KR20190129564A - Retardation film, method for manufacturing retardation film, polarizing plate comprising same, and liquid crystal display device comprising the same - Google Patents

Abstract

The present application provides a retardation film, including: an acrylate-based resin; a phase transition regulator having a glass transition temperature (Tg) of 130 °C or higher; and a composition comprising a positive retardation material or a cured product thereof. The temperature of thermal shrinkage (TTS) of the retardation film is 110 °C or more and 130 °C or less, and the phase transition regulator having the Tg of 130 °C or more includes 12 parts by weight or more and 25 parts by weight or less based on 100 parts by weight of the acrylate-based resin. Provided are the retardation film, a manufacturing method of the retardation film, a polarizing plate including the same, and a liquid crystal display device.

Description

Retardation film, manufacturing method of retardation film, polarizing plate including the same and liquid crystal display device including the same TECHNICAL FIELD

The present invention relates to a retardation film, a method of manufacturing the retardation film, a polarizing plate including the same, and a liquid crystal display device including the same.

In recent years, the development of optical technology has been used to replace conventional CRTs, such as plasma display panels (PDPs), liquid crystal displays (LCDs), and organic light emitting diodes (OLEDs). Display devices using the scheme have been proposed and marketed. Recently, the characteristics required for such display apparatuses are becoming more advanced, and accordingly, the required characteristics for peripheral components such as optical films applied to the display apparatuses are also becoming more advanced. In particular, in recent years, display devices are becoming thinner, lighter, and larger in screen area, and wide viewing angles, high contrast, suppression of image color change according to viewing angle, and uniform display are particularly important problems.

The retardation film is an optical film used in a display device for the purpose of improving the viewing angle, display quality, and the like, and may be classified into one having a constant wavelength dispersion, a flat wavelength dispersion, and a reverse wavelength dispersion depending on the wavelength dispersion characteristics. A retardation film having a constant wavelength dispersion means a retardation film having a property of decreasing retardation value generated as the wavelength of incident light increases, and a retardation film having a flat wavelength dispersion has a similar degree regardless of the wavelength of incident light. It means a retardation film having a characteristic that generates a retardation value, the retardation film having a reverse wavelength dispersion means a retardation film having a characteristic that also increases as the wavelength of the incident light increases.

In particular, among polarizing plates used in LCDs, there are polarizing plates requiring an optical laminate having high heat resistance and low level of phase difference. In order to manufacture an optical laminate having high heat resistance and a low level of phase difference, a liquid crystal coating was applied. For this purpose, an alignment layer coating is additionally required on the optical laminate, and due to the high price of the liquid crystal, it is not competitive. have. On the other hand, the use of acrylic rather than liquid crystal can satisfy the retardation at a low price, but when using an acryl-based retardation film having a low glass transition temperature has a disadvantage that the heat resistance of the retardation film is not good.

Therefore, there is a need for research on a cost competitive and excellent retardation film for producing an optical laminate having high heat resistance and low level retardation.

Korean public publication 2005-0101743

The present invention relates to a retardation film, a polarizing plate including the same, a manufacturing method of the polarizing plate, and a liquid crystal display including the same.

An exemplary embodiment of the present application, the acrylate resin; Phase transition regulator having a glass transition temperature (Tg) of 130 ° C. or higher; And a retardation film comprising a composition comprising a positive retardation material or a cured product thereof, wherein a temperature of thermal shrinkage (TTS) of the retardation film is 110 ° C. or more and 130 ° C. or less, and the glass transition temperature (Tg, Glass transition temperature) 130 ° C or more retardation modifier to provide a retardation film that is included in more than 12 parts by weight to 25 parts by weight based on 100 parts by weight of the acrylate resin.

Another exemplary embodiment, the acrylate resin; Phase transition regulator having a glass transition temperature (Tg) of 130 ° C. or higher; And forming a composition comprising a positive retardation material; Stretching the composition; And drying the composition, wherein after the stretching of the retardation film, a temperature of thermal shrinkage (TTS) is 110 ° C. or more and 130 ° C. or less, and the glass transition temperature (Tg). , glass transition temperature) 130 ° C or more retardation control agent provides a method for producing a retardation film that is included in more than 12 parts by weight to 25 parts by weight based on 100 parts by weight of the acrylate resin.

Another embodiment, the polarizer; And it provides a polarizing plate comprising at least one retardation film according to an embodiment of the present application.

Finally, a liquid crystal cell; An upper polarizer provided in an upper layer of the liquid crystal cell; A lower polarizer provided in the lower layer of the liquid crystal cell; And a backlight unit provided under the lower polarizer, wherein at least one of the upper polarizer and the lower polarizer is a polarizer; And a phase difference film according to an exemplary embodiment of the present application disposed on one surface of the polarizer.

Retardation film according to the present invention is an acrylate resin; Phase transition regulator having a glass transition temperature (Tg) of 130 ° C. or higher; And a positive retardation material in a specific condition to provide a retardation film having excellent heat resistance.

