Photoresist, display substrate and display panel

Abstract

The application is suitable for the technical field of display, and specifically provides a photoresist, a display substrate and a display panel. The photoresist contains at least one pigment dispersant shown in the following formula (I): (I), wherein A includes an alkylene group or an alkenylene group; Z includes one or more of a carboxyl group, a hydroxyl group, a mercapto group, a substituted alkyl group, and a substituted or unsubstituted alkoxy group, an alkenyl group, an alkenyloxy group, an acyl group, and an ester group; the substituents in the substituted alkyl group and the alkenyl group include at least one of a carboxyl group, a hydroxyl group, and a mercapto group; and the substituents in the substituted alkoxy group, the alkenyloxy group, the acyl group, and the ester group include at least one of a carboxyl group, a hydroxyl group, a mercapto group, and an alkoxy group. The affinity of the pyrrole group of the pigment dispersant to black pigments such as carbon black is high, and the dispersibility of the Z group in a photoresist solvent is good, so that the pigment dispersant can significantly improve the dispersibility of the black pigments in the photoresist.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of display, in particular to a photoresist, a display substrate and a display panel. BACKGROUND

[0002] A thin film transistor-liquid crystal display (TFT-LCD) mainly comprises a TFT substrate and a CF (color filter) substrate arranged oppositely and a liquid crystal layer between the two substrates. The TFT-LCD controls the deflection of liquid crystal molecules by controlling the switching of a thin film transistor (TFT) through an electric signal to realize picture display. The CF substrate mainly provides three primary colors for color display of the panel, and the color resist between the three primary colors usually needs to be separated by a black matrix (BM) to prevent color bleeding.

[0003] The BM is generally obtained by a negative photoresist containing a photopolymerizable substance, an initiator, an alkali-soluble resin and a black pigment (such as carbon black) after exposure and development. In order to achieve a good light shielding effect of the BM, the addition amount of the black pigment such as carbon black is usually large, but the large use of carbon black and the like makes it easy to aggregate, which in turn leads to uneven local exposure during the exposure process and a serious edge phenomenon of the obtained BM. SUMMARY

[0004] In view of this, the present application provides a photoresist and an application thereof to solve the problem of edge of a cured pattern formed by the photoresist due to the aggregation of the black pigment in the existing photoresist.

[0005] In a first aspect, the present application provides a photoresist, comprising an alkali-soluble resin, a monomer, an oligomer, a photoinitiator, a black pigment, a pigment dispersant and a solvent, wherein the pigment dispersant comprises at least one substance represented by the following formula (I):

[0006]

[0007] wherein A comprises an alkylene group or an alkenylene group; Z comprises one or more of a carboxyl group, a hydroxyl group, a mercapto group, a substituted alkyl group, and a substituted or unsubstituted alkoxy group, alkenyl group, alkenyloxy group, acyl group, ester group, wherein the substituents in the substituted alkyl group, alkenyl group comprise at least one of a carboxyl group, a hydroxyl group, a mercapto group, and the substituents in the substituted alkoxy group, alkenyloxy group, acyl group, ester group comprise at least one of a carboxyl group, a hydroxyl group, a mercapto group, an alkoxy group.

[0008] The photoresist provided by the present application contains a pigment dispersant with a specific structure, one end of which is a pyrrole group and the other end is a Z group connected to the pyrrole group through a proper hydrocarbon chain, wherein the pyrrole group has high affinity for black pigments such as carbon black, and the Z group has good dispersibility in the photoresist solvent, which enables the pigment dispersant to form micelles with the black pigment in the photoresist system, thereby greatly improving the uniformity of the dispersion of the black pigment in the photoresist. When the photoresist is used to prepare a black matrix, the black pigment is less likely to aggregate during the exposure process of the photoresist, and the BM pattern formed has less edge phenomenon and better light shielding effect.

[0009] In a second aspect, the present application provides a display substrate, which has a solidified product of the photoresist according to the first aspect of the present application on a substrate.

[0010] In a third aspect, the present application provides a display panel, which comprises the display substrate according to the second aspect of the present application, and a counter substrate arranged opposite to the display substrate. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 An interaction schematic diagram of the pigment dispersant provided by the present application and black pigment-carbon black.

[0012] Figure 2 A structural schematic diagram of the display substrate provided by the embodiment of the present application.

[0013] Figure 3 A structural schematic diagram of the display panel provided by the embodiment of the present application.

[0014] Figure 4 A transmission electron microscope (TEM) photo of the photoresist of Example 1 (a) to which the pigment dispersant of the present application is added and the photoresist of Comparative Example 1 (b) to which the pigment dispersant of the present application is not added.

[0015] Figure 5 An optical microscope (OM) photo of the substrate (c) with a BM prepared by the photoresist of Example 1 and the substrate (d) with a BM prepared by the photoresist of Comparative Example 1.

[0016] Figure 6 A curve of the OD (optical density) value of the BM prepared by the photoresist of Example 1 and the BM prepared by the photoresist of Comparative Example 1 with respect to the thickness of the BM. DETAILED DESCRIPTION

[0017] The embodiment of the present application provides a photoresist, which comprises an alkali-soluble resin, a photo-polymerizable substance, a photo-initiator, a black pigment, a pigment dispersant and a solvent, wherein the pigment dispersant comprises at least one substance with the following structural general formula (I):

[0018]

[0019] A comprises alkylene or alkenylene; Z comprises one or more of carboxyl (-COOH), hydroxyl (-OH), mercapto (-SH), substituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted alkenyl, substituted or unsubstituted alkenyloxy, substituted or unsubstituted ester group and substituted or unsubstituted acyl group, wherein the substituents in the substituted alkyl, the substituted alkenyl comprise at least one of carboxyl, hydroxyl and mercapto, and the substituents in the substituted alkoxy, the substituted alkenyloxy, the substituted ester group and the substituted acyl group comprise at least one of carboxyl, hydroxyl, mercapto and alkoxy.

[0020] In the photoresist, one end of the pigment dispersant is a pyrrole group, and the other end is a Z group connected with the pyrrole group through a proper hydrocarbon chain A, wherein the pyrrole group has high affinity for the black pigment such as carbon black, and the Z group has good dispersibility in the solvent of the photoresist; based on the principle of similar solubility, when the pigment dispersant meets the black pigment such as carbon black, the pyrrole head group of the pigment dispersant will automatically face the black pigment, and the Z group will stretch in the solvent, that is, micelles capable of stably existing in the photoresist system are formed between the pigment dispersant and the black pigment (see Figure 1 Based on the fact that the black pigment is wrapped by the micelles, the black pigment is not prone to aggregation, and the uniformity of dispersion of the black pigment in the photoresist system is greatly improved; when the photoresist is subjected to exposure treatment, the black pigment is not prone to aggregation, and is not prone to local non-uniform exposure. However, when the photoresist is used to prepare a BM, the probability of the BM pattern formed to have a rough edge is greatly reduced, the light shielding effect of the BM is improved, and the good display quality of the display panel is ensured.

