KR101632473B1 - Preparing method for polarizer, polarizer and polarizing plate comprising the same - Google Patents

Abstract

The present invention provides a method for producing a polymer film, comprising: forming a laminate by laminating a polyvinyl alcohol film on at least one surface of a polymer film; Dry-stretching the laminate; And coating an aqueous solution containing a dichroic dye on the polyvinyl alcohol-based film of the stretched laminate and coating the coated film at a temperature of 30 to 80 ° C .; a polarizer and a polarizer produced thereby; And a polarizing plate comprising the same.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarizer, and a method of manufacturing the polarizer. 2. Description of the Related Art Polarizers and Polarizers Using Polarizers, Polarizers and Polariz- ing Plates Comprising the Same,

The present invention relates to a process for producing a polarizer, a polarizer prepared using the same, and a polarizing plate comprising the polarizer, and more particularly, to a process for producing a polarizer capable of improving the process stability, , A method of producing a polarizer capable of producing a thin polarizer, a polarizer manufactured using the polarizer, and a polarizing plate comprising the polarizer.

A polarizer used in a polarizing plate is an optical element for making natural light polarized in a specific direction, and is widely used in liquid crystal display devices and display devices such as organic light emitting devices (OLED). At present, as a polarizer used in the display device, a polyvinyl alcohol polarizing film in which molecular chains containing iodine or a dichroic dye are oriented in a certain direction is generally used. Such a polyvinyl alcohol polarizing film is generally used as a base film A swelling treatment, a cross-linking treatment, a stretching treatment, a cleaning treatment, a drying treatment, and the like, on a polyvinyl alcohol-based film.

On the other hand, in the conventional manufacturing process as described above, it is required that the thickness of the polyvinyl alcohol film before stretching is more than 60 탆 in order to perform stretching without occurrence of breakage. In this case, .

Accordingly, studies have been made to produce a polarizer with a thin thickness while stretching is performed without occurrence of breakage. In this connection, a hydrophilic polymer layer is coated on the base layer, or a base layer forming material and a hydrophilic polymer layer forming material are co- A method of producing a thin polarizing plate by using a laminate produced by the above method has been proposed.

However, in the above production method, the polymer film and the polyvinyl alcohol-based film are easily peeled off or the polymer film and the polyvinyl alcohol-based film are easily peeled off because the polyvinyl alcohol film is immersed in hot water to perform swelling, There is a problem in that process stability is not good, for example, breakage may occur in the alcoholic film or curling may occur in the produced polarizer.

Therefore, a new method for producing a polarizer capable of producing a polarizer excellent in process stability and thin and yet excellent in optical characteristics is required.

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a process for dyeing a polarizer, And further to provide a polarizer capable of producing a polarizer having a thin shape and excellent in optical characteristics, a polarizer produced using the polarizer, and a polarizer comprising the polarizer.

According to an aspect of the present invention, there is provided a method of manufacturing a polymer film, comprising: forming a laminate by laminating a polyvinyl alcohol film on at least one surface of a polymer film; Dry-stretching the laminate; And an aqueous solution containing a dichroic dye on the polyvinyl alcohol-based film of the stretched laminate and drying the solution at a temperature of 30 to 80 캜 And coating the substrate with the polarizer.

At this time, it is preferable to use a heating roll as the coating step.

The dichroic dye concentration of the aqueous solution containing the dichroic dye is preferably 4 to 20% by weight.

The aqueous solution containing the dichroic dye preferably contains iodine and iodide in a weight ratio of 1: 4 to 1:20.

Meanwhile, the aqueous solution containing the dichroic dye may further include a crosslinking agent.

Meanwhile, the polarizer manufacturing method of the present invention may further include a step of coating an aqueous solution containing a cross-linking agent on the polyvinyl alcohol-based film after the coating step and crosslinking.

Meanwhile, the polarizer manufacturing method of the present invention may further include a step of applying an aqueous solution containing a iodide compound onto the polyvinyl alcohol film after the step of coating to complement the polarizer.

On the other hand, the polymer film preferably has a glass transition temperature of 120 캜 or lower.

On the other hand, the dry stretching step is preferably performed uniaxially in the transverse direction (TD) of the laminate.

The dry stretching step is preferably performed at a temperature of (Tg-20) DEG C to (Tg + 60) DEG C, where Tg is the glass transition temperature of the polyvinyl alcohol-based film.

It is preferable that the dry stretching step is performed at a stretching magnification of 4 to 7 times.

In another aspect, the present invention also provides a polarizer produced by the above production method and a polarizing plate comprising the polarizer.

At this time, it is preferable that the thickness of the polarizer produced by the above manufacturing method is 10 탆 or less.

It is also preferable that the polarizers produced by the above-described method have a simple transmittance of 38 to 44% and a polarization degree of 99.8% or more.

Since the polarizer production method of the present invention carries out a dyeing process or the like using a coating process, problems such as peeling between a polymer film and a polyvinyl alcohol film, breakage of a polymer film and a polyvinyl alcohol film, and curling of a polarizer to be produced There is no.

In addition, the polarizer manufacturing method of the present invention can easily swell the polyvinyl alcohol by performing the coating process in a specific temperature range, thereby further improving the efficiency of the dyeing.

