KR102712598B1 - Substrate, Liquid Crystal Display Device Including The Same And Method Of Fabricating The Same - Google Patents

Abstract

The present invention provides a substrate for a liquid crystal display device, comprising: a substrate; and an alignment film disposed on an upper portion of the substrate and made of an alignment material including a first alignment portion, a second alignment portion, a photodecomposition portion, and a photopolymerization portion.

Description

Substrate, liquid crystal display device including the same, and method of fabricating the same {Substrate, liquid crystal display device including the same, and method of fabricating the same}

The present invention relates to a substrate, and more particularly, to a substrate including an alignment film having improved hardness and alignment power, a liquid crystal display device including the same, and a manufacturing method thereof.

Recently, as the era has rapidly advanced into the information society, the display field that processes and displays large amounts of information has developed, and the need for flat panel displays has arisen to respond to the needs of the times, such as thinness, weight reduction, and low power consumption.

Accordingly, a thin film transistor liquid crystal display (TFT-LCD) with excellent color reproducibility and a thin form factor was developed. The liquid crystal display displays images by utilizing the optical anisotropy and polarization properties of liquid crystal molecules.

Liquid crystal displays include an alignment film to initially align the liquid crystal layer, and the alignment film is formed through a rubbing process or a photoalignment process.

The photoalignment process, which has advantages in terms of visual characteristics, includes a printing step of an alignment material layer, a firing step, an ultraviolet irradiation step, and a post-firing step. In the firing step, imidization of the alignment material progresses, and in the ultraviolet irradiation step, the alignment material layer becomes anisotropic.

Recently, in order to improve the hardness of the alignment film, a crosslinking additive is added to the alignment material to form an alignment material layer. The crosslinking additive can improve the hardness of the alignment material layer by forming a polymer network between the alignment materials.

However, in an alignment film using an alignment material with added crosslinking additives, as the amount of crosslinking additives increases, the hardness of the alignment film increases, but there is a problem in that the unreacted crosslinking additives increase, causing alignment defects.

In addition, the polymer network by the crosslinking additive is formed by the heat of the sintering step, and since a portion of the total heat supplied in the sintering step is not used for imidization but for polymer network formation, there is a problem that as the amount of crosslinking additive added increases, the imidization rate decreases and the orientation force decreases.

In addition, in a double-layer alignment film with different resistivity and orientation, there is a problem in that the polymer network formation is concentrated in the lower layer than in the upper layer, which has weaker hardness, and thus the efficiency of improving hardness is reduced.

Accordingly, there is a problem of defects such as afterimages occurring in liquid crystal displays including alignment films using alignment materials with cross-linking additives added.

The present invention has been proposed to solve such problems, and the purpose of the present invention is to provide a substrate in which alignment defects are prevented and hardness and alignment power are improved by forming an alignment film using an alignment material in which a photopolymerization unit is introduced into at least one side chain of an alignment unit and a photodecomposition unit, a liquid crystal display device including the same, and a manufacturing method thereof.

Another object of the present invention is to provide a substrate in which alignment defects are prevented and the hardness and alignment force of the upper layer of the alignment film are improved by forming the upper layer or the upper and lower layers of the alignment film using an alignment material having a photopolymerization unit introduced into the side chain of at least one of an alignment unit and a photodecomposition unit, a liquid crystal display device including the same, and a manufacturing method thereof.

To solve the above problem, the present invention provides a substrate for a liquid crystal display device, including a substrate; and an alignment film disposed on the upper portion of the substrate and made of an alignment material including a first alignment portion, a second alignment portion, a photodecomposition portion, and a photopolymerization portion.

And, the photopolymerization unit is bonded to a side chain of at least one of the first alignment unit, the second alignment unit, and the photodecomposition unit, and is polymerized by first ultraviolet rays in a non-polarized state to form a polymer network, and the photodecomposition unit is selectively decomposed by second ultraviolet rays in a polarized state to uniaxially orient the first alignment unit and the second alignment unit.

In addition, the first orientation portion may include a diamine or a polyimide having a repeating unit represented by the chemical formula 1 below.

[Chemical formula 1]

In addition, the second orientation portion may include a polyamic acid having a repeating unit represented by the chemical formula 2 below.

[Chemical formula 2]

In addition, the photolytic unit may include a dianhydride including cyclobutane and its derivatives represented by the chemical formula 3 below.

