Polyurea-based absorbing gel for electronic device packaging and preparation method thereof

Abstract

The present invention provides a polyurea-based absorbing gel for electronic device packaging and a preparation method thereof. The absorbing gel is obtained by the polymerization reaction of components A and B; wherein component A includes polyetheramine, isocyanate, nano-absorbing filler, and solvent; and component B includes polyaspartic acid ester and a defoaming agent. Compared with traditional electronic device packaging materials, the polyurea-based absorbing gel of the present invention has the following advantages: excellent absorbing performance and adjustable absorption band. By adjusting the component ratio and thickness, impedance matching can be optimized to achieve minimum reflection loss and dynamic adjustment of the absorption band; good flexibility and ductility enable it to closely fit complex geometric surfaces to form a uniform absorbing layer, ensuring the consistency of the electromagnetic wave absorption effect; outstanding self-repairing performance. Its molecular structure contains a large number of dynamic chemical bonds, which can quickly restore its original performance through external stimulation, reducing maintenance costs and increasing service life.

Description

Technical Field

[0001] The present invention belongs to the technical field of absorbing materials, and in particular relates to a polyurea-based absorbing gel for electronic device packaging. The present invention also relates to a method for preparing the polyurea-based absorbing gel for electronic device packaging. Background Art

[0002] With the rapid development of electronic technology, the application of electronic devices and components in daily life and industrial production is becoming more and more extensive, and the resulting electromagnetic interference problem is becoming more and more prominent. How to effectively improve the electromagnetic protection capabilities of electronic devices and ensure the safety and reliability of their operation has become a major challenge facing the electronic technology industry.

[0003] In order to achieve better wave-absorbing effects, traditional electronic packaging materials usually need to add a large amount of wave-absorbing fillers or increase the thickness, which increases the overall weight of the material and is not conducive to the lightweight production of electronic devices. At the same time, complex structural designs also place higher demands on the adaptability of packaging materials, requiring the development of more sophisticated molding processes, which significantly increases production costs. In addition, traditional electronic packaging materials usually do not have self-healing properties. Once the joints are impact-deformed or damaged, electromagnetic leakage will occur and their protective properties will be lost.

[0004] Polyurea is an organic polymer material formed by the polymerization of polyamines and isocyanates. When prepared in a gel state, it exhibits excellent plasticity, allowing it to conform perfectly to complex geometric surfaces. Compared to other gels, polyurea gel is more stable and less susceptible to environmental influences. When subjected to external forces, it can deform significantly without breaking or damaging. Even if scratched, it can repair cracks. Furthermore, polyurea gel is easily processable and can be prepared through low-cost processes such as mold casting and reaction injection molding, showing great potential for application in electronic device packaging.

[0005] A Chinese patent application, Application No. 201310113225.3, on the preparation of a polyurethane absorbing gel material, discloses a polyurethane absorbing gel material with high absorption performance, a simple manufacturing process, and on-site foaming. However, damage cannot be promptly repaired, making long-term electromagnetic protection difficult to achieve. A Chinese patent application, Application No. 202311706165.6, on the preparation of a clay-like composite absorbing material, discloses a clay-like gelatin / tannic acid / polyvinyl alcohol composite absorbing material. This composite absorbing material has strong plasticity, but the organic matrix used is unstable and easily affected by the external environment, leading to performance degradation. Therefore, the development of electronic packaging absorbing materials with excellent absorption performance, high stability, strong plasticity, easy repairability, and lightweightness has become a current priority. Summary of the Invention

[0006] The purpose of the present invention is to provide a polyurea-based absorbing gel for electronic device packaging, which solves the problems of poor plasticity and self-repairing properties of existing absorbing gels.

[0007] Another object of the present invention is to provide a method for preparing the polyurea-based absorbing gel for electronic device packaging.