In addition, since the method for producing a polarizer according to the present invention uses a laminate in which a polyvinyl alcohol film is laminated on at least one surface of a polymer film, it is possible to produce a polarizer having a thin shape and excellent optical characteristics.

Fig. 1 is a conceptual diagram showing a method of measuring curl of a laminate after drying treatment in the examples and the comparative examples. Fig.

Hereinafter, preferred embodiments of the present invention will be described. However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Further, the embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art.

The inventors of the present invention have conducted extensive studies and have found that when a thin film polarizer is subjected to a dyeing process using a coating method at a specific temperature instead of the dyeing process by immersing it in hot water after stretching, , And further, the dyeing efficiency is excellent, and the present invention has been completed.

More specifically, the polarizer manufacturing method of the present invention includes the steps of: forming a laminate by laminating a polyvinyl alcohol film on at least one surface of a polymer film; Dry-stretching the laminate; And an aqueous solution containing a dichroic dye on the polyvinyl alcohol-based film of the stretched laminate and drying the solution at a temperature of 30 to 80 캜 And coating the substrate.

The polymer film is used to prevent the polyvinyl alcohol film from being broken during the stretching process. The polymer film usable in the present invention is not particularly limited, and examples thereof include a polyurethane film, a polyolefin film, a polyester film, A polyolefin film, a polyamide film, an acrylic film, a high-density polyethylene film, a low-density polyethylene film, a high-density polyethylene and a low-density polyethylene coextruded film, a copolymer resin containing ethylene vinyl acetate in high-density polyethylene, a polyethylene terephthalate- A cellulose-based film or the like can be used.

At this time, the polymer film usable in the present invention preferably has a glass transition temperature of 120 DEG C or lower. If the glass transition temperature of the polymer film is more than 120 캜, it is necessary to stretch at a high temperature of 140 캜 or more for high-magnification stretching. In this case, denaturation of polyvinyl alcohol may occur and the efficiency of the dyeing may decrease. On the other hand, the glass transition temperature can be measured by a differential scanning calorimeter (DSC). For example, in the case of using a differential scanning calorimeter (DSC), when a sample of about 10 mg is sealed in a special pen and heated at a constant temperature, the endothermic heat and the heat generation amount of the material due to the phase change occur, The transition temperature can be measured.

The polyvinyl alcohol film laminated on at least one side of the polymer film may be used without any particular limitation as long as it contains a polyvinyl alcohol resin or a derivative thereof. At this time, derivatives of the polyvinyl alcohol resin include, but are not limited to, polyvinyl formal resins and polyvinyl acetal resins. Alternatively, the polyvinyl alcohol-based film may be a commercially available polyvinyl alcohol-based film commonly used in the art for producing polarizers, such as P30, PE30, PE60 manufactured by Kuraray Co., Ltd., M3000 M6000 manufactured by Nippon Synthetic Chemical Industry Co., .

On the other hand, the polyvinyl alcohol film is not limited to this, but the degree of polymerization is preferably about 1,000 to 10,000, and preferably about 1,500 to 5,000. When the degree of polymerization satisfies the above range, molecular motion is free and can be mixed with iodine or a dichroic dye or the like in a flexible manner.

The polyvinyl alcohol film preferably has a thickness of about 1 to 60 mu m, preferably about 1 to 40 mu m. When the thickness of the polyvinyl alcohol film exceeds 60 탆, it is difficult to realize a thickness of 10 탆 or less even when stretched. When the thickness is less than 1 탆, breakage tends to occur during stretching.

In the present invention, the method of laminating the polymer film and the polyvinyl alcohol film is not particularly limited. For example, an aqueous solution containing a forming material of a polyvinyl alcohol-based film in a polymer film may be coated on a polymer film by a known method such as bar coating, reverse coating, gravure coating, spin coating, screen coating, fountain coating, spray coating, Or the like, followed by drying to obtain a laminate. The forming material of the polymer film and the forming material of the polyvinyl alcohol film are injected into a co-extruder generally used in the related art, and the co-extruded polymer film and the polyvinyl alcohol film are controlled to have an appropriate thickness Whereby a laminate can be obtained.

On the other hand, in the present invention, the polymer film and the polyvinyl alcohol-based film may be attached by weak attraction without forming a separate medium to form a laminate. The adhesive force is 2N / 2 cm or less. Preferably, it is about 0.1 to 1 N / 2 cm or so. When the adhesive force satisfies the above range, the polymer film and the polyvinyl alcohol-based film are not separated during the stretching process, and surface damage in the separation process after stretching can be minimized.

On the other hand, the adhesive force is an adhesive force which is measured when sample films having a width of 2 cm are attached. More specifically, after the polyvinyl alcohol film of the laminate is fixed by a sample holder, a force in a direction perpendicular to the surface direction of the laminate Was used to peel the polyvinyl alcohol film from the polymer film. Peel Strength was measured using a Texture Analyzer (Model: TA-XT Plus) manufactured by Stable Micro Systems.

On the other hand, in order to improve the adhesion between the polymer film and the polyvinyl alcohol film, the surface treatment may be performed on one side or both sides of the polymer film or the polyvinyl alcohol film. At this time, the surface treatment can be carried out through various surface treatment methods well known in the art, for example, corona treatment, plasma treatment or surface modification treatment using a strong base aqueous solution such as NaOH or KOH.

