Positive photosensitive resin composition

Abstract

A positive-type photosensitive resin composition and a manufacturing method using the same are disclosed. The positive-type photosensitive resin composition includes a polymer resin containing i) 5 to 95 wt % of a polyimide precursor having a structural unit represented by Chemical Formula 1, ii) 5 to 95 wt % of a polyimide precursor having a structural unit represented by Chemical Formula 2, and iii) 0 to 20 wt % of a polyimide precursor having a structural unit represented by Chemical Formula 3; 5 to 50 parts by weight of a quinone diazide compound relative to 100 parts by weight of the polymer resin; and 100 to 2,000 parts by weight of a solvent relative to 100 parts by weight of the polymer resin.

Description

[Technical Field]

[0001] The present invention relates to a positive photosensitive resin composition, and more particularly to a positive photosensitive resin composition used in display devices. [Background technology]

[0002] Recently, OLED (Organic Light Emitting Diodes), especially AMOLED (Active Matrix OLED), has been gaining attention among display devices for various reasons.

[0003] OLED devices typically include an organic insulating film, which is typically formed using a polyimide photosensitive resin composition. Among the polyimide precursors used in conventional polyimide photosensitive resin compositions, polyamic esters are typically substituted with alkyl groups. However, alkyl-substituted polyamic esters have poor solubility control and low sensitivity, making it urgently necessary to find solutions to address these issues. Summary of the Invention [Problem to be solved by the invention]

[0004] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a positive photosensitive resin composition which has an easily adjustable solubility and which has a significantly improved sensitivity. [Means for solving the problem]

[0005] In order to achieve the above object, the present invention provides a positive photosensitive resin composition comprising: i) a polymer resin containing 5 to 95% by weight of a polyimide precursor having a structural unit represented by the following chemical formula 1; ii) 5 to 95% by weight of a polyimide precursor having a structural unit represented by the following chemical formula 2; and iii) 0 to 20% by weight of a polyimide precursor having a structural unit represented by the following chemical formula 3; 5 to 50 parts by weight of a quinone diazide compound relative to 100 parts by weight of the polymer resin; and 100 to 2,000 parts by weight of a solvent relative to 100 parts by weight of the polymer resin. [Chemical formula 1] TIFF0007801224000001.tif37170 [Chemical formula 2] TIFF0007801224000002.tif45170 [Chemical formula 3] TIFF0007801224000003.tif38170

[0006] In the above chemical formulas 1 to 3, R1 and R2 are each independently an organic group having 5 to 30 carbon atoms, in which hydrogen can be substituted with a hydroxyl group (OH), methyl, or fluorine, and methylene can be substituted with oxygen or nitrogen, and R3 is a substituent derived from epoxy.

[0007] The present invention also provides a display element comprising a driving circuit, a planarization layer, a first electrode, an insulating layer, a light-emitting layer, and a second electrode on a substrate, wherein at least one of the planarization layer and the insulating layer is formed from the positive photosensitive resin composition. [Effects of the Invention]

[0008] The positive photosensitive resin composition according to the present invention has easy-to-control solubility, and therefore can improve sensitivity, chemical resistance, adhesive strength, etc., and suppress the occurrence of scum and cracks during pattern formation of display elements such as OLEDs. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing a pattern film formed on an ITO (Indium Tin Oxide) substrate on which a pattern has been formed according to an embodiment of the present invention, and an EL (Electroluminescent Lighting) layer deposited thereon. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will now be described in further detail. In this specification, "*" means the same or different atom or moiety connected in a chemical formula. The positive photosensitive resin composition according to the present invention comprises a polymer resin, a quinonediazide compound, and a solvent.

[0011] The polymer resin used in the present invention serves to form a polyimide film by polymerization, and may contain 5 to 95 wt %, specifically 10 to 90 wt %, of a polyimide precursor having a structural unit represented by the following chemical formula 1; 5 to 95 wt %, specifically 50 to 90 wt %, of a polyimide having a structural unit represented by the following chemical formula 2; and 0 to 20 wt %, specifically 0 to 15 wt %, of a polyimide precursor having a structural unit represented by the following chemical formula 3. [Chemical formula 1] TIFF0007801224000004.tif39170 [Chemical formula 2] TIFF0007801224000005.tif47170 [Chemical formula 3] TIFF0007801224000006.tif39170

[0012] In the above chemical formulas 1 to 3, R1 and R2 may each independently be an organic group having 5 to 30 carbon atoms, specifically an organic group having 5 to 20 carbon atoms. Hydrogen in the organic group may be substituted with a hydroxyl group (OH), methyl, or fluorine, and methylene groups may be substituted with oxygen or nitrogen. R3 is a substituent derived from epoxy, specifically a substituent represented by the following chemical formula 4. [Chemical formula 4] TIFF0007801224000007.tif43170

[0013] In the above Chemical Formula 4, R4 is a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms, and the hydrogen of the alkyl group can be substituted with 1 to 3 fluorine atoms or hydroxyl groups, and the methylene group can be substituted with an alkenyl group, oxygen, nitrogen, ester (COO) or carbonyl (C=O).

