KR101732226B1 - Preparing method for the optical film, optical mamber and optical film by the same method, polarizing plate and liquid crystal display comprising the same - Google Patents

Abstract

The present invention relates to a method for producing a birefringent film, comprising: uniaxially stretching an unstretched birefringent film in a transverse direction (TD); Attaching the stretched birefringent film to a shrinkable film to form a laminate; And heat-shrinking the laminate in the transverse direction (TD) such that the stretched birefringent film satisfies the following formula (1), an optical member and an optical film produced using the same, And a polarizing plate and a liquid crystal display including the same.
Equation (1): n _x > n _z > n _y
Ny is a refractive index in a direction perpendicular to the nx direction of the birefringent film, nz is a thickness of the birefringent film in the direction perpendicular to the nx direction, nz is a thickness of the birefringent film, Direction.

Description

TECHNICAL FIELD [0001] The present invention relates to a method of manufacturing an optical film, an optical member and an optical film manufactured using the same, a polarizing plate and a liquid crystal display including the polarizing plate and the liquid crystal display, THE SAME}

The present invention relates to a method for producing an optical film, an optical member and an optical film manufactured using the optical film, a polarizing plate and a liquid crystal display including the optical member, and more particularly to an IPS mode liquid crystal display An optical member and an optical film manufactured using the same, a polarizing plate including the same, and a liquid crystal display device.

The liquid crystal display device is spreading as an optical display device because its power consumption is lower than that of a cathode ray tube display, its volume is small, its weight is light and it is easy to carry. In general, a liquid crystal display device has a basic structure in which a polarizing plate is provided on both sides of a liquid crystal cell, and the orientation of the liquid crystal cell changes depending on whether an electric field is applied to the driving circuit, and the characteristics of light transmitted through the polarizing plate are changed, Is visualized. At this time, the path of light and the birefringence change depending on the incident angle of the incident light because the liquid crystal is an anisotropic material having two different refractive indices.

Due to such characteristics, the liquid crystal display device has a problem that the contrast ratio, which is a measure for how much the image is seen clearly according to the viewing angle, is changed and the gray scale inversion phenomenon occurs, It has disadvantages. In order to overcome such disadvantages, an optical compensation film for developing an optical retardation generated in a liquid crystal cell is used for a liquid crystal display device.

As such a retardation film, for example, an optical film having a refractive index distribution of n _x > n _z > n _y is used. At this time, the optical film having the refractive index distribution as described above is difficult to be realized as a single film, and conventionally, a structure composed of two or more layers of multilayer films has been presented. However, in the case of a multilayer film, it is difficult to make the film thinner, and if the optical axis of two or more laminated films is not precisely aligned, the desired retardation characteristics are not exhibited.

Therefore, studies for producing an optical film having the refractive index distribution as described above are progressing continuously. For example, a shrinkable film is attached to one side or both sides of a resin film via an acrylic adhesive, A method of stretching the laminate at a high temperature and imparting a contracting force in a direction perpendicular to the stretching direction has been proposed.

At this time, a film which is generally in a non-drawn state is used as the resin film. However, when the thin film is extruded in order to thin the retardation film to be produced, it is very difficult to produce the retardation film having a sufficiently wide width. Therefore, when the retardation film is attached to a shrinkable film to shrink it, Is too narrow to produce a very low productivity and the possibility of mass production is low.

The present invention is an optical member to be produced by that for solving the above problems, a new n _x> n _z> n _y the method of producing a single optical film having a refractive index profile having a thin thickness and a large width, and using this and An optical film, a polarizing plate including the same, and a liquid crystal display device.

On the other hand, the object of the present invention is not limited to the above description. It will be understood by those of ordinary skill in the art that there is no difficulty in understanding the additional problems of the present invention.

In one aspect, the present invention provides a method of producing a birefringent film, comprising: uniaxially stretching an unstretched birefringent film in the transverse direction (TD); Attaching the stretched birefringent film to a shrinkable film to form a laminate; And heat-shrinking the laminate in the width direction (TD) such that the stretched birefringent film satisfies the following formula (1).

Equation (1): n _x > n _z > n _y

Ny is a refractive index in a direction perpendicular to the nx direction of the birefringent film, nz is a thickness of the birefringent film in the direction perpendicular to the nx direction, nz is a thickness of the birefringent film, Direction.

At this time, it is preferable that the stretching is performed so that the width of the birefringent film after stretching becomes 1400 mm to 6000 mm.

The stretching step may be performed such that the thickness of the birefringent film after stretching is 5 占 퐉 to 40 占 퐉.

Further, it is preferable that the stretching step is performed so that the birefringent film after stretching satisfies the following formula (2).

(2): 0 nm? R _{in (a)} ? 100 nm

In the above formula (2), R _{in (a)} is the retardation value of the birefringent film measured at a wavelength of 550 nm.

It is preferable that the stretching step is performed so that the birefringent film after stretching satisfies the following formula (3).

Formula (3): -100 nm? R _{th (a)} ? 100 nm

In the above formula (3), R _{th (a)} is the thickness direction retardation value of the birefringent film measured at a wavelength of 550 nm.

Further, the stretching step is preferably performed at a temperature of (Tg) to (Tg + 50 deg. C), where Tg is the glass transition temperature of the birefringent film.

It is preferable that the stretching step is performed at a stretching magnification of 1.5 to 6.0 times.

On the other hand, in the step of forming the laminate, the shrinkable film may be attached to one side or both sides of the stretched birefringent film.

Alternatively, the step of forming the laminate may include attaching a stretched birefringent film to both sides of the shrinkable film.

On the other hand, it is preferable that the step of forming the laminate is performed by a method of attaching a birefringent film obtained by stretching through an active energy ray-curable resin layer to a shrinkable film.

On the other hand, it is preferable that the step of heat shrinking the laminate is performed so as to satisfy the following formula (4).

(4): 0%? S ₂ - S ₁ ? 5%

In the formula (4), S ₁ is a shrinkage ratio in the direction perpendicular to the stretching direction of the birefringent film in the laminated state, and S ₂ is a shrinkage ratio in the direction perpendicular to the stretching direction of the shrinkable film in the laminated state .

It is preferable that the step of heat shrinking the laminate is performed so as to satisfy the following formulas (5) and (6).

(5): 0.10 N / 2 cm? P _a ? 1.0 N / 2 cm

Equation (6): 0.01 N / 2 cm? P _b ? 0.5 N / 2 cm

In the formulas (5) and (6), P _a is the adhesive strength between the birefringent film and the shrinkable film before heat shrinkage, and P _b is the adhesive strength between the birefringent film and the shrinkable film after heat shrinkage.

On the other hand, it is preferable that the step of heat shrinking the laminate is performed by a method of uniaxially stretching the laminate in the longitudinal direction (MD).

At this time, it is preferable that the stretching is performed at a temperature of (Tg ') to (Tg' + 100 ° C) when the glass transition temperature of the shrinkable film is Tg '.

The stretching is preferably performed at a draw ratio of 1.1 to 3.0 times.

In another aspect, the present invention provides an optical member comprising a birefringent film uniaxially stretched in the transverse direction (TD) and a shrinkable film, wherein the birefringent film satisfies the following formula (1).

Equation (1): n _x > n _z > n _y

Ny is a refractive index in a direction perpendicular to the nx direction of the birefringent film, nz is a thickness of the birefringent film in the direction perpendicular to the nx direction, nz is a thickness of the birefringent film, Direction.

Further, the present invention provides an optical film which is produced by the above production method and satisfies the following formulas (7) to (9).

