Nitrogen-containing phosphorus DOPO reactive flame retardant, and preparation method and application thereof

Abstract

The application relates to a nitrogen and phosphorus-containing DOPO reaction type flame retardant as well as a preparation method and application thereof, which comprises the following steps: mixing and dissolving DOPO and an organic solvent, adding an epoxy monomer, continuously reacting at 60-90 DEG C for 10-16 hours, removing the solvent through rotary evaporation, drying to obtain a DOPO type reaction type flame retardant monomer; mixing the DOPO type reaction type flame retardant monomer and the organic solvent, stirring until the DOPO type reaction type flame retardant monomer is completely dissolved, continuously adding dicyandiamide and triethylamine into the reactor, removing the solvent through rotary evaporation, drying to obtain the nitrogen and phosphorus-containing DOPO reaction type flame retardant. The nitrogen and phosphorus-containing DOPO reaction type flame retardant with high flame retardance is prepared by connecting DOPO and dicyandiamide through diglycidyl ether as a bridge. The nitrogen and phosphorus-containing DOPO reaction type flame retardant promotes the generation of carbon at high temperature through the nitrogen and phosphorus synergistic effect, plays the roles of heat insulation, oxygen insulation and smoke suppression, interrupts the chain reaction of combustion, prevents the generation of melt dripping phenomenon, and has good flame retardation effect.

Description

Technical Field

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

[0002] With continuous economic development, polymer materials are increasingly used in transportation, construction, aviation, and other fields. Polymer products are also appearing more and more frequently in people's production and daily lives. However, due to the flammability of polymer materials, flame retardants are usually added to improve their flame-retardant properties, thereby reducing their potential hazards. Traditional halogenated flame retardants release large amounts of toxic gases and fumes during combustion, causing serious environmental pollution. Therefore, halogen-free flame retardants have become the current development trend. Among them, phosphorus-containing and nitrogen-containing flame retardants are new types of halogen-free flame retardants that have attracted much attention in recent years, possessing advantages such as high efficiency, low smoke, low toxicity, and environmental friendliness. However, traditional nitrogen-containing and phosphorus-containing flame retardants have low flame-retardant efficiency, and large amounts of flame retardants can cause a loss of material mechanical properties and are prone to migration and precipitation. Therefore, there is an urgent need to design and synthesize flame retardants with good flame-retardant effects and good matrix compatibility.

[0003] 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) is a novel reactive phosphorus-based flame retardant intermediate with advantages such as good chemical stability, excellent flame retardant properties, high flame retardant efficiency, halogen-free and non-toxic, and environmentally friendly. It is widely added to polymer materials to improve their flame retardant performance. DOPO has a unique chemical structure; its reactive pH bonds readily react with carbon-carbon double bonds, epoxy groups, and carbonyl groups to obtain DOPO derivatives. Therefore, other synergistic flame-retardant elements can be introduced into the DOPO structure to further enhance the flame retardant effect of DOPO-type flame retardants. Nitrogen-phosphorus flame retardants, in particular, have advantages such as low migration, good thermal stability, high efficiency and non-toxicity, wide applicability, and good economic efficiency, and are widely used in plastics, rubber, resins, and other materials. Summary of the Invention

[0004] Technical problem to be solved: The present invention aims to provide an easy-to-use, nitrogen-phosphorus DOPO reactive flame retardant, its preparation method and application.

[0005] Technical solution: A method for preparing a nitrogen-phosphorus DOPO reactive flame retardant, the preparation steps are as follows: (1) DOPO and organic solvent are mixed and dissolved, wherein the mass ratio of DOPO to organic solvent is (0.2-0.6):1, an epoxy monomer is added, wherein the molar ratio of epoxy group of epoxy monomer to DOPO is (0.9-1.2):1, the reaction is continued at 60-90℃ for 10-16h, the solvent is removed by rotary evaporation, and the DOPO reactive flame retardant monomer is obtained by drying; the organic solvent is at least one of methanol, anhydrous ethanol, chloroform, and dioxane; the epoxy monomer is ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,5-pentanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether. (1) At least one of glycerol ethers; (2) Mix DOPO reactive flame retardant monomer and organic solvent, wherein the mass ratio of DOPO reactive flame retardant monomer to organic solvent is (0.2-0.6):1, wherein the organic solvent is either dimethylformamide or dimethyl sulfoxide, stir until DOPO reactive flame retardant monomer is completely dissolved, continue to add dicyandiamide and triethylamine to reactor, wherein the molar ratio of DOPO reactive flame retardant monomer to dicyandiamide is (0.8-1.2):1, the amount of triethylamine is 1%-3% of the total weight of DOPO reactive flame retardant monomer and dicyandiamide, continue to react at 60-90℃ for 10-16h, remove solvent by rotary evaporation, and dry to obtain nitrogen-phosphorus DOPO reactive flame retardant.

