Macroporous high-strength aramid fiber honeycomb core as well as preparation method and preparation mold thereof

Abstract

The invention discloses a large-cell high-strength aramid fiber honeycomb core and a preparation method and a preparation mold thereof, the aramid fiber honeycomb core comprises a plurality of layers of aramid fiber thick paper, the upper and lower surfaces of the aramid fiber thick paper are alternately hot-melted and bonded together at equal intervals, and a plurality of through-hole cells which are arranged in parallel at intervals and have regular hexagonal cross sections are formed between two adjacent layers of aramid fiber thick paper; the material is prepared by a specific preparation mold and a preparation method. According to the method, high-weight aramid paper can be subjected to honeycomb cell lamination molding, then a honeycomb core with large cell size, regular cell size, stable structure and thick cell wall can be prepared, the mechanical properties such as compression strength and shear strength of the honeycomb core are improved, the bonding strength between paper is high, the thermal stability is good, the defects such as cell cracking and deformation are avoided, and the quality of the honeycomb core is improved. In addition, the method has the advantage of environment-friendly production process.

Description

Technical Field

[0001] The invention relates to the technical field of aramid paper materials, and in particular to a large-cell high-strength aramid honeycomb core and a preparation method and a preparation mold thereof. Background Art

[0002] Aramid paper honeycomb has a series of excellent properties such as light weight, high strength and high modulus, flame retardancy, high temperature resistance, and low dielectric loss. It has become the preferred core material for advanced composite honeycomb sandwich structures. It has been widely used as a secondary load-bearing structural member in aerospace, rail transit and other fields. It plays an important role in reducing structural quality and improving the processing performance of related parts.

[0003] As described in patents such as CN108215339 A "A high-strength aramid paper honeycomb core and its manufacturing method" and CN 106794653A "Honeycomb structure core with high compressive strength", the traditional honeycomb core preparation method generally includes the steps of gluing, laminating, hot pressing and curing, stretching and shaping, dipping, drying and curing, and slicing the hot-pressed aramid honeycomb paper. Among them, the key to the successful preparation of the honeycomb core is to use a suitable core strip glue to gluing the aramid honeycomb paper. Since the hot-pressed aramid honeycomb paper itself has a high mechanical strength, when the aramid honeycomb paper after gluing and hot pressing is stretched and shaped, if the gluing process is improper or the bonding strength of the core strip glue is insufficient, it often causes quality defects such as cell cracking and deformation, thereby adversely affecting the mechanical strength and dimensional stability of the honeycomb core. In addition, since high-quantity aramid paper has higher stiffness and bending resistance, when its absolute dry quantity exceeds 100g / m 2 In the above, the traditional core strip glue coating and curing process makes it difficult to stretch and shape the multi-layered high-quantity aramid paper into a honeycomb core structure with regular dimensions. Therefore, if you want to increase the quantitative thickness of the aramid honeycomb paper to increase the thickness and support strength of the aramid fiber body in the honeycomb cell wall and develop a high-strength aramid honeycomb core with higher compression strength and shear strength, the traditional preparation process is not applicable. Therefore, further, due to the limited quantitative thickness of the aramid thick paper, the mechanical strength of the honeycomb cell wall is also limited, so that the cell size of the traditional honeycomb core is also limited, and the cell side length is usually in the range of about 1.6mm~5.0mm. Summary of the invention

[0004] The present invention provides an aramid honeycomb core with large pores and high-strength material properties, which has higher compression strength and shear strength under the same or lower density conditions, as well as a preparation method and a preparation mold for the above-mentioned aramid honeycomb core, to solve the technical problems mentioned in the background technology.

[0005] In order to solve the above technical problems, the technical solution proposed by the present invention is: A mold for preparing an aramid honeycomb core comprises an upper mold plate, a plurality of hexagonal prism templates and a lower mold plate, wherein the hexagonal prism template comprises a plurality of hexagonal prisms and a fixed frame for fixing the hexagonal prisms, wherein the fixed frame is detachably fixedly connected to the hexagonal prisms, wherein the plurality of hexagonal prisms are arranged laterally at equal intervals, and the interval between adjacent hexagonal prisms is the side length of the hexagonal prisms; the lower surface of the upper mold plate and the upper surface of the lower mold plate are both provided with a plurality of spaced-apart semi-hexagonal prism protrusions, so that the upper mold plate, the hexagonal prism templates and the lower mold plate can be staggered, matched, inlaid and overlapped to form an integral structure.

