阅读说明：本技术 一种吸波氰酸酯树脂、吸波氰酸酯树脂复材及其制备方法 (Wave-absorbing cyanate ester resin, wave-absorbing cyanate ester resin composite material and preparation method thereof ) 是由 吕通 赵宏杰 宫元勋 朱伟杰 刘甲 于 2021-10-21 设计创作，主要内容包括：本发明涉及一种吸波氰酸酯树脂、吸波氰酸酯树脂复材及其制备方法。所述方法：将氰酸酯树脂、环氧树脂和吸收剂进行密炼粗混,得到粗混吸波氰酸酯树脂；将粗混吸波氰酸酯树脂进行开炼精混,得到精混吸波氰酸酯树脂,然后加入固化剂,得到吸波氰酸酯树脂固化体系；固化剂选自脂肪胺固化剂、聚酰胺固化剂、芳香胺固化剂、聚醚胺固化剂、双氰胺固化剂、酸酐类固化剂中的一种或多种；将吸波氰酸酯树脂固化体系在不同温度阶段触发固化,得到不同粘度的吸波氰酸酯树脂。本发明中的吸波氰酸酯树脂在不同的工艺过程中具备不同的粘度,有利于吸收剂的分散均匀,有利于压延成型,使吸波氰酸酯树脂具有更好的吸波性能稳定性以及工艺特性。(The invention relates to wave-absorbing cyanate ester resin, a wave-absorbing cyanate ester resin composite material and a preparation method thereof. The method comprises the following steps: carrying out banburying and rough mixing on cyanate ester resin, epoxy resin and an absorbent to obtain rough mixed wave-absorbing cyanate ester resin; refining and fine mixing are carried out on the rough mixed wave-absorbing cyanate ester resin to obtain fine mixed wave-absorbing cyanate ester resin, and then a curing agent is added to obtain a wave-absorbing cyanate ester resin curing system; the curing agent is selected from one or more of aliphatic amine curing agent, polyamide curing agent, aromatic amine curing agent, polyether amine curing agent, dicyandiamide curing agent and anhydride curing agent; and triggering and curing the wave-absorbing cyanate resin curing system at different temperature stages to obtain the wave-absorbing cyanate resin with different viscosities. The wave-absorbing cyanate ester resin has different viscosities in different technological processes, is beneficial to uniform dispersion of the absorbent and calendering molding, and has better wave-absorbing performance stability and technological characteristics.)

1. The preparation method of the wave-absorbing cyanate ester resin is characterized by comprising the following steps:

(1) putting the cyanate ester resin, the epoxy resin and the absorbent into an internal mixer for internal mixing and coarse mixing to obtain coarse mixed wave-absorbing cyanate ester resin;

(2) putting the rough mixed wave-absorbing cyanate ester resin obtained in the step (1) into an open mill for open-refining and fine mixing to obtain fine mixed wave-absorbing cyanate ester resin, and then adding a curing agent into the fine mixed wave-absorbing cyanate ester resin to obtain a wave-absorbing cyanate ester resin curing system; the curing agent is selected from one or more of aliphatic amine curing agent, polyamide curing agent, aromatic amine curing agent, polyether amine curing agent, dicyandiamide curing agent and anhydride curing agent;

(3) and (3) triggering and curing the wave-absorbing cyanate resin curing system obtained in the step (2) at different temperature stages to obtain the wave-absorbing cyanate resin with different viscosities.

2. The method of claim 1, wherein:

the molar ratio of the cyanate ester resin, the curing agent and the epoxy resin is 1: (0.1-0.5): (0.5 to 0.7); and/or

The curing agent is an aliphatic amine curing agent, and preferably, the curing agent is one or more of diethylenetriamine, triethylene tetramine and tetraethylene pentamine.

3. The method of claim 1, wherein:

the cyanate resin is one or more of bisphenol A type cyanate resin, tetramethyl bisphenol F type cyanate resin, bisphenol M type cyanate resin, bisphenol E type cyanate resin and polyfunctional group type cyanate resin;

the epoxy resin is one or more of E-51 type epoxy resin, E-44 type epoxy resin, E-20 type epoxy resin, F-44 type epoxy resin and F-51 type epoxy resin; and/or

The absorbent is one or more of carbonyl iron, ferrum-silicon-aluminum, ferrite, conductive carbon black, carbon fiber, graphene, carbon nano tube and silicon carbide, and preferably, the dosage of the absorbent is 5-90% of the sum of the mass of the cyanate ester resin and the mass of the epoxy resin.

4. The production method according to any one of claims 1 to 3, characterized in that:

in the step (1), the temperature of the banburying and rough mixing is 20-300 ℃, the time of the banburying and rough mixing is 10-120 min, and the rotating speed of a rotor of the banburying and rough mixing is 10-250 r/min;

in the step (2), the temperature of the refining and mixing is 20-300 ℃, and the roller speed of the refining and mixing is 2-17 m/min;

in the step (2), the rough mixed wave-absorbing cyanate ester resin obtained in the step (1) is placed into an open mill for refining and mixing for 10-80 min to obtain refined mixed wave-absorbing cyanate ester resin, and then a curing agent is added into the refined mixed wave-absorbing cyanate ester resin and refining and mixing are continuously carried out for 2-10 min to obtain a wave-absorbing cyanate ester resin curing system; and/or

In the step (3), the wave-absorbing cyanate resin curing system obtained in the step (2) is triggered to be cured in a staged manner within the temperature range of 20-300 ℃, so that wave-absorbing cyanate resins with different viscosities are obtained.

5. Wave-absorbing cyanate ester resin prepared by the preparation method of any one of claims 1 to 4.

6. The preparation method of the wave-absorbing cyanate ester resin composite material is characterized by comprising the following steps:

(a) putting the cyanate ester resin, the epoxy resin and the absorbent into an internal mixer for internal mixing and coarse mixing to obtain coarse mixed wave-absorbing cyanate ester resin;

(b) putting the rough mixed wave-absorbing cyanate ester resin obtained in the step (a) into an open mill for open-refining and fine mixing to obtain fine mixed wave-absorbing cyanate ester resin, and then adding a curing agent into the fine mixed wave-absorbing cyanate ester resin to obtain a wave-absorbing cyanate ester resin curing system; the curing agent is selected from one or more of aliphatic amine curing agent, polyamide curing agent, aromatic amine curing agent, polyether amine curing agent, dicyandiamide curing agent and anhydride curing agent;

(c) triggering and curing the wave-absorbing cyanate ester resin curing system obtained in the step (b) at least at one low-temperature stage to obtain a wave-absorbing cyanate ester resin blank, and then putting the wave-absorbing cyanate ester resin blank into a calender for calendering to obtain a wave-absorbing cyanate ester resin film;

(d) and (3) laminating and spreading a plurality of layers of the wave-absorbing cyanate resin film, and then triggering and curing at least at one high-temperature stage to prepare the wave-absorbing cyanate resin composite material.

