A polyurea material based on cross-linking with boronate and a method for preparing the same

Abstract

The application provides a polyurea material based on boron cross-linking and a preparation method thereof, and belongs to the polyurea material field. The polyurea material is prepared from the following raw materials: an amino-terminated silicon substrate, a diisocyanate, an alcohol amine compound and a compound containing a boron structure; wherein the mass ratio of the amino-terminated silicon substrate, the diisocyanate, the alcohol amine compound and the compound containing the boron structure is (1-100):(0.1-50):(0.01-40):(0.01-40). The polyurea material has simple preparation process, excellent mechanical properties, excellent strain rate response and excellent impact resistance, and can well protect the substrate from being damaged by external high-speed objects. At the same time, the polyurea material is cross-linked based on dynamic bonds and can be recycled, and has extremely strong application prospects in the fields of electronic product protection and human body protection.

Description

Technical Field

[0001] This invention belongs to the field of polyurea materials, specifically relating to a boron-crosslinked polyurea material and its preparation method. Background Technology

[0002] Polyurea is an elastomer formed by the reaction of isocyanates and amines. It possesses hard structural domains randomly dispersed within soft domains, enabling the formation of heterogeneous landscapes with nanoscale microstructures, each domain exhibiting a unique glass transition temperature. During its commercialization in the late 1980s, polyurea gained widespread attention due to its excellent explosion-proof properties and bulletproof protection.

[0003] Under extreme loads such as explosions and impacts, the effects of polyurea materials on the protected substrate are very complex. On the one hand, high impact loads can cause changes in the internal structure of polyurea materials, such as rearrangement of soft and hard segments, crystallization, and hardening. These processes help to disperse energy, thereby protecting the substrate (Liu, Y.; Wang, P.; Jin, F.; Fan, H.; AArch.Civ.Mech.Eng.; 2021; 21(30); 1-15). On the other hand, the strain rate dependence of polyurea materials makes them potential for applications in impact resistance and impact protection. Under certain conditions, this strain rate sensitivity can cause polyurea materials to change from elastic behavior to glassy behavior when deformed at high strain rates, thereby dispersing a large amount of energy (Giller, CB; Gamache, RM; Wahl, KJ; Saab, AP; Roland, CMJCompos.Mater.2016, 50(20), 2853-2859). In simple terms, when subjected to extreme loads such as impacts and explosions, polyurea materials disperse and absorb energy through their own changes, thereby protecting the underlying substrate from damage.

[0004] However, current polyurea materials do not respond well to strain rates, making it difficult to further improve their impact and explosion resistance.

[0005] Therefore, there is an urgent need to obtain polyurea materials with excellent strain rate response and high impact and explosion resistance. Summary of the Invention

[0006] The purpose of this invention is to provide a polyurea material based on boron crosslinking and its preparation method.

[0007] This invention provides a polyurea material containing a boron-bin structure, the polyurea material being prepared from the following raw materials: an amino-terminated silicon matrix, a diisocyanate, an alkanolamine compound, and a compound containing a boron-bin structure;

[0008] The mass ratio of the terminal amino-terminated silicon matrix, diisocyanate, alkanolamine compound, and compound containing a boron structure is (1-100):(0.1-50):(0.01-40):(0.01-40).

[0009] Furthermore,

[0010] The mass ratio of the terminal amino-containing silicon matrix, diisocyanate, alkanolamine compound, and compound containing a boron structure is (5-7):(0.1-1):(0.1-1):(0.01-0.5); preferably (5.5-6.5):(0.67-0.89):(0.18-0.24):(0.06-0.274).

[0011] Furthermore,

[0012] The mass ratio of the terminal amino-containing silicon matrix, diisocyanate, alkanolamine compound, and compound containing a boron structure is 6:0.8:0.22:0.062.

[0013] Furthermore,

[0014] The mass ratio of the terminal amino-containing silicon matrix, diisocyanate, alkanolamine compound, and compound containing a boron structure is 6:0.67:0.18:(0.1-0.274); preferably 6:0.67:0.18:0.14.

[0015] Furthermore,

[0016] The amino-terminated silicon matrix is ​​one or more of aminopropyl-terminated polydimethylsiloxane, amino-terminated polyether, amino-terminated polylactic acid, amino-terminated polytetrahydrofuran, polyetheramine, and polyoxyethylene diamine; preferably, it is aminopropyl-terminated polydimethylsiloxane.

