A method for preparing a flame-retardant epoxy resin containing a recyclable flame retardant and its application.

Abstract

This invention discloses a method for preparing a flame-retardant epoxy resin containing a recyclable flame retardant and its application. The method for preparing the flame retardant includes: preparing a manganese cobalt oxide flame retardant through the co-precipitation of manganese and cobalt ions followed by calcination. This invention synthesizes a manganese cobalt oxide flame retardant via a co-precipitation method and uses it as a filler in epoxy resin, curing it to obtain a green, halogen-free, environmentally friendly flame-retardant epoxy resin. It does not pollute the environment during pyrolysis or combustion and can effectively catalyze the conversion of harmful gases generated during combustion, which is beneficial to environmental protection and sustainable development. It has excellent flame-retardant properties, greatly reducing the release of heat, smoke, and harmful gases during epoxy resin combustion, significantly enhancing its fire safety. Furthermore, it enables efficient recovery of the flame retardant from the epoxy resin, with a recovery rate of up to 90.0%, achieving high-quality resource utilization.

Description

Technical Field

[0001] This invention relates to the field of flame-retardant polymer materials technology, specifically to a method for preparing a flame-retardant epoxy resin containing a recyclable flame retardant and its application. Background Technology

[0002] Epoxy resins play a vital role in electronic devices, structural components, coatings, and many other aspects of daily life due to their low cost, ease of processing, and excellent chemical resistance. However, the unique structure of epoxy resins makes them highly flammable, producing large amounts of smoke and harmful gases during combustion, which greatly endangers human property and safety. Therefore, it is urgent to introduce flame retardants into epoxy resin composites to improve their fire safety performance.

[0003] Previously, due to the high toxicity, carcinogenicity, environmental persistence, and bioaccumulation of halogenated flame retardants such as polybrominated biphenyls (PBBBs) and polybrominated diphenyl ethers (PBDEs), these inexpensive and highly effective halogenated flame retardants have been banned in most countries and regions. Subsequently, phosphorus-based flame retardants were considered one of the effective alternatives to halogenated flame retardants. However, phosphorus compounds pose potential hazards to humans and the environment. Inorganic nano-flame retardants have attracted widespread attention from researchers due to their low or non-toxicity, including carbon nanotubes, graphene, C60, POSS, silicates, Mxene, and metal or non-metal oxides. Compared with organic flame retardants, these nano-inorganic fillers have advantages such as simple synthesis, high yield, and controllable particle size, and are widely used in the flame retardant field.

[0004] Metal oxides, due to their simple synthesis, large specific surface area, and strong chemical inertness, have been widely used in catalysis, adsorption, and separation. Because metals possess excellent catalytic char-forming ability, they have also been extensively studied in the field of flame-retardant composite materials. However, generally, metal oxides must be combined with other organic fillers to achieve better flame-retardant effects, which increases economic costs. Therefore, developing efficient and simple-to-prepare metal oxide flame retardants will be beneficial for improving flame retardancy and economic efficiency. Furthermore, due to the high stability of metal oxides, flame retardants can theoretically be recovered from waste polymer composite materials, which will greatly benefit the high-quality utilization of metal resources. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a method for preparing a flame-retardant epoxy resin containing a recyclable flame retardant and its application.

[0006] To achieve the above-mentioned objectives, in a first aspect, the present invention provides a method for preparing a recyclable manganese cobalt oxide flame retardant, comprising the following steps: dispersing the recyclable manganese cobalt oxide flame retardant in bisphenol A type epoxy resin by mechanical stirring to obtain a mixture, and then reacting the mixture at a certain temperature for a period of time; then adding an aromatic diamine curing agent and stirring until a stable and uniform epoxy resin solution is obtained; finally, evacuating the epoxy resin solution to remove air bubbles, pouring it into a preheated mold, and performing thermosetting, and cooling it to room temperature after curing; finally, a flame-retardant epoxy resin containing the recyclable flame retardant is prepared.

[0007] The preparation method of the recyclable manganese cobalt oxide flame retardant is as follows:

[0008] Manganese sulfate monohydrate and cobalt sulfate heptahydrate were dissolved in an ethanol-water solution to obtain a solution. This solution was then added to an ethanol-water solution containing 12 g of ammonium bicarbonate to obtain a mixture. The resulting mixture was left to stand overnight at room temperature, then centrifuged and washed. The resulting powder was vacuum dried at 80 °C for 10 hours, and then dried in air at 500 °C for 5 min. -1 The recyclable manganese cobalt oxide flame retardant was obtained by calcining at a heating rate of 4 hours.