7. The method of claim 6, wherein:

the molar ratio of the cyanate ester resin, the curing agent and the epoxy resin is 1: (0.1-0.5): (0.5 to 0.7);

the curing agent is an aliphatic amine curing agent, and preferably, the curing agent is one or more of diethylenetriamine, triethylene tetramine and tetraethylene pentamine.

8. The production method according to claim 6 or 7, characterized in that:

in the step (c), triggering and curing the wave-absorbing cyanate ester resin curing system obtained in the step (b) at 50-80 ℃ to obtain a wave-absorbing cyanate ester resin blank, and then putting the wave-absorbing cyanate ester resin blank into a calender for calendering to obtain a wave-absorbing cyanate ester resin film;

in the step (d), a plurality of wave-absorbing cyanate resin films are laminated and then triggered and cured at 180-250 ℃ to prepare the wave-absorbing cyanate resin composite material.

9. The method of claim 6, wherein:

the viscosity of the wave-absorbing cyanate ester resin curing system is 500-20000 cps; and/or

The viscosity of the wave-absorbing cyanate ester resin blank is 30000-500000 cps.

10. The wave-absorbing cyanate ester resin composite material prepared by the preparation method of any one of claims 6 to 9.

Technical Field

The invention belongs to the technical field of wave-absorbing material preparation, and particularly relates to wave-absorbing cyanate ester resin, a wave-absorbing cyanate ester resin composite material and a preparation method thereof.

Background

The wave-absorbing material is a material capable of absorbing and attenuating incident electromagnetic waves, converting electromagnetic energy into heat energy and dissipating the heat energy or enabling the electromagnetic waves to disappear due to interference. With the development of scientific technology, the wave-absorbing material has wide application in various aspects. The method has important significance in the fields of electromagnetic protection, microwave darkroom, mobile communication, military stealth and the like. The resin-based wave-absorbing composite material has the advantages of strong designability, large-area integral forming and the like, and becomes one of the most important application materials in the aerospace stealth field.

The wave-absorbing resin is a raw material for preparing a resin-based wave-absorbing composite material and consists of an electromagnetic wave absorbent and a resin matrix, wherein the electromagnetic wave absorbent determines the wave-absorbing property of the resin-based wave-absorbing composite material, and the resin matrix determines more process characteristics of the resin-based wave-absorbing composite material. The invention realizes that the wave-absorbing resin needs to have different viscosity states in the whole process, for example, when the wave-absorbing resin is mixed, the wave-absorbing resin needs to have lower viscosity, and the low viscosity is favorable for the uniform dispersion of the electromagnetic wave absorbent in the resin matrix. When the wave-absorbing resin is rolled to form a film, the wave-absorbing resin needs to have certain viscosity to endow the adhesive film with film-forming characteristics, and the improvement of plasticity is beneficial to the precise rolling forming of the adhesive film. When the wave-absorbing resin is completely cured and molded, the wave-absorbing resin has the highest viscosity, and the material has good mechanical properties due to complete crosslinking and curing. The wave-absorbing resin has high absorbent content, the viscosity control is particularly important for the performance regulation and control, and the wave-absorbing resin with controllable viscosity can effectively improve the wave-absorbing property and the process property of the resin-based wave-absorbing composite material.

However, the existing wave-absorbing resin generally has the problem of uncontrollable viscosity in the whole process flow. For example, chinese patent application CN111704868A provides a wave-absorbing adhesive film and a method for preparing the same, chinese patent application CN107586436A provides a wave-absorbing prepreg and a method for preparing the same, and chinese patent application CN112029421A discloses a wave-absorbing adhesive film material and a method for preparing the same, but the viscosity of the wave-absorbing resin involved in these methods is not controllable, and is only suitable for a process at a certain stage, or the high or low viscosity is not good for the uniform dispersion and calendering molding of the absorbent, for example, if the viscosity is low, although the resin can be ensured to have good uniformity during mixing, the viscosity is low during calendering, the adhesive film has poor plasticity, the molding precision is not high, and if the viscosity is high, although the resin has high plasticity during calendering, the molding precision is high, but the uniformity during mixing is difficult to ensure.

In summary, it is very necessary to provide a wave-absorbing cyanate ester resin, a wave-absorbing cyanate ester resin composite material and a preparation method thereof.

Disclosure of Invention

The invention provides wave-absorbing cyanate resin, a wave-absorbing cyanate resin composite material and a preparation method thereof, aiming at solving the technical problem that the viscosity of the existing wave-absorbing resin is uncontrollable in the whole process flow. The wave-absorbing cyanate ester resin has different viscosities in different process procedures, which is beneficial to the uniform dispersion of the absorbent and the calendaring molding of the wave-absorbing composite material intermediate, so that the wave-absorbing cyanate ester resin has better wave-absorbing performance (the stability of the wave-absorbing performance is improved) and process characteristics.

The invention provides a preparation method of wave-absorbing cyanate ester resin in a first aspect, which comprises the following steps:

(1) putting the cyanate ester resin, the epoxy resin and the absorbent into an internal mixer for internal mixing and coarse mixing to obtain coarse mixed wave-absorbing cyanate ester resin;

(2) putting the rough mixed wave-absorbing cyanate ester resin obtained in the step (1) into an open mill for open-refining and fine mixing to obtain fine mixed wave-absorbing cyanate ester resin, and then adding a curing agent into the fine mixed wave-absorbing cyanate ester resin to obtain a wave-absorbing cyanate ester resin curing system; the curing agent is selected from one or more of aliphatic amine curing agent, polyamide curing agent, aromatic amine curing agent, polyether amine curing agent, dicyandiamide curing agent and anhydride curing agent;

(3) and (3) triggering and curing the wave-absorbing cyanate resin curing system obtained in the step (2) at different temperature stages to obtain the wave-absorbing cyanate resin with different viscosities.

Preferably, the molar ratio of the cyanate ester resin, the curing agent and the epoxy resin is 1: (0.1-0.5): (0.5 to 0.7); and/or the curing agent is an aliphatic amine curing agent, preferably, the curing agent is one or more of diethylenetriamine, triethylene tetramine and tetraethylene pentamine.

