KR20110079139A - Manufacturing method of polarizing film and polarizing film thereby - Google Patents

Abstract

PURPOSE: A manufacturing method of polaroid film and a polaroid film manufactured therefrom are provided to control thickness of the nano fiber with the speed of electricity emission and rotation speed of wind roll, and to form pattern by arranging nano fiber along the electric field in which voltage is sanctioned to the wind roll. CONSTITUTION: The nano fiber(40) is obtained by electricity-emitting the polymer. The nano tube pattern is formed on the base film(50) by sanctioning the electric field, in the roll(20) in which the base film is wound, and winding. The base film in which nano tube is arranged is orientated.

Description

Manufacturing method of polarizing film and polarizing film manufactured therefrom {MANUFACTURING METHOD OF POLARIZING FILM AND POLARIZING FILM THEREBY}

The present invention relates to a method for manufacturing a polarizing film and a polarizing film produced therefrom, and more particularly, to a method of manufacturing a polarizing film to easily control the thickness and spacing of nanofibers and have excellent polarization characteristics in electrospinning a polymer material. And it relates to a polarizing film produced therefrom.

Liquid crystal display (LCD) refers to a display device in which a liquid crystal is injected between two glass substrates on which a transparent electrode is formed on a surface, and controls light transmittance while rotating liquid crystal by applying electricity from the outside. Liquid crystal display panels used in LCD devices have advantages over other display devices because of their thinness, lightness, and low power consumption. However, unlike CRTs, liquid crystal display panels are devices that control light transmittance, rather than pixels emitting light by themselves. Therefore, the backlight unit may be installed on the rear side of the liquid crystal panel and used as a light source, and a voltage may be applied to the liquid crystal in the front portion to control the light transmission to display the screen.

The polarizing film is a mechanism having a function of transmitting and shielding light, and in the LCD, the polarizing film is a basic component because it functions to switch light. In addition to the LCD, the polarizing film may be applied to small devices such as electronic calculators and wristwatches in the early stages of development, and recently, laptop personal computers, word processes, liquid crystal color projectors, vehicle navigation systems, liquid crystal televisions, personal phones, and indoor and outdoor measurements. Wide range of devices and the like.

Conventional polarizing film is manufactured with a structure comprising a polyvinyl alcohol (PVA) film polarizer dyed with iodine or dichroic dye and a protective film on one or both sides.

Recently, display apparatuses require more improved visual characteristics, and thus, polarizing films that exhibit increased optical isotropy have been developed. In particular with respect to optical isotropy, it is required that the retardation value expressed by the product of the birefringence and the thickness of the optical film is small.

Various attempts have been proposed as part of such an improvement effort, and Korean Patent Laid-Open Publication No. 2004-0105583 discloses a carbonate bond from a dihydroxy compound having a specific structural formula and a dihydroxy compound having a dimethanol structure, and a carboxylic acid diester. The polarizing sheet using the polycarbonate resin composition manufactured by mix | blending the polycarbonate resin manufactured by formation and the polycarbonate resin obtained by carbonate bond formation from bisphenol A and carboxylic acid diester or phosgene was proposed. The proposed technique is a method of preparing a polarizing sheet by manufacturing a polycarbonate resin composition by melt extrusion method and then attaching a known polarizing film to it, and since the polycarbonate resin simply serves as a protective film, In not much different from the conventional method.

In addition, Korean Patent Laid-Open No. 2006-0092737 relates to a film composed of carbon nanotubes and a method of manufacturing the same, and provides a carbon nanotube film having optical transparency in the visible light region, and chemically surface treated carbon nanotubes Alternatively, a carbon nanotube bundle is deposited on a substrate using a Langmuir-Blodgett method to disclose a uniform or patterned carbon nanotube film and a method of manufacturing the same. The patent document describes that carbon nanotubes prepared by the above method are extremely thin and uniform enough to have conductivity and transparent, and can be used in electronic devices, sensors, displays, etc. because the carbon nanotubes are oriented in one direction at a high density. have. However, the technology has a disadvantage in that it is not possible to commercially produce small scale in a very limited place as well as the durability of the film is weak, so it is difficult to secure reliability as a material.

