Pigment for red photoresist and preparation and application thereof

Abstract

The invention belongs to the field of liquid crystal display, and particularly relates to a pigment for red photoresist and preparation and application thereof. The pigment comprises a red organic pigment and a dispersant. Wherein the red organic pigment is one of P.R.149, P.R.177, P.R.179, P.R.242, P.R.244, P.R.254, P.R.264 and P.R.291, and the red organic pigment is one of P.R.149, P.R.177, P.R.179, P.R.242, P.R.244, P.R.254, P.R.264 and P.R.291. The dispersing agent is applied to the photoresist pigment, so that the pigment can be promoted to be uniformly dispersed in a solvent type or solvent-free type system to meet the developing precision requirement.

Description

Technical Field

[0001] This invention belongs to the field of liquid crystal displays, specifically relating to a red photoresist pigment and its preparation and application. Background Technology

[0002] Color filters are a crucial component of liquid crystal displays (LCDs), enabling the display to present rich color images. The performance of the color photoresist used to fabricate the color filters is key to the quality of the display, generally requiring high brightness, high contrast, high transmittance, and high stability. The fabrication of color photoresist involves two parts: first, pigments are used to prepare a color paste, and then the color paste is used to prepare the color photoresist. The color paste mainly includes pigments, additives, and solvents.

[0003] Pigments, as colorants, are of paramount importance. They must be uniform in size, non-agglomerated, and stably dispersed in the photoresist paste during use. This is crucial for achieving high contrast and high brightness. Currently, dispersants are added to treat the pigments to achieve the desired size and improve dispersion. However, existing methods still have limitations, such as excessively large particle size, uneven particle size distribution, poor stability, and poor contrast.

[0004] The selection and development of dispersants are often limited to specific application systems. For example, Chinese patent application CN117487375A provides a red dye derivative, which can be used as a dispersant in high-temperature direct-injection red disperse dye inks. However, high-temperature disperse inks and photoresist pigments belong to different technical fields, and there are significant differences in their performance requirements, application scenarios, and dispersion media. The former is generally an aqueous dispersion system, while the pigments used in photoresist usually need to be stably dispersed in an oil-based medium. Specifically, the core design of dispersants for high-temperature disperse inks lies in the adaptation to inkjet processes and the high-temperature color-fixing requirements in textile printing and dyeing scenarios. The aim is to improve the dispersibility, stability, and color fastness of pigments in printing inks, without considering special performance constraints such as photochemical reaction compatibility. However, photoresist pigment systems have multi-dimensional and stringent performance requirements for dispersants. Therefore, the design ideas and technical solutions of dispersants suitable for ink systems are difficult to directly transfer to photoresist systems, and there are currently no reports of successful cross-domain applications.

[0005] In summary, developing a pigment suitable for photoresist systems, possessing excellent dispersion stability, and meeting requirements such as high contrast and high brightness has significant application value. Summary of the Invention

[0006] In order to solve the above-mentioned problems in the prior art, the purpose of this invention is to improve the dispersibility and stability of pigment particles for photoresist while ensuring that the red spectral performance is not affected, thereby providing a red photoresist pigment and its preparation and application.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A dispersant is used to prepare pigments for red photoresists. The use of this dispersant can meet the demanding requirements of photoresist applications, ensuring dispersion stability throughout the coating, exposure, and development processes.

[0008] The structure of the dispersant is shown in Formula 1:

[0009] Formula 1 In the formula, R1 and R2, whether the same or different, are selected from hydrogen, C1-C4 alkyl groups, hydroxyethyl, cyanoethyl, methanesulfonyl, formyl, or the group -(CH2). n -X, where X is -COOCH3, -OCOCH3, a carboxylic acid group or a sulfonic acid group, and n is an integer from 1 to 3; R3 is hydrogen, a C1-C4 alkyl group, hydroxyl group, amino group, halogen, formamido group, acetamido group, propionamido group, methanesulfonamide group, or the group -NH(CH2). m -Y, where Y is a carboxylic acid group or a sulfonic acid group, and m is an integer from 1 to 3; R4 and R5, whether the same or different, are selected from hydrogen, C1-C4 alkyl, C1-C4 alkoxy, halogen, nitro, cyano, carboxylic acid or sulfonic acid. R6 is hydrogen, a C1-C4 alkyl group, a C1-C4 alkoxy group, a nitro group, a halogen group, a cyano group, a methyl formate group, a carboxylic acid group, a sulfonic acid group, or a phosphoric acid group; and R1-R6 contains at least one carboxylic acid group or a sulfonic acid group.

