A self-repairing flame-retardant glass polymer material and its preparation method

Abstract

The present invention discloses a self-healing, inherently flame-retardant glass-like polymer material and its preparation method, belonging to the technical field of self-healing polymer materials. The glass-like polymer is prepared from raw materials including bisphenol A diglycidyl ether, 2-hydroxyethyl 2-methyl-2-acrylate phosphate, and diethylene glycol butyl ether. A new glass-like polymer, BPA-HEMAP, is prepared by cross-linking and curing with an epoxy monomer using a reactive flame-retardant phosphorus-containing reagent. The prepared BPA-HEMAP passes the V-0 vertical combustion test with a limiting oxygen index of 28%. After continuous heating at 120°C for 3 hours, it exhibits excellent self-healing properties and good reworkability.

Description

Technical Field

[0001] The present invention belongs to the technical field of self-repairing polymer materials, and in particular relates to a self-repairing intrinsically flame-retardant glass polymer material and a preparation method thereof. Background Art

[0002] In today's world, due to the rapid growth of population, resource shortage has become a major problem. How to improve resource utilization is one of the hot topics in scientific research. Can we prepare materials with excellent performance, reusability and less harm to the environment to cope with the problem of resource shortage?

[0003] After more than ten years of development, glass-like polymer materials (Vitrimer) have achieved results in many directions, including sulfide bond exchange. Some researchers have used mercapto-acrylate-based crosslinking agents (TMADA) to crosslink 2-hydroxyethyl acrylate (HEA) to prepare polymers. These materials show dynamic properties such as re-healing and ductility; some researchers have used disulfide bond aromatic amine curing agents (4-AFD) as curing agents to react and crosslink acrylates to prepare double dynamic covalent bond epoxy resin materials with 4-AFD as the hard segment and dicarboxylic acid as the soft segment; in addition, researchers have composed bisphenol A glycidyl ether, glutaric anhydride and terminal carboxyl polyether. The prepared carbon fiber reinforced glass-like polymer composite material can be degraded by ethylene glycol, realizing the effective recycling of carbon fiber. CN 114479011A dissolves trimethylolpropane triglycidyl ether, a crosslinking agent, and a catalyst in an organic solvent to obtain a mixture; the crosslinking agent includes 2,2′(1,4-phenylene)bis[4-mercapto-1,3,2-dioxolane and 3,3-dithiodipropionic acid; the organic solvent is removed from the mixture and then cured to obtain an epoxy-based glass-like polymer material based on dynamic reversible covalent bonds. CN 116333268 A prepares an epoxy-based glass-like polymer material with excellent overall performance by compounding E51 and EGDGE epoxy resins based on a VU dynamic covalent bond mechanism, along with a curing agent. This glass-like polymer preparation technology improves the fracture toughness and repairability of epoxy-based glass-like polymers, offering practical value in extending their service life and reducing energy consumption in engineering applications. However, conventional glass-like polymers suffer from flame retardancy and other issues, limiting their application. Summary of the Invention

[0004] The present invention proposes a self-repairing, intrinsically flame-retardant glass-like polymer material (Vitrimer) and its preparation method. The present invention uses a reactive flame-retardant phosphorus-containing reagent and epoxy monomer for cross-linking and curing to prepare a self-repairing, intrinsically flame-retardant glass-like polymer, BPA-HEMAP.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] In one aspect of the present invention, a self-repairing inherently flame-retardant glass polymer material (Vitrimer) is proposed. According to an embodiment of the present invention, the raw materials for preparing the Vitrimer include: bisphenol A diglycidyl ether (BPA), 2-methyl-2-acrylate-2-hydroxyethyl phosphate (HEMAP), and diethylene glycol butyl ether (DB). The prepared self-repairing inherently flame-retardant glass polymer material can be represented by BPA-HEMAP. The raw materials for preparing the Vitrimer used in the present invention have the following technical characteristics:

[0007] The present invention introduces a relatively active phosphorus-containing curing agent to crosslink and cure the traditional epoxy monomer bisphenol A diglycidyl ether. The epoxy monomer is bisphenol A diglycidyl ether (BPA), and its structural formula is as follows:

[0008]

[0009] The phosphorus-containing curing agent is 2-hydroxyethyl 2-methyl-2-acrylate phosphate (HEMAP), and its structural formula is as follows:

[0010]

[0011] Furthermore, the phosphorus-containing curing agent HEMAP is mainly obtained by condensation reaction of raw materials 2-hydroxyethyl methacrylate (a) and trimethyl phosphate (b).

