Preparation method and application of polyaniline and hectorite wave-absorbing material

Abstract

The invention relates to the technical field of wave-absorbing coatings, and discloses a preparation method and application of a polyaniline and hectorite wave-absorbing material, and the preparation method comprises the following steps: S1, mixing hectorite with a silane coupling agent KH550, and grinding to obtain silane surface modified hectorite; s2, putting the silane surface modified hectorite into a diluted hydrochloric acid solution, and stirring for the first time to obtain a mixture; then adding aniline into the mixture, and stirring for the second time to form an aniline and hectorite acidic suspension; and S3, slowly dropwise adding an ammonium persulfate solution into the aniline and hectorite acidic suspension in a stirring state, continuously stirring for a period of time, centrifuging, washing with water for multiple times, and drying to obtain the polyaniline and hectorite wave-absorbing material. The prepared material has the characteristics of a wave-absorbing material and the characteristics of a thickening agent, and the use limit of hectorite in the coating can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of microwave absorbing coatings, and in particular to a preparation method and application of a polyaniline@hectorite microwave absorbing material. Background Art

[0002] With the development of electronic information technology, the problem of electromagnetic pollution has become increasingly prominent. Electromagnetic interference not only interferes with electronic equipment in the fields of medicine, industry, commerce and military, but also causes potential damage to the human body if it stays in a high electromagnetic environment for a long time. The use of electromagnetic wave absorbing materials is an effective means to attenuate these electromagnetic energies. The absorbing coating prepared by compounding absorbing materials with polymer resins can effectively absorb electromagnetic waves and reduce electromagnetic interference and pollution when applied to the surface of the equipment. It also has good application prospects in military fields such as aircraft stealth.

[0003] Polyaniline is a conductive polymer with advantages such as light weight, stable performance, and corrosion resistance. It is a dielectric loss-type absorbing material with a resistance loss mechanism. Due to its weak magnetic loss capacity and poor impedance matching, it is difficult to use it alone as an absorbing material. It is usually used in combination with ferrite (CN117126533A), magnetic alloy (CN117362818A), carbon material (CN107722932B) and other absorbing materials to greatly improve its absorbing performance. In addition to being related to the nature of the material, the composite structure also has a great influence on the absorbing performance. For example, after attapulgite is composited with barium ferrite and loaded with polyaniline, in addition to dielectric loss and magnetic loss, its absorbing performance is further improved due to the interface effect and quantum effect mechanism introduced by its core-shell structure (CN110591088A).

[0004] In addition to absorbing materials, the composition of absorbing coatings also includes base materials (polymer resins), diluents, thickeners and other additives. Hectorite is a synthetic inorganic magnesium lithium silicate crystal with a montmorillonite structure. It will swell quickly when added to water to form a three-dimensional network gel containing a large amount of water. It is widely used in coatings as a thickener and protective glue. However, in the process of coating application, in order to reduce the viscosity of the coating and facilitate construction, it is sometimes necessary to add a viscosity reducer, so its usage is limited. Summary of the invention

[0005] Purpose of the invention: In view of the problems existing in the prior art, the present invention provides a method for preparing a polyaniline@hectorite absorbing material and its application. The material prepared by the present invention has both the properties of an absorbing material and a thickener, and can increase the use limit of hectorite in coatings.

[0006] Technical solution: On the one hand, the present invention provides a method for preparing a polyaniline@hectorite absorbing material, comprising the following steps: S1: mixing hectorite with silane coupling agent KH550, grinding, and obtaining silane surface modified hectorite; S2: placing the silane surface-modified hectorite in a dilute hydrochloric acid solution and stirring for the first time to obtain a mixture; then adding aniline to the mixture and stirring for the second time to form an aniline@hectorite acidic suspension; S3: slowly drop the ammonium persulfate solution into the aniline@hectorite acidic suspension under stirring, then continue stirring for a period of time, centrifuge, wash with water for multiple times, and dry to obtain the polyaniline@hectorite absorbing material.

[0007] Furthermore, in S1, the mass ratio of the hectorite to the silane coupling agent KH550 is 1:0.05-0.15.

[0008] Furthermore, in S2, the solid-liquid ratio of the silane surface modified hectorite to the dilute hydrochloric acid solution is 10-15%; and the concentration of the dilute hydrochloric acid is 1-2%.

[0009] Furthermore, in S2, the mass volume ratio of the hectorite in the mixture to the aniline is 1:0.25-0.5.

[0010] Furthermore, in S2, the first stirring time is 20 to 30 min; and the second stirring time is 5 to 10 h.

[0011] Furthermore, in S3, the concentration of the ammonium persulfate solution is 50-100 g / L.

[0012] Preferably, in S3, the ammonium persulfate solution is slowly added dropwise into the aniline@hectorite acidic suspension using an atomizing nozzle under stirring.