[0006] As a further preferred embodiment of the above technical solution, screw holes are provided at corresponding positions on both sides of the upper mold plate and on both sides of the lower mold plate, and the upper mold plate, the plurality of hexagonal prism templates and the lower mold plate are fixed by bolts and the screw holes after being overlapped.

[0007] As a further preferred embodiment of the above technical solution, the side length of the hexagonal prism is 5-30 mm, and the column height is 100-1000 cm.

[0008] As a further preferred embodiment of the above technical solution, the fixed frame and the hexagonal prism are detachably connected and fixed by bolts.

[0009] Based on the same technical concept, the present invention also provides a method for preparing an aramid honeycomb core, which is prepared by using the aramid honeycomb core preparation mold described in the above technical solution, and comprises the following steps: S1, performing aging and demoulding treatment on the surfaces of the upper mold platen, the hexagonal prism template and the lower mold platen; S2, laying a layer of aramid thick paper that has not been heat-pressed between the surfaces of adjacent hexagonal prism templates, and after the laying is completed, the layer of hexagonal prism templates is staggered and matched with the adjacent layer of hexagonal prism templates, and the two adjacent layers of aramid thick paper are in contact with each other through the gaps of the hexagonal prism templates; overlapping the stacked hexagonal prism templates with the upper mold plate and the lower mold plate, and fixing them with bolts and screw holes to form an integral structure; S3, heating the whole structure, in order to fully heat the aramid paper in the mold to above its glass transition temperature, so as to produce interlayer hot melt bonding, the surface temperature of the mold needs to be heated to 300-360°C, and kept warm for 20-60 minutes; maintaining the surface temperature of the upper mold pressing plate at 285-330°C, and pressing the upper mold pressing plate vertically downward for hot pressing treatment; S4, after the hot pressing is completed, the fixed frame is removed, and the hexagonal prisms are pulled out layer by layer to obtain a honeycomb core intermediate product; the honeycomb core intermediate product is impregnated and cured in an impregnating resin to obtain the aramid honeycomb core.

[0010] As a further preferred embodiment of the above technical solution, in step S1, a release agent is applied to the surfaces of the upper mold plate, the hexagonal prism template and the lower mold plate, and then heat treated at 200-320° C. for 60-200 min to complete the aging and demolding treatment.

[0011] As a further preferred embodiment of the above technical solution, the absolute dry weight range of the aramid thick paper in step S2 is 80-800 g / m 2 , the moisture content range is 5%~70%; or the aramid thick paper has an absolute dry weight range of 30~80g / m 2 , composed of multiple layers of low-weight aramid paper with a moisture content ranging from 5% to 70%.

[0012] As a further preferred embodiment of the above technical solution, the aramid thick paper is one of para-aramid paper and meta-aramid paper. The components of the aramid thick paper include at least one of para-aramid fibrid, para-aramid short fibers, meta-aramid fibrid and meta-aramid short fibers.

[0013] As a further preferred embodiment of the above technical solution, a plurality of overlapping hexagonal column templates are overlapped with an upper mold plate and a lower mold plate, and fixed by bolts and screw holes to form an integral structure, and then an insulation layer is used to wrap the four sides of the integral structure; the insulation layer is an insulating asbestos felt.

[0014] As a further preferred embodiment of the above technical solution, before the heating described in step S3, in order to remove excess moisture in the aramid paper, the overall structure is placed in an oven for drying at a drying temperature of 80-160° C. and a drying time of 1-2 hours.

[0015] As a further preferred embodiment of the above technical solution, the hot pressing pressure of the hot pressing treatment in step S3 is 25-60 MPa, and the hot pressing time is 1-10 min.

[0016] As a further optimization of the above technical solution, after step S3 completes the hot pressing treatment of the upper mold plate by vertically pressing downward, the overall structure is inverted, the dimension of the lower mold plate is maintained at 285~320℃, and the lower mold plate is vertically pressed downward for hot pressing treatment. The hot pressing pressure of the hot pressing treatment is 5~60MPa, and the hot pressing time is 5~15min.