(7): 150 nm? R _{in (b)} ? 350 nm

(8): 50 nm? R _{th (b)} ? 250 nm

Equation (9): 0.1? Nz _(b) ? 1

In the above formulas (7) to (9), R _{in (b)} is a retardation value of the optical film measured at a wavelength of 550 nm, R _{th (b)} and, Nz _(b) being the ratio (R _th / R _in) of the thickness retardation value on a plane direction retardation value measured at a wavelength of 550nm of the optical film.

At this time, the optical film preferably has a width of 1300 mm to 3500 mm and a thickness of 10 μm to 40 μm.

The present invention also provides a polarizing plate and a liquid crystal display providing the optical film.

The optical film produced by the production method of the present invention can realize a retardation property effectively having a refractive index distribution of n _x > n _z > n _y even in a single film, and can be manufactured in a thin shape, The color and the change of the sensation are less than those of the laminated film of two or more layers.

In particular, in the manufacturing method of the present invention, the birefringent film is uniaxially stretched in the width direction (TD) before heat shrinkage, and the stretched birefringent film is shrunk in the width direction (TD) by using the shrinkable film , The optical film to be produced can have a sufficiently wide width and a thin thickness, and therefore, it has a high productivity and a high possibility of mass production.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing an exemplary result of heat shrinkage of a laminate manufactured according to the present invention. FIG.

First, terms used in this specification are defined.

(1) where n _x is the refractive index in the direction in which the refractive index in the plane direction is the maximum (that is, the slow axis direction), and n _y is the refractive index in the direction perpendicular to the slow axis in the plane direction , and n _z means the refractive index in the thickness direction. The n _x , n _y , and n _z are measured in light having a wavelength of 550 nm. Meanwhile, n _{x ,} n _{y , and} n _z can be measured by a well-known method well known in the art. For example, measurement can be performed using prism coupler equipment (SPA-3DR manufactured by SAIRON TECHNOLOGY) Do.

(2) R _in means a retardation value in the plane direction in the light having a wavelength of 550 nm, and is obtained by the retardation value R _in = (n _x -n _y ) x d. Here, n _x and n _y are the same as described above, and d represents the thickness of the film. On the other hand, R _{in (a)} means the retardation value in the plane direction of the birefringent film, and R _{in (b)} means the retardation value in the plane direction of the optical film. On the other hand, _in the R it can be measured by a known method known in the art and, for example, can be measured using the equipment of Axoscan Axomatrics社.

(3) R _th means the retardation value in the thickness direction in the light having the wavelength of 550 nm, and is obtained by the thickness direction retardation value R _th = (n _z -n _y ) x d. Here, n _y and n _z are the same as described above, and d represents the thickness of the film. On the other hand, R _{th (a)} means the thickness direction retardation value of the birefringent film, and R _{th (b)} means the thickness direction retardation value of the optical film. On the other hand, the R _th can be determined by well-known methods known in the art and, for example, can be measured using the equipment of Axoscan Axomatrics社.

(4) A birefringent film refers to a film that exhibits a refractive index in a specific direction by stretching. At this time, when the maximum refractive index is expressed in the stretching direction, the birefringent film is specifically defined as a film having a maximum refractive index Is specifically referred to as a negative birefringent film.

(5) A shrinkable film means a film having greater heat shrinkage than the above-mentioned birefringent film. More specifically, the shrinkable film has a width shrinkage of about 10% or more as measured in a single film state under the same heat shrinkage condition it means. On the other hand, the width shrinkage ratio can be measured by a well-known method well known in the art. For example, the film may be spotted at 1 cm intervals, then shrink the film using Zwick Universe Testing Machine (UTM) equipment and measure the distance of the point after shrinkage.

(6) In the present specification, the pressure-sensitive adhesive means the following properties.

- It is a semi-solid substance with high viscosity and low elasticity.

- Combine with the adherend by applying pressure.

- The state does not change during the coupling process.

- It is a type of wide adhesive, which is called a pressure-sensitive adhesive (PSA) because it exhibits an adhesive force after being interposed between adherends.

(7) In this specification, the active energy ray-curable resin layer means that the following properties are distinguished from the above-mentioned pressure-sensitive adhesives.

- When the composition is in a liquid state and has a low viscosity with fluidity, when it is applied to an adherend, the adhesion area is increased by wetting the adherend and cured by irradiation of active energy ray to bond with the adherend.

- Increase in active energy radiation dose leads to cure through adhesive state.

- In the bonding process, the state irreversibly changes from a liquid phase to a solid phase.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Further, the embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art. The shape and size of elements in the drawings may be exaggerated for clarity.

1. Optical film manufacturing method

The inventors of the present invention have conducted extensive research to solve the above problems. As a result, they have found that a birefringent film is uniaxially stretched in the transverse direction (TD) in advance and adhered to a shrinkable film to form a laminate, It has been found out that the optical film to be produced can have a sufficiently wide width and a thin thickness when shrinking, and that the productivity is high and the mass production possibility is high, and the present invention has been completed.

More specifically, the method for producing an optical film of the present invention comprises: uniaxially stretching an unstretched birefringent film in a transverse direction (TD); Attaching the stretched birefringent film to a shrinkable film to form a laminate; And heat-shrinking the laminate in the transverse direction (TD) so that the stretched birefringent film satisfies the following formula (1).

Equation (1): n _x > n _z > n _y

Ny is a refractive index in a direction perpendicular to the nx direction of the birefringent film, nz is a thickness of the birefringent film in the direction perpendicular to the nx direction, nz is a thickness of the birefringent film, Direction.

end. Unfinished Birefringence  film Stretching  step

First, the unoriented birefringent film used in the present invention may be a positive birefringent film or a negative birefringent film which is generally used in the art as a precursor film of an optical film finally produced, without any particular limitation. For example, the above-mentioned birefringent film includes, but is not limited to, polyethylene terephthalate, polyamide, polyimide, polycarbonate, polyester, polyurethane, polypropylene, triacetylcellulose, polyamideimide, polyvinyl Those containing an alcohol, polyvinyl chloride, polyphenylene ether, polyarylate, polyaryl ether ketone, polyether ketone, polyester imide, polyfumaric acid ester, polyethersulfone, polyolefin and the like can be used. The negative birefringent film may include, but is not limited to, polymethyl methacrylate, polystyrene, and the like.

On the other hand, the unoriented birefringent film is more preferably a positive birefringent film. Definition The birefringent film exhibits the maximum refractive index in the stretching direction. When the film is forced to shrink in a direction perpendicular to the stretching direction by using a shrinkable film in the high-temperature stretching process, n _x > n _z > n _y There is an advantage that it can be easily implemented. The positive birefringent film preferably comprises a polycarbonate, a polyamide, a polyimide, or a polyamideimide including a benzene ring or an alicyclic ring in the main chain. In this case, since the retardation manifestation is excellent, it is possible to effectively realize a high retardation value even in a thin film thickness.

On the other hand, the thickness of the unoriented birefringent film is preferably 10 탆 to 100 탆, for example, 10 탆 to 80 탆 or 10 탆 to 75 탆. In the case of having such a thickness range, thinning can be achieved by stretching, and the range of the retardation value added by the present invention can be implemented effectively.

On the other hand, the unoriented birefringent film preferably has a light transmittance at a wavelength of 290 nm or more of 80% or more, for example, a light transmittance at a wavelength of 290 to 800 nm or a wavelength of 290 to 500 nm of 80% to 95% Or 80% to 90%. In the case of the present invention, it is preferable to adhere the birefringent film and the shrinkable film via an active energy ray-curable resin layer. In the case of the cationically curable resin layer of the active energy ray curable resin layer, When a birefringent film having a light transmittance of 80% or less in the vicinity thereof is used, it is difficult to pass ultraviolet rays, so that hardening of the resin layer may be difficult. On the other hand, the light transmittance can be measured by a publicly known method, for example, using a U-3310 spectrometer manufactured by Hitachi.

