Functional composite board and preparation method thereof

Abstract

The invention discloses a functional composite board and a preparation method thereof, the functional composite board comprises a first surface back board and a second surface back board, a honeycomb is arranged between the first surface back board and the second surface back board, in-situ foaming filling is carried out in the honeycomb, the filled foaming material is polyimide foam, and the first surface back board and the second surface back board are arranged in the honeycomb. The middle density layer of the polyimide foam is larger than the density layers on the upper and lower sides. The functional composite board has good noise reduction and sound absorption performance, flame retardant performance, mechanical performance and certain wave absorption performance.

Description

Technical Field

[0001] The invention relates to the field of composite materials, and in particular to a functional composite board and a preparation method thereof. Background Art

[0002] Energy conservation is the development trend of today's society. Honeycomb materials have been widely used in building insulation, especially in lightweight houses and vehicle bulkhead filling. However, due to the porous structure of honeycomb materials, they are inherently deficient in sound insulation and heat preservation. Therefore, people usually cover the honeycomb panels on both sides to improve their sound insulation and heat preservation performance.

[0003] Since the flame retardant effect of adhesives is usually poor and will gradually fall off with the increase of years of use, the sound insulation and heat preservation performance of honeycomb materials will gradually lose. Therefore, the staff in this field began to use foam materials to fill the honeycomb holes of honeycomb panels to obtain better and more stable sound insulation and heat preservation performance. However, the commonly used foam materials, such as polystyrene foam and polyurethane foam, are generally poor in flame retardancy and often have great safety hazards.

[0004] After searching, Chinese patent document CN215970377U discloses a lightweight sound insulation composite board, including a prepreg layer, an adhesive layer, and a honeycomb foam material. The prepreg layer is composed of prepreg and is respectively arranged on the upper surface and the lower surface of the honeycomb foam material; the adhesive layer is composed of an adhesive and is arranged between the prepreg layer and the honeycomb foam material; the honeycomb foam material is an aramid honeycomb filled with a foam material, and the density of the honeycomb foam material is 300-800kg / m 3 , with a thickness of 5-30mm; wherein the foaming material in the aramid honeycomb increases in density from top to bottom; and is formed in one piece. Aramid honeycomb is made of aramid paper through a series of processes such as gluing, laminating, hot pressing, stretching and shaping, dipping and curing, and slicing. It is compounded with the skin material into a sandwich structure, which can greatly reduce the weight of the component and has advantages in many aspects such as effective weight reduction, corrosion reduction, noise improvement, damping and shock absorption. However, the cost of aramid honeycomb is relatively expensive and cannot be widely used in the civilian field. And the prepreg layer needs to be separately provided with an adhesive layer for bonding.

[0005] Chinese patent document CN215512691U discloses a flame-retardant honeycomb panel. The flame-retardant honeycomb panel includes an aramid honeycomb, an upper melamine fiber product and a lower melamine fiber product. The aramid honeycomb panel is arranged in the middle position as a core material; an upper melamine fiber product is arranged on the aramid honeycomb panel as an upper surface; and a lower melamine fiber product is arranged under the aramid honeycomb panel as a lower surface. The honeycomb panel, foam filling material, etc. used are all highly flame-retardant materials, and the flame-retardant honeycomb panel obtained inherits their high flame-retardant properties. The surface layer used is a melamine fiber material, and its density is much lower than the commonly used metal or mineral surface layer materials. However, the melamine fiber has obvious deficiencies in terms of lightweight compared to glass fiber and carbon fiber, and due to the large skeleton structure of melamine, its noise reduction effect is poor.

[0006] Chinese patent document CN105563970A discloses a composite material structure with a PMI core, a preparation method and an application thereof, comprising a core material (I) and a skin layer (II) arranged on the upper and lower surfaces of the core material (I), wherein the skin layer is composed of a resin-based fiber-reinforced composite material, the core material (I) is PMI foam, and the specific gravity of the core material (I) is 75 kg / m 3 -200kg / m 3 , with a thickness of 0.4mm-5.0mm. The composite material structure of the PMI foam sandwich prepared by the invention has excellent properties such as high strength, light weight, good interlayer bonding, not easy to delaminate and split, impact resistance, high temperature resistance, and corrosion resistance. At the same thickness, its strength is comparable to that of aluminum alloy, and its weight is less than a quarter of that of aluminum alloy. The full name of PMI foam is polymethacrylimide foam. Compared with traditional foam, it has the properties of high strength, light weight, good rigidity, halogen-free, and high temperature resistance. It is the most superior closed-cell engineering foam. It still requires a transition film bonding layer (III) to cooperate with the skin layer (II) and the core material (I) as an adhesive to increase the bonding force between the two.

