KR20090104702A - Apparatus of manufacturing polarization plate and method thereof, and polarization plate and optical film obtained by the method - Google Patents

Abstract

PURPOSE: An apparatus for manufacturing polarizing plates, method for the same, and polarizing plates and optical films obtained by the method are provided using UV-curable adhesives without the use of water or other solvents. CONSTITUTION: An apparatus(1) for manufacturing polarizing plates comprises the following units. An unwinding unit unwinds a continuously rolled film. A coating unit(5) coats an UV-curable adhesive on one side of the unrolled film. An overlapping unit makes the coated film overlapped. An UV irradiating unit irradiates ultraviolet rays in order to harden the UV-curable adhesive.

Description

A manufacturing apparatus and manufacturing method of a polarizing plate, a polarizing plate and an optical laminated body obtained by this manufacturing method TECHNICAL FIELD

This invention relates to the manufacturing apparatus and manufacturing method of the polarizing plate used for a liquid crystal display device, an image display apparatus, etc., and the polarizing plate and optical laminated body obtained by this manufacturing method.

Generally, a polarizing plate is formed by bonding a protective film to one side or both sides of a polarizing film. As a protective film, the film provided with the function of any one of retardation film, a brightness improving film, a viewing angle improvement film, and a transflective film may be used.

By the way, the direction of the optical axis of an optical film in a liquid crystal display etc., ie, the direction of the absorption axis of a polarizing film, and the direction of the slow axis of a retardation film have a big influence on the display performance of the liquid crystal display etc. made into the objective. give. Therefore, an optical film is cut out so that it may become the direction of the optical axis suitable for a liquid crystal display device etc. made into the objective. And the cut sheet film is bonded to a continuous film so that an optical axis may become 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 surface of a rolled polyvinyl alcohol polarizing film by using an aqueous adhesive.

[Patent Document 1] Japanese Patent Application Laid-Open No. 2007-193333

However, in the polarizing plate obtained by the method described in Patent Literature 1, when the heat-promoting acceleration test (so-called heat cycle test) that repeats heating and cooling or the heat-resistant test placed under a high temperature environment for a long time is performed, the end portion protrudes or Bubbles may occur on the joining surfaces or curls may occur on the joining surfaces. Moreover, in the manufacturing method of the polarizing plate of patent document 1, since the dryer for drying an aqueous adhesive is needed, there existed a problem that an apparatus enlarged and cost increased.

The main object of this invention is to provide the manufacturing apparatus of the polarizing plate which does not enlarge an apparatus and further improves the production efficiency, and the manufacturing method of the polarizing plate using the same. Moreover, another object of this invention is to provide the polarizing plate which is excellent in an external appearance by suppressing generation | occurrence | production of the edge part and bubble in the bonding surface of a film.

MEANS TO SOLVE THE PROBLEM The present inventors earnestly examined in order to solve the said subject. As a result, after apply | coating UV cure adhesive to a continuous roll-shaped film, bonding the sheet film cut | disconnected to predetermined | prescribed size so that an optical axis may become a predetermined angle, and irradiating an ultraviolet-ray to a bonding surface, and hardening an UV cure adhesive, (i) Since no dryer is required, the apparatus is not enlarged, and the polarizing plate can be manufactured continuously and efficiently. (ii) In addition, the bonding surface in the bonding surface of the film in a heat resistance promotion test or a heat resistance test. It discovered that the polarizing plate by which generation | occurrence | production of the edge part protrusion, the generation | occurrence | production of the bubble, and the generation | occurrence | production of the curl in the joining surface was suppressed was found, and completed this invention.

That is, this invention relates to the following description.

(1) One side is a continuous film wound up in roll shape, The other side is a manufacturing apparatus of the polarizing plate which bonds the polarizing film and protective film which are sheet films,

A means for unwinding the continuous film wound in a roll shape, a means for applying an ultraviolet curable adhesive on one side of the released continuous film, a means for superposing a sheet film on the adhesive coated surface of the continuous film, and the ultraviolet curable type Polarizing plate manufacturing apparatus containing ultraviolet irradiation means for hardening an adhesive agent.

