KR100936518B1 - Curable composition for liquid crystal display and liquid crystal display comprising barrier rib and alignment layer manufactured using the same - Google Patents

Abstract

PURPOSE: A curable composition for a liquid crystal display and the liquid crystal display comprising a barrier rib and an alignment layer manufactured using the same are provided to remove a problem that liquid crystal alignment is distorted on an interface of a liquid crystal area and a polymer barrier rib, thereby improving liquid crystal display features. CONSTITUTION: A unit structure compound composed of a curable composition includes an oligomer P, a connection part Y, and a functional group A. The oligomer P keeps viscosity of a composition. The oligomer P keeps a material property of a barrier rib after curing. The connection part Y connects the oligomer and a functional group A. In the functional group A, photo curing or a thermosetting reaction is possible. The functional group A includes a chemical structure having a conjugated structure similar to the structure of a liquid crystal. When a polarized light ultraviolet ray is applied, the functional group A has an anisotropy chemical structure inside a curable material.

Description

A curable composition for a liquid crystal display and a liquid crystal display including a partition and an alignment layer manufactured using the same.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display including a curable composition for a liquid crystal display and a partition wall and an alignment layer manufactured using the same, and more particularly, to a partition structure for maintaining a gap of cells for each pixel in a flexible liquid crystal display device. The present invention relates to a curable composition for a liquid crystal display that improves liquid crystal display characteristics by solving a problem that liquid crystal alignment is disturbed at an interface between a polymer partition and a liquid crystal region, and a liquid crystal display including a partition and an alignment layer manufactured using the same.

Liquid crystal display technology continues to evolve and rapidly replace the existing cathode ray tube-based display market, and is widely used to manufacture display devices for various information devices such as computer monitors, laptop display devices, and televisions. . In addition, in recent years, much research has been made on flexible display technology based on flexible plastic substrates instead of glass substrates. Such flexible display devices are in the spotlight as next generation display devices to replace display devices based on current glass substrates.

In the case of a flexible liquid crystal display device, since a flexible plastic substrate is used, a cell gap, which is a gap between the substrates, may not be uniformly maintained due to the bending of the substrate, thereby causing distortion of the liquid crystal display characteristics.

In order to solve this problem, it is necessary to introduce a barrier rib structure for maintaining a cell gap for each pixel. The manufacturing method of the liquid crystal display device including the barrier rib structure can be divided into two methods of forming the barrier ribs after forming the barrier ribs and forming the barrier ribs after the substrates are bonded.

In the former case, a barrier rib having a desired shape can be formed, but the barrier rib forming process is complicated and the process is long. Thus, the latter method of forming the barrier rib after bonding the substrates has been proposed to overcome the disadvantage.

In the latter method, when a mixture of the ultraviolet curing compound and the liquid crystal is injected between the substrates and the ultraviolet rays are irradiated only on the portion where the barrier ribs are to be formed, the curing reaction proceeds only in the region where the ultraviolet rays are irradiated, thereby forming the polymer barrier walls and the liquid crystals on the remaining portions. Take this principle that exists. However, this method has a problem in that the liquid crystal alignment at the interface between the polymer barrier and the liquid crystal region is disturbed by the polymer barrier and distortion of the liquid crystal display characteristics at the interface occurs.

Therefore, in order to remove the poor liquid crystal alignment appearing at the interface between the polymer barrier and the liquid crystal region in a flexible liquid crystal display having a conventional barrier rib structure, it is necessary to adjust the physical properties of the UV curable composition to control the interaction between the barrier rib and the liquid crystal at the interface. This is emerging.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide chemical structural anisotropy to the partition structure of a conventional flexible liquid crystal display device, thereby achieving liquid crystal molecular control at the interface between the partition wall and the liquid crystal region. The present invention provides a curable composition for a liquid crystal display capable of improving liquid crystal display characteristics by solving a problem occurring between a barrier rib and a liquid crystal.

