Polyimide film, and preparation method therefor and use thereof

Abstract

The present application provides a polyimide film, and a preparation method therefor and the use thereof. The method comprises the following steps: sequentially performing hybrid chemical imidization treatment, film casting treatment, heating and curing treatment, and peeling treatment on an adhesive solution used for forming a polyimide film, so as to obtain an initial adhesive film, subjecting the initial adhesive film to at least one instance of infiltration chemical imidization treatment and solvent elution treatment, so as to obtain an intermediate adhesive film, and subjecting the intermediate adhesive film to biaxial stretching treatment and high-temperature treatment to obtain the polyimide film. The preparation method for a polyimide (PI) film provided by the present application can solve the engineering problems such as peeling of the adhesive film being difficult and tensile tearing of the adhesive film in the PI film production process, and especially in an ultra-thin PI film production process, thereby preparing high-performance polyimide films.

Description

A polyimide film, its preparation method and application

[0001] This application claims priority to Chinese Patent Application No. 202411555157.0, filed on November 4, 2024, entitled "A polyimide film and its preparation method, production apparatus and application", the entire contents of which are incorporated herein by reference.

[0002] This application claims priority to Chinese Patent Application No. 202511475387.0, filed on October 15, 2025, entitled "A polyimide film and its preparation method and application", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of polymer materials technology, and in particular to a polyimide film, its preparation method, and its application. Background Technology

[0004] Polyimide (PI) film is a type of organic polymer film material with excellent comprehensive performance. Since DuPont industrialized Kapton-type PI film in the 1960s, PI film has been widely used in high-tech fields such as aviation, aerospace, electronics, and electrical engineering. It has developed into a key basic material of modern industry. Especially in the microelectronics industry, PI film, as the substrate of flexible copper clad laminate (FCCL), has promoted the rapid progress and large-scale application of flexible printed circuit board (FPCB) technology, and has also been influencing the updating and iteration of microelectronic packaging technology.

[0005] In recent years, with the rapid development of miniaturization and portability of consumer electronics products and the lightweighting of equipment such as new energy vehicles and aerospace vehicles, PI film, a key raw material for FCCL, is being transformed towards thinner and thinner materials. The mainstream demand thickness has extended from the traditional 25μm~75μm to 3.5μm~75μm. Among them, the demand for PI film with a thickness of 3.5μm~12.5μm has surged and is expected to become the mainstream substrate for the next generation of FPCBs.

[0006] Currently, the industrialized PI film manufacturing technology mainly adopts a two-step method. First, a polyamic acid (PAA) solution of a certain viscosity is prepared by polycondensation of aromatic dianhydride and aromatic diamine in a solvent. Then, a film containing a certain amount of solvent is prepared by casting the PAA solution onto a ring-shaped steel belt, or by mixing PAA with dehydrating agent, catalyst, etc. and casting it onto a ring-shaped steel belt to prepare a film containing a certain amount of solvent. Finally, the film is stretched and subjected to high temperature treatment to obtain the PI film. However, the following technical bottlenecks exist when using this technology to manufacture PI films with a thickness of 12.5μm and below: First, compared to the casting process of PI films with a thickness of more than 12.5μm, the amount of PAA solution extruded from the die per unit time is reduced by several times. The "curtain" formed by casting is both light and thin, and is easily disturbed by the surrounding air during the production process, resulting in wrinkles or damage to the surface of the film formed on the annular steel belt, affecting product quality, and in severe cases, even making production impossible; Second, after the cast film is heated and volatilized on the annular steel belt, the "thin" film containing a small amount of solvent after the evaporation of organic volatiles is firmly bonded to the smooth and flat steel belt, making it difficult to peel off, and the stability of the process cannot be guaranteed; Finally, when the peeled "thin" film is stretched and subjected to high-temperature treatment under the fixation of the fixture, it is very easy to tear when stretched at high temperature due to its low tensile strength and poor toughness, which often leads to production interruptions and poor production continuity.

[0007] To address the aforementioned technical problems, Japanese patent application JP2009226632A discloses a method for preparing an ultrathin PI film. This method involves adding a release agent to a PAA precursor solution and coating it onto a substrate surface to form a gel film. The resulting gel film is not subjected to peeling or stretching; instead, it is directly heated and cured on the substrate surface before being peeled off to obtain the ultrathin PI film. Chinese invention patent CN110343275B discloses a method for preparing an ultrathin PI film. This method involves adding a certain amount of plasticizer to the PAA solution to improve the elongation at break and toughness of the manufactured film, and also to lower the glass transition temperature. The film is then subjected to high-ratio high-temperature longitudinal stretching and low-temperature transverse stretching to produce a PI film with a thickness of 5 μm. Both of these invention patent proposals are improvements on industrially mature two-step manufacturing technologies. While Japanese patent application JP2009226632A can produce PI films with a thickness of less than 10 μm, this method affects the surface roughness of the PI film and also suffers from low production efficiency. The method described in Chinese invention patent CN110343275B requires extremely high precision in film-forming equipment. During high-ratio stretching, uneven stretching force can lead to localized wrinkles, deformation, or uneven thickness in the produced PI film, resulting in color differences and affecting product performance and appearance. Furthermore, phthalate plasticizers have been identified as carcinogenic, teratogenic, and mutagenic, posing significant health risks and have been banned in many plastic product processing industries. Therefore, this method has limitations in industrial application. In addition, Chinese invention patents CN104059551A, CN105131320B, and CN116238220A disclose coating methods for manufacturing ultra-thin PI films, capable of providing PI films with thicknesses of 1μm to 6μm. Specifically, a PAA solution is coated onto the surface of a substrate containing a release agent or adhesive, followed by high-temperature imidization to obtain a composite film containing an ultra-thin PI film layer. This composite film can be used directly or after peeling off the base layer. However, ultrathin PI films manufactured using this method exhibit poor thickness uniformity and low mechanical strength, and cannot be produced efficiently via roll-to-roll processing. Chinese invention patents CN113372591B and CN108409994B disclose a one-step method for manufacturing ultrathin PI films. This method first prepares a soluble PI solution, then coats the soluble PI solution onto a substrate surface to form a film. After drying the solvent by heating, the film is peeled off to obtain the ultrathin PI film. This method eliminates the need for imidization and high-temperature stretching treatments, making it simple and efficient. However, this method requires soluble PI as the coating precursor solution, which not only limits the molecular structure of PI but also faces challenges such as the difficulty in obtaining monomers and high raw material costs, often resulting in insufficient mechanical properties of the ultrathin PI film.

[0008] Therefore, developing a simple, stable, and easily industrialized method for preparing ultrathin polyimide films, solving engineering problems such as film peeling difficulties and film stretching and tearing in PI film processes, especially ultrathin PI film processes, and preparing high-performance polyimide films is an urgent technical problem to be solved in this field. Summary of the Invention

[0009] This application provides a polyimide film, its preparation method, and its application, to at least solve engineering problems such as film peeling difficulties and film stretching and tearing in PI film manufacturing processes, especially ultra-thin PI film manufacturing processes, and to achieve the technical effect that the film is not easily damaged, easy to peel, and not easily torn during high-temperature stretching, thus producing a high-performance polyimide film.

[0010] One aspect of this application provides a method for preparing a polyimide film, comprising the following steps: sequentially subjecting an adhesive solution used to form a polyimide film to a mixing chemical imidization treatment, a casting film-forming treatment, a heating curing treatment, and a peeling treatment to obtain an initial adhesive film; the initial adhesive film undergoes at least one immersion chemical imidization treatment and a solvent elution treatment to obtain an intermediate adhesive film; and the intermediate adhesive film undergoes biaxial stretching treatment and high-temperature treatment to obtain the polyimide film.

[0011] According to one embodiment of this application, the adhesive comprises a precursor solution and a chemical imidizing agent solution. The precursor solution comprises a first polyamic acid solution and / or a polyimide-polyamic acid solution. The polyimide-polyamic acid solution is a mixture of a second polyamic acid solution and polyimide or a polyamic acid-polyimide copolymer solution. The solid content of the first polyamic acid solution and the polyimide-polyamic acid solution is 8%-12%.

[0012] According to one embodiment of this application, the first polyamic acid solution is prepared by polycondensation reaction of a first aromatic dianhydride and a first aromatic diamine in a solvent in which nanofillers are dispersed; and / or, the second polyamic acid solution is prepared by polycondensation reaction of a second aromatic dianhydride and a second aromatic diamine in a solvent in which nanofillers are dispersed.

[0013] According to one embodiment of this application, in the adhesive solution, the mass ratio of the precursor solution to the imidizing agent is (10:1) to (1:1).

[0014] According to one embodiment of this application, the heat curing treatment is performed at a temperature of 60℃-120℃ for a time of 15s-60s; and / or, the infiltration chemical imidization treatment includes a first infiltration chemical imidization treatment and a second infiltration chemical imidization treatment sequentially performed on the product obtained from the heat curing treatment; the first infiltration chemical imidization treatment is performed at a temperature of 45℃-100℃ for a time of 5s-40s; the second infiltration chemical imidization treatment is performed at a temperature of 45℃-150℃ for a time of 5s-40s; and / or, the solvent elution treatment is performed at a temperature of 10℃-30℃ for a time of 5s-40s.

[0015] According to one embodiment of this application, the tensile strength of the initial adhesive film is 10 MPa to 100 MPa; and / or, the tensile strength of the intermediate adhesive film is 30 MPa to 120 MPa; and / or, the solvent content of the intermediate adhesive film is 30% to 180%.

[0016] According to one embodiment of this application, the adhesive comprises a silane coupling agent, the silane coupling agent comprising a compound having the structure shown in Formula I:

[0017] Formula I, wherein R1 is selected from C1-C6 alkyl groups, -O-R5, -HN-R6, -HN-R7-Ph, or -Ph, wherein R5, R6, and R7 are each independently selected from C1-C9 alkyl groups, and Ph represents phenyl; the formula I is connected between R2 and R3. This indicates that R2 and R3 are independent of each other or connected to each other; and R2 and R3 are each independently selected from -H, C1-C5 alkyl, C7-C12 alkylphenyl, C2-C5 alkenyl, C2-C5 alkynyl, C2-C5 ester, halogen, C1-C5 haloalkyl, C2-C5 cyano; R4 is selected from C1-C10 alkyl.

[0018] According to one embodiment of this application, R1 is selected from -CH3, -CH2CH2CH3, -C(CH3)3, -CH2(CH2)4CH3, OCH2CH3, -OCH2(CH2)3CH3, -OCH2(CH2)7CH3, -HNCH3, -HNCH2CH3, -HN(CH3)2, -N(CH3)CH2Ph, or -Ph; and / or, when R2 and R3 are independent of each other, R2 and R3 are each independently selected from -H, -CH3, -CH2CH3, -CH2 Ph, -CH2CH=CH2, -CH2(CH2)2CH=CH2, -CH2C≡CH, -CH2(CH2)2C≡CH, -CH2CH2OOCCH3, I, Br, Cl, -CH2CN, -CH2CH2CN or -CH2(CH2)2CN; when R2 and R3 are connected to each other, R2 and R3 are each independently selected from -CH2-, -CHBr- or -CH2CH2-; and / or, R4 is selected from -CH3, -CH2CH3, -CH2(CH2)6CH3.

[0019] Another aspect of this application provides a polyimide film manufactured using the above-described method for preparing polyimide films.

[0020] According to one embodiment of this application, the polyimide film contains a silane coupling agent, which includes compounds having the structure shown in Formula I.

[0021] According to one embodiment of this application, the silane coupling agent in the polyimide film has a mass percentage content of 1% to 20%.

[0022] According to one embodiment of this application, the thickness of the polyimide film is 3.5 μm to 12.5 μm; and / or, the linear coefficient of thermal expansion of the polyimide film is 2 ppm / ℃ to 20 ppm / ℃; and / or, the surface tension of the polyimide film is greater than or equal to 36 dyn / cm.

[0023] Another aspect of this application provides a laminated structure, including a polyimide film and a metal layer stacked with the polyimide film; wherein the polyimide film includes a polyimide film prepared according to the above-described method for preparing polyimide film or the above-described polyimide film.

[0024] According to one embodiment of this application, the metal layer includes a copper layer.

[0025] Another aspect of this application provides an electronic product including the aforementioned laminated structure.

[0026] In another aspect, this application provides a polyimide film production apparatus for performing the above-described method for preparing a polyimide film, comprising a mixer, an extrusion die, a heating drive roller, a first chemical imidization reaction vessel, a second chemical imidization reaction vessel, and a solvent elution vessel; the mixer is connected to the extrusion die; the extrusion die and the heating drive roller are arranged opposite to each other, such that the adhesive liquid extruded by the extrusion die contacts the heating drive roller to perform the heating curing treatment, thereby obtaining an initial adhesive film; the first chemical imidization reaction vessel is used to perform a first wetting chemical imidization treatment; the second chemical imidization reaction vessel is used to perform a second wetting chemical imidization treatment; and the solvent elution vessel is used to perform the solvent elution treatment.

[0027] According to one embodiment of this application, each of the first chemical imidization reaction vessel, the second chemical imidization reaction vessel, and the solvent elution vessel is provided with at least two guide rollers, so that the initial adhesive film comes into contact with the solvent in the first chemical imidization reaction vessel, the second chemical imidization reaction vessel, and the solvent elution vessel in sequence; and / or, the width of the adhesive liquid extruded by the extrusion die is 200mm-2000mm.

[0028] The method for preparing polyimide films provided in this application improves the tensile strength of the film through chemical imidization of the adhesive solution; it further increases the proportion of imide rings in the film through at least one contact between the film and the chemical imidizing reagent, thereby improving the tensile strength of the film through rapid chemical imidization reaction; and it controls the solvent content of the film by contact elution with the solvent, so that the film has both strength and toughness, solving the problems of tearing and film breakage during biaxial stretching and high-temperature treatment. This solves the engineering problems such as film peeling difficulties and film stretching and tearing in PI film manufacturing processes, especially ultra-thin PI film manufacturing processes. It has the advantages of simple preparation method, easy industrialization, film that is not easily damaged during manufacturing, easy to peel, and not easily torn during high-temperature stretching. It can produce polyimide films with a thickness of 3.5μm to 12.5μm and a linear thermal expansion coefficient of 2ppm / ℃ to 20ppm / ℃. Attached Figure Description

[0029] Figure 1 is a schematic diagram of a polyimide film production apparatus according to an embodiment of this application;

[0030] Figure 2 is a schematic diagram of a polyimide film production apparatus according to an embodiment of this application;

[0031] Figure 3 shows the silane coupling agent C-1 synthesized in Example 16. 1 HNMR spectrum.

[0032] Explanation of reference numerals in the attached drawings: Mixer 101; Extrusion die 102; Heating drive roller 103; First guide roller 104; Second guide roller 105; Third guide roller 106; Fourth guide roller 107; Fifth guide roller 108; Sixth guide roller 109; Seventh guide roller 110; Eighth guide roller 111; Ninth guide roller 112; Tenth guide roller 113; First chemical imidization reaction vessel 201; Second chemical imidization reaction vessel 202; Solvent elution vessel 203. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] The first aspect of this application provides a method for preparing an imide film, comprising the following steps: sequentially subjecting a liquid adhesive for forming a polyimide film to a mixing chemical imidization treatment, a casting film-forming treatment, a heating curing treatment, and a peeling treatment to obtain an initial adhesive film; the initial adhesive film undergoes at least one immersion chemical imidization treatment and a solvent elution treatment to obtain an intermediate adhesive film; the intermediate adhesive film undergoes biaxial stretching treatment and high-temperature treatment to obtain a polyimide film.

