KR20120008425A - Optical film, manufacturing method thereof, and liquid crystal display device comprising the same - Google Patents

Abstract

PURPOSE: An optical film, a manufacturing method thereof, and a liquid crystal display device including the optical film are provided to be stably used under a hot and humid environment. CONSTITUTION: An optical film includes base materials, a photoreactive polymer, a polyfunctional monomer, photoinitiators, organic solvent, a liquid crystal alignment layer, and a liquid crystal layer. The photoreactive polymer includes at least one component from a group which is made of norbornene photoreactive polymers. A crosslinking reaction can occur between the polyfunctional monomer and the photoreactive polymer. The liquid crystal alignment layer is formed from a liquid crystal alignment layer composite. The ratio of the polyfunctional monomer to the photoreactive polymer is 1:10 to 10:1.

Description

Optical film, a method of manufacturing the same, and a liquid crystal display including the same {OPTICAL FILM, PREPARATION METHOD OF THE SAME, AND LIQUID CRYSTAL DISPLAY COMPRISING THE SAME}

The present invention relates to an optical film, a method for manufacturing the same, and a liquid crystal display including the same, and more particularly, an optical film having an optical property suitable for use as a compensation film in a liquid crystal display for a TN mode, and a method for manufacturing the same. And a liquid crystal display device including the same.

Recently, liquid crystal displays (LCDs), plasma display panels (PDPs), and the like have been widely used in the display field, replacing conventional CRTs. The device is gradually becoming thinner, lighter, and larger in area, and with this trend, researches to improve the uniformity of the screen, the contrast ratio, the viewing angle, and the like are continued to realize higher quality images.

To this end, optical films made of polymer materials such as polarizing films, polarizer protective films, retardation films, plastic substrates, and light guide plates are used for high quality images. In particular, in the case of the liquid crystal display, various colors of compensation films are used to compensate for the color or brightness of the screen depending on the light transmission angle due to the optical anisotropy of the liquid crystal cell.

On the other hand, currently commercially available liquid crystal display devices, according to the arrangement of the liquid crystal molecules in the liquid crystal cell, twisted nematic (TN), super twisted nematic (STN), vertical alignment (VA) And various modes such as in-plane switching (IPS), and since each of the liquid crystal cells has a unique liquid crystal array, the resulting optical anisotropy is also different. Therefore, since the optical properties required for the compensation film for compensating optical anisotropy of these liquid crystal cells are also different, it is necessary to develop an optical film having various optical properties.

Conventionally used compensation films mainly include a stretched film that is largely stretched to a polymer film to impart optical anisotropy, and a liquid crystal film produced by applying a polymerizable liquid crystal compound on a plastic substrate, drying, and irradiating and curing ultraviolet rays. Among them, the liquid crystal film is more preferable than the stretched film in that various optical properties can be realized depending on the shape of the liquid crystal molecules used and the orientation of the liquid crystal.

Generally, a liquid crystal film is manufactured by apply | coating an aligning agent, such as a polyimide or polyvinyl alcohol, on a plastic base material, forming an oriented film, rubbing it in a fixed direction, and then apply | coating and orientating a polymeric liquid crystal compound again. However, when the alignment film is used as described above, since the adhesive strength with the liquid crystal film is insufficient, problems such as peeling or shrinking of the liquid crystal film may occur in a high temperature and high humidity environment. In addition, in the method using rubbing, static electricity, scratch marks, etc. are easily generated due to friction during rubbing, and problems such as generation of fine dust from rubbing cloth or the like cannot be avoided.

Therefore, a non-contact liquid crystal aligning method is researched in an effort to solve the problem of this rubbing method, and the light alignment method which manufactures a liquid crystal aligning film using light irradiation among them is proposed. At this time, the photo-alignment film material for aligning the liquid crystal is by photodimerization reaction of cinnamate group, coumarin group, chalcone group, photoisomerization reaction of polymer including azobenzene group, and photolysis of polyimide polymer Although the reaction and the like have been reported, there is a problem in that thermal stability or light stability is generally weak and contamination by decomposition products may occur.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides an optical film excellent in durability and adhesiveness, and having optical properties suitable for desired optical properties, in particular, a compensation film for a TN mode liquid crystal display device, and a method of manufacturing the same.

To this end, the present invention in one aspect, 1) a substrate, 2) a norbornene-based photoreactive polymer formed on the substrate, a) a cinnamate group, a photoreactive polymer comprising a unit represented by the formula (1), and A photoreactive polymer comprising at least one selected from the group consisting of a photoreactive polymer comprising a unit represented by the following formula (2), b) a polyfunctional monomer capable of crosslinking reaction with the photoreactive polymer, c) a photoinitiator, and d) An optical film comprising an organic solvent, a liquid crystal alignment film formed from a liquid crystal alignment film composition having a ratio of the photoreactive polymer to the polyfunctional monomer in a ratio of 1:10 to 10: 1, and 3) a liquid crystal layer formed on the liquid crystal alignment film. to provide.

[Formula 1]

[Formula 2]

In addition,

1) A group consisting of: a) a norbornene-based photoreactive polymer comprising a cinnamate group, a photoreactive polymer comprising a unit represented by Formula 1, and a photoreactive polymer comprising a unit represented by Formula 2 on a substrate A photoreactive polymer comprising at least one member selected from b) a multifunctional monomer capable of crosslinking with said photoreactive polymer, c) a photoinitiator, and d) an organic solvent, wherein said photopolymer to polyfunctional monomer comprises: After applying and drying the liquid crystal alignment film composition contained in a ratio of 10 to 10: 1, irradiating ultraviolet rays to form a liquid crystal alignment film, and 2) a polymerizable liquid crystal compound, a photoinitiator, and an organic solvent on the liquid crystal alignment film. It provides a method for producing an optical film comprising the step of applying and drying the liquid crystal compound solution containing, and irradiating ultraviolet light.

Moreover, this invention provides the liquid crystal display device containing the said optical film.