[Chemical formula 3]

And, the photopolymerization unit may include one of coumarine or a derivative thereof, cinnamate or a derivative thereof, and chalcone or a derivative thereof.

In addition, the alignment film may include an upper layer including the first alignment portion, the second alignment portion, the photodecomposition portion, and the photopolymerization portion, and a lower layer including the third alignment portion and the second alignment portion.

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And, the photolytic unit includes dianhydride, the first alignment unit includes polyimide or diamine having a repeating unit represented by the following chemical formula 1, the second alignment unit includes polyamic acid having a repeating unit represented by the following chemical formula 2, the third alignment unit includes dianhydride, and the photopolymerization unit can be independently bonded to at least one of a side chain of the photolytic unit, dianhydride, and a side chain of the first alignment unit, diamine.
[Chemical formula 1]

[Chemical formula 2]

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In addition, the alignment film may include an upper layer including the first alignment portion, the second alignment portion, the photodecomposition portion, and the photopolymerization portion, and a lower layer including the third alignment portion, the second alignment portion, and the photopolymerization portion.
And, the photolytic unit includes dianhydride, the first alignment unit includes polyimide or diamine having a repeating unit represented by the following chemical formula 1, the second alignment unit includes polyamic acid having a repeating unit represented by the following chemical formula 2, the third alignment unit includes dianhydride, and the photopolymerization unit can be independently bonded to at least one of a side chain of the photolytic unit, dianhydride, a side chain of the first alignment unit, diamine, and a side chain of the third alignment unit, dianhydride.
[Chemical formula 1]

[Chemical formula 2]

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Meanwhile, the present invention provides a method for manufacturing a substrate for a liquid crystal display device, comprising: a step of forming an alignment material layer by applying an alignment material including a first alignment portion, a second alignment portion, a photodecomposition portion, and a photopolymerization portion on an upper portion of a substrate; a step of performing a first heat treatment on the alignment material layer to remove a solvent of the alignment material layer; a step of performing a second heat treatment on the alignment material layer to imidize the alignment material layer; a step of irradiating a first ultraviolet ray in a non-polarized state on the alignment material layer to form a polymer network on the alignment material layer; and a step of irradiating a second ultraviolet ray in a polarized state on the alignment material layer to uniaxially align the alignment material layer.

And, the photopolymerization unit is polymerized by the first ultraviolet ray in a non-polarized state to form the polymer network, and the photodecomposition unit is selectively decomposed by the second ultraviolet ray in a polarized state to uniaxially align the first alignment unit and the second alignment unit.

The present invention forms an alignment film by using an alignment material having a photopolymerization unit introduced into at least one side chain among an alignment unit and a photodegradable unit, thereby preventing alignment defects and improving hardness and alignment strength.

In addition, the present invention has the effect of preventing alignment defects and improving the hardness and alignment power of the upper layer of the alignment film by forming the upper layer or the upper and lower layers of the alignment film using an alignment material having a photopolymerization unit introduced into the side chain of at least one of the alignment unit and the photodecomposition unit.

FIG. 1 is a cross-sectional view illustrating a liquid crystal display device according to a first embodiment of the present invention.
FIG. 2 is a drawing illustrating an alignment material constituting an alignment film according to a first embodiment of the present invention.
FIGS. 3A to 3C are drawings illustrating a method for forming an alignment film using an alignment material according to a first embodiment of the present invention.
FIG. 4 is a drawing illustrating an alignment film according to a second embodiment of the present invention.
FIG. 5 is a drawing illustrating an alignment film according to a third embodiment of the present invention.
FIG. 6 is a drawing illustrating an ultraviolet irradiation device for an alignment film according to the first embodiment of the present invention.

Hereinafter, with reference to the attached drawings, a substrate according to the present invention, a liquid crystal display device including the same, and a manufacturing method thereof will be described, using an in-plane switching mode (IPS mode) liquid crystal display device as an example.

FIG. 1 is a cross-sectional view illustrating a liquid crystal display device according to a first embodiment of the present invention.

As illustrated in FIG. 1, a liquid crystal display device (110) according to a first embodiment of the present invention includes first and second substrates (120, 160) facing each other and spaced apart from each other and including red, green, and blue subpixel areas (SPr, SPg, SPb), a liquid crystal layer (180) formed between the first and second substrates (120, 160), and a backlight unit (not shown) under the first substrate (120).

