A DOPO reactive flame retardant, a preparation method and application thereof

Abstract

The application relates to a DOPO reaction type flame retardant as well as a preparation method and application thereof. DOPO and an organic solvent are added into a reactor, stirring is carried out until the DOPO is completely dissolved, an epoxy monomer is continuously added into the reactor, and reaction is continuously carried out at 60-90 DEG C for 10-16 h; the solvent is removed through rotary evaporation, and an epoxy-DOPO intermediate is obtained through drying; the epoxy-DOPO intermediate and the organic solvent are added into a reactor, stirring is carried out until the epoxy-DOPO intermediate is completely dissolved, trimethylol phosphine oxide and potassium hydroxide are continuously added into the reactor, and reaction is continuously carried out at 90-130 DEG C for 10-16 h; the solvent is removed through rotary evaporation, and the DOPO reaction type flame retardant is obtained through drying. The DOPO reaction type flame retardant synthesized by the application has the advantages of simple synthesis method, application in plastic and foam flame retardation, improvement of the thermal stability and mechanical properties of the plastic and foam, obvious reduction of the slagging rate of the foam and obvious improvement of the compression resistance of the foam.

Description

Technical Field

[0001] This invention belongs to the field of flame retardant technology, specifically relating to a class of DOPO reactive flame retardants, their preparation methods, and applications. Background Technology

[0002] With the rapid development of modern science and technology and industry, polymer materials have been widely used in various fields. However, due to the flammability of polymer materials, fires can cause enormous loss of life and property. Typically, flame retardants are added to polymer materials to improve their flame-retardant properties and ensure the safety of people and property. Among many flame retardants, phosphorus-containing flame retardants have advantages such as good flame-retardant effect, good thermal stability, good environmental performance, wide application range, and good economy, and are widely used in plastics, rubber, textiles, coatings, and other materials. However, traditional phosphorus-containing flame retardants, except for trimethylolphosphine oxide, are basically esters or inorganic substances. Over time, flame retardant migration occurs in composite materials, leading to a decrease in the material's flame-retardant performance. Trimethylolphosphine oxide is acidic and contains approximately 10% water, limiting its application; generally, a concentration of around 30% is needed to achieve a significant flame-retardant effect. Another advantage is that large amounts of flame retardants can reduce the mechanical properties of the matrix material, affecting construction. Therefore, there is an urgent need to develop flame retardants with good flame-retardant effect and good compatibility with the matrix.

[0003] To achieve this goal, it is essential to develop reactive flame retardants with good flame-retardant properties. 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and its derivatives possess advantages such as good flame retardancy, halogen-free and non-toxic properties, and environmental friendliness, and are widely added to polymer materials to improve their flame-retardant performance. DOPO has a unique chemical structure; its active pH bond readily reacts with carbon-carbon double bonds, epoxy groups, and carbonyl groups to obtain DOPO derivatives. This invention uses diglycidyl ether as a bridge to connect DOPO and tris(hydroxymethyl)phosphorus oxide, preparing a highly flame-retardant reactive flame retardant. Reactive flame retardants exhibit good flame-retardant effects, require significantly less dosage than DOPO-type additive flame retardants, and due to the chemical reaction, have good compatibility with the host material, are less prone to migration and loss, and offer higher safety. Therefore, there is an urgent need to design and synthesize DOPO-type reactive flame retardants with good flame-retardant effects and a simple synthesis process. Summary of the Invention

[0004] Technical problem to be solved: The present invention aims to provide a DOPO reactive flame retardant that is easy to operate and has good flame retardant effect, as well as its preparation method and application.

