KR101065652B1 - Solution composition for alignment film, method of forming alignment film, method of manufacturing liquid crystal display device using the same, and liquid crystal display device comprising alignment film manufactured by the same - Google Patents

Abstract

Disclosed are an alignment film solution composition capable of achieving sufficient imidization at a low temperature, a method of forming an alignment film using the same, a method of manufacturing a liquid crystal display device, and a liquid crystal display device. To this end, an alignment film solution composition comprising a first alignment layer solution having an dianhydride compound and a diamine compound, a dianhydride compound in which some functional groups are substituted with an alkyl group, and a second alignment layer solution having a diamine compound are provided. And it provides an alignment film solution composition comprising a first alignment film solution and a catalyst. Further, a method of forming an alignment film using the alignment film solution composition, a method of manufacturing a liquid crystal display device, and a liquid crystal display device are provided. Even at low temperatures, the degree of imidization of the alignment film can be improved, and an alignment film with remarkably improved physicochemical resistance can be obtained. Therefore, even when the liquid crystal layer is formed by the dropping method, local intrusion of the alignment film by the liquid crystal can be prevented.

Description

An alignment film solution composition, a method of forming an alignment film, a method of manufacturing a liquid crystal display device using the same, and a liquid crystal display device including the alignment film manufactured by the same. USING THE SAME, AND LIQUID CRYSTAL DISPLAY DEVICE COMPRISING ALIGNMENT FILM MANUFACTURED BY THE SAME}

1 is a photograph showing dripping spots observed upon liquid crystal dropping in an alignment film formed by the prior art.

2 is a flowchart illustrating a method of forming an alignment layer according to an embodiment of the present invention.

3 is a flowchart illustrating a method of manufacturing a liquid crystal display device using the alignment film forming method of FIG. 2.

4 is a schematic cross-sectional view showing a liquid crystal display device manufactured by the method of FIG.

Brief description of the main parts of the drawing

10, 11 substrate 20, 21 thin film electrode

30, 31 alignment film 40 liquid crystal

The present invention relates to an alignment film solution composition used in a liquid crystal display device, a method of forming an alignment film using the same, and a liquid crystal display device, and more particularly, to form an alignment film solution composition capable of sufficiently imidizing even at low temperature and an alignment film using the same. It relates to a method and a liquid crystal display device.

Liquid crystal is a material having both the fluid characteristics of the liquid and the optical characteristics of the solid at the same time has the advantage that can easily control the molecular arrangement and optical properties. LIQUID CRYSTAL DISPLAY DEVICE (LCD) is a display device made by using the characteristics of the liquid crystal and displays information on the screen by adjusting the transmittance of light. In such a liquid crystal display device, the control of the molecular arrangement of the liquid crystal has a great influence on stabilization of the display quality of the liquid crystal display device. The alignment layer serves to orient the liquid crystal molecules on the surface of the alignment layer in a predetermined direction. However, when the liquid crystal has an unwanted pattern due to the physical and chemical influences generated in the process, the pattern is transferred to the liquid crystal alignment to show screen defects.

This will be described in detail as follows. Scheme 1 below shows a general imidization step in forming a polyimide organic alignment film.                         

First, an alignment film solution containing a dianhydride represented by Chemical Formula 1 and a diamine represented by Chemical Formulas 2 to 3 is applied onto a substrate of a liquid crystal display, and then the solvent is evaporated through preliminary drying. To synthesize a polyamic acid represented by the formula (4). Subsequently, the polyamic acid is converted into the polyimide represented by Chemical Formula 5 through the present curing process. At this time, the main curing is performed for about 30 minutes at about 200 to 300 ℃.

