A pigment dispersion for a color filter, a preparation method thereof, and a color filter.

Abstract

This invention discloses a pigment dispersion for color filters, a preparation method thereof, and a color filter. The pigment dispersion comprises a pigment, a dispersant, a resin, additives, and a solvent. The resin has the structure shown in general formula (I). R1 ​​is selected from H, methyl, and carboxyl groups; R2 is selected from H, methyl, carboxyl, benzyl, and benzoic acid groups; R3 is selected from methyl, ethyl, n-propyl, n-butyl, n-pentyl, and n-hexyl groups; R4 is selected from H, methyl, ethyl, n-propyl, and isopropyl groups; R5, R6, R7, and R8 are each independently selected from H or methyl groups; and n is 30–60. This pigment dispersion can achieve a low pigment particle size and exhibits excellent dispersion performance and stability.

Description

Technical Field

[0001] This invention belongs to the field of fine chemical technology, specifically relating to a pigment dispersion for color filters, its preparation method, and a color filter using the pigment dispersion for color filters. Background Technology

[0002] Abundant visual information permeates people's production and daily lives, yet the human eye, as the visual organ that receives the most information, cannot record every moment. With continuous technological advancements, display technology (visual information processing technology) has emerged. Flat panel display devices, including liquid crystal displays (LCDs), organic light-emitting diode (OLEDs), electroluminescent displays (ELDs), and plasma display panels (PDPs), are increasingly being used in televisions, computers, projectors, automotive displays, game consoles, and more. In particular, liquid crystal displays have developed rapidly in recent years, becoming the mainstream of flat panel displays.

[0003] With the rapid development of display technology, people have increasingly higher requirements for the color and image quality of display devices. Liquid crystal displays (LCDs), with their excellent color reproduction and large screen sizes, are becoming increasingly popular and have become the mainstream of flat panel displays. Color filters, as a core component, determine the final performance of flat panel displays. Currently, traditional color filter manufacturing methods include dyeing, pigment dispersion, electrodeposition, and printing. Dyeing methods use dyes with poor thermal stability that cannot meet the requirements of subsequent processes, while color filters prepared by electrodeposition and printing methods have low clarity and cannot meet performance requirements. Therefore, pigment dispersion is the most commonly used preparation method in the industry.

[0004] The core technical challenge in pigment dispersion methods lies in dispersing pigment particles to a low particle size. When pigment particles are of a low size, their surface energy is relatively large, leading to particle aggregation and eventual sedimentation under gravity, which macroscopically manifests as a deterioration of the pigment dispersion. Therefore, there is an urgent need to provide a pigment dispersion with small particle size and high stability, along with its preparation method. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide a pigment dispersion for color filters, a preparation method thereof, and a color filter; the pigment dispersion can achieve a low pigment particle size and has excellent dispersion performance and stability.

[0006] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution:

[0007] A pigment dispersion for a color filter, comprising a pigment, a dispersant, a resin, an additive, and a solvent, wherein the resin has a structure shown in general formula (I):

[0008]

[0009] Among them, R1 is selected from H, methyl, and carboxyl; R2 is selected from H, methyl, carboxyl, benzyl, and benzoic acid; R3 is selected from methyl, ethyl, n-propyl, n-butyl, n-pentyl, and n-hexyl; R4 is selected from H, methyl, ethyl, n-propyl, and isopropyl; R5, R6, R7, and R8 are each independently selected from H or methyl; n is 30 to 60.

[0010] Furthermore, the resin is obtained by copolymerization of an unsaturated amide containing a benzene ring, an unsaturated carboxylic acid ester containing an epoxy group, an unsaturated carboxylic acid, and an unsaturated aromatic hydrocarbon.