[0035] Specifically, the adhesive solution includes a precursor solution and a chemical imidizing agent solution. The precursor solution includes a precursor, which is a raw material used to form polyimide. Specifically, it may include polyamic acid and / or polyamic acid-polyimide copolymer (or polyimide-polyamic acid copolymer). Specifically, one or more of polyamic acid, polyamic acid-polyimide copolymer, and mixtures of polyimide and polyimide can be used as the precursor. For example, polyamic acid, polyamic acid-polyimide copolymer, or a mixture of the two can be used as the precursor.

[0036] Specifically, the precursor solution may include a first polyamic acid solution (PAA solution) and / or a polyimide-polyamic acid solution (or polyamide-polyimide solution (PAA-PI solution)), wherein the polyimide-polyamic acid solution is a mixture of a second polyamic acid solution and polyimide or a polyamic acid-polyimide copolymer solution.

[0037] Specifically, the first polyamic acid solution can be prepared by polycondensation reaction of the first aromatic dianhydride and the first aromatic diamine in a solvent in which nanofillers are dispersed.

[0038] Specifically, the second polyamic acid solution can be prepared by polycondensation reaction of the second aromatic dianhydride and the second aromatic diamine in a solvent in which nanofillers are dispersed.

[0039] In the embodiments of this application, polyimide can be obtained by conventional methods, such as commercial purchase or self-made by conventional methods, such as using commercially available TPI powder.

[0040] Specifically, the polyimide can be a thermoplastic polyimide. Thermoplastic polyimide can be prepared by reacting a second polyamic acid solution with an organic amine compound under heating conditions; or, the thermoplastic polyimide includes commercially available thermoplastic polyimides.

[0041] In some embodiments, the precursor solution further contains inorganic nanofillers, specifically inorganic nanofillers dispersed in a first polyamic acid solution and / or a polyamic acid-polyimide copolymer solution, so that the precursor solution contains inorganic nanofillers, thereby introducing inorganic nanofillers into the obtained polyimide film.

[0042] In this application, polyamic acid can be formed by the condensation of aromatic dianhydride and aromatic diamine. The solvent in the polyamic acid solution comes from the solvent used in the synthesis process of polyamic acid. That is, the polyamic acid solution can be formed by the condensation reaction of aromatic dianhydride and aromatic diamine in a solvent. Furthermore, it can be formed by the condensation reaction of aromatic dianhydride and aromatic diamine in a solvent containing inorganic nanofillers.

[0043] Specifically, the first polyamic acid solution can be prepared by a polycondensation reaction of a first aromatic dianhydride and a first aromatic diamine in a solvent in which nanofillers are dispersed. This application does not limit the specific conditions of the polycondensation reaction described above, and commonly used reaction conditions in the art can be used. For example, in one embodiment, under nitrogen protection, the nanofillers are first dispersed in a solvent, and then the first aromatic dianhydride and the first aromatic diamine are added separately to induce a polycondensation reaction between the first aromatic dianhydride and the first aromatic diamine, thereby obtaining the first polyamic acid solution.

[0044] In addition, the polyimide-polyamic acid copolymer solution can be prepared by reacting a second polyamic acid solution with an organic amine compound under heating conditions.

[0045] In the embodiments of this application, unless otherwise specified, the organic amine compounds used may include tertiary amine compounds, which are selected from at least one of quinoline, isoquinoline, pyridine, 3-methylpyridine, triethylamine, and N-methylimidazole.

[0046] In the embodiments of this application, the tensile strength of the initial adhesive film can be 10MPa to 100MPa, for example, a range of 10MPa, 30MPa, 50MPa, 80MPa, 100MPa or any two of these.

[0047] In the embodiments of this application, the tensile strength of the intermediate film is 30MPa to 120MPa, for example, a range of 30MPa, 50MPa, 70MPa, 90MPa, 100MPa, 110MPa, 120MPa or any two of these.

[0048] In the embodiments of this application, the tensile strength of the initial film and the intermediate film can be measured by conventional methods, such as by referring to GB / T 1040.3-2006 "Determination of tensile properties of plastics - Part 3: Test conditions for films and sheets", or by using an Instron 68SC-05 universal tensile testing machine.

[0049] In the embodiments of this application, the solvent content of the intermediate film can be 30% to 180%, for example, 30%, 60%, 100%, 140%, 180%, or a range consisting of any two of these.

[0050] Specifically, the method for preparing the polyimide film provided in this application involves sequentially performing a mixing chemical imidization, casting film formation, heat curing, and peeling treatment on the adhesive solution to obtain an initial adhesive film (HGF). The initial adhesive film undergoes at least one immersion chemical imidization treatment and solvent elution treatment to obtain an intermediate adhesive film (SGF). The intermediate adhesive film is then subjected to biaxial stretching at high temperature to obtain the polyimide film. The initial adhesive film (HGF) has a tensile strength of 10 MPa to 100 MPa; the intermediate adhesive film (SGF) has a tensile strength of 30 MPa to 120 MPa and a solvent content of 30% to 180%.

[0051] The method for preparing the polyimide film provided in this application uses an adhesive solution including an imidizing agent solution, and further including at least one of a first polyamic acid solution and a polyimide-polyamic acid solution. For example, the adhesive solution is a mixture of a first polyamic acid solution and a chemical imidizing agent solution, or a mixture of a polyimide-polyamic acid solution and a chemical imidizing agent solution, or a mixture of a first polyamic acid solution, a polyimide-polyamic acid solution, and a chemical imidizing agent solution.

[0052] In the method provided in this application, the first aromatic dianhydride may be selected from pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA), 2,2',3,3'-biphenyltetracarboxylic dianhydride (a-BPDA), 4,4'-diphenyl ether dianhydride (ODPA), 3,4,3',4'-triphenyl diether dianhydride (HQDPA), diphenyl diether dianhydride (BzDPA), 4,4'-(hexafluoroisopropene) phthalic anhydride (6FDA), 2,2-diphenylpropane- At least one of 3,4,3',4'-tetracarboxylic acid dianhydride (PDPA), p-phenylene-bis(phenyltriptate) dianhydride (TAHQ), 1,5,6,10-tetrahydro-methylbridgedoxazo[4,5-D]oxacycloheptane-2,4,7,9-tetraone (DTOPT), 5-[4-(1,3-dioxo-2-benzofuran-5-yl)phenyl]-2-benzofuran-1,3-dione (TPDA), and 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF).

[0053] In the method provided in this application, the first aromatic diamine may be selected from at least one of 4,4'-diaminodiphenyl ether (4,4'-ODA), 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), 1,4-phenylenediamine (PDA), 1,4-bis(4-aminophenoxy)benzene (1,4,4-APB), 9,9-bis(4-aminophenyl)fluorene (BAPF), 4,4'-bis(4-aminophenoxy)biphenyl (BAPB), 4,4'-biphenyldiamine (Bz), 2,6-diamino-9H-fluorene-9-one (DAFT), and 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane (HFBAPP).

[0054] This application does not limit the molar ratio of the first aromatic diamine to the first aromatic dianhydride. In one embodiment, the molar ratio of the first aromatic diamine to the first aromatic dianhydride is 1:0.995 to 1:1.02.

[0055] More specifically, unless otherwise specified, the solvent used in this application may be selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, acetone, butanone, toluene, ethyl acetate, tetrahydrofuran, and chloroform. The nanofiller may be selected from at least one of silica, dicalcium phosphate, calcium pyrophosphate, calcium oxide, alumina, titanium dioxide, and zirconium dioxide. The filler's function is to improve the opening performance of the polyimide film, achieving antistatic and anti-adhesion effects. The amount added is 0.05% to 5% of the sum of the mass of the aromatic diamine and aromatic dianhydride.

[0056] The polyimide-polyamic acid solution is a mixed solution of a second polyamic acid solution and polyimide, or a copolymer solution of polyimide-polyamic acid, wherein the second polyamic acid solution is prepared by a polycondensation reaction of a second aromatic dianhydride and a second aromatic diamine in a solvent in which nanofillers are dispersed. This application does not limit the specific conditions of the above-mentioned polycondensation reaction; reference can be made to the preparation method of the first polyamic acid solution.

[0057] In the method provided in this application, the second aromatic dianhydride may be selected from at least one of the following: pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA), 2,2',3,3'-biphenyltetracarboxylic dianhydride (a-BPDA), 4,4'-diphenyl ether dianhydride (ODPA), 3,4,3',4'-triphenyl diether dianhydride (HQDPA), diphenyl diether dianhydride (BzDPA), 4,4'-(hexafluoroisopropene) phthalic anhydride (6FDA), 2,2-diphenylpropane-3,4,3',4'-tetracarboxylic dianhydride (PDPA), p-phenylene-bisphenyltrilate dianhydride (TAHQ), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), and 3,3',4,4'-diphenyl sulfone tetracarboxylic dianhydride (DSDA).

[0058] In the method provided in this application, the second aromatic diamine may be selected from 4,4'-diaminodiphenyl ether (4,4'-ODA), 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), 4,4'-diaminodiphenylmethane (MDA), 2,2-bis(4-aminophenyl)propane (IDPA), 1,3-bis(3-aminophenoxy)benzene (1,3,3-APB), 1,4-bis(4-aminophenoxy)benzene (1,4,4-APB), 2,4'-diaminodiphenylmethane (DPA), etc. At least one of the following: aminotoluene (DAT), 1,3-bis(aminopropane)tetramethyldisiloxane (GAPDS), 9,9-bis(4-aminophenyl)fluorene (BAPF), 4,4'-bis(4-aminophenoxy)biphenyl (BAPB), 4,4'-biphenyldiamine (Bz), 2,6-diamino-9H-fluorene-9-one (DAFT), and 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane (HFBAPP).

[0059] This application does not limit the molar ratio of the second aromatic diamine and the second aromatic dianhydride. In one embodiment, the molar ratio of the second aromatic diamine and the second aromatic dianhydride is 1:0.995 to 1:1.02.

[0060] The polyimide may be selected from any of the following sources: in one embodiment, the polyimide is a thermoplastic polyimide (e.g., commercially available TPI powder); in another embodiment, the polyimide is prepared by reacting a second polyamic acid solution with a tertiary amine compound under heating conditions. Under heating conditions, the second polyamic acid solution may undergo a cyclization dehydration reaction catalyzed by the tertiary amine compound to generate polyimide. The tertiary amine compound is selected from at least one of quinoline, isoquinoline, pyridine, 3-methylpyridine, triethylamine, and N-methylimidazole.

[0061] A copolymer solution of polyimide and polyamic acid can be prepared by reacting a second polyamic acid solution with a tertiary amine compound under heating conditions. Under heating conditions, the second polyamic acid solution undergoes a partial cyclization and dehydration reaction catalyzed by the tertiary amine compound to generate polyimide. The tertiary amine compound is selected from at least one of quinoline, isoquinoline, pyridine, 3-methylpyridine, triethylamine, and N-methylimidazole.

[0062] In the method provided in this application, by reducing the solid content of the adhesive solution, the thickness and weight of the "curtain" formed by the adhesive solution casting are increased, which helps to improve the solvent content inside the cast adhesive film. In some embodiments, the solid content of the first polyamic acid solution and the polyimide-polyamic acid solution can be 8%-12%. The lower solid content of the first polyamic acid solution and the polyimide-polyamic acid solution can increase the thickness and weight of the "curtain" extruded from the mixture formed by the first polyamic acid solution during casting. This can eliminate the influence of airflow on the "curtain" disturbance in the casting area, thereby helping to avoid problems such as film surface wrinkles or damage of the formed film, and further optimizing the quality of the obtained polyimide film.

[0063] The solid content refers to the proportion of the sum of the masses of aromatic diamines and aromatic dianhydrides in the first polyamic acid solution and the polyimide-polyamic acid solution to the total mass of the precursor solution. For example, when the precursor solution is the first polyamic acid solution, the solid content of the first polyamic acid solution is 8%-12%. When the precursor solution includes both the first polyamic acid solution and the polyimide-polyamic acid solution, the solid content of both the first polyamic acid solution and the polyimide-polyamic acid solution is 8%-12%. The mixing ratio of the first polyamic acid solution and the polyimide-polyamic acid solution is arbitrary by mass.

[0064] For the first polyamic acid solution, a solid content of 8%-12% can be achieved through the following two methods:

[0065] Method 1: A first polyamic acid solution with a solid content of 8%-12% is directly prepared by polycondensation reaction of a first aromatic dianhydride and a first aromatic diamine in a solvent in which nanofillers are dispersed. The viscosity of the solution prepared by the above method is 5000 cP to 200000 cP.

[0066] Method 2: Using Method 1, a high-viscosity solution with a solid content of 15%-30% and a viscosity of 100,000 cP to 1,000,000 cP is prepared. The solution is then diluted with a solvent to obtain a first polyamic acid solution with a solid content of 8%-12% and a viscosity of 5,000 cP to 200,000 cP.

[0067] For polyimide-polyamic acid solutions, a solid content of 8%-12% can be achieved through the following two methods:

[0068] Method 1: First, a second polyamic acid solution with a solid content of 8% to 12% is prepared by polycondensation of the second aromatic dianhydride and the second aromatic diamine in a solvent in which nanofillers are dispersed. Then, an organic amine compound (such as a tertiary amine compound) is added and heated to react, so that part of the polyamic acid is converted into polyimide, and a PAA-PI solution with a solid content of 8% to 12% is obtained.

[0069] Method 2: Mix the above-mentioned second polyamic acid solution with a solid content of 8%–12% with a polyimide solution. The polyimide solution can be sourced from any of the following: First, dissolve commercially available TPI powder in a solvent to prepare a soluble polyimide solution with a solid content of 8%–12%. The solvent is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, acetone, butanone, tetrahydrofuran, chlorobenzene, and m-cresol. Second, add an organic amine compound (such as a tertiary amine compound) to the above-mentioned second polyamic acid solution with a solid content of 8%–12%, and heat to completely convert the polyamic acid in the second polyamic acid solution into polyimide, obtaining a polyimide solution with a solid content of 8%–12% and a viscosity of 5000 cP–200000 cP. Mixing this solution with a second polyamic acid solution containing 8% to 12% yields a polyimide-polyamic acid solution with a solid content of 8% to 12%.

[0070] In the embodiments of this application, during the preparation of the above-mentioned polyamic acid-polyimide solution, the amount of organic amine compound added can be 10% to 150% of the total molar amount of the aromatic dianhydride or aromatic diamine used.