[0012]

[0013] Furthermore, the molar ratio of the raw materials (a) and (b) used in preparing HEMAP is (1-3):(1-3).

[0014] The self-repairing flame-retardant glass polymer material (Vitrimer) is synthesized by the ring-opening of the epoxy group of bisphenol A diglycidyl ether (BPA) and the reaction of the phosphorus hydroxyl group of 2-methyl-2-acrylate-2-hydroxyethyl phosphate (HEMAP) to form a phosphate bond. The synthesis route is as follows:

[0015]

[0016] Wherein, R1 is the structural portion of 2-hydroxyethyl 2-methylacrylate phosphate (HEMAP) structure except the phosphorus hydroxyl group, and R2 is the structural portion of bisphenol A diglycidyl ether structure except the epoxy group.

[0017] Furthermore, the molar ratio of bisphenol A diglycidyl ether (BPA) and 2-methyl-2-acrylate-2-hydroxyethyl phosphate (HEMAP) used in the preparation of BPA-HEMAP is (1-2):(1-3), preferably (1-1.5):(1-1.5).

[0018] In addition, the present invention provides a method for preparing a self-repairing intrinsically flame-retardant glass polymer material (Vitrimer). According to an embodiment of the present invention, the method comprises:

[0019] (1) Preheat 32 wt% of bisphenol A diglycidyl ether in a beaker at 70°C for 1 h, then stir 20 wt% of diethylene glycol butyl ether and bisphenol A diglycidyl ether at a speed of 10-60 r / min until a homogeneous solution is obtained;

[0020] (2) adding 48 wt% of 2-methyl-2-acrylic acid-2-hydroxyethyl phosphate at a rate of 20 drops / min using a dropper, stirring at a rate of 10 to 60 r / min until a homogeneous solution is formed, and standing for 5 to 10 minutes until the reaction heat is released to form a homogeneous solution;

[0021] (3) After standing at room temperature for 20 to 30 minutes, wait for the fluidity of the solution to increase, and then place it in a vacuum oven at 105°C.

[0022] Degas under vacuum until the solution becomes uniform and transparent;

[0023] (4) Place the sample in an oven and heat it to 120°C for 6 to 12 hours, then increase the oven temperature to 150°C.

[0024] The target sample BPA-HEMAP was obtained after accelerated curing for 3 h.

[0025] The method for preparing the flame-retardant glass polymer (Vitrimer) of the present invention takes into account the high activity of the curing agent. Once mixed, the two react rapidly, exothermically curing, and the addition of an appropriate amount of organic solvent is necessary to reduce the reaction rate. The organic solvent selected is diethylene glycol butyl ether (DB). To prevent the alcohol and phosphate curing agent from reacting first, the preparation method according to the present invention follows the order of adding the epoxy monomer and the organic solvent first, stirring them evenly before adding the phosphate curing agent, ensuring the preparation of a qualified sample.

[0026] According to the preparation method of the above-mentioned self-healing intrinsically flame-retardant glass-like polymer material (Vitrimer) of the present invention, the prepared glass-like polymer material BPA-HEMAP passes the vertical combustion test V-0 level, has a limiting oxygen index of 28%, has a good self-healing effect after continuous heating at 120°C for 3 hours, and has good reprocessability.

[0027] In summary, the present invention uses phosphorus-containing substances as curing agents to cross-link and cure with epoxy monomers, so that the glass-like polymer has certain flame retardant and smoke suppression properties, and the introduction of flame retardants will not cause damage to the environment. This expands the research direction of Vitrimer and also reduces its original usage restrictions.

