Halogen-containing photosensitive polyimide and application thereof

Abstract

The invention discloses halogen-containing photosensitive polyimide and application thereof, and belongs to the technical field of micro-nano processing of optical anti-counterfeiting materials. The invention provides a processing method for realizing a controllable micro-nano structure by utilizing halogen-containing photosensitive polyimide. According to the method, the controllable micro-nano structure on the surface of a halogen-containing photosensitive polyimide film is realized by adjusting ultraviolet exposure time, exposure quantity, developing time and temperature. Halogen is introduced into polyimide for modification, so that the photosensitivity and the resolution ratio are improved while the excellent performance of common photosensitive polyimide is reserved, and the micro-nano imaging requirement is met; according to the method, the grating structure with the line width characteristic size being half of the photoetching line width value is formed on the surface of the halogen-containing photosensitive polyimide film, and the limit of the resolution size of traditional equipment is broken through, so that a pattern with higher precision is obtained, and the application prospect of the method in the optical anti-counterfeiting field is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of micro-nano processing of optical anti-counterfeiting materials, and in particular relates to a halogen-containing photosensitive polyimide and application thereof. Background Art

[0002] Polyimide is a polymer material with excellent optical properties. Its application in optical anti-counterfeiting is primarily due to its high transparency, heat resistance, chemical stability, and mechanical properties. While conventional polyimide possesses these advantages, it still has some drawbacks, such as a lack of photosensitivity, the need for photoresist-assisted patterning, a complex multi-step processing process, and limited resolution. With the continuous advancement of optical anti-counterfeiting technology, the application of polyimide in this field has further expanded. For example, the introduction of photosensitive polyimide materials has enabled high-density anti-counterfeiting storage via laser inscription. However, there are also issues such as insufficient photosensitivity. At the same time, the introduction of halogens (such as fluorine, chlorine, bromine, and iodine) can enhance the material's photosensitivity and corrosion resistance.

[0003] Micro-nanofabrication is a precision machining technology capable of fabricating nanoscale or even submicron structures on material surfaces. Its advantages include high precision, high efficiency, and large surface area, which are crucial for the fineness and uniqueness of optical anti-counterfeiting patterns. Traditional photolithography processes are multi-step, costly, and difficult to overcome equipment limitations, failing to meet the requirements of high resolution and controllable structures. Furthermore, the resolution of traditional photolithography is limited by diffraction effects, making it impossible to achieve feature sizes smaller than the wavelength of light. Summary of the Invention

[0004] Based on the above-mentioned limitations on materials and equipment, the present invention provides a halogen-containing photosensitive polyimide and its application. After undergoing photolithography and development processes, the film prepared from the halogen-containing photosensitive polyimide material can form a grating structure with a line width characteristic size that is half the photolithography line width value, breaking through the resolution size limit of traditional equipment, thereby obtaining a higher-precision pattern and improving its application prospects in the field of optical anti-counterfeiting.

[0005] A halogen-containing photosensitive polyimide, the chemical structure of which is:

[0006]

[0007] Among them, the structural unit It is a substituted aromatic ring containing at least one halogen element; structural unit B is an aromatic ring containing at least two hydroxyl groups, and is connected to the photosensitive group through an alkane chain by an ether bond; n is an integer from 1 to 40; and x is 5-200.

[0008] The photosensitive groups of the above-mentioned halogen-containing photosensitive polyimide are:

[0009] .

[0010] Furthermore, the structural unit Selected from the following structural formula:

[0011] ; wherein X is selected from F, Cl, Br or I.

[0012] Furthermore, the structural unit B is selected from the following structural formula:

[0013]

[0014] .

[0015] In this invention, the introduction of halogen not only changes the electronic structure of the molecule but also enhances its luminescence efficiency at specific wavelengths, thereby improving the recognizability and security of anti-counterfeiting information. Furthermore, the halogenated imide material can produce multiple colors of fluorescence and afterglow under ultraviolet light excitation. This multi-color luminescence property provides greater complexity and security for anti-counterfeiting.

