Micro-nano porous pyramid structure light absorption composite material and preparation method thereof

Abstract

The invention provides a preparation method of a light-absorbing composite material with a micro-nano porous pyramid structure, which comprises the following steps: preparing a metal flat plate of which the surface part is full of pyramids as a template, coating a carbon nano polymer mixed prepolymer on the template, putting the coated template into a pressurizing container, curing, and demolding, thereby obtaining the light-absorbing composite material with the micro-nano porous pyramid structure. The light absorption composite material with the micro-nano porous light absorption structure on the surface is obtained. The surface of the obtained material has a smooth and fine micro-nano porous pyramid structure with good matching degree with a template. When being used as a light-absorbing material, the material has high light-absorbing efficiency. And during a BRDF test, the composite material always keeps a relatively low BRDF value.

Description

Technical Field

[0001] This invention relates to light-absorbing composite materials. Background Technology

[0002] Stray light refers to harmful illumination on the image plane of a photoelectric system caused by partial radiation entering the system. Space-based optical detection systems are highly susceptible to stray light interference during operation. This not only reduces image contrast and signal-to-noise ratio, but in severe cases, the target signal can be completely overwhelmed by stray light, leading to optical imaging or detection failure. Stray light interference has become a key factor limiting the ability of space-based target detection systems to detect high-magnitude space targets, and the resulting imaging degradation effect greatly hinders subsequent target identification, detection, and characteristic sensing. Currently, with the continuous improvement of the sensitivity and detection threshold of photoelectric detection devices, higher requirements are being placed on the suppression of stray light in space optical detection systems.

[0003] Currently, high-performance stray light absorbing materials are a bottleneck restricting stray light suppression efficiency, especially for light-absorbing materials that still perform well when stray light is incident at large angles (>60°). Commonly used stray light absorbing materials are mainly based on carbon-based composite coatings. This technology has the advantages of wide absorption frequency band and convenient construction, but its light absorption performance at large angles still falls short of requirements. This invention proposes a light-absorbing composite material based on a micro / nano porous pyramidal structure. It utilizes the micron-sized pyramid and its surface nanoporous structure to increase the path of incident light through multiple reflections and refractions, and pre-places carbon nanomaterials inside the pyramid to absorb light energy, achieving the effect of attenuating incident light. The absorption effect at large angles is significantly better than that of carbon-based composite coatings. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a micro / nano porous pyramidal light-absorbing composite material, characterized by comprising the following steps:

[0005] (1) Prepare a metal plate with a dense array of pyramidal grooves on its surface as a negative template for pyramidal forming;

[0006] (2) Coat the template with a release agent, and then cover the template surface with a carbon nanoparticle polymer hybrid prepolymer;

[0007] (3) The template covered with carbon nanoparticle polymer mixed prepolymer is placed in a pressure container, heated and cured, and then demolded to obtain a light-absorbing composite material with a micro-nano porous pyramidal structure on the surface.

[0008] Furthermore, in step (1), the metal plate is a nickel-based template, and its preparation method is as follows: First, a number of closely arranged pyramidal structures are engraved on the surface of the copper plate using a diamond tool through a precision machining method to serve as a positive mold. The height of the pyramids is in the micrometer range. Then, an electroforming process is used to replicate a metal plate with a number of closely arranged pyramidal groove arrays on the surface of the copper plate positive mold, which is the negative template used for pyramidal forming.

[0009] Furthermore, in step (1), the pyramid is a closely arranged triangular pyramid with a scale of micrometers, the height of the triangular pyramid is 50-200 micrometers, and the length of the base is 25-400 micrometers.

[0010] Further, in step (2), the carbon nanoparticle polymer hybrid prepolymer is a material obtained by mixing carbon nanomaterials with polymer prepolymers; wherein, the content of polymer prepolymers is 95-99.5 wt%; wherein, the carbon nanomaterials are selected from one or a mixture of carbon black, carbon nanotubes or graphene; the polymer prepolymers are selected from a mixture of epoxy resin and amine curing agent, or 4,4'-bismaleimide diphenylmethane.

