Conductive polyimide composite material and preparation method thereof

Abstract

The invention belongs to the technical field of resin-based composite material preparation, and particularly discloses a conductive polyimide composite material and a preparation method thereof. The polyimide film with the metal layer and the thermosetting polyimide prepreg blank are bonded and then co-cured, the metal layer is transferred to the surface of the polyimide composite material from the polyimide film through high temperature and high pressure, high-precision preparation of the thin-metal-layer conductive polyimide composite material is achieved, the method is simple, and the cost is low. And the method is high in manufacturing efficiency, suitable for batch and industrial production, good in application prospect and high in economic value. The preparation process of the metal layer and the curing process of the composite material are fused, preparation of the thin metal layer can be achieved, the prepared surface metal layer is firmly combined with the polyimide composite material, and meanwhile the composite material is endowed with electromagnetic shielding and lightning protection functions through the conductive effect of the metal layer; the method has a wide application prospect in the field of aerospace.

Description

Technical Field

[0001] The invention belongs to the technical field of preparing resin-based composite materials, and in particular relates to a conductive polyimide composite material and a method for preparing the conductive polyimide composite material based on surface film transfer. Background Art

[0002] Thermosetting polyimide resins and their composite materials have excellent comprehensive properties at high temperatures, can be used for a long time at high temperatures (280°C ~ 400°C), and can be used as load-bearing components in high temperature environments. They are widely used in the fields of aviation, aerospace and space technology, especially in aero engines and aerospace planes.

[0003] However, with the continuous improvement of equipment performance, the high performance of aviation equipment also requires polyimide composite materials to have electromagnetic shielding, lightning resistance and other properties, which is mainly achieved by improving the surface conductivity of the composite material. At present, the traditional method of improving the surface conductivity of composite materials is mainly to form a metal coating on the surface of the composite material by spraying. However, the metal layer produced by spraying is generally thicker and less dense. Although it can conduct electricity, its resistance to thermal oxidation is insufficient, and there is no matching high-temperature putty at this stage, resulting in weak interface bonding between it and the composite material. In addition, a surface self-metallization method can also be used to form a metal layer on the surface of the polyimide composite material. Although this method can form a thinner metal layer, it needs to be etched with a strong alkaline solution, which will have an adverse effect on the performance of the composite material itself. More importantly, the coating formation cycle is long and is not suitable for manufacturing larger parts.

[0004] To solve this problem, Chinese patent CN101736330B (BYD) provides a polyimide surface metallization method, including: coarsening treatment, activation treatment, reduction treatment and chemical metal plating treatment of the polyimide film in sequence, and to improve the bonding between the surface coating and the polyimide, a salt-based palladium activation solution (containing water-soluble chlorides of metal elements from the second to fourth periods of the periodic table, compounds containing pyridine groups and water-soluble palladium salts) is used to activate the film to deposit a uniform layer of activation center core particles on the polyimide surface, providing a basic site for metal plating, and ensuring that the metal plating can be uniformly attached to the polyimide surface. Although this method can enhance the bonding between the metal coating and the polyimide film, its preparation process is complicated, the raw materials are expensive and varied, and the production cost is high.

[0005] Therefore, there is an urgent need to develop a polyimide composite material with easily available raw materials, simple preparation process, and electromagnetic shielding and lightning protection functions and a preparation method thereof. Summary of the invention

[0006] The main technical problem solved by the present invention is that the metal layer on the surface of the conductive polyimide composite material is difficult to prepare and the bonding force between the metal layer and the composite material is weak, so that the electromagnetic shielding and lightning protection functions cannot be effectively provided. To this end, the present invention proposes a method for preparing a conductive polyimide composite material based on surface film transfer, wherein a polyimide film having a metal layer is bonded to a thermosetting polyimide prepreg blank and then co-cured, and the metal layer is transferred from the polyimide film to the surface of the polyimide composite material by high temperature and high pressure, thereby obtaining a conductive polyimide composite material with a thin metal layer firmly bonded to the composite material.