[0016] The present invention also discloses a method for preparing a halogen-containing photosensitive polyimide, which specifically comprises the following steps:

[0017] Under the protection of inert gas, pyromellitic dianhydride and a diamine monomer having a structural unit A and a substituted aromatic ring containing at least one halogen element X are added to an organic solvent and stirred in an ice-water bath at 0-5°C for 2 hours; then a photosensitive aromatic ring monomer having a structural unit B and containing at least two hydroxyl groups is added, stirred for 18 hours, and reacted for a total of 20 hours to obtain a halogen polyimide solution, wherein the molar ratio of pyromellitic dianhydride to the diamine monomer is 1:1.

[0018] The molar amount of the photosensitive group accounts for 0.1% to 40% of the total amount of all monomers.

[0019] A processing method for achieving controllable micro-nanostructures using the above-mentioned halogen-containing photosensitive polyimide comprises the following steps: coating a halogen-containing photosensitive polyimide solution on a pretreated substrate surface by casting, blade coating or spin coating, and vacuum baking to obtain a halogen-containing photosensitive polyimide film; then, transferring a pattern on the obtained halogen-containing photosensitive polyimide film by different methods: exposing the film through a mask with a target image of a grating structure by ultraviolet light, or directly exposing the film by laser direct writing to obtain an exposed halogen-containing photosensitive polyimide film; finally, immersing the exposed halogen-containing photosensitive polyimide film in a developer for development, then rinsing it with a lotion and drying it, thereby obtaining a holographic color pattern of a grating structure with a line width characteristic dimension half the photolithographic line width value on the surface of the halogen-containing photosensitive polyimide film.

[0020] Optionally, the substrate pretreatment method includes treating the substrate with a 3-aminopropyltriethoxysilane solution or cleaning the substrate with UV.

[0021] The term "UV cleaning" refers to a precision cleaning technology that uses the photosensitive oxidation effect of ultraviolet light to remove organic pollutants on the surface of materials. It is widely used in electronic manufacturing, optical devices and other fields.

[0022] Furthermore, the halogen-containing photosensitive polyimide solution is coated on a substrate and baked in a vacuum oven, a forced air oven, or a heating table at 80° C. to 120° C. for 80 to 100 minutes to remove the solvent, thereby forming a halogen-containing photosensitive polyimide film.

[0023] Furthermore, the thickness of the halogen-containing photosensitive polyimide film is 5-500 μm;

[0024] Furthermore, when ultraviolet light is exposed through a mask having a grating-shaped target image, the wavelength of the ultraviolet light is 150-450 nm, the exposure time is 3000-5000 milliseconds, and the exposure amount is 150-180 mJ / cm 2 .

[0025] Furthermore, the exposure line width in the grating structure of the target pattern in the mask or laser direct exposure is 0.1-10 μm, the line spacing is 0.1-10 μm, and the grating period is 0.1-10 μm;

[0026] Furthermore, the soaking time is 6-60s and the temperature is 50°C-80°C.

[0027] Furthermore, the developer is a polar organic solvent, and the polar organic solvent is selected from methanol, ethanol, acetonitrile, dimethyl sulfoxide (DMSO) or N,N-dimethylacetamide (DMAC), or a mixed solvent of chloroform and acetone (chloroform:acetone = 95:5, 85:15 or 75:25), or a mixed solvent of methanol and dichloromethane (methanol:dichloromethane = 1:1, 1:5 or 1:10);

[0028] Furthermore, the washing liquid used for rinsing after development is selected from polar organic solvents for development.

[0029] When the above-mentioned halogen-containing photosensitive polyimide is exposed to ultraviolet light, the photosensitive groups in the molecules undergo a photochemical reaction, resulting in cross-linking of the chain segments in the exposed area, while the unexposed area remains unreacted. This cross-linking reaction changes the chemical structure of the material, causing differences in its solubility in the developer, thereby forming the desired pattern through selective removal of the developer.