[0017] And / or, the diisocyanate is any one or more of naphthalene diisocyanate, terephthalene diisocyanate, toluene diisocyanate, isophorone diisocyanate, trimethylhexane diisocyanate, 1,6-hexane diisocyanate, 4,4-diphenylmethane diisocyanate, and dicyclohexylmethane diisocyanate.

[0018] And / or, the compound containing the diboron structure is any one or more of 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.

[0019] Furthermore,

[0020] The alkanolamines are alkanolamines that simultaneously contain one or more hydroxyl groups and a single primary amine.

[0021] Furthermore,

[0022] The structure of the alkanolamine compound is as follows:

[0023] (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) One or more of the following.

[0024] The present invention also provides a method for preparing the above-mentioned polyurea material, the method comprising the following steps:

[0025] 1) The reaction of an amino-terminated silicon matrix with a diisocyanate dissolved in an organic solvent,

[0026] 2) React with an alcohol amine compound dissolved in an organic solvent;

[0027] 3) Add a compound containing a boron-containing structure that is soluble in an organic solvent to crosslink the compound, and then dry to remove the solvent to obtain the final product;

[0028] The reaction in step 1) is carried out under the protection of an inert gas for 8-24 hours; the reaction in step 2) is carried out for 8-24 hours; the reaction in step 3) is carried out for 2-8 hours; and the reaction temperature is 40-90℃.

[0029] In step 1), the mass-to-volume ratio of the terminal amino-terminated silicon matrix to the organic solvent is (1-10) g.

[0030] (1-100)ml;

[0031] In step 2), the mass-to-volume ratio of the alkanolamine compound to the organic solvent is (0.1-10) g:(1-10) ml.

[0032] The mass-to-volume ratio of the compound containing the boron structure to the organic solvent in step 3) is (0.01-10):(1-10) ml;

[0033] Preferably, the reaction time for step 1) is 12 hours; the reaction time for step 2) is 12 hours; the reaction time for step 3) is 4 hours; and the reaction temperature is 70°C.

[0034] In step 1), the mass-to-volume ratio of the terminal amino-terminated silicon matrix to the organic solvent is 6:10 ml.

[0035] In step 2), the mass-to-volume ratio of the alkanolamine compound to the organic solvent is (0.18-0.24) g: 2 ml.

[0036] The mass-to-volume ratio of the compound containing the boron structure to the organic solvent in step 2) is (0.06-0.274):2 ml.

[0037] Furthermore,

[0038] The organic solvent is any one or more of tetrahydrofuran, acetone, dichloromethane, dimethylformamide, dimethylacetamide, chloroform, toluene, and ethyl acetate.

[0039] The present invention also provides the use of the polyurea material in the preparation of protective equipment for electronic products or personal protective equipment.

[0040] The term "boron-bonded" refers to a structure formed by two boron atoms directly connected by a chemical bond or by a rigid unit; the rigid unit contains at least one of the following structures: double bond, triple bond, aromatic ring, or aromatic fused ring.

[0041] Experimental results show that this invention provides a boron-crosslinked polyurea material and its preparation method. The synthesis of this boron-crosslinked polyurea material is simple. First, a silicon-based polyurea with one or more alcohol-terminated ends is prepared, and then crosslinked with boron-containing boric acid, resulting in a structure containing one or more boron-boron bonds or boron-aromatic ring-boron bonds, with the boron structure accounting for 0.1%-20% of the polyurea material's mass fraction. The boron-crosslinked polyurea material prepared by this invention exhibits excellent mechanical properties, excellent strain rate responsiveness, and excellent impact resistance, effectively protecting the matrix from damage by high-speed external objects. Furthermore, this polyurea material is based on dynamic bond crosslinking, allowing for recycling. It has extremely broad application prospects in the fields of electronic product protection and personal protective equipment, including screen protectors, mobile phone cases, sports protective gear, and bulletproof vests.

[0042] 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.

[0043] 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

[0044] Figure 1 This is a diagram illustrating the reaction process of boron-crosslinked polyurethane.

[0045] Figure 2 Infrared spectra of Example 1 and Comparative Example 1;

[0046] 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.