On the other hand, the glass transition temperature of the unoriented birefringent film is preferably 20 ° C or more, more preferably 20 ° C to 100 ° C or 30 ° C to 80 ° C, more preferably 20 ° C or more higher than the glass transition temperature of the shrinkable film have. When the glass transition temperature is different, the shrinkable film is strongly shrunk in the high temperature stretching process, and the birefringent film is relatively hard in the state of the polymer, so that the shrinkage is not strong in itself. At this time, the birefringent film is further shrunk by forcibly shrinking due to the strong shrinkable film, and as a result, the polymer is strongly oriented, so that a high retardation can be exhibited. The method of measuring the glass transition temperature is not particularly limited, and for example, the glass transition temperature can be measured by a differential scanning calorimeter (DSC). For example, in the case of using a differential scanning calorimeter (DSC), when a sample of about 10 mg is sealed in a dedicated pan and heated at a constant temperature, the amount of endothermic heat The transition temperature can be measured.

Next, when the unoriented birefringent film as described above is prepared, the birefringent film is uniaxially stretched in the transverse direction (TD). In this case, the birefringent film can have a sufficiently wide width and a thin thickness even after heat shrinkage, and as a result, there is an advantage that productivity and mass production possibility of the optical film are high.

In this case, the stretching is preferably performed so that the width of the birefringent film after stretching is 1400 mm to 6000 mm. For example, it is preferable that the width of the birefringent film after stretching is 1500 to 6000 mm or 1550 to 4000 mm Do. When the width of the birefringent film after stretching satisfies the above range, it can have a sufficient width at a thin thickness after the heat shrinkage, so that it can have excellent productivity and mass productivity as described above.

It is preferable that the stretching is performed so that the thickness of the birefringent film after stretching becomes 5 占 퐉 to 40 占 퐉. For example, the thickness of the birefringent film after stretching is 10 占 퐉 to 30 占 퐉 or 18 占 퐉 to 25 占 퐉 . ≪ / RTI > When the thickness of the birefringent film after stretching satisfies the above range, it is possible to produce a thin optical film without problems such as breakage, and it is easy to realize a desired retardation value.

The stretching is preferably performed so that the birefringent film after stretching satisfies the following formula (2). For example, after the stretching, the birefringent film may have a retardation value of 0 to 50 nm or 0 to 30 nm It can be done. As the retardation in the plane direction of the birefringent film after stretching becomes closer to zero phase difference, it is easy for the birefringent film to realize a retardation characteristic suitable for application to the IPS mode or the like after the heat shrinking step to be described later.

(2): 0 nm? R _{in (a)} ? 100 nm

In the above formula (2), R _{in (a)} is the retardation value of the birefringent film measured at a wavelength of 550 nm.

The stretching is preferably performed so that the birefringent film after stretching satisfies the following formula (3). For example, after the stretching, the retardation value in the thickness direction of the birefringent film is in the range of -50 nm to 50 nm or -35 nm to 35 nm . ≪ / RTI > Similarly, as the retardation in the thickness direction of the birefringent film after stretching approaches zero phase difference, it is easy for the birefringent film to realize a retardation characteristic suitable for application to the IPS mode or the like, after the heat shrinking step to be described later.

Formula (3): -100 nm? R _{th (a)} ? 100 nm

In the above formula (3), R _{th (a)} is the thickness direction retardation value of the birefringent film measured at a wavelength of 550 nm.

When the glass transition temperature of the birefringent film is Tg, the stretching is preferably performed at a temperature of (Tg) to (Tg + 50 deg. C), for example, (Tg + 10 deg. + 30 ° C) or at a temperature of (Tg + 20 ° C) to (Tg + 30 ° C). If the stretching temperature is within such a range, it is easy for the birefringent film after stretching to have the width, thickness, and retardation value as described above.

In addition, the stretching is preferably performed at a stretching magnification of 1.5 to 6.0 times, for example, at a stretching magnification of 1.5 to 3.5 times or 2.0 to 3.0 times. When the stretching magnification satisfies the above range, it is also easy for the birefringent film after stretching to have the width, thickness, and retardation value as described above.

On the other hand, the stretching method is not particularly limited and may be carried out by a stretching method well known in the art. For example, a tenter may be used for drawing in the width direction (TD).

I. The laminate  Forming step

First, the stretched film and the shrinkable film adhered to the birefringent film are stretched so as to forcibly shrink the birefringent film in the width direction (TD) so that the birefringent film can satisfy the relationship of n _x > n _z > n _y As the film, if the shrinkable film usable in the present invention has greater heat shrinkability than the birefringent film, a known resin film can be used without any particular limitation. For example, but not limited to, polymethyl methacrylate, polyethylene terephthalate, polyamide, polyimide, polycarbonate, polyester, polyurethane, polypropylene, triacetylcellulose, polystyrene, polyamideimide, polyvinyl Alcohol, polyvinyl chloride, polyphenylene ether, and the like can be used. However, as described above, the width shrinkage measured in a single film state under the same heat shrinkage condition is at least about 10 % Should be larger.

On the other hand, the shrinkable film is preferably, but not particularly limited to, polyethylene terephthalate. Polyethylene terephthalate is not only excellent in price competitiveness but also has excellent heat shrinkability during high temperature stretching due to its low glass transition temperature.

On the other hand, the shrinkable film may be a uniaxially or biaxially stretched film. For example, the shrinkable film may be uniaxially stretched in the width direction (TD), or biaxially stretched in the longitudinal direction (MD) and the width direction have. At this time, the present invention can be used as a commercially available shrinkable film, which is uniaxially or biaxially stretched, or can be used by uniaxially or biaxially stretching a commercially available shrinkable unoriented polymer film.

Next, the form of attachment of the stretched birefringent film and the shrinkable film is not particularly limited. For example, the birefringent film may be attached to one side or both sides of the stretched birefringent film, or both sides of the shrinkable film To which a stretched birefringent film is adhered.

Among them, it is more preferable to form a laminate by attaching a shrinkable film to both surfaces of a stretched birefringent film, or by attaching a stretched birefringent film to both surfaces of a shrinkable film. In this case, it is possible to prevent curling and wrinkling of the birefringent film that may occur during the heat shrinkage process, and to provide appropriate shrinkage force, so that a desired retardation can be easily realized. On the other hand, in the case of forming a laminate by a method of attaching a stretched birefringent film to both sides of a shrinkable film, two optical films can be manufactured by one step, and the advantage of being very excellent in productivity can also be obtained have.

Next, a known pressure-sensitive adhesive, an adhesive, or the like can be used as the attachment means for forming the laminate, and it is particularly preferable to use an active energy radiation curable resin layer. According to the study of the inventors of the present invention, when a pressure-sensitive adhesive such as an acrylic pressure-sensitive adhesive is used, adhesive residue by a pressure-sensitive adhesive is generated and not only the productivity is lowered but also the two layers of the film adhered by the pressure- There is a problem that the birefringent film can not be sufficiently shrunk. Further, in the case of using an aqueous adhesive, for example, a polyvinyl alcohol-based water-based adhesive, among the adhesives, bubbles are generated in the film after peeling off by moisture. In contrast, when the active energy ray-curable resin layer is used, the above-mentioned problems do not occur.

On the other hand, the active energy ray-curable resin layer usable in the present invention is not particularly limited, and various active energy ray-curable compositions having the above-described characteristics can be selected for the birefringent film and the shrinkable film to be selected and cured Can be used. That is, not only the formula (1) to be described later but also the formula (2) to be described later are also satisfied, more preferably the formulas (3) and (4) are also satisfactory By selecting an active energy ray curable composition and curing it.