[0028] In some embodiments of the present invention, in step (1), the bisphenol A diglycidyl ether is preheated in a beaker at 70° C. for 0.5 to 1.0 h, thereby reducing the initial viscosity of the epoxy monomer bisphenol A diglycidyl ether and making the mixing more uniform.

[0029] In some embodiments of the present invention, in step (1), the stirring speed is 10-60 r / min, and the stirring speed should not be too high to reduce excessive bubbles introduced during the stirring process.

[0030] In some embodiments of the present invention, in step (2), the curing agent 2-hydroxyethyl 2-methylpropenoate phosphate (HEMAP) is added dropwise with a stirring speed of 10-60 r / min.

[0031] In some embodiments of the present invention, the vacuum degassing in step (3) is carried out at a temperature of 90 to 120° C., preferably at 105° C., for 10 to 30 minutes.

[0032] In some embodiments of the present invention, in step (4), the vacuum degree of the vacuum degassing is not higher than 40Pa.

[0033] In some embodiments of the present invention, in step (4), the pre-curing temperature is 120°C for 6 to 12 hours, and the post-curing temperature is 150°C for 2 to 4 hours, preferably 3 hours. In this way, the sample can be cured in stages until the target sample is obtained.

[0034] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0036] Figure 1 IR spectra of BPA, DB, HEMAP, and BPA-HEMAP used to prepare Vitrimer according to an embodiment of the present invention;

[0037] Figure 2This is the BPA-HEMAP vertical combustion test process;

[0038] Figure 3 This is the comparative example BPA-DDM vertical combustion test process;

[0039] Figure 4 This is a scanning electron microscope image of BPA-HEMAP in Example;

[0040] Figure 5 This is a microscopic morphology of BPA-DDM under a scanning electron microscope;

[0041] Figure 6 This is a self-repairing image of BPA-HEMAP at different temperatures magnified 100 times in Example;

[0042] Figure 7 This is a self-healing diagram of the comparative example BPA-DDM at different temperatures, magnified 100 times. DETAILED DESCRIPTION

[0043] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, but should not be construed as limiting the present invention.

[0044] The present invention discloses a self-repairing intrinsically flame-retardant glass polymer material (Vitrimer) and a preparation method thereof, wherein the raw materials for preparing the Vitrimer include: bisphenol A diglycidyl ether (BPA), 2-methyl-2-acrylate-2-hydroxyethyl phosphate (HEMAP), and diethylene glycol butyl ether (DB).

[0045] The inventors discovered that by cross-linking and curing a reactive flame-retardant phosphorus-containing reagent with an epoxy monomer and then adding it to Vitrimer, they created a new glass-like polymer, BPA-HEMAP, that is inherently flame-retardant. The prepared BPA-HEMAP passed the V-0 vertical combustion test, had a limiting oxygen index of 28%, exhibited excellent self-healing properties after continuous heating at 120°C for 3 hours, and exhibited good reworkability. This innovative use of a reactive phosphorus-containing reagent to prepare Vitrimer achieves inherent flame retardancy.

[0046] Furthermore, the mass fraction of diethylene glycol butyl ether (DB) used as a diluent is 15% to 25%, preferably 20%. A reactive flame retardant phosphorus-containing reagent is used for crosslinking and curing with an epoxy monomer, and the molar ratio of the raw materials bisphenol A diglycidyl ether (BPA) and 2-methyl-2-acrylate-2-hydroxyethyl phosphate (HEMAP) is (1-2):(1-3), preferably (1-1.5):(1-1.5).

[0047] The following embodiments of the present invention are described in detail. It should be noted that the following embodiments are illustrative and are intended only to explain the present invention and are not to be construed as limiting the present invention. In addition, unless otherwise expressly stated, all reagents used in the following embodiments are commercially available or can be synthesized according to methods described herein or known methods. Reaction conditions not listed are also readily available to those skilled in the art.

