A medium- and low-temperature curing high-temperature resistant microwave absorbing material and its preparation method

Abstract

This invention discloses a medium- and low-temperature curing high-temperature resistant microwave absorbing material and its preparation method, relating to the field of electromagnetic wave absorbing materials. The method involves uniformly mixing an absorbent, tetraglycidylamine-type epoxy resin, and a polyether-modified polysiloxane defoamer to obtain component A; and uniformly mixing diethyltoluenediamine, boron trifluoride monoethylamine, and butyl glycidyl ether to obtain component B. In use, component A and component B are mixed uniformly, poured into the desired location, and cured at 75-120°C to obtain the medium- and low-temperature curing high-temperature resistant microwave absorbing material. The microwave absorbing material prepared by this invention meets the requirements of "ready-to-use potting" and medium- and low-temperature curing, and has a glass transition temperature >200°C, meeting the requirements for microwave absorbing materials in complex cavity structures of aerospace vehicles.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic wave absorbing materials, and in particular to a medium- and low-temperature curing high-temperature resistant wave absorbing material and its preparation method. Background Technology

[0002] Microwave-absorbing materials are functional materials that can absorb and attenuate incident electromagnetic wave energy, dissipating it by converting it into other forms of energy (such as mechanical, electrical, and thermal energy) through dielectric loss, or causing the electromagnetic wave to disappear due to interference. They exhibit very low reflection, scattering, and projection, making them widely used in antennas, combiner / splitters, and microwave components of various spacecraft. With the development of electromagnetic stealth technology in the aerospace field and the increasing severity of electromagnetic interference and pollution in daily life, microwave absorbing materials have gradually become a research hotspot in the field of functional materials.

[0003] Various types of probe satellites are commonly equipped with absorbing materials, which place high demands on the performance and precision of these materials. This is especially true for complex cavity structures near high-power antennas, where the absorbing material must precisely fill the cavity and withstand the high temperatures (>200℃) caused by the high-power antenna's operation. Furthermore, conventional rigid absorbing materials are regular blocks, primarily processed to the required dimensions. However, for complex cavity structures (such as large internal cavities with small openings), rigid materials cannot be installed. Therefore, the absorbing material must also meet the requirement of "ready to be potted immediately."

[0004] Currently, commonly used low-viscosity resin composite absorbers can be used to prepare castable microwave absorbing materials, thus meeting the "ready-to-use and immediately potting" requirement. However, such microwave absorbing materials are limited by the characteristics of the resin. Materials that are cured at medium and low temperatures (curing temperature ≤130℃) have a low glass transition temperature (glass transition temperature ≤160℃), which cannot meet the high-temperature resistance requirements under high power. On the other hand, materials that are cured at high temperatures (>200℃) will affect the performance of electronic components in the equipment and cannot be used. Summary of the Invention

[0005] The purpose of this invention is to provide a medium-low temperature curing high-temperature resistant microwave absorbing material and its preparation method. The microwave absorbing material meets the requirements of "ready to be used and potted" and medium-low temperature curing (curing temperature ≤130℃), and the glass transition temperature is >200℃.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides a method for preparing a medium-low temperature curing high-temperature resistant microwave absorbing material, which includes the following steps:

[0008] (1) Mix the absorbent, tetraglycidylamine type epoxy resin and polyether modified polysiloxane defoamer evenly to obtain component A.

[0009] (2) Mix diethyltoluenediamine, boron trifluoride monoethylamine and butyl glycidyl ether evenly to obtain component B;

[0010] (3) When using, mix component A and component B evenly, pour into the part to be used, and cure at a temperature of 75-120℃ to obtain a medium and low temperature curing high temperature absorbing material.

[0011] Preferably, the absorbent in step (1) is one or more of carbonyl iron powder, iron-silicon-aluminum alloy powder, iron-silicon-chromium alloy powder, silicon carbide powder, and graphene powder.

[0012] Preferably, the mass ratio of absorbent to tetraglycidylamine type epoxy resin in step (1) is 7:3-8:2.

[0013] Preferably, in step (1), the amount of polyether-modified polysiloxane defoamer is 0.3%-0.6% of the total mass of the absorbent and tetraglycidylamine resin.

[0014] Preferably, the mass ratio of diethyltoluenediamine and boron trifluoride monoethylamine in step (2) to tetraglycidylamine epoxy resin in step (1) is 35:3:100.