[0013] Preferably, in S3, the continuous stirring time is 5 to 8 h.

[0014] On the other hand, the present invention provides an application of a polyaniline@hectorite absorbing material prepared by any of the above methods in an absorbing coating, wherein the polyaniline@hectorite absorbing material is uniformly mixed with an epoxy resin and a curing agent, and cured to form a polyaniline@hectorite absorbing coating.

[0015] Furthermore, the mass ratio of the polyaniline@hectorite absorbing material, epoxy resin and curing agent is 2:2~2.5:0.4~0.6.

[0016] S1: Hectorite and silane coupling agent KH550 were mixed in a mass ratio of 1:0.05-0.15, and ground for 20 minutes to obtain hectorite surface-modified with silane.

[0017] S2: Add silane-modified hectorite to a dilute hydrochloric acid solution at a solid-liquid mass volume ratio of 10-15% and a hydrochloric acid concentration of 1%-2%, and stir for 30 minutes to form a mixture. Then add aniline to the mixture at a hectorite: aniline mass volume ratio of 1:0.25-0.5, and continue stirring for 5-10 hours to form an aniline@hectorite acidic suspension.

[0018] S3: Prepare an ammonium persulfate solution with a concentration of 50-100 g / L, and slowly add the ammonium persulfate solution to the aniline@hectorite acidic suspension using an atomizing nozzle under stirring according to the volume ratio of ammonium persulfate: hydrochloric acid of 2:3, then stir for 5-8 hours, centrifuge, wash with water for multiple times, and dry to obtain the polyaniline@hectorite absorbing material.

[0019] The synthesis principle of the present invention is as follows: The silane coupling agent is adsorbed on the surface of the hectorite, and its organic group is grafted onto the surface of the hectorite after hydrolysis. The amino groups on the surface of the coupling agent and the amino groups of aniline can form hydrogen bonds to strengthen the adsorption of aniline on the surface of the hectorite. Then, polyaniline is formed by initiation of ammonium persulfate in dilute hydrochloric acid to increase the loading of polyaniline on the surface of the hectorite.

[0020] Beneficial effects: Compared with the prior art, the present invention has the following advantages: (1) Polyaniline is loaded on the surface of lithium soapstone to form a composite material. When it forms an absorbing coating with the resin, in addition to the dielectric loss of polyaniline, the internal layers of the lithium soapstone and the three-dimensional network structure formed can provide mechanisms such as interface effects to absorb electromagnetic waves and enhance the absorbing performance.

[0021] (2) Polyaniline@lithium soapstone is used in coatings and has the properties of a thickener and an absorbing material. Its surface is loaded with polyaniline, which reduces its viscosity and improves the fluidity of the absorbing coating, which is beneficial for on-site construction and can reduce the use of viscosity reducers such as sodium pyrophosphate and sodium hexametaphosphate, thereby increasing its usage in coatings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 XRD spectra of laponite (a) and polyaniline@laponite (b) in Embodiment 1; Figure 2 This is a curve diagram of the wave absorption performance of polyaniline@hectorite in Implementation Example 1. DETAILED DESCRIPTION

[0023] The present invention is described in detail below in conjunction with the embodiments.

[0024] Implementation 1: This embodiment provides a method for preparing a polyaniline@hectorite absorbing material, which is as follows: 4 g of hectorite and 0.2 g of silane coupling agent KH550 were mixed at a mass ratio of 1:0.05 and milled for 20 min to obtain hectorite with silane surface modification. The prepared hectorite with silane surface modification was added to 28 mL of dilute hydrochloric acid solution with a concentration of 1% at a solid-liquid mass volume ratio of 10%, stirred for 30 min to form a mixture, and then 1 g of aniline was added to the mixture at a mass volume ratio of hectorite to aniline of 1:0.25, and stirred for 5 h to form an aniline@hectorite acidic suspension. A 50 g / L ammonium persulfate solution was prepared, and 28 mL of ammonium persulfate solution was slowly added to the aniline / hectorite acidic suspension using an atomizing nozzle under stirring, and then stirred for 5 h, centrifuged, washed with water several times, and dried to obtain a polyaniline@hectorite absorbent material.

[0025] This embodiment also provides an application of polyaniline@hectorite absorbing material in absorbing coating, as follows: The polyaniline@hectorite absorbing material prepared above was evenly mixed with epoxy resin and curing agent in a mass ratio of 2:2.5:0.5, and cured to form a polyaniline@hectorite absorbing coating.

[0026] The electromagnetic parameters of polyaniline@lithium laponite absorbing coating were tested using vector network analyzer. Figure 1 Figure 2 is the XRD spectrum of hectorite (a) and polyaniline@hectorite (b). It can be seen that after loading polyaniline, its XRD spectrum shows a broad peak in the range of 2θ 18~30°, indicating that polyaniline is loaded on the surface of hectorite. Figure 2 This is the absorbing performance curve of the polyaniline@lithium absorbing coating. When the coating thickness is 3 mm, its reflection loss can reach -22 dB, and the absorbing performance is better in the low frequency band (5~9 GHz).