In addition, the retardation film according to the present invention after the stretching, the temperature of the thermal shrinkage (TTS, TTS, satisfies a value of 110 ° C or more and 130 ° C or less to have a characteristic of excellent heat resistance at high temperature.

In addition, the retardation film according to the present invention is a phase difference regulator having a glass transition temperature (Tg, 130g or more) which is a negative retardation material; And a positive retardation material at the same time to have a low retardation, and is suitable for use in LCDs, and has excellent heat resistance.

1 is a view showing a laminated structure of a polarizing plate according to an exemplary embodiment of the present application.
2 is a view showing a laminated structure of a polarizing plate according to an exemplary embodiment of the present application.
3 is a view showing a liquid crystal display device according to an exemplary embodiment of the present application.

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. Moreover, embodiment of this invention is provided in order to demonstrate this invention in detail to the person skilled in the art.

An exemplary embodiment of the present application, the acrylate resin; Phase transition regulator having a glass transition temperature (Tg) of 130 ° C. or higher; And a temperature of thermal shrinkage (TTS) of 110 ° C. or more and 130 ° C. or less after stretching of the retardation film with a retardation film comprising a composition comprising a positive retardation material or a cured product thereof. Tg, glass transition temperature) 130 ° C or more retardation modifier to provide a retardation film that is included in more than 12 parts by weight to 25 parts by weight based on 100 parts by weight of the acrylate resin.

Retardation film according to the present invention is an acrylate resin; Phase transition regulator having a glass transition temperature (Tg) of 130 ° C. or higher; And a positive phase difference material, and in particular, the content portion may include a phase difference regulator having a glass transition temperature (Tg, glass transition temperature) of 130 ° C. or higher, thereby manufacturing a phase difference film having excellent heat resistance at high temperature.

In the present specification, the glass transition temperature was measured using METTLER DSC (Differential Scanning Calorymeter) equipment, and the measuring method is 3 mg to 20 mg of the resin to be measured in an aluminum crucible and 30 ° C. to 250 ° C. of 10 ° C. per minute. The resin is melted at a temperature rising rate, cooled to 30 ° C. again, and then melted at a temperature rising rate of 10 ° C. per minute up to 200 ° C. again. At this time, through the METTLER DSC equipment, the middle point of the temperature range in which the resin changes the specific heat behavior during the second melting process is measured, this value is measured as the glass transition temperature value.

In the present application, the shrinkage onset temperature refers to a temperature at which the retardation film produced by the stretching process starts to shrink rapidly as the stretch is released, and the shrinkage onset temperature using a thermomechanical analyzer (TMA) is used. Can be measured. On the graph measured by the thermal / mechanical characteristic analyzer, the temperature at which the film shows the shrinkage behavior after the expansion behavior is referred to as the shrinkage start temperature.

The method of measuring the shrinkage onset temperature is measured using a TA TMA (Q400) equipment after preparing a sample of an optical film with a dimension of 80 × 4.5 mm. Specifically, when temperature is applied under conditions of a temperature increase rate of 10 ° C./min and a load of 0.02 N, the temperature of the inflection point at which the sample begins to contract after expansion in the MD and TD directions, respectively (on the graph, the tangential slope is 0) Shrinkage start temperature.

In an exemplary embodiment of the present application, the shrinkage start temperature of the retardation film may be 110 ° C. or more and 130 ° C. or less.

When the retardation film which concerns on this application has the said shrinkage start temperature, the retardation film will have the characteristic which was excellent in heat resistance later at high temperature. In particular, when the shrinkage initiation temperature is lower than the above range, relaxation of the polymer oriented by stretching in a high temperature environment may occur, and thus deformation may occur in the retardation value.

In one embodiment of the present application, the acrylate resin may include a (meth) acrylate resin having a weight average molecular weight of 100,000 g / mol to 5 million g / mol.

The said weight average molecular weight is one of the average molecular weights whose molecular weight is not uniform and the molecular weight of a certain polymeric material is used as a reference, and is a value obtained by averaging the molecular weight of the component molecular species of the polymeric compound with molecular weight distribution in a weight fraction.

The weight average molecular weight can be measured through Gel Permeation Chromatography (GPC) analysis.

In the present specification, (meth) acrylate is meant to include both acrylates and methacrylates. The (meth) acrylate resin may be, for example, a copolymer of a (meth) acrylic acid ester monomer and a crosslinkable functional group-containing monomer.

Although the said (meth) acrylic acid ester monomer is not specifically limited, For example, alkyl (meth) acrylate is mentioned, More specifically, it is a monomer which has a C1-C12 alkyl group, A pentyl (meth) acrylate, n-butyl (meth) acrylate, ethyl (meth) acrylate, methyl (meth) acrylate, hexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethyl It may include one or more types of hexyl (meth) acrylate, dodecyl (meth) acrylate and decyl (meth) acrylate.

The crosslinkable functional group-containing monomer is not particularly limited, but may include, for example, one or more types of hydroxy group-containing monomers, carboxyl group-containing monomers and nitrogen-containing monomers.

Examples of the hydroxyl group-containing compound include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth ) Acrylate, 8-hydroxyoctyl (meth) acrylate, 2-hydroxyethylene glycol (meth) acrylate, 2-hydroxypropylene glycol (meth) acrylate, etc. are mentioned.