[0014] As the substituent represented by Chemical Formula 4, R3 is suitably a compound derived from a compound selected from the group consisting of epoxycyclohexylmethyl methacrylate (ECMMA), 1,2-epoxy-4-vinylcyclohexane, 3,4-(epoxycyclohexane)methyl-3',4'-epoxycyclohexylcarboxylate, and 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate modified epsilon-caprolactone. In particular, when there is an alkyl or alkyne structure as a cyclohexyl terminal substituent, such as 1,2-epoxy-4-vinylcyclohexane, it can be used as an insulating film for OLEDs because it has better thermal stability than carboxylate, but is not limited thereto.

[0015] The polymer resin is produced by polymerizing the structural components of the aromatic dianhydride and diamine, for example, in a molar ratio of 1:0.6 to 1:1.4. If the molar ratio of the structural components of the aromatic dianhydride and diamine is not within the range, the molecular weight of the resin will be less than 3,000, resulting in weakened mechanical and thermal properties.

[0016] The structural component of the aromatic dianhydride may be selected from one or more compounds represented by the following chemical formulas R1-1 to R1-7, which means that the structure of R1 in the polymer resin is a structure derived from the following aromatic dianhydride. [Chemical formula R1-1] TIFF0007801224000008.tif49170 [Chemical formula R1-2] TIFF0007801224000009.tif51170 [Chemical formula R1-3] TIFF0007801224000010.tif70170 [Chemical formula R1-4] TIFF0007801224000011.tif87170 [Chemical formula R1-5] TIFF0007801224000012.tif53170 [Chemical formula R1-6] TIFF0007801224000013.tif54170 [Chemical formula R1-7] TIFF0007801224000014.tif66170

[0017] The structural component of the diamine can be selected from at least one compound represented by the following chemical formulas R2-1 to R2-10, and preferably an aromatic diamine can be used. In the polymer resin, the structure of R2 is derived from the following diamine. [Chemical formula R2-1] TIFF0007801224000015.tif29170 [Chemical formula R2-2] TIFF0007801224000016.tif43170 [Chemical formula R2-3] TIFF0007801224000017.tif25170 [Chemical formula R2-4] TIFF0007801224000018.tif42170 [Chemical formula R2-5] TIFF0007801224000019.tif41170 [Chemical formula R2-6] TIFF0007801224000020.tif55170 [Chemical formula R2-7] TIFF0007801224000021.tif54170 [Chemical formula R2-8] TIFF0007801224000022.tif24170 [Chemical formula R2-9] TIFF0007801224000023.tif69170 [Chemical formula R2-10] TIFF0007801224000024.tif31170

[0018] In the polyimide precursor having the structural unit represented by Chemical Formula 1, the content of the structural unit represented by Chemical Formula 1 is not particularly limited as long as it can increase the development speed of the composition, and may be, for example, 0.1 to 100 mol %, specifically 5 to 100 mol %, based on the number of all repeating units.

[0019] In the polyimide precursor having the structural unit represented by Chemical Formula 1, R3 is a substituent derived from epoxy, thereby producing a material in which a hydroxyl group (OH) is substituted for R3 of the polyamic ester. When a polyimide precursor having a structural unit represented by Chemical Formula 1 containing the hydroxyl group (OH)-substituted polyamic ester structure is used as a photosensitive resin composition, it exhibits faster sensitivity than conventional photosensitive resin compositions without hydroxyl groups. For example, when a positive-type photosensitive resin composition is applied to an OLED substrate, the solvent is evaporated by soft baking, and then light is irradiated, the quinone diazide material changes from hydrophobic to hydrophilic. At this time, if the structural unit represented by Chemical Formula 1 has a hydroxyl group (OH), the development speed is further increased, improving sensitivity.

[0020] The weight-average molecular weight (Mw) of the polyimide precursor having the structural unit represented by Chemical Formula 1 may be 3,000 to 20,000, specifically 3,500 to 10,000. If the molecular weight of the polyimide precursor is too low, the mechanical and thermal properties of the cured resin composition may not be suitable for OLEDs, whereas if the molecular weight is too high, the required integrated light dose, i.e., sensitivity, during the processing of the resin composition may be too slow, resulting in high OLED production costs.

[0021] Polyimides having a structural unit represented by Chemical Formula 2 can control sensitivity. In the structure of Chemical Formula 2, when R2 is substituted with a hydroxy group, sensitivity can be controlled quickly, while when R2 is substituted with fluorine, sensitivity is controlled slowly. In the structural unit represented by Chemical Formula 2, R1 and R2 are the same as those described above.

[0022] The weight-average molecular weight (Mw) of the polyimide having the structural unit represented by Chemical Formula 2 may be 4,000 to 20,000, specifically 3,500 to 10,000. If the molecular weight of the polyimide is too low, the mechanical and thermal properties after curing of the resin composition may be unsuitable for OLEDs, whereas if the molecular weight is too large, the required amount of integrated light, i.e., sensitivity, during the processing of the resin composition may be too slow, resulting in increased OLED production costs.

