Method for preparing display panel coating composition, and display panel coating composition prepared using same

Abstract

The present invention relates to a method for preparing a display panel coating composition, and a coating composition prepared using same. The method for preparing a coating composition comprises the steps of: (S100) stirring, at room temperature and at atmospheric pressure, raw materials comprising a main material and an initiator, so as to form a first homogeneous mixture; (S200) removing, under reduced pressure, moisture or gaseous substances from the first homogeneous mixture so as to form a second homogeneous mixture; and (S300) removing particulate substances from the second homogeneous mixture by using a microfilter.

Description

Method for manufacturing a coating composition for a display panel and a coating composition for a display panel manufactured thereby

[0001] The present invention relates to a method for manufacturing a coating composition for a display panel and a coating composition for a display panel manufactured thereby. Specifically, it relates to a method for manufacturing a coating composition capable of improving the reliability and productivity of a display panel and a coating composition for a display panel manufactured thereby.

[0002] As various display devices such as liquid crystal displays (LCDs), plasma display panels (PDPs), electroluminescent displays (ELDs), and cathode ray tube displays (CRTs) advance, high performance and high reliability are required for coating materials used in display panels. In particular, to improve efficiency, display panels form a high-refractive index film on the panel using a coating composition. The high-refractive index film can bond the display panel to other components, such as color filters.

[0003] Generally, coating compositions are synthesized using precursors such as aliphatic or aromatic structures and organic materials such as toluene. However, various residual impurities, such as aromatic, alicyclic, or aliphatic structures, may be generated during the synthesis process. In particular, residual impurities having aromatic structures cause π-π stacking interactions due to their aromatic structures. These interactions can increase the degassing time by reducing the diffusion rate of outgas.

[0004] Furthermore, gaseous substances were generated in the coating composition due to various residual impurities, and these gaseous substances turned into bubbles during the film formation (drying after application) of the composition. Due to these bubbles, the applied coating composition failed to completely fill the panel, leading to defects in the display panel. Additionally, the gaseous substances continuously affected the display panel, reducing its reliability. Consequently, conventionally, an outgassing process was performed to remove gaseous substances after application during the film formation of the composition. However, removing the bubbles required a significant amount of time. This not only complicated the manufacturing process but also increased production time, resulting in problems such as reduced productivity and reliability of the display panel. Ultimately, the degassing time became a critical factor in the manufacturing of display panels.

[0005] Furthermore, if the moisture content in the coating composition is high, a large amount of gaseous substances or moisture may be generated inside the display panel when heating is performed or the display is used for a long time, which may shorten the lifespan of the OLED (especially the light-emitting layer) or affect the reliability inside the display panel.

[0006] To address these issues, conventional methods have included defoaming agents or defoaming agents as components of the composition to prevent bubble formation during film formation or to rapidly remove existing bubbles. However, during the film formation process of the coating composition, curable materials undergo cross-linking, whereas defoaming agents and defoaming agents do not. As the operating temperature of the display increases, these defoaming agents and defoaming agents exhibit greater mobility than the cross-linked materials within the film, making them highly likely to turn into gas; this gas has degraded the reliability of the display panel.

[0007] The present invention aims to provide a method for manufacturing a coating composition for a display panel that can shorten the bubble degassing time and has a low moisture content, even without including a defoaming agent and / or an antifoaming agent.

[0008] In addition, the present invention aims to provide a coating composition for a display panel that can improve the reliability and productivity of the display panel by being manufactured by the above method.

[0009] The present invention provides a method for manufacturing a coating composition for a display panel, comprising: (S100) a step of forming a first homogeneous mixture by stirring raw materials including a main material and an initiator at room temperature and atmospheric pressure; (S200) a step of forming a second homogeneous mixture by removing moisture or gaseous substances from the first homogeneous mixture under vacuum reduced pressure; and (S300) a step of removing particulate substances from the second homogeneous mixture using a micro filter.

