Electrically continuous conductive adhesive film and preparation method thereof

Abstract

The invention relates to the technical field of conductive composite materials, in particular to an electric continuous conductive adhesive film and a preparation method thereof.The electric continuous conductive adhesive film comprises a conductive functional layer and a resin film layer wrapping the conductive functional layer; conductive particles are arranged in the resin film layer, and the weight ratio of the conductive particles to the resin film layer is 1-15%. The preparation method comprises the steps that the average diameter of the conductive particles is determined according to the thickness of the adhesive film, and the average diameter of the conductive particles is larger than the thickness of the resin film; heating and melting the resin at a set melting temperature, adding the conductive particles into the molten resin, and stirring until the conductive particles and the resin are uniformly mixed to form a resin mixture; molding the cooled resin mixture into an adhesive film by adopting a hot melting method; and compounding the adhesive film with a conductive functional layer, and carrying out hot-pressing compounding and cooling section hardening to obtain the electrically continuous conductive adhesive film. The electrically continuous conductive adhesive film and the preparation method thereof aim at solving the problem that the surface conductivity of the conductive adhesive film after resin curing is relatively poor.

Description

Technical Field

[0001] The invention relates to the technical field of conductive composite materials, and in particular to an electrically continuous conductive adhesive film and a preparation method thereof. Background Art

[0002] In order to ensure flight safety, all aircraft components must be fully electrically connected for the following purposes:

[0003] 1) Form a lightning current channel to prevent lightning from damaging the aircraft structure;

[0004] 2) It helps dissipate or release static electricity on the aircraft surface;

[0005] 3) Form a closed electromagnetic shielding body to protect airborne electronic equipment from external electromagnetic interference.

[0006] Advanced composite materials are widely used in aircraft structures due to their high specific strength and specific modulus, which can achieve significant structural weight reduction. However, their electrical conductivity is insufficient and it is difficult to form a complete conductive path, which poses a flight safety hazard. At present, lightning protection technologies for composite surface metallization at home and abroad mainly include:

[0007] 1) Spray aluminum on the surface of the composite material using flame or plasma thermal spraying technology;

[0008] 2) Laying metal foil or metal mesh on the surface of the composite material and bonding it by one-step curing or adhesive;

[0009] 3) A conductive nonwoven fabric is combined with an adhesive film to form a conductive film, which is cured together with the composite material.

[0010] Among them, conductive film has excellent lightning protection and electromagnetic shielding performance due to its light weight and good processability. However, the surface of traditional conductive film is covered with resin after curing, resulting in insufficient surface conductivity. At present, many conductive films are used in many occasions, and at the same time, they are required to meet the requirements of electromagnetic shielding and lightning protection, and also meet the requirements of electrical continuity with other metal devices or fasteners.

[0011] For example, when used for electromagnetic wave reflection plates, not only is the conductive film itself required to reflect electromagnetic waves, but the other related connectors are also required to maintain electrical continuity. Composite materials often need to be slotted and punched to connect with other parts through bolts, which also requires that the metal parts and the composite surface can achieve electrical continuity. This generally requires that the conductive film is cured on the surface of the composite material and has a certain degree of conductivity.

[0012] Therefore, the inventors provide an electrically continuous conductive adhesive film and a method for preparing the same. Summary of the invention

[0013] (1) Technical issues to be solved

[0014] The embodiment of the present invention provides an electrically continuous conductive adhesive film and a preparation method thereof, which solves the technical problem that the conductive adhesive film has poor surface conductivity after the resin is cured.

[0015] (2) Technical solution

[0016] The first aspect of the present invention provides an electrically continuous conductive adhesive film, comprising a conductive functional layer and a resin film layer wrapped around the conductive functional layer; wherein the resin film layer contains conductive particles, the average diameter of the conductive particles is greater than the thickness of the resin film layer, the conductive particles are connected to the conductive functional layer, and the weight ratio of the conductive particles to the resin film layer is 1 to 15%.

[0017] Furthermore, the conductive particles include any one of metal particles, carbon material particles, and metal and carbon material composite particles.

[0018] Furthermore, the material of the resin film layer includes any one of medium-temperature curing epoxy resin, high-temperature curing epoxy resin, cyanate resin, bismaleimide resin and polyimide resin.