Specifically, gate wiring (not shown) and data wiring (not shown) that intersect each other and define red, green, and blue subpixel areas (SPr, SPg, SPb) are formed on the inner surface of the first substrate (120), and a thin film transistor (T) that is connected to the gate wiring and data wiring and includes a gate electrode (122), a semiconductor layer (126), a source electrode (128), and a drain electrode (130) is formed in each of the red, green, and blue subpixel areas (SPr, SPg, SPb).

A gate insulating layer (124) is formed between the gate electrode (122) and the semiconductor layer (126), and a protective layer (132) is formed on the entire surface of the first substrate (120) above the thin film transistor (T).

Here, the gate electrode (122) and source electrode (128) of the thin film transistor (T) can be connected to gate wiring and data wiring, respectively.

In the red, green, and blue subpixel regions (SPr, SPg, SPb) on the upper portion of the protective layer (132), a pixel electrode (134) connected to the drain electrode (130) of the thin film transistor (T) and a common electrode (136) spaced apart from the pixel electrode (134) are formed.

A first alignment film (138) is formed on the entire surface of the first substrate (120) above the pixel electrode (134) and the common electrode (136).

The pixel electrode (134) and the common electrode (136) have a bar shape, are made of a metal material or a transparent conductive material, and can be arranged alternately in each of the red, green, and blue subpixel areas (SPr, SPg, SPb).

In FIG. 1, the pixel electrode (134) and the common electrode (136) are formed as the same layer as an example, but in other embodiments, the pixel electrode (134) and the common electrode (136) may be formed as different layers with an insulating layer interposed therebetween.

And, a black matrix (162) is formed at the boundaries of the red, green, and blue subpixel areas (SPr, SPg, SPb) on the inner side of the second substrate (160), and a color filter layer (164) is formed on the entire surface of the second substrate (160) below the black matrix (162).

The color filter layer (164) includes red, green, and blue color filters (166, 168, 170) corresponding to red, green, and blue subpixel areas (SPr, SPg, SPb), respectively.

A planarization layer (172) is formed on the entire surface of the second substrate (160) under the color filter layer (164), and a second alignment film (174) is formed on the entire surface of the second substrate (160) under the planarization layer (172).

In a liquid crystal display device (110) like this, when a thin film transistor is turned on according to the gate voltage of the gate wire, the data voltage of the data wire is applied to the pixel electrode (134) through the thin film transistor.

A horizontal electric field is generated between the pixel electrode (134) to which the data voltage is applied and the common electrode (136) to which the common voltage is applied, and the liquid crystal molecules of the liquid crystal layer (180) are rearranged according to the generated horizontal electric field to display an image.

In a liquid crystal display device (110) according to the first embodiment of the present invention, at least one of the first and second alignment films (138, 174) is made of an alignment material having a photopolymerization part introduced into the side chain of at least one of the alignment part and the photodecomposition part, which will be described with reference to the drawings.

FIG. 2 is a drawing illustrating an alignment material constituting an alignment film according to a first embodiment of the present invention, and is described together with reference to FIG. 1.

As illustrated in FIG. 2, the alignment material constituting at least one of the first and second alignment films (138, 174) according to the first embodiment of the present invention includes first and second alignment portions (140, 142), a photodecomposition portion (144), and a photopolymerization portion (146).

The first alignment portion (140) is a portion having an alignment force that aligns liquid crystal molecules adjacent to the first and second alignment films (138, 174) of the liquid crystal layer (180) in one direction, and can be arranged in a row with the second alignment portion (142) and the photodecomposition portion (144).

For example, the first orientation portion (140) may include a diamine or a polyimide having a repeating unit represented by the chemical formula 1 below.

[Chemical formula 1]

The second alignment portion (142) is a precursor that becomes the first alignment portion (140) by removing moisture, and can be arranged in a row with the first alignment portion (140) and the photodecomposition portion (144).

For example, the second orientation portion (142) may include a polyamic acid having a repeating unit represented by the chemical formula 2 below.

[Chemical formula 2]

The photodecomposition section (144) is a section that selectively decomposes by polarized ultraviolet rays having a wavelength of about 254 nm to uniaxially align the first and second alignment sections (140, 142), and can be arranged in a line with the first and second alignment sections (140, 142).

And, the photodecomposition part (144) arranged parallel to the polarization direction of ultraviolet rays is decomposed, and the photodecomposition part (144) arranged perpendicular to the polarization direction of ultraviolet rays is not decomposed and can remain as is.

