Method for controlling surface appearance and roughness of polyimide film
The polyimide film is prepared at high temperature through aprotic polar solvent etching process, which solves the problem of difficult control of the surface roughness of the polyimide film, improves its adhesion with other materials, and maintains mechanical properties , meet different application needs.
Patent Information
- Application Number
- CN202411320914.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-23
- Publication Date
- 2024-12-13
AI Technical Summary
The surface roughness of the polyimide film is difficult to control, affecting its bonding properties with other materials, and the stretching process may result in lower mechanical properties than the unstretched film.
Aprotic polar solvent etching process is used to prepare polyimide films at high temperatures. By controlling the temperature and etching time, controllable surface microstructure and roughness are formed to ensure the surface morphology and adhesion properties of the film.
Effectively control the surface roughness and morphology of the polyimide film, improve its adhesion with other materials, while maintaining mechanical properties, and meeting different application needs.
Smart Images
Figure CN119116397A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of polyimide film preparation, and in particular relates to a method for controlling the surface morphology and roughness of a polyimide film. Background Art
[0002] The existing film-forming process of polyimide often uses unidirectional or bidirectional stretching process to further improve its comprehensive performance, but it also makes its surface density higher and difficult to bond with other materials; it can also be completed without stretching due to usage needs, but its mechanical properties are often lower than those of stretched films. Rough surfaces are generally conducive to the bonding of materials due to the increase in surface area, so it is extremely necessary to control the orderliness and roughness of the surface morphology of the material. Effectively controlling the surface roughness and morphology of polyimide without losing its comprehensive performance has practical application value in improving the adhesion of polyimide films. Summary of the invention
[0003] In order to solve the above-mentioned technical problems, this application provides the following technical solutions:
[0004] The present invention provides a method for controlling the surface morphology and roughness of a polyimide film, comprising the following steps:
[0005] S1: adding equivalent amounts of dianhydride monomer and diamine monomer into a non-protonic polar solvent at a solid content of 20%, completing the reaction at room temperature under the protection of dry nitrogen to obtain polyamic acid;
[0006] S2: coating the polyamic acid on a carrier to form a film, and heating to 250-280° C. for thermal imidization to obtain a primary film;
[0007] S3: after removing the primary membrane from the support, etching is performed in a non-protonic polar solvent bath to obtain an etched membrane;
[0008] S4: heating the etched film to 300-400° C. in a high temperature furnace under vacuum conditions to complete the preparation of the polyimide film.
[0009] The membrane of the present invention adopts a non-protonic polar solvent etching process and then completes solvent volatilization at high temperature, and forms a membrane surface with controllable surface microstructure and roughness by controlling temperature and etching time (speed in production) to facilitate later applications.
[0010] Preferably, the dianhydride monomer is selected from pyromellitic dianhydride, and the diamine monomer is selected from diphenyl ether diamine.
[0011] Preferably, the polyimide film has a thickness of 15-55 μm.
[0012] Preferably, the surface root mean square roughness (RMS) of the polyimide film is 10-100 nm.
[0013] Preferably, in step S1, the molar ratio of the dianhydride monomer to the diamine monomer is 1:1.
[0014] Preferably, the aprotic polar solvent is selected from N,N-dimethylacetamide (DMAc) or N-methylpyrrolidone.
[0015] Preferably, in step S1, the total content of the dianhydride monomer and the diamine monomer in the solution system is 20 wt%.
[0016] Preferably, in step S1, the reaction is carried out under the protection of dry nitrogen at a temperature of 20-30°C.
[0017] Preferably, in step S3, the etching time is 10-30 minutes.
[0018] Preferably, in step S4, heating is performed under vacuum conditions (relative vacuum degree -0.01 MPa), the heating time is 1-3 hours, and the temperature is 300-350°C.
[0019] Specifically, the method for controlling the surface morphology and roughness of the polyimide film comprises the following steps:
[0020] The precursor polyamic acid required for the polyimide membrane is synthesized from commercial equivalents of dianhydride monomers and diamine monomers in a non-protonic polar solvent (see the schematic diagram of the synthesis route). Figure 1 ), the solid content is generally designed to be 20% (the weight percentage of the dianhydride monomer and the diamine monomer in the solution), and the synthesis of polyamic acid is completed under the protection of dry nitrogen; the polyamic acid with a solid content of 20% is coated on the carrier as required to form a polyamic acid film (in the actual production process, the original unidirectional or bidirectional drawing process is not affected or changed), and the primary film is obtained by thermal imidization at 250°C to 280°C; after the primary film is removed from the carrier, it passes through a non-protonic polar solvent tank (the actual etching time is controlled by the speed), and directly enters a high-temperature furnace controlled at a temperature of 300°C to 400°C to complete the volatilization of the solvent and complete the film formation of polyimide. The process is shown in Figure 2 .
