WO2014204143A1 - Method for manufacturing thin polarizer, and thin polarizer and polarizing plate manufactured using same - Google Patents

Method for manufacturing thin polarizer, and thin polarizer and polarizing plate manufactured using same Download PDF

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Publication number
WO2014204143A1
WO2014204143A1 PCT/KR2014/005231 KR2014005231W WO2014204143A1 WO 2014204143 A1 WO2014204143 A1 WO 2014204143A1 KR 2014005231 W KR2014005231 W KR 2014005231W WO 2014204143 A1 WO2014204143 A1 WO 2014204143A1
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WO
WIPO (PCT)
Prior art keywords
film
polyvinyl alcohol
unstretched
stretching
laminate
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PCT/KR2014/005231
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French (fr)
Korean (ko)
Inventor
남성현
정종현
나균일
유혜민
Original Assignee
주식회사 엘지화학
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Priority claimed from KR1020140067603A external-priority patent/KR101584441B1/en
Application filed by 주식회사 엘지화학 filed Critical 주식회사 엘지화학
Priority to US14/385,935 priority Critical patent/US9645293B2/en
Priority to CN201480000906.1A priority patent/CN104395789B/en
Publication of WO2014204143A1 publication Critical patent/WO2014204143A1/en

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
    • G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
    • G02B5/3041—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks
    • G02B5/305—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks including organic materials, e.g. polymeric layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B32B27/306—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising vinyl acetate or vinyl alcohol (co)polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B32B27/308—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising acrylic (co)polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/36—Layered products comprising a layer of synthetic resin comprising polyesters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/40—Properties of the layers or laminate having particular optical properties
    • B32B2307/402—Coloured
    • B32B2307/4026—Coloured within the layer by addition of a colorant, e.g. pigments, dyes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2457/00—Electrical equipment
    • B32B2457/20—Displays, e.g. liquid crystal displays, plasma displays

Definitions

  • the present invention relates to a method of manufacturing a thin polarizer, a thin polarizer and a polarizing plate manufactured using the same, and more particularly, a method of manufacturing a thin polarizer having a thin thickness of 10 ⁇ m or less, a thin polarizer and a polarizing plate manufactured using the same. It is about.
  • the polarizer used in the polarizing plate is an optical element for making natural light or arbitrary polarization into a polarized light in a specific direction, and is widely used in a display device such as a liquid crystal display device and an organic light emitting device (OLED).
  • a polarizer used in the display device a polyvinyl alcohol polarizing film in which molecular chains containing an iodine compound or a dichroic dye are oriented in a constant direction is generally used.
  • the polyvinyl alcohol polarizing film is prepared by a method of dyeing and crosslinking iodine or dichroic dye on a polyvinyl alcohol-based film, and stretching in a predetermined direction, wherein the stretching process is an aqueous solution of boric acid or an iodine solution. Wet drawing carried out in solution or dry drawing carried out in air, and the like, and the draw ratio is generally at least 5 times.
  • stretching exceeds 60 micrometers.
  • polarizers are also required to have a thinner thickness.
  • a polyvinyl alcohol-based film having a thickness before stretching of more than 60 ⁇ m as in the prior art there is a limit in reducing the thickness of the polarizer. Therefore, studies have been attempted to fabricate thinner polarizers.
  • Korean Unexamined Patent Publication No. 2010-0071998 discloses a method of manufacturing a thin polarizing plate using a laminate prepared by coating a hydrophilic polymer layer on a substrate layer or co-extrusion of a substrate layer forming material and a hydrophilic polymer layer forming material. It is.
  • the separation of the polyvinyl alcohol layer and the base layer is not easy after stretching and a high peel force is required for the separation, the polyvinyl alcohol layer is damaged or deformed during the separation process. Problems tend to occur, and as a result, there is a problem that optical properties such as polarization degree of the polyvinyl alcohol film are inferior.
  • the polyvinyl alcohol resin is manufactured by melting and extruding the polyvinyl alcohol resin or by applying the coating solution after coating and then applying the polyvinyl alcohol according to extrusion conditions, coating conditions or film forming conditions.
  • the physical properties of the film tend to change, and not only the physical properties of the finally produced polyvinyl alcohol are lowered, but also it is difficult to realize uniform physical properties.
  • the present invention is to solve the above problems, to provide a method of manufacturing a polarizer having a thin thickness while having excellent process stability of the manufacturing method, excellent optical properties.
  • the present invention provides a method of manufacturing a thin polarizer comprising the step of stretching the film laminate so as to and the step of separating the polymer film and the polyvinyl alcohol-based film of the stretched film laminate.
  • the film laminate is a first unstretched polymer film, a first unstretched polyvinyl alcohol-based film attached to the first unstretched polymer film, and a second unstretched polyvinyl alcohol-based film attached to the film It may be made of an unoriented polymer film.
  • the film laminate is a first unstretched polymer film, a first unstretched polyvinyl alcohol-based film adhered on the first unstretched polymer film, the first unstretched polyvinyl alcohol-based film A second unstretched polymer film, a second unstretched polyvinyl alcohol-based film attached to the second unstretched polymer film, and a third unstretched polymer film attached to the second unstretched polyvinyl alcohol-based film. have.
  • the unstretched polymer film has a maximum draw ratio of 5 times or more, preferably 5 times to 15 times, in a temperature range of 20 ° C. to 85 ° C., for example, a high density polyethylene film or polyurethane Film, polypropylene film, polyolefin film, ester film, low density polyethylene film, high density polyethylene and low density polyethylene coextrusion film, copolymer resin film containing ethylene vinyl acetate in high density polyethylene, acrylic film, polyethylene terephthalate film, polyvinyl Alcohol Film, Cellulose Film Etc. can be mentioned.
  • the stretching of the film laminate may be performed by dry stretching or wet stretching.
  • the boric acid concentration is preferably performed in an aqueous boric acid solution having a concentration of 1% by weight to 5% by weight.
  • the stretching of the film laminate may be performed at a draw ratio of 5 times to 15 times at a temperature of 20 ° C. to 85 ° C.
  • the present invention may further include the step of dyeing at least one of iodine and dichroic dye on the unstretched polyvinyl alcohol-based film before the stretching of the film laminate.
  • Separating the polymer film and the polyvinyl alcohol-based film of the stretched film laminate may be performed by applying a peel force of 2N / 2cm or less.
  • the present invention provides a thin polarizer having a thickness of 10 ⁇ m or less, a single transmittance of 40 to 45%, and a degree of polarization of 99% or more.
  • the present invention provides a polarizing plate including the thin polarizer.
  • a thin polarizer having a thickness of 10 ⁇ m or less can be manufactured with excellent process stability through a simple process.
  • 1 is a schematic diagram showing a method for measuring adhesion or peeling force using a texture analyzer (Texture Analyzer).
  • FIG. 2 is a graph showing the breakage incidence of the film laminates prepared by Example 1 and Comparative Examples 1 and 2.
  • FIG. 2 is a graph showing the breakage incidence of the film laminates prepared by Example 1 and Comparative Examples 1 and 2.
  • Figure 3 is a photograph showing the surface state of the thin polarizer prepared by Example 2.
  • the present inventors have conducted a long study to manufacture a thin polyvinyl alcohol polarizing film, and as a result, using a laminated film formed by attaching a thin unstretched polyvinyl alcohol-based film to one or both sides of the unstretched polymer film , No breakage occurred in the manufacturing process, and found that a polarizer excellent in optical properties such as polarization degree while having a very thin thickness of 10 ⁇ m or less can be produced.
  • the present invention relates to a manufacturing method, a thin polarizer and a polarizing plate manufactured using the same) and 10-2012-0130577 (name of the invention: a manufacturing method of a thin polarizer, a thin polarizer and a polarizing plate manufactured using the same).
  • the method of manufacturing a thin polarizer of the present invention comprises the steps of: attaching an unstretched polyvinyl alcohol-based film to a film between at least two or more unstretched polymer films through a attraction force or an adhesive layer, the stretched polyvinyl alcohol-based film And stretching the film laminate such that the thickness thereof is 10 ⁇ m or less, and separating the polymer film and the polyvinyl alcohol-based film of the stretched film laminate.
  • the modulus value per unit area of the polyvinyl alcohol-based film is lowered compared to the case of one sheet, and thus the breakage rate is increased. As a result, it is possible to stably perform high magnification stretching.
  • the peeling of the polyvinyl alcohol-based film which may occur due to the swelling degree of the polyvinyl alcohol-based film in the wet stretching process for manufacturing the polarizer and / or separation phenomenon with the polymer substrate Etc. can be effectively suppressed and the instability of the film laminate can be reduced.
  • a phenomenon in which the swollen polyvinyl alcohol-based film is wound around a roll may occur.
  • a polyvinyl alcohol-based film may be used. Since the polymer base material is located on both sides, such a phenomenon is prevented, and the process can be performed without damaging the laminate even in a low concentration aqueous solution of boric acid.
  • the polyvinyl alcohol-based film when the polyvinyl alcohol-based film is exposed to the outside, when the film laminate is rolled into a roll film before the polarizer manufacturing process is introduced, the polyvinyl alcohol is generally damaged by polyvinyl alcohol-based film damage or moisture. Problems such as sticking of the surface of the system film and occurrence of wrinkles may occur, but the above problems may be prevented in advance.
  • an unstretched polyvinyl alcohol-based film is attached between at least two unstretched polymer films via a attraction force or an adhesive layer to form a film laminate.
  • the said film laminated body should just be a shape in which an unstretched polyvinyl alcohol-type film is arrange
  • the number of an unstretched polymer film and an unstretched polyvinyl alcohol-type film is specifically limited. It doesn't work.
  • the said film laminated body is a 1st unstretched polyvinyl alcohol-type film adhered on a 1st unstretched polymer film, the said 1st unstretched polymer film, and the said 1st unstretched polyvinyl alcohol-type film It may have a structure made of a second unstretched polymer film to be attached, that is, a structure such as an unstretched polymer film / unstretched polyvinyl alcohol-based film / unstretched polymer film.
  • the film laminate is attached to a first unstretched polymer film, a first unstretched polyvinyl alcohol-based film attached to the first unstretched polymer film, and the first unstretched polyvinyl alcohol-based film.
  • a second unstretched polymer film, a second unstretched polyvinyl alcohol film adhered on the second unstretched polymer film, and a third unstretched polymer film adhered on the second unstretched polyvinyl alcohol film A structure such as an unstretched polymer film / unstretched polyvinyl alcohol-based film / unstretched polymer film / unstretched polyvinyl alcohol-based film / unstretched polymer film may be used.
  • a film laminate in which a larger number of polymer films or polyvinyl alcohol-based films are laminated may be used, and it will be apparent that all such modifications fall within the scope of the present invention.
  • the polymer film is necessarily positioned on both surfaces of each of the polyvinyl alcohol-based films.
  • the effect of lowering the possibility of deformation of the polyvinyl alcohol-based film in the further process for the film laminate can be obtained, the principle of which is as mentioned above.
  • the unstretched polymer film used in the film laminate of the present invention is for preventing the polyvinyl alcohol-based film from breaking in the stretching step, preferably, the maximum stretching ratio is 5 under the temperature conditions of 20 °C to 85 °C. It may be a polymer film more than twice. In this case, the maximum draw ratio means a draw ratio immediately before breakage occurs.
  • the stretching may be dry stretching or wet stretching, in the case of wet stretching, the stretching ratio in the case of stretching in an aqueous boric acid solution having a boric acid concentration of 1.0 to 5% by weight.
  • Such polymer films include, but are not limited to, high density polyethylene films and polyurethanes. Film, polypropylene film, polyolefin film, ester film, low density polyethylene film, high density polyethylene and low density polyethylene coextrusion film, copolymer resin film containing ethylene vinyl acetate in high density polyethylene, acrylic film, polyethylene terephthalate film, polyvinyl Alcohol Film, Cellulose Film Etc. can be mentioned.
  • the unstretched polymer film used in the present invention may have a thickness of about 20 ⁇ m to 100 ⁇ m, preferably about 30 ⁇ m to 80 ⁇ m, and more preferably about 40 ⁇ m to 60 ⁇ m. If the thickness of the unstretched polymer film is less than 20 ⁇ m, breakage may occur due to insufficient support of the polyvinyl alcohol-based film in the stretching process of the film laminate, and when the thickness of the unstretched polymer film exceeds 100 ⁇ m, the stretchability of the film laminate This is because the optical properties of the finally obtained polarizer may be inhibited by preventing free width shrinkage during drying of the polyvinyl alcohol-based film.
  • the glass transition temperature of the unstretched polymer film is preferably lower than the glass transition temperature of the polyvinyl alcohol-based film, for example, it is preferably about 20 °C to 60 °C, preferably 30 °C to 60 °C. Do. In general, considering that the glass transition temperature of the polyvinyl alcohol-based film is about 70 ° C. to 80 ° C., when the glass transition temperature of the polymer film satisfies the numerical range, the polymer film is more soft under the stretching temperature condition. It can have a result, it is possible to stretch the polyvinyl alcohol-based film better.
  • the glass transition temperature of the polymer film is preferably 20 ° C. or higher.
  • the glass transition temperature may be measured by a differential scanning calorimeter (DSC). For example, when a sample of about 10 mg is sealed in a dedicated pan of a differential scanning calorimeter (DSC) and heated to a constant temperature condition, the endothermic and calorific values generated by phase shifting are plotted according to the temperature. The temperature can be measured.
  • DSC differential scanning calorimeter
  • the unoriented polymer film has a modulus at room temperature (25 ° C.) of about 200 MPa to 1500 MPa, preferably about 350 MPa to 1300 MPa.
  • a modulus at room temperature 25 ° C.
  • the modulus of the polymer film exceeds 1500MPa, high magnification stretching may be difficult, and when less than 200MPa, breakage may occur in the stretching process.
  • the modulus is fixed to both ends of the sample prepared according to JIS-K6251-1 standard, and then applied a force in a direction perpendicular to the thickness direction of the film to measure the stress per unit area according to the tensile rate (strain)
  • the value obtained by this is referred to, and a tensile force meter (Zwick / Roell Z010 UTM) etc. can be used as a measuring instrument.
  • the unstretched polymer film may have a force at break point at room temperature (25 ° C.) of about 5N to about 40N, preferably about 10N to about 30N.
  • the breaking force refers to a tensile force at the time when the film is broken when fixing both ends of the film and then applying a tensile force in a direction perpendicular to the thickness direction of the film, for example, a tensile force meter (Zwick / Roell Z010 UTM) and the like can be measured.
  • Zwick / Roell Z010 UTM tensile force meter
  • two or more polymer films are used, wherein the polymer films, for example, the first unstretched polymer film, the second unstretched polymer film, and the third unstretched polymer film are the same.
  • a polymer film may be sufficient and a different polymer film may be sufficient.
  • the unstretched polyvinyl alcohol-based film disposed between the unstretched polymer film has a thickness of about 10 ⁇ m to 60 ⁇ m, preferably about 10 ⁇ m to 40 ⁇ m.
  • the thickness of the unstretched polyvinyl alcohol-based film exceeds 60 ⁇ m, it is difficult to realize a thickness of 10 ⁇ m or less even when stretched, and when the thickness is less than 10 ⁇ m, breakage occurs easily during stretching.
  • the unstretched polyvinyl alcohol-based film is not limited to this, but the degree of polymerization is preferably about 1,000 to 10,000, preferably 1,500 to 5,000. This is because when the degree of polymerization satisfies the above range, the molecular motion is free and can be mixed flexibly with iodine or dichroic dye.
  • the unstretched polyvinyl alcohol-based film of the present invention a commercially available polyvinyl alcohol-based film may be used.
  • PS30, PE30, PE60 of Kureray Co., Ltd. M2000, M3000, M6000, etc. may be used. Can be.
  • each polyvinyl alcohol-based film may have the same composition or different polymerization degree or the like.
  • the unstretched polyvinyl alcohol-based film is a film in which iodine and / or dichroic dye are dyed. More preferably, the unstretched polyvinyl alcohol-based film may be a film in which a swelling process and a dyeing process are performed.
  • the present invention may further perform the step of dyeing iodine and / or dichroic dye on the unstretched polyvinyl alcohol-based film before the stretch of the film laminate, preferably the unstretched Swelling a polyvinyl alcohol-based film and dyeing iodine and / or dichroic dye on the swollen unstretched polyvinyl alcohol-based film may be further performed.
  • the step of swelling the unstretched polyvinyl alcohol-based film is to promote the adsorption and diffusion of the iodine and / or dichroic dye to the polyvinyl alcohol-based film, to improve the stretchability of the polyvinyl alcohol-based film
  • the present invention is not limited thereto.
  • the unstretched polyvinyl alcohol-based film may be immersed in pure water at 25 ° C. to 30 ° C. for 5 seconds to 30 seconds, more preferably 10 seconds to 20 seconds. have.
  • the swelling is preferably performed so that the swelling degree of the unstretched polyvinyl alcohol-based film is about 36% to 44%, preferably about 38% to 42%.
  • the swelling degree of the unstretched polyvinyl alcohol-based film satisfies the above numerical range, optical properties such as the degree of polarization of the finally produced thin polarizer appear very excellent. Meanwhile, the swelling degree was calculated as ⁇ (weight of polyvinyl alcohol-based film after swelling-weight of polyvinyl alcohol-based film before swelling) / weight of polyvinyl alcohol-based film before swelling ⁇ ⁇ 100.
  • the step of dyeing iodine and / or dichroic dye on the unstretched polyvinyl alcohol-based film is impregnated in the dye bath containing a dye solution containing iodine and / or dichroic dye.
  • a dyeing solution containing iodine and / or a dichroic dye may be applied onto a polyvinyl alcohol-based film, wherein water is generally used as a solvent of the dyeing solution, but is compatible with water.
  • the organic solvent which has sex may be mixed.
  • the content of iodine and / or dichroic dye in the dyeing solution may be about 0.06 parts by weight to about 0.25 parts by weight based on 100 parts by weight of the solvent.
  • the dyeing solution may further contain an adjuvant for improving the dyeing efficiency in addition to the iodine and / or dichroic dye
  • the adjuvant includes potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide Iodide compounds such as copper iodide, barium iodide, calcium iodide, tin iodide, titanium iodide or mixtures thereof can be used.
  • the content of the adjuvant may be about 0.3 parts by weight to about 2.5 parts by weight with respect to 100 parts by weight of the solvent, and more preferably, the weight ratio of iodine to iodide compound may be about 1: 5 to about 1:10.
  • the dyeing step is preferably carried out at a temperature of about 25 °C to 40 °C, the dyeing bath immersion time is preferably about 30 seconds to 120 seconds, but is not limited thereto.
  • the film laminate of the present invention as described above may be produced by alternately attaching the unstretched polymer film and the unstretched polyvinyl alcohol-based film alternately with an adhesive, or alternately laminated without a separate medium.
  • the surface treatment may be performed 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.
  • the thickness of the adhesive layer before stretching is about 20 nm to 4000 nm, preferably about 20 nm to 1000 nm, and more preferably 20 nm to 500 nm. May be enough.
  • the thickness of the adhesive layer after the stretching of the film laminate may be about 10nm to 1000nm, preferably 10nm to 500nm, more preferably 10nm to 200nm.
  • the adhesive the material is not particularly limited, various adhesives known in the art can be used without limitation.
  • the adhesive layer may be formed of an aqueous adhesive or an ultraviolet curable adhesive.
  • the adhesive layer may be formed by an aqueous adhesive including at least one selected from the group consisting of polyvinyl alcohol-based resins, acrylic resins, and vinyl acetate-based resins.
  • the adhesive layer may be formed by an aqueous adhesive including a polyvinyl alcohol-based resin having an acrylic group and a hydroxyl group.
  • the polyvinyl alcohol-based resin having an acrylic group and a hydroxyl group may have a degree of polymerization of about 500 to 1800.
