A UV-blocking polyimide resin and its preparation method and application

Abstract

The present invention provides a UV-blocking polyimide resin, a preparation method, and applications thereof. By designing the polyimide molecular structure and introducing anti-UV groups into the polyimide, the cutoff wavelength red shift of the polyimide material is controlled, thereby improving the UV-blocking properties of the polyimide cover material for flexible display devices, thereby increasing the service life of the flexible display product and the stability of device performance.

Description

Technical Field

[0001] The present invention belongs to the field of polymer materials, and in particular relates to an ultraviolet-barrier polyimide resin and a preparation method and application thereof. Background Art

[0002] Display terminal products are entering a new era of transformation. Flexible screens are increasingly widely used due to their advantages, including bendability, lightness, drop resistance, fast response, and wide operating temperature range. In the future, more flexible terminal products will continue to be introduced. To achieve "softness" while maintaining excellent mechanical and optical properties, flexible transparent polyimide materials are becoming the primary choice for cover materials, replacing traditional glass.

[0003] However, with the use of organic materials such as polyimide instead of inorganic glass as cover plates, flexible displays are increasingly exposed to UV light over time, which can lead to accelerated aging of organic light-emitting materials, device performance degradation, and even failure. Therefore, UV protection or UV blocking is becoming increasingly important. Improving the UV blocking properties of polyimide cover plates can significantly extend the service life of flexible displays and the stability of device performance. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings and defects mentioned in the above background technology, provide a UV-blocking polyimide resin and its preparation method and application, and introduce anti-UV groups into the polyimide through the design of the polyimide molecular structure to increase the blocking wavelength of the polyimide material and achieve the purpose of UV resistance of the flexible display device.

[0005] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0006] The present invention provides a UV-blocking polyamic acid resin having the following general structure:

[0007]

[0008] Wherein, X is a phenolic unit;

[0009] Y, Z and Ar3 are aromatic units;

[0010] Ar1 and Ar2 are aryl units or cycloalkyl units;

[0011] R1 is an alkane group;

[0012] m and n are positive integers.

[0013] The UV-blocking polyamic acid resin provided by the present invention creatively implants a hydroxyl-containing triazine ring into the main chain of a transparent polyimide molecule. The hydroxyl groups in the molecular chain form intrinsic hydrogen bonds with the triazine ring, forming a chelate ring. After absorbing UV light energy, the molecule undergoes thermal vibration, breaking the intrinsic hydrogen bonds and opening the chelate ring, converting the UV light energy into heat and releasing it. Simultaneously, by regulating the number of hydroxyl groups on the triazine o-phenylene group, the red shift of the absorption band can be controlled. This ensures high transmittance of the transparent polyimide while achieving a controllable red shift of its cutoff wavelength to 400 nm, achieving excellent UV-blocking effectiveness.

[0014] In a preferred embodiment, in the structure of the UV-blocking polyamic acid resin, X is selected from any one of the following structures:

[0015]

[0016] In a preferred embodiment, in the structure of the UV-blocking polyamic acid resin, Y, Z, and Ar3 are each independently selected from any one of the following structures:

[0017]

[0018] In a preferred embodiment, in the structure of the UV-blocking polyamic acid resin, Ar1 and Ar2 are each independently selected from any one of the following structures:

[0019]

[0020] In a preferred embodiment, in the structure of the UV-blocking polyamic acid resin, R1 is selected from a linear alkyl group, a branched alkyl group or a cycloalkyl group.

[0021] In a preferred embodiment, in the structure of the UV-blocking polyamic acid resin, n is 10-200, and m is 1-20.

[0022] In a preferred embodiment, the UV-blocking polyamic acid resin has a solid content of 5 to 35%, preferably 10 to 20%.

[0023] In a preferred embodiment, the viscosity of the UV-blocking polyamic acid resin is 500 to 500,000 cP, preferably 10,000 to 100,000 cP.

[0024] The present invention also provides a method for preparing a UV-blocking polyamic acid resin, comprising the following steps: dissolving a triazine ring diamine A containing X, Y, Z, and R1 structures in an organic solvent; adding a dianhydride B containing an Ar1 structure; then adding a diamine C containing an Ar3 structure; and finally adding a dianhydride D containing an Ar2 structure under a protective atmosphere, and reacting to obtain the polyamic acid resin. In actual operation, the reaction is carried out under stirring.

[0025] In a preferred embodiment, the molar ratio of the triazine ring diamine A to the diamine C is 0.1-5:95-99.9; preferably 0.5-3:97-99.5.

