JP2009265646A - Manufacturing apparatus and method of polarizing plate, polarizing plate obtained by the manufacturing method, and optical laminated body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing apparatus and method of a polarizing plate, capable of improving production efficiency without enlarging the apparatus, and a polarizing plate with good appearance, which is reduced in curling in a sticking face of a film by suppressing end swelling and generation of bubble on the sticking face. <P>SOLUTION: In the manufacturing apparatus of a polarizing plate for sticking a polarizing film 2 and a protective film 8 one of which is a film wound in a roll shape and the other of which is a sheet film, the polarizing film 2 wound in the roll shape is delivered, an ultraviolet curing adhesive is applied to one surface of the polarizing film 2, the sheet protective film 8 is superposed on the adhesive-applied surface of the polarizing film 2, and the ultraviolet curing adhesive is cured by an ultraviolet irradiation device 11. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polarizing plate manufacturing apparatus and manufacturing method used for a liquid crystal display device, an image display device, and the like, and a polarizing plate and an optical laminate obtained by the manufacturing method.

  Generally, a polarizing plate is formed by bonding a protective film on one side or both sides of a polarizing film. As the protective film, a film having any of the functions of a retardation film, a brightness enhancement film, a viewing angle improvement film, and a transflective film may be used.

  By the way, the direction of the optical axis of the optical film in the liquid crystal display device or the like, that is, the direction of the absorption axis of the polarizing film or the direction of the slow axis of the retardation film greatly affects the display performance of the target liquid crystal display device or the like. Therefore, the optical film is cut out so as to be in the direction of the optical axis suitable for the target liquid crystal display device or the like. Then, the cut sheet film is bonded to the continuous film so that the optical axis is at a predetermined angle. For example, Patent Document 1 describes a method for producing a polarizing plate in which a protective film or a retardation film is bonded to one side of a roll-shaped polyvinyl alcohol polarizing film using an aqueous adhesive.

JP 2007-193333 A

  However, in the polarizing plate obtained by the method described in Patent Document 1, when the heat resistance acceleration test (so-called heat cycle test) in which heating and cooling are repeated and the heat resistance test in a high temperature environment for a long time are performed, the end portion rises. Or bubbles may occur on the bonding surface of the film, or curl may occur on the bonding surface. Furthermore, in the method for producing a polarizing plate described in Patent Document 1, a dryer for drying the aqueous adhesive is required, so that there is a problem that the apparatus is increased in size and costs are increased.

  A main object of the present invention is to provide a polarizing plate manufacturing apparatus and a manufacturing method of a polarizing plate using the same, in which the apparatus is not enlarged and the production efficiency is improved. In addition, another object of the present invention is to provide a polarizing plate having a good appearance, in which edge bulge and bubble generation are suppressed on the bonding surface of the film.

  The present inventors have intensively studied to solve the above problems. As a result, after applying an ultraviolet curable adhesive to a continuous roll-shaped film and laminating the single wafer film cut to a predetermined size so that the optical axis is at a predetermined angle, By irradiating ultraviolet rays to cure the ultraviolet curable adhesive, (i) a dryer is not required, so that the apparatus does not increase in size and can be produced continuously and efficiently, and (ii) The inventors found that a polarizing plate in which the edge bulge and the generation of bubbles on the bonding surface of the film and the occurrence of curling on the bonding surface were suppressed in the heat resistance acceleration test and the heat resistance test was obtained, and the present invention was completed. .