[0021] In the present application, the substituted or unsubstituted ester group can be represented as -O-C(=O)-R1or -C(=O)O-R1, wherein R1includes an alkyl group, an alkenyl group, or an alkyl or alkenyl group substituted with at least one of -COOH, -OH, -SH, or an alkoxy group. Among them, -COOH, -OH, -SH, and an alkoxy group are substituents in the substituted ester group. When R1is a substituted or unsubstituted alkyl group, the -O-C(=O)-R1or -C(=O)O-R1may be referred to as a substituted or unsubstituted alkyl ester group; when R1is a substituted or unsubstituted alkenyl group, the -O-C(=O)-R1or -C(=O)O-R1may be referred to as a substituted or unsubstituted alkenyl ester group. In some embodiments, the number of carbon atoms in the substituted or unsubstituted alkyl group can be 1-6, and further can be 1-4. The number of carbon atoms in the substituted or unsubstituted alkenyl group can be 2-6, and further can be 2-4. For example, the substituted or unsubstituted ester group can specifically include, but is not limited to, -OCOCH3, -OCOCH2CH3, -OCO-CH2CH2OH, -OCO-CH2CH2COOH, -OCO-CH2CH2OCH2CH3, -OCO-CH(CH3)CH2OCH3, -OCO-CH=CH2, -OCO-C(CH3)=CH2, -OCO-C(OH)=CH2, and the like. The ester group in the form of -C(=O)O-R1is similar to the ester group in the form of -O-C(=O)-R1described above, and will not be listed one by one here.

[0022] Among them, the substituted or unsubstituted acyl group can be represented as -C(=O)-R2, wherein R2includes an alkyl group, an alkenyl group, or an alkyl or alkenyl group substituted with at least one of -COOH, -OH, -SH, or an alkoxy group. When R2is a substituted or unsubstituted alkyl group, the -C(=O)-R2may be referred to as a substituted or unsubstituted alkyl acyl group; when R2is a substituted or unsubstituted alkenyl group, the -C(=O)-R2may be referred to as a substituted or unsubstituted alkenyl acyl group. In the present application, when the number of carbon atoms of the acyl group is mentioned, it refers to the number of carbon atoms of R2. The number of carbon atoms of the substituted or unsubstituted alkyl group and the substituted or unsubstituted alkenyl group is as described above. In some embodiments, R2is an unsubstituted alkyl or alkenyl group, which has good compatibility with ketone solvents, and it is preferable that R2be an alkyl group with a number of carbon atoms of 1-4.

[0023] wherein the substituted or unsubstituted alkoxy group can be represented by the general formula -O-R3, wherein R3 includes an unsubstituted alkyl group or a substituted alkyl group (e.g., an alkyl group substituted with at least one of -COOH, -OH, -SH, an alkoxy group). When R3 is a substituted alkyl group, -O-R3 is a substituted alkoxy group. Exemplary substituted or unsubstituted alkoxy groups can include -OCH3, -OCH2CH3, -CH(OCH2CH3)2, -OCH2CH2-OCH3, -OCH2CH2OH, -OCH2CH2OCH2CH3, and the like.

[0024] Similarly, the substituted or unsubstituted alkenyloxy group can be represented by the general formula -O-R4, wherein R4 includes an unsubstituted alkenyl group or a substituted alkenyl group (e.g., an alkenyl group substituted with at least one of -COOH, -OH, -SH, an alkoxy group). In some embodiments, R3 and R4 can include a straight chain or a branched chain, with a straight chain being preferred for better compatibility with solvents in the photoresist. In some embodiments, R3 can have a carbon atom number of 1-6, and further can have a carbon atom number of 1-4. R4 can have a carbon atom number of 2-6, and further can have a carbon atom number of 2-4.

[0025] In some embodiments, A can include an alkylene group having a carbon atom number of 1-10, or an alkenylene group having a carbon atom number of 2-10. A group of A having an appropriate length can pull the pyrrole group and the Z group apart at a proper distance, which can facilitate the formation of micelles of the pigment dispersant of formula (I) to sufficiently coat the black pigment, and avoid excessive carbon atom number from affecting the solubility of the pigment dispersant in the system. In some embodiments, A can have a carbon atom number of 2-8.

[0026] In some embodiments, the alkylene group or the alkenylene group can be a straight chain or a branched chain. In some embodiments, the alkylene group or the alkenylene group is a straight chain. A straight chain of A can facilitate both the proper distance between the pyrrole group and the Z group, and the number of pigment dispersants surrounding the black pigment, which can further improve the uniformity of the dispersion. In some embodiments, the straight chain alkylene group can be represented by -(CH2)a-, wherein a is 1-10. In some embodiments, the alkenylene group can be a straight chain alkenylene group containing at least one -CH=CH-. In some embodiments, the straight chain alkenylene group can be represented by -(CH=CH)b-, wherein b is 1-5, or -(CH2)c-CH=CH-(CH2)d-, wherein c is 0-8, d is 0-8, and c+d is 0-8. In some embodiments, the straight chain alkenylene group can be represented by -(CH2)a-CH=CH-(CH2)b-, wherein a is 1-10, and b is 1-5. a b c d

[0027] ​​​​In addition, when Z is a substituted alkyl group, the number of hydrogen atoms on the carbon atom to which Z is attached is ≤ 1. Naturally, the number of hydrogen atoms on the carbon atom to which Z is attached is 2. This is to facilitate the classification of various groups. For example, when Z is a substituted alkyl group, it can be -CH(OH)2, -C(CH3)2(OH), -CH(CH3)-CH2OH, etc. In addition, one or more of the same -COOH, -OH, -SH can be present in the substituted alkyl group, or both -COOH and -OH substituents can be present.

[0028] In some embodiments of the present application, Z includes -COOH, -OH, -SH, an alkyl group having 1 to 4 carbon atoms substituted with at least one of -COOH, -OH, -SH, an alkoxy group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, an alkenyloxy group having 2 to 4 carbon atoms, an alkyl acyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted ester group. In this case, the pigment dispersant having these Z's has good compatibility with the solvent in the photoresist (see below).

[0029] In some embodiments, the pigment dispersant is a saturated group-containing substance of formula (I). In this case, A is an alkylene group, and Z includes -COOH, -OH, -SH, the substituted alkyl group, the substituted or unsubstituted alkoxy group, the substituted or unsubstituted ester group, or the substituted or unsubstituted acyl group; wherein the substituted or unsubstituted ester group is a substituted or unsubstituted alkyl ester group, and the substituted or unsubstituted acyl group is a substituted or unsubstituted alkyl acyl group. In the exposure and curing process of the photoresist, the saturated group-containing pigment dispersant does not participate in the polymerization reaction of the unsaturated group-containing photopolymerizable substance (e.g., monomer, oligomer), etc. In some embodiments, Z can include -COOH, -OH, -SH, -CH(OH)2, -C(CH3)2(OH), -CH(CH3)-CH2OH, -OCH3, -OCH2CH3, -CH(OCH2CH3)2, -OCOCH3, -OCOCH2CH3, -OCO-CH2CH2OH, -OCO-CH2CH2COOH, -OCO-CH2CH2OCH2CH3.