In addition, another object of the present invention is to provide a liquid crystal display comprising a barrier rib and an alignment film manufactured by using the curable composition for a liquid crystal display.

In order to achieve the above object, in one aspect of the present invention provides a curable composition for a liquid crystal display comprising an oligomer containing a functional group capable of photocuring at least one oligomer end.

In general, the conventional curable composition used in the liquid crystal display is a photocuring reaction occurs when irradiated with light in the ultraviolet wavelength band to form a crosslinked structure. Due to the crosslinked structure, the cured composition has an appropriate level of mechanical strength and has excellent transmittance in the visible region, and thus can be utilized as a partition of a flexible liquid crystal display device.

In the present invention, in order to solve the problem that the liquid crystal alignment at the interface between the liquid crystal and the barrier rib is poor in the conventional flexible liquid crystal display device having a barrier rib structure, an oligomer including a functional group capable of photocuring at least one oligomer terminal as a curable compound forming the barrier rib By using it is possible to control the interaction with the liquid crystal.

Here, the photocurable functional group is a functional group based on a photodimer reactive compound which is capable of curing reaction by irradiation with ultraviolet rays and has a conjugated structure similar to that after contracting, for example, cinnamate and chalcone. Photocurable functional groups such as), coumarin and derivatives thereof.

When a curable composition comprising an oligomer containing a photocurable functional group is irradiated with ultraviolet rays to at least one end of the oligomer, the photocurable functional group contained in the composition is a result of the photodimerization reaction by the ultraviolet irradiation. As a result, only a molecule in a specific direction is reacted to form a crosslinked cured product which chemically generates optical anisotropy. In this case, unlike the conventional curable compound, the barrier ribs have chemical structural anisotropy, so that the barrier ribs can interact with the liquid crystal and the alignment of the liquid crystal molecules can be controlled through such interactions. You can see the effects that can be solved.

The curable composition according to the present invention comprises an oligomer represented by the following formula (1):

Wherein P is a substituted or unsubstituted C ₂ -C ₂₀ alkylene group or a substituted or unsubstituted C ₂ -C ₂₀ heteroalkylene group, A is a group consisting of cinnamate, coumarin, chalcone and derivatives thereof And Y may be selected from the group consisting of carbonyl, amide, thioester, sulfoxide and phenyl groups or absent.

As can be seen in Formula 1, the unit structure compound constituting the curable composition according to the present invention is an oligomer P, connecting portion Y connecting the oligomer and the functional group A to maintain the viscosity of the composition and to maintain the physical properties of the partition after curing And, when irradiated with polarized ultraviolet rays including a chemical structure capable of photocuring or thermosetting reaction and having a conjugated structure similar to that of the liquid crystal has an anisotropic chemical structure inside the cured product to enable interaction with the liquid crystal It consists of functional group A.

Here, oligomer P is a substituted or unsubstituted C ₂ -C ₂₀ alkylene group or a substituted or unsubstituted C ₂ -C ₂₀ heteroalkylene group. The number average molecular weight is about 300 to 3000, and the number of repeat units is controlled. Through the control of the molecular weight is possible. That is, the viscosity of the curable compound and the physical properties of the partition after curing can be adjusted according to the change in the number of repeating units of P.

According to one embodiment, The oligomer P may be selected from Formula 2 below.

In the formula, n is an integer of 1 to 10, R is selected from the following formula (3).

Wherein X is -H, -F, -CN, -CF ₃ or -C _m H _{2m +1} (m is an integer from 1 to 6).

In Formula 1, the linking group Y connecting the oligomer P and the photocurable functional group A is selected from the group consisting of carbonyl, amide, thioester, sulfoxide, and phenyl groups. May not exist.

The functional group A capable of photocuring or thermosetting reaction in Chemical Formula 1 is selected based on a photodimeric reactive compound capable of curing reaction by ultraviolet irradiation and having a conjugated structure similar to liquid crystal after curing. Cinnamate, chalcone, coumarin and derivatives thereof, including but not limited to.