That is, the present invention relates to the following description.
(1) One is a continuous film wound in a roll shape, and the other is a polarizing plate manufacturing apparatus for laminating a polarizing film and a protective film, which are single-wafer films,
A means for feeding a continuous film wound in a roll shape, a means for applying an ultraviolet curable adhesive on one side of the drawn continuous film, and a sheet film superimposed on the adhesive application surface of the continuous film An apparatus for producing a polarizing plate, comprising: means; and ultraviolet irradiation means for curing the ultraviolet curable adhesive.
(2) After laminating the sheet-fed film and the surface protective film covering them on the adhesive-coated surface of the continuous film in this order, and curing the ultraviolet curable adhesive to bond the continuous film and the sheet-fed film The manufacturing apparatus according to (1), further comprising means for peeling and separating the surface protective film.
(3) The single-wafer film is placed on a protective film peeling adhesive tape that travels from a feeding roll toward a take-up roll, and is transported to an overlapping position with the continuous film. The manufacturing apparatus according to (1) or (2), wherein the sheet film is overlapped with the continuous film while the protective film is peeled off.
(4) One is a film wound in a roll shape, and the other is a method for producing a polarizing plate for laminating a polarizing film and a protective film, which is a single wafer film,
While continuously feeding a continuous film wound in a roll, an ultraviolet curable adhesive is applied to one side of the continuous film, and then a single-wafer film is superimposed on the adhesive application surface of the continuous film, A method for producing a polarizing plate, comprising: irradiating ultraviolet rays to cure the ultraviolet curable adhesive, and laminating and bonding a single wafer film to the continuous film.
(5) A polarizing plate obtained by the production method according to (4) above, wherein a protective film is bonded to at least one surface.
(6) The polarizing plate according to (5), wherein the protective film has a function of any one of a retardation film, a brightness enhancement film, a viewing angle improvement film, and a transflective film.
(7) An optical laminate comprising the polarizing plate according to (5) and at least one selected from a retardation film, a brightness enhancement film, a viewing angle improvement film, and a transflective film.

According to the method for producing a polarizing plate of the present invention, a continuous roll-shaped film and a single wafer film are continuously and efficiently bonded using an ultraviolet curable adhesive without using water or other solvents. Can be matched. Furthermore, a drying apparatus for evaporating the solvent is not required. Therefore, the entire manufacturing apparatus is not increased in size and the cost can be reduced.
The polarizing plate of the present invention can reduce edge bulge and bubble generation on the bonding surface of the film in the heat resistance acceleration test and the like, and curl generation on the bonding surface.

It is a schematic explanatory drawing which shows one Embodiment of the polarizing plate manufacturing apparatus concerning this invention.

  One embodiment of a polarizing plate manufacturing apparatus according to the present invention is shown in FIG. As shown in the figure, the polarizing plate manufacturing apparatus 1 includes a pair of take-up rolls 61 and 62 for continuously feeding out the polarizing film 2 wound in a roll shape. On one surface of the polarizing film 2, a release film 3 for protecting the surface of the polarizing film 2 is bonded in advance, and the release film 3 is separated by the first roll 4. The release film 3 is collected in a roll shape.

  The polarizing film 2 from which the release film 3 has been separated is sent to an adhesive application device 5 that applies an ultraviolet curable adhesive, and a predetermined amount of an ultraviolet curable adhesive is applied to one surface by an application roll 51, and a pair of adhesive films is applied. It is sent to the combined rolls 71 and 72.

  On the other hand, a sheet protection film 8 cut to a predetermined size (hereinafter also referred to as a sheet protection film 8) is conveyed to the bonding rolls 71 and 72. A protective film (not shown) is bonded to the bonding surface of the sheet protective film 8 to the polarizing film 2. Therefore, it is necessary to peel off the protective film prior to bonding of the single wafer protective film 8 and the polarizing film 2. Therefore, while the protective film peeling adhesive tape 9 is continuously run in the conveying direction of the sheet protective film 8 from the feed roll 91 wound in a roll shape toward the take-up roll 92, The protective film surface of the single wafer protective film 8 is placed on and bonded together. Reference numeral 10 denotes a suction cup type conveying device for sucking and holding the sheet protective films 8 one by one and sequentially placing and bonding them on the surface of the conveying film 9.