[0030] In some embodiments of the present application, the pigment dispersant is a compound of formula (I) containing a saturated group. In this case, at least one of A and Z contains a carbon-carbon double bond, and when A is the alkylene group, Z includes one of the substituted or unsubstituted alkenyl group, substituted or unsubstituted alkenyloxy group, substituted or unsubstituted ester group, and substituted or unsubstituted acyl group; wherein the substituted or unsubstituted ester group is a substituted or unsubstituted alkenyl ester group, and the substituted or unsubstituted acyl group is a substituted or unsubstituted alkenyl acyl group. During the exposure and curing process of the photoresist, the pigment dispersant containing a saturated group can participate in the polymerization reaction of the photopolymerizable substance (e.g., monomer) to form a co-crosslinking product. In some embodiments, Z includes one of -CH=CH2, -CH2-CH=CH2, -O-CH=CH2, -OCO-CH=CH2, -OCO-C(CH3)=CH2, -OCO-C(OH)=CH2, and the like.

[0031] In addition, it should be noted that in some embodiments of the present application, the pigment dispersant can include the aforementioned compound of formula (I) containing a saturated group and the compound of formula (I) containing an unsaturated group.

[0032] In addition, the pyrrole group in formula (I) of the present application can also have at least one substituent selected from an alkyl group and an alkoxy group. The presence of the alkyl group and the alkoxy group has little effect on the affinity of the pyrrole group for black pigments.

[0033] In some specific embodiments, the pigment dispersant can include one or more of the following compounds of formula (i1) to formula (i12) or derivatives thereof. The derivative herein refers to a compound obtained by substituting (e.g., with an alkyl group or an alkoxy group) the pyrrole ring of the compound of formula (i1) to formula (i12).

[0034]

[0035]

[0036] It should be noted that in formula (i1) to formula (i10), each a can have different values and can be independently 1 to 10. In formula (i11) and formula (i12), each b can also have the same or different values.

[0037] In the embodiments of the present application, the solvent in the photoresist can include, but is not limited to, one or more of ester solvents, ether solvents, ketone solvents, alcohol solvents, etc. These solvents are usually polar solvents, and the Z groups described above are compatible with these solvents and do not affect the subsequent curing of the photoresist. In particular, the -COOH, -OH, -SH or the substituted group containing -COOH, -OH, -SH (such as substituted alkyl, etc.) in Z described above is more compatible with alcohol solvents, the substituted or unsubstituted alkoxy, alkenyloxy is more compatible with ether solvents, the substituted or unsubstituted acyl is more compatible with ketone solvents, and the substituted or unsubstituted ester group is more compatible with ester solvents.

[0038] Among them, for the ester solvent, propylene glycol methyl ether acetate (PGMEA), propylene glycol ethyl ether acetate, diethylene glycol ethyl ether acetate, diethylene glycol butyl ether acetate, 3-methoxybutyl acetate, 3-methoxypropyl methyl acetate, 3-ethoxypropyl methyl acetate, 3-ethoxypropyl ethyl acetate, pentyl formate, ethyl acetate, n-butyl acetate, butyl propionate, ethyl butyrate, etc. can be listed. For the ether solvent, diethylene glycol methyl ethyl ether, diethylene glycol dimethyl ether, ethylene glycol dimethyl ether, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol n-propyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, etc. can be listed. For the ketone solvent, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, 2-heptanone, etc. can be listed. For the alcohol solvent, methanol, ethanol, propanol, n-butanol, etc. can be listed.

[0039] In some embodiments of the present application, the solvent includes propylene glycol methyl ether acetate, 3-methoxybutyl acetate, diethylene glycol methyl ethyl ether and propylene glycol n-propyl ether. This solvent has high safety and good solubility for each raw material in the photoresist described above, and the coating performance of the photoresist is good. Further, the solvent includes the following mass ratio of each component: 40-60% of propylene glycol methyl ether acetate, 10-20% of 3-methoxybutyl acetate, 3-10% of diethylene glycol methyl ethyl ether and 10-30% of propylene glycol n-propyl ether.

[0040] In the embodiments of the present application, the black pigment includes carbon black. The particle size of the carbon black is 10-50 nm, and further can be 15 nm-30 nm. The carbon black with the particle size in this range is more suitable for the photoresist system described above, which can avoid the self-aggregation of the carbon black due to its too small particle size, too large specific surface area and more abundant surface charge, and can also correspondingly reduce the addition amount of the pigment dispersant used to disperse the carbon black. In addition, the carbon black with the particle size in this range can also avoid affecting the coating flatness and coating density of the photoresist, and further affecting the light shielding property of the cured product of the photoresist.

[0041] In the present application, the photopolymerizable substance can include photopolymerizable monomers and / or oligomers. When the photoresist is irradiated by light of a certain wavelength, the photopolymerizable substance can undergo a polymerization crosslinking reaction under the initiation of a photoinitiator to form a polymer, and interweave with the alkali-soluble resin, black pigment, etc., to obtain a cured product with a certain network structure. In addition, in the case where the pigment dispersant contains an unsaturated carbon-carbon double bond, the pigment dispersant can also participate in the chemical crosslinking reaction.

[0042] In some embodiments of the present application, the photoresist includes the following mass percentages of each raw material:

[0043] Alkali-soluble resin: 5%-10%;

[0044] Photopolymerizable monomer: 5%-15%;

[0045] Oligomer: 1%-3%;

[0046] Photoinitiator: 0.1%-10%;

[0047] Black pigment: 5%-40%;

[0048] Pigment dispersant: 0.1%-5%;

[0049] Solvent: 45%-80%.

[0050] The pigment dispersant provided by the embodiments of the present application has strong dispersing effect on black pigment, and a small amount of addition can greatly improve the dispersion uniformity of black pigment in the photoresist. The introduction of the pigment dispersant can hardly change the composition of other components of the photoresist system. In the cooperation of an appropriate amount of pigment dispersant, black pigment and an appropriate amount of other raw materials, the dispersion uniformity and storage stability of the overall photoresist can be ensured. When the photoresist is subsequently subjected to exposure treatment, the black pigment is not easy to aggregate, and the exposure uniformity is improved.

[0051] In some embodiments of the present application, the mass percentage of black pigment in the photoresist can be 5%-35%, and can be 6%, 8%, 10%, 15%, 20%, 25%, 30%, etc. An appropriate amount of black pigment can neither reduce the shading effect of the BM made by the photoresist, nor cause the viscosity of the photoresist to be too large and difficult to be uniformly coated due to excessive addition.

[0052] In some embodiments of the present application, the mass percentage of the pigment dispersant in the photoresist is 0.1%-2%, specifically 0.15%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.8%, 1%, 1.5%, etc. Further, the mass percentage can be 0.1%-0.2%. A lower content of the pigment dispersant can sufficiently disperse the black pigment uniformly, avoiding excessive content of the pigment dispersant to reduce the viscosity of the photoresist and affect the coating quality.