Alternatively, the polymer film and the polyvinyl alcohol-based film may be attached using an adhesive. When the base film and the polyvinyl alcohol film are adhered using an adhesive, the thickness of the adhesive layer is preferably about 20 to 4000 nm. When the thickness of the adhesive layer satisfies the above range, it is advantageous to peel off the polyvinyl alcohol-based film after the stretching and drying process without damage.

On the other hand, the adhesive should have an adhesive force (adhesive force) of 2 N / 2 cm or less, and its material is not particularly limited, and various adhesives known in the art can be used without limitation. For example, the adhesive layer may be formed of an aqueous adhesive or an ultraviolet curable adhesive.

When a laminate is formed by laminating a polyvinyl alcohol film on a polymer film, the laminate is stretched. In the case of the present invention, the above stretching is performed by dry stretching rather than wet stretching, and the purpose and effect of the present invention, which performs a sanding process by coating rather than a dipping process by performing dry stretching instead of wet stretching, Can be maximized.

On the other hand, the dry stretching is usually carried out by uniaxial stretching. This uniaxial stretching can be carried out with respect to the longitudinal direction (MD) of the laminate, or with respect to the transverse direction (TD) of the laminate. Also, longitudinal (MD) shrinkage may be caused by simultaneous biaxial stretching of the laminate in the transverse direction (TD). On the other hand, the transverse (TD) stretching method of the laminate is, for example, a fixed one uniaxial stretching method in which one end is fixed through a tenter, and the longitudinal (MD) stretching Examples of the method include an inter-roll stretching method, a compression stretching method, and a free-end uniaxial stretching method. On the other hand, the stretching treatment may be carried out in multiple stages, or by biaxial stretching, warp stretching, or the like.

On the other hand, in the case of the present invention, it is more preferable that the dry stretching is uniaxially stretched in the transverse direction (TD) of the laminate. In the case of uniaxially stretching in the machine direction (MD), in the case of attaching a brightness enhancement film or the like to a polarizing plate including a polarizer to be produced, the transmissive axes are formed in directions perpendicular to each other. And a roll-to-sheet process in which the transmission axes coincide with each other have been applied. However, in this case, there is a problem that it is difficult to match the transmission axis, and further, since a cutting process is further required, productivity is lowered. However, in the case of uniaxially stretching in the transverse direction (TD), it is easy to align the transmission axes and the lamination can be continuously performed by a roll-to-roll method, .

On the other hand, in the stretching step, the laminate is preferably stretched at a stretching magnification of 4 to 7 times. When the stretching magnification exceeds 7 times, breakage may occur during stretching. When the stretching magnification is lower than 4 times, the degree of orientation of the polymer decreases and the degree of polarization of the polarizer produced may be lowered.

The stretching may be performed at a temperature of (Tg-20) DEG C to (Tg + 60) DEG C, where Tg is the glass transition temperature of the polyvinyl alcohol-based film. For example, in general, the glass transition temperature of the polyvinyl alcohol-based film is about 80 ° C, and the stretching can be performed at a temperature of 60 ° C to 140 ° C. If the stretching is carried out at the temperature in the above range, the possibility of breakage of the polymer film or breakage of the polyvinyl alcohol film is low.

After the laminate is stretched, an aqueous solution containing a dichroic dye is coated on the polyvinyl alcohol-based film of the stretched laminate, followed by coating. In the present invention, a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based film by coating the dichroic dye. Further, by performing the dipping treatment after the stretching treatment as described above, the dichroic dye can be more suitably adsorbed and oriented on the polyvinyl alcohol-based film.

At this time, the coating method may be a coating method such as a coating method, a roll coating method, a spin coating method, a printing method, a blade coating method and the like widely known in the art. However, Preferably 40 to 70 DEG C, and particularly preferably 45 to 65 DEG C. More specifically, in the coating method widely known in the art, the coating is carried out while applying heat to the laminate at 30 to 80 캜, more preferably 40 to 70 캜, particularly preferably 45 to 65 캜. In this case, the heat of the temperature range is transferred to the laminate, so that swelling of the polyvinyl alcohol can easily occur, and as a result, the efficiency of the dyeing can be increased. On the other hand, when the coating is carried out at a temperature of less than 30 캜, when the thickness of the polyvinyl alcohol-based film after stretching is about 4 탆 or more, the polarization efficiency of the polarizer produced is poor, When the coating is carried out under the temperature condition of < RTI ID = 0.0 > 100 C, < / RTI > the excessively high heat is applied. Meanwhile, in the coating method, water is generally used as a solvent, and an organic solvent having good compatibility with water may be further added.

On the other hand, in the coating step, the method of applying heat to the laminate in the temperature range is not particularly limited. For example, a hot air nozzle or the like may be separately installed in the coating process to apply heat to the laminate, or heat may be applied to the laminate using a heating roll. Among them, it is particularly preferable to apply heat to the laminate by using a heating roll. In case of heating using a hot air nozzle, a change in the concentration of the salt solution may be caused by hot air, and due to the flow of hot air, the appearance of the film may be poor and nonuniformity may be caused. However, This is because the problem does not occur in the case of giving.

