Multilayer composite film

Abstract

The invention relates to the technical field of films, in particular to a multi-layer composite film which is prepared from at least one layer of a polyaryletherketone material film, at least one layer of a polyimide material film and at least one layer of a bisphenol AF type polyaryletherketone material containing an imide side group or a film of the bisphenol AF type polyaryletherketone material through laminating and hot-pressing compounding. The bisphenol AF type polyaryletherketone material containing the imide side group or the film of the bisphenol AF type polyaryletherketone material is arranged between each layer of polyaryletherketone material film and each layer of polyimide material film; the multilayer composite film formed after lamination has a good interfacial compatibility effect and high peel strength, and can give full play to the advantages of polyaryletherketone and polyimide materials to the greatest extent.

Description

Technical Field

[0001] This invention relates to the field of thin film technology, and specifically to a multilayer composite thin film. Background Technology

[0002] With the rapid development of modern industrial technology, the demand for high-performance thin film materials is increasing daily. Polyaryletherketone (PAGE) films and polyimide films, with their excellent comprehensive properties, have demonstrated enormous application potential in numerous fields. PAGE films possess excellent high-temperature resistance, corrosion resistance, mechanical properties, and electrical insulation; while polyimide films excel in high-temperature resistance, electrical properties, and flame retardancy. In-depth research on these two types of films is of great significance for expanding their application scope and improving the performance and quality of related industries.

[0003] Polyaryletherketones (PEEK), such as PEEK, are semi-crystalline aromatic polyetheretherketone polymers with a unique molecular structure that allows them to maintain good physical and chemical properties even at high temperatures. Polyimides, such as PEI, are amorphous aromatic polyetherimide polymers whose imide groups in their molecular structure endow them with excellent thermal stability and mechanical properties. Existing technologies often directly blend these two materials to form composites, but the compatibility between them is poor. Melt blending often results in island-like structures, leading to a decline in the composite material's performance. Therefore, how to leverage the advantages of both films while simultaneously achieving a compatible interface is the technical problem this invention aims to solve. Summary of the Invention

[0004] To address the aforementioned technical problems, a multilayer composite film is provided. This invention involves placing at least one layer of bisphenol AF type polyarylether ketone material or its film containing imide side groups between at least one polyarylether ketone film and at least one polyimide film. The resulting multilayer composite film exhibits good interfacial compatibility, high peel strength, and maximizes the advantages of both polyarylether ketone and polyimide materials.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0006] A multilayer composite film comprising at least one layer of polyaryletherketone material film, at least one layer of polyimide material film, and at least one layer of bisphenol AF type polyaryletherketone material or film containing imide side groups, which are laminated and hot-pressed together;

[0007] The bisphenol AF type polyarylether ketone material or its film containing imide side groups is disposed between each layer of the polyarylether ketone material film and each layer of the polyimide material film;

[0008] The chemical structure of the bisphenol AF type polyarylether ketone containing an imide side group is as follows:

[0009]

[0010] Its number-average molecular weight is 10,000 to 30,000 g / mol, its weight-average molecular weight is 30,000 to 60,000 g / mol, and its PDI is in the range of 1-3.

[0011] Furthermore, the polyaryletherketone material film is selected from one or more of the following materials: polyetheretherketone (PEEK), polyetherketone (PEK), polyetherketoneketone (PEKK), polyetheretherketoneketone (PEEKK), and polyetherketoneetherketoneketone (PEKEKK).

[0012] The polyimide film is selected from one or more of polyimide (PI), polyetherimide (PEI), and polyamideimide (PAI) to form a film. The polyimide (PI) is selected from one of pyromellitic thermoplastic polyimide and biphenyl thermoplastic polyimide and is a semi-aromatic or aromatic polyimide.

[0013] Furthermore, in the multilayer composite film, the polyaryletherketone material film accounts for 5%-28% by weight, the polyimide material film accounts for 70%-90%, and the bisphenol AF type polyaryletherketone material or film containing imide side groups accounts for 1%-15%.