(2) A sheet film and a surface protective film covering them are superimposed in this order on the adhesive coated surface of the continuous film, the ultraviolet curable adhesive is cured to bond the continuous film and the sheet film, and then the surface protective film is peeled off and separated. The manufacturing apparatus as described in (1) containing means to perform.

(3) The said sheet film is mounted on the adhesive film for protective film peeling which runs toward a take-up roll from a supply roll, and is conveyed to the overlapping position with the said continuous film, The sheet film is said while peeling a protective film from the said sheet film. The manufacturing apparatus as described in (1) or (2) comprised so that it may overlap with a continuous film.

(4) As a manufacturing method of the polarizing plate which bonds the polarizing film and protective film which one side is a film wound in roll shape, and the other is a sheet film,

Applying an ultraviolet curable adhesive on one side of the continuous film while continuously unrolling the continuous film wound in a roll shape, and then laminating a sheet film on the adhesive application side of the continuous film, and then irradiating ultraviolet light to the ultraviolet curable adhesive Curing, and manufacturing a polarizing plate comprising laminating a sheet film to the continuous film.

(5) The polarizing plate by which a protective film is bonded by at least one surface obtained by the manufacturing method as described in said (4).

(6) The polarizing plate as described in (5) in which the said protective film is equipped with the function of any one of retardation film, a brightness improving film, a viewing angle improvement film, and a transflective film.

(7) The optical laminated body by which the polarizing plate of said (5) and at least 1 sort (s) chosen from retardation film, a brightness improving film, a viewing angle improvement film, and a semi-transmissive reflective film are bonded together.

According to the method for producing a polarizing plate of the present invention, the continuous rolled film and the sheet film can be continuously bonded with high efficiency using an ultraviolet curable adhesive without using water or other solvents. In addition, there is no need for a drying device for volatilizing the solvent. Therefore, the manufacturing apparatus as a whole can not be enlarged and the cost can be reduced.

The polarizing plate of this invention can reduce the generation | occurrence | production of the edge part protruding, the bubble, and the generation | occurrence | production of the curl in the bonding surface in the bonding surface of a film in a heat-resistant acceleration test, etc.

One embodiment of the polarizing plate manufacturing apparatus which concerns on this invention is shown in FIG. As shown in the figure, this polarizing plate manufacturing apparatus 1 is equipped with a pair of take-up rolls 61 and 62 which continuously unwind the polarizing film 2 wound in roll shape. The peeling film 3 for surface protection of the polarizing film 2 is previously bonded by one side of the polarizing film 2, and the peeling film 3 is isolate | separated by the 1st roll 4. The peeling film 3 is wound up and collect | recovered in roll shape.

The polarizing film 2 in which the peeling film 3 was isolate | separated is sent to the adhesive agent application apparatus 5 which apply | coats an ultraviolet curable adhesive agent, and a predetermined amount of ultraviolet curable adhesive agent is apply | coated to one side by the application roll 51, It is sent to a pair of bonding rolls 71 and 72.

On the other hand, the sheet protective film 8 cut | disconnected to predetermined | prescribed magnitude | size is conveyed to the bonding rolls 71 and 72. FIG. A protective film (not shown) is bonded to the bonding surface of the sheet protective film 8 with the polarizing film 2. Therefore, the protective film must be peeled off prior to the bonding of the sheet protective film 8 and the polarizing film 2. Therefore, this protective film peeling is carried out continuously, running the adhesive tape 9 for protective film peeling in the conveyance direction of the sheet protective film 8 toward the winding roll 92 from the supply roll 91 wound by roll shape. The protective film surface of the sheet protective film 8 is mounted and bonded on the adhesive tape 9. Reference numeral 10 denotes a suction conveying device for suction-holding the sheet protective film 8 one by one, sequentially loading and bonding the surface of the adhesive tape 9 for protective film peeling.

