A high impact polyurea material chain-extended by a boron-containing structure and a method of making the same

Abstract

The application provides a high-impact polyurea material extended by a boron-containing structure and a preparation method thereof, and belongs to the polyurea material field. The raw materials of the polyurea material include: an amino-terminated polymer, a diisocyanate and a boron-containing compound containing two or more hydroxyl groups; the molar ratio of the amino-terminated polymer, the diisocyanate and the boron-containing compound containing two or more hydroxyl groups is (0.1-2):(0.1-4):(0.1-2). The polyurea material has simple synthesis process, excellent storage modulus, energy dissipation efficiency, strain rate response characteristics and impact resistance. On the one hand, the excellent storage modulus, energy dissipation efficiency and excellent impact resistance of the polyurea material can well protect the substrate from being damaged by the outside world; on the other hand, the polyurea material is crosslinked based on dynamic bonds and can be recycled. The polyurea material has a very wide application prospect in the fields of electronic product protection and human body protection, such as screen protection film, mobile phone protective shell, sports protective equipment, bulletproof clothing and the like.

Description

Technical Field

[0001] This invention belongs to the field of polyurea materials, specifically relating to a high-impact polyurea material with boron-containing chain extension and its preparation method. Background Technology

[0002] Protective materials are crucial in personal and industrial production, as well as in flexible electronics. Typically, protective materials possess impact and puncture resistance. Impact-resistant materials include soft materials (such as foams and gels) and hard materials (such as metals, ceramics, and composites), and their impact resistance derives from their energy absorption or high modulus.

[0003] Polyurea materials have attracted widespread attention in the fields of protection, bulletproofing, and explosion protection due to their high strength and excellent strain rate response (Sun Y, Wang X, Ji C, et al. Defence Technology; 2021; 17(4); 1496-1513). Their properties are influenced by their structure; by designing supramolecular polymer networks, polyurea materials with excellent mechanical properties and various functions can be manufactured. Different compositions can lead to significant changes in the performance of polyurea materials. Currently, the energy storage modulus, energy dissipation efficiency, strain rate response characteristics, and impact resistance of polyurea materials are not yet optimal and require further improvement.

[0004] Therefore, there is an urgent need to obtain polyurea materials with excellent energy storage modulus, energy dissipation efficiency, strain rate response characteristics and impact resistance. Summary of the Invention

[0005] The purpose of this invention is to provide a high-impact polyurea material with boron-containing chain extension and its preparation method.

[0006] This invention provides a polyurea material, wherein the raw materials of the polyurea material include: an amino-terminated polymer, a diisocyanate, and a boron-containing compound containing two or more hydroxyl groups;

[0007] The molar ratio of the terminal amino polymer, diisocyanate, and boron-containing compound containing two or more hydroxyl groups is (0.1-2):(0.1-4):(0.1-2).

[0008] Furthermore,

[0009] The molar ratio of the terminal amino polymer, diisocyanate, and boron-containing compound containing two or more hydroxyl groups is 1:2:1.

[0010] Furthermore,

[0011] The amino-terminated polymer is any one or more of aminopropyl-terminated polydimethylsiloxane, amino-terminated polyether, amino-terminated polylactic acid, amino-terminated polytetrahydrofuran, polyetheramine, and polyoxyethylenediamine; preferably, the amino-terminated polymer is aminopropyl-terminated polydimethylsiloxane.

[0012] Furthermore,

[0013] The boron-containing compound containing two or more hydroxyl groups is a compound containing two or more hydroxyl groups and also containing a single boron structure;

[0014] Alternatively, the boron-containing compound containing two or more hydroxyl groups is a compound containing two or more hydroxyl groups and also containing a diboron structure.

[0015] Furthermore,

[0016] The compound containing two or more hydroxyl groups and a single boron structure is a compound containing a boric acid structure.

[0017] Preferably, the following are boric acid, phenylboric acid, ethylboric acid, butylboric acid, heptaylboric acid, methylboric acid, neopentylboric acid, 9-phenanthrolineboric acid, 9-anthraciteboric acid, 1-naphthaleneboric acid, n-pentylboric acid, cyclobutylboric acid, n-propylboric acid, cyclohexylboric acid, phenylethylboric acid, cyclohexylboric acid, 2-anthraciteboric acid, ferroceneboric acid, 1-pyreneboric acid, 3-perylboric acid, and pentafluorophenylboric acid;

[0018] More preferably, the compound containing the boric acid structure is n-butylboronic acid and / or phenylboronic acid.