[0007] At the same time, the present invention also provides a conductive polyimide composite material prepared based on a surface film transfer method, and the composite material is endowed with electromagnetic shielding and lightning protection functions by means of the conductive effect of the transferred surface metal layer.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0009] A method for preparing a conductive polyimide composite material comprises the following steps:

[0010] The polyimide film with the metal layer is bonded to the thermosetting polyimide prepreg blank, and then co-cured. After the curing is completed, the polyimide film is removed to obtain a conductive polyimide composite material.

[0011] The present invention integrates the preparation process of the metal layer with the curing process of the composite material, which can realize the high-precision preparation of the thin metal layer and significantly improve the manufacturing efficiency. At the same time, the surface metal layer is firmly combined with the polyimide composite material, and its conductive effect can also give the composite material electromagnetic shielding and lightning protection functions.

[0012] As a preferred embodiment of the present invention, the metal in the metal layer includes but is not limited to one or more of gold, silver, copper, aluminum, tungsten, nickel and the like.

[0013] As a preferred embodiment of the present invention, the thickness of the metal layer is 0.1-100 μm.

[0014] Specifically, the polyimide film with a metal layer is a commercially available product.

[0015] As a preferred embodiment of the present invention, the polyimide film is prepared using linear polyimide or thermoplastic polyimide. Among them, thermoplastic polyimide, as a high temperature resistant resin, has higher thermal stability and high creep resistance than traditional thermosetting polyimide, and the film material using it as a carrier can more effectively realize the transfer of the metal layer.

[0016] As a preferred embodiment of the present invention, the polyimide film has a metal layer on one or both sides. During bonding, the side with the metal layer faces the thermosetting polyimide prepreg blank.

[0017] As a preferred embodiment of the present invention, the method for preparing the thermosetting polyimide prepreg blank comprises:

[0018] Thermosetting polyimide prepreg is layered and then pretreated under the conditions of 80-230° C. and vacuum degree ≥0.09 MPa to obtain a thermosetting polyimide prepreg blank.

[0019] Specifically, the thermosetting polyimide prepreg includes but is not limited to one or more of unidirectional prepreg, fabric prepreg, and the like.

[0020] Specifically, the pretreatment time is 30 to 90 minutes.

[0021] As a preferred embodiment of the present invention, the bonding uses a polyimide adhesive. The polyimide adhesive is a commercially available product. When in use, the polyimide adhesive is applied to the side of the polyimide film having the metal layer, ensuring that the side having the metal layer faces the thermosetting polyimide prepreg blank during bonding, so as to facilitate the transfer of the surface metal layer.

[0022] As a preferred embodiment of the present invention, the metal layer of the polyimide film may be subjected to surface treatment before bonding, including but not limited to one or more of electrochemical treatment, plasma treatment, etc. Surface treatment of the metal layer can obtain a clean surface, and more importantly, improve the bonding strength between the metal layer and the thermosetting polyimide composite material.

[0023] As a preferred embodiment of the present invention, the bonding is to bond a polyimide film having a metal layer to one side or both sides of the thermosetting polyimide prepreg blank.

[0024] As a preferred embodiment of the present invention, high temperature auxiliary materials are used for packaging after bonding to ensure smooth high temperature and high pressure curing.

[0025] As a preferred embodiment of the present invention, the co-curing is: keeping warm at 260-450° C. and 0.1-2.5 MPa for 200-720 min.

[0026] As a preferred embodiment of the present invention, the co-curing is carried out in stages, first keeping warm at 260-330°C for 10-60 minutes, pressurizing to 0.1-2.5MPa, and then heating to 350-450°C and keeping warm and pressurizing for 120-720 minutes to ensure that the prepreg is fully bonded to the metal layer on the surface of the film.

[0027] A conductive polyimide composite material prepared by the method.

[0028] Specifically, the conductive polyimide composite material can be applied to electromagnetic shielding and lightning protection in high temperature environments.

