KR102164771B1 - Method for manufacturing optical film, optical film and polarizer plate comprising the same - Google Patents

Abstract

The present specification comprises the steps of preparing a film using a resin composition; And in the optical film manufacturing method comprising the step of biaxially stretching the film, wherein the resin composition is (meth) acrylic resin; And a spherical rubber elastic body, wherein the stretching comprises the step of changing the spherical rubber elastic body to an elliptical rubber elastic body having a ratio (L/T) of a long diameter (L) and a short diameter (T) of a cross-sectional area of 3 to 8 It relates to a method of manufacturing an optical film, an optical film formed using the same, and a polarizing plate including the same.

Description

Manufacturing method of an optical film, an optical film, and a polarizing plate including the same TECHNICAL FIELD [METHOD FOR MANUFACTURING OPTICAL FILM, OPTICAL FILM AND POLARIZER PLATE COMPRISING THE SAME}

The present specification relates to a method of manufacturing an optical film, an optical film, and a polarizing plate including the same.

A polarizing plate used in an image display device such as a liquid crystal display device generally has a structure in which a protective film is provided on at least one surface of the polarizer. The protective film serves to protect a polarizer having a very thin thickness, and also serves to protect a polarizer vulnerable to ultraviolet rays.

In general, a triacetyl cellulose film (hereinafter, a TAC film) is mainly used as a protective film for protecting a polarizer. However, the TAC film has a problem in that mechanical strength, heat resistance, and absorption resistance are weak, and when used for a long period of time, the polarization degree or color of the polarizer is changed due to film deformation, and the general polarizing plate characteristics are deteriorated. Therefore, a method of using an acrylic resin film having excellent moisture resistance and heat resistance instead of the TAC film as a material of the polarizer protective film has been proposed.

However, when the acrylic resin film is used alone, the toughness is weak and there is a problem in that it is easily broken or cracked when deformation such as abnormal bending or bending is applied. Therefore, in order to overcome this, a method of improving toughness by introducing an impact modifier such as a rubber elastic body has been proposed, but a lot of rubber elastic bodies must be added to improve toughness, and thus, there is a problem that differential pressure or gelation of the polymer filter occurs. .

Korean Patent Application Publication No. 2010-0130153

The present specification provides a method of manufacturing an optical film, an optical film, and a polarizing plate including the same.

An exemplary embodiment of the present specification

Preparing a film using a resin composition; And

In the optical film manufacturing method comprising the step of biaxially stretching the film,

The resin composition is a (meth)acrylic resin; And a spherical rubber elastomer,

The stretching provides a method for manufacturing an optical film comprising the step of changing the spherical rubber elastic body to an elliptical rubber elastic body having a ratio (L/T) of a long diameter (L) and a short diameter (T) of a cross-sectional area of 3 to 8 .

Another exemplary embodiment of the present specification is

It provides an optical film manufactured by the above method.

Another exemplary embodiment of the present specification is

(Meth)acrylic resin; And

An optical film comprising an elliptical rubber elastomer,

The optical film has a plane direction retardation value of 0 nm to 10 nm, a thickness direction retardation value of -5 nm to 30 nm, and a plane direction retardation and a thickness direction retardation are calculated through the following equations (1) and (2), respectively. Provides an optical film.

Equation (1): R _in = (n _x -n _y ) xd

Equation (2): R_th = [(n_x+n_y)/2-n_z] x d

In the above formulas (1) and (2), R _in is the retardation _in the plane direction, R _th is the retardation in the thickness direction, d is the film thickness, and n _x , n _y and n _z are the refractive index in the x direction, the refractive index in the y direction, and the refractive index in the z direction measured at a wavelength of 550 nm, respectively.

Another exemplary embodiment of the present specification is

Polarizer; And

It provides a polarizing plate including the optical film provided on at least one surface of the polarizer.

Another exemplary embodiment of the present specification is

Display panel; And

It provides an image display device including the polarizing plate attached to one or both sides of the display panel.

According to the exemplary embodiments described herein, the rubber elastic body included in the optical film is changed to an elliptical shape. Accordingly, mechanical properties such as impact energy of the optical film are improved. Therefore, it is possible to solve the problem of breakage or cracking when manufacturing an optical film or when applied to a polarizing plate or an image display device.

1 is a diagram showing a structure of a polarizing plate according to an exemplary embodiment of the present specification.
2 and 3 are diagrams showing SEM measurement results of an optical film according to exemplary embodiments of the present specification.