[0048] The raw materials and auxiliary agents used in the examples of the present invention are as follows:

[0049]

[0050] Example

[0051] Preparation of standard Vitrimer samples Prepare the raw materials as shown in Table 1. The specific preparation steps are as follows:

[0052] (1) Preheat 21.72 g of bisphenol A diglycidyl ether in a beaker at 70°C for 1 h, then stir 9.12 g of diethylene glycol butyl ether at 40 r / min until a homogeneous solution is obtained;

[0053] (2) Add 14.45 g of 2-methyl-2-acrylic acid-2-hydroxyethyl phosphate using a dropper at a rate of 20 drops / min, stir at a rate of 40 r / min until a homogeneous solution is formed, and let it stand for 8 minutes until the reaction heat is released to form a homogeneous solution;

[0054] (3) After standing at room temperature for 25 min, wait for the fluidity of the solution to increase, and then vacuum degas in a vacuum oven at 105°C until the solution becomes uniform and transparent;

[0055] (4) The sample was placed in an oven and heated to 120°C for curing for 12 hours. The oven temperature was then increased to 150°C and accelerated curing was performed for 3 hours to obtain the target sample BPA-HEMAP.

[0056] Comparative Example

[0057] The sample formula for preparing conventional epoxy resin is shown in Table 1. The specific preparation steps are as follows:

[0058] (1) First, weigh 8 g of 4,4'-4,4'-diaminodiphenylmethane and place it in a plastic cup and melt it in an oven at 105°C for later use;

[0059] (2) Place a beaker containing 40 g of bisphenol A diglycidyl ether on a magnetic stirrer, heat to 70°C and stir, slowly add the melted 4,4'-diaminodiphenylmethane solution into the beaker and stir until a homogeneous solution is obtained;

[0060] (3) Preheat the standard mold at 120°C, then pour the stirred epoxy resin solution into the mold and vacuum degas at 105°C for 10 minutes;

[0061] (4) Finally, the mold containing the resin sample was placed in a 120°C oven for heat curing for 6 hours, and finally in a 150°C oven for three hours to produce the final sample, designated BAP-DDM. The formulations of the example sample BPA-HEMAP and the comparative example sample BPA-DDM are shown in Table 1.

[0062] Table 1 Formulations of Example Sample BPA-HEMAP and Comparative Example Sample BPA-DDM

[0063]

[0064] The following specific test examples demonstrate the beneficial effects of the present invention. The performance testing and characterization of a self-repairing intrinsically flame-retardant glass polymer material (Vitrimer) of the present invention are as follows:

[0065] (1) Fourier transform infrared spectrometer was used to analyze BPA, HEMAP, DB sample solutions, crushed BPA-HEMAP particles, and carbon layer after cone calorimetry in attenuated total reflectance mode at 500-4500 cm -1 32 scans were collected within the range to obtain the infrared (FTIR) spectrum.

[0066] (2) According to the UL94 standard, the sample plate was sawed into 3mm×13mm×100mm specimens and the combustion test was carried out in a vertical combustion test instrument. When performing vertical combustion, the specimen was clamped, the flame position was adjusted to a 45° tilt, the left side of the specimen was aligned with the left side of the flare, and it was vertically located in the middle of the flare. The process was recorded by a mobile phone camera.

[0067] (3) The residue after burning the sample was stuck on the conductive double-sided tape, blown tightly with a spray bottle, and then gold-sprayed. The morphology of the carbon residue was analyzed under the microstructure using a scanning electron microscope. A micro-focused Raman spectrometer was used to analyze the carbon layer at 500-2000 mm using a 532 nm argon ion laser. -1 Characterize within the range.

[0068] (4) Two samples with smooth surfaces were cut into small pieces, and a mark was scratched on the surface with a blade. Images were collected through an optical microscope connected to a computer, and the self-healing effect of the sample scratches was observed after being heated for a period of time at 70℃, 90℃, 120℃ and 150℃ on a constant temperature workbench.

