WO2020199463A1 - Method for preparing pigment dispersion - Google Patents

Abstract

Provided in the present invention is a method for preparing a pigment dispersion: using a covalent organic framework material with a network structure as a template, making pigment molecules in the form of a solution crystallise in the network structure of the covalent organic framework, such that the mesh size of the network structure of the covalent organic framework can be used to control the particle size of the pigment crystals; after the pigment is fully crystallised, separating the pigment crystals from the covalent organic framework by means of a salt washing method, and adding a surfactant; thus, a pigment dispersion with high dispersibility and uniform particle size can be obtained and, after post-treatment, the pigment dispersion can be used for preparing colour photoresist, being a high performance pigment capable of achieving the high penetration and high contrast of a display product; the covalent organic framework material can be re-used multiple times.

Description

Preparation method of pigment dispersion Technical field

The invention relates to the field of display technology, in particular to a method for preparing a pigment dispersion.

Background technique

Thin Film Transistor Liquid Crystal Display (TFT-LCD) has many advantages such as thin body, power saving, and no radiation, and has been widely used. Most of the liquid crystal display devices currently on the market are backlight liquid crystal display devices, which include a liquid crystal display panel and a backlight module. Generally, a liquid crystal display panel is composed of a color filter (CF) substrate, a TFT array substrate, a liquid crystal (LC) sandwiched between the color filter substrate and the TFT array substrate, and a sealant; its molding process Generally include: front-end array process and CF process (thin film, yellow light, etching and stripping), middle-end cell process (TFT array substrate and CF substrate bonding) and back-end module assembly (Module) Process (drive IC and printed circuit board pressing); Among them, the front Array process is mainly to form TFT substrates to control the movement of liquid crystal molecules; the front CF process is mainly to form CF substrates; the middle cell process is mainly to form TFT substrates and CF Liquid crystals are added between the substrates; the subsequent module assembly process is mainly to drive the integration of IC pressing and the printed circuit board, and then drive the liquid crystal molecules to rotate and display images.

The CF substrate is the main device used by the LCD to realize color display, and its basic composition usually includes: a glass substrate, a black matrix (Black Matrix, BM), a color filter layer, and so on. Among them, the color filter layer mainly achieves the effect of color display through color photoresist. The light emitted by the backlight is modulated by liquid crystal molecules and enters the CF substrate, and passes through the red (R) photoresist and green photoresist of the color filter layer on the CF substrate. The light filtering function of the (G) photoresist and the blue (B) photoresist respectively display three kinds of light of red, green and blue, and the photoresists of different colors respectively transmit the light of the corresponding color bands, thereby realizing the color display of the display.

At present, the manufacturing method of the color filter layer in TFT-LCD technology is mainly based on the pigment dispersion method. The color filter layer is mainly composed of phthalocyanine, azo, anthraquinone pigments dispersed in the resin, and through coating , Exposure, development and other processes to form R/G/B photoresist patterns. Usually these pigments have poor solubility in organic solvents. For example, the PGMEA (propylene glycol monomethyl ether ester) solvent commonly used in color filters, so that the dispersibility is poor, and the particulate pigments have scattering, which can affect the brightness and LCD brightness. Contrast has a certain influence, therefore, the current pigment color resist dye (Dye), which can effectively solve the problem of solubility and dispersibility, which is beneficial to improve the brightness and contrast of LCD. However, the thermal stability of dyes is poor, and it is difficult to meet the thermal process of the LCD process (usually the highest temperature is 230 ℃). Many dyes undergo thermal cracking due to poor stability during the thermal process, which affects the color of the color filter layer. The degree of influence is great.

With the development of liquid crystal display technology, the requirements for high color gamut, high penetration, high contrast and other performance are getting higher and higher, and the color filter layer is directly related to the color gamut, transmittance and contrast. In the industry, the requirements for pigments in color film photoresists are naturally higher and higher. The high thermal stability of pigments can meet the temperature of the liquid crystal display preparation process. The particle size and particle size distribution of the pigments have become the key to improving product quality. Control factor.

The current methods of preparing pigments are all obtained through the "top-down" approach, that is, through physical methods to achieve the grinding and dispersion of large particles to nano-scale pigments. The particle size dispersion prepared by this method is uneven. And it is difficult to obtain a small size (≤50nm). Therefore, with the high requirements of liquid crystal display technology for color gamut, penetration and contrast, the development of pigments in color film photoresists is also a key factor restricting the development of high-performance liquid crystal display technology.

Summary of the invention

The purpose of the present invention is to provide a method for preparing a pigment dispersion, which uses a template method to prepare a pigment dispersion with uniform particle size, controllable scale and high dispersibility. When the pigment dispersion is used to prepare a color photoresist, it can be Meet the development needs of high color gamut, high penetration and high contrast liquid crystal displays.