Hereinafter, the present specification will be described in detail.

In the present specification, when a part "includes" a certain component, it means that other components may be further included rather than excluding other components unless otherwise stated.

An exemplary embodiment of the present specification is a method of manufacturing a film using a resin composition; And

In the optical film manufacturing method comprising the step of biaxially stretching the film,

The resin composition is a (meth)acrylic resin; And a spherical rubber elastomer,

The stretching provides a method for manufacturing an optical film comprising the step of changing the spherical rubber elastic body to an elliptical rubber elastic body having a ratio (L/T) of a long diameter (L) and a short diameter (T) of a cross-sectional area of 3 to 8 .

In the exemplary embodiment of the present specification, the manufacturing of the resin composition into a film form may be performed according to a method well known in the art, such as a solution caster method or an extrusion method. In some cases, during the film manufacturing process, an additive such as an improving agent may be additionally added within a range that does not deteriorate the physical properties of the film.

In an exemplary embodiment of the present specification, the stretching is 1.5 to 4 times in the machine direction (MD) and 1.5 to 4 times in the width direction (TD) at a temperature 5°C to 20°C higher than the glass transition temperature of the resin composition. It proceeds under double conditions.

More specifically, the stretching is performed by biaxial stretching of 1.5 to 2 times in the machine direction (MD) and 2.5 to 3 times in the width direction (TD). If the stretching ratio is less than 1.5 times in the width direction, the toughness of the film is lowered, making it difficult to apply to the polarizing plate. If it exceeds 4 times in the width direction, it is impossible to produce a stable film due to the fracture of the film during the stretching process. have.

In the present specification, "Machine Direction (MD)" refers to a longitudinal direction corresponding to the progression direction during continuous production of a film, and "Transverse Direction (TD)" refers to a vertical direction in the MD direction.

In the exemplary embodiment of the present specification, the stretching may be performed in one of the machine direction (MD) and the width direction (TD) first and then in the other direction, or both directions may be simultaneously stretched. Further, the stretching may be performed in one step or may be performed in multiple steps.

In the exemplary embodiment of the present specification, the stretching is performed at a temperature of (Tg+5)°C to (Tg+20)°C when the glass transition temperature of the resin composition for manufacturing the optical film is Tg. Specifically, the stretching may be performed at 105 ℃ to 150 ℃.

In the exemplary embodiment of the present specification, Tg of the optical film may be 100°C to 130°C. More specifically, it may be 110 ℃ to 120 ℃.

In the exemplary embodiment of the present specification, the glass transition temperature of the resin composition may be measured by a differential scanning calorimeter (DSC).

In the exemplary embodiment of the present specification, in order to change the spherical rubber elastic body into an elliptical rubber elastic body, when stretching is performed at a low temperature, stretching must be performed at a low magnification in MD and TD. On the other hand, when stretching is performed at a high temperature, stretching must be performed at a high magnification in MD and TD.

Specifically, in the exemplary embodiment of the present specification, when the stretching is performed at a temperature of 5° C. or more and less than 15° C. than the glass transition temperature of the resin composition, the stretching ratio is 2.4 to 2.7 times in TD and 1.5 times in MD. The rubber elastic body can be changed to an elliptical shape only when it is performed 4 times.

In addition, in the exemplary embodiment of the present specification, when the stretching is performed at a temperature of 15° C. or higher than the glass transition temperature of the resin composition, the stretching ratio is more than 2.7 times 4 times in TD and 1.5 times to 4 times in MD. Only when the rubber elastic body can be changed to an elliptical shape.

For example, if the film is stretched 1.8 times by MD and 2.56 times by TD, if stretching is performed at a temperature 10°C higher than the glass transition temperature of the film, the spherical elastic body is transformed into an elliptical elastic body, but at a temperature 20°C higher than the glass transition temperature. If stretching is performed, the elastic body does not deform into an elliptical shape.

As another example, when the film is stretched at a temperature 20°C higher than the glass transition temperature of the film, if stretching is performed 1.8 times by MD and 2.9 times by TD, the spherical elastic body is transformed into an elliptical elastic body, but 1.8 times by MD. If the stretching is performed by 2.56 times TD, the spherical elastic body does not deform into an ellipse.

In the present specification, the "oval shape" means that the ratio (L/T) of the long diameter (L) and the short diameter (T) in the cross-sectional area of the object is 3 or more and 8 or less.