[0010] Preferably, in the dispersant formula, R1 is selected from hydrogen, C1-C4 alkyl, cyanoethyl, or a group -(CH2). n -X, where X is -COOCH3, -OCOCH3, a carboxylic acid group or a sulfonic acid group, and n is an integer from 1 to 3; R2 is selected from hydrogen, C1-C4 alkyl groups, cyanoethyl groups, and the group -(CH2). n -X, where X is -COOCH3, -OCOCH3, a carboxylic acid group or a sulfonic acid group, and n is an integer from 1 to 3; R3 is selected from hydrogen, chlorine, acetamido, propionamido, methanesulfonamide, or the group -NH(CH2). m -Y, where Y is a carboxylic acid group or a sulfonic acid group, and m is an integer from 1 to 3; R4 and R5 can be the same or different and are selected from hydrogen, chlorine, bromine, cyano, carboxylic acid or sulfonic acid groups; R6 is selected from methyl, nitro, carboxylic acid, and sulfonic acid groups; and R1-R6 contain at least one carboxylic acid or sulfonic acid group.

[0011] More preferably, in the dispersant formula, R1 and R2, which may be the same or different, are selected from C1-C4 alkyl, cyanoethyl, or -(CH2) groups. n -X, where X is -COOCH3, -OCOCH3, a carboxylic acid group or a sulfonic acid group, and n is an integer from 1 to 3; R3 is selected from hydrogen, chlorine, propionamide, methanesulfonamide, or the group -NH(CH2). m -Y, where Y is a carboxylic acid group or a sulfonic acid group, and m is an integer from 1 to 3; R4 and R5 can be the same or different and can be selected from hydrogen, chlorine, bromine or cyano groups; R6 is selected from methyl, nitro, carboxylic acid, and sulfonic acid groups; and R1-R6 contain at least one carboxylic acid or sulfonic acid group.

[0012] A red pigment for use in color photoresist comprises a red organic pigment and the dispersant.

[0013] The red organic pigment is one of PR149, PR177, PR179, PR242, PR244, PR254, PR264, and PR291.

[0014] The amount of the dispersant used is 0.5wt%-10wt% of the mass of the red organic pigment.

[0015] A method for preparing the pigment for the red photoresist, wherein a red organic pigment is mixed with a dispersant, and an inorganic salt and an organic solvent are added for a kneading process.

[0016] Furthermore, the kneading temperature is -10℃ to 100℃, preferably -5℃ to 80℃, and the kneading temperature can be changed in stages during the kneading process. The inorganic salt is selected from water-soluble inorganic salts such as sodium chloride, potassium chloride, and sodium sulfate. The amount used is 12-20 times that of the red organic pigment, and the particle size of the inorganic salt is 1μm-50μm, which can be obtained by mechanical crushing or commercially available products.

[0017] The organic solvent is a water-soluble organic solvent that inhibits crystal growth. Examples include ethylene glycol, propylene glycol, glycerol, ethylene glycol monomethyl ether, ethylene glycol methyl ether acetate, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol methyl ether acetate, methanol, ethanol, and acetone. Water-insoluble solvents such as toluene, xylene, chlorobenzene, dichlorobenzene, and nitrobenzene may also be added.

[0018] The amount of solvent used is 0.1-5 times that of the red organic pigment.

[0019] A pigment for red photoresist is used to prepare a color paste for red photoresist.

[0020] A color paste for red photoresist includes the pigment, resin, and solvent for red photoresist.

[0021] The resin is an acrylic resin, a polyamic acid resin, etc.; the solvent is one or more of methanol, ethanol, toluene, xylene, tetrahydrofuran, acetone, ethylene glycol monomethyl ether, ethylene glycol methyl ether acetate, propylene glycol monomethyl ether, propylene glycol methyl ether acetate, N,N-dimethylformamide, and N-methylpyrrolidone.