[0023] The polyimide precursor having the structural unit represented by Chemical Formula 3 has a polyamic acid structure containing a carboxyl group, and when it has a hydroxyl group (OH) like the polyimide precursor having the structural unit represented by Chemical Formula 1, it can further increase the development speed and improve sensitivity. However, if the structural unit represented by Chemical Formula 3 is used in an amount of 20 wt % or more in the resin polymer composition, the development difference between the exposed and unexposed areas, i.e., the contrast ratio, is small, and the function of the photosensitizer is lost. In the structural unit represented by Chemical Formula 3, R1 and R2 are the same as those described above.

[0024] The weight-average molecular weight (Mw) of the polyimide having the structural unit represented by Chemical Formula 3 may be 3,000 to 20,000, specifically 3,500 to 10,000. If the molecular weight of the polyimide precursor is too low, the mechanical and thermal properties of the cured resin composition may not be suitable for OLEDs, whereas if the molecular weight is too large, the required integrated light dose, i.e., sensitivity, during the processing of the resin composition may be too slow, resulting in increased OLED production costs.

[0025] The content of the polyimide precursor having the structural unit represented by Chemical Formula 1 may be 5 to 95 wt %, specifically 10 to 90 wt %, of the total polymer, the content of the polyimide precursor having the structural unit represented by Chemical Formula 2 may be 5 to 95 wt %, specifically 50 to 90 wt %, and the content of the polyimide precursor having the structural unit represented by Chemical Formula 3 may be 0 to 20 wt %, specifically 0 to 15 wt %.

[0026] The polymer resin contains, as its main components, a polyimide precursor having a structural unit represented by Chemical Formula 1 and a polyimide having a structural unit represented by Chemical Formula 2. When the polyimide precursor having a structural unit represented by Chemical Formula 1 or the polyimide having a structural unit represented by Chemical Formula 2 is contained in an amount of less than 5 wt % based on the total polymer resin, photoresist scum and cracks are likely to occur, or photoresist coating properties such as a decrease in chemical resistance may be deteriorated. When the amount is more than 95 wt %, there are problems such as increased sensitivity and cracks.

[0027] The polymer resin includes a polyimide having a structural unit represented by Chemical Formula 2 as a main component, and may include the structure of Chemical Formula 2 in an amount of, for example, 50 to 95 wt %, specifically 60 to 95 wt %, based on the total weight of the polymer resin, and may exhibit coating properties such as chemical resistance and crack prevention effects.

[0028] The quinone diazide compound is a photosensitive material that photoreacts from hydrophobic to hydrophilic before and after light irradiation, and is an essential compound for forming a photosensitive resin composition. It is particularly useful for controlling sensitivity. The quinone diazide compound is obtained by reacting a phenol compound with a naphthoquinone diazide sulfonic acid halide compound, and the phenol compound includes compounds represented by the following chemical formulas 4-1 to 4-3. [Chemical formula 4-1] TIFF0007801224000025.tif115170 [Chemical formula 4-2] TIFF0007801224000026.tif70170 [Chemical formula 4-3] TIFF0007801224000027.tif73170

[0029] In the chemical formulas 4-1 to 4-3, R 31 ~R 36 are each independently a hydrogen atom, a halogen atom, a hydroxy group, an alkyl group having 1 to 4 carbon atoms, or an alkenyl group having 1 to 4 carbon atoms, and R 37 and R 38 are each independently hydrogen, halogen, or an alkyl group having 1 to 4 carbon atoms, and R 39 is hydrogen or an alkyl group having 1 to 4 carbon atoms.

[0030] The content of the quinone diazide compound may be 5 to 50 parts by weight, specifically 10 to 40 parts by weight, based on 100 parts by weight of the polymer resin. If the content of the quinone diazide compound is small, the sensitivity becomes too high, and if it is excessive, scum and cracks may easily occur, and the coating properties of the photoresist, such as a decrease in chemical resistance, may be deteriorated.

[0031] If the viscosity of the solvent is too high, it can cause unevenness and uneven coating thickness when applied to a substrate. To reduce unevenness and uneven coating thickness, a solvent must be mixed with the polymer resin and quinone diazide compound to maintain the appropriate viscosity. The solvent should have a boiling point of 230°C or less and should have excellent solubility for the polymer resin and quinone diazide compound. Examples of suitable solvents include gamma-butyrolactone (GBL), N-methylpyrrolidone (NMP), propylene glycol methyl ether acetate (PGMEA), propylene glycol methyl ether (PGME), ethyl lactate (EL), methyl-3-methoxypropionate (MMP), and mixtures thereof. For example, a molar ratio of gamma-butyrolactone (GBL), methyl-3-methoxypropionate (MMP), and propylene glycol methyl ether (PGME) of 24:20:56 can be used.

[0032] The content of the solvent may be 100 to 2,000 parts by weight, specifically 250 to 1,500 parts by weight, based on 100 parts by weight of the polymer resin. If the content of the solvent is small, there is a problem that solid precipitation may occur during long-term storage of the resin composition, and if the content of the solvent is excessive, there is a problem that an appropriate thickness cannot be achieved during coating in the process of forming an insulating film using the resin composition.

[0033] By applying a positive photosensitive resin composition containing a polymer resin including a polyimide precursor having a structural unit represented by Chemical Formula 1, a polyimide having a structural unit represented by Chemical Formula 2, and a polyimide precursor having a structural unit represented by Chemical Formula 3, a quinone diazide compound, and a solvent to a substrate, the insulating properties between metal films in the substrate can be maintained. In order to complement the characteristics of the insulating film, additives such as a thermal crosslinker, a thermal acid generator, a UV absorber, and a thermal base generator can be added singly or in combination.