In the present specification, the "spherical" means that the ratio (L/T) of the long diameter (L) and the short diameter (T) of an object is less than 3.

In the present specification, the "longest diameter (L)" means the length of the longest part in the cross-sectional area of the object.

In the present specification, the "shorter diameter (T)" refers to the length of the vertical portion of the major diameter.

In one embodiment of the present specification, the spherical rubber elastic body may have surface irregularities formed.

In the present specification, the "cross-sectional area of an object" means a cross-sectional area in a portion representing the maximum diameter of the object.

In the exemplary embodiment of the present specification, the stretching is performed in a range of a stretching speed of 10%/min to 20,000%/min, preferably 100%/min to 10,000%/min in one direction. When the drawing speed is less than 10%/min, it takes a long time to obtain a sufficient draw ratio, and there is a fear that the manufacturing cost may increase. When the stretching speed exceeds 20,000%/min, there is a fear that the stretched film may break.

In the exemplary embodiment of the present specification, the stretching may be used without limitation, as long as it is a device capable of stretching a film including a known stretching device such as a roll stretching machine or a tender-type stretching machine.

In the exemplary embodiment of the present specification, the (meth)acrylic resin includes a (meth)acrylic monomer as a main component, and is not particularly limited as long as it is a material known in the art, for example, an alkylmethacrylate monomer or an alkyl It may be a copolymer containing a methacrylate-based monomer. In this case, the alkyl methacrylate-based monomer includes not only alkyl methacrylate but also derivatives of alkyl methacrylate.

Specifically, the (meth)acrylic resin is an alkyl methacrylate-based monomer; Homopolymers of alkyl methacrylate-based monomers; Or a copolymer formed by polymerizing at least one of an aromatic vinyl-based monomer, an acrylonitrile-based monomer, a styrene-based monomer, a phenylmaleimide-based monomer, and an acid anhydride with an alkyl methacrylate-based monomer. More specifically, the (meth)acrylic resin includes a homopolymer of an alkyl methacrylate-based monomer.

In the present specification, "monomer" means a repeating structure included in a polymer. That is, "monomer" may mean a structure included in the form of a bivalent or more in a polymer by a polymerization reaction.

In the present specification, "derivative" refers to a similar compound obtained by chemically changing a part of a compound, and means a compound in which a hydrogen atom or a specific group of atoms in the compound is substituted by another atom or group of atoms.

In the present specification, “copolymer” means that an element referred to as a monomer is polymerized and included as a repeating unit in the copolymer resin. The copolymer may be a block copolymer or a random copolymer, but is not limited thereto. In addition, even when referring to the monomers included in the copolymer in the present specification, it is not limited to including only the mentioned monomers, and within the scope not departing from the object of the present invention, other monomers other than the above-mentioned monomers are used as comonomers. It can be additionally included.

In an exemplary embodiment of the present specification, the alkyl moiety of the alkyl methacrylate-based monomer may be a substituted or unsubstituted alkyl group or a cycloalkyl group, and in this case, the number of carbon atoms of the alkyl moiety is preferably about 1 to 10, and , More preferably 1 to 6, and most preferably a methyl group or an ethyl group. Specifically, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, hydroxyethyl methacrylate, isobornyl methacrylate and cyclohexyl methacrylate It may be at least one selected from the group consisting of, but is not limited thereto.

In the exemplary embodiment of the present specification, the styrene-based monomer may be an unsubstituted styrene monomer or a substituted styrene monomer. The substituted styrene monomer may be styrene substituted with a substituent including an aliphatic hydrocarbon or hetero atom in a benzene ring or vinyl group. For example, styrene, α-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 2-methyl-4-chlorostyrene, 2,4,6- Trimethylstyrene, cis-β-methylstyrene, trans-β-methylstyrene, 4-methyl-α-methylstyrene, 4-fluoro-α-methylstyrene, 4-chloro-α-methylstyrene, 4-bromo-α -Methylstyrene, 4-t-butylstyrene, 2-fluorostyrene, 3-fluorostyrene, 4-fluorostyrene, 2,4-difluorostyrene, 2,3,4,5,6-pentafluorostyrene , 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene, 2,4-dichlorostyrene, 2,6-dichlorostyrene, octachlorostyrene, 2-bromostyrene, 3-bromostyrene, 4-bromo It may be one or more selected from the group consisting of styrene, 2,4-dibromostyrene, α-bromostyrene, and β-bromostyrene, but is not limited thereto.