[0017] As a further preferred embodiment of the above technical solution, the impregnating resin in step S4 includes at least one of phenolic resin, polyimide resin, polyetherimide and epoxy resin; the number of dipping is 1 to 4 times, and after each dipping, it is dried at 50 to 80°C for 10 to 30 minutes, and then pre-cured at 90 to 145°C for 15 to 40 minutes. After the last dipping, it is cured at 160 to 200°C for 60 to 200 minutes.

[0018] Based on the same technical concept, the present invention also provides a large-pore high-strength aramid honeycomb core, comprising multiple layers of aramid thick paper whose upper and lower surfaces are alternately hot-melt-bonded at equal intervals, and a plurality of parallel and spaced through-hole grids with regular hexagonal cross-sections are formed between two adjacent layers of aramid thick paper. A certain amount of impregnating resin material is adsorbed on the surface and interior of each layer of the aramid thick paper. The large-pore high-strength aramid honeycomb core is prepared by the preparation method described in the above technical solution.

[0019] As a further preferred embodiment of the above technical solution, the impregnating resin accounts for 25% to 80% of the total mass of the entire aramid honeycomb core.

[0020] As a further preferred embodiment of the above technical solution, the side length of the regular hexagonal through-hole grid is 5 to 30 mm.

[0021] The present invention has the following beneficial effects: The present invention uses a hexagonal lamination mold to heat-press and bond aramid thick paper, and can perform honeycomb lamination shaping on high-quantity aramid paper, thereby obtaining a honeycomb core with larger cell size and thicker cell wall. The increase in cell wall thickness increases the number of aramid fibers that can withstand mechanical stress in the honeycomb cells, thereby obtaining an aramid honeycomb core with better mechanical properties such as compression strength and shear strength. The aramid paper is hot-pressed and shaped at high temperature by a standard-sized hexagonal lamination mold, so that an aramid honeycomb core with more regular cell size and more stable structure can be obtained. At the same time, since the aramid thick paper of adjacent layers is hot-melt bonded by the aramid fiber body, the bonding strength is higher and the bonding thermal stability is better, and defects such as cell cracking and deformation will not occur. In addition, the present invention can also avoid the use of node glue containing organic solvents such as phenolic resin and epoxy resin, so that there is no VOC (volatile organic compound) emission during the hot pressing and curing process of aramid paper, and the production process is more environmentally friendly.

[0022] The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 This is a schematic structural diagram of a macroporous high-strength aramid honeycomb core of Example 1; Figure 2 This is a schematic diagram of the mold structure for preparing the aramid honeycomb core of Example 1; Figure 3 This is a schematic diagram of laying aramid thick paper in a preparation mold in step (2) of Example 1; Figure 4This is a schematic diagram of pre-pressing aramid thick paper using a preparation mold in step (2) of Example 1.

[0024] Legend: 1. Upper mold plate; 2. Lower mold plate; 3. Hexagonal prism; 4. Fixed frame; 5. Screw hole; 6. Aramid thick paper. DETAILED DESCRIPTION

[0025] The embodiments of the present invention are described in detail below with reference to the accompanying drawings, but the present invention can be implemented in many different ways as defined and covered by the claims.

[0026] Embodiment 1: The large-cell high-strength aramid honeycomb core of this embodiment has a structure as follows: Figure 1 As shown, it includes multiple layers of aramid thick paper (meta-aramid paper) with alternately equal intervals between the upper and lower surfaces and hot-melt bonded together, and multiple parallel and spaced through-hole grids with regular hexagonal cross-sections are formed between two adjacent layers of aramid thick paper. A certain amount of impregnating resin material is adsorbed on the surface and inside of each layer of aramid thick paper. The side length of the regular hexagonal through-hole grid is 8mm, and the impregnating resin content is 43% of the total mass. The density of the aramid honeycomb core is 48g / m 3 .