[0011] The unsaturated amides containing a benzene ring can be selected from compounds with the following structural formulas:

[0012]

[0013] Unsaturated carboxylic acid esters containing epoxy groups can be selected from compounds with the following structural formulas:

[0014]

[0015]

[0016] Unsaturated carboxylic acids can be selected from compounds with the following structural formulas:

[0017]

[0018] Unsaturated aromatic hydrocarbons can be selected from compounds shown in the following structural formulas:

[0019]

[0020]

[0021] The resin preparation process is as follows: 10-30 parts of unsaturated carboxylic acid, 10-30 parts of unsaturated amide containing a benzene ring, 20-50 parts of unsaturated carboxylic acid ester containing an epoxy group, and 20-30 parts of unsaturated aromatic hydrocarbon are added to a reactor. Under an inert atmosphere (such as nitrogen), the above substances are stirred and mixed evenly. The mixture is then gradually heated to 80°C. Next, 50-500 parts of a propylene glycol methyl ether acetate solution containing 1-12 parts of initiator are added. The reaction temperature is maintained at 80°C for 2 hours. After that, the reaction solution is further heated to 110°C and reacted for another 2 hours. The mixture is then naturally cooled to room temperature, and the product resin is collected.

[0022] Furthermore, the pigment dispersion for the color filter comprises 5%–50% pigment, 2%–40% dispersant, 2%–50% resin, 0–10% additives, and 30%–80% solvent.

[0023] Furthermore, the pigment is at least one of red, green, blue, yellow, and purple pigments.

[0024] Furthermore, the dispersant is at least one of polyurethane, polyacrylate, polyester, and polysiloxane, such as DISPER BYK-2000, DISPER BYK-163, BYK-LPN22102 (manufactured by BYK Chemicals, Germany), EFKA46, and EFKA47.

[0025] Furthermore, the additive is at least one of leveling agent, filler, antioxidant, and anti-crystallizing agent, such as BYK-323, Sumitomo FC-430, and BASF IRGANOX 1010.

[0026] Furthermore, the solvent is preferably at least one selected from ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, acetone, methyl acetone, ethanol, propanol, and ethylene glycol.

[0027] The present invention further provides a method for preparing a pigment dispersion for a color filter, specifically comprising: mixing a dispersant, a resin, an additive, and a solvent, then adding a pigment for pre-dispersion, grinding, and filtration to obtain a pigment dispersion.

[0028] The present invention further provides a color filter, which is specifically made using the pigment dispersion liquid for color filters described above.

[0029] Furthermore, the color filter is used in flat panel display devices.

[0030] The beneficial effects of this invention are:

[0031] The resin in this invention is obtained by copolymerizing unsaturated amides containing benzene rings, unsaturated carboxylic acid esters containing epoxy groups, unsaturated carboxylic acids, and unsaturated aromatic hydrocarbons. The amino groups in the synthesized resin structure have a high affinity for organic pigments, which can improve the fineness of the pigments. The aromatic groups in the resin structure can improve the affinity for solvents, thereby promoting better pigment dispersion, improving the dispersion stability of pigments, enhancing the dispersion effect of dispersants, and meeting the temperature requirements of subsequent process stages when applied to color filters, while also achieving excellent contrast performance.

[0032] The resin in this invention can work in conjunction with a dispersant to effectively disperse micronized pigments without increasing the amount of dispersant added, thereby improving the dispersion stability of the pigment dispersion and achieving a nanoscale particle size and a narrower particle size distribution. Detailed Implementation

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] This invention provides a pigment dispersion for color filters; the pigment dispersion comprises 5%–50% pigment, 2%–40% dispersant, 2%–50% resin, 0–10% additives, and 30%–80% solvent; the resin has the structure shown in general formula (I):

[0035]

[0036] Among them, R1 is selected from H, methyl, and carboxyl; R2 is selected from H, methyl, carboxyl, benzyl, and benzoic acid; R3 is selected from methyl, ethyl, n-propyl, n-butyl, n-pentyl, and n-hexyl; R4 is selected from H, methyl, ethyl, n-propyl, and isopropyl; R5, R6, R7, and R8 are each independently selected from H or methyl; n is 30 to 60.

