Preparation method of high-toughness carbon fiber paper honeycomb core material

Abstract

The invention belongs to the technical field of composite material honeycomb core material manufacturing, and particularly discloses a preparation method of a high-toughness carbon fiber paper honeycomb core material. By introducing the high-toughness epoxy resin, the surface of the carbon fiber paper is coated with the high-toughness epoxy resin in the surface treatment process of the carbon fiber paper and the first impregnation process of the honeycomb, so that pores in the surface of the carbon fiber paper are sealed; and the problem that the overall toughness of the carbon fiber honeycomb is reduced due to the fact that impregnating resin enters the carbon fiber paper in the subsequent impregnation process is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of composite honeycomb core material manufacturing, and specifically relates to a method for preparing a high-toughness carbon fiber paper honeycomb core material. The process method can be used for preparing carbon fiber paper honeycombs to improve the toughness of the carbon fiber paper honeycombs. Background Art

[0002] In the future, aircraft will develop towards faster flight speed, longer range and high maneuverability, which puts higher requirements on the strength and stiffness of honeycomb core materials. A structural schematic diagram of an existing honeycomb core material is shown in Figure 1 As shown. Obviously, the existing aramid paper honeycomb can no longer meet the requirements of future aircraft for honeycomb core materials. Carbon fiber honeycomb is made of carbon fiber as raw material. Carbon fiber has higher strength and stiffness, which can ensure that the honeycomb has better mechanical properties. At the same time, compared with traditional aramid paper honeycomb core materials, carbon fiber honeycomb core materials can be prepared into honeycomb core materials with different temperature resistance levels and different mechanical properties by changing the types of resin and fiber to meet the design and use requirements. In addition, the sandwich structure panels commonly used in the aerospace field are generally made of carbon fiber prepreg. The thermal expansion coefficients of existing aramid paper honeycomb core materials, aluminum honeycomb core materials and foam core materials are all different from those of carbon fiber panels. When the temperature of the use environment changes greatly, the difference in the thermal expansion coefficients of the materials will cause the structure to produce large internal stress, and even cause structural deformation or failure in severe cases. The carbon fiber honeycomb core material has the same thermal expansion coefficient as the carbon fiber panel material, which can reduce the internal stress during manufacturing and use and avoid related problems caused by the difference in expansion coefficients. However, carbon fiber paper has a large internal porosity. Compared with aramid paper of the same specification, the porosity of carbon fiber paper is more than 4 times. Due to the structural characteristics of carbon fiber paper, if the traditional honeycomb dipping method is used, it is very easy to have the problem of poor toughness of the honeycomb and its pore walls, which affects the processing and subsequent use of the honeycomb material. Summary of the invention

[0003] 1. Technical issues to be resolved

[0004] The technical problem to be solved by the present invention is that the strength and rigidity of the honeycomb core material are not sufficient to meet the needs of the rapid development of aircraft.

[0005] (II) Technical solution

[0006] In order to solve the above technical problems, the present invention provides a method for preparing a high-toughness carbon fiber paper honeycomb core material, comprising the steps of:

[0007] S1. The carbon fiber paper is primed with a first high-toughness epoxy resin solution and then subjected to high-temperature treatment to obtain a high-toughness treated carbon fiber paper;

[0008] S2. A carbon fiber paper honeycomb core material to be impregnated with the high toughness treated carbon fiber paper is prepared;

[0009] S3. The carbon fiber paper honeycomb core material to be impregnated is impregnated in a second high-toughness epoxy resin solution, and then cured at high temperature to obtain a toughened carbon fiber paper honeycomb core material;

[0010] S4. The toughened carbon fiber paper honeycomb core material is impregnated with a phenolic resin solution until the carbon fiber paper honeycomb density reaches the preset density requirement of 32 kg / m 3 -72㎏ / m 3 , and then solidified to prepare a high-toughness carbon fiber paper honeycomb core material.

[0011] As a preferred embodiment of the present invention, in step S1, the high-toughness epoxy resin in the first high-toughness epoxy resin solution is a high-temperature curing epoxy resin, and the curing temperature is 170°C to 200°C.

[0012] As a preferred embodiment of the present invention, the high-toughness epoxy resin in the first high-toughness epoxy resin solution is a mixture of bisphenol A epoxy resin, bisphenol F epoxy resin, glycidyl ester epoxy resin, and phenolic resin, and the mass ratio of each component in the mixture is bisphenol A epoxy resin: bisphenol F epoxy resin: glycidyl ester epoxy resin: phenolic resin = (15-45): (8-25): (10-20): (5-20).

