Phosphorus-containing dihydric alcohol flame retardant as well as preparation and application thereof

Abstract

The invention relates to a phosphorus-containing dihydric alcohol flame retardant as well as preparation and application thereof, and belongs to the field of organic compounds. The invention provides phosphorus-containing dihydric alcohol. The structure of the phosphorus-containing dihydric alcohol is shown as a formula I in the specification. Trihydroxymethyl phosphorus oxide and inorganic acid react to synthesize eight-membered ring-shaped phosphorus-containing dihydric alcohol (DTHPO for short), the eight-membered ring-shaped phosphorus-containing dihydric alcohol is applied to polyurethane foam preparation, flame-retardant intrinsic polyurethane foam is obtained, and the limit oxygen index of the obtained flame-retardant material can reach 27%. # imgabs0 #

Description

Technical Field

[0001] The invention relates to a phosphorus-containing diol flame retardant and preparation and application thereof, belonging to the field of organic compounds. Background Art

[0002] Rigid polyurethane foam (RPUF) has the advantages of light weight, high specific strength, low thermal conductivity, aging resistance, chemical corrosion resistance, and good bonding performance. It is currently the most widely used insulation material in the world and is used in many fields such as building insulation, cold storage insulation, and rail transportation. However, RPUF is composed of a large number of flammable hydrocarbon segments, and has low density and large specific surface area. Its limiting oxygen index (LOI) is only 18-20%, which is very easy to ignite, accompanied by a large amount of heat and toxic gases such as HCN and CO. There is a great fire hazard. In view of the flammability problem of polyurethane foam, flame retardants are often introduced in the preparation process by blending or copolymerization. In the early stage of RPUF combustion and decomposition, the flame retardant achieves the flame retardancy of RPUF by terminating the chain reaction of combustion free radicals, diluting the concentration of combustible gases, and hindering heat transfer. Organophosphorus flame retardants are favored by people because of their non-toxic and harmless advantages, but there are still problems to be solved in achieving long-term flame retardancy of RPUF. The reason is that most phosphorus-based flame retardants are additive flame retardants, which can easily migrate and precipitate from polyurethane curing materials under external conditions, resulting in a decrease in the flame retardant properties of the material. Intrinsic flame retardant FPUF can effectively alleviate the above problems by introducing flame retardants into the polyurethane network structure through covalent bonds.

[0003] Among halogen-free flame retardants, organophosphorus flame retardants are favored by people due to their high efficiency, low toxicity, harmlessness to the environment and adjustable structure. Chen Mingjun et al. found that the intrinsic flame retardant polyurethane foam constructed with trihydroxymethylphosphine oxide (THPO) exhibits a rare expansion and charring behavior, which has attracted the attention of a large number of flame retardant peers (M.-J.Chen, C.-R.Chen, Y.Tan, J.-Q.Huang, X.-L.Wang, L.Chen, Y.-Z.Wang, Ind.Eng.Chem.Res.53(2014)1160–1171.), but the flame retardant efficiency of the phosphorus-based flame retardants derived from this is low. Summary of the invention

[0004] The invention synthesizes an octacyclic phosphorus-containing diol (DTHPO for short) by reacting trihydroxymethylphosphine oxide with an inorganic acid, and applies the DTHPO to the preparation of polyurethane foam to obtain flame-retardant intrinsic polyurethane foam. The limiting oxygen index of the obtained flame-retardant material can reach 27%.

[0005] The technical solution of the present invention:

[0006] The first technical problem to be solved by the present invention is to provide a phosphorus-containing diol, the structure of which is shown in Formula I:

[0007]

[0008] The second problem to be solved by the present invention is to provide a method for preparing the above-mentioned phosphorus-containing diol. The preparation method comprises the following steps: firstly, under the protection of nitrogen or inert gas, stirring and mixing anhydrous trihydroxymethylphosphine oxide, acid and organic solvent; then heating to 100-160° C. for reaction for 2-48 hours; and finally, purifying to obtain the phosphorus-containing diol shown in formula I; wherein the dosage ratio of acid to trihydroxymethylphosphine oxide is 0.1-2 mL: 1 g, i.e., the dosage of acid per milliliter is 0.1-2 times the weight of trihydroxymethylphosphine oxide in grams.