[0069] The performance test results and conclusions of the self-repairing intrinsically flame-retardant glass polymer material (Vitrimer) of the present invention are as follows:

[0070] like Figure 1 As shown in the infrared spectrum, BPA-HEMAP is mainly formed by the ring-opening epoxy reaction between BPA and HEMAP, and DB mainly provides solvent. For BPA-HEMAP, the peak is at 2961 cm -1 The peak at 2864 cm is the stretching vibration peak of the C-H bond. -1 The peak is the symmetrical stretching vibration peak of the -CH2 bond, located at 1504cm -1 The peak is the C=C bond skeleton vibration peak, located at 1233cm -1 The peak at 1180 cm is the stretching vibration peak of the CO bond. -1 The peak at 999 cm is the stretching vibration of the P=O bond. -1 The peak is the stretching vibration peak of the POC bond, located at 828cm -1 The peaks are the bending vibration peaks of the benzene ring. By analyzing these peaks, it was found that the C=C bond in BPA, the C=C bond in the benzene ring and HEMAP, the P=O bond, and the POC bond all appear in BPA-HEMAP, which fully demonstrates that BPA-HEMAP is successfully synthesized from BPA and HEMAP.

[0071] like Figure 2 As shown, during the first ten seconds of ignition, the BPA-HEMAP sample from the Example formed only a small flame. The flame on the specimen immediately extinguished after the ignition device was removed, leaving a charred layer on the surface of the specimen at the ignition point. Five seconds later, a second ignition was performed, and after another ten seconds, the flame was removed, and the specimen also immediately extinguished. The charred layer formed was larger than that after the first ignition. Almost no visible smoke particles were produced during the entire combustion process. Vertical combustion tests show that traditional epoxy resins are flammable, while BPA-HEMAP achieves V-0 flame retardancy. This demonstrates that the introduction of phosphorus imparts excellent charring ability to this glass-like polymer, achieving V-0 flame retardancy for a material that is not originally flame-retardant.

[0072] like Figure 3 As shown, the comparative sample BPA-DDM will continue to burn after ignition. The flame of the sample will become larger and larger without any trend of reduction until the entire sample is burned out. After the sample is burned out, it is found that almost no carbon layer is formed during the entire combustion process, and a large amount of solid smoke particles will be formed and float in the air with an unpleasant odor.

[0073] like Figure 4As shown in the scanning electron microscope image of the combustion residue of Example BPA-HEMAP, at 200 μm, the carbon layer is partially honeycomb-shaped and partially flaky. While the honeycomb-shaped carbon layer occasionally exhibits depressions, it is densely connected and fluffy with numerous small carbon spheres, some of which even swell. While the flaky carbon layer has some holes, it does not exhibit cracks like the carbon layer of BPA-DDM. Instead, it is tightly cross-linked, and the surface spherical spheres that swell are more numerous than those of traditional glass-like polymers. A comparison of the microscopic morphology and carbonization process of traditional epoxy resins and BPA-HEMAP demonstrates that the introduction of phosphorus into BPA-HEMAP produces a larger carbon layer. The carbon layer provides excellent insulation against oxygen and combustible gases, and its flame retardancy reaches V-0 in flame retardancy tests. Combustion expands, releasing relatively little material, demonstrating that BPA-HEMAP primarily relies on the formation of a carbon layer for condensed-phase flame retardancy.

[0074] like Figure 5 As shown, scanning electron microscopy of the comparative BPA-DDM revealed a very small carbon layer. When the post-combustion carbon residue was magnified to 200μm, some flakes or blocks of carbon were visible. The flakes of carbon were not tightly connected and contained many cracks. Further magnification to 50μm revealed some expanded spheres, but no pores. For the blocky carbon layer, some pores were visible on the surface, and the carbon layer appeared to have shrunk into grooves, indicating that the carbonization itself was not particularly good. Not only did it fail to isolate oxygen and combustible gases, but it also allowed heat to enter the material, causing thermal decomposition, thus repeating a vicious cycle.

[0075] like Figure 6 As shown, the BPA-HEMAP sample, an example, was heated at 70°C, 90°C, 120°C, and 150°C, and the self-healing of scratches was observed. After heating at 150°C for 20 minutes, the self-healing effect was already very significant, with most scratches becoming smaller or even disappearing. Heating the sample at 70°C for three hours showed no change in the scratches, suggesting that the ester bond self-healing activity at 70°C is insufficient, resulting in no self-healing effect. Heating the sample at 120°C for three hours also showed significant self-healing. Heating the sample at 90°C for two hours only showed slight changes. After heating for another hour, some repair was observed, with the scratches becoming much finer than at the initial stage, and even a few scratches disappearing. However, the effect was not as good as at 120°C and 150°C. This is because the lower heating temperature reduces the activity of the ester bond, thus affecting the self-healing effect.