[0008] The technical solution adopted by the present invention is a polyurea-based absorbing gel for electronic device packaging, which is obtained by polymerization reaction of components A and B; wherein component A includes polyetheramine, isocyanate, nano-absorbing filler and solvent; component B includes polyaspartic acid ester and defoaming agent; in terms of mass percentage, polyetheramine accounts for 33%-35% of the absorbing gel, isocyanate accounts for 14%-16% of the absorbing gel; nano-absorbing filler accounts for 0.3%-0.5% of the absorbing gel; solvent accounts for 16.9%-17.1% of the absorbing gel; polyaspartic acid ester accounts for 30%-30.2% of the absorbing gel; and defoaming agent accounts for 3.4%-3.6% of the absorbing gel.

[0009] The technical solution of the present invention is characterized in that:

[0010] Polyetheramine is a polymer with a polyether structure as the main chain and an amino group as the terminal active functional group. Its chemical formula is C 3n+ 3H 6n+10 O n N2 is specifically one or more combinations of molecular weights of 5000, 2000, 400, and 230; when the molecular weight is 5000, n is 84-85; when the molecular weight is 2000, n is 33-34; when the molecular weight is 400, n is 5-6; and when the molecular weight is 230, n is 2-3.

[0011] The isocyanate is an aliphatic diisocyanate, specifically any one or more combinations of isophorone diisocyanate, hexamethylene diisocyanate, and dicyclohexylmethane diisocyanate; the polyaspartic acid ester is an aliphatic secondary amine, specifically any one or more combinations of F520, F524, and F420.

[0012] The nano-absorbing filler is one or more combinations of one-dimensional carbon nanotubes, two-dimensional graphene or MXene nanosheets, and three-dimensional ferrite nanoparticles, with a particle size ranging from 0.1 nm to 100 nm; the solvent is a polar organic solvent, specifically any one of ethanol, acetone, dimethylformamide, methylacetamide, and dimethyl sulfoxide; the defoaming agent is any one of LF8750 defoaming agent, BYK-024 defoaming agent, and 6250B silicone defoaming agent.

[0013] Another technical solution adopted by the present invention is a method for preparing a polyurea-based absorbing gel for electronic device packaging, which specifically comprises the following steps:

[0014] S1. Prepolymerization of component A: subjecting the polyetheramine to a high-temperature dehydration treatment to obtain a dehydrated polyetheramine; adding the dehydrated polyetheramine to a container, stirring in a water bath while continuously introducing nitrogen, adding isocyanate and stirring to obtain a prepolymer of component A;

[0015] Preparation of Component A: Dissolve the nano-absorbing filler in a solvent, ultrasonicate it, and then add the prepolymer of Component A. Then, increase the temperature and speed, and stir for a certain period of time to obtain Component A.

[0016] S3 gelation process: Component A and polyaspartic acid ester are mixed in a certain amount ratio, followed by adding a defoaming agent and stirring to obtain a mixed product;

[0017] S4. Preform molding: The mixed product is cast into a preheated fixed-size mold, and then subjected to a degassing treatment. After the reaction is completed, the microwave-absorbing gel is obtained.

[0018] Another technical solution of the present invention is also characterized in that:

[0019] The specific steps of S1 are: placing a polyetheramine in a beaker, performing a high-temperature dehydration treatment in a vacuum drying oven, and slowly cooling to room temperature after the reaction is completed to obtain a dehydrated polyetheramine; adding the dehydrated polyetheramine to a three-necked flask, stirring in a 25°C water bath while continuously introducing nitrogen, then adding isocyanate in a certain amount and ratio, and continuously stirring until the reaction is complete to obtain a prepolymer of component A;

[0020] The mass percentage of the polyetheramine is 33%-35%, the mass percentage of the isocyanate is 14%-16%, and the total mass percentage of the polyetheramine and the isocyanate accounts for 49% of the mass percentage of the absorbing gel;

[0021] The process parameters in this step are as follows: the temperature of the vacuum drying oven is set to 120°C, the vacuum degree is ≤-90kPa, and the dehydration time is 1h-2h; the water bath stirring temperature is 25°C, and the nitrogen flow rate is 20mL / min; the stirring speed when adding isocyanate is 30r / min-50r / min, and the stirring time is 30min~1h.

