KR20090065017A - Polarizer and production process thereof - Google Patents

Abstract

A polarizing plate and a manufacturing method thereof are provided to include a polarizer protecting layer capable of providing a thin film type polarizing plate by facilitating thickness control. A resin layer is formed by coating an ultraviolet curing or thermosetting resin on a carrier film(a). A polarizer protecting layer is formed by bonding the resin layer with a polarizer layer through adhesive(d). The carrier film is removed. The carrier film is selected among polyethylene terephthalate, cyclo olefin polymer, polycarbonate, triacetyl cellulose, and polyethersulphone.

Description

Polarizing plate and manufacturing method thereof

The present invention relates to a method of manufacturing a polarizing plate including a polarizer protective layer and a polarizing plate produced thereby.

A polarizing plate generally has a structure in which a polyvinyl alcohol (PVA) -based molecular chain is oriented in a predetermined direction and includes an iodine compound or a dichroic polarizing material, or a dehydration reaction of a polyvinyl alcohol film or a polyvinyl chloride (PVC) film A polarizer having a polyene structure formed by the dehydrochlorination reaction of the present invention has a structure in which a triacetyl cellulose film (hereinafter referred to as a TAC film) is laminated with an aqueous adhesive composed of a polyvinyl alcohol-based aqueous solution as a protective film. .

Figure 1 schematically shows a conventional polarizing plate manufacturing method using a TAC.

As shown in FIG. 1, a TAC material without a phase retardation is used for manufacturing a polarizing plate using a conventional TAC, undergoes a surface gumification process for adhesion of a TAC, and then undergoes a thermal bonding process with a water-soluble PVA adhesive. In the case of the polarizing plate manufactured as described above, the material of the polarizer protective layer is limited to the TAC that is easily adhered to the polarizer, and there is a risk of breakage during the manufacturing process, which makes it difficult to apply a thin film type TAC.

In order to solve this problem, an epoxy acrylate resin is laminated on a polarizer in the form of a film as a protective film (Japanese Patent Laid-Open No. 2007-47498), or an acrylic resin layer is used as a polarizing plate protective film (Japanese Laid-Open Patent No. 2006-284882), A method of laminating or blending a thermoplastic resin layer on an acrylic resin layer to form a polarizing plate protective sheet (Japanese Patent Laid-Open No. 2004-126546, Japanese Patent Laid-Open No. 2006-215463) or the like has been proposed.

However, the above methods do not sufficiently reflect the inherent high heat resistance and high transparency of the acrylic resin or have a complicated laminate structure. Therefore, it is difficult to manufacture a thin film having a thickness of 40 μm or less due to breakage of the protective film in the manufacturing process, and the polarizing plate used on the outside of the display requires a separate surface treatment, thereby increasing the manufacturing cost.

The present invention provides a polarizing plate including a polarizer protective layer which can provide a thin film type polarizing plate with easy thickness control as well as bring about the same surface treatment effect as a conventional surface treated polarizer protective layer without any surface treatment coating. To provide.

The present invention comprises the steps of (a) coating a UV curable or thermosetting resin on a carrier film to form a resin layer, and (b) bonding the resin layer with a polarizer layer to form a polarizer protective layer It provides a manufacturing method of a polarizing plate comprising.

In addition, if necessary (c) provides a method of manufacturing a polarizing plate further comprising the step of removing the carrier film after the step (b).

Another embodiment of the present invention provides a polarizer protective film including a carrier film and a resin layer formed by coating and curing one surface of a carrier film.

In addition, the polarizer protective film provides a polarizing plate included on one side or both sides of the polarizer and an image display device including the polarizing plate.

According to the present invention, the thickness of the protective layer can be arbitrarily controlled without particular limitation, and thus a polarizing plate including a polarizer protective layer capable of forming a thin film and a method of manufacturing the same can be provided. In addition, it is possible to provide a polarizing plate and an image display device which can reduce the surface treatment and the like, thereby simplifying the process and reducing the cost.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 2, the present invention provides a method of forming a resin layer by (a) coating and curing a UV curable or thermosetting resin on a carrier film, and (b) using an adhesive to form the resin layer. A method of manufacturing a polarizing plate comprising adhering and curing with a polarizer layer to form a polarizer protective layer.

In addition, if necessary (c) after the step (b) may further comprise the step of removing the carrier film using a carrier film peeling device.

According to the present invention, since the polarizer protective layer is formed by curing the UV curable or thermosetting resin, there is almost no phase in the surface or thickness direction. In addition, since the resin layer is formed on the carrier film by the coating method, the thickness can be controlled to form an ultra-thin film with a thickness of 3 to 80 μm, preferably 3 to 40 μm. When the protective layer is directly formed on the polarizer, a problem of fracture may occur in the manufacturing process, but according to the present invention, the carrier film serves as a support to prevent this.

The coating of the UV-curable or thermosetting resin is not particularly limited, but may be performed using a coating method capable of imparting coating uniformity such as gravure coating, microgravure coating, lip die coating, comma coating, and bar coating. have.