On the other hand, the method using the heating roll is not particularly limited as long as it can apply the heat of the temperature range to the stretched laminate in the coating process. For example, in a general coating process, a coating process may be carried out using a heating roll heated to the above-mentioned temperature range, or a heating guide roll heated to the above temperature range may be added to the rear end in a general coating process So that the efficiency of the dyeing can be increased. On the other hand, the method of heating the roll is not particularly limited, and can be heated by methods well known in the art.

On the other hand, when the coating process is carried out using a heating roll heated to the above-mentioned temperature range in the general coating process, the heat transfer to the stretched laminate can be carried out by heating the polyvinyl alcohol film of the polymer film It is more preferable to carry out through the opposite surface of the substrate. This is because when the heating roll is in contact with the surface of the polyvinyl alcohol-based film to transmit heat, there is a possibility that the problem of appearance defects of the produced polarizer may be caused.

On the other hand, in the aqueous solution containing the dichroic dye, the concentration of the dichroic dye is preferably 4 to 20 wt%, more preferably 5 to 15 wt%, and particularly preferably 7 to 12 wt% . If the concentration of the dichroic dye is less than 4% by weight, the efficiency of the dyeing is lowered and the polarization efficiency may be lowered. If the concentration exceeds 20% by weight, the dye may be overbased to decrease the transmittance.

On the other hand, the dichroic dye is not particularly limited as long as it is used in the art in the production of a polarizer, and for example, iodine or an organic dye can be used. Examples of the organic dyes include red BR, red LR, red R, pink LB, rubin BL, Borde GS, sky blue LG, lemon yellow, blue BR, blue 2R, navy RY, green LG, violet LB, violet B , Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Brilliant Violet BK, Supra Blue G, Supra Blue GL, Supra Orange GL, , Direct First Orange S, First Black, and the like can be used.

On the other hand, in the case of the present invention, iodine is more preferably used as the dichroic dye, and iodine and iodide are preferably used together. In this case, the efficiency of the dyeing can be further improved.

Examples of the iodide compound include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide and titanium iodide. Of these, potassium iodide is particularly preferable. In this case, the weight ratio of iodine and iodide compound is preferably in the range of 1: 4 to 1:20, more preferably in the range of 1: 5 to 1:15, in the range of 1: 7 to 1:12 Is particularly preferable. When the weight ratio of iodine and iodide compound satisfies the above range, the optical characteristics of the polarizer produced are more excellent.

Meanwhile, in the polarizer manufacturing method of the present invention, an aqueous solution containing a crosslinking agent is coated on a polyvinyl alcohol-based film to fix the dichroic dye adsorbed and oriented on the polyvinyl alcohol-based film after the coating step, Step < / RTI > As described above, the crosslinking step of the present invention can also be carried out by a coating method rather than an immersion method.

At this time, the method of applying the aqueous solution containing the crosslinking agent may be carried out by a coating method well known in the art. For example, the method can be carried out by coating an aqueous solution containing a crosslinking agent on a polyvinyl alcohol-based film by a coating method such as a bar coating method, a roll coating method, a spin coating method, a printing method, a blade coating method, It is also possible to carry out the coating at a temperature of 30 to 80 DEG C, more preferably 40 to 70 DEG C, particularly preferably 45 to 65 DEG C by using a heating roll or the like particularly as in the step of dying the dichroic dye. As the solvent, water is generally used, and an organic solvent having good compatibility with water may be further added.

On the other hand, in the aqueous solution containing the crosslinking agent, the concentration of the crosslinking agent is preferably 0.5 to 5% by weight, more preferably 0.6 to 4% by weight, and particularly preferably 1 to 3% by weight. If the concentration of the cross-linking agent is less than 0.5% by weight, the amount of the cross-linking agent can be easily dissolved in water because of the small amount of cross-linking. This is because the crosslinking agent may precipitate on the surface of the film to cause surface contamination.

As the crosslinking agent, conventionally known materials may be used. Boron compounds such as boric acid and sodium borate, and glyoxal or glutaraldehyde. These compounds may be used alone or in combination. Among them, boric acid is particularly preferably used.

On the other hand, an iodide compound may be further added to the aqueous solution containing the crosslinking agent. Examples of such iodine compounds include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide and titanium iodide. Of these, potassium iodide desirable.

Meanwhile, in order to prevent the color change of the dichroic dye adsorbed and oriented on the polyvinyl alcohol film after the coating step, an aqueous solution containing a iodide compound is coated on the polyvinyl alcohol film And a step of complementing the image. As such, in the case of the present invention, the step of complementing can be performed by a coating method instead of the immersion method. At this time, the color change is generally caused by the step of crosslinking, and the step of complementing is preferably performed after the step of crosslinking.

At this time, in the complementary color step, the method of applying the aqueous solution containing the iodide compound may be performed by a coating method well known in the art. For example, the method can be carried out by coating an aqueous solution containing a iodide compound on a polyvinyl alcohol film using a coating method such as a bar coating method, a roll coating method, a spin coating method, a printing method, a blade coating method, The coating may be carried out at a temperature of 30 to 80 DEG C, more preferably 40 to 70 DEG C, and particularly preferably 45 to 65 DEG C, using a heating roll or the like particularly as in the step of dying the dichroic dye. As the solvent, water is generally used, and an organic solvent having good compatibility with water may be further added.