[0022] The specific steps of S2 are:

[0023] A certain amount of nano-absorbing filler is dissolved in an appropriate amount of solvent, and after ultrasonic treatment, it is added to the prepolymer of component A obtained in S1. Then, the temperature and the rotation speed are increased, and after stirring for a certain period of time, a semi-fluid paste of component A is obtained;

[0024] The mass percentage of the nanometer absorbing filler is 0.3%-0.5%, and the mass percentage of the solvent is 16.9%-17.1%, and the total accounts for 17.4% of the mass percentage of the absorbing gel;

[0025] The process parameters in this step are: ultrasonic frequency 120 kHz, ultrasonic time 30 min, stirring temperature 85° C., stirring speed 120 r / min-150 r / min, and stirring time 3 h.

[0026] The specific steps of S3 are:

[0027] Mix component A and polyaspartic acid ester in a certain ratio, then add an appropriate amount of defoamer and stir for a certain period of time until the gelation reaction is completed;

[0028] The mass percentage of polyaspartic acid ester is 30%-30.2%, and the mass percentage of defoaming agent is 3.4%-3.6%, and the total accounts for 33.6% of the mass percentage of the absorbing gel;

[0029] The process parameters in this step are: stirring temperature 25°C, stirring speed 30r / min-50r / min, and stirring time 5min-10min.

[0030] The specific steps of S4 are:

[0031] The mixed product is cast into a preheated fixed-size mold, and then transferred to a vacuum drying oven for defoaming. After the reaction is completed, a polyurea-based absorbing gel is obtained;

[0032] The process parameters in this step are: mold preheating temperature is 60°C, mold size can be designed according to actual needs, defoaming vacuum degree ≤-90kPa, and defoaming time is 10min-30min.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] Excellent absorption performance and adjustable absorption band. The nano-absorbing fillers used in this invention all have a large specific surface area, forming a conductive network within the polyurea matrix, promoting conductivity loss and generating interfacial polarization loss. The absorbing fillers and polyurea matrix also provide dipole polarization loss. By adjusting the composition ratio and controlling the thickness, impedance matching can be optimized, achieving minimum reflection loss and dynamic adjustment of the absorption band.

[0035] The absorbing gel of the present invention exhibits excellent flexibility and ductility, primarily due to the polyurea segments in its molecular structure, which can displace and rotate under external forces. Furthermore, the low modulus and high ductility of the polyurea-based absorbing gel enable it to conform tightly to the surface of the coating, forming a uniform absorbing layer and ensuring uniform and consistent electromagnetic wave absorption.

[0036] Excellent self-healing properties ensure material reliability and service life. A key feature of polyurea-based absorbing gel is its self-healing properties. Its molecular structure contains numerous dynamic chemical bonds, which, after damage, can reversibly break and reform in response to external stimuli (such as heat, light, and solvents), rapidly restoring its original performance. This not only reduces performance degradation caused by damage but also lowers maintenance costs and frequency, improving the material's economical and environmental performance.

[0037] In summary, the present invention provides a polyurea-based absorbing gel for electronic device packaging, which has the characteristics of absorbing waves, plasticity and self-repairing, and shows great application potential in the field of electronic device packaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the molecular structure of the polyurea-based absorbing gel for electronic device packaging of the present invention.

[0039] Figure 2 This is a physical display diagram of the polyurea-based absorbing gel for electronic device packaging of the present invention. DETAILED DESCRIPTION

[0040] In order to make the technical solution of the present invention clearer, a more comprehensive and detailed description will be given below in conjunction with specific implementation cases.

[0041] A polyurea-based absorbing gel for electronic device packaging is obtained by polymerization reaction of components A and B. Component A includes polyetheramine, isocyanate, nano-absorbing filler, and solvent; component B includes polyaspartic acid ester and a defoamer. In terms of mass percentage, the polyetheramine accounts for 33%-35% of the absorbing gel, the isocyanate accounts for 14%-16% of the absorbing gel, the nano-absorbing filler accounts for 0.3%-0.5% of the absorbing gel, the solvent accounts for 16.9%-17.1% of the absorbing gel, the polyaspartic acid ester accounts for 30%-30.2% of the absorbing gel, and the defoamer accounts for 3.4%-3.6% of the absorbing gel.

