KR102377896B1 - A Composition for Cleaning Alignment Film - Google Patents

Abstract

The present invention relates to a cleaning solution composition for an alignment layer, and provides a cleaning solution composition capable of preventing adhesion and adhesion of polyimide contaminants due to volatility of the cleaning agent by including a low volatility hydrophilic additive. According to the cleaning liquid composition according to the present invention, it is possible to prevent contamination by polyimide decomposition products and at the same time to easily disperse the decomposition products to facilitate removal in the cleaning process.

Description

Alignment film cleaning liquid composition {A Composition for Cleaning Alignment Film}

The present invention relates to an alignment film cleaning liquid composition, and more particularly, to a cleaning liquid composition for cleaning a polyimide alignment film in a liquid crystal display manufacturing process.

The alignment layer is formed through a rubbing process or an ultraviolet irradiation process in a liquid crystal display alignment process. In order to compensate for physical problems and contamination caused by the conventional rubbing process, a photo-alignment layer forming method using UV irradiation is used.

As shown in FIG. 1 , in the photo-alignment layer process, after a polymer (eg, polyimide) for forming a photo-alignment layer is applied on a substrate and then light is irradiated in a predetermined pattern (angle), the light is irradiated in the same direction The polyimide chains are arranged in this manner, and then, when the liquid crystal process is performed, the liquid crystals are arranged in the same direction.

In the alignment layer process, polyimide is imidized by the reaction and curing process of the acid anhydride and diamine as follows.

The polyimide molecular chains after curing are in an arbitrary arrangement, and the carbon ring of the acid part may be cut by polarized UV irradiation, so that the polymer may be decomposed. At this time, the degree of polymer chain breakage varies depending on the polymer chain direction and the UV polarization direction, so that a decomposed product having a low molecular weight distribution in the form of a monomer or oligomer is generated. These decomposition products are dissolved and removed by the cleaning solution from the cleaning process, thereby forming trenches in which the liquid crystals can be arranged in a defect-free state.

When the cleaning solution in which the polyimide decomposition product is dissolved is removed after the cleaning process, the highly volatile cleaning solution volatilizes and the polyimide decomposition product may aggregate and remain. FIG. 2 schematically illustrates the cause of defects in a cleaning process using a highly volatile solvent such as ethyl lactate (EL). In the alignment layer cleaning process, a cleaning liquid spraying process and a water spraying process are performed. An air knife may be used in order to minimize the flow of the cleaning liquid in the cleaning liquid spraying process to the water spray zone. When an air knife is used, the volatilization of the residual cleaning liquid can be accelerated, so that agglomerates are more likely to occur, and since the agglomerates are not volatile, they are likely to adhere to the substrate. Agglomerates attached to the substrate are insoluble in water, so they cannot be removed during the water rinsing step and remain on the substrate. can cause The light leakage phenomenon is a phenomenon that occurs when some of the light incident on the liquid crystal is emitted to the outside through the liquid crystal oriented at an angle, and is one of the criteria for judging a defect.

An object of the present invention is to provide a cleaning solution composition having low volatility and excellent dispersibility in polyimide monomer and miscibility in water so as to solve the above problems.

The present invention in order to solve the above problems,

100 parts by weight of an organic solvent having a volatility exceeding 0.1; and

There is provided a cleaning solution composition comprising 0.1 to 20 parts by weight of a low volatility hydrophilic additive having a volatility of 0.1 or less.

According to the cleaning solution composition according to the present invention, it is possible to effectively prevent the residual adhesion to the substrate after the cleaning process due to excellent dispersibility to polyimide decomposition products and miscibility with water during the polyimide photo-alignment film cleaning process.

1 schematically shows the principle of a photo-alignment film process.
2 schematically illustrates the principle of occurrence of a defect problem in an existing process.
3 schematically shows the principle of the improvement effect according to the invention.
4 is a photograph of the surface after an alignment layer cleaning treatment according to Example 2. Referring to FIG.
5 is a photograph of the surface after the alignment layer cleaning treatment according to Comparative Example 1. Referring to FIG.

Hereinafter, the present invention will be described in detail. The terms or words used in the present specification and claims should not be construed as being limited to their ordinary or dictionary meanings, and the inventor may properly define the concept of the term in order to best describe his invention. Based on the principle that there is, it should be interpreted as meaning and concept consistent with the technical idea of the present invention.