On the other hand, in the complementary coloring step, the concentration of the iodide compound in the aqueous solution containing the iodide compound is preferably 1 to 10 wt%, more preferably 3 to 8 wt%, and particularly preferably 4 to 6 wt% desirable. When the concentration of the iodide compound is less than 1% by weight, the effect is insufficient and the polyvinyl alcohol film becomes blue light due to the color change of the dichroic dye. When the concentration of the iodide compound exceeds 10% by weight, Is too high to cause the polyvinyl alcohol-based film to become reddish.

Examples of the iodide compound include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide and titanium iodide. Among them, potassium iodide is particularly preferable.

In the case of the present invention, the dyeing, crosslinking, and complementary color treatments may be carried out as described above. However, the present invention is not limited thereto, and the dyeing, crosslinking and complementary treatments may be performed simultaneously. More specifically, in the case of the present invention, after the laminate is stretched, an aqueous solution containing a dichroic dye further containing a crosslinking agent is applied on the polyvinyl alcohol film of the stretched laminate, The dyeing, crosslinking and complementary treatment may be performed at the same time.

The coating method may be a coating method such as a coating method, a roll coating method, a spin coating method, a printing method, and a blade coating method, which are well known in the art, as described above. Preferably at 40 to 70 DEG C, particularly preferably at 45 to 65 DEG C. Further, water is generally used as a solvent, and an organic solvent having good compatibility with water may be further added.

The method of applying the heat satisfying the temperature range to the stretched laminate in the coating step as described above is not particularly limited, but it is particularly preferable to apply heat by using a heating roll Do.

Further, as described above, the method using the heating roll is not particularly limited as long as it can apply heat to the stretched laminated body using a heat-treated roll and satisfies the temperature range described above. For example, In the method, the heating efficiency can be improved by using a heating roll heated to the above-mentioned temperature range, or a heating guide roll heated to the above temperature range at the rear end in a general coating process is additionally provided, It can also increase efficiency.

As described above, in the case of using the heating roll as described above, when the polyvinyl alcohol film is laminated only on one side of the polymer film, the heat transfer to the stretched laminate is performed by using a polyvinyl alcohol film Is carried out through the opposite surface of the laminated surface.

In the aqueous solution containing the dichroic dye, the concentration of the dichroic dye is preferably 4 to 20% by weight, more preferably 5 to 15% by weight, and more preferably 7 to 12% by weight, Is particularly preferable.

The weight ratio of the iodine and the iodide compound is preferably 1: 4 to 1: 1, more preferably 1: 2 to 1: 1, more preferably 1: 1: 20, more preferably in the range of 1: 5 to 1:15, and particularly preferably in the range of 1: 7 to 1: 12.

In the aqueous solution containing the dichroic dye, the concentration of the crosslinking agent is preferably from 0.5 to 5% by weight, more preferably from 0.6 to 4% by weight, and more preferably from 1 to 3% by weight Particularly preferred.

In addition, as described above, the crosslinking agent can be used alone or in combination with conventionally known materials, and it is particularly preferable to use boric acid.

Meanwhile, the polarizer manufacturing method of the present invention may further include, after the coating step, cleaning the laminate to remove unnecessary residues deposited on the surface of the polyvinyl alcohol-based film as needed. In the case of the present invention, since the dyeing and crosslinking treatment are performed by the coating process, there is an advantage that the amount of unnecessary residue deposited is smaller than in the case of performing the dyeing and crosslinking treatment by the conventional immersion process, Not necessary.

On the other hand, the cleaning step may be performed by applying an aqueous solution containing a cleaning agent onto a polyvinyl alcohol-based film using a coating method well-known in the art. The present invention also carries out a step of cleaning by a coating method rather than a dipping method, even if it is subjected to a cleaning step as necessary. In this case, the washing step is not particularly limited in the order of the drying step to be described later. At this time, water or an iodide compound may be used as the cleaning agent.

On the other hand, in the cleaning step, when the cleaning agent is an iodide compound, the concentration of the iodide compound in the aqueous solution containing the iodide compound is preferably 1 to 10 wt%, more preferably 3 to 8 wt% , And 4 to 6% by weight. Examples of the iodide compound include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide and titanium iodide. Of these, Potassium is preferred.

Meanwhile, the polarizer manufacturing method of the present invention may further include drying the laminate after the coating. In this case, the drying is preferably performed at a temperature of about 20 to 100 ° C, more preferably about 40 to 90 ° C, in consideration of the optical characteristics of the polarizer, and the drying time is preferably 1 to 10 Min. The drying process is to prevent the deterioration of the physical properties of the polyvinyl alcohol polarizer due to moisture during the production process of the polarizer through the removal of water on the surface and inside of the polyvinyl alcohol and to smooth the width shrinkage of the stretched polyvinyl alcohol film during the drying process Thereby enhancing the polarizability of the polarizer by increasing the orientation of the complex composed of polyvinyl alcohol and iodine. At this time, it is preferable that the drying step is carried out after performing the dyeing, crosslinking, complementary treatment, and the like.