[0042] Polyetheramine is a polymer with a polyether structure as the main chain and an amino group as the terminal active functional group. Its chemical formula is C 3n+ 3H 6n+10 O n N2 is specifically one or more combinations of molecular weights of 5000, 2000, 400, and 230; when the molecular weight is 5000, n is 84-85; when the molecular weight is 2000, n is 33-34; when the molecular weight is 400, n is 5-6; and when the molecular weight is 230, n is 2-3.

[0043] The isocyanate is an aliphatic diisocyanate, specifically any one or more combinations of isophorone diisocyanate, hexamethylene diisocyanate, and dicyclohexylmethane diisocyanate; the polyaspartic acid ester is an aliphatic secondary amine, specifically any one or more combinations of F520, F524, and F420.

[0044] The nano-absorbing filler is one or more combinations of one-dimensional carbon nanotubes, two-dimensional graphene or MXene nanosheets, and three-dimensional ferrite nanoparticles, with a particle size ranging from 0.1 nm to 100 nm; the solvent is a polar organic solvent, specifically any one of ethanol, acetone, dimethylformamide, methylacetamide, and dimethyl sulfoxide; the defoaming agent is any one of LF8750 defoaming agent, BYK-024 defoaming agent, and 6250B silicone defoaming agent.

[0045] The preparation method of polyurea-based absorbing gel for electronic device packaging specifically comprises the following steps:

[0046] S1. Prepolymerization of Component A: Place polyetheramine in a beaker and dehydrate it at high temperature in a vacuum drying oven. After the reaction is complete, slowly cool it to room temperature to obtain dehydrated polyetheramine. Add the dehydrated polyetheramine to a three-necked flask, stir it in a 25°C water bath while continuously purging it with nitrogen. Then, add isocyanate in a certain amount and continue stirring until the reaction is complete to obtain Component A prepolymer.

[0047] The mass percentage of the polyetheramine is 33%-35%, the mass percentage of the isocyanate is 14%-16%, and the total mass percentage of the polyetheramine and the isocyanate accounts for 49% of the mass percentage of the absorbing gel;

[0048] The process parameters in this step are as follows: the temperature of the vacuum drying oven is set to 120°C, the vacuum degree is ≤-90 kPa, and the dehydration time is 1 h to 2 h; the water bath stirring temperature is 25°C, and the nitrogen flow rate is 20 mL / min; the stirring speed when adding isocyanate is 30 r / min to 50 r / min, and the stirring time is 30 min to 1 h.

[0049] S2. Preparation of component A: A certain amount of nano-absorbing filler is dissolved in an appropriate amount of solvent, ultrasonically treated and added to the prepolymer component A obtained in S1, then the temperature and speed are increased, and stirring is continued for a certain period of time to obtain a semi-fluid paste of component A;

[0050] The mass percentage of the nanometer absorbing filler is 0.3%-0.5%, and the mass percentage of the solvent is 16.9%-17.1%, and the total accounts for 17.4% of the mass percentage of the absorbing gel;

[0051] The process parameters in this step are: ultrasonic frequency 120 kHz, ultrasonic time 30 min, stirring temperature 85°C, stirring speed 120 r / min - 150 r / min, and stirring time 3 h.

[0052] S3 gelation process: Component A and polyaspartic acid ester are mixed in a certain amount ratio, followed by adding an appropriate amount of defoamer and stirring for a certain time until the gelation reaction is complete;

[0053] The mass percentage of polyaspartic acid ester is 30%-30.2%, and the mass percentage of defoaming agent is 3.4%-3.6%, and the total accounts for 33.6% of the mass percentage of the absorbing gel;

[0054] The process parameters in this step are: stirring temperature 25°C, stirring speed 30 r / min-50 r / min, and stirring time 5 min-10 min.

[0055] S4 preform molding: The mixed product is cast into a preheated fixed size mold, and then transferred to a vacuum drying oven for degassing. After the reaction is completed, a polyurea-based absorbing gel is obtained;

[0056] The process parameters in this step are as follows: mold preheating temperature is 60°C, mold size can be designed according to actual needs, defoaming vacuum degree ≤-90 kPa, and defoaming time is 10 min-30 min.

