Flame retardant based on mussel-imitating material as well as preparation method and application of flame retardant

Abstract

The invention provides a flame retardant based on a mussel-imitating material and a preparation method and application of the flame retardant, and the preparation method comprises the following steps: tannic acid, formaldehyde and glycine are subjected to a Mannich reaction to obtain the mussel-imitating material; the preparation method comprises the following steps: wrapping APP with a mussel-imitating material to obtain a TA-Gly-APP microcapsule; and complexing the TA-Gly-APP microcapsule with ferric ions to obtain the flame retardant based on the mussel-imitating material. The flame retardant disclosed by the invention has relatively good thermal stability and excellent flame retardant property, and meanwhile, meets the requirements on environmental protection and sustainable development.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of flame retardant technology, in particular to a kind of flame retardant based on imitation mussel material and its preparation method and application. BACKGROUND

[0002] Traditional organic halogen flame retardant generates toxic gas and a large amount of smoke when burning, and inorganic flame retardant has poor compatibility with polymers, which easily leads to the decline of material mechanical properties and flame retardant performance. Cellulose-based materials are widely used, but they are highly flammable and pose a fire hazard. Polymer foam and other materials are more flammable due to their low density and large surface area. Imitation mussel material is widely used in underwater adhesives and wet environment bonding, biomedical field, energy storage, membrane separation and environmental protection technology, but it is not perfect in the field of flame retardant materials.

[0003] Tannic acid is a biological macromolecule with three-dimensional network structure formed by connecting three phenylpropane units through ether bond and carbon-carbon bond, which contains rich aromatic ring structure, aliphatic and aromatic hydroxyl and quinone group and other active groups. It is a natural "adhesive", but the direct application of tannic acid separated from plants will lead to low adhesion strength, poor water resistance of phenol formaldehyde resin synthesized by replacing phenol and easy formaldehyde residue, which limits its high value utilization field.

[0004] Intumescent flame retardant (IFR) is a new type of green and environmentally friendly flame retardant, which has the characteristics of halogen-free, low toxicity and low smoke. At present, ammonium polyphosphate / melamine / pentaerythritol is still the mainstream choice of intumescent flame retardant. However, pentaerythritol has the disadvantages of high water solubility and poor thermal stability; ammonium polyphosphate has the disadvantages of hygroscopicity, poor processing performance and thermal stability, which affects the application of flame retardant in practice. SUMMARY

[0005] The present application provides a kind of flame retardant based on imitation mussel material and its preparation method and application, which is obtained by Mannich reaction of tannic acid, formaldehyde and glycine, and then coated with APP to obtain an intumescent bio-based flame retardant with good thermal stability and excellent flame retardant performance.

[0006] The technical scheme of the present application is as follows: the preparation method of the flame retardant based on imitation mussel material comprises the following steps:

[0007] Tannic acid, formaldehyde and glycine are subjected to Mannich reaction to obtain imitation mussel material (abbreviated as TA-Gly-D); the imitation mussel material is coated on APP (ammonium polyphosphate) to obtain TA-Gly-APP microcapsules; and the TA-Gly-APP microcapsules are complexed with ferric ion to obtain the flame retardant based on imitation mussel material.

[0008] The equation of the Mannich reaction is shown as follows:

[0009]

[0010] Further, the preparation method of the imitation mussel material-based flame retardant comprises the following steps:

[0011] (1) adjust 50ml deionized water to pH 12-13, then add 0.5-1g tannic acid, 0.1-0.15g glycine and 1-2ml formaldehyde, and react in a 50-70℃ water bath for 3-5h, and keep the pH at 12-13 during the reaction, to obtain solution A;

[0012] (2) cool solution A to room temperature, stir at 40-50℃ and adjust its pH to 5-7, to obtain solution B;

[0013] (3) weigh 8-10g APP (ammonium polyphosphate) into 20-60ml deionized water, and ultrasonically disperse to obtain an APP suspension;

[0014] (4) add the APP suspension to solution B, stir for 5-10min, then add 0.15-0.25mmol of ferric chloride hexahydrate, stir for 5-10min, and then adjust the pH to 8-9, to obtain a TA-Gly-APP pre-prepared solution complexed with iron ions;

[0015] (5) centrifuge, wash and dry the pre-prepared solution of step (4) to obtain TA-Gly-APP solid complexed with iron ions, and the TA-Gly-APP solid complexed with iron ions is the imitation mussel material-based flame retardant.

[0016] Further, in step (1), NaOH is used to adjust the pH to 12-13.

[0017] Further, in step (2), hydrochloric acid is used to adjust the pH to 5-7.

[0018] Further, in step (4), NaOH is used to adjust the pH to 8-9.