In addition, the polarizer manufacturing method of the present invention may further include separating the polyvinyl alcohol-based film from the polymer film after the drying step, if necessary. That is, in the present invention, the polymer film may be used as it is as a polarizer protective film, or may not be peeled off. Meanwhile, in the separation step, when the polymer film and the polyvinyl alcohol-based film are adhered to each other by a weak attraction or adhesive and laminated, a weak peeling force may be applied to the polyvinyl alcohol-based film to separate the polymer film and the polyvinyl alcohol film from the polymer film. At this time, the peeling force is preferably 2 N / 2 cm or less, for example, about 0.1 to 2 N / 2 cm and 0.1 to 1 N / 2 cm. In this case, since the peeling force required to separate the polyvinyl alcohol film and the polymer film from each other is very weak compared with the case where the film is laminated using the coating or coextrusion, the two films can be easily separated without any process or equipment, The damage of the polyvinyl alcohol-based film is small in the process, and it is possible to have excellent optical performance.

The polarizer of the present invention produced by the above-described method has a thickness of 10 μm or less, preferably about 2 to 10 μm. Even with such a thin thickness, the single-layer transmittance is about 38 to 44%, and the degree of polarization is 99.8% or more, which shows excellent optical properties.

The present invention also provides a polarizer comprising the polarizer of the present invention produced by the above production method. That is, a polarizing plate can be formed by laminating a transparent film on one side or both sides of the polarizer of the present invention. As the transparent film, various films used as a polarizer protective film or a retardation film in the related art can be used without limitation. For example, a cellulose film, an acrylic film, a cycloolefin film, or the like can be used.

The method of laminating the polarizer and the transparent film is not particularly limited, and may be performed using an adhesive or a pressure sensitive adhesive well-known in the art. In this case, the pressure-sensitive adhesive or the adhesive may be appropriately selected in consideration of the material of the transparent film to be used. For example, when TAC is used as the transparent film, an aqueous adhesive such as a polyvinyl alcohol- When an acrylic film or a cycloolefin-based film is used as the transparent film, a photo-curable or thermosetting adhesive such as an acrylic adhesive or an epoxy adhesive can be used.

Hereinafter, the present invention will be described in more detail with reference to specific examples.

Example  One

A polyvinyl alcohol-based film (Nippon Synthetic Chemical Co., NH-26, Tg = 80 ° C) was dissolved in water to prepare a polyvinyl alcohol aqueous solution. The polyvinyl alcohol-based aqueous solution was coated on a polyethylene terephthalate film (Mitsubishi Plastics, SG-007, Tg = 80 캜, 150 탆) and dried to produce a laminate having a polyvinyl alcohol coating film having a thickness of 10 탆 Respectively.

The laminate was dry-drawn at a stretching magnification of 5 times in the machine direction (MD) by uniaxial free-end drawing at a temperature of 100 캜. The thickness of the polyvinyl alcohol-based film after stretching was 4.6 mu m.

Next, an aqueous solution containing 7% by weight of a dichroic dye (iodine: potassium iodide = 1: 10) was coated on the polyvinyl alcohol film of the stretched laminate using a bar coating method at a temperature of 60 ° C . More specifically, the laminate was passed through a heating roll using a bar coating method so that a heating roll heated to 60 占 폚 was contacted with a polyethylene terephthalate film, and coating treatment was conducted so that heat of 60 占 폚 was transferred to the laminate. Thereafter, an aqueous solution containing 1% by weight of boric acid was coated on the polyvinyl alcohol film using a bar coating method and subjected to crosslinking treatment. Thereafter, an aqueous solution containing 5% by weight of potassium iodide was coated on a polyvinyl alcohol film using a bar coating method to perform a complementary treatment.

Next, the laminate was dried in an oven at 80 캜 for 60 seconds, and after drying, the polyvinyl alcohol film was peeled from the polymer film to finally produce a polarizer having a thickness of 4.6 탆.

Example  2

A polarizer was produced in the same manner as in Example 1 except that the thickness of the polyvinyl alcohol-based film was 20 μm and the thickness of the polyvinyl alcohol-based film after stretching was 9.5 μm. Respectively. The final thickness of the prepared polarizer was 9.5 mu m.

Example  3

The procedure of Example 1 was repeated except that the thickness of the polyvinyl alcohol film was 15 탆 and the thickness of the polyvinyl alcohol film after stretching was 8.7 탆 and the concentration of the dichroic dye was 5 wt% Polarizers were prepared under the same conditions and in the same manner as in Example 1. The final thickness of the prepared polarizer was 8.7 mu m.

Example  4

In Example 3, an aqueous solution (iodine 1 wt%, potassium iodide 7 wt%, boric acid 1 wt%) containing iodine: potassium iodide: boric acid in a ratio of 1: 7: 1 was used A polarizer was produced under the same conditions and in the same manner as in Example 3, except that the film was coated on the polyvinyl alcohol film of the stretched laminate to simultaneously perform dyeing, crosslinking, and complementary color processing. The final thickness of the prepared polarizer was 8.7 mu m.

Example  5

A polyvinyl alcohol-based film (Nippon Synthetic Chemical Co., NH-26, Tg = 80 ° C) was dissolved in water to prepare a polyvinyl alcohol aqueous solution. The polyvinyl alcohol aqueous solution was coated on a polyolefin film (RnF, CPP, MPL-2, Tg = -20 ° C) and dried to prepare a laminate having a polyvinyl alcohol coating film having a thickness of 20 μm.

The laminate was dry-drawn at a stretching magnification of 5 times in the machine direction (MD) by uniaxial free-end drawing at a temperature of 100 캜. The thickness of the polyvinyl alcohol-based film after stretching was 12.2 占 퐉.

