A multi-layer flexible composite functional film and a preparation method thereof

Abstract

The application provides a multilayer flexible composite functional film and a preparation method thereof, which comprises a film layer 1 and a film layer 2, the film layer 1 comprises an outer film layer and an emission layer, the film layer 2 comprises a reflection layer and an inner film layer, and the structure is sequentially stacked from top to bottom as the outer film layer, the emission layer, the reflection layer and the inner film layer. The material of the inner film layer and the outer film layer is any one of transparent polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF) or polyvinyl chloride (PVC) or a combination thereof, the material of the emission layer is bead-shaped carbon black particles, the infrared emissivity of the outer surface of the functional film is improved, and then the heat is prevented from gathering on the outer surface, so that the outer surface of the functional film is efficiently radiated. The material of the reflection layer is sheet-shaped aluminum, the reflection layer can realize efficient reflection of sunlight, the heat is prevented from being absorbed on the outer surface of the multilayer flexible material in a large amount, and the effect of rapid heat dissipation is achieved.

Description

Technical Field

[0001] This invention belongs to the field of composite materials, specifically relating to a multilayer flexible composite functional membrane for airships and its preparation method. Background Technology

[0002] Flexible composite materials for airships are generally composed of weather-resistant layers, gas-barrier layers, load-bearing layers, and heat-sealing layers. They are a type of functional laminated capsule material. The functional membrane is coated on the outer surface of the multilayer flexible composite material, and its performance level directly affects the application effect of the airship. It mainly plays a role in weather protection. At the same time, the composition and structure of the functional membrane also determine the photothermal properties of the flexible composite material, including solar reflectivity and infrared emissivity. These properties directly determine the heat control effect of the flexible composite material.

[0003] Currently, the functional membrane materials used in flexible composite materials for airships include polyvinylidene fluoride (PVF), polyvinylidene fluoride (PVDF), and polyvinyl chloride (PVC). By adding a certain proportion of titanium dioxide, light stabilizers, and ultraviolet absorbers to these films, the white functional membrane can completely reflect and shield ultraviolet rays from sunlight. However, it cannot effectively shield visible light, especially near-infrared light. Therefore, multilayer flexible composite materials are prone to light transmission under sunlight, leading to increased internal heat and overpressure within the airship, among other problems.

[0004] Furthermore, the infrared emissivity of functional films such as white polyvinylidene fluoride (PVF), polyvinylidene fluoride (PVDF), and polyvinyl chloride (PVC) is generally around 0.5%. This low infrared emissivity easily leads to heat accumulation on the outer surface of the multilayer flexible composite material, preventing timely heat dissipation. Therefore, multilayer flexible composite materials prepared from currently used white PVF, PVDF, or PVC functional films suffer from poor thermal control.

[0005] To address the aforementioned technical problems, the existing technology involves aluminum plating on the surface of flexible composite materials. While this solves some of the issues, the aluminum layer is prone to peeling off, and the problem cannot be completely resolved. Summary of the Invention

[0006] The problem the invention aims to solve

[0007] Therefore, the technical problem to be solved by the present invention is to overcome the problems of low reflectivity, easy light transmission, and increased internal heat and overpressure of existing multilayer flexible composite functional films.

[0008] Furthermore, the study investigated the problems caused by the low emissivity of existing multilayer flexible composite functional films, which leads to heat accumulation on the surface of multilayer flexible composite materials and the inability to dissipate heat in a timely manner.

[0009] Furthermore, this invention provides a multilayer flexible composite functional membrane structure and its preparation method that can solve the above problems.

[0010] Solution for solving the problem

[0011] The present invention has found that the above-mentioned technical problems can be solved by the following technical solutions:

[0012] 1. A multilayer flexible composite functional membrane, wherein the functional membrane structure comprises a thin film layer 1 and a thin film layer 2 stacked sequentially;

[0013] The thickness ratio of thin film layer 1 to thin film layer 2 is 1:2 to 1:3;

[0014] Thin film layer 1 is located above thin film layer 2.

[0015] 2. The functional membrane according to claim 1, wherein the sum of the thicknesses of thin film layer 1 and thin film layer 2 is 15-45 μm.