In addition, Korean Patent Publication No. 2007-0028304 discloses a pigment for anisotropic dye films containing a compound having a compound having two or more functional groups, including at least one basic functional group selected from the group consisting of a dye and an acidic functional group, a basic functional group and a neutral functional group. The content about the anisotropic dye film formed using the composition and the polarizer using such a dye film is disclosed. However, the compound according to the present invention has a disadvantage in that it cannot be processed by heat because it is water-soluble and can be processed only in an aqueous solution state, as the polarizing film impregnated with an aqueous solution of iodine in a polyvinyl alcohol resin. In addition, by applying a pigment that is more expensive than the conventional commercialized polarizing film there is a problem that the economical efficiency is lowered.

Accordingly, the present inventors confirmed that the nanofibers used as the polarizers of the polarizing film can be easily manufactured by overcoming the above problems, and the polarizing properties of the polarizing films produced thereby are excellent. The present invention has been reached.

An object of the present invention is to provide a method of manufacturing a polarizing film that can form a polarizing pattern by arranging nanofibers on a substrate at uniform intervals.

Another object of the present invention is to provide a polarizing film having excellent polarization characteristics produced by the above method.

Polarizing film production method of the present invention for achieving the above object is a step of obtaining a nanofiber by electrospinning a polymer material; Winding the nanofibers while applying an electric field to the roll on which the base film is wound to form a nanotube pattern on the base film; And stretching the base film on which the nanotubes are aligned.

The polymer material electrospun with the nanofibers is preferably at least one polymer fiber selected from the group consisting of polyethylene terephthalate, polycarbonate, polymethyl methacrylate, polyethylene naphthalate and polystyrene.

The nanofibers preferably have a diameter of 20 nm to 1 μm.

The material of the base film is preferably at least one polymer selected from the group consisting of polyethylene terephthalate, polycarbonate, polymethyl methacrylate, polypropylene, polyethylene and polystyrene.

The pattern is that the nanofibers are aligned in the longitudinal direction on the base film, it is preferable that the alignment interval is uniform, the alignment interval is preferably 20nm to 1㎛.

On the other hand, the polarizing film of the present invention is prepared by the above method, and comprises a base film and a nanofiber layer attached to one side of the base film to form a pattern.

In the manufacturing method of the polarizing film of the present invention, the thickness of the nanofibers can be adjusted by the speed of electrospinning and the rotational speed of the take-up roll, and the nanofibers are arranged in accordance with the electric field formed by applying a voltage to the take-up roll to form a pattern. Form. Therefore, in the pattern formation of the nanofibers forming the polarizer of the polarizing film, it is easy to control the thickness and spacing of the nanofibers, thereby manufacturing a polarizing film having excellent polarization characteristics.

Method for producing a polarizing film of the present invention comprises the steps of electrospinning a polymer material to obtain nanofibers; Winding the nanofibers while applying an electric field to the roll on which the base film is wound to form a nanotube pattern on the base film; And stretching the base film on which the nanotubes are aligned.

In the first step in the manufacturing method of the polarizing film of the present invention, an electrospinning method is used. In this case, the electrospinning is a phenomenon in which fibers are formed when a polymer solution or a melt having sufficient viscosity is given electrostatic force. Therefore, if the material having a sufficient viscosity, it can be said that general electrospinning is possible. However, for use as a polarizer for polarizing film, polyethylene terephthalate (PET), polycarbonate (PC) polymethyl methacrylate (PMMA), polyethylene naphthalate (PEN) and polystyrene (PS) having excellent viscosity, heat resistance and moisture resistance It is preferably at least one polymer fiber selected from the group consisting of :

In the second step of the manufacturing method of the polarizing film of the present invention, the electrospun nanofibers are wound to form a nanotube pattern on the base film. Hereinafter, a second step of the present invention will be described with reference to FIGS. 1 and 2. 1 is a schematic diagram of a step of forming a nanotube pattern on a base film, which is a second step of the present invention, Figure 2 is a perspective view of the winding roll portion of FIG. 1 and 2, the nanofibers 40 formed by electrospinning at the injection hole 10 of the electrospinning machine are wound on the take-up rolls 20 by the centrifugal force of the take-up rolls 20, and then on the take-up rolls 20. On the base film 50 in which the nanofibers 40 are aligned in the longitudinal direction.