[0014] Furthermore, the polyaryletherketone material film comprises the following first component in 100% by weight: 90%-100% polyaryletherketone material with a melt index of 5-20 g / 10 min (test conditions 400℃, 2.16KG) and 0%-10% additives;

[0015] The polyimide film comprises the following second component in 100% by weight: 90%-100% polyimide material with a melt index of 5-20 g / 10 min (test conditions 380℃, 2.16 KG) and 0%-10% additives;

[0016] The absolute value of the difference between the melt index of the polyaryletherketone material in the first component and the melt index of the polyimide material in the second component is less than 5;

[0017] The additives include one or more of the following: metal oxide nanomaterials with a particle size of less than 100 nm, nano-silver with a particle size of less than 100 nm, titanate coupling agents (such as NDZ-201—isopropyltris(dioctyl pyrophosphoryloxy) titanate), plasticizers (such as dioctyl terephthalate DOTP, trioctyl trimellitate TOTM, tetraoctyl pyromellitic acid), and antioxidants.

[0018] The metal oxide nanomaterials are selected from one or more of nano-titanium dioxide, nano-zinc oxide, nano-alumina, and nano-indium oxide, and also serve as nucleating agents. After casting, rapid cooling increases transparency.

[0019] Preferably, in the multilayer composite film, the polyaryletherketone material film accounts for 5%-28% by weight, the polyimide material film accounts for 70%-90%, and the bisphenol AF type polyaryletherketone material or film containing imide side groups accounts for 1.5%-5%.

[0020] The polyaryletherketone material film comprises the following first component in 100% by weight: 90%-99.9% polyaryletherketone material with a melt index of 5-20 g / 10 min (test conditions 400℃, 2.16KG) and 0.1%-10% additives;

[0021] The polyimide film comprises the following second component in 100% by weight: 90%-99.9% polyimide material with a melt index of 5-20 g / 10 min (test conditions 380℃, 2.16 KG) and 0.1%-10% additives.

[0022] Furthermore, the process of obtaining the polyaryletherketone material film includes the following steps: after mixing the first component of the formulation, the mixture is melt-extruded using a twin-screw extruder, and then cast into a film;

[0023] During the melt extrusion process, the melt of the first component is devolatilized under a negative pressure in the range of -0.01MPa to -0.1MPa. The twin-screw extruder includes a feeding section, a solid conveying section, a melt plasticizing section, a mixing section, a venting section, a homogenizing section, and a die head area. Venting ports are provided in the melt plasticizing section, the mixing section, and the venting section. Each venting port is connected to a vacuum system to provide negative pressure.

[0024] When PEEK is selected, the temperature of the melting and plasticizing section is set to 360-380℃, the temperature of the mixing section is set to 370-390℃, the temperature of the venting section is set to 360-370℃, the temperature of the homogenizing section is set to 350-370℃, and the temperature of the die head area is set to 340-360℃.

[0025] When PEK is selected, the temperature of the melting and plasticizing section is set to 380-400℃, the temperature of the mixing section is set to 390-400℃, the temperature of the venting section is set to 380-390℃, the temperature of the homogenizing section is set to 370-390℃, and the temperature of the die head area is set to 365-385℃.

[0026] When PEKK is selected, the temperature of the melting and plasticizing section is set to 370-390℃, the temperature of the mixing section is set to 380-400℃, the temperature of the venting section is set to 365-375℃, the temperature of the homogenizing section is set to 360-380℃, and the temperature of the die head area is set to 350-370℃.

[0027] When PEEKK is selected, the temperature of the melting and plasticizing section is set to 365-385℃, the temperature of the mixing section is set to 375-395℃, the temperature of the venting section is set to 360-370℃, the temperature of the homogenizing section is set to 355-375℃, and the temperature of the die head area is set to 345-365℃.

[0028] When PEKEKK is selected, the temperature of the melting and plasticizing section is set to 400-420℃, the temperature of the mixing section is set to 410-430℃, the temperature of the venting section is set to 390-400℃, the temperature of the homogenizing section is set to 380-400℃, and the temperature of the die head area is set to 380-400℃. When multiple materials are selected for blending, the above parameters for individual materials can be used as a reference for optimization experiments.

