A negative photosensitive resin composition, a method for preparing the same, and an application thereof

Abstract

The application provides a negative photosensitive resin composition, and belongs to the technical field of photoresists, and comprises the following components by mass fraction: alkali-soluble resin 9-50%, sulfur-containing compound 6-30%, unsaturated bond-containing compound 3-30%, photoinitiator 1-5%, stabilizer 0.005-1%, curing agent 0.5-5%, and organic solvent 20-80%. Compared with the prior art of doping inorganic nanoparticles to improve the refractive index of a film layer, the negative resin composition of the application can achieve the performance of high refractive index without doping inorganic nanoparticles, does not need to solve the problems of dispersibility and stability of the resin composition, has excellent developing performance, can be cured at a low temperature lower than 120 DEG C, the hardened film after curing has high refractive index, and is suitable for a touch display panel of a higher refractive index film layer substrate.

Description

Technical Field

[0001] This invention relates to the field of photoresist technology, and more particularly to a negative photosensitive resin composition, its preparation method, and its application. Background Technology

[0002] Currently, display panels are developing towards higher pixel counts, higher contrast ratios, higher transmittance, and lower power consumption to achieve superior display effects. Touch panels (TPs), as the most widespread application in human-computer interaction, are typically combined with display panels to form touch display devices. The display effect of touch panels is updated in tandem with the development of display panels. Since light from the display panel needs to pass through the touch panel, the different effects of light transmission, refraction, and reflection on the touch panel directly affect the final display effect of the touch display device. To achieve better display effects, various processes or materials of the touch display panel can be optimized during the manufacturing process. The insulating and protective layers in the touch panel are important components of the entire device. By using different materials as insulating and protective layers, different properties can be given to the touch panel. A high refractive index design can improve the transmittance of the touch device and enhance the display effect. In applications such as Mini-LED, Micro-LED, and optical sensors, high refractive index negative photosensitive resins can be used to improve the optical matching of the device, increase the light extraction efficiency of the device, and reduce optical crosstalk.

[0003] The current mainstream high-refractive-index photoresist technology involves doping the resin system with inorganic nanofillers such as TiO2, ZrO2, and Ta2O5, relying on the high refractive index characteristics of inorganic particles to improve the overall film refractive index. However, this technology has significant drawbacks: 1. Inorganic nanoparticles are prone to aggregation and have poor dispersibility in organic resins, leading to increased film haze and decreased optical uniformity, affecting the optical performance of devices; 2. Nanoparticles are prone to sedimentation, resulting in insufficient storage stability of the photosensitive resin composition and shortening the product's shelf life; 3. The addition of fillers reduces the system's photosensitivity, easily generating residues during photolithography and development, reducing pattern imaging accuracy and development process width; 4. Inorganic fillers have poor interfacial compatibility with organic resins, leading to defects and insufficient adhesion in the cured film, failing to meet the stringent requirements of high-end touch display panel substrates; 5. Most of this type of material requires high-temperature curing processes, making it unsuitable for some low-temperature processes.

[0004] Therefore, the industry urgently needs to develop a negative photosensitive resin composition that can be cured at low temperatures, without the need for doping with inorganic nanoparticles, has an intrinsically high refractive index, excellent development performance, and good storage stability. Summary of the Invention

[0005] The purpose of this invention is to provide a negative photosensitive resin composition, its preparation method, and its application, so as to solve the above-mentioned problems existing in the prior art.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: The present invention provides a negative photosensitive resin composition comprising the following components in the indicated mass fractions: 9-50% alkali-soluble resin, 6-30% sulfur-containing compound, 3-30% unsaturated bond-containing compound, 1-5% photoinitiator, 0.005-1% stabilizer, 0.5-5% curing agent, and 20-80% organic solvent.

[0007] Preferably, the method for preparing the alkali-soluble resin includes the following steps: Methacrylic acid, hydroxyethyl methacrylate, and a naphthyl compound are mixed and subjected to free radical polymerization. Then, a fluorenyl compound is added and subjected to ring-opening polymerization to obtain an alkali-soluble resin. The naphthyl compound is shown in Formula I: Formula I, where R1 is a group in a compound having a carbon-carbon double bond; the fluorene compound is shown in Formula II: Formula II, in which R2 is a methyl or hydrogen atom, R3 is a methyl or hydrogen atom, R4 is an alkane with an epoxy group, and R5 is an alkane with an epoxy group.