For example, the photolysis unit (144) may include a dianhydride including cyclobutane and its derivatives.

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Here, the dianhydride of the photodecomposition part (144) arranged parallel to the polarization direction of ultraviolet rays is decomposed into a single molecular decomposition substance by cleaving cyclobutane upon irradiation with ultraviolet rays, whereas the dianhydride of the photodecomposition part (144) arranged perpendicular to the polarization direction of ultraviolet rays is not decomposed and can remain as is even when irradiated with ultraviolet rays.

The photopolymerization portion (146) is a portion that forms a polymer network by polymerization or cross-linking with an adjacent photopolymerization portion (146) by polarized ultraviolet rays having a wavelength of about 260 nm or more, and can be chemically bonded to the side chains of the first and second alignment portions (140, 142) and the photodecomposition portion (144).

Specifically, when ultraviolet rays in a polarized state are irradiated on the photopolymerization unit (146), a [2+2] cycloaddition reaction, which is a type of Diels-Alder reaction, occurs between vinyl (C=C), and as a result, cyclobutane is generated and the adjacent photopolymerization unit (146) is polymerized.

And, the photopolymerization portion (146) arranged parallel to the polarization direction of ultraviolet rays is polymerized, and the photodecomposition portion (146) arranged perpendicular to the polarization direction of ultraviolet rays is not polymerized and can remain as is. In the first embodiment of the present invention, by irradiating the alignment material with ultraviolet rays in a non-polarized state, the entire photopolymerization portion (146) can be polymerized regardless of the arrangement direction.

For example, the photopolymerization unit (146) may include one of coumarine or a derivative thereof that is polymerized by ultraviolet light in a polarized state having a wavelength of about 310 nm or more, cinnamate or a derivative thereof that is polymerized by ultraviolet light in a polarized state having a wavelength of about 260 nm or more, and chalcone or a derivative thereof that is polymerized by ultraviolet light in a polarized state having a wavelength of about 306 nm or more.

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By applying the alignment material according to the first embodiment of the present invention, an alignment material layer is formed, and the alignment material layer is irradiated with first ultraviolet rays in a non-polarized state to polymerize the photopolymerization portion (146), thereby improving the hardness of the alignment material layer, and by irradiating the alignment material layer with second ultraviolet rays in a polarized state to decompose the photodecomposition portion (144), thereby improving the alignment power of the alignment material layer.

FIGS. 3A to 3C are drawings illustrating a method of forming an alignment film using an alignment material according to a first embodiment of the present invention, and will be described with reference to FIGS. 1 and 2.

As shown in Fig. 3a, an alignment material layer is formed by applying an alignment material including first and second alignment parts (140, 142), a photodecomposition part (144), and a photopolymerization part (146).

In the alignment material layer, the first and second alignment parts (140, 142), the photodecomposition part (144), and the photopolymerization part (146) can be arranged in the horizontal and vertical directions.

Afterwards, a first heat treatment (drying process) is performed on the alignment material layer, and the alignment material layer is dried through the first heat treatment.

For example, the first heat treatment can be performed at a temperature of about 50 degrees to about 120 degrees for about 80 seconds to about 120 seconds.

Afterwards, a second heat treatment (sintering process) is performed on the alignment material layer. Through the second heat treatment, moisture (H ₂ O) is removed from the second alignment portion (142) of the alignment material layer, and the alignment material layer is imidized.

For example, the second heat treatment can be performed at a temperature of about 200 degrees to about 250 degrees for about 1000 seconds to about 2000 seconds.

Here, since no separate additive is used, the imidization rate increases and the orientation power is improved.

As illustrated in Fig. 3b, when the alignment material layer is irradiated with first ultraviolet light in a non-polarized state having a wavelength of about 260 nm or more, adjacent photopolymerization portions (146) of the alignment material layer are polymerized to generate cross-linking (CL), and as a result, a polymer network is formed in the alignment material layer and the hardness of the alignment material layer is improved.

Here, since the ultraviolet rays in a non-polarized state include polarization in all directions, the entire photopolymerization section (146) of the alignment material layer can be polymerized regardless of the arrangement direction.

In addition, since a polymer network is formed and hardness is improved without using a separate additive, alignment defects of the alignment film due to residual additives are prevented, and defects such as afterimages in liquid crystal displays are prevented.

As illustrated in Fig. 3c, when the alignment material layer is irradiated with second ultraviolet rays in a polarized state having a wavelength of about 254 nm, the photodecomposition portion (144) of the alignment material layer is selectively decomposed.

