A high-efficiency boron-containing flame retardant for epoxy resin, a preparation method and application thereof

Abstract

The application discloses a preparation method of a reactive boron-containing flame retardant and application thereof. The flame retardant is in a solid state, and the structure is as follows: the high-efficiency boron-containing flame retardant for epoxy resin is a flame retardant containing three flame-retardant elements of phosphorus, nitrogen and boron, and due to the synergistic flame-retardant effect among different elements, better flame-retardant performance can be improved at a lower adding amount. When 1-10% of the application is added into the epoxy resin, the flame-retardant performance can pass the UL94V-0 level, the limiting oxygen index is increased by about 4%, and the tensile performance and impact performance are obviously improved. The synthesized flame retardant has high flame-retardant efficiency, is harmless to the environment, belongs to the environment-friendly flame retardant, can be used to replace halogen flame retardants, and has positive social and safety benefits.

Description

Technical Field

[0001] The present invention relates to the field of flame retardants, and more specifically to a boron-containing high-efficiency flame retardant for epoxy resin, and a preparation method and application thereof. Background Art

[0002] Epoxy resins have attracted considerable attention over the past few decades due to their low cure shrinkage and the excellent adhesion, heat resistance, chemical resistance, mechanical properties, and electrical properties of their cured products. Epoxy resins are widely used in various fields, including electronics, coatings, and composite materials. Their widespread use indicates their broad market potential. However, traditional epoxy resins are highly flammable and produce large amounts of toxic fumes during combustion, which can cause irreparable damage to human life and property in the event of a fire. Therefore, improving the fire safety of epoxy resins has become a pressing issue and has attracted increasing attention.

[0003] Halogens are considered effective flame retardants for epoxy resins. However, over time, halogen-containing polymers produce large amounts of toxic substances during combustion, negatively impacting the environment and ecological health. Therefore, the development of halogen-free flame retardants is imperative. Phosphorus-nitrogen flame retardants have been shown in previous studies to offer the advantages of low smoke and low toxicity, but they still have the disadvantage of requiring a large dosage. Therefore, the search for a new element that can synergize with phosphorus-nitrogen flame retardants could significantly improve their flame retardancy. Summary of the Invention

[0004] Based on the above problems, the purpose of the present invention is to provide a boron-containing high-efficiency flame retardant for epoxy resin, and its preparation method and application. The flame retardant can significantly improve the flame retardancy of epoxy resin when used in epoxy resin.

[0005] In one aspect, the present invention provides a boron-containing high-efficiency flame retardant for epoxy resin, wherein the flame retardant is in a solid state and has the following structure:

[0006]

[0007] In another aspect, the present invention provides a method for preparing a boron-containing high-efficiency flame retardant for epoxy resin, comprising the following steps:

[0008] After mixing 3-amino-1,2-propanediol and an organic solvent, phenylboric acid is added and stirred, and then the boron-containing intermediate is obtained by decompression treatment;

[0009] The boron-containing intermediate, organic solvent and deionized water are uniformly mixed, and ammonium polyphosphate is quickly added and purified to obtain the boron-containing high-efficiency flame retardant.

[0010] Furthermore, the process of the preparation method is shown below:

[0011]

[0012] Further, the reduced pressure treatment is suction filtration.

[0013] Further, the purification includes any one or more of filtration, washing, reduced pressure distillation, vacuum drying.

[0014] Further, the organic solvent is selected from one or more of toluene, xylene, N,N-dimethylformamide or 1,4-dioxane.

[0015] Further, the mass ratio of the 3-amino-1,2-propanediol, the organic solvent and the phenylboronic acid is 1:(10-25).

[0016] (1-6).

[0017] Further, the mass ratio of the 3-amino-1,2-propanediol and the phenylboronic acid is 1:(1-2). In this case, the limiting oxygen index and vertical burning efficiency of the material are better.

[0018] Further, the mass ratio of the boron-containing intermediate, the organic solvent, the deionized water and the ammonium polyphosphate is 1:(15-30):(5-20):(0.5-5).

[0019] Further, the mass ratio of the boron-containing intermediate and the ammonium polyphosphate is 1:(1-4), preferably 1:(1-3), more preferably 1:(2-3). In this case, the limiting oxygen index and vertical burning efficiency of the material are better.