[0007] However, the above-mentioned prior art does not disclose, nor does it provide any technical inspiration on how to achieve a certain wave absorbing performance by setting up a filled foam material structure. Summary of the invention

[0008] In view of this, the object of the present invention is to provide a functional composite board and a preparation method thereof, which can achieve certain wave absorbing performance by setting a filled foam material structure.

[0009] The technical solutions adopted are: A functional composite board of the present invention comprises a first back plate and a second back plate, wherein a honeycomb is provided between the first back plate and the second back plate, wherein in-situ foaming and filling is performed in the honeycomb, wherein the filling foaming material is polyimide foam, wherein the middle density layer of the polyimide foam is greater than the density layers on the upper and lower sides.

[0010] Furthermore, the first back plate and the second back plate are both composed of a single layer or multiple layers of carbon / glass fiber, and the carbon / glass fiber is a composite of carbon fiber and glass fiber connected by epoxy resin to form an integral body.

[0011] Furthermore, the honeycomb is an aluminum honeycomb.

[0012] A method for preparing a functional composite board according to the present invention comprises the following steps: S1. Laying the honeycomb on the second backplane; S2. Mixing an aromatic dianhydride and an aromatic diamine in an organic solvent to obtain a polyamide ester solution; dividing the polyamide ester solution into three parts, including a first part, a second part and a third part, wherein a small amount of a closed-cell foaming agent and a foam stabilizer are added to the first part and stirred evenly, and a part of the organic solvent is dried to obtain a first polyimide precursor; a large amount of a closed-cell foaming agent and a foam stabilizer are added to the second part and the third part, respectively, and stirred evenly, and a part of the organic solvent is dried to obtain a second polyimide precursor and a third polyimide precursor; S3. Adding a second polyimide precursor, a first polyimide precursor and a third polyimide precursor sequentially into the honeycomb; S4. Lay the first backplane on the honeycomb and perform heat pressing treatment. Fill and foam the second polyimide precursor, the first polyimide precursor and the third polyimide precursor in the cavity of the honeycomb and solidify and shape them to obtain a functional composite board.

[0013] Furthermore, in step S4, the heat treatment temperature is 150-200° C. and the pressure is 0.3-0.5 MPa.

[0014] Furthermore, in step S2, the aromatic dianhydride is one or more of 1,2,4,5-pyromellitic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 2,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-biphenyl tetracarboxylic dianhydride, and 2,3',4,4'-biphenyl tetracarboxylic dianhydride; the aromatic diamine is one or more of p-diphenylamine, m-diphenylamine, 4,4'-diaminodiphenyl ether, and 3,4'-diaminodiphenyl ether.

[0015] Furthermore, the molar ratio of the aromatic dianhydride to the aromatic diamine is 0.9-1.1:1.

[0016] Furthermore, the foam stabilizer is one or more of polymethylsiloxane, polyethersiloxane, and vinylpolysiloxane.

[0017] Furthermore, the closed-cell foaming agent is an aqueous solution of aluminum hydroxide.

[0018] Furthermore, the organic solvent is one or more of tetrahydrofuran, N,N-dimethylformamide and dimethyl sulfoxide.

[0019] The beneficial effects of the present invention are: 1. Because the sandwich structure is filled with polyimide foam, the strength and stiffness of the pure honeycomb core material are improved. The polyimide foam is used as the structural unit of the sandwich structure, and the fiber layer of the face and back panels can be reduced appropriately.

[0020] 2. During the use of honeycomb sandwich structures, the surface is easily damaged, fine cracks are generated and water is soaked in, and it will expand under low or high temperature conditions. However, for closed-cell polyimide foam-filled foam, water and water vapor cannot enter the core material, reducing maintenance costs, so the life cost of the honeycomb sandwich structure filled with polyimide foam is more economical.

[0021] 3. The filling foam material is polyimide (PI), which is a polymer with better flame retardancy, higher thermal stability and lower smoke toxicity. Polyimide foam (PIF) can be used as a bulkhead interlayer thermal insulation and sound absorption material due to its excellent basic physical and chemical properties and thermal insulation and noise reduction functions.

[0022] 4. In terms of sound insulation and noise reduction, the noise, vibration and harshness (NVH) of honeycomb cores filled with polyimide foam is lower than that of composite laminates because they have inherent damping properties. If used as vehicle parts, cabin parts, etc., the foam-filled honeycomb structure brings a more luxurious and comfortable driving experience.