[0027] The mold for preparing the large-cell high-strength aramid honeycomb core of this embodiment is as follows: Figure 2 As shown, it includes: an upper mold plate 1, a multi-layer hexagonal prism template (with a side length of 8 mm and a column height of 950 mm) and a lower mold plate 2, all of which are made of steel. The hexagonal prism template consists of a plurality of hexagonal prisms 3 arranged in parallel horizontally and a fixed frame 4 for fixing the hexagonal prisms 3. The fixed frame 4 is detachably fixedly connected to the upper and lower surfaces of the hexagonal prisms 3 by bolts, and the spacing between adjacent hexagonal prisms 3 is the side length of the hexagonal prisms 3; screw holes 5 are provided at corresponding positions on both sides of the upper mold plate 1 and on both sides of the lower mold plate 2, and a plurality of spaced-apart semi-hexagonal prism protrusions (the shape and arrangement of the semi-hexagonal prism protrusions are consistent with the hexagonal prisms in the hexagonal prism template) are provided on the lower surface of the upper mold plate 1 and the upper surface of the lower mold plate 2, so that the upper mold plate 1, the hexagonal prism template and the lower mold plate 2 can be staggered, matched, inlaid and overlapped, and fixed by bolts and screw holes 5 to form an integral structure.

[0028] The preparation process of the large-cell high-strength aramid honeycomb core of this embodiment includes the following steps: (1) Mold surface demolding treatment: A layer of silicone grease demolding agent is applied to the surface of each layer of the hexagonal prism template, the lower surface of the upper mold pressing plate 1, and the upper surface of the lower mold pressing plate 2 of the preparation mold of this embodiment, and then the preparation mold is subjected to a surface heat aging treatment at 300° C. for 120 min; (2) Pre-pressing of aramid paper layers: Figure 3The absolute dry weight of the hexagonal prism templates processed in step (1) and laid layer by layer from bottom to top without hot pressing is 168 g / m 2 Meta-aramid thick paper base paper, the absolute dry weight is 168g / m 2 The meta-aramid thick paper is made of 4 layers with an absolute dry weight of 42g / m 2 , the meta-aramid wet paper with a moisture content of 58% is flatly stacked to obtain the result, wherein the proportion of the intermediate precipitated fibers in the meta-aramid wet paper is 47 parts, and the proportion of the intermediate short-cut fibers is 53 parts. While completing the laying of each layer of aramid thick paper, the hexagonal prism template or the upper and lower mold plates that are in contact with the upper and lower aramid thick paper layer are interlaced and pre-pressed together in parallel with the hexagonal prism template, so that each adjacent two layers of aramid honeycomb paper can contact each other through the gap of the hexagonal prism template, such as Figure 4 The screw holes 5 at the four corners of the upper mold pressing plate 1 and the lower mold pressing plate 2 are fixed with long bolts to form an integral structure of the preparation mold, and the four sides of the preparation mold except the upper mold pressing plate 1 and the lower mold pressing plate 2 are wrapped with multi-layer asbestos felt for thermal insulation protection; (3) Drying: The prepared mold is then transferred as a whole to an oven for drying at a temperature of 120°C for 1.5 h. (4) Heating: The prepared mold that has been dried in step (3) is further heated in an oven until the surface temperature of the template rises to 330° C. and then kept warm for 20 minutes; (5) Hot pressing: The prepared mold is transferred as a whole to a flat press, and the upper mold plate 1 is quickly hot-pressed vertically downward while maintaining the surface temperature of the upper mold plate 1 above 300°C. The pressing pressure is 30 MPa and the pressing time is 2 min. After the pressing is completed, the prepared mold is turned over so that the lower mold plate 2 faces upward, and then transferred to a flat press and the lower mold plate 2 is quickly hot-pressed vertically downward. The pressing pressure is 35 MPa and the pressing time is 8 min.

[0029] (6) Demolding: Cool the prepared mold to room temperature, remove the asbestos felt, bolts and the fixed frames 4 of each layer of the hexagonal prism template, and extract the hexagonal prisms 3 layer by layer to obtain an unimpregnated aramid honeycomb core intermediate product; (7) Dipping and curing: The intermediate product is dipped in an impregnating resin and then cured to obtain an aramid paper honeycomb block. The impregnating resin used is a phenolic resin diluted with 60% by mass of ethanol. The number of dips is 2 times. After the first dip, it is treated in a 70°C oven for 25 minutes, and then pre-cured at 135°C for 30 minutes. After the second dip, it is cured at 180°C for 150 minutes. (8) Slicing: The aramid honeycomb core that has been impregnated and cured is sliced ​​on a honeycomb-specific slicer using a diamond band saw and a high-power servo motor to obtain the aramid honeycomb core of this embodiment. The table advance speed of the slicer is controlled at 45 mm / min, and the linear speed of the band saw is 5000 mm / min. Embodiment 2: The large-cell high-strength aramid honeycomb core of this embodiment has a structure similar to that of Embodiment 1, the only difference being that the content of impregnated resin in the aramid honeycomb core of this embodiment is 42% of the total mass.