[0029] The temperature of the cooling rollers used for casting is at least 10°C lower than the glass transition temperature of the selected material to reduce crystallization and form a film with high transparency.

[0030] Furthermore, the process of obtaining the polyimide material film includes the following steps: mixing the second component of the formulation and then performing melt extrusion using a twin-screw extruder, followed by casting into a film;

[0031] During the melt extrusion process, the melt of the second component is devolatilized under a negative pressure in the range of -0.01MPa to -0.1MPa. The twin-screw extruder includes a feeding section, a solid conveying section, a melt plasticizing section, a mixing section, a venting section, a homogenizing section, and a die head area. Venting ports are provided in the melt plasticizing section, the mixing section, and the venting section. Each venting port is connected to a vacuum system to provide negative pressure.

[0032] When PI is selected, the temperature of the melting and plasticizing section is set to 380-400℃, the temperature of the mixing section is set to 380-400℃, the temperature of the exhaust section is set to 380-400℃, the temperature of the homogenization section is set to 380-400℃, and the temperature of the die head area is set to 380-400℃.

[0033] When PEI is selected, the temperature of the melting and plasticizing section is set to 340-380℃, the temperature of the mixing section is set to 360-380℃, the temperature of the venting section is set to 340-360℃, the temperature of the homogenizing section is set to 340-360℃, and the temperature of the die head area is set to 340-380℃.

[0034] When PAI is selected, the temperature of the melting and plasticizing section is set to 300-340℃, the temperature of the mixing section is set to 320-350℃, the temperature of the venting section is set to 300-320℃, the temperature of the homogenizing section is set to 310-330℃, and the temperature of the die head area is set to 300-320℃.

[0035] The temperature of the cooling rollers used for casting is at least 10°C lower than the glass transition temperature of the selected material. Rapid cooling can reduce crystallization and form films with higher transparency.

[0036] Preferably, in the preparation process of the polyaryletherketone (PAEK) material film and the polyimide material film, the following conditions are set: the vacuum degree of the melt plasticizing section is 0.04 MPa to 0.06 MPa (preliminary devolatilization to avoid sticky material overflow), the vacuum degree of the mixing section is 0.06 MPa to 0.08 MPa (enhanced devolatilization), and the vacuum degree of the venting section is in the range of 0.08 MPa to 0.1 MPa (removing residual volatiles to ensure product quality). Components such as plasticizers decompose at the melting temperature of PAEK; therefore, in order to prevent small molecule substances from carbonizing or foaming and adversely affecting the melt, vacuum devolatilization is performed first to ensure product quality.

[0037] Furthermore, the bisphenol AF type polyarylether ketone material containing imide side groups is obtained by polycondensation reaction of imide-containing bisphenol AF with 4,4'-difluorobenzophenone:

[0038]

[0039] For the specific method, please refer to the applicant's patent CN 119390967 A: bisphenol AF containing an imide with the above chemical structure and 4,4'-difluorobenzophenone are reacted with sodium carbonate and / or potassium carbonate in the presence of a reaction solvent and a dehydrating agent. The mixture is first subjected to azeotropic dehydration at 120-140℃ for 1-2 hours, followed by polycondensation at 160-180℃ for 4-12 hours (for specific examples, please refer to Example 1 of this patent).

[0040] Furthermore, the bisphenol AF type polyarylether ketone material containing imide side groups is melt-extruded and cast using a twin-screw extruder to obtain a film;

[0041] The temperature of the melt plasticizing section of the melt extrusion is set to 340-360℃, the temperature of the mixing section is set to 360-370℃, the temperature of the homogenizing section is set to 360-375℃, the temperature of the extruder head area is set to 350-365℃, and the temperature of the casting cooling roller is set to 120-160℃. Multiple cooling rollers can be set to decrease in temperature gradient.

[0042] Furthermore, the hot-pressing composite temperature is within the range of 300-400℃ for 10-30 minutes, and the pressure is set to 5-15MPa.