[0010] According to one example, the above-mentioned main material may include an epoxy group-containing material.

[0011] According to another example, the stirring speed of the above (S100) step may be 10 to 500 rpm.

[0012] According to another example, the above (S200) step uses a vacuum pump to 1×10 -1 Up to 1×10 -7 It can be performed for 0.5 to 25 hours at a vacuum of torr.

[0013] According to another example, in step (S300) above, the pore size of the microfilter may be in the range of 0.1 to 5 μm.

[0014] The present invention provides a coating composition for a display panel that is manufactured by the method described above and has a degassing time in the drying process after coating in the range of 30 to 80 seconds.

[0015] According to one example, the coating composition for the display panel may have a moisture content in the range of 20 to 80 ppm.

[0016] By including a vacuum depressurization process and a filtering process, the present invention enables the production of a coating composition for a display panel that has a shortened degassing time and a low moisture content, even without including a defoaming agent and / or an antifoaming agent as components of the composition.

[0017] FIG. 1 is a flowchart illustrating a method for preparing a coating composition according to the present invention.

[0018] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art, and the following embodiments may be modified in various different forms, and the scope of the present invention is not limited to the following embodiments. Throughout this specification, the same reference numerals refer to the same structures.

[0019] Unless otherwise defined, all terms used in this specification (including technical and scientific terms) may be used in a meaning commonly understood by those skilled in the art to which the present invention pertains. Additionally, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise.

[0020] Furthermore, the size and thickness of each component shown in the drawings are depicted arbitrarily for convenience of explanation, and thus the present invention is not necessarily limited to what is illustrated. Thicknesses have been enlarged in the drawings to clearly represent various layers and regions. Additionally, for convenience of explanation, the thickness of some layers and regions has been exaggerated in the drawings.

[0021] Furthermore, throughout the specification, when a part is described as "including" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0022] In addition, throughout the specification, the terms “above” or “on” mean that they include not only cases where they are located above or below the target part, but also cases where there is another part in between, and do not necessarily mean that they are located above with respect to the direction of gravity.

[0023] Furthermore, in this specification, terms such as "first," "second," etc., are used to distinguish components from one another, rather than indicating any arbitrary order or importance.

[0024]

[0025] Generally, a coating composition for a display panel is a composition for forming a high-refractive index film on a display panel. According to one example, the high-refractive index film may be interposed between the display panel and other adjacent components (e.g., color filters, polarizers, color conversion layers, etc.) within a display device to bond them together. However, when forming the high-refractive index film, if the coating composition contains a gaseous substance (a bubble-inducing substance), bubbles may be generated due to the gaseous substance, preventing the coating composition from completely filling the panel. Consequently, defects in the display panel may occur, which may reduce the productivity and reliability of the display panel.

[0026] Accordingly, to ensure the productivity and reliability of display panels, it is desirable for the coating composition to have low outgassing and moisture content. Therefore, conventionally, attempts were made to manufacture coating compositions with low bubble generation and moisture content by using defoaming agents or defoaming agents as components of the coating composition. However, during the film formation (drying after application) process of the coating composition, defoaming agents and defoaming agents do not cross-link. As the operating temperature of the display increases, these defoaming agents and defoaming agents have greater mobility than the cross-linked materials within the film, making them highly likely to turn into gas; this gas degrades the reliability of the display panel.

[0027] Accordingly, the present invention recognized that when manufacturing a coating composition, if a raw material containing a main material and an initiator is stirred and then a vacuum reduced-pressure purification process is performed, moisture or gaseous substances within the composition can be removed without using a defoaming agent or an antifoaming agent.

[0028] In addition, the present invention recognized that if a coating composition contains particulate (foreign) substances having a size (particle diameter) of about 2 μm or more, the reliability of the display may be reduced due to an increase in the defect rate of the display panel caused by the particulate (foreign) substances. To solve this problem, the present invention reduced the defect rate of the display panel by removing particulate substances with a particle diameter of about 2 μm or more from the composition by performing a purification process using a microfilter in addition to a stirring process and a vacuum depressurization purification process. In particular, the content of particulate foreign substances in the coating composition was minimized by using a microfilter of about 0.1 μm or less.