For example, the second ultraviolet ray may have a polarization state parallel to the horizontal direction, in which case the photodecomposition part (144) arranged in the horizontal direction becomes a decomposition state (DC) by the second ultraviolet ray, and the photodecomposition part (144) arranged in the vertical direction may remain as is without being decomposed.

Accordingly, the first and second alignment parts (140, 142) arranged in the horizontal direction are disconnected, and the first and second alignment parts (140, 142) arranged in the vertical direction are maintained connected, so that the alignment material layer can be uniaxially aligned in the vertical direction.

That is, by irradiating the second ultraviolet ray, the alignment material layer can be uniaxially aligned in a direction perpendicular to the polarization direction of the second ultraviolet ray.

Thereafter, a third heat treatment (post-firing process) is performed on the alignment material layer to complete the first or second alignment film (138, 174). Through the third heat treatment, some of the first and second alignment portions (140, 142) that are not aligned perpendicularly to the polarization direction of the second ultraviolet rays can be rearranged more perpendicularly to the polarization direction of the ultraviolet rays.

For example, the third heat treatment can be performed at a temperature of about 200 degrees to about 250 degrees for about 1000 seconds to about 2000 seconds.

Meanwhile, in another embodiment, each of the first and second alignment films may be formed as a double layer including an upper layer having a relatively high resistivity and a lower layer having a relatively low resistivity, which will be described with reference to the drawings.

FIG. 4 is a drawing illustrating an alignment film according to a second embodiment of the present invention. Descriptions of parts that are the same as those in the first embodiment are omitted.

As illustrated in FIG. 4, the alignment film (238) according to the second embodiment of the present invention includes an upper layer (238a) and a lower layer (238b). The upper layer (238a) is made of an alignment material including a first alignment portion (240a), a second alignment portion (242), a photodecomposition portion (244), and a photopolymerization portion (246), and the lower layer (238b) is made of an alignment material including a third alignment portion (240b) and a second alignment portion (242).

That is, the photopolymerization unit (246) for forming a polymer network is included only in the alignment material of the upper layer (238a), and the photopolymerization unit (246) can be bonded as a side chain to at least one of the first alignment unit (240a), the second alignment unit (242), and the photodecomposition unit (244).

For example, the photodecomposition unit (244) may be dianhydride.

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Here, the photopolymerization portion (246) can be independently bonded to at least one of the side chains of the photodecomposable portion (244) of the anhydride dioxide.

And, the photodecomposition part (244) of anhydride dioxide may include one of the substances represented by the chemical formulas (7-1) to (7-4) below.

[Chemical Formula 7-1]

[Chemical Formula 7-2]

[Chemical Formula 7-3]

[Chemical Formula 7-4]

The first orientation portion (240a) may be a polyimide or diamine having a repeating unit represented by the chemical formula 1 above.

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Here, the photopolymerization portion (246) can be independently bonded to at least one of the side chains of the diamine, which is the first orientation portion (240a).

And, the first orientation portion (240a), diamine, may include one of the substances represented by the chemical formulas (8-1) to (8-24) below.

[Chemical Formula 8-1]

[Chemical Formula 8-2]

[Chemical Formula 8-3]

[Chemical Formula 8-4]

[Chemical Formula 8-5]

[Chemical Formula 8-6]

[Chemical Formula 8-7]

[Chemical Formula 8-8]

[Chemical Formula 8-9]

[Chemical Formula 8-10]

[Chemical Formula 8-11]

[Chemical Formula 8-12]

[Chemical Formula 8-13]

[Chemical Formula 8-14]

[Chemical Formula 8-15]

[Chemical Formula 8-16]

[Chemical Formula 8-17]

[Chemical Formula 8-18]

[Chemical Formula 8-19]

[Chemical Formula 8-20]

[Chemical Formula 8-21]

[Chemical Formula 8-22]

[Chemical Formula 8-23]

[Chemical Formula 8-24]

The second orientation portion (242) may be a polyamic acid having a repeating unit represented by the chemical formula 2 above.

The third orientation portion (240b) may be dianhydride represented by the chemical formula 9 below.

[Chemical formula 9]

Here, Z can be one of the substances represented by chemical formulas (9-1) to (9-28) below.

