Reactive phosphorus-nitrogen flame retardant, and preparation method and use thereof
By preparing reactive phosphorus-nitrogen flame retardants containing phosphorus, nitrogen, benzene rings, and triazine rings, the problems of limited variety, high price, and high halogen content of existing flame retardants have been solved, achieving efficient and environmentally friendly flame retardant effects for polyurethane foam and improving the flame retardant performance of polyurethane foam.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JIANGSU CHANGNENG ENERGY SAVING NEW MATERIALS SCI & TECH
- Filing Date
- 2023-04-28
- Publication Date
- 2026-07-14
AI Technical Summary
Existing reactive flame retardants are limited in variety, expensive, have poor flame retardant effects, contain halogens and are not environmentally friendly, and additive flame retardants have poor compatibility with polyurethane, leading to a decline in the performance of polyurethane foam.
A reactive phosphorus-nitrogen flame retardant is prepared by chemical reaction. 2,4,6-tris(N,N-dihydroxyethyl)amino-1,3,5-triazine is grafted with phosphorus and chlorine compounds to form flame retardant elements containing phosphorus, nitrogen, benzene rings, and triazine rings, which are then incorporated into the polyurethane foam macromolecular chain. The preparation method includes stirring, dropping, extraction, and vacuum distillation steps.
The prepared flame retardant has good, long-lasting and stable flame retardant effect, is environmentally friendly, halogen-free and formaldehyde-free, and can significantly increase the critical oxygen index of polyurethane foam to 27.2% without affecting the performance of polyurethane foam.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention relates to the field of organic synthesis, and in particular to a reactive phosphorus-nitrogen flame retardant, its preparation method, and its uses. Background Technology
[0002] Flame retardants are additives that improve the flame retardancy, self-extinguishing properties, or smoke suppression of flammable or combustible materials. They are mainly used in transportation, furniture, and building materials. Classified by flame-retardant elements, flame retardants can be divided into halogenated flame retardants, phosphorus-based flame retardants, and nitrogen-based flame retardants. Halogenated flame retardants have high flame-retardant efficiency, require low dosage, and are relatively low in cost, while bromine-based flame retardants have good compatibility with materials. However, halogenated flame retardants release corrosive and toxic gases such as hydrogen halides under high-temperature open flame conditions, accompanied by dense smoke. Under increasingly stringent environmental and flame-retardant regulations, the market for halogenated flame retardants is gradually shrinking. Phosphorus-based and nitrogen-based flame retardants, on the other hand, have gained widespread attention due to their advantages such as low halogen content, halogen-free composition, low smoke, low toxicity, low dosage, and high efficiency.
[0003] Phosphorus and nitrogen-based flame retardants can be further classified into additive phosphorus and nitrogen flame retardants and reactive phosphorus and nitrogen flame retardants according to their different application principles. Additive phosphorus and nitrogen flame retardants mainly include red phosphorus, phosphates, and melamine derivatives; however, additive flame retardants generally have poor compatibility with polyurethane foam, especially solid flame retardants embedded in polyurethane through physical blending, which can cause foam collapse during the foaming process and reduce the physical properties of polyurethane. Reactive phosphorus and nitrogen flame retardants have reactive functional groups inside their molecules, which can participate in the reaction during the polyurethane foaming process and bind to the polyurethane molecular chain. They have advantages such as good stability, long-lasting flame retardant effect, low toxicity, and minimal impact on the performance of polyurethane foam; however, there are fewer varieties of reactive phosphorus and nitrogen flame retardants, and their development is more difficult. Currently, it remains one of the research directions that continues to receive attention.
[0004] Meanwhile, with the continuous expansion of flame retardant applications, the requirements for aldehyde content in flame retardants are becoming increasingly stringent in applications such as home furnishings and seating. Therefore, developing a formaldehyde-free flame retardant that is friendly to humans and the environment has become an inevitable trend.