[0019] Furthermore,

[0020] The compound containing two or more hydroxyl groups and a diboronic structure is any one or more of the following: tetrahydroxydiborane, 1,4-phenyldiboronic acid, 1,3-phenyldiboronic acid, biphenyldiboronic acid, anthracene-9,10-diboronic acid, 2,2'-bipyridine-4,4'-diboronic acid, 2,5-diboronic acid thiophene, pyrene-1,6-dimethyldiboronic acid, diboronic acid, 2,6-dimethoxypyridine-3,5-diboronic acid, bis(catechol) diboronic acid ester, and dibenzothiophene-2,8-diboronic acid;

[0021] Preferably, the compound containing two or more hydroxyl groups and a diboron structure is tetrahydroxydiborane.

[0022] Furthermore,

[0023] The diisocyanate is any one or more of naphthalene diisocyanate, terephthalic diisocyanate, toluene diisocyanate, isophorone diisocyanate, trimethylhexane diisocyanate, 1,6-hexane diisocyanate, 4,4-diphenylmethane diisocyanate, and dicyclohexylmethane diisocyanate.

[0024] Preferably, the diisocyanate is any one or more of isophorone diisocyanate, 1,6-hexane diisocyanate, and 4,4-diphenylmethane diisocyanate.

[0025] Furthermore,

[0026] The raw materials for the polyurea material also include catalysts.

[0027] The present invention also provides a method for preparing the polyurea material, the method comprising the following steps:

[0028] 1) The reaction of amino-terminated polymers with diisocyanates dissolved in organic solvents,

[0029] 2) Add a boron-containing compound with two or more hydroxyl groups dissolved in an organic solvent to carry out a chain extension reaction, dry to remove the solvent, and you will get the product.

[0030] The present invention also provides the use of the polyurea material in the preparation of protective equipment for electronic products and personal protective equipment.

[0031] The aforementioned boron-binding structure refers to a structure in which one or more boron atoms are directly connected by chemical bonds or by rigid units, wherein the rigid units contain at least one of the following structures: double bonds, triple bonds, aromatic rings, or aromatic fused rings.

[0032] The monoboron-structured boric acid refers to a boric acid containing one and only one boron atom. Monoboron-type boric acids contain two or more boron hydroxyl groups. Boron can be linked to an aliphatic chain or an aromatic group.

[0033] The catalyst includes dibutyltin dilaurate, triphenylbismuth, triethylenediamine, and dimethylethanolamine.

[0034] In summary, this invention provides a high-impact polyurea material with boron-containing chain extension and its preparation method. The polyurea material of this invention is prepared from an amino-terminated polymer, a diisocyanate, and a boron-containing compound containing two or more hydroxyl groups. The synthesis process of the polyurea material of this invention is simple, and the obtained polyurea material exhibits excellent rate responsiveness, energy dissipation efficiency, and impact resistance. Among them, the polyurea materials obtained in Examples 3 and 4 have the best storage modulus, while the polyurea material obtained in Example 5 has the best strain rate response characteristics, the highest energy dissipation efficiency, and the best impact resistance. On the one hand, the excellent storage modulus, energy dissipation efficiency, and impact resistance of the polyurea material of this invention can effectively protect the matrix from external damage; on the other hand, this polyurea material is based on dynamic bond crosslinking and can be recycled. This polyurea material has extremely broad application prospects in the fields of electronic product protection and personal protection, such as screen protectors, mobile phone cases, sports protective gear, and bulletproof vests.

[0035] Obviously, based on the above description of the present invention, and according to common technical knowledge and conventional methods in the field, various other modifications, substitutions or alterations can be made without departing from the basic technical concept of the present invention.