[0037] This resin is obtained by copolymerization of an unsaturated amide containing a benzene ring, an unsaturated carboxylic acid ester containing an epoxy group, an unsaturated carboxylic acid, and an unsaturated aromatic hydrocarbon. The specific preparation process is as follows: 10-30 parts of unsaturated carboxylic acid, 10-30 parts of an unsaturated amide containing a benzene ring, 20-50 parts of an unsaturated carboxylic acid ester containing an epoxy group, and 20-30 parts of an unsaturated aromatic hydrocarbon are added to a reactor. Under an inert atmosphere (such as nitrogen), the above substances are stirred and mixed evenly. The mixture is then gradually heated to 80°C, and 50-500 parts of a propylene glycol methyl ether acetate solution containing 1-12 parts of initiator are added. The reaction temperature is maintained at 80°C for 2 hours. After that, the reaction solution is further heated to 110°C and reacted for another 2 hours. The mixture is then naturally cooled to room temperature, and the product resin is obtained.

[0038] The pigment in the pigment dispersion is at least one of red, green, blue, yellow, and purple pigments.

[0039] The dispersant in the pigment dispersion is at least one of polyurethane, polyacrylate, polyester, and polysiloxane, such as DISPER BYK-2000, DISPER BYK-163, BYK-LPN22102 (manufactured by BYK Chemicals, Germany), EFKA46, and EFKA47.

[0040] The additives in this pigment dispersion are at least one of leveling agents, fillers, antioxidants, and anti-gelling agents, such as BYK-323, Sumitomo FC-430, and BASF IRGANOX 1010.

[0041] The solvent in the pigment dispersion is preferably at least one of ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, acetone, methyl acetone, ethanol, propanol, and ethylene glycol, and more preferably ethylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, or ethylene glycol.

[0042] The present invention further provides a method for preparing a pigment dispersion for a color filter, specifically: mixing a dispersant, resin, additive, and solvent, adding pigment for pre-dispersion, and then coarsely grinding, finely grinding, and filtering to obtain a pigment dispersion.

[0043] The present invention further provides a color filter, which is specifically prepared using the pigment dispersion for color filters described above through subsequent processes. Furthermore, this color filter is used in flat panel display devices.

[0044] The present invention will be further described below with reference to specific embodiments. In the following embodiments and comparative examples, "number of parts" refers to the number of parts by weight.

[0045] Example of resin synthesis:

[0046] Synthesis example 1

[0047] 20 parts of methacrylic acid, 25 parts of unsaturated amide compound (the compound shown in structural formula (1)), 30 parts of glycidyl acrylate, and 25 parts of styrene were added to a reactor. Under an inert atmosphere, the mixture was stirred until homogeneous, and the temperature was increased to 80°C at a rate of 10°C / min. 10 parts of azobisisobutyronitrile and 250 parts of propylene glycol methyl ether acetate were added, and the temperature was maintained at 80°C for 2 hours. Subsequently, the reaction mixture was heated to 110°C and reacted for another 2 hours. Then, it was naturally cooled to room temperature to obtain the reaction product resin A, which was found to have a Mw of 8200.

[0048] Synthesis example 2

[0049] 20 parts of ethyl acrylic acid, 25 parts of unsaturated amide compound (the compound shown in structural formula (1)), 30 parts of glycidyl acrylate, and 25 parts of styrene were added to a reactor. Under an inert atmosphere, the mixture was stirred until homogeneous, and the temperature was increased to 80°C at a rate of 10°C / min. 10 parts of azobisisobutyronitrile and 250 parts of propylene glycol methyl ether acetate were added, and the temperature was maintained at 80°C for 2 hours. Subsequently, the reaction mixture was heated to 110°C and reacted for another 2 hours. Then, it was naturally cooled to room temperature to obtain the reaction product resin B, which was found to have a Mw of 8100.