[0034] The thermal crosslinking agent performs a crosslinking reaction with the polymer resin to improve the chemical resistance of the photosensitive resin composition. The thermal crosslinking agent is a phenolic compound having the following chemical formula a, and specifically, may contain a functional group represented by the following chemical formula 5. [Chemical formula a] TIFF0007801224000028.tif20170 [Chemical formula 5] TIFF0007801224000029.tif49170 In the above chemical formula 5, A is the above chemical formula a, and in the above chemical formula a, n is an integer of 1 to 6, and Ra is alkyl having 1 to 3 carbon atoms.

[0035] The thermal crosslinking agent preferably includes a structure in which 1 to 4 functional groups represented by Chemical Formula 5 are bonded, and more specifically, it can include compounds represented by the following Chemical Formulas 5-1 to 5-4. [Chemical formula 5-1] TIFF0007801224000030.tif70170 [Chemical formula 5-2] TIFF0007801224000031.tif69170 [Chemical formula 5-3] TIFF0007801224000032.tif81170 [Chemical formula 5-4] TIFF0007801224000033.tif77170 A in the chemical formulas 5-1 to 5-4 is the same as described above.

[0036] The thermal crosslinking agent can be used in an amount of 10 to 50 parts by weight, specifically 10 to 30 parts by weight, per 100 parts by weight of polyimide polymer. If the amount of the thermal crosslinking agent is too small, the chemical resistance effect is lost, and if the amount of the thermal crosslinking agent is too large, when the photosensitive resin composition is coated on a substrate and developed after soft baking, the film thickness is reduced so much that the polymer resin cannot be made thicker than a certain height.

[0037] The thermal acid generator generates acid at a certain temperature or higher, accelerating the crosslinking reaction between the thermal crosslinking agent and the polymer resin. The content of the thermal acid generator is preferably 0.5 to 10 parts by weight per 100 parts by weight of the polyimide polymer. If the amount of the thermal acid generator is too small, it is ineffective, and if the amount of the thermal acid generator is too large, scum is generated.

[0038] When the photosensitive resin composition according to the present invention is applied to a substrate to be used as an insulating film, a UV absorber such as a benzophenone or benzotriazole may be added to prevent deterioration due to long-term exposure to external light. Examples of the UV absorber include 2-(2H-benzotriazole-2-yl)-phenol. The content of the UV absorber is preferably 0.01 to 2.0 parts by weight per 100 parts by weight of the polymer resin. Using too little UV absorber will result in ineffectiveness, while using too much will reduce heat resistance.

[0039] The present invention provides a method for manufacturing an insulating film formed from a positive-tone photosensitive resin composition. The insulating film can be used in display devices such as OLEDs, and has excellent high-sensitivity pattern developability, suppresses the generation of scum and cracks during pattern formation, and improves chemical resistance and adhesive strength.

[0040] The method for manufacturing the insulating film includes the steps of applying the positive photosensitive resin composition to a substrate, followed by drying, and exposing and developing the substrate coated with the photosensitive resin composition, followed by curing to form a polyimide film. The method for applying the photosensitive resin composition may be any conventionally known method, including, but not limited to, spin coating, dip coating, roll coating, screen coating, spray coating, and screen printing. The developer may be any conventionally known developer, including, but not limited to, an alkaline aqueous solution. The thickness of the insulating film of the present invention varies depending on the purpose, but is preferably, but not limited to, 1.0 to 15 μm.

[0041] The present invention also provides a display device comprising a driving circuit, a planarization layer, a first electrode, an insulating layer, a light-emitting layer, and a second electrode on a substrate, wherein at least one of the planarization layer and the insulating layer is formed from the positive photosensitive resin composition. The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0042] [Synthesis Example 1] Synthesis of polyimide precursor (chemical formula 1) A 1000 mL flask was charged with gamma-butyrolactone (GBL, 313 g), 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (bis-APAF, 71.8 g, 0.196 mol), and 1,3-bis(3-aminopropyl)tetramethyldisiloxane (SiDA, 0.99 g, 0.04 mol) dissolved at 50 °C. 3,3',4,4'-diphenylethertetracarboxylic acid dianhydride (ODPA, 46.5 g, 0.15 mol) was added and stirred at 70 °C for 25 hours. Then, phthalic anhydride (14.8 g, 0.1 mol) was added and reacted for 2 hours. Dimethylformamide dimethyl acetal (DFA, 17.8 g, 0.15 mol) was then added and stirred at 70 °C for 4 hours, after which the reaction was terminated to synthesize a polyimide precursor.