[Chemical Formula 9-1]

[Chemical Formula 9-2]

[Chemical Formula 9-3]

[Chemical Formula 9-4]

[Chemical Formula 9-5]

[Chemical Formula 9-6]

[Chemical Formula 9-7]

[Chemical Formula 9-8]

[Chemical Formula 9-9]

[Chemical Formula 9-10]

[Chemical Formula 9-11]

[Chemical Formula 9-12]

[Chemical Formula 9-13]

[Chemical Formula 9-14]

[Chemical Formula 9-15]

[Chemical Formula 9-16]

[Chemical Formula 9-17]

[Chemical Formula 9-18]

[Chemical Formula 9-19]

[Chemical Formula 9-20]

[Chemical Formula 9-21]

[Chemical Formula 9-22]

[Chemical Formula 9-23]

[Chemical Formula 9-24]

[Chemical Formula 9-25]

[Chemical Formula 9-26]

[Chemical Formula 9-27]

[Chemical Formula 9-28]

In the alignment film (238) according to the second embodiment of the present invention, by irradiating the first ultraviolet ray in a non-polarized state, the adjacent photopolymerization portion (246) can be polymerized to generate cross-linking (CL), and as a result, a polymer network is formed in the upper layer (238a) of the alignment film (238), thereby improving the hardness of the upper layer (238a) of the alignment film (238).

In addition, since a polymer network is formed without using a separate additive, alignment defects of the alignment film (238) due to residual additives are prevented, and defects such as afterimages in a liquid crystal display device are prevented.

In addition, the photodecomposition part (244) can be decomposed by irradiating the second ultraviolet ray in a polarized state, and as a result, the upper layer (238a) of the alignment film (238) can be uniaxially aligned and the alignment power can be improved.

FIG. 5 is a drawing illustrating an alignment film according to a third embodiment of the present invention. Descriptions of parts that are the same as those in the first and second embodiments are omitted.

As illustrated in FIG. 5, an alignment film (338) according to a third embodiment of the present invention includes an upper layer (338a) and a lower layer (338b). The upper layer (338a) is made of an alignment material including a first alignment portion (340a), a second alignment portion (342), a photodecomposition portion (344), and a photopolymerization portion (346), and the lower layer (338b) is made of an alignment material including a third alignment portion (340b), a second alignment portion (342), and a photopolymerization portion (346).

That is, the photopolymerization unit (346) for forming a polymer network is included in the alignment material of the upper layer (338a) and the lower layer (338b), and the photopolymerization unit (346) can be bonded to at least one of the first alignment unit (340a), the second alignment unit (342), the third alignment unit (340b), and the photodecomposition unit (344) as a side chain.

For example, the photodecomposition unit (344) may be dianhydride represented by the chemical formula 7 above.

Here, the photopolymerization unit (346) can be independently combined with at least one of R1, R2, R3, and R4.

And, X can be one of the substances represented by the chemical formulas (7-1) to (7-4) above.

The first orientation portion (340a) may be a polyimide represented by the chemical formula 1 above or a diamine represented by the chemical formula 8 above.

Here, the photopolymerization unit (346) can be independently combined with at least one of A1 and A2.

And, Y can be one of the substances represented by the chemical formulas (8-1) to (8-24) above.

The second orientation portion (342) may be a polyamic acid represented by the chemical formula 2 above.

The third orientation portion (340b) may be dianhydride represented by the chemical formula 9 above.

Here, the photopolymerization unit (346) can be independently bonded to at least one of the side chains of Z.

Z can be one of the substances represented by the chemical formulas (9-1) to (9-28) above.

In the alignment film (338) according to the third embodiment of the present invention, by irradiating the first ultraviolet ray in a non-polarized state, the adjacent photopolymerization portion (346) can be polymerized to generate cross-linking (CL), and as a result, a polymer network is formed in the upper layer (338a) and the lower layer (338b) of the alignment film (338), thereby improving the hardness of the upper layer (338a) and the lower layer (338b) of the alignment film (338).

In addition, since a polymer network is formed without using a separate additive, alignment defects of the alignment film (338) due to residual additives are prevented, and defects such as afterimages in a liquid crystal display device are prevented.

In addition, the photodecomposition part (344) can be decomposed by irradiating the second ultraviolet ray in a polarized state, and as a result, the upper layer (338a) of the alignment film (338) can be uniaxially aligned and the alignment power can be improved.

Meanwhile, the first and second ultraviolet rays can be irradiated onto the alignment film using one device, which will be explained with reference to the drawings.