The optical film of the present invention is excellent in durability, and can be used stably even in a high temperature and high humidity environment. In addition, the optical film of the present invention can easily implement the desired optical properties by adjusting the tilt angle of the liquid crystal layer by a simple method of controlling the ratio of the photoreactive polymer and the monomer in the alignment film composition.

1 is a graph showing the phase difference value according to the viewing angle of the film produced by Example 1 of the present invention.
Figure 2 is a graph showing the phase difference value according to the viewing angle of the film produced by Example 2 of the present invention.
Figure 3 is a graph showing the phase difference value according to the viewing angle of the film produced by Example 3 of the present invention.
Figure 4 is a graph showing the phase difference value according to the viewing angle of the film produced by Example 4 of the present invention.
Figure 5 is a graph showing the phase difference value according to the viewing angle of the film produced by Example 5 of the present invention.
6 is a view showing a contrast ratio measured by Experimental Example 2. FIG.

Hereinafter, the present invention will be described in detail.

The optical film according to the present invention comprises: 1) a substrate, 2) a norbornene-based photoreactive polymer formed on the substrate, a) a cinnamate group, a photoreactive polymer comprising a unit represented by the following Formula 1, and A photoreactive polymer comprising at least one selected from the group consisting of photoreactive polymers comprising a unit represented by 2, b) a polyfunctional monomer capable of crosslinking reaction with the photoreactive polymer, c) a photoinitiator, and d) an organic solvent And a liquid crystal alignment film formed from a liquid crystal alignment film composition having a ratio of the photoreactive polymer to the polyfunctional monomer in a range of 1:10 to 10: 1, and 3) a liquid crystal layer formed on the liquid crystal alignment film.

In this case, as the substrate 1, a substrate generally used in the technical field may be used, and is not particularly limited. For example, an acryl-based film, a cycloolefin polymer-based film, a triacetyl cellulose-based film, a polycarbonate-based film, or the like can be used, and in consideration of economics, an acryl-based film is preferable.

On the other hand, the acrylic film may include a (meth) acrylic resin. The (meth) acrylic resins may be those known in the art, in particular homo or copolymers of (meth) acrylic monomers; Copolymers of (meth) acrylic monomers and aromatic vinyl monomers; Copolymers of (meth) acrylic monomers, aromatic vinyl monomers and acid anhydrides; Copolymers of a (meth) acrylic monomer and a cyclic monomer can be used.

The (meth) acrylic monomer is sufficient as long as it is a compound having a double bond between the carbonyl group of the ester group and the conjugated (conjugated) carbons, and its substituent is not particularly limited. The (meth) acrylic monomers described herein are meant to include not only acrylates but also acrylate derivatives, and should be understood as concepts including alkylacrylates, alkylmethacrylates, alkylbutacrylates, and the like. For example, examples of the (meth) acrylic monomer include a compound represented by the following formula (11).

In Chemical Formula 11,

R ₁ , R ₂ and R ₃ each independently represent a monovalent hydrocarbon group having 1 to 30 carbon atoms with or without a hydrogen atom or a hetero atom, and at least one of R ₁ , R ₂ and R ₃ may be an epoxy group; R ₄ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

Specifically, the (meth) acrylic monomers include at least one acrylic type selected from the group consisting of methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, methyl methacrylate, and ethyl acrylate. Monomers may be used, in particular the use of methyl methacrylate (MMA) is most preferred.

As the aromatic vinyl monomer, it is preferable to use a monomer having a structure in which a benzene nucleus or vinyl group is substituted or unsubstituted with at least one C ₁ to C ₅ alkyl group or halogen group. For example, one or more styrene monomers selected from the group consisting of styrene, α-methylstyrene, p-methylstyrene, vinyltoluene and the like are preferable.

Carboxylic anhydride can be used as said acid anhydride, and monovalent, divalent or more polyvalent carboxylic anhydride can be used. Preferably, maleic anhydride or a derivative thereof may be used, for example, a compound of formula 12 may be used.

In Chemical Formula 12,

R ₇ and R ₈ each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

As the cyclic monomer, maleic anhydride, maleimide, glutaric anhydride, glutalimide, lactone and lactam or derivatives thereof may be used, and a maleimide monomer is more preferable. The maleimide monomers include, but are not limited to, N-cyclohexylmaleimide, N-phenylmaleimide, N-methylmaleimide, N-butylmaleimide or derivatives thereof, and in particular, N-cyclohexyl Most preferred are maleimides or derivatives thereof. The content of the cyclic monomer in the copolymer of the (meth) acrylic monomer and the cyclic monomer is 1 to 50% by weight, which is advantageous to lower the haze value of the film.

The film containing the (meth) acrylic resin further comprises an aromatic resin having a chain and an aromatic portion having a hydroxyl group-containing portion; Styrene resins; And a copolymer of a styrene monomer and a cyclic monomer.

It is preferable that the number average molecular weights of the aromatic resin which has the chain and aromatic part which have the said hydroxyl group containing part are 1,500-2,000,000 g / mol. It is preferable that the said aromatic resin contains phenoxy clock resin. Here, the phenoxy resin includes a structure in which at least one oxygen radical is bonded to a benzene ring. For example, the aromatic resin having a chain having an hydroxy group-containing portion and an aromatic portion may include at least one unit represented by the following formula (13). The aromatic resin preferably contains 5 to 10,000 units, more preferably 5 to 7,000 units, more preferably 5 to 5,000 units of the formula (13). When the aromatic resin includes two or more units represented by the following formula (13), they may be included in the form of random, alternating or block.

In Chemical Formula 13,

X is a divalent group containing at least one benzene ring, and R is a straight or branched chain alkylene having 1 to 6 carbon atoms.

Specifically, X is preferably a divalent group derived from a compound such as Chemical Formula 14 to Chemical Formula 16, but is not limited thereto.

In Chemical Formula 14

R ¹ is a direct bond, straight or branched alkylene having 1 to 6 carbon atoms, or cycloalkylidene having 3 to 20 carbon atoms,

R ² and R ³ are each independently hydrogen, straight or branched chain alkyl of 1 to 6 carbon atoms, or straight or branched chain alkenyl of 2 to 6 carbon atoms, and n and m are each independently an integer of 1 to 5 to be.