[0036] The following detailed embodiments further illustrate the above-described content of the present invention. However, this should not be construed as limiting the scope of the present invention to the following examples. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention. Attached Figure Description

[0037] Figure 1 A diagram illustrating the reaction process of polyurea with boron chain extension;

[0038] Figure 2 Infrared spectra of Example 1 and Comparative Example 1;

[0039] Figure 3 The graph shows the rheological test results of Example 1 and Comparative Example 1, and the curves showing the change of modulus with angular frequency, reflecting the structural stability and non-Newtonian fluid properties of the materials.

[0040] Figure 4 The modulus comparison results are for Examples 1-5;

[0041] Figure 5 This is a comparison chart showing the growth factor of modulus from low frequency to high frequency for Examples 1-5 and Comparative Examples 1-3;

[0042] Figure 6 The tensile loading-unloading curves for Example 1 and Comparative Example 1 are shown.

[0043] Figure 7 This is a comparison chart of the energy dissipation rates of Examples 1-5 and Comparative Examples 1-3;

[0044] Figure 8 This is a graph showing the tensile curves of Example 1 at different tensile rates;

[0045] Figure 9 This is a comparison chart of Young's modulus at different tensile rates for Example 1;

[0046] Figure 10 A schematic diagram of the apparatus for a low-speed ball drop test;

[0047] Figure 11 The graph shows a comparison of the peak force values ​​in the ball drop test for Examples 1-5 and Comparative Examples 1-3. The smaller the peak force value, the better the impact resistance. Detailed Implementation

[0048] The raw materials and equipment used in this invention are all known products, obtained by purchasing commercially available products.

[0049] Example 1: Preparation of the polyurea material of the present invention

[0050] Table 1. Raw material usage of polyurea materials in Examples 1-5 and Comparative Examples 1-3.

[0051]

[0052] First of all Aminopropyl-terminated polydimethylsiloxane was added to a three-necked flask, sealed, and evacuated for 2 hours to remove moisture. Then, 0.89 g (0.004 mol) of isophorone diisocyanate (IPDI) was added to 10 ml of anhydrous tetrahydrofuran and mixed thoroughly. The IPDI tetrahydrofuran solution was then slowly added dropwise to the three-necked flask with continuous stirring using a magnetic stirrer under an argon atmosphere. After the addition was complete, the reaction was carried out at room temperature under an argon atmosphere for 12 hours. After 12 hours of reaction, 0.20 g (0.002 mol) of n-butylboronic acid was dissolved in 5 ml of anhydrous tetrahydrofuran and, after thorough dissolution, 0.0072 g of dibutyltin dilaurate (DBTDL) was added and mixed thoroughly. The mixed solution was then slowly added dropwise to the reaction system in the three-necked flask. After the addition was complete, the system was heated to 60 °C, and the chain extension reaction was carried out at 60 °C under an argon atmosphere for 12 hours. After the reaction was completed, the solvent was completely removed from the reaction system in a vacuum oven at 40°C and 80 kPa for 12 hours to obtain the n-butylboronic acid chain-extended polyurea material, Example 1.

[0053] An impact-resistant film measuring 5 mm * 5 mm * 1 mm was obtained from the polyurea material of Example 1 using a molding method. The reaction equation for the preparation process of Example 1 is shown in the example. Figure 1 .

[0054] Example 2

[0055] First of all Aminopropyl-terminated polydimethylsiloxane was added to a three-necked flask, sealed, and evacuated for 2 hours to remove moisture. Then, 0.67 g (0.004 mol) of 1,6-hexamethylene diisocyanate (HDI) was added to 10 ml of anhydrous tetrahydrofuran and mixed thoroughly. Next, the IPDI tetrahydrofuran solution was slowly added dropwise to the three-necked flask with continuous stirring using a magnetic stirrer under an argon atmosphere. After the addition was complete, the reaction was carried out at room temperature under an argon atmosphere for 12 hours. After 12 hours of reaction, 0.20 g (0.002 mol) of n-butylboronic acid was dissolved in 5 ml of anhydrous tetrahydrofuran and dissolved thoroughly. Then, 0.0072 g of dibutyltin dilaurate (DBTDL) was added and mixed thoroughly. The mixed solution was slowly added dropwise to the reaction system in the three-necked flask. After the addition was complete, the system was heated to 60 °C, and the chain extension reaction was carried out at 60 °C under an argon atmosphere for 12 hours. After the reaction was completed, the solvent was completely removed from the reaction system in a vacuum oven at 40°C and 80 kPa for 12 h to obtain the n-butylboronic acid chain-extended polyurea material Example 2.