[0021] Preferably, no biaxial stretching is performed during the thermal imidization process.
[0022] The technical solution of the present invention has the following advantages over the prior art:
[0023] The principle of the present invention is that during the thermal imidization process of polyamic acid film formation, different non-protonic polar solvents are used to etch the surface of polyimide, and the evaporation rate of the solvent is controlled by changing the temperature to form an ordered microstructure on the surface of the polyimide to increase its surface roughness. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 Schematic diagram of the synthesis route of polyimide;
[0025] Figure 2 This is a schematic diagram of the membrane preparation process route;
[0026] Figure 3 is the infrared spectrum of Example 1;
[0027] Figure 4 The measured image (atomic force microscope) of the surface roughness of the polyimide film in Example 1; the polyimide film is not etched, and the heat treatment is continued at 250°C to 300°C;
[0028] Figure 5 This is a measured image (atomic force microscope) of the surface roughness of the polyimide film in Example 1; the polyimide film is further heat treated to 300° C. after etching;
[0029] Figure 6 This is the scanning electron microscope image of the polyimide film that was not etched and continued to be heat treated at 250℃ to 300℃;
[0030] Figure 7 Scanning electron microscope image of the etched polyimide film that was further heat treated to 300°C. DETAILED DESCRIPTION
[0031] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.
[0032] Example 1
[0033] This embodiment provides a polyimide film with controlled surface morphology and roughness, and the steps are as follows:
[0034] S1: Equivalent ratio of pyromellitic dianhydride and diphenyl ether diamine are reacted with N,N-dimethylacetamide as solvent at 25°C under dry nitrogen protection to produce polyamic acid; the total content of dianhydride monomer and diamine monomer in the solution system is 20wt%.
[0035] S2: coating the polyamic acid described in S1 on a carrier, and heating at 150° C. to form a polyamic acid film;
[0036] S3: continuing to heat the polyamic acid film in S2 to 250° C. for thermal imidization to obtain a primary film;
[0037] S4: After the primary film is removed from the support, the primary film is etched in a tank containing an N,N-dimethylacetamide solution for 10 minutes to obtain an etched film;
[0038] S5: The etched film is heated to 300° C. in a high temperature furnace and the film is formed for 2 hours under vacuum conditions (relative vacuum degree -0.01 MPa). The thickness of the polyimide in this embodiment is 25 μm, and the surface root mean square roughness is 10-100 nm.
[0039] Figure 1 The synthesis reactions involved in the composite film are shown. Figure 2 The preparation process of the membrane is shown. Figure 3 The infrared spectrum of Example 1 is to characterize the completion of thermal imidization. Figure 4 and 5 The surface roughness is measured using an atomic force microscope. Figure 6 and 7 This is a scanning electron microscope image.
[0040] Example 2
[0041] This embodiment provides a polyimide film with controlled surface morphology and roughness, and the steps are as follows:
[0042] S1: Equivalent ratios of pyromellitic dianhydride and diphenyl ether diamine are reacted with N-pyrrolidone as solvent at 25° C. under dry nitrogen protection to produce polyamic acid; the total content of dianhydride monomer and diamine monomer in the aprotic polar solvent is 20wt%.
[0043] S2: coating the polyamic acid described in S1 on a carrier, and heating at 150° C. to form a polyamic acid film;
[0044] S3: continuing to heat the polyamic acid film in S2 to 250° C. for thermal imidization to obtain a primary film;
[0045] S4: After the primary film is removed from the support, the primary film is etched in a tank containing an N,N-dimethylacetamide solution for 10 minutes to obtain an etched film;
[0046] S5: The etched film is heated to 300° C. in a high temperature furnace and the film is formed under vacuum conditions (-0.01 MPa) for 2 hours. The thickness of the polyimide in this embodiment is 25 μm, and the surface root mean square roughness is 10-100 nm.