[0005] Technical solution: A method for synthesizing a DOPO reactive flame retardant, the preparation steps are as follows: (1) Add DOPO and organic solvent to a reactor, wherein the mass ratio of DOPO to organic solvent is 0.2-0.6:1, stir until DOPO is completely dissolved, continue to add epoxy monomer to the reactor, wherein the molar ratio of epoxy group of epoxy monomer to DOPO is 0.9-1.2:1, continue to react at 60-90℃ for 10-16h, remove the solvent by rotary evaporation, and dry to obtain epoxy-DOPO intermediate; (2) Mix epoxy-DOPO intermediate and organic solvent The agent is added to the reactor, wherein the mass ratio of epoxy-DOPO intermediate to organic solvent is 0.2-0.6:1. The mixture is stirred until the epoxy-DOPO intermediate is completely dissolved. Trimethylolphosphine oxide and potassium hydroxide are then added to the reactor, wherein the molar ratio of epoxy-DOPO intermediate to trimethylolphosphine oxide is 0.9-1.2:1, and the amount of potassium hydroxide is 1-3% of the total weight of epoxy-DOPO intermediate and trimethylolphosphine oxide. The reaction is continued at 90-130℃ for 10-16 hours. The solvent is removed by rotary evaporation, and the mixture is dried to obtain the DOPO reactive flame retardant.

[0006] The organic solvent mentioned in step (1) is at least one of methanol, ethanol, chloroform, and dioxane; the mass ratio of DOPO to the organic solvent is 0.4:1.

[0007] The epoxy monomer mentioned in step (1) is at least one of ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,5-pentanediol diglycidyl ether, and 1,6-hexanediol diglycidyl ether; the molar ratio of epoxy group to DOPO in the epoxy monomer is 1:1.

[0008] The organic solvent mentioned in step (2) is dimethylformamide or dioxane; the mass ratio of epoxy-DOPO intermediate to organic solvent is 0.4:1.

[0009] The molar ratio of the epoxy-DOPO intermediate and trihydroxymethylphosphine oxide in step (2) is 1:1.

[0010] The amount of potassium hydroxide used in step (2) is 2% of the total weight of the epoxy-DOPO intermediate and trimethylolphosphine oxide.

[0011] The DOPO reactive flame retardant was prepared by the above method.

[0012] The above-mentioned DOPO reactive flame retardants are used in the preparation of plastics and foams.

[0013] Beneficial effects: (1) The synthesis method of the DOPO reactive flame retardant synthesized in this invention is simple and can be applied to flame retardancy of plastics and foams. Adding a small amount of the DOPO reactive flame retardant synthesized in this invention can greatly improve the flame retardant effect of plastics and foams. At the same time, it improves the thermal stability and mechanical properties of plastics and foams. The slag shedding rate of foam is significantly reduced and the compression resistance of foam is significantly improved; (2) It is easy to operate, the process is simple and the product quality is stable, making it easy to scale up industrial production. Attached Figure Description

[0014] Figure 1 The synthetic route for DOPO reactive flame retardants is described. Detailed Implementation

[0015] The embodiments described below are merely illustrative of the invention and should not be construed as limiting the scope or content of the invention. The invention will be further described in detail below with reference to the embodiments.

[0016] Example 1

[0017] (1) Add a measured amount of DOPO and anhydrous ethanol (mass ratio of DOPO to anhydrous ethanol is 0.4:1) to the reactor, heat at 60°C until DOPO is completely dissolved, continue to add a measured amount of ethylene glycol diglycidyl ether (molar ratio of ethylene glycol diglycidyl ether epoxy group to DOPO is 1:1) to the bottle, heat to 70°C, react for 12 h, remove anhydrous ethanol by rotary evaporation, and dry to obtain epoxy-DOPO intermediate.

[0018] (2) Add an appropriate amount of epoxy-DOPO intermediate and dimethylformamide to a transparent reactor (the mass ratio of epoxy-DOPO intermediate to organic solvent is 0.4:1), stir at 60°C until the epoxy-DOPO intermediate is completely dissolved, and continue to add an appropriate amount of trimethylolphosphine oxide (the molar ratio of epoxy-DOPO intermediate to trimethylolphosphine oxide is 1:1) and potassium hydroxide (the amount of potassium hydroxide is 2% of the total weight of epoxy-DOPO intermediate and trimethylolphosphine oxide), continue to react at 120°C for 12 hours, remove the solvent by rotary evaporation, and dry to obtain the DOPO reactive flame retardant.