[0006] The mass ratio of DOPO to organic solvent in step (1) is 0.4:1.

[0007] In step (1), the molar ratio of epoxy groups to DOPO in the epoxy monomer is 1:1.

[0008] In step (2), the mass ratio of DOPO reactive flame retardant monomer to organic solvent is 0.4:1.

[0009] The molar ratio of DOPO-type reactive flame retardant monomer and dicyandiamide in step (2) is 1:1.

[0010] The amount of triethylamine used in step (2) is 2% of the total weight of the DOPO-type reactive flame retardant monomer and dicyandiamide.

[0011] The nitrogen-phosphorus DOPO reactive flame retardant prepared by the above method.

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

[0013] Beneficial Effects: This invention uses diglycidyl ether as a bridge to connect DOPO and dicyandiamide to prepare a highly flame-retardant nitrogen-phosphorus DOPO reactive flame retardant. As a halogen-free intumescent flame retardant, this nitrogen-phosphorus flame retardant promotes char formation at high temperatures through a synergistic effect of nitrogen and phosphorus, providing heat insulation, oxygen isolation, and smoke suppression. It interrupts the chain reaction of combustion and prevents dripping, exhibiting excellent flame-retardant properties. Attached Figure Description

[0014] Figure 1 This describes the synthetic route for nitrogen-phosphorus DOPO reactive flame retardants. 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 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 ethylene glycol diglycidyl ether (molar ratio of ethylene glycol diglycidyl ether epoxy group to DOPO is 1:1) to the bottle, raise the temperature to 70°C, react for 12 h, remove anhydrous ethanol by rotary evaporation, and dry to obtain DOPO-type reactive flame retardant monomer.

[0018] (2) Add DOPO reactive flame retardant monomer and dimethylformamide to a transparent reactor (the mass ratio of DOPO reactive flame retardant monomer to organic solvent is 0.4:1), stir at 60°C until the DOPO reactive flame retardant monomer is completely dissolved, continue to add dicyandiamide (the molar ratio of DOPO reactive flame retardant monomer to dicyandiamide is 1:1) and triethylamine (the amount of triethylamine is 2% of the total weight of DOPO reactive flame retardant monomer and dicyandiamide) to the reactor, continue to react at 70°C for 12 hours, remove the solvent by rotary evaporation, and dry to obtain nitrogen-phosphorus DOPO reactive flame retardant.

[0019] Example 2

[0020] (1) Add 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 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 DOPO-type reactive flame retardant monomer.

[0021] (2) Add DOPO reactive flame retardant monomer and dimethylformamide to a transparent reactor (the mass ratio of DOPO reactive flame retardant monomer to dimethylformamide is 0.4:1), stir at 60°C until the DOPO reactive flame retardant monomer is completely dissolved, continue to add dicyandiamide (the molar ratio of DOPO reactive flame retardant monomer to dicyandiamide is 1:1) and triethylamine (the amount of triethylamine is 2% of the total weight of DOPO reactive flame retardant monomer and dicyandiamide) to the reactor, continue to react at 70°C for 12 hours, remove the solvent by rotary evaporation, and dry to obtain nitrogen-phosphorus DOPO reactive flame retardant.

[0022] Example 3

[0023] (1) Add 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 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 DOPO-type reactive flame retardant monomer.

[0024] (2) Add DOPO reactive flame retardant monomer and dimethylformamide to a transparent reactor (the mass ratio of DOPO reactive flame retardant monomer to dimethylformamide is 0.4:1), stir at 60°C until the DOPO reactive flame retardant monomer is completely dissolved, continue to add dicyandiamide (the molar ratio of DOPO reactive flame retardant monomer to dicyandiamide is 1:1) and triethylamine (the amount of triethylamine is 2% of the total weight of DOPO reactive flame retardant monomer and dicyandiamide) to the reactor, continue to react at 70°C for 12 hours, remove the solvent by rotary evaporation, and dry to obtain nitrogen-phosphorus DOPO reactive flame retardant.

[0025] Example 4

[0026] (1) Add 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 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 DOPO-type reactive flame retardant monomer.