In addition, since the TAC is used as a protective film, a polarizing agent and a protective layer are adhered to each other by a UV curing or thermosetting method without requiring a saponification process for adhesion.

The carrier film is a flexible plastic material capable of laminating plywood, and is not particularly limited, but is preferably PET, cyclo olefin polymer (PCP), PC, TAC, and polyethersulphone (PES).

If necessary, a carrier film having a primer layer formed on one or both surfaces thereof may be used to facilitate separation of the protective layer and the carrier film. In this case, the primer layer is preferably added to the acrylic or urethane-based resin coating layer of less than 0.1 to 3.0% by weight of the silicone-based acrylic resin.

The resin coated on the carrier film is not particularly limited as long as UV resin and thermosetting are possible.

As the UV curing resin, resins such as acrylic, urethane, vinyl, and epoxy resins can be mixed and used in the form of monomers or polymers, and 2,4,6- so as to enable photoinitiation in the wavelength region of 380 to 440 nm. 0.5 to 5.0% by weight of a long wavelength photoinitiator such as trimethylbenzoyl phosphine oxide (2,4,6-Trimethylbenzoyl phosphine oxide) may be added. In this case, a metal halide and a mercury lamp may be used as the UV curing lamp. In addition, a benzophenone-based compound commercialized as a short wavelength photoinitiator may be mixed with the long wavelength photoinitiator in a 1: 1 ratio.

In order to form a UV cured film, after coating the resin on a carrier film, it is preferable to irradiate ultraviolet rays by dividing the resin into two or three times with a light amount of 700 to 2000 mJ / cm 2 after drying for 1 to 3 minutes at 50 to 80 ° C.

As the thermosetting resin, acrylic, vinyl, epoxy, and ester resins may be mixed and used in the form of monomers or polymers. As the thermosetting initiator, a commercially available peroxide organic peroxide may be used.

In order to form a thermosetting film, after coating the resin on a carrier film, it is preferable to form a film by drying at a temperature between 90 ° C. and 120 ° C. for 3 to 5 minutes.

The resin may further be mixed with a functional agent such as a sunscreen agent, a UV absorber, a slip agent, an antistatic agent and an antireflective additive.

The ultraviolet absorber is not particularly limited as long as the ultraviolet absorber at 380 nm can be 5% or less. However, a thinuvin-based, cyasorb-based and benzophenol-based are preferable. In this case, the mixture is mixed at a ratio of 3 to 10% by weight based on the total composition.

For the purpose of improving the slip, silicone-based, fluorine-based and acrylic resins may be used, and a leveling agent may be added to prevent phase separation from occurring during the compounding process. As the leveling agent, silicone, fluorine and acrylic compounds may be used alone or in combination.

When the resin layer is exposed to the outermost layer of the polarizing plate to serve as a surface treatment layer, it should be such that dust or foreign matter does not easily adhere. To this end, it is possible to give an antistatic function when blending the resin solution. In order to impart the antistatic property, a conductive additive such as surfactant, ITO, zinc oxide and thiophene can be used.

In addition, PMMA beads and silica for AG may be added for the purpose of antireflection, and if necessary, an antireflection effect on the surface of the cured resin film may be obtained by using a carrier film having irregularities.

As the adhesive used for adhesion of the resin layer and the polarizer layer, both UV curing adhesives and thermosetting adhesives may be used. In particular, in the case of using a UV curing adhesive, the adhesion with the resin layer is easy to improve the adhesion efficiency. The UV-curing adhesive may be used by mixing monomers and oligomers such as acrylic, epoxy, acrylic acid, urethane, and the like, and TPO may be added to enable photoinitiation in a long wavelength band.

UV curing adhesive lamps can use metal halides and mercury lamps. When irradiating a large amount of light at one time, the polarizing plate may be deformed, so repeatedly irradiate several times with a light amount of 500 to 3000 mJ / cm 2.

As the curing agent of the thermosetting adhesive, polyurethane, polyester, melamine, amine and acrylic crosslinking agents may be used alone or in combination. In the case of thermosetting adhesion | attachment, it is preferable to proceed by dividing drying into two steps. That is, the carrier film may be first peeled off after drying for 3 to 5 minutes between 70 ° C. and 110 ° C., and the second heat treatment may be repeatedly performed under the same temperature condition, and then the adhesive strength may be increased by 30 ° C. aging treatment.

In addition, according to the present invention, if necessary, the carrier film can be substituted as a protective film of the polarizing plate, when the surface hardness of the polarizer protective layer is high can exhibit a clear surface treatment coating function without a separate hard coating.

In addition, as another embodiment of the present invention, as shown in Figure 3, to provide a polarizer protective film comprising a carrier film and a resin layer formed on the coating and UV curing or thermosetting on one surface thereof.

In addition, as another exemplary embodiment of the present invention, as shown in FIG. 4, a polarizer including a polarizer, a polarizer protective film laminated using an adhesive on one or both surfaces of the polarizer, and a peelable carrier film as necessary. do.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the following examples merely illustrate the present invention, and the protection scope of the present invention is not limited only to the following examples.