  The sheet protective film 8 bonded on the adhesive surface of the protective film peeling adhesive tape 9 is conveyed to the position where it is overlapped with the polarizing film 2, and the sheet is removed while peeling the protective film from the sheet protective film 8. The protective film 8 is configured to overlap the polarizing film 2. That is, the sheet protective film 8 is superimposed on the adhesive application surface of the polarizing film 2 by a pair of bonding rolls 71 and 72. At that time, the protective film peeling adhesive tape 9 is folded back in the direction opposite to the traveling direction of the sheet protective film 8 immediately before the bonding rolls 71 and 72, and the protective film is peeled off from the sheet protective film 8 at the folded portion. Therefore, only the sheet protective film 8 is superimposed on the adhesive application surface of the polarizing film 2 by the bonding rolls 71 and 72. As the protective film peeling pressure-sensitive adhesive tape 9, for example, a pressure-sensitive adhesive layer provided on the surface of a plastic film substrate can be used.

In the bonding rolls 71 and 72, the surface protective film 12 is further superimposed on the polarizing film 2 and the sheet protective film 8. The surface protective film 12 is a film wound in a roll shape, and is continuously drawn out and superimposed on the polarizing film 2 and the sheet protective film 8 by bonding rolls 71 and 72.
The surface protective film 12 is used to prevent the ultraviolet curable adhesive from protruding from the polarizing film 2 and the single wafer protective film 8 and contaminating the device. The surface protective film 12 is preferably one that does not hinder the curing of the ultraviolet curable adhesive by the subsequent ultraviolet irradiation, and examples thereof include plastic films such as transparent or translucent polyethylene and polyester resins.

  The sheet protective film 8, the polarizing film 2 and the surface protective film 12 which are overlapped by the bonding rolls 71 and 72 are conveyed toward the ultraviolet irradiation devices 11 and 11 by the take-up rolls 61 and 62.

  The ultraviolet irradiation devices 11 and 11 are provided above and below the conveyance path of the polarizing film 2 and the sheet protection film 8 and are configured to irradiate ultraviolet rays from above and below. Accordingly, even when either the polarizing film 2 or the sheet protective film 8 is made of a material that does not easily transmit ultraviolet rays, the ultraviolet curable adhesive is surely cured to firmly bond the polarizing film 2 and the sheet protective film 8. be able to.

  As the sheet protection film 8, the function as a retardation film, the function as a brightness enhancement film, the function as a reflection film, the function as a transflective film, the function as a diffusion film, the function as an optical compensation film, etc. A film having an optical function may be mentioned. In this case, for example, by laminating an optical functional film such as a retardation film, a brightness enhancement film, a reflection film, a transflective film, a diffusion film, an optical compensation film on the surface of the protective film, it has such a function. In addition, the protective film itself can be provided with such a function. Further, the protective film itself may have a plurality of functions such as a diffusion film having the function of a brightness enhancement film.

  For example, the above protective film is subjected to a stretching process described in Japanese Patent No. 2841377, Japanese Patent No. 3094113, etc., or a process described in Japanese Patent No. 3168850, etc. The function as can be provided. In addition, by forming micropores in the above protective film by a method as described in JP 2002-169025 A or JP 2003-29030 A, two or more layers having different central wavelengths of selective reflection are formed. By superimposing these cholesteric liquid crystal layers, a function as a brightness enhancement film can be imparted. By forming a metal thin film on the above protective film by vapor deposition or sputtering, a function as a reflective film or a transflective film can be imparted. By coating the protective film with a resin solution containing fine particles, a function as a diffusion film can be imparted. Moreover, the function as an optical compensation film can be provided by coating and aligning liquid crystalline compounds, such as a discotic liquid crystalline compound, on said protective film. In addition, using an appropriate adhesive, a brightness enhancement film such as a trade name: DBEF (manufactured by 3M Co., Ltd.), a trade name: a viewing angle improving film such as a WV film (manufactured by Fuji Photo Film Co., Ltd.), a trade name : Commercially available optical functional films such as retardation films such as Sumikalite (registered trademark) (Sumitomo Chemical Co., Ltd.) may be directly bonded to the polarizing film.