[0019] Example 2

[0020] (1) Add a measured amount of DOPO and anhydrous ethanol (mass ratio of DOPO to anhydrous ethanol is 0.4:1) to a transparent reactor, heat at 60°C until DOPO is completely dissolved, continue to add a measured amount of 1,4-butanediol diglycidyl ether (molar ratio of 1,4-butanediol diglycidyl ether epoxy group to DOPO is 1:1) to the bottle, heat to 70°C, react for 12 h, remove anhydrous ethanol by rotary evaporation, and dry to obtain epoxy-DOPO intermediate.

[0021] (2) Add an appropriate amount of epoxy-DOPO intermediate and dimethylformamide to a transparent reactor (the mass ratio of epoxy-DOPO intermediate to dimethylformamide is 0.4:1), stir at 60°C until the epoxy-DOPO intermediate is completely dissolved, and continue to add an appropriate amount of trimethylolphosphine oxide (the molar ratio of epoxy-DOPO intermediate to trimethylolphosphine oxide is 1:1) and potassium hydroxide (the amount of potassium hydroxide is 2% of the total weight of epoxy-DOPO intermediate and trimethylolphosphine oxide), continue to react at 120°C for 12 hours, remove the solvent by rotary evaporation, and dry to obtain DOPO reactive flame retardant.

[0022] Example 3

[0023] (1) Add a measured amount of DOPO and anhydrous ethanol (mass ratio of DOPO to anhydrous ethanol is 0.4:1) to a transparent reactor, heat at 60°C until DOPO is completely dissolved, continue to add a measured amount of 1,5-pentanediol diglycidyl ether (molar ratio of 1,5-pentanediol diglycidyl ether epoxy group to DOPO is 1:1) to the bottle, heat to 70°C, react for 12 h, remove anhydrous ethanol by rotary evaporation, and dry to obtain epoxy-DOPO intermediate.

[0024] (2) Add an appropriate amount of epoxy-DOPO intermediate and dimethylformamide to a transparent reactor (the mass ratio of epoxy-DOPO intermediate to dimethylformamide is 0.4:1), stir at 60°C until the epoxy-DOPO intermediate is completely dissolved, and continue to add an appropriate amount of trimethylolphosphine oxide (the molar ratio of epoxy-DOPO intermediate to trimethylolphosphine oxide is 1:1) and potassium hydroxide (the amount of potassium hydroxide is 2% of the total weight of epoxy-DOPO intermediate and trimethylolphosphine oxide), continue to react at 120°C for 12 hours, remove the solvent by rotary evaporation, and dry to obtain the DOPO reactive flame retardant.

[0025] Example 4

[0026] (1) Add a measured amount of DOPO and anhydrous ethanol (mass ratio of DOPO to anhydrous ethanol is 0.4:1) to a transparent reactor, heat at 60°C until DOPO is completely dissolved, continue to add a measured amount of 1,6-hexanediol diglycidyl ether (molar ratio of 1,6-hexanediol diglycidyl ether epoxy group to DOPO is 1:1) to the bottle, heat to 70°C, react for 12 h, remove anhydrous ethanol by rotary evaporation, and dry to obtain epoxy-DOPO intermediate.

[0027] (2) Add an appropriate amount of epoxy-DOPO intermediate and dimethylformamide to a transparent reactor (the mass ratio of epoxy-DOPO intermediate to dimethylformamide is 0.4:1), stir at 60°C until the epoxy-DOPO intermediate is completely dissolved, and continue to add an appropriate amount of trimethylolphosphine oxide (the molar ratio of epoxy-DOPO intermediate to trimethylolphosphine oxide is 1:1) and potassium hydroxide (the amount of potassium hydroxide is 2% of the total weight of epoxy-DOPO intermediate and trimethylolphosphine oxide), continue to react at 120°C for 12 hours, remove the solvent by rotary evaporation, and dry to obtain the DOPO reactive flame retardant.