[0053] In the present application, the photopolymerization monomer can be a compound having one or more ethylenic unsaturated bonds (i.e., carbon-carbon double bonds) in the molecule. Alternatively, the photopolymerization monomer can be selected from one or more of an unsaturated carboxylic acid monomer, an unsaturated carboxylic acid ester monomer, an acrylamide, an epoxy-containing monomer, etc., but is not limited thereto. Among them, the unsaturated carboxylic acid monomer can be an acrylic acid monomer, and the unsaturated carboxylic acid ester monomer can be an acrylate monomer, specifically a monofunctional acrylate monomer, a difunctional acrylate monomer, a multifunctional acrylate monomer, etc. Among them, the epoxy-containing monomer retains the epoxy group in the crosslinked product formed after participating in the polymerization reaction, which helps to significantly improve the adhesion of the cured product of the photoresist to the substrate. The cured product of the monofunctional or difunctional acrylate monomer has high adhesion to the substrate; the multifunctional acrylate monomer has high photo-reactivity. In some embodiments of the present application, the mass percentage of the photopolymerization monomer in the photoresist can be 5.6%-12%, specifically 6%, 8%, 10%, or 11%, etc.

[0054] In the present application, the oligomer is a polymer composed of a small number of repeating units, which is an incompletely polymerized polymer and still has polymerization reactivity. In the embodiments of the present application, the oligomer can include, but is not limited to, one or more of an acrylic oligomer, an acrylate oligomer, an acrylamide oligomer, an epoxy resin oligomer, an unsaturated polyester resin oligomer, or a copolymerized oligomer thereof. The above-mentioned oligomer can rapidly crosslink and cure with the polymerizable monomer, and the presence of the oligomer is beneficial to improve the adhesion and heat resistance of the cured film of the photoresist, etc. In some embodiments of the present application, the molecular weight of the oligomer is between 100-2000 to ensure high polymerization activity and high solubility in solvents.

[0055] In the present application, for the BM-forming negative photoresist, the exposed part of the photoresist remains due to its insolubility in the developer, and the unexposed BM negative photoresist can be washed away in the developing stage due to the alkali-soluble resin therein being soluble in the developer, forming a certain photoresist pattern. In the embodiments of the present application, the alkali-soluble resin is a vinyl resin with an acidic group (carboxyl, phosphoric acid group, sulfonic acid group), preferably a vinyl resin with a carboxyl group. In some embodiments, the alkali-soluble resin can be obtained by polymerization of a vinyl monomer with more than one carboxyl group (such as an unsaturated carboxylic acid), or copolymerization thereof with other copolymerizable monomers (such as unsaturated monocarboxylic acid ester, unsaturated carboxylic anhydride).

[0056] In some specific embodiments, the alkali-soluble resin can be obtained by copolymerization of (meth) acrylic acid and (meth) acrylate. Exemplarily, the alkali-soluble resin can be obtained by reaction of a mixture with the following proportions: 13-18 wt% of methacrylic acid; 17-23 wt% of methyl methacrylate; 20-28 wt% of butyl methacrylate; 17-23 wt% of benzyl methacrylate; 1-3 wt% of hydrogen donor reagent; 7-10 wt% of thermal initiator; and 8-25 wt% of solvent. Among them, the hydrogen donor reagent can include at least one thiol substance such as dodecanethiol, 1,2-ethanedithiol, 1,6-hexanedithiol, etc.; the thermal initiator can be one or more of benzenethiol, organic peroxide initiator, azo initiator, etc.

[0057] Specifically, the mass percentage content of the alkali-soluble resin in the photoresist can be 5%, 6%, 7.5%, 8%, 9% or 10%. In some embodiments, the mass percentage content can be 8%-10%.

[0058] In the present application, the photoinitiator can generate radicals upon irradiation with light of a certain wavelength, and can initiate polymerization of monomers, oligomers, etc. by the transfer of radicals. The photoinitiator can include one or more of benzophenone, α-aminoalkylphenone, benzoin, thioxanthone, anthraquinone, triazine, oxime, but is not limited thereto. Specifically, for benzophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-acetophenone, 2,2-dibutoxyacetophenone, 1-hydroxy-cyclohexyl-phenylmethanone (184), 2-methyl-1-(4-methylthiophenyl)-2-morpholin-1-propanone (907), 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173), 2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone, etc. can be listed. For α-aminoalkylphenone, 2-benzyl-2-dimethylamino-1-(4-morpholinylphenyl)-1-butanone (369), 2-dimethylamino-2-(4-methyl)benzyl-1-[4-(4-morpholinyl)phenyl]-1-butanone (379), 2-(dimethylamino)ethylbenzoate, etc. can be listed. For benzophenone, benzophenone, methylbenzophenone, hydroxybenzophenone, 4,4-dimethylaminobenzophenone, 4-bromobenzophenone, etc. can be listed. For benzoin, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, etc. can be listed. For thioxanthone, thioxanthone, 2-chlorothioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, etc. can be listed. For anthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, etc. can be listed. For triazine, 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4-methoxynaphthyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4-ethoxynaphthyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4-ethoxycarbonylnaphthyl)-4,6-bis(trichloromethyl)-s-triazine, etc. can be listed. For oxime, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime)ethanone (CGI-242 produced by Ciba-Geigy Co., Japan), 1-[4-(phenylthio)phenyl]-2-(O-benzoyloxime)-1,2-octanedione (CGI-124 produced by Ciba-Geigy Co., Japan), etc. can be listed.

[0059] In some embodiments, the photoinitiator is present in the photoresist in an amount of 0.1% to 10% by weight, and can be 0.2%, 0.3%, 0.5%, 1%, 2%, 5%, 6%, 8%, etc. The amount of photoinitiator added can be adjusted according to the polymerization activity of the monomers and oligomers in the photoresist system, the polymerization time, etc. In some embodiments, the amount is 1% to 10% by weight, and in other embodiments, the amount is 0.1% to 0.3% by weight.

[0060] In some embodiments, the photoresist further includes an initiator dispersant in an amount of less than or equal to 0.4% by weight. The initiator dispersant is used to improve the dispersibility of the photoinitiator in the photoresist system, thereby improving the molar extinction coefficient of the photoinitiator and improving its initiation efficiency. Illustratively, the initiator dispersant includes 3,3-diphenylpropionic acid or similar substances.

[0061] In some embodiments, the photoresist can further include various additives to improve its functions, such as one or more of a leveling agent, a defoaming agent, an adhesion promoter, an antioxidant, etc. The leveling agent can reduce the surface tension of the photoresist, promoting the formation of a flat and uniform coating film. The defoaming agent can effectively reduce the probability of air bubbles in the photoresist during preparation and use, improving the quality reliability of the coating film. The adhesion promoter can improve the adhesion of the photoresist to the substrate surface. The antioxidant can improve the storage stability of the photoresist and the oxidation resistance of the photoresist cured product.