[0023] 5. The surface of CN215970377U is a prepreg layer with a separate adhesive layer; the surface of the present invention can be further selected as a glass fiber layer, that is, the first back plate and the second back plate of the present invention are both composed of a single layer or multiple layers of carbon / glass fiber, and the carbon / glass fiber is a carbon fiber and a glass fiber connected and composited by epoxy resin to form a whole. In addition, the cost of aramid honeycomb is relatively expensive and cannot be widely used in the civilian field. The present invention can further select the honeycomb as an aluminum honeycomb core material, which can significantly reduce the cost.

[0024] 6. The front and back panel structure in CN215512691U uses melamine fiber, which is obviously inferior to glass fiber and carbon fiber in terms of lightness, and because the skeleton structure of melamine is large, its noise reduction effect is poor. The carbon fiber and glass fiber used in the present invention are connected and composited into one by epoxy resin, which has an advantage in noise reduction effect.

[0025] 7. The present invention fills the honeycomb with lightweight closed-cell polyimide foam to seal the pores and prevent epoxy resin from flowing into the honeycomb voids during processing. Compared with open-cell foaming agents, foam plastics made from closed-cell foaming agents have higher density, harder texture, better compression resistance, heat preservation and sound insulation properties. Aluminum hydroxide has a closed-cell effect during the preparation process and also has certain flame retardancy.

[0026] 8. In the present invention, the density of the middle layer of polyimide foam is greater than the density of the upper and lower layers, thereby forming a similar "core-shell" structure. The honeycomb filled with polyimide foam having the core-shell structure has certain wave absorbing properties. DETAILED DESCRIPTION

[0027] The present invention is described in detail below through specific examples, but the use and purpose of these exemplary implementation modes are only used to illustrate the present invention, and do not constitute any form of limitation on the actual protection scope of the present invention, nor limit the protection scope of the present invention to them. Example 1

[0028] A functional composite board of this embodiment includes a first back plate and a second back plate, an aluminum honeycomb is arranged between the first back plate and the second back plate, in-situ foaming and filling is performed in the aluminum honeycomb, the foaming material of the filling is polyimide foam, and the middle density layer of the polyimide foam is greater than the density layers on the upper and lower sides. The first back plate and the second back plate are both composed of a single layer of carbon / glass fiber, and the carbon / glass fiber is a carbon fiber and a glass fiber connected and composited into one by epoxy resin.

[0029] The method for preparing the functional composite board comprises the following steps: S1. Laying the honeycomb on the second backplane; S2. Add 29.421 g (0.1 mol) of 2,3,3′,4′-biphenyltetracarboxylic acid dianhydride to 70 g of tetrahydrofuran (THF) solvent, heat and reflux at 75°C until the solution becomes transparent, to obtain a 2,3,3′,4′-biphenyl dicarboxylic acid diester solution; dissolve 10.814 g (0.1 mol) of m-phenylenediamine in 44 g of tetrahydrofuran solvent to obtain a m-phenylenediamine solution; slowly add the m-phenylenediamine solution to the 2,3,3′,4′-biphenyl dicarboxylic acid diester solution, stir and react for 2 h, to obtain 154.235 g of polyamide ester solution; The polyamide ester solution is evenly divided into three parts, including a first part, a second part and a third part, wherein 5 g of an aluminum hydroxide aqueous solution and 0.8 g of polymethylsiloxane are added to the first part and stirred evenly, and a part of the organic solvent is dried to remove, thereby obtaining a first polyimide precursor; 10 g of an aluminum hydroxide aqueous solution and 0.8 g of polymethylsiloxane are added to the second part and the third part, respectively, and stirred evenly, and a part of the organic solvent is dried to remove, respectively, to obtain a second polyimide precursor and a third polyimide precursor; S3. Adding a second polyimide precursor, a first polyimide precursor and a third polyimide precursor sequentially into the honeycomb; S4. Lay the first back panel on the honeycomb and perform heat pressing treatment. Under the condition of nitrogen protection, the heat treatment temperature is 200°C, the pressure is 0.5MPa, and the heat preservation is carried out for 2 hours. The second polyimide precursor, the first polyimide precursor and the third polyimide precursor are filled and foamed in the cavity of the honeycomb, and cured and formed to obtain a functional composite board.

[0030] The honeycomb core material was divided into three positions: upper, middle and lower for density testing. The density of the upper and lower positions was 112kg / m 3 ; The density in the middle is 256kg / m 3 . Comparative Example 1

[0031] Referring to Example 1, the difference from Example 1 is that the filled polyimide foam has a relatively uniform density overall. In the preparation method, the polyamide ester solution is not divided into three times, but the polyimide precursor is prepared once and loaded into the honeycomb at one time.