[0011] In step (2), the epoxy resin is selected from one of the following: bisphenol A type epoxy resin, bisphenol F type epoxy resin, polyphenol type glycidyl ether epoxy resin, aliphatic glycidyl ether epoxy resin, glycidyl ester epoxy resin, glycidyl amine epoxy resin, or alicyclic epoxy resin.

[0012] Furthermore, the mass ratio of epoxy resin to amine curing agent is 10:1.

[0013] Further, in step (3), during the curing process, the coated template is placed in a pressure tank, pressurized, heated, and kept warm and pressurized, and then cooled and depressurized before being taken out of the tank; wherein, the pressure is increased to 0.1-0.5MPa, the temperature is 25-240℃, and the time for keeping warm and pressurizing is 2-12 hours.

[0014] This invention also claims protection for micro / nano porous pyramidal light-absorbing composite materials obtained based on the above method.

[0015] The technical effect of this invention is undeniable. The surface of the composite material obtained has a fine micro-nano porous pyramidal structure with good matching degree with the template, and the absorption rate in the visible light-near infrared band can reach more than 99.5%. Attached Figure Description

[0016] Figure 1 A schematic diagram (top) and a photograph (bottom) of the preparation process of the negative pyramidal nickel-based template;

[0017] Figure 2 A picture of a diamond tool used for ultra-precision machining (left) and a copper template that has been engraved (right);

[0018] Figure 3 A schematic diagram of the fabrication process of a micro / nano porous pyramidal light-absorbing composite material;

[0019] Figure 4 SEM image of the bismaleimide-diphenylmethane micropyramidal high-absorption composite material of Example 1;

[0020] Figure 5 The reflectance curve of the bismaleimide-diphenylmethane micropyramidal high-absorption composite material in Example 1 is shown.

[0021] Figure 6 The BRDF curve of the bismaleimide-diphenylmethane micropyramidal high-absorption composite material in Example 1 is shown.

[0022] Figure 7 SEM image of the bismaleimide-diphenylmethane micropyramidal high-absorption composite material of Example 2;

[0023] Figure 8 The reflectance curve of the bismaleimide-diphenylmethane micropyramidal high-absorption composite material in Example 2 is shown.

[0024] Figure 9 The BRDF curve of the bismaleimide-diphenylmethane micropyramidal high-absorption composite material in Example 2 is shown.

[0025] Figure 10 SEM image of the epoxy-based micropyramidal high-absorption composite material of Example 3;

[0026] Figure 11 The reflectance curve of the epoxy-based micropyramidal high-absorption composite material in Example 3 is shown.

[0027] Figure 12 SEM image of the epoxy-based micropyramidal high-absorption composite material of Example 4;

[0028] Figure 13 The reflectance curve of the epoxy-based micropyramidal high-absorption composite material in Example 4 is shown. Detailed Implementation

[0029] The present invention will be further described below with reference to embodiments, but it should not be construed that the scope of the present invention is limited to the following embodiments. Various substitutions and modifications made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention should be included within the scope of protection of the present invention.

[0030] Example 1

[0031] A method for preparing a micro / nano porous pyramidal light-absorbing composite material, characterized by comprising the following steps:

[0032] (1) Preparation of a metal negative template with a micron-sized pyramidal surface:

[0033] Several micron-sized "positive" triangular pyramids (each triangular pyramid protrusion, 75 microns high, 174 microns on each side) are etched onto the surface of a copper substrate using ultra-precision machining equipment. Then, this micron-sized pyramid structure is replicated onto the surface of a nickel plate using an electroforming process, resulting in a metal plate template with micron-sized "negative" pyramids on its surface (equipped with an array of pyramidal grooves corresponding to the "positive" triangular pyramids, i.e., the negative template).