In the exemplary embodiment of the present specification, the phenylmaleimide-based monomer is, for example, phenylmaleimide, nitrophenyl maleimide, monochlorophenyl maleimide, dichlorophenyl maleimide, monomethylphenyl maleimide, dimethylphenyl maleimide, and ethylmethylphenyl It may be one or more selected from the group consisting of maleimide, but is not limited thereto.

In an exemplary embodiment of the present specification, the (meth)acrylic resin may be polymethylmethacrylate.

In the exemplary embodiment of the present specification, the rubber elastomer is methacrylonitrile-butadiene-styrene (MBS)-based elastomer, acrylonitrile-butadiene-styrene (ABS)-based elastomer, acrylonitrile-ethylene-propylene-diene- Styrene (AES) elastomer, acrylonitrile-styrene-butylacrylate (ASA) elastomer, ethylene-propylene-diene terpolymer (EPDM) elastomer, styrene-butadiene-styrene (SBS) elastomer, styrene-isoprene -Styrene (SIS) elastomer, styrene-butadiene (SB) elastomer, styrene-isoprene rubber elastomer, ethylene-vinyl acetate (EVA) elastomer, ethylene-ethyl acrylate (EEA) elastomer, ethylene-vinyl alcohol ( EVOH) copolymer elastomer, ethylene chloride (CPE) resin elastomer, silicone rubber elastomer, acrylic-silicone rubber elastomer, polybutylene terephthalate (PBT) elastomer, polyethylene terephthalate (PET) elastomer and nylon elastomer. It may be any one selected from the group.

In the exemplary embodiment of the present specification, the resin composition includes 5wt% to 15wt% of the rubber elastomer based on the total weight of the resin composition.

In the exemplary embodiment of the present specification, the resin composition is an additive commonly used in the technical field to which the present invention belongs, such as a photoinitiator, surfactant, antioxidant, UV absorber, leveling agent, antifouling agent, ultraviolet absorber, in addition to the above-described components. It may further include. In addition, when the composition for an optical film contains the above additives, the content can be variously adjusted within a range that does not deteriorate the physical properties of the composition for forming an optical film, for example, 100 weight of (meth)acrylic resin It may be included in 0.1 parts by weight to 10 parts by weight based on parts.

In the exemplary embodiment of the present specification, the UV absorber may be, for example, a triazine-based or triazole-based UV absorber, but is not limited thereto.

An exemplary embodiment of the present specification provides an optical film manufactured by the method for manufacturing an optical film described above.

An exemplary embodiment of the present specification is a (meth)acrylic resin; And

An optical film comprising an elliptical rubber elastomer,

The optical film has a plane direction retardation value of 0 nm to 10 nm, a thickness direction retardation value of -5 nm to 30 nm, and a plane direction retardation and a thickness direction retardation are calculated through the following equations (1) and (2), respectively. Provides an optical film.

Equation (1): R _in = (n _x -n _y ) xd

Equation (2): R _th = [(n _x +n _y )/2-n _z ] xd

In the above formulas (1) and (2), R _in is the retardation _in the plane direction, R _th is the retardation in the thickness direction, d is the film thickness, and n _x , n _y and n _z are the refractive index in the x direction, the refractive index in the y direction, and the refractive index in the z direction measured at a wavelength of 550 nm, respectively.

Specifically, n _x is the refractive index in the direction in which the surface direction refractive index is the maximum (ie, the slow axis direction) when measured in light having a wavelength of 550 nm, and n _y is the refractive index in the surface direction when measured in light having a wavelength of 550 nm. In this case, it is the refractive index in the direction perpendicular to the slow axis (ie, the fast axis direction), and n _z means the refractive index in the thickness direction.

In the exemplary embodiment of the present specification, the n _x , n _y and n _z can be measured by a known method well known in the art, for example, a prism coupler equipment (SAIRON TECHNOLOGY company SPA-3DR) The average refractive index is measured using the same, and the birefringence is measured with Axomatrics' Axoscan, so that n _x , n _y and n _z can be calculated, respectively.

In the exemplary embodiment of the present specification, the "thickness" means an average width between one surface of a member and one surface opposite to the surface.