[0029] Beneficial effects of the present invention:

[0030] The invention provides a method for preparing a conductive polyimide composite material based on surface film transfer. The method comprises the following steps: a polyimide film having a metal layer is bonded to a thermosetting polyimide prepreg blank and then co-cured, and the metal layer is transferred from the polyimide film to the surface of the polyimide composite material by high temperature and high pressure, thereby realizing the preparation of a conductive polyimide composite material with a thin metal layer. The method is simple and efficient, suitable for batch and industrial production, and has good application prospects and high economic value.

[0031] The present invention integrates the preparation process of the metal layer with the curing process of the composite material, which can achieve high-precision preparation of the thin metal layer and significantly improve manufacturing efficiency. At the same time, the surface metal layer is firmly combined with the polyimide composite material, and its conductive effect can also give the composite material electromagnetic shielding and lightning protection functions, which has broad application prospects in the aerospace field. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is an assembly diagram of the conductive polyimide composite material before curing;

[0033] In the figure, 1 is a polyimide film with a metal layer, 2 is a polyimide adhesive layer, and 3 is a thermosetting polyimide prepreg blank.

[0034] Figure 2 Schematic diagram of the structure of the conductive polyimide composite material;

[0035] In the figure, 1 is a thin metal layer and 2 is a thermosetting polyimide composite material matrix.

[0036] In order to more clearly illustrate the technical solution to be protected by the present invention, the drawings in the embodiments and / or experimental examples are briefly introduced above. It should be understood that the above drawings should not be regarded as any limitation on the protection scope of the present invention. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is described in detail below through specific embodiments. The following embodiments are intended to further illustrate the content of the present invention in detail, but are not intended to limit the scope of protection of the claims of the present invention.

[0038] In the following examples and comparative examples, unless otherwise specified, the raw materials, reagents, equipment, etc. used are all commercially available products. Among them, the polyimide film with a metal layer was purchased from Forsman (Beijing) Technology Co., Ltd.; the polyimide adhesive was purchased from the Composites Center of China Aviation Manufacturing Technology Research Institute, product model AC723; the thermosetting polyimide prepreg was purchased from the Composites Center of China Aviation Manufacturing Technology Research Institute, product model CCF800H / AC721.

[0039] Example 1

[0040] This embodiment provides a method for preparing a conductive polyimide composite material, comprising the following steps:

[0041] (1) Using CCF800H / AC721 thermosetting polyimide prepreg, according to [45 / 0 / -45 / 90] 3s The designed layers are laid, and the prepreg after laying is pretreated at 135° C. and vacuum degree ≥ 0.09 MPa for 60 min to obtain a polyimide prepreg blank.

[0042] (2) A 55 μm thick single-sided copper-plated (linear) polyimide film is selected. The polyimide film thickness is 50 μm and the copper plating thickness is 5 μm. The copper-plated surface of the polyimide film is subjected to plasma treatment (technical parameters are: oxygen atmosphere, power of 200 W, and treatment time of 10 min). Then, a layer of polyimide adhesive is applied on the copper-plated surface, which is then laid and bonded to both sides of the prepreg blank obtained in step (1) (such as Figure 1 ), and then encapsulated with high temperature auxiliary materials.

[0043] (3) The encapsulated material is co-cured by first keeping the temperature at 290°C for 30 minutes, pressurizing to 1.5 MPa, and then heating to 375°C for 180 minutes. After the curing is completed, the polyimide film on the surface of the composite material is peeled off to obtain a conductive polyimide composite material (such as Figure 2 shown).

[0044] Example 2

[0045] This embodiment provides a method for preparing a conductive polyimide composite material, comprising the following steps:

[0046] (1) CCF800H / AC721 thermosetting polyimide prepreg was used and clad according to the designed layup of [45 / 0 / -45 / 90]3s. The clad prepreg was pretreated at 135°C and vacuum degree ≥0.09MPa for 60min to obtain a polyimide prepreg blank.