[0030] The mold for preparing the large-cell high-strength aramid honeycomb core of this embodiment is consistent with that of Example 1.

[0031] The preparation process of the large-cell high-strength aramid honeycomb core of this embodiment includes the following steps: (1) Mold surface demolding treatment: A layer of silicone grease demolding agent is applied to the surface of each layer of the hexagonal prism template, the lower surface of the upper mold pressing plate 1, and the upper surface of the lower mold pressing plate 2 of the preparation mold of this embodiment, and then the preparation mold is subjected to a surface heat aging treatment at 300° C. for 120 min; (2) Pre-pressing of aramid paper layers: Lay the layers from bottom to top between the hexagonal prism templates treated in step (1). The absolute dry weight without hot pressing is 164 g / m 2 Para-aramid thick paper base paper, the absolute dry weight is 164g / m 2 The meta-aramid thick paper is made of 4 layers with an absolute dry weight of 41g / m 2 , the meta-aramid wet paper with a moisture content of 57% is flatly stacked to obtain the same, wherein the intermediate precipitated fibers of the para-aramid wet paper account for 47 parts, and the para-chopped fibers account for 53 parts. While completing the laying of each layer of aramid thick paper, the hexagonal prism template or the upper mold plate 1 and the lower mold plate 2 that are in contact with the upper and lower layers of the aramid thick paper are interlaced and pre-pressed together in parallel with the hexagonal prism template, so that each adjacent two layers of aramid honeycomb paper can contact each other through the gap of the hexagonal prism template. The screw holes at the four corners of the upper mold plate 1 and the lower mold plate 2 are fixed with long bolts to form an integral structure of the preparation mold, and the four sides of the preparation mold except the upper mold plate 1 and the lower mold plate 2 are wrapped with multiple layers of asbestos felt for thermal insulation protection; (3) Drying: The prepared mold is then transferred as a whole to an oven for drying at a temperature of 120°C for 1.5 h. (4) Heating: The prepared mold that has been dried in step (3) is further heated in an oven until the surface temperature of the template rises to 330° C. and then kept warm for 25 minutes; (5) Hot pressing: The prepared mold is transferred as a whole to a flat press, and the upper mold plate 1 is quickly hot-pressed vertically downward while maintaining the surface temperature of the upper mold plate 1 above 310°C. The pressing pressure is 30 MPa and the pressing time is 3 min. After the pressing is completed, the prepared mold is turned over so that the lower mold plate 2 faces upward, and then transferred to a flat press. The surface temperature of the lower mold plate 2 is maintained above 305°C, and the lower mold plate 2 is quickly hot-pressed vertically downward. The pressing pressure is 35 MPa and the pressing time is 8 min.

[0032] (6) Demolding: Cool the prepared mold to room temperature, remove the asbestos felt, bolts and the fixed frames 4 of each layer of the hexagonal prism template, and extract the hexagonal prisms 3 layer by layer to obtain an unimpregnated aramid honeycomb core intermediate product; (7) Dipping and curing: The intermediate product is dipped in an impregnating resin and then cured to obtain an aramid paper honeycomb block. The impregnating resin used is a phenolic resin diluted with 60% by mass of ethanol. The number of dips is 2 times. After the first dip, it is treated in a 70°C oven for 25 minutes, and then pre-cured at 135°C for 30 minutes. After the second dip, it is cured at 180°C for 150 minutes. (8) Slicing: The aramid honeycomb core that has been impregnated and cured is sliced ​​on a honeycomb-specific slicer using a diamond band saw and a high-power servo motor to obtain the aramid honeycomb core of this embodiment. The table advance speed of the slicer is controlled at 45 mm / min, and the linear speed of the band saw is 5000 mm / min. Comparative Example 1: Using 0.08 mm thick meta-aramid paper and conventional phenolic resin as impregnation resin, the cell side length prepared by the traditional process (technical solution of CN108215339 A) is 3.0 mm and the honeycomb density is 64 g / m 3 , meta-aramid honeycomb core with a glue content of 48%.