[0029] Accordingly, the present invention sequentially performs a stirring process, a vacuum depressurization purification process, and a purification process using a microfilter on raw materials containing a main material and an initiator. By doing so, the present invention can produce a coating composition that can shorten the degassing time during film formation (drying after solution application) of the composition without the use of a degassing agent or an antifoaming agent. Furthermore, compared to conventional methods using degassing agents or antifoaming agents, the present invention can produce a coating composition with a lower outgassing amount, moisture content, and particulate matter content. Moreover, when a display device is manufactured using the coating composition produced by the present invention, not only is the manufacturing time shortened due to the reduced degassing time, but the defect rate of the display is also reduced, thereby ensuring the productivity and reliability of the display.

[0030] According to one example, a method for manufacturing a coating composition according to the present invention comprises: (S100) a step of forming a first homogeneous mixture by stirring raw materials including a main material and an initiator at room temperature and atmospheric pressure; (S200) a step of forming a second homogeneous mixture by removing moisture or gaseous substances from the first homogeneous mixture under vacuum reduced pressure; and (S300) a step of removing particulate substances from the second homogeneous mixture using a microfilter. However, the method is not limited to the above steps, and the following steps must not be performed sequentially; instead, the steps of each process may be modified or selectively combined according to design specifications. In particular, the order of steps (S200) and (S300) may be changed.

[0031] Hereinafter, with reference to FIG. 1, a method for preparing a coating composition according to the present invention will be described step by step.

[0032] (S100) Step: Raw material stirring step

[0033] First, raw materials including a main material and an initiator are stirred at room temperature and pressure to form a first homogeneous mixture.

[0034] The raw material of the present invention comprises a main material and an initiator. Unlike conventional methods, the raw material does not contain a defoaming agent or an antifoaming agent, nor is a defoaming agent or an antifoaming agent added to the raw material. In this context, "non-containing" means not only substantially not containing a defoaming agent or an antifoaming agent at all, but also containing almost none, or including them in trace amounts that do not affect the characteristics of the composition. For example, the composition prepared according to the present invention may contain a defoaming agent and an antifoaming agent of approximately 0.0001 weight% or less, specifically approximately 0.00001 weight% or less, and more specifically 0 weight%, relative to the total amount of the composition. As such, unlike conventional methods, since the present invention does not use a defoaming agent or an antifoaming agent, gas originating from the defoaming agent and an antifoaming agent is not generated during the film formation (drying after coating) of the composition. Therefore, the coating composition prepared according to the present invention has a lower out-gas amount compared to conventional methods.

[0035] In the present invention, the main component is an organic component (curing component) included in the composition and serves as the matrix component of the high-refractive index film. This main component may be a compound having one or more polymerizable functional groups within its molecule, or an oligomer and / or polymer formed from such a compound. The polymerizable functional groups may include, but are not limited to, epoxy groups, acrylate groups, etc.

[0036] According to one example, the main material may be an epoxy group-containing material. The epoxy group-containing material contains at least one epoxy group (epoxide group) within its molecule, and specifically may include an epoxy monomer, an epoxy oligomer, and an epoxy resin. If the main material includes at least one of an epoxy monomer, an epoxy oligomer, and an epoxy resin, the coating composition prepared according to the present invention may be a high-refractive index epoxy resin composition.

[0037] The above epoxy resin is a thermosetting resin capable of forming a three-dimensional network structure after curing. Furthermore, the epoxy resin exhibits excellent heat resistance, water resistance, and moisture resistance, which can improve the thermal reliability of high-refractive index films. Additionally, the epoxy resin can impart excellent mechanical strength, electrical insulation, and chemical resistance to high-refractive index films.