[0016] 3. The functional film according to claim 1 or 2, wherein the reflectivity is 98.5% to 99.9% and the emissivity is 0.70% to 0.80%.

[0017] 4. The functional membrane according to any one of claims 1-3, wherein the thin film layer 1 comprises an outer thin film layer and an emitting layer, and the thin film layer 2 comprises a reflective layer and an inner thin film layer;

[0018] The outer thin film layer is located above the emitting layer, the emitting layer is located above the reflective layer, and the reflective layer is located above the inner thin film layer.

[0019] 5. The functional membrane according to any one of claims 1-4, wherein the material of the emitting layer is carbon black particles, preferably bead-shaped carbon black particles, distributed in an island-like pattern, the average particle size of the carbon black is 10nm-13nm, preferably 11nm-12nm, and the mass ratio of the emitting layer to the outer thin film layer is 0.5%-3.0%, preferably 1.0%-1.5%; and / or

[0020] Relative tinting strength (IRB3): 90%–125%, preferably 100%–110%; and / or

[0021] Ash content: 0.4% to 0.8%, preferably 0.5% to 0.6%.

[0022] 6. The functional membrane according to claim 5, wherein the emitting layer is at least one layer, preferably one layer.

[0023] 7. The functional film according to any one of claims 1-4, wherein the reflective layer is made of aluminum, preferably sheet aluminum, and the sheet aluminum has a diameter range of 1-10 μm, preferably 5 μm-10 μm;

[0024] The thickness of the aluminum sheet is 0.1µm to 2.0µm, preferably 0.5µm to 1.0µm;

[0025] The mass ratio of the reflective layer to the inner thin film layer is 15% to 35%, preferably 20% to 30%.

[0026] 8. The functional film according to claim 7, wherein the sheet-like aluminum in the reflective layer is oriented along the length direction of the film;

[0027] The reflective layer is at least one layer, preferably one to two layers.

[0028] 9. The functional membrane according to any one of claims 1-8, wherein the inner thin film layer and the outer thin film layer are made of any one of transparent polyvinyl fluoride PVF, polyvinylidene fluoride PVDF or polyvinyl chloride PVC or a combination thereof, preferably polyvinyl fluoride PVF and / or polyvinylidene fluoride PVDF.

[0029] 10. The method for preparing the functional membrane according to any one of claims 1-9, comprising obtaining thin film layer 1 and thin film layer 2 respectively, and performing a lamination composite process to achieve the composite between thin film layer 1 and thin film layer 2.

[0030] 11. According to the preparation method of claim 10, bead-shaped carbon black particles are added to the outer thin film layer to prepare thin film layer 1;

[0031] Thin film layer 2 is prepared by adding sheet-like aluminum to the inner thin film layer.

[0032] 12. The application of the functional membrane according to any one of claims 1-9, or / and the functional membrane prepared by the preparation method according to claim 10 or 11, in the preparation of multilayer flexible composite materials for airships.

[0033] The effects of the invention

[0034] Based on the implementation of the above technical solution, the present invention can achieve the following technical effects:

[0035] (1) This invention proposes a multilayer flexible composite material functional membrane with optimized structure and material. It includes a thin film layer 1 and a thin film layer 2. The thin film layer 1 includes an outer thin film layer and an emitting layer, and the thin film layer 2 includes a reflective layer and an inner thin film layer. From top to bottom, the outer thin film layer, emitting layer, reflective layer and inner thin film layer are stacked in sequence. This functional membrane structure has a high solar reflectivity, as well as an infrared emission design and a high infrared emissivity. The two work together to achieve the effect of rapid heat control.

[0036] (2) The present invention further optimizes the material composition of the inner and outer film layers, preferably any one of transparent polyvinyl fluoride PVF, polyvinylidene fluoride PVDF or polyvinyl chloride PVC or a combination thereof, preferably polyvinyl fluoride PVF and / or polyvinylidene fluoride PVDF.

[0037] (3) The present invention further optimizes the structure of the emission layer. The material of the emission layer is bead-shaped carbon black particles, which are distributed in an island-like manner. The average particle size of the carbon black is 10-13 nm. The mass ratio of the emission layer to the outer film layer is 0.5%-3.0%, which improves the infrared emissivity of the outer surface of the functional film and avoids the accumulation of heat on the outer surface, thereby achieving efficient heat dissipation on the outer surface of the functional film.