[0071] As shown above, the polyimide included in the polyimide-polyamic acid solution can be prepared by reacting a second polyamic acid solution with an organic amine compound (such as a tertiary amine compound) under heating conditions. In this case, the amount of the tertiary amine compound added can be controlled to be 10% to 150% of the total molar amount of the second aromatic dianhydride or second aromatic diamine in the second polyamic acid solution; the heating time is 180 min to 360 min; and the heating temperature is 80℃ to 200℃. These reaction conditions allow the polyamic acid included in the second polyamic acid solution to have a higher polyimide conversion rate. It is worth noting that although the second aromatic dianhydride or second aromatic diamine forms the second polyamic acid solution through a condensation reaction, the above description still uses the amount of the organic amine compound added as a reference for determining the amount of the second aromatic dianhydride or second aromatic diamine required to form the second polyamic acid solution.

[0072] Furthermore, among the related technologies, the mainstream manufacturing processes for FCCL mainly include the PI film surface coating copper cladding method and the PI film surface copper plating method. However, in the industrial manufacturing process of PI film, its imidization process (especially the high-temperature imidization process) is prone to forming a weak boundary layer on the film surface, resulting in a generally low surface tension of the finished PI film, usually in the range of 30-35 dyn / cm, which cannot meet the manufacturing requirements of FCCL. For example, when a PI film with low surface tension forms a metal layer on the PI film surface through copper cladding processes such as coating copper cladding or copper plating, it affects the uniform and firm bonding between the metal layer and the PI film, thereby affecting the quality of the final product and the reliability of long-term use. To overcome this application limitation, industrial applications primarily employ surface corona treatment or surface plasma treatment to modify the surface of PI films. These methods can improve the surface tension of PI films to some extent. They are simple to operate and highly efficient, and have been widely used for the mass production of PI film rolls. However, on the one hand, these methods have limitations in improving the surface tension of PI films. On the other hand, both the ozone generated during corona discharge and the high-energy plasma generated during surface plasma treatment can damage the surface polyimide molecular structure of the PI film, degrading its mechanical properties to varying degrees. This is especially true for thin PI films with a thickness less than 12.5 μm, where existing surface treatment methods severely degrade their mechanical properties. Furthermore, industrially manufactured thin PI films inevitably contain foreign impurities (such as metal powder and carbon particles) introduced during the manufacturing process. When thin PI films undergo corona or plasma treatment, these foreign points are easily broken down, forming larger micropore defects. Meanwhile, the surface tension of PI films treated with corona or plasma is unstable and will gradually decline as the storage time of PI films increases (commonly known as "aging failure"), which brings great inconvenience to product quality management and downstream applications.

[0073] To further overcome this problem, in some embodiments of this application, the above-mentioned adhesive also includes a silane coupling agent having a compound with the structure shown in Formula I.

[0074] Wherein, R1 is selected from C1-C6 alkyl groups, -O-R5, -HN-R6, -HN-R7-Ph, or -Ph, wherein R5, R6, and R7 are each independently selected from C1-C9 alkyl groups, and Ph represents phenyl; the formula I is connected between R2 and R3. This indicates that R2 and R3 are independent of each other or connected to each other; and R2 and R3 are each independently selected from -H, C1-C5 alkyl, C7-C12 alkylphenyl, C2-C5 alkenyl, C2-C5 alkynyl, C2-C5 ester, halogen, C1-C5 haloalkyl, C2-C5 cyano; R4 is selected from C1-C10 alkyl.

[0075] By introducing the aforementioned silane coupling agent into the polyimide film, the surface tension and surface tension stability of the polyimide film can be improved, achieving a long-term increase in the surface tension of the polyimide film. The reason for this is that the aforementioned silane coupling agent has a chain structure as shown in Formula I. One end of its molecular chain is a siloxane group, and the other end contains functional groups such as carbonyl, amide, ester, olefin, and alkane groups. The two ends are connected by a n-propyl group. After mixing this silane coupling agent with the precursor solution used to form the polyimide film, a film is formed. In the formed polyimide film (or modified PI film), based on the siloxane group in the silane coupling agent shown in Formula I... The hydrolysis and cross-linking reactions of the polyimide group involve covalent bonding with the carboxyl groups in the uncyclized ammonium acid units. Simultaneously, polar groups such as carbonyl and amide groups readily bind to the polyimide molecules through hydrogen bonding. Based on these combined effects, the polyimide group can be uniformly embedded in the interior and surface of the modified PI film. The exposed carbonyl, amide, ester, olefin, and alkane functional groups on the surface increase the surface polarity and wettability of the polyimide film, thereby improving the surface tension and its long-term stability and uniformity. This results in a uniform and firm bond between the modified PI film and the metal layer material.

[0076] Therefore, in this application, the aforementioned silane coupling agent is suitable for polyimide films. By introducing the silane coupling agent having the structure shown in Formula I into the polyimide film, the surface tension of the polyimide film can be increased, which helps the metal layer to bond uniformly and firmly with the polyimide film, thereby improving the quality and reliability of downstream products (such as FCCL and FPCB). At the same time, introducing the aforementioned silane coupling agent into the polyimide film, while increasing the surface tension of the polyimide film, also maintains a low degree of defect and good mechanical properties of the polyimide film. Specifically, the polyimide film possesses both high tensile strength and elongation.

[0077] In the embodiments of this application, the silane coupling agent is as shown in Formula I. In Formula I, R2 and R3 can be independent of each other. In this case, the silane coupling agent shown in Formula I has the structure shown in Formula I-1. Alternatively, R2 and R3 can be connected to each other to form a ring structure (e.g., a three-membered ring, a five-membered ring, etc.). That is, the silane coupling agent shown in Formula I has the structure shown in Formula I-2.

[0078] It is understood that when the silane coupling agent has the structure shown in Formula I-1, R2 and R3 are each independently monovalent groups, specifically selected from -H, C1-C5 alkyl, C7-C12 alkylphenyl, C2-C5 alkenyl, C2-C5 alkyne, C2-C5 ester, halogen, C1-C5 haloalkyl, and C2-C5 cyano. Among them, C7-C12 alkylphenyl can be selected from -R7-Ph, where R7 is selected from C1-C6 alkyl and Ph represents phenyl.

[0079] When the silane coupling agent has the structure shown in Formula I-2, R2 and R3 are each independently a divalent group, specifically selected from C1-C5 alkyl groups or C1-C5 haloalkyl groups.

[0080] According to further research by the inventors, when the silane coupling agent has the structure shown in Formula I-1, it is more helpful to improve the surface tension and surface tension stability of the polyimide film, while maintaining the high mechanical properties of the polyimide film.

[0081] In the embodiments of this application, the alkyl groups of C1-C6 can have 1, 2, 3, 4, 5, or 6 carbon atoms, and can be straight-chain alkyl groups or branched isomeric alkyl groups. The alkyl groups of C1-C9 can have 1, 2, 3, 4, 5, 6, 7, 8, or 9 carbon atoms, and can be straight-chain alkyl groups or branched isomeric alkyl groups. The alkyl groups of C1-C10 can have 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 carbon atoms, and can be straight-chain alkyl groups or branched isomeric alkyl groups. The alkyl groups of C1-C5 can have 1, 2, 3, 4, or 5 carbon atoms, and can be straight-chain alkyl groups or branched isomeric alkyl groups. The olefinic groups of C2-C5 contain at least one C=C double bond, and can have 2, 3, 4, or 5 carbon atoms, and can be branched or unbranched. The C2-C5 alkyne group contains at least one C≡C triple bond, and its carbon number can be 2, 3, 4, or 5; it may or may not be branched. The C2-C5 ester group has 2, 3, 4, or 5 carbon atoms, and it may or may not be branched. The C2-C5 cyano group contains a cyano group (-CN), and its carbon number can be 2, 3, 4, or 5; it may or may not be branched. The halogen can be selected from iodine (I), bromine (Br), or chlorine (Cl).

[0082] According to the inventors' research, in Formula I, the R1 group serves as an end group on one side of the silane coupling agent molecular chain. Different R1 groups result in different chain lengths or substituents in the silane coupling agent molecular structure shown in Formula I, leading to different solubility and dispersibility of the silane coupling agent in the adhesive used to form the PI film. This affects the distribution of the silane coupling agent shown in Formula I in the modified PI film and its interaction with polyimide (PI), thereby affecting the surface tension and other properties of the modified PI film. Further considering these factors comprehensively, in some practical applications… In the example, R1 is selected from -CH3, -CH2CH2CH3, -C(CH3)3, -CH2(CH2)4CH3, OCH2CH3, -OCH2(CH2)3CH3, -OCH2(CH2)7CH3, -HNCH3, -HNCH2CH3, -HN(CH3)2, -N(CH3)CH2Ph ​​or -Ph, which helps the silane coupling agent to have a more suitable molecular chain structure, and further improves the effect of the silane coupling agent on improving the surface tension and other properties of polyimide films.

[0083] Furthermore, in the silane coupling agent molecular structure system shown in Formula I, R2 and R3 are attached to the carbon atoms between the carbonyl and amide groups in Formula I. Different R2 and R3 groups not only affect the polarity of the silane coupling agent but also the steric hindrance of the silane coupling agent molecular structure. This is also an important factor affecting the bonding state between the silane coupling agent and polyimide. Based on the aforementioned selection range of R2 and R3, further screening for more suitable groups helps to further improve the effect of the silane coupling agent on the surface tension and other properties of the polyimide film. Based on this, in some preferred embodiments, when R2 and R3 are independent of each other (i.e., the silane coupling agent has the structure shown in Formula I-1), R2 and R3 is independently selected from H, -CH3, -CH2CH3, -CH2Ph, -CH2CH=CH2, -CH2(CH2)2CH=CH2, -CH2C≡CH, -CH2(CH2)2C≡CH, -CH2CH2OOCCH3, I, Br, Cl, -CH2CN, -CH2CH2CN or -CH2(CH2)2CN. When R2 and R3 are connected to each other (i.e. the silane coupling agent has the structure shown in Formula I-2), R2 and R3 are independently selected from -CH2-, -CHBr- or -CH2CH2-, which helps to further improve the surface tension and other properties of the polyimide film introduced with the silane coupling agent.

[0084] Furthermore, in the silane coupling agent molecular structure shown in Formula I, R4 is a C1-C10 alkyl group, which is attached to the siloxane group to form a siloxane group. That is, Formula I uses a siloxane group as the end group on the other side of the silane coupling agent molecular chain. This end group has three siloxane groups. Through hydrolysis and cross-linking reactions, the silane coupling agent is uniformly anchored inside and on the surface of the polyimide film, thereby improving the surface tension, surface tension stability, durability, and other properties of the polyimide film with the siloxane coupling agent introduced.

[0085] It should be noted that, in Formula I, although the alkyl groups in the three alkoxy groups are all represented by R4, these R4 groups can be the same alkyl group or different alkyl groups.

[0086] To further avoid the complexity of silane coupling agent synthesis and low activity of hydrolysis reaction caused by the introduction of the three alkoxy groups in Formula I, which in turn affects the performance of silane coupling agents when applied to polyimide films, in some preferred embodiments, R4 is selected from -CH3, -CH2CH3 or -CH2(CH2)6CH3, which helps to further improve the surface tension and surface tension stability of polyimide films incorporating the siloxane coupling agent.

[0087] The preparation method of the silane coupling agent in this application embodiment may include the following steps: reacting the compound shown in Formula A with the compound shown in Formula B to obtain a silane coupling agent having the structure shown in Formula I.

[0088] In formula A, X is selected from -NH, O or S, and R0 is selected from -H or C1-C4 alkyl groups, wherein the number of carbon atoms of the C1-C4 alkyl group is, for example, 1, 2, 3 or 4.

[0089] In some specific embodiments, when R0 in formula A is selected from C1-C4 alkyl groups, it can be specifically selected from -CH3, -CH2CH3, or -C(CH3)3.

[0090] It is understandable that R1, R2, and R3 in Formula I are introduced from the compound shown in Formula A, and R1, R2, and R3 in Formula A are the same as R1, R2, and R3 in Formula I, respectively; R4 in Formula I is introduced from the compound shown in Formula B, and R4 in Formula B is the same as R4 in Formula I, which will not be repeated here.

[0091] In the above preparation process, the reaction equation for the preparation of the silane coupling agent of formula I by reacting the compound of formula A with the compound of formula B through the first reaction is shown below:

[0092] For example, the obtained silane coupling agent has the structure shown in Formula I-1, and the compound shown in Formula A is the compound shown in Formula A-1. The reaction equation for the preparation of the silane coupling agent shown in Formula I-1 by the compound shown in Formula A-1 and the compound shown in Formula B through the first reaction is shown below:

[0093] Furthermore, the molar ratio of the compound shown in Formula A to the compound shown in Formula B can be 1:1 to 1:1.1.

[0094] Furthermore, the first reaction can be carried out in the presence of a first solvent, which may include one or more of toluene, xylene, chlorobenzene, chloroform, N,N-dimethylformamide, tetrahydrofuran, ethanol, and N-methylpyrrolidone.

[0095] In some embodiments, the temperature of the first reaction is 20°C to 150°C, for example, a range of 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C or any combination thereof, which is beneficial to improving the preparation efficiency of silane coupling agents while also reducing energy consumption.

[0096] Specifically, the first reaction can be carried out under reflux, and the temperature of the first reaction is higher than the boiling point of the first solvent used, so that the first reaction is carried out under reflux.

[0097] In practice, the compound shown in Formula A and the compound shown in Formula B can be mixed in a first solvent and then a first reaction can be carried out, such as a reflux reaction. After the first reaction is completed, the first solvent in the first reaction system is evaporated, and the crude product obtained is purified by column chromatography or other methods to obtain the silane coupling agent.

[0098] Specifically, the compound shown in Formula B is γ-aminopropyltrialkoxysilane, which may include γ-aminopropyltriethoxysilane.

[0099] In some embodiments, the compound shown in Formula D can be used directly as the compound shown in Formula A, and reacted with the compound shown in Formula B to obtain a silane coupling agent having the structure shown in Formula I-1. In this case, R2 and R3 in Formula I-1 are each independently -H.

[0100] R1, X, and R0 in Equation A all come from Equation D. R1, X, and R0 in Equation D are the same as R1, X, and R0 in Equation A, respectively, and will not be repeated here.

[0101] In some specific embodiments, the compound shown in Formula D may include one or more of ethyl acetoacetate, ethyl benzoyl acetate, ethyl butyrylate, etc.

[0102] In other embodiments, the compound shown in Formula A can be obtained by reacting the compound shown in Formula D with a halohydrocarbon compound. That is, the preparation process of the compound shown in Formula A includes: subjecting the compound shown in Formula D to a second reaction with a halohydrocarbon compound to obtain the compound shown in Formula A.

[0103] Among them, haloalkanes include compounds shown in formula E-1 and / or compounds shown in formula E-2:

[0104] Y1-R 21 E-1

[0105] Y2-R 22 -Y2 Formula E-2

[0106] Wherein, Y1 is selected from halogen or Y2 is selected from halogens. Specifically, the halogen can be Cl, Br, or I.

[0107] Among them, R 21 Similar to R2 or R3 in equation A-1, R 22 For equation A A group that is missing one hydrogen atom; for example, when compound A is the compound shown in formula A-1, R 22It is a group formed by R2 or R3 in formula A-1 with one less hydrogen element.

[0108] Specifically, when the halohydrocarbon compound is selected from the compound shown in Formula E-1 and / or the compound shown in Formula E-2, the compound shown in Formula A can be the compound shown in Formula A-1, thereby obtaining the silane coupling agent shown in Formula I-1.