Examples of the carboxyl group-containing compound include (meth) acrylic acid, 2- (meth) acryloyloxyacetic acid, 3- (meth) acryloyloxypropyl acid, 4- (meth) acryloyloxybutyl acid, acrylic acid double Sieve, itaconic acid, maleic acid, or maleic anhydride.

Examples of the nitrogen-containing monomers include (meth) acrylonitrile, N-vinyl pyrrolidone, N-vinyl caprolactam, and the like.

At least one of vinyl acetate, styrene and acrylonitrile may be further copolymerized with the (meth) acrylate resin in view of other functionalities such as compatibility.

In one embodiment of the present application, the acrylate-based resin may be polymethyl methacrylate (PMMA, Poly methylmethacrylate).

When using polymethyl methacrylate (PMMA, Poly methylmethacrylate) as the acrylate resin, when using a polymethyl methacrylate including a ring structure, it is possible to form a product of low cost and high economical You will have the advantage.

In an exemplary embodiment of the present application, the phase difference regulator having a glass transition temperature of 130 ° C. or more provides a phase difference film that is a styrene-maleic anhydride (SMA) copolymer.

The said copolymer is called a copolymer obtained by superposing | polymerizing 2 or more types of other monomers, and, as for a copolymer, 2 or more types of units may be arrange | positioned irregularly or regularly.

The copolymer may be a random copolymer having random forms of monomers mixed with each other, a block copolymer in which blocks arranged in a predetermined section are repeated, or alternating forms in which monomers are alternately repeated and polymerized. There may be a copolymer (Alternating Copolymer), the phase difference regulator having a glass transition temperature of 130 ℃ or more according to an embodiment of the present application may be an irregular copolymer, a block copolymer or an alternating copolymer.

When only the acrylate resin is present in the retardation film composition, the glass transition temperature of the retardation film composition is low, but by using together the retardation regulator having a glass transition temperature of 130 ° C. or higher, the glass transition temperature of the retardation film composition is increased, so that the heat resistance is particularly excellent. Will have characteristics.

In the case of the retardation film composition of the present application, polymethyl methacrylate (PMMA, Polymethylmethacrylate) having a low glass transition temperature is used as the acrylate resin, and thus, Styrene-maleic anhydride (SMA) having a low glass transition temperature is used. The glass transition temperature of styrene-maleic anhydride (SMA) used at this time is 130 ° C or higher to increase the glass transition temperature of the retardation film composition as a whole. have.

In an exemplary embodiment of the present application, the phase difference regulator having a glass transition temperature (Tg) of 130 ° C. or more may be included in an amount of 12 parts by weight or more and 25 parts by weight or less based on 100 parts by weight of the acrylate resin.

In another exemplary embodiment, the phase difference regulator having a glass transition temperature (Tg) of 130 ° C. or more is 12 parts by weight or more and 23 parts by weight or less, preferably 12 parts by weight or more, based on 100 parts by weight of the acrylate resin. It may be included in 20 parts by weight or less.

When the phase difference regulator having a glass transition temperature (Tg) of 130 ° C. or higher according to the present application has the above range, the glass transition temperature of the composition can be realized high, thereby having excellent heat resistance at high temperature. In addition, the present invention has a feature capable of expressing a phase difference in a suitable range.

In one embodiment of the present application, the glass transition temperature of the glass transition temperature (Tg, glass transition temperature) 130 ℃ or more may be 130 ℃ or more, preferably 133 ℃ or more.

In another exemplary embodiment, the glass transition temperature of the phase difference regulator having a glass transition temperature (Tg) of 130 ° C. or more may be 150 ° C. or less, preferably 140 ° C. or less.

In an exemplary embodiment of the present application, the positive retardation material is provided, based on 100 parts by weight of the acrylate-based resin, 5 parts by weight to 15 parts by weight is provided.

In another exemplary embodiment, the positive phase difference material may be included in an amount of 6 parts by weight to 14 parts by weight, preferably 6 parts by weight or more and 12 parts by weight or less, based on 100 parts by weight of the acrylate resin.

When the positive retardation material according to the present application is included in the content range, the retardation film has a feature that can reduce the retardation expression by the retardation regulator.

In one embodiment of the present application, the retardation film provides a retardation film that satisfies the following formula 1 and formula 2.

[Equation 1]

0nm ≤ R _in (550) ≤ 3nm

[Equation 2]

0nm ≤ R _th (550) ≤ 20nm

In Formula 1 and Formula 2,

R _in (550) is the plane retardation at a wavelength of 550 nm, is a value of (n _x -n _y ) xd,

R _th (550) is a thickness retardation at a wavelength of 550 nm, and is a value of {n _z- (n _x + n _y ) / 2} xd,

N _x is a refractive index in a slow axis direction of the retardation film surface,

N _y is a refractive index in the fast axis direction of the retardation film surface,

N _z is a refractive index in the retardation film thickness direction,

D is the thickness of the retardation film.

