A microporous fluoropolyimide film material and a method for preparing the same

Abstract

The present application relates to the field of polyimide material, in particular to a kind of microporous fluorine-containing polyimide film material and preparation method thereof.The present application is based on years of research and accumulation of polyimide material structure and performance, combined with the characteristics of fluorine-containing polyimide, the chemical activity and physical properties of a variety of intended compounds are analyzed, and on the basis of a large number of experiments, it is found that C2-C 60 Alkanoate alkyl alcohol and poly (dimethylsiloxane) monohydroxy-terminated compound are the most excellent for the gradual pore-forming effect of fluorine-containing polyimide film with chemical reaction.The present application uses special grafting group to gradually form pores with chemical reaction, not only solves the problem of comprehensive performance degradation caused by other pore-forming methods, but also this pore-forming mechanism can use traditional polyimide film production equipment and process to realize, the maturity of film preparation technology is higher, the production cost is lower, the preparation process is more continuous and efficient, and the continuous production of porous polyimide film is easier to realize.

Description

Technical Field

[0001] This invention relates to the field of polyimide materials, specifically a microporous fluorinated polyimide film material and its preparation method. Background Technology

[0002] Polyimide film is an insulating material used in integrated circuits. As an insulating material in integrated circuits, its mechanical properties, thermal stability, dielectric properties, and moisture absorption properties directly determine the electronic signal transmission efficiency and device lifespan. Polyimide materials differ from other polymers in terms of heat resistance due to the presence of phthalimide rings in their molecular chains. Furthermore, different polyimide structures exhibit significant differences in various properties. Commonly structured polyimides have been extensively studied, and it has become a consensus in polyimide material research that introducing special groups into the molecular structure of common polyimides can improve certain properties.

[0003] Fluorine, the smallest atom besides hydrogen, has always appeared in a very mysterious way. As a highly reactive element, fluorine plays a significant role in many fields such as medicine and refrigeration; for example, polymers represented by polytetrafluoroethylene (PTFE) have become very important materials in the field of industrial technology. As early as the 1960s, fluorine was introduced into the structure of polyimide to obtain fluorinated polyimide materials. The main chain of fluorinated polyimide materials is a fluorine-containing structure, in which hydrogen on aromatic rings, heterocyclic rings, or aliphatic chains is replaced by fluorine or fluoroalkyl groups. Fluorinated polyimides are classified into the following categories according to the structure of the fluorine substituents and their substitution positions in the polymer: a) polyimides with perfluorinated aliphatic chains as the main chain; b) polyimides containing trifluoromethyl and hexafluoropropyl groups; c) polyimides with hydrogen on aromatic rings replaced by fluorine; d) polyimides containing fluorinated aliphatic side chains; e) perfluorinated polyimides.

[0004] Fluorine is the most electronegative element of all, and the CF bond it forms has a high energy that is difficult to break. This manifests in materials as improved thermal stability, lighter color, and better light transmittance of fluorinated polyimides. In addition, fluorinated polyimides have lower dielectric constants, lower water absorption, and higher solubility. In particular, low dielectric constants and low water absorption are the most important performance indicators for insulating materials in chip electronic products, in addition to good heat resistance. Lower dielectric constants can ensure faster signal transmission, and low water absorption ensures better environmental adaptability for electronic products. The light transmittance of fluorinated polyimide films will have a greater competitive advantage in photovoltaic power generation and flexible displays.

[0005] With the accelerating pace of informatization, the integration of electronic products is becoming increasingly sophisticated. Even materials like fluorinated polyimide cannot meet the dielectric properties required for high-speed, high-frequency signal transmission. Air has the lowest dielectric constant in nature, around 1.0. Forming tiny micropores within a polyimide film creates a two-phase system of polyimide and air, significantly reducing the material's dielectric constant and dielectric loss. Among various polyimide structures, dense fluorinated polyimide films have already been applied in integrated circuits, improving the transmission speed and stability of electronic signals. If microporous structures can be formed within fluorinated polyimide films, the dielectric constant and dielectric loss will be further reduced, greatly enhancing high-speed, high-frequency electronic signal transmission. Fluorinated polyimide films will become the most dielectrically efficient and heat-resistant material. Guided by this idea of ​​reducing the dielectric constant through internal pore formation, the preparation of fluorinated polyimide films with microporous structures has become a research hotspot in recent years.

[0006] Due to the unique structure and properties of polyimide, it is difficult to form natural micropores within the film. Most methods involve external processes to induce or artificially create pores, often at the cost of sacrificing some of the intrinsic properties of polyimide to achieve the microporous structure. Published methods include etching, phase inversion induced (PII), and electrospinning. Some of these methods, such as etching and PII, cause irreversible degradation of the film through external processes. Etching requires the use of strong acid after film formation to remove inorganic substances doped within the film. This process cannot guarantee the absence of internal residues and can affect the film's mechanical properties. PII, on the other hand, involves introducing a poor solvent during the semi-dry film stage to promote phase separation from the outside. The channels through which the original solvent leach out form pores. The inability of the poor solvent to penetrate the interior of the semi-dry film inevitably leads to differences in phase separation between the inside and outside of the film, as evidenced by the fact that pores are mostly formed on the outer side of the film and exhibit poor uniformity. Furthermore, the short-term acceleration of phase separation by the added solvent can also affect the regularity of the molecular structure, thus impacting mechanical properties. Electrospinning is a common method for creating through-holes on both sides of a thin film. It generates polyamic acid filaments through electrostatic interaction, which are then stacked to form a porous film. However, this method results in relatively large pores and poor mechanical properties. While these methods each have their own drawbacks, the biggest problem is that they are difficult to scale up due to the numerous steps involved or the discontinuous film-forming process.

[0007] It is evident that the pore size and pore distribution of porous polyimide films prepared by existing technologies cannot be effectively controlled. Some processes can lead to film degradation, resulting in poor mechanical properties. The involvement of multiple processes leads to low production efficiency and makes it difficult to achieve large-scale production. This results in inherent technical difficulties in forming tiny pores inside fluorinated polyimide films.