In order to achieve the above objective, the present invention provides a method for preparing a pigment dispersion, which includes the following steps:

Step S1: preparing a covalent organic framework material, the covalent organic framework material has a network structure;

Step S2: Provide pigment, prepare the pigment into a pigment solution, place the covalent organic framework material in the pigment solution, that is, use the covalent organic framework material as a template, and let the pigment molecules in the form of a solution in the network structure of the covalent organic framework Medium crystallization, forming pigment crystals;

Step S3: Separate the pigment crystals from the network structure of the covalent organic framework by salt washing, and add a surfactant to obtain a pigment dispersion.

The method for preparing the covalent organic framework material in the step S1 is that the tetrakis (4-formylphenyl) methane compound and the phenylenediamine compound undergo a Schiff base reaction under the action of a catalyst to obtain the covalent organic framework material .

The tetrakis(4-formylphenyl)methane compound is tetrakis(4-formylphenyl)methane or a derivative of tetrakis(4-formylphenyl)methane, and the phenylenediamine compound is terephthalic diamine. Amine or phenylenediamine derivatives;

Wherein, the general structural formula of the tetrakis (4-formylphenyl) methane derivative is

其中，n为中间碳原子连接烷烃的数量，n为1-30；

Wherein, n is the number of alkane connected to the middle carbon atom, n is 1-30;

其中，m为中间苯环的重复单元数，m为1-15。 The general structural formula of the phenylenediamine derivative is

Where m is the number of repeating units of the middle benzene ring, and m is 1-15.

The catalyst used in the step S1 is bis((trifluoromethyl)sulfonyl)imide.

The pigment provided in the step S2 is a red pigment, a green pigment, a yellow pigment or a blue pigment.

The pigments provided in the step S2 are pigment red 254, pigment red 177, pigment green 7, pigment green 36, pigment green 58, pigment yellow 138, pigment yellow 150, pigment yellow 185 and pigment blue B15:1-6 One or more.

The network structure of the covalent organic framework material prepared in the step S1 has a grid, and the equivalent diameter of the grid is 20-60 nm.

The salt lotion used in the salt washing in the step S3 is sodium chloride.

The pigment dispersion is used to prepare color photoresist.

The color photoresist is used to prepare the color photoresist on the color film substrate.

The beneficial effects of the present invention: the preparation method of the pigment dispersion of the present invention uses a covalent organic framework material with a network structure as a template, allowing the pigment molecules to crystallize in the network structure of the covalent organic framework in the form of a solution, so that it can be used The mesh size of the covalent organic framework network structure controls the particle size of the pigment crystals. After the pigment is fully crystallized, the pigment crystals are separated from the covalent organic framework by salt washing, and surfactants are added to obtain A pigment dispersion with high dispersibility and uniform particle size. The pigment dispersion can be used to prepare color photoresist after post-processing. It is a high-performance pigment that can achieve high penetration and high contrast in display products. Covalent organic framework materials Can be reused many times.

In order to further understand the features and technical content of the present invention, please refer to the following detailed description and accompanying drawings of the present invention. However, the accompanying drawings are only provided for reference and illustration and are not used to limit the present invention.

Description of the drawings

The technical solutions and other beneficial effects of the present invention will be made obvious by describing in detail the specific embodiments of the present invention in conjunction with the accompanying drawings.

In the attached picture,

Fig. 1 is a schematic flow chart of the preparation method of the pigment dispersion of the present invention;

Figure 2 is a schematic diagram of the three-dimensional network structure of covalent organic framework materials.

detailed description

In order to further illustrate the technical means adopted by the present invention and its effects, the following will describe in detail in combination with the preferred embodiments of the present invention.

Please refer to Figure 1. The present invention provides a method for preparing a pigment dispersion, which is used to prepare a color photoresist, and then used to prepare a color photoresist on a color film substrate, which can achieve high penetration of display products. And high-contrast high-performance pigments.

Example 1: Using the network structure of covalent organic framework materials (Covalent Organic Frameworks, COF) to prepare a red pigment dispersion

The first embodiment includes the following steps:

Step S1: Prepare a covalent organic framework material, the covalent organic framework material has a network structure, and during the preparation process, the organic building units are connected together by covalent bonds to form a porous framework with a periodic structure.

Specifically, the covalent organic framework material can be produced in the following manner: the tetrakis (4-formylphenyl) methane compound and the phenylenediamine compound undergo a Schiff base reaction under the action of a catalyst to obtain the covalent organic framework material. Wherein, the tetrakis(4-formylphenyl)methane compound is tetrakis(4-formylphenyl)methane or a derivative of tetrakis(4-formylphenyl)methane, and the phenylenediamine compound is p- Phenylenediamine or phenylenediamine derivatives.