Preferably, the cyanate ester resin is one or more of bisphenol a type cyanate ester resin, tetramethyl bisphenol F type cyanate ester resin, bisphenol M type cyanate ester resin, bisphenol E type cyanate ester resin, and multifunctional cyanate ester resin; the epoxy resin is one or more of E-51 type epoxy resin, E-44 type epoxy resin, E-20 type epoxy resin, F-44 type epoxy resin and F-51 type epoxy resin; and/or the absorbent is one or more of carbonyl iron, ferrum-silicon-aluminum, ferrite, conductive carbon black, carbon fiber, graphene, carbon nano tube and silicon carbide, and preferably, the using amount of the absorbent is 5-90% of the sum of the masses of the cyanate resin and the epoxy resin.

Preferably, in the step (1), the temperature of the banburying and rough mixing is 20-300 ℃, the time of the banburying and rough mixing is 10-120 min, and the rotating speed of a rotor of the banburying and rough mixing is 10-250 r/min; in the step (2), the temperature of the refining and mixing is 20-300 ℃, and the roller speed of the refining and mixing is 2-17 m/min; in the step (2), the rough mixed wave-absorbing cyanate ester resin obtained in the step (1) is placed into an open mill for refining and mixing for 10-80 min to obtain refined mixed wave-absorbing cyanate ester resin, and then a curing agent is added into the refined mixed wave-absorbing cyanate ester resin and refining and mixing are continuously carried out for 2-10 min to obtain a wave-absorbing cyanate ester resin curing system; and/or in the step (3), triggering the wave-absorbing cyanate resin curing system obtained in the step (2) to be cured in a staged manner within the temperature range of 20-300 ℃ to obtain the wave-absorbing cyanate resin with different viscosities.

In a second aspect, the invention provides a wave-absorbing cyanate ester resin prepared by the preparation method of the first aspect of the invention.

The invention provides a preparation method of a wave-absorbing cyanate ester resin composite material in a third aspect, which comprises the following steps:

(a) putting the cyanate ester resin, the epoxy resin and the absorbent into an internal mixer for internal mixing and coarse mixing to obtain coarse mixed wave-absorbing cyanate ester resin;

(b) putting the rough mixed wave-absorbing cyanate ester resin obtained in the step (a) into an open mill for open-refining and fine mixing to obtain fine mixed wave-absorbing cyanate ester resin, and then adding a curing agent into the fine mixed wave-absorbing cyanate ester resin to obtain a wave-absorbing cyanate ester resin curing system; the curing agent is selected from one or more of aliphatic amine curing agent, polyamide curing agent, aromatic amine curing agent, polyether amine curing agent, dicyandiamide curing agent and anhydride curing agent;

(c) triggering and curing the wave-absorbing cyanate ester resin curing system obtained in the step (b) at least at one low-temperature stage to obtain a wave-absorbing cyanate ester resin blank, and then putting the wave-absorbing cyanate ester resin blank into a calender for calendering to obtain a wave-absorbing cyanate ester resin film;

(d) and (3) laminating and spreading a plurality of layers of the wave-absorbing cyanate resin film, and then triggering and curing at least at one high-temperature stage to prepare the wave-absorbing cyanate resin composite material.

Preferably, the molar ratio of the cyanate ester resin, the curing agent and the epoxy resin is 1: (0.1-0.5): (0.5 to 0.7); the curing agent is an aliphatic amine curing agent, and preferably, the curing agent is one or more of diethylenetriamine, triethylene tetramine and tetraethylene pentamine.

Preferably, in the step (c), the wave-absorbing cyanate ester resin curing system obtained in the step (b) is triggered and cured at 50-80 ℃ to obtain a wave-absorbing cyanate ester resin blank, and then the wave-absorbing cyanate ester resin blank is placed into a calender for calendering to obtain a wave-absorbing cyanate ester resin film; in the step (d), a plurality of wave-absorbing cyanate resin films are laminated and then triggered and cured at 180-250 ℃ to prepare the wave-absorbing cyanate resin composite material.

Preferably, the viscosity of the wave-absorbing cyanate ester resin curing system is 500-20000 cps; and/or the viscosity of the wave-absorbing cyanate ester resin blank is 30000-500000 cps.

In a fourth aspect, the invention provides a wave-absorbing cyanate ester resin composite material prepared by the preparation method in the third aspect.

Compared with the prior art, the invention at least has the following beneficial effects:

(1) the wave-absorbing cyanate ester resin with low viscosity in the processes of banburying, rough mixing and open refining mixing is beneficial to the uniform dispersion of the absorbent, and the electrical property and the wave-absorbing property stability of the wave-absorbing cyanate ester resin are improved.

(2) The microwave-absorbing cyanate ester resin has increased viscosity after the curing reaction at a certain temperature is triggered, so that the plasticity and the film forming property of the microwave-absorbing cyanate ester resin are improved, and the precise film forming property is favorable for controlling the wave absorbing performance of the microwave-absorbing cyanate ester resin composite material.

(3) The viscosity of the wave-absorbing cyanate ester resin in the mixing stage is in the range of 500-20000 cps, and the surface density Cv values of the wave-absorbing cyanate ester resin composites in different areas can reach 0.02-0.05 in the range; after the first stage curing (low-temperature stage curing), the viscosity is within the viscosity range of 30000-500000 cps, the calendering thickness precision can reach within the thickness range of +/-5%, and the wave-absorbing cyanate ester resin does not have viscosity after being completely cured.

(4) According to the invention, the low-viscosity wave-absorbing cyanate ester resin is beneficial to the dispersion of the absorbent, the high-viscosity wave-absorbing cyanate ester resin which is triggered and cured at different temperature stages is beneficial to the thickness precision control, and the reflection rate absorption peak frequency value Cv value can be controlled within 0.1 after the wave-absorbing resin film is rolled into a multi-layer lamination; compared with the wave-absorbing performance of the wave-absorbing cyanate ester resin composite material which is not pre-cured, the wave-absorbing cyanate ester resin composite material obtained by the invention has the advantages that the wave-absorbing performance stability of the wave-absorbing cyanate ester resin composite material is improved; the wave-absorbing cyanate resin film obtained by the invention can control the value of the reflection rate absorption peak frequency value Cv within 0.1 after being laminated in multiple layers, is beneficial to obtaining the wave-absorbing cyanate resin composite material with good wave-absorbing performance, and can accurately control the thickness precision of the wave-absorbing cyanate resin composite material within a wider range.