FIG. 6 is a drawing illustrating an ultraviolet irradiation device for an alignment film according to the first embodiment of the present invention, which will be described with reference to FIGS. 1 to 3c.

As illustrated in FIG. 6, an ultraviolet irradiation device (410) for irradiating ultraviolet rays to an alignment film according to a first embodiment of the present invention includes a first irradiation unit comprising a first light source (420), a first mirror (422), and a first filter (424), and a second irradiation unit comprising a second light source (430), a second mirror (432), a second filter (434), and a polarizing plate (436), and can sequentially irradiate first and second ultraviolet rays to a first alignment film (138) on a first substrate (120) mounted on a stage (440) with one scan.

The first light source (420) emits first ultraviolet rays in a non-polarized state with various wavelengths, and the first mirror (422) is arranged on the back surface of the first light source (420) to reflect ultraviolet rays emitted backward from the first light source (420) and transmit them forward.

The first filter (424) selectively passes some wavelengths of the first ultraviolet rays. For example, the first filter (424) can pass wavelengths of about 260 nm or longer and block wavelengths of less than about 260 nm.

Accordingly, the first irradiation unit can irradiate the first alignment film (138) with unpolarized first ultraviolet rays having a wavelength of about 260 nm or more, and as a result, a polymer network is formed by the photopolymerization unit (146) of the first alignment film (138), and the hardness of the first alignment film (138) is improved.

In addition, the second light source (430) emits non-polarized second ultraviolet rays having various wavelengths, and the second mirror (432) is arranged on the back surface of the second light source (430) to reflect ultraviolet rays emitted backward from the second light source (430) and transmit them forward.

The second filter (434) selectively passes some wavelengths of the second ultraviolet rays. For example, the second filter (434) can pass a wavelength of about 254 nm and block wavelengths other than about 254 nm.

The polarizing plate (436) selectively allows some polarization components of the second ultraviolet rays to pass through. For example, the polarizing plate (436) can allow linear polarization components parallel to one direction to pass through and block other linear polarization components.

Accordingly, the second irradiation unit can irradiate the first alignment film (138) with second ultraviolet rays in a polarized state having a wavelength of about 254 nm, and as a result, the first alignment film (138) is uniaxially aligned by the photodecomposition unit (144) of the first alignment film (138), and the alignment power of the first alignment film (138) is improved.

As described above, in the substrate according to the present invention, the liquid crystal display device including the same, and the manufacturing method thereof, by introducing a photopolymerization portion (146) into the side chain of at least one of the alignment portions (140, 142) and the photolytic portion (144), alignment defects of the alignment film (138, 172) can be prevented and hardness and alignment power can be improved.

And, by forming the upper layer (238a) of the alignment film (238) using an alignment material having a photopolymerization portion (246) introduced into at least one side chain among the alignment portions (240a, 242) and the photodecomposition portion (244), or by forming the upper and lower layers (338a, 338b) of the alignment film (338) using an alignment material having a photopolymerization portion (346) introduced into at least one side chain among the alignment portions (340a, 340b, 342) and the photodecomposition portion (344), alignment defects of the alignment film (238, 338) can be prevented, and the hardness and alignment force of the upper layer (238a, 338a) of the alignment film (238, 338) can be improved.

Although the present invention has been described above with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various modifications and changes may be made to the present invention without departing from the technical spirit and scope of the present invention as set forth in the claims below.

110: Liquid crystal display device 120: First substrate
160: Second substrate 138: First alignment film
140: 1st orientation part 142: 2nd orientation part
144: Photolysis section 146: Photopolymerization section
174: Second alignment layer 180: Liquid crystal layer

Claims (15)

substrate and;
An alignment film formed of an alignment material, which is disposed on the upper portion of the substrate and includes a first alignment portion, a second alignment portion, a photodecomposition portion, and a photopolymerization portion.
Including,
The first orientation part, the second orientation part and the photodecomposition part are arranged in a row,
The photopolymerization unit is bonded to a side chain of at least one of the first orientation unit, the second orientation unit and the photodecomposition unit,
A substrate for a liquid crystal display device in which adjacent photopolymerization sections are polymerized to form a polymer network regardless of the arrangement direction by first ultraviolet rays in a non-polarized state.
In paragraph 1,
A substrate for a liquid crystal display device in which the above-mentioned photodecomposition section is selectively decomposed by second ultraviolet rays in a polarized state to uniaxially align the first alignment section and the second alignment section.
In paragraph 1,
The above first orientation portion is a substrate for a liquid crystal display device including a diamine or a polyimide having a repeating unit represented by the chemical formula 1 below.
[Chemical formula 1]