[0056] An impact-resistant film of 5mm*5mm*1mm was obtained from the polyurea material of Example 2 by molding.

[0057] Example 3

[0058] First of all Aminopropyl-terminated polydimethylsiloxane was added to a three-necked flask, sealed, and evacuated for 2 hours to remove moisture. Then, 1.01 g (0.004 mol) of 4,4-diphenylmethane diisocyanate (MDI) was added to 10 ml of anhydrous tetrahydrofuran and mixed thoroughly. Next, the tetrahydrofuran solution of IPDI was slowly added dropwise to the three-necked flask, with continuous stirring using a magnetic stirrer, under an argon atmosphere. After the addition was complete, the reaction was carried out at room temperature under an argon atmosphere for 12 hours. After 12 hours of reaction, 0.20 g (0.002 mol) of n-butylboronic acid was dissolved in 5 ml of anhydrous tetrahydrofuran, and after thorough dissolution, 0.0072 g of dibutyltin dilaurate (DBTDL) was added and mixed thoroughly. The mixed solution was slowly added dropwise to the reaction system in the three-necked flask. After the addition was complete, the system was heated to 60 °C, and the chain extension reaction was carried out at 60 °C under an argon atmosphere for 12 hours. After the reaction was completed, the solvent was completely removed from the reaction system in a vacuum oven at 40°C and 80 kPa for 12 hours, yielding the n-butylboronic acid chain-extended polyurea material, Example 3. The polyurea material of Example 3 was then molded to obtain an impact-resistant film of 5 mm * 5 mm * 1 mm.

[0059] Example 4

[0060] First of all Aminopropyl-terminated polydimethylsiloxane was added to a three-necked flask, sealed, and evacuated for 2 hours to remove moisture. Then, 0.89 g (0.004 mol) of isophorone diisocyanate (IPDI) was added to 10 ml of anhydrous tetrahydrofuran and mixed thoroughly. The IPDI tetrahydrofuran solution was then slowly added dropwise to the three-necked flask with continuous stirring using a magnetic stirrer under an argon atmosphere. After the addition was complete, the reaction proceeded at room temperature under an argon atmosphere for 12 hours. After 12 hours of reaction, 0.24 g (0.002 mol) of phenylboronic acid was dissolved in 5 ml of anhydrous tetrahydrofuran and, after thorough dissolution, 0.0072 g of dibutyltin dilaurate (DBTDL) was added and mixed thoroughly. This mixed solution was then slowly added dropwise to the reaction system in the three-necked flask. After the addition was complete, the system was heated to 60 °C, and the chain extension reaction was carried out at 60 °C under an argon atmosphere for 12 hours. After the reaction was completed, the solvent was completely removed from the reaction system in a vacuum oven at 40°C and 80 kPa for 12 hours to obtain the polyurea material with phenylboronic acid chain extension, Example 4.

[0061] An impact-resistant film of 5mm*5mm*1mm was obtained from the polyurea material of Example 4 by molding.

[0062] Example 5

[0063] First of all Aminopropyl-terminated polydimethylsiloxane was added to a three-necked flask, sealed, and evacuated for 2 hours to remove moisture. Then, 0.89 g (0.004 mol) of isophorone diisocyanate (IPDI) was added to 10 ml of anhydrous tetrahydrofuran and mixed thoroughly. The IPDI tetrahydrofuran solution was then slowly added dropwise to the three-necked flask with continuous stirring using a magnetic stirrer under an argon atmosphere. After the addition was complete, the reaction was carried out at room temperature under an argon atmosphere for 12 hours. After 12 hours of reaction, 0.18 g (0.002 mol) of tetrahydroxydiborane was dissolved in 5 ml of anhydrous tetrahydrofuran and dissolved thoroughly. Then, 0.0072 g of dibutyltin dilaurate (DBTDL) was added and mixed thoroughly. The mixed solution was then slowly added dropwise to the reaction system in the three-necked flask. After the addition was complete, the system was heated to 60 °C, and the chain extension reaction was carried out at 60 °C under an argon atmosphere for 12 hours. After the reaction was completed, the solvent was completely removed from the reaction system in a vacuum oven at 40°C and 80 kPa for 12 hours to obtain the tetrahydroxydiborane chain-extended polyurea material, Example 5.