[0019] Furthermore, the conductive functional layer is any one of a conductive non-woven fabric, a carbon nanotube film and a conductive fabric.

[0020] Furthermore, the surface density of the conductive functional layer is 1 to 100 g / m 2 .

[0021] Furthermore, the thickness of the conductive functional layer is 0.01-0.2 mm.

[0022] Furthermore, the surface resistance of the conductive functional layer is 0.0001-5Ω / □.

[0023] The second aspect of the present invention provides a method for preparing the above-mentioned electrically continuous conductive adhesive film, comprising the following steps:

[0024] Determining an average diameter of the conductive particles according to the thickness of the adhesive film, wherein the average diameter of the conductive particles is greater than the thickness of the resin film;

[0025] Heat the resin to melt at a set melting temperature, add the conductive particles into the molten resin, and stir until the conductive particles and the resin are evenly mixed to form a resin mixture;

[0026] forming the cooled resin mixture into a film by a hot melt method;

[0027] The adhesive film is compounded with the conductive functional layer, and subjected to hot pressing and hardening in a cooling stage to obtain an electrically continuous conductive adhesive film.

[0028] Furthermore, the surface density of the film is 20 to 100 g / m 2 .

[0029] Furthermore, the surface density of the electrically continuous conductive film is 30 to 150 g / m 2 .

[0030] (3) Beneficial effects

[0031] In summary, the present invention adopts conductive particles whose average diameter is greater than the thickness of the adhesive film to ensure that the conductive particles can pierce the adhesive film and connect with the conductive functional layer after composite to achieve electrical continuity, and realize surface conductivity after the conductive functional layer and the resin film layer are composited and cured, while ensuring the processability and adhesion of the resin film and maintaining light weight and surface electrical continuity. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments of the present invention are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0033] Figure 1 is a schematic structural diagram of an electrically continuous conductive adhesive film provided by an embodiment of the present invention;

[0034] Figure 2 is a microscopic morphology diagram of a resin film layer provided by an embodiment of the present invention;

[0035] Figure 3 This is an optical photograph of an electrically continuous conductive adhesive film provided by an embodiment of the present invention;

[0036] Figure 4 It is a schematic flow chart of a method for preparing an electrically continuous conductive adhesive film provided in an embodiment of the present invention.

[0037] In the figure:

[0038] 1-conductive functional layer; 2-resin film layer; 3-protective layer. DETAILED DESCRIPTION

[0039] The following is a further detailed description of the embodiments of the present invention in conjunction with the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to exemplarily illustrate the principles of the present invention, but cannot be used to limit the scope of the present invention, that is, the present invention is not limited to the described embodiments, and covers any modification, replacement and improvement of parts, components and connection modes without departing from the spirit of the present invention.

[0040] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0041] Figure 1 is a schematic diagram of the structure of an electrically continuous conductive adhesive film provided by an embodiment of the present invention, see Figure 1 The conductive film may include a conductive functional layer 1 and a resin film layer 2 wrapped around the conductive functional layer 1, and a protective layer 3 is provided on both the upper and lower surfaces of the conductive film. The two protective layers 3 attached to the upper and lower surfaces may be a polyethylene film and a release paper, respectively. Figure 2 As shown, the resin film layer 2 contains conductive particles, the average diameter of the conductive particles is greater than the thickness of the resin film layer 2, the conductive particles are connected to the conductive functional layer 1, and the weight ratio of the conductive particles to the resin film layer 2 is 1 to 15%.

[0042] In the above embodiment, a small amount of conductive particles whose diameter is slightly larger than the thickness of the resin film layer 2, when the resin film layer 2 containing the conductive particles is compounded with the conductive functional layer 1, the conductive particles pierce the resin film layer 2 and connect with the conductive functional layer 1, so that the surface remains conductive after curing. Figure 3 As shown. Specifically, the conductive particles include any one of metal particles, carbon material particles and metal and carbon material composite particles; the material of the resin film layer 2 includes any one of medium temperature curing epoxy resin, high temperature curing epoxy resin, cyanate resin, bismaleimide resin and polyimide resin; the conductive functional layer 1 is any one of conductive non-woven fabric, carbon nanotube film and conductive fabric. Furthermore, the surface density of the conductive functional layer 1 is 1 to 100 g / m 2 The thickness of the conductive functional layer 1 is 0.01 to 0.2 mm, the surface resistance of the conductive functional layer 1 is 0.0001 to 5 Ω / □, and the average pore spacing of the conductive fabric is less than 50 μm.