[0043] [Synthesis Example 2] Synthesis of polyimide precursor (chemical formula 1) A 1000 mL flask was charged with gamma-butyrolactone (GBL, 309 g), 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (bis-APAF, 68.1 g, 0.1860 mol), 4,4'-oxydianiline (2.0 g, 0.01 mol), and 1,3-bis(3-aminopropyl)tetramethyldisiloxane (SiDA, 0.99 g, 0.04 mol) dissolved at 50 °C. 3,3',4,4'-diphenylethertetracarboxylic acid dianhydride (ODPA, 47.8 g, 0.154 mol) was added and stirred at 70 °C for 25 hours. Then, phthalic anhydride (13.63 g, 0.092 mol) was added and reacted for 2 hours. Thereafter, dimethylformamide dimethyl acetal (DFA, 18.3 g, 0.154 mol) was added, and the mixture was stirred at 70° C. for 4 hours, after which the reaction was terminated to synthesize a polyimide precursor.

[0044] [Synthesis Example 3] Synthesis of polyimide precursor (chemical formula 1) A 1000 mL flask was charged with gamma-butyrolactone (GBL, 329 g), 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (bis-APAF, 71.8 g, 0.196 mol), and 1,3-bis(3-aminopropyl)tetramethyldisiloxane (SiDA, 0.99 g, 0.04 mol) dissolved at 50 °C. 3,3',4,4'-diphenylethertetracarboxylic dianhydride (ODPA, 32.3 g, 0.104 mol) and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA, 22.2 g, 0.05 mol) were added and stirred at 70 °C for 25 hours. Then, phthalic anhydride (13.6 g, 0.092 mol) was added and reacted for 2 hours. Thereafter, dimethylformamide dimethyl acetal (DFA, 18.3 g, 0.154 mol) was added, and the mixture was stirred at 70° C. for 4 hours, after which the reaction was terminated to synthesize a polyimide precursor.

[0045] [Synthesis Example 4] Synthesis of polyimide precursor (chemical formula 1) A polyimide precursor was synthesized in the same manner as in Synthesis Example 1, except that 1,2-epoxy-4-vinylcyclohexane (37.25 g, 0.3 mol) and triethylamine (0.81 g, 0.008 mol) were used instead of dimethylformamide dimethyl acetal. The reaction was terminated after stirring for 48 hours, thereby synthesizing a polyimide precursor.

[0046] [Synthesis Example 5] Synthesis of polyimide precursor (chemical formula 1) A polyimide polymer was synthesized in the same manner as in Synthesis Example 2, except that 1,2-epoxy-4-vinylcyclohexane (38.25 g, 0.308 mol) and triethylamine (0.81 g, 0.008 mol) were used instead of dimethylformamide dimethyl acetal. After stirring for 48 hours, the reaction was terminated, thereby synthesizing a polyimide precursor.

[0047] [Synthesis Example 6] Synthesis of polyimide precursor (chemical formula 1) A polyimide precursor was synthesized in the same manner as in Synthesis Example 3, except that 1,2-epoxy-4-vinylcyclohexane (38.25 g, 0.308 mol) and triethylamine (0.81 g, 0.008 mol) were used instead of dimethylformamide dimethyl acetal. The reaction was terminated after stirring for 48 hours, thereby synthesizing a polyimide precursor.

[0048] [Synthesis Example 7] Polyimide synthesis (chemical formula 2) A 1000 mL flask was charged with gamma-butyrolactone (GBL, 294 g), 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (bis-APAF, 49.81 g, 0.136 mol), and 1,3-bis(3-aminopropyl)tetramethyldisiloxane (SiDA, 0.99 g, 0.04 mol) dissolved at 50 °C. 3,3',4,4'-diphenylethertetracarboxylic acid dianhydride (ODPA, 62.0 g, 0.20 mol) was added and stirred at 50 °C for 4 hours. 3-aminophenol (13.1 g, 0.12 mol) was then added and reacted for 2 hours. 60 mL of toluene was then added, and the reaction was terminated by stirring at 150 °C for 2 hours and then at 180 °C for 2 hours, thereby synthesizing polyimide.

[0049] [Synthesis Example 8] Polyimide synthesis (chemical formula 2) A 1000 mL flask was charged with gamma-butyrolactone (GBL, 313 g), 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (bis-APAF, 71.79 g, 0.196 mol), and 1,3-bis(3-aminopropyl)tetramethyldisiloxane (SiDA, 0.99 g, 0.04 mol) dissolved at 50 °C. 3,3',4,4'-diphenylethertetracarboxylic acid dianhydride (ODPA, 46.5 g, 0.15 mol) was added and stirred at 50 °C for 4 hours. Then, phthalic anhydride (14.8 g, 0.10 mol) was added and reacted for 2 hours. 60 mL of toluene was then added, and the reaction was terminated by stirring at 150 °C for 2 hours and then at 180 °C for 2 hours to synthesize polyimide.

[0050] [Synthesis Example 9] Synthesis of polyimide precursor (chemical formula 1) Gamma-butyrolactone (GBL, 316 g) was placed in a 1000 mL flask, and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (bis-APAF, 71.8 g, 0.196 mol) and 1,3-bis(3-aminopropyl)tetramethyldisiloxane (SiDA, 0.99 g, 0.04 mol) were dissolved at 50 °C. 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA, 17.77 g, 0.04 mol), 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride (18.5 g, 0.07 mol), and 2,3,3',4'-biphenyltetracarboxylic dianhydride (17.7 g, 0.06 mol) were added to the reactor and stirred at 70°C for 25 hours. After stirring, phthalic anhydride (8.89 g, 0.06 mol) was added and the reaction continued for another 2 hours. The reactor temperature was then raised to 130°C and the reaction continued for 30 hours, after which the temperature was lowered to 70°C. 1,2-epoxy-4-vinylcyclohexane (29.8 g, 0.24 mol) and triethylamine (0.81 g, 0.008 mol) were added to the mixture, and the mixture was stirred at 70° C. for 48 hours, after which the reaction was terminated to synthesize a polyimide precursor.