[0047] Figure 4 The graph shows the energy storage modulus as a function of frequency for Example 1 and Comparative Example 1.

[0048] Figure 5 The results show the comparison of polyurea modulus between Examples 1-6 and Comparative Examples 1-3;

[0049] Figure 6 The uniaxial stretch curves are for Examples 1-3 and Comparative Examples 1-3;

[0050] Figure 7 The uniaxial stretching curves are for Examples 1, 4, 5, and 6.

[0051] Figure 8 The results show the comparison of fracture stress between Examples 1-3 and Comparative Examples 1-3;

[0052] Figure 9 This is a graph showing the tensile curves of Example 1 at different tensile rates;

[0053] Figure 10 This is a comparison chart of Young's modulus at different tensile rates for Example 1;

[0054] Figure 11 A schematic diagram of the apparatus for a low-speed ball drop test;

[0055] Figure 12 The graph shows a comparison of peak force values ​​in the ball drop test for Examples 1-6 and Comparative Examples 1-3. The smaller the peak force value, the better the impact resistance. Detailed Implementation

[0056] The raw materials and equipment used in this invention are all known products, obtained by purchasing commercially available products.

[0057] Examples 1-6: Preparation of the boron-crosslinked polyurea material of the present invention

[0058] Table 1 Usage of each raw material

[0059]

[0060] Using the raw material ratios of the embodiments in Table 1, the boron-crosslinked polyurea material of the present invention was prepared according to the following steps.

[0061] First, aminopropyl-terminated polydimethylsiloxane (molecular weight 3000 g / mol) was added to a three-necked flask, sealed, and evacuated for 2 hours to remove moisture. Then, isophorone diisocyanate (IPDI) 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 continued under an argon atmosphere for 12 hours. After the reaction was complete, ethanolamine was added to 2 ml of tetrahydrofuran, mixed thoroughly, and then added to the three-necked flask system. The reaction was then carried out at room temperature for 12 hours. After the reaction was complete, tetrahydroxydiborane was dissolved in 2 ml of tetrahydrofuran to form a homogeneous solution, which was then added to the three-necked flask reaction system. After the addition was complete, the reaction system was heated to 70°C and reacted for 4 hours. After the reaction was complete, the reaction solution was completely dried in a vacuum oven at 50°C and 70 kPa to remove the solvent, yielding the polyurea material based on boron crosslinking of this invention.

[0062] Each group of polyurea materials was molded to obtain an impact-resistant film of 5mm*5mm*1mm. The reaction equation for the preparation process in Example 1 is shown in Example 1. Figure 1 .

[0063] Comparative Examples 1-3: Preparation of polyurea materials without boron crosslinking

[0064] Using the raw material ratios of the comparative examples in Table 1, prepare polyurea materials according to the following steps: Comparative Examples 1-3.

[0065] First, aminopropyl-terminated polydimethylsiloxane was added to a three-necked flask, sealed, and evacuated for 2 hours to remove moisture. Then, isophorone diisocyanate (IPDI) 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 continued for 12 hours under an argon atmosphere. After the reaction was complete, ethanolamine was added to 2 ml of tetrahydrofuran, mixed thoroughly, and then added to the three-necked flask system. The reaction was then carried out at room temperature for 12 hours. After the reaction was completed, the reaction solution was completely dried in a vacuum oven at 50°C and 70 kPa to remove the solvent, yielding a boron-free crosslinked polyurea material.

[0066] The polyurea material was molded to obtain an impact-resistant film of 5mm*5mm*1mm, which serves as comparative examples 1-3.

[0067] The following experimental examples demonstrate the beneficial effects of the boron-crosslinked polyurea material prepared according to the present invention.

[0068] Experimental Example 1: Structural characterization of the polyurea based on boron crosslinking according to the present invention.

[0069] I. Experimental Methods

[0070] The structural characteristics of the materials in Example 1 and Comparative Example 1 were tested using infrared characterization. The number-average molecular weight and weight-average molecular weight of each sample were determined using gel permeation chromatography (GPC).

[0071] II. Experimental Results

[0072] The infrared characterization results of Example 1 and Comparative Example 1 are as follows: Figure 2 As shown in Table 2, the GPC tests for each sample are as follows.