[0009] The mass ratio of the recyclable manganese cobalt oxide flame retardant to bisphenol A type epoxy resin is 5-15:100.

[0010] The mass ratio of the aromatic diamine curing agent to the bisphenol A type epoxy resin is 18-26:100.

[0011] Furthermore, the reaction temperature of the recyclable manganese cobalt oxide flame retardant and the bisphenol A type epoxy resin is 85-120°C, and the reaction time is 40-60 minutes.

[0012] The above-described preparation method of the present invention yields a flame-retardant epoxy resin containing a recyclable flame retardant.

[0013] The above-described preparation method of the present invention is applied in the preparation of a flame-retardant epoxy resin containing a recyclable flame retardant with a recovery rate of over 90.0%.

[0014] Specifically, the present invention adopts the following technical solution:

[0015] The present invention discloses a method for preparing a recyclable manganese cobalt oxide flame retardant, comprising the following steps: dissolving manganese sulfate monohydrate (6 mmol) and cobalt sulfate heptahydrate (2 mmol) in 200 mL of a solution (ethanol / water = 1 / 10). Adding the above solution to 200 mL of a solution (ethanol / water = 1 / 10) containing 12 g of ammonium bicarbonate. Allowing the resulting mixture to stand overnight at room temperature, followed by centrifugation and washing. The resulting powder is vacuum dried at 80 °C for 10 hours, and then dried in air at 500 °C for 5 min. -1 The product obtained by calcining at a heating rate of 4 hours was named Mn3CoO. x .

[0016] Secondly, the present invention provides the application of the recyclable manganese cobalt oxide flame retardant prepared by the above-mentioned method for preparing a recyclable manganese cobalt oxide flame retardant.

[0017] In one embodiment, it is used to prepare a flame-retardant epoxy resin.

[0018] In one embodiment, the recyclable manganese cobalt oxide flame retardant is dispersed in bisphenol A type epoxy resin by mechanical stirring to obtain a uniform mixture. Then, the mixture is reacted at a certain temperature for a period of time, and an aromatic diamine curing agent is added. The mixture is stirred until an epoxy resin solution is obtained. Finally, the epoxy resin solution is vacuumed to remove air bubbles, then poured into a preheated mold and thermo-cured. After curing, it is cooled to room temperature. Finally, a flame-retardant epoxy resin is prepared.

[0019] In one embodiment, the mass ratio of recyclable manganese cobalt oxide flame retardant to bisphenol A type epoxy resin is 5 to 15:100.

[0020] In one embodiment, the mass ratio of aromatic diamine curing agent to bisphenol A type epoxy resin is 18-26:100.

[0021] In one embodiment, the reaction temperature of the recyclable manganese cobalt oxide flame retardant and the bisphenol A type epoxy resin is 85–120°C, and the reaction time is 40–60 minutes.

[0022] The advantages and beneficial effects of this invention compared to the prior art are as follows:

[0023] (1) The present invention provides a flame-retardant epoxy resin containing a recyclable flame retardant, which has a simple process, is easy to control, and has high efficiency.

[0024] (2) The flame-retardant epoxy resin containing recyclable manganese cobalt oxide flame retardant provided by the present invention can effectively catalyze the formation of a high-quality char layer during the combustion process. The high-quality char layer can effectively isolate the transfer of oxygen and heat during the combustion process.

[0025] (3) The flame-retardant epoxy resin containing recyclable manganese cobalt oxide flame retardant provided by the present invention effectively inhibits the release of heat, smoke and harmful gases during the combustion process of epoxy resin.