[0043] The conductive functional layer 1 and the resin film layer 2 are compositely co-cured, and have good processability and maintainability, small curing deformation, light weight, and can effectively reduce weight, while having good electromagnetic shielding performance. The conductive adhesive film has a wide range of applications and can be used in multiple fields such as lightning protection, electromagnetic shielding, electromagnetic wave reflection, and heating material electrode preparation.

[0044] Figure 4 is a schematic diagram of a method for preparing an electrically continuous conductive adhesive film provided by an embodiment of the present invention, see Figure 4 , the method may include the following steps:

[0045] S100, determining an average diameter of the conductive particles according to the thickness of the adhesive film, wherein the average diameter of the conductive particles is greater than the thickness of the resin film.

[0046] Specifically, calculate the theoretical thickness of the film:

[0047]

[0048] Where l is the theoretical thickness of the film, ρ ds is the surface density of the conductive functional layer, ρ dv is the volume density of the conductive functional layer, ρ rs is the surface density of the resin film ρ rv is the bulk density of the resin film.

[0049] The conductive particles are screened to ensure that their average diameter d is slightly larger than the film thickness l, to ensure that the conductive particles can pierce the film and the conductive functional layer after compounding to achieve electrical continuity and surface conductivity. The preferred average diameter d of the conductive particles is 1.05l to 1.5l.

[0050] S200, heating and melting the resin at a set melting temperature, adding the conductive particles into the molten resin, and stirring until the conductive particles and the resin are evenly mixed to form a resin mixture.

[0051] Specifically, the melting temperature is controlled to a level where no reaction occurs but the viscosity is low (viscosity < 1000 Pa·s), which is specifically adjusted according to different types of resins, wherein the preferred viscosity is < 150 Pa·s. Then the conductive particles are slowly added to the resin, stirred at a high speed (stirring speed > 200 rpm) until the conductive particles and the resin are evenly mixed, and then cooled for use. The weight ratio of the conductive particles to the resin is 1 to 15%.

[0052] S300, forming the cooled resin mixture into an adhesive film by a hot melt method.

[0053] Specifically, the surface density of the film is 20 to 100 g / m 2 .

[0054] S400, compounding the adhesive film and the conductive functional layer, and subjecting the compounding to hot pressing, and hardening in a cooling section to obtain an electrically continuous conductive adhesive film.

[0055] Specifically, the conductive film is obtained by hot pressing and laminating with a hot pressing roller, hardening in a cooling section, and covering the surface with a protective film. The surface density of the electrically continuous conductive film is 30 to 150 g / m 2 .

[0056] Example 1

[0057] 1. The conductive particles are carbon material and metal composite particles with an average particle size of 60μm. The resin is medium temperature curing epoxy resin. The two are mixed in a ratio of 5:100 and melted and mixed at 60℃.

[0058] 2. The obtained resin containing conductive particles is coated on the release paper in a film machine by melting method, and the film surface density is 50g / m 2 .

[0059] 3. The above film and the metal-deposited conductive nonwoven fabric (surface density 45g / m 2 , thickness 0.04mm) to obtain a conductive film with a surface density of 95g / m 2 The basic properties of the conductive film are shown in Table 1.

[0060] 4. The above conductive film is compounded with carbon fiber reinforced medium-temperature epoxy resin to obtain a surface electrically continuous composite material, the contact resistance between the surface and the metal is 20 mΩ.

[0061] Table 1 Basic properties of conductive films

[0062] project Test value <![CDATA[Areal density, g / m 2 > 95 Single layer thickness, mm 0.05 Pull-out strength, MPa 9.7 Peel strength, MPa 4.3 Tensile shear strength, MPa 12.4

[0063] Example 2

[0064] 1. The conductive particles are carbon material and metal composite particles with an average particle size of 80μm. The resin is cyanate resin. The two are mixed in a ratio of 10:100 and melted and mixed at 90°C.