[0057] Example 1

[0058] S1. Prepolymerization of Component A: Place 9.9 g of polyetheramine (molecular weight, 2000) in a beaker and dehydrate it at high temperature in a vacuum drying oven. After the reaction is complete, slowly cool it to room temperature to obtain the dehydrated polyetheramine. Add the dehydrated polyetheramine to a three-necked flask, stir in a 25°C water bath while continuously purging with nitrogen, then add 4.8 g of isophorone diisocyanate and continue stirring until the reaction is complete to obtain the Component A prepolymer.

[0059] The mass percentage of polyetheramine is 33%, the mass percentage of isophorone diisocyanate is 16%, and the total mass percentage of polyetheramine and isophorone diisocyanate accounts for 49% of the mass percentage of the absorbing gel;

[0060] The process parameters in this step are as follows: the temperature of the vacuum drying oven is set to 120°C, the vacuum degree is ≤-90 kPa, and the dehydration time is 1 h; the water bath stirring temperature is 25°C, and the nitrogen flow rate is 20 mL / min; the stirring speed when adding isophorone diisocyanate is 30 r / min, and the stirring time is 30 min.

[0061] S2. Preparation of Component A: Dissolve 0.09 g of MXene nanosheets in 5.46 ml of dimethylacetamide, ultrasonically treat, and add to the prepolymer of Component A obtained in S1. Then, increase the temperature and rotational speed, and stir for a period of time to obtain a semifluid paste of Component A.

[0062] The mass percentage of the nano-absorbing filler MXene nanosheets is 0.3%, and the mass percentage of the solvent dimethylformamide is 17.1%, and the total accounts for 17.4% of the mass percentage of the absorbing gel;

[0063] The process parameters in this step are: ultrasonic frequency 120 kHz, ultrasonic time 30 min, stirring temperature 85°C, stirring speed 120 r / min, and stirring time 3 h.

[0064] S3 gelation process: Component A was mixed with 9 g of polyaspartic acid ester F420, followed by the addition of 1.08 ml of LF8750 defoamer and stirring for a certain period of time until the gelation reaction was complete;

[0065] The mass percentage of polyaspartic acid ester F420 is 30%, the mass percentage of LF8750 defoaming agent is 3.6%, and the total accounts for 33.6% of the mass percentage of the absorbing gel;

[0066] The process parameters in this step are: stirring temperature 25°C, stirring speed 30 r / min, and stirring time 5 min.

[0067] S4 preform molding: The mixed product is cast into a preheated fixed size mold, and then transferred to a vacuum drying oven for degassing. After the reaction is completed, a polyurea-based absorbing gel is obtained;

[0068] The process parameters in this step are as follows: mold preheating temperature is 60°C, mold size can be designed according to actual needs, defoaming vacuum degree ≤-90 kPa, and defoaming time is 10 min.

[0069] Example 2

[0070] S1. Prepolymerization of Component A: Place 10.5 g of polyetheramine (molecular weight, 5000) in a beaker and dehydrate it at high temperature in a vacuum drying oven. After the reaction is complete, slowly cool it to room temperature to obtain the dehydrated polyetheramine. Add the dehydrated polyetheramine to a three-necked flask, stir in a 25°C water bath while continuously purging with nitrogen, then add 4.2 g of hexamethylene diisocyanate and continue stirring until the reaction is complete to obtain the Component A prepolymer.

[0071] The mass percentage of polyetheramine is 35%, the mass percentage of hexamethylene diisocyanate is 14%, and the total mass percentage of polyetheramine and isocyanate accounts for 49% of the mass percentage of the absorbing gel;

[0072] The process parameters in this step are as follows: the temperature of the vacuum drying oven is set to 120°C, the vacuum degree is ≤-90 kPa, and the dehydration time is 2 h; the water bath stirring temperature is 25°C, and the nitrogen flow rate is 20 mL / min; the stirring speed of adding hexamethylene diisocyanate is 50 r / min, and the stirring time is 1 h.

[0073] S2. Preparation of Component A: Dissolve 0.15 g of one-dimensional carbon nanotubes in 5.34 ml of dimethylformamide, sonicate, and add to the prepolymer of Component A obtained in S1. Then, increase the temperature and rotational speed, and stir for a period of time to obtain a semifluid paste of Component A.