At this time, the electrode 30 is disposed on the winding roll 20 at regular intervals along the longitudinal direction of the winding roll 20, and when a constant voltage is applied to the electrode 30, an electric field is formed between the electrodes. Thus, the nanofibers 40 are arranged at regular intervals along the electric field. At this time, the take-up roll 20 may move in the longitudinal direction of the take-up roll so that the nanotube pattern formed while the nanofiber 40 is wound may be formed at uniform intervals without being overlapped on the base film 50. .

The winding roll 20 is not particularly limited in the spacing between the injection port 10 of the electrospinning machine, but if both are installed as close as possible, the nanofiber discharged from the injection port 10 is immediately wound on the take-up roll 20 It is preferable in that it can be.

In the above, the thickness of the nanofibers can be easily adjusted by the spinning speed in the electrospinning and the winding speed of the take-up roll 20. The thickness of the nanofibers obtained by the electrospinning is preferably 20nm to 1㎛ diameter. The numerical range is a minimum value for showing the properties as a polarizer. When the thickness of the nanofibers is out of the numerical range, the performance of polarization is deteriorated, which is not preferable.

On the other hand, the nanotube pattern is formed in a form in which the nanofibers are aligned in the longitudinal direction on the base film. In this case, the spacing between the nanofibers 40 in the pattern can be easily adjusted according to the strength of the voltage applied to the electrode 30. With respect to the spacing of the nanofibers, the alignment spacing is to be used for polarizing film It is preferable that they are 20 nm-1 micrometer. Uniform polarization performance is realized only when aligned at uniform intervals.

On the other hand, as a material that can be used as the substrate may be used a variety of polymer materials showing transparency in the range of the desired wavelength. These may be amorphous or semicrystalline and may be homopolymers, copolymers or blends thereof. Examples of such polymeric materials include, but are not limited to: poly (carbonate); Syndiotactic and isotactic poly (styrene); C1-C8 alkylstyrene; (Meth) acrylates containing alkyl, aromatic or aliphatic rings, including poly (methylmethacrylate) and poly (methylmethacrylate) copolymers; Ethoxylated and propoxylated (meth) acrylates; (Meth) acrylate of a polyfunctional group; Acrylated epoxy; Epoxy resins; Other unsaturated ethylenic polymers; Copolymers of cyclic olefins and cyclic olefins; Poly (acrylonitrile butadiene styrene); Styrene acryrronitrile copolymers; Poly (vinylcyclohexane); PMMA / poly (vinylfluoride) mixtures; Poly (phenylene oxide) alloys; Styrenic block copolymers; Polyimide; Polysulfones; Poly (vinylchloride); Poly (dimethyl siloxane); Polyurethane; Unsaturated polyesters; Polyethylene, including low birefringence polyethylene; Polypropylene; Poly (alkane terephthalates) such as polyethylene terephthalate; Poly (alkane naphthalate) such as poly (ethylene naphthalate); Polypolyamides; Ionomers; Vinyl acetate / polyethylene copolymers; Cellulose acetate; Cellulose acetate butyrate; Fluorinated polymers; Poly (styrene) and -poly (ethylene) copolymers; Poly (carbonate) / aliphatic PET mixtures and PET / PEN copolymers.

Among the above materials, polyethylene terephthalate, polycarbonate, polymethyl methacrylate, polypropylene, polyethylene, polystyrene, etc., which have high mechanical strength and are excellent in heat resistance, cold resistance, moisture resistance, and the like, are preferable.