[0022] A method for preparing a color paste for red photoresist involves mixing and shaking a red photoresist pigment, resin, and solvent to obtain a color paste for red photoresist.

[0023] The beneficial effects of this invention are as follows: This invention applies a dispersant to photoresist pigments, which not only promotes uniform dispersion of pigments in solvent-based or solvent-free systems to meet development precision requirements, but also forms a chemical synergistic effect with related components such as resins, solvents, photopolymerizable monomers, photoinitiators, and additives. That is, it does not interfere with monomer conversion rate and cross-linking network formation, nor does it react with other components. At the same time, it can regulate and maintain the viscosity of the system, pigment particle size, and other properties to meet the high requirements of photoresist usage conditions, and ensure the dispersion stability of the entire process of coating, exposure, and development.

[0024] This invention applies dispersants to the field of photoresist, achieving significant improvements in stability, dispersibility, contrast, and brightness. Detailed Implementation

[0025] The following specific embodiments are used to further illustrate the present invention. It should be noted that the specific embodiments described herein are only for illustration and explanation of the present invention and are not limited to the present invention. Various modifications can be made within the scope defined by the claims.

[0026] The red organic pigment in this example is commercially available. The resin is butyl methacrylate:acrylic acid = 3:7, Mw = 13000; the dispersant is prepared according to patent CN117487375A (structure shown below). All other reagents are commercially available unless otherwise stated.

[0027] Example 1 Preparation of pigments for red photoresist Weigh out 50g of PR177, 2.5g of dispersant 1, 150g of diethylene glycol, and 600g of sodium chloride (<50μm). Pour PR177 and dispersant 1 into the kneader chamber, add sodium chloride and diethylene glycol, start the kneading process, knead at 80℃ for 1 hour, then cool to 5℃ and continue kneading for 5 hours. Remove the kneaded material, add 2kg of water, heat to 60℃, stir for 1 hour, filter, wash, and vacuum dry at 55℃ to obtain red photoresist pigment 1.

[0028] Preparation of color paste for red photoresist Weigh 5g of the above-mentioned red photoresist pigment 1, 30g of propylene glycol methyl ether acetate and 2g of acrylic resin, add 40mL of 0.3-0.4mm zirconium beads to a sealed container and shake in a shaker for 3 hours. Filter out the zirconium beads to obtain red photoresist pigment R-1.

[0029] Example 2 Preparation of pigments for red photoresist Weigh 50g of PR179, 0.25g of dispersant 1, 200g of diethylene glycol, 5g of xylene, and 700g of sodium chloride (<50μm). Pour PR179 and dispersant 1 into the kneader chamber, add sodium chloride, diethylene glycol, and xylene, and start the kneading process. Knead at 60℃ for 1 hour, then cool to -5℃ and continue kneading for 7 hours. Remove the kneaded material, add 2kg of water, heat to 60℃, stir for 1 hour, filter, wash, and vacuum dry at 55℃ to obtain red photoresist pigment 2.

[0030] Preparation of color paste for red photoresist Weigh 5g of the above-mentioned red photoresist pigment 2, 30g of propylene glycol methyl ether acetate, 1.5g of PB-821 and 2g of acrylic resin, add 40mL of 0.3-0.4mm zirconium beads, add to a sealed container and shake in a shaker for 3 hours, filter out the zirconium beads, and obtain red photoresist pigment R-2.

[0031] Example 3 Preparation of pigments for red photoresist Weigh 50g of PR254, 5g of dispersant 2, 250g of diethylene glycol, 10g of methanol, and 1000g of sodium chloride (<50μm). Pour PR254 and dispersant 2 into the kneader chamber, add sodium chloride, diethylene glycol, and methanol, and start the kneading process. Knead at 80℃ for 1 hour, then cool to 5℃ and continue kneading for 5 hours. Remove the kneaded material, add 2kg of water, heat to 60℃, stir for 1 hour, filter, wash, and vacuum dry at 55℃ to obtain red photoresist pigment 3.