[0074] The mass percentage of the one-dimensional carbon nanotube nanometer absorbing filler is 0.5%, and the mass percentage of the solvent dimethylformamide is 16.9%, and the total accounts for 17.4% of the mass percentage of the absorbing gel;

[0075] The process parameters in this step are: ultrasonic frequency 120 kHz, ultrasonic time 30 min, stirring temperature 85°C, stirring speed 150 r / min, and stirring time 3 h.

[0076] S3 gelation process: Component A was mixed with 9.06 g of polyaspartic acid ester resin F524, followed by the addition of 1.02 ml of BYK-024 defoamer and stirring for a certain period of time until the gelation reaction was complete;

[0077] The mass percentage of polyaspartic acid ester F524 is 30.2%, and the mass percentage of BYK-024 defoamer is 3.4%, and the total accounts for 33.6% of the mass percentage of the absorbing gel;

[0078] The process parameters in this step are: stirring temperature 25°C, stirring speed 50 r / min, and stirring time 10 min.

[0079] S4 preform molding: The mixed product is cast into a preheated fixed size mold, and then transferred to a vacuum drying oven for degassing. After the reaction is completed, a polyurea-based absorbing gel is obtained;

[0080] The process parameters in this step are as follows: mold preheating temperature is 60°C, mold size can be designed according to actual needs, defoaming vacuum degree ≤-90 kPa, and defoaming time is 30 min.

[0081] Example 3

[0082] S1. Prepolymerization of Component A: Place 10.2 g of polyetheramine (molecular weight, 2000) in a beaker and dehydrate it at high temperature in a vacuum drying oven. After the reaction is complete, slowly cool it to room temperature to obtain the dehydrated polyetheramine. Add the dehydrated polyetheramine to a three-necked flask, stir in a 25°C water bath while continuously purging with nitrogen, then add 4.5 g of isophorone diisocyanate and continue stirring until the reaction is complete to obtain the Component A prepolymer.

[0083] The mass percentage of polyetheramine is 34%, the mass percentage of isophorone diisocyanate is 15%, and the total mass percentage of polyetheramine and isophorone diisocyanate accounts for 49% of the mass percentage of the absorbing gel;

[0084] The process parameters in this step are as follows: the temperature of the vacuum drying oven is set to 120°C, the vacuum degree is ≤-90 kPa, and the dehydration time is 1.5 h; the water bath stirring temperature is 25°C, and the nitrogen flow rate is 20 mL / min; the stirring speed when adding isophorone diisocyanate is 40 r / min, and the stirring time is 45 min.

[0085] S2. Preparation of Component A: Dissolve 0.12 g of graphene in 4.65 ml of dimethyl sulfoxide (DMSO), ultrasonically treat, and add to the prepolymer of Component A obtained in S1. Then, increase the temperature and rotational speed, and stir for a period of time to obtain a semifluid paste of Component A.

[0086] The mass percentage of the nanometer wave-absorbing filler graphene is 0.4%, and the mass percentage of the solvent dimethyl sulfoxide is 17%, and the total accounts for 17.4% of the mass percentage of the wave-absorbing gel;

[0087] The process parameters in this step are: ultrasonic frequency 120 kHz, ultrasonic time 30 min, stirring temperature 85°C, stirring speed 130 r / min, and stirring time 3 h.

[0088] S3 gelation process: Component A was mixed with 9.03 g of polyaspartic acid resin F520, followed by the addition of 1.05 ml of 6250B silicone defoamer and stirring for a certain period of time until the gelation reaction was complete;

[0089] The mass percentage of polyaspartic acid ester F520 is 30.1%, and the mass percentage of 6250B silicone defoamer is 3.5%, and the total accounts for 33.6% of the mass percentage of the absorbing gel;

[0090] The process parameters in this step are: stirring temperature 25°C, stirring speed 40 r / min, and stirring time 7 min.