[0038] The epoxy resin usable in the present invention is a polymer containing at least one epoxide group in its molecule, and it is preferable that the epoxy resin does not contain halogen atoms such as bromine in its molecule, or contains them in an amount of about 1000 ppm or less, so as to substantially not contain them. In addition, the epoxy resin may not only contain silicon, urethane, polyimide, polyamide, etc. in its molecule, but may also contain phosphorus atoms, sulfur atoms, nitrogen atoms, etc.

[0039] Non-limiting examples of such epoxy resins include fluorene skeleton-containing epoxy resins, biphenyl skeleton-containing epoxy resins, spiro-biphenyl epoxy resins, cyclo-aliphatic epoxy resins, novolac skeleton-containing epoxy resins, dicyclopentadiene skeleton-containing epoxy resins, bisphenol skeleton-containing epoxy resins, diphenyl alkylene skeleton-containing epoxy resins, triazine skeleton-containing epoxy resins, triphenol alkylene skeleton-containing epoxy resins, xylylene skeleton-containing epoxy resins, and biphenyl aralkyl epoxy resins. These may include aralkyl skeleton-containing epoxy resins, naphthalene skeleton-containing epoxy resins, alicyclic skeleton-containing epoxy resins, furanyl skeleton-containing epoxy resins, etc., and these may be used alone or in a mixture of two or more types.

[0040] Specifically, the epoxy resin is novolac epoxy resin, dicyclopentadiene epoxy resin (DCPD epoxy resin), bisphenol epoxy resin, diphenylethylene epoxy resin, triazine epoxy resin, fluorene epoxy resin, dimethyl fluorene epoxy resin, diphenyl fluorene epoxy resin, triphenol methane epoxy resin, biphenyl epoxy resin, xylylene epoxy resin, biphenyl phenyl methyl epoxy resin, naphthyl epoxy resin, and 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarbolsylate It may be a resin (3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate resin), furanyl epoxy resin, etc., but is not limited thereto.

[0041] According to one example, the above-mentioned main material may include one or more selected from the group consisting of biphenyl epoxy resin, fluorene epoxy resin, diphenyl fluorene epoxy resin, spiro-biphenyl epoxy resin, and cycloaliphatic epoxy resin.

[0042] In the present invention, the initiator is a substance that induces (initiates) a polymerization reaction, and may be, for example, a cationic initiator.

[0043] Cationic initiators can generate cations or Lewis acids by irradiation with active energy lines such as visible light, ultraviolet rays, X-rays, or electron beams, or by heating, and can initiate the polymerization reaction of epoxy groups. In addition, cationic initiators can also cure epoxy resins.

[0044] According to one example, the cationic initiator may be a cationic thermal initiator, a latent cationic initiator, or both. The cationic thermal initiator acts catalytically at heat. When a latent cationic initiator is mixed with the cationic thermal initiator, storage stability or workability may be improved. Cationic thermal initiators usable in the present invention include, but are not limited to, Blend of amine phosphate and phenyl amine borates, Sanaid SI B3A [((4-Acetoxyphenyl)benzyl(methyl)sulfonium, tetrakis(pentafluorophenyl)borate (1:1))], Sanaid SI B3 [(benzyl(4-hydroxyphenyl)methylsulfonium, tetrakis(pentafluorophenyl)borate (1:1))], Sanaid SI-80 [(4-Hydroxyphenyl)(2-methylbenzyl)methylsulfonium hexafluoroantimonate], Sanaid SI-100 [Benzyltetramethylenesulfonium hexafluoroantimonate], Sanaid SI-110, Sanaid SI 360 [(4-hydroxyphenyl)methyl(1-naphthalenylmethyl)sulfonium,hexafluorophosphate)].

[0045] The content of such initiator is not particularly limited and, for example, may be about 1 to 10 parts by weight, specifically about 1 to 6 parts by weight, specifically about 1 to 3 parts by weight, based on 100 parts by weight of epoxy resin.