[0019] Further, in step (5), after centrifugation of the pre-prepared solution of step (4), the supernatant is removed, the sediment is washed with anhydrous ethanol and then centrifuged again, and the sediment after centrifugation is vacuum dried.

[0020] The imitation mussel material-based flame retardant is prepared by using the preparation method.

[0021] The imitation mussel material-based flame retardant is prepared by using the preparation method.

[0022] The imitation mussel material-based flame retardant is prepared by using the preparation method.

[0023] The present application is prepared by the Mannich reaction of tannic acid, formaldehyde and glycine, and then the mussel-like material is coated on ammonium polyphosphate (APP) to obtain TA-Gly-APP microcapsules, and the TA-Gly-APP microcapsules are complexed with ferric ions, so that the expanded bio-based flame retardant is prepared, which has good thermal stability and excellent flame retardant performance, significantly improves the flame retardant performance of the material, improves the mechanical properties of the epoxy resin, and meets the requirements of green environmental protection and sustainable development. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0025] Figure 1 is the heat release rate graph of different samples;

[0026] Figure 2 is the total heat release graph of different samples;

[0027] Figure 3 is the smoke release rate graph of different samples;

[0028] Figure 4 is the total smoke release graph of different samples;

[0029] Figure 5 is the CO release rate of different samples;

[0030] Figure 6 is the CO2 release rate of different samples;

[0031] Figure 7 is the front and side of the carbon layer of the cone calorimeter combustion of different samples, (a) EP pure sample,

[0032] (b) 7% APP / EP, (c) 7% Fe@TA-Gly-APP / EP;

[0033] Figure 8 is the XPS full scan graph of the residual carbon of Fe complexed TA-Gly-APP;

[0034] Figure 9 is the XPS narrow scan peak separation graph of the residual carbon of Fe complexed TA-Gly-APP. DETAILED DESCRIPTION

[0035] With reference to the accompanying drawings on the basis of the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0036] Embodiment 1

[0037] The preparation method of the flame retardant based on the mimicking mussel material comprises the following steps:

[0038] (1) 50 ml of deionized water was measured and placed in a single-necked flask, and the pH was adjusted to 13 with NaOH. 1 g of tannic acid (TA) and 0.131 g of glycine (Gly) were weighed and placed in the single-necked flask, and 1 ml of formaldehyde was added. The flask was placed in a 60°C water bath and stirred for 5 min, and the pH was adjusted to 13 again. The solution was reacted for 4 h, and the pH was maintained at 13 during the reaction. Solution A was obtained.

[0039] (2) After the reaction in step (1) was completed, solution A was cooled to room temperature and poured into a clean beaker. The beaker was placed on a heat collecting constant temperature magnetic stirrer, and the temperature was maintained at 40°C. While stirring, hydrochloric acid was slowly added to adjust the pH to 6. Solution B was obtained.

[0040] (3) 10 g of APP (ammonium polyphosphate) was weighed and placed in 20 mL of deionized water, and ultrasonic dispersion was performed for 15 min to form a suspension to prevent agglomeration. An APP suspension was obtained.

[0041] (4) The APP suspension was added to solution B and stirred for 5 min. Then, 0.052 g (0.192 mmol) of iron trichloride hexahydrate was added, and stirring was performed for 5 min. The molar ratio of tannic acid to iron trichloride hexahydrate was 3:1. Sodium hydroxide solution was added dropwise to adjust the pH to 8. A TA-Gly-APP pre-prepared solution complexed with iron ions was obtained.

[0042] (5) The pre-prepared solution of step (4) was centrifuged at 6000 rpm for 10 min using a high-speed centrifuge. The supernatant was discarded, and the precipitate was washed with anhydrous ethanol and then centrifuged again. The precipitate was placed in a vacuum drying oven and dried at 70°C. Iron ion complexed TA-Gly-APP solid (abbreviated as: Fe@TA-Gly-APP) was obtained.

[0043] Embodiment 2

[0044] The epoxy resin is prepared as follows: Bisphenol A epoxy resin (abbreviation: EP) is placed in a water bath at 70°C for 10 minutes so that it becomes a flow state for easy weighing; about 19 g of bisphenol A epoxy resin is weighed into a plastic cup and vacuumized in a 70°C vacuum drying oven for 10 min to remove bubbles in the epoxy resin;

[0045] About 1.33 g of Fe@TA-Gly-APP (prepared in Example 1) ground to 200 mesh is weighed into the EP and stirred for 15 min to form a uniform mixture, which is transferred to a vacuum drying oven at 70°C, vacuumized for 20 min, and taken out after the bubbles completely escape;

[0046] Finally, the water bath is heated to 70°C, about 1.9 g of molten m-phenylenediamine is added, stirred for 10 min until completely dissolved, transferred to a vacuum drying oven at 70°C, vacuumized for 5 min, and quickly poured into a mold while hot, then transferred to an oven at 40°C for 4.5 h, then raised to 80°C for 3 h, and finally raised to 120°C for 1.5 h, demolded to obtain a 7% Fe@TA-Gly-APP / EP sample.