[0050] Synthesis example 3

[0051] 25 parts of methacrylic acid, 30 parts of unsaturated amide compound (the compound shown in structural formula (2)), 30 parts of glycidyl acrylate, and 25 parts of styrene were added to a reactor. Under an inert atmosphere, the mixture was stirred until homogeneous, and the temperature was increased to 80°C at a rate of 10°C / min. 10 parts of azobisisobutyronitrile and 250 parts of propylene glycol methyl ether acetate were added, and the temperature was maintained at 80°C for 2 hours. Subsequently, the reaction mixture was heated to 110°C and reacted for another 2 hours. Then, it was naturally cooled to room temperature to obtain the reaction product resin C, which was found to have a Mw of 8500.

[0052] Synthesis example 4

[0053] 20 parts maleic acid, 25 parts unsaturated amide compound (the compound shown in structural formula (1)), 30 parts glycidyl acrylate, and 25 parts styrene were added to a reactor. Under an inert atmosphere, the mixture was stirred until homogeneous, and the temperature was increased to 80°C at a rate of 10°C / min. 10 parts azobisisobutyronitrile and 250 parts propylene glycol methyl ether acetate were added, and the temperature was maintained at 80°C for 2 hours. The reaction mixture was then heated to 110°C and reacted for another 2 hours. The mixture was then allowed to cool naturally to room temperature to obtain the reaction product resin D, which was found to have a Mw of 7900.

[0054] Synthesis example 5

[0055] 25 parts maleic acid, 25 parts unsaturated amide compound (the compound shown in structural formula (1)), 30 parts glycidyl acrylate, and 25 parts p-styrene were added to a reactor. Under an inert atmosphere, the mixture was stirred until homogeneous, and the temperature was increased to 80°C at a rate of 10°C / min. 10 parts azobisisobutyronitrile and 250 parts propylene glycol methyl ether acetate were added, and the temperature was maintained at 80°C for 2 hours. The reaction mixture was then heated to 110°C and reacted for another 2 hours. The mixture was then allowed to cool naturally to room temperature to obtain the reaction product resin E, which was found to have a Mw of 8200.

[0056] Synthesis example 6

[0057] 20 parts of methacrylic acid, 25 parts of unsaturated amide compound (the compound shown in structural formula (2)), 30 parts of glycidyl acrylate, and 25 parts of p-styrene were added to a reactor. Under an inert atmosphere, the mixture was stirred until homogeneous, and the temperature was increased to 80°C at a rate of 10°C / min. 10 parts of azobisisobutyronitrile and 250 parts of propylene glycol methyl ether acetate were added, and the temperature was maintained at 80°C for 2 hours. Subsequently, the reaction mixture was heated to 110°C and reacted for another 2 hours. Then, it was naturally cooled to room temperature to obtain the reaction product resin F, which was measured to have a Mw of 7800.

[0058] Synthesis Example 7

[0059] 20 parts of methacrylic acid, 25 parts of unsaturated amide compound (the compound shown in structural formula (1)), 30 parts of glycidyl ethyl acrylate, and 25 parts of styrene were added to a reactor. Under an inert atmosphere, the mixture was stirred until homogeneous, and the temperature was increased to 80°C at a rate of 10°C / min. 10 parts of azobisisobutyronitrile and 250 parts of propylene glycol methyl ether acetate were added, and the temperature was maintained at 80°C for 2 hours. Subsequently, the reaction mixture was heated to 110°C and reacted for another 2 hours. Then, it was naturally cooled to room temperature to obtain the reaction product resin G, which was found to have a Mw of 8300.

[0060] Preparation of pigment dispersion

[0061] Example 1

[0062] 30 parts of BYK2000, 25 parts of the obtained resin A, and 120 parts of propylene glycol methyl ether acetate were thoroughly mixed in a disperser at a speed of 2000 r / min. Then, 35 parts of CI Pigment Red 254 were added and the mixture was further thoroughly mixed to obtain a pigment dispersion premix. The mixture was then transferred to a sand mill and sand-milled for 2 hours to obtain pigment dispersion 1.