The sheet protective film 8 bonded on the adhesive face of the adhesive tape 9 for protective film peeling is conveyed to the overlapping position with the polarizing film 2, and a sheet is peeled off while peeling a protective film from the said sheet protective film 8 It is comprised so that the protective film 8 may overlap with the polarizing film 2. That is, the sheet protective film 8 is superimposed on the adhesive agent coating surface of the polarizing film 2 by a pair of bonding rolls 71 and 72. At that time, the adhesive tape 9 for peeling of protective film is folded in the opposite direction to the traveling direction of the sheet protective film 8 immediately before the bonding rolls 71 and 72, and is protected from the sheet protective film 8 at the folding part. Since the film is peeled off, only the sheet protective film 8 is superposed on the adhesive application surface of the polarizing film 2 by the bonding rolls 71 and 72. As the adhesive tape 9 for peeling protective film, what provided the adhesive layer in the surface of a plastic film base material, etc. can be used, for example.

In the bonding rolls 71 and 72, the surface protection film 12 is further superimposed on the polarizing film 2 and the sheet protective film 8. This surface protection film 12 is a film wound in roll shape, and it is unwound continuously and is made to superimpose on the polarizing film 2 and the sheet protective film 8 by the bonding rolls 71 and 72. FIG.

The surface protective film 12 is used to prevent the ultraviolet curable adhesive from being pushed out of the polarizing film 2 and the sheet protective film 8 and contaminating the device. As the surface protection film 12, it is preferable that the hardening | curing of the ultraviolet curable adhesive agent by the following ultraviolet irradiation does not interfere, For example, plastic films, such as transparent or semitransparent polyethylene and polyester resin, are mentioned.

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

The ultraviolet irradiation device is provided above and below the conveyance path of the polarizing film 2 and the sheet protective film 8, and is comprised so that an ultraviolet-ray may be irradiated from the upper and lower sides. Accordingly, even when either the polarizing film 2 or the sheet protective film 8 is a material which is difficult to transmit ultraviolet rays, the ultraviolet curable adhesive is surely cured, and the polarizing film 2 and the sheet protective film 8 are formed. It can be firmly bonded.

As the sheet protective film 8, a film having optical functions such as a function as a retardation film, a function as a brightness enhancement film, a function as a reflective film, a function as a semi-transmissive reflective film, a function as a diffusion film, a function as an optical compensation film, etc. Can 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 semi-transmissive reflection film, a diffusion film, an optical compensation film and the like on the surface of the protection film, a protective film in addition to having such a function You can also give this functionality to itself. Moreover, you may make a protective film itself a some function like the diffusion film which has a function of a brightness improving film.

For example, the above described protective film may be subjected to the stretching treatment described in Japanese Patent No. 2841377, Japanese Patent No. 3094113, or the like, or the treatment described in Japanese Patent No. 3168850, or the like, to impart a function as a retardation film. Can be. Furthermore, by forming a fine hole in the above-mentioned protective film by the method as described in JP-A-2002-169025 or JP-A-2003-29030, two or more layers having different center wavelengths of selective reflection By superimposing a cholesteric liquid crystal layer, the function as a brightness improving film can be provided. By forming a metal thin film on said protective film by vapor deposition, sputtering, etc., the function as a reflective film or a semi-transmissive reflective film can be provided. By coating the resin solution containing microparticles | fine-particles on said protective film, the function as a diffusion film can be provided. Further, by coating and orienting a liquid crystal compound such as a discotic liquid crystal compound on the protective film, the function as an optical compensation film can be imparted. Moreover, using a suitable adhesive, brand name: brightness improvement films, such as DBEF (made by 3M Corporation), brand name: viewing angle improvement films, such as WV film (made by Fuji Photographic Film Co., Ltd.), brand name: Sumikalite (trademark registration) Commercially available optical functional films, such as retardation films, such as (Sumitomoka Chemical Co., Ltd.), may be directly bonded to a polarizing film.