In Equations 1 and 2, R _in (550) was a surface direction retardation measured at a wavelength of 550 nm, and the measurement was measured using Axoscan, Axometrics. In addition, R _th (550) is a thickness direction retardation at a wavelength of 550 nm, and is a value of {n _z- (n _x + n _y ) / 2} xd, and the refractive index in the thickness direction is measured by AxoScan equipment, It is a value determined by the value and thickness of the difference with the average of refractive index.

That is, in Equations 1 and 2, R _in (550) is a plane direction retardation value at a wavelength of 550 nm, and R _th (550) means a thickness direction retardation value at a wavelength of 550 nm.

The plane direction retardation at each wavelength is determined by the difference between the refractive index in the slow axis direction and the refractive index in the fast axis direction and the thickness of the retardation film as described in Equations 1 and 2 above. to be. The slow axis and fast axis are determined by the orientation direction of the polymer chain of the retardation film. The direction in which the polymer chain is oriented is called the slow axis. The slow axis takes the longest time for light to pass through and has the greatest retardation delay. Fast axis is the opposite concept. The fast axis is the direction in which the polymer chain is oriented in a small direction. It is called the fast axis.

In one embodiment of the present application, the positive retardation material may be a polymer having a melting index (MI) of 120 or more.

In another exemplary embodiment, the positive phase difference material may be a polymer having a melting index (MI) of 120 or more and 180 or less, preferably 150 or less.

The melt index refers to the melt flowability of the material at a constant load and at a constant temperature, and the high melt index means excellent injection moldability, and the larger the melt flow index, the easier the flow.

The measurement of the melt index, after heating a specific material for a certain time and cut the resin coming out of the lower end of the MI meter at intervals of 30 seconds to measure the weight accordingly, the weight value converted into 10 minutes is the melt index value.

Since the positive phase difference material has the melt index value, the positive retardation material has excellent compatibility with the acrylate-based resin and has a property of suppressing haze generation.

In one embodiment of the present application, the positive retardation material may be polycarbonate (PC, Poly Carbonate), excellent compatibility with the acrylate-based resin, can lower the phase difference, and lower the glass transition temperature If the material is not limited thereto.

By using the polycarbonate as the positive phase difference material, when used with a phase difference regulator having a glass transition temperature (Tg) of 130 ° C. or more, which is a negative phase difference material, the phase difference can be lowered without changing the glass transition temperature. Has the characteristics.

In the present specification, a negative retardation material refers to a material that expresses an optical axis (refractive index in the direction in which the surface refractive index is maximum: n _x ) in a direction perpendicular to the stretching direction after stretching (after orientation), and a positive retardation material refers to stretching It means a substance which expresses an optical axis in the direction parallel to a extending | stretching direction after (after orientation).

In one embodiment of the present application, the thickness of the retardation film is 10 ㎛ or more and 100 ㎛ It may be:

In another exemplary embodiment, the thickness of the retardation film is 10 μm or more and 100 μm Or less, Preferably it is 15 micrometers or more and 95 micrometers Or less, More preferably, it is 15 micrometers or more and 80 micrometers It may be:

As can be seen in Equation 1 and Equation 2, the retardation value is changed according to the thickness of the retardation film, in the present application, when the thickness of the retardation film has the above range has a feature that can adjust the retardation of the desired degree.

In one embodiment of the present application, the glass transition temperature of the composition of the retardation film may be 120 ℃ or more.

The glass transition temperature of the composition is 120 ℃ or more means, acrylate resin; A phase difference regulator having a glass transition temperature of 130 ° C. or higher; And it means a glass transition temperature for a composition comprising a positive retardation material, the measuring method is the same as described above.

In one embodiment of the present application, the glass transition temperature of the composition of the retardation film may be 125 ℃ or more, preferably 125 ℃ or more.

In one embodiment of the present application, the glass transition temperature of the composition of the retardation film may be 150 ° C or less, preferably 130 ° C or less.

In the case of the retardation film according to the present application, the glass transition temperature value of the composition, including a phase difference regulator having a glass transition temperature of 130 ° C or more, can maintain the above range, according to the retardation film has a very excellent heat resistance characteristics .

On the other hand, the manufacturing method of the retardation film of the present invention having the characteristics as described above is not particularly limited, it may be prepared by a method of forming the film after forming the composition, and stretching it.

The composition is prepared by, for example, extruding and kneading the mixture obtained after preblending the film raw material with any suitable mixer such as an omni mixer. In this case, the mixer used for extrusion kneading is not specifically limited, For example, any suitable mixer, such as an extruder, such as a single screw extruder and a twin screw extruder, and a pressurized kneader, can be used.

As a method of the said film shaping | molding, arbitrary suitable film shaping | molding methods, such as the solution casting method (solution casting method), the melt-extrusion method, the calender method, the compression molding method, are mentioned, for example. Among these film forming methods, a solution cast method (solution casting method) and a melt extrusion method are preferable.