[0109] Specifically, the compound shown in formula E-1 may include Y 11 -R2 and / or Y 12 -R3, Y 11 Y 12 Each is independently selected from halogens, specifically from Cl, Br, or I, Y. 11 With Y 12 R2 and R3 can be the same or different. R2 and R3 in the compound shown in formula A-1 are derived from R in the compound shown in formula E-1. 21 (R2, R3).

[0110] Specifically, the compound shown in Formula E-1 may include haloalkanes, such as iodomethane.

[0111] Furthermore, the compound shown in formula E-2 may include Y 21 -R'2-Y 22 and / or Y 22 -R'3-Y 22 Y 21 Y 22 Each is independently selected from halogens, specifically from Cl, Br, or I, Y. 21 With Y 22 They can be the same or different, R'2 and R'3 can be the same or different, and R2 and R3 in the compound shown in formula A-1 come from R in the compound shown in formula E-2. 22 (R'2, R'3).

[0112] In some specific embodiments, the halohydrocarbon compound may include Y 11 -R2、Y 12 -R3、Y 21 -R'2-Y2、Z 21 One or more of -R'3-Z2, wherein Y 11 Y 12 Y 21 Y 22 Each is independently selected from halogens, R'2 is a group formed by R2 in formula A-1 with one less hydrogen element, and R3 is a group formed by R3 in formula A-1 with one less hydrogen element.

[0113] Specifically, the amount of R2 (or R3) introduced into the compound of formula A-1 can be controlled by controlling the molar ratio of the compound shown in formula D to the halohydrocarbon compound (formula E-1, formula E-2). For example, when the molar ratio of the compound shown in formula D to the halohydrocarbon compound is approximately 1:1, in the compound of formula A-1, one of R2 and R3 is -H and the other is a substituent introduced through formula E-1 or formula E-2. When the molar ratio of the compound shown in formula D to the halohydrocarbon compound is approximately 1:2, in the compound of formula A-1, both R2 and R3 are substituents introduced through formula E-1 or formula E-2.

[0114] In some embodiments, the molar ratio of compound D to haloalkanes can be 1:1 to 1:2.2.

[0115] Specifically, the molar ratio of the compound shown in Formula D to the compound shown in Formula E-1 can be 1:1 to 1:2.2.

[0116] Specifically, the molar ratio of the compound shown in Formula D to the compound shown in Formula E-2 can be 1:1 to 1:2.2.

[0117] In the above preparation process, the reaction equation for the synthesis of compound A from compound D and compound E-1 via a second reaction is shown below:

[0118] In the above preparation process, the reaction equation for the synthesis of compound A from compound D and compound E-2 via a second reaction is shown below:

[0119] In some specific embodiments, when Y1 in E-1 is selected from... When the compound shown in Formula E-1 may include one or more of N-chlorosuccinimide (NCS), N-bromosuccinimide (NBS), and N-iodosuccinimide (NIS).

[0120] In the embodiments of this application, unless otherwise specified, the compounds shown in Formula B, Formula D, and the haloalkanes shown in Formula E-1 and Formula E-2 can all be obtained by conventional methods, such as commercial purchases, or self-made by conventional methods based on conventional chemical reaction principles, and there are no special restrictions on this.

[0121] In some embodiments, the temperature of the second reaction is 20°C to 80°C, for example, a range of 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C or any combination thereof, which is beneficial to improve reaction efficiency while also reducing energy consumption.

[0122] In some embodiments, the second reaction may be carried out under the action of a base. The base may include inorganic bases and / or organic bases. Inorganic bases may include one or more of carbonates, bicarbonates, metal hydroxides, and sulfates. Organic bases may include triethylamine and / or 1,8-diazabicyclo[5.4.0]undec-7-ene.

[0123] The carbonates may include alkali metal carbonates, specifically potassium carbonate and / or sodium carbonate; the bicarbonates may include alkali metal bicarbonates, specifically sodium bicarbonate; the metal hydroxides may include alkali metal hydroxides, specifically sodium hydroxide and / or potassium hydroxide; and the sulfates may include alkali metal sulfates, specifically sodium sulfate.

[0124] In some specific embodiments, the above-mentioned base may include one or more of potassium carbonate, sodium carbonate, sodium bicarbonate, triethylamine, 1,8-diazabicyclo[5.4.0]undec-7-ene, sodium hydroxide, potassium hydroxide, and sodium sulfate.

[0125] Furthermore, the second reaction can be carried out in the presence of a second solvent, which includes one or more of N,N-dimethylformamide, ethyl acetate, acetone, tetrahydrofuran, ethanol, N-methylpyrrolidone, and dichloromethane.

[0126] In practice, the compound shown in formula D, the halogenated hydrocarbon compound, and the base can be added to the second solvent, and then the second reaction can be carried out under stirring. After the second reaction is completed, the solvent is evaporated, and then organic solvents such as chloroform are added to the system for extraction. Then, the system is filtered and the organic solvent is evaporated to obtain the crude product. The crude product is then purified by column chromatography and other methods to obtain the compound shown in formula A.

[0127] Generally, a gel solution can be prepared by mixing a precursor solution containing a precursor, a chemical imidizing reagent solution, and a silane coupling agent solution containing a silane coupling agent.

[0128] For example, the above-mentioned adhesive solution can be a mixture of the above-mentioned precursor solution, silane coupling agent solution and chemical imidizing agent solution. For instance, the adhesive solution can be a mixture of the first polyamic acid solution, silane coupling agent solution and chemical imidizing agent solution, or a mixture of the polyamic acid-polyimide solution, silane coupling agent solution and chemical imidizing agent solution, or a mixture of the first polyamic acid solution, polyamic acid-polyimide solution, silane coupling agent solution and chemical imidizing agent solution.

[0129] Specifically, the solvent in the adhesive solution comes from the solvent in the aforementioned precursor solution, the solvent in the silane coupling agent solution, and the solvent in the chemical imidizing reagent solution. The solvents in these solutions may be the same or different.

[0130] In some embodiments, the mass concentration of the silane coupling agent in the silane coupling agent solution can be from 5% to 100%, for example, a range of 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, or any combination thereof. It is understood that when the mass concentration of the silane coupling agent in the silane coupling agent solution is 100%, the silane coupling agent solution consists entirely of silane coupling agent and contains no solvent.

[0131] Specifically, the silane coupling agent solution can be prepared by mixing a silane coupling agent with a solvent. The solvent used can include organic solvents, specifically amide solvents and / or pyrrolidone solvents. The amide solvents can include N,N-dimethylformamide and / or N,N-dimethylacetamide, and the pyrrolidone solvents can include N-methylpyrrolidone. For example, the solvent used includes one or more of N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone.

[0132] In this application, the imidizing agent is used to react the polyamic acid contained in the adhesive solution to generate polyimide. This application does not limit the composition of the chemical imidizing agent; conventional chemical imidizing agents in the art can be used.

[0133] It is worth noting that the chemical imidizing agent contained in the adhesive (i.e., the chemical imidizing agent used to perform mixed chemical imidization of the adhesive) can be the same as or different from the chemical imidizing agent used to perform the wetting chemical imidization treatment.

[0134] In this embodiment of the application, the process of performing mixed chemical imidization treatment on the adhesive includes: mixing the precursor liquid with a chemical imidizing reagent solution (first chemical imidizing reagent solution) for mixed chemical imidization treatment (as shown in Figure 1), or mixing the precursor liquid, silane coupling agent solution, and first chemical imidizing reagent solution for chemical imidization treatment (as shown in Figure 2).

[0135] Specifically, as shown in Figures 1 and 2, the precursor liquid (such as the first polyamic acid solution and / or polyamic acid-polyimide solution) can be degassed using conventional methods, and then mixed with the first chemical imidizing reagent solution (as shown in Figure 1), or with the first chemical imidizing reagent solution and silane coupling agent solution (as shown in Figure 2) in the mixer 101. The resulting adhesive solution is extruded through the extrusion die 102 to form a "curtain" of a certain width (the width can be 200mm to 2000mm). The "curtain" flows onto the heated drive roller 103 on the surface and is heated and cured while rolling with the drive roller 103 to remove the solvent and form an adhesive film. When the adhesive film moves to the peeling point, it is peeled off from the drive roller 103. Specifically, it can be peeled off by conventional methods such as manual traction peeling. The peeled adhesive film (i.e., the initial adhesive film) HGF continues to be pulled by the guide roller for subsequent processing such as impregnation chemical imidization treatment.

[0136] In this embodiment, the drive roller 103 can be cylindrical, such as a heating cylinder, heating drum, or other conventional drive roller structure, and there are no particular limitations on this.

[0137] Furthermore, the mass ratio of the precursor solution to the first imidizing reagent solution in the adhesive solution can be controlled to be (10:1) to (1:1). Specifically, when the precursor solution in the adhesive solution only includes the first polyamic acid solution, the mass ratio of the first polyamic acid solution to the first imidizing reagent solution is (10:1) to (1:1); when the precursor solution in the adhesive solution only includes the polyimide-polyamic acid solution, the mass ratio of the polyimide-polyamic acid solution to the first imidizing reagent solution is (10:1) to (1:1); when the precursor solution in the adhesive solution includes both the first polyamic acid solution and the polyimide-polyamic acid solution, the mass ratio of the sum of the masses of the first polyamic acid solution and the polyimide-polyamic acid solution to the mass ratio of the first imidizing reagent solution is (10:1) to (1:1). These mass ratios allow the resulting polyimide film to have higher tensile strength.

[0138] The adhesive solution undergoes a series of treatments, including chemical imidization, casting (extruded onto the surface of the support component via an extrusion die), and then heat curing. During the heat curing process, the initial adhesive film formed by the cast adhesive solution is heated, causing some of the solvent to evaporate, resulting in an initial adhesive film (HGF). The initial adhesive film is then peeled off from the support component and undergoes at least one immersion chemical imidization treatment and solvent elution treatment to obtain an intermediate adhesive film (SGF). The intermediate adhesive film is further subjected to biaxial stretching and high-temperature treatment to obtain a polyimide film.

[0139] Specifically, the heat curing treatment temperature can be 60℃-120℃, such as 60℃, 70℃, 80℃, 90℃, 100℃, 110℃, 120℃, or any combination thereof, and the treatment time is 15s-60s, such as 15s-20s or 30s-60s. Under this temperature condition, it is conducive to the effective cyclization of polyamic acid molecules in the adhesive film, improving the tensile strength and other mechanical properties of the adhesive film after peeling, while maintaining a high solvent content in the adhesive film, reducing the adhesion strength between the adhesive film and the surface of the drive roller 3, making it easier to peel the adhesive film from the drive roller 3, and further helping to solve the problem of difficult peeling.

[0140] In this application, the heating curing temperature is the heating temperature of the adhesive liquid cast onto the drive roller 103, which is also the heating temperature of the drive roller 3. The heating curing time refers to the contact time between the adhesive liquid cast onto the heating roller 103 and the heating roller 103. The heating time can be controlled by conventional methods such as adjusting the rotation speed of the drive roller 103.

[0141] In existing technologies, the manufacturing of ultrathin polyimide films suffers from bottlenecks, including the ease with which the "curtain flow" formed by the adhesive liquid casting is disturbed by air, leading to wrinkles and damage on the film surface, difficulty in peeling, and easy tearing during high-temperature stretching. The reasons for this may be: firstly, the amount of adhesive liquid extruded from the die per unit time during the production of ultrathin polyimide films is small, resulting in a thinner and lighter curtain flow; secondly, the solvent content in the "thin" film formed by the adhesive liquid casting is low, making it prone to excessive evaporation in existing heating and devolatilization devices; thirdly, the methods for controlling the solvent content of the film are limited; and finally, the film has low tensile strength and poor toughness. Therefore, the existing technology for preparing ultrathin polyimide films exhibits the aforementioned defects.

[0142] In the process of manufacturing the polyimide film using the above-described method, the adhesive film (including the initial adhesive film and the intermediate adhesive film) exhibits characteristics such as being resistant to breakage, easy to peel off, and not easily torn under high-temperature stretching. The reasons for this are as follows: First, the low solid content of the casting adhesive ensures that the "curtain" formed by the casting is not affected by surrounding airflow, avoiding the problems of "wrinkles" and "holes." Second, the high solvent content of the adhesive combined with a rationally designed heating and curing time and temperature effectively controls the high solvent content within the adhesive film, thereby reducing the adhesion strength between the adhesive film and the substrate surface and solving the problem of difficult peeling. Furthermore, the design of the polyimide-polyamic acid in the adhesive and the rapid chemical imidization of polyamic acid or the rapid chemical imidization of polyimide-polyamic acid... Imidization yields polyimide-polyamic acid with a high imide ring ratio, thereby improving the tensile strength of the initial film. Then, the initial film undergoes further tensile strength enhancement through wetting chemical imidization. Finally, solvent elution treatment of the film treated with wetting chemical imidization effectively controls the solvent content within the film to a reasonable level. In summary, the resulting intermediate film possesses both strength and toughness, solving the problems of tearing and film breakage during biaxial stretching and high-temperature treatment. This facilitates precise control of the condensed-state structure of molecules within the film, enabling the manufacture of polyimide films with high dimensional stability. Therefore, the polyimide film preparation method provided in this application achieves the technical effects of a film that is not easily damaged during manufacturing, is easy to peel off, and is not easily torn during high-temperature stretching.

[0143] In the entire manufacturing process, the chemical imidization treatment can be performed twice or more, including mixed imidization of the precursor liquid and the first chemical imidizing reagent solution (e.g., mixed imidization of the first polyamic acid solution and the first chemical imidizing reagent solution, or mixed imidization of the polyimide-polyamic acid solution and the first chemical imidizing reagent solution, or mixed imidization of the polyimide-polyamic acid solution, the polyimide-polyamic acid solution and the first chemical imidizing reagent solution, or mixed imidization of the precursor liquid, the silane coupling agent solution and the first chemical imidizing reagent solvent), and at least one immersion imidization of the initial film with the second chemical imidizing reagent solution.

[0144] In this embodiment of the application, when the initial film is subjected to at least one immersion chemical imidization treatment, during each immersion chemical imidization treatment, the initial film comes into contact with and is immersed in the chemical imidization reagent solution to perform the chemical imidization treatment. The chemical imidization reagent solution used for each immersion chemical imidization treatment may be the same or different.

[0145] It is worth noting that, as mentioned earlier, the chemical imidizing agent contained in the adhesive solution can be the same as or different from the chemical imidizing agent used to perform the impregnation chemical imidization treatment. When the impregnation chemical imidization treatment includes a first impregnation chemical imidization treatment and a second impregnation chemical imidization treatment performed sequentially, the chemical imidizing agents used in the first and second impregnation chemical imidization treatments can also be the same or different. For ease of distinction, the chemical imidizing agent solution contained in the adhesive solution is referred to as the first chemical imidizing agent solution, the chemical imidizing agent solution used to perform the first impregnation chemical imidization treatment is referred to as the second chemical imidizing agent solution, and the chemical imidizing agent solution used to perform the second impregnation chemical imidization treatment is referred to as the third chemical imidizing agent solution. The third chemical imidizing agent solution and the second chemical imidizing agent solution can be the same or different. When they are the same, it is assumed that the second chemical imidizing agent solution is used for all impregnation chemical imidization treatments.