[0026] In a preferred embodiment, the molar ratio of the dianhydride B to the dianhydride D is 0.1-5:95-99.9; preferably 0.5-3:97-99.5.

[0027] In a preferred embodiment, the ratio of the total molar amount of the triazine ring diamine A and diamine C to the total molar amount of the dianhydride B and dianhydride D is 1:0.99-1.1, preferably 1:0.995-1.05.

[0028] In a preferred embodiment, the organic solvent is one of cresol, m-cresol, N,N-dimethylformamide, N,N-dimethylacetamide or pyrrolidone, preferably pyrrolidone.

[0029] The present invention also provides an application of an ultraviolet-barrier polyimide resin, wherein the ultraviolet-barrier polyimide resin is used to prepare a polyimide flexible display cover material.

[0030] In a preferred embodiment, the preparation process of the polyimide flexible display cover material is as follows: after defoaming the polyimide resin to form a film material on a substrate, the film material is subjected to thermal imidization treatment and then subjected to laser stripping.

[0031] Further preferably, the substrate is selected from a glass substrate or a mirror steel strip.

[0032] More preferably, the film material is formed on the substrate by spin coating, blade coating, slit coating or casting.

[0033] Further preferably, the process of the thermal imidization is: first, pre-curing at 50-150° C. for 10-60 minutes under a vacuum environment, then heating to 180-350° C. at a heating rate of 3-10° C. / min under a protective atmosphere while controlling the ambient oxygen content to be less than 100 ppm, and maintaining for 30-90 minutes; finally, cooling naturally.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The present invention creatively implants a hydroxyl-containing triazine ring into the main chain of a transparent polyimide molecule. The hydroxyl groups in the molecular chain form intrinsic hydrogen bonds with the triazine ring, forming a chelate ring. After absorbing ultraviolet light energy, the molecule undergoes thermal vibration, breaking the intrinsic hydrogen bonds and opening the chelate ring, converting the ultraviolet light energy into heat and releasing it. Simultaneously, by regulating the number of hydroxyl groups on the triazine phthalate, the red shift of the absorption band is controlled. This achieves a controllable red shift of the cutoff wavelength to 400nm while maintaining the high transmittance of the transparent polyimide, achieving an excellent ultraviolet blocking effect. Application of this material in flexible display cover materials can make flexible devices UV-resistant and improve their performance and service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Implementation Case 1: Infrared spectrum of polyimide. DETAILED DESCRIPTION

[0037] To facilitate understanding of the present invention, the present invention will be described in more comprehensive and detailed form below in conjunction with the accompanying drawings and preferred embodiments. However, the protection scope of the present invention is not limited to the following specific embodiments.

[0038] Unless otherwise defined, all technical terms used hereinafter have the same meanings as those generally understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0039] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0040] Example 1:

[0041] 0.1 mol of triazine ring diamine A containing X, Y, Z, and R1 structures was dissolved in NMP solvent. Under an inert gas atmosphere, 0.1 mol of dianhydride B containing Ar1 structure was added to the solution, followed by 9.9 mol of diamine C containing Ar3 structure, and finally 9.9 mol of dianhydride D containing Ar2 structure. The mixture was stirred and reacted to obtain a polyamic acid resin with a resin viscosity of 5000 to 1000 cP.

[0042] The obtained polyimide resin was defoamed and then slit-coated on a glass substrate to form a film material, and then subjected to thermal imidization treatment. The process of the thermal imidization treatment was as follows: pre-curing at 100°C under vacuum heating for 40 minutes; then transferring to a nitrogen atmosphere oven, controlling the ambient oxygen content to less than 100 ppm, heating at a rate of 7°C / min to 280°C, and maintaining for 60 minutes; finally, naturally cooling, and finally laser stripping to obtain a polyimide that can be used for flexible display cover materials. The specific structure is shown in Table 1.

[0043] Examples 2 to 5:

[0044] The only difference from Example 1 is the structure of the triazine ring diamine A containing X, Y, Z, and R1 structures. The specific structure is shown in Table 1.

[0045] Examples 6-7:

[0046] The only difference from Example 1 is that dianhydride B, diamine C and dianhydride D are different. The specific structures are shown in Table 1.

[0047] Example 8:

[0048] The difference from Example 1 is only in the molar amounts of diamine A, dianhydride B, diamine C and dianhydride D. The specific molar amounts are shown in Table 1.