In the exemplary embodiment of the present specification, the elliptical rubber elastic body included in the optical film is 1.5 to 4 times in the machine direction (MD) at a temperature of 5°C to 20°C higher than the glass transition temperature of the spherical rubber elastic body in the width direction. It was transformed into an elliptical shape by stretching under the conditions of 1.5 to 4 times (TD).

At this time, the stretching conditions are the same as described above in the method of manufacturing the optical film.

In one embodiment of the present specification, the elliptical rubber elastic body included in the optical film has a ratio (L/T) of a long diameter (L) and a short diameter (T) of 3 or more and 8 or less.

In the exemplary embodiment of the present specification, the optical film includes 5wt% to 15wt% of a rubber elastic body based on the total weight of the optical film.

In the exemplary embodiment of the present specification, the optical film further includes a UV absorber. The UV absorber at this time is the same as described above in the manufacturing method.

In the exemplary embodiment of the present specification, the optical film has a UV transmittance value of 20% or less at a wavelength of 380 nm. Accordingly, it may serve to protect a polarizer vulnerable to ultraviolet rays.

In the exemplary embodiment of the present specification, the impact energy value of the optical film is 600 kN·m/m ³ or more. When the impact energy is low, fracture may occur during film manufacturing, and crack may occur when cutting a polarizing plate. Therefore, the higher the impact energy is, the more preferable, and the upper limit thereof is not particularly limited, but may be, for example, 2,000 kN·m/m ³ or less.

The impact energy can be obtained through a drop impact experiment. Specifically, the impact energy can be obtained by dividing potential energy by the volume of the film. At this time, the potential energy was (gravity acceleration x falling ball weight x falling ball height), and the film volume was calculated as (film thickness x measurement area). That is, the impact energy can be calculated through (gravity acceleration x falling ball weight x falling ball height)/(film thickness x measurement area).

In the exemplary embodiment of the present specification, the weight of the falling ball is 10g to 100g.

In the exemplary embodiment of the present specification, the height of the falling ball is 50mm to 1,500mm.

In an exemplary embodiment of the present specification, the film thickness is 20 μm to 100 μm.

In one embodiment of the present specification, the measurement area is 2,500mm ² to 10,000mm ² (film diameter: 50mm to 100mm).

In one embodiment of the present specification, the optical film has a thickness of 20 μm to 100 μm, preferably 40 μm to 80 μm. According to the present specification, since the optical film has the same thickness as described above, it is possible to be thinner than a film including a separate coating layer, and an optical film of high hardness can be provided without occurrence of curls or cracks. Specifically, when the thickness of the optical film is less than 20 μm, there is a problem that the film is poorly handled and thus bends and breaks may occur during the manufacturing process and product handling. When it exceeds 80 μm, the polarizing plate is thinned. There is an impossible problem.

In the exemplary embodiment of the present specification, the optical film may have a light transmittance of 80% or more in a wavelength range of 400 nm to 800 nm. In addition, the haze of the optical film may be 2% or less. If the straight transmittance and turbidity of the optical film are less than 80% and 2% or more, respectively, there is a problem in that the luminance of the liquid crystal display device manufactured therefrom decreases.

In one embodiment of the present specification, the optical film is a polarizer protective film.

An exemplary embodiment of the present specification is a polarizer; And it provides a polarizing plate including the optical film according to the above-described embodiments provided on at least one surface of the polarizer.

At this time, the optical film may be attached to both sides of the polarizer, or may be attached only to one side. When the optical film is attached to only one surface of the polarizer, a protective film known in the art may be provided on the other surface as necessary.

The optical film according to an exemplary embodiment of the present specification may be directly attached to one or both sides of a polarizer, or attached on a protective film of a polarizing plate to which a protective film is attached to both sides of the polarizer, and thus may be usefully used as a protective film or a retardation film. have.

When the optical film is directly attached to one or both sides of a polarizer, for example, the structure is an upper protective film/polarizer/optical film, an optical film/polarizer/lower protective film, an optical film/upper protective film/polarizer/lower It may be a protective film or an upper protective film/polarizer/lower protective film/optical film.

1 shows a polarizing plate according to an exemplary embodiment of the present specification. Specifically, it is a diagram illustrating a case where an optical film is attached to both sides of a polarizer.

In one embodiment of the present specification, as the polarizer, those known in the art may be used without limitation, and for example, a film made of polyvinyl alcohol (hereinafter'PVA') containing iodine or a dichroic dye may be used. I can. The polarizer may be prepared by dyeing iodine or a dichroic dye on a PVA film, but the method of manufacturing the polarizer is not particularly limited. In the present specification, a polarizer means a state that does not include an optical film, and a polarizing plate means a state including a polarizer and an optical film.