Examples of the active energy ray curable composition generally used in this technical field include photo radical polymerization such as a (meth) acrylate radical curable composition, an en / thiol radical curable composition, and an unsaturated polyester radical curable composition , A composition using a cationic photopolymerization reaction such as an epoxy-based cationic curable composition, an oxetane-based cationic curable composition, an epoxy / oxetane-based cationic curable composition, and a vinyl ether-based cationic curable composition.

More specifically, for example, the composition using the photo radical polymerization reaction is not limited thereto, but it is possible to use a first compound represented by the following formula (1), a second compound comprising at least one carboxyl group, and a radical initiator Based on the total weight of the composition.

[Chemical Formula 1]

In the above formula (1), R ₁ represents an ester group or an ether group; R ₂ is C _{1 ~ 10} alkyl group, a C _4-10 cycloalkyl group, or a combination thereof, wherein R ₂ has at least one hydroxy substituent in the molecule; R ₃ is hydrogen, or a substituted or unsubstituted C _{1 ~ 10} alkyl group; On the other hand, the hydroxy group may be substituted at any position in the alkyl group or the cycloalkyl group. For example, the hydroxy group may be at the terminal of the alkyl group or may be in the middle of the alkyl group. Meanwhile, the remaining hydrogen atoms contained in the alkyl group or the cycloalkyl group may be substituted with any substituent.

At this time, the first compound is a component for realizing an adhesive force, and various compounds represented by Formula 1 may be used. For example, the first compound may be at least one compound selected from compounds represented by the following formulas (2) to (11), though not limited thereto.

(2)

(3)

[Chemical Formula 4]

[Chemical Formula 5]

[Chemical Formula 6]

(7)

[Chemical Formula 8]

[Chemical Formula 9]

[Chemical formula 10]

(11)

In addition, the second compound is for improving the heat resistance and the viscosity property of the composition, and includes at least one carboxyl group. More specifically, the second compound may be at least one selected from the group consisting of compounds represented by the following formulas (12) to (26).

[Chemical Formula 12]

[Chemical Formula 13]

[Chemical Formula 14]

또는

이고, p는 1 내지 5의 정수임)(Wherein R 'is

or

And p is an integer of 1 to 5)

[Chemical Formula 15]

[Chemical Formula 16]

[Chemical Formula 17]

[Chemical Formula 18]

[Chemical Formula 19]

[Chemical Formula 20]

[Chemical Formula 21]

[Chemical Formula 22]

(23)

≪ EMI ID =

(25)

(26)

In addition, the radical initiator contained in the radical curable composition is used for promoting radical polymerization to improve the curing rate. As the radical initiator, radical initiators generally used in the art can be used without particular limitation . For example, phosphine oxide, phenyl bis (2,4,6-trimethyl benzoyl), and the like can be preferably used, though not limited thereto .

Meanwhile, the radically curable composition may further contain an acrylic monomer containing a cyclic structure having 7 to 20 carbon atoms, preferably 7 to 15 carbon atoms, as a third compound for viscosity control. More specifically, the third compound is selected from, for example, isobornyl (meth) acrylate, norbornyl (meth) acrylate, dicyclopentanyl (meth) A group consisting of dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate and 1-adamantyl- (meth) acrylate , But the present invention is not limited thereto.

More preferably, the radical curable composition comprises 40 to 80 parts by weight of the first compound, 15 to 50 parts by weight of the second compound, and 0.5 to 10 parts by weight of the radical initiator based on 100 parts by weight of the total composition .

More specifically, for example, but not limited to, the composition using the photo cationic polymerization, the first epoxy compound or homopolymer having a glass transition temperature of 120 캜 or higher of the homopolymer may have a glass transition temperature of 60 캜 or lower A second epoxy compound and a photo cationic polymerization initiator. The epoxy compound means a compound having at least one epoxy group in the molecule, preferably a compound having at least two epoxy groups in the molecule, and a compound in the form of a monomer, a polymer or a resin . Preferably, the epoxy compound of the present invention may be in the form of a resin.

The first epoxy compound may be an epoxy compound having a glass transition temperature of not lower than 120 ° C. and may be used without any particular limitation. For example, the first epoxy compound may be an alicyclic epoxy compound having a glass transition temperature of 120 ° C. or higher and / An 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 120 ° C or higher of the homopolymer include 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, vinylcyclohexene dioxide dicyclopentadiene dioxide, bis epoxycyclo Pentyl ether, bisphenol A-based epoxy compounds, and bisphenol F-based epoxy compounds. It is more preferable that the glass transition temperature of the homopolymer of the first epoxy compound is about 120 ° C to 200 ° C.

The second epoxy compound can be used without any particular limitation as long as it is an epoxy compound having a glass transition temperature of 60 占 폚 or less of the homopolymer. For example, the second epoxy compound may be an alicyclic epoxy compound, an aliphatic epoxy compound, or the like. At this time, as the alicyclic epoxy compound, a bifunctional epoxy compound, that is, a compound having two epoxy groups is preferably used, and it is more preferable to use a compound in which the two epoxy groups are alicyclic epoxy groups. But is not limited to. As the aliphatic epoxy compound, an epoxy compound having an aliphatic epoxy group rather than an alicyclic epoxy group can be exemplified. For example, polyglycidyl ethers of aliphatic polyhydric alcohols; Polyglycidyl ethers of alkylene oxide adducts of aliphatic polyhydric alcohols; Polyglycidyl ethers of polyester polyols of aliphatic polyhydric alcohols and aliphatic polyvalent carboxylic acids; Polyglycidyl ethers of aliphatic polyvalent carboxylic acids; Polyglycidyl ethers of polyester polycarboxylic acids of aliphatic polyhydric alcohols and aliphatic polyvalent carboxylic acids; Dimers, oligomers or polymers obtained by vinyl polymerization of glycidyl acrylate or glycidyl methacrylate; Or an oligomer or polymer obtained by vinyl polymerization of glycidyl acrylate or glycidyl methacrylate and other vinyl monomers, and preferably an aliphatic polyhydric alcohol or an alkylene oxide adduct thereof polyglycidyl Ethers may be used, but are not limited thereto.

Preferably, the second epoxy compound of the present invention may contain at least one glycidyl ether group, and examples thereof include 1,4-cyclohexanedimethanol diglycidyl ether, 1,4-butanediol di Hexyldiol diglycidyl ether, neopentyldiglycidyl ether, resorcinol diglycidyl ether, diethylene glycol di glycidyl ether, ethylene glycol di glycidyl ether, 1,6-hexanediol diglycidyl ether, One selected from the group consisting of trimethylolpropane triglycidyl ether, n-butyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, and o-cresyl glycidyl ether. Or more can be used as the second epoxy compound of the present invention.

On the other hand, the second epoxy compound preferably has a glass transition temperature of the homopolymer of about 0 캜 to 60 캜

It is particularly preferable to use a combination of a first epoxy compound containing at least one epoxidized aliphatic ring group and a second epoxy compound containing at least one glycidyl ether group as the epoxy compound. When such a combination of the first epoxy compound and the second epoxy compound is used, it has been found that not only the low viscosity and the adhesive strength are satisfied but also the thermal shock property of the polarizing plate is improved.

Meanwhile, the second epoxy compound is preferably contained in an amount of 30 to 100 parts by weight based on 100 parts by weight of the first epoxy compound. When the content of the second epoxy compound is more than 100 parts by weight, the glass transition temperature of the whole composition is lowered to lower the heat resistance. If the content is less than 30 parts by weight, the adhesive strength may be lowered.