[0032] Preparation of color paste for red photoresist Weigh 5g of the above-mentioned red photoresist pigment 3, 30g of propylene glycol methyl ether acetate, 1.5g of PB-821 and 2g of acrylic resin, add 40mL of 0.3-0.4mm zirconium beads, add to a sealed container and shake in a shaker for 3 hours, filter out the zirconium beads, and obtain red photoresist pigment R-3.

[0033] Example 4 Preparation of pigments for red photoresist Weigh 50g of PR179, 2g of dispersant 3, 150g of diethylene glycol, and 750g of sodium chloride (<50μm). Pour PR179 and dispersant 3 into the kneader chamber, add sodium chloride and diethylene glycol, and start the kneading process at 60℃ for 8 hours. Remove the kneaded material, add 2kg of water, heat to 60℃, stir for 1 hour, filter, wash, and vacuum dry at 55℃ to obtain red photoresist pigment 4.

[0034] Preparation of color paste for red photoresist Weigh 5g of the above-mentioned red photoresist pigment 4, 30g of propylene glycol methyl ether acetate, 1.5g of PB-821 and 2g of acrylic resin, add 40mL of 0.3-0.4mm zirconium beads, add to a sealed container and shake in a shaker for 3 hours, filter out the zirconium beads, and obtain red photoresist pigment R-4.

[0035] Example 5 Preparation of pigments for red photoresist Weigh 50g of PR179, 1.5g of dispersant 4, 150g of diethylene glycol, and 750g of sodium chloride (<50μm). Pour PR179 and dispersant 4 into the kneader chamber, add sodium chloride and diethylene glycol, and start the kneading process at 60℃ for 8 hours. Remove the kneaded material, add 2kg of water, heat to 60℃, stir for 1 hour, filter, wash, and vacuum dry at 55℃ to obtain red photoresist pigment 5.

[0036] Preparation of color paste for red photoresist Weigh 5g of the above-mentioned red photoresist pigment 5, 30g of propylene glycol methyl ether acetate, 1.5g of PB-821 and 2g of acrylic resin, add 40mL of 0.3-0.4mm zirconium beads, add to a sealed container and shake in a shaker for 3 hours, filter out the zirconium beads, and obtain red photoresist pigment R-5.

[0037] Comparative Example 1 The difference from Example 1 is that dispersant 1 is not added, but the other conditions are the same as in Example 1.

[0038] Comparative Example 2 The difference from Example 2 is that dispersant 1 is not added, but the other conditions are the same as in Example 2.

[0039] Comparative Example 3 The difference from Example 3 is that dispersant 2 is not added, but the other conditions are the same as in Example 3.

[0040] Comparative Example 4 The difference from Example 4 is that dispersant 3 is replaced with dihydrogenated rosin, while the other conditions are the same as in Example 4.

[0041] Comparative Example 5 The difference from Example 5 is that dispersant 4 is replaced with dispersant YUS-FS3000, while the other conditions are the same as in Example 5.

[0042] The relevant performance tests were performed on Examples 1-5 and Comparative Examples 1-5 of the present invention. The testing instruments included: Omni nanoparticle size analyzer (Brookhaven Instruments, USA); Dektak XT step tester (Brookhaven Instruments, USA); and Tsubosaka Electric, CT-1-STB1 contrast meter (Tsubosaka Electric, Japan).

[0043] 1. Particle size test.

[0044] Take 0.1g of color paste, dilute it with 50g of propylene glycol methyl ether acetate, and test the particle size; place the color paste in a 60℃ oven for one week, dilute it again using the same method, and test the particle size (D50, unit: nm). Relevant data are shown in Table 1.

[0045] Table 1

[0046] As shown in Table 1, the particle size changes in Examples 1-5 were minimal after heat storage. In contrast, the changes in the comparative examples were significant, and Comparative Example 2 underwent a change in properties after heat storage, becoming gel-like and extremely viscous, rendering it unusable. This demonstrates that the dispersant added in this invention plays a crucial role in dispersibility and stability, and its effect is superior to common dispersants.

[0047] 2. Film thickness, brightness, and contrast tests.