[0008] In addition to the numerous superior properties brought by the introduction of fluorine structures into polyimides, certain problems also exist. First, the formation of uniform intrinsic micropores within the polyimide film requires significant phase separation during the imidization stage of the film preparation process. At this stage, the cyclization reaction releases compounds that remain within the system. When the temperature rises to the point where these compounds volatilize, the resulting voids form the microporous structure. However, the introduction of fluorine structures improves the solubility of polyimides, which in turn hinders phase separation. Second, because fluorine has a very strong electron-withdrawing effect, it reduces the reactivity of adjacent functional groups, which is detrimental to polymer chain growth. If other chemical structures are grafted onto the monomer before polymerization, the reactivity of the polymerizable functional groups on the fluorinated monomer will be further reduced, significantly impacting mechanical properties. Summary of the Invention

[0009] In view of this, the technical problem to be solved by the present invention is to provide a microporous fluorinated polyimide film material and its preparation method. The preparation method provided by the present invention can obtain a microporous fluorinated polyimide film material with uniform pore size and porosity, and has high mechanical properties and heat resistance.

[0010] This invention provides a microporous fluorinated polyimide film material, which is obtained by reacting a fluorinated polyamide ester having the structure of Formula I with a polyimide.

[0011]

[0012] Wherein, z≥1000;

[0013] Ar1 and Ar2 are independently selected from substituted or unsubstituted fluorinated aromatic groups, substituted or unsubstituted fluorinated heteroaromatic groups, substituted or unsubstituted fluorinated aliphatic groups, substituted or unsubstituted aromatic groups, substituted or unsubstituted heteroaromatic groups, and substituted or unsubstituted aliphatic groups.

[0014] M1 and M2 are independently selected from C2 to C3. 60 Alkyl ester or poly(dimethylsiloxane) group, and M1 and M2 may be the same or different;

[0015] The structural units of the fluorinated polyamide ester include at least one fluorinated structural unit among Ar1 and Ar2, and both Ar1 and Ar2 are fluorine-free structural units.

[0016] The fluorinated polyamide ester of the present invention has structural units having M1 and M2 side chain groups, wherein M1 and M2 are independently selected from C2 to C3. 60 Alkyl ester or poly(dimethylsiloxane) group, and M1 and M2 may be the same or different; wherein, C2 to C 60 Alkyl esters are preferably C4-C5.15 The alkyl group is an alkyl ester, which can be a straight-chain group or a branched-chain group. Preferably, M1 and M2 are independently selected from C2 to C2 of the structure of formula Ia. 60 Alkyl ester or poly(dimethylsiloxane) group having the structure of formula Ib;

[0017]

[0018] Wherein, n≥1, m≥1

[0019] The x≥1 is preferably 5 to 15;

[0020] R represents an adipose chain.

[0021] The fluorinated polyamide ester having Formula I structure of the present invention has a poly(dimethylsiloxane) group, that is, the structural unit of the fluorinated polyamide ester includes M1 and M2, both of which are selected from C2 to C3. 60 The alkyl alkyl group of the alkyl group and at least one of the structural units selected from poly(dimethylsiloxane) group in M1 and M2. The molar amount of the poly(dimethylsiloxane) group is 5% to 30% of the total molar amount of M1 and M2, preferably 9% to 13%. This invention selects C2 to C2... 60 Alkyl esters and poly(dimethylsiloxane) groups are used as grafting groups. After these groups are removed, they act as poor solvents in the system, effectively promoting phase separation. Furthermore, the suitable boiling points ultimately lead to the formation of uniform intrinsic micropores within the microporous fluorinated polyimide film. Additionally, the distribution ratio of pore-forming groups on the polymer intermediate molecular chain can effectively control the pore size, distribution, and porosity.

[0022] The microporous fluorinated polyimide film material of this invention includes fluorinated aliphatic polyimide materials and fluorinated aromatic polyimide materials, as well as their copolymers and block and graft copolymers. Specifically, the Ar1 and Ar2 in the fluorinated polyamide ester of this invention are independently selected from substituted or unsubstituted fluorinated aromatic groups, substituted or unsubstituted fluorinated heteroaromatic groups, substituted or unsubstituted fluorinated aliphatic groups, substituted or unsubstituted aromatic groups, substituted or unsubstituted heteroaromatic groups, and substituted or unsubstituted aliphatic groups. The structural units of the fluorinated polyamide ester of this invention include at least one fluorinated structural unit among Ar1 and Ar2, and structural units in which both Ar1 and Ar2 are fluorine-free. The molar percentage of at least one fluorinated structural unit among Ar1 and Ar2 in all structural units is preferably 1% to 100%. By controlling the proportion of fluorinated units, the comprehensive properties of the porous polyimide film skeleton, such as heat resistance, water absorption, dielectric properties, and mechanical properties, can be systematically controlled.

[0023] To improve the temperature resistance of the obtained microporous fluorinated polyimide film material, the main chain of the fluorinated polyamide ester preferably has an aromatic structure. Preferably, the Ar1 has one or more of the structures of formula Ar1-a to Ar1-i.

[0024]

[0025] The Ar2 has one or more of the structures of Ar2-a to Ar2-h;

[0026]

[0027] Wherein, R1 and R2 are independently selected from H, F or trifluoromethyl;

[0028] The R 1 and R 2 The group is independently selected from the groups shown in Formulas 1 to 9;

[0029]

[0030] X is selected from hydrogen, alkyl, cycloalkyl, aryl, fluoroalkyl, hydroxyl, alkoxy, phenoxy, cyano, nitro, amino, acetamino, ester, acyl, halogen or carboxyl, preferably selected from -H, -Br, -Cl, -F, -NO2, -CN, -H, -CH3, -CH2CH3, -CH2CH2CH3, isopropyl, isobutyl, tert-butyl, cyclopentyl, cyclohexyl, phenyl or naphthyl.

[0031] The y is an integer from 1 to 4.

[0032] Of the above formulas Ar1-a to Ar1-i, the structure shown in formula Ar1-a is preferably... The structure shown in formula Ar1-b is preferably... The structure shown in formula Ar1-c is preferably... or The structure shown in formula Ar1-d is preferably... The structure shown in formula Ar1-e is preferably... The structure shown in formula Ar1-f is preferably... The structure shown in formula Ar1-g is preferably... The R 1 As mentioned above, I will not repeat myself.