More preferably, the weight ratio of the first epoxy compound to the second epoxy compound is about 1: 1 to 3: 1, more preferably 1: 1 to 2: 1, An epoxy compound and a second epoxy compound may be mixed and used in a weight ratio of 1: 1. When the weight ratio of the first epoxy compound and the second epoxy compound is in the above range, the most preferable physical properties in terms of the glass transition temperature and the adhesion can be obtained.

On the other hand, the cationic photopolymerization initiator is a compound which produces a cationic species or Lewis acid by irradiation with an active energy ray. Examples of the cationic photopolymerization initiator include onium salts such as aromatic diazonium salts, aromatic iodine aluminum salts and aromatic sulfonium salts, Iron-arene complex, and the like, but the present invention is not limited thereto. On the other hand, the content of the cationic photopolymerization initiator is about 0.5 to 20 parts by weight, preferably about 0.5 to 15 parts by weight, more preferably about 0.5 to 10 parts by weight based on 100 parts by weight of the first epoxy compound .

The cationically curable composition may further contain 100 to 400 parts by weight of an oxetane compound having at least one oxetanyl group in the molecule, if necessary. When an oxetane compound is used, the viscosity of the composition can be lowered to make the resin layer thinner after curing.

On the other hand, the oxetane compound is not particularly limited as long as it has at least one oxetanyl group in the molecule, and various oxetane compounds well known in the art can be used. Examples of the oxetane compound of the present invention include 3-ethyl-3 - [(3-ethyloxetan-3-yl) methoxymethyl] oxetane, 1,4-bis [ 3-yl) methoxymethyl] benzene, 1,4-bis [(3-ethyloxetane-3-yl) methoxy] benzene, 1,3- ) Methoxy] benzene, 1,2-bis [(3-ethyloxetan-3-yl) methoxy] benzene, 4,4'- Phenyl, 3,3 ', 5,5'-tetramethyl-4,4'-bis [3-ethyloxetane-3-yl] 3-yl) methoxy] naphthalene, bis [4 - {(3-ethyloxetan-3-yl) ) Methoxy} phenyl] methane, bis [2 - {(3-ethyloxetane-3-yl) methoxy} phenyl] methane, 2,2- ) Methoxy} phenyl] propane, an etherified product of 3-chloromethyl-3-ethyloxetane of novolak type phenol-formaldehyde resin, 3 (4) Oxetane- (3-ethyloxetan-3-yl) methoxymethyl] norbornane, 1,1,1,3,3-tetramethyl- Methoxy methyl] propane, 1-butoxy-2,2-bis [(3-ethyloxetan-3-yl) methoxymethyl] , [2- (3-ethyloxetan-3-yl) methoxy} ethylthio] ethane, bis [{4- , And 1,6-bis [(3-ethyloxetan-3-yl) methoxy] -2,2,3,3,4,4,5,5-octafluorohexane. On the other hand, the content of the oxetane compound is preferably 100 to 400 parts by weight, more preferably 150 to 300 parts by weight based on 100 parts by weight of the first epoxy compound.

On the other hand, when two oxetanyl groups are used as the oxetane compound, it is effective to increase the glass transition temperature of the resin layer after curing, and it is advantageous in the case of having one oxetanyl group.

Meanwhile, the active energy ray curable composition used in the present invention is preferably cured by ultraviolet rays having a wavelength of 320 nm or more. In general, a polyethylene terephthalate film used as a shrinkable film does not transmit light of a low region, for example, light of 310 nm or less. Therefore, an active energy ray curable composition which is cured by ultraviolet rays of such a low region wavelength is used It is troublesome to irradiate ultraviolet rays to both sides of the laminate for curing. However, in the case of using an active energy ray-curable composition which can be cured even by a relatively high wavelength, for example, ultraviolet rays of 320 nm or more, curing of the adhesive body can be performed even if ultraviolet rays are irradiated on only one side of the laminate , The manufacturing process is further simplified, and the productivity is improved.

From this point of view, in the case of the present invention, it is preferable to use, among the active energy ray curable composition, a composition which uses a photo radical polymerization reaction. Since a composition using a photo radical polymerization reaction mainly uses a radical initiator that absorbs a region of about 390 nm, it is possible to irradiate ultraviolet rays on only one surface in order to cure both of them. On the other hand, a composition using a photo cationic polymerization reaction mainly uses a cationic initiator that absorbs a region of about 295 nm. In order to cure both of them, there is a need to irradiate ultraviolet rays on both sides.

Meanwhile, the active energy ray-curable resin layer used in the present invention preferably has a glass transition temperature of 70 ° C or higher, for example, about 70 ° C to 150 ° C or about 80 ° C to 120 ° C. In this case, since it can have sufficient heat resistance, it can have a sufficient adhesive force in the high temperature stretching process for heat shrinkage.

On the other hand, in the case of forming a laminate through such an active energy ray-curable resin layer, the method of forming the laminate is not particularly limited, and for example, a method of applying an active energy ray curable composition between a birefringent film and a shrinkable film And then curing them by laminating them and irradiating the active energy ray-curable composition with active energy rays.

At this time, the method of applying the active energy ray-curable composition between the birefringent film and the shrinkable film is not particularly limited. For example, by flowing the active energy ray-curable composition on the birefringent film or the shrinkable film in a dripping manner, A method of forming a sufficient amount of banks (BANK) can be used.

Also, the method of laminating is not particularly limited, and for example, a lamination process or the like may be used in which the films are passed between two rolls rotating in opposite directions while adhering them using a composition.

The method of curing the active energy ray curable composition is also not particularly limited, and may be performed by, for example, curing by irradiation with active energy rays such as ultraviolet rays, visible rays, electron rays, and X rays. At this time, the method of irradiation is not particularly limited. For example, ultraviolet light having a light intensity of about 500 mJ / cm ² is irradiated using an ultraviolet irradiator (LH10 Fusion D bulb) under conditions of about 2000 mW / cm ² and a speed of about 20 m / min And the like.

Meanwhile, the laminate of the present invention formed by the above-described method may have a length to width ratio of 1.5 times or more, preferably about 2 to 8 times, more preferably about 2 to 5 times. As described above, the longer the length of the laminate is, the weaker the force transmitted to the central portion of the laminate is, so that the shrinkage can be more freely generated.

All. The laminate  Heat shrinkage step

When the laminate is formed in the same manner as described above, the laminate is thermally shrunk. At this time, the production method of the optical film of the present invention satisfies the following formula (1) by the heat shrinkage step. That is, the birefringent film attached to the shrinkable film is forced to shrink in the width direction (TD) by the shrinkable film, and as a result, the refractive index in the width direction (TD) becomes smaller than the refractive index in the thickness direction, n _x > n _z > n _y . When the birefringent film finally satisfies n _x > n _z > n _y , it can be very useful as an IPS mode retardation film.

Equation (1): n _x > n _z > n _y

In the formula (1), n _x is birefringent, and the plane direction refractive index is the maximum refractive index in the direction of the film, n _y is a refractive index in the direction perpendicular to the n _x direction in the birefringent film, n _z is the birefringence Is the refractive index in the thickness direction of the film.

On the other hand, it is preferable that the production method of the optical film of the present invention satisfies the following formula (2) by the heat shrinkage step. As described above, when the birefringent film and the shrinkable film shrink at substantially the same magnification in the laminated state, the birefringent film can be sufficiently shrunk, so that it is possible to manufacture an optical film of very high quality. More preferably, the difference between the width shrinkage percentage of the shrinkable film in the laminated state and the width shrinkage percentage of the birefringent film in the laminated state may be about 0% to 3%, 0% to 2%, or 0% to 1%. On the other hand, the width shrinkage ratio can be measured by a well-known method well known in the art. For example, before the laminate is formed, dots are taken at intervals of 1 cm on one side of both the birefringent film and the shrinkable film, , Peeling off the film after heat shrinkage, and measuring the distance between the respective films.