Drawings

FIG. 1 is a process flow chart for preparing the wave-absorbing cyanate ester resin.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

The invention provides a preparation method of wave-absorbing cyanate ester resin in a first aspect, and fig. 1 is a process flow chart of the wave-absorbing cyanate ester resin preparation method of the invention, for example, as shown in fig. 1, a wave-absorbing cyanate ester resin curing system is prepared, an absorbent, cyanate ester resin and epoxy resin are firstly banburied and coarsely mixed, after being uniformly mixed, the mixture is put into an open mill for fine mixing, and stage curing reaction is triggered at different temperatures, so that the wave-absorbing cyanate ester resin has different viscosities at different processing stages to adapt to processability; the wave-absorbing cyanate ester resin prepared by the invention is triggered and cured at different temperature stages, so that wave-absorbing cyanate ester resins with different viscosities can be obtained, and the viscosity is controllable; the wave-absorbing cyanate ester resin with controllable viscosity is beneficial to uniform dispersion of the absorbent and simultaneously beneficial to calendaring and forming of the wave-absorbing cyanate ester resin.

In the invention, the preparation method of the wave-absorbing cyanate ester resin comprises the following steps:

(1) putting the cyanate ester resin, the epoxy resin and the absorbent into an internal mixer for internal mixing and coarse mixing to obtain coarse mixed wave-absorbing cyanate ester resin; the cyanate ester resin and the epoxy resin are not particularly limited in kind and source, and commercially available cyanate ester resins which can be directly purchased or synthesized by existing methods can be used.

(2) Putting the rough mixed wave-absorbing cyanate ester resin obtained in the step (1) into an open mill for open-refining and fine mixing to obtain fine mixed wave-absorbing cyanate ester resin, and then adding a curing agent into the fine mixed wave-absorbing cyanate ester resin to obtain a wave-absorbing cyanate ester resin curing system; the curing agent is selected from one or more of aliphatic amine curing agent, polyamide curing agent, aromatic amine curing agent, polyether amine curing agent, dicyandiamide curing agent and anhydride curing agent;

(3) and (3) triggering and curing the wave-absorbing cyanate resin curing system obtained in the step (2) at different temperature stages to obtain the wave-absorbing cyanate resin with different viscosities.

In the invention, the curing agent is selected from one or more of aliphatic amine curing agent, polyamide curing agent, aromatic amine curing agent, polyether amine curing agent, dicyandiamide curing agent and anhydride curing agent, and the curing agents of different types have different curing temperatures, in the invention, when a plurality of curing agents with different curing temperatures are added in the step (2), correspondingly, in the step (3), the curing is triggered at a plurality of corresponding curing temperature stages according to a mode that the curing temperatures are sequentially increased, so that the wave-absorbing cyanate ester resin with different viscosities is obtained; in step (3), the cyanate ester resin is triggered to be cured within the thermal self-polymerization temperature range of the cyanate ester resin (the cyanate ester thermal self-polymerization temperature is generally higher than 177 ℃), so that the wave-absorbing cyanate ester resin with different viscosities is obtained; in the invention, the curing temperature is strictly controlled, so that the curing at the higher curing temperature stage cannot be initiated at the lower curing temperature stage, and the wave-absorbing cyanate ester resin with different viscosities can be obtained after the curing is triggered at each temperature stage, so that the wave-absorbing cyanate ester resin has different viscosities at different processing stages to adapt to the processability.

According to some preferred embodiments, the molar ratio of the cyanate ester resin, the curing agent and the epoxy resin is 1: (0.1-0.5): (0.5 to 0.7) (e.g., 1:0.1:0.5, 1:0.1:0.6, 1:0.1:0.7, 1:0.2:0.5, 1:0.2:0.6, 1:0.2:0.7, 1:0.3:0.5, 1:0.3:0.6, 1:0.3:0.7, 1:0.4:0.5, 1:0.4:0.6, 1:0.4:0.7, 1:0.5:0.5, 1:0.5:0.6, or 1:0.5: 0.7); and/or the curing agent is an aliphatic amine curing agent, preferably, the curing agent is one or more of diethylenetriamine, triethylene tetramine and tetraethylene pentamine; in the invention, preferably, in the step (2), an aliphatic amine curing agent with a lower curing temperature, for example, an aliphatic amine curing agent with a curing temperature of 50-80 ℃ is added, so that the wave-absorbing cyanate resin curing system obtained in the step (2) is triggered to cure in two temperature stages, including the curing in the low-temperature stage of 50-80 ℃ and the curing in the high-temperature cyanate resin thermal self-polymerization temperature stage; in the present invention, it is preferable that the molar ratio of the cyanate ester resin to the epoxy resin is 1: (0.5-0.7), in the range of the molar ratio, the wave-absorbing cyanate ester resin with controllable viscosity can be obtained, on one hand, in the mixing stage of banburying coarse mixing and refining fine mixing, the wave-absorbing cyanate ester resin curing system with the viscosity of 500-20000 cps can be obtained, the wave-absorbing cyanate ester resin curing system in the viscosity range is beneficial to uniform dispersion of the absorbent, the density Cv value of the wave-absorbing cyanate ester resin in different areas can reach 0.02-0.05, and the electrical property and the wave-absorbing property stability of the wave-absorbing cyanate ester resin can be improved; on the other hand, after the wave-absorbing cyanate ester resin is cured at the low temperature of 50-80 ℃, the viscosity of the wave-absorbing cyanate ester resin can be kept within the viscosity range of 30000-500000 cps, the wave-absorbing cyanate ester resin within the viscosity range is beneficial to calendering and film forming, the precision of the calendered thickness can reach +/-5 percent, the precise film forming characteristic is beneficial to controlling the wave-absorbing performance of the wave-absorbing cyanate ester resin composite material, and is beneficial to ensuring the wave-absorbing performance and the mechanical performance of the wave-absorbing cyanate ester resin film after calendering and film forming, so that the reflection rate absorption peak frequency Cv value can be controlled within 0.1 after the calendered wave-absorbing cyanate ester resin film is laminated in multiple layers, the stability of the wave-absorbing cyanate ester resin is effectively improved, if the content of the epoxy resin is higher, the viscosity of the wave-absorbing cyanate ester resin is improved more, and if the content of the epoxy resin is lower, the viscosity of the wave-absorbing cyanate ester resin is improved less, the viscosity of the wave-absorbing cyanate ester resin can not be controlled within the viscosity of 30000-500000 cps, this is not beneficial to the rolling molding of the wave-absorbing cyanate ester resin.