[0073] Table 2 GPC test results for each sample

[0074]

[0075]

[0076] from Figure 2 It can be seen that the materials in both Example 1 and Comparative Example 1 contain 1700 cm⁻¹ -1 The characteristic peak of C=O indicates that the materials in Example 1 and Comparative Example 1 are both polyurea materials.

[0077] The material in Example 1 contained 1198 cm. -1 The presence of the BB characteristic peak indicates that Example 1 successfully synthesized a polyurea material containing boron crosslinking.

[0078] Meanwhile, the GPC results in Table 2 show that the molecular weight of the material decreases with the increase of IPDI content during synthesis. When the molar ratio of IPDI to terminal amino silicone oil is 2:1, i.e., in Example 3 and Comparative Example 3, the relative molecular mass of the material is approximately 4900 g / mol, close to the relative molecular mass of the terminal amino silicone oil, indicating minimal chain extension. However, the molecular weights of Examples 1 and 2, as well as Comparative Examples 1 and 2, are much higher than the molecular weight of the terminal amino silicone oil, indicating that a chain extension reaction occurred.

[0079] Experimental Example 2: Investigation of the Rheological Properties of the Boron Crosslinked Polyurea Material Based on the Invention

[0080] Rheological tests were used to compare the shear thickening properties of Example 1 and Comparative Example 1, and the results are as follows: Figure 3 and Figure 4 . Figure 3 This indicates that within the test range of 0.01-100Hz, the storage modulus of Example 1 and Comparative Example 1 are both greater than the loss modulus, demonstrating that the material exhibits elastic properties and good stability throughout the entire test frequency range.

[0081] The storage modulus of both Example 1 and Comparative Example 1 increased with increasing test frequency, exhibiting shear thickening characteristics. Figure 4 From 0.01 Hz to 100 Hz, the storage modulus of Example 1 increased from 53783 Pa to 231913 Pa, an increase of 4.3 times. However, for Comparative Example 1, its storage modulus increased from 23026 Pa to 69519 Pa, an increase of only 3.0 times. Therefore, Example 1 has more obvious shear thickening characteristics than Comparative Example 1, that is, the polyurea based on boron crosslinking has better rate response properties.

[0082] In addition, comparing the moduli of Examples 1-3 and Comparative Examples 1-3, the boron-crosslinked polyurea material has a higher modulus; in conjunction with Table 1 and Figure 5 It can be seen that, with a fixed amount of tetrahydroxydiborane added, the modulus of the polyurea material decreases with increasing amounts of isophorone diisocyanate and ethanolamine. However, when the amounts of isophorone diisocyanate are 0.67 g and ethanolamine are 0.18 g, the modulus of the polyurea material increases with increasing amounts of tetrahydroxydiborane, and the modulus of Example 6 is the highest.

[0083] Experimental Example 3: Comparison of mechanical properties between polyurea materials based on boron crosslinking and those without boron crosslinking

[0084] Mechanical properties were tested using the methods specified in GB / T529-1999. The uniaxial tensile curves for each sample are shown below. Figure 6 and Figure 7 As shown, the results of the fracture stress comparison are as follows: Figure 8 As shown. From Figure 6 and Figure 7 As can be seen, the polyurea materials prepared in all embodiments exhibit obvious elastomer tensile behavior, and there is no obvious yielding process during the stretching process.

[0085] Comparison results of fracture stress Figure 8 As can be seen, the mechanical strength of the polyurea in Examples 1-3 first increases and then decreases, with Example 2 exhibiting the best mechanical strength. Furthermore, the fracture stress of the polyurea material based on boron crosslinking is greater than that of the polyurea material without boron crosslinking, indicating that the introduction of boron crosslinking can significantly increase the mechanical strength of the material.

[0086] Experimental Example 4: Strain rate response characteristics of polyurea materials based on boron crosslinking.

[0087] The tensile curves of Example 1 were tested at different strain rates, and the results are as follows: Figure 9 As shown, with increasing strain rate, the fracture stress of the material increases, but the elongation at break decreases, exhibiting a clear strain rate response characteristic. Increasing the strain rate makes the material more brittle and stronger, exhibiting solid properties; decreasing the strain rate makes the material more fluid-like.

[0088] Comparison of Young's modulus at different strain rates revealed that increasing strain rate led to a rapid increase in Young's modulus, indicating that the material exhibited a harder state. Figure 10 The modulus of the material increases more significantly with increasing frequency, and its excellent strain rate response characteristics lay the foundation for the material's impact resistance.