The polymer material as described above may be used as a substrate after being molded into a sheet through an extrusion or stretching process, or stretched together with the nanofibers after the nanofiber layer is formed on the substrate.

In the polymer material used as the base material, additives such as weather resistance improving agent, UV absorbing agent, hindered amine light stabilizer, antioxidant, dispersant, lubricant, nucleating agent, antistatic agent, dye or pigment, flame retardant, foaming agent, etc. may be used together as necessary. Can be. The additives may be organic materials such as polymers in the form of beads or particles or nanoparticles, or may be inorganic materials such as glass, ceramics or metal oxide nanoparticles. The surface of the additives may be used with a binder such as a silane coupling agent for bonding the glass to the polymeric material, for example.

The final step in the method of manufacturing a polarizing film of the present invention is the step of stretching the base film is aligned the nanofibers. The stretching is performed for the purpose of increasing the polarization by extending the nanofibers arranged in the pattern shape on the base film in the longitudinal direction. The stretching is performed at a draw ratio of 2 to 8 times, preferably at a draw ratio of 4 to 6 times using a uniaxial stretching machine. If the draw ratio is less than 2 times the polarization characteristics are not implemented, if the draw ratio is more than 8 times, the film may be cracked or cracks occur, and the film may be severely cut.

Hereinafter, the present invention will be described in detail with reference to a preferred embodiment so that those skilled in the art can easily practice the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

[Example]

1. Electrospinning

≪ Example 1 >

15 g of polyethylene terephthalate (PET) polymer was kneaded and dissolved in 85 g of a 50:50 solution of THF (tetrahydrofuran) and DMF (dimethylformamide) for 4 hours. The solution was installed in a solution supply device of an electrospinning apparatus (Mazda, Japan) and spun at a voltage of 10 kv to obtain nanofibers having a thickness of 300 nm.

<Example 2>

15 g of polycarbonate (PC) polymer was added to 85 g of a 50:50 solution of THF and DMF, and dissolved for 4 hours by kneading. A 300nm thickness by radiation by installing the solution in the solution supply of the electrospinning apparatus with a voltage of 12kv is to obtain a nanofiber.

<Example 3>

15 g of polymethyl methacrylate (PMMA) polymer was added to 85 g of a 50:50 solution of THF and DMF, and dissolved by kneading for 6 hours while heating at 60 ° C. The solution is installed in the solution supply device of the electrospinning apparatus and radiated at a voltage of 12 kv to have a thickness of 300 nm Nanofibers were obtained.

<Example 4>

15 g of polyethylene naphthalate (PEN) polymer was added to 85 g of a 50:50 solution of THF and DMF, and dissolved by kneading for 6 hours while heating at 80 ° C. The solution was installed in a solution supply device of an electrospinning apparatus and radiated at a voltage of 12 kv to obtain a nanofiber having a thickness of 300 nm.

Example 5

15 g of polystyrene (PS) polymer was added to 85 g of a 50:50 solution of THF and DMF, and dissolved by kneading for 4 hours. The solution was installed in the solution supply device of the electrospinning apparatus and spun at a voltage of 10 kv to obtain a nanofiber having a thickness of 300 nm.

2, nanotube pattern formation

The fiber spun into nanofibers through the electrospinning is wound on the roll on which the base film located in front of the spinning device is located. The rotational speed of the roll was rotated at a speed of 60 rpm, and a current of 10 mA was supplied to the roll to obtain a substrate in which nanofibers were uniformly aligned at intervals of 300 nm.

3. Stretch

The film of Example 2 was installed in a uniaxial stretching machine and subjected to uniaxial stretching at a draw ratio of 5 times while applying heat at the Tg temperature of the substrate in the direction in which the nanofibers were arranged. The performance of the polarizing film obtained through this is shown in Table 1 below.