The attachment of the polarizer and the optical diffusing film may be performed through a method of laminating films well known in the art. For example, after coating an adhesive on the surface of an optical film or polarizer using a roll coater, gravure coater, bar coater, knife coater, or capillary coater, the optical film and polarizer are heat-laminated with a paper roll, or laminated by room temperature compression. It can be carried out by a method.

As the adhesive, any material used in the art may be used without limitation, and for example, a water-based adhesive, a thermosetting adhesive, or an ultraviolet curable adhesive may be used. Specifically, polyvinyl alcohol-based adhesives, polyurethane-based adhesives, and acrylic adhesives may be used without limitation.

In an exemplary embodiment of the present specification, the total thickness of the polarizing plate may be 45 μm or more, for example, 45 μm to 250 μm, or 50 μm to 120 μm, or 50 μm to 100 μm. According to the present specification, by applying the above-described optical film to the polarizing plate, it is possible to achieve a high hardness without generating curls or cracks while having a thin thickness.

In the exemplary embodiment of the present specification, the polarizing plate may be a polarizing plate for TN (Twisted Nematic) or STN (Super Twisted Nematic) liquid crystal, and may be In-Plane Switching (IPS), Super-IPS, or FFS (Fringe Field Switching). ) May be a polarizing plate for horizontal alignment mode, or a polarizing plate for vertical alignment mode.

An exemplary embodiment of the present specification is a display panel; And it provides an image display device including the above-described polarizing plate attached to one or both sides of the display panel.

In the exemplary embodiment of the present specification, the display panel may be a liquid crystal panel or an organic light emitting panel, and accordingly, the image display device may be a liquid crystal display device (LCD) or an electroluminescent device (LED).

Specifically, the image display device may be a liquid crystal display device including a liquid crystal panel and polarizing plates respectively provided on both sides of the liquid crystal panel, wherein at least one of the polarizing plates is a polarizing plate according to an exemplary embodiment of the present specification described above. Can be More specifically, the liquid crystal display may include a liquid crystal cell and an upper polarizing plate and a lower polarizing plate provided on both sides of the liquid crystal cell, respectively, and the optical film may include an outer side of an upper polarizing plate without the liquid crystal cell and/ Alternatively, it may be provided as a retardation film or a protective film outside the lower polarizing plate on which the liquid crystal cell is not provided. That is, one or two or more optical films may be provided on the outside of the upper polarizing plate without the liquid crystal cell, the outside of the lower polarizing plate without the liquid crystal cell, and/or on the outside without the liquid crystal cell in both the upper and lower polarizing plates. I can.

More specifically, the optical film is a protective film and may be located at the outermost part of the liquid crystal display device. In this case, in particular, it is possible to solve the problem of occurrence of fracture or crack.

In the exemplary embodiment of the present specification, the type of the liquid crystal panel included in the liquid crystal display device is not particularly limited, and all known panels may be applied. In addition, other components constituting the liquid crystal display device, for example, the types of upper and lower substrates (for example, color filter substrates or array substrates) are not particularly limited, and configurations known in the art are not limited. Can be employed.

Hereinafter, the present specification will be described in more detail through examples. However, the following examples are for illustrating the present specification, and the scope of the present specification is not limited thereby.

Example 1.

A fabric sheet was prepared by extruding a polymethyl methacrylate resin containing 10 wt% of a spherical rubber elastomer (L/T: less than 3) based on the total weight of the composition. Thereafter, an optical film was prepared by stretching 1.8 times in the MD direction at 125°C, which is 10°C higher than the glass transition temperature, and stretching 2.56 times in the TD direction at the same temperature.

Example 2.

A fabric sheet was prepared by extruding a polymethyl methacrylate resin containing 10 wt% of a spherical rubber elastomer (L/T: less than 3) based on the total weight of the composition. Thereafter, an optical film was prepared by stretching 1.8 times in the MD direction at 130°C, which is 15°C higher than the glass transition temperature, and then stretching 2.9 times in the TD direction at the same temperature.

Example 3.