As a solvent used for the said solution casting method (solution casting method), For example, aromatic hydrocarbons, such as benzene, toluene, xylene; Aliphatic hydrocarbons such as cyclohexane and decalin; Esters such as ethyl acetate and butyl acetate; Ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; Alcohols such as methanol, ethanol, isopropanol, butanol, isobutanol, methyl cellosolve, ethyl cellosolve and butyl cellosolve; Ethers such as tetrahydrofuran and dioxane; Halogenated hydrocarbons such as dichloromethane, chloroform and carbon tetrachloride; Dimethylformamide; Or dimethyl sulfoxide. These solvents may be used independently or may use 2 or more types together.

As an apparatus for performing the said solution casting method (solution casting method), a drum type casting machine, a band type casting machine, a spin coater, etc. are mentioned, for example. In addition, as said melt-extrusion method, the T-die method, the inflation method, etc. are mentioned, for example. Molding temperature may be 150 ~ 350 ℃, or 200 ~ 300 ℃.

When forming a film by the said T die method, a T die can be attached to the front-end | tip of a well-known single screw extruder or a twin screw extruder, the film extruded in film shape can be rolled, and a roll-shaped film can be obtained.

After the film is formed through the above process, the film is stretched. The stretching step may be performed in the longitudinal direction (MD) stretching or in the transverse direction (TD) stretching, or both. In addition, in the case where both longitudinal stretching and transverse stretching are performed, either stretching may be performed first and then stretching in the other direction, or both directions may be simultaneously stretched. In addition, the stretching may be performed in one step, or may be carried out in multiple steps. In the case of longitudinal stretching, stretching by the speed difference between the rolls can be performed, and in the case of transverse stretching, a tenter can be used. The starting angle of the tenter is usually within 10 degrees, which suppresses the bowing phenomenon occurring during the lateral stretching and regularly controls the angle of the optical axis. Even when the transverse stretching is carried out in multiple stages, the anti-boeing effect can be obtained.

In addition, in an exemplary embodiment of the present application, the stretching ratio in the stretching of the film may be 1.05 to 10 times based on the length in the stretching direction.

In addition, the total draw ratio may be stretched to be 1.1 times or more, or 1.2 times or more, or 1.5 times or more, 25 times or less, or 10 times or less, or 7 times or less based on the total stretching area of the base film. When the draw ratio is less than 1.1 times, the effect of stretching may not be sufficiently achieved, and when the draw ratio is greater than 25 times, the film layer may be cracked.

Before the stretching, a process of flattening the coated surface of the composition and drying to volatilize the solvent included in the composition may be performed.

An exemplary embodiment of the present application, the acrylate resin; Phase transition regulator having a glass transition temperature (Tg) of 130 ° C. or higher; And forming a composition comprising a positive retardation material; Stretching the composition; And drying the composition, wherein after the stretching of the retardation film, a temperature of thermal shrinkage (TTS) is 110 ° C. or more and 130 ° C. or less, and the glass transition temperature (Tg). , glass transition temperature) 130 ° C or more retardation control agent provides a method for producing a retardation film that is included in more than 12 parts by weight to 25 parts by weight based on 100 parts by weight of the acrylate resin.

In one embodiment of the present application, the stretching temperature (A) in the stretching step of the composition provides a method for producing a polarizing plate that satisfies the following formula 3 with respect to the glass transition temperature (B) of the composition. .

[Equation 3]

B + 11 ℃ ≤A≤B + 40 ℃

The content of the stretching process is the same as mentioned above.

In the stretching step according to the present application, when the stretching temperature satisfies Equation 3 with respect to the glass transition temperature of the retardation film composition, the temperature of thermal shrinkage (TTS) is higher than 110 ℃ 130 ℃ It satisfies the value and has excellent heat resistance at high temperature.

The stretched retardation film is stretched at a specific temperature or more, the shrinkage occurs, and with this in mind, the shrinkage behavior can be confirmed using TMA, or it can be confirmed that the stretched film by shrinking it to a high temperature in an oven (Oven). have. For example, when it is kept at the temperature of 150 ° C. for 5 minutes, shrinkage similar to the dimension before stretching occurs, and the stretching ratio can also be known.

In one embodiment of the present application, the phase difference regulator having a glass transition temperature of 130 ℃ or more provides a method for producing a phase difference film is a styrene-maleic anhydride (SMA) copolymer.

In an exemplary embodiment of the present application, the positive retardation material, based on 100 parts by weight of the acrylate-based resin, provides a method for producing a retardation film is contained in 5 parts by weight or more and 15 parts by weight or less.

In one embodiment of the present application, the acrylate-based resin provides a method for producing a retardation film that is polymethyl methacrylate (PMMA, polymethyl methacrylate).

The retardation film may be subjected to heat treatment (annealing) or the like after the stretching treatment in order to stabilize its optical isotropy and mechanical properties. The heat treatment conditions are not particularly limited and may employ any suitable conditions known to those skilled in the art.

The retardation film of the present invention as described above can be usefully applied to a polarizing plate and / or a liquid crystal display device. In one embodiment of the present invention, the present invention is a polarizer; And it provides a polarizing plate comprising at least one retardation film of the present application.

In one embodiment of the present application, the polarizer; And it provides a polarizing plate comprising at least one phase difference film.