[0064] An impact-resistant film of 5mm*5mm*1mm was obtained from the polyurea material of Example 5 by molding.

[0065] Comparative Example 1

[0066] First of all Aminopropyl-terminated polydimethylsiloxane was added to a three-necked flask, sealed, and evacuated for 2 hours to remove moisture. Then, 0.89 g (0.004 mol) of isophorone diisocyanate (IPDI) was added to 10 ml of anhydrous tetrahydrofuran and mixed thoroughly. The IPDI tetrahydrofuran solution was then slowly added dropwise to the three-necked flask with continuous stirring using a magnetic stirrer under an argon atmosphere. After the addition was complete, the reaction proceeded at room temperature under an argon atmosphere for 12 hours. After 12 hours of reaction, 0.21 g (0.002 mol) of 1,2-pentanediol was dissolved in 5 ml of anhydrous tetrahydrofuran and, after thorough dissolution, 0.0072 g of dibutyltin dilaurate (DBTDL) was added and mixed thoroughly. This mixed solution was then slowly added dropwise to the reaction system in the three-necked flask. After the addition was complete, the system was heated to 60 °C, and the chain extension reaction was carried out at 60 °C under an argon atmosphere for 12 hours. After the reaction was completed, the solvent was completely removed from the reaction system in a vacuum oven at 40℃ and 80kPa for 12 hours to obtain the polyurea material of Comparative Example 1.

[0067] Comparative Example 1 polyurea material was used to obtain an impact-resistant film of 5mm*5mm*1mm by molding.

[0068] Comparative Example 2

[0069] First of all Aminopropyl-terminated polydimethylsiloxane was added to a three-necked flask, sealed, and evacuated for 2 hours to remove moisture. Then, 0.67 g (0.004 mol) of 1,6-hexamethylene diisocyanate (HDI) was added to 10 ml of anhydrous tetrahydrofuran and mixed thoroughly. Next, the IPDI tetrahydrofuran solution was slowly added dropwise to the three-necked flask with continuous stirring using a magnetic stirrer under an argon atmosphere. After the addition was complete, the reaction was carried out at room temperature under an argon atmosphere for 12 hours. After 12 hours of reaction, 0.21 g (0.002 mol) of 1,2-pentanediol was dissolved in 5 ml of anhydrous tetrahydrofuran and, after thorough dissolution, 0.0072 g of dibutyltin dilaurate (DBTDL) was added and mixed thoroughly. The mixed solution was then slowly added dropwise to the reaction system in the three-necked flask. After the addition was complete, the system was heated to 60 °C, and the chain extension reaction was carried out at 60 °C under an argon atmosphere for 12 hours. After the reaction was completed, the solvent was completely removed from the reaction system in a vacuum oven at 40°C and 80 kPa for 12 hours to obtain a polyurea material with extended n-butylboronic acid. The polyurea material was used to obtain an impact-resistant film of 5 mm * 5 mm * 1 mm by molding, as Example 2.

[0070] Comparative Example 3

[0071] First of all Aminopropyl-terminated polydimethylsiloxane was added to a three-necked flask, sealed, and evacuated for 2 hours to remove moisture. Then, 1.01 g (0.004 mol) of 4,4-diphenylmethane diisocyanate (MDI) was added to 10 ml of anhydrous tetrahydrofuran and mixed thoroughly. Next, the tetrahydrofuran solution of IPDI was slowly added dropwise to the three-necked flask with continuous stirring using a magnetic stirrer under an argon atmosphere. After the addition was complete, the reaction was carried out at room temperature under an argon atmosphere for 12 hours. After 12 hours of reaction, 0.21 g (0.002 mol) of 1,2-pentanediol was dissolved in 5 ml of anhydrous tetrahydrofuran and, after thorough dissolution, 0.0072 g of dibutyltin dilaurate (DBTDL) was added and mixed thoroughly. The mixed solution was then slowly added dropwise to the reaction system in the three-necked flask. After the addition was complete, the system was heated to 60 °C, and the chain extension reaction was carried out at 60 °C under an argon atmosphere for 12 hours. After the reaction was completed, the solvent was completely removed from the reaction system in a vacuum oven at 40℃ and 80kPa for 12 hours to obtain Comparative Example 3.