  After the bonding, the surface protection film 12 is wound up in a roll shape and separated from the polarizing film 2 and the sheet protection film 8. The bonded polarizing film 2 and the single wafer protective film 8 are cut into a predetermined size and used as an optical laminate.

  In the present invention, the ultraviolet curable adhesive for adhering the polarizing film 2 and the protective film 8 has a property of causing a photopolymerization reaction and curing when irradiated with ultraviolet rays. For example, when an ultraviolet curable adhesive is irradiated with ultraviolet rays having a wavelength of about 350 to 380 nm, the initial curing is started in several tens of seconds and cured with appropriate elasticity after several minutes. Such an ultraviolet curable adhesive is composed of a prepolymer, a monomer, a photopolymerization initiator (for example, a photocationic polymerization initiator), etc., and has little expansion with respect to heat and has a stable accuracy through a temperature cycle. Furthermore, since it has low shrinkage, it can be bonded with high accuracy, and since it has a low water absorption rate, it can maintain high quality even in environments with high humidity and high temperature. Examples of the ultraviolet curable adhesive include epoxy resin adhesives that do not contain an aromatic ring in the molecule, such as hydrogenated epoxy resins, alicyclic epoxy resins, and aliphatic epoxy resins.

  Such an ultraviolet curable adhesive does not substantially contain water or other solvent in its composition, so that no solvent remains between the polarizing film 2 and the protective film 8, and polarized light in the heat resistance acceleration test. A polarizing plate and an optical laminate having a good appearance can be obtained without the occurrence of bubbles on the edge of the plate and the bonding surface with the glass surface. The application amount of the ultraviolet curable adhesive is not particularly limited, and for example, the film thickness is 0.5 μm to 6 μm, preferably 1 μm to 4 μm. Further, the application of the ultraviolet curable adhesive is not particularly limited to the method and apparatus shown in FIG.

When curing is performed by irradiation with ultraviolet rays, the light source used has a light emission distribution at a wavelength of 100 nm to 400 nm. The irradiation intensity of ultraviolet rays 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 1 to 600 mW / cm ^2. preferable. If the irradiation intensity of ultraviolet rays is less than 1 mW / cm ² , the reaction time becomes too long, and if it exceeds 600 mW / cm ² , the polarizing film is deteriorated due to heat radiated from the lamp and heat generated during polymerization of the composition. It can happen.

The irradiation time of ultraviolet rays 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 1000 mJ / cm ^2. It is preferably set. When the integrated light quantity is less than 10 mJ / cm ² , the generation of active species derived from the initiator is not sufficient, and curing may be insufficient. On the other hand, when the integrated light quantity exceeds 1000 mJ / cm ² , Irradiation time becomes extremely long, which is disadvantageous in terms of productivity.

Although the conveyance speed of the laminated body of the polarizing film 2 and the protective film 8 at the time of irradiating an ultraviolet-ray is not specifically limited, The tension | tensile_strength of 50-500 N / m and the irradiation intensity | strength are 1-600 mW / cm < ² > and irradiation in a conveyance direction. It is preferable to irradiate the laminate with ultraviolet rays for 1 to 10 seconds.

  In the present embodiment, the polarizing film 2 is used as the continuous film and the protective film 8 is used as the sheet film. Conversely, the continuous film may be a protective film and the sheet film may be a polarizing film.

  Moreover, an optical laminated body is manufactured by bonding the polarizing plate obtained as described above and at least one selected from a retardation film, a brightness enhancement film, a viewing angle improvement film, and a transflective plate. can do.

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

Using the apparatus shown in FIG. 1, an ultraviolet curable adhesive (KRX492-25 manufactured by ADEKA) was applied to one side of a polyvinyl alcohol polarizing film having a thickness of 123 μm and a width of 400 mm using a coating apparatus. A single-phase retardation film (300 mm × 400 mm, thickness of 88 μm, manufactured by Sekisui Chemical Co., Ltd.) is superposed, and then irradiated with ultraviolet rays at an integrated light amount of 300 mJ / cm ² for 5 seconds by an ultraviolet irradiation device. The curable adhesive was cured to obtain a polarizing plate (irradiation ultraviolet wavelength: 365 nm, adhesive film thickness: 3 μm, transport tension: 100 N / m).