[0062] Embodiments of the present application also provide a method for preparing a photoresist, including the following steps:

[0063] The alkali-soluble resin, the photopolymerizable substance, the black pigment, the pigment dispersant, the initiator, and the solvent are mixed uniformly under no light irradiation to obtain the photoresist.

[0064] The specific structure and content of the pigment dispersant in the photoresist, as well as the specific selection and optional content range of other raw materials, are described above, and will not be repeated here. The preparation method of the photoresist is simple and controllable, and is suitable for industrial production.

[0065] In some embodiments, the preparation process of the photoresist includes:

[0066] The alkali-soluble resin, the photopolymerizable substance, the black pigment, the pigment dispersant, and a portion of the solvent are mixed and uniformly dispersed under no light irradiation to obtain a first mixture;

[0067] The photoinitiator and another portion of the solvent are mixed to obtain a second mixture;

[0068] mixing the first mixture with the second mixture to obtain the photoresist.

[0069] By using this embodiment to prepare the photoresist, the pigment dispersant can form micelles with the black pigment in advance, which can stably exist in the solvent, and then mixed with the photoinitiator, so that the dispersibility of each component in the system of the obtained photoresist is better. In addition, the first mixture does not contain the photoinitiator, so that the preparation process of the first mixture can avoid the crosslinking of the system due to improper control of the light condition, thereby reducing the storage property and processability of the photoresist.

[0070] The method for uniformly dispersing the raw materials is not limited to one or more of stirring, grinding, ultrasonic, etc. Further, when preparing the first mixture, the black pigment, the pigment dispersant and the solvent can be mixed first to obtain a black pigment dispersion, and then the alkali-soluble resin, the photopolymerizable substance, etc. are added. In this way, the black pigment and the pigment dispersant can be fully contacted and compounded. Alternatively, the solvent added in the preparation of the first mixture can account for 70%-90% of the total solvent.

[0071] When the photoresist further comprises an initiator dispersant, the initiator dispersant can be added together with the photoinitiator. When the photoresist further comprises other additives such as leveling agents, defoaming agents, adhesion promoters, antioxidants, etc., the additives can be selectively added to the first mixture, or can be added after the first mixture and the second mixture are mixed.

[0072] The application also provides a black matrix comprising a cured product of the photoresist provided in the application. That is, the black matrix is obtained by curing the photoresist.

[0073] Specifically, the application provides a method for forming a black matrix, comprising the following steps:

[0074] The photoresist provided in the application is coated on a substrate to form a film layer.

[0075] The film layer is exposed and developed to obtain a black matrix.

[0076] The coating method can include spraying, rotation, roller coating or brushing, etc. The thickness of the photoresist film layer is within the common thickness range of the black matrix pattern in liquid crystal displays. In addition, after the wet photoresist is coated on the substrate, pre-baking can be performed to reduce the solvent and reduce the flowability of the film layer. Alternatively, the pre-baking temperature can be 90-120°C.

[0077] The exposure can be performed by disposing a mask on the film layer and irradiating the film layer with light through the mask. In this way, the curing of the partial photoresist film layer (exposed region) can be achieved. The mask can be selected or customized according to the required black matrix pattern.

[0078] The light source provides light rays, usually including ultraviolet rays, to initiate the cross-linking and curing of the photoresist film layer by irradiating the common photoinitiator to generate free radicals. Generally, the light source used during exposure can include mercury lamps or UV-LEDs (ultraviolet light-emitting diodes) and the like.

[0079] The developing can be performed by using a developing solution to remove unnecessary parts and reveal the required pattern. For the negative photoresist of the present application, the unnecessary part is the photoresist film layer that is not irradiated by light, and the required pattern is the distribution area of the photoresist cured product formed by light irradiation. The developing solution used for developing is usually an alkaline solution. Specifically, solutions of inorganic bases such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, and aqueous ammonia can be used, and organic bases such as tetramethylammonium hydroxide (TMAH), trimethylamine, and triethanolamine can also be used. The developing time can be 1-10 min. In some embodiments, after developing, a post-baking treatment can be performed to reduce the standing wave effect of the exposed and unexposed regions and further cure the black matrix pattern to improve its adhesion, hardness, and the like. The post-baking treatment can be performed at a temperature of 200-250°C (for example, 220°C, 230°C) for 20-50 min (for example, 30 min).

[0080] The developing solution is alkaline to remove the unexposed soluble resin (here specifically the alkali-soluble resin). Specifically, inorganic bases such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, and aqueous ammonia, and alkaline organic amines such as diethylamine, trimethylamine, tetramethylammonium hydroxide (TMAH), and triethanolamine can be used. In addition, the developing solution can also be added with an appropriate amount of water-soluble organic solvents such as methanol and ethanol and surfactants. Preferably, after developing with the above developing solution, the unnecessary parts are removed by washing with ultrapure water, and then drying is performed.

[0081] The substrate can be the substrate of a color film substrate or the substrate of an array substrate, and the substrate of a color film substrate is more common. If it is the substrate of a color film substrate, the red, green, and blue color resistance layers can be sequentially prepared after the black matrix is prepared.

[0082] The method for forming the black matrix provided in the embodiments of the present application forms the black matrix by using the photoresist exposure and development provided in the embodiments of the present application. After adding the pigment dispersant with the specific structure, the dispersion of the black pigment-carbon black in the photoresist is good, and the aggregation is less likely to occur. Therefore, the edge of the black matrix formed by the photoresist is smooth, the edge roughness phenomenon is less likely to occur, the pattern is more regular, and the light shielding effect is better.

[0083] The embodiments of the present application further provide a display substrate, and the base of the display substrate is provided with the cured product of the photoresist provided in the embodiments of the present application. The display substrate can be a color film substrate or an array substrate. Specifically, the black matrix on the display substrate can be the cured product of the photoresist.

[0084] The embodiments of the present application further provide a display panel, which comprises the display substrate provided in the embodiments of the present application and a counter substrate arranged opposite to the display substrate.

[0085] Figure 2 The structural schematic diagram of the display substrate provided in some embodiments of the present application is shown in Figure 2 . Figure 3 The structural schematic diagram of the display panel provided in some embodiments of the present application is shown in Figure 2 . The display substrate 100 in the embodiments of the present application can specifically be a color film substrate 100.

[0086] Referring to Figure 2 , the color film substrate 100 comprises a base 10, and a black matrix 11 and an RGB color resistance 12 are arranged on one side surface of the base 10. Any two adjacent RGB color resistances 12 are spaced apart by the black matrix 11. The black matrix 11 is used for light shielding to avoid the color mixing phenomenon between the adjacent RGB color resistances 12. It should be noted that the RGB color resistance layer 12 comprises red (R) color resistance, green (G) color resistance and blue (B) color resistance with light transmission. Figure 2 and Figure 3 do not distinguish the color resistances of the RGB color resistance 12. In addition, referring to Figure 3 , the color film substrate 100 can further comprise a transparent conductive layer 13, which is located above the black matrix 11 and the RGB color resistance layer 12 and is used as the common electrode of the color film substrate 100.