[0046] Optionally, additives known in the art (except for defoaming agents and defoaming agents) may be additionally added to the raw material as needed, within a range that does not impair the physical properties of the coating composition. Examples of additives include, but are not limited to, fillers, coupling agents, UV absorbers, antioxidants, polymerization initiators, dyes, pigments, dispersants, thickeners, leveling agents, and coloring agents. The content of such additives may be as known in the art, for example, about 0.0001 to 10 weight percent based on the total amount of the coating composition.

[0047] Once the aforementioned main ingredient and initiator are prepared, they are injected (introduced) into a reactor (e.g., reaction tank) equipped with a stirrer, either all at once or sequentially, and then uniformly stirred by the stirrer. By doing so, the present invention can obtain a material (first homogeneous mixture) in which the main ingredient and the initiator are uniformly mixed.

[0048] The material of the above reactor is not particularly limited and may be, for example, stainless steel. The above stainless steel has excellent corrosion resistance, heat resistance, and pressure resistance, so it can not only stably stir even under high temperature and high pressure, but also prevent the raw material from being contaminated by impurities.

[0049] In the above step (S100), the main component and the initiator can be uniformly stirred using a stirrer at a stirring speed of about 10 to 500 rpm, specifically about 20 to 300 rpm, more specifically about 25 to 200 rpm. If the stirring speed is less than 10 rpm, the main component and the initiator may not be able to form a uniform state. Meanwhile, if the stirring speed exceeds 500 rpm, the mixture may splash onto the walls of the reactor, and if the mixture splashed onto the walls is exposed for a long time, it may solidify and be detected as a foreign substance.

[0050] The above-mentioned stirrers are those generally known in the field, such as rotary blade stirrers, magnetic stirrers, vibrating stirrers, ultrasonic stirrers, etc., but are not limited thereto.

[0051] The above stirring process can be performed at room temperature (e.g., about 20±5℃) and atmospheric pressure (e.g., 0.9~1.1 atm).

[0052] (S200) Step: Removal of moisture and / or gaseous substances

[0053] Afterwards, moisture or gaseous substances are removed from the first homogeneous mixture obtained in step (S100) under vacuum pressure to obtain a second homogeneous mixture.

[0054] The above (S200) step is a vacuum reduced pressure purification process, using a vacuum pump to 1×10 -1 Up to 1×10 -7 It can be performed for about 0.5 to 25 hours at a vacuum level of torr. If the vacuum decompression purification time is too short, less than 0.5 hours, moisture or gaseous substances are not removed, and the degassing time cannot be shortened. On the other hand, if the vacuum decompression purification process is performed for too long, exceeding about 25 hours, a large amount of volatile substances may be removed, and the viscosity may increase. Also, if the vacuum level is too weak, the vacuum decompression purification may take a long time.

[0055] As described above, by performing step (S200), moisture and gaseous substances in the first homogeneous mixture are removed. Accordingly, the present invention can control the moisture content (moisture concentration) of the final coating composition to within the range of 20 to 80 ppm. In addition, when the final coating composition prepared according to the present invention is film-formed (dried after application), the degassing time after application can be shortened to about 30 to 80 seconds.

[0056] (S300) Step: Removal of particulate matter from the mixture

[0057] Next, particulate matter is removed from the second homogeneous mixture obtained in step (S200) using a microfilter. By doing so, the present invention can obtain a homogeneous coating composition with a low amount of outgassing and moisture, and with minimized particulate matter.

[0058] The above step (S300) is a precision filtration purification process that can remove particulate matter from the second homogeneous mixture through a porous medium (filter medium). At this time, one or more microfilters may be used. However, to prevent overloading of the filters, multiple filters, for example, 2 to 6 filters may be used. According to one example, 2 to 4 microfilters may be used when performing step (S300).