[0065] 2. The obtained resin containing conductive particles is coated on the release paper in a film machine by a melting method, and the film surface density is 60g / m 2 .

[0066] 3. The above film and the metal-deposited conductive nonwoven fabric (surface density 45g / m 2 , thickness 0.04mm) composite conductive film, 105g / m 2 .

[0067] 4. The above conductive film was compounded with quartz fiber reinforced cyanate resin to obtain a surface electrically continuous composite material, the contact resistance between the surface and the metal was 110 mΩ.

[0068] Example 3

[0069] 1. The conductive particles are carbon material and metal composite particles with an average particle size of 80μm. The resin is high-temperature epoxy resin. The two are mixed in a ratio of 12:100 and melted and mixed at 80℃.

[0070] 2. The obtained resin containing conductive particles is coated on the release paper in a film machine by melting method, and the film surface density is 55g / m 2 .

[0071] 3. The above film and the metal-deposited conductive nonwoven fabric (surface density 48g / m 2, thickness 0.04mm) to obtain a conductive film with a surface density of 103g / m 2 .

[0072] 4. The above conductive film is compounded with quartz fiber reinforced cyanate resin to obtain a surface electrically continuous composite material, the contact resistance between the surface and the metal is 80 mΩ.

[0073] It should be clear that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. The present invention is not limited to the specific steps and structures described above and shown in the figures. In addition, for the sake of brevity, a detailed description of known methods and technologies is omitted here.

[0074] The above are only embodiments of the present application and are not limited to the present application. For those skilled in the art, the present application may have various changes and variations without departing from the scope of the present invention. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. An electrically continuous conductive film, characterized in that: The invention comprises a conductive functional layer (1) and a resin film layer (2) wrapped around the conductive functional layer (1); wherein the resin film layer (2) contains conductive particles, the average diameter of the conductive particles is greater than the thickness of the resin film layer (2), the conductive particles are connected to the conductive functional layer (1), and the weight ratio of the conductive particles to the resin film layer (2) is 1 to 15%.

2. The electrically continuous conductive adhesive film according to claim 1, characterized in that: The conductive particles include any one of metal particles, carbon material particles, and metal and carbon material composite particles.

3. The electrically continuous conductive adhesive film according to claim 1, characterized in that: The material of the resin film layer (2) includes any one of medium-temperature curing epoxy resin, high-temperature curing epoxy resin, cyanate resin, bismaleimide resin and polyimide resin.

4. The electrically continuous conductive adhesive film according to claim 1, characterized in that: The conductive functional layer (1) is any one of a conductive non-woven fabric, a carbon nanotube film and a conductive fabric, and the average pore spacing of the conductive fabric is less than 50 μm.

5. The electrically continuous conductive adhesive film according to claim 4, characterized in that: The surface density of the conductive functional layer (1) is 1 to 100 g / m 2 .

6. The electrically continuous conductive adhesive film according to claim 4, characterized in that: The thickness of the conductive functional layer (1) is 0.01 to 0.2 mm.

7. The electrically continuous conductive adhesive film according to claim 4, characterized in that: The surface resistance of the conductive functional layer (1) is 0.0001-5Ω / □.

8. A method for preparing an electrically continuous conductive adhesive film as claimed in any one of claims 1 to 7, characterized in that: The method comprises the following steps: Determining an average diameter of the conductive particles according to the thickness of the adhesive film, wherein the average diameter of the conductive particles is greater than the thickness of the resin film; Heat the resin to melt at a set melting temperature, add the conductive particles into the molten resin, and stir until the conductive particles and the resin are evenly mixed to form a resin mixture; forming the cooled resin mixture into a film by a hot melt method; The adhesive film is compounded with the conductive functional layer, and subjected to hot pressing and hardening in a cooling stage to obtain an electrically continuous conductive adhesive film.

9. The method for preparing an electrically continuous conductive adhesive film according to claim 8, characterized in that: The surface density of the film is 20 to 100 g / m 2 .

10. The method for preparing an electrically continuous conductive adhesive film according to claim 8, characterized in that: The surface density of the electrically continuous conductive film is 30 to 150 g / m 2 .

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