(2): 0%? S ₂ - S ₁ ? 5%

In the formula (2), S ₁ is a shrinkage ratio in the direction perpendicular to the stretching direction of the birefringent film in the laminated state, S ₂ is a shrinkage ratio in the direction perpendicular to the stretching direction of the heat shrinkable film in the laminated state Shrinkage ratio.

Further, it is preferable that the production method of the optical film of the present invention satisfies the following formulas (3) and (4) by the heat shrinkage step. As described above, when the adhesive force between the birefringent film and the shrinkable film before heat shrinkage has an adhesive force of about the following range, there is an advantage that peeling can not easily occur in the heat shrinkage stage. At the same time, If it has an adhesive strength of about the following range, there is an advantage that it can be easily peeled off without damaging the film during peeling after heat shrinkage. More preferably, the adhesive strength between the birefringent film and the shrinkable film before heat shrinkage may be about 0.10 N / 2 cm to 0.50 N / 2 cm or about 0.15 N / 2 cm to 0.30 N / 2 cm, and the adhesive force between the birefringent film and the shrinkable film The adhesive force may be about 0.05 N / 2 cm to about 0.30 N / 2 cm or about 0.10 N / 2 cm to about 0.15 N / 2 cm. The following adhesive strength can be measured by a well-known method well known in the art. For example, it can be measured using a Texture Analyzer (Model: TA-XT Plus) equipment of Stable Micro Systems.

(3): 0.10 N / 2 cm? P _a ? 1.0 N / 2 cm

(4): 0.01 N / 2 cm? P _b ? 0.50 N / 2 cm

In the above formulas (3) and (4), P _a is the adhesive strength between the birefringent film and the shrinkable film before heat shrinkage, and P _b is the adhesion strength between the birefringent film and the shrinkable film after heat shrinkage.

On the other hand, the heat shrinking step is preferably performed by a method of uniaxially stretching the laminate in the longitudinal direction (MD) by using a known drawing machine or the like. For example, uniaxial stretching can be performed by pulling the laminate in the longitudinal direction (MD) using UTM equipment while holding both ends of the laminate in the longitudinal direction (MD) in an oven at high temperature. The birefringent film used in the present invention is preferably a positive birefringent film exhibiting a maximum refractive index along the stretching direction. In this case, the longitudinal direction MD becomes the x direction (the direction in which the refractive index becomes maximum) The direction TD becomes the y direction (direction perpendicular to the direction in which the refractive index becomes the maximum). At this time, the laminate shrinks in the y direction which is the width direction (Td) due to the high temperature stretching. In particular, the birefringent film shrinks sharply when it is laminated with the shrinkable film which relatively shrinks more easily, _{Since y} is smaller than n _z , n _x > n _z & gt _; n < _y & gt _; can be effectively implemented.

The stretching is preferably performed at a temperature of (Tg ') to (Tg' + 100 ° C), for example, (Tg '+ 20 ° C) when the glass transition temperature of the shrinkable film is Tg' To (Tg ' + 80 < 0 > C). A high retardation can be realized only when the stretching temperature satisfies the above range. Specifically, at such a stretching temperature, the birefringent film tends to shrink sharply, but the shrinkable film tends to shrink very strongly. Since these are adhered by the resin layer, the birefringent film has strong shrinkage And, as a result, can have a high phase difference.

In addition, the stretching is preferably performed at a draw magnification of 1.1 to 3.0 times, for example, at a draw magnification of 1.1 to 2.5 times or 1.1 to 2.0 times. When the stretching at such a stretching magnification is performed, the birefringent film can be shrunk in the width direction as much as desired by the present invention, and the present invention can realize a phase difference as high as desired.

la. Birefringence  Film peeling step

Meanwhile, the manufacturing method of the present invention may further include peeling the birefringent film from the shrinkable film after the heat shrinking step. That is, in order to use the birefringent film as a single retardation film, peeling is preferable. On the other hand, the peeling step may proceed at room temperature, and the peeling method is not particularly limited.

2. Optical element and optical film

The present invention also provides an optical member manufactured by the above manufacturing method. Specifically, the present invention provides a birefringent film uniaxially stretched in the transverse direction (TD) and a shrinkable film, wherein the birefringent film satisfies the above-mentioned formula (1). In this case, the material and the lamination method of the shrinkable film and the birefringent film are the same as described above, and the optical member is also more preferably satisfying the above-described formula (2), and more preferably, ) And (4).

The present invention also provides an optical film produced by the above-mentioned production method. At this time, the optical film of the present invention preferably satisfies at least one of the following formulas (7) to (9). In this case, it can be very useful as a retardation film for IPS mode. More preferably, the optical film according to the present invention has a retardation value in the range of about 200 nm to about 300 nm, a retardation value in the range of about 100 nm to about 200 nm, and an Nz value in the range of about 0.2 to about 0.9 or about 0.3 to about 0.7 have.

(7): 150 nm? R _{in (b)} ? 350 nm

(8): 50 nm? R _{th (b)} ? 250 nm

Equation (9): 0.1? Nz _(b) ? 1

In the above formulas (7) to (9), R _{in (b)} is a retardation value of the optical film measured at a wavelength of 550 nm, R _{th (b)} and, Nz _(b) being the ratio (R _th / R _in) of the thickness retardation value on a plane direction retardation value measured at a wavelength of 550nm of the optical film.

At this time, the width of the optical film is preferably about 1300 mm to 3500 mm, and more preferably about 1400 mm to 3000 mm. In order to match the width of the currently produced polarizing plate, the width of the optical film to be manufactured must satisfy the above-mentioned range, and this case is applicable to the actual industry.

Further, the thickness of the optical film is preferably about 10 탆 to 40 탆, and more preferably about 10 탆 to 35 탆. If the thickness of the optical film to be manufactured is as thin as that, the polarizing plate and the liquid crystal display including the polarizing plate and the liquid crystal display device can be made thin and light.

3. Polarizer and liquid crystal display

The present invention also provides a polarizing plate comprising at least one optical film. In this case, the optical film according to the present invention may be directly attached to one side or both sides of the polarizer, or may be attached to a protective film of a polarizer having a protective film on both sides of the polarizer, and thus may be usefully used as a retardation film. When the optical film is directly adhered to one surface or both surfaces of the polarizer, for example, the structure may be an upper protective film / a polarizer / an optical film, an optical film / a polarizer / a lower protective film, an optical film / an upper protective film / Protective film or an upper protective film / polarizer / lower protective film / optical film.

The present invention also provides a liquid crystal display device including at least one optical film. For example, the present invention provides an IPS mode liquid crystal display including at least one optical film. The liquid crystal display may include a liquid crystal cell and a first polarizing plate and a second polarizing plate disposed on both surfaces of the liquid crystal cell, and the optical film may include the liquid crystal cell, the first polarizing plate and / And may be provided as a retardation film between the polarizing plates. That is, an optical film may be provided between the first polarizing plate and the liquid crystal cell, and one optical film may be provided between the second polarizing plate and the liquid crystal cell, or between the first polarizing plate and the liquid crystal cell, 2 or more .