[0048] 1 mL of pigment was spin-coated onto glass slides at speeds of 500 rpm, 1500 rpm, and 2000 rpm, respectively. The coated glass slides were then placed on a heating plate and heated at 120°C for 90 s, followed by heating in an oven at 230°C for 30 min. (Y = 0.3200 was kept constant). Relevant data are shown in Table 2.

[0049] Table 2

[0050] As shown in Table 2, when y=0.3200 is fixed, the color difference is not significant. Although the film thickness is similar, the film thickness in the examples is thinner, which is beneficial for improving brightness and saving energy in practical applications. The contrast ratio and brightness differ greatly. Examples 1-5 all show good results, but comparative examples 1-5 are significantly worse than the examples, especially with a significant decrease in contrast ratio.

[0051] The above results demonstrate that the addition of a dispersant enhances various properties of the color paste, such as brightness and contrast. In Example 3, compared to other examples, adding too much dispersant resulted in a decrease in brightness and contrast. Therefore, the amount of dispersant also affects the color paste performance and needs to be strictly controlled.

Claims

1. A red photoresist pigment, characterized in that: It contains a red organic pigment and a dispersant; wherein the red organic pigment is one of PR149, PR177, PR179, PR242, PR244, PR254, PR264, and PR291. The structure of the dispersant is shown in Formula 1: Formula 1 In the formula, R1 and R2, whether the same or different, are selected from hydrogen, C1-C4 alkyl groups, hydroxyethyl, cyanoethyl, methanesulfonyl, formyl, or the group -(CH2). n -X, where X is -COOCH3, -OCOCH3, a carboxylic acid group or a sulfonic acid group, and n is an integer from 1 to 3; R3 is hydrogen, a C1-C4 alkyl group, hydroxyl group, amino group, halogen, formamido group, acetamido group, propionamido group, methanesulfonamide group, or the group -NH(CH2). m -Y, where Y is a carboxylic acid group or a sulfonic acid group, and m is an integer from 1 to 3; R4 and R5, whether the same or different, are selected from hydrogen, C1-C4 alkyl, C1-C4 alkoxy, halogen, nitro, cyano, carboxylic acid or sulfonic acid. R6 is hydrogen, a C1-C4 alkyl group, a C1-C4 alkoxy group, a nitro group, a halogen group, a cyano group, a methyl formate group, a carboxylic acid group, a sulfonic acid group, or a phosphoric acid group; and R1-R6 contains at least one carboxylic acid group or a sulfonic acid group.

2. The red photoresist pigment according to claim 1, characterized in that: The amount of dispersant used is 0.5wt%-10wt% of the mass of the red organic pigment.

3. A method for preparing the red photoresist pigment according to claim 1, characterized in that: Red organic pigments are mixed with dispersants, and then kneaded with inorganic salts and organic solvents.

4. The method for preparing red photoresist pigment according to claim 1, characterized in that: The kneading temperature is -10℃ to 100℃.

5. The method for preparing red photoresist pigment according to claim 1, characterized in that: The inorganic salt is selected from one or more of sodium chloride, potassium chloride, and sodium sulfate; the amount of inorganic salt used is 12-20 times that of the red organic pigment; the particle size of the inorganic salt is 1μm-50μm.

6. The method for preparing red photoresist pigment according to claim 1, characterized in that: The organic solvent is a water-soluble organic solvent that inhibits crystal growth; the amount of solvent used is 0.1-5 times that of the red organic pigment.

7. A red photoresist pigment as described in claim 1 is used to prepare a red photoresist color paste.

8. A color paste for red photoresist, characterized in that: The method includes the pigment, resin, and solvent for the red photoresist as described in claim 1; wherein the resin is an acrylic resin or a polyamic acid resin; and the solvent is one or more of methanol, ethanol, toluene, xylene, tetrahydrofuran, acetone, ethylene glycol monomethyl ether, ethylene glycol methyl ether acetate, propylene glycol monomethyl ether, propylene glycol methyl ether acetate, N,N-dimethylformamide, and N-methylpyrrolidone.

9. A method for preparing a color paste for red photoresist as described in claim 8, characterized in that: A red photoresist color paste is obtained by mixing and shaking pigments, resins, and solvents.

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