Taking tetrakis(4-formylphenyl)methane and p-phenylenediamine as an example, tetrakis(4-formylphenyl)methane and p-phenylenediamine can undergo a Schiff base reaction at room temperature under the action of a catalyst to form The chemical reaction formula of a covalent organic framework material with a network structure is as follows:

In addition, in the process of preparing covalent organic framework materials, the structure of COF can be modified according to the structures of tetrakis (4-formylphenyl) methane compounds and phenylenediamine compounds, as shown in Figure 2, and then Regulate the grid size in the COF network structure, and control the equivalent diameter of the grid in the network structure within the range of 20-60nm.

Wherein, the general structural formula of the tetrakis (4-formylphenyl) methane derivative is

其中中间碳原子连接烷烃的数量n可以为1-30，该中间碳原子连接烷烃的长度是6-36nm。

The number n of the alkane connected to the middle carbon atom can be 1-30, and the length of the alkane connected to the middle carbon atom is 6-36 nm.

从而也可以通过其中间苯环的重复单元的长度来调控形成网络结构的空间尺寸，其中中间苯环的重复单元数m可以是1-15，该中间苯环的重复单元的长度范围在5-75nm。 The general structural formula of the phenylenediamine derivative is

Therefore, the length of the repeating unit of the middle benzene ring can also be used to control the spatial size of the network structure. The number of repeating units m of the middle benzene ring can be 1-15, and the length of the repeating unit of the middle benzene ring ranges from 5 to 5 75nm.

The general formula of COF generated by the Schiff base reaction of tetrakis (4-formylphenyl) methane derivatives and phenylenediamine derivatives under the action of a catalyst is shown below,

Specifically, the catalyst used in the step S1 is bis((trifluoromethyl)sulfonyl)imide.

Step S2, using the aforementioned COF network structure as a template to prepare a red pigment into a pigment solution. Taking two common red pigments in color photoresist, Pigment Red 254 and Pigment Red 177 as examples, the covalent organic skeleton The material is placed in the pigment solution, and the nanocrystal structure of the red pigment can be formed after 120 minutes of rest. That is, the covalent organic framework material is used as a template to allow the pigment molecules to crystallize in the covalent organic framework network structure in the form of a solution to form the pigment Crystal. Among them, the molecular structural formulas of Pigment Red 254 and Pigment Red 177 are respectively

Step S3: Separate the pigment crystals from the network structure of the covalent organic framework by salt washing, that is, use a salt solution such as sodium chloride solution to wash the pigment crystals from the network structure of the covalent organic framework, and then add to the surface Active agent to obtain a pigment dispersion of a red pigment with uniform dispersion and uniform particle size.

Example 2: Using COF network structure to prepare green pigment dispersion

Using the COF network structure in Example 1 as a template, the green pigment was prepared into a pigment solution. The three common green pigments in color photoresist, Pigment Green 7, Pigment Green 36, and Pigment Green 58 were taken as examples. The covalent organic framework material is placed in the pigment solution, and the nanocrystalline structure of the green pigment can be formed after 120 minutes of standing. Its size can be controlled by the size of the grid in the COF network structure, and then the green pigment is washed by salt. The crystals are separated from the COF network structure, and then surfactants are added to obtain a highly dispersed, uniform particle size green pigment dispersion. Among them, the molecular structural formulas of Pigment Green 7, Pigment Green 36, and Pigment Green 58 are respectively

Example 3: Preparation of yellow pigment dispersion liquid using COF network structure

Using the COF network structure in Example 1 as a template, the yellow pigment was prepared into a pigment solution. Among them, three common yellow pigments in color photoresist, Pigment Yellow 138, Pigment Yellow 150, and Pigment Yellow 185 were taken as examples. The covalent organic framework material is placed in the pigment solution, and the nanocrystalline structure of the yellow pigment can be formed after standing for 120 minutes. Its size can be controlled by the size of the grid in the COF network structure, and then the yellow pigment is washed by salt. The crystals are separated from the COF network structure and surfactants are added to obtain a yellow pigment dispersion with high dispersion and uniform particle size. Among them, the molecular structural formulas of Pigment Yellow 138, Pigment Yellow 150 and Pigment Yellow 185 are respectively

Example 4: Preparation of blue pigment dispersion liquid using COF network structure