In Chemical Formula 15,

R ⁴ is each independently hydrogen, straight or branched chain alkyl of 1 to 6 carbon atoms, or straight or branched chain alkenyl of 2 to 6 carbon atoms, and p is an integer of 1 to 6;

In Chemical Formula 16,

R ⁶ and R ⁷ are each independently a direct bond, straight or branched alkylene having 1 to 6 carbon atoms, or cycloalkylidene having 3 to 20 carbon atoms,

R ⁵ and R ⁸ are each independently hydrogen, straight or branched chain alkyl of 1 to 6 carbon atoms, or straight or branched chain alkenyl of 2 to 6 carbon atoms, and q and r are each independently an integer of 1 to 5 to be.

Specific examples of the compound represented by Formula 14 to Formula 16 are as follows, but are not limited thereto.

Most preferably, the aromatic resin includes 5 to 10,000 one or more phenoxy clock units represented by the following general formula (17).

The terminal of the anti-aromatic resin may be an OH group.

When the film containing the (meth) acrylic resin includes an aromatic resin having a chain having the hydroxy group-containing portion and an aromatic portion, the content of the (meth) acrylic resin is preferably about 40 to 99% by weight, and about 70 More preferably, the content of the aromatic resin is about 1 to 60% by weight, more preferably about 2 to 30% by weight.

When a copolymer of the styrene monomer and the cyclic monomer is used, the content of the cyclic monomer in the copolymer is about 1 to 99% by weight, preferably about 1 to 70% by weight, more preferably about 5 to 60% by weight.

When the film containing the said (meth) acrylic-type resin contains the said styrene resin or the copolymer of the said styrene monomer and a cyclic monomer with the aromatic resin which has the chain and aromatic part which have the said hydroxyl-group containing part, ( The content of the meta) acrylic resin is preferably about 50 to 99% by weight, more preferably about 75 to 98% by weight, and the content of the aromatic resin is preferably about 0.5 to 40% by weight, and about 1 to about 1. It is more preferable that it is 30% by weight, and the content of the styrene resin or the copolymer of the styrene monomer and the cyclic monomer is preferably about 0.5 to 30% by weight, and more preferably about 1 to 20% by weight.

Next, the liquid crystal aligning film of the optical film which concerns on this invention is demonstrated. The liquid crystal aligning film of this invention is formed on the said base material, and is formed from the liquid crystal aligning film composition containing a) photoreactive polymer, b) polyfunctional monomer c) photoinitiator, and d) organic solvent.

At this time, in the liquid crystal aligning film composition, the ratio of the photoreactive polymer to the polyfunctional monomer is preferably about 1:10 to about 10: 1. When the ratio of the photoreactive polymer and the polyfunctional monomer is within the above range, the substrate adhesion and orientation are excellent. In addition, when the ratio of the photoreactive polymer to the polyfunctional monomer is about 1: 4 to 4: 1, properties particularly suitable for the TN mode compensation film can be obtained.

On the other hand, the photoreactive polymer from the group consisting of a norbornene-based photoreactive polymer containing a cinnamate group, a photoreactive polymer comprising a unit represented by the formula (1), and a photoreactive polymer comprising a unit represented by the formula (2) It is preferable to use one or more selected, and the number average molecular weight is 10,000-500,000.

In addition, the norbornene-based photoreactive polymer including the cinnamate group may include a unit represented by the following formula (3).

In Chemical Formula 3,

n is 50 to 5,000,

At least one of R1 and R2 is represented by the following formula (4),

The remainder is selected from the group consisting of hydrogen, halogen, an alkyl group having 1 to 20 carbon atoms and a group of formula (4),

In Formula 4, R 3 is each independently selected from the group consisting of hydrogen, halogen, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and an allyloxy group.

The norbornene-based photoreactive polymer containing the cinnamate group includes polynorbornene cinnamate, polynorbornene alkoxycinnamate (alkoxy group having 1 to 20 carbon atoms), polynorbornene allylyloxycinnamate, polynorbornene fluorinated cinnamate , Polynorbornene chlorinated cinnamate and polynorbornene dicinnamate may be used any one or more selected from the group consisting of, but is not limited thereto.

In the optical film according to the present invention, the norbornene-based photoreactive polymer including the cinnamate group more preferably includes any one or more of the units represented by the following formulas (5) to (10).

In Chemical Formulas 5 to 10, n is 50 to 5,000.

On the other hand, the content of the photoreactive polymer is preferably 0.1 to 20% by weight, more preferably 0.1 to 10% by weight of the total liquid crystal alignment film composition. If the content is less than 0.1% by weight, the thickness of the film is too small to obtain a good alignment film. If the content is more than 20% by weight, the thickness of the film is excessively difficult to obtain a good alignment film.

In the optical film according to the present invention, the polyfunctional monomer in the 2) liquid crystal alignment layer composition is used together with the photoreactive polymer to induce an additional crosslinking reaction in addition to the dimerization reaction of the photoreactive polymer during ultraviolet irradiation.

The crosslinking reaction includes both the crosslinking reaction in the photoreactive polymer, the crosslinking reaction between the photoreactive polymer and the polyfunctional monomer, and the crosslinking reaction between the photoreactive polymer and the liquid crystal molecules.

When the cinnamate group is irradiated with polarized ultraviolet rays, there is a characteristic of aligning in the vertical direction of the polarized ultraviolet ray, but only a part of the entire cinnamate group is reacted and the rest remains unreacted. In this invention, the method of improving the adhesive force between a base material and a liquid crystal aligning film, a liquid crystal aligning film, and a liquid crystal film utilizes the cinnamate group which remains in the said unreacted state. That is, as the photoinitiator and the polyfunctional monomer are introduced, a crosslinking reaction is induced between the unreacted cinnamate period or the cinnamate group and the multifunctional monomer, and a crosslinking reaction is also induced with the liquid crystal molecules coated on the liquid crystal alignment layer in the future.

In the present specification, the meaning of 'multifunctional' is defined as including two or more functional groups.