[0072] The polyurea material of Comparative Example 3 was used to obtain an impact-resistant film of 5mm*5mm*1mm by molding.

[0073] The following experimental examples demonstrate the beneficial effects of the boron-based chain-extended polyurea material of the present invention.

[0074] Experimental Example 1: Structural Characterization of Polyurea Based on Boron-Containing Chain Extension in This Invention

[0075] I. Experimental Methods

[0076] The structural characteristics of the materials in Example 1 and Comparative Example 1 were tested using infrared characterization.

[0077] II. Experimental Results

[0078] pass Figure 2 Infrared characterization revealed that the materials in Example 1 and Comparative Example 1 both contained [a substance] at 1700 cm⁻¹. -1 The presence of the C=O characteristic peak indicates that the materials in Example 1 and Comparative Example 1 are both polyurea materials. However, the material in Example 1 contains a 1306 cm⁻¹ peak. -1 The presence of the BOC characteristic peak indicates that Example 1 successfully synthesized a polyurea material containing boron-structured chain extensions.

[0079] Experimental Example 2: Viscoelastic Properties of Polyurea Materials Based on Boron-Containing Chain Extensions in This Invention

[0080] I. Experimental Methods

[0081] The viscoelastic properties of the materials in Example 1 and Comparative Example 1 were tested using the method specified in SH / T 0777-2005.

[0082] II. Experimental Results

[0083] The shear thickening properties of materials, such as Figure 3 and 4 As shown. Figure 3 The results show that the storage modulus of both Example 1 and Comparative Example 1 is greater than the loss modulus within the test frequency range (0.01Hz-100Hz), indicating that the material exhibits elastic properties and good stability throughout the entire test frequency range.

[0084] The storage modulus of the polyurea materials in Example 1 and Comparative Example 1 both increased with increasing test frequency, exhibiting shear thickening characteristics. Moreover, compared to the polyurea material in Comparative Example 1 without boron-containing chain extenders, the shear frequency had a greater impact on the polyurea with boron-containing chain extenders.

[0085] from Figure 3 and Figure 4 As can be seen from the above, the storage modulus of the polyurea material obtained in the embodiments of the present invention is better than that of the polyurea material obtained in Comparative Example 1, and the storage modulus of the polyurea materials obtained in Examples 3 and 4 is the best.

[0086] The results of comparing the increase factor of storage modulus of different materials during rheological testing (storage modulus at 100Hz divided by storage modulus at 0.01Hz) are as follows: Figure 5 As shown, this also reflects the magnitude of the material's strain rate response. It was found that the polyurea materials with boron-containing chain extensions (Examples 1-5) showed a significantly higher increase in storage modulus than the polyurea materials with similar structures but without boron chain extensions (Comparative Examples 1-3), and their strain rate response characteristics were significantly improved. Among them, the polyurea material obtained in Example 5 showed the greatest increase in storage modulus and the best strain rate response characteristics.

[0087] Experimental Example 3: Comparison of energy dissipation between boron-based chain-extended polyurea materials and boron-free chain-extended polyurea materials.

[0088] Energy dissipation was tested using the method specified in GB / T1686-1985 during the material loading-unloading process. The stress-strain curves of loading-unloading for Example 1 and Comparative Example 1 are compared here, and the experimental results are as follows: Figure 6 It was found that the hysteresis loop of the polyurea material with butylboronic acid chain extension (Example 1) was significantly larger than that of the polyurea material with 1,2-pentanediol chain extension (Comparative Example 1), indicating that the boron-containing chain-extended polyurea material can generate more energy dissipation.

[0089] The energy dissipation efficiency (percentage of the area under the load-unload curve to the area under the load curve) of Examples 1-5 and Comparative Examples 1-3 is compared as follows: Figure 7As shown, the energy dissipation efficiency of the boron-containing chain-extended polyurea materials (Examples 1-5) is generally higher than that of the boron-free chain-extended polyurea materials (Comparative Examples 1-3), and the polyurea material obtained in Example 5 has the highest energy dissipation efficiency.