[0047] (2) A single-sided copper-plated (linear) polyimide film with a thickness of 60 μm is selected, the thickness of the polyimide film is 50 μm, and the thickness of the copper plating layer is 10 μm. The copper-plated surface of the polyimide film is plasma treated (technical parameters are: oxygen atmosphere, power of 200 W, and treatment time of 10 min). Then, a layer of polyimide adhesive is applied on its copper-plated surface, which is covered and bonded to both sides of the prepreg blank obtained in step (1), and then encapsulated with a high-temperature auxiliary material.

[0048] (3) The encapsulated material is co-cured by first keeping the temperature at 290°C for 30 minutes, pressurizing to 1.5 MPa, and then heating to 375°C and keeping the temperature and pressure for 180 minutes. After the curing is completed, the polyimide film on the surface of the composite material is peeled off to obtain a conductive polyimide composite material.

[0049] Example 3

[0050] This embodiment provides a method for preparing a conductive polyimide composite material, comprising the following steps:

[0051] (1) CCF800H / AC721 thermosetting polyimide prepreg was used and clad according to the designed layup of [45 / 0 / -45 / 90]3s. The clad prepreg was pretreated at 135°C and vacuum degree ≥0.09MPa for 60min to obtain a polyimide prepreg blank.

[0052] (2) A single-sided copper-plated (linear) polyimide film with a thickness of 35 μm is selected, the thickness of the polyimide film is 25 μm, and the thickness of the copper plating layer is 10 μm. The copper-plated surface of the polyimide film is plasma treated (technical parameters are: oxygen atmosphere, power of 200 W, and treatment time of 10 min). Then, a layer of polyimide adhesive is applied on its copper-plated surface, which is covered and bonded to both sides of the prepreg blank obtained in step (1), and then encapsulated with a high-temperature auxiliary material.

[0053] (3) The encapsulated material is co-cured by first keeping the temperature at 290°C for 30 minutes, pressurizing to 1.5 MPa, and then heating to 375°C and keeping the temperature and pressure for 180 minutes. After the curing is completed, the polyimide film on the surface of the composite material is peeled off to obtain a conductive polyimide composite material.

[0054] Example 4

[0055] This embodiment provides a method for preparing a conductive polyimide composite material, comprising the following steps:

[0056] (1) CCF800H / AC721 thermosetting polyimide prepreg was used and clad according to the designed layup of [45 / 0 / -45 / 90]3s. The clad prepreg was pretreated at 135°C and vacuum degree ≥0.09MPa for 60min to obtain a polyimide prepreg blank.

[0057] (2) A single-sided silver-plated (thermoplastic) polyimide film with a thickness of 30 μm is selected, the thickness of the polyimide film is 25 μm, and the thickness of the silver-plated layer is 5 μm. The silver-plated surface of the polyimide film is plasma treated (technical parameters are: oxygen atmosphere, power of 200 W, and treatment time of 10 min). Then, a layer of polyimide adhesive is applied on the silver-plated surface, which is then covered and bonded to both sides of the prepreg blank obtained in step (1), and then encapsulated using a high-temperature auxiliary material.

[0058] (3) The encapsulated material is co-cured by first keeping it at 290°C for 30 minutes, pressurizing it to 1.5 MPa, and then heating it to 350°C and keeping it at this temperature and pressure for 600 minutes. After the curing is completed, the polyimide film on the surface of the composite material is peeled off to obtain a conductive polyimide composite material.

[0059] Example 5

[0060] This embodiment provides a method for preparing a conductive polyimide composite material, comprising the following steps:

[0061] (1) CCF800H / AC721 thermosetting polyimide prepreg was used and clad according to the designed layup of [45 / 0 / -45 / 90]3s. The clad prepreg was pretreated at 135°C and vacuum degree ≥0.09MPa for 60min to obtain a polyimide prepreg blank.