[0043] Beneficial technical effects:

[0044] This invention forms a polyaryletherketone (PAE) material film, a polyimide material film, and a bisphenol AF type PAE material or film containing imide side groups as an intermediate layer between the two. These three materials are then stacked and thermally bonded to form a multilayer composite film. By selecting PAE materials and polyimide materials with similar melt indices, and using bisphenol AF type PAEs containing imide side groups as an adhesive layer, the two films are hot-pressed together to achieve a multilayer film with a tensile strength of over 140 MPa, a visible light transmittance of over 75%, and a peel strength of over 70 N / mm. Detailed Implementation

[0045] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0046] Unless otherwise specifically stated, the numerical values ​​set forth in these embodiments do not limit the scope of the invention. Techniques and methods known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques and methods should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that values ​​expressed, for example, as "within the range of ab" or "between the range of ab," do not include the endpoint values ​​a and b; values ​​expressed as "for ab," "is ab," or "ab" include the endpoint values ​​a and b.

[0047] Furthermore, it should be noted that the use of terms such as "first" and "second" to define the components is merely for the purpose of distinguishing the components in each step. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0048] Experimental methods not specified in the following examples are generally performed according to national standards; if there is no corresponding national standard, they are performed according to general standard requirements or general methods.

[0049] Example 1

[0050] This case study focuses on the preparation of PEEK thin films:

[0051] The first component includes 100% by weight as shown in Table 1 below:

[0052] PEEK (model 7600G) with a melt index of 5 g / 10 min (test conditions 400℃, 2.16KG) and additives, the specific formulation is shown in Table 1;

[0053] Table 1 Formulation of Component 1

[0054]

[0055] The first component of the formula in Table 1 was mixed and then melt-extruded using a twin-screw extruder, and then cast into a film (film thickness 0.01 mm).

[0056] During the melt extrusion process, the melt of the first component is devolatilized. The twin-screw extruder includes a feeding section, a solid conveying section, a melt plasticizing section, a mixing section, a venting section, a homogenizing section, and a die head area. Venting ports are provided in the melt plasticizing section, the mixing section, and the venting section. Each venting port is connected to a vacuum system to provide negative pressure.

[0057] The temperature of the melting and plasticizing section is set to 370±5℃, the temperature of the mixing section is set to 380±5℃, the temperature of the exhaust section is set to 365±5℃, the temperature of the homogenizing section is set to 370℃, and the temperature of the die head area is set to 360℃; the vacuum degree of the melting and plasticizing section is 0.05MPa, the vacuum degree of the mixing section is 0.07MPa, and the vacuum degree of the exhaust section is 0.09MPa.

[0058] The number of cooling rollers for casting is set to 3, and the temperatures of the cooling rollers in the processing direction are set to 130℃, 100℃ and 60℃ respectively.

[0059] Example 2

[0060] This case study demonstrates the preparation of PEI thin films:

[0061] The second component includes the following 100% by weight percentages as shown in Table 1:

[0062] Polyetherimide (PEI model ULTEM1000) with a melt index of 7.1 g / 10 min (test conditions 380℃, 2.16KG) and additives, the specific formulation is shown in Table 2;

[0063] Table 2 Formulation of the second component

[0064]

[0065] The second component of the formula in Table 2 was mixed and then melt-extruded using a twin-screw extruder, and then cast into a film (film thickness 0.05 mm).

[0066] During the melt extrusion process, the melt of the second component is devolatilized. The twin-screw extruder includes a feeding section, a solid conveying section, a melt plasticizing section, a mixing section, a venting section, a homogenizing section, and a die head area. Venting ports are provided in the melt plasticizing section, the mixing section, and the venting section. Each venting port is connected to a vacuum system to provide negative pressure.

[0067] The temperature of the melting and plasticizing section is set to 355±5℃, the temperature of the mixing section is set to 365±5℃, the temperature of the exhaust section is set to 365±5℃, the temperature of the homogenizing section is set to 370℃, and the temperature of the die head area is set to 360±5℃; the vacuum degree of the melting and plasticizing section is 0.05MPa, the vacuum degree of the mixing section is 0.08MPa, and the vacuum degree of the exhaust section is 0.09MPa.