[0020] In another aspect, the present application provides a flame-retardant epoxy resin composite material, which comprises an epoxy resin and the boron-containing high-efficiency flame retardant for epoxy resin as described above.

[0021] Further, the composite material contains 1-10% of the boron-containing high-efficiency flame retardant for epoxy resin.

[0022] Further, the epoxy resin is one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, polyphenol type glycidyl ether epoxy resin, aliphatic glycidyl ether epoxy resin or glycidyl ester type epoxy resin.

[0023] Further, the composite material further contains 10-20% of a curing agent.

[0024] In another aspect, the present application provides a preparation method of a flame-retardant epoxy resin composite material, which comprises the following steps:

[0025] The boron-containing high-efficiency flame retardant is added to the preheated epoxy resin, and heated and stirred until uniform;

[0026] Add curing agent and continue stirring, then place in a vacuum environment for degassing;

[0027] Pour it into the preheated mold while it is still hot and solidify;

[0028] The mixture was naturally cooled to room temperature to obtain the flame retardant epoxy resin composite material.

[0029] Furthermore, the curing agent is selected from 4,4-diaminodiphenylmethane.

[0030] Furthermore, the preheating is performed in a vacuum environment at 100°C.

[0031] Furthermore, the curing conditions are: curing at 100° C., 120° C. and 140° C. in sequence for 1-3 hours.

[0032] The beneficial effects of the present invention are as follows:

[0033] The boron-containing high-efficiency flame retardant for epoxy resin provided by the present invention exhibits a significant flame retardant effect when the epoxy resin matrix burns, significantly improving the flame retardant's efficiency. Furthermore, the flame retardant requires minimal addition, resulting in minimal impact on the mechanical properties of the epoxy matrix. Furthermore, compared to common boron-based flame retardants, this flame retardant can be used not only in epoxy systems but also in other matrices, demonstrating its universal applicability.

[0034] The preparation method of the boron-containing high-efficiency flame retardant for epoxy resin provided by the present invention is simple, the raw materials are easy to obtain, and the harm to the environment during the experiment is relatively small. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0036] Figure 1 The infrared spectrum of the flame retardant prepared in Example 1 is shown. DETAILED DESCRIPTION

[0037] In order to more clearly illustrate the present invention, the present invention is further described below in conjunction with preferred embodiments and accompanying drawings. Similar components in the accompanying drawings are represented by the same reference numerals. It should be understood by those skilled in the art that the following detailed description is illustrative rather than restrictive and should not be used to limit the scope of protection of the present invention.

[0038] Example 1

[0039] A boron-containing high-efficiency flame retardant for epoxy resin, the preparation of which comprises the following steps:

[0040] Step 1: Add 4.55g of 3-amino-1,2-propanediol and 70ml of N,N-dimethylformamide to a 250ml three-necked flask equipped with a magnetic stirrer and a water separator. Heat to 50°C and then add 6.1g of phenylboric acid. React for 8h, cool, and remove excess organic solvent by vacuum distillation to obtain a boron-containing intermediate.

[0041] Step 2: Mix 3.87g of the boron-containing intermediate, 100ml of ethanol, and 40ml of deionized water. After stirring for 30 minutes, quickly add 10g of ammonium polyphosphate and react at 100°C for 6 hours in a three-necked flask equipped with a spherical condenser. After the reaction, filter, wash three times with N,N-dimethylformamide, and dry to obtain a solid boron-containing flame retardant, also known as the boron-containing high-efficiency flame retardant for epoxy resin.

[0042] Example 2

[0043] A boron-containing high-efficiency flame retardant for epoxy resin, the preparation of which comprises the following steps:

[0044] Step 1: Add 4.55g of 3-amino-1,2-propanediol and 70ml of N,N-dimethylformamide to a 250ml three-necked flask equipped with a magnetic stirrer and a water separator. Heat to 50°C and then add 6.1g of phenylboric acid. React for 8h, cool, and remove excess organic solvent by vacuum distillation to obtain a boron-containing intermediate.