[0009] Furthermore, the acid includes Bronsted acid such as concentrated sulfuric acid, concentrated phosphoric acid, nitric acid, formic acid or acetic acid, etc., preferably concentrated sulfuric acid (mass concentration ≥ 70%) and concentrated phosphoric acid (mass concentration ≥ 85%).

[0010] Furthermore, the organic solvent includes a polar solvent, an alcohol solvent, an ether solvent, a sulfone solvent or an aromatic solvent.

[0011] Furthermore, the organic solvent is selected from: alcohol solvents such as methanol or ethanol; ether solvents such as anisole, ethyl ether and 1,4-dioxane; sulfone solvents such as dimethyl sulfoxide; aromatic solvents such as toluene or benzene; halogen-containing polar solvents such as dichloromethane and chloroform; aromatic polar solvents such as xylene, pyridine or chlorobenzene, nitrile solvents such as acetonitrile or propionitrile, and amide solvents such as N,N-dimethylformamide and N,N-dimethylacetamide; preferably pyridine, anisole, chlorobenzene and N,N-dimethylformamide.

[0012] Furthermore, the dosage ratio of the organic solvent to tris(hydroxymethyl)phosphine oxide is 5-8 mL:1 g, that is, the volume of the organic solvent per milliliter is 5-8 times the mass of tris(hydroxymethyl)phosphine oxide in grams.

[0013] Furthermore, the purification treatment is as follows: adding a weak base solution to the reaction system to make the reaction system neutral, then distilling to remove the solvent, then washing and filtering to obtain a filtrate, and finally rotary evaporating and drying to obtain the target product.

[0014] The third technical problem to be solved by the present invention is to point out that the phosphorus-containing diol shown in formula I is used as a flame retardant.

[0015] It is further applied to the preparation of intrinsic flame-retardant polyurethane materials.

[0016] The fourth technical problem to be solved by the present invention is to provide a flame retardant polyurethane material, the raw materials and the proportions of the flame retardant polyurethane material are: 100 parts by weight of phosphorus-containing diol (DTHPO), 50 to 80 parts by weight of diisocyanate, 2 to 3 parts by weight of water, 2.5 to 4 parts by weight of foam stabilizer, 0.2 to 0.4 parts by weight of tertiary amine catalyst, 0.3 to 0.1 parts by weight of tin catalyst, and 4 to 5 parts by weight of cross-linking agent.

[0017] Furthermore, the foam stabilizer is selected from: sulfonated sesame oil alcohol ester, alkyl sulfonate or polydimethylsiloxane-polyoxyalkylene copolymer, preferably polydimethylsiloxane-polyoxyalkylene copolymer.

[0018] Furthermore, the tertiary amine catalyst is selected from: triethylenediamine, N,N-dimethylcyclohexylamine, dimethylbenzylamine, triethanolamine or N,N-dimethylaminoethanol, preferably triethylenediamine.

[0019] Furthermore, the tin catalyst is selected from: diisobutyltin dilaurate (T 12 ) or stannous octoate or stannous oleate, preferably diisobutyltin dilaurate (T 12 ).

[0020] Furthermore, the cross-linking agent is selected from: triethanolamine, diethanolamine or ethanolamine, preferably triethanolamine

[0021] Furthermore, the limiting oxygen index of the intrinsic flame retardant polyurethane material can reach 27%.

[0022] Beneficial effects of the present invention:

[0023] 1. The present invention produces a novel structure phosphorus-containing polyol DTHPO, which has the advantages of neutral pH value, suitable hydroxyl value, good compatibility, etc.

[0024] 2. In the preparation method of DTHPO of the present invention, only a catalytic amount of acid (only 0.2 to 2 mL of acid is added to 1 g of trihydroxymethylphosphine oxide) is used as a catalyst, which has the characteristics of using less materials, cheap and easy to obtain raw materials, simple equipment, easy operation, high yield, easy large-scale conversion and production; it has good environmental and economic benefits and has good industrial application prospects.

[0025] 3. The phosphorus-containing diol prepared by the method of the present invention can not only be used as an organic synthesis intermediate, but also has a wide range of applications due to its excellent thermal stability and high phosphorus content. It is particularly suitable for the preparation of intrinsic flame-retardant polyurethane; the limiting oxygen index of the obtained flame-retardant polyurethane material is 27%. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to further illustrate the structure and performance of the product, the following drawings are given.