Next, an aqueous solution containing 7% by weight of a dichroic dye (iodine: potassium iodide = 1: 10) was coated on the polyvinyl alcohol film of the stretched laminate using a bar coating method at a temperature of 60 ° C . More specifically, using a bar coating method, the laminate was passed through a heating roll so that a heating roll heated to 60 ° C was brought into contact with the polyolefin film, and the laminate was coated so that heat of 60 ° C was transferred to the laminate. Thereafter, an aqueous solution containing 1% by weight of boric acid was coated on the polyvinyl alcohol film using a bar coating method and subjected to crosslinking treatment. Thereafter, an aqueous solution containing 5% by weight of potassium iodide was coated on a polyvinyl alcohol film using a bar coating method to perform a complementary treatment.

Next, the laminate was dried in an oven at 80 캜 for 60 seconds, dried, and then the polyvinyl alcohol film was peeled off from the polymer film to finally produce a polarizer having a thickness of 12.2 탆.

Example  6

The polarizer was manufactured in the same manner as in Example 5, except that the thickness of the polyvinyl alcohol-based film was 15 탆 and the thickness of the polyvinyl alcohol-based film after stretching was 8.5 탆. Respectively. The final thickness of the prepared polarizer was 8.5 탆.

Example  7

In Example 5, the thickness of the polyvinyl alcohol film was coated at 15 占 퐉, and the laminate was uniaxially dry-stretched at a stretching magnification of 5 times in the transverse direction (TD) at a temperature of 100 占 폚 using a tenter to obtain polyvinyl A polarizer was produced under the same conditions and in the same manner as in Example 5 except that the thickness of the alcohol-based film was 3.5 탆. The final thickness of the prepared polarizer was 3.5 탆.

Comparative Example  One

A polyvinyl alcohol-based film (Nippon Synthetic Chemical Co., NH-26, Tg = 80 ° C) was dissolved in water to prepare a polyvinyl alcohol aqueous solution. The polyvinyl alcohol-based aqueous solution was coated on a polyethylene terephthalate film (Mitsubishi Plastics, SG-007, Tg = 80 캜, 150 탆) and dried to produce a laminate having a polyvinyl alcohol coating film having a thickness of 10 탆 Respectively.

The laminate was dry-drawn at a stretching magnification of 5 times in the machine direction (MD) by uniaxial free-end drawing at a temperature of 100 캜. The thickness of the polyvinyl alcohol-based film after stretching was 6.4 占 퐉.

And the layered product subjected to the stretching treatment was immersed in an aqueous solution containing 4% by weight of a dichroic dye (iodine: potassium iodide = 1: 10). Thereafter, the above-mentioned laminate was immersed in an aqueous solution containing 1% by weight of boric acid and crosslinked. Thereafter, the laminate was immersed in an aqueous solution containing 5% by weight of potassium iodide to perform complementary treatment.

Next, the laminate was dried in an oven at 80 캜 for 60 seconds, and after drying, the polyvinyl alcohol film was peeled off from the polymer film to finally produce a polarizer having a thickness of 6.4 탆.

Comparative Example  2

A polarizer was produced in the same manner as in Example 2 except that the temperature of the heating roll was 25 ° C. The final thickness of the prepared polarizer was 9.6 mu m.

Comparative Example  3

A polarizer was produced in the same manner as in Example 2 except that the temperature of the heating roll was 90 ° C. The final thickness of the prepared polarizer was 9.4 占 퐉.

Comparative Example  4

Example 5 was prepared in the same manner as in Example 5 except that the thickness of the polyvinyl alcohol film was 20 탆 and the thickness of the polyvinyl alcohol film after stretching was 8.8 탆 and the temperature of the heating roll was 25 캜. Polarizers were prepared under the same conditions and methods. The final thickness of the prepared polarizer was 8.8 mu m.

Comparative Example  5

Example 5 was prepared in the same manner as in Example 5 except that the thickness of the polyvinyl alcohol film was 15 占 퐉 and the thickness of the polyvinyl alcohol film after stretching was 7.6 占 퐉 and the temperature of the heating roll was 90 占 폚 Polarizers were prepared under the same conditions and methods. The final thickness of the prepared polarizer was 7.6 mu m.

Experimental Example  One

In Examples 1 to 6 and Comparative Examples 1 to 5, the degree of peeling of the polyvinyl alcohol-based film from the polymer film due to breakage in the polymer film during the dyeing process was measured and is shown in Table 1 below. More specifically, Examples 1 to 6 and Comparative Examples 1 to 5 were repeated five times each time, and the number of times of occurrence of breakage and peeling after the dyeing process was visually judged to be?, 0 in case of 0, and? , And X for three or more times.