1 is a diagram illustrating a laminated structure of a polarizing plate 103 according to an exemplary embodiment of the present application. Specifically, the polarizing plate 103 has a structure in which the polarizer 102 and the retardation film 101 are laminated on one surface of the polarizer.

In one embodiment of the present application, the polarizer is not particularly limited, and a film made of polyvinyl alcohol (PVA) containing a polarizer well known in the art, for example, iodine or a dichroic dye, is used.

The polarizer exhibits a property of extracting only light vibrating in one direction from incident light while vibrating in various directions. This property can be achieved by stretching polyvinyl alcohol (PVA) absorbing iodine with strong tension. For example, more specifically, swelling soaking the PVA film in an aqueous solution, swelling, dyeing with a dichroic material imparting polarization to the swelled PVA film, stretching the dyed PVA film The polarizer may be formed through a stretching step of arranging the dichroic dye materials side by side in the stretching direction, and a complementary color step of correcting the color of the PVA film subjected to the stretching step. However, the polarizing plate of the present invention is not limited thereto.

In one embodiment of the present application, the polarizer and the retardation film may be adhered with an adhesive, and any usable adhesive is not particularly limited as long as it is known in the art. For example, there are water-based adhesives, one-component or two-component polyvinyl alcohol (PVA) adhesives, polyurethane adhesives, epoxy adhesives, styrene butadiene rubber (SBR) adhesives, or hot melt adhesives. It is not limited only to these examples.

The retardation film may be directly attached to one side or both sides of the polarizer. In addition, it is attached to the protective film of the conventional polarizing plate with a protective film on both sides of the polarizer, it can be usefully used as a retardation film.

When the retardation film is directly attached to one side or both sides of the polarizer, for example, the structure may be an upper protective film / polarizer / retardation film or a retardation film / polarizer / low protective film. The attaching method is a roll coater, a gravure coater, a bar coater, a knife coater, a capillary coater, or a micro chamber doctor blade coater and the like to coat the primer on the surface of the retardation film or polarizer, and then , By spraying an adhesive in a dropwise manner, and heating the laminated body including the retardation film and the polarizer with a lamination roll, laminating by pressing at room temperature, or UV curing.

2 is a view showing a laminated structure of a polarizing plate according to an exemplary embodiment of the present application. Specifically, the polarizing plate 103 may have a structure in which the polarizer protective film 104 / the polarizer 102 / the retardation film 101 are sequentially stacked.

In an exemplary embodiment of the present application, a polarizer protective film is attached to one surface of the polarizer, and the polarizing plate according to the present application is attached to a surface opposite to the surface on which the polarizer protective film of the polarizer is attached. do.

In one embodiment of the present application, the polarizer protective film is a COP (cycloolefin polymer) film, acrylic film, TAC (triacetylcellulose) film, COC (cycloolefin copolymer) film, PNB (polynorbornene) film and PET (polyethylene) terephtalate) film may be made of any one or more.

In an exemplary embodiment of the present application, a liquid crystal display device including the polarizing plate is provided.

In addition, it provides a liquid crystal display device comprising at least one retardation film according to an embodiment of the present application.

In one embodiment of the present application, the liquid crystal cell; An upper polarizer provided in an upper layer of the liquid crystal cell; A lower polarizer provided in the lower layer of the liquid crystal cell; And a backlight unit provided under the lower polarizer, wherein at least one of the upper polarizer and the lower polarizer is a polarizer; And a phase difference film according to the present application disposed on one surface of the polarizer.

In one embodiment of the present application, the upper polarizing plate is the polarizer; And the retardation film, wherein the retardation film is disposed to face the liquid crystal cell.

The upper polarizer is the polarizer; And the retardation film, wherein the retardation film is disposed to face the liquid crystal cell, wherein the upper polarizer is the polarizer; And the retardation film, wherein the retardation film is disposed in the liquid crystal cell direction in the liquid crystal display, and specifically, a backlight unit, a lower polarizing plate, a liquid crystal cell, a retardation film, and a polarizer are sequentially stacked. It means having a structure.

The lower polarizer is the polarizer; And the retardation film, wherein the retardation film is disposed to face the backlight unit, wherein the lower polarizer is the polarizer; And the retardation film, wherein the retardation film is disposed in the direction of the backlight unit in the liquid crystal display, and specifically, the backlight unit / polarizer / retardation film / liquid crystal cell / upper polarizing plate is sequentially stacked. It means having a structure.

In the liquid crystal display device according to the present application, when the retardation film of the upper polarizing plate is disposed to face the liquid crystal cell, or when the retardation film of the lower polarizing plate is disposed to face the backlight unit, optical improvement such as an increase in luminous performance Physical properties have particularly excellent characteristics.

The backlight unit includes a light source for irradiating light from the back of the liquid crystal panel, and the type of the light source is not particularly limited, and a general LCD light source such as CCFL, HCFL or LED may be used.