The functional group performs a role of a crosslinking reaction and a polymerization reaction by radicals, and the type thereof is not limited as long as it includes a carbon-to-carbon double bond. For example, although an acrylate group is mentioned as a typical functional group, it is not limited to this.

The polyfunctional monomer is preferably a multifunctional monomer containing a functional group (carbon-to-carbon double bond) capable of radical reaction selected from the group consisting of the following structural formula.

Specific examples of the multifunctional monomers include trimethylolpropane triacrylate, pentaerythritol tri (meth) / tetraacrylate, dipentaerythritol hexa / pentaacrylate, triglycerol di (meth) acrylate, tripropylene glycol di (Meth) acrylate, tetraethylene glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, glycerol di (meth) acrylate, 2-hydrate Hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, methoxyethyl (meth) acrylate, N, N-dimethylaminoethyl (methyl) acrylate, butoxytriethylene glycol (meth) acrylic Latex, 2-carboxyethyl acrylate, hydroxypropyl acrylate, mono-2- (acryloyloxy) ethyl succinate, vinyl acrylate, 3- (acryloyl jade ) -2-hydroxypropyl (meth) acrylate, glycerol 1,3-diglycerol diacrylate, tri (propylene glycol) glycerol diacrylate, allyl (meth) acrylate, diacetone acrylamide, (meth ) Acrylamide, methyl 2-acetamidoacrylate, N- [tris (hydroxymethyl) methyl] acrylamide, N, N- (1,2-dihydroxyethylene) bisacrylamide, N, N-methylene Bis (acrylamide), 1,3,5-triacryloylhexahydro-1,3,5-triazine, 2,4,6-triallyloxy-1,3,5-triazine, tris (2 , 3-epoxypropyl) isocyanurate, tris [2- (acryloyloxy) ethyl] isocyanurate, tetracyanoethylene oxide, triallyl 1,3,5-benzenetricapoxylate, diacetone Acrylamide, N, N- (1,2-dihydroxyethylene) bisacrylamide, poly (melamine-co-formaldehyde), 2-carboxyethyl Acrylate, hydroxypropyl acrylate, mono-2- (acryloyloxy) ethyl succinate, vinyl acrylate, 3- (acryloyloxy) -2-hydroxypropyl (meth) acrylate, 2- ( 2-oxo-imidazolidinyl) ethyl (meth) acrylate, caprolactone 2-((meth) acryloyloxy) ethyl ester, mono-2-((meth) acryloyloxy) ethyl maleate, 1 , 2,3-triazole-4,5-dicarboxylic acid, 3-allyloxy-1,2-propanediol, bis [4- (glycidyloxy) phenyl] methane, 2-vinyl-1,3 -Dioxalene, polyurethane acrylate (Cytec, EB1290, UP135, UP111, UP128) and the like may be included one or two or more, but is not limited thereto.

The polyfunctional monomer is more preferably pentaerythritol triacrylate, dipentaerythritol hexaacrylate or tris [2- (acryloyloxy) ethyl] isocyanurate, polyurethane acrylate, but is not limited thereto. It doesn't happen.

The content of the multifunctional monomer is preferably 0.1 to 20% by weight, more preferably 0.1 to 15% by weight of the total liquid crystal alignment film composition. If the content is less than 0.1% by weight, there is no effect of an additional crosslinking reaction, and if the content is more than 20% by weight, the orientation ability is lost.

In the optical film according to the present invention, any of the above 2) liquid crystal alignment film compositions can be used as long as the photoinitiator can induce a radical reaction. For example, the photoinitiator may include, but are not limited to, α-hydroxy ketones, α-amino ketones, phenyl glyoxylates, oxime esters, and the like. In particular, the photoinitiator is preferably an oxime ester.

Oxime ester initiators are useful photoinitiators mainly used in the photoresist process in the color filter layer inside the LCD, and have excellent photosensitivity and high curing efficiency even at low UV irradiation. Therefore, it is useful to form a barrier layer that has a strong durability to prevent the coating material on the surface of the film that is well soluble in various organic solvents, such as acrylic film, and easily eroded, and the oxime ester photoinitiator is used to Help. Therefore, the effect anticipated by using this photoalignment film can eliminate the erosion or inadequate interlayer bonding force portion between the substrate and the liquid crystal anisotropic layer, and induce a stable liquid crystal alignment.

 The content of the photoinitiator is preferably 0.01 to 5% by weight, more preferably 0.01 to 2% by weight of the total liquid crystal alignment film composition. If the content is less than 0.01% by weight, the effect of additional crosslinking reaction cannot be expected, and when the content is more than 5% by weight, the orientation ability is significantly reduced, which is not preferable.

In the optical film according to the present invention, one or two or more organic solvents selected from the group consisting of an ether, an aromatic, a halogen, an olefin, and a ketone may be used as the organic solvent in the 2) liquid crystal alignment layer composition. . More specifically, cyclopentanone, cyclo nucleanone, chlorobenzene, N-methylpyrrolidone, toluene, xylene, mesitylene, cymene, dimethyl sulfoxide, dimethylformamide, chloroform, gamma butyrolactone, tetrahydro Furan etc. can be used, but it is not limited to this.

Next, 3) a liquid crystal layer is demonstrated.

In the optical film according to the present invention, the 3) liquid crystal layer contains a polymerizable liquid crystal compound.

The polymerizable liquid crystal compound may be a nematic liquid crystal that is polymerized with a surrounding liquid crystal monomer by light to form a liquid crystal polymer.

In general, the polymerizable liquid crystal compound is applied in an isotropic state on an alignment film fixed by applying an alignment film composition to an alignment-oriented plastic substrate or a plastic substrate, and then phase-transforms into a liquid crystal having nematic regularity by polymerization during drying and curing. There is a property to be oriented in a specific direction, and therefore the orientation does not change even if another layer is laminated.