[0034] (2) Preparation and coating of carbon nanoparticle polymer hybrid prepolymers:

[0035] Carbon black, carbon nanotubes and 4,4'-bismaleimide diphenylmethane were mixed in a ratio of 1:1:98 to obtain a mixed prepolymer, which was then processed into a film with a thickness of 80-150 micrometers on a coating machine.

[0036] After cleaning the surface of the micron-sized pyramidal metal template in step (1), spray a layer of release agent onto its surface using a spray gun. After the solvent in the release agent has completely evaporated, attach the adhesive film obtained in step (2) to the surface of the metal template. The number of adhesive film layers is 1-3. Then, put it into a vacuum bag and evacuate the air to make the metal template and the adhesive film adhere tightly.

[0037] (3) Curing:

[0038] The intermediate obtained in step (2) was placed in a pressurized tank, pressurized at 0.4 MPa, heated, kept at 150℃ for 2 hours, 180℃ for 2 hours, 200℃ for 2 hours, 220℃ for 2 hours, and 240℃ for 4 hours. After cooling and depressurization, the intermediate was taken out of the tank and the metal template was removed to obtain a light-absorbing composite material with a micro-nano porous pyramidal structure on the surface.

[0039] The microstructure of the composite material was observed using a scanning electron microscope, and the reflectance was measured using a visible-near-infrared spectrophotometer equipped with an integrating sphere. The results showed that the absorbance in the visible light range reached 99.4%, confirming the high light absorption efficiency of the present invention.

[0040] Figure 4 This is a SEM microstructure image of the light-absorbing composite material prepared in this implementation case. The side length L of the pyramid is 174 μm, which is consistent with the design.

[0041] Figure 5 This is the reflectance curve of the light-absorbing composite material prepared in this embodiment. The reflectance is less than 0.6% at 0° incident angle. Figure 6 This is the BRDF reflectance curve of the light-absorbing composite material prepared in this embodiment. The data shows its reflectance SR -1 All below 10 -2 .

[0042] Example 2

[0043] A method for preparing a micro / nano porous pyramidal light-absorbing composite material, characterized by comprising the following steps:

[0044] (1) Preparation of a metal negative template with a micron-sized pyramidal surface:

[0045] Several micron-sized positive triangular pyramids (each triangular pyramid protrusion, 75 microns high, 94 microns side length) are engraved on the surface of a copper substrate using ultra-precision machining equipment. Then, the micron-sized pyramid structure is copied to the surface of a nickel plate using an electroforming process to obtain a metal plate template 1 with micron-sized negative pyramids on the surface (which has an array of pyramidal grooves corresponding to the "positive" triangular pyramids, i.e., the negative template).

[0046] (2) Preparation and coating of carbon nanoparticle polymer hybrid prepolymers:

[0047] Carbon black, carbon nanotubes and 4,4'-bismaleimide diphenylmethane were mixed in a ratio of 1:1:98 to obtain a mixed prepolymer, which was then processed into a film with a thickness of 80-150 micrometers on a coating machine.

[0048] After cleaning the surface of the micron-sized pyramidal metal template 1 in step (1), spray a layer of release agent on its surface using a spray gun. After the solvent in the release agent has completely evaporated, attach the adhesive film obtained in step (2) to the surface of the metal template. The number of adhesive film layers is 1-3. Then, put it into a vacuum bag and evacuate the air to make the metal template and the adhesive film adhere tightly.

[0049] (3) Curing:

[0050] The intermediate obtained in step (2) was placed in a pressurized tank, pressurized at 0.4 MPa, heated, kept at 150℃ for 2 hours, 180℃ for 2 hours, 200℃ for 2 hours, 220℃ for 2 hours, and 240℃ for 4 hours. After cooling and depressurization, the intermediate was taken out of the tank and the metal template was removed to obtain a light-absorbing composite material with a micro-nano porous pyramidal structure on the surface.