[0013] As a preferred embodiment of the present invention, a toughening agent is further added to the first high-toughness epoxy resin solution, and the toughening agent is selected from one or more of polyethersulfone and polyetheretherketone, and the mass fraction of the toughening agent in the first high-toughness epoxy resin solution is 15% to 35%.

[0014] As a preferred embodiment of the present invention, the solvent used in the first high-toughness epoxy resin solution is selected from one of ethanol, toluene, acetone and ethyl acetate.

[0015] As a preferred embodiment of the present invention, the solid content of the first high-toughness epoxy resin solution is 0.5% to 10%.

[0016] The solid content refers to the weight of the first high-toughness epoxy resin solution after drying divided by the total weight of the first high-toughness epoxy resin solution before drying.

[0017] As a preferred embodiment of the present invention, step S2 specifically comprises using the high-toughness treated carbon fiber paper as raw material, adopting a stretching method, and preparing the carbon fiber paper honeycomb core material to be impregnated through four steps of gluing, pressing, stretching and shaping;

[0018] The core strip adhesive used in the gluing process is phenolic modified epoxy resin adhesive, the resin solvent is ethyl acetate or acetone, and the resin viscosity is 30-180Cp during gluing;

[0019] During the pressing process, the node glue curing temperature is 150-190°C, the pressure is 0.2MPa-1.0MPa, and the curing time is 90min-300min;

[0020] During the shaping process, the shaping temperature is 150-280°C.

[0021] As a preferred embodiment of the present invention, in step S3, the high-toughness epoxy resin in the second high-toughness epoxy resin solution is a high-temperature curing epoxy resin, and the curing temperature is 170°C to 200°C.

[0022] As a preferred embodiment of the present invention, the high-toughness epoxy resin in the second high-toughness epoxy resin solution is a mixture of bisphenol A epoxy resin, bisphenol F epoxy resin, glycidyl ester epoxy resin, and phenolic resin, and the mass ratio of each component in the mixture is bisphenol A epoxy resin: bisphenol F epoxy resin: glycidyl ester epoxy resin: phenolic resin = (15-45): (8-25): (10-20): (5-20).

[0023] As a preferred embodiment of the present invention, a toughening agent is further added to the second high-toughness epoxy resin solution, and the toughening agent is selected from one or more of polyethersulfone and polyetheretherketone, and the mass fraction of the toughening agent in the second high-toughness epoxy resin solution is 15% to 35%.

[0024] As a preferred embodiment of the present invention, the solvent used in the second high-toughness epoxy resin solution is selected from one of ethanol, toluene, acetone and ethyl acetate.

[0025] As a preferred embodiment of the present invention, the solid content of the second high-toughness epoxy resin solution is 3% to 15%.

[0026] The solid content refers to the weight of the second highest toughness epoxy resin solution after drying divided by the total weight of the second highest toughness epoxy resin solution before drying.

[0027] As a preferred embodiment of the present invention, in step S4, the phenolic resin solution is an aminophenolic resin solution.

[0028] As a preferred embodiment of the present invention, the solvent used in the phenolic resin solution is ethanol or water.

[0029] As a preferred embodiment of the present invention, the solid content of the phenolic resin solution is 25% to 45%.

[0030] Solid content refers to the weight of the phenolic resin solution after drying divided by the total weight of the phenolic resin solution before drying.

[0031] (III) Beneficial effects

[0032] The above technical solution of the present invention has the following advantages:

[0033] Compared with the traditional honeycomb core material impregnation method, the present invention greatly improves the toughness of the carbon fiber paper honeycomb through the toughening treatment of primer coating and the first dipping toughening resin covering, which can effectively avoid the brittle fracture of the honeycomb wall during the processing of the carbon fiber paper honeycomb core material and the local cracking problem during the honeycomb curved surface forming process, so that the toughness of the carbon fiber paper honeycomb basically reaches the toughness level of aramid paper honeycomb, and improves the processability of the carbon fiber paper honeycomb to prepare the sandwich structure. At the same time, due to the higher strength and modulus of the carbon fiber paper honeycomb, it can provide the possibility for further weight reduction and stiffness improvement of the composite material structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic diagram of the structure of an existing honeycomb core material; in the figure: L-longitudinal direction; W-transverse direction; T-height; N-node; B-cell side length; D-inscribed circle diameter;

[0035] Figure 2 A schematic diagram of the preparation process of the high-toughness carbon fiber paper honeycomb core material provided by the present invention. DETAILED DESCRIPTION

[0036] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0037] The honeycomb core material used in the following examples is a carbon fiber paper honeycomb with a carbon fiber paper surface weight of 48 g / m 2 , thickness 0.15mm, honeycomb cell side length 3.0mm, honeycomb height 180mm.