In the optical film according to the present invention, it is preferable that the polymerizable liquid crystal compound is one or more materials having an acrylate group polymerizable by photoreaction. Examples of the material having an acrylate group include cyano biphenyl acrylate, cyano phenyl cyclohexane acrylate, cyano phenyl ester acrylate, benzoic acid phenyl ester acrylate, phenyl pyrimidine acrylate, and mixtures thereof. Low molecular liquid crystal which shows a nematic phase at room temperature or high temperature, such as these etc. are mentioned.

Meanwhile, in the present invention, the liquid crystal layer is preferably a splay oriented liquid crystal layer, and in this case, the average tilt angle of the liquid crystal layer is preferably about 20 ° to about 70 °. Here, the average inclination angle is an angle at which one of the splay-aligned liquid crystal molecules forms the base surface is called an inclination angle.

Meanwhile, the average tilt angle of the liquid crystal layer may be adjusted by adjusting the ratio of the photoreactive polymer and the polyfunctional monomer in the liquid crystal alignment layer composition. Increasing the content of the photoreactive polymer and decreasing the content of the polyfunctional monomer results in a decrease in the average tilt angle, decreasing the content of the photoreactive polymer, and increasing the content of the multifunctional monomer results in an increase in the average tilt angle. More specifically, the orientation of the liquid crystal molecules by the photoreactive polymer is due to the pi-pie interaction between the liquid crystal molecules and the material produced by the photoreactive polymer in response to UV light, the amount of UV product of the photoreactive polymer. As a result, the force for fixing the liquid crystal molecules becomes proportional. Therefore, when the amount of the photoreactive polymer on the surface of the alignment layer decreases, the force for fixing the liquid crystal molecules is weakened, and the average inclination angle is increased. In contrast, when the amount of the photoreactive polymer is increased, the force for fixing the liquid crystal molecules becomes stronger, and the average tilt angle is lowered.

The optical film according to the present invention may have characteristics of optical anisotropy, and may be used as a retardation film, a polarizing film protective film, or the like for a liquid crystal display device. On the other hand, the optical film of the present invention preferably has an in-plane retardation value of 20 to 200nm, preferably 20 to 180nm, most preferably about 30 to 150nm, in this case, the optical film of the present invention is a TN mode liquid crystal display It can be usefully used as a compensation film of the device.

In addition, according to the present invention, an optical film having various optical properties can be produced by a simple method of controlling the ratio of the photoreactive polymer and the polyfunctional monomer in the alignment film composition.

Next, the optical film manufacturing method of this invention is demonstrated.

Method for producing an optical film according to the present invention is 1) a photoreactive polymer comprising a) a norbornene-based photoreactive polymer comprising a cinnamate group, a unit represented by the following formula (1), and a formula (2) on a substrate A photoreactive polymer comprising at least one selected from the group consisting of photoreactive polymers comprising units, b) a polyfunctional monomer capable of crosslinking reaction with the photoreactive polymer, c) a photoinitiator, and d) an organic solvent, Applying and drying a liquid crystal alignment layer composition containing the photopolymer to the polyfunctional monomer in a ratio of 1:10 to 10: 1, and then irradiating ultraviolet rays to form a liquid crystal alignment layer, and 2) polymerizing on the liquid crystal alignment layer And applying and drying a liquid crystal compound solution including a crystalline liquid crystal compound, a photoinitiator, and an organic solvent, and irradiating ultraviolet rays.

In the method for manufacturing an optical film according to the present invention, any one of the methods for applying the liquid crystal alignment film composition on the substrate in the step 1) may be used as long as it can be generally performed in the art. At this time, it is preferable to apply | coat the liquid crystal aligning film composition uniformly at the thickness of about 800-5,000 kPa on a base material.

In the step 1), after applying the liquid crystal alignment film composition on the substrate, it may be dried for at least 30 seconds at 25 ~ 150 ℃ to remove the remaining solvent. If the drying temperature is less than 25 ℃ is not dried enough to cause staining or the orientation performance may be degraded under the influence of the remaining solvent, if it exceeds 150 ℃ may cause deformation of the substrate is not preferred.

After drying is completed, orientation can be provided in any desired direction by irradiating the ultraviolet rays linearly polarized in a predetermined direction for 0.5 seconds or more. This allows the photoreactive polymer constituting the liquid crystal alignment film to induce primary molecular orientation in the direction (absorption axis) perpendicular to the transmission axis of the ultraviolet polarizing plate (wire grid polarizing plate) through the dimerization (ring addition) reaction by ultraviolet irradiation. do. Therefore, when adjusting the polarization direction of the irradiated ultraviolet rays, the alignment direction of the alignment film can be adjusted to any desired angle, so that the optical axis of the polymerizable liquid crystal compound applied on the liquid crystal alignment film in the future at any angle with respect to the advancing direction of the substrate. It is possible to adjust.

In the method for producing an optical film according to the present invention, the liquid crystal compound solution of step 2) may be prepared by dissolving a polymerizable liquid crystal compound and a photoinitiator in an organic solvent. The content of the polymerizable liquid crystal compound in the liquid crystal compound solution is not particularly limited, but is preferably 5 to 70 parts by weight, more preferably 5 to 50 parts by weight per 100 parts by weight of the total liquid crystal compound solution. If the content of the polymerizable liquid crystal compound is less than 5 parts by weight, staining may be severe, and if the content of the polymerizable liquid crystal compound is greater than 70 parts by weight, the amount of the solvent may be small to precipitate the polymerizable liquid crystal compound.

The liquid crystal compound solution contains a small amount of photoinitiator. The content of the photoinitiator is preferably 3 to 10 parts by weight per 100 parts by weight of the polymerizable liquid crystal compound in the total liquid crystal compound solution. If the content of the photoinitiator is less than 3 parts by weight, sufficient curing does not occur during ultraviolet irradiation, and if it exceeds 10 parts by weight, the alignment of the liquid crystal may change due to the influence of the photoinitiator.

In addition to the photoinitiator, a chiral agent, a surfactant, a polymerizable monomer, a polymer, and the like may be added to the liquid crystal compound solution as long as the liquid crystal alignment is not prevented.