[0033] The microporous fluorinated polyimide film material provided by this invention has a structure of formula II;

[0034]

[0035] Ar1, Ar2, and z are the same as those described in Equation I above, and will not be repeated here.

[0036] This invention also provides a method for preparing the microporous fluorinated polyimide film material described in any of the above technical solutions, comprising the following steps: subjecting a fluorinated polyamide ester to an imidization reaction to obtain the microporous fluorinated polyimide film material. The fluorinated polyamide ester described in this invention is the same as described above and will not be repeated. The reaction formula for the method of preparing the microporous fluorinated polyimide film material provided by this invention is as follows:

[0037]

[0038] The imidization reaction temperature described in this invention is 50℃~400℃, preferably 80℃~350℃, and the imidization reaction time is 0.3h~30h. This invention achieves imidization of fluorinated polyamide esters and microporousization of the resulting fluorinated polyimide film through heat treatment within the above temperature range. The degree of imidization of the resulting intrinsically microporous polyimide film material is typically above 90%, most preferably 100%. This invention uses industry-known thermal imidization to prepare microporous fluorinated polyimide film materials. The film preparation process is continuous and efficient, requiring no other steps and avoiding degradation of the film. The continuous film preparation process significantly reduces costs and enables large-scale production of microporous fluorinated polyimide film materials.

[0039] Specifically, this invention sequentially processes a fluorinated polyamide ester adhesive into a pre-curing stage, an imidization stage, and a high-temperature treatment stage to obtain a microporous fluorinated polyimide film material. This invention employs a step-by-step heating method for the fluorinated polyamide ester, which is more conducive to preparing films with excellent overall performance. The pre-curing stage, also known as the solvent evaporation stage, has a temperature of 50℃ to 150℃, preferably 80℃ to 120℃, and a treatment time of 0.1h to 10.0h. This invention first processes the fluorinated polyamide ester into the pre-curing stage, which evaporates the solvent of the fluorinated polyamide ester to obtain the film material. The obtained film material is a semi-dry film, still containing residual solvent, preferably with a residual solvent mass fraction of 20% to 50% of the total mass of the semi-dry film. The imidization stage treatment described in this invention is also known as the cyclization branching removal stage treatment. The temperature of the imidization stage treatment is 100℃~250℃, preferably 120℃~180℃, and the treatment time is 0.1h~10.0h. The high-temperature treatment stage treatment described in this invention is also known as the pore formation stage treatment. The temperature of the high-temperature treatment stage treatment is 180℃~400℃, preferably 180℃~350℃, and the treatment time is 0.1h~10.0h. The chemical and physical changes in the above three stages overlap; for clarity, they are named according to the main physicochemical changes of that stage. In addition to the above-mentioned segmented heating method, a gradient heating method can also be used for imidization, with a preferred heating rate of 0.1℃ / min~5℃ / min.

[0040] In some embodiments of the present invention, a fluorinated polyamide ester adhesive is coated onto a carrier plate, and then subjected to a pre-curing stage, an imidization stage, and a high-temperature treatment stage to obtain a microporous fluorinated polyimide film material. The fluorinated polyamide ester adhesive can be coated onto the carrier plate using adhesive coating equipment well-known in the art, and the coating method can be slit coating, baffle coating, spin coating, spray coating, or cast coating; the carrier plate can be a continuous steel strip, polyester film, copper foil, aluminum foil, glass, or mirror steel plate.

[0041] In other embodiments of the present invention, a fluorinated polyamide ester adhesive is coated onto a carrier plate, and after a pre-baking curing process and curing of the adhesive film into a semi-dry film, the semi-dry film is peeled off from the carrier plate and supported by a hollow frame. For example, the edge of the film is fixed by the needle plate, chain clamp, or other equipment used in the production of existing polyimide films, and the film is supported and placed in a high-temperature environment to achieve imidization. This process enables volatiles to escape to both sides of the film, avoiding the situation where the pores on both sides are uneven due to the evaporation of solvent on one side.

[0042] The above-mentioned film preparation process is compatible with the conventional polyimide film production process. It does not require the addition of new processes and equipment on the basis of conventional polyimide film production processes and equipment. The film preparation process is efficient and low-cost, which is conducive to the rapid realization of large-scale industrial production of microporous fluorinated polyimide film materials.

[0043] Preferably, the preparation method of the microporous fluorinated polyimide film material provided by the present invention includes the following steps:

[0044] S1) A dianhydride having the structure of formula a and a diamine having the structure of formula b are reacted to obtain polyamic acid;

[0045] H2N-Ar2-NH2 (Formula b);

[0046] S2) The monohydroxy compound and the polyamic acid obtained in step S1) are reacted to obtain a fluorinated polyamide ester; the monohydroxy compound is selected from C2 to C3. 60 Alkyl esters, alkyl alcohols, and monohydroxy-terminated poly(dimethylsiloxane) having the structure of formula C;

[0047]

[0048] S3) The fluorinated polyamide ester obtained in step S2) is subjected to an imidization reaction to obtain a microporous fluorinated polyimide film material.

[0049] The reaction formula for the preparation method of the above-mentioned microporous fluorinated polyimide thin film material is as follows:

[0050]

[0051] Specifically, this invention first involves a condensation reaction of a dianhydride having the structure of formula a and a diamine having the structure of formula b in a solvent to obtain polyamic acid. The condensation reaction temperature is -5℃ to 50℃, preferably 0℃ to 25℃, and the reaction time is 15h to 17h, preferably 16h. The solvents used in this invention include, but are not limited to, N,N′-dimethylformamide (DMF), N,N′-dimethylacetamide (DMAc), N-methylpyrrolidone, dimethyl sulfoxide (DMSO), and tetrahydrofuran / methanol mixtures (THF / MeOH).