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

Manufacturing example  One - Birefringence  film

(1) Birefringent film A

A pellet was prepared from a 30φ L / D 40 Vent-type Co-rotating Twin Extruder at 250 ° C. using a polycarbonate resin (LG Chem, DVD 1080, Tg = 148 ° C.). An unoriented film having a width of 1200 mm and a thickness of 47.3 탆 was prepared by melting the raw pellets prepared above at 250 캜 in an extruder with an extruder and then passing them through a coat hanger type T-die. At this time, the light transmittance of the polycarbonate resin at a wavelength of 290 nm was 80% or more. The unoriented film was uniaxially stretched at 166 DEG C in the TD direction at a ratio of 2 times using a tenter machine to produce a uniaxially stretched birefringent film A having a width of 2400 mm and a thickness of 23.1 mu m. On the other hand, the stretched film had a width shrinkage of 12% when unidirectionally stretched by 20% in the longitudinal direction (MD) using UTM equipment in a 152 ° C oven.

(2) Birefringent film B

A pellet was prepared from a 30φ L / D 40 Vent-type Co-rotating Twin Extruder at 250 ° C. using a polycarbonate resin (LG Chem, DVD 1080, Tg = 148 ° C.). The raw pellets thus prepared were melted in an extruder at 250 캜 by an extruder and then passed through a T-die of a coat hanger type to obtain an unstretched birefringent film having a width of 1200 mm and a thickness of 20.8 탆 B was prepared. At this time, the light transmittance of the polycarbonate resin at a wavelength of 290 nm was 80% or more. On the other hand, the unstretched film also had a width shrinkage of 12% when it was uniaxially stretched by 20% in a longitudinal direction (MD) using UTM equipment in a 152 ° C oven.

Manufacturing example  2 - shrink film

A polyethylene terephthalate stretched film (TP69C, biaxially stretched by SKC, Tg = 76 ° C) commercially available as a shrinkable film was used. On the other hand, the stretched film had a shrinkage in the transverse direction (TD) of 58% when unidirectionally stretched by 20% in the longitudinal direction (MD) using a UTM machine in an oven at 152 ° C.

Manufacturing example  3 - Radical  Curable composition

Radical curable compositions were prepared for use as active energy ray curable resin layers. Specifically, the radical curable composition is prepared by dissolving 70% by weight of 2-hydroxyethyl acrylate, 10% by weight of itaconic acid, and 4,4 '- ((((propane-2,2-diylbis Bis (oxy)) bis (1- (methacryloyloxy) propane-3,2-diyl)) bis (oxy)) bis (4-oxobutanoic acid) , 3 parts by weight of a radical initiator phenyl bis (2,4,6-trimethylbenzoyl) -phosphine oxide and 5 parts by weight of a photo-acid generator, diphenyl (4-phenylthio) phenylsulfonium hexafluorophosphate . The glass transition temperature of the composition measured using a differential scanning calorimeter (DSC Mettler) was 82 ° C.

Example  One

A birefringent film A in the uniaxially stretched state of Preparation Example 1 was attached to both surfaces of the shrinkable film of Production Example 2 to form a laminate. Specifically, the radical curable composition of Preparation Example 3 was applied between the shrinkable film and the birefringent film by a dripping method, and after lamination, the laminate was laminated on one side with a UV curing machine (Light Hammer, Fusion UV) / cm ² , a speed of 2000 mW / cm ² and a speed of 20 m / min to form a laminate. Meanwhile, the lamp used for the UV curing machine was LH10 Fusion D bulb, and the distance between the lamp and the sample was 5.7 cm. On the other hand, the length of the laminate was 10 cm and the width was 5 cm, so that the ratio of the length to the width was about 2 times. The laminate was uniaxially stretched by 25% in an MD direction in a 152 ° C oven using UTM equipment. The laminate was taken out and the birefringent film attached to both sides of the shrinkable film was peeled off at room temperature to produce two optical films .

Example  2

In the same manner as in Example 1, except that the laminate was uniaxially stretched by 30% in the MD direction using a UTM machine in an oven at 152 ° C, two optical films were produced in the same manner.

Example  3

In the same manner as in Example 1, except that the laminate was uniaxially stretched by 35% in the MD direction in a 152 ° C oven using UTM equipment, two optical films were produced in the same manner.

Example  4

The two sheets of optical films were prepared in the same manner as in Example 1 except that the laminate was uniaxially stretched by 30% in the MD direction using a UTM equipment in a 153 ° C oven.

Comparative Example

Two optical films were produced in the same manner as in Example 1, except that the birefringent film B in the unstretched state of Production Example 1 was used.

Experimental Example  1 - Before contraction Birefringence  Measurement of film properties

The width, thickness and retardation characteristics of the birefringent films A and B before heat shrinkage as used in the above Examples and Comparative Examples were measured and shown in Table 1 below. Meanwhile, the width was measured using a general ruler, the thickness was measured using a Tesa u-hite thickness meter, and the phase difference value was measured using an Axoscan's Axoscan measuring apparatus.

division film Stretching condition Width (mm) Thickness (㎛) R _in (nm) R _th (nm) Example Birefringent Film A 166 占 폚 / TD / 1 axis / 2 times 2400 23.1 9.2 -31.9 Comparative Example Birefringent film B Unfinished 1200 20.8 9 -10

As can be seen from the above Table 1, unlike the unoriented birefringent film used in the comparative example, the TD uniaxially stretched birefringent film used in the examples had a sufficient width of about 2400 mm despite the thin thickness of about 23.1 탆 And further, the retardation characteristic is also close to zero phase difference.

Experimental Example  2 - Width Shrinkage ( S _One , S ₂ ) And adhesive strength P _a , P _b ) Measure

In the above Examples and Comparative Examples, the width shrinkage ratio (S ₁ ) of the birefringent film in the laminated state and the shrinkage ratio (S ₂ ) of the shrinkable film were measured and shown in Table 2 below. At this time, the width shrinkage rates (S ₁ and S ₂ ) are obtained by taking two pieces of the birefringent film and the shrinkable film on one surface at intervals of 1 cm before lamination, laminating them, Was measured by a method of determining the point spacing of the film.

In the above Examples and Comparative Examples, the shrinkage around the birefringent adhesive force between the film and the shrinkable film (P _a), and then shrinked to measure the adhesive force (P _b) of the birefringent film and the shrinkable film are shown in Table 2 . In this case, the adhesive force (P _a, P _b) is the Texture Analyzer Stable Micro Systems社: was measured using a (model TA-XT Plus) equipment.

division S ₁ S ₂ P _a P _b Example 1 Optical film 1 40% 40% 0.18 0.14 Optical film 2 40% 0.17 0.13 Example 2 Optical film 3 40% 40% 0.18 0.14 Optical film 4 40% 0.17 0.13 Example 3 Optical film 5 40% 40% 0.18 0.14 Optical film 6 40% 0.17 0.13 Example 4 Optical film 7 40% 40% 0.18 0.14 Optical film 8 40% 0.17 0.13 Comparative Example Optical film 9 40% 40% 0.18 0.14 Optical film 10 40% 0.17 0.13

As can be seen from the above Table 2, in the case of the laminate produced in the embodiment of the present invention, both of the birefringent films satisfies the formula (2), and further satisfies the formulas (3) and (4). As a result, in the case of the laminate produced in the example of the present invention, peeling was not easily caused in the heat shrinkage process, and as a result, as shown in FIG. 1 as an example (resin layer omitted), two sheets of the birefringent film (1) and (2) contracted substantially in the same manner as the shrinkable film (3).

On the other hand, in the case of the comparative example, as in the embodiment of the present invention, the laminate was formed using the active energy ray-curable resin layer. As a result, all of the birefringent films satisfied the formula (2) (4) is satisfied.