As the organic solvent in preparing the liquid crystal compound solution, halogenated hydrocarbons such as chloroform, tetrachloroethane, trichloroethylene, tetrachloroethylene and chlorobenzene; Aromatic hydrocarbons such as benzene, toluene, xylene, mesitylene, cymene, methoxy benzene and 1,2-dimethoxybenzene; Ketones such as acetone, methyl ethyl ketone, cyclohexanone and cyclopentanone; Alcohols such as isopropyl alcohol and n-butanol; Cellosolves such as methyl cellosolve, ethyl cellosolve and butyl cellosolve; Etc. may be used, but is not limited thereto, and may be used in the form of a single or a mixture.

After the liquid crystal compound solution is applied onto the liquid crystal alignment film, a drying process is performed. The drying temperature is preferably 25 to 120 ° C., and the drying time is preferably at least 1 minute. The drying temperature is an important factor in the alignment position attitude of the liquid crystal, and when it is out of the temperature range and the time range, it may affect the alignment of the liquid crystal and stains may occur.

After the drying process, the liquid crystal layer oriented on the liquid crystal alignment layer is fixed by polymerization and curing through ultraviolet irradiation. At this time, curing by polymerization is carried out in the presence of a photoinitiator that absorbs the wavelength of the ultraviolet region. Ultraviolet irradiation can be performed in air | atmosphere or in the nitrogen atmosphere which interrupted oxygen in order to improve reaction efficiency. Typically ultraviolet irradiator may be used a medium or high pressure mercury ultraviolet lamp, or a metal halide lamp having an intensity of 80 w / cm or more. In the ultraviolet irradiation, a cold mirror or other cooling device may be provided between the substrate and the ultraviolet lamp so that the surface temperature of the liquid crystal layer is within a temperature range having a liquid crystal state.

In addition, the present invention provides a liquid crystal display device comprising one or two or more optical films.

The optical film which concerns on this invention is used suitably as an optical compensation member for liquid crystal display devices. For example, the optical film of the present invention is a super twist nematic (STN) type LCD, a thin film transistor-twisted nematic (TFT-TN) type LCD, a vertical alignment (VA) type LCD, an in-plane switching (IPS) type. Retardation films such as LCD; Half wave plate; Quarter wave plate; Reverse wavelength dispersion film; Optical compensation films; Color filters; Laminated film with a polarizing plate; The polarizing plate may be used as a compensation film, and among these, may be usefully used as a TN type LCD compensation film.

Hereinafter, preferred examples are provided to aid in understanding the present invention. However, the following examples are merely provided to more easily understand the present invention, and the contents of the present invention are not limited thereto.

Example

≪ Example 1 >

A resin composition obtained by uniformly mixing a poly (N-cyclohexylmaleimide-co-methylmethacrylate) resin and a phenoxy resin at a weight ratio of 85:15 was added to a 16φ extruder in which a nitrogen was substituted from the raw material hopper to the extruder. The raw material pellets were prepared by feeding and melting at 250 ° C.

Phenoxy resin was PKFE (Mw = 60,000, Mn = 16,000, Tg = 98 ° C) from InChemRez®, and poly (N-cyclohexylmaleimide-co-methylmethacrylate) resin was N-cyclone based on NMR analysis. The content of hexylmaleimide was 6.5% by weight.

The obtained raw pellet was vacuum-dried, melted by the extruder at 250 degreeC, and passed through the T-die of a coat hanger type, and the acrylic film of 40 micrometers in thickness was manufactured through the chrome plating casting roll, a drying roll, etc.

As shown in Table 1 below, 5-norbornene-2-methyl- (4-methoxy cinnamate), a photoreactive polymer, dipentaerythritol hexaacrylate, a polyfunctional monomer, and Igacure OXE02 (Switzerland, Ciba-, photoinitiator) Geigy) was dissolved in cyclopentanone at concentrations of 1% by weight, 4% by weight and 0.5% by weight, respectively, and the liquid crystal aligning film coating liquid prepared in the above composition was dried on the acrylic film, and then applied to have a thickness of 1,000 mm 3. And hot air dried for 2 minutes in a 70 degreeC drying oven, and the liquid crystal aligning film was formed.

The liquid crystal alignment layer uses a high pressure mercury lamp of 80 w / cm intensity as a light source, and uses a wire grid polarizer manufactured by Moxtek, to emit polarized ultraviolet light perpendicular to the traveling direction of the substrate at a speed of 3 m / min. Orientation was imparted by ash exposure.

95% by weight of a polymerizable liquid crystal compound (Merck) capable of splay alignment consisting of cyano biphenyl acrylate, cyano phenyl cyclohexane acrylate, and cyano phenyl ester acrylate on the liquid crystal alignment layer, and an igure which is a photoinitiator. A polymerizable liquid crystal compound coating solution prepared by dissolving 907 (Ciba-Geigy, Switzerland) mixed 5 wt% solids in toluene was added to a thickness of 1 micron after drying. After drying for 2 minutes in a 60 ° C. drying oven, a liquid crystal film was produced by irradiating and curing unpolarized ultraviolet light with a high-pressure mercury lamp of 80 w / cm intensity.

Therefore, finally, the optical film laminated | stacked in order of the acrylic film, the liquid crystal aligning film formed on the said acrylic film, and the liquid crystal film formed on the said liquid crystal aligning film was obtained.

Item Weight ratio (%) Alignment film composition solution


menstruum Cyclopentanone 94.5 Alignment film composition

5-norbornene-2-methyl- (4-methoxy cinnamate) One Dipentaerythritol hexaacrylate 4 Igacure OXE02 0.5

<Example 2>

5-cyclonorene-2-methyl- (4-methoxy cinnamate), a photoreactive polymer, dipentaerythritol hexaacrylate, a polyfunctional monomer, and the photoinitiator Igacure OXE02 (Ciba-Geigy, Switzerland) A liquid crystal film was prepared in the same manner as in Example 1, except that the pentanone was dissolved in concentrations of 1.5% by weight, 3% by weight, and 0.5% by weight, respectively.