[0063] Example 2

[0064] 30 parts of BYK2000, 25 parts of the obtained resin B, and 120 parts of propylene glycol methyl ether acetate were thoroughly mixed in a disperser at a speed of 2000 r / min. Then, 35 parts of CI pigment red 254 were added and the mixture was further thoroughly mixed to obtain a pigment dispersion premix. The mixture was then transferred to a sand mill and sand-milled for 2 hours to obtain pigment dispersion 2.

[0065] Example 3

[0066] 30 parts of BYK2000, 25 parts of the obtained resin A, and 120 parts of propylene glycol methyl ether acetate were thoroughly mixed in a disperser at a speed of 2000 r / min. Then, 35 parts of CI Pigment Red 177 were added and the mixture was further thoroughly mixed to obtain a pigment dispersion premix. The mixture was then transferred to a sand mill and sand-milled for 2 hours to obtain pigment dispersion 3.

[0067] Example 4

[0068] 30 parts of BYK2000, 25 parts of the obtained resin B, and 120 parts of propylene glycol methyl ether acetate were thoroughly mixed in a disperser at a speed of 2000 r / min. Then, 35 parts of CI pigment red 177 were added and the mixture was further thoroughly mixed to obtain a pigment dispersion premix. The mixture was then transferred to a sand mill and sand-milled for 2 hours to obtain pigment dispersion 4.

[0069] Example 5

[0070] 30 parts of BYK2000, 25 parts of the obtained resin A, and 120 parts of propylene glycol methyl ether acetate were thoroughly mixed in a disperser at a speed of 2000 r / min. Then, 35 parts of CI pigment green 58 were added and the mixture was further thoroughly mixed to obtain a pigment dispersion premix. The mixture was then transferred to a sand mill and sand-milled for 2 hours to obtain pigment dispersion 5.

[0071] Example 6

[0072] 30 parts of BYK161, 25 parts of the obtained resin C, and 120 parts of propylene glycol methyl ether acetate were thoroughly mixed in a disperser at a speed of 2000 r / min. Then, 35 parts of CI pigment green 58 were added and the mixture was further thoroughly mixed to obtain a pigment dispersion premix. The mixture was then transferred to a sand mill and sand-milled for 2 hours to obtain pigment dispersion 6.

[0073] Example 7

[0074] 30 parts of BYK2000, 25 parts of the obtained resin D, and 120 parts of propylene glycol methyl ether acetate were thoroughly mixed in a disperser at a speed of 2000 r / min. Then, 35 parts of CI pigment blue (15:6) were added and the mixture was further thoroughly mixed to obtain a pigment dispersion premix. The mixture was then transferred to a sand mill and sand-milled for 2 hours to obtain pigment dispersion 7.

[0075] Example 8

[0076] 30 parts of BYK2000, 25 parts of the obtained resin B, and 120 parts of propylene glycol methyl ether acetate were thoroughly mixed in a disperser at a speed of 2000 r / min. Then, 35 parts of CI pigment blue (15:6) were added and the mixture was further thoroughly mixed to obtain a pigment dispersion premix. The mixture was then transferred to a sand mill and sand-milled for 2 hours to obtain pigment dispersion 8.

[0077] Comparative Example 1

[0078] 30 parts of BYK2000, 25 parts of BASF LR8800, and 120 parts of propylene glycol methyl ether acetate were thoroughly mixed in a disperser at a speed of 2000 r / min. Then, 35 parts of CI Pigment Red 254 were added and the mixture was further thoroughly mixed to obtain a pigment dispersion premix. The mixture was then transferred to a sand mill and sand-milled for 2 hours to obtain pigment dispersion 9.