As a specific example, functional group A may be selected from Formula 4 below:

In the above formula, R is -H, -F, -CN, -CF ₃ or -C _m H _{2m +1} (m is an integer of 1 to 6).

For example, in the case of cinnamate, which is a representative structure among photoreactive functional groups, when irradiated with polarized ultraviolet rays, cinnamate functional groups arranged in parallel with the polarization axis preferentially absorb ultraviolet energy as shown in Reaction Scheme (a) below. The photodimerization reaction proceeds predominantly, and the arrangement of the photodimers thus formed has a directivity as shown in the following Reaction Scheme (b). That is, the formed photodimer includes a structure in which a benzene ring and a butane ring are connected in a straight line at the center thereof, and since the chemical structure is similar to the ring structure included in the liquid crystal molecule, the alignment of the liquid crystal is induced through interaction with the liquid crystal. can do. Therefore, the alignment of the liquid crystal is possible by the photodimer formed perpendicular to the polarization direction.

The curable composition according to the present invention may be used alone with the oligomer, and in some cases, various additives may be used. To adjust the viscosity, conventional solvents or viscosity increasing agents may be added, and various compounds used in general-purpose curable compositions such as acrylic monomers, epoxy monomers, and other resins to control the mechanical properties of the cured product or to control the curing properties. Can be added. In this case, it is possible to prepare a curable composition by mixing the respective components according to the appropriate composition ratio and then stirred uniformly.

In addition, another aspect of the present invention provides a liquid crystal display including a partition wall and an alignment layer manufactured using the curable composition.

The method for manufacturing a liquid crystal display according to the present invention is the same as the method for manufacturing a liquid crystal display including a partition known in the art, and there is a difference only in the polarization state of ultraviolet rays irradiated when the partition is formed. Therefore, the curable composition of the present invention can be directly applied to the manufacture of a liquid crystal display including a known barrier rib structure.

As known in the art, various barrier rib structures may be formed by controlling a mask pattern or irradiation energy during ultraviolet irradiation, and in this case, chemical structural anisotropy may be imparted to the barrier ribs formed. One of such methods is known, in which a thin film polymer layer is formed between a substrate and a liquid crystal when ultraviolet rays of low intensity are irradiated to the mixture of the liquid crystal and the curable compound without using a mask. In this case, when the curable compound of the present invention is used, chemical structure anisotropy can be formed on the thin film polymer layer, so that the alignment function of the liquid crystal can be added to the surface of the polymer layer, so that the alignment film material can be omitted.

According to an embodiment of the present invention, in the case of the partition of the liquid crystal cell used in the liquid crystal display, by curing the mixture of the curable composition and the liquid crystal molecules described above, the pixels of the liquid crystal display is separated by the phase separation phenomenon of the curable composition and the liquid crystal molecules A partition can be manufactured. Here, the curable composition is bonded to each other through ultraviolet curing to form a partition. More specifically, after injecting a mixture of the curable composition and the liquid crystal into the cell gap of the liquid crystal and irradiated with polarized ultraviolet rays to the portion to form the partition wall, the curable compound is moved to the partition wall position and the curing reaction proceeds to form a polymer partition wall. do.

Moreover, in the case of the liquid crystal aligning film used for a liquid crystal display, it can manufacture by hardening the curable composition mentioned above. After coating the curable composition on a substrate, the liquid crystal alignment layer may be manufactured to have chemical structural anisotropy inside the thin film by forming a polymer thin film by bonding to each other through UV curing.

The substrate used when manufacturing the liquid crystal display may be a glass or plastic substrate, and the material of the plastic substrate may be polyethersulfone, polycarbonate, polyester, polyetherimide, Polyimide, polyetheretherketon, polyethylene terephthalate and the like are used.

By using the curable composition for a liquid crystal display of the present invention as described above, in the fabrication of a barrier rib structure for maintaining the gap of the cells for each pixel in a conventional flexible liquid crystal display device, at the interface between the polymer barrier and the liquid crystal region The problem that the liquid crystal alignment is disturbed can be solved, thereby improving the liquid crystal display characteristics.