<Example 3>

5-cyclonorene-2-methyl- (4-methoxy cinnamate), a photoreactive polymer, dipentaerythritol hexaacrylate, a polyfunctional monomer, and the photoinitiator Igacure OXE02 (Ciba-Geigy, Switzerland) A liquid crystal film was prepared in the same manner as in Example 1, except that the pentanone was dissolved in 2.5 wt%, 2.5 wt%, and 0.5 wt% concentrations, respectively.

<Example 4>

5-cyclonorene-2-methyl- (4-methoxy cinnamate), a photoreactive polymer, dipentaerythritol hexaacrylate, a polyfunctional monomer, and the photoinitiator Igacure OXE02 (Ciba-Geigy, Switzerland) A liquid crystal film was prepared in the same manner as in Example 1, except that the pentanone was dissolved in 3 wt%, 1.5 wt%, and 0.5 wt% concentrations, respectively.

Example 5

5-cyclonorene-2-methyl- (4-methoxy cinnamate), a photoreactive polymer, dipentaerythritol hexaacrylate, a polyfunctional monomer, and the photoinitiator Igacure OXE02 (Ciba-Geigy, Switzerland) A liquid crystal film was prepared in the same manner as in Example 1, except that 4 wt%, 1 wt%, and 0.5 wt% of pentanone were dissolved in the concentrations.

Experimental Example 1 Measurement of Average Inclined Angle

After measuring the retardation value according to the viewing angle of the liquid crystal film according to Examples 1 to 5, the average tilt angle was calculated using Merk Equation. In this case, the retardation value was measured using Axoscan (Axometrics, Inc.), and the measurement results are shown in FIGS. 1 to 5. The average tilt angle of each film calculated using the retardation values shown in FIGS. 1 to 5 is as described in Table 2 below.

No. Average tilt angle (°) Example 1 52.3 ° Example 2 39.5 ° Example 3 37.3 ° Example 4 35.4 ° Example 5 30.3 °

From Table 2, it can be seen that by using the optical film of the present invention, by controlling the content of the photopolymerizable polymer and the polyfunctional monomer, an optical film having various average tilt angles can be produced. Thus, by adjusting the average inclination angle of the optical film, by using an optical film suitable for the liquid crystal cell mode and specifications, the compensation effect can be maximized.

Experimental Example 2-Contrast Ratio Measurement

The optical film prepared in Example 1 was twisted 90 degrees filled with a nematic liquid crystal having a cell gap of 4.5 um and a refractive index value of ne = 1.6 and no = 1.5 measured by wavelength light of 550 nm. After mounting to the TN-LCD), the contrast ratio for the viewing angle range of the inclination angle of 0 ° to 80 ° and the east angle of 0 ° to 360 ° was measured. The measurement results are shown in FIG.

As shown in FIG. 6, when the optical film of Example 1 is used, the contrast ratio value is improved at an inclination angle, and the contrast ratio is 10: 1 or more at all viewing angles (inclination angle 0 to 80 degrees and east angle 0 to 360 degrees). It can be seen that excellent.

Claims (29)

1) description,
2) a norbornene-based photoreactive polymer formed on the substrate and comprising a) a cinnamate group, a photoreactive polymer comprising a unit represented by the following formula (1), and a photoreactive polymer comprising a unit represented by the following formula (2) A photoreactive polymer comprising at least one member selected from the group consisting of: b) a polyfunctional monomer capable of crosslinking reaction with the photoreactive polymer, c) a photoinitiator, and d) an organic solvent,
A liquid crystal alignment film formed from the liquid crystal alignment film composition having a ratio of the photoreactive polymer to the polyfunctional monomer in a ratio of 1:10 to 10: 1, and
3) an optical film comprising a liquid crystal layer formed on the liquid crystal alignment film:
[Formula 1]

(2)

The method of claim 1,
Said 1) the base material is at least one optical film selected from the group consisting of an acrylic film, a cycloolefin polymer film, a triacetyl cellulose film, and a polycarbonate film.
The method of claim 1,
The said 1) base material is an optical film characterized by the above-mentioned acrylic film.
The method of claim 3,
The said acryl-type film contains (meth) acrylic-type resin, The optical film characterized by the above-mentioned.
The method of claim 4, wherein
The (meth) acrylic resin may be a homo or copolymer of a (meth) acrylic monomer; Copolymers of (meth) acrylic monomers and aromatic vinyl monomers; Copolymers of (meth) acrylic monomers, aromatic vinyl monomers and acid anhydrides; And (meth) acrylic monomers and copolymers of cyclic monomers.
The method of claim 3,
The acrylic film is an aromatic resin having a chain having an hydroxyl group-containing portion and an aromatic portion; Styrene resins; And at least one member selected from the group consisting of a copolymer of a styrene monomer and a cyclic monomer.
The method of claim 1,
The a) photoreactive polymer is an optical film, characterized in that the number average molecular weight of 10,000 to 500,000.
The method of claim 1,
Norbornene-based photoreactive polymer comprising the cinnamate group is an optical film comprising a unit represented by the following formula (3):
(3)

In Chemical Formula 3,
n is 50 to 5,000,
At least one of R1 and R2 is represented by the following formula (4),
The remainder is selected from the group consisting of hydrogen, halogen, an alkyl group having 1 to 20 carbon atoms and a group of formula (4),
[Chemical Formula 4]

In Formula 4, R 3 is each independently selected from the group consisting of hydrogen, halogen, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and an allyloxy group.
The method of claim 1,
The norbornene-based photoreactive polymer comprising the cinnamate group includes polynorbornene cinnamate, polynorbornene alkoxycinnamate (alkoxy group having 1 to 20 carbon atoms), polynorbornene allylyloxycinnamate, polynorbornene fluorinated cinnamate, An optical film comprising at least one member selected from the group consisting of polynorbornene chlorinated cinnamate and polynorbornene discinnamate.
The method of claim 1,
The norbornene-based photoreactive polymer comprising the cinnamate group is an optical film comprising at least one selected from the units represented by the following formulas (5) to (10):
[Chemical Formula 5]

[Formula 6]

[Formula 7]

[Chemical Formula 8]

[Formula 9]

[Formula 10]