[0051] [Synthesis Example 10] Synthesis of polyimide precursor (chemical formula 1) Gamma-butyrolactone (GBL, 321 g) was placed in a 1000 mL flask, and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (bis-APAF, 71.8 g, 0.196 mol) and 1,3-bis(3-aminopropyl)tetramethyldisiloxane (SiDA, 0.99 g, 0.04 mol) were dissolved at 50 °C. 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA, 22.21 g, 0.05 mol), 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride (13.21 g, 0.05 mol), and 2,3,3',4'-biphenyltetracarboxylic dianhydride (20.6 g, 0.07 mol) were added to the reactor and stirred at 70°C for 25 hours. After stirring, phthalic anhydride (8.89 g, 0.06 mol) was added and the reaction continued for another 2 hours. The reactor temperature was then raised to 130°C and the reaction continued for 30 hours, after which the temperature was lowered to 70°C. 1,2-epoxy-4-vinylcyclohexane (19.9 g, 0.16 mol) and triethylamine (0.81 g, 0.008 mol) were added to the mixture, and the mixture was stirred at 70° C. for 48 hours, after which the reaction was terminated to synthesize a polyimide precursor.

[0052] [Synthesis Example 11] Synthesis of polyimide precursor (chemical formula 1) Gamma-butyrolactone (GBL, 327 g) was placed in a 1000 mL flask, and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (bis-APAF, 71.79 g, 0.196 mol) and 1,3-bis(3-aminopropyl)tetramethyldisiloxane (SiDA, 0.99 g, 0.04 mol) were dissolved therein at 50°C. 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA, 22.21 g, 0.05 mol), 2,3,3',4'-biphenyltetracarboxylic dianhydride (14.7 g, 0.05 mol), and 3,3',4,4'-diphenylethertetracarboxylic dianhydride (ODPA, 21.7 g, 0.07 mol) were added to the reactor and stirred at 70°C for 25 hours. After stirring, phthalic anhydride (8.89 g, 0.06 mol) was added and the reaction continued for another 2 hours. The reactor temperature was then raised to 130°C and the reaction continued for 30 hours, after which the temperature was lowered to 70°C. 1,2-epoxy-4-vinylcyclohexane (19.9 g, 0.16 mol) and triethylamine (0.81 g, 0.008 mol) were added to the reactor and stirred at 70°C for 48 hours. The reaction was then terminated to synthesize a polyimide precursor.

[0053] [Synthesis Example 12] Synthesis of polyimide precursor (chemical formula 3) Gamma-butyrolactone (GBL, 327 g) was placed in a 1000 mL flask, and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (bis-APAF, 71.79 g, 0.196 mol) and 1,3-bis(3-aminopropyl)tetramethyldisiloxane (SiDA, 0.99 g, 0.04 mol) were dissolved at 50 °C. 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA, 22.21 g, 0.05 mol), 2,3,3',4'-biphenyltetracarboxylic dianhydride (14.7 g, 0.05 mol), and 3,3',4,4'-diphenylethertetracarboxylic dianhydride (ODPA, 21.7 g, 0.07 mol) were added to the mixture and stirred at 70°C for 25 hours. After that, phthalic anhydride (8.89 g, 0.06 mol) was added and the mixture was further reacted for 2 hours to synthesize polyamic acid.

[0054] [Examples 1 to 26 and Comparative Examples 1 to 11] Production of photosensitive resin composition Photosensitive resin compositions were prepared by mixing the polyimides and polyimide precursors synthesized in Synthesis Examples 1 to 12 in the ratios shown in Table 1 below. Specifically, the solid contents of the polyimides and polyimide precursors synthesized in Synthesis Examples 1 to 12 were confirmed, and then quinone diazide and thermal crosslinker were mixed with 100 parts by weight of the polymer resin in the ratios shown in Table 1 below. Then, a photosensitive resin composition was prepared using a solvent mixed in a molar ratio of GBL:MMP:PGME = 24:20:56 so that the total solid content was 13%.

[0055] In Table 1 below, the compound represented by the following formula 4-1-1 was used as Tris-TPPA used as the quinone diazide compound, and the compound represented by the following formula 4-2-1 was used as Tris-THAP. When using a thermal crosslinker having a structure of chemical formula 5-2 or 5-3, A was used as a thermal crosslinker in which n in the chemical formula a is 1 and Ra is a methyl group. [Chemical formula 4-1-1] TIFF0007801224000034.tif80170 [Chemical formula 4-2-1] TIFF0007801224000035.tif73170

[0056] [Table 1] TIFF0007801224000037.tif251170 TIFF0007801224000038.tif64170

[0057] [Experimental Example] Physical property evaluation The photosensitive resin compositions of Comparative Examples 1 to 10 and Examples 1 to 26 synthesized in the ratios listed in Table 1 were coated onto a substrate. Then, a thin film was coated onto a glass substrate using a spin coater and dried on a hot plate at 120°C for 2 minutes to form a film with a thickness of 2.0 μm. The physical properties of the photoresist, such as sensitivity, scum, cracks, chemical resistance, adhesion, and OLED reliability, were measured using the prepared substrate, and the results are listed in Table 2 below.