In addition, since the liquid crystal alignment layer can be formed in addition to the partition wall by changing the photocuring method, the partition wall and the alignment layer can be integrated in the display element. If the present technology is applied to a conventional flexible liquid crystal display device, it is possible to remove the alignment layer, which is one of the main components, thereby reducing the material cost and simplifying the process.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention.

Therefore, the configuration shown in the drawings and the embodiments described herein are only one of the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

Example

< Production Example >: Photocurable Oligomer  Produce

Preparation Example 1 1,6- hexanediyl DC cinnamoyl ether (1,6- Hexanediyl Preparation of dicinnamoyl ether) (2 Ci - HD )

First, 80 ml of THF solvent was added to the reactor, followed by 2 g of 1,6-hexanediol (HD) with an oligomer structure P and 5.64 g of cinnamoyl chloride as a photoreactive functional group. Was dissolved and a small amount of thionyl chloride was added as a catalyst, followed by stirring at room temperature for 24 hours. After the reaction proceeded, the reaction mixture was slowly cooled to room temperature, poured into 200 mL of methanol, and the precipitate was filtered and washed with 1-2 L of water. After drying at room temperature to obtain a 1,6-hexanediyl dicinnamoyl ether (1,6-Hexanediyl dicinnamoyl ether) (2Ci-HD) of the photocurable oligomer of the formula. Yield was 2.95 g (38.6%). Nuclear magnetic resonance spectrum data of the formula is as follows.

¹ H-NMR (CDCl ₃ solvent) δ = 7.7 (d, 1H, Ar—C H = CH—), 6.5 (d, H, Ar—CH═C H −), 4.2 (s, 2H, —C H 2-O-), 1.7 (s, 2H, -C H 2-CH2-O-), 1.5 (s, 2H, -CH2-CH2-C H 2-CH2-CH2-)

Preparation Example 2 1,10- decanediyl Preparation of-cinnamoyl-dish ether (1,10- decanediyl dicinnamoyl ether) (DD 2 Ci)

Synthesis was carried out in the same manner as in Production Example 1, except that 1,10-decanediol (DD) was used as the oligomer structure P. 60 ml of THF, 2 g of 1,10-decanediol, 3.82 g of cinnamoyl chloride and thionyl chloride were added to the reactor, and the mixture was stirred at room temperature for 24 hours. After the reaction proceeded, the reaction mixture was slowly cooled to room temperature, poured into 200 mL of methanol, and the precipitate was filtered and washed with 1-2 L of water. After drying at room temperature to synthesize the 1,10-decanediyl dicinnamoyl ether (1,10-decanediyl dicinnamoyl ether) (2Ci-DD) of the formula. The yield was 2.10 g (36.1%). Nuclear magnetic resonance spectrum data of the formula is as follows.

¹ H-NMR (CDCl ₃ solvent) δ = 7.7 (d, 1H, Ar—C H = CH—), 6.5 (d, H, Ar—CH═C H −), 4.2 (s, 2H, —C H 2-O-), 1.7 (s, 2H, -C H 2-CH2-O-), 1.4 (s, 2H, -C H 2-CH2-CH2-O-), 1.3 (s, 4H, -CH2 -CH2-CH2-C H 2-C H 2-CH2-CH2-)

< Experimental Example >: Of the present invention Photocurable Oligomer  Compatibility test for liquid crystal display elements of the composition to include

< Experimental Example  1>: UV  Investigation of Absorption Spectrum Change

After diluting the photocurable oligomer prepared in Preparation Examples 1 and 2 to 2% by weight in a cyclohexanone solvent and spin coating a quartz substrate, the thin film was prepared and then UV (intensity: 0.0, 0.5, 1.2 and 2.4 J / cm ² ) was measured by using a UV spectrophotometer to measure the photoreaction properties are shown in Figure 1 the results.