A fabric sheet was prepared by extruding a polymethyl methacrylate resin containing 5 wt% of a spherical rubber elastomer (L/T: less than 3) based on the total weight of the composition. Thereafter, an optical film was prepared by stretching 1.8 times in the MD direction at 125°C, which is 10°C higher than the glass transition temperature, and stretching 2.56 times in the TD direction at the same temperature.

Example 4.

A fabric sheet was prepared by extruding a polymethyl methacrylate resin containing 15 wt% of a spherical rubber elastomer (L/T: less than 3) based on the total weight of the composition. Thereafter, an optical film was prepared by stretching 1.8 times in the MD direction at 135°C, 20°C higher than the glass transition temperature of 115°C, and then stretching 2.9 times in the TD direction at the same temperature.

Example 5

A fabric sheet by adding 0.55 phr of a UV modifier (LA-F70, ADEKA) to a polymethyl methacrylate resin containing 10 wt% of a spherical rubber elastomer (L/T: less than 3) relative to the total weight of the composition and extruding Was produced. Thereafter, the glass transition temperature was stretched 1.8 times in the MD direction at 125°C, 10°C higher than the glass transition temperature, and then 2.56 times stretched in the TD direction at the same temperature to prepare an optical film of about 60 μm.

Comparative Example 1.

A fabric sheet was prepared by extruding a polymethyl methacrylate resin containing 10 wt% of a spherical rubber elastomer (L/T: less than 3) based on the total weight of the composition. Thereafter, an optical film was prepared by stretching 1.8 times in the MD direction at 135°C, 20°C higher than the glass transition temperature of 115°C, and stretching 2.56 times in the TD direction at the same temperature.

Comparative Example 2.

A fabric sheet was prepared by extruding a polymethyl methacrylate resin containing 10 wt% of a spherical rubber elastomer (L/T: less than 3) based on the total weight of the composition. Thereafter, an optical film was prepared by stretching 1.8 times in the MD direction at 130°C, which is 15°C higher than the glass transition temperature, and stretching 2.56 times in the TD direction at the same temperature.

Comparative Example 3.

A fabric sheet was prepared by extruding a polymethyl methacrylate resin containing 5 wt% of a spherical rubber elastomer (L/T: less than 3) based on the total weight of the composition. Thereafter, an optical film was prepared by stretching 1.8 times in the MD direction at 135°C, 20°C higher than the glass transition temperature of 115°C, and stretching 2.56 times in the TD direction at the same temperature.

Comparative Example 4.

A fabric sheet was prepared by extruding a polymethyl methacrylate resin containing 15 wt% of a spherical rubber elastomer (L/T: less than 3) based on the total weight of the composition. Thereafter, an optical film was prepared by stretching 1.8 times in the MD direction at 135°C, 20°C higher than the glass transition temperature of 115°C, and stretching 2.56 times in the TD direction at the same temperature.

Comparative Example 5 .

A raw sheet was prepared by extruding a polymethyl methacrylate resin containing no rubber elastic body. Thereafter, an optical film was prepared by stretching 1.8 times in the MD direction at 130°C, which is 15°C higher than the glass transition temperature, and stretching 2.56 times in the TD direction at the same temperature.

Comparative Example 6.

A raw sheet was prepared by extruding a polymethyl methacrylate resin containing no rubber elastic body. Thereafter, an optical film was prepared by stretching 1.8 times in the MD direction at 130°C, which is 15°C higher than the glass transition temperature, and then stretching 2.9 times in the TD direction at the same temperature.

Experimental Example 1. Measurement of impact energy

The optical films prepared in Examples 1 to 4 and Comparative Examples 1 to 6 were prepared as samples of 10 cm x 10 cm, and the samples were fixed between metal plates with a circular hole of 58 cm ² and then 36 g metal balls The impact energy was measured by dividing the potential energy at the maximum height at which the film was not destroyed by free falling at a certain height by the volume of the film and calculated as energy per unit volume.

Experimental Example 2. Measurement of transmittance

HITACHI's U-3310 Spectrophotometer was used with a scan speed of 600 nm/min to measure the wavelength from 200 to 850 nm, and then the transmittance in the UV region of 380 nm and the visible region of 550 nm.

The evaluation results of the properties of the optical films prepared in Examples 1 to 5 are shown in Table 1 below, and the evaluation results of the optical films prepared in Comparative Examples 1 to 6 are shown in Table 2 below.