[0146] More specifically, to further increase the tensile strength of the polyimide film, in one embodiment, the immersion chemical imidization treatment includes sequentially subjecting the product (initial film) obtained from the heat curing treatment to a first immersion chemical imidization treatment and a second immersion chemical imidization treatment; that is, after immersing the initial film in a second chemical imidizing reagent solution for the first immersion chemical imidization treatment, it is then immersed in a third chemical imidizing reagent solution for the second immersion chemical imidization treatment. Through two consecutive immersion chemical imidization treatments, the efficiency of the chemical imidization reaction of the initial film is improved, the proportion of imide rings in the film is increased, thereby further improving the tensile strength and other mechanical properties of the formed intermediate film, facilitating subsequent stretching and other processing, and improving the mechanical properties of the resulting polyimide film.

[0147] Specifically, the processing temperature of the first immersion chemical imidization treatment can be 45℃-100℃, for example, 45℃, 50℃, 60℃, 70℃, 80℃, 90℃, 100℃ or any combination thereof, and the processing time is 5s-40s, for example, 5s, 10s, 20s, 25s, 30s, 35s, 40s or any combination thereof.

[0148] Furthermore, the second impregnation chemical imidization treatment is carried out at a temperature of 45°C-150°C, for example, 80°C-150°C, or 45°C-100°C, for example, 45°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, or any combination thereof, and for a treatment time of 5s-40s, for example, 5s, 10s, 20s, 25s, 30s, 35s, 40s, or any combination thereof. The above treatment temperature and time can further increase the proportion of imide rings in the film, thereby improving the tensile strength of the obtained polyimide film.

[0149] To further improve the tensile strength of the polyimide film, in one embodiment, the chemical imidizing reagent solutions used in each of the above-mentioned treatment processes may independently include a dehydrating agent, a catalyst, a solvent, and an additive. The dehydrating agent is selected from at least one of acetic anhydride, trifluoroacetic anhydride, benzoic anhydride, acetyl chloride, and thionyl chloride; the catalyst is selected from at least one of quinoline, isoquinoline, pyridine, 3-methylpyridine, triethylamine, and N-methylimidazole; the solvent is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; and the additive is selected from at least one of tricresyl phosphate, triphenyl phosphate, diphenyltoluene phosphate, and trioctyl trimellitate. The imidizing reagents described above can further increase the proportion of imide rings in the film, thereby improving the tensile strength of the film.

[0150] In the preparation process of the above-mentioned polyimide film, solvent extraction and elution of the initial film after impregnation chemical imidization treatment helps to regulate the condensed state structure of molecules in the film, while improving the strength and toughness of the film. This avoids problems such as tearing and film breakage during subsequent biaxial stretching and high-temperature treatment, thereby improving the preparation efficiency of polyimide film and the performance of the obtained polyimide film.

[0151] Solvent elution involves contacting the chemically imidized film with a solvent to obtain an intermediate film. This application does not limit the specific number of chemical imidization treatments or the specific conditions, nor does it limit the processing time and temperature of the solvent elution process; as long as the above requirements are met, it is acceptable.

[0152] In some embodiments, the solvent used in the solvent elution process may include one or more of the following: acetone, butanone, ethyl acetate, tetrahydrofuran, chloroform, n-hexane, petroleum ether, m-cresol, dimethyl urea, dimethyl sulfoxide, toluene, xylene, etc.

[0153] To further address the issue of tearing and breakage of the adhesive film during biaxial stretching and high-temperature processing, and to facilitate the manufacture of high-dimensionally stable polyimide films, an intermediate adhesive film with controllable solvent content is produced. The solvent elution treatment temperature is 10℃-30℃, for example, 10℃, 15℃, 20℃, 25℃, 30℃, or any combination thereof, and the treatment time is 5s-40s, for example, 5s-20s or 20s-40s, for example, 20s, 25s, 30s, 35s, 40s, or any combination thereof. These treatment conditions effectively control the solvent content within the adhesive film, allowing the film to balance strength and toughness, thus preventing tearing and breakage during biaxial stretching and high-temperature processing, resulting in a high-dimensionally stable polyimide film.

[0154] In this embodiment, the time for the first immersion chemical imidization treatment, the time for the second immersion chemical imidization treatment, and the time for the solvent elution treatment refer to the residence time of the film in the corresponding reactor or container. Specifically, the time of these treatment processes can be controlled by conventional methods such as adjusting the rotation speed of the drive roller 103. This application can adjust the rotation speed of the drive roller 103 in a conventional manner, and there are no special limitations on this.

[0155] Biaxial stretching at high temperatures can also be performed using conditions commonly used in the field. For example, the film is longitudinally stretched at room temperature or under heating conditions (e.g., 80°C to 150°C), and then transversely stretched and cooled within the range of 80°C to 600°C (e.g., 150°C to 600°C) to obtain a polyimide film. In this case, the intermediate film is stretched simultaneously with the high-temperature treatment during the transverse stretching process to obtain the polyimide film.

[0156] The longitudinal stretching ratio can be 1:(1-1.1), and the stretching temperature can be 25℃~150℃, such as room temperature or 80℃~150℃.

[0157] During the biaxial stretching process described above, one or more transverse stretching operations can be performed. For example, three transverse stretching operations can be performed sequentially, with a stretching ratio of 1:(1-1.2) for each transverse stretching operation. The stretching temperature is 80℃~600℃, for example, 150℃~600℃ or 80℃~450℃.

[0158] In this embodiment, the intermediate film can be biaxially stretched using a conventional biaxial stretching process, and the stretching ratio and temperature of the longitudinal and transverse stretching can be controlled using conventional methods, without any particular limitations.

[0159] In specific implementation, as shown in Figures 1 and 2, after the adhesive film is peeled off from the drive roller 103, the initial adhesive film HGF formed moves forward under the traction of the first guide roller 104, the second guide roller 105, the third guide roller 106, the fourth guide roller 107, the fifth guide roller 108, the sixth guide roller 109, the seventh guide roller 110, the eighth guide roller 111, the ninth guide roller 112, and the tenth guide roller 113, and is sequentially introduced into the first chemical imidization reaction vessel 201 containing the second chemical imidization reagent solution, and the second chemical imidization reaction vessel 202 containing the second chemical imidization reagent solution. An imidization reaction vessel 202 and an elution vessel 203 containing a solvent for solvent elution are used. The initial film HGF undergoes a first immersion chemical imidization treatment when flowing through the first chemical imidization reaction vessel 201, a second immersion chemical imidization treatment when flowing through the second chemical imidization reaction vessel 202, and a solvent elution treatment when flowing through the elution vessel 203. The intermediate film SGF after solvent elution is drawn by the tenth guide roller 113 and undergoes subsequent biaxial stretching and other processes to obtain a polyimide film.

[0160] Referring again to Figures 1 and 2, the second guide roller 105 and the third guide roller 106 are disposed in the first chemical imidization reaction vessel 201, specifically at the bottom of the first chemical imidization reaction vessel 201, so as to facilitate the immersion of the film flowing through the first chemical imidization reaction vessel 201 in the second chemical imidization reagent solution for the first immersion chemical imidization treatment; the fifth guide roller 108 and the sixth guide roller 109 are disposed in the second chemical imidization reaction vessel 202, specifically at the bottom of the second chemical imidization reaction vessel 202, so as to facilitate the immersion of the film flowing through the second chemical imidization reaction vessel 202 in the third chemical imidization reagent solution for the second immersion chemical imidization treatment; the eighth guide roller 111 and the ninth guide roller 112 are disposed in the elution vessel 203, specifically at the bottom of the elution vessel 203, so as to facilitate the immersion of the film flowing through the elution vessel 203 in the sixth solvent for solvent elution treatment. The fourth guide roller 107, the seventh guide roller 110, and the tenth guide roller 113 are located outside the above-mentioned reaction vessel (or reagent tank) and elution vessel, and serve to pull the film.

[0161] This application does not limit the driving and driven relationship between the guide rollers 10, and can be set as needed. For example, the first guide roller 104, the fourth guide roller 107, the seventh guide roller 110, and the tenth guide roller 113 are driving guide rollers 10, and the second guide roller 105, the third guide roller 106, the fifth guide roller 108, the sixth guide roller 109, the eighth guide roller 111, and the ninth guide roller 112 are driven guide rollers 10.

[0162] In this embodiment, the chemical imidization reaction vessel can be an independent chemical imidization reagent immersion tank (or immersion reaction tank), and the elution vessel can be a solvent elution tank. These reaction vessels or tanks can be stainless steel containers, and the guide roller 10 can be a stainless steel guide roller 10, but is not limited thereto.

[0163] In this embodiment, the required PI film thickness can be obtained by adjusting the amount of precursor. The amount of precursor can be adjusted by conventional operation, and there are no special limitations on this.

[0164] In this embodiment, the precursor fluid, silane coupling agent solution, and first chemical imidizing reagent solution can be pumped into mixer 1 by an output pump, and the amount of these solutions can be controlled by adjusting the pumping speed (pump rate) using conventional methods, without any particular limitation.

[0165] This application also provides a polyimide film, which is prepared using any of the above-described methods for preparing polyimide films. Since the polyimide film is not easily torn during high-temperature stretching, it can be processed to a lower thickness.

[0166] Specifically, in one embodiment, the thickness of the polyimide film is 3.5 μm to 12.5 μm, for example, a range of 3.5 μm, 5 μm, 7 μm, 9 μm, 11 μm, 12.5 μm or any combination thereof.

[0167] The thickness of the polyimide film can be measured by conventional methods, such as by referring to the testing methods in GB / T 6672-2001 "Mechanical Measurement Method for Determination of Thickness of Plastic Films and Sheets", or by using the CHY-CA mechanical contact thickness gauge from China Saicheng Instruments.

[0168] In this application, the polyimide film prepared by the above-mentioned method can be applied to circuit boards and other applications.

[0169] This application also provides a laminated structure, including a polyimide film and a metal layer laminated with the polyimide film; wherein the polyimide film includes the aforementioned polyimide film or a polyimide film prepared according to the aforementioned method for preparing polyimide films. This laminated structure has advantages corresponding to the aforementioned polyimide film, which will not be elaborated further.

[0170] In some embodiments, the metal layer includes a copper layer.

[0171] In this embodiment of the application, the aforementioned stacked structure can be a flexible copper clad laminate (FCCL) or a flexible printed circuit board (FPCB), but is not limited to these.

[0172] In the embodiments of this application, a metal layer such as a copper layer can be formed on the polyimide film using conventional processes, such as conventional copper coating or copper plating on the PI film surface. Generally, no particular limitation is made in this regard.

[0173] This application also provides an electronic product including the aforementioned laminated structure. This electronic product has advantages corresponding to the aforementioned polyimide film, which will not be elaborated further.

[0174] In this embodiment, the type of electronic product is not limited; it can be any conventional electronic product to which the above-mentioned laminated structure is applicable, such as consumer electronics products like mobile phones, automobiles, aircraft, and other equipment.

[0175] This application also provides a polyimide film production apparatus for performing the above-described polyimide film preparation method. Figures 1 and 2 are schematic diagrams of the polyimide film production apparatus according to an embodiment of this application. As shown in Figures 1 and 2, the apparatus includes a mixer 101, an extrusion die 102, a heating drive roller 103, a first chemical imidization reaction vessel 201, a second chemical imidization reaction vessel 202, and a solvent elution vessel 203. The three vessels can be rectangular stainless steel containers.

[0176] As shown in Figure 1, mixer 101 mixes the first polyamic acid solution, chemical imidization solution, and polyimide-polyamic acid solution (if any) and pumps them into extrusion die 102. As shown in Figure 2, mixer 101 mixes the first polyamic acid solution, chemical imidization solution, polyimide-polyamic acid solution (if any), and silane coupling agent solution and pumps them into extrusion die 102. Extrusion die 102 is positioned opposite to heating drive roller 103, allowing the extruded adhesive from extrusion die 102 to contact the heating drive roller 103 as it falls under gravity. The heating drive roller 103 rotates counterclockwise upon contact, catching the adhesive extruded from extrusion die 102 and simultaneously heating and curing the catching adhesive. Controlling the heating temperature and rotation speed of the heating drive roller 103 controls the curing temperature and time. When the adhesive film reaches the peeling point, peeling drive roller (e.g., heated drum) 103 is used; the peeling method can be manual traction peeling. After the adhesive solution is heated and cured, an initial adhesive film HGF is obtained. The initial adhesive film HGF is peeled off from the surface of the heated drive roller 103 and sequentially enters the first chemical imidization reaction vessel 201, the second chemical imidization reaction vessel 202, and the solvent elution vessel 203. The first chemical imidization reaction vessel 201 and the second chemical imidization reaction vessel 202 contain the same or different chemical imidization reagent solutions, and the solvent elution vessel 203 contains solvent for solvent elution. All three vessels are equipped with heating devices. HGF is immersed in the contents of the first chemical imidization reaction vessel 201 for the first immersion chemical imidization treatment, immersed in the contents of the second chemical imidization reaction vessel 202 for the second immersion chemical imidization treatment, and immersed in the contents of the solvent elution vessel 203 for solvent elution treatment, yielding an intermediate adhesive film SGF. Controlling the running speed of the HGF and the temperature of the contents of the three vessels controls the processing time and temperature of the first immersion chemical imidization treatment, the second immersion chemical imidization treatment, and the solvent elution treatment. The intermediate film is further subjected to biaxial stretching and high-temperature treatment (the corresponding treatment equipment is common in the field and is not shown in Figures 1 and 2) to obtain a polyimide film.

[0177] The polyimide film production apparatus provided in this application uses a single heated drive roller design to replace the traditional annular steel belt design, which can reduce the complexity of equipment design and manufacturing costs, shorten the distance and time for film drying and devolatilization, reduce production energy consumption and improve production efficiency, and achieve the technical effect that the film is not easily damaged, easy to peel off and not easily torn under high temperature stretching during the manufacturing process.

[0178] Furthermore, in order to prolong the residence time of HGF in the first chemical imidization reaction vessel 201, the second chemical imidization reaction vessel 202, and the solvent elution vessel 203, in one embodiment, at least two guide rollers are provided in each of the first chemical imidization reaction vessel 201, the second chemical imidization reaction vessel 202, and the solvent elution vessel 203, so that the initial film can sequentially contact the contents in the first chemical imidization reaction vessel 201, the second chemical imidization reaction vessel 202, and the solvent elution vessel 203.