[0089] Experimental Example 5: Comparison of impact resistance between boron-crosslinked polyurea materials and non-boron-crosslinked polyurea materials.

[0090] Utilize Figure 11 The equipment is used to test the impact resistance of materials by performing a low-speed drop tower impact test on the samples. A standard impactor is released from a specific height, and the impact resistance of the material is evaluated by analyzing the magnitude of the impact force on the force sensor. At the moment of impact, the smaller the reading of the force sensor, the better the impact resistance of the material. The mass of the ball is 10g, and the release height is 50cm.

[0091] Impact resistance results are as follows Figure 12 As shown, a smaller peak force indicates better impact resistance. Furthermore, the peak force of boron-crosslinked polyurea materials is lower than that of non-boron-crosslinked polyurea materials, meaning that boron-crosslinked polyurea materials possess superior impact resistance. The peak force does not decrease with increasing boron content. Figure 12 As can be seen, Example 5 has the smallest peak force and the best impact resistance.

[0092] In summary, this invention provides a boron-crosslinked polyurea material and its preparation method. First, a silicon-based polyurea composed of one or more alcohol-terminated silica substrates is prepared. Then, it is crosslinked with boron-containing boric acid, resulting in a structure containing one or more boron-boron bonds or boron-aromatic ring-boron bonds, with the boron-linked structure accounting for 0.1%-20% of the polyurea material's mass fraction. The boron-crosslinked polyurea material prepared by this invention exhibits excellent mechanical properties, excellent strain rate responsiveness, and excellent impact resistance. Example 2 shows the best mechanical properties, while Example 5 demonstrates the best impact resistance. The excellent impact resistance of the boron-crosslinked polyurea material of this invention effectively protects the matrix from damage by high-speed external objects. Furthermore, the polyurea material of this invention is based on dynamic bond crosslinking, allowing for recycling. It has extremely broad application prospects in the fields of electronic product protection and personal protection, including screen protectors, mobile phone cases, sports protective gear, and bulletproof vests.

Claims

1. A polyurea material containing a bisboron structure, characterized by, The polyurea material is prepared from the following raw materials: an amino-terminated silicon matrix, diisocyanate, alkanolamine compounds, and compounds containing a boron structure; The mass ratio of the terminal amino-terminated silicon matrix, diisocyanate, alkanolamine compound, and compound containing a boron structure is (5.5-6.5):(0.67-0.89):(0.18-0.24):(0.06-0.274). The amino-terminated silicon matrix is ​​aminopropyl-terminated polydimethylsiloxane; The diisocyanate is isophorone diisocyanate; The alcohol amine compound structure is: ; The compound containing the diboron structure is tetrahydroxydiborane.

2. The polyurea material as described in claim 1, characterized in that, The mass ratio of the terminal amino-containing silicon matrix, diisocyanate, alkanolamine compound, and compound containing a boron structure is 6:0.8:0.22:0.

062.

3. The polyurea material of claim 1, wherein, The mass ratio of the terminal amino-terminated silicon matrix, diisocyanate, alkanolamine compound, and compound containing a boron structure is 6:0.67:0.18:(0.1-0.274).

4. The polyurea material as described in claim 3, characterized in that, The mass ratio of the terminal amino-containing silicon matrix, diisocyanate, alkanolamine compound, and compound containing a boron structure is 6:0.67:0.18:0.

14.

5. A method for preparing the polyurea material according to any one of claims 1-4, characterized in that, The method includes the following steps: 1) The reaction of aminopropyl-terminated polydimethylsiloxane with isophorone diisocyanate dissolved in an organic solvent. 2) React with an alcohol amine compound dissolved in an organic solvent; 3) Add tetrahydroxydiborane dissolved in an organic solvent to crosslink, and then dry to remove the organic solvent to obtain the final product.

6. The method as described in claim 5, characterized in that, The organic solvent is any one or more of tetrahydrofuran, acetone, dichloromethane, dimethylformamide, dimethylacetamide, chloroform, toluene, and ethyl acetate.

7. Use of the polyurea material according to any one of claims 1-4 in the preparation of protective equipment for electronic products or personal protective equipment.

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