[0005] Chinese patent application CN115679470A discloses a flame-retardant polyester fiber fabric and its preparation method, which synthesizes a dicarboxylic acid triazine phosphate flame retardant. The preparation method includes: adding 6-(N,N-dihydroxyethyl)amino-2,4-dichloro-1,3,5-triazine, serine, and N,N-diisopropylethylamine to tetrahydrofuran, stirring to dissolve, and then reacting at 60-75°C for 6-18 hours. After the reaction, the mixture is cooled, concentrated under reduced pressure, and recrystallized. 6-(N,N-dihydroxyethyl)amino-2,4-serine-1,3,5-triazine was obtained; then it was reacted with 5,5-dimethyl-1,3-dioxacaprolactone chloride at 25-40°C for 12-36 h. The resulting triazine phosphate used the triazine ring as the nitrogen source and the tetrafunctional dioxacaprolactone phosphate as the phosphorus source to form a nitrogen-phosphorus synergistic flame retardant system, which has a good flame retardant effect. However, its structure contains the functional group carboxyl, so it cannot be applied in the field of polyurethane. Summary of the Invention
[0006] One of the technical problems to be solved by the present invention is that existing reactive flame retardants are few in variety, expensive, have poor flame retardant effect, and contain halogens, which are not environmentally friendly. The present invention provides a reactive phosphorus-nitrogen flame retardant that has the advantages of good flame retardant effect, long flame retardant performance, good stability, no formaldehyde or halogens, little environmental impact and economical raw materials.
[0007] The second technical problem to be solved by the present invention is to provide a method for preparing a reactive phosphorus-nitrogen flame retardant, which corresponds to the solution of the first technical problem.
[0008] The third technical problem to be solved by the present invention is to provide a use corresponding to solving one of the technical problems.
[0009] To solve one of the above-mentioned technical problems, the present invention adopts the following technical solution: a reactive phosphorus-nitrogen flame retardant, the structural formula of which is as follows:
[0010]
[0011] Among them, R1-R4 are selected from -H, One of them, and R1-R4 are not all -H at the same time.
[0012] To solve the second technical problem mentioned above, the present invention adopts the following technical solution: a method for preparing a reactive phosphorus-nitrogen flame retardant, comprising the following steps:
[0013] (1) 2,4,6-tris(N,N-dihydroxyethyl)amino-1,3,5-triazine, acid binder, and reaction solvent were added to a reaction vessel and stirred evenly under ice bath conditions to obtain material I;
[0014] (2) Add phosphorus and chlorine compound dropwise to material I for 1 to 3 hours. The molar ratio of the added phosphorus and chlorine compound to 2,4,6-tris(N,N-dihydroxyethyl)amino-1,3,5-triazine is 1 to 4:1 to obtain material II.
[0015] (3) After the addition is complete, continue the reaction in an ice bath for 1 to 3 hours, then naturally heat up to room temperature and continue the reaction for 1 to 12 hours to obtain material III; (4) After the reaction is complete, filter the solution, and extract, dry and distill under reduced pressure to obtain the reactive phosphorus and nitrogen flame retardant product.
[0016] In the above technical solution, preferably, the acid-binding agent in step (1) is selected from at least one of triethylamine or pyridine, and its molar ratio with that of the phosphorus-chlorine compound is 1:1.
[0017] In the above technical solution, preferably, the reaction solvent in step (1) is selected from at least one of dichloromethane, trichloromethane or tetrahydrofuran.
[0018] In the above technical solution, preferably, the phosphorus-chlorine compound in step (2) is selected from at least one of diphenylphosphine chloride, diphenylphosphine chloride, or diphenoxyphosphine chloride.
[0019] In the above technical solution, preferably, the ice bath temperature is -10 to 10°C.
[0020] In the above technical solution, preferably, the filtrate in step (4) is first extracted with chloroform and sodium chloride aqueous solution, and then dried with anhydrous sodium sulfate; the conditions for vacuum distillation are a temperature of 40 to 70°C and a pressure of -0.08 to -0.10 MPa, measured by a gauge pressure gauge.