Using the COF network structure in Example 1 as a template, the blue pigment was prepared into a pigment solution. A common blue pigment in color photoresist, pigment blue B15:1-6, was used as an example. The organic framework material is placed in the pigment solution, and it can form the nanocrystalline structure of the blue pigment after 120 minutes of standing. Its size can be controlled by the size of the grid in the COF network structure, and then the blue pigment is washed by salt. The crystals are separated from the COF network structure, and a surfactant is added to obtain a highly dispersed, uniform particle size blue pigment dispersion. Among them, the molecular structure of Pigment Blue B15:1-6 is

The preparation method of the pigment dispersion of the present invention uses a covalent organic framework material with a network structure as a template, allowing the pigment molecules to crystallize in the covalent organic framework network structure in the form of a solution, so that the covalent organic framework network structure can be utilized The particle size of the pigment crystal is controlled by the mesh size of the pigment. After the pigment is fully crystallized, the pigment crystal is separated from the covalent organic framework by salt washing, and surfactants are added, so that high dispersibility and particle size can be obtained. A pigment dispersion with a uniform diameter. The pigment dispersion can be used to prepare color photoresist after post-processing. It is a high-performance pigment that can achieve high penetration and high contrast for display products, and the covalent organic skeleton material can be reused many times .

In summary, the preparation method of the pigment dispersion of the present invention uses a covalent organic framework material with a network structure as a template, allowing the pigment molecules to crystallize in the network structure of the covalent organic framework in the form of a solution, so that the covalent organic framework can be used The mesh size of the valence organic framework network structure controls the particle size of the pigment crystals. After the pigment is fully crystallized, the pigment crystals are separated from the covalent organic framework by salt washing, and surfactants are added to obtain high A pigment dispersion with a dispersibility and uniform particle size. The pigment dispersion can be used to prepare color photoresists after post-processing. It is a high-performance pigment that can achieve high penetration and high contrast in display products. Covalent organic framework materials can Repeated use many times.

As mentioned above, for those of ordinary skill in the art, various other corresponding changes and modifications can be made according to the technical solutions and technical ideas of the present invention, and all these changes and modifications shall fall within the protection scope of the claims of the present invention. .

Claims (10)

A method for preparing a pigment dispersion includes the following steps: Step S1: preparing a covalent organic framework material, the covalent organic framework material has a network structure; Step S2: Provide pigment, prepare the pigment into a pigment solution, place the covalent organic framework material in the pigment solution, that is, use the covalent organic framework material as a template, and let the pigment molecules in the form of a solution in the network structure of the covalent organic framework Medium crystallization, forming pigment crystals; Step S3: Separate the pigment crystals from the network structure of the covalent organic framework by salt washing, and add a surfactant to obtain a pigment dispersion. The method for preparing a pigment dispersion according to claim 1, wherein the method for preparing a covalent organic framework material in step S1 is to combine a tetrakis(4-formylphenyl)methane compound and a phenylenediamine compound The Schiff base reaction occurs under the action of the catalyst to obtain a covalent organic framework material. The method for preparing a pigment dispersion according to claim 2, wherein the tetrakis(4-formylphenyl)methane compound is tetrakis(4-formylphenyl)methane or tetrakis(4-formylphenyl) ) Methane derivatives, the phenylenediamine compound is p-phenylenediamine or a phenylenediamine derivative; The general structural formula of the tetrakis (4-formylphenyl) methane derivative is

Wherein, n is the number of alkane connected to the middle carbon atom, n is 1-30; The general structural formula of the phenylenediamine derivative is

Where m is the number of repeating units of the middle benzene ring, and m is 1-15. 3. The method for preparing a pigment dispersion according to claim 2, wherein the catalyst used in the step S1 is bis((trifluoromethyl)sulfonyl)imide. The method for preparing a pigment dispersion according to claim 1, wherein the pigment provided in the step S2 is a red pigment, a green pigment, a yellow pigment or a blue pigment. The method for preparing a pigment dispersion according to claim 5, wherein the pigments provided in step S2 are Pigment Red 254, Pigment Red 177, Pigment Green 7, Pigment Green 36, Pigment Green 58, Pigment Yellow 138, Pigment One or more of Yellow 150, Pigment Yellow 185 and Pigment Blue B15:1-6. The method for preparing a pigment dispersion according to claim 1, wherein the network structure of the covalent organic framework material prepared in step S1 has a grid, and the equivalent diameter of the grid is 20-60 nm. The method for preparing a pigment dispersion according to claim 1, wherein the salt lotion used in the salt washing in step S3 is sodium chloride. 8. The method for preparing a pigment dispersion according to claim 1, wherein the pigment dispersion is used to prepare a color photoresist. 9. The method for preparing a pigment dispersion according to claim 9, wherein the color photoresist is used to prepare a color photoresist on a color film substrate.

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