[0076] like Figure 7As shown, a comparative BPA-DDM sample heated continuously at 150°C showed a thinning of the scratch after one hour. However, after two hours of continuous heating, the scratch remained unchanged compared to the one-hour heating, and the material also showed no softening. Traditional BPA-DDM is not supposed to have self-healing properties, but the scratch changes at 150°C may be related to the movement of its molecular bonds at high temperatures. Heating the sample at 120°C for three hours showed no change at all, indicating a complete lack of self-healing properties at this temperature.

[0077] Compared with traditional BPA-DDM, the example sample BPA-HEMAP has a very good self-repairing effect under the action of high temperature environment. Even if it is continuously heated in a lower temperature environment, the sample will also have a self-repairing effect as the heating time increases, which fully proves that the BPA-HEMAP generated by the ester exchange reaction has excellent performance.

[0078] In summary, the present invention provides a self-repairing intrinsically flame-retardant glass-like polymer material (Vitrimer) and a preparation method thereof. The prepared glass-like polymer material BPA-HEMAP passes the V-0 level in the vertical combustion test, has a limiting oxygen index of 28%, has a good self-repairing effect after continuous heating at 120°C for 3 hours, and has good reprocessability.

[0079] In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. In the absence of mutual contradiction, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples. Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and are not to be construed as limiting the present invention. Those skilled in the art may change, modify, replace, and modify the above embodiments within the scope of the present invention.

Claims

1. A self-repairing flame-retardant glass polymer material, characterized in that: The glass-like polymer material is prepared from epoxy monomer, phosphorus-containing curing agent, and diluent in a mass ratio of 21.72g:14.45g:9.12g. The diluent is diethylene glycol butyl ether. The epoxy monomer is bisphenol A diglycidyl ether, and its structural formula is as follows: ； The phosphorus-containing curing agent is 2-methyl-2-acrylic acid-2-hydroxyethyl phosphate, and its structural formula is as follows: The 2-hydroxyethyl 2-methyl-2-acrylic acid ester phosphate is obtained by a condensation reaction. The raw materials of the condensation reaction include 2-hydroxyethyl methacrylate and phosphoric acid. The structural formula of the 2-hydroxyethyl methacrylate is shown in formula (a), and the structural formula of the phosphoric acid is shown in formula (b): The molar ratio of the 2-hydroxyethyl methacrylate to the phosphoric acid is 1:1; The synthesis of the glass-like polymer material is carried out by reacting the epoxy group of bisphenol A diglycidyl ether with the phosphorus hydroxyl group of 2-methyl-2-acrylate-2-hydroxyethyl phosphate to form a phosphate bond.

2. A method for preparing the self-repairing intrinsically flame-retardant glass polymer material according to claim 1, characterized in that: include: (1) Preheat bisphenol A diglycidyl ether, then add diethylene glycol butyl ether to dilute and stir until a homogeneous solution; (2) Add 2-hydroxyethyl 2-methyl-2-acrylate phosphate and stir until a homogeneous solution is obtained; (3) After standing at room temperature for a period of time, vacuum degassing is performed until the solution becomes uniform and transparent; (4) The sample is cross-linked and cured according to the pre-curing and post-curing stages to obtain the glass-like polymer material.

3. The method according to claim 2, characterized in that In step (1), the preheating temperature is 70°C and the time is 0.5~1.0h.

4. The method according to claim 2, characterized in that In steps (1) and (2), the stirring speed is 10-60 r / min.

5. The method according to claim 2, characterized in that In step (3), the temperature of the vacuum degassing is 90-120°C, the time is 10-30 minutes, and the vacuum degree of the vacuum degassing is not higher than 40Pa.

6. The method according to claim 2, characterized in that In step (4), the pre-curing temperature is 120°C for 6 to 12 hours, and the post-curing temperature is 150°C for 2 to 4 hours.

Images