In order to solve this problem, the present invention provides a cleaning solution composition comprising 100 parts by weight of an organic solvent having a volatility of more than 0.1 and 0.1 to 20 parts by weight of a low volatility hydrophilic additive having a volatility of 0.1 or less.

The cleaning solution composition of the present invention having the above configuration has low volatility and excellent dispersibility in polyimide monomer and miscibility in water.

Therefore, as shown in FIG. 3 , in the cleaning agent containing the low volatility additive according to the present invention, even if the high volatility solvent is evaporated and removed in the air knife process, the polyimide decomposition product is dispersed in the low volatility hydrophilic additive and cohesively attached to the substrate prevent it from becoming Since they also have solubility (miscibility) in water, they can be easily removed by being dispersed in water in a subsequent rinse process.

According to a preferred embodiment, the volatility is a relative volatility based on volatility 1 of normal butyl acetate, and the amount of volatility is measured at 25° C. and atmospheric pressure (760 mmHg) for 5 hours.

The additive may be abbreviated as a low volatility additive or a hydrophilic additive hereinafter.

According to one embodiment, the content of the low volatility additive may be 0.1 to 20 parts by weight, preferably 0.1 to 10 parts by weight, more preferably 0.1 to 5 parts by weight based on 100 parts by weight of the high volatility organic solvent.

If the content of the low-volatile additive is too small, the cleaning power tends to decrease, and if the content is too large, it may not be sufficiently removed in the cleaning solution removal process using an air knife or the like due to the increase in viscosity. This is highly likely to cause defects.

According to one embodiment, the low volatility additive having a volatility of 0.1 or less may be selected from alcohols, ethers, pyrrolidones, sulfoxides, and combinations thereof having a vapor pressure of 1 mmHg or less. The volatility of the low-volatile additive may be lower than the volatility of the organic solvent and is not particularly limited, but may be 0.0001 or more in consideration of process applicability.

The low volatility additive is preferably a hydrophilic material having a solubility of 20 g or more with respect to 100 g of water to facilitate removal by water in the rinse process. More preferably, it may have a solubility of 50 g or more with respect to 100 g of water.

According to one embodiment, the low volatility additive having a volatility of 0.1 or less may be an alcohol or an organic group including at least one hydroxyl group. The hydroxyl group is distinct from OH included in a carboxyl group (COOH), and may mean a functional group consisting of hydrogen and oxygen.

In addition, one or more of the hydrogen atoms of the low-volatile additive include a carboxyl group, a thiol group, a hydroxy group, an alkyl group having 1 to 20 carbon atoms, a heteroalkyl group having 1 to 20 carbon atoms, an alkylcarbonyl group having 2 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms. A carbonyl group, an alkoxy group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a heteroalkenyl group having 2 to 20 carbon atoms, a hetero alkynyl group having 2 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, an aryl group having 7 to 30 carbon atoms It may be substituted with an alkyl group or the like.

Specifically, for example, the low volatility additive is ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, glycerol, butyl diglycol, methyl pyrrolidone, diethylene glycol monoethyl ether, diethylene glycol It may be selected from monomethyl ether, dipropylene glycol monomethyl ether, dimethyl sulfoxide, and combinations thereof.

On the other hand, the organic solvent having a volatility exceeding 0.1 may be selected from alcohols, esters, ethers, acetates, and combinations thereof, and preferably has a volatility of 0.2 or more. It is preferable that the organic solvent has a higher volatility, and the upper limit of the volatility is not particularly limited, but may be 5 or less in consideration of process applicability.

Among the alcohols, the monohydric alcohol may include, for example, methanol, ethanol, propanol, butanol, cyclohexanol, and mixtures thereof.

Specific examples of the organic solvent include, but are not limited to, ethyl lactate, ethyl alcohol, propylene glycol methyl ether, propylene glycol methyl ether acetate, and combinations thereof.

The ethers may include, for example, propylene glycol methyl ether, and the acetates may include, for example, propylene glycol methyl ether acetate.

In addition, the esters may include ethyl lactate.

As the organic solvent included in the cleaning solution composition, the same compound as in the example may be used, but as a compound capable of applying improved physical properties by adding the low volatility additive of the present invention, it may be appropriately selected by a person skilled in the art, It is not limited to the description.

The cleaning liquid composition of the present invention may further include conventional additives known in the art to improve cleaning performance.

According to one embodiment, the cleaning solution composition may further include a surfactant as an additional additive.