Experimental Example  3 - Measurement of physical properties of optical film after shrinkage

The width, thickness, and retardation characteristics of the optical films prepared in the above Examples and Comparative Examples were measured and shown in Table 3 below. The thicknesses were measured using a TESA Tesla u-hite thickness gauge. The n _x , n _y , and n _z values were measured using a prism coupler (SPA-3DR, SAIRON TECHNOLOGY) And the phase difference value was measured using Axoscan's Axoscan measuring instrument.

division Width (mm) Thickness (㎛) n _x / n _y / n _z R _in (nm) R _th (nm) Nz Example 1 Optical film 1 1440 31.3 1.5883 / 1.5802 / 1.5841 258 124 0.48 Optical film 2 1440 28.6 1.5885 / 1.5800 / 1.5841 258 124 0.48 Example 2 Optical film 3 1440 30.8 1.5891 / 1.5795 / 1.5839 305 147 0.48 Optical film 4 1440 30.9 1.5891 / 1.5794 / 1.5841 305 147 0.48 Example 3 Optical film 5 1440 30.2 1.5897 / 1.5789 / 1.5840 334 161 0.48 Optical film 6 1440 28.7 1.5897 / 1.5790 / 1.5839 334 161 0.48 Example 4 Optical film 7 1440 30.3 1.5881 / 1.5799 / 1.5846 252 140 0.55 Optical film 8 1440 28.5 1.5884 / 1.5796 / 1.5846 252 140 0.55 Comparative Example Optical film 9 720 31.0 1.5892 / 1.5788 / 1.5846 265 141 0.53 Optical film 10 720 30.5 1.5883 / 1.5799 / 1.5844 251 128 0.51

As shown in Table 3, according to the embodiment of the present invention, the IPS mode liquid crystal display device has a thin thickness of about 30 占 퐉, a width of about 1440 mm, and is sufficiently wide to have a phase difference value It can be seen that two single optical films can be produced.

On the other hand, in the comparative example, it is possible to produce an optical film satisfying the relationship of n _x > n _z > n _y of a thin thickness, but the width of the produced optical film is very narrow, It can be understood that there is a difficulty in this.

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

1, 2: birefringent film
3: shrinkable film
W: Width
L: Length

Claims (20)

Uniaxially stretching the unoriented birefringent film in the transverse direction (TD);
Attaching the stretched birefringent film to a shrinkable film through an active energy ray curable composition to form a laminate; And
And thermally shrinking the laminate in the transverse direction (TD) so that the stretched birefringent film satisfies the following formula (1): " (1) "
Wherein the active energy ray curable composition is a radical curable composition comprising a first compound represented by Formula 1, a second compound comprising at least one carboxyl group, and a radical initiator.
[Chemical Formula 1]

In the above formula (1), R ₁ represents an ester group or an ether group; R ₂ is a C _1-10 alkyl group, a C _4-10 cycloalkyl group, or a combination thereof, wherein R ₂ has at least one hydroxy substituent in the molecule; R ₃ is hydrogen, or a substituted or unsubstituted C _1-10 alkyl group.
Equation (1): n _x > n _z > n _y
In the formula (1), n _x is birefringent, and the plane direction refractive index is the maximum refractive index in the direction of the film, n _y is a refractive index in the direction perpendicular to the n _x direction in the birefringent film, n _z is the birefringence Refractive index in the thickness direction of the film.
The method according to claim 1,
Wherein the stretching is performed so that the width of the birefringent film after stretching becomes 1400 mm to 6000 mm.
The method according to claim 1,
Wherein the stretching is performed such that the thickness of the birefringent film after stretching is 5 占 퐉 to 40 占 퐉.
The method according to claim 1,
Wherein the stretching is performed so that the birefringent film after stretching satisfies the following formula (2).
(2): 0 nm? R _{in (a)} ? 100 nm
In the above formula (2), R _{in (a)} is the retardation value of the birefringent film measured at a wavelength of 550 nm.
The method according to claim 1,
And the stretching step is performed so that the birefringent film after stretching satisfies the following formula (3).
Formula (3): -100 nm? R _{th (a)} ? 100 nm
In the above formula (3), R _{th (a)} is the thickness direction retardation value of the birefringent film measured at a wavelength of 550 nm.
The method according to claim 1,
Wherein the stretching is performed at a temperature of (Tg) to (Tg + 50 deg. C), where Tg is the glass transition temperature of the birefringent film.
The method according to claim 1,
Wherein the stretching step is performed at a stretching magnification of 1.5 to 6.0 times.
The method according to claim 1,
Wherein the step of forming the laminate comprises attaching a shrinkable film to one side or both sides of the stretched birefringent film.
The method according to claim 1,
Wherein the step of forming the laminate comprises attaching a stretched birefringent film on both sides of the shrinkable film.
delete The method according to claim 1,
Wherein the step of heat shrinking the laminate is carried out so as to satisfy the following formula (4).
(4): 0%? S ₂ - S ₁ ? 5%
In the formula (4), S ₁ is a shrinkage ratio in the direction perpendicular to the stretching direction of the birefringent film in the laminated state, and S ₂ is a shrinkage ratio in the direction perpendicular to the stretching direction of the shrinkable film in the laminated state .
The method according to claim 1,
Wherein the step of heat shrinking the laminate is carried out so as to satisfy the following formulas (5) and (6).
(5): 0.10 N / 2 cm? P _a ? 1.0 N / 2 cm
Equation (6): 0.01 N / 2 cm? P _b ? 0.5 N / 2 cm
In the formulas (5) and (6), P _a is the adhesive strength between the birefringent film and the shrinkable film before heat shrinkage, and P _b is the adhesive strength between the birefringent film and the shrinkable film after heat shrinkage.
The method according to claim 1,
Wherein the step of heat shrinking the laminate is performed by a method of uniaxially stretching the laminate in the longitudinal direction (MD).
14. The method of claim 13,
Wherein the stretching is performed at a temperature of (Tg ') to (Tg' + 100 ° C) when the glass transition temperature of the shrinkable film is Tg '.
14. The method of claim 13,
Wherein the stretching is performed at a draw magnification of 1.1 to 3.0 times.
A birefringent film uniaxially stretched in the transverse direction (TD), and
And a shrinkable film attached to the stretched birefringent film through an active energy ray curable composition,
Wherein the birefringent film satisfies the following formula (1)
Wherein the active energy ray curable composition is a radical curable composition comprising a first compound represented by the following Chemical Formula 1, a second compound comprising at least one carboxyl group, and a radical initiator.
[Chemical Formula 1]

In the above formula (1), R ₁ represents an ester group or an ether group; R ₂ is a C _1-10 alkyl group, a C _4-10 cycloalkyl group, or a combination thereof, wherein R ₂ has at least one hydroxy substituent in the molecule; R ₃ is hydrogen, or a substituted or unsubstituted C _1-10 alkyl group.
Equation (1): n _x > n _z > n _y
In the formula (1), n _x is birefringent, and the plane direction refractive index is the maximum refractive index in the direction of the film, n _y is a refractive index in the direction perpendicular to the n _x direction in the birefringent film, n _z is the birefringence Refractive index in the thickness direction of the film.
14. A process for producing a polyurethane foam, which is produced by the process of any one of claims 1 to 9 and 11 to 15,
The optical film satisfies the following formulas (7) to (9).
(7): 150 nm? R _{in (b)} ? 350 nm
(8): 50 nm? R _{th (b)} ? 250 nm
Equation (9): 0.1? Nz _(b) ? 1
In the above formulas (7) to (9), R _{in (b)} is a retardation value of the optical film measured at a wavelength of 550 nm, R _{th (b)} and, Nz _(b) being the ratio (R _th / R _in) of the thickness retardation value on a plane direction retardation value measured at a wavelength of 550nm of the optical film.
18. The method of claim 17,
Wherein the optical film has a width of from 1300 mm to 3500 mm and a thickness of from 10 탆 to 40 탆.
A polarizing plate comprising the optical film of claim 17.
A liquid crystal display device comprising the optical film of claim 17.

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