[0087] Referring to Figure 3The display panel 400 provided by the embodiment of the present application comprises the color film substrate 100 and the array substrate 200 arranged opposite to the color film substrate 100. The liquid crystal layer 300 is arranged between the color film substrate 100 and the array substrate 200, and the liquid crystal layer 300 comprises a plurality of liquid crystal molecules. The array substrate 200 is a common substrate in the field of liquid crystal display, and the structure of the TFT substrate 200 is a prior art, which will not be described in detail in the present application.

[0088] The black matrix on the color film substrate is formed by the photoresist provided by the embodiment of the present application, and the edge of the black matrix rarely has the phenomenon of black pigment aggregation, the edge of the black matrix is smooth, and there is no phenomenon of burr, the light shielding effect is good, and the quality reliability of the display panel comprising the color film substrate is high.

[0089] In other embodiments of the present application, the display substrate can also be an array substrate, and the substrate of the array substrate has the cured product of the photoresist. At this time, the array substrate can be referred to as a "COA (Color Filter on Array) substrate", which is a color filter (i.e., RGB color resist) made on the array substrate.

[0090] Specifically, the substrate of the array substrate can be provided with a black matrix comprising the cured product of the photoresist. The corresponding display panel comprises an array substrate and an opposite substrate (specifically, a color film substrate without a color filter) arranged opposite to the array substrate. The structure of the array substrate and the display panel is a conventional structure in the display field, except that the material of the black matrix on the array substrate is different, and the present application will not be illustrated.

[0091] Similarly, since the black matrix on the array substrate is formed by the photoresist provided by the embodiment of the present application, the edge of the black matrix rarely has the phenomenon of black pigment aggregation, the edge of the black matrix is smooth, and there is no phenomenon of burr, the light shielding effect is good, and the quality reliability of the display panel is also high.

[0092] The technical solutions of the present application will be further described through specific embodiments.

[0093] Embodiment 1

[0094] A photoresist for forming a black matrix, the photoresist comprising the following raw materials in mass percentage:

[0095] Alkali-soluble resin (specific preparation method is described below): 8%;

[0096] Photopolymerizable monomer (specifically, methyl methacrylate and butyl methacrylate): 12%;

[0097] Oligomer (specifically, an oligomer of methyl methacrylate and methyl methacrylate, with a molecular weight of about 1000): 2%;

[0098] Photoinitiator (specifically, Irgacure 369): 2%;

[0099] Initiator dispersant (specifically, 3,3-diphenylpropionic acid): 0.3%;

[0100] Black pigment (specifically, carbon black with a particle size of 20 nm): 20%;

[0101] Pigment dispersant (its structural formula is shown in the aforementioned formula (i1), a = 2): 0.2%;

[0102] Solvent (specifically, a mixture of propylene glycol methyl ether acetate, 3-methoxybutyl acetate, diethylene glycol methyl ethyl ether, and propylene glycol n-propyl ether in a mixing ratio of 50:20:10:20): 55.5%.

[0103] The preparation process of the aforementioned alkali-soluble resin includes:

[0104] (1) Methyl methacrylate, methyl methacrylate, butyl methacrylate, benzyl methacrylate, hydrogen donor (specifically, dodecanethiol), thermal initiator-phenyl mercaptan, and the solvent used in Example 1 are mixed to obtain a mixture; the mixture includes the following raw materials in the preparation percentage: 15 wt% of methyl methacrylate; 20 wt% of methyl methacrylate; 22 wt% of butyl methacrylate; 20 wt% of benzyl methacrylate; 1 wt% of dodecanethiol; 7 wt% of phenyl mercaptan; and 15 wt% of the solvent;

[0105] (2) The aforementioned mixture is heated at a temperature of 70°C under reduced pressure to cause thermal polymerization of the system, and then the obtained reaction product is subjected to gradient elution to obtain a refined alkali-soluble resin.

[0106] The preparation process of the aforementioned pigment dispersant includes: 50 mL of deionized water is added to a 200 mL round-bottom flask, 27.83 g of pyrrole-1-propanoic acid (CAS No. 89059-06-3) and 3.2 g of methanol are added and stirred thoroughly, 1-5 mL of concentrated sulfuric acid is slowly added, and then heated to reflux at 105°C for 8 h; after the reaction is completed, saturated sodium carbonate solution is added to the obtained reaction solution, and liquid-liquid separation is performed using a separatory funnel; the upper layer solution is taken, and recrystallized using ethanol; and the obtained pure product is the aforementioned pigment dispersant.

[0107] The reaction equation involved in the process of synthesizing the pigment dispersant is as follows:

[0108]

[0109] The preparation method of the aforementioned photoresist includes:

[0110] (1) Weigh each raw material according to the above raw material ratio of photoresist. First, add the alkali-soluble resin, photopolymer monomer, oligomer, black pigment, pigment dispersant and a portion of solvent (e.g. 70%) into a completely opaque and sealed stainless steel bottle, stir thoroughly to mix evenly, and obtain the first mixture A.

[0111] Add the photoinitiator, photoinitiator dispersant, and remaining solvent to another completely opaque and sealed stainless steel bottle, and stir thoroughly to mix evenly to obtain the second mixture B;

[0112] (2) Add the above mixture A and mixture B simultaneously and completely into a completely sealed and opaque stainless steel bottle, and stir thoroughly to obtain the required photoresist.

[0113] The photoresist of Example 1 was used to prepare a black matrix (BM), specifically including the following steps:

[0114] (1) The photoresist was coated on a glass substrate and pre-baked at 100°C for 100s to form a film with a thickness of 1μm;

[0115] (2) A photomask is placed on the above photoresist film layer and exposed to it using a UV-LED light source with a wavelength of 365nm. The distance between the light source and the substrate is 250μm, and the UV irradiation energy of the light source is 40mJ / cm². 2 ;

[0116] (3) After that, the mask is removed, and the exposed photoresist film is developed at 23°C for 60s using alkaline developer, and then baked at 230°C for 30min to obtain a black matrix pattern on the glass substrate.

[0117] To strongly support the beneficial effects of the embodiments of this application, the carbon black dispersion of both the photoresist of Example 1 and the photoresist without the pigment dispersant of this application under the same conditions (referred to as the photoresist of Comparative Example 1) was observed under TEM. The results are as follows: Figure 4 As shown. Following the method described in Example 1, the photoresist of Comparative Example 1 was also prepared as a BM on the substrate. The BM morphology of Example 1 and Comparative Example 1 was observed under OM (Optical Marking), and the results are as follows. Figure 5 As shown.

[0118] from Figure 4 As can be seen from the TEM image, the photoresist of Comparative Example 1 without the pigment dispersant provided in this application ( Figure 4 In Example (a), carbon black easily aggregates to form large particles, resulting in uneven carbon black dispersion; while the photoresist of Example 1 with the pigment dispersant provided in this application added... Figure 4 In (b)), the carbon black exhibits a uniform dispersion effect with consistent particle size.