According to some preferred embodiments, the cyanate ester resin is one or more of bisphenol a type cyanate ester resin, tetramethyl bisphenol F type cyanate ester resin, bisphenol M type cyanate ester resin, bisphenol E type cyanate ester resin, multifunctional type cyanate ester resin; in the present invention, the cyanate ester resins used may be either commercially available or synthesized by conventional methods.

According to some preferred embodiments, the epoxy resin is one or more of an E-51 type epoxy resin, an E-44 type epoxy resin, an E-20 type epoxy resin, an F-44 type epoxy resin, an F-51 type epoxy resin; in the present invention, any of these epoxy resins can be used as they are commercially available.

According to some preferred embodiments, the absorbent is one or more of carbonyl iron, sendust, ferrite, conductive carbon black, carbon fiber, graphene, carbon nanotube, and silicon carbide, and preferably, the amount of the absorbent is 5 to 90% (e.g., 5%, 15%, 25%, 40%, 50%, 60%, 70%, 80%, or 90%) and preferably 40 to 85% (e.g., 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, or 85%) of the sum of the masses of the cyanate ester resin and the epoxy resin.

According to some preferred embodiments, in step (1), the temperature of the banburying rough mixing is 20 to 300 ℃ (e.g., 20 ℃, 40 ℃, 60 ℃, 80 ℃, 100 ℃, 120 ℃, 140 ℃, 160 ℃, 180 ℃, 200 ℃, 220 ℃, 240 ℃, 260 ℃, 280 ℃ or 300 ℃), preferably 80 to 300 ℃ (e.g., 80 ℃, 100 ℃, 120 ℃, 140 ℃, 160 ℃, 180 ℃, 200 ℃, 220 ℃, 240 ℃, 260 ℃, 280 ℃ or 300 ℃), the banburying rough mixing time is 10 to 120min (e.g., 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110 or 120min), preferably 30 to 60min (e.g., 30, 40, 50 or 60min), the rotor rotation speed of the banburying rough mixing is 10 to 250r/min (e.g., 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 110, 150, 190 ℃,/L, 220. 230, 240 or 250r/min), preferably 150 to 250r/min (e.g. 150, 160, 170, 180, 190, 200, 210, 220, 230, 240 or 250 r/min).

In some more preferred embodiments, the temperature of the banburying and rough mixing is 80-300 ℃, the time of the banburying and rough mixing is 30-60 min, and the rotation speed of a rotor of the banburying and rough mixing is 150-250 r/min.

According to some preferred embodiments, in step (2), the temperature of the flash refining is 20 to 300 ℃ (e.g., 20 ℃, 40 ℃, 60 ℃, 80 ℃, 100 ℃, 120 ℃, 140 ℃, 160 ℃, 180 ℃, 200 ℃, 220 ℃, 240 ℃, 260 ℃, 280 ℃, or 300 ℃), preferably 80 to 250 ℃ (e.g., 80 ℃, 100 ℃, 120 ℃, 140 ℃, 160 ℃, 180 ℃, 200 ℃, 220 ℃, or 250 ℃), and the roll speed of the flash refining is 2 to 17m/min (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or 17m/min), preferably 10 to 15m/min (e.g., 10, 11, 12, 13, 14, or 15 m/min); in the present invention, the unit m/min of the roll speed represents meters/minute.

In some more preferred embodiments, the temperature of the refining and mixing is 80-250 ℃, and the roller speed of the refining and mixing is 10-15 m/min.

According to some preferred embodiments, in the step (2), the rough mixed wave-absorbing cyanate ester resin obtained in the step (1) is placed into an open mill to be subjected to open refining mixing for 10 to 80min (for example, 10, 20, 30, 40, 50, 60, 70 or 80min), preferably 30 to 60min (for example, 30, 40, 50 or 60min) to obtain a refined mixed wave-absorbing cyanate ester resin, and then a curing agent is added into the refined mixed wave-absorbing cyanate ester resin and is subjected to open refining mixing for 2 to 10min (for example, 2, 5, 8 or 10min) to obtain a wave-absorbing cyanate ester resin curing system, in the present invention, it is preferred that the open refining mixing temperature after the curing agent is added is 40 ℃.

According to some preferred embodiments, in the step (3), the wave-absorbing cyanate ester resin curing system obtained in the step (2) is triggered and cured in a staged manner at the temperature of 20-300 ℃, so as to obtain wave-absorbing cyanate ester resins with different viscosities.

According to some specific embodiments, the preparation of the wave-absorbing cyanate ester resin comprises the following steps:

(1) putting the cyanate ester resin, the epoxy resin and the absorbent into an internal mixer for internal mixing and coarse mixing to obtain coarse mixed wave-absorbing cyanate ester resin; the molar ratio of the cyanate ester resin to the epoxy resin is 1: (0.5 to 0.7); the cyanate resin is one or more of bisphenol A type cyanate resin, tetramethyl bisphenol F type cyanate resin, bisphenol M type cyanate resin, bisphenol E type cyanate resin and polyfunctional group type cyanate resin;

(2) putting the rough mixed wave-absorbing cyanate ester resin obtained in the step (1) into an open mill for open-refining and fine mixing to obtain fine mixed wave-absorbing cyanate ester resin, and then adding an aliphatic amine curing agent into the fine mixed wave-absorbing cyanate ester resin to obtain a wave-absorbing cyanate ester resin curing system; the molar ratio of the curing agent to the cyanate ester resin is (0.1-0.5): 1;

(3) and (3) sequentially triggering and curing the wave-absorbing cyanate ester resin curing system obtained in the step (2) at a low temperature stage of 50-80 ℃ for 0.5-2 h and at a high temperature stage of 180-250 ℃ for 1-4 h to obtain the wave-absorbing cyanate ester resin with different viscosities.