[0047] Comparative Example 1

[0048] This example is basically the same as Example 2, except that Fe@TA-Gly-APP is not added, to obtain a pure EP sample.

[0049] Comparative Example 2

[0050] This example is basically the same as Example 2, except that Fe@TA-Gly-APP is replaced by APP, to obtain a 7% APP / EP sample.

[0051] Cone calorimeter tests are performed on Example 2 and Comparative Examples 1-2, and the sample size for the cone calorimeter is 100 mm x 100 mm x 3 mm, and the test results are shown in Table 1.

[0052] Table 1 Cone calorimeter test results

[0053]

[0054] As can be seen from Table 1, the addition of 7% APP and 7% Fe@TA-Gly-APP slightly reduces the ignition time (TTI) of EP, greatly delays the time to peak heat release rate (t PHRR ), greatly reduces the peak value of heat release rate (P HRR ), and greatly reduces the maximum smoke release rate (PkSPR) of 7% Fe@TA-Gly-APP / EP.

[0055] FromFigure 1 It can be seen that the heat release rate (HRR) of 7% Fe@TA-Gly-APP / EP decreased more significantly and earlier in the mid-to-late stages compared to EP and APP / EP. The overall peak HRR was lower than that of 7% APP / EP, indicating that Fe@TA-Gly-APP has a stronger flame retardant effect and a shorter ignition time, suggesting that Fe... 3 The catalytic effect of + may accelerate the graphitization of the carbon layer, forming a more stable and heat-insulating protective layer.

[0056] Depend on Figure 2 It can be seen that the total heat released (THR) of epoxy resin rises rapidly in the initial stage of combustion, indicating that the epoxy resin undergoes intense pyrolysis and releases a large amount of heat. Furthermore, the THR continues to increase in the later stages, without any self-extinguishing phenomenon. The total heat release is 129.85 MJ / m³. 2 The fire hazard is high. The rate of increase in THR for 7% APP / EP and 7% Fe@TA-Gly-APP / EP is significantly slower, while the total heat release decreases significantly, with 7% APP / EP decreasing to 105.63 MJ / m³. 2 The 7% Fe@TA-Gly-APP / EP ratio decreased to 78.66 MJ / m 2 The total heat release curve of 7%Fe@TA-Gly-APP / EP rises gently and the peak value increases more slowly in the later stage, without a violent exothermic peak, indicating that the heat release is relatively slow during combustion. In the later stage, the THR hardly increases, indicating that its self-extinguishing time is shorter than that of 7%APP / EP and its flame retardant performance is better.

[0057] Depend on Figure 3 and 4 It can be seen that the total smoke release of the flame-retardant epoxy resin samples with the addition of 7% Fe@TA-Gly-APP flame retardant is lower than that of pure EP and APP / EP, and the upward trend is generally slower. This is because the addition of 7% Fe@TA-Gly-APP / EP may promote the formation of a char layer during combustion, preventing further combustion of the epoxy resin. The smoke release rate (SPR) and total smoke release (TSR) of 7% Fe@TA-Gly-APP / EP are much lower than those of pure 7% APP / EP and EP, indicating that Fe acts as a catalyst, accelerating the polymer crosslinking and carbonization process, fixing more char in the char layer. The formation of the char layer not only blocks heat and oxygen but also reduces the release of volatile substances, thereby reducing the peak values ​​of SPR and TSR. Therefore, the modified Fe@TA-Gly-APP flame retardant reduces the smoke release rate and total smoke release.

[0058] Depend on Figure 5 and 6It can be seen that EP rapidly produces a large amount of CO and CO2 in a short time during combustion, and the CO and CO2 release of the sample added with the flame retardant is significantly reduced, wherein the peak value of the CO and CO2 release rate of the 7% Fe@TA-Gly-APP / EP is the lowest, wherein the CO is reduced by 80%, and the CO2 is reduced by 70%, indicating that it releases gas more gently during combustion, and the combustion is more complete, indicating that the catalysis of Fe is significant.