[0068] The number of cooling rollers for casting is set to 3, and the temperatures of the cooling rollers in the processing direction are set to 140℃, 100℃ and 60℃ respectively.

[0069] Example 3

[0070] This case study describes the preparation of a bisphenol AF-type polyaryletherketone film with an imide side group, having the chemical structure of Formula I.

[0071] The chemical structure of the bisphenol AF type polyarylether ketone containing an imide side group is shown in Formula I below:

[0072]

[0073] The number-average molecular weight is 2.58 × 10⁻⁶. 4 g / mol, weight-average molecular weight 5.7 × 10 4 g / mol, PDI = 2.21, Tg = 185℃ (for the preparation process, please refer to Example 1 of Patent CN 119390967 A);

[0074] The bisphenol AF type polyarylether ketone material with imide side groups of Formula I chemical structure was melt extruded and cast using a twin-screw extruder to obtain a film (film thickness 0.005 mm);

[0075] The temperature of the melt extrusion plasticizing section is set to 350±5℃, the temperature of the mixing section is set to 365±5℃, the temperature of the homogenizing section is set to 370±5℃, and the temperature of the die head area is set to 360±5℃; the number of cooling rollers for casting is set to 3, and the temperature of the cooling rollers in the processing direction is set to 160℃, 100℃, and 60℃ respectively.

[0076] Example 4

[0077] A multilayer composite film is prepared by stacking the following layers in sequence: PEEK film I (15g) of Example 1, bisphenol AF type polyaryletherketone film (2g) with imide side groups of Formula I of Example 3 as the intermediate layer, and PEI film III (53g) of Example 2, and then hot-pressing the laminated film.

[0078] The hot-pressing composite temperature is 380℃ for 10 minutes, and the pressure is set at 15MPa.

[0079] Example 5

[0080] A multilayer composite film is prepared by stacking the following layers in sequence: PEEK film II (10g) from Example 1, bisphenol AF type polyaryletherketone film (2g) with imide side groups of chemical structure I from Example 3 as the intermediate layer, and PEI film I (58g) from Example 2, and then hot-pressing the layers together.

[0081] The hot-pressing composite temperature is 380℃ for 10 minutes, and the pressure is set at 15MPa.

[0082] Example 6

[0083] A multilayer composite film is prepared by stacking the following layers in sequence: PEEK film III (5g) of Example 1, bisphenol AF type polyaryletherketone film (2g) with imide side groups containing the chemical structure of Formula I of Example 3, and PEI film II (63g) of Example 2, and then hot-pressing the layers together.

[0084] The hot-pressing composite temperature is 380℃ for 10 minutes, and the pressure is set at 15MPa.

[0085] Comparative Example 1

[0086] In this case, a layer of PEEK blank control film from Example 1 and a layer of PEI blank control film from Example 2 were directly hot-pressed together (the hot-pressing parameters were the same as in Example 4).

[0087] Comparative Example 2

[0088] In this case, pure PEEK particles and pure PEI particles were directly melt-blended and extruded in equal mass ratio and then cast into a film (the film was processed according to the parameters of Example 1).

[0089] Comparative Example 3

[0090] In this case, the first component was prepared according to the formulation of PEEK film I in Example 1, and the second component was prepared according to the formulation of PEI film III in Example 2. Then, the blend film was formed according to the operation of Comparative Example 2.

[0091] Comparative Example 4

[0092] In this case, the PEEK film I from Example 1 and the PEI film III from Example 2 are directly hot-pressed together (same as Example 4, except that there is no intermediate layer).

[0093] Test Case

[0094] The performance of the hot-pressed composite films in the above cases was tested, and the results are shown in Table 3.