[0027] Figure 1 is the NMR spectrum of DTHPO; Figure 1 It shows that when deuterated water is used as solvent, δ4.70 is the H peak of deuterated water solvent, δ3.19-3.18 are the methylene peaks of 4 -OCH2P, and δ2.87-2.86 are the H peaks of 2 methylene peaks of O=P-CH2-OH.

[0028] Figure 2 is the NMR spectrum of DTHPO; Figure 2 It shows that δ25.49 and δ25.42 are the absorption peaks of the two phosphorus atoms on CH2-P=O. DETAILED DESCRIPTION

[0029] The specific implementation modes of the present invention are further described below in conjunction with embodiments, but the present invention is not limited to the scope of the embodiments.

[0030] Embodiment 1:

[0031] Tris(hydroxymethyl)phosphine oxide (0.033 mol, 4.63 g) was added to a 250 mL round-bottom flask with a stirrer, and the water in the tris(hydroxymethyl)phosphine oxide was removed by an oil pump in a water bath at 80°C, and then 1 mL of concentrated sulfuric acid (concentration of 98 wt%) was added dropwise, and finally 30 mL of N,N-dimethylformamide (DMF) was added as an organic solvent. After the tris(hydroxymethyl)phosphine oxide was completely dissolved, the temperature was raised to 120°C and the reaction was continued for 24 hours. After the reaction was completed, it was neutralized with a saturated sodium bicarbonate solution, and then the DMF and water were removed by vacuum distillation, and the mixture was washed with anhydrous ethanol, and the filtrate was filtered to remove the ethanol by rotary evaporation, and dried in a vacuum oven at 60°C to obtain a light yellow liquid with a yield of 94%.

[0032] Embodiment 2:

[0033] Trimethylolphosphine oxide (0.033 mol, 4.63 g) was added to a 250 mL round-bottom flask with a stirrer, and the water in the trimethylolphosphine oxide was removed by an oil pump in a water bath at 80°C, and then 0.5 mL of concentrated sulfuric acid (concentration of 85 wt%) was added dropwise, and finally 30 mL of N,N-dimethylformamide was added as an organic solvent. After the trimethylolphosphine oxide was completely dissolved, the temperature was raised to 120°C and the reaction was continued for 24 hours. After the reaction was completed, it was neutralized with a saturated sodium bicarbonate solution, and then DMF and water were removed by vacuum distillation, washed with anhydrous ethanol, and the filtrate was filtered to remove ethanol by rotary evaporation, and dried in a vacuum oven at 60°C to obtain a light yellow liquid with a yield of 90%.

[0034] Embodiment 3:

[0035] Trimethylolphosphine oxide (0.033 mol, 4.63 g) was added to a 250 mL round-bottom flask with a stirrer, and the water in the trimethylolphosphine oxide was removed by an oil pump in a water bath at 80°C, and then 1 mL of concentrated phosphoric acid was added dropwise, and finally 30 mL of N,N-dimethylformamide was added as an organic solvent. After the trimethylolphosphine oxide was completely dissolved, the temperature was raised to 120°C and the reaction was continued for 24 hours. After the reaction was completed, it was neutralized with a saturated sodium bicarbonate solution, and then DMF and water were removed by vacuum distillation, washed with anhydrous ethanol, and the filtrate was filtered to remove ethanol by rotary evaporation, and dried in a vacuum oven at 60°C to obtain a light yellow liquid with a yield of 84%.

[0036] Embodiment 4:

[0037] Trimethylolphosphine oxide (0.033 mol, 4.63 g) was added to a 250 mL round-bottom flask with a stirrer, and the water in the trimethylolphosphine oxide was removed by an oil pump in a water bath at 80°C, and then 1 mL of concentrated sulfuric acid was added dropwise, and finally 30 mL of toluene was added as an organic solvent. After the trimethylolphosphine oxide was completely dissolved, the temperature was raised to 120°C and the reaction was continued for 24 hours. After the reaction was completed, it was neutralized with a saturated sodium bicarbonate solution, and then toluene and water were removed by vacuum distillation, washed with anhydrous ethanol, and the filtrate was filtered to remove ethanol by rotary evaporation, and dried in a vacuum oven at 60°C to obtain a light yellow liquid with a yield of 87%.