[0052] After obtaining polyamic acid, this invention reacts a monohydroxy compound with the polyamic acid obtained in step S1) under a catalyst to obtain a fluorinated polyamide ester; the monohydroxy compound is selected from C2 to C3. 60 Alkyl esters, alkyl alcohols, and monohydroxy-terminated poly(dimethylsiloxanes) having the C2-C3 structure. The monohydroxy compounds described in this invention are selected from two types, one of which is C2-C3. 60 Alkyl esters, including C2-C6 alkyl alcohols60 aliphatic straight-chain alkyl esters and C2-C 60 fatty branched alkyl esters, preferably C4-C5 alkyl alcohols. 15 Alkyl esters, preferably C2-C2 alcohols having the structure of formula Ia. 60 Alkyl esters; In some embodiments of the present invention, C2 to C 60 The alkyl alcohol ester is selected from at least one of methyl 6-hydroxyhexanoate, methyl 8-hydroxyoctanoate, or ethyl 6-hydroxyhexanoate. Another is a monohydroxy-terminated poly(dimethylsiloxane) having the structure of formula c, where R and x in formula c are the same as R and x in the aforementioned formula Ib, and will not be repeated here; the reaction temperature is -10℃ to 30℃, preferably -5℃ to 15℃. The catalyst of the present invention includes, but is not limited to, at least one of the following compounds: trimethylamine, triethylamine, tripropylamine, tributylamine, N,N'-dimethylalkylamine, pyridine, alkylpyridine, or benzylpyridine.

[0053] In step S2) of this invention, the monohydroxy-terminated poly(dimethylsiloxane) accounts for 5% to 30% of the total amount of the monohydroxy compound, preferably 12% to 18%. The grafting rate of the polymer intermediate with alkyl alkanoates and poly(dimethylsiloxane) groups on the molecular chain synthesized by this invention is 1% to 100%, most preferably 80% to 100%. The percentage of poly(dimethylsiloxane) groups in the amount of branched chain material is 5% to 30%, preferably 9% to 13%. This invention synthesizes polymer intermediates with alkyl alkanoates and poly(dimethylsiloxane) groups on the molecular chain using a chemical reaction process known in the industry.

[0054] After obtaining the fluorinated polyamide ester in step S2), the fluorinated polyamide ester obtained in step S2) is subjected to an imidization reaction to obtain a microporous fluorinated polyimide film material. The imidization reaction of the fluorinated polyamide ester obtained in step S2) is the same as described above and will not be repeated here.

[0055] The preparation method provided by this invention yields a microporous polyimide film material. By optimizing the chemical reaction sequence, a polyamic acid solution is first generated by reacting dianhydride with diamine. Then, alkyl alcohols and monohydroxy-terminated poly(dimethylsiloxane) are added to the polyamic acid solution and react with carboxyl groups under the action of a catalyst, uniformly distributing them onto the polymer molecular backbone in the form of chemical bonds. This yields a polymer intermediate for a porous fluorinated polyimide film. On the one hand, these compounds can effectively promote phase separation within the system during the amidation stage of film formation, forming a pore structure of uniform size and distribution, thus solving the problem that fluorinated polyimides are difficult to form intrinsic micropores. On the other hand, it can avoid the problems of lower activity and lower degree of polymerization caused by monomers with large-volume side groups. The final film-forming process yields a porous fluorinated polyimide film with excellent mechanical properties. The chemical reaction-induced pore formation method is more conducive to the formation of intrinsic pores of uniform size and distribution within the film, and also effectively avoids the deterioration effect of some physical processes on the film. The resulting film has excellent heat resistance and dielectric properties, and also has a lower water absorption rate and excellent chemical stability, showing broad application prospects in aerospace, integrated circuits and new energy fields.

[0056] In the preparation of porous polyimide films, the optimal pore-forming method is the natural generation of pores during the chemical reaction. This method does not affect the molecular chain regularity of the polymer and does not damage the macroscopic or microscopic structure of the material. The pores gradually form during the chemical reaction, and their size and structure better match the material's properties. Furthermore, the pore structure can be specifically adjusted by regulating the proportion of the pore-forming material. Although this pore-forming method has many advantages, implementing it even in ordinary polymer materials presents significant challenges, and the difficulty is even more pronounced in polyimide, a material with high rigidity and high temperature resistance. To address this technical problem, this invention provides a microporous fluorinated polyimide film material and its preparation method. Based on years of research on the structure and properties of polyimide materials, and combined with the inherent characteristics of fluorinated polyimide, the chemical activity and physical properties of various target compounds were investigated and analyzed. Based on extensive experiments, C2~C 60 Alkyl alcohols and poly(dimethylsiloxane) monohydroxy end-capping compounds exhibit the best effect on the gradual pore formation of microporous fluorinated polyimide films through chemical reactions. This invention employs special grafted groups for gradual pore formation through chemical reactions, which not only solves the problem of deteriorated film performance caused by other pore-forming methods, but more importantly, this pore-forming mechanism can be achieved using traditional polyimide film production equipment and processes. This results in higher maturity of film preparation technology, lower production costs, higher continuous efficiency in the preparation process, and easier continuous production of porous polyimide films. Attached Figure Description

[0057] Figure 1 This is a SEM cross-sectional image of the porous fluorinated polyimide film prepared in Example 1;

[0058] Figure 2 This is a SEM image of the micropores in the porous fluorinated polyimide film prepared in Example 2.

[0059] Figure 3 This is a SEM image of the micropores in the porous fluorinated polyimide film prepared in Example 3.

[0060] Figure 4 The image shows the micropore SEM scan morphology of the porous fluorinated polyimide film prepared in Example 4.

[0061] Figure 5 This is a SEM image of the micropores in the porous fluorinated polyimide film prepared in Example 5.

[0062] Figure 6 The image shows the micropore SEM scan morphology of the porous fluorinated polyimide film prepared in Example 6.

[0063] Figure 7 SEM image of the micropores in the porous fluorinated polyimide film prepared in Comparative Example 1;

[0064] Figure 8 The image shows the micropore SEM scan morphology of the porous fluorinated polyimide film prepared in Comparative Example 2.