[0059] The microfilters usable in the present invention are not particularly limited as long as they are generally known in the art. However, if large particulate foreign substances with a particle size exceeding about 2 μm are present in the final coating composition, said particulate substances may cause defects in the panel. Therefore, in the present invention, it is preferable to use a microfilter with a pore size of about 0.05 to 5 μm, specifically in the range of about 0.1 to 5 μm, and more specifically in the range of about 0.1 to 2 μm. By doing so, the number of particulate foreign substances with a maximum particle size of 0.1 to 2 μm in the final coating composition can be controlled to 20 or fewer.

[0060] If multiple microfilters are arranged sequentially, it is appropriate that the pore size of at least the microfilter placed at the end is within the aforementioned range.

[0061] The purification time in this step may be about 40 to 100 hours, specifically about 40 to 80 hours, more specifically about 40 to 60 hours.

[0062] Optionally, the coating composition obtained in step (S300) can be filled into a canister or the like for storage.

[0063] The material of the above canister may be stainless steel, etc. This prevents foreign substances from being mixed into the final coating composition.

[0064]

[0065] The coating composition manufactured through the method of the present invention described above forms a high-refractive index film on the surface of a display panel by coating the surface of the panel. The content of gaseous substances (e.g., toluene) is about 1.5% or less of the total gaseous substances, and the moisture content is in the range of about 20 to 80 ppm, so the amount of outgassing or moisture is low. Accordingly, the coating composition of the present invention has a very short degassing time after coating in the film formation process (drying process after coating), in the range of about 30 to 80 seconds. In addition, the coating composition of the present invention contains a content of particulate substances with a particle size of 2 μm or more at a level of substantially zero, and also contains a small amount of particulate substances with a particle size of about 0.5 to 2 μm, such as about 20 or fewer, so the defect rate caused by foreign substances can be reduced.

[0066] As such, the coating composition of the present invention reduces the degassing time and the defect rate during film formation (drying after coating), thereby shortening the coating time and reducing costs, which not only improves the productivity of the display but also enhances the reliability of the display. Furthermore, unlike conventional methods, the coating composition of the present invention does not require the inclusion of degassing agents or defoaming agents. Therefore, the amount of gaseous substances generated by degassing agents or defoaming agents is zero, which further improves the reliability of the display compared to conventional methods.

[0067]

[0068] Meanwhile, when manufacturing the aforementioned coating composition, the present invention may utilize a manufacturing apparatus for the coating composition comprising: a reaction tank equipped with a stirrer; a vacuum purification unit equipped with a vacuum pump; and a microfilter. To avoid duplication, the description of components already described is omitted.

[0069] The apparatus for manufacturing the coating composition includes a first connecting part (e.g., a connecting pipe) connecting the reaction tank and the vacuum purification unit, and a second connecting part (e.g., a connecting pipe) connecting the vacuum purification unit and the filter. In this case, the material of each connecting part may be stainless steel, Teflon, silicone, etc., to ensure the reliability of the process equipment and prevent the ingress of foreign substances.

[0070]

[0071] The present invention will be described in detail below through examples, but the following examples and experimental examples are merely illustrative of one form of the present invention, and the scope of the present invention is not limited to the following examples and experimental examples.

[0072] <Example 1>

[0073] 33 wt% of (3',4'-Epoxycyclohexane)methyl 3,4-epoxycyclohexylcarboxylate, 44.4 wt% of 2-biphenylyl glycidyl ether, and 21.5 wt% of bisphenol A-bisphenol A diglycidyl ether polymer were introduced into a reaction tank along with 1.1 wt% of a cationic thermal initiator based on a blend of amine phosphate and phenyl amine borates. Subsequently, a first homogeneous mixture was obtained by stirring at room temperature (approx. 25 ℃) and atmospheric pressure (approx. 1 atm) using a stirrer mounted on the reaction tank to ensure the raw materials had a homogeneous composition. At this time, the stirring speed of the stirrer was approximately 50 rpm. Afterward, the first homogeneous mixture was introduced into a vacuum purification unit, and the first homogeneous mixture was purified under reduced vacuum pressure to obtain a second homogeneous mixture from which moisture and gaseous substances had been removed. At this time, the vacuum time is approximately 18 hours, and the vacuum pump pressure (vacuum level) is approximately 0.05 × 10⁻⁶ -1 The torr was. Subsequently, a coating composition was prepared by removing particulate matter (maximum particle size: greater than 2 μm) from the second homogeneous mixture for about 100 hours using four microfilters (pore size of the filter: approximately 0.1 to 1 μm, pore size of the filter arranged at the end: 0.1 μm). At this time, the four microfilters were arranged in the order of the first microfilter (pore size: 1 μm) - the second microfilter (pore size: 0.5 μm) - the third microfilter (pore size: 0.2 μm) - the fourth microfilter (pore size: 0.1 μm). The number of particulate foreign substances with a maximum particle size of about 0.5 to 2 μm in the prepared coating composition was about 20 or fewer.