[0038] (4) The present invention further optimizes the structure of the reflective layer. The material of the reflective layer is sheet aluminum with a sheet diameter range of 1 to 10 μm and a sheet thickness of 0.1 to 2.0 μm. The mass ratio of the reflective layer to the inner film layer is 15% to 35%. The reflective layer can achieve efficient reflection of sunlight, avoid heat absorption on the outer surface of the multilayer flexible material, and achieve rapid heat dissipation. Attached Figure Description

[0039] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0040] Figure 1 This is a schematic diagram of a functional membrane structure.

[0041] The attached figures are labeled as follows:

[0042] 1-Thin film layer 1, 2-Thin film layer 2, 3-Functional film structure, 11-Outer thin film layer, 12-Emitting layer, 21-Reflecting layer, 22-Inner thin film layer. Detailed Implementation

[0043] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0045] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0046] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0047] <First Aspect>

[0048] The first aspect of this invention discloses a multilayer flexible composite functional membrane:

[0049] A multilayer flexible composite functional membrane includes a thin film layer 1 and a thin film layer 2 stacked sequentially, wherein the thickness ratio of thin film layer 1 to thin film layer 2 is 1:2 to 1:3, thin film layer 1 is located above thin film layer 2, and its reflectivity is 98.5% to 99.9%, its emissivity is 0.70% to 0.80%, and its thickness is 15 to 45 μm.

[0050] The thin film layer 1 is divided into an outer thin film layer and an emitting layer, and the thin film layer 2 is divided into a reflective layer and an inner thin film layer. The outer thin film layer is located above the emitting layer, the emitting layer is located above the reflective layer, and the reflective layer is located above the inner thin film layer.

[0051] The outer film layer is made of any one of transparent polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), or polyvinyl chloride (PVC) or a combination thereof, preferably polyvinyl fluoride (PVF) and / or polyvinylidene fluoride (PVDF).

[0052] The material of the emission layer is carbon black particles, preferably bead-shaped carbon black particles, distributed in an island-like pattern. The average particle size of the carbon black is 10nm to 13nm, preferably 11nm to 12nm. The relative tinting strength (IRB3) is 90% to 125%, preferably 100% to 110%. The ash content is 0.4% to 0.8%, preferably 0.5% to 0.6%. The mass ratio of the emission layer to the outer film layer is 0.5% to 3.0%, preferably 1.0% to 1.5%.

[0053] The emission layer is at least one layer, preferably one layer.

[0054] The reflective layer is made of aluminum, preferably sheet aluminum, with a sheet diameter ranging from 1 to 10 μm, preferably 5 μm to 10 μm, and a sheet thickness of 0.1 μm to 2.0 μm, preferably 0.5 μm to 1.0 μm. The mass ratio of the reflective layer to the inner thin film layer is 15% to 35%, preferably 20% to 30%; and / or

[0055] The sheet-like aluminum in the reflective layer is oriented along the length of the thin film; and / or

[0056] The reflective layer is at least one layer, preferably one to two layers.

[0057] The inner film layer is made of any one of transparent polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), or polyvinyl chloride (PVC) or a combination thereof, preferably polyvinyl fluoride (PVF) and / or polyvinylidene fluoride (PVDF).

[0058] The inner film and the outer film layer are made of the same material.

[0059] <Second aspect>

[0060] The second aspect of this invention discloses a method for preparing a multilayer flexible composite functional membrane:

[0061] Step 1: Add bead-shaped carbon black particles to transparent polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), or polyvinyl chloride (PVC) and perform biaxial stretching to form a transparent film with dispersed carbon black particles. That is, add bead-shaped carbon black particles to the outer film layer, wherein the number of carbon black layers is at least one, preferably one, and the mass ratio of the emission layer to the outer film layer is 0.5% to 3.0%, preferably 1.0% to 1.5%, to form film layer 1;

[0062] Step 2: Add sheet aluminum to transparent polyvinylidene fluoride (PVF), polyvinylidene fluoride (PVDF), or polyvinyl chloride (PVC) for biaxial stretching. Under the biaxial stretching of the film, the sheet aluminum is oriented parallel to the longitudinal and transverse directions of the film. The mass ratio of the reflective layer to the inner film layer is 15% to 35%, preferably 20% to 30%. That is, the sheet aluminum is added to the inner film layer, wherein the number of sheet aluminum layers is at least 1, preferably 1 to 2, to form film layer 2.