[0033] Comparative Example 2: Using 0.08mm thick para-aramid paper and conventional phenolic resin as impregnation resin, the cell side length prepared by the traditional process (technical solution of CN108215339 A) is 3.0mm and the honeycomb density is 64g / m 3 Para-aramid honeycomb core with a glue content of 47%.

[0034] The aramid honeycomb cores of Example 1, Example 2 and Comparative Example 1, Comparative Example 2 were tested and compared in terms of stable compressive strength, shear strength, and shear modulus. The results are shown in Table 1: Table 1. Performance test results of the aramid honeycomb core of each embodiment and comparative example

[0035] From the test comparison results in the above table, it can be seen that the specifications prepared in Example 1 and Example 2 are 8.0mm-48kg / m 3 The compression strength, shear strength and shear modulus of the macrocellular inter- and para-cellular honeycomb cores are higher than those of the honeycomb cores prepared in Comparative Examples 1 and 2, and the specifications are 3.0 mm-64 kg / m 3 The meta-aramid honeycomb core has been significantly improved compared with the comparative aramid honeycomb core, and the compression strength and shear strength performance are improved by more than 10%. This shows that the aramid honeycomb core obtained by the preparation mold and preparation method of the present invention can provide higher mechanical properties without increasing the weight, so it is more suitable for use as a lightweight load-bearing structural component in the aerospace field.

[0036] In addition, in actual use, according to the needs of performance optimization and improvement, higher strength composite materials such as polyimide fiber, aramid III fiber, carbon fiber and other high-strength fibers, or a higher quantitative range such as 800g / m2~6000g / m 2 The aramid honeycomb paper is used as the raw material of the honeycomb core, and the honeycomb core material obtained by producing the preparation method and the preparation mold of the present invention is also within the protection scope of this patent. The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. For those skilled in the art, improvements and changes obtained without departing from the technical concept of the present invention should also be regarded as the protection scope of the present invention.

[0037] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A mold for preparing an aramid honeycomb core, characterized in that: The invention comprises an upper mold plate (1), a plurality of hexagonal prism templates and a lower mold plate (2), wherein the hexagonal prism template comprises a plurality of hexagonal prisms (3) and a fixed frame (4) for fixing the hexagonal prisms (3), wherein the fixed frame (4) is detachably fixedly connected to the hexagonal prisms (3), wherein the plurality of hexagonal prisms (3) are arranged horizontally at equal intervals, and the interval between adjacent hexagonal prisms (3) is the side length of the hexagonal prisms (3); the lower surface of the upper mold plate (1) and the upper surface of the lower mold plate (2) are both provided with a plurality of semi-hexagonal prism protrusions arranged at intervals, so that the upper mold plate (1), the hexagonal prism template and the lower mold plate (2) can be staggered, matched, inlaid and overlapped to form an integral structure.

2. The aramid honeycomb core preparation mold according to claim 1, characterized in that: Screw holes (5) are provided at corresponding positions on both sides of the upper mold plate (1) and on both sides of the lower mold plate (2); the upper mold plate (1), the plurality of hexagonal prism templates and the lower mold plate (2) are fixed by bolts and the screw holes (5) after being overlapped.

3. The aramid honeycomb core preparation mold according to claim 1, characterized in that: The side length of the hexagonal prism (3) is 5-30 mm, and the height of the prism is 100-1000 cm.