Example 1

A polyvinyl alcohol (PVA) -based molecule was stretched five times in a predetermined direction, impregnated with an iodine compound, and dried at 100 ° C. to prepare a polarizer.

Dissolve an epoxy acrylate (Bisphenol-A Epoxy Diacrylate) resin in 50% by weight in a solvent mixed with isopropyl alcohol and acetone at 8: 2, and after stirring for about 2 hours, the thickness of the carrier film with a 200mesh micro gravure coater Coating was performed on a 50 micrometer polyester film.

The coated polyester film was dried at a drying temperature of 50 ° C. to 80 ° C. for about 2 minutes, and irradiated twice with an amount of ultraviolet light of 900 mJ / cm 2 to form a resin film having a thickness of about 27 μm. An acrylic acid UV curable adhesive is used as an adhesive for bonding the polarizer and the protective film of the polarizer, and an adhesive is injected between the polarizer and the resin film formed on the carrier film and laminated. The amount of cm 2 light was irradiated in four portions and joined. Immediately after the bonding was completed, the carrier film was peeled off to complete the polarizing plate.

Comparative example  One

As the polarizer protective film on the polarizer manufactured by the method of Example 1, a triacetyl cellulose film was used as the outer side and a triacetyl cellulose film having a phase value of 10 nm or less was laminated on the opposite side of the polarizer. In order to improve the surface energy of the triacetyl cellulose surface for bonding the polarizer and the protective film, it was impregnated with NaOH 3% caustic soda solution for 2 minutes. The adhesive was laminated with an aqueous adhesive made of a polyvinyl alcohol-based aqueous solution, dried for 4 minutes at a drying temperature of 80 to 100 ° C, and then aged for 48 hours in a 30 ° C chamber.

Physical properties of the protective film and the polarizing plate prepared according to Example 1 and Comparative Example 1 are shown in Table 1 below.

Example Comparative example Protective film Thickness (㎛) 27 40 Permeability (%) 92.1 92.0 Haze 1.2 0.9 Rin (nm) 0.6 1 ~ 2 Rth (nm) 2.6 5 material TAC Workability (break) Good Good Polarizer Thickness (㎛) 98 140 Group transmittance (%) 41.0 41.2 Parallel transmittance (%) 34.3 35.2 Orthogonal Transmittance (%) 0.004 0.007

As shown in Table 1, according to the present invention, it is possible to manufacture a protective film and a polarizing plate in the form of a thin film, and exhibits a smaller plane direction retardation (Rin) and thickness direction retardation (Rth) values than the TAC protection film. have.

Figure 1 schematically shows a conventional polarizing plate manufacturing method using a TAC.

Figure 2 schematically shows a method of manufacturing a polarizing plate according to one embodiment of the present invention.

Figure 3 shows the structure of a polarizer protective film according to one embodiment of the present invention.

Figure 4 shows the structure of a polarizing plate according to one embodiment of the present invention.

Claims (14)

(a) coating a UV curable or thermosetting resin on a carrier film to form a resin layer, and (b) bonding the resin layer with a polarizer layer using an adhesive to form a polarizer protective layer. Method for producing a polarizing plate comprising a. The method of claim 1, further comprising (c) removing the carrier film after the step (b). The method of claim 1, wherein the carrier film is selected from PET, cyclo olefin polymer (COP), PC, TAC, and polyethersulphone (PES). The method of claim 1, wherein the UV curable resin is a mixture of acrylic, urethane, vinyl, and epoxy resins in a monomer or polymer form. The method of claim 1, wherein the coating of the UV curable or thermosetting resin is performed by gravure coating, microgravure coating, lip die coating, comma coating, and bar coating. The method of claim 1, wherein the resin layer is coated with a thickness of 3 to 80 μm. The method of claim 6, wherein the resin layer is coated with a thickness of 3 to 40 μm. The method according to claim 1, wherein the UV curable or thermosetting resin is additionally used by mixing a sunscreen, a UV absorber, a slip, an AS (antistatic) functional agent and an antireflective additive. The method of claim 1, wherein the adhesive is used by mixing acrylic, epoxy, acrylic acid, and urethane resins with monomers or oligomers. A polarizer protective film comprising a carrier film and a resin layer formed by coating and UV curing or thermosetting on one surface thereof. The polarizer protective film of claim 10, wherein the resin layer mixes a sunscreen, a UV absorber, a slip, an AS (antistatic) functional agent, and an antireflective additive to a UV curable or thermosetting resin. A polarizing plate formed by applying an adhesive to one or both sides of the polarizer, laminating the polarizer protective film according to claim 10, and then UV curing or thermosetting. A polarizing plate formed by applying an adhesive to one or both sides of the polarizer, laminating the polarizer protective film according to claim 10, followed by UV curing or heat curing, and peeling off the carrier film. An image display device comprising the polarizing plate according to claim 12.

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