[0063] Step 3: Composite thin film layer 1 and thin film layer 2 into a functional membrane material. The thickness ratio of thin film layer 1 to thin film layer 2 is 1:2 to 1:3.

[0064] <Third aspect>

[0065] The third aspect of this invention discloses an application of a multilayer flexible composite functional membrane:

[0066] Application of the multilayer flexible composite functional membrane and the functional membrane prepared by the preparation method in the preparation of multilayer flexible composite materials for airships.

[0067] Furthermore, the application of the functional membrane in the airship airship capsule material.

[0068] This invention proposes a multilayer flexible composite functional membrane structure and its preparation method, which differs from the currently used white functional membrane heat control structure in the following ways and has the following advantages: First, the solar reflective layer composed of sheet aluminum has a higher solar reflectivity than the white functional membrane; second, the white functional membrane heat control structure lacks active infrared emission design and function, i.e., it does not have an emission layer composed of carbon black particles. In contrast, the heat control structure proposed in this invention features active heat emission design, and the infrared emission layer composed of carbon black can effectively emit the heat accumulated on the outer surface of the functional membrane, resulting in stronger heat dissipation capacity. Through the synergistic effect of these two aspects, the multilayer flexible composite functional membrane of this invention exhibits a strong heat control effect.

[0069] To better understand the functional membrane structure proposed in this invention, two examples are provided for illustration.

[0070] Example 1

[0071] The polyvinylidene fluoride (PVDF) functional film is 25 μm thick and is transparent. The film structure, from top to bottom, consists of an outer film layer, a carbon black emitting layer, a sheet-like aluminum reflective layer, and an inner film layer. The carbon black heat dissipation layer is composed of bead-like carbon black particles distributed in an island-like pattern. The average carbon black particle size is 11 nm, the ash content is 0.5%, and the mass ratio of carbon black to the outer film layer is 1.0%. Sheet-like aluminum is oriented and arranged in the film to form a sheet-like aluminum reflective layer, with one layer. The mass ratio of sheet-like aluminum to the inner film layer is 20%, and the sheet-like aluminum has a diameter of 2 μm and a thickness of 0.1 μm. Both the outer and inner film layers are made of PVDF. The thickness ratio of film layer 1 to film layer 2 is 1:1.

[0072] Preparation method:

[0073] Step 1: Add bead-shaped carbon black particles to transparent polyvinylidene fluoride (PVDF) and perform biaxial stretching to form a transparent film with dispersed carbon black particles, forming film layer 1;

[0074] Step 2: Add sheet aluminum to transparent polyvinylidene fluoride (PVDF) and perform biaxial stretching. Under the action of biaxial stretching, the sheet aluminum is oriented parallel to the longitudinal and transverse directions of the film to form film layer 2.

[0075] Step 3: Combine thin film layer 1 and thin film layer 2 to form a functional membrane material, with the thickness ratio of thin film layer 1 to thin film layer 2 being 1:1.

[0076] The PVDF functional film with the above structure has a solar reflectance of 98.5% and an infrared emissivity of 0.72.

[0077] Example 2

[0078] The polyvinyl fluoride (PVF) functional film is 40µm thick and transparent. The film structure, from top to bottom, consists of an outer film layer, a carbon black emitting layer, a sheet-like aluminum reflective layer, and an inner film layer. The carbon black heat dissipation layer is composed of bead-like carbon black particles distributed in an island-like pattern. The average carbon black particle size is 12nm, the ash content is 0.8%, and carbon black accounts for 3.0% of the mass of the outer film layer. The sheet-like aluminum reflective layer consists of two layers, with a mass ratio of sheet aluminum to the inner film layer of 30%. The sheet aluminum has a diameter range of 4µm and a thickness of 0.1µm. Both the outer and inner film layers are made of PVF. The thickness ratio of film layer 1 to film layer 2 is 1:2.