[0179] Specifically, as shown in Figures 1 and 2, the polyimide film production apparatus further includes a first guide roller 104, a second guide roller 105, a third guide roller 106, a fourth guide roller 107, a fifth guide roller 108, a sixth guide roller 109, a seventh guide roller 110, an eighth guide roller 111, a ninth guide roller 112, and a tenth guide roller 113. The second guide roller 105 and the third guide roller 106 are disposed in the first chemical imidization reaction vessel 201; the fifth guide roller 108 and the sixth guide roller 109 are disposed in the second chemical imidization reaction vessel 202; and the eighth guide roller 111 and the ninth guide roller 112 are disposed in the solvent elution vessel 203. These rollers can be, for example, stainless steel guide rollers disposed at the bottom of the vessel. This arrangement allows the initial film to be immersed in the three vessels and in contact with the contents for appropriate processing. The fourth guide roller 107, the seventh guide roller 110, and the tenth guide roller 113 are disposed outside the vessels, serving to transfer the initial film to different vessels. This application does not limit the driving and driven relationship of the first to tenth guide rollers, and can be set as needed. For example, in one embodiment, the fourth guide roller 107, the seventh guide roller 110, and the tenth guide roller 113 are driving guide rollers.

[0180] More specifically, in one embodiment, the width of the adhesive extruded by the extrusion die 102 can be controlled to be 200mm-2000mm. Adhesive with the above width can be more evenly distributed on the surface of the heating drive roller 103, resulting in a more uniform texture in the initial adhesive film.

[0181] This application also proposes a tensile strength standard for HGF as shown in Table 1, which demonstrates the relationship between the specifications of HGF and the tensile strength of the final polyimide film. This tensile strength was obtained using an Instron 68SC-05 universal tensile testing machine.

[0182] Table 1

[0183] This application also provides the solvent content of SGF and the tensile strength standard of SGF as shown in Table 2:

[0184] Table 2

[0185] The solvent content of SGF is calculated as follows: [(Total weight of SGF before high-temperature treatment - Weight of SGF after high-temperature treatment) / Weight of SGF after high-temperature treatment] × 100%; the weight of SGF after high-temperature treatment is the weight after heating SGF at 450℃ for 2 hours; the tensile strength of SGF is determined using an Instron 68SC-05 universal tensile testing machine. For example, to obtain a polyimide film with a diameter of 12.5 μm, the solvent content of SGF needs to be controlled between 40% and 70%, and the tensile strength needs to be controlled between 70 MPa and 100 MPa.

[0186] The present application will be further described below through specific embodiments.

[0187] Examples 1 to 15, Comparative Examples 1 to 5

[0188] Example 1

[0189] 1) Under nitrogen protection, add 11220.7g NMP to a 20L reactor and start stirring; weigh 26g of dicalcium phosphate and add it to the reactor, stirring and dispersing for 20min; weigh 373.2g ODA and 201.5g PDA and add them to the reactor, stirring at room temperature for 30min; weigh 405.1g PMDA and 545.9g s-BPDA and slowly add them to the reactor sequentially; stir for 300min to obtain a PAA solution with a solid content of 12% and a viscosity of 1595p; after degassing, freeze and store at -10℃ for later use. This PAA solution is the first polyamic acid solution.

[0190] 2) Under nitrogen protection, 1025g NMP, 2217g acetic anhydride, 858g pyridine, and 275g triphenyl phosphate were added sequentially to a 5L reactor and stirred for 180min to obtain the first chemical imidizing reagent solution, which was then frozen and stored at -10℃ for later use.

[0191] 3) Under nitrogen protection, 8750g NMP, 24050g acetic anhydride, and 11000g 3-methylpyridine were added sequentially to a 50L reactor and stirred for 180min to obtain the second chemical imidizing reagent solution.

[0192] Prepare 40,000g of the second chemical imidizing reagent solution according to this method, and transfer the second chemical imidizing reagent solution to the first imidization reaction vessel and the second imidization reaction vessel respectively, and store them at room temperature for later use.

[0193] 4) Add 40,000 g of n-hexane to the solvent elution container and store at room temperature for later use.

[0194] 5) Set the pump speed of the first polyamic acid solution output pump to 50 g / min, the pump speed of the first chemical imidizing reagent solution output pump to 15 g / min, the stirring speed of the mixer to 300 rpm, the vertical distance between the extrusion die and the heating drive roller to 10 mm, the heating temperature of the heating drive roller to 80℃ (i.e., the processing temperature of the heat curing treatment), the temperature of the imidizing reagent in the first and second imidizing reaction containers to 60℃ (i.e., the processing temperature of the first and second impregnation chemical imidization treatments), and the temperature of the solvent in the solvent elution container to 25℃ (i.e., the processing temperature of the solvent elution treatment); turn on the equipment, control the rotation speed of the heating drive roller, so that the processing time of the heat curing treatment is 45 s, the processing time of the first and second impregnation chemical imidization treatments is 30 s each, and the processing time of the solvent elution treatment is 30 s. The first polyamic acid solution and the chemical imidizing reagent solution are simultaneously pumped into the mixer and mixed. The mixed solution then enters the extrusion die. The mixed solution extruded from the extrusion die forms a yellow transparent "curtain" and falls onto the surface of the heated drive roller to form a film. The film is heated by the heated drive roller to remove some of the solvent and is peeled off at the peeling point to obtain the initial film (HGF-1). The initial film (HGF-1) is drawn by the guide roller and sequentially immersed in the first imidization reaction vessel, the second imidization reaction vessel, and the solvent elution vessel to obtain the intermediate film (SGF-1). The intermediate film (SGF-1) is then subjected to biaxial stretching and high-temperature treatment to obtain a high-performance ultrathin PI film UHPI-1 with a thickness of 7.5 μm.

[0195] Example 2

[0196] 1) Under nitrogen protection, 10456.7g of NMP was added to a 25L reactor and stirring was started. 36g of dicalcium phosphate was weighed and added to the reactor, and the mixture was stirred and dispersed for 20 minutes. 559.8g of ODA and 302.3g of PDA were weighed and added to the reactor, and the mixture was stirred at room temperature for 30 minutes. 610.2g of PMDA and 822.9g of s-BPDA were weighed and slowly added to the reactor sequentially. The mixture was stirred for 300 minutes to obtain a PAA solution with a solid content of 18% and a viscosity of 8935p. 6375g of NMP was slowly added to the reactor, and stirring was continued for 120 minutes to obtain a PAA solution with a solid content of 12% and a viscosity of 1250p. After degassing, the solution was frozen at -10℃ for later use. This PAA solution is the first polyamic acid solution.

[0197] 2) The first chemical imidizing reagent solution, the second chemical imidizing reagent solution, and the solvent in the solvent elution container are the same as in Example 1.

[0198] 3) HGF-2 and SGF-2 were manufactured according to the method of Example 1. SGF-2 was then subjected to biaxial stretching and high-temperature treatment to obtain a high-performance ultrathin PI film UHPI-2 with a thickness of 7.5 μm. In the biaxial stretching and high-temperature treatment process, the film was first stretched at a longitudinal stretching ratio of 1:1.01 and a temperature of 100°C, then stretched sequentially at a transverse stretching ratio of 1:1.01 and a temperature of 300°C, then at a transverse stretching ratio of 1:1.02 and a temperature of 350°C, and finally at a transverse stretching ratio of 1:1.03 and a temperature of 400°C to obtain the ultrathin PI film UHPI-2.

[0199] Example 3

[0200] 1) Under nitrogen protection, add 15990g NMP to a 35L reactor and start stirring; weigh 52g of dicalcium phosphate and add it to the reactor, stirring and dispersing for 20min; weigh 578g ODA and 1186.3g BAPP and add them to the reactor, stirring at room temperature for 30min; weigh 895.9g ODPA and 849.7g s-BPDA and slowly add them to the reactor sequentially; stir for 300min to obtain a PAA solution with a solid content of 18% and a viscosity of 9330p; slowly add 9750g NMP to the reactor and continue stirring for 180min to obtain a PAA solution with a solid content of 12% and a viscosity of 1071p; then add 373g isoquinoline, stir for 10min, raise the temperature to 120℃, continue stirring and reacting for 30min, stop heating, degas the mixed solution, and freeze it at -10℃ for later use. This solution is the polyimide-polyamic acid solution.

[0201] 2) Under nitrogen protection, 5520g NMP, 3381.6g acetic anhydride, 2138.4g isoquinoline and 555g triphenyl phosphate were added sequentially to a 15L reactor and stirred for 180min to obtain the first chemical imidizing reagent solution, which was then frozen and stored at -10℃ for later use.

[0202] 3) The solvent in the second chemical imidization reagent solution and the film solvent elution tank is the same as in Example 1.

[0203] 4) HGF-3 and SGF-3 were manufactured according to the method of Example 1. SGF-3 was then subjected to biaxial stretching and high temperature treatment to obtain a high-performance ultrathin PI film UHPI-3 with a thickness of 7.5 μm.

[0204] Example 4

[0205] 1) The PAA solution, the first chemical imidizing reagent solution, the second chemical imidizing reagent solution, and the solvent in the solvent elution container are the same as in Example 1;

[0206] 2) Increase the amount of mixed solution extruded per unit time by the die head proportionally, and use the same method as in Example 1 to produce HGF-4 and SGF-4. SGF-4 is then subjected to biaxial stretching and high temperature treatment to obtain a high-performance ultrathin PI film UHPI-4 with a thickness of 10μm.

[0207] Example 5

[0208] 1) The PAA solution, the first chemical imidizing reagent solution, the second chemical imidizing reagent solution, and the solvent in the solvent elution container are the same as in Example 1;

[0209] 2) Increase the amount of mixed solution extruded per unit time by the die head proportionally, and use the same method as in Example 1 to produce HGF-5 and SGF-5. SGF-5 is then subjected to biaxial stretching and high temperature treatment to obtain a high-performance ultrathin PI film UHPI-5 with a thickness of 12.5μm.

[0210] Example 6

[0211] 1) Under nitrogen protection, 15033.3g of NMP was added to a 35L reactor and stirring was started; 50g of dicalcium phosphate was weighed and added to the reactor, and the mixture was stirred and dispersed for 30min; 345.2g of ODA and 745.6g of PDA were weighed and added to the reactor and stirred at room temperature for 30min; 940.6g of PMDA and 1268.6g of s-BPDA were weighed and slowly added to the reactor sequentially; the mixture was stirred for 300min to obtain a PAA solution with a solid content of 18% and a viscosity of 12679p; 14466.7g of NMP was slowly added to the reactor and stirring was continued for 120min to obtain a PAA solution with a solid content of 10% and a viscosity of 995p. After degassing, the solution was frozen at -10℃ for later use. This PAA solution is the first polyamic acid solution. The first chemical imidizing reagent solution, the second chemical imidizing reagent solution, and the solvent in the solvent elution vessel were the same as in Example 1.

[0212] 2) HGF-6 and SGF-6 were manufactured according to the method of Example 1. SGF-6 was then subjected to biaxial stretching and high temperature treatment to obtain a high-performance ultrathin PI film UHPI-6 with a thickness of 5μm.

[0213] Example 7

[0214] 1) Under nitrogen protection, 13666.7g of NMP was added to a 40L reactor and stirring was started; 50g of dicalcium phosphate was weighed and added to the reactor, and the mixture was stirred and dispersed for 30min; 307.7g of ODA and 664.6g of PDA were weighed and added to the reactor and stirred at room temperature for 30min; 670.8g of PMDA and 1356.9g of s-BPDA were weighed and slowly added to the reactor sequentially; the mixture was stirred for 300min to obtain a PAA solution with a solid content of 18% and a viscosity of 18130P; 20833.3g of NMP was slowly added to the reactor and stirring was continued for 120min to obtain a PAA solution with a solid content of 8% and a viscosity of 632P. After degassing, the solution was frozen and stored at -10℃ for later use. This PAA solution is the first polyamic acid solution. The first chemical imidizing reagent solution, the second chemical imidizing reagent solution, and the solvent in the film solvent washing tank were the same as in Example 1.

[0215] 2) HGF-7 and SGF-7 were manufactured according to the method of Example 1. SGF-7 was then subjected to biaxial stretching and high temperature treatment to obtain a high-performance ultrathin PI film UHPI-7 with a thickness of 3.5 μm.

[0216] Example 8

[0217] 1) The PAA solution, the first chemical imidizing reagent solution, the second chemical imidizing reagent solution, and the solvent in the solvent elution container are the same as in Example 1.

[0218] 2) HGF-8 and SGF-8 were manufactured according to the method of Example 1, except that HGF-8 was only processed in the first imidization reaction vessel, that is, only the first imidization treatment was performed to obtain SGF-8. SGF-8 was then subjected to biaxial stretching and high temperature treatment to obtain a high-performance ultrathin PI film UHPI-8 with a thickness of 7.5 μm.

[0219] Example 9

[0220] 1) Under nitrogen protection, 15944.4g of NMP was added to a 30L reactor and stirring was started; 52g of dicalcium phosphate was weighed and added to the reactor, and the mixture was stirred and dispersed for 20min; 1255.1g of ODA and 290.5g of PDA were weighed and added to the reactor and stirred at room temperature for 30min; 1954.4g of PMDA was weighed and slowly added to the reactor sequentially; the mixture was stirred for 300min to obtain a PAA solution with a solid content of 18% and a viscosity of 10431p; 9722.2g of NMP was slowly added to the reactor and stirring was continued for 120min to obtain a PAA solution with a solid content of 12% and a viscosity of 763p. After degassing, the solution was frozen at -10℃ for later use. This PAA solution is the first polyamic acid solution. The first chemical imidizing reagent solution, the second chemical imidizing reagent solution, and the solvent in the solvent elution vessel were the same as in Example 1.

[0221] 2) HGF-9 and SGF-9 were manufactured according to the method in Example 1. SGF-9 was then subjected to biaxial stretching and high temperature treatment to obtain a high-performance ultrathin PI film UHPI-9 with a thickness of 7.5 μm.

[0222] Example 10

[0223] 1) Under nitrogen protection, 10456.7g of NMP was added to a 25L reactor and stirring was started; 36g of dicalcium phosphate was weighed and added to the reactor, and the mixture was stirred and dispersed for 20min; 559.8g of ODA and 302.3g of PDA were weighed and added to the reactor and stirred at room temperature for 30min; 608.2g of PMDA and 820.3g of s-BPDA were weighed and slowly added to the reactor sequentially; the mixture was stirred for 300min to obtain a PAA solution with a solid content of 18% and a viscosity of 1926p. After degassing, the solution was frozen and stored at -10℃ for later use. This PAA solution is the first polyamic acid solution. The first chemical imidizing reagent solution, the second chemical imidizing reagent solution, and the solvent in the solvent elution vessel were the same as in Example 1.

[0224] 2) HGF-10 and SGF-10 were manufactured according to the method of Example 1. SGF-10 was then subjected to biaxial stretching and high temperature treatment to obtain a high-performance ultrathin PI film UHPI-10 with a thickness of 25μm.

[0225] Example 11

[0226] 1) The PAA solution was prepared in the same manner as in Example 10, and the solvents in the solvent elution containers for the first chemical imidizing reagent solution and the second chemical imidizing reagent solution were the same as in Example 1.

[0227] 2) HGF-11 and SGF-11 were manufactured according to the method of Example 1. SGF-11 was then subjected to biaxial stretching and high temperature treatment to obtain a high-performance ultrathin PI film UHPI-11 with a thickness of 50 μm.

[0228] Example 12

[0229] 1) The PAA solution was prepared in the same manner as in Example 10, and the first chemical imidizing reagent solution, the second chemical imidizing reagent solution, and the solvent in the solvent elution container were the same as in Example 1.