[0090] Experimental Example 4: Strain Rate Response Characteristics of Boron Chain Extender-Based Polyurea Materials

[0091] The mechanical properties were tested using the methods specified in GB / T529-1999. Stress-strain curves of Example 1 were tested at different strain rates, and the results are as follows: Figure 8 As shown.

[0092] from Figure 8 As can be seen, with the increase of strain rate, the fracture stress of the material increases, but the elongation at break decreases. The polyurea material in Example 1 exhibits obvious strain rate response characteristics. The increase of strain rate makes the material more inclined to a brittle and strong state, i.e., solid properties, while the decrease of strain rate makes the material more inclined to fluid properties.

[0093] Example 1: Young's modulus results at different strain rates are as follows Figure 9 As shown, an increase in strain rate leads to a rapid increase in the Young's modulus of the material, resulting in a harder material. The material's excellent strain rate response characteristics form the basis for its impact resistance.

[0094] Experimental Example 5: Comparison of impact resistance between boron-based chain-extended polyurea materials and boron-free chain-extended polyurea materials.

[0095] like Figure 10 The impact resistance of materials was tested by using a low-speed drop tower impact test. A standard impactor was released from a specific height, and the impact resistance of the material was evaluated by analyzing the magnitude of the impact force on the force sensor. The smaller the reading of the force sensor at the moment of impact, the better the impact resistance of the material. The mass of the ball was 10g and the release height was 50cm.

[0096] Impact resistance results are as follows Figure 11 As shown, the experimental results indicate that the peak force values ​​of the boron-containing chain extender polyurea materials (Examples 1-5) are all lower than those of the non-boron chain extender polyurea materials (Comparative Examples 1-3), demonstrating that the introduction of the boron-containing chain extender can significantly increase the impact resistance of polyurea. Among them, the polyurea material obtained in Example 5 exhibits the best impact resistance.

[0097] In summary, this invention provides a high-impact polyurea material with a boron-containing chain extension structure and its preparation method. The polyurea material of this invention is prepared from an amino-terminated polymer, a diisocyanate, and a boron-containing compound containing two or more hydroxyl groups. The synthesis process of the polyurea material of this invention is simple, and the obtained polyurea material exhibits excellent storage modulus, energy dissipation efficiency, strain rate response characteristics, and impact resistance. Among them, the polyurea materials obtained in Examples 3 and 4 have the best storage modulus, while the polyurea material obtained in Example 5 has the best strain rate response characteristics, the highest energy dissipation efficiency, and the best impact resistance. On the one hand, the excellent storage modulus, energy dissipation efficiency, strain rate response characteristics, and impact resistance of the polyurea material of this invention can effectively protect the matrix from external damage; on the other hand, this polyurea material is based on dynamic bond crosslinking and can be recycled. This polyurea material has extremely broad application prospects in the fields of electronic product protection and personal protection, such as screen protectors, mobile phone cases, sports protective gear, and bulletproof vests.

Claims

1. A polyurea material, characterized in that, The raw materials for the polyurea material include: aminopropyl-terminated polydimethylsiloxane, diisocyanate, and boron-containing compounds containing two or more hydroxyl groups; The molar ratio of the aminopropyl-terminated polydimethylsiloxane, diisocyanate, and boron-containing compound containing two or more hydroxyl groups is 1:2:

1. The boron-containing compound containing two or more hydroxyl groups is n-butylboronic acid, phenylboronic acid, or tetrahydroxydiborane; The diisocyanate is isophorone diisocyanate or 4,4'-diphenylmethane diisocyanate.

2. The polyurea material as described in claim 1, characterized in that, The raw materials for the polyurea material also include catalysts.

3. A method for preparing the polyurea material according to claim 1 or 2, characterized in that, The method includes the following steps: 1) The reaction of aminopropyl-terminated polydimethylsiloxane with diisocyanate dissolved in organic solvents, 2) Add a boron-containing compound containing two or more hydroxyl groups dissolved in an organic solvent to carry out a chain extension reaction, dry to remove the solvent, and you will get the product.

4. The use of the polyurea material according to claim 1 or 2 in the preparation of protective equipment for electronic products and personal protective equipment.

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