  • the adhesive layer may be formed using an aqueous adhesive including an amine-based metal compound crosslinking agent in acetacetyl group-containing polyvinyl alcohol-based resin.
  • the adhesive may be an aqueous solution containing 100 parts by weight of a polyvinyl alcohol-based resin containing an acetacetyl group and 1 to 50 parts by weight of an amine metal compound crosslinking agent.
  • the polymerization degree and saponification degree of the polyvinyl alcohol-based resin are not particularly limited as long as they contain acetacetyl group, but the polymerization degree is 200 to 4,000, and the saponification degree is preferably 70 mol% to 99.9 mol%.
  • the degree of polymerization is 1,500 to 2,500, and the degree of saponification is more preferably 90 mol% to 99.9 mol%.
  • the polyvinyl alcohol-based resin preferably comprises 0.1 to 30 mol% of the acetacetyl group.
  • the reaction with the amine-based metal compound crosslinking agent may be smooth, and may be sufficiently significant for the water resistance of the desired adhesive.
  • the amine-based metal compound crosslinking agent is a water-soluble crosslinking agent having a functional group having reactivity with the polyvinyl alcohol-based resin, preferably in the form of a metal complex containing an amine ligand.
  • Possible metals include zirconium (Zr), titanium (Ti), hafnium (Hf), tungsten (W), iron (Fe), cobalt (Co), nickel (Ni), ruthenium (Ru), osmium (Os), Transition metals such as rhodium (Rh), iridium (Ir), palladium (Pd) and platinum (Pt) are possible, and ligands bound to the central metal are primary amines, secondary amines (diamines), tertiary amines or ammonium hydrides. As long as it contains at least 1 or more amine groups, such as a lockside, it is all possible.
  • the solid content of the polyvinyl alcohol-based resin containing the acetacetyl group is preferably about 1% by weight to about 10% by weight. If the solid content of the polyvinyl alcohol-based resin is less than 1% by weight, the water resistance is not sufficiently secured, so that the effect of lowering the breakage rate in the stretching process is less. If the content is more than 10% by weight, the workability is deteriorated. This is because damage may occur on the alcohol-based film surface.
  • the pH of the adhesive is preferably 4.5 to 9 or so.
  • fills the said numerical range it is because it is more advantageous in storage property and durability in a high humidity environment.
  • the pH of the adhesive can be adjusted by the method of containing an acid in the aqueous solution, wherein the acid used for pH adjustment can be used both strong and weak acid.
  • the acid used for pH adjustment can be used both strong and weak acid.
  • nitric acid, hydrochloric acid, sulfuric acid or acetic acid and the like can be used.
  • the thickness of the adhesive layer formed by the above adhesive is about 80 nm to 200 nm, preferably about 80 nm to 150 nm before stretching the film laminate, and after stretching the film laminate, about 10 nm to 100 nm, preferably 10 nm to It is preferable that it is about 80 nm. This is because when the thickness of the adhesive layer satisfies the above range, the adhesion between the base film and the polyvinyl alcohol-based film is maintained at an appropriate level so that the breakage rate in the stretching process is reduced and the polarizer surface damage during peeling can be minimized. .
  • the said adhesive agent In the case of the said adhesive agent, a crosslinking reaction occurs between the amine type metal compound and the acetacetyl group of polyvinyl alcohol-type resin at the time of hardening, and the water resistance of the adhesive layer after hardening becomes very excellent. Therefore, when the polymer film and the polyvinyl alcohol-based film are laminated using the adhesive, the phenomenon in which the adhesive dissolves in water during wet stretching can be minimized, and thus it can be particularly useful when performing wet stretching. .
  • the adhesive layer may be formed of an ultraviolet curable adhesive, for example, a first epoxy compound having a glass transition temperature of homopolymer of 120 ° C. or more, a second epoxy compound having a glass transition temperature of homopolymer of 60 ° C. or less and It may be formed of an ultraviolet curable adhesive containing a cationic photopolymerization initiator.
  • the UV-curable adhesive is 100 parts by weight of the first epoxy compound having a glass transition temperature of the homopolymer of 120 °C or more, 30 to 100 parts by weight of the second epoxy compound having a glass transition temperature of the homopolymer of 60 °C or less and cationic photopolymerization It may include 0.5 to 20 parts by weight of the initiator.
  • an epoxy compound refers to a compound having one or more epoxy groups in a molecule, preferably a compound having two or more epoxy groups in a molecule, and is in the form of a monomer, a polymer, or a resin.
  • the concept includes all of the compounds.
  • the epoxy compound of the present invention may be in the form of a resin.
  • the glass transition temperature of the homopolymer is an epoxy compound of 120 °C or more can be used without particular limitation, for example, the alicyclic epoxy compound and the glass transition temperature of the homo polymer is 120 °C or more and / Or aromatic epoxy may be used as the first epoxy compound of the present invention.
  • Specific examples of the epoxy compound having a glass transition temperature of homopolymer of 120 ° C. or higher include 3,4-epoxycyclohexylmethyl-3,4′-epoxycyclohexanecarboxylate, vinylcyclohexenedioxide dicyclopentadiene dioxide, and bisepoxycyclo.
  • the first epoxy compound is more preferably the glass transition temperature of the homopolymer is about 120 °C to 200 °C.
  • the second epoxy compound may be used without particular limitation as long as the glass transition temperature of the homopolymer is an epoxy compound of 60 ° C. or less.
  • an alicyclic epoxy compound, an aliphatic epoxy compound, or the like may be used as the second epoxy compound.
  • alicyclic epoxy compound it is preferable to use a bifunctional epoxy compound, that is, a compound having two epoxies, and more preferably use a compound in which the two epoxy groups are both alicyclic epoxy groups. It is not limited.
  • the epoxy compound which has an aliphatic epoxy group which is not an alicyclic epoxy group can be illustrated.
  • polyglycidyl ether of aliphatic polyhydric alcohol Polyglycidyl ethers of alkylene oxide adducts of aliphatic polyhydric alcohols; Polyglycidyl ethers of polyester polyols of aliphatic polyhydric alcohols and aliphatic polyhydric carboxylic acids; Polyglycidyl ethers of aliphatic polyvalent carboxylic acids; Polyglycidyl ethers of polyester polycarboxylic acids of aliphatic polyhydric alcohols and aliphatic polyhydric carboxylic acids; Dimers, oligomers or polymers obtained by vinyl polymerization of glycidyl acrylate or glycidyl methacrylate; Or oligomers or polymers obtained by vinyl polymerization of glycidyl acrylate or glycidyl me
  • aliphatic polyhydric alcohol for example, an aliphatic polyhydric alcohol having 2 to 20 carbon atoms, 2 to 16 carbon atoms, 2 to 12 carbon atoms, 2 to 8 carbon atoms or 2 to 4 carbon atoms may be exemplified.
  • Ethylene glycol 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-butanediol, neo Pentyl glycol, 3-methyl-2,4-pentanediol, 2,4-pentanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 3,5-heptanediol, 1,8-octanediol, 2-methyl-1,8- Aliphatic diols such as octanediol, 1,9-nonane
  • alkylene oxide of 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms or 1 to 4 carbon atoms can be exemplified, for example, ethylene jade Seeds, propylene oxide or butylene oxide and the like can be used.
  • aliphatic polyhydric carboxylic acid For example, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, sumeric acid, azelaic acid, sebacic acid, dodecane diacid, 2-methyl succinic acid, 2-methyladipic acid, 3-methyladipic acid, 3-methylpentaneic acid, 2-methyloctanoic acid, 3,8-dimethyldecanediic acid, 3,7-dimethyldecanediic acid, 1,20-eicosamethylenedica Carboxylic acid, 1,2-cyclopentanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1, 4-cyclohexanedicarboxylic acid, 1,4-dicarboxymethylenecyclohexane, 1,2,3-propylic acid, 1,
  • the second epoxy compound of the present invention may include one or more glycidyl ether groups, for example, 1,4-cyclohexanedimethanol diglycidyl ether, 1,4-butanediol diggle Cydyl ether, 1,6-hexanediol diglycidyl ether, neopentyl diglycidyl ether, resorcinol diglycidyl ether, diethylene glycol diglycidyl ether, ethylene glycol diglycidyl ether, One selected from the group consisting of trimethylolpropanetriglycidyl ether, n-butyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, and o-cresyl glycidyl ether The above can be used as the second epoxy compound of the present invention.
  • the second epoxy compound has a glass transition temperature of about 0 ° C to 60 ° C of the homopolymer.
  • the present invention is not limited thereto, but in the present invention, it is preferable to use a combination of the first epoxy compound including at least one epoxidized aliphatic ring group and the second epoxy compound including at least one glycidyl ether group as the epoxy compound. Particularly preferred.
  • the film laminate is stretched.
  • the stretching is preferably carried out so that the thickness of the polyvinyl alcohol-based film is less than 10 ⁇ m, for example, the thickness of the polyvinyl alcohol-based film is 1 ⁇ m to 10 ⁇ m, 3 ⁇ m to 10 ⁇ m or 1 ⁇ m It is preferable to carry out so that it becomes about 5 micrometers.
  • the stretching conditions are not particularly limited, for example, the stretching may be carried out at a draw ratio of 5 times to 15 times at a temperature of 20 °C to 85 °C, more preferably 40 It may be carried out at a draw ratio of 5 to 12 times at a temperature of °C to 80 °C.
  • the stretching may be performed by wet stretching or dry stretching.
  • wet stretching since the surface adhesion of the thermoplastic polyurethane film and the polyvinyl alcohol-based film is stronger than the dry stretching, the stretching can be performed stably without a separate bonding means.
  • the wet stretching is preferably carried out in an aqueous boric acid solution, wherein the boric acid concentration of the aqueous boric acid solution is preferably about 1.0 to 5.0 wt%.
  • the manufacturing process of the polarizing element is a process of washing with water, swelling, dyeing, washing, stretching, complementary color, drying and the like
  • the washing and stretching process is preferably carried out in an aqueous boric acid solution.
  • the boric acid concentration may be about 0.1 to 2.5 wt%, preferably about 0.5 to 2.0 wt%
  • the boric acid concentration is about 1.0 to 5.0 wt%, preferably 1.5 to It may be about 4.5 wt%.
  • the adhesion between the stretched polyvinyl alcohol-based film and the stretched polymer film after the stretching of the film laminate is 2N / 2cm or less, preferably, about 0.1 to 2N / 2cm, more preferably about 0.1 to 1N / 2cm.
  • the adhesive layer is stretched together by stretching, as well as the polyvinyl alcohol-based film and the polymer film.
  • the thickness is reduced to a level of 10 to 50% compared to before stretching, and as a result, the adhesion force between the polyvinyl alcohol-based film and the polymer film is lowered to 2N / 2cm or less, thereby making it easy to separate.
  • the adhesive force is the adhesive force measured when the sample films of 2cm length is attached, a specific measuring method is shown in FIG.
  • the adhesion between the films as shown in Figure 1, after fixing the polyvinyl alcohol film (A) of the film laminate with a sample holder (H), with respect to the surface direction of the film laminate Peel strength measured by peeling the polyvinyl alcohol film (A) from the polymer film (B) by applying a force in a vertical direction, wherein the measuring instrument is a texture analyzer (Stable Micro Systems, Inc.) TA-XT Plus) was used.
  • the drying is preferably 20 to 100 °C, more preferably about 40 to 90 °C, it is preferably carried out for 1 to 10 minutes at the above temperature.
  • the drying process prevents the PVA polarizer from deteriorating the physical properties of the PVA polarizer by water removal during the production of the PVA surface and the inside and smoothly induces the shrinkage of the polyvinyl alcohol film stretched during the drying process. It serves to improve the polarization degree of the polarizer by increasing the orientation of the complex composed of iodine.
  • the separating step may be performed by applying a weak peel force to the polyvinyl alcohol-based film to be separated from the polymer film.
  • the peel force is preferably 2N / 2cm or less, for example, may be about 0.1 to 2N / 2cm or 0.1 to 1N / 2cm.
  • the peel force required to separate the polyvinyl alcohol-based film and the polymer film is very weak compared to the case of lamination using a coating or co-extrusion, the two films are easily separated without any other process or equipment. Not only that, but also the damage of the polyvinyl alcohol-based film in the separation process is very low, it shows very excellent optical performance.
  • the thin polarizer manufacturing method of the present invention as described above, sheet-to-sheet (sheet-to-sheet) process, sheet-to-roll process or roll well known in the art It may be carried out through a roll-to-roll process or the like.
  • the sheet-to-sheet process is a method using a sheet-like film cut to a predetermined size with a raw film (ie, polyvinyl alcohol-based film and a polymer film), the sheet-to-roll process is a part of the raw film Refers to a method of using a rolled film wound with a long film and using a sheet-like film cut to a constant size as another raw film.
  • a roll-to-roll process is a method of using a rolled film as a raw film. In view of the continuity and productivity of the process, it is particularly preferred to use a roll-to-roll process among these.
  • a non-stretched polyvinyl alcohol-based film roll is disposed between the unstretched polymer film rolls, and the polyvinyl alcohol-based film and the polymer film are unwound from the film rolls, respectively, of 2 N / 2 cm or less.
  • the at least two or more unstretched polymer film and the unstretched polyvinyl alcohol-based film is attached, and then rewound in a roll shape, then unwinds the film laminate from the rewound film laminate roll to be introduced into the stretching process. It may be, or may be added directly to the stretching process without rewinding.
  • a separation means eg, a peeling roll
  • a separation means is inserted between the polymer film and the polyvinyl alcohol-based film to separate the interface between the polymer film and the polyvinyl alcohol-based film, and then the separated polymer film and It can be carried out by the method of winding the polyvinyl alcohol-based film in different rolls.
  • the polarizer of the present invention produced by the above method is very thin, the thickness of which is about 10 ⁇ m or less, preferably about 1 ⁇ m to 10 ⁇ m, more preferably about 3 ⁇ m to 10 ⁇ m.
  • the unitary transmittance is about 40 to 45%, and the polarization degree is 99% or more, indicating very excellent optical properties.
  • the polarizer of this invention is very excellent in the uniformity of the polarization degree to the width direction. More specifically, the polarizer of the present invention has a standard deviation of the degree of polarization measured at ten points located at equal intervals along the width direction of the polarizer at 0.002% or less.
  • a polarizing plate can be formed by laminating a transparent film on one side or both sides on the polarizer of the present invention as described above.
  • various films used as a polarizer protective film or a retardation film in the art may be used without limitation, for example, an acrylic film, a PET film, an acrylic primer treated PET film, a cellulose film , Cycloolefin-based film, polycarbonate-based film, polynorbornene-based film and the like can be used.
  • the laminating method of the polarizer and the transparent film is not particularly limited, and a film lamination method well known in the art, for example, after applying an adhesive or an adhesive to at least one surface of the polarizer and / or the transparent film, the polarizer and the transparent film It may be performed using a method such as laminating.
  • the pressure-sensitive adhesive or adhesive may be appropriately selected in consideration of the material of the transparent film to be used, for example, when using a TAC as a transparent film, an aqueous adhesive such as a polyvinyl alcohol-based adhesive may be used, When using an acrylic film, a COP film, etc. as a transparent film, photocuring or thermosetting adhesives, such as an acrylic adhesive and an epoxy adhesive, can be used.
  • the lamination method of the polarizer and the transparent film is not particularly limited, but is preferably made of a roll-to-roll method using a polarizer film roll and a transparent film roll in terms of productivity. Since a method of manufacturing a polarizing plate by laminating a polarizer and a transparent film in a roll-to-roll manner is well known in the art, a detailed description thereof will be omitted. Thus, when manufacturing a polarizing plate by a roll-to-roll system, a long rolled polarizing plate can be obtained.
  • the polarizing plate of the present invention in addition to the transparent film may further include other functional optical layers, such as brightness enhancement film, primer layer, hard coating layer, anti-glare layer, anti-reflection layer or adhesive layer for adhesion with the liquid crystal panel.
  • functional optical layers such as brightness enhancement film, primer layer, hard coating layer, anti-glare layer, anti-reflection layer or adhesive layer for adhesion with the liquid crystal panel.
  • the formation method of these optical layers is not specifically limited, The well-known method well known in the art can be used.
  • the polarizing plate of the present invention has a very thin thickness compared to the conventional polarizing plate and has excellent optical properties, and thus may be usefully used in display devices such as liquid crystal display panels and organic light emitting display devices.
  • the unstretched polyvinyl alcohol-based film Kuraray's PE30 grade polyvinyl alcohol-based film (thickness: 30 ⁇ m) was used, and after swelling for 15 seconds in a 25 ° C. pure water solution, 0.3 wt% concentration and A polyvinyl alcohol-based film which was subjected to a dyeing process for 60 seconds in an iodine solution at 25 ° C. was used.
  • the unstretched polyurethane film a film prepared using a thermoplastic polyurethane resin obtained by reacting methylenediphenyl diisocyanate, 1,4-butanediol and adipic acid was used.
  • the unstretched polyvinyl alcohol film is alternately laminated on both sides of the unstretched polyurethane film without a medium to form a film laminate having an unstretched polyvinyl alcohol film / unstretched polyurethane film / unstretched polyvinyl alcohol film structure. It was.
  • the unstretched polyvinyl alcohol-based film and the unstretched polyurethane film the same ones as in Example 1 were used.
  • Kuraray's PE30 grade polyvinyl alcohol film (thickness: 30 ⁇ m) was prepared by swelling in pure water at 25 ° C. for 15 seconds, followed by dyeing for 60 seconds in 0.3 wt% concentration and iodine solution at 25 ° C. .
  • the thickness ratio of the polyvinyl alcohol-based film after the stretching step to the thickness of the polyvinyl alcohol-based film before the stretching step was calculated according to the following formula. The calculation result is shown in FIG.
  • Thickness ratio (dr) (%) ⁇ thickness of polyvinyl alcohol-based film after stretching (d) / thickness of polyvinyl alcohol-based film before stretching (d 0 ) ⁇ ⁇ 100
  • the thickness ratio dr was about 27%, and the thickness ratio dr of Comparative Examples 1 and 2 was approximately. 21% to 22%.
  • the thickness ratio is 19%, and it can be seen that stretching was performed well without breaking compared to Comparative Examples 1 and 2.
  • the unstretched film laminate of Example 1 was After washing for 15 seconds in a 1 wt% solution of boric acid, it was stretched 7 times in a boric acid solution of 52 °C, 2.5 wt%. Thereafter, after 5% by weight of potassium iodide (KI) solution through a complementary color process, the drying process was performed for 5 minutes in an 80 °C oven. Then, in the stretched film laminate, the polyvinyl alcohol-based films were separated from the polyurethane substrate, respectively, to obtain a thin polarizer. The thickness of the polarizer was 7-10 micrometers.
  • KI potassium iodide
  • Figure 3 is a photograph showing the surface state of the film laminate after the drying step of Example 2 is shown. As shown in FIG. 3, when the film laminate of Example 2 is used, not only a stable stretching process is performed without breaking, but also the surface state of the polyvinyl alcohol-based film is uniform and good.
  • a 4% by weight aqueous solution was prepared by dissolving polyvinyl alcohol (average degree of polymerization 2000, degree of 94%, Japanese Synthetic) containing acetacetyl group (5% by weight) in pure water. Titanium amine complex crosslinking agent (product name: TYZOR TE, DuPont) was added at a ratio of 6.7 parts by weight per 100 parts by weight of polyvinyl alcohol and mixed with stirring to prepare an adhesive A.
  • polyvinyl alcohol average degree of polymerization 2000, degree of 94%, Japanese Synthetic
  • Titanium amine complex crosslinking agent product name: TYZOR TE, DuPont
  • M2000-grade polyvinyl alcohol-based film (thickness: 20 ⁇ m) of Japan Synthetic Inc. was used as the unstretched polyvinyl alcohol-based film
  • methylene diphenyl diisocyanate and 1,4-butanediol were used as the unstretched polyurethane film.