[0030] Wherein, the line width of the grating structure formed on the surface of the halogen-containing photosensitive polyimide film after exposure is 0.1-10 μm, and the height is 50-500 nm.

[0031] The halogen-containing photosensitive polyimide film after exposure is developed in a polar organic solvent. According to the time-temperature equivalence principle, the development rate constant is exponentially related to the temperature (k∝e −Ea / RTk ), the temperature and time need to be balanced to avoid over- or under-development. Short development time may retain finer line width (high resolution), but it needs to be matched with the exposure dose. Too long development time may cause line width deviation. Therefore, the development time and temperature need to be matched according to the polarity of the developer and the exposure dose.

[0032] Compared with the prior art, the present invention has the following advantages and technical effects:

[0033] The present invention provides a method for achieving controllable micro- and nanostructures using halogen-containing photosensitive polyimide. This method achieves controllable micro- and nanostructures on the surface of a halogen-containing photosensitive polyimide film by adjusting the ultraviolet exposure time, exposure dose, development time, and temperature. By introducing halogen modification into the polyimide, the present invention improves photosensitivity and resolution while retaining the excellent properties of conventional photosensitive polyimide, meeting the requirements of micro- and nanoscale patterning. Using this method, the present invention forms a grating structure with a line width characteristic dimension half the photolithographic line width on the surface of the halogen-containing photosensitive polyimide film, surpassing the resolution size limit of conventional equipment. This allows for the production of higher-precision patterns and enhances its application prospects in the field of optical anti-counterfeiting. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 This is an atomic force microscope 2D image after development during the preparation of the holographic color pattern in Example 1;

[0036] Figure 2 This is a periodic diagram after development in the process of preparing the holographic color pattern in Example 1;

[0037] Figure 3 This is an atomic force microscope 3D image after development during the preparation of the holographic color pattern in Example 1;

[0038] Figure 4 This is an atomic force microscope 2D image after exposure during the preparation of the holographic color pattern in Example 1;

[0039] Figure 5 This is a periodic diagram after exposure in the process of preparing the holographic color pattern in Example 1;

[0040] Figure 6 This is an atomic force microscope 3D image of Example 1 after exposure during the preparation of the holographic color pattern.

[0041] Figure 7 This is an atomic force microscope 2D image after development during the preparation of the holographic color pattern in Example 2;

[0042] Figure 8 This is a periodic diagram after development in the process of preparing the holographic color pattern in Example 2;

[0043] Figure 9 This is an atomic force microscope 3D image after development during the preparation of the holographic color pattern in Example 2;

[0044] Figure 10 This is an atomic force microscope 2D image after exposure during the preparation of the holographic color pattern in Example 2;

[0045] Figure 11 This is a periodic diagram after exposure in the process of preparing the holographic color pattern in Example 2;

[0046] Figure 12 This is an atomic force microscope 3D image of Example 2 after exposure during the preparation of the holographic color pattern. DETAILED DESCRIPTION

[0047] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0048] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0049] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0050] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.

[0051] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0052] In order to solve the problems of high cost, insufficient photosensitivity and limited device resolution size of existing optical anti-counterfeiting technology, the embodiments of the present invention utilize halogen-containing photosensitive polyimide materials and perform reasonable molecular design on them to prepare intrinsic halogen-containing photosensitive polyimide materials. At the same time, the performance of the polyimide material is maintained or slightly improved due to the introduction of halogen atoms; then, reasonable technical processing is performed on the surface of the obtained halogen-containing photosensitive polyimide film through exposure and development operations to obtain a holographic color pattern with a micro-nano grating structure.

[0053] Embodiments of the present invention provide a method for achieving controllable micro-nanostructures using halogen-containing photosensitive polyimide. This method achieves controllable micro-nanostructures by adjusting the UV exposure time, exposure dose, development time, and temperature on the surface of the halogen-containing photosensitive polyimide film. After undergoing photolithography and development processes, the surface of the halogen-containing photosensitive polyimide film can form a grating structure with a line width characteristic dimension half the lithographic line width. This method, provided by embodiments of the present invention, overcomes the resolution and size limitations of conventional equipment, resulting in higher-precision patterns and enhancing its application prospects in the field of optical anti-counterfeiting.