[0027] (2) Add DOPO reactive flame retardant monomer and dimethylformamide to a transparent reactor (the mass ratio of DOPO reactive flame retardant monomer to dimethylformamide is 0.4:1), stir at 60°C until the DOPO reactive flame retardant monomer is completely dissolved, continue to add dicyandiamide (the molar ratio of DOPO reactive flame retardant monomer to dicyandiamide is 1:1) and triethylamine (the amount of triethylamine is 2% of the total weight of DOPO reactive flame retardant monomer and dicyandiamide) to the reactor, continue to react at 70°C for 12 hours, remove the solvent by rotary evaporation, and dry to obtain nitrogen-phosphorus DOPO reactive flame retardant.

[0028] Examples 5-8

[0029] The nitrogen-phosphorus DOPO reactive flame retardant (15% of phenol by mass) synthesized in Examples 1-4 was added to a reactor along with phenol and paraformaldehyde (phenol-formaldehyde molar ratio of 1:1.7). 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, a phenolic resin containing the novel nitrogen-phosphorus DOPO reactive flame retardant was obtained. The obtained resin was mixed evenly with Tween-80, n-pentane, phosphoric acid, and other additives, poured into a mold, and cured in an oven at 75°C for 2 hours to obtain a phenolic foam containing the novel nitrogen-phosphorus 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

[0031] Bending performance / MPa 0.43 0.41 0.37 0.31 0.15 Compression performance / MPa 6.71 6.42 5.96 5.74 4.12 Critical oxygen index / % 54 51 48 44 36

[0032] As can be seen from the data in the table, the phenolic foam containing the novel nitrogen-phosphorus 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 preparing a nitrogen-phosphorus DOPO reactive flame retardant, comprising the following steps: (1) mixing and dissolving DOPO and an organic solvent, wherein the mass ratio of DOPO to the organic solvent is (0.2-0.6):1, adding an epoxy monomer, wherein the molar ratio of the epoxy group of the epoxy monomer to DOPO is (0.9-1.2):1, continuing the reaction at 60-90℃ for 10-16 h, removing the solvent by rotary evaporation, and drying to obtain a DOPO-type reactive flame retardant monomer; wherein the organic solvent is at least one of methanol, anhydrous ethanol, chloroform, and dioxane; 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; characterized in that, The steps also include: (2) mixing DOPO reactive flame retardant monomer and organic solvent, wherein the mass ratio of DOPO reactive flame retardant monomer to organic solvent is (0.2-0.6):1, and the organic solvent is either dimethylformamide or dimethyl sulfoxide. Stirring until the DOPO reactive flame retardant monomer is completely dissolved, and then adding dicyandiamide and triethylamine to the reactor, wherein the molar ratio of DOPO reactive flame retardant monomer to dicyandiamide is (0.8-1.2):1, and the amount of triethylamine is 1%-3% of the total weight of DOPO reactive flame retardant monomer and dicyandiamide. The reaction is continued at 60-90℃ for 10-16 hours, the solvent is removed by rotary evaporation, and the product is dried to obtain nitrogen-phosphorus DOPO reactive flame retardant.

2. The preparation method of the nitrogen-phosphorus DOPO reactive flame retardant according to claim 1, characterized in that, The mass ratio of DOPO to organic solvent in step (1) is 0.4:

1.

3. The preparation method of the nitrogen-phosphorus DOPO reactive flame retardant according to claim 1, characterized in that, In step (1), the molar ratio of epoxy groups to DOPO in the epoxy monomer is 1:

1.

4. The preparation method of the nitrogen-phosphorus DOPO reactive flame retardant according to claim 1, characterized in that, In step (2), the mass ratio of DOPO reactive flame retardant monomer to organic solvent is 0.4:

1.

5. The preparation method of the nitrogen-phosphorus DOPO reactive flame retardant according to claim 1, characterized in that, The molar ratio of DOPO reactive flame retardant monomer and dicyandiamide in step (2) is 1:

1.

6. The preparation method of the nitrogen-phosphorus DOPO reactive flame retardant according to claim 1, characterized in that, The amount of triethylamine used in step (2) is 2% of the total weight of the DOPO-type reactive flame retardant monomer and dicyandiamide.

7. A nitrogen-phosphorus DOPO reactive flame retardant prepared by any one of claims 1 to 6.

8. The use of the nitrogen-phosphorus DOPO reactive flame retardant of claim 7 in the preparation of plastics and foams.

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