  • a film prepared using a thermoplastic polyurethane resin obtained by reacting adipic acid was used as the unstretched polyurethane film.
  • the film laminate was washed in a 1 wt% solution of boric acid for 15 seconds, the film laminate was stretched at a draw ratio of 7 times at 52 ° C. and 2.5 wt% of boric acid solution. Then, after a complementary color process in a 5 wt% potassium iodide (KI) solution, it was dried for 5 minutes in an 80 °C oven. Then, the polyurethane film and the polyvinyl alcohol-based film were separated with a peel force of 0.7 N / 2 cm to obtain two thin polarizers having a thickness of 5 to 8 ⁇ m.
  • KI potassium iodide
  • Optical properties such as single transmittance, polarization degree, single color, and orthogonal color of the thin polarizers prepared according to Examples 2 and 3 were measured with a JASCO V-7100 Spectrophotometer. The measurement results are shown in [Table 1].
  • the thin polarizer manufactured according to the method of the present invention has excellent optical properties such as single transmittance, polarization degree, and color.

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Abstract

The present invention relates to a method for manufacturing a thin polarizer, comprising the steps of: forming a film laminate by adhering an unstretched polyvinyl alcohol-based film by means of an attractive force or an adhesive layer between at least two unstretched polymer films; stretching the film laminate so that the polyvinyl alcohol-based films have a thickness of 10 μm or less after the stretching; and separating the polymer films and the polyvinyl alcohol-based films from the stretched film laminate.

Description

박형 편광자의 제조 방법, 이를 이용하여 제조된 박형 편광자 및 편광판 Manufacturing method of thin polarizer, thin polarizer and polarizing plate manufactured using same
본 발명은 박형 편광자의 제조 방법, 이를 이용하여 제조된 박형 편광자 및 편광판에 관한 것으로, 보다 구체적으로는, 10㎛ 이하의 얇은 두께를 갖는 박형 편광자의 제조 방법, 이를 이용하여 제조된 박형 편광자 및 편광판에 관한 것이다.The present invention relates to a method of manufacturing a thin polarizer, a thin polarizer and a polarizing plate manufactured using the same, and more particularly, a method of manufacturing a thin polarizer having a thin thickness of 10 μm or less, a thin polarizer and a polarizing plate manufactured using the same. It is about.
편광판에 사용되는 편광자는 자연광 또는 임의의 편광을 특정 방향의 편광으로 만들기 위한 광학 소자로, 액정표시소자, 유기발광소자(OLED)와 같은 디스플레이 장치에 널리 이용되고 있다. 현재 상기 디스플레이 장치에 사용되는 편광자로는 요오드계 화합물 또는 이색성 염료를 함유하는 분자 사슬이 일정한 방향으로 배향된 폴리비닐알코올계 편광 필름이 일반적으로 사용되고 있다.The polarizer used in the polarizing plate is an optical element for making natural light or arbitrary polarization into a polarized light in a specific direction, and is widely used in a display device such as a liquid crystal display device and an organic light emitting device (OLED). Currently, as a polarizer used in the display device, a polyvinyl alcohol polarizing film in which molecular chains containing an iodine compound or a dichroic dye are oriented in a constant direction is generally used.
상기 폴리비닐알코올계 편광필름은 폴리비닐알코올계 필름에 요오드 또는 이색성 염료를 염착시킨 후, 일정 방향으로 연신하고 가교하는 방법에 의해 제조되고 있으며, 이때 상기 연신 공정은 붕산 수용액 또는 요오드 수용액과 같은 용액 상에서 수행되는 습식 연신 또는 대기 중에서 수행되는 건식 연신 등으로 수행될 수 있고, 연신 배율은 일반적으로 5배 이상이다. 그런데, 이와 같은 종래의 제조 공정에서, 파단 발생 없이 연신이 수행되기 위해서는, 연신 전의 폴리비닐알코올계 필름의 두께가 60㎛를 초과할 것이 요구된다. 연신 전 폴리비닐알코올계 필름의 두께가 60㎛ 이하일 경우, 폴리비닐알코올계 필름의 팽윤도가 높아지고, 얇은 두께로 인해 연신 공정에서 단위 면적 당 작용하는 모듈러스가 커져 파단이 쉽게 발생할 수 있기 때문이다.The polyvinyl alcohol polarizing film is prepared by a method of dyeing and crosslinking iodine or dichroic dye on a polyvinyl alcohol-based film, and stretching in a predetermined direction, wherein the stretching process is an aqueous solution of boric acid or an iodine solution. Wet drawing carried out in solution or dry drawing carried out in air, and the like, and the draw ratio is generally at least 5 times. By the way, in this conventional manufacturing process, in order for extending | stretching to be performed without a breakage generation, it is required that the thickness of the polyvinyl alcohol-type film before extending | stretching exceeds 60 micrometers. This is because when the thickness of the polyvinyl alcohol-based film before stretching is 60 μm or less, the swelling degree of the polyvinyl alcohol-based film is increased, and the thinness of the polyvinyl alcohol-based film increases the modulus acting per unit area in the stretching process, thereby easily causing breakage.
한편, 최근 디스플레이 장치들의 박형화 경향에 따라 편광판 역시 보다 얇은 두께를 가질 것이 요구되고 있다. 그러나 종래와 같이 연신 전 두께가 60㎛를 넘는 폴리비닐알코올계 필름을 사용할 경우에 편광자의 두께를 줄이는데 한계가 있다. 따라서, 보다 얇은 두께의 편광자를 제조하기 위한 연구들이 시도되고 있다.On the other hand, according to the trend of thinning of display devices, polarizers are also required to have a thinner thickness. However, when using a polyvinyl alcohol-based film having a thickness before stretching of more than 60 ㎛ as in the prior art there is a limit in reducing the thickness of the polarizer. Therefore, studies have been attempted to fabricate thinner polarizers.
한국공개특허 제2010-0071998호에는 기재층 상에 친수성 고분자층을 코팅하거나, 기재층 형성재와 친수성 고분자층 형성재를 공압출하여 제조되는 적층체를 이용하여 박형의 편광판을 제조하는 방법이 개시되어 있다. 그러나, 코팅이나 공압출법의 경우, 연신 후에 폴리비닐알코올층과 기재층의 분리가 쉽지 않고, 분리를 위해 높은 박리력이 요구되기 때문에, 분리 과정에서 폴리비닐알코올층이 손상되거나 변형되는 등의 문제가 발생하기 쉬우며, 그 결과 폴리비닐알코올 필름의 편광도 등의 광학 물성이 떨어진다는 문제점이 있었다. 또한, 코팅법이나 공압출법을 이용할 경우, 폴리비닐알코올 수지를 용융시킨 다음 압출하거나, 코팅액으로 제조한 후에 도포하는 방식으로 제조되기 때문에 압출 조건, 코팅 조건 또는 제막 조건에 따라 제조되는 폴리비닐알코올 필름의 물성이 변화되기 쉬워 최종적으로 제조된 폴리비닐알코올의 물성이 저하될 뿐 아니라, 균일한 물성을 구현하기도 어렵다. Korean Unexamined Patent Publication No. 2010-0071998 discloses a method of manufacturing a thin polarizing plate using a laminate prepared by coating a hydrophilic polymer layer on a substrate layer or co-extrusion of a substrate layer forming material and a hydrophilic polymer layer forming material. It is. However, in the case of coating or co-extrusion, since the separation of the polyvinyl alcohol layer and the base layer is not easy after stretching and a high peel force is required for the separation, the polyvinyl alcohol layer is damaged or deformed during the separation process. Problems tend to occur, and as a result, there is a problem that optical properties such as polarization degree of the polyvinyl alcohol film are inferior. In addition, when a coating method or a coextrusion method is used, the polyvinyl alcohol resin is manufactured by melting and extruding the polyvinyl alcohol resin or by applying the coating solution after coating and then applying the polyvinyl alcohol according to extrusion conditions, coating conditions or film forming conditions. The physical properties of the film tend to change, and not only the physical properties of the finally produced polyvinyl alcohol are lowered, but also it is difficult to realize uniform physical properties.
본 발명은 상기와 같은 문제점을 해결하기 위한 것으로, 제조 방법의 공정 안정성이 우수하고, 우수한 광학 특성을 가지면서도 두께가 얇은 편광자를 제조하는 방법을 제공하고자 한다.The present invention is to solve the above problems, to provide a method of manufacturing a polarizer having a thin thickness while having excellent process stability of the manufacturing method, excellent optical properties.
본 발명은, 적어도 둘 이상의 미연신 고분자 필름 사이에 인력 또는 접착제층을 매개로 미연신 폴리비닐알코올계 필름을 부착하여 필름 적층체를 형성하는 단계, 연신된 폴리비닐알코올계 필름의 두께가 10㎛ 이하가 되도록 상기 필름 적층체를 연신하는 단계 및 상기 연신된 필름 적층체의 고분자 필름과 폴리비닐알코올계 필름을 분리시키는 단계를 포함하는 박형 편광자의 제조 방법을 제공한다. The present invention, the step of attaching the unstretched polyvinyl alcohol-based film between at least two unstretched polymer film via a attraction force or an adhesive layer to form a film laminate, the thickness of the stretched polyvinyl alcohol-based film is 10㎛ It provides a method of manufacturing a thin polarizer comprising the step of stretching the film laminate so as to and the step of separating the polymer film and the polyvinyl alcohol-based film of the stretched film laminate.
상기 필름 적층체는 제1미연신 고분자 필름, 상기 제1미연신 고분자 필름 상에 부착되는 제1미연신 폴리비닐알코올계 필름, 및 상기 제1미연신 폴리비닐알코올계 필름 상에 부착되는 제2미연신 고분자 필름으로 이루어질 수 있다. The film laminate is a first unstretched polymer film, a first unstretched polyvinyl alcohol-based film attached to the first unstretched polymer film, and a second unstretched polyvinyl alcohol-based film attached to the film It may be made of an unoriented polymer film.
또한, 상기 필름 적층체는 제1미연신 고분자 필름, 상기 제1미연신 고분자 필름 상에 부착되는 제1미연신 폴리비닐알코올계 필름, 상기 제1미연신 폴리비닐알코올계 필름 상에 부착되는 제2미연신 고분자 필름, 상기 제2미연신 고분자 필름 상에 부착되는 제2미연신 폴리비닐알코올계 필름 및 상기 제2미연신 폴리비닐알코올계 필름 상에 부착되는 제3미연신 고분자 필름으로 이루어질 수 있다. In addition, the film laminate is a first unstretched polymer film, a first unstretched polyvinyl alcohol-based film adhered on the first unstretched polymer film, the first unstretched polyvinyl alcohol-based film A second unstretched polymer film, a second unstretched polyvinyl alcohol-based film attached to the second unstretched polymer film, and a third unstretched polymer film attached to the second unstretched polyvinyl alcohol-based film. have.
상기 미연신 고분자 필름은 20℃ 내지 85℃의 온도 범위에서 최대 연신 배율이 5배 이상, 바람직하게는 5배 내지 15배 정도인 것이 바람직하며, 예를 들면, 고밀도 폴리에틸렌 필름, 폴리우레탄 필름, 폴리프로필렌 필름, 폴리올레핀 필름, 에스테르계 필름, 저밀도 폴리에틸렌 필름, 고밀도 폴리에틸렌 및 저밀도 폴리에틸렌 공압출 필름, 고밀도 폴리에틸렌에 에틸렌 비닐아세테이트가 함유된 공중합체 수지 필름, 아크릴 필름, 폴리에틸렌테레프탈레이트 필름, 폴리비닐알코올계 필름, 셀룰로오스계 필름 등을 들 수 있다. The unstretched polymer film has a maximum draw ratio of 5 times or more, preferably 5 times to 15 times, in a temperature range of 20 ° C. to 85 ° C., for example, a high density polyethylene film or polyurethane Film, polypropylene film, polyolefin film, ester film, low density polyethylene film, high density polyethylene and low density polyethylene coextrusion film, copolymer resin film containing ethylene vinyl acetate in high density polyethylene, acrylic film, polyethylene terephthalate film, polyvinyl Alcohol Film, Cellulose Film Etc. can be mentioned.
한편, 상기 필름 적층체를 연신하는 단계는 건식 연신 또는 습식 연신으로 수행될 수 있으며, 습식 연신의 경우, 붕산 농도가 1중량% 내지 5중량%인 붕산 수용액에서 수행되는 것이 보다 바람직하다. Meanwhile, the stretching of the film laminate may be performed by dry stretching or wet stretching. In the case of wet stretching, the boric acid concentration is preferably performed in an aqueous boric acid solution having a concentration of 1% by weight to 5% by weight.
상기 필름 적층체를 연신하는 단계는 20℃ 내지 85℃의 온도에서 5배 내지 15배의 연신 배율로 수행될 수 있다. The stretching of the film laminate may be performed at a draw ratio of 5 times to 15 times at a temperature of 20 ° C. to 85 ° C.
본 발명은 상기 필름 적층체를 연신하는 단계 전에 미연신 폴리비닐알코올계 필름에 요오드 및 이색성 염료 중 적어도 하나를 염착시키는 단계를 더 포함할 수 있다. The present invention may further include the step of dyeing at least one of iodine and dichroic dye on the unstretched polyvinyl alcohol-based film before the stretching of the film laminate.
상기 연신된 필름 적층체의 고분자 필름과 폴리비닐알코올계 필름을 분리시키는 단계는 2N/2cm 이하의 박리력을 가하여 수행될 수 있다. Separating the polymer film and the polyvinyl alcohol-based film of the stretched film laminate may be performed by applying a peel force of 2N / 2cm or less.
또한, 본 발명은 상기 제조방법으로 제조되며, 두께가 10㎛ 이하이고, 단체 투과도 40 ~ 45%이며, 편광도가 99% 이상인 박형 편광자를 제공한다.In addition, the present invention provides a thin polarizer having a thickness of 10 μm or less, a single transmittance of 40 to 45%, and a degree of polarization of 99% or more.
또한, 본 발명은 상기 박형 편광자를 포함하는 편광판을 제공한다.In addition, the present invention provides a polarizing plate including the thin polarizer.
본 발명의 제조 방법에 따르면, 단순한 공정을 통해 10㎛ 이하의 두께를 갖는 박형의 편광자를 우수한 공정 안정성으로 제조할 수 있다.According to the production method of the present invention, a thin polarizer having a thickness of 10 μm or less can be manufactured with excellent process stability through a simple process.
또한, 본 발명과 같이, 적어도 둘 이상의 미연신 고분자 필름 사이에 PVA 필름이 적층된 필름 적층체를 이용하여 연신을 수행할 경우, 고배율 연신을 수행하는 경우에도 파단 발생율이 현저하게 저하되어 PVA 편광자의 배향도를 높일 수 있고, 그 결과 우수한 광학 물성을 갖는 박형 편광자를 제조할 수 있다. In addition, as in the present invention, when stretching is performed using a film laminate in which a PVA film is laminated between at least two or more unstretched polymer films, even when high magnification stretching is performed, the incidence of breakage is significantly lowered. The degree of orientation can be increased, and as a result, a thin polarizer having excellent optical properties can be manufactured.
도 1은 질감 분석기(Texture Analyzer)를 이용한 부착력 또는 박리력 측정 방법을 나타낸 모식도이다.1 is a schematic diagram showing a method for measuring adhesion or peeling force using a texture analyzer (Texture Analyzer).
도 2는 실시예 1 및 비교예 1 ~ 2에 의해 제조된 필름 적층체의 파단 발생율을 비교하여 보여주는 그래프이다.FIG. 2 is a graph showing the breakage incidence of the film laminates prepared by Example 1 and Comparative Examples 1 and 2. FIG.
도 3은 실시예 2에 의해 제조된 박형 편광자의 표면 상태를 보여주는 사진이다.Figure 3 is a photograph showing the surface state of the thin polarizer prepared by Example 2.
본 발명자들은 박형의 폴리비닐알코올계 편광필름을 제조하기 위해 오랜 연구를 거듭한 결과, 미연신 고분자 필름의 일면 또는 양면에 얇은 두께의 미연신 폴리비닐알코올계 필름을 부착하여 형성된 적층 필름을 이용하면, 제조 공정에서 파단이 발생하지 않고, 두께가 10㎛ 이하로 매우 얇으면서도 편광도 등의 광학 물성이 우수한 편광자를 제조할 수 있음을 알아내고, 10-2012-0130576(발명의 명칭: 박형 편광자의 제조 방법, 이를 이용하여 제조된 박형 편광자 및 편광판) 및 10-2012-0130577(발명의 명칭: 박형 편광자의 제조 방법, 이를 이용하여 제조된 박형 편광자 및 편광판)에 관한 발명을 출원하였다. The present inventors have conducted a long study to manufacture a thin polyvinyl alcohol polarizing film, and as a result, using a laminated film formed by attaching a thin unstretched polyvinyl alcohol-based film to one or both sides of the unstretched polymer film , No breakage occurred in the manufacturing process, and found that a polarizer excellent in optical properties such as polarization degree while having a very thin thickness of 10 μm or less can be produced. 10-2012-0130576 The present invention relates to a manufacturing method, a thin polarizer and a polarizing plate manufactured using the same) and 10-2012-0130577 (name of the invention: a manufacturing method of a thin polarizer, a thin polarizer and a polarizing plate manufactured using the same).
다만, 상기 출원 발명들의 경우 파단 발생율을 낮출 수 있는 정도에 있어서 한계점이 있었으며, 고분자 필름과 폴리비닐알코올계 필름 사이의 부착력이 낮기 때문에 공정 중에 폴리비닐알코올계 필름과 고분자 필름이 분리되거나, 이탈되는 등의 문제점이 발생하여 공정 안정성이 떨어진다는 문제점이 있었다. 따라서, 본 발명자들은 상기와 같은 문제점을 해결할 수 있는 파단 발생율이 낮고, 공정 안정성이 우수한 박형 편광자의 제조 방법을 개발하기 위해 연구를 거듭한 결과, 본 발명을 완성하였다. However, in the case of the above-described inventions, there was a limit in reducing the breakage rate, and because the adhesion between the polymer film and the polyvinyl alcohol-based film is low, the polyvinyl alcohol-based film and the polymer film are separated or separated during the process. There was a problem that the process stability is lowered due to such problems. Therefore, the present inventors have completed the present invention as a result of repeated studies to develop a thin polarizer having a low breakage rate and excellent process stability that can solve the above problems.
이하, 본 발명의 바람직한 실시 형태들을 설명한다. 그러나, 본 발명의 실시형태는 여러 가지 다른 형태로 변형될 수 있으며, 본 발명의 범위가 이하 설명하는 실시 형태로 한정되는 것은 아니다. 또한, 본 발명의 실시형태는 당해 기술분야에서 평균적인 지식을 가진 자에게 본 발명을 더욱 완전하게 설명하기 위해서 제공되는 것이다.Hereinafter, preferred embodiments of the present invention will be described. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. In addition, the embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.
본 발명의 박형 편광자 제조 방법은, 적어도 둘 이상의 미연신 고분자 필름 사이에 인력 또는 접착제층을 매개로 미연신 폴리비닐알코올계 필름을 부착하여 필름 적층체를 형성하는 단계, 연신된 폴리비닐알코올계 필름의 두께가 10㎛ 이하가 되도록 상기 필름 적층체를 연신하는 단계 및 상기 연신된 필름 적층체의 고분자 필름과 폴리비닐알코올계 필름을 분리시키는 단계를 포함한다. The method of manufacturing a thin polarizer of the present invention comprises the steps of: attaching an unstretched polyvinyl alcohol-based film to a film between at least two or more unstretched polymer films through a attraction force or an adhesive layer, the stretched polyvinyl alcohol-based film And stretching the film laminate such that the thickness thereof is 10 μm or less, and separating the polymer film and the polyvinyl alcohol-based film of the stretched film laminate.