[0079] Comparative Example 2

[0080] 30 parts of BYK2000, 25 parts of BASF LR8986, and 120 parts of propylene glycol methyl ether acetate were thoroughly mixed in a disperser at a speed of 2000 r / min. Then, 35 parts of CI Pigment Red 254 were added and the mixture was further thoroughly mixed to obtain a pigment dispersion premix. The mixture was then transferred to a sand mill and sand-milled for 2 hours to obtain pigment dispersion 10.

[0081] Comparative Example 3

[0082] 30 parts of BYK2000, 25 parts of Toyo HK77030, and 120 parts of propylene glycol methyl ether acetate were thoroughly mixed in a disperser at a speed of 2000 r / min. Then, 35 parts of CI Pigment Red 254 were added and the mixture was further thoroughly mixed to obtain a pigment dispersion premix. The mixture was then transferred to a sand mill and sand-milled for 2 hours to obtain pigment dispersion 11.

[0083] Comparative Example 4

[0084] 30 parts of BYK2000, 25 parts of BASF PE9032, and 120 parts of propylene glycol methyl ether acetate were thoroughly mixed in a disperser at a speed of 2000 r / min. Then, 35 parts of CI Pigment Red 254 were added and the mixture was further thoroughly mixed to obtain a pigment dispersion premix. The mixture was then transferred to a sand mill and sand-milled for 2 hours to obtain pigment dispersion 12.

[0085] Assessment methods and results

[0086] The average particle size and polydispersity (PDI) of the pigment dispersion were tested according to the national standard GB / T 19077-2016 Particle Size Distribution by Laser Diffraction, after 1 day, 7 days, and 30 days, and the rate of change of the average particle size after standing for 30 days. The results are shown in Table 1 below.

[0087] Table 1

[0088]

[0089]

[0090] The test results in Table 1 clearly show that the pigment dispersion provided by the present invention can disperse pigments to the nanoscale and has excellent stable particle size distribution. Compared with pigment dispersions made using commercially available resins, the pigment dispersion provided by the present invention has superior dispersion performance and stability.

[0091] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any modifications or equivalent transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A pigment dispersion liquid for a color filter, characterized by comprising: The pigment dispersion liquid comprises 5-50% of pigment, 2-40% of dispersant, 2-50% of resin, 0-10% of additive and 30-80% of solvent; the resin has a structure shown in general formula (I): （I） R1 is selected from H, methyl, carboxyl; R2 is selected from H, methyl, carboxyl, benzyl, benzoic acid; R3 is selected from methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl; R4 is selected from H, methyl, ethyl, n-propyl, isopropyl; R5, R6, R7, R8 are independently selected from H or methyl; n is 30-60; The resin is obtained by copolymerization of unsaturated amide containing benzene ring, unsaturated carboxylic ester containing epoxy group, unsaturated carboxylic acid and unsaturated aromatic hydrocarbon; The dispersant is at least one of polyurethane, polyacrylate, polyester and polysiloxane.

2. The pigment dispersion liquid for a color filter according to claim 1, characterized by, The pigment is at least one of red pigment, green pigment, blue pigment, yellow pigment and purple pigment.

3. The pigment dispersion liquid for a color filter according to claim 1, characterized by, The additive is at least one of leveling agent, filling agent, antioxidant and anti-condensation agent.

4. The pigment dispersion liquid for a color filter according to claim 1, characterized by, The solvent is at least one of ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, acetone, methyl ketone, ethanol, propanol and ethylene glycol.

5. A method for producing the pigment dispersion liquid for a color filter as claimed in any one of claims 1 to 4, characterized by, The dispersant, resin, additive and solvent are mixed, and then the pigment is added to perform pre-dispersion, grinding and filtration to obtain the pigment dispersion liquid.

6. A color filter characterized by The pigment dispersion liquid is used for the filter for color display device.

7. The color filter according to claim 6, characterized by: The filter is used for flat panel display device.

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