing the polarizing plate 50 into 5 equal parts in the width direction, and is half the length. The above measurement results are shown in FIG. 1 .

Example 2

A polarizing plate was obtained in the same manner as in Example 1, except that the cumulative amount of ultraviolet rays 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 sides of a polyvinyl alcohol film via an epoxy resin composition [KRX492-32] (manufactured by ADEKA) as an adhesive, such as As shown in FIG. 3 , under a tension of 600 N, without adhering to the roller, the ultraviolet rays provided by the ultraviolet irradiation device 61 (FUSION: manufactured by Fuji-Jon Co., Ltd.) were passed in the horizontal direction at a linear speed of 11 m/min. The lamp is the ultraviolet ray irradiated by the LH10-60UV electrodeless lamp 1 to polymerize and cure it. The cumulative light amount of the ultraviolet rays at this time was 119 (mJ/cm ² ). Moreover, it carried out similarly to Example 1, and obtained the polarizing plate. The results are shown in Figure 1 .

Comparative Example 2

A polarizing plate was obtained in the same manner as in Comparative Example 1, except that the cumulative amount of ultraviolet rays was 27 (mJ/cm ² ). The results are shown in Table 1.

Table 1

As shown in Table 1, any of the polarizing plates of Comparative Example 1 and Comparative Example 2 generated wavy, and compared with Comparative Example 2, the polarizing plate of Comparative Example 1, which had a large amount of accumulated ultraviolet light, generated strong wavy. On the other hand, the wave number of the polarizing plate obtained in Example 1 and Example 2 was 0, and the generation|occurence|production of reverse curl and wavy curl was suppressed. Furthermore, in Example 1 and Example 2, the obtained film was cut into a rectangle of 20 cm x 30 cm, set on a flat plate, and the bending state (curling) of the four corners was checked. As a result, no curl was observed at all.

Claims (11)

1. A method for manufacturing a liquid crystal display panel in which the occurrence of wavy curling is suppressed, comprising a method for manufacturing a polarizing plate in which protective films are laminated and bonded to both surfaces of a polarizing plate,

subjecting the surface of the protective film to which the polarizing plate is bonded to an easy adhesion treatment, and superposing the polarizing plate and the protective film with an adhesive therebetween to obtain a laminate, and then adhering the laminate to a convex curved surface formed in an arc shape along the longitudinal direction of the laminate, and curling the laminate on the side of a liquid crystal cell bonded to a liquid crystal display panel to form a protrusion, while irradiating the laminate with an active energy ray to polymerize and cure the adhesive, and conveying the laminate with a conveying nip roller,

the irradiation intensity of the active energy ray is 0.1mJ/cm²～100mJ/cm²。

2. The method for manufacturing a liquid crystal display panel according to claim 1,

the convex curved surface is the outer peripheral surface of the roller.

3. The method for manufacturing a liquid crystal display panel according to claim 2,

the surface temperature of the roller is 20-25 ℃.

4. The method for manufacturing a liquid crystal display panel according to claim 2,

the laminate with the adhesive in an uncured state was passed through the roller at 30mJ/cm²Ultraviolet ray cumulative light quantity irradiation activity ofAn energy line.

5. The method of manufacturing a liquid crystal display panel according to claim 1 or 2,

the polarizer is a polyvinyl alcohol film which is uniaxially stretched and in which iodine or a dichroic dye is adsorbed and oriented, and one of the protective films is an amorphous polyolefin resin film and the other is a triacetyl cellulose film.

6. The method for manufacturing a liquid crystal display panel according to claim 1,

the thickness of the adhesive is 1-10 μm.

7. The method for manufacturing a liquid crystal display panel according to claim 1,

and irradiating the adhesive with active energy rays on the downstream side of the convex curved surface in the conveying direction to completely polymerize and cure the adhesive.

8. An apparatus for manufacturing a liquid crystal display panel having a polarizing plate, in which the occurrence of wavy curling is suppressed, includes:

a mechanism for performing an easy adhesion treatment on the surface of the protective film, which is bonded to the polarizing plate;

a mechanism for coating adhesive on one side of the protective film or both sides of the polarizing plate;

a mechanism for superposing the protective film on both sides of the polarizing plate via an adhesive; and

a mechanism for polymerizing and curing the adhesive, wherein,

the polarizing plate manufacturing apparatus further includes a conveying nip roller for conveying the polarizing plate on the downstream side in the conveying direction of the mechanism for polymerizing and curing the adhesive,

the mechanism for polymerizing and curing the adhesive comprises: a roller for curling the polarizing plate on which the protective film is laminated on one side of the liquid crystal cell attached to the liquid crystal display panel to form a protrusion and conveying the polarizing plate while adhering to the outer peripheral surface of the roller, and an active energy ray irradiation device for irradiating the outer peripheral surface of the roller with active energy rays,

the irradiation intensity of the active energy ray is 0.1mJ/cm²～100mJ/cm²。

9. The manufacturing apparatus of a liquid crystal display panel according to claim 8, wherein the active energy ray irradiation apparatus is an ultraviolet irradiation apparatus.

10. The manufacturing apparatus of liquid crystal display panel according to claim 8,

the adhesive curing apparatus is provided with a 2 nd active energy ray irradiation device which is arranged on the downstream side of the active energy ray irradiation device in the conveying direction and is used for completely curing the adhesive.

11. The manufacturing apparatus of liquid crystal display panel according to claim 8,

the surface temperature of the roller is 20-25 ℃.

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