[0021] This invention provides a reactive phosphorus-nitrogen flame retardant. The phosphorus-nitrogen flame retardant compound is obtained by grafting a phosphorus-chlorine compound with 2,4,6-tris(N,N-dihydroxyethyl)amino-1,3,5-triazine via a chemical reaction and then purifying the resulting compound. This compound contains elements or groups with flame-retardant effects, such as phosphorus, nitrogen, benzene rings, and triazine rings, exhibiting excellent flame-retardant properties. Furthermore, the compound contains at least two reactive groups (-OH), which, when added to the foaming formulation of polyurethane foam, can further react with -NCO in the black component. This allows the flame-retardant elements to be integrated into the macromolecular chain structure of the polyurethane foam, preventing migration and ensuring long-lasting flame retardant performance. Moreover, this structure is halogen-free and aldehyde-free, offering environmental friendliness. When this flame retardant is applied to the flame retardancy of polyurethane foam, only this one flame retardant is needed to increase the critical oxygen index of the polyurethane foam to 27.2%, achieving significant technical benefits. Detailed Implementation
[0022] The following are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. All technical solutions that fall within the scope of the present invention should be included in the scope of protection of the present invention. For those skilled in the art, minor improvements and modifications made to the present invention without departing from the principle of the present invention should also be included in the scope of protection of the present invention.
[0023]
Example 1
[0024] A reactive phosphorus-nitrogen flame retardant, the preparation method of which includes the following steps:
[0025] (1) Weigh 2,4,6-tris(N,N-dihydroxyethyl)amino-1,3,5-triazine, triethylamine and chloroform and add them to a round-bottom flask. Stir them evenly under ice bath conditions to obtain material I.
[0026] (2) Add diphenylphosphine chloride dropwise to material I. The molar ratio of diphenylphosphine chloride to 2,4,6-tris(N,N-dihydroxyethyl)amino-1,3,5-triazine is 3:1. The dropwise addition time is 3h to obtain material II.
[0027] (3) After the addition is complete, continue the reaction in an ice bath for 1 hour, then naturally heat to room temperature and continue the reaction for 8 hours to obtain material III;
[0028] (4) After the reaction was completed, the mixture was filtered. The filtrate was extracted with chloroform and sodium chloride aqueous solution, dried with anhydrous sodium sulfate, and then distilled under reduced pressure to obtain reactive phosphorus-nitrogen flame retardant S1. Its physical property data are shown in Table 3. The main structural formula of the product is as follows:
[0029]
[0030]
Examples 2-6
[0031] Examples 2 to 6 were carried out according to the steps in Example 1, with the differences being the reaction raw materials, raw material ratios, reaction time, and reaction temperature, as shown in Table 1; the performance data of the obtained reactive phosphorus-nitrogen flame retardant products are shown in Table 3.
[0032] Table 1. Molar ratios of raw materials and reaction conditions in the preparation of reactive phosphorus-nitrogen flame retardants in Examples 1-6.
[0033]
[0034]
[0035] The main structural formulas of the reactive phosphorus-nitrogen flame retardants prepared in Examples 2-6 are as follows: S2: S3: S4: S5: S6:
[0036]
Example 7
[0037] The reactive phosphorus-nitrogen flame retardants prepared in Examples 1 to 6 were added to the polyurethane foam formulation to improve the flame retardant properties of the polyurethane foam. The weight parts of each component in the formulation are shown in Table 2, and the flame retardant properties of the obtained polyurethane foam are shown in Table 3.
[0038] Table 2 shows the weight parts of each component in the polyurethane foam formulation for Examples 1-6 and Comparative Example 1.
[0039]
[0040]
Comparative Example 1
[0041] The phosphorus-nitrogen flame retardant was synthesized according to the technical solution of Example 1 in Chinese patent application CN110283207A, and the steps are as follows:
[0042] Hexamethoxymethyl melamine (HMMM, 3.9 g, 0.01 mol) and phosphate diol (di-2-hydroxyethylamine methyl phosphate diethyl ester, FRC-6, 5.1 g, 0.02 mol) were added to a 100 mL three-necked flask, followed by p-toluenesulfonic acid (TsOH, approximately 0.005 g) and N,N-dimethylformamide (DMF, 2 g). The ether exchange reaction was carried out under nitrogen protection and magnetically stirred at 120 °C for 3 h. The reaction system was cooled to room temperature, 2 mL of ethyl acetate was added and stirred until homogeneous, and then 12 mL of n-hexane was added under stirring. The mixture was allowed to stand and the phases separated, and the supernatant was removed. This process was repeated 3–5 times. The lower viscous layer was then rotary evaporated at 55–70 °C to remove the solvent, yielding a brownish-yellow viscous product: phosphorus-nitrogen synergistic flame retardant S, with a yield of 95%.