[0045] Step 2: Mix 3.87g of the boron-containing intermediate, 100ml of ethanol, and 40ml of deionized water. After stirring for 30 minutes, 5.0g of ammonium polyphosphate was quickly added to a three-necked flask equipped with a spherical condenser. The mixture was reacted at 100°C for 6 hours. After the reaction, the mixture was filtered, washed three times with N,N-dimethylformamide, and dried to obtain a solid boron-containing flame retardant, also known as the high-efficiency boron-containing flame retardant for epoxy resin.

[0046] Example 3

[0047] A boron-containing high-efficiency flame retardant for epoxy resin, the preparation of which comprises the following steps:

[0048] Step 1: Add 4.55g of 3-amino-1,2-propanediol and 70ml of N,N-dimethylformamide to a 250ml three-necked flask equipped with a magnetic stirrer and a water separator. Heat to 50°C and then add 6.1g of phenylboric acid. React for 8h, cool, and remove excess organic solvent by vacuum distillation to obtain a boron-containing intermediate.

[0049] Step 2: Mix 3.87g of the boron-containing intermediate, 100ml of ethanol, and 40ml of deionized water. After stirring for 30 minutes, quickly add 7.0g of ammonium polyphosphate and react at 100°C for 6 hours in a three-necked flask equipped with a spherical condenser. After the reaction, filter, wash three times with N,N-dimethylformamide, and dry to obtain a solid boron-containing flame retardant, also known as the boron-containing high-efficiency flame retardant for epoxy resin.

[0050] Example 4

[0051] A boron-containing high-efficiency flame retardant for epoxy resin, the preparation of which comprises the following steps:

[0052] Step 1: Add 4.55 g of 3-amino-1,2-propanediol and 70 ml of N,N-dimethylformamide to a 250 ml three-necked flask equipped with a mechanical stirrer and a water separator. Heat to 50°C and then add 6.1 g of phenylboric acid. React for 8 hours, cool, and remove excess organic solvent by vacuum distillation to obtain a boron-containing intermediate.

[0053] Step 2: Mechanically mix the boron-containing intermediate obtained in step 1 and ammonium polyphosphate in a mass ratio of 1:4 to obtain a mixed boron-containing flame retardant.

[0054] Application Example 1

[0055] The boron-containing flame retardant in Example 1 was added to 30 g of bisphenol A epoxy resin in a beaker and stirred until uniform. Then, 5.6 g of 4,4-diaminodiphenylmethane was added and the mixture was placed in a vacuum environment at 80°C for degassing for 10 minutes. The mixture was poured into a mold preheated to 110°C while hot, and then cured at 120°C and 140°C for 2 hours, and then naturally cooled to room temperature to obtain a flame-retardant composite material.

[0056] Application Example 2

[0057] Take 1 g of the boron-containing flame retardant in Example 2 and add it to 30 g of bisphenol A epoxy resin in a beaker, stir until uniform, then add 5.6 g of 4,4-diaminodiphenylmethane, place it in a vacuum environment at 80°C for degassing for 10 minutes, pour it into a mold preheated to 110°C while hot, and then cure it at 120°C and 140°C for 2 hours, then naturally cool to room temperature to obtain a flame retardant composite material.

[0058] Application Example 3

[0059] Take 1 g of the boron-containing flame retardant in Example 3 and add it to 30 g of bisphenol A epoxy resin in a beaker, stir until uniform, then add 5.6 g of 4,4-diaminodiphenylmethane, place it in a vacuum environment at 80°C for degassing for 10 minutes, pour it into a mold preheated to 110°C while hot, and then cure it at 120°C and 140°C for 2 hours, then naturally cool to room temperature to obtain a flame retardant composite material.

[0060] Application Example 4

[0061] The only difference from Application Example 1 is that 2 g of the boron-containing flame retardant in Example 1 is added to this Application Example. The rest is the same as Application Example 1 and will not be repeated here.

[0062] Application Example 5

[0063] The only difference from Application Example 1 is that 3 g of the boron-containing flame retardant in Example 1 is added to this Application Example. The rest is the same as Application Example 1 and will not be repeated here.

[0064] Comparative Example 1

[0065] The only difference from Application Example 1 is that the boron-containing flame retardant in Example 1 is not added in this Application Example. The rest is the same as Application Example 1 and will not be repeated here.

[0066] Comparative Example 2

[0067] The only difference from Application Example 5 is that 3 g of the mixed boron-containing flame retardant in Example 5 is added to this Application Example. The rest is the same as Application Example 1 and will not be repeated here.