Experimental Example  2

In Examples 1 to 6 and Comparative Examples 1 to 5, the degree of curling of the laminate before peeling of the polarizer after the dyeing and drying treatment was measured and is shown in Table 1 below. More specifically, as shown in Fig. 1, the laminate is placed on a horizontal glass substrate with the polarizer facing upward, and the distance H from the top or bottom of the curved portion of the laminate to the end of the laminate is measured using a steel ruler Respectively.

division Polymer film Staining process Breaking and peeling Curl (mm) Example 1 PET film Coating process ◎ 17 Example 2 Coating process ◎ 17 Example 3 Coating process ◎ 16 Example 4 Coating process ◎ 15 Example 5 PO-based film Coating process ◎ 11 Example 6 Coating process ◎ 14 Example 7 Coating process ◎ 13 Comparative Example 1 PET film Immersion process X 35 Comparative Example 2 Coating process ◎ 15 Comparative Example 3 Coating process ○ 14 Comparative Example 4 PO-based film Coating process ◎ 17 Comparative Example 5 Coating process ○ 25 PET: polyethylene terephthalate, PO: polyolefin

As can be seen from Table 1, in Comparative Example 1 in which the dipping process was carried out by the dipping process as in the prior art, the process stability was not good. Also, it was found that the curl of the laminate .

However, in the case of the embodiments in which the dyeing process is performed by the coating process as in the present invention, the process stability is excellent and the curl of the laminate to be produced is also at a good level.

Experimental Example  3

Optical properties of the polarizers prepared in Examples 1 to 6 and Comparative Examples 1 to 5 were measured with a V-7100 spectrophotometer equipped with an automatic polarizing film analyzer VAP-7070 manufactured by JASCO, and are shown in Table 2 below

division Polymer
film Roll heating
Temperature
(° C) After stretching
PVA thickness
(탆) Dichroism
Dye concentration
(weight%) Boric acid concentration
(weight%) Yo-yo
Potassium concentration
(weight%) group
Permeability
(%) Polarization degree
(%) Example 1 PET system
film 60 4.6 7 One 5 42.5 99.9 Example 2 60 9.5 7 One 5 42.5 99.9 Example 3 60 8.7 5 One 5 42.7 99.9 Example 4 60 8.7 [I ₂ / KI / BA = 1: 7: 1] 42.6 99.9 Example 5 PO system
film 60 12.2 7 One 5 43.2 99.8 Example 6 60 8.5 7 One 5 43.2 99.8 Example 7 60 3.5 7 One 5 39.8 99.9 Comparative Example 1 PET system
film - 6.4 4 (immersion) 1 (immersion) 5 (immersion) 42.7 99.8 Comparative Example 2 25 9.6 7 One 5 44.5 97.5 Comparative Example 3 90 6.4 7 One 5 32.5 99.9 Comparative Example 4 PO system
film 25 8.8 7 One 5 47.5 94.5 Comparative Example 6 90 7.6 7 One 5 33.9 99.8 PVA: polyvinyl alcohol, PET: polyethylene terephthalate, PO: polyolefin,
I ₂ : iodine, KI: potassium iodide, BA: boric acid

As shown in Table 2, in Comparative Examples 2 and 4 in which the temperature of the heating roll was lower than 30 ° C and the dichroic dye coating was performed at a low temperature, the polarization efficiency of the polarizer produced was poor due to low efficiency of the dyeing . Further, in the case of Comparative Examples 3 and 6 in which the temperature of the heating roll is higher than 80 DEG C and the dye coating of dichroic dyes is carried out at an excessively high temperature, the temperature of the heat to be transferred is too high and the polarity of the produced polarizer is rather poor Able to know.

However, in Examples 1 to 6 in which the temperature of the heating roll was 60 ° C and the dyeing coating was carried out under appropriate temperature conditions, the polyvinyl alcohol swelled easily and the dyeing efficiency was excellent. As a result, Is very excellent as in the case of the polarizer produced by the conventional immersion.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be obvious to those of ordinary skill in the art.

F:
H: distance from the lowest or lowest end of the curved portion of the laminate to the end portion of the laminate

Claims (15)

Laminating a polyvinyl alcohol film on at least one side of the polymer film to form a laminate;
Dry-stretching the laminate; And
An aqueous solution containing a dichroic dye is applied onto the stretched polyvinyl alcohol film of the laminate, and the film is dried at a temperature of 50 to 70 캜 Coating;
/ RTI >
Wherein the coating is performed using any one selected from the group consisting of a bar coating method.
delete The method according to claim 1,
Wherein the dichroic dye concentration of the aqueous solution containing the dichroic dye is 4 to 20 wt%.
The method according to claim 1,
Wherein the aqueous solution containing the dichroic dye contains iodine and iodide at a weight ratio of 1: 4 to 1:20.
The method according to claim 1,
Wherein the aqueous solution containing the dichroic dye further comprises a crosslinking agent.
The method according to claim 1,
Further comprising a step of applying an aqueous solution containing a cross-linking agent onto the polyvinyl alcohol-based film after the coating step and then crosslinking.
The method according to claim 1,
Further comprising the step of applying an aqueous solution containing an iodide compound onto the polyvinyl alcohol-based film to complement the polarizing film after the coating step.
The method according to claim 1,
Wherein the polymer film has a glass transition temperature of 80 to 120 占 폚.
The method according to claim 1,
Wherein the dry stretching step is uniaxially stretched in the transverse direction (TD) of the laminate.
The method according to claim 1,
Wherein the dry stretching step is performed at a temperature of (Tg-20) DEG C to (Tg + 60) DEG C, where Tg is the glass transition temperature of the polyvinyl alcohol-based film.
The method according to claim 1,
Wherein the dry stretching step is performed at a draw magnification of 4 to 7 times.
delete delete delete delete

Images