[0058] 1. Sensitivity Measurement A broadband intensity of 20 mW / cm was applied to the fabricated substrate using a predetermined pattern mask. 2 After investigating the standard dose of ultraviolet light for forming a 5 μm contact hole CD, the film was developed in an aqueous solution of 2.38 parts by weight of tetramethylammonium hydroxide at 23°C for 1 minute and washed with ultrapure water for 1 minute. It was then cured in an oven at 250°C for 60 minutes to obtain a patterned film with a contact hole CD of 5 μm. The sensitivity was 40-150 mJ / cm. 2 is the correct result value.

[0059] 2. Scum measurement The inside of the pattern formed during the sensitivity measurement was observed by SEM to check whether there was any residue in the line & space and contact hole. If there was any development residue, it was marked with X, if there was any development residue only at the pattern boundary, it was marked with △, and if there was no development residue, it was marked with O.

[0060] 3. Crack measurement The prepared substrate was visually inspected and observed under a microscope at 100x magnification. If cracks were observed, they were marked with an X; if cracks were observed only at the edge of the coating, they were marked with a △; and if no cracks were observed, they were marked with an O.

[0061] 4. Chemical resistance measurement The prepared substrate was immersed in methylpyrrolidone (NMP) at 60°C for 120 seconds, and the change in thickness of the cured film before and after immersion was measured. The change was marked as follows: less than 150 Å, 150 Å to less than 300 Å, 300 Å to less than 600 Å, and 600 Å or more.

[0062] 5. Adhesion Strength Measurement A pattern film was formed in the same manner as in the sensitivity measurement, but the adhesive strength was compared depending on the bake temperature, based on a 10 μm line width and slit width ratio of 1:1. In this case, adhesive strength maintained at a pre-bake temperature of 90°C to 100°C was marked as O, adhesive strength maintained at a pre-bake temperature of 105°C to 115°C was marked as △, and adhesive strength maintained or not maintained at a pre-bake temperature of 120°C or higher was marked as X.

[0063] 6. OLED Reliability Measurement A pattern film can be formed in the same manner as in the sensitivity measurement. Figure 1 shows how a pattern film is formed on an ITO substrate on which a pattern is formed, and then EL is deposited. As shown in Figure 1, Al is deposited on the top as a cathode electrode, and an encapsulation process is performed. The time (T) until the luminance decreases by 3% in the device on state is measured at 85°C and 85% RH. 97 If 1000 hours or more was secured, it was marked as O, and if less than 1000 hours, it was marked as X.

[0064] [Table 2]

[0065] As shown in Table 2, Comparative Examples 1 to 3 are polyimide precursors prepared using Synthesis Examples 1 to 3, each containing a structure in which R3 is alkyl in the structural unit represented by Chemical Formula 1. In contrast, Examples 1 to 3 are polyimide precursors prepared using Synthesis Examples 4 to 6, each containing a structure in which R3 is derived from an epoxy compound in the structural unit represented by Chemical Formula 1. Comparing these, it can be seen that Examples 1 to 3 showed an improvement in sensitivity of about 10%, as well as improvements in physical properties such as scum, cracking, chemical resistance, adhesion, and OLED reliability. In Comparative Examples 4 to 7, when a polymer resin was synthesized using only a polyimide precursor having a structural unit represented by Chemical Formula 1 or a polyimide having a structural unit represented by Chemical Formula 2, or a polymer resin synthesized using less than 5 wt% of a polyimide precursor having a structural unit represented by Chemical Formula 1 or a polyimide having a structural unit represented by Chemical Formula 2, the physical properties of scum, cracking, chemical resistance, adhesion, and OLED reliability were poor compared to Examples 1 to 3.

[0066] It can be seen that when the photosensitive material quinone diazide is contained in an amount of less than 5 parts by weight relative to the polymer resin as in Comparative Examples 8 to 11, the sensitivity is very high (Comparative Examples 8 and 9). On the other hand, when the quinone diazide is contained in an amount of more than 50 parts by weight relative to the polymer resin, the sensitivity is low, and compared to Examples 1 to 3, the physical properties of scum, cracks, chemical resistance, adhesion, and OLED reliability are poor.