상기와 같이 미연신 폴리비닐알코올계 필름의 양면에 미연신 고분자 필름이 위치하는 필름 적층체를 이용하는 경우, 한 장의 폴리비닐알코올계 필름에 대해 위, 아래 대칭형으로 고분자 필름이 위치하기 때문에, 상기 필름 적층체에 대한 연신 공정 등의 후속 공정에서 상기 폴리비닐알코올계 필름의 변형 가능성이 낮아져 편광자 제조의 공정 안정성이 향상될 뿐 아니라, 편광판 제조 시에 컬 특성도 우수하다. When using a film laminate in which an unstretched polymer film is located on both sides of an unstretched polyvinyl alcohol-based film as described above, since the polymer film is symmetrically positioned up and down with respect to one polyvinyl alcohol-based film, the film In a subsequent step such as a stretching step for the laminate, the possibility of deformation of the polyvinyl alcohol-based film is lowered, so that not only the process stability of the polarizer manufacturing is improved, but also the curl characteristics are excellent in the manufacturing of the polarizing plate.
또한, 상기 필름 적층체를 이용하는 경우, 고분자 필름이 두 장 이상이기 때문에, 한 장인 경우에 비해, 필름 적층체에 장력 인가시, 폴리비닐알코올계 필름의 단위 면적당 모듈러스 값이 낮아지게 되어 파단 발생률이 감소하고, 그 결과, 고배율 연신을 안정적으로 수행할 수 있다.In addition, in the case of using the film laminate, since there are two or more polymer films, when the tension is applied to the film laminate, the modulus value per unit area of the polyvinyl alcohol-based film is lowered compared to the case of one sheet, and thus the breakage rate is increased. As a result, it is possible to stably perform high magnification stretching.
또한, 상기와 같은 구조의 필름 적층체의 경우, 편광자 제조를 위한 습식 연신 공정에서 폴리비닐알코올계 필름의 팽윤도 증가에 따라 발생할 수 있는 폴리비닐알코올계 필름의 벗겨짐 및/또는 고분자 기재와의 분리현상 등을 효과적으로 억제할 수 있어 필름 적층체의 불안정성을 감소시킬 수 있다.In addition, in the case of the film laminate of the above structure, the peeling of the polyvinyl alcohol-based film which may occur due to the swelling degree of the polyvinyl alcohol-based film in the wet stretching process for manufacturing the polarizer and / or separation phenomenon with the polymer substrate Etc. can be effectively suppressed and the instability of the film laminate can be reduced.
또한, 상대적으로 붕산 농도가 적은 습식 연신 공정 조건에서는, 일반적으로, 팽윤된 폴리비닐알코올계 필름이 롤(roll)에 감겨 붙어버리는 현상이 발생할 수 있는데, 본 발명에 따르면, 폴리비닐알코올계 필름의 양면에 고분자 기재가 위치하고 있기 때문에 이와 같은 현상 발생이 방지되어, 저농도의 붕산 수용액에서도 적층체 손상 없이 공정을 진행할 수 있다. In addition, in wet drawing process conditions having a relatively low boric acid concentration, a phenomenon in which the swollen polyvinyl alcohol-based film is wound around a roll may occur. According to the present invention, a polyvinyl alcohol-based film may be used. Since the polymer base material is located on both sides, such a phenomenon is prevented, and the process can be performed without damaging the laminate even in a low concentration aqueous solution of boric acid.
한편, 본 출원인의 기출원된 특허 발명의 제조방법의 경우, 폴리비닐알코올계 필름이 고분자 필름의 일면 또는 양면에 부착되어 있기 때문에, 습식 연신 공정에서 폴리비닐알코올계 필름과 고분자 필름의 팽윤도 차이에 의해 폴리비닐알코올계 필름이 고분자 필름의 한쪽 방향으로 밀리는 현상이 발생한다는 문제점이 있었다. 그러나, 본 발명의 필름 적층체의 경우, 폴리비닐알코올계 필름이 외부로 노출되지 않기 때문에, 습식 연신 공정을 사용하는 경우에도 상기와 같은 현상이 최대한 억제된다.On the other hand, in the case of the manufacturing method of the present patent application of the present applicant, since the polyvinyl alcohol-based film is attached to one side or both sides of the polymer film, the difference in the swelling degree of the polyvinyl alcohol-based film and the polymer film in the wet stretching process This causes a problem that the polyvinyl alcohol-based film is pushed in one direction of the polymer film. However, in the case of the film laminate of the present invention, since the polyvinyl alcohol-based film is not exposed to the outside, the above phenomenon is suppressed as much as possible even when the wet stretching step is used.
또한, 폴리비닐알코올계 필름이 외부로 노출되어 있을 경우, 편광자 제조 공정 투입 전에, 필름 적층체를 롤 필름으로 와인딩(winding)하는 경우, 일반적으로 폴리비닐알코올계 필름 손상, 수분에 의해 폴리비닐알코올계 필름 면끼리 붙어 버리는 현상 및 주름 발생 등의 문제점이 발생할 수 있으나, 본 발명에 따르면 상기 문제점들을 미연에 방지할 수 있다. In addition, when the polyvinyl alcohol-based film is exposed to the outside, when the film laminate is rolled into a roll film before the polarizer manufacturing process is introduced, the polyvinyl alcohol is generally damaged by polyvinyl alcohol-based film damage or moisture. Problems such as sticking of the surface of the system film and occurrence of wrinkles may occur, but the above problems may be prevented in advance.
이하에서는 본 발명의 제조 방법을 보다 구체적으로 설명하기로 한다.Hereinafter, the manufacturing method of the present invention will be described in more detail.
먼저, 적어도 둘 이상의 미연신 고분자 필름 사이에 인력 또는 접착제층을 매개로 미연신 폴리비닐알코올계 필름을 부착하여 필름 적층체를 형성한다.First, an unstretched polyvinyl alcohol-based film is attached between at least two unstretched polymer films via a attraction force or an adhesive layer to form a film laminate.
본 발명에 있어서, 상기 필름 적층체는 2개 이상의 미연신 고분자 필름 사이에 미연신 폴리비닐알코올계 필름이 배치되는 형상이면 되고, 미연신 고분자 필름이나 미연신 폴리비닐알코올계 필름의 개수는 특별히 한정되지 않는다. In this invention, the said film laminated body should just be a shape in which an unstretched polyvinyl alcohol-type film is arrange | positioned between two or more unstretched polymer films, The number of an unstretched polymer film and an unstretched polyvinyl alcohol-type film is specifically limited. It doesn't work.
예를 들면, 상기 필름 적층체는, 제1미연신 고분자 필름, 상기 제1미연신 고분자 필름 상에 부착되는 제1미연신 폴리비닐알코올계 필름, 상기 제1미연신 폴리비닐알코올계 필름 상에 부착되는 제2미연신 고분자 필름으로 이루어진 구조, 즉 미연신 고분자 필름/미연신 폴리비닐알코올계 필름/미연신 고분자 필름과 같은 구조일 수 있다.For example, the said film laminated body is a 1st unstretched polyvinyl alcohol-type film adhered on a 1st unstretched polymer film, the said 1st unstretched polymer film, and the said 1st unstretched polyvinyl alcohol-type film It may have a structure made of a second unstretched polymer film to be attached, that is, a structure such as an unstretched polymer film / unstretched polyvinyl alcohol-based film / unstretched polymer film.
또는, 상기 필름 적층체는, 제1미연신 고분자 필름, 상기 제1미연신 고분자 필름 상에 부착되는 제1미연신 폴리비닐알코올계 필름, 상기 제1미연신 폴리비닐알코올계 필름 상에 부착되는 제2미연신 고분자 필름, 상기 제2미연신 고분자 필름 상에 부착되는 제2미연신 폴리비닐알코올계 필름 및 상기 제2미연신 폴리비닐알코올계 필름 상에 부착되는 제3미연신 고분자 필름으로 이루어진 구조, 즉, 미연신 고분자 필름/미연신 폴리비닐알코올계 필름/미연신 고분자 필름/미연신 폴리비닐알코올계 필름/미연신 고분자 필름과 같은 구조일 수도 있다. 상기한 구조들 이외에 더 많은 수의 고분자 필름이나 폴리비닐알코올계 필름을 적층한 필름 적층체를 사용할 수도 있으며, 이러한 변형이 모두 본 발명의 범주에 속하는 것은 자명할 것이다. Alternatively, the film laminate is attached to a first unstretched polymer film, a first unstretched polyvinyl alcohol-based film attached to the first unstretched polymer film, and the first unstretched polyvinyl alcohol-based film. A second unstretched polymer film, a second unstretched polyvinyl alcohol film adhered on the second unstretched polymer film, and a third unstretched polymer film adhered on the second unstretched polyvinyl alcohol film A structure such as an unstretched polymer film / unstretched polyvinyl alcohol-based film / unstretched polymer film / unstretched polyvinyl alcohol-based film / unstretched polymer film may be used. In addition to the above structures, a film laminate in which a larger number of polymer films or polyvinyl alcohol-based films are laminated may be used, and it will be apparent that all such modifications fall within the scope of the present invention.
한편, 본 발명의 필름 적층체에 2장 이상의 폴리비닐알코올계 필름이 포함되는 경우에도, 상기 폴리비닐알코올계 필름 각각의 양면에는 반드시 고분자 필름이 위치하게 된다. 따라서, 필름 적층체에 대한 추가 공정에서 폴리비닐알코올계 필름의 변형 가능성이 낮아지는 효과를 얻을 수 있으며, 그 원리는 상기 언급한 바와 같다.On the other hand, even when two or more polyvinyl alcohol-based films are included in the film laminate of the present invention, the polymer film is necessarily positioned on both surfaces of each of the polyvinyl alcohol-based films. Thus, the effect of lowering the possibility of deformation of the polyvinyl alcohol-based film in the further process for the film laminate can be obtained, the principle of which is as mentioned above.
한편, 본 발명의 필름 적층체에 사용되는 미연신 고분자 필름은 연신 공정에서 폴리비닐알코올계 필름이 파단되는 것을 방지하기 위한 것으로, 바람직하게는, 20℃ 내지 85℃ 온도 조건하에서 최대 연신 배율이 5배 이상인 고분자 필름일 수 있다. 이때, 상기 최대 연신 배율은 파단이 발생하기 직전의 연신 배율을 의미한다. 한편, 상기 연신은 건식 연신 또는 습식 연신일 수 있으며, 습식 연신의 경우, 붕산 농도가 1.0 내지 5중량%인 붕산 수용액에서 연신을 실시한 경우의 최대 연신 배율을 의미한다. On the other hand, the unstretched polymer film used in the film laminate of the present invention is for preventing the polyvinyl alcohol-based film from breaking in the stretching step, preferably, the maximum stretching ratio is 5 under the temperature conditions of 20 ℃ to 85 ℃. It may be a polymer film more than twice. In this case, the maximum draw ratio means a draw ratio immediately before breakage occurs. On the other hand, the stretching may be dry stretching or wet stretching, in the case of wet stretching, the stretching ratio in the case of stretching in an aqueous boric acid solution having a boric acid concentration of 1.0 to 5% by weight.
이러한 고분자 필름으로는, 이로써 한정되는 것은 아니나, 예를 들면, 고밀도 폴리에틸렌 필름, 폴리우레탄 필름, 폴리프로필렌 필름, 폴리올레핀 필름, 에스테르계 필름, 저밀도 폴리에틸렌 필름, 고밀도 폴리에틸렌 및 저밀도 폴리에틸렌 공압출 필름, 고밀도 폴리에틸렌에 에틸렌 비닐아세테이트가 함유된 공중합체 수지 필름, 아크릴 필름, 폴리에틸렌테레프탈레이트 필름, 폴리비닐알코올계 필름, 셀룰로오스계 필름 등을 들 수 있다. Such polymer films include, but are not limited to, high density polyethylene films and polyurethanes. Film, polypropylene film, polyolefin film, ester film, low density polyethylene film, high density polyethylene and low density polyethylene coextrusion film, copolymer resin film containing ethylene vinyl acetate in high density polyethylene, acrylic film, polyethylene terephthalate film, polyvinyl Alcohol Film, Cellulose Film Etc. can be mentioned.
한편, 본 발명에서 사용되는 상기 미연신 고분자 필름은, 그 두께가 20㎛ 내지 100㎛, 바람직하게는 30㎛ 내지 80㎛, 더 바람직하게는 40㎛ 내지 60㎛ 정도일 수 있다. 미연신 고분자 필름의 두께가 20㎛ 미만이면, 필름 적층체의 연신 공정에서 폴리비닐알코올계 필름을 충분히 지지하지 못해 파단 등이 발생할 수 있으며, 100㎛를 초과하는 경우에는 필름 적층체의 연신성이 저하될 수 있고, 폴리비닐알코올계 필름의 건조 시에 자유로운 폭 수축을 방해하여 최종적으로 얻어진 편광자의 광학 물성을 저해할 수 있기 때문이다.Meanwhile, the unstretched polymer film used in the present invention may have a thickness of about 20 μm to 100 μm, preferably about 30 μm to 80 μm, and more preferably about 40 μm to 60 μm. If the thickness of the unstretched polymer film is less than 20 µm, breakage may occur due to insufficient support of the polyvinyl alcohol-based film in the stretching process of the film laminate, and when the thickness of the unstretched polymer film exceeds 100 µm, the stretchability of the film laminate This is because the optical properties of the finally obtained polarizer may be inhibited by preventing free width shrinkage during drying of the polyvinyl alcohol-based film.
또한, 상기 미연신 고분자 필름의 유리전이온도는 폴리비닐알코올계 필름의 유리전이온도보다 낮은 것이 바람직하며, 예를 들면, 20℃ 내지 60℃ 정도, 바람직하게는 30℃ 내지 60℃ 정도인 것이 바람직하다. 일반적으로 폴리비닐알코올계 필름의 유리전이온도가 70℃ 내지 80℃ 정도임을 감안할 때, 고분자 필름의 유리전이온도가 상기 수치 범위를 만족할 경우, 연신 온도 조건에서 고분자 필름이 좀더 소프트(Soft)한 특성을 가질 수 있으며, 그 결과 폴리비닐알코올계 필름을 더 잘 연신시킬 수 있다. 다만, 고분자 필름의 유리전이온도가 너무 낮을 경우에는 고배율 연신 시에 파단이 발생할 수 있으므로, 고분자 필름의 유리전이온도는 20℃ 이상인 것이 바람직하다. 한편, 상기 유리전이온도는 시차주사형 열량계(DSC)에 의해 측정될 수 있다. 예를 들면, 약 10mg의 시료를 시차주사형 열량계(DSC)의 전용 팬(pan)에 밀봉하고 일정 승온 조건으로 가열할 때 상변이가 일어나면서 발생하는 흡열량 및 발열량을 온도에 따라 그려 유리전이온도를 측정할 수 있다. In addition, the glass transition temperature of the unstretched polymer film is preferably lower than the glass transition temperature of the polyvinyl alcohol-based film, for example, it is preferably about 20 ℃ to 60 ℃, preferably 30 ℃ to 60 ℃. Do. In general, considering that the glass transition temperature of the polyvinyl alcohol-based film is about 70 ° C. to 80 ° C., when the glass transition temperature of the polymer film satisfies the numerical range, the polymer film is more soft under the stretching temperature condition. It can have a result, it is possible to stretch the polyvinyl alcohol-based film better. However, when the glass transition temperature of the polymer film is too low, breakage may occur during high magnification stretching, and the glass transition temperature of the polymer film is preferably 20 ° C. or higher. On the other hand, the glass transition temperature may be measured by a differential scanning calorimeter (DSC). For example, when a sample of about 10 mg is sealed in a dedicated pan of a differential scanning calorimeter (DSC) and heated to a constant temperature condition, the endothermic and calorific values generated by phase shifting are plotted according to the temperature. The temperature can be measured.
또한, 상기 미연신 고분자 필름은 상온(25℃)에서의 모듈러스(Modulus)가 200MPa 내지 1500MPa 정도, 바람직하게는, 350MPa 내지 1300MPa 정도인 것이 바람직하다. 고분자 필름의 모듈러스가 1500MPa를 초과하는 경우에는 고배율 연신이 어려울 수 있으며, 200MPa 미만인 경우에는 연신 과정에서 파단이 발생할 수 있기 때문이다. 이때, 상기 모듈러스는 JIS-K6251-1 규격에 따라 준비된 샘플의 양 끝단을 고정시킨 후, 필름의 두께 방향에 수직한 방향으로 힘을 가하여 인장율(strain)에 따른 단위 면적당 응력(stress)를 측정하여 얻어진 값을 말하며, 측정 기기로는, 예를 들면, 인장력계(Zwick/Roell Z010 UTM) 등을 사용할 수 있다. In addition, the unoriented polymer film has a modulus at room temperature (25 ° C.) of about 200 MPa to 1500 MPa, preferably about 350 MPa to 1300 MPa. When the modulus of the polymer film exceeds 1500MPa, high magnification stretching may be difficult, and when less than 200MPa, breakage may occur in the stretching process. In this case, the modulus is fixed to both ends of the sample prepared according to JIS-K6251-1 standard, and then applied a force in a direction perpendicular to the thickness direction of the film to measure the stress per unit area according to the tensile rate (strain) The value obtained by this is referred to, and a tensile force meter (Zwick / Roell Z010 UTM) etc. can be used as a measuring instrument.
또한, 상기 미연신 고분자 필름은 상온(25℃)에서의 파단력(Force at Break Point)이 5N 내지 40N 정도, 바람직하게는 10N 내지 30N 정도일 수 있다. 이때, 파단력은 필름의 양 끝단을 고정시킨 후, 필름의 두께 방향에 수직한 방향으로 인장력을 가하였을 때 필름이 파단되는 시점에서의 인장력을 의미하는 것으로, 예를 들면, 인장력계(Zwick/Roell Z010 UTM) 등을 이용하여 측정할 수 있다. 미연신 고분자 필름의 파단력이 상기 수치 범위를 벗어나는 경우, 고배율 연신이 어렵거나, 연신 과정에서 파단이 발생하는 등의 문제점이 발생할 수 있다. In addition, the unstretched polymer film may have a force at break point at room temperature (25 ° C.) of about 5N to about 40N, preferably about 10N to about 30N. In this case, the breaking force refers to a tensile force at the time when the film is broken when fixing both ends of the film and then applying a tensile force in a direction perpendicular to the thickness direction of the film, for example, a tensile force meter (Zwick / Roell Z010 UTM) and the like can be measured. When the breaking force of the unstretched polymer film is out of the above numerical range, high magnification stretching may be difficult or breakage may occur in the stretching process.
한편, 본 발명의 경우, 2개 이상의 고분자 필름을 사용하는데, 이때 상기 고분자 필름들, 예를 들면, 상기 제1미연신 고분자 필름, 제2미연신 고분자 필름 및 제3미연신 고분자 필름 등은 동일한 고분자 필름일 수도 있고, 상이한 고분자 필름일 수도 있다. Meanwhile, in the present invention, two or more polymer films are used, wherein the polymer films, for example, the first unstretched polymer film, the second unstretched polymer film, and the third unstretched polymer film are the same. A polymer film may be sufficient and a different polymer film may be sufficient.
다음으로, 상기 미연신 고분자 필름 사이에 배치되는 미연신 폴리비닐알코올계 필름은 그 두께가 10㎛ 내지 60㎛ 정도, 바람직하게는 10㎛ 내지 40㎛ 정도인 것이 좋다. 미연신 폴리비닐알코올계 필름의 두께가 60㎛를 초과할 경우, 연신하여도 10㎛ 이하의 두께를 구현하기 어렵고, 그 두께가 10㎛ 미만인 경우에는 연신 중 파단이 발생하기 쉽다. Next, the unstretched polyvinyl alcohol-based film disposed between the unstretched polymer film has a thickness of about 10 μm to 60 μm, preferably about 10 μm to 40 μm. When the thickness of the unstretched polyvinyl alcohol-based film exceeds 60 µm, it is difficult to realize a thickness of 10 µm or less even when stretched, and when the thickness is less than 10 µm, breakage occurs easily during stretching.