In paragraph 1,
The second orientation portion is a substrate for a liquid crystal display device including a polyamic acid having a repeating unit represented by the chemical formula 2 below.
[Chemical formula 2]

In the first paragraph,
The above photolytic section is a substrate for a liquid crystal display device including a dianhydride including cyclobutane and its derivatives represented by the chemical formula 3 below.
[Chemical formula 3]

In paragraph 1,
The above photopolymerization unit is a substrate for a liquid crystal display device, which contains one of coumarine or a derivative thereof, cinnamate or a derivative thereof, and chalcone or a derivative thereof.
In paragraph 1,
A substrate for a liquid crystal display device, wherein the alignment film comprises an upper layer including the first alignment portion, the second alignment portion, the photodecomposition portion, and the photopolymerization portion, and a lower layer including the third alignment portion and the second alignment portion.
In paragraph 7,
The above photodecomposition unit comprises dianhydride,
The above first orientation part includes a polyimide or diamine having a repeating unit represented by the chemical formula 1 below,
The second orientation portion includes a polyamic acid having a repeating unit represented by the chemical formula 2 below,
The third orientation portion comprises dianhydride,
A substrate for a liquid crystal display device, wherein the photopolymerization unit is independently bonded to at least one of the side chain of the photodecomposition unit, the anhydride dioxide, and the side chain of the first alignment unit, the diamine.
[Chemical formula 1]

[Chemical formula 2]

In the first paragraph,
A substrate for a liquid crystal display device, wherein the alignment film comprises an upper layer including the first alignment portion, the second alignment portion, the photodecomposition portion, and the photopolymerization portion, and a lower layer including the third alignment portion, the second alignment portion, and the photopolymerization portion.
In Article 9,
The above photodecomposition unit comprises dianhydride,
The above first orientation part includes a polyimide or diamine having a repeating unit represented by the chemical formula 1 below,
The second orientation portion includes a polyamic acid having a repeating unit represented by the chemical formula 2 below,
The third orientation portion comprises dianhydride,
A substrate for a liquid crystal display device, wherein the photopolymerization unit is independently bonded to at least one of the side chain of the photodecomposable anhydride, the side chain of the first alignment unit, the diamine, and the side chain of the third alignment unit, the dioxide anhydride.
[Chemical formula 1]

[Chemical formula 2]

A step of forming an alignment material layer by applying an alignment material including a first alignment portion, a second alignment portion, a photodecomposition portion, and a photopolymerization portion on the upper part of a substrate;
A step of performing a first heat treatment on the alignment material layer to remove the solvent of the alignment material layer;
A step of performing a second heat treatment on the alignment material layer to imidize the alignment material layer;
A step of irradiating first ultraviolet rays in a non-polarized state to the alignment material layer to form a polymer network in the alignment material layer;
A step of irradiating the second ultraviolet ray in a polarized state to the alignment material layer to uniaxially align the alignment material layer.
Including,
The first orientation part, the second orientation part and the photodecomposition part are arranged in a row,
The photopolymerization unit is bonded to a side chain of at least one of the first orientation unit, the second orientation unit and the photodecomposition unit,
A method for manufacturing a substrate for a liquid crystal display device, wherein adjacent photopolymerization sections are polymerized regardless of the arrangement direction by the first ultraviolet ray in a non-polarized state to form the polymer network.
In Article 11,
A method for manufacturing a substrate for a liquid crystal display device, wherein the photodecomposition section is selectively decomposed by the second ultraviolet ray in a polarized state to uniaxially align the first alignment section and the second alignment section.
In paragraph 1,
A substrate for a liquid crystal display device, wherein, by irradiation with the first ultraviolet ray, a [2+2] cyclization addition reaction occurs between vinyl (C=C) of the photopolymerization portion to generate cyclobutane, and adjacent photopolymerization portions are polymerized with each other by the cyclobutane.
In the second paragraph,
The above first ultraviolet ray has a wavelength of 260 nm or more,
The above second ultraviolet ray is a substrate for a liquid crystal display device having a wavelength of 254 nm. In paragraph 1,
A substrate for a liquid crystal display device, wherein the second alignment portion is a precursor that becomes the first alignment portion by removing moisture.