[0230] 2) The temperature of the heating cylinder is designed to be 100℃. After the cast adhesive forms a film on the surface of the heating cylinder, it is heated and cured, and then peeled off to obtain HGF-12. SGF-12 is manufactured according to the method of Example 1. SGF-12 is then subjected to biaxial stretching and high temperature treatment to obtain a high-performance ultra-thin PI film UHPI-12 with a thickness of 7.5μm.

[0231] Example 13

[0232] 1) The PAA solution was prepared in the same manner as in Example 10, and the solvents in the solvent elution containers for the first chemical imidizing reagent solution and the second chemical imidizing reagent solution were the same as in Example 1.

[0233] 2) The temperature of the heating cylinder is designed to be 120℃. After the cast adhesive forms a film on the surface of the heating cylinder, it is heated and cured, and then peeled off to obtain HGF-13. SGF-13 is manufactured according to the method of Example 1. SGF-13 is then subjected to biaxial stretching and high temperature treatment to obtain a high-performance ultrathin PI film UHPI-13 with a thickness of 7.5μm.

[0234] Example 14

[0235] 1) The PAA solution was prepared in the same manner as in Example 10, and the first chemical imidizing reagent solution, the second chemical imidizing reagent solution, and the solvent in the solvent elution container were the same as in Example 1.

[0236] 2) The temperature of both the first chemical imidization reaction vessel and the second chemical imidization reaction vessel was set to 100°C; HGF-14 and SGF-14 were manufactured according to the method of Example 1, and SGF-14 was then subjected to biaxial stretching and high temperature treatment to obtain a high-performance ultrathin PI film UHPI-14 with a thickness of 7.5 μm.

[0237] Example 15

[0238] 3) The PAA solution was prepared in the same manner as in Example 10, and the first chemical imidizing reagent solution, the second chemical imidizing reagent solution, and the solvent in the solvent elution container were the same as in Example 1.

[0239] 4) The temperatures of the first chemical imidization reaction vessel and the second chemical imidization reaction vessel were set to 100°C and 120°C, respectively; HGF-15 and SGF-15 were manufactured according to the method of Example 1, and SGF-15 was then subjected to biaxial stretching and high temperature treatment to obtain a high-performance ultrathin PI film UHPI-15 with a thickness of 7.5 μm.

[0240] Comparative Example 1

[0241] 1) Under nitrogen protection, 10456.7g of NMP was added to a 25L reactor and stirring was started; 50g of dicalcium phosphate was weighed and added to the reactor, and the mixture was stirred and dispersed for 20min; 559.8g of ODA and 302.3g of PDA were weighed and added to the reactor and stirred at room temperature for 30min; 607.2g of PMDA and 819.3g of s-BPDA were weighed and slowly added to the reactor sequentially; the mixture was stirred for 300min to obtain a PAA solution with a solid content of 18% and a viscosity of 1356p. The solvents in the solvent elution vessels for the first and second chemical imidizing reagent solutions were the same as in Example 1.

[0242] 2) HGF-12 was manufactured according to the method of Example 1, but the surface of HGF-12 had wrinkles and holes, and HGF-12 could not be completely peeled off from the surface of the heating roller, making it impossible to manufacture stably.

[0243] Comparative Example 2

[0244] 1) The solvents in the solvent elution containers of PAA solution, first chemical imidizing reagent solution, and second chemical imidizing reagent solution are the same as in Example 1.

[0245] 2) HGF-13 and SGF-13 were manufactured according to the method of Example 1. HGF did not pass through the first and second imidization reaction vessels, that is, it did not undergo the first and second imidization treatments. SGF-13 tore during biaxial stretching and high-temperature treatment after being fixed by a fixture, making continuous production impossible.

[0246] Comparative Example 3

[0247] 1) The solvents in the solvent elution containers of PAA solution, first chemical imidizing reagent solution, and second chemical imidizing reagent solution are the same as in Example 1.

[0248] 2) HGF-14 and SGF-14 were manufactured according to the method of Example 1. HGF was not subjected to a solvent washing tank. SGF-14 tore during biaxial stretching and high-temperature treatment after being fixed by a fixture, making continuous production impossible.

[0249] Comparative Example 4

[0250] This comparative example does not use the equipment provided in the second aspect of this application, but uses an annular steel belt to allow the "curtain" formed by the adhesive to fall onto the surface of the annular steel belt to form a film and dry. The drying temperature is 150°C and the drying time is 45 seconds.

[0251] 1) The PAA solution, the first chemical imidizing reagent solution, the second chemical imidizing reagent solution, and the solvent in the film solvent elution tank are the same as in Example 1.

[0252] 2) The “curtain flow” falls onto the surface of the annular steel belt to form a film and dry, resulting in HGF-15, but it cannot be completely peeled off from the surface of the steel belt.

[0253] Comparative Example 5

[0254] 1) The PAA solution, the first chemical imidizing reagent solution, the second chemical imidizing reagent solution, and the solvent in the film solvent elution tank are the same as in Example 1.

[0255] 2) The temperature of the heating roller is set to 150℃. The "curtain flow" falls onto the surface of the heating roller to form a film and dry to obtain HGF-16, but it cannot be completely peeled off from the surface of the steel strip.

[0256] The properties of the samples prepared in each embodiment and comparative example were measured, and the results are shown in Table 3.

[0257] Thickness measurement method: The CHY-CA mechanical contact thickness gauge from China Saicheng Instruments was used for measurement.

[0258] Tensile strength / elongation measurement method: Tested using an Instron 68SC-05 universal tensile testing machine;

[0259] The linear coefficient of thermal expansion (CTE) was measured using a TMA450 static thermomechanical analyzer from Thermo Fisher Scientific, USA, at a heating rate of 3°C / min.

[0260] Table 3

[0261] Note: × — Unable to produce adhesive / film for testing.

[0262] As shown in Table 3, compared with the comparative examples, each embodiment can produce polyimide films with higher tensile strength and elongation. Meanwhile, the polyimide films obtained in each embodiment all have a lower coefficient of linear thermal expansion.

[0263] Examples 16 to 33, Comparative Examples 6 to 10

[0264] In the following examples, the silane coupling agents prepared in each example were subjected to 1H NMR spectroscopy (NMR spectroscopy). 1 ¹H NMR analysis revealed its corresponding molecular structure. Taking the silane coupling agent C-1 prepared in Example 16 as an example, its… 1 The HNMR spectrum is shown in Figure 3.

[0265] Example 16

[0266] 1) The molecular structure of the novel silane coupling agent C-1 is shown in formula C-1:

[0267] 2) The synthesis method of the novel silane coupling agent C-1 (hereinafter referred to as compound C-1) is as follows:

[0268] A magnetic stir bar was added to a 100ml double-necked flask, and 50ml of dry toluene was added. 5g of ethyl acetoacetate was weighed and added to the flask, along with 8.6g of γ-aminopropyltriethoxysilane. The mixture was refluxed in an oil bath for 12 hours, and then the toluene was evaporated to obtain the crude product of compound C-1. The crude product was then purified by column chromatography to obtain compound C-1.

[0269] Example 17

[0270] 1) The molecular structure of the novel silane coupling agent C-2 is shown in formula C-2:

[0271] 2) The synthesis method of the novel silane coupling agent C-2 (hereinafter referred to as compound C-2) differs from that of Example 16 in that ethyl benzoyl is used instead of ethyl acetoacetate. That is, the reaction raw materials for synthesizing compound C-2 are ethyl benzoyl and γ-aminopropyltriethoxysilane, and the molar ratio of ethyl benzoyl to γ-aminopropyltriethoxysilane is 1:1.01. The remaining steps and conditions are the same as those in Example 16.

[0272] Example 18

[0273] 1) The molecular structure of the novel silane coupling agent C-3 is shown in formula C-3:

[0274] 2) The synthesis method of the novel silane coupling agent C-3 (hereinafter referred to as compound C-3) differs from that of Example 16 in that the reaction raw materials are ethyl butyrylamide and γ-aminopropyltriethoxysilane, and the molar ratio of ethyl butyrylamide and γ-aminopropyltriethoxysilane is 1:1.01. The remaining steps and conditions are the same as those in Example 16.

[0275] Example 19

[0276] 1) The molecular structure of the novel silane coupling agent C-4 is shown in formula C-4:

[0277] 2) Synthesis of Formula D-1: A magnetic stir bar was added to a 100 ml single-necked flask, and 50 ml of N,N-dimethylformamide was added. 5 g of ethyl benzoylbenzene was weighed and added to the flask, along with 3.7 g of iodomethane and 3.6 g of potassium carbonate. The mixture was stirred at room temperature for 12 h. Then, the N,N-dimethylformamide was evaporated, followed by extraction with chloroform, filtration, and chloroform evaporation to obtain crude ethyl 2-methyl-3-phenyl-3-oxopropionate. This crude product was then purified by column chromatography to obtain ethyl 2-methyl-3-phenyl-3-oxopropionate (Formula D-1).

[0278] 3) The synthesis method of the novel silane coupling agent C-4 (hereinafter referred to as compound C-4) differs from that of Example 16 in that the reaction raw materials are ethyl 2-methyl-3-phenyl-3-oxopropionate and γ-aminopropyltriethoxysilane, and the molar ratio of ethyl 2-methyl-3-phenyl-3-oxopropionate and γ-aminopropyltriethoxysilane is 1:1.01. The remaining steps and conditions are the same as those in Example 16.

[0279] Example 20

[0280] 1) The molecular structure of the novel silane coupling agent C-5 is shown in formula C-5:

[0281] 2) Synthesis of formula D-2: A magnetic stir bar was added to a 100 ml single-necked flask, and 50 ml of N,N-dimethylformamide was added. 5 g of ethyl benzoyl was weighed and added to the flask, along with 7.4 g of iodomethane and 7.2 g of potassium carbonate. The mixture was stirred at room temperature for 12 h. Then, the N,N-dimethylformamide was evaporated, followed by extraction with chloroform, filtration, and evaporation of chloroform to obtain crude product ethyl 2,2-dimethyl-3-phenyl-3-oxopropionate. The crude product was then purified by column chromatography to obtain ethyl 2,2-dimethyl-3-phenyl-3-oxopropionate (formula D-2).

[0282] 3) The synthesis method of the novel silane coupling agent C-5 (hereinafter referred to as compound C-5) differs from that of Example 16 in that the reaction raw materials are ethyl 2,2-dimethyl-3-phenyl-3-oxopropionate and γ-aminopropyltriethoxysilane, and the molar ratio of ethyl 2,2-dimethyl-3-phenyl-3-oxopropionate and γ-aminopropyltriethoxysilane is 1:1.01. The remaining steps and conditions are the same as those in Example 16.

[0283] Example 21

[0284] 1) Under nitrogen protection, 1197g NMP and 133g compound C-1 were added sequentially to a 2L reactor and stirred for 1 hour to obtain a solution of compound C-1 for later use.

[0285] 2) Under nitrogen protection, add 11379.1g NMP to a 20L reactor and start stirring; weigh 26g of dicalcium phosphate and add it to the reactor, stirring and dispersing for 20min; weigh 373.2g ODA and 201.5g PDA and add them to the reactor, stirring at room temperature for 30min; weigh 405.1g PMDA and 545.9g s-BPDA and slowly add them to the reactor in sequence, stirring for 300min to obtain a PAA solution with a viscosity of 1595P; after degassing, freeze and store at -10℃ for later use.

[0286] 3) Under nitrogen protection, add 1025g NMP, 2217g acetic anhydride, 858g pyridine and 275g triphenyl phosphate sequentially to a 5L reactor and stir for 180min to obtain the first chemical imidizing reagent solution, which is then frozen and stored at -10℃ for later use.

[0287] 4) Under nitrogen protection, add 8750g NMP, 24050g acetic anhydride, and 11000g 3-methylpyridine sequentially to a 50L reactor and stir for 180min to obtain a chemical imidizing reagent solution. Prepare 40000g of this chemical imidizing reagent solution as the second chemical imidizing reagent solution and transfer it to the chemical imidizing reagent impregnation reaction tank (i.e., the first chemical imidizing reaction vessel 201). Prepare another 40000g of this chemical imidizing reagent solution as the third chemical imidizing reagent solution and transfer it to the chemical imidizing reagent impregnation reaction tank (i.e., the second chemical imidizing reaction vessel 202). Store at room temperature for later use.

[0288] 5) Add 40,000 g of n-hexane to the solvent elution tank and store at room temperature for later use.

[0289] As shown in Figure 2, containers containing polyamic acid solution, first chemical imidizing reagent solution, and silane coupling agent solution are respectively connected to mixer 101 via output pumps. The pump speeds are set as follows: polyamic acid solution output pump: 50 g / min; compound C-1 solution output pump: 0.3 g / min; first chemical imidizing reagent solution output pump: 15 g / min; mixer 101 stirring speed: 300 rpm; heating cylinder (drive roller 103) heating temperature (i.e., film casting temperature): 80℃; film casting... The time is 45s; the heating temperature of both the chemical imidizing reagent impregnation reaction tank (I) and the chemical imidizing reagent impregnation reaction tank (II) is 60℃ (that is, the temperature of the first and second impregnation chemical imidization treatments is 60℃); the time of the first and second impregnation chemical imidization treatments is 30s; the temperature of the solvent elution tank is 25℃ (that is, the temperature of the solvent elution treatment is 25℃); the time of the solvent elution treatment is 30s; the equipment is turned on, and the polyamic acid solution, compound C-1 solution, and the first chemical imidizing reagent solution are... The mixture is pumped into mixer 101 and then extruded into die 102. The extruded liquid forms a yellow, transparent "curtain" and falls onto the surface of the heating cylinder to form a film. The film is heated by the heating cylinder to remove some solvent and is peeled off at the peeling point to obtain the initial film HGF. The initial film HGF is drawn by guide rollers and passes through the first chemical imidization reaction vessel 201, the second chemical imidization reaction vessel 202, and the solvent elution vessel 203, undergoing the first immersion chemical imidization treatment, the second immersion chemical imidization treatment, and the solvent elution treatment in sequence to obtain the intermediate film. SGF intermediate film is then subjected to biaxial stretching and high-temperature treatment during the biaxial stretching process. Specifically, it is first stretched at a longitudinal stretching ratio of 1:1.01 and a temperature of 100℃, then stretched sequentially at a transverse stretching ratio of 1:1.01 and a temperature of 300℃, then at a transverse stretching ratio of 1:1.02 and a temperature of 350℃, and finally at a transverse stretching ratio of 1:1.03 and a temperature of 400℃, to obtain a PI film UHPI-16 with a thickness of 7.5μm, in which compound C-1 accounts for 0.5% by mass.

[0290] Example 22

[0291] The method for preparing the 7.5 μm thick PI film UHPI-17 differs from that in Example 21 in that the pumping speed of the solution output pump for compound C-1 solution is adjusted to 0.61 g / min, so that the mass percentage of compound C-1 in the PI film UHPI-17 is 1%. The remaining steps and conditions are the same as in Example 21.

[0292] Example 23

[0293] The method for preparing the 7.5 μm thick PI film UHPI-18 differs from that in Example 21 in that the pumping speed of the solution output pump for compound C-1 solution is adjusted to 1.22 g / min, so that the mass percentage of compound C-1 in the PI film UHPI-18 is 2%. The remaining steps and conditions are the same as in Example 21.