한편, 상기 미연신 폴리비닐알코올계 필름은, 이로써 한정되는 것은 아니나, 중합도가 1,000 내지 10,000 정도, 바람직하게는 1,500 내지 5,000 정도인 것이 좋다. 중합도가 상기 범위를 만족할 때, 분자 움직임이 자유롭고, 요오드 또는 이색성 염료 등과 유연하게 혼합될 수 있기 때문이다.On the other hand, the unstretched polyvinyl alcohol-based film is not limited to this, but the degree of polymerization is preferably about 1,000 to 10,000, preferably 1,500 to 5,000. This is because when the degree of polymerization satisfies the above range, the molecular motion is free and can be mixed flexibly with iodine or dichroic dye.
한편, 본 발명의 미연신 폴리비닐알코올계 필름으로는 시판되는 폴리비닐알코올계 필름을 사용할 수 있으며, 예를 들면, 구라레 사의 PS30, PE30, PE60, 일본합성사의 M2000, M3000, M6000 등이 사용될 수 있다. Meanwhile, as the unstretched polyvinyl alcohol-based film of the present invention, a commercially available polyvinyl alcohol-based film may be used. For example, PS30, PE30, PE60 of Kureray Co., Ltd. M2000, M3000, M6000, etc. may be used. Can be.
한편, 본 발명의 필름 적층체에 2개 이상의 폴리비닐알코올계 필름이 사용될 경우에, 각각의 폴리비닐알코올계 필름은 그 조성이나 중합도 등이 서로 동일하거나 상이할 수 있다. On the other hand, when two or more polyvinyl alcohol-based films are used in the film laminate of the present invention, each polyvinyl alcohol-based film may have the same composition or different polymerization degree or the like.
한편, 상기 미연신 폴리비닐알코올계 필름은 요오드 및/또는 이색성 염료가 염착된 상태의 필름인 것이 바람직하다. 보다 바람직하게는, 상기 미연신 폴리비닐알코올계 필름은 팽윤 공정 및 염착 공정이 수행된 필름일 수 있다. On the other hand, it is preferable that the unstretched polyvinyl alcohol-based film is a film in which iodine and / or dichroic dye are dyed. More preferably, the unstretched polyvinyl alcohol-based film may be a film in which a swelling process and a dyeing process are performed.
이를 위해, 본 발명은, 상기 필름 적층체를 연신하기 전에, 미연신 폴리비닐알코올계 필름에 요오드 및/또는 이색성 염료를 염착하는 단계를 추가로 실시할 수 있으며, 바람직하게는 상기 미연신 폴리비닐알코올계 필름을 팽윤시키는 단계 및 상기 팽윤된 미연신 폴리비닐알코올계 필름에 요오드 및/또는 이색성 염료를 염착하는 단계를 추가로 실시할 수 있다. To this end, the present invention may further perform the step of dyeing iodine and / or dichroic dye on the unstretched polyvinyl alcohol-based film before the stretch of the film laminate, preferably the unstretched Swelling a polyvinyl alcohol-based film and dyeing iodine and / or dichroic dye on the swollen unstretched polyvinyl alcohol-based film may be further performed.
이때, 상기 미연신 폴리비닐알코올계 필름을 팽윤시키는 단계는 요오드 및/또는 이색성 염료가 폴리비닐알코올계 필름에 흡착, 확산되는 것을 촉진시키고, 폴리비닐알코올계 필름의 연신성을 향상시키기 위한 것으로, 이로써 한정되는 것은 아니나, 예를 들면, 미연신 폴리비닐알코올계 필름을 25℃ 내지 30℃의 순수에서 5초 내지 30초, 더 바람직하게는 10초 내지 20초 동안 침지시키는 방법으로 수행될 수 있다. 또한, 상기 팽윤은 미연신 폴리비닐알코올계 필름의 팽윤도가 36% 내지 44% 정도, 바람직하게는 38% 내지 42% 정도가 되도록 수행되는 것이 바람직하다. 미연신 폴리비닐알코올계 필름의 팽윤도가 상기 수치 범위를 만족할 경우, 최종적으로 제조되는 박형 편광자의 편광도 등과 같은 광학 특성이 매우 우수하게 나타난다. 한편, 상기 팽윤도는 {(팽윤 후 폴리비닐알코올계 필름의 중량 - 팽윤 전 폴리비닐알코올계 필름의 중량)/팽윤 전 폴리비닐알코올계 필름의 중량}×100으로 계산하였다. At this time, the step of swelling the unstretched polyvinyl alcohol-based film is to promote the adsorption and diffusion of the iodine and / or dichroic dye to the polyvinyl alcohol-based film, to improve the stretchability of the polyvinyl alcohol-based film For example, the present invention is not limited thereto. For example, the unstretched polyvinyl alcohol-based film may be immersed in pure water at 25 ° C. to 30 ° C. for 5 seconds to 30 seconds, more preferably 10 seconds to 20 seconds. have. In addition, the swelling is preferably performed so that the swelling degree of the unstretched polyvinyl alcohol-based film is about 36% to 44%, preferably about 38% to 42%. When the swelling degree of the unstretched polyvinyl alcohol-based film satisfies the above numerical range, optical properties such as the degree of polarization of the finally produced thin polarizer appear very excellent. Meanwhile, the swelling degree was calculated as {(weight of polyvinyl alcohol-based film after swelling-weight of polyvinyl alcohol-based film before swelling) / weight of polyvinyl alcohol-based film before swelling} × 100.
또한, 상기 미연신 폴리비닐알코올계 필름에 요오드 및/또는 이색성 염료를 염착하는 단계는 미연신 폴리비닐알코올계 필름을 요오드 및/또는 이색성 염료를 함유하는 염착 용액이 담긴 염착조에 함침시키거나, 요오드 및/또는 이색성 염료를 함유하는 염착 용액을 폴리비닐알코올계 필름 상에 도포하는 방법으로 수행될 수 있으며, 이때, 상기 염착 용액의 용매로는 일반적으로 물이 사용되지만, 물과 상용성을 갖는 유기 용매가 혼합되어 있어도 무방하다. 한편, 상기 염착 용액 내의 요오드 및/또는 이색성 염료의 함량은 용매 100 중량부에 대해서, 0.06 중량부 내지 0.25 중량부 정도일 수 있다. 또한, 상기 염착 용액에는 요오드 및/또는 이색성 염료 외에 염착 효율을 향상시키기 위한 보조제가 추가로 함유될 수 있으며, 상기 보조제로는 요오드화 칼륨, 요오드화 리튬, 요오드화 나트륨, 요오드화 아연, 요오드화 알루미늄, 요오드화 납, 요오드화 구리, 요오드화 바륨, 요오드화 칼슘, 요오드화 주석, 요오드화 티탄 또는 이들의 혼합물과 같은 요오드화 화합물이 사용될 수 있다. 이때, 상기 보조제의 함량은 용매 100중량부에 대하여 0.3중량부 내지 2.5 중량부 정도일 수 있으며, 보다 바람직하게는, 요오드 대 요오드화 화합물의 중량비가 1:5 내지 1: 10 정도일 수 있다. 한편, 상기 염착 단계는 25℃ 내지 40℃ 정도의 온도에서 수행되는 것이 바람직하며, 염착조 침지 시간은 30초 내지 120초 정도인 것이 바람직하나, 이로써 한정되는 것은 아니다.In addition, the step of dyeing iodine and / or dichroic dye on the unstretched polyvinyl alcohol-based film is impregnated in the dye bath containing a dye solution containing iodine and / or dichroic dye. Alternatively, a dyeing solution containing iodine and / or a dichroic dye may be applied onto a polyvinyl alcohol-based film, wherein water is generally used as a solvent of the dyeing solution, but is compatible with water. The organic solvent which has sex may be mixed. Meanwhile, the content of iodine and / or dichroic dye in the dyeing solution may be about 0.06 parts by weight to about 0.25 parts by weight based on 100 parts by weight of the solvent. In addition, the dyeing solution may further contain an adjuvant for improving the dyeing efficiency in addition to the iodine and / or dichroic dye, and the adjuvant includes potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide Iodide compounds such as copper iodide, barium iodide, calcium iodide, tin iodide, titanium iodide or mixtures thereof can be used. In this case, the content of the adjuvant may be about 0.3 parts by weight to about 2.5 parts by weight with respect to 100 parts by weight of the solvent, and more preferably, the weight ratio of iodine to iodide compound may be about 1: 5 to about 1:10. On the other hand, the dyeing step is preferably carried out at a temperature of about 25 ℃ to 40 ℃, the dyeing bath immersion time is preferably about 30 seconds to 120 seconds, but is not limited thereto.
한편, 상기와 같은 본 발명의 필름 적층체는 미연신 고분자 필름과 미연신 폴리비닐알코올계 필름을 접착제를 매개로 교대로 부착하거나, 또는 별도의 매개물 없이 교대로 적층함으로써 제조될 수 있다. On the other hand, the film laminate of the present invention as described above may be produced by alternately attaching the unstretched polymer film and the unstretched polyvinyl alcohol-based film alternately with an adhesive, or alternately laminated without a separate medium.
한편, 인력을 이용하여 상기 미연신 고분자 필름과 미연신 폴리비닐알코올계 필름을 부착할 경우에는, 고분자 필름이나 폴리비닐알코올계 필름의 일면 또는 양면에 표면처리를 수행함으로써 적절한 부착력을 가지도록 할 수 있다. 이때, 상기 표면처리는 당해 기술 분야에 잘 알려져 있는 다양한 표면처리 방법, 예를 들면, 코로나 처리, 플라즈마 처리 또는 NaOH나 KOH와 같은 강염기 수용액을 이용한 표면 개질 처리 등을 통해 수행될 수 있다. On the other hand, when attaching the unstretched polymer film and the unstretched polyvinyl alcohol-based film by the attraction, it is possible to have a proper adhesion by performing a surface treatment on one or both sides of the polymer film or polyvinyl alcohol-based film. have. In this case, the surface treatment may be performed 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.
한편, 접착제를 이용하여 미연신 고분자 필름과 미연신 폴리비닐알코올계 필름을 부착할 경우, 연신 전 접착제층의 두께는 20nm 내지 4000nm 정도, 바람직하게는 20nm 내지 1000nm 정도, 더 바람직하게는 20nm 내지 500nm 정도일 수 있다. 한편, 상기 필름 적층체의 연신 후 접착제층의 두께는 10nm 내지 1000nm 정도, 바람직하게는, 10nm 내지 500nm 정도, 더 바람직하게는, 10nm 내지 200nm 정도일 수 있다. 연신 전, 후의 접착제층의 두께가 상기 범위를 만족할 때, 연신 및 건조 공정 이후에 폴리비닐알코올계 필름을 손상 없이 박리하는데 유리하다.On the other hand, when the unstretched polymer film and the unstretched polyvinyl alcohol-based film are attached using an adhesive, the thickness of the adhesive layer before stretching is about 20 nm to 4000 nm, preferably about 20 nm to 1000 nm, and more preferably 20 nm to 500 nm. May be enough. On the other hand, the thickness of the adhesive layer after the stretching of the film laminate may be about 10nm to 1000nm, preferably 10nm to 500nm, more preferably 10nm to 200nm. When the thickness of the adhesive layer before and after stretching satisfies the above range, it is advantageous to peel the polyvinyl alcohol-based film without damage after the stretching and drying process.
한편, 상기 접착제는, 그 재질이 특별히 한정되는 것은 아니며, 당해 기술 분야에 알려진 다양한 접착제들이 제한없이 사용될 수 있다. 예를 들어, 상기 접착제층은 수계 접착제 또는 자외선 경화형 접착제로 형성될 수 있다. On the other hand, the adhesive, the material is not particularly limited, 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.
보다 구체적으로, 상기 접착제층은 폴리비닐알코올계 수지, 아크릴계 수지 및 비닐아세테이트계 수지로 이루어진 군으로부터 선택된 1종 이상을 포함하는 수계 접착제에 의해 형성될 수 있다. More specifically, the adhesive layer may be formed by an aqueous adhesive including at least one selected from the group consisting of polyvinyl alcohol-based resins, acrylic resins, and vinyl acetate-based resins.
또는, 상기 접착제층은 아크릴기 및 히드록시기를 갖는 폴리비닐알코올계 수지를 포함하는 수계 접착제에 의해 형성될 수 있다. 이때, 상기 아크릴기 및 히드록시기를 갖는 폴리비닐알코올계 수지는 중합도가 500 내지 1800 정도일 수 있다. Alternatively, the adhesive layer may be formed by an aqueous adhesive including a polyvinyl alcohol-based resin having an acrylic group and a hydroxyl group. At this time, the polyvinyl alcohol-based resin having an acrylic group and a hydroxyl group may have a degree of polymerization of about 500 to 1800.
또는, 상기 접착층은, 아세트아세틸기 함유 폴리비닐알코올계 수지에 아민계 금속 화합물 가교제를 포함하는 수계 접착제를 이용하여 형성될 수 있다. 보다 구체적으로는, 상기 접착제는 아세트아세틸기를 함유하는 폴리비닐알코올계 수지 100중량부 및 아민계 금속 화합물 가교제 1 내지 50중량부를 포함하는 수용액일 수 있다.Alternatively, the adhesive layer may be formed using an aqueous adhesive including an amine-based metal compound crosslinking agent in acetacetyl group-containing polyvinyl alcohol-based resin. More specifically, the adhesive may be an aqueous solution containing 100 parts by weight of a polyvinyl alcohol-based resin containing an acetacetyl group and 1 to 50 parts by weight of an amine metal compound crosslinking agent.
여기서, 상기 폴리비닐알코올계 수지의 중합도 및 검화도는 아세트아세틸기를 함유하기만 하면 특별히 한정되지 않으나, 중합도가 200 ~ 4,000이며, 검화도가 70몰% ~ 99.9몰%인 것이 바람직하다. 분자 움직임의 자유로움에 따른 함유 물질과의 유연한 혼합을 고려하면 중합도는 1,500 ~ 2,500이며, 검화도는 90몰% ~ 99.9몰%인 것이 더욱 바람직하다. 이때, 상기 폴리비닐알코올계 수지는 상기 아세트아세틸기를 0.1 ~ 30몰%로 포함하는 것이 바람직하다. 상기한 범위에서 아민계 금속화합물 가교제와의 반응이 원활할 수 있으며, 목적하는 접착제의 내수성에 충분히 유의적일 수 있다.Here, the polymerization degree and saponification degree of the polyvinyl alcohol-based resin are not particularly limited as long as they contain acetacetyl group, but the polymerization degree is 200 to 4,000, and the saponification degree is preferably 70 mol% to 99.9 mol%. Considering flexible mixing with the containing material according to the freedom of molecular movement, the degree of polymerization is 1,500 to 2,500, and the degree of saponification is more preferably 90 mol% to 99.9 mol%. In this case, the polyvinyl alcohol-based resin preferably comprises 0.1 to 30 mol% of the acetacetyl group. In the above range, the reaction with the amine-based metal compound crosslinking agent may be smooth, and may be sufficiently significant for the water resistance of the desired adhesive.
상기 아민계 금속화합물 가교제는 상기 폴리비닐알코올계 수지와의 반응성을 갖는 관능기를 가지는 수용성 가교제로서 아민계 리간드를 함유하는 금속 착물 형태인 것이 바람직하다. 가능한 금속으로는 지르콘늄(Zr), 타이타늄(Ti), 하프늄(Hf), 텅스텐(W), 철(Fe), 코발트(Co), 니켈(Ni), 루테늄(Ru), 오스뮴(Os), 로듐(Rh), 이리듐(Ir), 팔라듐(Pd), 백금(Pt) 등의 전이 금속이 가능하며, 중심 금속에 결합된 리간드로는 일차아민, 이차아민(다이아민), 삼차아민 이나 암모늄하이드록사이드 등의 적어도 하나 이상의 아민기를 포함한 것이면 모두 가능하다.The amine-based metal compound crosslinking agent is a water-soluble crosslinking agent having a functional group having reactivity with the polyvinyl alcohol-based resin, preferably in the form of a metal complex containing an amine ligand. Possible metals include zirconium (Zr), titanium (Ti), hafnium (Hf), tungsten (W), iron (Fe), cobalt (Co), nickel (Ni), ruthenium (Ru), osmium (Os), Transition metals such as rhodium (Rh), iridium (Ir), palladium (Pd) and platinum (Pt) are possible, and ligands bound to the central metal are primary amines, secondary amines (diamines), tertiary amines or ammonium hydrides. As long as it contains at least 1 or more amine groups, such as a lockside, it is all possible.
또한, 상기 접착제에 있어서, 상기 아세트아세틸기를 함유하는 폴리비닐알코올계 수지의 고형분 함량은 1중량% 내지 10중량%정도인 것이 바람직하다. 폴리비닐알코올계 수지의 고형분 함량이 1중량% 미만인 경우에는 내수성이 충분히 확보되지 않아 연신 공정에서의 파단 발생율 저하 효과가 적고, 10중량%를 초과할 경우에는 작업성이 떨어지고, 박리 시에 폴리비닐알코올계 필름 표면에 손상이 발생할 수 있기 때문이다. In the adhesive, the solid content of the polyvinyl alcohol-based resin containing the acetacetyl group is preferably about 1% by weight to about 10% by weight. If the solid content of the polyvinyl alcohol-based resin is less than 1% by weight, the water resistance is not sufficiently secured, so that the effect of lowering the breakage rate in the stretching process is less. If the content is more than 10% by weight, the workability is deteriorated. This is because damage may occur on the alcohol-based film surface.
한편, 상기 접착제의 pH는 4.5 내지 9 정도인 것이 바람직하다. 접착제의 pH가 상기 수치 범위를 만족할 경우, 저장성, 고습 환경에서의 내구성에 있어서 보다 유리하기 때문이다. On the other hand, the pH of the adhesive is preferably 4.5 to 9 or so. When the pH of an adhesive agent satisfy | fills the said numerical range, it is because it is more advantageous in storage property and durability in a high humidity environment.
한편, 상기 접착제의 pH는 수용액 중에 산을 함유시키는 방법으로 조절할 수 있으며, 이때, 상기 pH 조절을 위해 사용되는 산은 강산 및 약산 모두 사용가능하다. 예를 들면, 질산, 염산, 황산 또는 아세트산 등이 사용될 수 있다. On the other hand, the pH of the adhesive can be adjusted by the method of containing an acid in the aqueous solution, wherein the acid used for pH adjustment can be used both strong and weak acid. For example, nitric acid, hydrochloric acid, sulfuric acid or acetic acid and the like can be used.
상기와 같은 접착제에 의해 형성되는 접착제층의 두께는 필름 적층체의 연신 전에는 80nm 내지 200nm 정도, 바람직하게는 80nm 내지 150nm 정도이고, 필름 적층체의 연신 후에는 10nm 내지 100nm 정도, 바람직하게는 10nm 내지 80nm 정도인 것이 바람직하다. 접착제층의 두께가 상기 범위를 만족할 경우, 기재 필름과 폴리비닐알코올계 필름의 접착력이 적절한 수준으로 유지되어 연신 공정에서의 파단 발생율이 저하되는 동시에 박리 시에 편광자 표면 손상을 최소화할 수 있기 때문이다.The thickness of the adhesive layer formed by the above adhesive is about 80 nm to 200 nm, preferably about 80 nm to 150 nm before stretching the film laminate, and after stretching the film laminate, about 10 nm to 100 nm, preferably 10 nm to It is preferable that it is about 80 nm. This is because when the thickness of the adhesive layer satisfies the above range, the adhesion between the base film and the polyvinyl alcohol-based film is maintained at an appropriate level so that the breakage rate in the stretching process is reduced and the polarizer surface damage during peeling can be minimized. .