[0043] The obtained flame retardant was added to the polyurethane foam formulation to improve the flame retardant properties of the polyurethane foam. The weight parts of each component in the formulation are shown in Table 2, and the flame retardant properties of the obtained polyurethane foam are shown in Table 3.
[0044] Table 3. Index data of phosphorus-nitrogen flame retardants and their polyurethane foams in Examples 1-6 and Comparative Example 1.
[0045]
[0046] As shown in Table 3, the critical oxygen index performance data indicates that when the reactive phosphorus-nitrogen flame retardants prepared in Examples 1-6 are added to the same polyurethane foam foam formulation at the same dosage, the critical oxygen index of the resulting polyurethane foam is above 24.5%, reaching 27.2%, which is superior to that of Comparative Example 1. Furthermore, the flame retardant prepared in this invention is a reactive flame retardant containing multiple flame retardant elements such as phosphorus, nitrogen, benzene ring, and triazine ring in its compound structure, resulting in more durable flame retardant performance. The flame retardant compound structure does not contain halogen or aldehyde structures, making it more environmentally friendly and possessing good technical effects. It can be used to improve the flame retardant performance of polyurethane foam.
Claims
1. A reactive phosphorus-nitrogen flame retardant, the structural formula of which is as follows: ； in, R1-R4 are selected from -H, One of them, and R1-R4 are not all -H at the same time.
2. A method for preparing the reactive phosphorus-nitrogen flame retardant according to claim 1, comprising the following steps: (1) 2,4,6-tris(N,N-dihydroxyethyl)amino-1,3,5-triazine, along with an acid-binding agent and a reaction solvent, were added to a reaction vessel and stirred evenly under ice bath conditions to obtain material I; (2) Add phosphorus and chlorine compounds dropwise to material I for 1-3 hours. The molar ratio of the added phosphorus and chlorine compounds to 2,4,6-tris(N,N-dihydroxyethyl)amino-1,3,5-triazine is 1-4:1 to obtain material II. (3) After the addition is complete, continue the reaction in an ice bath for 1-3 hours, then naturally heat to room temperature and continue the reaction for 1-12 hours to obtain material III; (4) After the reaction is completed, the product is filtered, and the filtrate is extracted, dried and distilled under reduced pressure to obtain the reactive phosphorus-nitrogen flame retardant product.
3. The preparation method of the reactive phosphorus-nitrogen flame retardant according to claim 2, characterized in that, The acid-binding agent in step (1) is selected from at least one of triethylamine or pyridine, and its molar ratio with that of the phosphorus-chlorine compound is 1:
1.
4. The preparation method of the reactive phosphorus-nitrogen flame retardant according to claim 2, characterized in that, The reaction solvent in step (1) is selected from at least one of dichloromethane, trichloromethane, or tetrahydrofuran.
5. The method for preparing the reactive phosphorus-nitrogen flame retardant according to claim 2, characterized in that, The phosphorus-chlorine compound in step (2) is diphenylphosphine chloride.
6. The method for preparing the reactive phosphorus-nitrogen flame retardant according to claim 2, characterized in that, The ice bath temperature is -10 to 10℃.
7. The preparation method of the reactive phosphorus-nitrogen flame retardant according to claim 2, characterized in that, The filtrate in step (4) is first extracted with chloroform and sodium chloride aqueous solution, and then dried with anhydrous sodium sulfate; the conditions for vacuum distillation are a temperature of 40 to 70°C and a pressure of -0.08 to -0.10 MPa, measured by a gauge pressure gauge.
8. The application of the reactive phosphorus-nitrogen flame retardant according to claim 1 in the flame retardancy of polyurethane foam.