[0028] Examples 5-8

[0029] The DOPO reactive flame retardant (15% of the mass of phenol) synthesized in Examples 1-4 was added to a reactor along with phenol and paraformaldehyde (phenol-formaldehyde molar ratio of 1:1.85). Sodium hydroxide was added to adjust the pH of the system to 9-10, and the temperature was raised to 70°C. After the paraformaldehyde was completely depolymerized, the temperature was raised to 85-90°C. After the reaction was completed, phenolic resin containing DOPO reactive flame retardant was obtained. The obtained resin was mixed evenly with PEG-12 polydimethylsiloxane, n-pentane, and curing agent, poured into a mold, and cured in an oven at 70°C for 0.5 hours to obtain phenolic foam containing DOPO reactive flame retardant. The mechanical properties of the foam were tested in a SANS7 oven. The tests were conducted on a CMT-4304 universal testing machine, following standards GB / TB8813-2008 and GB / T8812.1-2007, to assess the flexural and compressive properties of the foam. The critical oxygen index was determined using a JF-3 oxygen index meter according to method GB / 2406.1-2008. The sample size was 100×10×10 μm. 3 The test results for each embodiment are shown in Table 1.

[0030] Table 1. Main performance indicators of phenolic foam prepared in Examples 5-8 (45 kg / m³) 3 )

[0031] Bending performance / MPa 6.96 6.52 6.41 5.85 4.03 Compression performance / MPa 0.33 0.28 0.24 0.18 0.16 Critical oxygen index / % 55 52 50 45 38.4

[0032] As can be seen from the data in the table, the phenolic foam containing DOPO reactive flame retardant prepared in this invention has significantly better bending, compression, and critical oxygen index properties than ordinary phenolic foam.

[0033] The above examples are merely illustrative of the technical concept and features of this invention, intended to enable those skilled in the art to understand the content of this invention and implement it accordingly, and should not be construed as limiting the scope of protection of this invention. All equivalent transformations or modifications made in accordance with the spirit and essence of this invention should be included within the scope of protection of this invention.

Claims

1. A method for synthesizing a DOPO reactive flame retardant, characterized in that... The preparation steps are as follows: (1) Add DOPO and organic solvent to the reactor, wherein the mass ratio of DOPO to organic solvent is 0.2-0.6:1, stir until DOPO is completely dissolved, and continue to add epoxy monomer to the reactor, wherein the molar ratio of epoxy group of epoxy monomer to DOPO is 1:1, continue to react at 60-90℃ for 10-16 h, remove solvent by rotary evaporation, and dry to obtain epoxy-DOPO intermediate; wherein the epoxy monomer is at least one of ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,5-pentanediol diglycidyl ether, and 1,6-hexanediol diglycidyl ether; (2) Add epoxy-DOPO intermediate and organic solvent to the reactor, wherein the mass ratio of epoxy-DOPO intermediate to organic solvent is 0.2-0.6:

1. Stir until epoxy-DOPO intermediate is completely dissolved. Continue to add trimethylolphosphine oxide and potassium hydroxide to the reactor, wherein the molar ratio of epoxy-DOPO intermediate to trimethylolphosphine oxide is 0.9-1.2:

1. The amount of potassium hydroxide is 1-3% of the total weight of epoxy-DOPO intermediate and trimethylolphosphine oxide. Continue to react at 90-130℃ for 10-16h. Remove the solvent by rotary evaporation and dry to obtain DOPO reactive flame retardant.

2. The method for synthesizing the DOPO reactive flame retardant according to claim 1, characterized in that, The organic solvent mentioned in step (1) is at least one of methanol, ethanol, chloroform, and dioxane; the mass ratio of DOPO to the organic solvent is 0.4:

1.

3. The method for synthesizing the DOPO reactive flame retardant according to claim 1, characterized in that, The organic solvent mentioned in step (2) is dimethylformamide or dioxane; the mass ratio of epoxy-DOPO intermediate to organic solvent is 0.4:

1.

4. The method for synthesizing the DOPO reactive flame retardant according to claim 1, characterized in that, The molar ratio of the epoxy-DOPO intermediate and trihydroxymethylphosphine oxide in step (2) is 1:

1.

5. The method for synthesizing the DOPO reactive flame retardant according to claim 1, characterized in that, The amount of potassium hydroxide used in step (2) is 2% of the total weight of the epoxy-DOPO intermediate and trimethylolphosphine oxide.

6. The DOPO reactive flame retardant prepared by any one of claims 1 to 5.

7. The use of the DOPO reactive flame retardant of claim 6 in the preparation of plastics and foams.

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