[0065] Figure 9 The image shows the micropore SEM scan morphology of the porous fluorinated polyimide film prepared in Comparative Example 3. Detailed Implementation

[0066] This invention discloses a microporous fluorinated polyimide thin film material and its preparation method. Those skilled in the art can refer to the content of this document and appropriately modify the process parameters to achieve the same result. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments, and those skilled in the art can obviously make modifications or appropriate alterations and combinations to the methods and applications described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

[0067] The testing instruments, testing conditions, and methods for performing performance testing on the samples in this invention are as follows:

[0068] 1. Microstructure characterization: The microstructure of the gold-sputtered microporous polyimide film was observed using an XL30 field emission environmental scanning electron microscope (SEM) (FEI, USA).

[0069] 2. Heat resistance: TGA-2 thermogravimetric analyzer (TGA), PerkinElmer, USA, heating rate 10℃ / min, nitrogen atmosphere.

[0070] 3. Glass transition temperature: Static thermomechanical analyzer (TMA Q400), test atmosphere is nitrogen, heating rate is 5℃ / min, temperature range is 40℃~400℃.

[0071] 4. Mechanical properties: Mechanical property testing machine (Instron-1121 type), tensile rate 5mm / min, sample strip size 50mm×10mm, the test result is the average value of 10 test sample strips;

[0072] 5. Porosity Testing: This invention employs a density calculation method. The porous film is cut into 20mm × 20mm square samples using a die cutter. The film mass is weighed and its thickness is measured. The density of the sample is calculated; the density of polyimide is 1.4 g / cm³. 3 Porosity is calculated using the following formula:

[0073]

[0074] In the formula, ρ1 is the sample density calculated based on mass and volume, and ρ0 is the density of polyimide.

[0075] The molecular weight range of the monohydroxy-terminated poly(dimethylsiloxane) used in the specific embodiments of the present invention is 600 to 6000.

[0076] The present invention will be further described below with reference to the embodiments:

[0077] Example 1

[0078] A 500 mL three-necked round-bottom flask equipped with a nitrogen inlet and a mechanical stirrer was placed in a cold bath at -3 °C. 16.012 g of 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl was added to the reaction flask, followed by 100 mL of N,N'-dimethylacetamide (DMAc). The mechanical stirrer was turned on, and after the solids were completely dissolved, 14.711 g of biphenyltetracarboxylic dianhydride (BPDA) was added to the reaction flask. The temperature of the reaction solution was controlled to be ≤25 °C. After the addition was completed, the cold bath was turned off, and the reaction was continued at room temperature for 16 h to obtain a light yellow viscous gel.

[0079] Turn on the cold bath and set the temperature to -3℃. After the temperature of the above adhesive solution reaches the set temperature, add 13.156g of methyl 6-hydroxyhexanoate and 6.044g of poly(dimethylsiloxane) monohydroxy end-capping agent. After mixing evenly with the adhesive solution, slowly add 10.12g of triethylamine diluted with 30mL of DMAc to the reaction solution. After the addition is completed, turn off the cold bath and restore the reaction to room temperature for another 8 hours to obtain a light yellow viscous adhesive solution.

[0080] After filtration and defoaming, the above-mentioned adhesive solution is coated onto a glass plate and baked in a 100°C oven for 1 hour to fully cure the adhesive film. The adhesive film is then peeled off from the glass plate and fixed around its edges onto a hollow stainless steel frame. The film is then placed in a high-temperature oven, where the temperature is increased from 120°C to 200°C and held for 0.5 hours. The temperature is then further increased to 350°C and held for 0.5 hours to obtain a porous fluorinated polyimide film.

[0081] The microporous morphology of the prepared polyimide film is as follows: Figure 1 As shown, Figure 1 The image shows the SEM cross-sectional morphology of the porous fluorinated polyimide film prepared in Example 1. The relevant properties of the film are characterized as shown in Appendix Table 1.

[0082] Example 2

[0083] A 500 mL three-necked round-bottom flask equipped with a nitrogen inlet and a mechanical stirrer was placed in a cold bath at -3°C. 16.012 g of 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl was added to the reaction flask, followed by 100 mL of N,N'-dimethylacetamide (DMAc). The mechanical stirrer was turned on, and after the solids were completely dissolved, 10.906 g of pyromellitic dianhydride (PMDA) was added to the reaction flask. The temperature of the reaction solution was controlled to be ≤25°C. After the addition was completed, the cold bath was turned off, and the reaction was continued at room temperature for 16 h to obtain a light yellow viscous gel.

[0084] Turn on the cold bath and set the temperature to -3℃. After the temperature of the above adhesive solution reaches the set temperature, add 13.156g of methyl 6-hydroxyhexanoate and 6.044g of poly(dimethylsiloxane) monohydroxy end-capping agent. After mixing evenly with the adhesive solution, slowly add 10.12g of triethylamine diluted with 30mL of DMAc to the reaction solution. After the addition is completed, turn off the cold bath and restore the reaction to room temperature for another 8 hours to obtain a light yellow viscous adhesive solution.

[0085] After filtration and defoaming, the above-mentioned adhesive solution is coated onto a glass plate and baked in a 100°C oven for 1 hour to fully cure the adhesive film. The adhesive film is then peeled off from the glass plate and fixed around its edges onto a hollow stainless steel frame. The film is then placed in a high-temperature oven, where the temperature is increased from 120°C to 200°C and held for 0.5 hours. The temperature is then further increased to 350°C and held for 0.5 hours to obtain a porous fluorinated polyimide film.

[0086] The microporous morphology of the prepared polyimide film is as follows: Figure 2 As shown, Figure 2 The image shows the micropore SEM scan morphology of the porous fluorinated polyimide film prepared in Example 2. The film's related properties are characterized as shown in Appendix Table 1.

[0087] Example 3

[0088] A 500 mL three-necked round-bottom flask equipped with a nitrogen inlet and a mechanical stirrer was placed in a cold bath at -3°C. 16.012 g of 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl was added to the reaction flask, followed by 80 mL of N,N'-dimethylacetamide (DMAc). The mechanical stirrer was turned on, and after the solids were completely dissolved, 10.906 g of pyromellitic dianhydride (PMDA) was added to the reaction flask. The temperature of the reaction solution was controlled to be ≤25°C. After the addition was completed, the cold bath was turned off, and the reaction was continued at room temperature for 16 h to obtain a light yellow viscous gel.