According to some more specific embodiments, the preparation of the wave-absorbing cyanate ester resin comprises the following steps:

(1) putting the cyanate ester resin, the epoxy resin and the absorbent into an internal mixer for internal mixing and coarse mixing to obtain coarse mixed wave-absorbing cyanate ester resin; the molar ratio of the cyanate ester resin to the epoxy resin is 1: (0.5 to 0.7); the dosage of the absorbent is 5-90% of the sum of the masses of the cyanate ester resin and the epoxy resin; the temperature of the banburying and rough mixing is 20-300 ℃, the time of the banburying and rough mixing is 10-120 min, and the rotating speed of a rotor of the banburying and rough mixing is 10-250 r/min; the cyanate resin is one or more of bisphenol A type cyanate resin, tetramethyl bisphenol F type cyanate resin, bisphenol M type cyanate resin, bisphenol E type cyanate resin and polyfunctional group type cyanate resin; the epoxy resin is one or more of E-51 type epoxy resin, E-44 type epoxy resin, E-20 type epoxy resin, F-44 type epoxy resin and F-51 type epoxy resin; the absorbent is one or more of carbonyl iron, iron-silicon-aluminum, ferrite, conductive carbon black, carbon fiber, graphene, carbon nano tube and silicon carbide.

(2) Placing the rough mixed wave-absorbing cyanate ester resin obtained in the step (1) into an open mill, performing open refining and mixing for 10-80 min at the temperature of 20-300 ℃, obtaining fine mixed wave-absorbing cyanate ester resin after uniform mixing, adding one or more epoxy resin curing agents with different temperatures into the fine mixed wave-absorbing cyanate ester resin, and continuing open refining and mixing for 2-10 min at the temperature of 40 ℃ to obtain a wave-absorbing cyanate ester resin curing system; the molar ratio of the curing agent to the cyanate ester resin is (0.1-0.5): 1; the roll speed of the refining and fine mixing is 2-17 m/min; the epoxy resin curing agent with different temperatures is one or more of aliphatic amine, polyamide, aromatic amine, polyether amine, dicyandiamide and anhydride curing agent.

(3) Triggering the wave-absorbing cyanate resin curing system obtained in the step (2) to be cured in a staged manner at different temperatures to obtain wave-absorbing cyanate resins with different viscosity states; the range of different curing trigger temperatures is 20-300 ℃.

In a second aspect, the invention provides a wave-absorbing cyanate ester resin prepared by the preparation method of the first aspect of the invention.

The invention provides a preparation method of a wave-absorbing cyanate ester resin composite material in a third aspect, which comprises the following steps:

(a) putting the cyanate ester resin, the epoxy resin and the absorbent into an internal mixer for internal mixing and coarse mixing to obtain coarse mixed wave-absorbing cyanate ester resin;

(b) putting the rough mixed wave-absorbing cyanate ester resin obtained in the step (a) into an open mill for open-refining and fine mixing to obtain fine mixed wave-absorbing cyanate ester resin, and then adding a curing agent into the fine mixed wave-absorbing cyanate ester resin to obtain a wave-absorbing cyanate ester resin curing system; the curing agent is selected from one or more of aliphatic amine curing agent, polyamide curing agent, aromatic amine curing agent, polyether amine curing agent, dicyandiamide curing agent and anhydride curing agent;

(c) triggering and curing the wave-absorbing cyanate ester resin curing system obtained in the step (b) at least at one low-temperature stage to obtain a wave-absorbing cyanate ester resin blank (also called as a wave-absorbing cyanate ester resin composite intermediate), and then putting the wave-absorbing cyanate ester resin blank into a calender for calendering to obtain a wave-absorbing cyanate ester resin film;

(d) and (3) layering the multiple layers of wave-absorbing cyanate resin films (placing the layers), and then triggering and curing at least at one high-temperature stage to prepare the wave-absorbing cyanate resin composite material (also can be called as a wave-absorbing cyanate resin composite material).

The viscosity of the wave-absorbing cyanate ester resin in the mixing stage is in the range of 500-20000 cps, uniform dispersion of the absorbent is facilitated in the range, the surface density Cv values of the wave-absorbing cyanate ester resin composites in different areas can reach 0.02-0.05, and the electrical property and the wave-absorbing property stability of the wave-absorbing cyanate ester resin are improved; after low-temperature stage curing, the viscosity of the wave-absorbing cyanate resin is within the viscosity range of 30000-500000 cps, the calendering thickness precision can reach +/-5% of the thickness range, the precise film-forming property is favorable for controlling the wave-absorbing performance of the wave-absorbing cyanate resin composite material, the wave-absorbing performance and the mechanical property of the wave-absorbing cyanate resin film after calendering and film-forming are favorable for ensuring the reflection rate absorption peak frequency value Cv value of the calendered wave-absorbing cyanate resin film after multilayer lamination can be controlled within 0.1; compared with the wave-absorbing performance of the wave-absorbing cyanate ester resin composite material which is not pre-cured, the wave-absorbing cyanate ester resin composite material directly rolls the wave-absorbing resin into a film, thereby being beneficial to improving the stability of the wave-absorbing performance of the wave-absorbing cyanate ester resin composite material; the wave-absorbing cyanate resin film obtained by the invention can control the value of the reflection rate absorption peak frequency Cv within 0.1 after being laminated in multiple layers, is beneficial to the wave-absorbing cyanate resin composite material with good wave-absorbing performance, and can accurately control the thickness of the wave-absorbing cyanate resin composite material within a wider range.

According to some preferred embodiments, the molar ratio of the cyanate ester resin, the curing agent and the epoxy resin is 1: (0.1-0.5): (0.5 to 0.7) (e.g., 1:0.1:0.5, 1:0.1:0.6, 1:0.1:0.7, 1:0.2:0.5, 1:0.2:0.6, 1:0.2:0.7, 1:0.3:0.5, 1:0.3:0.6, 1:0.3:0.7, 1:0.4:0.5, 1:0.4:0.6, 1:0.4:0.7, 1:0.5:0.5, 1:0.5:0.6, or 1:0.5: 0.7); the curing agent is an aliphatic amine curing agent, and preferably, the curing agent is one or more of diethylenetriamine, triethylene tetramine and tetraethylene pentamine.

According to some preferred embodiments, in the step (c), the wave-absorbing cyanate ester resin curing system obtained in the step (b) is triggered and cured at 50-80 ℃ to obtain a wave-absorbing cyanate ester resin blank, and then the wave-absorbing cyanate ester resin blank is placed into a calender for calendering to obtain a wave-absorbing cyanate ester resin film; in the step (d), the wave-absorbing cyanate resin composite material is prepared by laminating and solidifying a plurality of layers of wave-absorbing cyanate resin films at 180-250 ℃.

According to some preferred embodiments, the viscosity of the wave-absorbing cyanate ester resin curing system is 500-20000 cps; the viscosity of the wave-absorbing cyanate ester resin blank is 30000-500000 cps.