[0119] From Figure 5 the OM picture of the BM prepared from the photoresist of Example 1, it can be seen that the BM prepared from the photoresist of Example 1 has no edge effect, the edge of the BM is smooth, and the pattern of the BM is regular, which helps to improve the reliability of the liquid crystal display. Figure 5 The cross region in (c) of the OM picture of the BM prepared from the photoresist of Comparative Example 1 shows a serious edge effect, i.e., more carbon black is gathered at the edge of the BM, which affects the light shielding performance of the BM, and causes light leakage, resulting in color difference of RGB three primary colors of the display panel, and affecting the display performance of the liquid crystal display. Figure 5 The cross region in (d) of the OM picture of the BM prepared from the photoresist of Example 1 has no edge effect, the edge of the BM is smooth, and the pattern of the BM is regular, which helps to improve the reliability of the liquid crystal display.

[0120] In addition, the light shielding effect of the BM prepared from the photoresist of Example 1 and the BM prepared from the photoresist of Comparative Example 1 was measured, and the results are shown in Table 1. Figure 6 Table 1 Figure 6 The OD value of the BM prepared from the photoresist of Example 1 and the BM prepared from the photoresist of Comparative Example 1 with respect to the thickness of the BM is shown in Figure 1. The red small squares represent the data points on the OD curve of the BM of Example 1, and the blue small dots represent the data points on the OD curve of the BM of Comparative Example 1.

[0121] From the simulation formula in Table 2, it can be calculated that when the film thickness of the BM is 1 μm, the OD value of the BM prepared from the photoresist of Example 1 is 2.4029*1+1.8362=4.2391, and the OD value of the BM prepared from the photoresist of Comparative Example 1 is 2.4113*1+1.686=4.0973, and the improvement range of the OD value w=(4.2391-4.0973] / 4.0973*100=3.46%. Figure 6 Example 2

[0122] A photoresist for forming a black matrix, which is different from Example 1 in that the pigment dispersant used is pyrrole-1-propionic acid, and the structural formula is shown as formula (i2) as described above, and a=2.

[0123] TEM observation of the photoresist of Example 2 also did not find the phenomenon of carbon black gathering; the BM prepared from the photoresist has no edge effect, and the OD value of the BM with a thickness of 1 μm is about 4.32, which is about 5.36% higher than the OD value of the BM prepared from the photoresist without adding the pigment dispersant under the same conditions.

[0124] Example 3

[0125]

[0126] ​A photoresist for forming black matrix, which is different from that of Example 1 in that the structural formula of the pigment dispersant used is shown as the aforementioned formula (i3), a = 1. The CAS number of the pigment dispersant is 136927-42-9.

[0127] The photoresist of Example 3 was observed by TEM, and no carbon black aggregation phenomenon was found. The BM prepared by the photoresist had no edge phenomenon, and the OD value of the BM with a thickness of 1 μm was about 4.28, which was about 4.39% higher than the OD value of the BM prepared by the photoresist without the pigment dispersant under the same conditions.

[0128] Example 4

[0129] A photoresist for forming black matrix, which is different from that of Example 1 in that the structural formula of the pigment dispersant used is shown as the aforementioned formula (i4), a = 1. The CAS number of the pigment dispersant is 714957-06-9.

[0130] The photoresist of Example 4 was observed by TEM, and no carbon black aggregation phenomenon was found. The BM prepared by the photoresist had no edge phenomenon, and the OD value of the BM with a thickness of 1 μm was about 4.25, which was about 3.66% higher than the OD value of the BM prepared by the photoresist without the pigment dispersant under the same conditions.

[0131] Example 5

[0132] A photoresist for forming black matrix, which is different from that of Example 1 in that the structural formula of the pigment dispersant used is shown as the aforementioned formula (i8), a = 3.

[0133] The preparation process of the pigment dispersant includes: adding 50 mL of deionized water into a 200 mL round-bottom flask, then adding 15.31 g of pyrrole-1-butanoic acid (CAS number: 70686-51-0) and 4.42 g of vinyl alcohol and stirring thoroughly, slowly adding 1-5 mL of concentrated sulfuric acid, and heating to reflux at 105°C for 8 h. After the reaction is completed, saturated sodium carbonate solution is added to the obtained reaction solution, and the liquid is separated using a separatory funnel. The upper solution is taken, and recrystallization is performed using ethanol. The obtained pure product is the aforementioned pigment dispersant.

[0134] The photoresist of Example 5 was observed by TEM, and no carbon black aggregation phenomenon was found. The BM prepared by the photoresist had no edge phenomenon, and the OD value of the BM with a thickness of 1 μm was about 4.24, which was 3.21% higher than the OD value of the BM prepared by the photoresist without the pigment dispersant under the same conditions.

[0135] Example 6

[0136] A photoresist for forming a black matrix, which is different from that of Example 1 in that the structural formula of the pigment dispersant used is shown as the aforementioned formula (i9), a = 6.

[0137] The preparation process of the pigment dispersant includes: 1) preparing pyrrole-1-hexanol: 62.32 g of 3,4-dihydroxy-n-butyraldehyde (CAS: 81893-52-9) and 35.10 g of 6-amino-1-hexanol (CAS: 4048-33-3) are dissolved in a mixed solution of ethanol: pH = 7.5 phosphate buffer (v:v = 4:6) 150 mL, dehydrated at 60°C under reduced pressure by rotary evaporation to obtain an oil 88.72 g, and the oil is dissolved in pure water and eluted by column chromatography (water and acetonitrile are used as eluents, respectively). The acetonitrile eluted part is collected, concentrated to obtain pyrrole-1-hexanol 31.65 g (yield about 32%). 2) 50 mL of deionized water is added to a 200 mL round-bottom flask, then 20.5 g of pyrrole-1-hexanol and 8.61 g of methacrylic acid are added and stirred well, 1-5 mL of concentrated sulfuric acid is slowly added, and then heated to reflux at 105°C for 8 h. After the reaction is completed, saturated sodium carbonate solution is added to the obtained reaction solution, and the upper layer is separated using a separatory funnel, and recrystallized using ethanol. The obtained pure product is the above-mentioned pigment dispersant.

[0138] The reaction equation involved in the preparation of the pigment dispersant of Example 6 includes:

[0139]

[0140] The photoresist of Example 6 is also observed by TEM, and no carbon black aggregation phenomenon is found; the BM prepared by the photoresist has no edge phenomenon, and the OD value of the BM with a thickness of 1 μm is about 4.34, which is about 5.85% higher than the OD value of the BM prepared by the photoresist without adding the pigment dispersant under the same conditions.

[0141] Example 7

[0142] A photoresist for forming a black matrix, which is different from that of Example 1 in that the structural formula of the pigment dispersant used is shown as the aforementioned formula (i1), a = 4.