The surfactant may be additionally added to improve the wetting property on the application surface so that the cleaning solution composition can work evenly on the substrate, improve the foam properties of the additive, and increase solubility in other organic additives.

The surfactant may be at least one selected from the group consisting of nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants.

The nonionic surfactant may be mixed and added with other types of surfactant for the reason that ions are not generated in an aqueous solution state. Nonionic surfactants include, for example, ethoxylated linear alcohols, ethoxylated alkyl phenols, fatty acid esters, amine and amide derivatives, alkylpolyglycosides, ethylene oxide-propylene oxide interpolymers, polyalcohols and ethoxyrays. polyalcohols, thiols and mercaptan derivatives.

The anionic surfactant may include sulfate, sulfonate, organophosphate, sarcoside, alkyl amino acid, and lauryl sarcosinate, for example, alkyl ester sulfate, alkyl ethoxy ether sulfate, dodecyl benzene sulfonate. , alkyl benzene sulfonates, alpha-olefin sulfonates, ligno sulfonates, and sulfo-carboxyl compounds.

The cationic surfactant can be adsorbed to a negatively charged substrate, thereby acting as an antistatic and softening agent. It can also serve as a dispersing agent for solid particles, a floating dust collector, a hydrophobic agent, and a corrosion inhibitor. Cationic surfactants may include, for example, fatty acid amines, quaternary alkyl-ammonium, linear diamines, n-dodecyl pyridinium chloride, imidazole and morpholine compounds.

The amphoteric surfactant has anionic and cationic dissociation in the same molecule and has a certain isoelectric point, for example, amphocarboxylate, alkyl betaine, amidoalkyl betaine, amidoalkyl sultaine, amphophosphate, phosphobene tines, pyrophosphobetaines, carboxyalkyl alkyl polyamines.

As the surfactant, for example, one or more of acetylenediol, alkylamine, alkylcarboxylic acid, and pluronic-based polymer may be used. The pluronic-based polymer may include, for example, a block copolymer of ethylene oxide and propylene oxide.

Surfactants that may be included in the cleaning solution composition may be those generally used in the art, but are not limited to the surfactants described above.

The surfactant may be added in an amount of 0.0005 to 5 parts by weight based on 100 parts by weight of the cleaning solution composition, for example, 0.001 to 2 parts by weight of a nonionic surfactant, an amphoteric surfactant, or a mixture thereof. there is. If the surfactant content is not appropriate, the effect of improving the wettability, improving the foam properties of the additive, and increasing the solubility in other organic additives may not be expected, or the surfactant precipitation problem may occur due to the problem of solubility.

When such additives are additionally blended, the blending amount can be appropriately selected according to the purpose of use of each additive, but from the viewpoint of not impairing the effects of the present invention, other additives are added to 100 parts by weight of the cleaning solution composition of the present invention. It can be added in the range of 10 weight part or less in total.

The cleaning solution composition according to the present invention preferably does not contain water because sufficient cleaning power is required for water-insoluble polyimide decomposition products.

According to one embodiment, polyimide having heat resistance, coating properties and mechanical strength suitable for film formation, chemical resistance to withstand cleaning after processing, and various structural properties due to the characteristics of high-temperature process conditions may be used as the main material of the alignment layer. .

Therefore, according to one embodiment, the cleaning solution composition may be used in the polyimide alignment layer manufacturing process. The manufacturing process may be a manufacturing process of an alignment layer formed using polyimide, a polyamic acid derivative, and a combination thereof.

The alignment layer may include, for example, polyvinyl cinamate, polysiloxane, maleimide, and the like, and may include, for example, a polyimide-based compound including a photoreactive group in a side chain as a photopolymerization material.

As the type of polyimide, for example, wholly aromatic polyimide using compression sintering molding method, thermoplastic polyimide, thermosetting polyimide, melt molding polyimide, organic solvent soluble polyimide, low thermal expansion polyimide, low stress polyimide Mid, colorless and transparent polyimide, photosensitive polyimide, polyimide for high-strength high modulus fiber, etc. can be illustrated.

According to one embodiment, as the type of the alignment layer to which the cleaning solution composition according to the present invention can be applied, for example, PVA (Patterned Vertical Alignment), TN (Twisted Nematic), VA (Vertical Alignment), MVA (Multi- domain Vertical Alignment), In-Plane Switching (IPS), and Optically Compensated Bend (OCB) may be exemplified.