However, even after this main hardening, sufficient imidation does not advance and a considerable part of an orientation film remains in a polyamic-acid state. The polyamic acid remaining in the alignment film is physically damaged by the liquid crystal, particularly when the liquid crystal layer is formed through the dropping method. The dropping method means a liquid crystal filling method in which a liquid crystal is dropped on a glass substrate coated with an alignment layer using a syringe or the like and then compressed to produce a liquid crystal cell. In this case, a certain amount of time and pressure are required to level the entire panel at the point where the liquid crystal is dropped. However, in the state where the liquid crystal is not sufficiently leveled, the alignment layer is damaged by the chemical reaction between the liquid crystal compound and the alignment layer compound.

That is, the liquid crystal includes functional groups such as ester groups, halogen groups, cyano groups, and alkyl groups depending on the kind thereof, and the amide groups and carboxyl groups of the polyamic acid in which the functional groups contained in the liquid crystal in a sufficiently leveled state remain in the alignment film. By partially dissolving and swelling an alignment film that is electrostatically bonded or not sufficiently imidized, a state change of the alignment film according to the distribution of the liquid crystal is caused in a subsequent process.

As described above, an irreversible change is caused in the alignment layer according to the drop pattern of the liquid crystal droplets, resulting in a permanent pattern of liquid crystal alignment, which is observed as a stain when the liquid crystal display device is driven.

1 is a photograph showing dripping spots observed upon liquid crystal dropping in an alignment film formed by the prior art. Referring to FIG. 1, it can be seen that luminance varies depending on the dropping point of the liquid crystal when the liquid crystal display device manufactured by the dropping method is driven.

There is known a technique for preventing unevenness of such an alignment film. For example, Korean Patent Laid-Open Publication No. 10-2003-0037820 discloses a liquid crystal display device which can improve a bright point defect of an alignment layer by differently setting positions of vacuum holes provided in a plurality of hot plates when a glass substrate for pre-drying is moved. An alignment film forming apparatus and method are disclosed. According to the above-described invention, the uniformity of the thermal conductivity can be improved by preventing the drying at a specific point from being different from other points. By overcoming the difference in thermal conductivity, it is possible to prevent defect defects of the alignment layer and to improve a problem of bright point caused when the alignment layer is dried.

According to this method, it is possible to prevent the occurrence of unevenness of the alignment film by achieving the same dryness over the entire preliminary alignment film, but the degree of imidization cannot be sufficiently improved. In addition, in order to proceed with the imidization reaction, a process of curing at a relatively high temperature of 200 to 300 ° C. is required. High temperature process conditions may lower the economical efficiency of manufacturing a liquid crystal display and may cause deterioration of members due to high temperatures. . Therefore, when the liquid crystal layer is formed using a dropping method, the alignment layer solution composition, the alignment layer using the same, and the liquid crystal display device employing the alignment layer can be sufficiently imidized at low temperature to prevent damage of the alignment layer due to the liquid crystal. The development of technology is required.

Accordingly, a first object of the present invention is to provide an alignment film solution composition capable of achieving sufficient imidization at a low temperature.

A second object of the present invention is to provide a method for forming an alignment film using the above-described alignment film solution composition.

A third object of the present invention is to provide a method of manufacturing a liquid crystal display device using the above-described alignment film forming method.                         

A fourth object of the present invention is to provide a liquid crystal display device manufactured by the above-described method for manufacturing a liquid crystal display device.

In order to achieve the first object of the present invention described above, an embodiment of the present invention comprises a dianhydride compound represented by the following formula (1), and a diamine compound comprising at least one of the compounds represented by the following formulas (2) to 1 provides an alignment film solution composition comprising an alignment film solution and an dianhydride compound containing an alkyl group, and a second alignment film solution containing a diamine compound containing an alkyl group (wherein R 3 is O (CH 2) 15 CH 3 or COO (CH2) 15CH3).

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 In order to achieve the first object of the present invention described above, another embodiment of the present invention is at least one diamine selected from the group consisting of a dianhydride compound represented by Formula 1, and the compound represented by Formula 2 to 3 An alignment film solution composition comprising an alignment film solution containing a compound and a catalyst for reducing the imidization activation energy of the alignment film solution.