[0089] Turn on the cold bath and set the temperature to -3℃. After the temperature of the above adhesive solution reaches the set temperature, add 14.419g of ethyl 6-hydroxyhexanoate and 6.044g of poly(dimethylsiloxane) monohydroxy end-capping agent. After mixing evenly with the adhesive solution, slowly add 10.12g of triethylamine diluted with 28mL of DMAc to the reaction solution. After the addition is completed, turn off the cold bath and restore the reaction to room temperature for another 8 hours to obtain a light yellow viscous adhesive solution.

[0090] After filtration and defoaming, the above-mentioned adhesive solution is coated onto a glass plate and baked in a 100°C oven for 1 hour to fully cure the adhesive film. The adhesive film is then peeled off from the glass plate and fixed around its edges onto a hollow stainless steel frame. The film is then placed in a high-temperature oven, where the temperature is increased from 120°C to 200°C and held for 0.5 hours. The temperature is then further increased to 350°C and held for 0.5 hours to obtain a porous fluorinated polyimide film.

[0091] The microporous morphology of the prepared polyimide film is as follows: Figure 3 As shown, Figure 3 The image shows the micropore SEM scan morphology of the porous fluorinated polyimide film prepared in Example 3. The film's related properties are characterized as shown in Appendix Table 1.

[0092] Example 4

[0093] A 500 mL three-necked round-bottom flask equipped with a nitrogen inlet and a mechanical stirrer was placed in a cold bath at -3°C. 10.012 g of 4,4'-diaminodiphenyl ether (ODA) and 100 mL of N-methyl-2-pyrrolidone (NMP)acetamide (DMAc) were added to the reaction flask. The mechanical stirrer was turned on, and after the solids were completely dissolved, 22.212 g of hexafluorodianhydride (6FDA) was added to the reaction flask. The temperature of the reaction solution was controlled to be ≤25°C. After the addition was completed, the cold bath was turned off, and the reaction was continued at room temperature for 16 h to obtain a light yellow viscous gel.

[0094] Turn on the cold bath and set the temperature to -3℃. After the temperature of the above adhesive solution reaches the set temperature, add 15.682g of methyl 8-hydroxyoctanoate and 6.044g of poly(dimethylsiloxane) monohydroxy end-capping agent. After mixing evenly with the adhesive solution, slowly add 10.12g of triethylamine diluted with 29mL of NMP to the reaction solution. After the addition is completed, turn off the cold bath and restore the reaction to room temperature for another 8 hours to obtain a light yellow viscous adhesive solution.

[0095] After filtration and defoaming, the above-mentioned adhesive solution is coated onto a glass plate and baked in a 100°C oven for 1 hour to fully cure the adhesive film. The adhesive film is then peeled off from the glass plate and fixed around its edges onto a hollow stainless steel frame. The film is then placed in a high-temperature oven, where the temperature is increased from 120°C to 200°C and held for 0.5 hours. The temperature is then further increased to 350°C and held for 0.5 hours to obtain a porous fluorinated polyimide film.

[0096] The microporous morphology of the prepared polyimide film is as follows: Figure 4 As shown, Figure 4 The image shows the micropore SEM scan morphology of the porous fluorinated polyimide film prepared in Example 4. The film's related properties are characterized as shown in Appendix Table 1.

[0097] Example 5

[0098] A 500 mL three-necked round-bottom flask equipped with a nitrogen inlet and a mechanical stirrer was placed in a cold bath at -3°C. 14.617 g of 1,3,3-triphenyl diether diamine (1,3,3-APB) and 100 mL of N-methyl-2-pyrrolidone (NMP) acetamide (DMAc) were added to the reaction flask. The mechanical stirrer was turned on, and after the solids were completely dissolved, 22.212 g of hexafluorodianhydride (6FDA) was added to the reaction flask. The temperature of the reaction solution was controlled to be ≤25°C. After the addition was completed, the cold bath was turned off, and the reaction was continued at room temperature for 16 h to obtain a light yellow viscous gel.

[0099] Turn on the cold bath and set the temperature to -3℃. After the temperature of the above adhesive solution reaches the set temperature, add 15.682g of methyl 8-hydroxyoctanoate and 6.044g of poly(dimethylsiloxane) monohydroxy end-capping agent. After mixing evenly with the adhesive solution, slowly add 10.12g of triethylamine diluted with 47mL of NMP to the reaction solution. After the addition is completed, turn off the cold bath and restore the reaction to room temperature for another 8 hours to obtain a light yellow viscous adhesive solution.

[0100] After filtration and defoaming, the above-mentioned adhesive solution is coated onto a glass plate and baked in a 100°C oven for 1 hour to fully cure the adhesive film. The adhesive film is then peeled off from the glass plate and fixed around its edges onto a hollow stainless steel frame. The film is then placed in a high-temperature oven, where the temperature is increased from 120°C to 200°C and held for 0.5 hours. The temperature is then further increased to 350°C and held for 0.5 hours to obtain a porous fluorinated polyimide film.

[0101] The microporous morphology of the prepared polyimide film is as follows: Figure 5 As shown, Figure 5 The image shows the micropore SEM scan morphology of the porous fluorinated polyimide film prepared in Example 5. The film's related properties are characterized as shown in Appendix Table 1.

[0102] Example 6

[0103] A 500 mL three-necked round-bottom flask equipped with a nitrogen inlet and a mechanical stirrer was placed in a cold bath at -3°C. 16.012 g of 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl and 100 mL of N-methyl-2-pyrrolidone (NMP)acetamide (DMAc) were added to the reaction flask. The mechanical stirrer was turned on, and after the solids were completely dissolved, 11.106 g of hexafluorodianhydride (6FDA) and 7.356 g of BPDA were added to the reaction flask. The temperature of the reaction solution was controlled to be ≤25°C. After the addition was completed, the cold bath was turned off, and the reaction was continued at room temperature for 16 h to obtain a light yellow viscous gel.