[0091] S4 preform molding: The mixed product is cast into a preheated fixed size mold, and then transferred to a vacuum drying oven for degassing. After the reaction is completed, a polyurea-based absorbing gel is obtained;

[0092] The process parameters in this step are as follows: mold preheating temperature is 60°C, mold size can be designed according to actual needs, defoaming vacuum degree ≤-90 kPa, and defoaming time is 20 min.

[0093] Table 1 compares the self-healing and absorbing properties of the polyurea-based absorbing gels described in Examples 1, 2, and 3 with those of polyurethane absorbing gels and polyacrylic acid organic gels. As can be seen from Table 1, the self-healing efficiency of the polyurea-based absorbing gels described in Examples 1, 2, and 3 is superior to that of the polyacrylic acid organic gel, with a shorter self-healing time and higher efficiency. This is mainly attributed to the hydrogen bond interactions in the gel molecular structure, which enable reassembly after breakage to restore the original structure. In addition, the minimum reflection loss value of the polyurea-based absorbing gels described in Examples 1, 2, and 3 is also superior to that of the polyurethane absorbing gel. This is due to the difference in fillers, which leads to differences in absorbing properties. Conductive carbon black and ferrite are based on conductive loss and magnetic loss mechanisms, respectively, while graphene and MXene can dissipate electromagnetic waves through conductive loss and dielectric loss, and on the other hand, their high specific surface area and unique two-dimensional nanostructure enable further enhanced absorbing performance through mechanisms such as interface polarization and dipole polarization. Therefore, their minimum reflection loss is superior to that of the polyurethane absorbing gel.

[0094] Table 1 Comparison of self-healing and absorbing properties of the polyurea-based absorbing gels, polyurethane absorbing gels, and polyacrylic acid organic gels in Examples 1-3

[0095]

[0096] Figure 1 This is a schematic diagram of the molecular structure of the polyurea-based microwave-absorbing gel prepared in this invention. As can be seen, the soft and hard segments in the polyurea molecular chains are cross-linked to form a three-dimensional gel network, and the nano-absorbing fillers are covalently grafted onto the polyurea molecular chains and evenly distributed within the polyurea matrix. Figure 2 This is a physical display of the polyurea-based absorbing gel prepared by the present invention. It can be seen that the polyurea-based absorbing gel prepared by the present invention has excellent plasticity and can be perfectly adhered to the surface of electronic equipment.

Claims

1. Polyurea-based absorbing gel for electronic device packaging, characterized by: The absorbing gel is obtained by polymerization reaction of components A and B; wherein component A comprises polyetheramine, isocyanate, nano-absorbing filler and solvent; component B comprises polyaspartic acid ester and defoaming agent; in terms of mass percentage, polyetheramine accounts for 33%-35% of the absorbing gel, isocyanate accounts for 14%-16% of the absorbing gel; nano-absorbing filler accounts for 0.3%-0.5% of the absorbing gel; solvent accounts for 16.9%-17.1% of the absorbing gel; polyaspartic acid ester accounts for 30%-30.2% of the absorbing gel; and defoaming agent accounts for 3.4%-3.6% of the absorbing gel; The polyaspartic acid ester is an aliphatic secondary amine, specifically any one or more combinations of F520, F524 and F420; The nano-wave absorbing filler is one or more combinations of one-dimensional carbon nanotubes, two-dimensional graphene or MXene nanosheets, and three-dimensional ferrite nanoparticles, and the particle size is between 0.1nm and 100nm.

2. The polyurea-based absorbing gel for electronic device packaging according to claim 1, characterized in that: The polyetheramine is a polymer with a main chain of a polyether structure and an amino group as a terminal active functional group, and has a molecular weight of 5000 or 2000.

3. The polyurea-based absorbing gel for electronic device packaging according to claim 1, characterized in that: The isocyanate is an aliphatic diisocyanate, specifically any one or more combinations of isophorone diisocyanate, hexamethylene diisocyanate, and dicyclohexylmethane diisocyanate.

4. The polyurea-based absorbing gel for electronic device packaging according to claim 1, characterized in that: The solvent is a polar organic solvent, specifically any one of ethanol, acetone, dimethylformamide, methylacetamide, and dimethyl sulfoxide; the defoaming agent is any one of LF8750 defoaming agent, BYK-024 defoaming agent, and 6250B silicone defoaming agent.