In order to achieve the second object of the present invention described above, according to the alignment film forming method according to an embodiment of the present invention, the alignment film solution is applied to a substrate, and the alignment film solution is pre-dried to be converted into a compound containing polyamic acid. Thereafter, the compound containing the polyamic acid is cured at about 190 to 220 ° C. at low temperature to be converted to the compound containing the polyimide to form an alignment layer.

In order to achieve the above-described third object of the present invention, according to the manufacturing method of the liquid crystal display device according to an embodiment of the present invention, a pair of substrates facing each other on which a thin film electrode is formed, and the substrate on which the thin film electrode is formed After the alignment film is formed on the above-mentioned method, the liquid crystal is dropped between the alignment films to fill the liquid crystal.

In order to achieve the fourth object of the present invention described above, an embodiment of the present invention is a pair of substrates facing each other, a thin film electrode formed on the substrate, the substrate formed by the above-described alignment film forming method, the substrate on which the thin film electrode is formed Provided is a liquid crystal display including a liquid crystal filled between an alignment layer positioned on the alignment layer and an alignment layer.

When the alignment film solution according to the present invention is used, the degree of imidization of the alignment film can be improved even at low temperatures, and the alignment film can be obtained with significantly improved physicochemical resistance. Therefore, even when the liquid crystal layer is formed by the dropping method, local intrusion of the alignment film by the liquid crystal can be prevented. As a result, the present invention can improve the reliability of the alignment film and the economics of the manufacturing process thereof, thereby making it possible to economically manufacture high quality liquid crystal display devices.

Hereinafter, the alignment film solution composition according to the present invention will be described in more detail.

The alignment layer solution composition according to an embodiment of the present invention is a part of the dianhydride compound having a phenylene group, and the first alignment layer solution, which is a general organic alignment layer solution containing a diamine compound, and the dianhydride compound and diamine compound having the phenylene group. A second alignment layer solution including a compound in which a functional group is substituted with an alkyl group is included.

Specifically, the dianhydride compound in the first alignment layer solution composition is, for example, a compound represented by Formula 1, and the diamine compound includes one or both of the compounds represented by Formulas 2 to 3.

The dianhydride compound having an alkyl group in the second alignment layer solution composition is, for example, a compound in which at least one functional group is substituted with an alkyl group in the compound represented by Formula 1. The diamine compound having an alkyl group in the second alignment layer solution composition is, for example, a compound in which at least one functional group of the compound represented by Formulas 2 to 3 is substituted with an alkyl group.

The dianhydride compound and diamine compound in which the phenylene group is substituted with the alkyl group may be easily imidized even at low temperature because the stiffness is lower in molecular structure than the compound substituted with the phenylene group alone. Here, the first alignment layer solution is used in about 70 to 90% by weight, the second alignment layer solution is used in about 10 to 30% by weight. If less than about 10% by weight of the second alignment layer solution is used, the amount is insignificant to obtain a low temperature curing (imidization) effect, and when used in excess of about 30% by weight, heat resistance, chemical resistance, and the like decrease.

An alignment layer solution composition according to another embodiment of the present invention is an dianhydride compound represented by Formula 1, and an alignment layer solution and a catalyst comprising at least one diamine compound selected from the group consisting of compounds represented by Formulas 2 to 3 below. It includes.

The catalyst may be used as pyridine, tertary amine, or a mixture thereof. By using a pyridine or tert-amine catalyst instead of a catalyst such as isoquinoline or p-toluene sulfonic acid used in the conventional alignment film solution, the activation energy required for imidization can be lowered. Therefore, the polycondensation of the alignment film solution at low temperature becomes possible.

Here, the amount is used in the ratio of about 97 to 99.5% by weight of the alignment film solution, and about 0.05 to 3% by weight of the catalyst. If the amount of the catalyst is less than about 0.05% by weight, it is insufficient to achieve the low temperature curing effect. Even if the amount of the catalyst is used in excess of about 3% by weight, the low temperature imidization rate does not increase in proportion to the amount used, and it is not economically desirable. .