[0074]

[0075] <Example 2> and <Reference Example 1> to <Reference Example 3>

[0076] A coating composition was prepared by performing each process in the same manner as Example 1, except that each process was performed according to the process conditions listed in Table 1 below.

[0077]

[0078] <Comparative Example 1>

[0079] A coating composition was prepared in the same manner as in Example 1, except that BYK-1794 was further added as a defoaming agent when preparing the first homogeneous mixture in Example 1. At this time, the content of the defoaming agent was 0.5 parts by weight when the total content, which is the sum of the content of the main material used in Example 1 and the content of the cationic thermal initiator, was considered to be 100 parts by weight.

[0080]

[0081] <Comparative Example 2>

[0082] A coating composition was prepared by performing the same procedure as in Example 1, except that instead of introducing the first homogeneous mixture into a vacuum purification unit and purifying it under reduced vacuum pressure in Example 1, particulate matter was removed from the first homogeneous mixture using four microfilters for 90 hours.

[0083]

[0084] <Comparative Example 3>

[0085] A coating composition was prepared by performing the same procedure as in Example 1, except that the microfilter used in Example 1 was not used.

[0086]

[0087] Item Example 1 Example 2 Reference Example 1 Reference Example 2 Reference Example 3 Stirring Speed ​​(rpm) 50 50 60 0 10 50 Vacuum Time (h) 15 20 30 5 35 Vacuum Pump Vacuum Level (torr) 0.05 × 10⁻⁶ -1 0.05×10 -1 0.5×10 -1 0.05×10 -1 0.5×10 -1 Particulate foreign matter purification time (h) 100 60 100 20 110 Pore size of terminal filter (㎛) 0.1 0.1 0.1 0.11

[0088] Item Comparison Example 1 Comparison Example 2 Comparison Example 3 Stirring Speed ​​(rpm) 50 50 50 Vacuum Time (h) 18 18 Vacuum Pump Vacuum Level (torr) 0.05 × 10⁻⁶ -1 -0.05×10 -1 Particulate foreign matter purification time (h) 100 900 Pore size of terminal filter (㎛) 0.1 0.1-

[0089]

[0090] <Evaluation Example 1>

[0091] The moisture content, degassing time during curing, and particulate matter content of the coating compositions of Examples 1 and 2 and Reference Examples 1 to 3 were evaluated as follows, and the results are shown in Table 3.

[0092] (a) moisture content

[0093] The moisture content in the coating composition was measured using a Karl Fischer moisture meter.

[0094] (b) Desorption time

[0095] Approximately 0.1 kg of coating composition was dispensed onto a slide glass using a dispensing device, and the slide glass with the dispensed composition was placed in a chamber and subjected to vacuum depressurization to measure the time required for air bubbles to be removed from the composition film. Here, the removal of air bubbles was confirmed visually.

[0096] (c) Content of gaseous substances

[0097] After analyzing the coating composition using gas chromatography-mass spectrometry, the results were indicated as follows based on the detected amount of gaseous substances (i.e., the sum of the areas of the detected components).