[0049] Comparative Example:

[0050] 10 mol of diamine C containing an Ar3 structure was dissolved in NMP solvent. Under an inert gas atmosphere, 0.1 mol of dianhydride B containing an Ar1 structure was added to the solution, and then 9.9 mol of dianhydride D containing an Ar2 structure was added. The mixture was stirred and reacted to obtain a polyamic acid resin with a resin viscosity of 5000 to 1000 cP. The obtained polyimide resin was defoamed and then slit-coated on a glass substrate to form a film material. After thermal imidization treatment, it was laser stripped to prepare a polyimide that can be used for flexible display cover materials. The specific structure is shown in Table 1.

[0051] The specific structures and molar amounts of the above examples and comparative examples are shown in Table 1.

[0052] The main optical properties of the nine polyimide materials prepared in the above examples and comparative examples are shown in Table 2.

[0053] Table 1: Specific structures and molar amounts of Examples 1 to 8 and Comparative Examples

[0054]

[0055]

[0056] Table 2: Main optical properties of polyimide materials of Examples 1 to 8 and Comparative Examples

[0057] Transmittance% Yellowness YI Haze Cut-off wavelength nm Example 1 88.61 2.02 1.32 355 Example 2 86.22 2.20 1.41 380 Example 3 85.12 2.63 1.55 400 Example 4 87.44 2.31 1.36 365 Example 5 89.22 1.98 1.25 350 Example 6 90.1 1.88 1.30 360 Example 7 87.42 2.68 1.28 370 Example 8 84.18 2.97 1.55 365 Comparative Example 89.58 2.04 1.56 340

Claims

1. A UV-blocking polyamic acid resin, characterized in that: A structure having the following general formula: ； Wherein, X is a phenolic unit; Y, Z and Ar3 are aromatic units; Ar1 and Ar2 are aryl units or cycloalkyl units; R1 is an alkane group; m and n are positive integers; In the structure of the UV-blocking polyamic acid resin, X is selected from any one of the following structures: ； In the structure of the UV-blocking polyamic acid resin, Y and Z are both selected from one of the following structures: ； In the structure of the UV-blocking polyamic acid resin, Ar3 is the following structure: ； In the structure of the UV-blocking polyamic acid resin, Ar1 and Ar2 are each independently selected from any one of the following structures: ； The preparation method of the ultraviolet-barrier polyamic acid resin is as follows: Dissolve a triazine ring diamine A containing X, Y, Z, and R1 structures in an organic solvent, add a dianhydride B containing an Ar1 structure, then add a diamine C containing an Ar3 structure, and finally add a dianhydride D containing an Ar2 structure under a protective gas atmosphere, and react to obtain a polyamic acid resin; The molar ratio of the triazine ring diamine A to the diamine C is 0.1-5:95-99.9; the molar ratio of the dianhydride B to the dianhydride D is 0.1-5:95-99.9; and the ratio of the total molar amount of the triazine ring diamine A and diamine C to the total molar amount of the dianhydride B and dianhydride D is 1:0.99-1.

1.

2. The ultraviolet-blocking polyamic acid resin according to claim 1, characterized in that: In the structure of the UV-blocking polyamic acid resin, R1 is selected from a linear alkyl group, a branched alkyl group or a cycloalkyl group.

3. The ultraviolet-blocking polyamic acid resin according to claim 1, characterized in that: In the structure of the UV-blocking polyamic acid resin, n is 10-200, and m is 1-20; the UV-blocking polyamic acid resin has a solid content of 5-35%; and a viscosity of 500-500,000 cP.

4. The ultraviolet-blocking polyamic acid resin according to claim 1, characterized in that: The organic solvent is one of cresol, m-cresol, N,N-dimethylformamide, N,N-dimethylacetamide or pyrrolidone.

5. The use of a UV-blocking polyamic acid resin according to any one of claims 1 to 4, characterized in that: The ultraviolet blocking polyimide resin is used to prepare a polyimide flexible display cover material.

6. The use of a UV-blocking polyamic acid resin according to claim 5, characterized in that: The preparation process of the polyimide flexible display cover material is as follows: after defoaming the polyimide resin to form a film material on the substrate, it is subjected to thermal imidization treatment and then subjected to laser stripping. The substrate is selected from a glass substrate or a mirror steel strip; Forming film on substrate by spin coating, knife coating, slot coating or casting; First, pre-curing is carried out at 50-150°C for 10-60 minutes in a vacuum environment, and then, under a protective atmosphere, the ambient oxygen content is controlled to be less than 100ppm, and the temperature is increased to 180-350°C at a heating rate of 3-10°C / min, and maintained for 30-90 minutes; finally, the temperature is naturally lowered.

Images