[0026] (4) This invention provides a method for preparing a flame-retardant epoxy resin containing a recyclable flame retardant and its application. The method for preparing the flame retardant includes: preparing a manganese cobalt oxide flame retardant by co-precipitation of manganese and cobalt ions followed by calcination. This invention synthesizes a manganese cobalt oxide flame retardant by co-precipitation and uses it as a filler in epoxy resin to prepare a green, halogen-free, environmentally friendly flame-retardant epoxy resin. It does not cause environmental pollution during thermal decomposition or combustion and can effectively catalyze the conversion of harmful gases generated during combustion, which is beneficial to environmental protection and sustainable development. It has excellent flame-retardant properties, greatly reducing the release of heat, smoke, and harmful gases during the combustion of epoxy resin, and significantly enhancing its fire safety. Furthermore, it can achieve efficient recovery of the flame retardant in epoxy resin, with a recovery rate of up to 90%, realizing high-quality utilization of resources. Attached Figure Description

[0027] Figure 1 Image of a sample of recyclable manganese cobalt oxide flame retardant;

[0028] Figure 2 These are sample images of three shapes of flame-retardant epoxy resin containing recyclable flame retardants. Detailed Implementation

[0029] To make the technical problem to be solved, the technical solution, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0030] In a first aspect, the present invention provides a method for preparing a recyclable manganese cobalt oxide flame retardant, the specific steps of which are as follows:

[0031] A solution was obtained by dissolving manganese sulfate monohydrate (6 mmol) and cobalt sulfate heptahydrate (2 mmol) in 200 mL of a solution (prepared with anhydrous ethanol / water at a volume ratio of 1 / 10). This solution was then added to a 200 mL solution containing 12 g of ammonium bicarbonate (prepared with anhydrous ethanol / water at a volume ratio of 1 / 10) to obtain a mixture. The resulting mixture was left to stand at room temperature overnight, followed by centrifugation and washing. The resulting powder was vacuum dried at 80 °C for 10 hours, and then dried in air at 500 °C for 5 min. -1 Calcination at a heating rate of 4 hours yielded a recyclable manganese cobalt oxide flame retardant, which was named Mn3CoO. x .

[0032] Secondly, the present invention provides the application of the recyclable manganese cobalt oxide flame retardant prepared by the above-mentioned method for preparing a recyclable manganese cobalt oxide flame retardant.

[0033] Furthermore, it is used to prepare flame-retardant epoxy resins.

[0034] Furthermore, the obtained recyclable manganese cobalt oxide flame retardant was dispersed in bisphenol A type epoxy resin by mechanical stirring to obtain a uniform mixture. Then, the mixture was reacted at a certain temperature for a period of time, and an aromatic diamine curing agent was added. The mixture was stirred until an epoxy resin solution was obtained. Finally, the epoxy resin solution was vacuumed to remove air bubbles, then poured into a preheated mold and heat-cured. After curing, it was cooled to room temperature. Finally, a flame-retardant epoxy resin was prepared.

[0035] Furthermore, the mass ratio of recyclable manganese cobalt oxide flame retardant to bisphenol A type epoxy resin is 5–15:100, for example, 5:100, 7:100, 9:100, 11:100, 13:100, 15:100, etc. Within this range, the mass ratio of recyclable manganese cobalt oxide flame retardant to bisphenol A type epoxy resin can not only effectively improve the flame retardant performance of epoxy resin composites, but also avoid the reduction of mechanical properties of epoxy resin composites due to excessive flame retardant dosage.

[0036] Furthermore, the mass ratio of aromatic diamine curing agent to bisphenol A type epoxy resin is 18–26:100, for example, 18:100, 20:100, 21:100, 23:100, 24:100, 26:100, etc. Within this range, the mass ratio of aromatic diamine curing agent to bisphenol A type epoxy resin can effectively cure the epoxy resin and avoid problems such as insufficient curing and curing agent residue that would affect the mechanical properties of the epoxy resin.

[0037] Furthermore, the reaction temperature of the recyclable manganese cobalt oxide flame retardant and bisphenol A type epoxy resin is 85-120℃, for example, 80℃, 100℃, 110℃, 120℃, etc.; the reaction time is 40-60 minutes, for example, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, etc.; the optimal reaction conditions are selected according to the ratio of recyclable manganese cobalt oxide flame retardant and bisphenol A type epoxy resin, and the reaction temperature and reaction time are reasonably controlled to obtain a hot epoxy resin solution that is uniformly mixed with the flame retardant.

[0038] According to experiments, the optimal conditions are a mass ratio of recyclable manganese cobalt oxide flame retardant, bisphenol A type epoxy resin, and aromatic diamine curing agent of 5:75:20, which, when uniformly mixed at 100°C for 40 minutes, yields an epoxy resin composite material with the highest flame retardant efficiency and the best mechanical properties.