[0008] Preferably, the alkali-soluble resin has an acid value of 80-160 mgKOH / g and a weight-average molecular weight of 3000-5000.

[0009] Preferably, the general structural formula of the sulfur-containing compound includes Formula IV Formula V Formula VI Formula VII or Equation VIII, where R6~R 25 It consists of hydrogen atoms or hydrocarbon groups; The sulfur-containing compound has a sulfur content of 3-40% by mass.

[0010] Preferably, the compound containing unsaturated bonds is one or more of pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate.

[0011] Preferably, the photoinitiator includes benzophenone, isopropylthioxanthone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 1-[4-(phenylthio)phenyl]-1,2-octanedione-2-(O-benzoyl oxime) or 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl] acetophenone-1-(O-acetyl oxime).

[0012] Preferably, the stabilizer comprises one or more of p-hydroxyanisole, hydroquinone, and 2,2,6,6-tetramethylpiperidine-1-oxo radical.

[0013] Preferably, the curing agent comprises one or more of 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, and 2-phenylimidazole; The organic solvent includes one or more of diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, propylene glycol methyl ether, propylene glycol methyl ether acetate, and diacetone alcohol.

[0014] This invention provides a method for preparing the above-mentioned negative photosensitive resin composition, comprising the following steps: The components of the above negative photosensitive resin composition are thoroughly mixed and stirred at room temperature, and then filtered using a filter membrane in a two-stage pressure filtration method to obtain the negative photosensitive resin composition.

[0015] This invention provides the application of the above-described negative photosensitive resin composition in the field of electronic display devices.

[0016] The beneficial effects of this invention are: This invention comprises a negative photosensitive resin composition consisting of an alkali-soluble resin, a sulfur-containing compound, a compound containing unsaturated bonds, a photoinitiator, a stabilizer, a curing agent, and an organic solvent. Compared with existing technologies that dope inorganic nanoparticles to increase the refractive index of the film, the negative resin composition of this invention achieves high refractive index performance without doping inorganic nanoparticles, eliminates the need to solve the problems of resin composition dispersion and stability, and has excellent development performance. It can be cured at low temperatures below 120°C, and the cured hardened film has a high refractive index, making it suitable for touch display panels with high refractive index film layers. Detailed Implementation

[0017] The present invention provides a negative photosensitive resin composition comprising the following components in the indicated mass fractions: 9-50% alkali-soluble resin, 6-30% sulfur-containing compound, 3-30% unsaturated bond-containing compound, 1-5% photoinitiator, 0.005-1% stabilizer, 0.5-5% curing agent, and 20-80% organic solvent.

[0018] In this invention, unless otherwise specified, all raw materials required for preparation are commercially available products well known to those skilled in the art.

[0019] In the negative photosensitive resin composition provided by the present invention, the mass fraction of the alkali-soluble resin is preferably 9-50%, more preferably 30%.

[0020] In this invention, the acid value of the alkali-soluble resin is preferably 80-160 mgKOH / g, more preferably 100-150 mgKOH / g, and the weight-average molecular weight is preferably 3000-15000, more preferably 9000-12000.

[0021] In this invention, the method for preparing the alkali-soluble resin preferably includes the following steps: Under a nitrogen atmosphere, methacrylic acid, hydroxyethyl methacrylate, naphthyl compound, thermal initiator and solvent were added to a four-necked flask and reacted at 80°C for 2 hours, then the temperature was raised to 130°C and reacted for 1 hour; this step was to achieve free radical polymerization of carbon-carbon double bonds. Under a nitrogen atmosphere, the catalyst and fluorene compound were added to a four-necked flask and reacted at 90°C for 3 hours to obtain an alkali-soluble resin; this step was to catalyze the ring-opening polymerization of epoxy groups under the action of the catalyst.

[0022] In this invention, the naphthyl compound is preferably as shown in Formula I: Formula I, where R1 is a group of a compound having a carbon-carbon double bond; the naphthyl compound further preferably includes one or more of 2-naphthyl acrylate, 3-(2-naphthyl)acrylic acid and 2-naphthioethyl acrylate, more preferably 2-naphthyl acrylate.