After the adhesion, the surface protective film 12 is wound into a roll to be separated into the polarizing film 2 and the sheet protective film 8. The bonded polarizing film 2 and the sheet protective film 8 are cut | disconnected to predetermined size, and are used as an optical laminated body.

In this invention, the ultraviolet curable adhesive agent which adheres the said polarizing film 2 and the sheet protective film 8 has the characteristic that when an ultraviolet-ray is irradiated, it will cause a photopolymerization reaction and harden | cure. For example, when the ultraviolet curable adhesive is irradiated with an ultraviolet ray having a wavelength of about 350 nm to 380 nm, the initial curing is started for several tens of seconds, and after a few minutes, it is cured to an appropriate elasticity. Such an ultraviolet curable adhesive is composed of a prepolymer, a monomer, a photopolymerization initiator (for example, a photo cationic polymerization initiator), and the like, and has less expansion with respect to heat, and thus the accuracy is stable through a temperature cycle. In addition, because of the low shrinkage, it can be bonded with high accuracy, and because of the low water absorption, high quality can be maintained even under an environment such as high humidity and high temperature. Examples of the ultraviolet curable adhesive include epoxy resin adhesives which do not contain an aromatic ring in molecules such as hydrogenated epoxy resins, alicyclic epoxy resins, and aliphatic epoxy resins.

Since such an ultraviolet curable adhesive does not substantially contain water and other solvents in its composition, no solvent remains between the polarizing film 2 and the sheet protective film 8, and the end protrusion of the polarizing plate in the heat resistance promotion test is not included. In addition, a bubble does not generate | occur | produce in the bonding surface with a glass surface, and a polarizing plate and an optical laminated body with a favorable external appearance can be obtained. The application amount of the ultraviolet curing adhesive is not particularly limited, and is, for example, 0.5 µm to 6 µm, and preferably 1 µm to 4 µm in thickness. In addition, the coating of an ultraviolet curable adhesive is not specifically limited to the method and apparatus shown in FIG.

When hardening by ultraviolet irradiation, the light source used has a light emission distribution in wavelength 100nm -400nm. Although the irradiation intensity of an ultraviolet-ray is determined for every composition made into the objective, it is although it does not specifically limit, It is preferable that irradiation intensity of the wavelength range effective for activation of an initiator is 1-600 mW / cm <2>. When the irradiation intensity of the ultraviolet rays is less than 1 mW / cm 2, the reaction time is long, and when it exceeds 600 mW / cm 2, there is a possibility that the polarizing film may be deteriorated by the heat radiated from the lamp and the heat generated during the polymerization of the composition.

Irradiation time of an ultraviolet-ray is controlled for every composition to harden | cure, Although it does not specifically limit, It is preferable to set so that the accumulated light amount shown as a product of irradiation intensity and irradiation time may be set to 10-1000 mJ / cm <2>. If the amount of accumulated light is less than 10 mJ / cm 2, the generation of active species derived from the initiator may not be sufficient, and curing may become insufficient. On the other hand, if the amount of accumulated light exceeds 1000 mJ / cm 2, the irradiation time becomes very long. It is disadvantageous in terms of productivity.

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

In addition, in this embodiment, although the polarizing film 2 was used as a continuous film, and the sheet protective film 8 was used as a sheet film, on the contrary, a continuous film may be a protective film and a sheet film may be a polarizing film.

Moreover, an optical laminated body can be manufactured by bonding together the polarizing plate obtained as mentioned above and at least 1 sort (s) chosen from retardation film, a brightness improving film, a viewing angle improvement film, and a semi-transmissive reflecting plate.

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

Example 1

An ultraviolet curable adhesive (KRX492-25, manufactured by ADEKA Corporation) was applied to one surface of a polyvinyl alcohol polarizing film having a thickness of 123 μm and a width of 400 mm using the apparatus shown in FIG. The phase difference film (300 mm x 400 mm, thickness 88 micrometers, the Sekisuga Chemical Co., Ltd. make) of the sheet | seat is superimposed on it, and it irradiates an ultraviolet-ray for 5 second with the accumulated light quantity of 300 mJ / cm <2> by an ultraviolet irradiation device. And the ultraviolet curable adhesive was cured to obtain a polarizing plate (irradiation ultraviolet wavelength: 365 nm, adhesive film thickness: 3 µm, conveyance tension: 100 N / m).