Using the alignment film solution composition according to the above-described embodiments, there is an advantage that can be rapidly imidized at a low temperature.

The present invention also provides a method of forming an alignment layer using a low temperature curing method. 2 is a flowchart illustrating a method of forming an alignment layer according to an embodiment of the present invention.

Referring to FIG. 2, an alignment layer solution may be formed by first applying an alignment layer solution to a substrate (S10), preliminary drying (S20), and then performing low temperature curing (S30).

In this embodiment, the alignment film solution is first applied to the substrate (S10). Specifically, the contamination and dust remaining on the patterned substrate is removed using a cleaning solution, and then the alignment layer solution is applied onto the glass substrate. The coating is carried out using a spin method, a dipping method, a roller coating method, or the like.

In the present embodiment, the alignment film solution composition according to the above-described embodiments is used to form the polyimide organic alignment film. That is, a dianhydride compound having a phenylene group, and a first alignment layer solution which is a general organic alignment film solution containing a diamine compound, a dianhydride compound having a phenylene group and a compound in which some functional groups are substituted with an alkyl group in the diamine compound. An alignment film solution comprising an alignment film solution composition including a second alignment film solution, or at least one diamine compound selected from the group consisting of a dianhydride compound represented by Formula 1, and a compound represented by Formulas 2 to 3 below. An alignment film solution composition containing a catalyst can be used.

Subsequently, the alignment layer solution is pre-dried to form a polyamic acid (S20). The dianhydride including the phenylene group represented by Chemical Formula 1 and the diamine represented by Chemical Formulas 2 to 3 are reacted in the solvent to form a polyamic acid represented by Chemical Formula 4 through a preliminary drying process. R at 4 is for example O (CH 2) 15 CH 3 or COO (CH 2) 15 CH 3). In addition, the solvent is evaporated prior to the curing process by the predrying, the predrying process is carried out at about 80 ℃.

Subsequently, the compound containing the polyamic acid is cured at a low temperature to be converted to the compound containing the polyimide (S30).

The low temperature curing is carried out at a temperature of about 190 to 220 ℃. According to the conventional method, curing for polyimidization is carried out by firing for about 20 to 40 minutes at a temperature of about 200 to 300 ℃. However, in this embodiment, since the alignment film solution composition of the above-described embodiment is used, rapid imidization is possible even at low temperatures.

That is, by using an alignment film solution composition comprising an dianhydride having a substituted alkyl group and diamine or an alignment film solution composition containing a catalyst such as pyridine or tert-amine, the dehydration polycondensation reaction proceeds smoothly even at low temperatures. It is converted to the polyimide shown.

Imideization of about 60% or more can be achieved through the low temperature imidization reaction, and the amide group or carboxylic acid group of the polyamic acid of the alignment film and the ester group, halogen group, and cyano group contained in the liquid crystal can be achieved even if the liquid crystal is dropped into the alignment film. The reaction of the alkyl group and the like can be prevented to prevent the state change of the alignment layer due to the distribution of the liquid crystal. Therefore, even when the liquid crystal is filled by the dropping method, it is possible to minimize the unevenness due to the liquid crystal dropping.

At this time, if the curing temperature is less than about 190 ° C., imidization may not proceed sufficiently, and dropping stains may be observed during the manufacture of the liquid crystal display device. If the curing temperature exceeds 220 ° C., the device may be deteriorated due to high temperature. It is not preferable in terms of phosphorus.

The present invention provides a method of manufacturing a liquid crystal display device using the alignment film forming method. FIG. 3 is a flowchart illustrating an embodiment of a method of manufacturing a liquid crystal display device using the alignment film forming method of FIG. 2.

Referring to FIG. 3, in this embodiment, a pair of substrates on which a thin film electrode is formed is prepared (S100), an alignment layer is formed on the substrate by a low temperature imidization method (S200), and then liquid crystal is filled (S300). A liquid crystal display device is manufactured.                     