[0104] Turn on the cold bath and set the temperature to -3℃. After the temperature of the above adhesive solution reaches the set temperature, add 14.419g of ethyl 6-hydroxyhexanoate and 6.044g of poly(dimethylsiloxane) monohydroxy end-capping agent. After mixing evenly with the adhesive solution, slowly add 10.12g of triethylamine diluted with 37mL of NMP to the reaction solution. After the addition is completed, turn off the cold bath and restore the reaction to room temperature for another 8 hours to obtain a colorless viscous adhesive solution.

[0105] After filtration and defoaming, the above-mentioned adhesive solution is coated onto a glass plate and baked in a 100°C oven for 1 hour to fully cure the adhesive film. The adhesive film is then peeled off from the glass plate and fixed around its edges onto a hollow stainless steel frame. The film is then placed in a high-temperature oven, where the temperature is increased from 120°C to 200°C and held for 0.5 hours. The temperature is then further increased to 350°C and held for 0.5 hours to obtain a porous fluorinated polyimide film.

[0106] The microporous morphology of the prepared polyimide film is as follows: Figure 6 As shown, Figure 6 The image shows the micropore SEM scan morphology of the porous fluorinated polyimide film prepared in Example 6. The film's related properties are characterized as shown in Appendix Table 1.

[0107] Comparative Example 1

[0108] A 500 mL three-necked round-bottom flask equipped with a nitrogen inlet and a mechanical stirrer was placed in a cold bath at -3°C. 16.012 g of 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl was added to the reaction flask, followed by 100 mL of N,N'-dimethylacetamide (DMAc). The mechanical stirrer was turned on, and after the solids were completely dissolved, 10.906 g of pyromellitic dianhydride (PMDA) was added to the reaction flask. The temperature of the reaction solution was controlled to be ≤25°C. After the addition was completed, the cold bath was turned off, and the reaction was continued at room temperature for 16 h to obtain a light yellow viscous gel.

[0109] Turn on the cold bath and set the temperature to -3℃. After the temperature of the above adhesive solution reaches the set temperature, add 14.618g of methyl 6-hydroxyhexanoate and mix it evenly with the adhesive solution. Then, dilute 10.12g of triethylamine with 30mL of DMAc and slowly add it dropwise to the reaction solution. After the addition is completed, turn off the cold bath and restore the reaction to room temperature for another 8 hours to obtain a light yellow viscous adhesive solution.

[0110] After filtration and defoaming, the above-mentioned adhesive solution is coated onto a glass plate and baked in a 100°C oven for 1 hour to fully cure the adhesive film. The adhesive film is then peeled off from the glass plate and fixed around its edges onto a hollow stainless steel frame. The film is then placed in a high-temperature oven, where the temperature is increased from 120°C to 200°C and held for 0.5 hours. The temperature is then further increased to 350°C and held for 0.5 hours to obtain a porous fluorinated polyimide film.

[0111] The microporous morphology of the prepared polyimide film is as follows: Figure 7 As shown, Figure 7 The micropore SEM scan morphology of the porous fluorinated polyimide film prepared in Comparative Example 1 is shown in Appendix Table 1. The relevant properties of the film are characterized.

[0112] Comparative Example 2

[0113] A 500 mL three-necked round-bottom flask equipped with a nitrogen inlet and a mechanical stirrer was placed in a cold bath at -3°C. 16.012 g of 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl was added to the reaction flask, followed by 100 mL of N,N'-dimethylacetamide (DMAc). The mechanical stirrer was turned on, and after the solids were completely dissolved, 10.906 g of pyromellitic dianhydride (PMDA) was added to the reaction flask. The temperature of the reaction solution was controlled to be ≤25°C. After the addition was completed, the cold bath was turned off, and the reaction was continued at room temperature for 16 h to obtain a light yellow viscous gel.

[0114] Turn on the cold bath and set the temperature to -3℃. After the temperature of the above adhesive solution reaches the set temperature, add 17.424g of methyl 8-hydroxyoctanoate and mix it evenly with the adhesive solution. Then, dilute 10.12g of triethylamine with 30mL of DMAc and slowly add it dropwise to the reaction solution. After the addition is finished, turn off the cold bath and restore the reaction to room temperature for another 8 hours to obtain a light yellow viscous adhesive solution.

[0115] After filtration and defoaming, the above-mentioned adhesive solution is coated onto a glass plate and baked in a 100°C oven for 1 hour to fully cure the adhesive film. The adhesive film is then peeled off from the glass plate and fixed around its edges onto a hollow stainless steel frame. The film is then placed in a high-temperature oven, where the temperature is increased from 120°C to 200°C and held for 0.5 hours. The temperature is then further increased to 350°C and held for 0.5 hours to obtain a porous fluorinated polyimide film.

[0116] The microporous morphology of the prepared polyimide film is as follows: Figure 8 As shown, Figure 8 The image shows the micropore SEM scan morphology of the porous fluorinated polyimide film prepared in Comparative Example 2. The film's related properties are characterized as shown in Appendix Table 1.

[0117] Comparative Example 3

[0118] A 500 mL three-necked round-bottom flask equipped with a nitrogen inlet and a mechanical stirrer was placed in a cold bath at -3°C. 16.012 g of 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl was added to the reaction flask, followed by 100 mL of N,N'-dimethylacetamide (DMAc). The mechanical stirrer was turned on, and after the solids were completely dissolved, 10.906 g of pyromellitic dianhydride (PMDA) was added to the reaction flask. The temperature of the reaction solution was controlled to be ≤25°C. After the addition was completed, the cold bath was turned off, and the reaction was continued at room temperature for 16 h to obtain a light yellow viscous gel.

[0119] Turn on the cold bath and set the temperature to -3℃. After the temperature of the above adhesive solution reaches the set temperature, add 7.309g of methyl 6-hydroxyhexanoate and 30.217g of poly(dimethylsiloxane) monohydroxy end-capping agent. After mixing evenly with the adhesive solution, slowly add 10.12g of triethylamine diluted with 30mL of DMAc to the reaction solution. After the addition is completed, turn off the cold bath and restore the reaction to room temperature for another 8 hours to obtain a light yellow viscous adhesive solution.