[0023] In this invention, the thermal initiator is preferably azobisisobutyronitrile; the solvent is preferably propylene glycol methyl ether acetate.

[0024] In this invention, the mass ratio of methacrylic acid, hydroxyethyl methacrylate, naphthyl compound, thermal initiator and solvent is preferably 5~15:16~30:8~20:2~4:35~60, and more preferably 10:16:10:2:35.

[0025] In this invention, the catalyst is preferably 2-methylimidazole.

[0026] In this invention, the fluorene compound is preferably as shown in Formula II: Formula II, wherein R2 is a methyl or hydrogen atom, R3 is a methyl or hydrogen atom, R4 is an alkane with an epoxy group, and R5 is an alkane with an epoxy group; the fluorene compound further preferably includes one or more of 9,9-bis(4-epoxypropyloxophenyl)fluorene and 9,9-bis(4-epoxypropyloxo-3-tolyl)fluorene, more preferably 9,9-bis(4-epoxypropyloxophenyl)fluorene.

[0027] In this invention, the mass ratio of the catalyst to the fluorene compound is preferably 1~3:6~10, and more preferably 1:7.

[0028] In the negative photosensitive resin composition provided by the present invention, the mass fraction of the sulfur-containing compound is preferably 6-30%, and more preferably 10%.

[0029] In this invention, the sulfur-containing compound is preferably a polycyclic aromatic hydrocarbon compound containing sulfur atoms, and the mass content of sulfur element is preferably 3-40%.

[0030] In this invention, the general structural formula of the sulfur-containing compound preferably includes: Formula IV Formula V Formula VI Formula VII or Equation VIII, where R6~R 25 It is a hydrogen atom or a hydrocarbon group; the sulfur-containing compound is further preferably benzodithiophene.

[0031] In the negative photosensitive resin composition provided by the present invention, the mass fraction of the compound containing unsaturated bonds is preferably 3-30%, more preferably 20%.

[0032] In this invention, the unsaturated compound preferably includes one or more of pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate, and more preferably pentaerythritol triacrylate.

[0033] In the negative photosensitive resin composition provided by the present invention, the mass fraction of the photoinitiator is preferably 1-5%, more preferably 3%.

[0034] In this invention, the photoinitiator preferably includes benzophenone, isopropylthioxanthone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 1-[4-(phenylthio)phenyl]-1,2-octanedione-2-(O-benzoyl oxime), or 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl] ethyl ketone-1-(O-acetyl oxime), more preferably 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl] ethyl ketone-1-(O-acetyl oxime).

[0035] In the negative photosensitive resin composition provided by the present invention, the mass fraction of the stabilizer is preferably 0.005~1%, more preferably 0.01%.

[0036] In this invention, the stabilizer preferably includes one or more of p-hydroxyanisole, hydroquinone, and 2,2,6,6-tetramethylpiperidine-1-oxygen radical, and more preferably p-hydroxyanisole.

[0037] In the negative photosensitive resin composition provided by the present invention, the mass fraction of the curing agent is preferably 0.5-5%, and more preferably 3%.

[0038] In this invention, the curing agent preferably includes one or more of 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole and 2-phenylimidazole, and more preferably 2-methylimidazole.

[0039] In the negative photosensitive resin composition provided by the present invention, the mass fraction of the organic solvent is preferably 20-80%, and more preferably 70%.

[0040] In this invention, the organic solvent preferably includes one or more of diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, propylene glycol methyl ether, propylene glycol methyl ether acetate, and diacetone alcohol, and more preferably propylene glycol methyl ether acetate.

[0041] The present invention provides a method for preparing the above-mentioned negative photosensitive resin composition, comprising the following steps: thoroughly mixing and stirring the components of the above-mentioned negative photosensitive resin composition at room temperature, and filtering by a filter membrane using a two-stage pressure filtration method to obtain the negative photosensitive resin composition.

[0042] In this invention, the pore size of the filter membrane is preferably 0.1~1μm, and more preferably 0.1 μm.

[0043] In this invention, the pressure of the secondary booster filter is preferably 0.1~0.5 MPa, and more preferably 0.2 MPa.