First, in this embodiment, a pair of substrates are prepared (S100). The pair of substrates may be a substrate commonly used in a liquid crystal display, and typically include a color filter substrate on which a common electrode and an RGB pixel are formed, and a pixel electrode and a thin film transistor (TFT). Prepare the TFT substrates to face each other.

 Subsequently, an alignment layer is formed on the substrate (200). The alignment film is formed by the alignment film forming method according to the embodiment of the present invention described above. Specifically, the alignment film solution composition is coated on the substrate on which the thin film electrode is formed, and preliminarily dried to convert to a compound containing polyamic acid, and then the compound containing the polyamic acid is imidized at about 190 to 220 ° C. to align the alignment film. To form. If the curing temperature is less than about 190 ° C., imidization may not proceed sufficiently, and dropping stains may be observed when manufacturing a liquid crystal display device. If the curing temperature exceeds 220 ° C., the device may be deteriorated due to high temperature. Not desirable The alignment layer solution composition is an alignment layer solution composition according to the aforementioned embodiments of the present invention.

Finally, the liquid crystal is filled between the alignment layers (S300). The liquid crystal can be filled between the alignment layers by a vacuum injection method or the like. However, in this embodiment, since the degree of imidization progresses to 60% or more, an alignment layer having improved physical and chemical resistance is used. Occurrence is reduced.

In addition, the present invention provides a liquid crystal display device manufactured by the method for manufacturing the liquid crystal display device. 4 is a schematic cross-sectional view showing a liquid crystal display manufactured by the method of FIG.

Referring to FIG. 4, the liquid crystal display of the present invention includes an alignment layer formed according to the method of forming the alignment layer described above on the pair of substrates 10 and 11, the thin film electrodes 20 and 21, and the substrate on which the thin film electrodes are formed. 30, 31, and a liquid crystal 40 filled between the alignment layers.

First, the liquid crystal display according to the present embodiment includes a pair of substrates 10 and 11 facing each other. The pair of substrates may be substrates commonly used in liquid crystal display devices. For example, one of the pair of substrates is a color filter substrate 10 in which a common electrode 20 and an RGB pixel (not shown) are formed, and the other is a pixel electrode 21 and a TFT (not shown). ) Is a TFT substrate 11 formed.

And thin film electrodes 20 and 21 formed on the substrate. The thin film electrodes 20 and 21 are formed to face each other on the pair of substrates 10 and 11 facing each other, and the common electrode 20 is formed in the color filter substrate 10 of the pair of substrates. The pixel electrode 21 is formed on the TFT substrate 11.

In addition, the liquid crystal display according to the present exemplary embodiment includes alignment layers 30 and 31 formed by a low temperature curing process. The formation of the alignment layer is performed by one embodiment of the method of forming the alignment layer described above. Specifically, the alignment layer solution composition is pre-dried to be converted into a compound containing polyamic acid, and the compound containing the polyamic acid is cured at about 190 to 220 ° C. to convert to a polyimide to form alignment layers 30 and 31. If the curing temperature is less than about 190 ° C., imidization may not proceed sufficiently, and dropping stains may be observed during the manufacture of the liquid crystal display device. If the curing temperature exceeds 220 ° C., the device may be deteriorated due to high temperature. It is not preferable in terms of cotton. The alignment layer solution composition is an alignment layer solution composition according to the aforementioned embodiments of the present invention.

And a liquid crystal 40 filled between the alignment layers. The liquid crystal 40 can be filled by a vacuum injection method or the like. However, in this embodiment, since the imidation degree is provided with an alignment film having a degree of imidization of 60% or more, no dropping stain occurs even when a dropping method is applied.