[0038] Example 1

[0039] This embodiment provides a method for preparing a high-toughness carbon fiber paper honeycomb core material. The preparation process flow chart is shown in Figure 2 As shown, the steps include:

[0040] S1. Coating carbon fiber paper with high-toughness epoxy resin primer: After unwinding, the carbon fiber paper enters the high-toughness epoxy resin solution at a speed of 1 m / min to coat the carbon fiber paper with primer. Then the carbon fiber paper enters a high-temperature oven to treat the high-toughness epoxy resin at high temperature for 5 minutes. After the treatment is completed, the paper is rolled up for standby use to obtain a high-toughness treated carbon fiber paper;

[0041] S2. Preparation of honeycomb to be impregnated: Using high-toughness treated carbon fiber paper as raw material, a stretching method is used to prepare a carbon fiber paper honeycomb core material to be impregnated through four steps of gluing, pressing, stretching and shaping;

[0042] S3. Honeycomb high-toughness epoxy resin impregnation: Place the unimpregnated carbon fiber paper honeycomb block into a high-toughness epoxy resin solution, lift the honeycomb out of the resin solution at a lifting speed of 20 mm / min, and then cure the high-toughness epoxy resin in a high-temperature oven to obtain a toughened carbon fiber paper honeycomb core material;

[0043] S4. The toughened carbon fiber paper honeycomb core material is impregnated with a phenolic resin solution until the carbon fiber paper honeycomb density reaches the preset density requirement of 48 kg / m 3 After curing, a high-toughness carbon fiber paper honeycomb core material is prepared.

[0044] In step S1, the high-toughness epoxy resin in the first high-toughness epoxy resin solution is a high-temperature curing epoxy resin, and the curing temperature is 180° C. Specifically, the high-toughness epoxy resin in the first high-toughness epoxy resin solution is a mixture of E51 epoxy resin and E44 epoxy resin, and the mass ratio of the mixture is E51 epoxy resin: E44 epoxy resin = 20:10.

[0045] A toughening agent is also added to the first high-toughness epoxy resin solution. The toughening agent is polyethersulfone, and the mass fraction of the toughening agent in the first high-toughness epoxy resin solution is 20%.

[0046] The solvent used in the first high-toughness epoxy resin solution is ethanol.

[0047] The solid content of the first high-toughness epoxy resin solution is 4%. After the primer coating treatment, the basis weight of the carbon fiber paper increases by 2%.

[0048] The solid content refers to the weight of the first high-toughness epoxy resin solution after drying divided by the total weight of the first high-toughness epoxy resin solution before drying.

[0049] In step S2, the core strip adhesive used in the gluing process is a phenolic modified epoxy resin adhesive, the resin solvent is ethyl acetate, and the resin viscosity is 90Cp during gluing;

[0050] During the pressing process, the node glue curing temperature was 180°C, the pressure was 0.7MPa, and the curing time was 240min;

[0051] During the shaping process, the shaping temperature is 240°C.

[0052] In step S3, the high-toughness epoxy resin in the second high-toughness epoxy resin solution is a high-temperature curing epoxy resin. Specifically, the high-toughness epoxy resin in the second high-toughness epoxy resin solution is a mixture of E51 epoxy resin and E44 epoxy resin, and the mixing ratio of the mixture is E51 epoxy resin: E44 epoxy resin = 20:10.

[0053] A toughening agent is also added to the second high-toughness epoxy resin solution. The toughening agent is polyethersulfone, and the mass fraction of the toughening agent in the second high-toughness epoxy resin solution is 20%.

[0054] Step S3 After the honeycomb is impregnated with high-toughness epoxy resin, the volume density of the carbon fiber paper honeycomb increases by 3kg / m 3 The curing temperature of high-toughness epoxy resin is 180°C and the curing time is 120 minutes. After curing, the density of carbon fiber paper honeycomb is 32kg / m 3 .

[0055] The solvent used in the second high-toughness epoxy resin solution is ethanol; the solid content of the second high-toughness epoxy resin solution is 8%.

[0056] The solid content refers to the weight of the second highest toughness epoxy resin solution after drying divided by the total weight of the second highest toughness epoxy resin solution before drying.

[0057] In step S4, the phenolic resin solution is an aminophenolic resin solution;

[0058] The solvent used for the phenolic resin solution is ethanol;

[0059] The solid content of the phenolic resin solution was 35%.

[0060] Solid content refers to the weight of the phenolic resin solution after drying divided by the total weight of the phenolic resin solution before drying.