Comparative Example 1

As a pressure-sensitive adhesive, a polarizing plate was produced in the same manner as in Example 1 except that the retardation film of the sheet was bonded to one surface of the polarizing film using NS300MP (manufactured by Lintec Co., Ltd.), and a heat resistance promotion test was performed.

<Heat resistance promotion test>

The polarizing plates obtained in Example 1 and Comparative Example 1 were repeatedly heated and cooled alternately at a temperature condition of 85 ° C and -40 ° C at 30 minute intervals in a thermostatic chamber, and after 350 cycles of this, the presence of bubbles was observed. As a result, although the generation | occurrence | production of the bubble was confirmed in the polarizing plate of the comparative example 1 over the perimeter, the bubble was hardly confirmed by the polarizing plate of Example 1.

<Heat test (end projection of film)>

After the polarizing plate obtained in Example 1 was hold | maintained in 85 degreeC atmosphere for 250 hours, the edge protrusion of the film was observed with the confocal interference microscope (PL-micro 2300 by SENSOFAR company). As a result, the protrusion height was within 1 micrometer in the range within 500 micrometers from the edge part. On the other hand, in the polarizing plate of the comparative example 1, protrusion height was 3 micrometers-4 micrometers.

As mentioned above, although the manufacturing apparatus and manufacturing method of the polarizing plate of this invention, the polarizing plate and optical laminated body obtained by this manufacturing method were explained in full detail, this invention is not limited to these descriptions, In the range which does not impair the meaning of this invention. It can be changed or improved as appropriate.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic explanatory drawing which shows one Embodiment of the polarizing plate manufacturing apparatus which concerns on this invention.

Claims (7)

As a polarizing plate manufacturing apparatus which joins the polarizing film and protective film which one side is a continuous film wound in roll shape, and the other is a sheet film, Means for unwinding the continuous film wound in a roll shape, Means for applying an ultraviolet curable adhesive to one side of the unwrapped continuous film, Means for superposing a sheet film on the adhesive coated surface of the continuous film; UV irradiation means for curing the ultraviolet curable adhesive Polarizing plate manufacturing apparatus comprising a. The surface protective film according to claim 1, wherein a sheet film and a surface protective film covering them are superimposed on the adhesive coated surface of the continuous film in this order, and the ultraviolet curable adhesive is cured to bond the continuous film and the sheet film. The polarizing plate manufacturing apparatus further includes a means which peels and isolates. The said sheet film is mounted on the adhesive film for protective film peeling which runs toward a winding roll from a supply roll, and is conveyed to the overlapping position with the said continuous film, The protective film of Claim 1 or 2 characterized by the above-mentioned. The polarizing plate manufacturing apparatus comprised so that a sheet film may overlap with said continuous film, peeling off. As a manufacturing method of the polarizing plate which bonds the polarizing film and protective film which one side is a film wound up in roll shape, and the other is a sheet film, Applying an ultraviolet curable adhesive on one side of the continuous film while continuously unrolling the continuous film wound in a roll shape, and then laminating a sheet film on the adhesive coated surface of the continuous film, and then irradiating ultraviolet light to apply the ultraviolet curable adhesive Hardening | curing and laminating and bonding a sheet film on the said continuous film. The polarizing plate by which a protective film is bonded by at least one surface obtained by the manufacturing method of Claim 4. The polarizing plate of Claim 5 in which the said protective film is equipped with the function of any one of retardation film, a brightness improving film, a viewing angle improvement film, and a semi-transmissive reflective film. The optical laminated body by which the polarizing plate of Claim 5 and at least 1 sort (s) chosen from retardation film, a brightness improving film, a viewing angle improvement film, and a semi-transmissive reflective film are bonded together.

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