According to some specific embodiments, the preparation method of the wave-absorbing cyanate ester resin composite material comprises the following steps:

(a) putting the cyanate ester resin, the epoxy resin and the absorbent into an internal mixer for internal mixing and coarse mixing to obtain coarse mixed wave-absorbing cyanate ester resin; the molar ratio of the cyanate ester resin to the epoxy resin is 1: (0.5 to 0.7); the dosage of the absorbent is 5-90% of the sum of the masses of the cyanate ester resin and the epoxy resin; the temperature of the banburying and rough mixing is 20-300 ℃, the time of the banburying and rough mixing is 10-120 min, and the rotating speed of a rotor of the banburying and rough mixing is 10-250 r/min; the cyanate resin is one or more of bisphenol A type cyanate resin, tetramethyl bisphenol F type cyanate resin, bisphenol M type cyanate resin, bisphenol E type cyanate resin and polyfunctional group type cyanate resin; the epoxy resin is one or more of E-51 type epoxy resin, E-44 type epoxy resin, E-20 type epoxy resin, F-44 type epoxy resin and F-51 type epoxy resin; the absorbent is one or more of carbonyl iron, iron-silicon-aluminum, ferrite, conductive carbon black, carbon fiber, graphene, carbon nano tube and silicon carbide.

(b) Placing the rough mixed wave-absorbing cyanate ester resin obtained in the step (a) into an open mill, carrying out open refining mixing for 10-80 min at 20-300 ℃, obtaining fine mixed wave-absorbing cyanate ester resin after uniform mixing, then adding a curing agent into the fine mixed wave-absorbing cyanate ester resin, and carrying out open refining mixing for 2-10 min at 40 ℃ to obtain a wave-absorbing cyanate ester resin curing system; the molar ratio of the curing agent to the cyanate ester resin is (0.1-0.5): 1; the roll speed of the refining and fine mixing is 2-17 m/min; preferably, the curing agent is one or more of diethylenetriamine, triethylene tetramine and tetraethylene pentamine.

(c) Triggering and curing the wave-absorbing cyanate ester resin curing system obtained in the step (b) at a low temperature stage of 50-80 ℃ to obtain a wave-absorbing cyanate ester resin blank, and then putting the wave-absorbing cyanate ester resin blank into a calender for calendering to obtain a wave-absorbing cyanate ester resin film; the temperature of the rolling is 100-200 ℃ (e.g., 100 ℃, 120 ℃, 140 ℃, 160 ℃, 180 ℃ or 200 ℃), the pressure of the rolling is 500-1500N (e.g., 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400 or 1500N), the speed of the rolling is 3-6 m/s (e.g., 3, 4, 5 or 6m/s), and the thickness of the rolling is 0.1-5 mm, preferably 1-2 mm (e.g., 1, 1.5 or 2 mm); in the present invention, the calendered thickness (calendered thickness) refers to the thickness of each layer of the wave-absorbing cyanate ester resin film.

(d) And (3) laminating the multiple layers of wave-absorbing cyanate resin films, and then triggering and curing at a high temperature stage of 180-250 ℃ to prepare the wave-absorbing cyanate resin composite material.

In a fourth aspect, the invention provides a wave-absorbing cyanate ester resin composite material prepared by the preparation method in the third aspect.

The invention will be further illustrated by way of example, but the scope of protection is not limited to these examples.

Example 1

(a) Putting cyanate ester resin (bisphenol A type cyanate ester resin), epoxy resin (E-51 type epoxy resin) and absorbent (carbonyl iron powder) into an internal mixer for banburying and coarse mixing to obtain coarse mixed wave-absorbing cyanate ester resin; wherein the molar ratio of the bisphenol A type cyanate ester resin to the E-51 type epoxy resin is 1:0.6, and the addition amount of the carbonyl iron powder is 50% of the sum of the mass of the bisphenol A type cyanate ester resin and the mass of the E-51 type epoxy resin; the technological conditions of banburying and coarse mixing are as follows: the temperature of the banburying and rough mixing is 120 ℃, the time of the banburying and rough mixing is 45min, and the rotating speed of a rotor of the banburying and rough mixing is 200 r/min.

(b) Placing the rough mixed wave-absorbing cyanate ester resin obtained in the step (a) into an open mill, performing refining and fine mixing for 45min at the temperature of 120 ℃, uniformly mixing to obtain fine mixed wave-absorbing cyanate ester resin, adding a curing agent (triethylene tetramine) into the fine mixed wave-absorbing cyanate ester resin, and continuously performing refining and fine mixing for 5min at the temperature of 40 ℃ to obtain a wave-absorbing cyanate ester resin curing system; the molar ratio of the curing agent to the bisphenol A cyanate ester resin is 0.2: 1; the roll speed for the refining and the fine mixing is 12 m/min.

(c) Triggering and curing the wave-absorbing cyanate ester resin curing system obtained in the step (b) for 1h at the low temperature stage of 50 ℃ to obtain a wave-absorbing cyanate ester resin blank, and then putting the wave-absorbing cyanate ester resin blank into a calender for calendering to obtain a wave-absorbing cyanate ester resin film; the process conditions of calendering are as follows: the temperature of the rolling is 150 ℃, the pressure of the rolling is 1000N, the speed of the rolling is 4m/s, and the thickness of the rolling is 1.5 mm.

(d) And (c) placing the four layers of wave-absorbing cyanate resin films obtained in the step (c) in a laminated mode (laminated layer laying mode), and then triggering and curing for 3 hours at a high temperature stage of 200 ℃ to obtain the wave-absorbing cyanate resin composite material.

In this embodiment, the viscosity of the wave-absorbing cyanate ester resin curing system obtained in step (b) and the viscosity of the wave-absorbing cyanate ester resin blank obtained in step (c) are tested, and the results are shown in table 1.

The wave-absorbing cyanate ester resin composite material prepared by the embodiment has an average reflectivity absorption peak value of-10.6 dB at 3GHz, and the total thickness of the wave-absorbing cyanate ester resin composite material is 6 mm.

In the embodiment, the film thickness, the surface density and the wave-absorbing performance of the wave-absorbing cyanate ester resin composite material at different positions are measured, and the Cv (discrete coefficient) value of typical data is used to characterize the process stability, so that the film thickness, the surface density and the wave-absorbing performance of the wave-absorbing cyanate ester resin composite material prepared in the embodiment are controlled uniformly, the preparation process stability of the embodiment is quite good, and the results are shown in table 1.