[0059] By Figure 7 It can be seen that the residual carbon after combustion of the epoxy resin without adding the flame retardant is small, and the surface of the residual carbon is loose and porous, which cannot effectively insulate heat. The flame-retardant resin sample after adding the flame retardant forms a highly expanded carbon layer, and under the same addition amount, the carbon layer generated by the Fe@TA-Gly-APP flame-retardant resin sample is higher and the surface is more uniform than that of the APP flame-retardant resin sample. It is indicated that the addition of TA-DOPA makes the epoxy resin generate a uniform and sufficient carbon layer during combustion, so as to achieve the purpose of flame retardation. At the same time, the introduction of Fe 3 After the addition of Fe

[0060] By Figure 9 It can be seen from Table 2 that Fe exists in the CCT residual carbon of Fe@TA-Gly-APP, and the corresponding binding energy of Figure O1s is 531.31 eV, which is in the range of 530.15-531.76 eV, indicating that Fe-O exists in the surface film, that is, C=O at 531.31 eV exists in the form of Fe carbonate, and the existence of Fe-O can catalyze the carbonization efficiency and promote the rapid generation of the carbon layer, which is the condensed phase flame-retardant mode. The atomic concentration of P in the CCT residual carbon of Fe@TA-Gly-APP in Table 2 is only 0.18%, which is much lower than the initial addition amount, which may be due to the fact that PO· or PO2· free radicals formed by the cracking of APP during the combustion of the composite material enter the gas phase reaction zone to capture H· or OH· free radicals necessary for combustion, thereby blocking the combustion chain reaction, resulting in a decrease in the phosphorus content in the residual carbon. It is concluded that Fe@TA-Gly-APP is a flame-retardant mechanism by the catalytic carbonization of Fe-O bond and the synergistic effect of condensed phase and gas phase.

[0061] Table 2 XPS data of residual carbon of TA-Gly-APP complexed with Fe 3+

[0062]

[0063]

[0064] Table 3 Experimental data of mechanical properties of EP composite materials

[0065] ​

[0066] From table 3, it can be seen that the mechanical properties of EP after adding APP have obvious decline, which is due to the poor compatibility of APP and EP. Compared with the APP / EP material, the impact strength, tensile strength and elongation at break of the composite material of Fe@TA-Gly-APP and EP after coating modification are significantly improved, which shows that Fe@TA-Gly enhances the interface bonding force of APP and EP and improves the compatibility of the flame retardant and the polymer, so the mechanical properties of the epoxy resin are increased.

[0067] The above only describes the preferred embodiments of the present application and is not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. Flame retardant based on a mimetope of Mytilus galloprovincialis and a process for its preparation, characterized in that, The method comprises the following steps: Tannic acid, formaldehyde and glycine are subjected to Mannich reaction to obtain a mussel-inspired material; the mussel-inspired material is wrapped in APP to obtain TA-Gly-APP microcapsules; the TA-Gly-APP microcapsules are complexed with ferric ions to obtain a mussel-inspired material-based flame retardant.

2. The process for the preparation of a compound according to claim 1, characterized in that, The preparation method thereof comprises the following steps: (1) 50 ml of deionized water is adjusted to a pH of 12-13, then 0.5-1 g of tannic acid, 0.1-0.15 g of glycine and 1-2 ml of formaldehyde are added, and the reaction is carried out in a 50-70°C water bath for 3-5 h, and the pH is kept at 12-13 during the reaction to obtain solution A; (2) Solution A is cooled to room temperature, stirred at 40-50°C and adjusted to a pH of 5-7 to obtain solution B; (3) 8-10 g of APP is weighed into 20-60 ml of deionized water and ultrasonically dispersed to obtain an APP suspension; (4) The APP suspension is added to solution B, stirred for 5-10 min, then 0.15-0.25 mmol of ferric chloride hexahydrate is added, stirred for 5-10 min, and then the pH is adjusted to 8-9 to obtain a TA-Gly-APP pre-prepared solution complexed with ferric ions; (5) The pre-prepared solution of step (4) is centrifuged, washed and dried to obtain TA-Gly-APP solid complexed with ferric ions, and the TA-Gly-APP solid complexed with ferric ions is a mussel-inspired material-based flame retardant.

3. The process for the preparation of a compound according to claim 2, characterized in that, In step (1), NaOH is used to adjust the pH to 12-13.

4. The process for the preparation of a compound according to claim 2, characterized in that, In step (2), hydrochloric acid is used to adjust the pH to 5-7.

5. The process for the preparation of a compound according to claim 2, characterized in that, In step (4), NaOH is used to adjust the pH to 8-9.

6. The process of claim 2, wherein the process is carried out at a temperature of from 20 to 40°C. In step (5), after the pre-prepared solution of step (4) is centrifuged, the supernatant is removed, the sediment is washed with anhydrous ethanol and then centrifuged again, and the centrifuged sediment is vacuum dried.

7. Flame retardant based on a mimic mussel material, characterized in that The preparation method of any one of claims 1-6 is used.

8. Use of the mussel-inspired material-based flame retardant of claim 7 in the preparation of epoxy resin.

Images