[0015] Preferably, in step (2), the mass ratio of butyl glycidyl ether to boron trifluoride monoethylamine is (1-1.5):1.

[0016] Preferably, the curing time in step (3) corresponds to the curing temperature and is one of 75℃ / 12h, 90℃ / 10h, 100℃ / 6h, 110℃ / 4h or 120℃ / 2h.

[0017] Secondly, the present invention provides a medium-low temperature curing high temperature absorbing material, which is prepared by the above-mentioned preparation method.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects:

[0019] (1) Diethyltoluenediamine is an aromatic amine epoxy curing agent, which is liquid at room temperature, facilitating uniform mixing with other components. Boron trifluoride monoethylamine (solid powder) is a co-catalyst, which can effectively reduce the curing temperature of aromatic amine curing agents (the conventional curing temperature of aromatic amine epoxy curing agents needs to reach above 150℃). Butyl glycidyl ether is an active diluent, which can effectively reduce the viscosity of the mixed system, facilitating the casting of the mixed components. At the same time, it can effectively dissolve boron trifluoride monoethylamine, thereby ensuring the uniform dispersion of boron trifluoride monoethylamine in the mixed components.

[0020] (2) The microwave absorbing material prepared by the present invention meets the requirements of "ready to use and potting" and medium and low temperature curing (curing temperature ≤130℃), and the glass transition temperature is >200℃, which meets the requirements of the complex cavity structure of aerospace for microwave absorbing materials. Attached Figure Description

[0021] Figure 1 The results are the glass transition temperature test results of the microwave absorbing material obtained in Example 1 after curing. Detailed Implementation

[0022] To make the various technical features, advantages, or effects of the present invention more apparent and understandable, a detailed description is provided below in conjunction with the accompanying drawings.

[0023] Example 1

[0024] (1) Mix carbonyl iron powder (80g), tetraglycidylamine type epoxy resin (20g) and polyether modified polysiloxane defoamer (0.3g) evenly to obtain component A;

[0025] (2) Mix diethyltoluene diamine (7g), boron trifluoride monoethylamine (0.6g) and butyl glycidyl ether (0.6g) evenly to obtain component B;

[0026] (3) Mix components A and B evenly, pour into the part to be used, and cure at 75°C for 12 hours to obtain the required microwave absorbing material.

[0027] Example 2

[0028] Example 2 is basically the same as Example 1, except that the absorbent is iron-silicon-chromium alloy powder and 0.5g of polyether-modified polysiloxane defoamer.

[0029] Example 3

[0030] Example 3 is basically the same as Example 1, except that: carbonyl iron powder 75g, tetraglycidylamine type epoxy resin 25g, polyether modified polysiloxane defoamer 0.6g, diethyltoluene diamine 8.75g, boron trifluoride monoethylamine 0.8g, and butyl glycidyl ether 1.0g.

[0031] Example 4

[0032] (1) Mix carbonyl iron powder (70g), tetraglycidylamine type epoxy resin (30g) and polyether modified polysiloxane defoamer (0.3g) evenly to obtain component A;

[0033] (2) Mix diethyltoluene diamine (10.5g), boron trifluoride monoethylamine (0.9g) and butyl glycidyl ether (0.9g) evenly to obtain component B;

[0034] (3) Mix components A and B evenly, pour into the part to be used, and cure at 100℃ for 6 hours to obtain the required microwave absorbing material.

[0035] Example 5

[0036] Example 5 is basically the same as Example 1, except that the butyl glycidyl ether content is 0.9g.

[0037] Example 6

[0038] Example 6 is basically the same as Example 1, except that it is cured at 120°C for 2 hours.

[0039] Comparative Example 1 (regarding the mass ratio of absorbent to epoxy resin)

[0040] (1) Mix carbonyl iron powder (90g), tetraglycidylamine type epoxy resin (10g) and polyether modified polysiloxane defoamer (0.3g) evenly to obtain component A;

[0041] (2) Mix diethyltoluene diamine (7g), boron trifluoride monoethylamine (0.6g) and butyl glycidyl ether (0.6g) evenly to obtain component B;

[0042] (3) Mix components A and B evenly, pour into the part to be used, and cure at 75°C for 12 hours to obtain the required microwave absorbing material.