When the alignment film solution according to the present invention is used, the degree of imidization of the alignment film can be improved even at low temperatures, and the alignment film can be obtained with significantly improved physicochemical resistance. Therefore, even when the liquid crystal layer is formed by the dropping step, local intrusion of the alignment film by the liquid crystal can be prevented. As a result, the present invention can improve the reliability of the alignment film and the economics of the manufacturing process thereof, thereby making it possible to economically manufacture high quality liquid crystal display devices.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims It can be understood that

Claims (10)

A first alignment layer solution including a dianhydride compound represented by the following Chemical Formula 1, and diamine compounds represented by the following Chemical Formulas 2 to 3; And A second an dianhydride in which any one of hydrogen atoms bonded to a carbon atom is substituted with an alkyl group, and at least one selected from diamine compounds in which at least one functional group of the compound represented by the following Chemical Formulas 2 to 3 is substituted with an alkyl group An alignment film solution composition comprising an alignment film solution; [Formula 1]

[Formula 2]

(3)

However, in Chemical Formula 3, R is O (CH ₂ ) ₁₅ CH ₃ or COO (CH ₂ ) ₁₅ CH ₃ . The alignment layer solution composition of claim 1, comprising 70 to 90 wt% of the first alignment layer solution, and 10 to 30 wt% of the second alignment layer solution. An oriented film solution comprising a dianhydride compound represented by the following Chemical Formula 1, and diamine compounds represented by the following Chemical Formulas 2 to 3; And An alignment film solution composition comprising pyridine or tertary amine and comprising a catalyst for reducing the imidization activation energy of the alignment film solution; [Formula 1]

[Formula 2]

(3)

However, in Chemical Formula 3, R is O (CH ₂ ) ₁₅ CH ₃ or COO (CH ₂ ) ₁₅ CH ₃ . delete 4. The alignment film solution composition of claim 3 comprising 97 to 99.5 wt% of the alignment film solution, and 0.05 to 3 wt% of the catalyst. An anhydride compound represented by Formula 1 below, a first alignment layer solution including a diamine compound represented by Formulas 2 to 3 below, and a dianhydride compound wherein any one of hydrogen atoms bonded to a carbon atom is substituted with an alkyl group, And applying an alignment layer solution composition comprising a second alignment layer solution including at least one of diamine compounds in which at least one functional group of the compound represented by Formulas 2 to 3 is substituted with an alkyl group; Pre-drying the alignment layer solution composition to convert the compound into a polyamic acid-containing compound; And Forming an alignment layer comprising the step of curing the compound containing the polyamic acid at 190 ℃ to 220 ℃ converted to a compound containing a polyimide; [Formula 1]

[Formula 2]

(3)

However, in Chemical Formula 3, R is O (CH ₂ ) ₁₅ CH ₃ or COO (CH ₂ ) ₁₅ CH ₃ . The method of claim 6, wherein the polyamic acid comprises a compound represented by Formula 4 below. [Formula 4]

However, in Chemical Formula 4, R is O (CH ₂ ) ₁₅ CH ₃ or COO (CH ₂ ) ₁₅ CH ₃ . The method for forming an alignment film according to claim 6, wherein the degree of imidization of the compound containing the polyimide is 60% or more. a) preparing a pair of substrates facing each other on which a thin film electrode is formed; b) an dianhydride compound represented by the following Chemical Formula 1, and an alignment layer solution including the diamine compounds represented by the following Chemical Formulas 2 to 3 on the substrate on which the thin film electrode is formed, and pyridine or tertary amine; Applying an alignment layer solution composition comprising a catalyst for reducing the imidization reaction activation energy of the alignment layer solution; Pre-drying the alignment layer solution composition to convert the compound into a polyamic acid-containing compound; And Forming an alignment layer comprising curing the compound including the polyamic acid at 190 ° C. to 220 ° C. and converting the compound into a compound including a polyimide; And c) a method of manufacturing a liquid crystal display device including dropping liquid crystal between the alignment layers to fill a liquid crystal; [Formula 1]

[Formula 2]

(3)

However, in Chemical Formula 3, R is O (CH ₂ ) ₁₅ CH ₃ or COO (CH ₂ ) ₁₅ CH ₃ . delete

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