[0044] This invention provides the application of the above-mentioned negative photosensitive resin composition in the field of electronic display devices. The preferred method of application includes the following steps: spin-coating the negative photosensitive resin composition onto a glass substrate, vacuum drying, and then baking at 70-100°C for 2-4 minutes to obtain the treated glass substrate; using an i-line exposure machine at 50-300 mJ / cm². 2 The treated glass substrate was exposed to the above exposure amount to obtain an exposed glass substrate; the exposed glass substrate was developed at 25°C for 60 s using a TMAH developer solution with a concentration of 0.5~2.38%, then rinsed with pure water for 30~60 s, and air-dried to obtain a developed glass substrate; the developed glass substrate was cured at 80~100°C for 30~60 min to obtain a negative photosensitive resin composition hardened film.

[0045] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0046] Example 1

[0047] In this embodiment, the negative photosensitive resin composition comprises the following components by mass fraction: 20% alkali-soluble resin, 10% benzodithiophene, 5% pentaerythritol triacrylate, 2% 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]acetophenone-1-(O-acetyloxime), 0.01% p-hydroxyanisole, 0.5% 2-methylimidazole, and 62.49% propylene glycol methyl ether acetate; The preparation method of the alkali-soluble resin includes the following steps: methacrylic acid, hydroxyethyl methacrylate, naphthalene 2-acrylate, azobisisobutyronitrile, and propylene glycol methyl ether acetate are added to a four-necked flask in a mass ratio of 10:16:10:2:35. Under a nitrogen atmosphere, the mixture is first reacted at 80°C for 2 hours, and then the temperature is raised to 130°C for 1 hour. 2-methylimidazole and 9,9-bis(4-epoxypropyloxyphenyl)fluorene are added to the four-necked flask in a mass ratio of 1:7. Under a nitrogen atmosphere, the mixture is reacted at 90°C for 3 hours to obtain an alkali-soluble resin with an acid value of 90 mgKOH / g and a weight-average molecular weight of 9000.

[0048] The preparation method of the negative photosensitive resin composition is as follows: the above components are thoroughly mixed in a three-necked flask, stirred evenly at room temperature, filtered using a filter membrane with a pore size of 0.1 μm and a two-stage pressure filtration method with a filtration pressure of 0.2 MPa to obtain the negative photosensitive resin composition.

[0049] Example 2

[0050] The only difference from Example 1 is: In this embodiment, the negative photosensitive resin composition comprises the following components by mass fraction: 30% alkali-soluble resin, 20% benzodithiophene, 20% pentaerythritol triacrylate, 3% 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]acetophenone-1-(O-acetyloxime), 0.02% p-hydroxyanisole, 1% 2-methylimidazolium, and 25.98% propylene glycol methyl ether acetate; The preparation method of the alkali-soluble resin includes the following steps: methacrylic acid, hydroxyethyl methacrylate, naphthalene 2-acrylate, azobisisobutyronitrile, and propylene glycol methyl ether acetate are added to a four-necked flask in a mass ratio of 5:20:8:3:40. Under a nitrogen atmosphere, the mixture is first reacted at 80°C for 2 h, and then the temperature is increased to 130°C for 1 h. 2-Methylimidazole and 9,9-bis(4-epoxypropyloxyphenyl)fluorene are added to the four-necked flask in a mass ratio of 2:6. Under a nitrogen atmosphere, the mixture is reacted at 90°C for 3 h to obtain an alkali-soluble resin with an acid value of 80 mgKOH / g and a weight-average molecular weight of 12000. With all other parameters unchanged, a negative photosensitive resin composition was obtained.

[0051] Example 3

[0052] The only difference from Example 1 is: In this embodiment, the negative photosensitive resin composition comprises the following components by mass fraction: 50% alkali-soluble resin, 10% benzodithiophene, 10% pentaerythritol triacrylate, 5% 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]acetophenone-1-(O-acetyloxime), 1% p-hydroxyanisole, 2% 2-methylimidazolium, and 22% propylene glycol methyl ether acetate; The preparation method of the alkali-soluble resin includes the following steps: methacrylic acid, hydroxyethyl methacrylate, naphthalene 2-acrylate, azobisisobutyronitrile, and propylene glycol methyl ether acetate are added to a four-necked flask in a mass ratio of 15:30:20:4:50. Under a nitrogen atmosphere, the mixture is first reacted at 80°C for 2 hours, and then the temperature is increased to 130°C for 1 hour. 2-methylimidazole and 9,9-bis(4-epoxypropyloxyphenyl)fluorene are added to the four-necked flask in a mass ratio of 3:10. Under a nitrogen atmosphere, the mixture is reacted at 90°C for 3 hours to obtain an alkali-soluble resin with an acid value of 150 mgKOH / g and a weight-average molecular weight of 12000. With all other parameters unchanged, a negative photosensitive resin composition was obtained.