[0294] Example 24

[0295] The method for preparing the 7.5 μm thick PI film UHPI-19 differs from that in Example 21 in that the pumping speed of the solution output pump for compound C-1 solution is adjusted to 2.5 g / min, so that the mass percentage of compound C-1 in the PI film UHPI-19 is 4%. The remaining steps and conditions are the same as in Example 21.

[0296] Example 25

[0297] The method for preparing the 7.5 μm thick PI film UHPI-20 differs from that in Example 21 in that the pumping speed of the solution output pump for compound C-1 solution is adjusted to 3.16 g / min, so that the mass percentage of compound C-1 in the PI film UHPI-20 is 5%. The remaining steps and conditions are the same as in Example 21.

[0298] Example 26

[0299] The method for preparing the 7.5 μm thick PI film UHPI-21 differs from that in Example 21 in that the pumping speed of the solution output pump for compound C-1 solution is adjusted to 3.83 g / min, so that the mass percentage of compound C-1 in the PI film UHPI-21 is 6%. The remaining steps and conditions are the same as in Example 21.

[0300] Example 27

[0301] The method for preparing the 7.5 μm thick PI film UHPI-22 differs from that in Example 21 in that the pumping speed of the solution output pump for compound C-1 solution is adjusted to 5.22 g / min, so that the mass percentage of compound C-1 in the PI film UHPI-22 is 8%. The remaining steps and conditions are the same as in Example 21.

[0302] Example 28

[0303] The method for preparing the 7.5 μm thick PI film UHPI-23 differs from that in Example 21 in that compound C-1 is replaced with compound C-2, and the pumping speed of the solution output pump for compound C-2 solution is adjusted to 3.16 g / min so that the mass percentage of compound C-2 in the PI film UHPI-23 is 5%. The remaining steps and conditions are the same as in Example 21.

[0304] Example 29

[0305] The method for preparing the 7.5 μm thick PI film UHPI-24 differs from that in Example 21 in that compound C-2 is used to replace compound C-1, and the pumping speed of the solution output pump of compound C-1 is adjusted to 3.16 g / min so that the mass percentage of compound C-5 in the PI film UHPI-24 is 5%. The remaining steps and conditions are the same as in Example 21.

[0306] Example 30

[0307] The method for preparing the 5 μm thick PI film UHPI-25 differs from that in Example 28 in that the thickness of the obtained PI film UHPI-25 is 5 μm, the mass percentage of compound C-2 is 5%, and the remaining steps and conditions are the same as in Example 28.

[0308] Example 31

[0309] The difference between the preparation method of the PI film UHPI-26 with a thickness of 12.5 μm and Example 28 is that the thickness of the obtained PI film UHPI-26 is 12.5 μm, the mass ratio of compound C-2 is 5%, and the remaining steps and conditions are the same as in Example 28.

[0310] Example 32

[0311] The method for preparing the PI film UHPI-27 with a thickness of 25 μm differs from that in Example 28 in that the thickness of the obtained PI film UHPI-27 is 25 μm, the mass percentage of compound C-2 is 5%, and the remaining steps and conditions are the same as in Example 28.

[0312] Example 33

[0313] The method for preparing the 75 μm thick PI film UHPI-28 differs from that in Example 28 in that the thickness of the obtained PI film UHPI-28 is 75 μm, the mass percentage of compound C-2 is 5%, and the remaining steps and conditions are the same as in Example 28.

[0314] Example 34

[0315] UHPI-23 from Example 28 was stored at room temperature for 1 month to obtain UHPI-29, 3 months to obtain UHPI-30, 6 months to obtain UHPI-31, and 12 months to obtain UHPI-32.

[0316] Comparative Example 6

[0317] The difference between the preparation method of the 7.5 μm thick PI film UHPI-33 and Example 21 is that no silane coupling agent is used in the preparation process of the PI film UHPI-33, that is, the amount of compound C-1 added in step 1) is 0.

[0318] Comparative Example 7

[0319] The difference between the preparation method of the 7.5 μm thick PI film UHPI-34 and Example 21 is that γ-aminopropyltriethoxysilane (KH550) is used to replace compound C-1, and the mass percentage of KH550 in the PI film UHPI-34 is 5%.

[0320] Comparative Example 8

[0321] The difference between the preparation method of the 7.5 μm thick PI film UHPI-35 and Example 21 is that γ-glycidoxypropyltrimethoxysilane (KH560) is used to replace compound C-1, and the mass percentage of KH560 in the PI film UHPI-35 is 5%.

[0322] Comparative Example 9

[0323] UHPI-36 was obtained by treating the PI film UHPI-33 with a surface corona treatment method. Specifically, the surface corona treatment equipment HD1000 from Shanghai Kejia Electronics Co., Ltd. was used to perform the surface corona treatment on UHPI-33, with an output power of 500W.

[0324] Comparative Example 10

[0325] UHPI-37 was obtained by surface plasma treatment of PI film UHPI-33. Specifically, the surface plasma treatment of UHPI-33 was performed using a plasma system of model IoN100 from PVA Tepla GmbH, Germany, with oxygen as the plasma source, a flow rate of 50 sccm, and a processing power of 100 W.

[0326] Comparative Example 11

[0327] UHPI-36 in Comparative Example 9 was stored at room temperature for 1 month to obtain UHPI-38, 3 months to obtain UHPI-39, 6 months to obtain UHPI-40, and 12 months to obtain UHPI-41.

[0328] Comparative Example 12

[0329] UHPI-37 in Comparative Example 10 was stored at room temperature for 1 month to obtain UHPI-42, 3 months to obtain UHPI-43, 6 months to obtain UHPI-44, and 12 months to obtain UHPI-45.

[0330] Thickness measurement method for UHPI-16 to UHPI-45: The CHY-CA mechanical contact thickness gauge from China Saicheng Instruments was used for measurement.

[0331] The surface tension of UHPI-16 to UHPI-45 was determined according to the test method in GB / T 14216-2008 "Determination of wetting tension of plastic films and sheets".

[0332] The tensile strength and elongation of UHPI-16 to UHPI-45 were measured using an Instron 68SC-05 universal tensile testing machine.

[0333] The test results are shown in Tables 4 and 5.

[0334] Table 4

[0335] As shown in Table 4, compared to the unmodified PI film in Comparative Example 6 and the PI films modified with conventional silane coupling agents in Comparative Examples 7-8, the modification of the polyimide film by introducing a silane coupling agent with the structure shown in Formula I into the polyimide film in Examples 16-33 can improve the surface tension of the polyimide film while maintaining a low degree of defect and good mechanical properties. Specifically, compared to the PI films modified with conventional silane coupling agents in Comparative Examples 7-8, the surface tension of the PI film in Examples 25-18 can be significantly improved using the same amount of silane coupling agent.

[0336] Furthermore, compared to the corona treatment in Comparative Example 9 and the plasma treatment in Comparative Example 10, Examples 16 to 33 can improve the surface tension of the polyimide film without destroying the polyimide molecular structure in the polyimide film or amplifying the defects of the PI film. The effect is long-lasting, which can solve the problem of aging degradation. It also has the advantages of safe modification and simple operation.

[0337] Furthermore, taking the PI films of Example 28, Comparative Example 9, and Comparative Example 10 as examples, Examples 34, 11, and 12 were conducted. The surface tensions of UHPI-29, UHPI-30, UHPI-31, UHPI-32, UHPI-38, UHPI-39, UHPI-40, UHPI-41, UHPI-42, UHPI-43, UHPI-44, and UHPI-45 were measured and are shown in Table 5 to verify the surface tension stability of the PI films.

[0338] Table 5

[0339] As can be seen from Table 5, compared with the PI film modification methods of corona treatment and plasma treatment, the PI film in Example 34, by introducing a silane coupling agent with the structure shown in Formula I, can improve the stability and durability of the surface tension of the PI film and solve the problem of aging degradation.

[0340] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

A method for preparing a polyimide film, characterized in that, The process includes the following steps: sequentially performing a mixing chemical imidization treatment, a casting film formation treatment, a heat curing treatment, and a peeling treatment on the adhesive liquid used to form a polyimide film to obtain an initial adhesive film; the initial adhesive film undergoes at least one immersion chemical imidization treatment and a solvent elution treatment to obtain an intermediate adhesive film; and the intermediate adhesive film undergoes biaxial stretching treatment and high-temperature treatment to obtain the polyimide film. The method for preparing the polyimide film according to claim 1 is characterized in that, The adhesive comprises a precursor solution and a chemical imidizing agent solution. The precursor solution comprises a first polyamic acid solution and / or a polyimide-polyamic acid solution. The polyimide-polyamic acid solution is a mixture of a second polyamic acid solution and polyimide or a polyamic acid-polyimide copolymer solution. The solid content of the first polyamic acid solution and the polyimide-polyamic acid solution is 8%-12%. The method for preparing the polyimide film according to claim 2 is characterized in that, The first polyamic acid solution is prepared by polycondensation reaction of a first aromatic dianhydride and a first aromatic diamine in a solvent in which nanofillers are dispersed; And / or, the second polyamic acid solution is prepared by polycondensation of a second aromatic dianhydride and a second aromatic diamine in a solvent in which nanofillers are dispersed. The method for preparing the polyimide film according to claim 2 is characterized in that, In the adhesive solution, the mass ratio of the precursor solution to the imidizing agent is (10:1) to (1:1). The method for preparing the polyimide film according to any one of claims 1-4 is characterized in that, The heat curing process is carried out at a temperature of 60℃-120℃ for 15s-60s. The method for preparing the polyimide film according to any one of claims 1-4 is characterized in that, The impregnation chemical imidization treatment includes a first impregnation chemical imidization treatment and a second impregnation chemical imidization treatment performed sequentially on the product obtained by heat curing treatment; the first impregnation chemical imidization treatment is performed at a temperature of 45℃-100℃ for a time of 5s-40s; the second impregnation chemical imidization treatment is performed at a temperature of 45℃-150℃ for a time of 5s-40s. The method for preparing the polyimide film according to any one of claims 1-4 is characterized in that, The solvent elution process is carried out at a temperature of 10℃-30℃ for a time of 5s-40s. The method for preparing the polyimide film according to any one of claims 1-4 is characterized in that, The tensile strength of the initial adhesive film is 10 MPa to 100 MPa; And / or, the tensile strength of the intermediate film is 30 MPa to 120 MPa; And / or, the solvent content of the intermediate film is 30% to 180%. The method for preparing the polyimide film according to any one of claims 1-8 is characterized in that, The adhesive comprises a silane coupling agent, which includes a compound having the structure shown in Formula I: Formula I, wherein R1 is selected from C1-C6 alkyl groups, -O-R5, -HN-R6, -HN-R7-Ph, or -Ph, wherein R5, R6, and R7 are each independently selected from C1-C9 alkyl groups, and Ph represents phenyl; In Equation I, the connection between R2 and R3 This indicates that R2 and R3 are independent of each other or connected to each other; and R2 and R3 are each independently selected from -H, C1-C5 alkyl, C7-C12 alkylphenyl, C2-C5 alkenyl, C2-C5 alkynyl, C2-C5 ester, halogen, C1-C5 haloalkyl, and C2-C5 cyano. R4 is selected from C1-C10 alkyl groups. The method for preparing the polyimide film according to claim 8 is characterized in that, The R1 is selected from -CH3, -CH2CH2CH3, -C(CH3)3, -CH2(CH2)4CH3, OCH2CH3, -OCH2(CH2)3CH3, -OCH2(CH2)7CH3, -HNCH3, -HNCH2CH3, -HN(CH3)2, -N(CH3)CH2Ph ​​or -Ph; And / or, when R2 and R3 are independent of each other, each of R2 and R3 is independently selected from -H, -CH3, -CH2CH3, -CH2Ph, -CH2CH=CH2, -CH2(CH2)2CH=CH2, -CH2C≡CH, -CH2(CH2)2C≡CH, -CH2CH2OOCCH3, I, Br, Cl, -CH2CN, -CH2CH2CN or -CH2(CH2)2CN; when R2 and R3 are connected to each other, each of R2 and R3 is independently selected from -CH2-, -CHBr- or -CH2CH2-. And / or, the R4 is selected from -CH3, -CH2CH3, -CH2(CH2)6CH3. A polyimide film, characterized in that, It is manufactured using the method for preparing the polyimide film according to any one of claims 1-10. The polyimide film according to claim 11 is characterized in that, The polyimide film contains a silane coupling agent, which comprises a compound having the structure shown in Formula I: Formula I, wherein R1 is selected from C1-C6 alkyl groups, -O-R5, -HN-R6, -HN-R7-Ph, or -Ph, wherein R5, R6, and R7 are each independently selected from C1-C9 alkyl groups, and Ph represents phenyl; In Equation I, the connection between R2 and R3 This indicates that R2 and R3 are independent of each other or connected to each other; and R2 and R3 are each independently selected from -H, C1-C5 alkyl, C7-C12 alkylphenyl, C2-C5 alkenyl, C2-C5 alkynyl, C2-C5 ester, halogen, C1-C5 haloalkyl, and C2-C5 cyano. R4 is selected from C1-C10 alkyl groups. The polyimide film according to claim 12 is characterized in that, In the polyimide film, the mass percentage of the silane coupling agent is 1% to 20%. The polyimide film according to any one of claims 11-13 is characterized in that, The thickness of the polyimide film is 3.5 μm to 12.5 μm; And / or, the linear coefficient of thermal expansion of the polyimide film is 2ppm / ℃-20ppm / ℃; And / or, the surface tension of the polyimide film is greater than or equal to 36 dyn / cm. A laminated structural component, characterized in that, It includes a polyimide film and a metal layer stacked with the polyimide film; wherein the polyimide film includes a polyimide film prepared according to the method of preparing a polyimide film according to any one of claims 1-10 or a polyimide film according to any one of claims 11-14. The laminated structure according to claim 15 is characterized in that, The metal layer includes a copper layer. An electronic product characterized in that, Includes the laminated structure as described in claim 15 or 16. A polyimide film production apparatus for performing the method for preparing a polyimide film according to any one of claims 1-10, characterized in that, Includes a mixer, an extrusion die, a heated drive roller, a first chemical imidization reaction vessel, a second chemical imidization reaction vessel, and a solvent elution vessel; The mixer is connected to the extrusion die; the extrusion die is positioned opposite to the heating drive roller, so that the adhesive extruded by the extrusion die comes into contact with the heating drive roller to perform the heating and curing process, thereby obtaining an initial adhesive film; The first chemical imidization reaction vessel is used to perform the first immersion chemical imidization treatment; The second chemical imidization reaction vessel is used to perform the second immersion chemical imidization treatment; The solvent elution vessel is used to perform the solvent elution process. The polyimide film production apparatus according to claim 18 is characterized in that, Each of the first chemical imidization reaction vessel, the second chemical imidization reaction vessel, and the solvent elution vessel is provided with at least two guide rollers, so that the initial film comes into contact with the solvent in the first chemical imidization reaction vessel, the second chemical imidization reaction vessel, and the solvent elution vessel in sequence; And / or, the width of the adhesive liquid extruded by the extrusion die is 200mm-2000mm.

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