[0054] The inert gas in the embodiment of the present invention is nitrogen.

[0055] Example 1

[0056] A processing method for realizing controllable micro-nanostructure using halogen-containing photosensitive polyimide

[0057] The chemical structure of the halogen-containing photosensitive polyimide in this embodiment is as follows:

[0058] ;

[0059] The preparation method of the halogen-containing photosensitive polyimide is as follows:

[0060] Under the protection of inert gas, pyromellitic dianhydride and a diamine containing 4,4-diamino-3,3-difluorobiphenyl were added to DMF in an equimolar ratio, and the mixture was stirred in an ice-water bath at 0-5°C for 2 hours. Then, 2,2'-methylenebis(tetramethylphenol) containing a photosensitive group was added, and the mixture was stirred for 18 hours. After a total reaction time of 20 hours, a halogenated polyimide solution was obtained, in which the molar amount of the photosensitive group accounted for 0.1% of the total amount of all monomer substances.

[0061] The cover glass was placed in a UV cleaning machine for 15 minutes, and the halogen-containing photosensitive polyimide solution was applied to the UV-cleaned cover glass by spin coating. The cover glass was then transferred to a vacuum oven and baked at 80°C for 100 minutes to obtain a halogen-containing photosensitive polyimide film. The obtained halogen-containing photosensitive polyimide film was placed in close contact with the chrome surface of a UV-transmissive mask plate, fixed below the pattern of the mask plate, and placed under a UV light source with a wavelength of 365 nm for selective exposure. The exposure time was 5000 milliseconds and the exposure dose was 150 mJ / cm 2 , wherein the exposure line width in the grating structure of the target pattern of the mask plate is 2μm, the line spacing is 2μm, and the grating period is 4μm, thereby obtaining an exposed halogen-containing photosensitive polyimide film; finally, the exposed halogen-containing photosensitive polyimide film is immersed in a developer (ethanol) at 80°C for 6s for development, and then rinsed with ethanol, and the excess washing liquid is blown dry with a hot hair dryer, thereby obtaining a holographic color pattern on the surface of the halogen-containing photosensitive polyimide film with a grating size half of the size after photolithography, and the line width is 1μm and the line spacing is 2μm.

[0062] Figure 1-3 The following are the atomic force microscope 2D image, periodic diagram and atomic force microscope 3D image after development in the process of preparing the holographic color pattern in Example 1; Figure 4-6 The following are the atomic force microscope 2D image, periodic diagram and atomic force microscope 3D image of Example 1 after exposure in the process of preparing the holographic color pattern. It can be seen that: in this example, the halogen-containing photosensitive polyimide film has a regular grating structure on its surface, the film scanning range is 16μm, the pattern line width is 1μm, the grating structure spacing is 2μm, and its groove depth is 80nm.

[0063] Example 2

[0064] A processing method for realizing controllable micro-nanostructure using halogen-containing photosensitive polyimide

[0065] The chemical structure of the halogen-containing photosensitive polyimide in this embodiment is as follows:

[0066] ;

[0067] The preparation method of the halogen-containing photosensitive polyimide is as follows:

[0068] Under the protection of inert gas, pyromellitic dianhydride and a diamine containing 4,4-dichloro-2,2'-diaminodiphenylmethane were added to DMF in an equimolar ratio, and the mixture was stirred in an ice-water bath at 0-5°C for 2 hours. Then, 2-isopropylhydroquinone containing a photosensitive group was added, and the mixture was stirred for 18 hours. After a total reaction time of 20 hours, a halogenated polyimide solution was obtained, in which the molar amount of the photosensitive group accounted for 0.1% of the total amount of all monomer substances.