[0032] The honeycomb core material is divided into three positions: upper, middle and lower for density testing. The density of the upper, middle and lower positions is 160±2kg / m 3 . Comparative Example 2

[0033] Referring to Example 1, the difference from Example 1 is that the foaming agent is replaced by water instead of the aluminum hydroxide aqueous solution.

[0034] The functional composite panels prepared in Example 1 and Comparative Examples 1-2 were subjected to performance tests. The test results are shown in Table 1 below.

[0035] Table 1 Sound absorption coefficient Limiting oxygen index Smoke density / Ds Compression strength / Mpa Reflectivity R in the frequency range of 5-10GHZ Example 1 ＞0.6 ≥32% ＜10 3.62 ≤-8 Comparative Example 1 ＞0.5 ≥32% ＜10 2.84 ≤-1 Comparative Example 2 ＞0.5 20%-24% ＜16 1.98 ≤-7 It can be seen from Table 1 that the functional composite board of Example 1 has certain wave absorbing performance, which indicates that the honeycomb filled with polyimide foam having a core-shell structure has certain wave absorbing performance.

[0036] The functional composite board of Example 1 has a strong compressive strength, which indicates that the functional composite board prepared by the closed-cell foaming agent has good mechanical properties.

[0037] The series of detailed descriptions listed above are only specific descriptions of feasible embodiments of the present invention. They are not intended to limit the scope of protection of the present invention. All equivalent embodiments or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A functional composite board, It is characterized in that It comprises a first back plate and a second back plate, wherein a honeycomb is arranged between the first back plate and the second back plate, wherein the honeycomb is in-situ foamed and filled, and the filling foaming material is polyimide foam, wherein the middle density layer of the polyimide foam is greater than the density layers on the upper and lower sides.

2. The functional composite panel according to claim 1, It is characterized in that The first back plate and the second back plate are both composed of a single layer or multiple layers of carbon / glass fiber, and the carbon / glass fiber is a composite of carbon fiber and glass fiber connected by epoxy resin to form an integral body.

3. The functional composite panel according to claim 1, It is characterized in that The honeycomb is an aluminum honeycomb.

4. A method for preparing the functional composite board according to any one of claims 1 to 3, It is characterized in that The steps include: S1. Laying the honeycomb on the second backplane; S2. Mixing an aromatic dianhydride and an aromatic diamine in an organic solvent to obtain a polyamide ester solution; dividing the polyamide ester solution into three parts, including a first part, a second part and a third part, wherein a small amount of a closed-cell foaming agent and a foam stabilizer are added to the first part and stirred evenly, and a part of the organic solvent is dried to obtain a first polyimide precursor; a large amount of a closed-cell foaming agent and a foam stabilizer are added to the second part and the third part, respectively, and stirred evenly, and a part of the organic solvent is dried to obtain a second polyimide precursor and a third polyimide precursor; S3. Adding a second polyimide precursor, a first polyimide precursor and a third polyimide precursor sequentially into the honeycomb; S4. Lay the first backplane on the honeycomb and perform heat pressing treatment. Fill and foam the second polyimide precursor, the first polyimide precursor and the third polyimide precursor in the cavity of the honeycomb and solidify and shape them to obtain a functional composite board.

5. The method for preparing the functional composite board according to claim 4, It is characterized in that In step S4, the heat treatment temperature is 150-200°C and the pressure is 0.3-0.5 MPa.

6. The method for preparing the functional composite board according to claim 4, It is characterized in that In step S2, the aromatic dianhydride is one or more of 1,2,4,5-pyromellitic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 2,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-biphenyl tetracarboxylic dianhydride, and 2,3',4,4'-biphenyl tetracarboxylic dianhydride; the aromatic diamine is one or more of p-diphenylamine, m-diphenylamine, 4,4'-diaminodiphenyl ether, and 3,4'-diaminodiphenyl ether.

7. The method for preparing the functional composite board according to claim 6, It is characterized in that The molar ratio of the aromatic dianhydride to the aromatic diamine is 0.9-1.1:

1.

8. The method for preparing the functional composite board according to claim 4, It is characterized in that The foam stabilizer is one or more of polymethylsiloxane, polyethersiloxane and vinylpolysiloxane.

9. The method for preparing the functional composite board according to claim 4, It is characterized in that The closed-cell foaming agent is an aqueous solution of aluminum hydroxide.

10. The method for preparing the functional composite board according to claim 4, It is characterized in that The organic solvent is one or more of tetrahydrofuran, N,N-dimethylformamide and dimethyl sulfoxide.