상기 접착제의 경우, 경화 시에 아민계 금속 화합물과 폴리비닐알코올계 수지의 아세트아세틸기 사이에 가교 반응이 일어나, 경화 후 접착층의 내수성이 매우 우수해진다. 따라서, 상기 접착제를 이용하여 고분자 필름과 폴리비닐알코올계 필름을 적층할 경우, 습식 연신 시에 접착제가 물에 녹아나오는 현상을 최소화할 수 있어, 습식 연신을 수행하는 경우에 특히 유용하게 사용될 수 있다. In the case of the said adhesive agent, a crosslinking reaction occurs between the amine type metal compound and the acetacetyl group of polyvinyl alcohol-type resin at the time of hardening, and the water resistance of the adhesive layer after hardening becomes very excellent. Therefore, when the polymer film and the polyvinyl alcohol-based film are laminated using the adhesive, the phenomenon in which the adhesive dissolves in water during wet stretching can be minimized, and thus it can be particularly useful when performing wet stretching. .
한편, 상기 접착제층은, 자외선 경화형 접착제로 형성될 수도 있으며, 예를 들면, 호모폴리머의 유리전이온도가 120℃ 이상인 제1에폭시 화합물, 호모폴리머의 유리전이온도가 60℃ 이하인 제2에폭시 화합물 및 양이온성 광 중합 개시제를 포함하는 자외선 경화형 접착제로 형성될 수 있다. 구체적으로, 상기 자외선 경화형 접착제는 호모폴리머의 유리전이온도가 120℃ 이상인 제1에폭시 화합물 100 중량부, 호모폴리머의 유리전이온도가 60℃ 이하인 제2에폭시 화합물 30 내지 100 중량부 및 양이온성 광 중합 개시제 0.5 내지 20 중량부를 포함할 수 있다. Meanwhile, the adhesive layer may be formed of an ultraviolet curable adhesive, for example, a first epoxy compound having a glass transition temperature of homopolymer of 120 ° C. or more, a second epoxy compound having a glass transition temperature of homopolymer of 60 ° C. or less and It may be formed of an ultraviolet curable adhesive containing a cationic photopolymerization initiator. Specifically, the UV-curable adhesive is 100 parts by weight of the first epoxy compound having a glass transition temperature of the homopolymer of 120 ℃ or more, 30 to 100 parts by weight of the second epoxy compound having a glass transition temperature of the homopolymer of 60 ℃ or less and cationic photopolymerization It may include 0.5 to 20 parts by weight of the initiator.
본 명세서에서 에폭시 화합물은 분자 내에 1개 이상의 에폭시기를 갖는 화합물을 의미하는 것으로, 바람직하게는 분자 내에 2개 이상의 에폭시기를 갖는 화합물이며, 단량체(monomer), 중합체(polymer) 또는 수지(resin)의 형태의 화합물들을 모두 포함하는 개념이다. 바람직하게는 본 발명의 에폭시 화합물은 수지 형태일 수 있다. As used herein, an epoxy compound refers to a compound having one or more epoxy groups in a molecule, preferably a compound having two or more epoxy groups in a molecule, and is in the form of a monomer, a polymer, or a resin. The concept includes all of the compounds. Preferably the epoxy compound of the present invention may be in the form of a resin.
한편, 상기 제1에폭시 화합물로는, 호모폴리머의 유리전이온도가 120℃ 이상인 에폭시 화합물이면 특별한 제한 없이 사용될 수 있으며, 예를 들면, 호모 폴리머의 유리전이온도가 120℃ 이상인 지환족 에폭시 화합물 및/또는 방향족 에폭시가 본 발명의 제1에폭시 화합물로 사용될 수 있다. 호모폴리머의 유리전이온도가 120℃ 이상인 에폭시 화합물의 구체적인 예로는, 3,4-에폭시시클로헥실메틸-3,4'-에폭시시클로헥산카복실레이트, 비닐사이클로헥센디옥사이드 디시클로펜타디엔디옥사이드, 비스에폭시사이클로펜틸에테르, 비스페놀 A 계 에폭시 화합물, 비스페놀 F 계 에폭시 화합물 등을 들 수 있다. 한편, 상기 제1에폭시 화합물은 호모폴리머의 유리전이온도가 120℃ 내지 200℃ 정도인 것이 보다 바람직하다.On the other hand, as the first epoxy compound, if the glass transition temperature of the homopolymer is an epoxy compound of 120 ℃ or more can be used without particular limitation, for example, the alicyclic epoxy compound and the glass transition temperature of the homo polymer is 120 ℃ or more and / Or aromatic epoxy may be used as the first epoxy compound of the present invention. Specific examples of the epoxy compound having a glass transition temperature of homopolymer of 120 ° C. or higher include 3,4-epoxycyclohexylmethyl-3,4′-epoxycyclohexanecarboxylate, vinylcyclohexenedioxide dicyclopentadiene dioxide, and bisepoxycyclo. A pentyl ether, a bisphenol A type epoxy compound, a bisphenol F type epoxy compound, etc. are mentioned. On the other hand, the first epoxy compound is more preferably the glass transition temperature of the homopolymer is about 120 ℃ to 200 ℃.
다음으로, 상기 제2에폭시 화합물은, 호모폴리머의 유리전이온도가 60℃ 이하인 에폭시 화합물이면 특별한 제한 없이 사용될 수 있다. 예를 들면, 상기 제2에폭시 화합물로 지환족 에폭시 화합물, 지방족 에폭시 화합물 등이 사용될 수 있다.Next, the second epoxy compound may be used without particular limitation as long as the glass transition temperature of the homopolymer is an epoxy compound of 60 ° C. or less. For example, an alicyclic epoxy compound, an aliphatic epoxy compound, or the like may be used as the second epoxy compound.
이때, 상기 지환족 에폭시 화합물로는, 2관능형 에폭시 화합물, 즉 2개의 에폭시를 가지는 화합물을 사용하는 것이 바람직하고, 상기 2개의 에폭시기가 모두 지환식 에폭시기인 화합물을 사용하는 것이 보다 바람직하지만, 이에 제한되는 것은 아니다.In this case, as the alicyclic epoxy compound, it is preferable to use a bifunctional epoxy compound, that is, a compound having two epoxies, and more preferably use a compound in which the two epoxy groups are both alicyclic epoxy groups. It is not limited.
지방족 에폭시 화합물로는, 지환족 에폭시기가 아닌 지방족 에폭시기를 가지는 에폭시 화합물이 예시될 수 있다. 예를 들면, 지방족 다가 알코올의 폴리글리시딜에테르; 지방족 다가 알코올의 알킬렌옥시드 부가물의 폴리글리시딜에테르; 지방족 다가 알코올과 지방족 다가 카복실산의 폴리에스테르 폴리올의 폴리글리시딜에테르; 지방족 다가 카복실산의 폴리글리시딜에테르; 지방족 다가 알코올과 지방족 다가 카복실산의 폴리에스테르 폴리카복실산의 폴리글리시딜에테르; 글리시딜 아크릴레이트 또는 글리시딜 메타크릴레이트의 비닐 중합에 의해 얻어지는 다이머, 올리고머 또는 폴리머; 또는 글리시딜 아크릴레이트 또는 글리시딜 메타크릴레이트와 다른 비닐계 단량체의 비닐 중합에 의해 얻어지는 올리고머 또는 폴리머가 예시될 수 있고, 바람직하게는 지방족 다가 알코올 또는 그 알킬렌옥시드 부가물의 폴리글리시딜에테르가 사용될 수 있으나, 이에 제한되는 것은 아니다.As an aliphatic epoxy compound, the epoxy compound which has an aliphatic epoxy group which is not an alicyclic epoxy group can be illustrated. For example, polyglycidyl ether of aliphatic polyhydric alcohol; Polyglycidyl ethers of alkylene oxide adducts of aliphatic polyhydric alcohols; Polyglycidyl ethers of polyester polyols of aliphatic polyhydric alcohols and aliphatic polyhydric carboxylic acids; Polyglycidyl ethers of aliphatic polyvalent carboxylic acids; Polyglycidyl ethers of polyester polycarboxylic acids of aliphatic polyhydric alcohols and aliphatic polyhydric carboxylic acids; Dimers, oligomers or polymers obtained by vinyl polymerization of glycidyl acrylate or glycidyl methacrylate; Or oligomers or polymers obtained by vinyl polymerization of glycidyl acrylate or glycidyl methacrylate with other vinyl monomers, preferably polyglycidyl of aliphatic polyhydric alcohols or their alkylene oxide adducts. Ether may be used, but is not limited thereto.
상기에서 지방족 다가 알코올로는, 예를 들면, 탄소수 2 내지 20, 탄소수 2 내지 16, 탄소수 2 내지 12, 탄소수 2 내지 8 또는 탄소수 2 내지 4의 지방족 다가 알코올이 예시될 수 있고, 예를 들면, 에틸렌글리콜, 1,2-프로판디올, 1,3-프로판디올, 2-메틸-1,3-프로판디올, 2-부틸-2-에틸-1,3-프로판디올, 1,4-부탄디올, 네오펜틸글리콜, 3-메틸-2,4-펜탄디올, 2,4-펜탄디올, 1,5-펜탄디올, 3-메틸-1,5-펜탄디올, 2-메틸-2,4-펜탄디올, 2,4-디에틸-1,5-펜탄디올, 1,6-헥산디올, 1,7-헵탄디올, 3,5-헵탄디올, 1,8-옥탄디올, 2-메틸-1,8-옥탄디올, 1,9-노난디올, 1,10-데칸디올 등의 지방족 디올; 시클로헥산디메탄올, 시클로헥산디올, 수소 첨가 비스페놀 A, 수소 첨가 비스페놀 F 등의 지환식 디올; 트리메틸올에탄, 트리메틸올프로판, 헥시톨류, 펜티톨류, 글리세린, 폴리글리세린, 펜타에리스리톨, 디펜타에리스리톨, 테트라메틸올프로판 등이 예시될 수 있다.As the aliphatic polyhydric alcohol, for example, an aliphatic polyhydric alcohol having 2 to 20 carbon atoms, 2 to 16 carbon atoms, 2 to 12 carbon atoms, 2 to 8 carbon atoms or 2 to 4 carbon atoms may be exemplified. Ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-butanediol, neo Pentyl glycol, 3-methyl-2,4-pentanediol, 2,4-pentanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 3,5-heptanediol, 1,8-octanediol, 2-methyl-1,8- Aliphatic diols such as octanediol, 1,9-nonanediol and 1,10-decanediol; Alicyclic diols such as cyclohexanedimethanol, cyclohexanediol, hydrogenated bisphenol A and hydrogenated bisphenol F; Trimethylol ethane, trimethylol propane, hexitols, pentitols, glycerin, polyglycerol, pentaerythritol, dipentaerythritol, tetramethylol propane and the like can be exemplified.
또한, 상기에서 알킬렌옥시드로는, 탄소수 1 내지 20, 탄소수 1 내지 16, 탄소수 1 내지 12, 탄소수 1 내지 8 또는 탄소수 1 내지 4의 알킬렌옥시드가 예시될 수 있고, 예를 들면, 에틸렌옥시드, 프로필렌옥시드 또는 부틸렌옥시드 등이 사용될 수 있다.In addition, as the alkylene oxide in the above, alkylene oxide of 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms or 1 to 4 carbon atoms can be exemplified, for example, ethylene jade Seeds, propylene oxide or butylene oxide and the like can be used.
또한, 상기 지방족 다가 카복실산으로는, 예를 들면, 옥살산, 말론산, 숙신산, 글루타르산, 아디프산, 피멜산, 수베린산, 아젤라산, 세바신산, 도데칸이산, 2-메틸숙신산, 2-메틸아디프산, 3-메틸아디프산, 3-메틸펜탄이산, 2-메틸옥탄이산, 3,8-디메틸데칸이산, 3,7-디메틸데칸이산, 1,20-에이코사메틸렌디카르복실산, 1,2-시클로펜탄디카르복실산, 1,3-시클로펜탄디카르복실산, 1,2-시클로헥산디카르복실산, 1,3-시클로헥산디카르복실산, 1,4-시클로헥산디카르복실산, 1,4-디카르복실메틸렌시클로헥산, 1,2,3-프로판트리카르복실산, 1,2,3,4-부탄테트라카르복실산, 1,2,3,4-시클로부탄테트라카르복실산 등이 예시될 수 있으나, 이에 제한되는 것은 아니다.Moreover, as said aliphatic polyhydric carboxylic acid, For example, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, sumeric acid, azelaic acid, sebacic acid, dodecane diacid, 2-methyl succinic acid, 2-methyladipic acid, 3-methyladipic acid, 3-methylpentaneic acid, 2-methyloctanoic acid, 3,8-dimethyldecanediic acid, 3,7-dimethyldecanediic acid, 1,20-eicosamethylenedica Carboxylic acid, 1,2-cyclopentanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1, 4-cyclohexanedicarboxylic acid, 1,4-dicarboxymethylenecyclohexane, 1,2,3-propanetricarboxylic acid, 1,2,3,4-butanetetracarboxylic acid, 1,2, 3,4-cyclobutanetetracarboxylic acid and the like can be exemplified, but is not limited thereto.
바람직하게는, 본 발명의 상기 제2에폭시 화합물은 글리시딜 에테르기를 하나 이상 포함하는 것일 수 있으며, 예를 들면, 1,4-시클로헥산디메탄올 디글리시딜 에테르, 1,4-부탄디올디글시딜에테르, 1,6-헥산디올디글리시딜에테르, 네오펜틸디글시딜에테르, 레조시놀디글리시딜에테르, 디에틸렌글라이콜디글리시딜에테르, 에틸렌글라이콜디글리시딜에테르, 트리메틸올프로판트리글리시딜에테르, n-부틸 글리시딜 에테르, 2-에틸헥실 글리시딜 에테르, 페닐 글리시딜 에테르, 및 o-크레실(Cresyl) 글리시딜 에테르로 이루어진 그룹으로부터 선택된 1종 이상이 본 발명의 제2에폭시 화합물로 사용될 수 있다. Preferably, the second epoxy compound of the present invention may include one or more glycidyl ether groups, for example, 1,4-cyclohexanedimethanol diglycidyl ether, 1,4-butanediol diggle Cydyl ether, 1,6-hexanediol diglycidyl ether, neopentyl diglycidyl ether, resorcinol diglycidyl ether, diethylene glycol diglycidyl ether, ethylene glycol diglycidyl ether, One selected from the group consisting of trimethylolpropanetriglycidyl ether, n-butyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, and o-cresyl glycidyl ether The above can be used as the second epoxy compound of the present invention.
한편, 상기 제2에폭시 화합물은 호모폴리머의 유리전이온도가 0℃ 내지 60℃ 정도인 것이 보다 바람직하다On the other hand, it is more preferred that the second epoxy compound has a glass transition temperature of about 0 ° C to 60 ° C of the homopolymer.
한편, 이로써 한정되는 것은 아니나, 본 발명의 경우, 상기 에폭시 화합물로 에폭시화 지방족 고리기를 하나 이상 포함하는 제1에폭시 화합물 및 글리시딜에테르기를 하나 이상 포함하는 제2에폭시 화합물의 조합을 사용하는 것이 특히 바람직하다. Meanwhile, the present invention is not limited thereto, but in the present invention, it is preferable to use a combination of the first epoxy compound including at least one epoxidized aliphatic ring group and the second epoxy compound including at least one glycidyl ether group as the epoxy compound. Particularly preferred.
상기와 같은 방법으로 필름 적층체를 형성한 다음, 상기 필름 적층체를 연신한다. 이때, 상기 연신은 폴리비닐알코올계 필름의 두께가 10㎛이하가 되도록 수행하는 것이 바람직하며, 예를 들면, 폴리비닐알코올계 필름의 두께가 1㎛ 내지 10㎛, 3㎛ 내지 10㎛ 또는 1㎛ 내지 5㎛ 정도가 되도록 수행하는 것이 바람직하다. After forming a film laminate in the same manner as described above, the film laminate is stretched. In this case, the stretching is preferably carried out so that the thickness of the polyvinyl alcohol-based film is less than 10㎛, for example, the thickness of the polyvinyl alcohol-based film is 1㎛ to 10㎛, 3㎛ to 10㎛ or 1㎛ It is preferable to carry out so that it becomes about 5 micrometers.
한편, 본 발명에 있어서, 연신 조건은 특별히 한정되는 것은 아니나, 예를 들면, 상기 연신은 20℃ 내지 85℃의 온도에서 5배 내지 15배의 연신 배율로 수행될 수 있으며, 보다 바람직하게는 40℃ 내지 80℃의 온도에서 5배 내지 12배의 연신 배율로 수행될 수 있다.On the other hand, in the present invention, the stretching conditions are not particularly limited, for example, the stretching may be carried out at a draw ratio of 5 times to 15 times at a temperature of 20 ℃ to 85 ℃, more preferably 40 It may be carried out at a draw ratio of 5 to 12 times at a temperature of ℃ to 80 ℃.
이때, 상기 연신은 습식 연신 또는 건식 연신으로 수행될 수 있다. 다만, 습식 연신을 실시하는 경우, 건식 연신에 비해 열가소성 폴리우레탄 필름과 폴리비닐알코올계 필름의 표면 부착력이 강해지기 때문에 별도의 접착 수단이 없이 안정적으로 연신을 수행할 수 있다는 점에서 보다 바람직하다. 한편, 상기 습식 연신은 붕산 수용액 내에서 수행되는 것이 바람직하며, 이때, 상기 붕산 수용액의 붕산 농도는 1.0~5.0 wt% 정도인 것이 바람직하다. In this case, the stretching may be performed by wet stretching or dry stretching. However, when the wet stretching is performed, since the surface adhesion of the thermoplastic polyurethane film and the polyvinyl alcohol-based film is stronger than the dry stretching, the stretching can be performed stably without a separate bonding means. On the other hand, the wet stretching is preferably carried out in an aqueous boric acid solution, wherein the boric acid concentration of the aqueous boric acid solution is preferably about 1.0 to 5.0 wt%.
상기와 같은 붕산 수용액에서 연신이 수행될 경우, 붕산 가교로 인해 PVA 필름의 파단 발생율이 저하되어 공정 안정성이 증대되며, 습식 공정 중 발생하기 쉬운 PVA 필름의 주름 발생을 제어할 수 있다. 또한 건식연신 대비 저온에서도 연신이 가능하다는 장점이 있다. When the stretching is performed in the aqueous boric acid solution as described above, the breakage rate of the PVA film is lowered due to the boric acid crosslinking, thereby increasing process stability and controlling wrinkles of the PVA film, which is easily generated during the wet process. In addition, there is an advantage that stretching is possible at low temperatures compared to dry stretching.
한편, 일반적으로 편광소자 제조 공정은, 수세, 팽윤, 염착, 세정, 연신, 보색, 건조 등의 과정으로 이루어지는데, 본 발명의 경우, 세정 및 연신 공정이 붕산 수용액에서 수행되는 것이 바람직하다. 보다 바람직하게는, 세정 공정의 경우 붕산 농도가 0.1~2.5 wt% 정도, 바람직하게는 0.5~2.0 wt% 정도일 수 있으며, 연신 공정의 경우 붕산 농도는 1.0~5.0 wt% 정도, 바람직하게는 1.5~4.5 wt%정도일 수 있다. On the other hand, in general, the manufacturing process of the polarizing element is a process of washing with water, swelling, dyeing, washing, stretching, complementary color, drying and the like, in the case of the present invention, the washing and stretching process is preferably carried out in an aqueous boric acid solution. More preferably, in the cleaning process, the boric acid concentration may be about 0.1 to 2.5 wt%, preferably about 0.5 to 2.0 wt%, and in the stretching process, the boric acid concentration is about 1.0 to 5.0 wt%, preferably 1.5 to It may be about 4.5 wt%.