[0062] (2) A single-sided aluminum-plated (thermoplastic) polyimide film with a thickness of 30 μm is selected, the thickness of the polyimide film is 25 μm, and the thickness of the aluminum-plated layer is 5 μm. The aluminum-plated surface of the polyimide film is plasma treated (technical parameters are: oxygen atmosphere, power of 200 W, and treatment time of 10 min). Then, a layer of polyimide adhesive is applied on the aluminum-plated surface, which is then covered and bonded to both sides of the prepreg blank obtained in step (1), and then encapsulated using a high-temperature auxiliary material.

[0063] (3) The encapsulated material is co-cured by first keeping it at 290°C for 30 minutes, pressurizing it to 1.5 MPa, and then heating it to 350°C and keeping it at this temperature and pressure for 600 minutes. After the curing is completed, the polyimide film on the surface of the composite material is peeled off to obtain a conductive polyimide composite material.

[0064] In other embodiments of the present invention, the raw materials and process parameters in the preparation method can be arbitrarily used or taken in a given range, which will not substantially affect the final performance of the conductive polyimide composite material.

[0065] Experimental example

[0066] The conductive polyimide composite materials prepared in Examples 1 to 5 were tested for conductivity using a four-probe method. The test results are shown in Table 1.

[0067] Table 1 Test results of conductive properties of conductive polyimide composite materials

[0068] project <![CDATA[Surface resistivity / Ω·sq -1 > Example 1 0.27 Example 2 0.20 Example 3 0.17 Example 4 0.12 Example 5 0.25

[0069] It can be seen from Table 1 that the conductive polyimide composite material prepared in the embodiment of the present invention has good conductivity and is suitable for electromagnetic shielding and lightning protection in high temperature environments.

[0070] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for preparing a conductive polyimide composite material, characterized in that: The following steps are involved: The polyimide film with the metal layer is bonded to the thermosetting polyimide prepreg blank, and then co-cured. After the curing is completed, the polyimide film is removed to obtain a conductive polyimide composite material.

2. The preparation method according to claim 1, characterized in that: The metal in the metal layer includes, but is not limited to, one or more of gold, silver, copper, aluminum, tungsten, and nickel; And / or, the thickness of the metal layer is 0.1-100 μm.

3. The preparation method according to claim 1, characterized in that: The polyimide film is prepared by using linear polyimide or thermoplastic polyimide; And / or, the polyimide film has a metal layer on one side or both sides, and during bonding, the side with the metal layer faces the thermosetting polyimide prepreg blank.

4. The preparation method according to claim 1, characterized in that: The preparation method of the thermosetting polyimide prepreg blank comprises: Thermosetting polyimide prepreg is layered and then pretreated under the conditions of 80-230° C. and vacuum degree ≥0.09 MPa to obtain a thermosetting polyimide prepreg blank.

5. The preparation method according to claim 4, characterized in that: The thermosetting polyimide prepreg includes but is not limited to one or both of unidirectional prepreg and fabric prepreg; And / or, the pretreatment time is 30 to 90 minutes.

6. The preparation method according to claim 1, characterized in that: The bonding uses a polyimide adhesive, and when in use, the polyimide adhesive is brushed on the side of the polyimide film with the metal layer.

7. The preparation method according to claim 1, characterized in that: The metal layer of the polyimide film may be subjected to surface treatment before bonding, including but not limited to one or both of electrochemical treatment and plasma treatment.

8. The preparation method according to claim 1, characterized in that: The bonding is to bond a polyimide film having a metal layer to one side or both sides of the thermosetting polyimide prepreg blank; And / or, after the bonding, a high temperature auxiliary material is used for packaging.

9. The preparation method according to claim 1, characterized in that: The co-curing is: keeping warm for 200 to 720 minutes at 260 to 450° C. and 0.1 to 2.5 MPa; And / or, the co-curing is carried out in stages, firstly keeping the temperature at 260-330° C. for 10-60 min, pressurizing to 0.1-2.5 MPa, and then heating to 350-450° C. and keeping the temperature and pressure for 120-720 min.

10. A conductive polyimide composite material prepared by the preparation method according to any one of claims 1 to 9.

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