[0038] Embodiment 5:

[0039] Trimethylolphosphine oxide (0.033 mol, 4.63 g) was added to a 250 mL round-bottom flask with a stirrer, and the water in the trimethylolphosphine oxide was removed by an oil pump in a water bath at 80°C, and then 1 mL of concentrated sulfuric acid was added dropwise, and finally 30 mL of N,N-dimethylformamide was added as an organic solvent. After the trimethylolphosphine oxide was completely dissolved, the temperature was raised to 140°C and the reaction was continued for 24 hours. After the reaction was completed, it was neutralized with a saturated sodium bicarbonate solution, and then DMF and water were removed by vacuum distillation, washed with anhydrous ethanol, and the filtrate was filtered to remove ethanol by rotary evaporation, and dried in a vacuum oven at 60°C to obtain a light yellow liquid with a yield of 85%.

[0040] Embodiment 6:

[0041] Trimethylolphosphine oxide (0.033 mol, 4.63 g) was added to a 250 mL round-bottom flask with a stirrer, and the water in the trimethylolphosphine oxide was removed by an oil pump in a water bath at 80°C, and then 1 mL of concentrated sulfuric acid was added dropwise, and finally 30 mL of N,N-dimethylformamide was added as an organic solvent. After the trimethylolphosphine oxide was completely dissolved, the temperature was raised to 120°C and the reaction was continued for 48 hours. After the reaction was completed, the pH value was neutralized with a saturated sodium bicarbonate solution, and then DMF and water were removed by vacuum distillation, washed with anhydrous ethanol, and the filtrate was filtered to remove ethanol by rotary evaporation, and dried in a vacuum oven at 60°C to obtain a light yellow liquid with a yield of 82%.

[0042] Application Example 1:

[0043] Preparation of high resilience polyurethane foam flame retardant material (formula see Table 1): 100g phosphorus-containing polyol DTHPO prepared in Example 1, 2g distilled water (H2O), 4g foam stabilizer (DC-2525), 0.3g amine catalyst (A-1), 0.3g dibutyltin dilaurate (T 12 ) and 4.0g triethanolamine (TEOA) were mixed, mechanically stirred for 4 minutes, and then 64.2g modified diisocyanate (MDI-2412) was added, mechanically stirred for 6 seconds, and then the sample was quickly poured into the mold. After the foam growth is completed, the foam is transferred to a 70°C oven for curing for 2 hours. After curing, the foam is taken out of the mold and cut into 100*10*10cm long foam strips. Finally, the flame retardant material obtained is tested for the limiting oxygen index of the sample with reference to GB / T2406.2-2009 "Plastic Combustion Performance Test Method-Oxygen Index Method".

[0044] Table 1 Formulation of flame retardant polyurethane materials (wt%)

[0045]

[0046] The results show that when the phosphorus-containing polyol DTHPO of the present invention is used in the preparation of intrinsic flame-retardant high-resilience polyurethane foam, its limiting oxygen index has reached a flame-retardant level of 27%; without adding any flame retardant, the limiting oxygen index of the high-resilience polyurethane foam is only 18%, which is in the extremely flammable range; this shows that the intrinsic high-resilience polyurethane foam prepared by the present invention has a good flame retardant effect.

[0047] Comparative Example 1:

[0048] Trimethylolphosphine oxide (0.033 mol, 4.63 g) was added to a 250 mL round-bottom flask containing a stirrer. The water in the trimethylolphosphine oxide was removed by an oil pump in an 80 ° C water bath. Then 10 mL of sulfuric acid was added dropwise. Finally, 30 mL of N, N-dimethylformamide was added as an organic solvent. After the trimethylolphosphine oxide was completely dissolved, the temperature was raised to 140 ° C and the reaction was continued for 24 hours. The target product was not obtained.

[0049] Comparative Example 2:

[0050] Trihydroxymethylphosphine oxide (0.033 mol, 4.63 g) was added to a 250 mL round-bottom flask containing a stirrer. The water in the trihydroxymethylphosphine oxide was removed by an oil pump in an 80 ° C water bath. Then 1 mL of sulfuric acid was added dropwise. Finally, 30 mL of N, N-dimethylformamide was added as an organic solvent. After the trihydroxymethylphosphine oxide was completely dissolved, the temperature was raised to 80 ° C and the reaction was continued for 24 hours. It was also found that the target product was not obtained.