Example
One Example
2 Example
3 Example
4 Example
5 Resin composition Polymethyl methacrylate
(wt%) 90 90 95 85 90 Rubber elastomer
(wt%) 10 10 5 15 10 UV absorber
(phr) - - - - 0.55 Glass transition temperature (℃) 115 115 115 115 115 Stretching conditions MD draw ratio (times) 1.8 1.8 1.8 1.8 1.8 TD draw ratio (times) 2.56 2.9 2.56 2.9 2.56 Stretching temperature (℃) Tg+10 Tg+15 Tg+10 Tg+20 Tg+10 R _in /R _th (nm) 2/23 3/26 2/18 3/29 2/23 Film properties Impact energy
(kN m/m ³ ) 1050 1015 714 988 1050 Of rubber elastomer
L/T 4.9 4.5 4.3 4.1 4.9 Transmittance at 380nm
(%) 93 93 93 93 4 Transmittance at 550nm
(%) 93 93 93 93 93

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative example
5 Comparative example
6 Resin composition
(wt%) Polymethyl methacrylate 90 90 95 85 100 100 Rubber elastomer 10 10 5 15 - - Glass transition temperature (℃) 115 115 115 115 115 115 Stretching conditions MD draw ratio (times) 1.8 1.8 1.8 1.8 1.8 1.8 TD draw ratio (times) 2.56 2.56 2.56 2.56 2.56 2.9 Stretching temperature (℃) Tg
+20 Tg
+15 Tg
+20 Tg
+20 Tg
+15 Tg
+15 R _e /R _th (nm) 2/17 2/19 2/13 2/22 2/11 3/14 Film properties Impact energy
(kN m/m ³ ) 591 832 384 776 402 483 Of rubber elastomer
L/T One 1.2 One One - - Transmittance at 380nm
(%) 93 93 93 93 93 93 Transmittance at 550nm
(%) 93 93 93 93 93 93

From the L/T of the rubber elastomers described in Tables 1 and 2, it can be seen that in Examples 1 to 5, the rubber elastomers were changed to an elliptical shape due to appropriate stretching conditions. On the other hand, since the rubber elastomers prepared in Comparative Examples 1 to 6 had an L/T of less than 3, it can be confirmed that the rubber elastomers did not exhibit an elliptical shape as the stretching conditions were different.

In addition, in the case of the optical films prepared in Examples 1 to 5 in which the rubber elastomer was changed to an elliptical shape, the impact energy was 600 kN m/m ³ or more, whereas in Comparative Examples 5 and 6 in which the rubber elastomer was not added , In the case of the manufactured optical film, it can be seen that the impact energy is less than 600 kN·m/m ³ . In addition, in the case of Comparative Examples 1 to 4 in which the rubber elastic body is not deformed into an elliptical shape, it can be seen that the impact energy is reduced compared to the Example.

On the other hand, in the case of Example 5 to which the UV absorber was added, it can be seen that the transmittance at 380 nm is 4%.

2 shows the SEM measurement results of the optical film prepared in Example 2. 3 shows SEM measurement results of the optical film prepared in Comparative Example 2. 2 and 3, it can be seen that the rubber elastic body included in the optical film prepared in Example 2 was changed to an elliptical shape, whereas the rubber elastic body included in the optical film prepared in Comparative Example 2 maintained a spherical shape. have.

10: optical film
20: polarizer

Claims (11)

Preparing a film using a resin composition; And
In the polarizer protective film manufacturing method comprising the step of biaxially stretching the film,
The resin composition is a (meth)acrylic resin; And a spherical rubber elastomer,
The stretching is performed at a temperature of 5° C. or more and less than 15° C. than the glass transition temperature of the resin composition, 2.4 to 2.7 times TD, 1.5 to 4 times MD, or 15° C. than the glass transition temperature of the resin composition At the above temperature, TD is more than 2.7 times and less than 4 times and MD is performed at a stretching ratio of 1.5 to 4 times, and the ratio (L/T) of the long diameter (L) and the short diameter (T) of the cross-sectional area to the spherical rubber elastic body is 3 Including the step of changing to an elliptical rubber elastomer having more than 8 or less,
The method of manufacturing a polarizer protective film wherein the polarizer protective film includes an elliptical rubber elastic body. delete The method according to claim 1,
The resin composition is a method of manufacturing a polarizer protective film containing 5wt% to 15wt% of a rubber elastic body based on the total weight of the resin composition. A polarizer protective film manufactured by the manufacturing method of claim 1. delete delete delete delete delete delete delete

Images