[0027] Implementation 2: This embodiment provides a method for preparing a polyaniline@hectorite absorbing material, which is as follows: 4 g of hectorite and 0.4 g of silane coupling agent KH550 were mixed in a mass ratio of 1:0.1 and milled for 20 min to obtain hectorite with silane surface modification. The prepared hectorite with silane surface modification was added to 37 mL of dilute hydrochloric acid solution with a concentration of 1.5% according to a solid-liquid mass volume ratio of 12%, stirred for 30 min to form a mixture, and then 1.4 g of aniline was added to the mixture according to a mass volume ratio of hectorite:aniline of 1:0.35, and stirred for 8 h to form an aniline@hectorite acidic suspension. A 70 g / L ammonium persulfate solution was prepared, and 24.7 mL of ammonium persulfate solution was slowly added to the aniline@hectorite acidic suspension using an atomizing nozzle under stirring, and then stirred for 6.5 h, centrifuged, washed with water for many times, and dried to obtain a polyaniline@hectorite absorbing material.

[0028] Implementation 3: This embodiment provides a method for preparing a polyaniline@hectorite absorbing material, which is as follows: 4 g of hectorite and 0.6 g of silane coupling agent KH550 were mixed in a mass ratio of 1:0.15 and milled for 20 min to obtain silane surface-modified hectorite. The prepared silane surface-modified hectorite was added to 31 mL of dilute hydrochloric acid solution with a concentration of 2% according to a solid-liquid mass volume ratio of 15%, stirred for 30 min to form a mixture, and then 2 g of aniline was added to the mixture according to a mass volume ratio of hectorite to aniline of 1:0.5, and continued to stir for 10 h to form an aniline@hectorite acidic suspension. A 100 g / L ammonium persulfate solution was prepared, and 20.7 mL of ammonium persulfate solution was slowly added to the aniline / hectorite acidic suspension using an atomizing nozzle under stirring, and then stirred for 8 h, centrifuged, washed with water several times, and dried to obtain a polyaniline@hectorite absorbent material.

[0029] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a polyaniline@hectorite absorbing material, characterized in that: The following steps are involved: S1: mixing hectorite with silane coupling agent KH550, grinding, and obtaining silane surface modified hectorite; S2: placing the silane surface-modified hectorite in a dilute hydrochloric acid solution and stirring for the first time to obtain a mixture; then adding aniline to the mixture and stirring for the second time to form an aniline@hectorite acidic suspension; S3: slowly drop the ammonium persulfate solution into the aniline@hectorite acidic suspension under stirring, then continue stirring for a period of time, centrifuge, wash with water for multiple times, and dry to obtain the polyaniline@hectorite absorbing material.

2. The method for preparing the polyaniline@hectorite absorbing material according to claim 1, characterized in that: In S1, the mass ratio of the hectorite to the silane coupling agent KH550 is 1:0.05-0.

15.

3. The method for preparing the polyaniline@hectorite absorbing material according to claim 1, characterized in that: In S2, the solid-to-liquid ratio of the silane surface modified hectorite to the dilute hydrochloric acid solution is 10-15%; and the concentration of the dilute hydrochloric acid is 1-2%.

4. The method for preparing the polyaniline@hectorite absorbing material according to claim 1, characterized in that: In S2, the mass volume ratio of the hectorite in the mixture to the aniline is 1:0.25-0.

5.

5. The method for preparing the polyaniline@hectorite absorbing material according to claim 1, characterized in that: In S2, the first stirring time is 20 to 30 min; the second stirring time is 5 to 10 h.

6. The method for preparing the polyaniline@hectorite absorbing material according to claim 1, characterized in that: In S3, the concentration of the ammonium persulfate solution is 50-100 g / L.

7. The method for preparing the polyaniline@hectorite absorbing material according to claim 1, characterized in that: In S3, the ammonium persulfate solution is slowly added dropwise into the aniline@hectorite acidic suspension using an atomizing nozzle under stirring.

8. The method for preparing the polyaniline@hectorite absorbing material according to claim 1, characterized in that: In S3, the continuous stirring time is 5 to 8 h.

9. Use of the polyaniline@hectorite absorbing material prepared by the method according to any one of claims 1 to 8 in an absorbing coating, characterized in that: The polyaniline@hectorite absorbing material is uniformly mixed with epoxy resin and curing agent, and then cured to form a polyaniline@hectorite absorbing coating.

10. The use of the polyaniline@hectorite absorbing material in a absorbing coating according to claim 9, characterized in that: The mass ratio of the polyaniline@hectorite absorbing material, epoxy resin and curing agent is 2:2-2.5:0.4-0.6.

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