[0053] Example 4

[0054] The only difference from Example 1 is: In this embodiment, the negative photosensitive resin composition comprises the following components by mass fraction: 9% alkali-soluble resin, 6% benzodithiophene, 30% pentaerythritol triacrylate, 4% 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]acetophenone-1-(O-acetyloxime), 0.005% p-hydroxyanisole, 5% 2-methylimidazole, and 45.995% propylene glycol methyl ether acetate; The preparation method of the alkali-soluble resin includes the following steps: methacrylic acid, hydroxyethyl methacrylate, naphthalene 2-acrylate, azobisisobutyronitrile, and propylene glycol methyl ether acetate are added to a four-necked flask in a mass ratio of 8:25:15:2:55. Under a nitrogen atmosphere, the mixture is first reacted at 80°C for 2 hours, and then the temperature is raised to 130°C for 1 hour. 2-methylimidazole and 9,9-bis(4-epoxypropyloxyphenyl)fluorene are added to the four-necked flask in a mass ratio of 1:10. Under a nitrogen atmosphere, the mixture is reacted at 90°C for 3 hours to obtain an alkali-soluble resin with an acid value of 110 mgKOH / g and a weight-average molecular weight of 10000. With all other parameters unchanged, a negative photosensitive resin composition was obtained.

[0055] Example 5

[0056] The only difference from Example 1 is: In this embodiment, the negative photosensitive resin composition comprises the following components by mass fraction: 40% alkali-soluble resin, 15% benzodithiophene, 5% pentaerythritol triacrylate, 2% 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]acetophenone-1-(O-acetyloxime), 0.02% p-hydroxyanisole, 0.8% 2-methylimidazole, and 37.18% propylene glycol methyl ether acetate; The preparation method of the alkali-soluble resin includes the following steps: methacrylic acid, hydroxyethyl methacrylate, naphthalene 2-acrylate, azobisisobutyronitrile, and propylene glycol methyl ether acetate are added to a four-necked flask in a mass ratio of 12:28:18:3:60. Under a nitrogen atmosphere, the mixture is first reacted at 80°C for 2 hours, and then the temperature is increased to 130°C for 1 hour. 2-methylimidazole and 9,9-bis(4-epoxypropyloxyphenyl)fluorene are added to the four-necked flask in a mass ratio of 3:6. Under a nitrogen atmosphere, the mixture is reacted at 90°C for 3 hours to obtain an alkali-soluble resin with an acid value of 100 mgKOH / g and a weight-average molecular weight of 9000. With all other parameters unchanged, a negative photosensitive resin composition was obtained.

[0057] Comparative Example 1

[0058] The only difference from Example 1 is: The negative photosensitive resin composition in this comparative example does not contain sulfur-containing compounds. The alkali-soluble resin is acrylic resin SR-3611, specifically containing the following components by mass fraction: SR-3611 resin 40%, pentaerythritol triacrylate 20%, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]acetophenone-1-(O-acetyloxime) 2%, p-hydroxyanisole 0.02%, 2-methylimidazole 0.8%, and propylene glycol methyl ether acetate 37.18%. With all other parameters unchanged, a negative photosensitive resin composition was obtained.

[0059] Comparative Example 2

[0060] The only difference from Example 1 is: The negative photosensitive resin composition in this comparative example does not contain sulfur-containing compounds. The alkali-soluble resin is acrylic resin SR-3611, and zirconium oxide nanoparticles are added. Specifically, it contains the following components by mass fraction: SR-3611 resin 35%, zirconium oxide nanoparticles 10%, pentaerythritol triacrylate 15%, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]acetophenone-1-(O-acetyloxime) 2%, p-hydroxyanisole 0.02%, 2-methylimidazole 0.8%, and propylene glycol methyl ether acetate 37.18%. With all other parameters unchanged, a negative photosensitive resin composition was obtained.