한편, 상기 필름 적층체의 연신 후에 연신 폴리비닐알코올계 필름과 연신된 고분자 필름 사이의 부착력은 2N/2cm 이하, 바람직하게는, 0.1 내지 2N/2cm 정도, 더 바람직하게는 0.1 내지 1N/2cm 정도일 수 있다. 연신 고분자 필름과 연신 폴리비닐알코올 필름 사이의 부착력이 상기 범위를 만족할 경우, 분리 과정에서 표면 손상을 최소화할 수 있기 때문이다. 본 발명의 제조 방법에 따르면, 폴리비닐알코올계 필름과 고분자 필름 사이에 접착제층이 형성되어 있는 경우, 연신에 의해 폴리비닐알코올계 필름, 고분자 필름뿐 아니라 접착제층도 함께 연신되기 때문에, 접착제층의 두께가 연신 전 대비 10 ~ 50% 수준으로 감소하게 되며, 그 결과 폴리비닐알코올계 필름과 고분자 필름 사이의 부착력이 2N/2cm 이하로 저하되어 분리하기 쉬운 상태가 된다. 한편, 상기 부착력은 2cm 길이의 샘플 필름들을 부착하였을 때 측정되는 부착력이며, 구체적인 측정 방법은 도 1에 도시되어 있다. 본 발명에 있어서, 상기 필름들 사이의 부착력은, 도 1에 도시된 바와 같이, 필름 적층체의 폴리비닐알코올 필름(A)을 샘플 홀더(H)로 고정한 후, 필름 적층체의 면 방향에 대해 수직한 방향으로 힘을 가하여 고분자 필름(B)으로부터 폴리비닐알코올 필름(A)을 박리하면서 측정한 박리력(Peel Strength)의 크기를 말하며, 이때 측정 기기로는 Stable Micro Systems사의 Texture Analyzer (모델명: TA-XT Plus)를 사용하였다. On the other hand, the adhesion between the stretched polyvinyl alcohol-based film and the stretched polymer film after the stretching of the film laminate is 2N / 2cm or less, preferably, about 0.1 to 2N / 2cm, more preferably about 0.1 to 1N / 2cm. Can be. This is because when the adhesion between the stretched polymer film and the stretched polyvinyl alcohol film satisfies the above range, surface damage can be minimized during the separation process. According to the production method of the present invention, when the adhesive layer is formed between the polyvinyl alcohol-based film and the polymer film, the adhesive layer is stretched together by stretching, as well as the polyvinyl alcohol-based film and the polymer film. The thickness is reduced to a level of 10 to 50% compared to before stretching, and as a result, the adhesion force between the polyvinyl alcohol-based film and the polymer film is lowered to 2N / 2cm or less, thereby making it easy to separate. On the other hand, the adhesive force is the adhesive force measured when the sample films of 2cm length is attached, a specific measuring method is shown in FIG. In the present invention, the adhesion between the films, as shown in Figure 1, after fixing the polyvinyl alcohol film (A) of the film laminate with a sample holder (H), with respect to the surface direction of the film laminate Peel strength measured by peeling the polyvinyl alcohol film (A) from the polymer film (B) by applying a force in a vertical direction, wherein the measuring instrument is a texture analyzer (Stable Micro Systems, Inc.) TA-XT Plus) was used.
한편, 상기와 같이 필름 적층체를 연신한 후에, 필요에 따라, 연신된 필름 적층체를 건조하는 단계를 더 포함할 수 있다. 이때, 상기 건조는 20 내지 100℃, 더 바람직하게는 40 내지 90℃ 정도인 것이 좋으며, 상기의 온도로 1 내지 10분 동안 수행되는 것이 바람직하다. 건조 공정은 PVA 표면 및 내부의 수분 제거를 통해 편관판 제조공정 중 수분에 의한 PVA 편광자의 물성 저하를 방지하고, 건조 과정에서 연신된 폴리비닐알코올 필름의 폭수축을 원활하게 유도해주어 폴리비닐알코올 및 요오드로 구성된 착체의 배향성을 증대시켜 편광자의 편광도를 향상시키는 역할을 한다.On the other hand, after stretching the film laminate as described above, if necessary, further comprising the step of drying the stretched film laminate. At this time, the drying is preferably 20 to 100 ℃, more preferably about 40 to 90 ℃, it is preferably carried out for 1 to 10 minutes at the above temperature. The drying process prevents the PVA polarizer from deteriorating the physical properties of the PVA polarizer by water removal during the production of the PVA surface and the inside and smoothly induces the shrinkage of the polyvinyl alcohol film stretched during the drying process. It serves to improve the polarization degree of the polarizer by increasing the orientation of the complex composed of iodine.
다음으로, 상기 연신된 필름 적층체의 고분자 필름과 폴리비닐알코올계 필름을 분리시킨다. 본 발명에 있어서, 상기 분리 단계는 상기 폴리비닐알코올계 필름에 약한 박리력을 가하여 고분자 필름으로부터 이탈시키는 방법으로 수행될 수 있다. 이때, 상기 박리력은 2N/2cm 이하인 것이 바람직하며, 예를 들면, 0.1 내지 2N/2cm 또는 0.1 내지 1N/2cm 정도일 수 있다. Next, the polymer film and the polyvinyl alcohol-based film of the stretched film laminate are separated. In the present invention, the separating step may be performed by applying a weak peel force to the polyvinyl alcohol-based film to be separated from the polymer film. At this time, the peel force is preferably 2N / 2cm or less, for example, may be about 0.1 to 2N / 2cm or 0.1 to 1N / 2cm.
이와 같이, 본 발명의 경우, 코팅이나 공압출을 이용하여 적층된 경우에 비해, 폴리비닐알코올계 필름과 고분자 필름을 분리하는데 요구되는 박리력이 매우 약하기 때문에 별다른 공정이나 장비 없이도 두 필름을 쉽게 분리할 수 있을 뿐 아니라, 분리 공정에서 폴리비닐알코올계 필름의 손상이 적어 매우 우수한 광학 성능을 나타낸다.As described above, in the case of the present invention, since the peel force required to separate the polyvinyl alcohol-based film and the polymer film is very weak compared to the case of lamination using a coating or co-extrusion, the two films are easily separated without any other process or equipment. Not only that, but also the damage of the polyvinyl alcohol-based film in the separation process is very low, it shows very excellent optical performance.
한편, 상기와 같은 본 발명의 박형 편광자 제조 방법은, 당해 기술 분야에 잘 알려져 있는 시트-투-시트(sheet-to-sheet) 공정, 시트-투-롤(sheet-to-roll) 공정 또는 롤-투-롤(roll-to-roll) 공정 등을 통해 수행될 수 있다. 이때, 시트-투-시트 공정은 원료 필름(즉, 폴리비닐알코올계 필름 및 고분자 필름)으로 일정한 크기로 재단되어 있는 매엽형 필름을 사용하는 방법이며, 시트-투-롤 공정은 원료 필름 중 일부로는 길이가 긴 필름이 권취된 롤형 필름을 사용하고, 다른 원료 필름으로는 일정한 크기로 재단되어 있는 매엽형 필름을 사용하는 방법을 말한다. 또한, 롤-투-롤 공정은 원료 필름으로 롤형 필름을 사용하는 방법이다. 공정의 연속성 및 생산성을 고려할 때, 이 중에서도 롤-투-롤 공정을 사용하는 것이 특히 바람직하다. On the other hand, the thin polarizer manufacturing method of the present invention as described above, sheet-to-sheet (sheet-to-sheet) process, sheet-to-roll process or roll well known in the art It may be carried out through a roll-to-roll process or the like. At this time, the sheet-to-sheet process is a method using a sheet-like film cut to a predetermined size with a raw film (ie, polyvinyl alcohol-based film and a polymer film), the sheet-to-roll process is a part of the raw film Refers to a method of using a rolled film wound with a long film and using a sheet-like film cut to a constant size as another raw film. In addition, a roll-to-roll process is a method of using a rolled film as a raw film. In view of the continuity and productivity of the process, it is particularly preferred to use a roll-to-roll process among these.
예를 들면, 본 발명의 제조 방법은, 미연신 고분자 필름 롤 사이에 미연신 폴리비닐알코올계 필름 롤을 배치하고, 상기 필름 롤들로부터 폴리비닐알코올계 필름과 고분자 필름을 권출하면서 2N/2cm 이하의 부착력을 갖는 인력 또는 접착제층을 매개로 부착하여 적어도 둘 이상의 미연신 고분자 필름 및 미연신 폴리비닐알코올계 필름을 포함하는 필름 적층체를 형성하는 단계; 연신 후 폴리비닐알코올계 필름의 두께가 10㎛ 이하가 되도록 상기 필름 적층체를 연신하는 단계; 및 상기 연신된 필름 적층체의 고분자 필름과 폴리비닐알코올계 필름을 분리시키는 단계를 포함할 수 있다. For example, in the production method of the present invention, a non-stretched polyvinyl alcohol-based film roll is disposed between the unstretched polymer film rolls, and the polyvinyl alcohol-based film and the polymer film are unwound from the film rolls, respectively, of 2 N / 2 cm or less. Attaching at least two unstretched polymer films and unstretched polyvinyl alcohol-based films to form a film laminate including an attraction force or an adhesive layer having adhesion; Stretching the film laminate so that the polyvinyl alcohol-based film has a thickness of 10 μm or less after stretching; And separating the polymer film and the polyvinyl alcohol-based film of the stretched film laminate.
한편, 상기 적어도 2 이상의 미연신 고분자 필름과 미연신 폴리비닐알코올계 필름은 부착된 후, 롤 형상으로 재권취된 다음, 재권취된 필름 적층체 롤로부터 필름 적층체를 권출하여 연신 공정에 투입될 수도 있고, 또는 재권취 없이 바로 연신 공정에 투입될 수 있다.On the other hand, the at least two or more unstretched polymer film and the unstretched polyvinyl alcohol-based film is attached, and then rewound in a roll shape, then unwinds the film laminate from the rewound film laminate roll to be introduced into the stretching process. It may be, or may be added directly to the stretching process without rewinding.
또한, 상기 분리 단계는 고분자 필름과 폴리비닐알코올계 필름 사이에 박리 수단(예를 들면, 박리 롤)을 삽입하여, 고분자 필름과 폴리비닐알코올계 필름의 계면을 분리시킨 다음, 분리된 고분자 필름과 폴리비닐알코올계 필름을 서로 다른 롤에 권취하는 방법으로 수행될 수 있다In addition, in the separating step, a separation means (eg, a peeling roll) is inserted between the polymer film and the polyvinyl alcohol-based film to separate the interface between the polymer film and the polyvinyl alcohol-based film, and then the separated polymer film and It can be carried out by the method of winding the polyvinyl alcohol-based film in different rolls.
상기와 같은 방법에 의해 제조된 본 발명의 편광자는 그 두께가 10㎛ 이하, 바람직하게는 1㎛ 내지 10㎛ 정도, 보다 바람직하게는 3㎛ 내지 10㎛ 정도로 매우 얇다. 또한, 이와 같이 얇은 두께에서도, 단체 투과도가 40 ~ 45% 정도이며, 편광도가 99% 이상으로 나타나 매우 우수한 광학 물성을 나타낸다. The polarizer of the present invention produced by the above method is very thin, the thickness of which is about 10 μm or less, preferably about 1 μm to 10 μm, more preferably about 3 μm to 10 μm. In addition, even at such a thin thickness, the unitary transmittance is about 40 to 45%, and the polarization degree is 99% or more, indicating very excellent optical properties.
또한, 본 발명의 편광자는 폭 방향에 대한 편광도 균일성이 매우 우수하다. 보다 구체적으로는, 본 발명의 편광자는, 편광자의 폭 방향을 따라 등간격으로 위치하는 10개의 점에서 측정된 편광도의 표준 편차가 0.002% 이하이다. Moreover, the polarizer of this invention is very excellent in the uniformity of the polarization degree to the width direction. More specifically, the polarizer of the present invention has a standard deviation of the degree of polarization measured at ten points located at equal intervals along the width direction of the polarizer at 0.002% or less.
한편, 상기와 같은 본 발명의 편광자에 일면 또는 양면에 투명 필름을 적층하여 편광판을 형성할 수 있다. 이때 상기 투명 필름으로는, 당해 기술 분야에서 편광자 보호 필름 또는 위상차 필름으로 사용되는 다양한 필름들이 제한 없이 사용될 수 있으며, 예를 들면, 아크릴계 필름, PET필름, 아크릴계 프라이머 처리가 된 PET필름, 셀룰로오스계 필름, 사이클로올레핀계 필름, 폴리카보네이트계 필름, 폴리노보넨계 필름 등이 사용될 수 있다.On the other hand, a polarizing plate can be formed by laminating a transparent film on one side or both sides on the polarizer of the present invention as described above. In this case, as the transparent film, various films used as a polarizer protective film or a retardation film in the art may be used without limitation, for example, an acrylic film, a PET film, an acrylic primer treated PET film, a cellulose film , Cycloolefin-based film, polycarbonate-based film, polynorbornene-based film and the like can be used.
편광자와 투명 필름의 적층 방법은 특별히 제한되지 않으며, 당해 기술 분야에 잘 알려진 필름 합지 방법, 예를 들면, 상기 편광자 및/또는 투명 필름의 적어도 일면에 접착제 또는 점착제를 도포한 후 상기 편광자와 투명 필름을 합지하는 방법 등을 이용하여 수행될 수 있다. 이때 상기 점착제 또는 접착제는 사용되는 투명 필름의 재질 등을 고려하여 적절하게 선택될 수 있으며, 예를 들면, 투명 필름으로 TAC을 사용하는 경우에는 폴리비닐알코올계 접착제와 같은 수계 접착제를 이용할 수 있고, 투명 필름으로 아크릴 필름이나 COP 필름 등을 사용하는 경우에는 아크릴계 접착제, 에폭시계 접착제와 같은 광 경화 또는 열경화성 접착제를 이용할 수 있다.The laminating method of the polarizer and the transparent film is not particularly limited, and a film lamination method well known in the art, for example, after applying an adhesive or an adhesive to at least one surface of the polarizer and / or the transparent film, the polarizer and the transparent film It may be performed using a method such as laminating. At this time, the pressure-sensitive adhesive or adhesive may be appropriately selected in consideration of the material of the transparent film to be used, for example, when using a TAC as a transparent film, an aqueous adhesive such as a polyvinyl alcohol-based adhesive may be used, When using an acrylic film, a COP film, etc. as a transparent film, photocuring or thermosetting adhesives, such as an acrylic adhesive and an epoxy adhesive, can be used.
한편, 상기 편광자와 투명 필름의 적층 방식은, 특별히 제한되는 것은 아니나, 생산성 측면에서 편광자 필름 롤과 투명 필름 롤을 이용한 롤-투-롤 방식으로 이루어지는 것이 바람직하다. 롤-투-롤 방식으로 편광자와 투명 필름을 적층하여 편광판을 제조하는 방법은 당해 기술 분야에 잘 알려져 있으므로, 구체적인 설명은 생략한다. 이와 같이 롤-투-롤 방식으로 편광판을 제조할 경우, 장척의 롤형 편광판을 얻을 수 있다. On the other hand, the lamination method of the polarizer and the transparent film is not particularly limited, but is preferably made of a roll-to-roll method using a polarizer film roll and a transparent film roll in terms of productivity. Since a method of manufacturing a polarizing plate by laminating a polarizer and a transparent film in a roll-to-roll manner is well known in the art, a detailed description thereof will be omitted. Thus, when manufacturing a polarizing plate by a roll-to-roll system, a long rolled polarizing plate can be obtained.
한편, 상기 본 발명의 편광판은, 투명 필름 이외에 휘도향상필름, 프라이머층, 하드코팅층, 방현층, 반사 방지층 또는 액정 패널과의 부착을 위한 점착층 등과 같은 다른 기능성 광학층을 추가로 포함할 수 있다. 이들 광학층은 형성 방법은 특별히 한정되지 않으며, 당해 기술 분야에 잘 알려진 공지의 방법을 이용할 수 있다. On the other hand, the polarizing plate of the present invention, in addition to the transparent film may further include other functional optical layers, such as brightness enhancement film, primer layer, hard coating layer, anti-glare layer, anti-reflection layer or adhesive layer for adhesion with the liquid crystal panel. . The formation method of these optical layers is not specifically limited, The well-known method well known in the art can be used.
본 발명의 편광판은 종래의 편광판에 비해 그 두께가 매우 얇으면서도 우수한 광학 특성을 가져, 액정표시패널, 유기전계발광장치 등과 같은 디스플레이 장치에 유용하게 사용될 수 있다. The polarizing plate of the present invention has a very thin thickness compared to the conventional polarizing plate and has excellent optical properties, and thus may be usefully used in display devices such as liquid crystal display panels and organic light emitting display devices.
이하, 구체적인 실시예를 통해 본 발명을 보다 자세히 설명한다. Hereinafter, the present invention will be described in more detail with reference to specific examples.
실시예 1Example 1
미연신 폴리우레탄 필름 3장 및 미연신 폴리비닐알코올계 필름 2장을 매개물 없이 교대로 적층하여, 미연신 폴리우레탄 필름/미연신 폴리비닐알코올계 필름/미연신 폴리우레탄 필름/미연신 폴리비닐알코올계 필름/미연신 폴리우레탄 필름 구조의 필름 적층체를 형성하였다. Three unstretched polyurethane films and two unstretched polyvinyl alcohol-based films are alternately laminated without a medium, and the unstretched polyurethane film / unstretched polyvinyl alcohol-based film / unstretched polyurethane film / unstretched polyvinyl alcohol The film laminated body of the system film / unstretched polyurethane film structure was formed.
이때, 상기 미연신 폴리비닐알코올계 필름으로는 Kuraray사의 PE30 그레이드 폴리비닐알코올계 필름(두께: 30㎛)을 사용하였으며, 25℃ 순수 용액에서 15초간 팽윤 (swelling) 시킨 후, 0.3wt% 농도 및 25℃의 요오드 용액에서 60초간 염착 공정을 진행한 폴리비닐알코올계 필름을 사용하였다.In this case, as the unstretched polyvinyl alcohol-based film, Kuraray's PE30 grade polyvinyl alcohol-based film (thickness: 30 μm) was used, and after swelling for 15 seconds in a 25 ° C. pure water solution, 0.3 wt% concentration and A polyvinyl alcohol-based film which was subjected to a dyeing process for 60 seconds in an iodine solution at 25 ° C. was used.
미연신 폴리우레탄 필름으로는 메틸렌디페닐디이소시아네이트, 1,4-부탄디올 및 아디프산을 반응시켜 얻어진 열가소성 폴리우레탄 수지를 이용하여 제조된 필름을 사용하였다.  As the unstretched polyurethane film, a film prepared using a thermoplastic polyurethane resin obtained by reacting methylenediphenyl diisocyanate, 1,4-butanediol and adipic acid was used.
비교예 1Comparative Example 1
미연신 폴리비닐알코올계 필름 3장 및 미연신 폴리우레탄 필름 2장을 매개물 없이 교대로 적층하여, 미연신 폴리비닐알코올계 필름/미연신 폴리우레탄 필름/미연신 폴리비닐알코올계 필름/미연신 폴리우레탄 필름/미연신 폴리비닐알코올계 필름 구조의 필름 적층체를 형성하였다. 상기 미연신 폴리비닐알코올계 필름과 미연신 폴리우레탄 필름으로는 실시예 1과 동일한 것을 사용하였다.Three unstretched polyvinyl alcohol films and two unstretched polyurethane films are laminated alternately without a medium, and the unstretched polyvinyl alcohol film / unstretched polyurethane film / unstretched polyvinyl alcohol film / unstretched poly The film laminated body of urethane film / unstretched polyvinyl alcohol-type film structure was formed. As the unstretched polyvinyl alcohol-based film and the unstretched polyurethane film, the same ones as in Example 1 were used.