Claims

1. A phosphorus-containing diol, characterized in that The structure of the phosphorus-containing diol is shown in Formula I:

2. The method for preparing the phosphorus-containing diol according to claim 1, characterized in that: The preparation method comprises the following steps: firstly, under the protection of nitrogen or inert gas, stirring and mixing anhydrous trihydroxymethylphosphine oxide, acid and organic solvent; then heating to 100-160° C. for reaction for 2-48 hours; and finally purifying to obtain the phosphorus-containing diol shown in formula I; wherein the dosage ratio of the acid to the trihydroxymethylphosphine oxide is 0.1-2 mL: 1 g.

3. The method for preparing the phosphorus-containing diol according to claim 2, characterized in that: The acid comprises a Bronsted acid; Further, the acid is selected from: concentrated sulfuric acid, concentrated phosphoric acid, nitric acid, formic acid or acetic acid; Furthermore, the mass concentration of the concentrated sulfuric acid is ≥70%, and the mass concentration of the concentrated phosphoric acid is ≥85%.

4. The method for preparing the phosphorus-containing diol according to claim 2 or 3, characterized in that: The organic solvent includes a polar solvent, an alcohol solvent, an ether solvent, a sulfone solvent or an aromatic solvent.

5. The method for preparing the phosphorus-containing diol according to claim 4, characterized in that: The organic solvent is selected from the group consisting of methanol, ethanol, anisole, ethyl ether, 1,4-dioxane, dimethyl sulfoxide, toluene, benzene, dichloromethane, chloroform, xylene, pyridine, chlorobenzene, acetonitrile, propionitrile, N,N-dimethylformamide or N,N-dimethylacetamide; Preferably pyridine, anisole, chlorobenzene or N,N-dimethylformamide; Furthermore, the usage ratio of the organic solvent to trishydroxymethylphosphine oxide is 5-8 mL: 1 g.

6. The method for preparing the phosphorus-containing diol according to any one of claims 2 to 5, characterized in that: The purification treatment comprises the following steps: adding a weak alkaline solution dropwise to the reaction system to make the reaction system neutral, then removing the solvent by distillation, then washing and filtering to obtain a filtrate, and finally rotary evaporating and drying to obtain the target product.

7. Use of a phosphorus-containing diol in a flame retardant, wherein the phosphorus-containing diol is the phosphorus-containing diol according to claim 1; or is the phosphorus-containing diol prepared by the method according to any one of claims 2 to 5.

8. The use of the phosphorus-containing diol in a flame retardant according to claim 7, characterized in that: Used to prepare intrinsic flame retardant polyurethane materials.

9. A flame retardant polyurethane material, characterized in that: The raw materials and proportions of the flame-retardant polyurethane material are: 100 parts by weight of phosphorus-containing diol, 50-80 parts by weight of diisocyanate, 2-3 parts by weight of water, 2.5-4 parts by weight of foam stabilizer, 0.2-0.4 parts by weight of tertiary amine catalyst, 0.3-0.1 parts by weight of tin catalyst, and 4-5 parts by weight of cross-linking agent; wherein the phosphorus-containing diol is the phosphorus-containing diol according to claim 1; or is the phosphorus-containing diol prepared by the method according to any one of claims 2 to 5.

10. The flame retardant polyurethane material according to claim 9, characterized in that: The foam stabilizer is selected from: sulfonated sesame oil alcohol ester, alkyl sulfonate or polydimethylsiloxane-polyoxyalkylene copolymer; Furthermore, the tertiary amine catalyst is selected from: triethylenediamine, N,N-dimethylcyclohexylamine, dimethylbenzylamine, triethanolamine or N,N-dimethylaminoethanol; Furthermore, the tin catalyst is selected from: diisobutyltin dilaurate (T 12 ) or stannous octoate or stannous oleate; Further, the cross-linking agent is selected from: triethanolamine, diethanolamine or ethanolamine; Furthermore, the limiting oxygen index of the intrinsic flame retardant polyurethane material is 27%.

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