[0061] The amount of glue applied to the honeycomb in a single dipping step S4 is ≤5kg / m 3 After 4 times of dipping, the density of the honeycomb reaches 48kg / m 3 The honeycomb is then cured at high temperature to produce a high-toughness carbon fiber paper honeycomb core material.

[0062] The high-toughness carbon fiber paper honeycomb core material prepared in Example 1 has a strength increased by more than 60% and a modulus increased by more than 100% compared with the meta-aramid paper honeycomb core material of the same specification. The toughness of the two honeycombs was compared by bending the honeycomb walls. The results showed that the toughness of the two honeycombs was basically the same. Compared with the carbon fiber paper honeycomb that did not adopt the impregnation process, the toughness was increased by about 35%.

[0063] In other embodiments, the carbon fiber paper surface density, honeycomb cell size, and honeycomb height-related parameters may be changed to improve the toughness of the carbon fiber paper honeycomb core material.

[0064] It should be clear that the present invention is not limited to the specific steps described above and shown in the figures. Moreover, for the sake of brevity, detailed description of known methods and technologies is omitted here.

[0065] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a high-toughness carbon fiber paper honeycomb core material, characterized in that: Includes steps: S1. The carbon fiber paper is primed with a first high-toughness epoxy resin solution and then subjected to high-temperature treatment to obtain a high-toughness treated carbon fiber paper; S2. A carbon fiber paper honeycomb core material to be impregnated with the high toughness treated carbon fiber paper is prepared; S3. The carbon fiber paper honeycomb core material to be impregnated is impregnated in a second high-toughness epoxy resin solution, and then cured at high temperature to obtain a toughened carbon fiber paper honeycomb core material; S4. The toughened carbon fiber paper honeycomb core material is impregnated with a phenolic resin solution until the carbon fiber paper honeycomb density reaches 32 kg / m 3 -72㎏ / m 3 , and then solidified to prepare a high-toughness carbon fiber paper honeycomb core material.

2. The preparation method according to claim 1, characterized in that: In step S1, the high-toughness epoxy resin in the first high-toughness epoxy resin solution is a high-temperature curing epoxy resin, and the curing temperature is 170°C to 200°C.

3. The preparation method according to claim 2, characterized in that: The high-toughness epoxy resin in the first high-toughness epoxy resin solution is a mixture of bisphenol A epoxy resin, bisphenol F epoxy resin, glycidyl ester epoxy resin, and phenolic resin, and the mass ratio of each component in the mixture is: bisphenol A epoxy resin: bisphenol F epoxy resin: glycidyl ester epoxy resin: phenolic resin = (15~45): (8~25): (10~20): (5~20).

4. The preparation method according to claim 2, characterized in that: A toughening agent is further added to the first high-toughness epoxy resin solution. The toughening agent is selected from one or more of polyethersulfone and polyetheretherketone. The mass fraction of the toughening agent in the first high-toughness epoxy resin solution is 15% to 35%.

5. The preparation method according to claim 2, characterized in that: The solvent used in the first high-toughness epoxy resin solution is selected from one of ethanol, toluene, acetone and ethyl acetate; and / or, The solid content of the first high-toughness epoxy resin solution is 0.5% to 10%.

6. The preparation method according to claim 1, characterized in that: In step S3, the high-toughness epoxy resin in the second high-toughness epoxy resin solution is a high-temperature curing epoxy resin, and the curing temperature is 170°C to 200°C.

7. The preparation method according to claim 6, characterized in that: The high-toughness epoxy resin in the second high-toughness epoxy resin solution is a mixture of bisphenol A epoxy resin, bisphenol F epoxy resin, glycidyl ester epoxy resin, and phenolic resin, and the mass ratio of each component in the mixture is: bisphenol A epoxy resin: bisphenol F epoxy resin: glycidyl ester epoxy resin: phenolic resin = (15~45): (8~25): (10~20): (5~20).

8. The preparation method according to claim 6, characterized in that: A toughening agent is further added to the second high-toughness epoxy resin solution. The toughening agent is selected from one or more of polyethersulfone and polyetheretherketone. The mass fraction of the toughening agent in the second high-toughness epoxy resin solution is 15% to 35%.

9. The preparation method according to claim 6, characterized in that: The solvent used in the second high-toughness epoxy resin solution is selected from one of ethanol, toluene, acetone and ethyl acetate; and / or, The solid content of the second high-toughness epoxy resin solution is 3% to 15%.

10. The preparation method according to claim 1, characterized in that: In step S4, the phenolic resin solution is an aminophenolic resin solution; The solvent used in the phenolic resin solution is ethanol or water; The solid content of the phenolic resin solution is 25% to 45%.

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