[0051] The microstructure of the composite material was observed using a scanning electron microscope, and the reflectance was measured using a visible-near-infrared spectrophotometer equipped with an integrating sphere. The results showed that the absorbance in the visible light range reached 99.55%, confirming the high light absorption efficiency of the present invention.

[0052] Figure 7 This is a SEM microstructure image of the light-absorbing composite material prepared in this implementation case. The side length L of the pyramid is 94 μm, which is consistent with the design.

[0053] Figure 8 This is the reflectance curve of the light-absorbing composite material prepared in this embodiment. The reflectance is less than 0.45% at 0° incident angle. Figure 9 This is the BRDF reflectance curve of the light-absorbing composite material prepared in this embodiment. The data shows its reflectance SR at most angles. -1 All below 10 -3 .

[0054] Example 3

[0055] A method for preparing a micro / nano porous pyramidal light-absorbing composite material, characterized by comprising the following steps:

[0056] (1) Preparation of a metal negative template with a micron-sized pyramidal surface:

[0057] Several micron-sized positive triangular pyramids (each triangular pyramid protrusion, 75 microns high and 174 microns on the side) are etched on the surface of a copper substrate using ultra-precision machining equipment. Then, the micron-sized pyramid structure is copied to the surface of a nickel plate using an electroforming process to obtain a metal plate template with micron-sized negative pyramids on the surface (which has an array of pyramidal grooves corresponding to the "positive" triangular pyramids, i.e., the negative template).

[0058] (2) Preparation and coating of carbon nanoparticle polymer hybrid prepolymers:

[0059] Carbon black, carbon nanotubes and epoxy resin (epoxy resin is used in conjunction with a curing agent) are mixed at a ratio of 1:1:98 to obtain a mixed prepolymer, which is then processed into a film with a thickness of 80-150 micrometers on a coating machine.

[0060] After cleaning the surface of the micron-sized pyramidal metal template in step (1), a layer of release agent is sprayed onto its surface using a spray gun. After the solvent in the release agent has completely evaporated, the adhesive film obtained in step (2) is attached to the surface of the metal template and placed in a vacuum bag to remove air, so that the metal template and the adhesive film are tightly bonded.

[0061] (3) Curing:

[0062] The intermediate obtained in step (2) was placed in a pressurized tank, pressurized at 0.4 MPa, heated, and kept at 180°C for 2 hours. After cooling and depressurization, the intermediate was taken out and the metal template was removed to obtain a light-absorbing composite material with a micro-nano porous pyramidal structure on the surface.

[0063] The microstructure of the composite material was observed using a scanning electron microscope, and the reflectance was measured using a visible-near-infrared spectrophotometer equipped with an integrating sphere. The results showed that the absorbance in the visible light range reached 98.5%, confirming the high light absorption efficiency of the present invention.

[0064] Figure 8 This is a SEM microstructure image of the light-absorbing composite material prepared in this embodiment. The side length L of the pyramid is 174 μm, and the surface of the pyramid has a large number of irregular nanoscale pore structures.

[0065] Figure 9 This is the reflectance curve of the light-absorbing composite material prepared in this embodiment, which achieves a reflectance of less than 1.5% at 0° incident angle.

[0066] Example 4

[0067] A method for preparing a micro / nano porous pyramidal light-absorbing composite material, characterized by comprising the following steps:

[0068] (1) Preparation of a metal negative template with a micron-sized pyramidal surface:

[0069] Several micron-sized positive triangular pyramids (each triangular pyramid protrusion, 75 microns high and 94 microns long on each side) are etched onto the surface of a copper substrate using ultra-precision machining equipment. Then, the micron-sized pyramid structure is replicated onto the surface of a nickel plate using an electroforming process to obtain a metal plate template with micron-sized negative pyramids on its surface (which has an array of pyramidal grooves corresponding to the "positive" triangular pyramids, i.e., the negative template).