In both types of curable oligomers, the absorption spectrum near 284 nm, which is the absorption wavelength band of cinnamate functional groups, gradually decreases when irradiated with ultraviolet rays, which can be interpreted as the cinnamate functional groups cause photodimer reactions by ultraviolet rays.

< Experimental Example  2>: investigation of liquid crystal alignment characteristics of the liquid crystal alignment film

In addition, after diluting the photocurable oligomer prepared in Preparation Examples 1 and 2 to 2% by weight in a cyclohexanone solvent and spin-coated the glass substrate to prepare a thin film, the liquid crystal alignment layer was irradiated with polarized ultraviolet rays. Prepared. The glass substrates coated with the prepared liquid crystal alignment layer were bonded to each other by maintaining an empty gap of 8 μm, and then heated to 80 ° C., and then the liquid crystal E7 containing 0.2 wt% of disperse dye 14 in the space. After injecting and cooling to room temperature, a liquid crystal cell was produced. The prepared liquid crystal cell was heat-treated for 10 minutes at a predetermined temperature (not heated, 150 ° C. heating and 200 ° C. heating), and then absorbance of the dye according to the rotation angle of the liquid crystal cell in polarized state was measured and the results are shown in FIG. 2. .

In Figure 2, the difference in absorbance according to the rotation angle is a result of the dye arrangement according to the alignment of the liquid crystal, through which the photocurable oligomers of Preparation Examples 1 and 2 used in the present experiment shows the orientation of the liquid crystal Confirmed.

Through this, it was found that the photocurable oligomers prepared according to Preparation Examples 1 and 2 can be applied to the liquid crystal alignment layer material.

1 shows the state of UV absorption spectrum change of a photocurable composition according to the present invention according to ultraviolet irradiation (a) 1,6-hexanediyl dicinamoyl ether (2Ci-HD) and (b) 1,10-decanediyl dish Shown for namoyl ether (2Ci-DD) respectively;

Figure 2 shows the liquid crystal alignment characteristics of the liquid crystal alignment film prepared by irradiating the polarized ultraviolet ray to the photocurable composition according to the present invention (a) 1,6-hexanediyl dicinamoyl ether (2Ci-HD) and (b) 1, Shown for 10-decanediyl dicinamoyl ether (2Ci-DD) respectively.

Claims (11)

delete delete delete delete Curable composition for a liquid crystal display, characterized in that represented by the following formula (1): [Formula 1]

Wherein P is a substituted or unsubstituted C ₂ -C ₂₀ alkylene group or a substituted or unsubstituted C ₂ -C ₂₀ heteroalkylene group, A is a group consisting of cinnamate, coumarin, chalcone and derivatives thereof And Y may be selected from the group consisting of carbonyl, amide, thioester, sulfoxide and phenyl groups or absent. The method of claim 5, In Formula 1, P is a curable composition for a liquid crystal display, characterized in that selected from Formula 2 below: [Formula 2]

In the formula, n is an integer of 1 to 10, R is selected from the following formula (3). [Formula 3]

(Where X is -H, -F, -CN, -CF ₃ or -C _m H _{2m +1} (m is an integer from 1 to 6).) The method of claim 5, A in the general formula (1) is a curable composition for a liquid crystal display, characterized in that selected from the following formula (4): [Formula 4]

In the above formula, R is -H, -F, -CN, -CF ₃ or -C _m H _{2m +1} (m is an integer of 1 to 6). The curable composition for a liquid crystal display of claim 7, wherein A is 1,6-hexanediyl dicinnamoyl ether (1,6-Hexanediyl dicinnamoyl ether). The curable composition for a liquid crystal display according to claim 7, wherein A is 1,10-decanediyl dicinnamoyl ether (1,10-decanediyl dicinnamoyl ether). 10. A liquid crystal display comprising partitions made by curing the mixture of the curable composition of claim 5 and liquid crystal molecules. The liquid crystal display containing the liquid crystal aligning film manufactured by hardening | curing the curable composition of any one of Claims 5-9.

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