[0069] The cover glass soaked in the 3-aminopropyltriethoxysilane solution (2 wt.%) was removed and blown dry, and the halogen-containing photosensitive polyimide solution was applied to the treated cover glass by spin coating. The cover glass was then transferred to a hot plate and baked at 120°C for 80 minutes to obtain a halogen-containing photosensitive polyimide film. The obtained halogen-containing photosensitive polyimide film was placed in close contact with the chrome surface of a UV-transmissive mask, fixed below the pattern of the mask, and selectively exposed to a UV light source with a wavelength of 405 nm for 3000 milliseconds and an exposure dose of 180 mJ / cm 2 , wherein the exposure line width in the grating structure of the target pattern in the mask plate is 2μm, the line spacing is 3μm, and the grating period is 5μm, thereby obtaining an exposed halogen-containing photosensitive polyimide film; finally, the exposed halogen-containing photosensitive polyimide film is immersed in a developer (a mixed solvent of methanol and dichloromethane in an equal volume ratio) at 50°C for 60s for development, and then rinsed with a mixed solvent of methanol and dichloromethane in an equal volume ratio, and the excess washing solution is blown dry with a hot hair dryer, thereby obtaining a holographic color pattern on the surface of the halogen-containing photosensitive polyimide film with a grating size half of the size after photolithography, a line width of 1μm, and a line spacing of 3μm.

[0070] Figure 7-9 The following are the atomic force microscope 2D image, periodic diagram and atomic force microscope 3D image after development in the process of preparing the holographic color pattern in Example 2; Figure 10-12 The following are, in order, the atomic force microscopy (AFM) 2D image, periodogram, and AFM 3D image of the holographic color pattern after exposure in Example 2. A regular grating structure can be observed on the surface of the halogen-containing photosensitive polyimide film. The film scanning range is 16 μm, the pattern line width is 1 μm, the grating structure pitch is 3 μm, and the groove depth is 79 nm.

[0071] The above are only preferred specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A halogen-containing photosensitive polyimide, characterized in that: The chemical structural formula is: ； Among them, the structural unit is a substituted aromatic ring containing at least one halogen element X; structural unit B is an aromatic ring substituted with at least two hydroxyl groups; n is an integer from 1 to 40; and x is 5-200.

2. The halogen-containing photosensitive polyimide according to claim 1, characterized in that: The structural unit Selected from the following structural formula: ， wherein X is selected from F, Cl, Br or I.

3. The halogen-containing photosensitive polyimide according to claim 1, characterized in that: The structural unit B is selected from the following structural formula: 。 4. A method for realizing controllable micro-nanostructure processing using the halogen-containing photosensitive polyimide according to any one of claims 1 to 3, characterized in that: The following steps are involved: coating a halogen-containing photosensitive polyimide solution on the surface of a pretreated substrate, and baking the solution to obtain a halogen-containing photosensitive polyimide film; The halogen-containing photosensitive polyimide film is sequentially exposed, developed, washed and dried to obtain a holographic color pattern on the surface of the halogen-containing photosensitive polyimide film.

5. The processing method according to claim 4, characterized in that: The baking temperature is 80° C.-120° C., and the baking time is 80-100 minutes.

6. The processing method according to claim 4, characterized in that: The exposure is performed by transmitting ultraviolet light through a mask having a target image of a grating structure, or by direct exposure using laser direct writing.

7. The processing method according to claim 6, characterized in that: When UV light is exposed through a mask with a grating-shaped target image, the wavelength of the UV light is 150-450 nm, the exposure time is 3000-5000 milliseconds, and the exposure amount is 150-180 mJ / cm 2 .

8. The processing method according to claim 6, characterized in that: The exposure line width in the grating structure of the target pattern in the mask or laser direct exposure is 0.1-10 μm, the line spacing is 0.1-10 μm, and the grating period is 0.1-10 μm.

9. The processing method according to claim 4, characterized in that: The development operation is as follows: the exposed halogen-containing photosensitive polyimide film is immersed in a developer for development.

10. The processing method according to claim 9, characterized in that: The soaking time is 6-60s, and the temperature is 50°C-80°C.

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