[0067] Examples 1 to 21 are relatively excellent in sensitivity, scum, crack resistance, chemical resistance, adhesive strength, and OLED reliability applicable to OLED substrates. In particular, Examples 22 to 26, which use a thermal crosslinker, are extremely excellent in chemical resistance. [Explanation of symbols]

[0068] 1. ITO (Indium Tin Oxide) 2. Insulator 3 EL&Al(Electrolyminescent Lighting & Aluminum)

Claims

1. i) 5 to 95 wt % of a polyimide precursor having a structural unit represented by the following Chemical Formula 1, ii) 5 to 95 wt % of a polyimide precursor having a structural unit represented by the following Chemical Formula 2, and iii) 0 to 20 wt % of a polyimide precursor having a structural unit represented by the following Chemical Formula 3: 5 to 50 parts by weight of a quinone diazide compound relative to 100 parts by weight of the polymer resin; and 100 to 2,000 parts by weight of a solvent per 100 parts by weight of the polymer resin. [Chemical formula 1] [Chemical formula 2] [Chemical formula 3] [Chemical formula R] １ -1] [Chemical formula R] １ -2] [Chemical formula R] １ -3] [Chemical formula R] １ -4] [Chemical formula R] １ -5] [Chemical formula R] １ -6] [Chemical formula R] １ -7] [Chemical formula R] ２ -1] [Chemical formula R] ２ -2] [Chemical formula R] ２ -3] [Chemical formula R] ２ -4] [Chemical formula R] ２ -5] [Chemical formula R] ２ -6] [Chemical formula R] ２ -7] [Chemical formula R] ２ -8] [Chemical formula R] ２ -9] [Chemical formula R] ２ -10] [Chemical formula 4] (In the above chemical formulas 1 to 3, R １ is the chemical formula R １ -1 to R １ a structure derived from an aromatic dianhydride containing at least one compound represented by R ２ is the chemical formula R ２ -1 to R ２ -10, and R ３ is a substituent represented by the chemical formula 4, R 4 is a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms, hydrogen of the alkyl group can be substituted with 1 to 3 fluorine atoms or hydroxyl groups, and a methylene group of the alkyl group can be substituted with an alkenyl group, oxygen, nitrogen, ester (COO) or carbonyl (C═O).

2. The R ３ is derived from a compound selected from the group consisting of epoxycyclohexylmethyl methacrylate, 1,2-epoxy-4-vinylcyclohexene, 3,4-(epoxycyclohexene)methyl-3',4'-epoxycyclohexylcarboxylate, and 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexenecarboxylate-modified epsilon-caprolactone.

3. 2. The positive photosensitive resin composition according to claim 1, wherein the weight average molecular weight of the polyimide precursor having the structural unit represented by Chemical Formula 1, the polyimide precursor having the structural unit represented by Chemical Formula 2, and the polyimide precursor having the structural unit represented by Chemical Formula 3 is 3,500 to 20,000.

4. 2. The positive photosensitive resin composition according to claim 1, wherein the polymer resin contains 50 to 95 wt % of a polyimide having a structural unit represented by Chemical Formula 2.

5. 2. The positive photosensitive resin composition according to claim 1, wherein the quinone diazide compound is obtained by reacting a phenol compound selected from the group consisting of compounds represented by the following Chemical Formulas 4-1 to 4-3 with a naphthoquinone diazide sulfonic acid halide compound: [Chemical formula 4-1] [Chemical formula 4-2] [Chemical formula 4-3] (In the above chemical formulas 4-1 to 4-3, R ３１ ~R ３６ are each independently a hydrogen atom, a halogen atom, a hydroxy group, an alkyl group having 1 to 4 carbon atoms, or an alkenyl group having 2 to 4 carbon atoms; R ３７ and R ３８ are each independently hydrogen, halogen, or an alkyl group having 1 to 4 carbon atoms; R ３９ is hydrogen or an alkyl group having 1 to 4 carbon atoms.

6. 2. The positive photosensitive resin composition according to claim 1, wherein the solvent is selected from the group consisting of gamma butyrolactone (GBL), N-methylpyrrolidone (NMP), propylene glycol methyl ether acetate (PGMEA), ethyl lactate (EL), methyl-3-methoxypropionate (MMP), propylene glycol monomethyl ether (PGME), and mixtures thereof.

7. 2. The positive photosensitive resin composition according to claim 1, further comprising an additive selected from the group consisting of a thermal crosslinker, a thermal acid generator, a UV absorber, and a mixture thereof.

8. The positive photosensitive resin composition according to claim 7 , wherein the thermal crosslinking agent comprises a functional group represented by the following chemical formula 5: [Chemical formula 5] (In the above chemical formula 5, A is the following chemical formula a, and in the following chemical formula a, n is an integer of 1 to 6, and Ra is an alkyl having 1 to 3 carbon atoms.) [Chemical formula a]

9. 8. The positive photosensitive resin composition according to claim 7, wherein the thermal crosslinking agent is selected from the group consisting of compounds represented by the following chemical formulas 5-1 to 5-4: [Chemical formula 5-1] [Chemical formula 5-2] [Chemical formula 5-3] [Chemical formula 5-4] (In Chemical Formula 5-1 to Chemical Formula 5-4, A is the following Chemical Formula a, and in the following Chemical Formula a, n is an integer of 1 to 6, and Ra is alkyl having 1 to 3 carbon atoms.) [Chemical formula a]

10. 8. The positive photosensitive resin composition according to claim 7, wherein the thermal crosslinking agent is contained in an amount of 10 to 50 parts by weight based on 100 parts by weight of the polymer resin.

11. A display element comprising a substrate, a driving circuit, a planarization layer, a first electrode, an insulating layer, a light-emitting layer, and a second electrode, wherein at least one of the planarization layer and the insulating layer is formed from the positive photosensitive resin composition according to claim 1.

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