According to an exemplary embodiment, the cleaning solution composition may be used in a manufacturing process such as a photoisomerization method, a photolysis method, and a photocuring method as an alignment film manufacturing process.

Although there is no limitation in the manufacturing method to which the cleaning liquid composition according to the present invention can be applied, for example, a rubbing process, an ultraviolet irradiation process, etc. may be mentioned. The rubbing-related process may cause deterioration of display performance and production yield due to problems of damage to the transistor due to static electricity generation, dust adsorption, and scratch formation due to the difficulty in fine-tuning parameters in the rubbing-related process. In order not to prevent such a problem, a polarized UV irradiation technique may be used as a method for manufacturing a liquid crystal alignment layer without physical contact. The composition according to the present invention is particularly effective for cleaning a photo-alignment film produced by an ultraviolet irradiation process.

Therefore, according to one embodiment, the cleaning solution composition according to the present invention may be used in a process for manufacturing a photo-alignment layer of a polyimide film.

The cleaning method using the aqueous cleaning solution composition of the present invention is not particularly limited, and it can be treated using an immersion cleaning method, a shaking cleaning method, an ultrasonic cleaning method, a spray cleaning method, a puddle cleaning method, a brush cleaning method, and the like.

The present invention can apply various transformations and can carry out various embodiments. Hereinafter, the embodiments are illustrated in the drawings and described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them. . The following examples are only for illustrating the present invention, and the content of the present invention is not limited by the following examples, and all transformations, equivalents or substitutes included in the spirit and scope of the present invention should be understood.

Examples 1 to 10 and Comparative Examples 1 to 6

The volatility of the low volatility additive used was measured relative to that of n-butyl acetate. 2 g each of the low-volatile additive sample used in Experimental Example 1 was placed in a round silver plate, and left at room temperature (25° C.) to measure the change in the amount of the sample over 5 hours. The volatilization amount of normal butyl acetate was set as a reference value of 1, and relative volatility was measured by comparing the volatilization amounts of other compositions.

The cleaning solution compositions of Examples 1 to 10 and Comparative Examples 1 to 6 were prepared according to the composition of Table 1 below, and the unit of content is parts by weight.

division organic solvent 1 organic solvent 2 low volatility additives
(Ratio of input to organic solvent) type content type content type content Example 1 EL 100 - - MEG One Example 2 EL 100 - - PEG One Example 3 EL 100 - - BDG One Example 4 EL 100 - - NMP One Example 5 EL 100 - - DMSO One Example 6 EL 100 - - PEG 5 Example 7 Et-OH 100 - - PEG One Example 8 EL 50 Et-OH 50 PEG One Example 9 EL 50 PGME 50 PEG One Example 10 EL 50 PGMEA 50 PEG One Comparative Example 1 EL 100 - - - - Comparative Example 2 EL 100 - - PEG 0.05 Comparative Example 3 Et-OH 100 - - - - Comparative Example 4 EL 50 PGME 50 - - Comparative Example 5 EL 50 PGMEA 50 - - Comparative Example 6 - - Et-OH 100 BDG 50

The abbreviations and relative volatility and hydrophile-lipophile balance (HLB) values used in Table 1 are as follows.

division Relative volatility
(Normal butyl acetate nBA=1, standard) Solubility in 100 g of water
(Notation of dissolution amount) EL: ethyl lactate 0.214 50g or more Et-OH: ethyl alcohol 1.70 50g or more PGME: propylene glycol methyl ether 0.814 50g or more PGMEA: propylene glycol methyl ether acetate 0.368 50g or more MEG: monoethylene glycol 0.01 50g or more PEG: polyethylene glycol (molecular weight: 200) 0.01 or less 50g or more BDG: Butyldiglycol 0.003 50g or more NMP: N-methylpyrrolidone 0.03 50g or more DMSO: dimethyl sulfoxide 0.026 50g or more

Experimental Example 1: Evaluation of cleaning performance and alignment film damage

After coating polyimide on bare glass, it was fired at 230° C. to form a polyimide film to a thickness of 1,000 Å, followed by UV irradiation. It was cut into a size of 50 mm x 50 mm and used as an evaluation specimen.

Examples and Comparative Examples 300 g of the evaluation chemical solution according to each composition was filled in a double-jacketed beaker container, and then stirred at a speed of about 300 rpm using a magnetic stirrer while maintaining the temperature condition at 50° C. using a constant temperature circulation tank.