TABLE 1

Oriented film properties Polarizing film optical properties Width shrinkage
(%) Width direction
Thickness difference (㎛) Nano Fiber
Thickness (nm) Alignment interval
(Nm) Transmittance
(%) Polarization degree
(%) Example 1 15 <1 284 291 58.5 99.0 Example 2 13 <1 292 290 59.7 99.1 Example 3 14 <1 290 290 61.0 99.1 Example 4 13 <1 292 291 55.6 99.3 Example 5 13 <1 292 290 49.8 99.0

In the above table, shrinkage of 13 to 15 occurred in the direction stretched by uniaxial stretching and in the vertical direction (TD), which affected the shrinkage of the nanofibers and the alignment interval, but the film thickness difference was less than 1 μm and the fiber thickness The alignment interval also contracted uniformly. As a result of measuring the transmittance and the degree of polarization of the performance of the produced polarizing film by a UV meter, it was confirmed that all the polarizing film has a polarization degree of 99% or more.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications can be made within the scope of the technical idea of the present invention, and it is obvious that the present invention belongs to the appended claims. Do.

The polarizing film according to the manufacturing method of the present invention is a small device such as LCD, an electronic calculator, a wristwatch, and the like, and recently, a laptop personal computer, a word process, a liquid crystal color projector, a vehicle navigation system, a liquid crystal television, a personal phone, an indoor and outdoor measuring device, and the like. Can be used as light transmission and / or shielding member

1 is a schematic diagram of a step of forming a nanotube pattern on a substrate film which is a second step of the present invention,

FIG. 2 is a perspective view of a winding roll part of FIG. 1. FIG.

<Description of Signs of Drawings>

10 ... nozzle

20 ... winding roll

30 ... electrode

40 ... Nanofiber

50 ... base film

Claims (14)

Electrospinning the polymer material to obtain nanofibers; Winding the nanofibers while applying an electric field to the roll on which the base film is wound to form a nanotube pattern on the base film; And And stretching the base film in which the nanotubes are aligned. According to claim 1, wherein the polymer material for nanofibers is selected from the group consisting of polyethylene terephthalate (PET), polycarbonate (PC) polymethyl methacrylate (PMMA), polyethylene naphthalate (PEN) and polystyrene (PS) Method for producing the polarizing film, characterized in that at least one polymer fiber. The method of claim 1, wherein the diameter of the electrospun nanofibers is 20 nm to 1 μm in diameter. According to claim 1, wherein the material of the base film is polyethylene terephthalate (PET), polycarbonate (PC), polymethyl methacrylate (PMMA), polypropylene (PP), polyethylene (PE) and polystyrene (PS) Method for producing the polarizing film, characterized in that at least one polymer selected from the group consisting of. The method of claim 1, wherein the pattern is characterized in that the nanofibers are aligned in the longitudinal direction on the base film. The method of claim 5, wherein the pattern has a uniform alignment interval in the longitudinal direction of the nanofibers. The method of claim 6, wherein the alignment interval is 20nm to 1㎛ manufacturing method of the polarizing film. The polarizing film prepared by the method of claim 1, comprising a nanofiber layer attached to one side of the base film and the base film to form a pattern. The method of claim 8, wherein the base film is made of polyethylene terephthalate (PET), polycarbonate (PC), polymethyl methacrylate (PMMA), polypropylene (PP), polyethylene (PE) and polystyrene (PS) The polarizing film, characterized in that at least one polymer selected from the group consisting of. According to claim 8, wherein the nanofibers forming the nanofiber layer is composed of polyethylene terephthalate (PET), polycarbonate (PC) polymethyl methacrylate (PMMA), polyethylene or phthalate (PEN) and polystyrene (PS) The polarizing film, characterized in that at least one polymer fiber selected from the group. The polarizing film of claim 8, wherein the nanofibers have a diameter of 20 nm to 1 μm. The polarizing film of claim 8, wherein the patterns are arranged in the longitudinal direction of the nanofibers on the base film. The polarizing film of claim 12, wherein the pattern has a uniform alignment interval in the longitudinal direction of the nanofibers. The polarizing film of claim 13, wherein the alignment interval is 20 nm to 1 μm.

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