[0047] Figure 1 The synthesis reactions involved in the composite film are shown. Figure 2The film preparation process is shown.
[0048] Example 3
[0049] This embodiment provides a polyimide film with controlled surface morphology and roughness, and the steps are as follows:
[0050] S1: Equivalent ratio of pyromellitic dianhydride and diphenyl ether diamine are reacted in N,N-dimethylacetamide as solvent at 20°C under dry nitrogen protection to produce polyamic acid; the total content of dianhydride monomer and diamine monomer in the solution system is 20wt%.
[0051] S2: coating the polyamic acid on a carrier and heating at 100° C. to form a polyamic acid film;
[0052] S3: heating the polyamic acid film to 250° C. for thermal imidization to obtain a primary film;
[0053] S4: After the primary film is removed from the support, the primary film is etched in a tank containing an N,N-dimethylacetamide solution for 10 minutes to obtain an etched film;
[0054] S5: The etched film is heated to 300° C. in a high temperature furnace and the film is formed under vacuum conditions (-0.01 MPa) for 1 hour. The thickness of the polyimide in this embodiment is 15 μm, and the surface root mean square roughness is 10-100 nm.
[0055] Example 4
[0056] This embodiment provides a polyimide film with controlled surface morphology and roughness, and the steps are as follows:
[0057] S1: Equivalent ratio of pyromellitic dianhydride and diphenyl ether diamine are reacted in N,N-dimethylacetamide as solvent at 30°C under dry nitrogen protection to produce polyamic acid; the total content of dianhydride monomer and diamine monomer in the solution system is 20wt%.
[0058] S2: diluting the polyamic acid with a non-protonic polar solvent to a solid content of 20 wt % and then coating the polyamic acid on a carrier, and heating at 200° C. to form a polyamic acid film;
[0059] S3: heating the polyamic acid film to 280° C. for thermal imidization to obtain a primary film;
[0060] S4: After the primary film is removed from the support, it is etched in a tank containing N,N-dimethylacetamide solution for 30 minutes to obtain an etched film;
[0061] S5: The etched film is heated to 400° C. in a high temperature furnace and the film is formed under vacuum conditions (-0.01 MPa) for 3 hours. The thickness of the polyimide in this embodiment is 55 μm, and the surface root mean square roughness is 10-100 nm.
[0062] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.
Claims
1. A method for controlling the surface morphology and roughness of a polyimide film, characterized in that: The steps include: S1: adding equivalent amounts of dianhydride monomer and diamine monomer into a non-protonic polar solvent at a solid content of 20%, completing the reaction at room temperature under the protection of dry nitrogen to obtain polyamic acid; S2: coating the polyamic acid on a carrier to form a film, and heating to 250-280° C. for thermal imidization to obtain a primary film; S3: after removing the primary membrane from the support, etching is performed in a non-protonic polar solvent bath to obtain an etched membrane; S4: heating the etched film to 300-400° C. in a high temperature furnace under vacuum conditions to complete the preparation of the polyimide film.
2. The method for controlling the surface morphology and roughness of a polyimide film according to claim 1, characterized in that: The thickness of the polyimide film is 15-55 μm.
3. The method for controlling the surface morphology and roughness of a polyimide film according to claim 1, characterized in that: The surface root mean square roughness of the polyimide film is 10-100 nm.
4. The method for controlling the surface morphology and roughness of a polyimide film according to claim 1, characterized in that: In the step S1, the molar ratio of the dianhydride monomer to the diamine monomer is 1:
1.
5. The method for controlling the surface morphology and roughness of a polyimide film according to claim 1, characterized in that: The aprotic polar solvent is selected from N,N-dimethylacetamide or N-methylpyrrolidone.
6. The method for controlling the surface morphology and roughness of a polyimide film according to claim 1, characterized in that: In the step S1, the reaction temperature is 26°C.
7. The method for controlling the surface morphology and roughness of a polyimide film according to claim 1, characterized in that: In step S4, the etching time is 10-30 minutes.
8. The method for controlling the surface morphology and roughness of a polyimide film according to claim 1, characterized in that: In step S5, the heating time is 1-3 hours.
9. The method for controlling the surface morphology and roughness of a polyimide film according to claim 1, characterized in that: In step S5, the temperature is 300-350°C.