[0043] Comparative Example 2 (Regarding the dosage of defoamer)

[0044] (1) Mix carbonyl iron powder (80g), tetraglycidylamine type epoxy resin (20g) and polyether modified polysiloxane defoamer (0.1g) evenly to obtain component A;

[0045] (2) Mix diethyltoluene diamine (7g), boron trifluoride monoethylamine (0.6g) and butyl glycidyl ether (0.6g) evenly to obtain component B;

[0046] (3) Mix components A and B evenly, pour into the part to be used, and cure at 75°C for 12 hours to obtain the required microwave absorbing material.

[0047] Comparative Example 3 (regarding diluent dosage)

[0048] (1) Mix carbonyl iron powder (80g), tetraglycidylamine type epoxy resin (20g) and polyether modified polysiloxane defoamer (0.3g) evenly to obtain component A;

[0049] (2) Mix diethyltoluene diamine (7g), boron trifluoride monoethylamine (0.6g) and butyl glycidyl ether (1.2g) evenly to obtain component B;

[0050] (3) Mix components A and B evenly, pour into the part to be used, and cure at 75°C for 12 hours to obtain the required microwave absorbing material.

[0051] Comparative Example 4 (regarding curing time)

[0052] (1) Mix carbonyl iron powder (80g), tetraglycidylamine type epoxy resin (20g) and polyether modified polysiloxane defoamer (0.3g) evenly to obtain component A;

[0053] (2) Mix diethyltoluene diamine (7g), boron trifluoride monoethylamine (0.6g) and butyl glycidyl ether (0.6g) evenly to obtain component B;

[0054] (3) Mix components A and B evenly, pour into the area to be used, and cure at 75°C for 2 hours to obtain the required microwave absorbing material.

[0055] The glass transition temperature of the microwave absorbing materials obtained in Examples 1 to 6 and Comparative Examples 1 to 4 was tested. Specifically, the glass transition temperature was tested by machining 80×10×4mm samples according to standard methods and using Dynamic Mechanical Analysis (DMA) to test the glass transition temperature. The glass transition temperature was determined by measuring the changes in the elastic modulus and loss modulus of the material under constant external force. Figure 1 The material exhibits the highest loss modulus at 255℃, which is also its glass transition temperature. All test results are shown in Table 1.

[0056] Table 1 Curing temperature and glass transition temperature of microwave absorbing materials

[0057]

[0058]

[0059] Although the present invention has been disclosed above with reference to embodiments, it is not intended to limit the present invention. Appropriate modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention should be covered within the protection scope of the present invention, which is defined by the claims.

Claims

1. A method for preparing a medium- and low-temperature curing, high-temperature resistant microwave absorbing material, characterized in that, Includes the following steps: (1) Mix the absorbent, tetraglycidylamine type epoxy resin and polyether modified polysiloxane defoamer evenly. The mass ratio of absorbent to tetraglycidylamine type epoxy resin is 7:3-8:

2. The amount of polyether modified polysiloxane defoamer is 0.3%-0.6% of the total mass of absorbent and tetraglycidylamine type epoxy resin to obtain component A. (2) Mix diethyltoluenediamine, boron trifluoride monoethylamine and butyl glycidyl ether evenly, with the mass ratio of butyl glycidyl ether to boron trifluoride monoethylamine being (1-1.5):1, to obtain component B; (3) When using, mix component A and component B evenly, pour into the part to be used, and cure at a temperature of 75-120℃. The curing time corresponds to the curing temperature and is one of 75℃ / 12h, 90℃ / 10h, 100℃ / 6h, 110℃ / 4h or 120℃ / 2h to obtain a medium and low temperature curing high temperature absorbing material.

2. The preparation method according to claim 1, characterized in that, In step (1), the absorbent is one or more of the following: carbonyl iron powder, iron-silicon-aluminum alloy powder, iron-silicon-chromium alloy powder, silicon carbide powder, and graphene powder.

3. The preparation method according to claim 1, characterized in that, The mass ratio of diethyltoluenediamine and boron trifluoride monoethylamine in step (2) to tetraglycidylamine epoxy resin in step (1) is 35:3:

100.

4. A medium- and low-temperature curing, high-temperature resistant microwave absorbing material, characterized in that, It is prepared by the preparation method according to any one of claims 1-3.

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