[0120] After filtration and defoaming, the above-mentioned adhesive solution is coated onto a glass plate and baked in a 100°C oven for 1 hour to fully cure the adhesive film. The adhesive film is then peeled off from the glass plate and fixed around its edges onto a hollow stainless steel frame. The film is then placed in a high-temperature oven, where the temperature is increased from 120°C to 200°C and held for 0.5 hours. The temperature is then further increased to 350°C and held for 0.5 hours to obtain a porous fluorinated polyimide film.

[0121] The microporous morphology of the prepared polyimide film is as follows: Figure 9 As shown, Figure 9 The micropore SEM scan morphology of the porous fluorinated polyimide film prepared in Comparative Example 3 is shown in Appendix Table 1. The relevant properties of the film are characterized.

[0122] Table 1

[0123]

[0124]

[0125] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A microporous fluoropolyimide film material, characterized by, It is obtained by imidization reaction of fluorinated polyamide ester having the structure of Formula I; Formula I; Wherein, z≥1000; Ar1 and Ar2 are independently selected from unsubstituted fluorinated aromatic groups, unsubstituted fluorinated heteroaromatic groups, unsubstituted fluorinated aliphatic groups, unsubstituted aromatic groups, unsubstituted heteroaromatic groups, or unsubstituted aliphatic groups; at least one of Ar1 and Ar2 is an unsubstituted fluorinated aromatic group, an unsubstituted fluorinated heteroaromatic group, or an unsubstituted fluorinated aliphatic group. M1 and M2 are independently selected from C4~C 15 The fluoropolymer has an alkyl or poly(dimethylsiloxane) group, and M1 and M2 are not the same; the fluorinated polyamide ester having the structure of Formula I has a poly(dimethylsiloxane) group, and the molar amount of the poly(dimethylsiloxane) group accounts for 9% to 13% of the total molar amount of M1 and M2; the poly(dimethylsiloxane) group is derived from a monohydroxy-terminated poly(dimethylsiloxane) with a molecular weight of 600. The imidization reaction includes, in sequence, a pre-baking curing stage, an imidization stage, and a high-temperature treatment stage; The pre-baking and curing section is processed at a temperature of 50℃ to 150℃ for a time of 0.1 h to 10.0 h. The imidization process is performed at a temperature of 100℃ to 250℃ for a time of 0.1 h to 10.0 h. The high-temperature treatment section operates at temperatures ranging from 180°C to 400°C for a duration of 0.1 h to 10.0 h.

2. The microporous fluorinated polyimide membrane material of claim 1, wherein In the fluorinated polyamide ester, at least one fluorinated structural unit among Ar1 and Ar2 accounts for 1% to 100% of the total number of structural units.

3. The microporous fluorinated polyimide membrane material of claim 1, wherein M1 and M2 are independently selected from C4~C having the structure of formula Ia. 15 Alkyl ester or poly(dimethylsiloxane) group having the structure of formula Ib; Formula I-a; Formula I-b; Wherein, n ≥ 1, and m ≥ 1; Where x≥1; R represents an adipose chain.

4. The microporous fluorinated polyimide membrane material of claim 1, wherein The Ar1 has one or more of the structures Ar1-a to Ar1-c or Ar1-e to Ar1-i; Formula Ar1-a; Formula Ar1-b; Formula Ar1-c; Formula Ar1-e; Formula Ar1-f; Formula Ar1-g; Formula Ar1-h; Formula Ar1-i; The Ar2 has one or more of the structures of Ar2-a to Ar2-h; Ar2-a; Ar2-b; Ar2-c; Ar2-d; Ar2-e; Ar2-f; Ar2-g; Ar2-h; Wherein, R1 and R2 are independently selected from H, F or trifluoromethyl; said R 1 and R 2 are independently selected from one of the groups of structures shown in Formulas 1-8; Formula 1 ; Formula 2; Formula 3; Formula 4; Formula 5; Formula 6; Formula 7; Formula 8; X is selected from hydrogen, alkyl, cycloalkyl, aryl, fluoroalkyl, hydroxyl, alkoxy, phenoxy, cyano, nitro, amino, acetamino, ester, acyl, halogen, or carboxyl. The y is an integer from 1 to 4.

5. The microporous fluorinated polyimide membrane material of claim 1, wherein The microporous fluorinated polyimide film material has a structure of formula II; Formula II.

6. A method for producing the microporous fluorine-containing polyimide film material according to any one of claims 1 to 5, characterized by, Includes the following steps: Fluorinated polyamide esters are subjected to an imidization reaction to obtain microporous fluorinated polyimide film materials.

7. The method for preparing the microporous fluorinated polyimide film material according to claim 6, characterized in that, Specifically, the following steps are included: S1) A dianhydride having the structure of formula a and a diamine having the structure of formula b are reacted to obtain polyamic acid; Formula a; Formula b; S2) reacting a monohydroxy compound with the polyamic acid obtained in step S1) to obtain a fluorine-containing polyamide ester; the monohydroxy compound is a C4-C 15 alkyl alcohol and a monohydroxy-terminated poly(dimethylsiloxane) having the structure of formula c; the monohydroxy-terminated poly(dimethylsiloxane) has a molecular weight of 600; Formula c; R is a fatty chain; S3) The fluorinated polyamide ester obtained in step S2) is subjected to an imidization reaction to obtain a microporous fluorinated polyimide film material; The imidization reaction includes, in sequence, a pre-baking curing stage, an imidization stage, and a high-temperature treatment stage; The pre-baking and curing section is processed at a temperature of 50℃ to 150℃ for a time of 0.1 h to 10.0 h. The imidization process is performed at a temperature of 100℃ to 250℃ for a time of 0.1 h to 10.0 h. The high-temperature treatment section operates at temperatures ranging from 180°C to 400°C for a duration of 0.1 h to 10.0 h.

8. The method of claim 7 wherein the microporous fluoropolyimide film material is prepared by the steps of: In step S2), the reaction temperature is -10℃ to 30℃, and the reaction time is 15 h to 17 h.

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