[0079] Preparation method:

[0080] Step 1: Add bead-shaped carbon black particles to transparent polyvinyl fluoride PVF and perform biaxial stretching to form a transparent film with dispersed carbon black particles, forming film layer 1;

[0081] Step 2: Add sheet aluminum to transparent polyvinyl fluoride PVF and perform biaxial stretching. Under the action of biaxial stretching of the film, the sheet aluminum is oriented parallel to the longitudinal and transverse directions of the film. Two layers of sheet aluminum are set to form film layer 2.

[0082] Step 3: Composite thin film layer 1 and thin film layer 2 into a functional membrane material, with the thickness ratio of thin film layer 1 to thin film layer 2 being 1:2.

[0083] The PVF functional film with the above structure has a solar reflectance of 99.0% and an infrared emissivity of 0.78.

[0084] Table 1. Thermal control effect of different functional membranes

[0085]

[0086]

[0087] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A multilayer flexible composite functional membrane for airships, characterized in that, The functional membrane structure consists of a first thin film layer (1) and a second thin film layer (2) stacked sequentially. The thickness ratio of the first thin film layer (1) to the second thin film layer (2) is 1:2 to 1:3; The first thin film layer (1) is located above the second thin film layer (2); The sum of the thicknesses of the first thin film layer (1) and the second thin film layer (2) is 15-45 μm; Its solar reflectance is 98.5%–99.9%, and its infrared emissivity is 0.72 or 0.

78. The first thin film layer (1) includes an outer thin film layer and an emitting layer, and the second thin film layer (2) includes a reflective layer and an inner thin film layer; The outer thin film layer is located above the emitting layer, the emitting layer is located above the reflective layer, and the reflective layer is located above the inner thin film layer; The material of the emission layer is bead-shaped carbon black particles, distributed in an island-like pattern; The reflective layer is made of sheet aluminum, which is oriented parallel to the longitudinal and transverse directions of the film.

2. The functional membrane according to claim 1, characterized in that, The carbon black particles in the emission layer have an average particle size of 10 nm to 13 nm, a carbon black to outer film layer mass ratio of 0.5% to 3.0%, and / or a relative tinting strength IRB3 of 90% to 125%, and / or an ash content of 0.4% to 0.8%.

3. The functional membrane according to claim 2, characterized in that, The carbon black particles in the emission layer have an average particle size of 11 nm to 12 nm, a carbon black to outer film layer mass ratio of 1.0% to 1.5%, and / or a relative tinting strength IRB3 of 100% to 110%, and / or an ash content of 0.5% to 0.6%.

4. The functional membrane according to claim 3, characterized in that, The emission layer is at least one layer.

5. The functional membrane according to claim 4, characterized in that, The emission layer is a single layer.

6. The functional membrane according to claim 5, characterized in that, The sheet aluminum of the reflective layer has a sheet diameter ranging from 1 μm to 10 μm, a sheet thickness ranging from 0.1 μm to 2.0 μm, and a mass ratio of sheet aluminum to inner thin film layer of 15% to 35%.

7. The functional membrane according to claim 6, characterized in that, The sheet aluminum of the reflective layer has a sheet diameter ranging from 5 μm to 10 μm, a sheet thickness ranging from 0.5 μm to 1.0 μm, and a mass ratio of sheet aluminum to inner thin film layer of 20% to 30%.

8. The functional membrane according to any one of claims 1-7, characterized in that, The inner and outer film layers are made of any one of transparent polyvinylidene fluoride (PVF), polyvinylidene fluoride (PVDF), or polyvinyl chloride (PVC), or a combination thereof.

9. The functional membrane according to claim 8, characterized in that, The inner and outer film layers are made of polyvinylidene fluoride (PVF) and / or polyvinylidene fluoride (PVDF).

10. The method for preparing the functional membrane according to any one of claims 1-9, characterized in that, This includes obtaining a first thin film layer (1) and a second thin film layer (2) respectively; and using a lamination process to achieve the composite between the first thin film layer (1) and the second thin film layer (2).

11. The preparation method according to claim 10, characterized in that, Beaded carbon black particles are added to the outer film layer to prepare the first film layer (1); flake aluminum is added to the inner film layer to prepare the second film layer (2).

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