[0061] Comparative Example 3

[0062] The only difference from Example 1 is: In this comparative example, the alkali-soluble resin in the negative photosensitive resin composition is acrylic resin SR-3611, specifically comprising the following components by mass fraction: SR-3611 resin 40%, benzodithiophene 15%, pentaerythritol triacrylate 5%, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]acetophenone-1-(O-acetyloxime) 2%, p-hydroxyanisole 0.02%, 2-methylimidazole 0.8%, and propylene glycol methyl ether acetate 37.18%; With all other parameters unchanged, a negative photosensitive resin composition was obtained.

[0063] Comparative Example 4

[0064] The only difference from Example 1 is: The negative photosensitive resin composition in this comparative example does not contain sulfur-containing compounds and specifically includes the following components by mass fraction: alkali-soluble resin 40%, pentaerythritol triacrylate 5%, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]acetophenone-1-(O-acetyloxime) 2%, p-hydroxyanisole 0.02%, 2-methylimidazole 0.8%, and propylene glycol methyl ether acetate 52.18%; The preparation method of the alkali-soluble resin includes the following steps: methacrylic acid, hydroxyethyl methacrylate, naphthalene 2-acrylate, azobisisobutyronitrile, and propylene glycol methyl ether acetate are added to a four-necked flask in a mass ratio of 12:28:18:3:60. Under a nitrogen atmosphere, the mixture is first reacted at 80°C for 2 hours, and then the temperature is increased to 130°C for 1 hour. 2-methylimidazole and 9,9-bis(4-epoxypropyloxyphenyl)fluorene are added to the four-necked flask in a mass ratio of 3:6. Under a nitrogen atmosphere, the mixture is reacted at 90°C for 3 hours to obtain an alkali-soluble resin with an acid value of 100 mgKOH / g and a weight-average molecular weight of 9000. With all other parameters unchanged, a negative photosensitive resin composition was obtained.

[0065] Performance testing

[0066] 1. The negative photosensitive resin compositions of Examples 1-5 and Comparative Examples 1-4 were prepared into hardened films according to the following method, and the obtained hardened films were subjected to routine performance tests according to the following method. The results are shown in Table 1. 1) Preparation method of the hardened film: The negative photosensitive resin composition is spin-coated onto a glass substrate, pre-baked using vacuum drying and a baking process of 90℃×2 min, and then exposed to 150mJ / cm using an i-line exposure machine. 2 Then, the glass substrate coated with the negative photosensitive resin composition was developed at 25°C for 60 seconds using 2.38% TMAH developer, rinsed with pure water for 60 seconds, air-dried, and finally cured at 100°C for 50 minutes to obtain a hardened film of the negative photosensitive resin composition.

[0067] 2) Performance testing of the hardened film: ① Hardness: The pencil hardness test method was used. The test pencil was a Mitsubishi pencil. The hardness of the film was tested under a gravity of 500g. The test order was from soft to hard, that is, the pencil model was from 1H to 7H. The hardness test result was the pencil model before that which just scratched the hardened film. ② Adhesion: After the hardened film is coated onto the glass substrate and the main curing is completed, the adhesion is tested using the cross-cut adhesion test. The adhesion evaluation level from best to worst is: 5B, 4B, 3B, 2B, 1B, 0B. ③ Transmittance: Using Agilent Carry-3000 UV-vis, the full-band transmittance data of the film was tested, and the transmittance at a wavelength of 400nm was extracted; ④Refractive index: The film is coated on the silicon wafer and its refractive index is measured using an ellipsometer; ⑤ Development status: After development, compare whether there are flocculent substances or residues in the developing solution.

[0068] ⑥ Storage stability: Monitor whether there are aggregated particles in the coated film after the adhesive has been left at room temperature for 7 days.