[0095] Table 3 Performance of Each Case

[0096]

[0097]

[0098] As shown in Table 3, the multilayer composite film of Example 4 has higher tensile strength and elongation at break compared with the blended films of Comparative Example 2 and Comparative Example 3. The present invention uses bisphenol AF type polyarylether ketone containing imide side groups as an intermediate layer, which makes the multilayer film have higher peel strength and tensile strength, while the multilayer film has better toughness and acceptable transparency.

[0099] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A multilayer composite film, characterized in that, It is made by laminating and hot-pressing at least one layer of polyaryletherketone material film, at least one layer of polyimide material film, and at least one layer of bisphenol AF type polyaryletherketone material or film containing imide side groups; The bisphenol AF type polyarylether ketone material or its film containing imide side groups is disposed between each layer of the polyarylether ketone material film and each layer of the polyimide material film; The chemical structure of the bisphenol AF type polyarylether ketone containing an imide side group is as follows: Its number-average molecular weight is 10,000 to 30,000 g / mol, its weight-average molecular weight is 30,000 to 60,000 g / mol, and its PDI is in the range of 1-3.

2. The multilayer composite film according to claim 1, characterized in that, The polyaryletherketone material film is selected from one or more materials formed from polyetheretherketone, polyetherketone, polyetherketoneketone, polyetheretherketoneketone, and polyetherketoneetherketoneketone. The polyimide film is selected from one or more materials formed from polyimide, polyetherimide, and polyamideimide. The polyimide is selected from one of pyromellitic thermoplastic polyimide and biphenyl thermoplastic polyimide and is a semi-aromatic or aromatic polyimide.

3. The multilayer composite film according to claim 1, characterized in that, In the multilayer composite film, the polyaryletherketone material film accounts for 5%-28% by weight, the polyimide material film accounts for 70%-90%, and the bisphenol AF type polyaryletherketone material or film containing imide side groups accounts for 1%-15%.

4. The multilayer composite film according to claim 3, characterized in that, The polyaryletherketone (PAEK) material film comprises the following first component in 100% by weight: 90%-99.9% of PAEK material with a melt index of 5-20 g / 10 min under test conditions of 400℃ and 2.16 kg, and 0.1%-10% of additives; The polyimide film comprises the following second component in 100% by weight: 90%-100% polyimide material with a melt index of 5-20 g / 10 min under test conditions of 380℃ and 2.16 kg, and 0.1%-99.9% additives; The absolute value of the difference between the melt index of the polyaryletherketone material in the first component and the melt index of the polyimide material in the second component is less than 5.

5. A multilayer composite film according to claim 4, characterized in that, The additives include one or more of the following: metal oxide nanomaterials with a particle size of less than 100 nm, nano-silver with a particle size of less than 100 nm, titanate coupling agents, plasticizers, and antioxidants. The metal oxide nanomaterials are selected from one or more of nano-titanium dioxide, nano-zinc oxide, nano-alumina, and nano-indium oxide.

6. A multilayer composite film according to claim 4, characterized in that, The process of obtaining the polyaryletherketone material film includes the following steps: after mixing the first component of the formula, the mixture is melt-extruded using a twin-screw extruder, and then cast into a film. During the melt extrusion process, the melt of the first component is devolatilized under a negative pressure in the range of -0.01MPa to -0.1MPa. The twin-screw extruder includes a feeding section, a solid conveying section, a melt plasticizing section, a mixing section, a venting section, a homogenizing section, and a die head area. Venting ports are provided in the melt plasticizing section, the mixing section, and the venting section. Each venting port is connected to a vacuum system to provide negative pressure. The vacuum degree of the melting and plasticizing section is 0.04MPa to 0.06MPa, the vacuum degree of the mixing section is 0.06MPa to 0.08MPa, and the vacuum degree of the exhaust section is in the range of 0.08MPa to 0.1MPa. When PEEK is selected, the temperature of the melting and plasticizing section is set to 360-380℃, the temperature of the mixing section is set to 370-390℃, the temperature of the venting section is set to 360-370℃, the temperature of the homogenizing section is set to 350-370℃, and the temperature of the die head area is set to 340-360℃. When PEK is selected, the temperature of the melting and plasticizing section is set to 380-400℃, the temperature of the mixing section is set to 390-400℃, the temperature of the venting section is set to 380-390℃, the temperature of the homogenizing section is set to 370-390℃, and the temperature of the die head area is set to 365-385℃. When PEKK is selected, the temperature of the melting and plasticizing section is set to 370-390℃, the temperature of the mixing section is set to 380-400℃, the temperature of the venting section is set to 365-375℃, the temperature of the homogenizing section is set to 360-380℃, and the temperature of the die head area is set to 350-370℃. When PEEKK is selected, the temperature of the melting and plasticizing section is set to 365-385℃, the temperature of the mixing section is set to 375-395℃, the temperature of the venting section is set to 360-370℃, the temperature of the homogenizing section is set to 355-375℃, and the temperature of the die head area is set to 345-365℃. When PEKEKK is selected, the temperature of the melting and plasticizing section is set to 400-420℃, the temperature of the mixing section is set to 410-430℃, the temperature of the venting section is set to 390-400℃, the temperature of the homogenizing section is set to 380-400℃, and the temperature of the die head area is set to 380-400℃. The temperature of the cooling rollers used for casting is at least 10°C lower than the glass transition temperature of the selected material.