In Chemical Formulas 5 to 10, n is 50 to 5,000.
The method of claim 1,
The content of the a) photoreactive polymer is an optical film, characterized in that 0.1 to 20% by weight of the total liquid crystal alignment film composition.
The method of claim 1,
The b) the polyfunctional monomer is an optical film, characterized in that the polyfunctional monomer comprising a functional group capable of radical reaction selected from the group consisting of the following structural formula:

The method of claim 1,
B) The polyfunctional monomers include trimethylolpropane triacrylate, pentaerythritol tri (meth) / tetraacrylate, dipentaerythritol hexa / pentaacrylate, triglycerol di (meth) acrylate, tripropylene glycol di ( Meta) acrylate, tetraethylene glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, glycerol di (meth) acrylate, 2-hydroxy Ethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, methoxyethyl (meth) acrylate, N, N-dimethylaminoethyl (methyl) acrylate, butoxytriethylene glycol (meth) acrylate , 2-carboxyethyl acrylate, hydroxypropyl acrylate, mono-2- (acryloyloxy) ethyl succinate, vinyl acrylate, 3- (acryloyloxy) -2-hydroxy Lofil (meth) acrylate, glycerol 1,3-diglycerol diacrylate, tri (propylene glycol) glycerol diacrylate, allyl (meth) acrylate, diacetone acrylamide, (meth) acrylamide, methyl 2 Acetamidoacrylate, N- [tris (hydroxymethyl) methyl] acrylamide, N, N- (1,2-dihydroxyethylene) bisacrylamide, N, N-methylenebis (acrylamide), 1,3,5-triacryloylhexahydro-1,3,5-triazine, 2,4,6-triallyloxy-1,3,5-triazine, tris (2,3-epoxypropyl) Isocyanurate, tris [2- (acryloyloxy) ethyl] isocyanurate, tetracyanoethylene oxide, triallyl 1,3,5-benzenetricapoxylate, diacetone acrylamide, N, N -(1,2-dihydroxyethylene) bisacrylamide, poly (melamine-co-formaldehyde), 2-carboxyethyl acrylate, Doxypropyl acrylate, mono-2- (acryloyloxy) ethyl succinate, vinyl acrylate, 3- (acryloyloxy) -2-hydroxypropyl (meth) acrylate, 2- (2-oxo Imidazolidinyl) ethyl (meth) acrylate, caprolactone 2-((meth) acryloyloxy) ethyl ester, mono-2-((meth) acryloyloxy) ethyl maleate, 1,2, 3-triazole-4,5-dicarboxylic acid, 3-allyloxy-1,2-propanediol, bis [4- (glycidyloxy) phenyl] methane, and 2-vinyl-1,3,- Optical film comprising at least one selected from the group consisting of dioxalene, polyurethane acrylate (Cytec, EB1290, UP135, UP111, UP128).
The method of claim 1,
The content of the b) polyfunctional monomer is an optical film, characterized in that 0.1 to 20% by weight of the total liquid crystal alignment film composition.
The method of claim 1,
The content of the c) photoinitiator is an optical film, characterized in that 0.01 to 5% by weight of the total liquid crystal alignment film composition.
The method of claim 1,
The d) organic solvent is an optical film, characterized in that it comprises at least one selected from the group consisting of ether, aromatic, halogen, olefin, and ketone.
The method of claim 1,
Said 3) liquid crystal layer contains the polymeric liquid crystal compound of a nematic liquid crystal, The optical film characterized by the above-mentioned.
The method of claim 1,
3) The liquid crystal layer is a cyano biphenyl acrylate, cyano phenyl cyclohexane acrylate, cyano phenyl ester acrylate, benzoic acid phenyl ester acrylate, phenyl pyrimidine acrylate, and mixtures thereof An optical film comprising a polymerizable liquid crystal compound selected from the group consisting of.
The method of claim 1,
And said liquid crystal layer is splay oriented.
The method of claim 1,
The average tilt angle of the liquid crystal layer is 20 ° to 70 ° characterized in that the optical film.
The method of claim 1,
The optical film has an in-plane retardation value of 30 to 150 nm.
The method of claim 1,
The optical film is a compensation film for a TN mode liquid crystal display device.
1) a group consisting of a) a norbornene-based photoreactive polymer comprising a cinnamate group, a photoreactive polymer comprising a unit represented by the following formula (1), and a photoreactive polymer comprising a unit represented by the following formula (2) on a substrate A photoreactive polymer comprising at least one selected from b) a multifunctional monomer capable of crosslinking with said photoreactive polymer, c) a photoinitiator, and d) an organic solvent,
Applying and drying the liquid crystal alignment layer composition containing the photopolymer to the polyfunctional monomer in a ratio of 1:10 to 10: 1, and then irradiating ultraviolet rays to form a liquid crystal alignment layer, and
2) a method of manufacturing an optical film, comprising applying and drying a liquid crystal compound solution including a polymerizable liquid crystal compound, a photoinitiator, and an organic solvent on the liquid crystal alignment layer, and then irradiating ultraviolet rays.
[Formula 1]

(2)

The method of claim 23, wherein
The thickness of the liquid crystal aligning film of said 1) step is 800-5,000 kPa, The manufacturing method of the optical film characterized by the above-mentioned.
The method of claim 23, wherein
The content of the polymerizable liquid crystal compound of step 2) is a manufacturing method of the optical film, characterized in that 5 to 70 parts by weight per 100 parts by weight of the total liquid crystal compound solution.
The method of claim 23, wherein
The content of the photoinitiator of step 2) is an optical film manufacturing method, characterized in that 3 to 10 parts by weight per 100 parts by weight of the polymerizable liquid crystal compound.
The method of claim 23, wherein
The organic solvent of step 2) is an optical film production method comprising at least one selected from the group consisting of halogenated hydrocarbons, aromatic hydrocarbons, ketones, alcohols, and cellosolves.
A liquid crystal display device comprising one or two or more of the optical film of claim 1.
29. The liquid crystal display device according to claim 28, wherein the liquid crystal display device is in a TN mode.

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