3 is a view showing a liquid crystal display device according to an exemplary embodiment of the present application. Specifically, the upper polarizing plate 11 and the lower polarizing plate 12 may be stacked on both sides of the liquid crystal cell 10, and the surface in contact with the liquid crystal cell 10 of the lower polarizing plate 12 adjacent to the backlight unit 14. The protective film 13 may be laminated on the opposite surface. As the upper polarizing plate 11 and the lower polarizing plate 12, a polarizing plate according to an exemplary embodiment of the present application may be used.

The protective film is the same as the content of the polarizer protective film described above.

Hereinafter, the operation and effect of the invention will be described in more detail with reference to specific examples of the invention. However, these embodiments are only presented as an example of the invention, whereby the scope of the invention is not determined.

< Example >

Preparation of the composition

The components and weight ratios of the compositions used in the Examples and Comparative Examples herein are shown in Table 1 below.

Acrylate resin
(content) Retarder
(content) Positive phase difference material
(content) Glass transition temperature of the composition Example 1 PMMA (100 parts by weight) SMA
(14.1 parts by weight) Polycarbonate
(3.2 parts by weight) 120 ℃ Example 2 PMMA (100 parts by weight) SMA
(14.1 parts by weight) Polycarbonate
(3.2 parts by weight) 120 ℃ Example 3 PMMA (100 parts by weight) SMA
(16.7 parts by weight) Polycarbonate
(3.0 parts by weight) 121 ℃ Example 4 PMMA (100 parts by weight) SMA
(13.1 parts by weight) Polycarbonate
(6.0 parts by weight) 120 ℃ Comparative Example 1 PMMA (100 parts by weight) - - 116 ℃ Comparative Example 2 PMMA (100 parts by weight) SMA
(6.6 parts by weight) Polycarbonate
(3.0 parts by weight) 118 ℃ Comparative Example 3 PMMA (100 parts by weight) SMA
(6.6 parts by weight) Polycarbonate
(3.0 parts by weight) 118 ℃ Comparative Example 4 PMMA (100 parts by weight) SMA
(6.6 parts by weight) Polycarbonate
(3.0 parts by weight) 118 ℃ Comparative Example 5 PMMA (100 parts by weight) - Polycarbonate
(3.1 parts by weight) 116 ℃

About the composition which has the composition and weight ratio of the said Table 1, it extended | stretched according to the conditions of the following Table 2, and produced the retardation film.

Drawing temperature Elongation Ratio (MD / TD) Example 1 Tg + 13 ℃ 1.8 x 2.05 Example 2 Tg + 13 ℃ 1.7 x 1.91 Example 3 Tg + 14 ℃ 1.5 x 1.68 Example 4 Tg + 15 ℃ 1.7 X 1.97 Comparative Example 1 Tg + 15 ℃ 1.8 x 2.5 Comparative Example 2 Tg + 13 ℃ 1.8 x 2.3 Comparative Example 3 Tg + 10 ℃ 1.7 x 1.93 Comparative Example 4 Tg + 7 ℃ 1.7 x 1.93 Comparative Example 5 Tg + 15 ℃ 1.8 X 2.5

Table 3 shows the results of measuring film properties and heat resistance of the retardation films of Examples 1 to 4 and Comparative Examples 1 to 5.

Film properties Heat resistance @ 90 ℃ for 500h Heat resistance @ 105 ℃ for 500h R _in / R _th TTS (MD / TD) Rin / Rth Rin / Rth Example 1 0.5 / 10.5 110/113 0.4 / 11.5 0.5 / 12.0 Example 2 0.5 / 10.4 111/114 0.4 / 11.3 0.4 / 11.7 Example 3 0.8 / 10.9 115/117 0.8 / 11.7 0.8 / 12.0 Example 4 0.7 / 2.5 113/115 0.6 / 2.8 0.7 / 3.0 Comparative Example 1 0.8 / 12.0 100/105 3.2 / 18.3 3.1 / 18.7 Comparative Example 2 0.6 / 10.2 103/104 2.7 / 15.8 2.9 / 16.4 Comparative Example 3 0.5 / 11.3 102/102 2.9 / 16.7 2.7 / 17.1 Comparative Example 4 0.4 / 12.5 100/101 3.2 / 18.1 3.3 / 18.5 Comparative Example 5 0.6 / 2.1 102/103 2.7 / 5.1 2.4 / 6.2

In the case of Table 3, the composition of Table 1 is a table evaluating the heat resistance of the retardation film produced according to the stretching conditions of Table 2. The heat resistance at 90 ° C and 105 ° C was evaluated, and the evaluation criteria evaluated the level at which the initial phase difference value changed after 500 hours at each temperature.

When the TTS was high, the change occurred below 2nm on the Rth basis after 500 hours at each temperature, while the change was very large when the TTS was low. In the case of retardation film, optical design is made as an initial value reference, so there is no exact standard, but the smaller the retardation change at the initial value, the higher the heat resistance.