[0039] This invention has undergone numerous experiments, and some of the experimental results are presented here for reference to further describe the invention in detail. The following is a detailed description in conjunction with specific embodiments.

[0040] Example 1

[0041] Five parts of the recyclable manganese cobalt oxide flame retardant prepared in the first aspect above were dispersed in 75 parts of bisphenol A type epoxy resin by mechanical stirring to obtain a mixture. The mixture was then heated to 100°C and reacted for 40 minutes. Subsequently, 20 parts of diaminodiphenylmethane curing agent were added and stirred until a stable and homogeneous epoxy resin solution was obtained. Finally, the epoxy resin solution was vacuum-sealed to remove air bubbles, then poured into a preheated mold, and cured at 80°C for half an hour, 120°C for 2 hours, and 150°C for 2 hours. After curing, the mixture was allowed to cool naturally to room temperature and demolded to obtain the flame-retardant epoxy resin.

[0042] The prepared flame-retardant epoxy resin samples were subjected to cone calorimetry testing. The cone calorimetry sample dimensions were 100 mm × 100 mm × 3 mm. The results showed that the addition of recyclable manganese cobalt oxide flame retardant effectively reduced the heat release rate of the epoxy resin composite. Compared with epoxy resin without added flame retardant, the peak heat release rate of the epoxy resin composite decreased from 860.7 kW / m³. 2 It dropped to 452.2 kW / m 2 The rate of decrease was 47.5%; the recovery rate of flame retardants was 90.0%.

[0043] Example 2

[0044] Seven parts of the recyclable manganese cobalt oxide flame retardant prepared in the first aspect above were mechanically dispersed in 73 parts of bisphenol A type epoxy resin to obtain a mixture. The mixture was then heated to 100°C and reacted for 40 minutes. Subsequently, 20 parts of diaminodiphenylmethane curing agent were added and stirred until a stable and homogeneous epoxy resin solution was obtained. Finally, the epoxy resin solution was vacuum-sealed to remove air bubbles, then poured into a preheated mold, and cured at 80°C for half an hour, 120°C for 2 hours, and 150°C for 2 hours. After curing, the mixture was allowed to cool naturally to room temperature and demolded to obtain the flame-retardant epoxy resin.

[0045] The prepared flame-retardant epoxy resin samples were subjected to cone calorimetry testing. The cone calorimetry sample dimensions were 100 mm × 100 mm × 3 mm. The results showed that the addition of recyclable manganese cobalt oxide flame retardant effectively reduced the heat release rate of the epoxy resin composite. Compared with epoxy resin without added flame retardant, the peak heat release rate of the epoxy resin composite decreased from 860.7 kW / m³. 2 It decreased to 401.3 kW / m 2 The rate of decrease was 53.4%; the recovery rate of flame retardants was 86.3%.

[0046] Example 3

[0047] Nine parts of the recyclable manganese cobalt oxide flame retardant prepared in the first aspect above were dispersed in 71 parts of bisphenol A type epoxy resin by mechanical stirring to obtain a mixture. The mixture was then heated to 100°C and reacted for 40 minutes. Subsequently, 20 parts of diaminodiphenylmethane curing agent were added and stirred until a stable and homogeneous epoxy resin solution was obtained. Finally, the epoxy resin solution was vacuum-sealed to remove air bubbles, then poured into a preheated mold, and cured at 80°C for half an hour, 120°C for 2 hours, and 150°C for 2 hours. After curing, the mixture was allowed to cool naturally to room temperature and demolded to obtain the flame-retardant epoxy resin.

[0048] The prepared flame-retardant epoxy resin samples were subjected to cone calorimetry testing. The cone calorimetry sample dimensions were 100 mm × 100 mm × 3 mm. The results showed that the addition of recyclable manganese cobalt oxide flame retardant effectively reduced the heat release rate of the epoxy resin composite. Compared with epoxy resin without added flame retardant, the peak heat release rate of the epoxy resin composite decreased from 860.7 kW / m³. 2 It dropped to 374.7 kW / m 2 The rate of decrease was 56.5%; the recovery rate of flame retardants was 88.4%.