5. The method for preparing the polyurea-based absorbing gel for electronic device packaging according to any one of claims 1 to 4, characterized in that: The specific steps include: S1. Prepolymerization of component A: subjecting the polyetheramine to a high-temperature dehydration treatment to obtain a dehydrated polyetheramine; adding the dehydrated polyetheramine to a container, stirring in a water bath while continuously introducing nitrogen, adding isocyanate and stirring to obtain a prepolymer of component A; Preparation of Component A: Dissolve the nano-absorbing filler in a solvent, ultrasonicate it, and then add the prepolymer of Component A. Then, increase the temperature and speed, and stir for a certain period of time to obtain Component A. S3 gelation process: The component A and polyaspartic acid ester are mixed in a certain amount ratio, followed by adding a defoaming agent and stirring to obtain a mixed product; S4. Preform molding: The mixed product is cast into a preheated fixed-size mold, and then subjected to a degassing treatment. After the reaction is completed, the microwave-absorbing gel is obtained.

6. The method for preparing the polyurea-based microwave absorbing gel according to claim 5, characterized in that: The specific steps of S1 are: placing a polyetheramine in a beaker, performing a high-temperature dehydration treatment in a vacuum drying oven, and slowly cooling to room temperature after the reaction is completed to obtain a dehydrated polyetheramine; adding the dehydrated polyetheramine to a three-necked flask, stirring in a 25° C. water bath while continuously introducing nitrogen, then adding isocyanate in a certain amount and ratio, and continuously stirring until the reaction is complete to obtain a prepolymer of component A; The mass percentage of the polyetheramine is 33%-35%, the mass percentage of the isocyanate is 14%-16%, and the total mass percentage of the polyetheramine and isocyanate accounts for 49% of the mass percentage of the absorbing gel; The process parameters in this step are as follows: the temperature of the vacuum drying oven is set to 120°C, the vacuum degree is ≤-90kPa, and the dehydration time is 1h-2h; the water bath stirring temperature is 25°C, and the nitrogen flow rate is 20mL / min; the stirring speed when adding isocyanate is 30r / min-50r / min, and the stirring time is 30min~1h.

7. The method for preparing the polyurea-based microwave absorbing gel according to claim 5, characterized in that: The specific steps of S2 are: A certain amount of nano-absorbing filler is dissolved in an appropriate amount of solvent, and after ultrasonic treatment, it is added to the prepolymer of component A obtained in S1. Then, the temperature and the rotation speed are increased, and after stirring for a certain period of time, a semi-fluid paste of component A is obtained; The mass percentage of the nanometer absorbing filler is 0.3%-0.5%, and the mass percentage of the solvent is 16.9%-17.1%, and the total accounts for 17.4% of the mass percentage of the absorbing gel; The process parameters in this step are: ultrasonic frequency 120 kHz, ultrasonic time 30 min, stirring temperature 85° C., stirring speed 120 r / min-150 r / min, and stirring time 3 h.

8. The method for preparing the polyurea-based microwave absorbing gel according to claim 5, characterized in that: The specific steps of S3 are: Mix component A and polyaspartic acid ester in a certain ratio, then add an appropriate amount of defoamer and stir for a certain period of time until the gelation reaction is completed; The mass percentage of polyaspartic acid ester is 30%-30.2%, and the mass percentage of defoaming agent is 3.4%-3.6%, and the total accounts for 33.6% of the mass percentage of the absorbing gel; The process parameters in this step are: stirring temperature 25°C, stirring speed 30r / min-50r / min, and stirring time 5min-10min.

9. The method for preparing the polyurea-based microwave absorbing gel according to claim 5, characterized in that: The specific steps of S4 are: The mixed product is cast into a preheated fixed-size mold, and then transferred to a vacuum drying oven for defoaming. After the reaction is completed, a polyurea-based absorbing gel is obtained; The process parameters in this step are: mold preheating temperature is 60°C, mold size can be designed according to actual needs, defoaming vacuum degree ≤-90kPa, and defoaming time is 10min-30min.

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