[0143] The preparation process of the pigment dispersant includes: adding 50 mL of deionized water into a 200 mL round-bottom flask, then adding 16.55 g of pyrrole-1-pentanoic acid (CAS No. 145511-35-9) and 2.01 g of methanol and stirring thoroughly, slowly adding 1-5 mL of concentrated sulfuric acid, and heating to reflux at 105°C for 8 h. After the reaction is completed, saturated sodium carbonate solution is added to the obtained reaction solution, and liquid separation is performed using a separatory funnel. The upper solution is taken, and recrystallization is performed using ethanol. The obtained pure product is the pigment dispersant.

[0144] The photoresist of Example 7 is observed by TEM, and no carbon black aggregation phenomenon is found. The BM prepared by the photoresist has no edge phenomenon, and the OD value of the BM with a thickness of 1 μm is about 4.33, which is about 5.61% higher than the OD value of the BM prepared by the photoresist without adding the pigment dispersant under the same conditions.

[0145] Example 8

[0146] A photoresist for forming a black matrix, which is different from Example 1 in that the structural formula of the pigment dispersant used is shown as the aforementioned formula (i10), wherein a = 6.

[0147] The preparation process of the pigment dispersant includes: 1) preparing pyrrole-1-hexanol, which is the same as in Example 6; and 2) reacting pyrrole-1-hexanol with 2-hydroxy-acrylic acid, which is similar to the reaction of pyrrole-1-hexanol with methacrylic acid in Example 6.

[0148] The photoresist of Example 8 is observed by TEM, and no carbon black aggregation phenomenon is found. The BM prepared by the photoresist has no edge phenomenon, and the OD value of the BM with a thickness of 1 μm is about 4.36, which is about 6.10% higher than the OD value of the BM prepared by the photoresist without adding the pigment dispersant under the same conditions.

[0149] Example 9

[0150] A photoresist for forming a black matrix, which is different from Example 1 in that the structural formula of the pigment dispersant used is shown as the aforementioned formula (i11), wherein b = 1.

[0151] The preparation process of the pigment dispersant includes: 1) preparation of pyrrole-1-vinyl alcohol: 62.32 g of 3,4-dihydroxy-n-butyraldehyde (CAS: 81893-52-9) and 17.72 g of 2-amino-vinyl alcohol (CAS: 1537917-09-1) are dissolved in a mixed solution of ethanol: pH = 6.5 phosphate buffer (v:v = 4:6) 150 mL, dehydrated at 60°C under reduced pressure to obtain an oil 76.36 g, dissolve the oil in pure water, and then elute by column chromatography (using water and acetonitrile as eluents, respectively), collect the acetonitrile eluted part, and concentrate to obtain pyrrole-1-vinyl alcohol 26.59 g (yield about 33%). 2) In a 200 mL round-bottom flask, add 50 mL of deionized water, then add 20.65 g of pyrrole-1-vinyl alcohol and 8.32 g of acrylic acid, and stir well, then slowly add 1-5 mL of concentrated sulfuric acid, and heat to reflux at 105°C for 8h, after the reaction is completed, add saturated sodium carbonate solution to the obtained reaction solution, and use a separatory funnel to separate, take the upper layer, and recrystallize using ethanol, and the obtained pure product is the above-mentioned pigment dispersant.

[0152] In the preparation of the pigment dispersant of Example 9, the reaction equation involved includes:

[0153]

[0154] The photoresist of Example 9 was also observed by TEM, and no carbon black aggregation phenomenon was found; the BM prepared by the photoresist had no edge phenomenon, and the OD value of the BM with a thickness of 1 μm was about 4.33, which was about 5.61% higher than the OD value of the BM prepared by the photoresist without adding the pigment dispersant under the same conditions.

[0155] Example 10

[0156] A photoresist for forming a black matrix, which is different from Example 1 in that the structural formula of the pigment dispersant used is specifically as shown in the aforementioned formula (i12), wherein b = 1.

[0157] The preparation process of the pigment dispersant includes: 62.32 g of 3,4-dihydroxy-n-butyraldehyde (CAS: 81893-52-9) and 20.70 g of 1-amino-1,3-butadiene (CAS: 120627-19-2) are dissolved in a mixed solution of ethanol: pH = 6.5 phosphate buffer (v:v = 4:6) 150 mL, dehydrated at 60°C under reduced pressure to obtain an oil 62.31 g, dissolve the oil in pure water, and then elute by column chromatography (using water and acetonitrile as eluents, respectively), collect the acetonitrile eluted part, and concentrate to obtain the product 18.09 g (yield about 22%).

[0158] The reaction equation involved in the preparation of the pigment dispersant of Example 10 includes:

[0159]

[0160] The photoresist of Example 10 was also observed by TEM, and no carbon black aggregation phenomenon was found. The BM prepared from the photoresist had no edge phenomenon, and the OD value of the BM with a thickness of 1 μm was about 4.32, which was about 5.12% higher than the OD value of the BM prepared from the photoresist without the pigment dispersant under the same conditions.

[0161] The above examples only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the scope of protection of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A photoresist comprising an alkali-soluble resin, a photopolymerizable material, a photoinitiator, a black pigment, and a solvent, characterized in that, The black pigment includes carbon black, and the photoresist further includes a pigment dispersant, the pigment dispersant comprising at least one substance with the following general structural formula (I): （Ⅰ） Wherein, A includes alkylene or alkenylene; Z is one of carboxyl, alkoxy, alkenyl, alkenyloxy, substituted or unsubstituted ester group, wherein the substituent in the substituted ester group includes at least one of carboxyl, hydroxyl, mercapto, and alkoxy; the solvent is one or more of ester solvents, ether solvents, ketone solvents, and alcohol solvents.

2. The photoresist as described in claim 1, characterized in that, The alkylene group is a straight-chain alkylene group with 1-10 carbon atoms; the alkenyl group has 2-10 carbon atoms and is a straight-chain alkenyl group containing at least one carbon-carbon double bond.

3. The photoresist as described in claim 1, characterized in that, Z is a carboxyl group, an alkoxy group with 1-4 carbon atoms, an alkenyl group with 2-4 carbon atoms, an alkenoxy group with 2-4 carbon atoms, or a substituted or unsubstituted ester group.

4. The photoresist according to any one of claims 1-3, characterized in that, The photopolymerizable material includes photopolymerizable monomers and oligomers, and the photoresist includes the following raw materials in the following mass percentages: Alkali-soluble resin: 5%-10%; Photopolymerizable monomers: 5%-15%; Oligomers: 1%-3%; Photoinitiator: 0.1%-10%; Black pigment: 5%-40%; Pigment dispersant: 0.1%-5%; Solvent: 45%-80%.

5. The photoresist as described in claim 4, characterized in that, The photoresist also includes an initiator dispersant with a mass percentage of less than or equal to 0.4%; the initiator dispersant includes 3,3-diphenylpropionic acid.

6. A display substrate, characterized in that, The substrate of the display substrate has a cured photoresist as described in any one of claims 1-5.

7. A display panel, characterized in that, It includes the display substrate as described in claim 6, and a counter substrate disposed opposite to the display substrate.

Images