[0070] (2) Preparation and coating of carbon nanoparticle polymer hybrid prepolymers:

[0071] Carbon black, carbon nanotubes and epoxy resin (epoxy resin is used in conjunction with a curing agent) are mixed at a ratio of 1:1:98 to obtain a mixed prepolymer, which is then processed into a film with a thickness of 80-150 micrometers on a coating machine.

[0072] After cleaning the surface of the micron-sized pyramidal metal template in step (1), a layer of release agent is sprayed onto its surface using a spray gun. After the solvent in the release agent has completely evaporated, the adhesive film obtained in step (2) is attached to the surface of the metal template and placed in a vacuum bag to remove air, so that the metal template and the adhesive film are tightly bonded.

[0073] (3) Curing:

[0074] The intermediate obtained in step (2) was placed in a pressurized tank, pressurized at 0.4 MPa, heated, and kept at 180°C for 2 hours. After cooling and depressurization, the intermediate was taken out and the metal template was removed to obtain a light-absorbing composite material with a micro-nano porous pyramidal structure on the surface.

[0075] The microstructure of the composite material was observed using a scanning electron microscope, and the reflectance was measured using a visible-near-infrared spectrophotometer equipped with an integrating sphere. The results showed that the absorbance in the visible light range reached 99.2%, confirming the high light absorption efficiency of the present invention.

[0076] Figure 10 This is a SEM microstructure image of the composite material prepared in this embodiment. The side length L of the pyramid is 94 μm, and the surface of the pyramid has a large number of irregular nanoscale pore structures.

[0077] Figure 11 This is the reflectance curve of the composite material prepared in this embodiment, which achieves a reflectance of less than 0.75% at 0° incident angle.

Claims

1. A method for preparing a micro / nano porous pyramidal light-absorbing composite material, characterized in that, Includes the following steps: (1) Prepare a metal plate with the array of several pyramidal grooves closely arranged on its surface, as a negative template for pyramidal forming; (2) Coat the template with a release agent, and then cover the template surface with a carbon nanoparticle polymer hybrid prepolymer; (3) The template covered with carbon nanoparticle polymer mixed prepolymer is placed in a pressure container, heated and cured, and then demolded to obtain a light-absorbing composite material with a micro-nano porous pyramidal structure on the surface.

2. The micro / nano porous pyramidal light-absorbing composite material and its preparation method according to claim 1, characterized in that: In step (1), the metal plate is a nickel-based template. The preparation method is as follows: First, a number of closely arranged pyramidal structures are engraved on the surface of the copper plate using a diamond tool through precision machining to serve as a positive mold. The height of the pyramids is in the micrometer range. Then, an electroforming process is used to replicate a metal plate with a number of closely arranged pyramidal groove arrays on the surface of the positive mold of the copper plate, which is the negative template used for pyramidal forming.

3. The micro / nano porous pyramidal light-absorbing composite material and its preparation method according to claim 1, characterized in that: In step (1), the pyramid is a closely arranged triangular pyramid with a scale of micrometers.

4. The micro / nano porous pyramidal light-absorbing composite material and its preparation method according to claim 1, characterized in that: In step (2), the carbon nanoparticle polymer hybrid prepolymer is a material obtained by mixing carbon nanomaterials with polymer prepolymers; The carbon nanomaterial is selected from one or a mixture of carbon black, carbon nanotubes, or graphene.

5. The micro / nano porous pyramidal light-absorbing composite material and its preparation method according to claim 4, characterized in that: The mass ratio of epoxy resin to amine curing agent is 10:

1.

6. The micro / nano porous pyramidal light-absorbing composite material and its preparation method according to claim 1, characterized in that: In step (3), during curing, the coated template is placed in a pressure tank, pressurized, heated, and kept at a constant temperature and pressure, then cooled and depressurized before being taken out of the tank; wherein, the pressure is increased to 0.1-0.5MPa, the temperature is 25-240℃, and the time for keeping at a constant temperature and pressure is 2-12 hours.

7. A micro-nano porous pyramidal light-absorbing composite material obtained by the method according to any one of claims 1 to 6.

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