[0068] Comparative Example 3

[0069] The only difference from Application Example 1 is that the boron-containing flame retardant added to Example 1 in this Application Example is triphenylborane, and the rest is the same as Application Example 1 and will not be repeated here.

[0070] The flame retardant composite materials prepared in Application Examples 1-5 and Comparative Examples 1-2 were subjected to a limiting oxygen index test and a vertical combustion test.

[0071] Table 1 Performance test results of flame retardant composite materials obtained from application examples 1-5 and comparative examples 1-2

[0072] Example Limiting oxygen index (%) Vertical combustion Application Example 1 29.1 V-0 Application Example 2 27.8 V-2 Application Example 3 28.5 V-1 Application Example 4 29.6 V-0 Application Example 5 30.2 V-0 Comparative Example 1 26.1 NR Comparative Example 2 27.7 V-2 Comparative Example 3 25.9 NR

[0073] Figure 1 The infrared spectrum of the flame retardant synthesized in Example 1 is shown in the figure. It can be seen from the figure that after the reaction, the infrared curve of BA-APP is at 3374 cm -1 -NH appears 3+ The stretching vibration peak of OBO is at 2670 cm -1 The benzene ring can also be found at 1630cm -1 A vibration peak also appeared at .

[0074] The mechanical curves of the tensile and impact tests of Application Example 1, Application Example 2, Application Example 3, Application Example 4, Application Example 5, Application Comparative Example 1, Application Comparative Example 2, and Application Comparative Example 3 are shown in Table 2. It can be seen from the table that the impact strength and tensile properties of the high-efficiency boron-containing flame retardant for epoxy resin obtained by the present invention are significantly improved.

[0075] Table 2

[0076]

[0077]

[0078] In summary, the highly efficient boron-containing flame retardant for epoxy resin of the present invention not only greatly improves the flame retardancy of epoxy resin but also improves its toughness. In addition, the synthesis route is simple and the raw materials are easily obtained, making it an environmentally friendly flame retardant.

[0079] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A boron-containing high-efficiency flame retardant for epoxy resin, characterized in that: The flame retardant is in a solid state and contains the following structural fragments: The preparation of the flame retardant comprises the following steps: After mixing 3-amino-1,2-propanediol and an organic solvent, phenylboric acid is added and stirred, and then the boron-containing intermediate is obtained by decompression treatment; The boron-containing intermediate, organic solvent and deionized water are uniformly mixed, and ammonium polyphosphate is quickly added and purified to obtain the boron-containing high-efficiency flame retardant.

2. The boron-containing high-efficiency flame retardant for epoxy resin according to claim 1, characterized in that The organic solvent is selected from one or more of toluene, xylene, N,N-dimethylformamide or 1,4-dioxane.

3. The boron-containing high-efficiency flame retardant for epoxy resin according to claim 1, characterized in that The mass ratio of the 3-amino-1,2-propanediol, the organic solvent and the phenylboric acid is 1:(10-25):(1-6).

4. The boron-containing high-efficiency flame retardant for epoxy resin according to claim 1, characterized in that The mass ratio of the boron-containing intermediate, the organic solvent, deionized water and ammonium polyphosphate is 1: (15-30): (5-20): (0.5-5).

5. A flame retardant epoxy resin composite material, characterized in that: The composite material comprises epoxy resin and the boron-containing high-efficiency flame retardant for epoxy resin according to any one of claims 1 to 4.

6. The flame retardant epoxy resin composite material according to claim 5, characterized in that: The epoxy resin is one of bisphenol A epoxy resin, bisphenol F epoxy resin, polyphenol glycidyl ether epoxy resin, aliphatic glycidyl ether epoxy resin or glycidyl ester epoxy resin.

7. The method for preparing a flame retardant epoxy resin composite material according to any one of claims 5 to 6, wherein: The steps include: Add the boron-containing high-efficiency flame retardant to the preheated epoxy resin, and heat and stir until uniform; Add curing agent and continue stirring, then place in a vacuum environment for degassing; Pour it into the preheated mold while it is still hot and solidify; The mixture was naturally cooled to room temperature to obtain the flame retardant epoxy resin composite material.

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