[0049] Example 4

[0050] Fifteen parts of the recyclable manganese cobalt oxide flame retardant prepared in the first aspect above were mechanically dispersed in 65 parts of bisphenol A type epoxy resin to obtain a mixture. The mixture was then heated to 100°C and reacted for 40 minutes. Next, 20 parts of diaminodiphenylmethane curing agent were added, and the mixture was stirred until a stable and homogeneous epoxy resin solution was obtained. Finally, the epoxy resin solution was vacuum-sealed to remove air bubbles, then poured into a preheated mold, and cured at 80°C for half an hour, 120°C for 2 hours, and 150°C for 2 hours. After curing, the mixture was allowed to cool naturally to room temperature and demolded to obtain the flame-retardant epoxy resin.

[0051] The prepared flame-retardant epoxy resin samples were subjected to cone calorimetry testing. The cone calorimetry sample dimensions were 100 mm × 100 mm × 3 mm. The results showed that the addition of recyclable manganese cobalt oxide flame retardant effectively reduced the heat release rate of the epoxy resin composite. Compared with epoxy resin without added flame retardant, the peak heat release rate of the epoxy resin composite decreased from 860.7 kW / m³. 2 It decreased to 314.0 kW / m 2 The rate of decrease was 63.5%; the recovery rate of flame retardants was 88.2%.

[0052] Compare with Example 1

[0053] 80 parts of bisphenol A type epoxy resin and 20 parts of diaminodiphenylmethane curing agent were mechanically mixed at 100°C until homogeneous to obtain an epoxy resin solution. Finally, the epoxy resin solution was vacuum-sealed to remove air bubbles, then poured into a preheated mold, and cured at 80°C for half an hour, 120°C for 2 hours, and 150°C for 2 hours. After curing, it was allowed to cool naturally to room temperature and demolded to obtain the reference epoxy resin.

[0054] The prepared epoxy resin samples were subjected to cone calorimetry testing. The cone calorimetry sample dimensions were 100mm × 100mm × 3mm.

[0055] As can be seen from the above embodiments, the flame-retardant properties of the flame-retardant epoxy resins prepared by this invention are significantly improved. The introduction of recyclable manganese cobalt oxide flame retardants into the epoxy resins effectively reduces the heat release rate during the combustion process. This indicates that recyclable manganese cobalt oxide flame retardants can effectively suppress heat generation during epoxy resin combustion. Furthermore, recyclable manganese cobalt oxide flame retardants enable high-efficiency recycling of flame retardants. This suggests that recyclable manganese cobalt oxide flame retardants hold promise as an excellent candidate material for epoxy resin flame retardants.

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a flame-retardant epoxy resin containing a recyclable flame retardant, characterized in that: The process includes the following steps: dispersing a recyclable manganese cobalt oxide flame retardant in bisphenol A type epoxy resin by mechanical stirring to obtain a mixture; then reacting the mixture at a certain temperature for a period of time; adding an aromatic diamine curing agent and stirring until a stable and uniform epoxy resin solution is obtained; finally, evacuating the epoxy resin solution to remove air bubbles, pouring it into a preheated mold, and performing thermosetting; after curing, cooling to room temperature; and finally preparing a flame-retardant epoxy resin containing a recyclable flame retardant. The preparation method of the recyclable manganese cobalt oxide flame retardant is as follows: Manganese sulfate monohydrate and cobalt sulfate heptahydrate were dissolved in an aqueous ethanol solution to obtain a solution, the above solution was added to an aqueous ethanol solution containing 12 g of ammonium bicarbonate to obtain a mixture, the resulting mixture was left overnight at room temperature, then centrifuged and washed, the powder obtained was dried under vacuum at 80 °C for 10 hours, then calcined in air at 500 °C with a temperature ramp of 5 °C min -1 to obtain a recoverable manganese-cobalt oxide flame retardant; The mass ratio of the recyclable manganese cobalt oxide flame retardant to bisphenol A type epoxy resin is 5-15:

100. The mass ratio of the aromatic diamine curing agent to the bisphenol A type epoxy resin is 20:

75.

2. The method for preparing a flame-retardant epoxy resin containing a recyclable flame retardant according to claim 1, characterized in that: The reaction temperature of the recyclable manganese cobalt oxide flame retardant and the bisphenol A type epoxy resin is 85-120 °C, and the reaction time is 40-60 minutes.

3. The preparation method according to claim 1 or 2 yields a flame-retardant epoxy resin containing a recyclable flame retardant.

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