비교예 2Comparative Example 2
미연신 폴리우레탄 필름의 양면에 미연신 폴리비닐알코올계 필름을 매개물 없이 교대로 적층하여 미연신 폴리비닐알코올계 필름/미연신 폴리우레탄 필름/미연신 폴리비닐알코올계 필름 구조의 필름 적층체를 형성하였다. 상기 미연신 폴리비닐알코올계 필름과 미연신 폴리우레탄 필름으로는 실시예 1과 동일한 것을 사용하였다.The unstretched polyvinyl alcohol film is alternately laminated on both sides of the unstretched polyurethane film without a medium to form a film laminate having an unstretched polyvinyl alcohol film / unstretched polyurethane film / unstretched polyvinyl alcohol film structure. It was. As the unstretched polyvinyl alcohol-based film and the unstretched polyurethane film, the same ones as in Example 1 were used.
비교예 3Comparative Example 3
Kuraray사의 PE30 그레이드 폴리비닐알코올계 필름(두께: 30㎛)을 25℃ 순수 용액에서 15초간 팽윤 (swelling) 시킨 후, 0.3wt% 농도 및 25℃의 요오드 용액에서 60초간 염착 공정을 진행하여 준비하였다.Kuraray's PE30 grade polyvinyl alcohol film (thickness: 30 μm) was prepared by swelling in pure water at 25 ° C. for 15 seconds, followed by dyeing for 60 seconds in 0.3 wt% concentration and iodine solution at 25 ° C. .
실험예 1- 파단 발생율 측정Experimental Example 1 Measurement of Breakage Incidence
상기 실시예 1, 비교예 1~2의 필름 적층체 및 비교예 3의 폴리비닐알코올계 필름을 붕산 1wt% 용액에서 15초간 세정한 후, 52℃, 2.5wt%의 붕산 용액에서 적어도 하나의 폴리비닐알코올계 필름에서 파단이 일어나기 직전까지, 6 ~ 8배의 연신 배율로 연신하였다. After washing the film laminate of Example 1, Comparative Examples 1 and 2 and the polyvinyl alcohol-based film of Comparative Example 3 in a 1 wt% solution of boric acid for 15 seconds, at least one poly in 52 ℃, 2.5 wt% boric acid solution Stretching was performed at a draw ratio of 6 to 8 times until breakage occurred in the vinyl alcohol film.
연신 공정 전의 폴리비닐알코올계 필름의 두께에 대한 연신 공정 후의 폴리비닐알코올계 필름의 두께 비율을, 하기 수식에 따라 계산하였다. 계산 결과는 도 2에 도시하였다. The thickness ratio of the polyvinyl alcohol-based film after the stretching step to the thickness of the polyvinyl alcohol-based film before the stretching step was calculated according to the following formula. The calculation result is shown in FIG.
두께 비율(dr)(%) = {연신 후 폴리비닐알코올계 필름의 두께(d)/연신 전 폴리비닐알코올계 필름의 두께(d0)} ×100Thickness ratio (dr) (%) = {thickness of polyvinyl alcohol-based film after stretching (d) / thickness of polyvinyl alcohol-based film before stretching (d 0 )} × 100
상기 두께 비율(dr)의 수치가 작을수록 파단 없이 연신이 잘 이루어져, 연신 후 폴리비닐알코올계 필름의 두께가 얇음을 의미한다.The smaller the numerical value of the thickness ratio dr is, the better the stretching is made without breaking, which means that the thickness of the polyvinyl alcohol-based film is thin after stretching.
도 2에 도시된 바와 같이, 폴리비닐알코올계 필름을 단독 연신한 비교예 3의 경우, 상기 두께 비율(dr)은 27% 정도였으며, 비교예 1 및 비교예 2의 두께 비율(dr)은 대략 21% ~ 22% 정도였다. 이에 비해 실시예 1의 경우 두께 비율이 19%로 비교예 1~2에 비해 파단 없이 연신이 잘 이루어졌음을 알 수 있다. As shown in FIG. 2, in Comparative Example 3 in which the polyvinyl alcohol-based film was drawn alone, the thickness ratio dr was about 27%, and the thickness ratio dr of Comparative Examples 1 and 2 was approximately. 21% to 22%. On the other hand, in the case of Example 1, the thickness ratio is 19%, and it can be seen that stretching was performed well without breaking compared to Comparative Examples 1 and 2.
실시예 2Example 2
실시예 1의 미연신 필름 적층체를 붕산 1wt% 용액에서 15초간 세정한 후, 52℃, 2.5wt%의 붕산 용액에서 7배 연신하였다. 이후, 5wt%의 요오드화 칼륨(KI) 용액에서 보색 공정을 거친 후, 80℃ 오븐에서 5분간 건조 공정을 진행하였다. 그런 다음, 연신된 필름 적층체에서, 폴리비닐알코올계 필름을 폴리우레탄 기재로부터 각각 분리하여 박형 편광자를 얻었다. 편광자의 두께는 7~10㎛이었다. The unstretched film laminate of Example 1 was After washing for 15 seconds in a 1 wt% solution of boric acid, it was stretched 7 times in a boric acid solution of 52 ℃, 2.5 wt%. Thereafter, after 5% by weight of potassium iodide (KI) solution through a complementary color process, the drying process was performed for 5 minutes in an 80 ℃ oven. Then, in the stretched film laminate, the polyvinyl alcohol-based films were separated from the polyurethane substrate, respectively, to obtain a thin polarizer. The thickness of the polarizer was 7-10 micrometers.
한편, 도 3에는 상기 실시예 2의 건조 공정을 마친 필름 적층체의 표면 상태를 보여주는 사진이 도시되어 있다. 도 3에 도시된 바와 같이, 실시예 2의 필름 적층체를 이용할 경우, 파단 없이 안정적인 연신 공정이 이루어졌을 뿐 아니라, 폴리비닐알코올계 필름의 표면 상태가 균일하고 양호함을 알 수 있다. On the other hand, Figure 3 is a photograph showing the surface state of the film laminate after the drying step of Example 2 is shown. As shown in FIG. 3, when the film laminate of Example 2 is used, not only a stable stretching process is performed without breaking, but also the surface state of the polyvinyl alcohol-based film is uniform and good.
실시예 3Example 3
순수에 아세트아세틸기 (5중량%)를 함유하는 폴리비닐알코올(평균 중합도 2000, 감화도 94%, 일본 합성사)를 녹여 4중량% 수용액을 제조하였다. 여기에 티타늄 아민 콤플렉스 가교제(제품명: TYZOR TE, 듀폰사)를 폴리비닐알코올 100중량부당 6.7 중량부의 비로 첨가하여 교반하면서 혼합하여 접착제 A를 제조하였다. A 4% by weight aqueous solution was prepared by dissolving polyvinyl alcohol (average degree of polymerization 2000, degree of 94%, Japanese Synthetic) containing acetacetyl group (5% by weight) in pure water. Titanium amine complex crosslinking agent (product name: TYZOR TE, DuPont) was added at a ratio of 6.7 parts by weight per 100 parts by weight of polyvinyl alcohol and mixed with stirring to prepare an adhesive A.
미연신 폴리우레탄 필름 1장의 양면에 상기 접착제 A를 100nm 두께로 도포한 후, 미연신 폴리비닐알코올계 필름 2장을 부착하여 미연신 폴리비닐알코올계 필름/미연신 폴리우레탄 필름/미연신 폴리비닐알코올계 필름 구조의 필름 적층체 1을 제조하였다. 그런 다음, 상기 필름 적층체 1을 25℃ 순수 용액에서 15초간 팽윤 (swelling) 시킨 후, 0.3wt% 농도 및 25℃의 요오드 용액에서 60초간 염착 공정을 진행하였다. After apply | coating said adhesive agent A to 100 nm thickness on both surfaces of an unstretched polyurethane film, two unstretched polyvinyl alcohol-type films were affixed, and an unstretched polyvinyl alcohol-type film / an unstretched polyurethane film / unstretched polyvinyl The film laminated body 1 of alcohol type film structure was produced. Then, the film laminate 1 was swelled for 15 seconds in a 25 ° C. pure solution, followed by a dyeing process for 60 seconds in a 0.3 wt% concentration and an iodine solution at 25 ° C.
그런 다음, 상기 필름 적층체 1의 양면에 인력으로 미연신 폴리우레탄 필름 2장을 부착하여, 미연신 폴리우레탄/ 미연신 폴리비닐알코올계 필름/미연신 폴리우레탄 필름/미연신 폴리비닐알코올계/미연신 폴리우레탄 구조의 미연신 필름 적층체를 제조하였다. Then, two unstretched polyurethane films were attached to both surfaces of the film laminate 1 by attraction, and the unstretched polyurethane / unstretched polyvinyl alcohol-based film / unstretched polyurethane film / unstretched polyvinyl alcohol-based / An unstretched film laminate of an unstretched polyurethane structure was produced.
이때, 상기 미연신 폴리비닐알코올계 필름으로는 일본합성사의 M2000그레이드 폴리비닐알코올계 필름(두께: 20㎛)을 사용하였으며, 미연신 폴리우레탄 필름으로는 메틸렌디페닐디이소시아네이트, 1,4-부탄디올 및 아디프산을 반응시켜 얻어진 열가소성 폴리우레탄 수지를 이용하여 제조된 필름을 사용하였다. In this case, M2000-grade polyvinyl alcohol-based film (thickness: 20㎛) of Japan Synthetic Inc. was used as the unstretched polyvinyl alcohol-based film, and methylene diphenyl diisocyanate and 1,4-butanediol were used as the unstretched polyurethane film. And a film prepared using a thermoplastic polyurethane resin obtained by reacting adipic acid.
상기 미연신 필름 적층체를 붕산 1wt% 용액에서 15초간 세정 공정을 거친 후 52℃, 2.5중량%의 붕산 용액에서 7배의 연신 배율로 상기 필름 적층체를 연신하였다. 그런 다음, 5wt%의 요오드화 칼륨(KI) 용액에서 보색 공정을 거친 후, 80℃ 오븐에서 5분간 건조하였다. 그런 다음, 폴리우레탄 필름과 폴리비닐알코올계 필름을 0.7N/2cm의 박리력으로 분리하여 5~8㎛ 두께의 박형 편광자 2장을 얻었다. After the unstretched film laminate was washed in a 1 wt% solution of boric acid for 15 seconds, the film laminate was stretched at a draw ratio of 7 times at 52 ° C. and 2.5 wt% of boric acid solution. Then, after a complementary color process in a 5 wt% potassium iodide (KI) solution, it was dried for 5 minutes in an 80 ℃ oven. Then, the polyurethane film and the polyvinyl alcohol-based film were separated with a peel force of 0.7 N / 2 cm to obtain two thin polarizers having a thickness of 5 to 8 µm.
실험예 2 - 광학 물성 측정Experimental Example 2-Measurement of Optical Properties
실시예 2 및 실시예 3에 따라 제조된 박형 편광자의 단체 투과도, 편광도 및 단체 색상, 직교 색상 등의 광학 물성을 JASCO V-7100 Spectrophotometer로 측정하였다. 측정 결과는 [표 1]에 나타내었다. Optical properties such as single transmittance, polarization degree, single color, and orthogonal color of the thin polarizers prepared according to Examples 2 and 3 were measured with a JASCO V-7100 Spectrophotometer. The measurement results are shown in [Table 1].
표 1
구분 단체투과율(% ) 편광도(%) 단체 색상 직교 색상
a b a b
실시예 2 40.44 99.9860 -0.50 1.78 0.89 -1.71
실시예 3 40.75 99.9893 -0.61 1.99 0.71 -1.57
Table 1
division Group transmittance (%) % Polarization Group colors Orthogonal colors
a b a b
Example 2 40.44 99.9860 -0.50 1.78 0.89 -1.71
Example 3 40.75 99.9893 -0.61 1.99 0.71 -1.57
상기 [표 1]를 통해, 본 발명의 방법에 따라 제조된 박형 편광자가 단체 투과도, 편광도, 색감 등의 광학 물성이 우수함을 알 수 있다. Through Table 1, it can be seen that the thin polarizer manufactured according to the method of the present invention has excellent optical properties such as single transmittance, polarization degree, and color.
[부호의 설명][Description of the code]
H: 홀더H: Holder
A: 폴리비닐알코올계 필름A: polyvinyl alcohol film
B: 고분자 필름B: polymer film
MD: 종연신 방향MD: Longitudinal stretching direction

Claims (15)

  1. 적어도 둘 이상의 미연신 고분자 필름 사이에 인력 또는 접착제층을 매개로 미연신 폴리비닐알코올계 필름을 부착하여 필름 적층체를 형성하는 단계;Attaching an unstretched polyvinyl alcohol-based film between at least two unstretched polymer films via an attractive or adhesive layer to form a film laminate;
    폴리비닐알코올계 필름의 두께가 10㎛ 이하가 되도록 상기 필름 적층체를 연신하는 단계; 및 Stretching the film laminate so that the thickness of the polyvinyl alcohol-based film is 10 μm or less; And
    상기 연신된 필름 적층체의 고분자 필름과 폴리비닐알코올계 필름을 분리시키는 단계를 포함하는 박형 편광자의 제조 방법. The method of manufacturing a thin polarizer comprising the step of separating the polymer film and the polyvinyl alcohol-based film of the stretched film laminate.
  2. 제1항에 있어서,The method of claim 1,
    상기 필름 적층체는 제1미연신 고분자 필름, 상기 제1미연신 고분자 필름 상에 부착되는 제1미연신 폴리비닐알코올계 필름, 및 상기 제1미연신 폴리비닐알코올계 필름 상에 부착되는 제2미연신 고분자 필름으로 이루어지는 박형 편광자의 제조 방법.The film laminate is a first unstretched polymer film, a first unstretched polyvinyl alcohol-based film adhered on the first unstretched polymer film, and a second unstretched polyvinyl alcohol-based film adhered on the film The manufacturing method of the thin polarizer which consists of an unstretched polymer film.
  3. 제1항에 있어서,The method of claim 1,
    상기 필름 적층체는 제1미연신 고분자 필름, 상기 제1미연신 고분자 필름 상에 부착되는 제1미연신 폴리비닐알코올계 필름, 상기 제1미연신 폴리비닐알코올계 필름 상에 부착되는 제2미연신 고분자 필름, 상기 제2미연신 고분자 필름 상에 부착되는 제2미연신 폴리비닐알코올계 필름 및 상기 제2미연신 폴리비닐알코올계 필름 상에 부착되는 제3미연신 고분자 필름으로 이루어지는 박형 편광자의 제조 방법.The film laminate is a first unstretched polymer film, a first unstretched polyvinyl alcohol film attached to the first unstretched polymer film, and a second unstretched film adhered to the first unstretched polyvinyl alcohol film A thin polarizer comprising a new polymer film, a second unstretched polyvinyl alcohol film adhered on the second unstretched polymer film, and a third unstretched polymer film adhered on the second unstretched polyvinyl alcohol film. Manufacturing method.
  4. 제1항에 있어서,The method of claim 1,
    상기 미연신 고분자 필름은 20℃ 내지 85℃의 온도 범위에서 최대 연신 배율이 5배 이상인 고분자 필름인 박형 편광자의 제조 방법.The unstretched polymer film is a method of producing a thin polarizer is a polymer film having a maximum draw ratio of 5 times or more in the temperature range of 20 ℃ to 85 ℃.
  5. 제1항에 있어서,The method of claim 1,
    상기 미연신 고분자 필름은 고밀도 폴리에틸렌 필름, 폴리우레탄 필름, 폴리프로필렌 필름, 폴리올레핀 필름, 에스테르계 필름, 저밀도 폴리에틸렌 필름, 고밀도 폴리에틸렌 및 저밀도 폴리에틸렌 공압출 필름, 고밀도 폴리에틸렌에 에틸렌 비닐아세테이트가 함유된 공중합체 수지, 아크릴 필름, 폴리에틸렌테레프탈레이트 필름, 폴리비닐알코올계 필름 및 셀룰로오스계 필름으로 이루어진 군으로부터 선택된 1종 이상을 포함하는 것인 박형 편광자의 제조 방법.The unstretched polymer film is a high density polyethylene film, polyurethane film, polypropylene film, polyolefin film, ester film, low density polyethylene film, high density polyethylene and low density polyethylene coextrusion film, copolymer resin containing ethylene vinyl acetate in high density polyethylene And an acrylic film, a polyethylene terephthalate film, a polyvinyl alcohol film and a cellulose film.
  6. 제1항에 있어서,The method of claim 1,
    상기 필름 적층체를 연신하는 단계는 건식 연신 또는 습식 연신으로 수행되는 박형 편광자의 제조 방법.The stretching of the film laminate is a method of manufacturing a thin polarizer is performed by dry stretching or wet stretching.
  7. 제1항에 있어서,The method of claim 1,
    상기 필름 적층체를 연신하는 단계는 20℃ 내지 85℃의 온도에서 5배 내지 15배의 연신 배율로 수행되는 박형 편광자의 제조 방법.The stretching of the film laminate may be performed at a draw ratio of 5 to 15 times at a temperature of 20 ° C to 85 ° C.
  8. 제1항에 있어서,The method of claim 1,
    상기 필름 적층체를 연신하는 단계는 붕산 농도 1중량% 내지 5중량%의 붕산 수용액 내에서 수행되는 박형 편광자의 제조 방법.The stretching of the film laminate is a method of manufacturing a thin polarizer is carried out in an aqueous boric acid solution of boric acid concentration of 1% by weight to 5% by weight.
  9. 제1항에 있어서,The method of claim 1,
    상기 필름 적층체를 연신하는 단계 전에 미연신 폴리비닐알코올계 필름에 요오드 및 이색성 염료 중 적어도 하나를 염착시키는 단계를 더 포함하는 박형 편광자의 제조 방법. And dyeing at least one of iodine and dichroic dye on the unstretched polyvinyl alcohol-based film before the stretching of the film laminate.
  10. 제1항에 있어서,The method of claim 1,
    상기 필름 적층체를 연신하는 단계 이후에 연신된 폴리비닐알코올계 필름과 연신된 고분자 필름 사이의 부착력이 2N/2cm 이하인 박형 편광자의 제조 방법.A method of manufacturing a thin polarizer having an adhesion force of 2 N / 2 cm or less between the stretched polyvinyl alcohol-based film and the stretched polymer film after the stretching of the film laminate.
  11. 제1항에 있어서,The method of claim 1,
    상기 연신된 필름 적층체의 고분자 필름과 폴리비닐알코올계 필름을 분리시키는 단계는 2N/2cm 이하의 박리력을 가하여 수행되는 박형 편광자의 제조 방법. Separating the polymer film and the polyvinyl alcohol-based film of the stretched film laminate is a method of manufacturing a thin polarizer is performed by applying a peel force of 2N / 2cm or less.
  12. 청구항 1 내지 청구항 11 중 어느 한 항의 방법으로 제조되며,Prepared by the method of claim 1,
    두께가 10㎛ 이하이고, 단체 투과도 40 ~ 45%이며, 편광도가 99% 이상인 박형 편광자.A thin polarizer having a thickness of 10 μm or less, a single transmittance of 40 to 45%, and a degree of polarization of 99% or more.
  13. 제12항에 있어서, The method of claim 12,
    상기 박형 편광자는, 편광자 폭 방향을 따라 등 간격으로 위치하는 10개의 점에서 측정된 편광도의 표준편차가 0.002% 이하인 박형 편광자.The said thin polarizer is a thin polarizer whose standard deviation of the polarization degree measured in ten points which are equally spaced along the polarizer width direction is 0.002% or less.
  14. 청구항 12의 박형 편광자를 포함하는 편광판.A polarizing plate comprising the thin polarizer of claim 12.
  15. 청구항 14의 편광판을 포함하는 디스플레이 장치.Display device including the polarizing plate of claim 14.
PCT/KR2014/005231 2013-06-18 2014-06-13 Method for manufacturing thin polarizer, and thin polarizer and polarizing plate manufactured using same WO2014204143A1 (en)

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