4. A method for preparing an aramid honeycomb core, characterized in that: The aramid honeycomb core preparation mold according to any one of claims 1 to 3 is prepared, comprising the following steps: S1, performing aging and demoulding treatment on the surfaces of the upper mold plate (1), the hexagonal prism template and the lower mold plate (2); S2, laying layers of aramid thick paper that have not been heat-pressed between the surfaces of adjacent hexagonal prism templates, and after the laying is completed, interlacing and matching the hexagonal prism template of this layer with the hexagonal prism template of the adjacent layer, so that each two adjacent layers of aramid thick paper are in contact with each other through the gaps between the hexagonal prism templates; overlapping the stacked hexagonal prism templates with the upper mold plate (1) and the lower mold plate (2), and fixing them with bolts and screw holes (5) to form an overall structure; S3, heating the whole structure to a surface temperature of 300-360°C, and keeping the temperature for 20-60 minutes; maintaining the surface temperature of the upper mold pressing plate (1) at 285-330°C, and applying pressure vertically downward to the upper mold pressing plate (1) for hot pressing; S4, after the hot pressing is completed, the fixed frame (4) is removed, and the hexagonal prisms (3) are extracted layer by layer to obtain a honeycomb core intermediate product; the honeycomb core intermediate product is impregnated and cured in an impregnating resin to obtain the aramid honeycomb core.

5. The method for preparing an aramid honeycomb core according to claim 4, characterized in that: In step S1, a release agent is applied to the surfaces of the upper mold plate (1), the hexagonal prism template and the lower mold plate (2), and then heat-treated at 200-320° C. for 60-200 minutes to complete the aging and demoulding treatment.

6. The method for preparing an aramid honeycomb core according to claim 4, characterized in that: The absolute dry weight range of the aramid thick paper in step S2 is 80-800 g / m 2 , the moisture content range is 5%~70%; or the aramid thick paper has an absolute dry weight range of 30~80g / m 2 , composed of multiple layers of low-weight aramid paper with a moisture content ranging from 5% to 70%.

7. The method for preparing an aramid honeycomb core according to claim 4, characterized in that: A plurality of superimposed hexagonal column templates are superimposed on an upper mold plate (1) and a lower mold plate (2), and fixed by bolts and screw holes (5) to form an integral structure, and then a thermal insulation layer is used to wrap the four sides of the integral structure; the thermal insulation layer is a thermal insulation asbestos felt.

8. The method for preparing an aramid honeycomb core according to claim 4, characterized in that: Before the heating in step S3, the whole structure is placed in an oven for drying at a temperature of 80-160° C. for a drying time of 1-2 hours.

9. The method for preparing an aramid honeycomb core according to claim 4, characterized in that: The hot pressing pressure of the hot pressing treatment in step S3 is 25-60 MPa, and the hot pressing time is 1-10 min.

10. The method for preparing an aramid honeycomb core according to claim 4, characterized in that: After the upper mold plate (1) is subjected to hot pressing treatment by vertically pressing downwards in step S3, the whole structure is inverted, the dimension of the lower mold plate (2) is maintained at 285-320°C, and the lower mold plate (2) is subjected to vertically pressing downwards for hot pressing treatment, wherein the hot pressing pressure of the hot pressing treatment is 5-60 MPa and the hot pressing time is 5-15 min.

11. The method for preparing an aramid honeycomb core according to any one of claims 4 to 10, characterized in that: The impregnation resin in step S4 includes at least one of phenolic resin, polyimide resin, polyetherimide and epoxy resin; the number of dipping is 1 to 4 times, and after each dipping, it is dried at 50 to 80° C. for 10 to 30 minutes, and then pre-cured at 90 to 145° C. for 15 to 40 minutes. After the last dipping, it is cured at 160 to 200° C. for 60 to 200 minutes.

12. A large-cell high-strength aramid honeycomb core, characterized in that: It comprises multiple layers of aramid thick paper whose upper and lower surfaces are alternately hot-melt-bonded at equal intervals, and a plurality of through-hole grids with regular hexagonal cross-sections arranged in parallel and at intervals are formed between two adjacent layers of aramid thick paper. A certain amount of impregnating resin material is adsorbed on the surface and inside of each layer of the aramid thick paper. The large-pore high-strength aramid honeycomb core is prepared by the preparation method described in any one of claims 4 to 11.

13. The large-cell high-strength aramid honeycomb core according to claim 12, characterized in that: The impregnation resin accounts for 25% to 80% of the total mass of the entire aramid honeycomb core.

14. The large-cell high-strength aramid honeycomb core according to claim 12 or 13, characterized in that: The side length of the regular hexagonal through-hole grid is 5-30 mm.

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