[Comparative Example 1]
A polarizing plate was prepared in the same manner as in Example 1 except that NS300MP (manufactured by Lintec Co., Ltd.) was used as the adhesive, and a single-phase retardation film was bonded to one side of the polarizing film. Went.

<Heat resistance promotion test>
The polarizing plate obtained in Example 1 and Comparative Example 1 was repeatedly heated and cooled at intervals of 30 minutes at 85 ° C. and −40 ° C. in a constant temperature bath, and this was repeated 350 cycles. The presence or absence of occurrence was observed. As a result, in the polarizing plate of Comparative Example 1, the generation of bubbles was recognized over the entire periphery, but in the polarizing plate of Example 1, almost no bubbles were recognized.

<Heat resistance test (film edge bulge)>
The polarizing plate obtained in Example 1 was held in an atmosphere at 85 ° C. for 250 hours, and then the rising of the edge of the film was observed with a confocal interference microscope (PL-μ2300 manufactured by SENSOFAR). As a result, the rising height was within 1 μm within the range of 500 μm from the end. In contrast, the rising height of the polarizing plate of Comparative Example 1 was 3 to 4 μm.

  The polarizing plate manufacturing apparatus and manufacturing method of the present invention, and the polarizing plate and optical laminate obtained by the manufacturing method have been described in detail above, but the present invention is not limited to these descriptions. In the range which does not impair the meaning of this, it can change or improve suitably.

DESCRIPTION OF SYMBOLS 1: Manufacturing apparatus of polarizing plate, 2: Polarizing film, 3: Release film, 5: Adhesive coating apparatus, 8: Sheet-fed protective film, 9: Conveyance film, 11: Ultraviolet irradiation apparatus, 12: Surface protective film

Claims (7)

One is a continuous film wound in a roll shape, and the other is a polarizing plate manufacturing apparatus for laminating a polarizing film and a protective film, which are single-wafer films,
A means for feeding out a continuous film wound in a roll shape, a means for applying an ultraviolet curable adhesive on one side of the drawn-out continuous film, and a sheet-fed film superimposed on the adhesive-coated surface of the continuous film An apparatus for manufacturing a polarizing plate, comprising: means; and ultraviolet irradiation means for curing the ultraviolet curable adhesive.   The sheet protection film and the surface protection film covering them are superposed in this order on the adhesive-coated surface of the continuous film, and the surface protection is performed after the UV curable adhesive is cured to adhere the continuous film and the sheet film. The manufacturing apparatus according to claim 1, further comprising means for separating and separating the film.   The single-wafer film is placed on a protective film peeling adhesive tape that travels from a feed roll toward a take-up roll, and is transported to the overlapping position with the continuous film. The manufacturing apparatus of Claim 1 or 2 comprised so that a single wafer film may be piled up with the said continuous film, peeling. One is a film wound in a roll shape, and the other is a method for producing a polarizing plate for laminating a polarizing film and a protective film, which are single-wafer films,
While continuously feeding a continuous film wound in a roll, an ultraviolet curable adhesive is applied to one side of the continuous film, and then a sheet film is overlaid on the adhesive application surface of the continuous film. A method for producing a polarizing plate, comprising: irradiating ultraviolet rays to cure the ultraviolet curable adhesive, and laminating and bonding a single wafer film to the continuous film.   A polarizing plate obtained by the production method according to claim 4, wherein a protective film is bonded to at least one surface. The polarizing plate according to claim 5, wherein the protective film has a function of any one of a retardation film, a brightness enhancement film, a viewing angle improvement film, and a transflective film.   An optical laminate comprising the polarizing plate according to claim 5 and at least one selected from a retardation film, a brightness enhancement film, a viewing angle improvement film, and a transflective film.

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