In the invention, the smaller the film thickness Cv value, the surface density Cv value and the reflectivity absorption peak frequency Cv value are, the better the uniformity of the film thickness and the surface density and the better the stability of the wave-absorbing performance of the prepared wave-absorbing cyanate resin composite material are.

Example 2

Example 2 is essentially the same as example 1, except that:

in the step (a), the cyanate ester resin is tetramethyl bisphenol F type cyanate ester resin, the epoxy resin is E-44 type epoxy resin, and the absorbent is carbonyl iron powder; the molar ratio of the tetramethyl bisphenol F type cyanate ester resin to the E-44 type epoxy resin is 1:0.5, and the addition amount of the carbonyl iron powder is 50% of the sum of the masses of the tetramethyl bisphenol F type cyanate ester resin and the E-44 type epoxy resin.

In step (b), the curing agent is diethylenetriamine; the molar ratio of the curing agent to the tetramethyl bisphenol F type cyanate ester resin is 0.3: 1.

The average reflection rate absorption peak value of the wave-absorbing cyanate ester resin composite material prepared by the embodiment at 3GHz is-10.0 dB.

The same performance test as in example 1 was carried out for this example, and the results are shown in Table 1.

Example 3

Example 3 is essentially the same as example 1, except that:

in the step (a), the cyanate ester resin is bisphenol E type cyanate ester resin, the epoxy resin is F-44 type epoxy resin, and the absorbent is carbonyl iron powder; the molar ratio of the bisphenol E type cyanate ester resin to the F-44 type epoxy resin is 1:0.7, and the adding amount of the carbonyl iron powder is 50% of the sum of the mass of the bisphenol E type cyanate ester resin and the mass of the F-44 type epoxy resin.

In step (b), the curing agent is tetraethylenepentamine; the molar ratio of the curing agent to the bisphenol E type cyanate ester resin is 0.4: 1.

The average reflection rate absorption peak value of the wave-absorbing cyanate ester resin composite material prepared by the embodiment at 3GHz is-10.4 dB.

The same performance test as in example 1 was carried out for this example, and the results are shown in Table 1.

Example 4

Example 4 is essentially the same as example 1, except that:

in the step (a), the molar ratio of the bisphenol A type cyanate ester resin to the E-51 type epoxy resin is 1: 0.2.

The average reflection rate absorption peak value of the wave-absorbing cyanate ester resin composite material prepared by the embodiment at 3GHz is-10.5 dB.

The same performance test as in example 1 was carried out for this example, and the results are shown in Table 1.

Example 5

Example 5 is essentially the same as example 1, except that:

in the step (a), the molar ratio of the bisphenol A type cyanate ester resin to the E-51 type epoxy resin is 1: 0.8.

The average reflection rate absorption peak value of the wave-absorbing cyanate ester resin composite material prepared by the embodiment at 3GHz is-11.0 dB.

The same performance test as in example 1 was carried out for this example, and the results are shown in Table 1.

Comparative example 1

(a) Same as in step (a) of example 1.

(b) And (b) placing the rough mixed wave-absorbing cyanate ester resin obtained in the step (a) into an open mill, and carrying out refining and mixing for 45min at the temperature of 120 ℃, and after uniform mixing, obtaining the refined mixed wave-absorbing cyanate ester resin, wherein the roll speed of the refining and mixing is 12 m/min.

(c) Putting the fine mixed wave-absorbing cyanate ester resin obtained in the step (b) into a calender for calendering to obtain a wave-absorbing cyanate ester resin film; the process conditions of calendering are as follows: the temperature of the rolling is 150 ℃, the pressure of the rolling is 1000N, the speed of the rolling is 4m/s, and the thickness of the rolling is 1.5 mm.

(d) Same as in step (d) of example 1.

The average reflection rate absorption peak value of the wave-absorbing cyanate ester resin composite material prepared by the comparative example at 3GHz is-9.9 dB.

The viscosities of the rough mixed wave-absorbing resin and the fine mixed wave-absorbing cyanate ester resin in the comparative example are equal to 7100 cps.

The comparative example was subjected to the same performance test as in example 1, and the results are shown in Table 1.

Comparative example 2

Firstly, putting epoxy resin (E-51 type epoxy resin) and carbonyl iron powder (absorbent) into an internal mixer for banburying and coarse mixing to obtain coarse mixing wave-absorbing resin; wherein the addition amount of the carbonyl iron powder is 50 percent of the mass of the epoxy resin; the technological conditions of banburying and coarse mixing are as follows: the temperature of the banburying and rough mixing is 100 ℃, the time of the banburying and rough mixing is 45min, and the rotating speed of a rotor of the banburying and rough mixing is 200 r/min.

Secondly, putting the rough mixed wave-absorbing resin obtained in the step I into a resin open mill for refining and fine mixing for 45min to obtain fine mixed wave-absorbing resin which is uniformly mixed, and then adding m-xylylenediamine (curing agent) into the fine mixed wave-absorbing resin for continuously refining and fine mixing for 5 min; the technological conditions for refining and mixing are as follows: the temperature of the refining and mixing is 100 ℃, and the roller speed of the refining and mixing is 12 m/min; the curing agent is 1.7 wt% of the amount of the E-51 type epoxy resin.

Thirdly, the fine mixed wave-absorbing resin added with the curing agent obtained in the second step is placed into a precision calender for calendering to obtain a wave-absorbing resin adhesive film (wave-absorbing epoxy resin film); the process conditions of calendering are as follows: the temperature of the rolling is 150 ℃, the pressure of the rolling is 1000N, the speed of the rolling is 4m/s, and the thickness of the rolling is 1.5 mm.

Fourthly, the wave-absorbing epoxy resin film obtained in the fourth step is laminated and placed and then solidified for 3 hours at the temperature of 200 ℃ to obtain the wave-absorbing epoxy resin composite material.

The average reflectivity absorption peak value of the wave-absorbing epoxy resin composite material prepared by the comparative example at 3GHz is-10.7 dB.

In the comparative example, the viscosity of the rough mixed wave-absorbing resin is equal to that of the fine mixed wave-absorbing resin without the curing agent and is 5800cps, and the viscosity of the fine mixed wave-absorbing resin after the curing agent is added, refined and mixed for 5min is 6300 cps.

The comparative example was subjected to the same performance test as in example 1, and the results are shown in Table 1.

In particular, the symbol "/" in table 1 indicates that no corresponding reference is present.

The invention has not been described in detail and is in part known to those of skill in the art.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.