7. A multilayer composite film according to claim 4, characterized in that, The process of obtaining the polyimide film includes the following steps: mixing the second component of the formula and then performing melt extrusion using a twin-screw extruder, followed by casting into a film; During the melt extrusion process, the melt of the second component is devolatilized under a negative pressure in the range of -0.01MPa to -0.1MPa. The twin-screw extruder includes a feeding section, a solid conveying section, a melt plasticizing section, a mixing section, a venting section, a homogenizing section, and a die head area. Venting ports are provided in the melt plasticizing section, the mixing section, and the venting section. Each venting port is connected to a vacuum system to provide negative pressure. The vacuum degree of the melting and plasticizing section is 0.04MPa to 0.06MPa, the vacuum degree of the mixing section is 0.06MPa to 0.08MPa, and the vacuum degree of the exhaust section is in the range of 0.08MPa to 0.1MPa. When PI is selected, the temperature of the melting and plasticizing section is set to 380-400℃, the temperature of the mixing section is set to 380-400℃, the temperature of the exhaust section is set to 380-400℃, the temperature of the homogenization section is set to 380-400℃, and the temperature of the die head area is set to 380-400℃. When PEI is selected, the temperature of the melting and plasticizing section is set to 340-380℃, the temperature of the mixing section is set to 360-380℃, the temperature of the venting section is set to 340-360℃, the temperature of the homogenizing section is set to 340-360℃, and the temperature of the die head area is set to 340-380℃. When PAI is selected, the temperature of the melting and plasticizing section is set to 300-340℃, the temperature of the mixing section is set to 320-350℃, the temperature of the venting section is set to 300-320℃, the temperature of the homogenizing section is set to 310-330℃, and the temperature of the die head area is set to 300-320℃. The temperature of the cooling rollers used for casting is at least 10°C lower than the glass transition temperature of the selected material.

8. A multilayer composite film according to any one of claims 1-7, characterized in that, The bisphenol AF-type polyaryletherketone material containing an imide side group is obtained by polycondensation reaction of bisphenol AF containing an imide and 4,4'-difluorobenzophenone, with the following chemical structure:

9. A multilayer composite film according to claim 8, characterized in that, The bisphenol AF type polyarylether ketone material containing imide side groups was melt-extruded and cast using a twin-screw extruder to obtain a film; The temperature of the melt plasticizing section of the melt extrusion is set to 340-360℃, the temperature of the mixing section is set to 360-370℃, the temperature of the homogenizing section is set to 360-375℃, the temperature of the extruder head area is set to 350-365℃, and the temperature of the casting cooling roller is set to 60-160℃.

10. A multilayer composite film according to any one of claims 1-7, characterized in that, The hot-pressing composite is performed at a temperature of 300-400℃ for 10-30 minutes, with the pressure set at 5-15 MPa.

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