The cleaned specimen was sprayed for about 30 seconds at a pressure of 1.0 kgf/cm ² using a nitrogen (N ₂ ) injection device fixed to a 90 degree angle and a height of about 50 mm.

Thereafter, deionized water (DIW) was sprayed and rinsed for 1 minute, followed by drying with nitrogen.

The cleaning state of the specimen was observed using an optical microscope (BX51TRF, Olympus) and a scanning electron microscope (S-4800, Hitach), and the results are shown in Table 3 below.

division alignment film cleaning state
Ⅹ (very poor), △ (poor),
○ (good), ◎ (very good) light microscope scanning electron microscope Example 1 ◎ ◎ Example 2 ◎ ◎ Example 3 ◎ ◎ Example 4 ◎ ◎ Example 5 ◎ ◎ Example 6 ◎ ◎ Example 7 ◎ ◎ Example 8 ◎ ○ Example 9 ◎ ○ Example 10 ◎ ◎ Comparative Example 1 Ⅹ Ⅹ Comparative Example 2 △ Ⅹ Comparative Example 3 Ⅹ Ⅹ Comparative Example 4 Ⅹ Ⅹ Comparative Example 5 Ⅹ Ⅹ Comparative Example 6 Ⅹ Ⅹ

As shown in Table 3, it can be seen that in Examples 1 to 10 containing the low-volatile additive according to the present invention, defects hardly occur after cleaning the alignment layer. In particular, in the case of Example 2, as shown in FIG. 4 , it can be seen that the surface state of the film after cleaning the alignment film has no residual decomposition products, and the polyimide alignment film is not damaged, showing very good results. On the other hand, in Comparative Examples 1, 3, 4, and 5 that do not contain the low-volatile additive, it can be seen that many defects occur after cleaning the alignment layer, and as shown in FIG. It can be seen that shows very poor results due to residual decomposition products and damage to the alignment layer. In addition, although Comparative Example 2 contains a low volatility additive, it can be confirmed that the cleaning effect is poor because the content of the additive is not sufficient to exhibit the effect.

In addition, in the case of Comparative Example 6, it can be seen that the poor result is shown due to the problem of insufficient cleaning of the alignment layer due to the decrease in the ratio of the organic solvent according to the increase in the amount of the low volatile additive and the problem of rinsing due to the increase of the viscosity.

Therefore, by using the cleaning solution composition according to the present invention in the polyimide photo-alignment film cleaning process, it can be confirmed that the contamination defect requirements such as precipitates and adhesions that may be generated from the polyimide decomposition product are improved, and thus the cleaning performance is improved. .

As the specific parts of the present invention have been described in detail above, for those of ordinary skill in the art, these specific descriptions are only preferred embodiments, thereby limiting the scope of the present invention to the specific embodiments described above. it is not going to be

Claims (8)

100 parts by weight of an organic solvent having a volatility exceeding 0.1, and
Contains 0.1 to 20 parts by weight of a low volatility hydrophilic additive having a volatility of 0.1 or less,
The volatility is the relative volatility based on the volatility 1 of normal butyl acetate,
However, when the low volatility hydrophilic additive includes an alcohol, the alcohol includes two or less hydroxyl groups. delete The cleaning solution composition according to claim 1, wherein the low volatility hydrophilic additive has a solubility of 20 g or more in 100 g of water. The cleaning solution composition according to claim 1, wherein the low volatility hydrophilic additive is selected from alcohols, ethers, pyrrolidones, sulfoxides, and combinations thereof having a vapor pressure of 1 mmHg or less. According to claim 1, wherein the low volatility hydrophilic additive is ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, glycerol, butyl diglycol, methyl pyrrolidone, diethylene glycol monoethyl ether, diethylene A cleaning solution composition selected from glycol monomethyl ether, dipropylene glycol monomethyl ether, dimethyl sulfoxide, and combinations thereof. The cleaning solution composition according to claim 1, wherein the organic solvent is selected from alcohols, ethers, esters, acetates, and combinations thereof. The cleaning solution composition according to claim 1, wherein the organic solvent comprises ethyl lactate, ethyl alcohol, propylene glycol methyl ether, propylene glycol methyl ether acetate, and combinations thereof. The cleaning solution composition according to any one of claims 1 to 7, wherein the composition is used for cleaning the alignment layer.

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