[0069] Table 1. Test results of the hardened films of Examples 1-5 and Comparative Examples 1-4

[0070] As shown in Table 1, the negative photosensitive resin composition provided by this invention exhibits high hardness at 100°C and can be cured at temperatures below 120°C. Combined with Comparative Examples 1, 3, and 4, the refractive index of the hardened film prepared by the Comparative Example 4 system (containing only a specific alkali-soluble resin and no benzodithiophene) is 1.53; the refractive index of the hardened film prepared by the Comparative Example 3 system (containing only benzodithiophene and alkali-soluble acrylic resin SR-3611) is 1.55; and the refractive index of the hardened film prepared by the Comparative Example 1 system (not containing benzodithiophene and alkali-soluble acrylic resin SR-3611) is 1.44. All of these are lower than the refractive index (≥1.60) of the hardened film prepared by the negative photosensitive resin composition of this invention using a specific alkali-soluble resin and a sulfur-containing composition. This indicates that the synergistic effect of the two components can improve the refractive index of the system (since adding only the sulfur-containing compound cannot achieve a high refractive index effect, both components must be added together to achieve the desired effect; therefore, the effect of the sulfur-containing compound is not specifically explained). Compared with existing technologies that improve the refractive index of film by doping with inorganic nanoparticles, this invention can achieve high refractive index performance without doping with inorganic nanoparticles. The cured film has a refractive index ≥1.60, which is high and can be applied to touch display panels with high refractive index film substrates. It has excellent development performance, with no flocculent matter or residue after development, and better storage stability. It can be used as an insulating layer, protective layer, planarization layer and spacer layer in the preparation of electronic display devices, and is especially suitable for low-temperature process production.

[0071] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A negative photosensitive resin composition, characterized in that, It includes the following components by mass fraction: 9-50% alkali-soluble resin, 6-30% sulfur-containing compound, 3-30% unsaturated bond-containing compound, 1-5% photoinitiator, 0.005-1% stabilizer, 0.5-5% curing agent, and 20-80% organic solvent.

2. The negative photosensitive resin composition according to claim 1, characterized in that, The preparation method of the alkali-soluble resin includes the following steps: Under a nitrogen atmosphere, methacrylic acid, hydroxyethyl methacrylate, a naphthyl compound, a thermal initiator, and a solvent are mixed and subjected to a free radical polymerization reaction; then a catalyst and a fluorenyl compound are added to carry out a ring-opening polymerization reaction to obtain an alkali-soluble resin. The naphthyl compound is shown in Formula I: Formula I, where R1 is a group in a compound having a carbon-carbon double bond; the fluorene compound is shown in Formula II: Formula II, in which R2 is a methyl or hydrogen atom, R3 is a methyl or hydrogen atom, R4 is an alkane with an epoxy group, and R5 is an alkane with an epoxy group.

3. The negative photosensitive resin composition according to claim 1, characterized in that, The alkali-soluble resin has an acid value of 80~160 mgKOH / g and a weight-average molecular weight of 3000~15000.

4. The negative photosensitive resin composition according to claim 1, characterized in that, The general structural formula of the sulfur-containing compound includes Formula IV Formula V Formula VI Formula VII or Equation VIII, where R6~R 25 It consists of hydrogen atoms or hydrocarbon groups; The sulfur-containing compound has a sulfur content of 3-40% by mass.

5. The negative photosensitive resin composition according to claim 1, characterized in that, The unsaturated compound includes one or more of pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate.

6. The negative photosensitive resin composition according to claim 1, characterized in that, The photoinitiator includes benzophenone, isopropylthioxanthone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 1-[4-(phenylthio)phenyl]-1,2-octanedione-2-(O-benzoyl oxime) or 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]acetophenone-1-(O-acetyl oxime).

7. The negative photosensitive resin composition according to claim 1, characterized in that, The stabilizer includes one or more of p-hydroxyanisole, hydroquinone, and 2,2,6,6-tetramethylpiperidine-1-oxygen radical.

8. The negative photosensitive resin composition according to claim 1, characterized in that, The curing agent includes one or more of 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, and 2-phenylimidazole; The organic solvent includes one or more of diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, propylene glycol methyl ether, propylene glycol methyl ether acetate, and diacetone alcohol.

9. A method for preparing the negative photosensitive resin composition according to any one of claims 1 to 8, characterized in that, Includes the following steps: The components of the above negative photosensitive resin composition are thoroughly mixed and stirred at room temperature, and then filtered using a filter membrane in a two-stage pressure filtration method to obtain the negative photosensitive resin composition.

10. The application of the negative photosensitive resin composition according to claim 9 in the field of electronic display devices.

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