[0098] - Detected amount is 250,000,000 or more: ◎

[0099] - Detected amount exceeding 150,000,000 and less than 250,000,000: ○

[0100] - Detected amount 150,000,000 or less: △

[0101] (d) Content of particulate matter

[0102] The coating composition was diluted in acetone at a weight ratio of 1:1, and then the number of particulate matter particles with a maximum particle size of 2 μm or more in the composition was analyzed using a real-time liquid particle counter from RION.

[0103] (e) liquid haze

[0104] The liquid haze of the coating composition was analyzed using a haze meter (product name: NDH 8000, manufacturer: Nippon Denshoku).

[0105] - Analysis conditions: Quartz cell; Light source: White LED, Measurement beam: Φ14mm, Incident aperture: Φ25mm

[0106] Examples Reference Preliminary Comparative Example 1 2 1 2 3 1 2 3 Moisture content (ppm) 49 40 5 4 2 5 5 49 47 38 9 4 6 Degassing time (sec) 5 1 4 5 8 1 300 or more 6 0 1 2 300 or more 4 8 Gaseous substances △△○ ◎△△◎△ 2 ㎛ or larger Number of particulate foreign substances (pieces) 0 0 0 8 1 1 0 3 2 Liquid phase haze 0.0 4 0.0 3 0.0 4 0.0 5 0.0 6 4 7.7 1 0.0 5 0.0 4

[0107] As shown in Table 3, the coating compositions prepared in Examples 1 and 2 had a moisture content of 50 ppm or less, a degassing time of 45 to 51 seconds during curing, and zero particulate matter with a maximum particle size of 2 μm or more. In particular, as the vacuum level and vacuum depressurization time increased, the moisture content and degassment time of the compositions tended to decrease. On the other hand, the coating composition of Comparative Example 1, to which a defoaming agent was applied, had a short degassment time and a small number of particulate foreign substances; however, it was visibly very cloudy and opaque due to high liquid haze, so it was estimated that this would increase the defect rate during the subsequent production of display panels. Furthermore, the coating composition of Comparative Example 2, which did not undergo vacuum depressurization purification, had a high moisture content of 389 ppm and a degassment time of over 300 seconds, so it was estimated that a significant amount of time would be required for degassment during future mass production. Additionally, the coating composition of Comparative Example 3, which did not use a microfilter, had an excessively large number of particulate foreign substances.

[0108] Therefore, it was confirmed that the coating composition prepared according to the present invention can secure the productivity of the display because the degassing time is shortened due to the reduction of gaseous foreign substances.

Claims

1. (S100) A step of forming a first homogeneous mixture by stirring raw materials including a main material and an initiator at room temperature and atmospheric pressure; (S200) A step of forming a second homogeneous mixture by removing moisture or gaseous substances from the first homogeneous mixture under vacuum reduced pressure; and (S300) A step of removing particulate matter from the second homogeneous mixture using a microfilter. A method for manufacturing a coating composition for a display panel comprising 2. In Paragraph 1, A method for manufacturing a coating composition for a display panel, wherein the above-mentioned main component comprises an epoxy group-containing material.

3. In Paragraph 1, A method for manufacturing a coating composition for a display panel, wherein the stirring speed of the above step (S100) is 10 to 500 rpm.

4. In Paragraph 1, The above (S200) step uses a vacuum pump to 1×10 -1 Up to 1×10 -7 A method for manufacturing a coating composition for a display panel, wherein the method is performed for 0.5 to 25 hours at a vacuum of torr.

5. In Paragraph 1, A method for manufacturing a coating composition for a display panel, wherein, in step (S300) above, the pore size of the microfilter is in the range of 0.1 to 5 μm.

6. A coating composition for a display panel manufactured by the method described in any one of claims 1 to 5, wherein the degassing time during the drying process after coating is in the range of 30 to 80 seconds.

7. In Paragraph 6, Coating composition for a display panel having a moisture content in the range of 20 to 80 ppm.

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