In Examples 1 to 4 of Table 3, the glass transition temperature is high, and the drawing temperature is also excellent at heat resistance by drawing at a relatively high temperature, whereas in Comparative Example 1, the initial phase difference value is satisfied, but the glass transition is low. It can be confirmed that the heat resistance is not good due to the high stretching temperature due to the temperature, in the case of Comparative Example 2 is drawn at a relatively high stretching temperature with a high glass transition temperature by the use of SMA and PC, but higher than the stretching temperature The draw ratio shows low TTS and poor heat resistance. In addition, in the case of Comparative Examples 3 to 4 it can be seen that low TTS and poor heat resistance due to the low stretching temperature despite the high glass transition temperature. Finally, in the case of Comparative Example 5, it was confirmed that the low TTS and poor heat resistance despite the high stretching temperature due to the low glass transition temperature due to the non-use of SMA as the phase difference regulator.

101: retardation film
102: polarizer
103: polarizer
104: polarizer protective film
10: liquid crystal cell
11: upper polarizer
12: lower polarizer
13: protective film
14: backlight unit

Claims (18)

Acrylate resins;
Phase transition regulator having a glass transition temperature (Tg) of 130 ° C. or higher; And
A retardation film comprising a composition comprising a positive retardation material or a cured product thereof,
The shrinkage onset temperature (TTS) of the retardation film is 110 ° C or more and 130 ° C or less,
The retardation film having a glass transition temperature (Tg, 130 ° C or more) of the retardation film is included 12 parts by weight or more and 25 parts by weight or less based on 100 parts by weight of the acrylate resin. The method according to claim 1,
The retardation film, the retardation film satisfies the following formula 1 and formula 2:
[Equation 1]
0nm ≤ R _in (550) ≤ 3nm
[Equation 2]
0nm ≤ R _th (550) ≤ 20nm
In Formula 1 and Formula 2,
R _in (550) is the plane retardation at a wavelength of 550 nm, and is a value of (n _x -n _y ) xd,
R _th (550) is a thickness retardation at a wavelength of 550 nm, and is a value of {n _z- (n _x + n _y ) / 2} xd,
N _x is a refractive index in a slow axis direction of the retardation film surface,
N _y is a refractive index in the fast axis direction of the retardation film surface,
N _z is a refractive index in the retardation film thickness direction,
D is the thickness of the retardation film. The method according to claim 1,
Retardation film of the glass transition temperature 130 ℃ or more is a styrene-maleic anhydride (SMA) copolymer is a retardation film. The method according to claim 1,
The positive phase difference material, based on 100 parts by weight of the acrylate resin,
Retardation film is contained in 5 parts by weight or more and 15 parts by weight or less. The method according to claim 1,
The acrylate-based resin is polymethyl methacrylate (PMMA, polymethyl methacrylate) retardation film. The method according to claim 1,
The thickness of the retardation film is 10 µm or more and 100 µm Retardation film which is the following. The method according to claim 1,
The glass transition temperature of the composition is at least 120 ℃ retardation film. Acrylate resins; Phase transition regulator having a glass transition temperature (Tg) of 130 ° C. or higher; And forming a composition comprising a positive retardation material;
Stretching the composition; And
In the method for producing a retardation film comprising the step of drying the composition,
After the stretching of the retardation film, the temperature of thermal shrinkage (TTS) is 110 ° C or more and 130 ° C or less,
The glass transition temperature (Tg, glass transition temperature) 130 ° C or more retardation control agent manufacturing method of the retardation film is included 12 parts by weight to 25 parts by weight based on 100 parts by weight of the acrylate resin. The method according to claim 8,
The stretching temperature (A) in the step of stretching the composition is a method for producing a polarizing plate that satisfies the following formula 3 with respect to the glass transition temperature (B) of the composition:
[Equation 3]
B + 11 ° C. ≦ A ≦ B + 40 ° C. The method according to claim 8,
The phase difference control agent having a glass transition temperature of 130 ° C. or more is a styrene-maleic anhydride (SMA) copolymer. The method according to claim 8,
The positive phase difference material is based on 100 parts by weight of the acrylate resin,
The manufacturing method of retardation film contained in 5 weight part or more and 15 weight part or less. The method according to claim 8,
The acrylate-based resin is polymethyl methacrylate (PMMA, polymethyl methacrylate) is a method for producing a retardation film. The method according to claim 8,
Glass transition temperature of the composition is a method of producing a retardation film is 120 ℃ or more. Polarizer; And
The polarizing plate containing at least one retardation film of any one of Claims 1-7. The method according to claim 14,
A polarizer protective film is attached to one surface of the polarizer,
The retardation film is attached to the surface opposite to the surface attached to the polarizer protective film of the polarizer. Liquid crystal cell;
An upper polarizer provided in an upper layer of the liquid crystal cell;
A lower polarizer provided in the lower layer of the liquid crystal cell; And
It includes a backlight unit provided on the lower layer of the lower polarizing plate,
At least one of the upper polarizer and the lower polarizer is a polarizer; And a phase difference film of any one of claims 1 to 7 disposed on one surface of the polarizer. The method according to claim 16,
The upper polarizer is the polarizer; And the retardation film,
And the retardation film is disposed to face the liquid crystal cell. The method according to claim 16,
The lower polarizer is the polarizer; And the retardation film,
And the retardation film is disposed to face the backlight unit.

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