A DOPO phosphoramide derivative flame retardant, its preparation method and application in waterborne polyurethane

Abstract

This invention relates to the field of polyurethane, and discloses a DOPO phosphoramide derivative flame retardant, its preparation method, and its application in waterborne polyurethane. The invention uses p-aminophenol as the nitrogen component, introduces a double-terminated hydroxyl structure through a reaction with benzoyl chloride, and then prepares the DOPO phosphoramide derivative via a DOPO reaction. This DOPO phosphoramide derivative is halogen-free, smokeless, non-toxic, and exhibits long-lasting flame retardant properties; simultaneously, it can participate in the synthesis reaction of waterborne polyurethane as a reactive flame retardant, thus demonstrating better stability and less migration within the polyurethane.

Description

Technical Field

[0001] This invention relates to the field of polyurethane, and more particularly to a DOPO phosphoramide derivative flame retardant, its preparation method, and its application in waterborne polyurethane. Background Technology

[0002] Polyurethane (PU), as an important polymer material, is widely used in various fields such as home appliances, automobiles, construction, furniture, and footwear due to its excellent physical and mechanical properties, wear resistance, oil resistance, chemical resistance, ozone resistance, electrical insulation, and good processing performance. However, the flammability of polyurethane is a major hidden danger in its application, especially under high temperature or fire conditions, where polyurethane materials can burn rapidly and release large amounts of toxic gases, posing a great threat to human safety and the environment.

[0003] 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) is a typical phosphorus-containing flame retardant. The biphenyl and phenanthrene ring structures in the DOPO molecule, especially the phosphorus element existing in a cyclic O=PO bond, give it higher chemical and thermal stability. More importantly, DOPO has better flame retardant properties than general acyclic organophosphates.

[0004] Currently, there are few examples of DOPO phosphoramide derivative flame retardants prepared based on DOPO and applied to materials, especially their application in waterborne polyurethanes. Therefore, it is of research significance to prepare DOPO phosphoramide derivative flame retardants applicable to waterborne polyurethanes. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a DOPO phosphoramide derivative flame retardant, its preparation method, and its application in waterborne polyurethane. This invention uses p-aminophenol as the nitrogen component, introducing a double-terminated hydroxyl structure through a reaction with benzoyl chloride, and then preparing the DOPO phosphoramide derivative via a DOPO reaction. This DOPO phosphoramide derivative is halogen-free, smokeless, non-toxic, and exhibits long-lasting flame retardant properties; simultaneously, it can participate in the synthesis reaction of waterborne polyurethane as a reactive flame retardant, thus demonstrating better stability and less migration within the polyurethane.

[0006] The specific technical solution of this invention is as follows:

[0007] First, this invention provides a DOPO phosphoramide derivative flame retardant, the chemical structural formula of which is as follows:

[0008]

[0009] This invention uses p-aminophenol as the nitrogen component, introducing a double-terminated hydroxyl structure through a reaction with benzoyl chloride, and then preparing a DOPO phosphoramide derivative via a DOPO reaction. This DOPO phosphoramide derivative is a novel nitrogen-phosphorus flame retardant. p-Aminophenol has an aniline structure, and the nitrogen atom linked to the benzene ring exhibits stronger flame-retardant properties, showing superior performance compared to alkylamines. However, nitrogen-based flame retardants have poor flame-retardant effects when used alone. Therefore, this invention prepares a DOPO phosphoramide derivative flame retardant (DOPO-MBAP) containing both nitrogen and phosphorus through a series of reactions. The synergistic flame-retardant performance resulting from the direct linkage of the nitrogen and phosphorus elements in this flame retardant is superior to that of unlinked nitrogen and phosphorus elements. Furthermore, it can participate in the synthesis reaction of waterborne polyurethane as a reactive flame retardant, thus exhibiting better stability in polyurethane. This composite flame retardant is halogen-free, smokeless, non-toxic, non-migrating, and has long-lasting flame-retardant properties.

[0010] Secondly, this invention provides a method for preparing the above-mentioned DOPO phosphoramide derivative flame retardant, comprising the following steps:

[0011] Step 1: Using p-aminophenol and methoxybenzoyl chloride as raw materials, the reaction yields methoxybenzoamide p-phenol (MBAP);

[0012] Step 2: Using methoxybenzamide p-phenol as a raw material, react in the presence of AlCl3 and anhydrous ethanethiol, and extract with dichloromethane to obtain the methoxybenzamide p-phenol demethoxylated intermediate;

[0013] Step 3: Using methoxybenzamide p-phenol demethoxyl intermediate and DOPO as raw materials, the DOPO phosphoramide derivative flame retardant (DOPO-MBAP) is obtained after reaction.

[0014] The synthetic route of this invention is shown below:

[0015]

[0016] Preferably, the above preparation method specifically includes:

[0017] Step 1: Add ethyl acetate containing 4-6 ml of triethylamine and 2-4 g of p-aminophenol to a reaction vessel, add 4-6 ml of methoxybenzoyl chloride at 0-5℃, stir the reaction, filter the crude product, wash it, and dry it under vacuum to obtain methoxybenzoamide p-phenol (MBAP).

[0018] Step 2: Add methoxybenzamide p-phenol to dichloromethane containing 30-50 mg AlCl3 and 1-3 ml anhydrous ethanethiol and stir at 0-5 °C. Extract the reaction mixture with dichloromethane, take the organic layer, and dry it under vacuum to obtain the methoxybenzamide p-phenol demethoxylated intermediate.

[0019] Step 3: At 1-10℃, add dichloromethane containing triethylamine to carbon tetrachloride, control the temperature at 10-15℃, add the methoxybenzamide-p-phenol demethoxylated intermediate and DOPO, raise the temperature to 20-30℃ and stir to react; filter the product and evaporate the filtrate under reduced pressure, wash with ethanol, and dry under vacuum to obtain DOPO phosphoramide derivative flame retardant (DOPO-MBAP); the amount of DOPO used is 1-1.3 times the amount reacted with the methoxybenzamide-p-phenol demethoxylated intermediate.

[0020] Preferably, in step 1, the amount of ethyl acetate used is 30-50 ml.

[0021] Preferably, in step 2, the amount of dichloromethane used is 10-30 ml, and dichloromethane is used as a co-solvent and also as an extractant.

[0022] Preferably, in step 2, the reaction time of the stirring reaction is 2-3 hours.

[0023] Preferably, in step 3: the amount of carbon tetrachloride used is 2-3 ml, the amount of triethylamine used is 2-4 ml, and the amount of dichloromethane used is 20-30 mL.

[0024] Preferably, in step 3, the vacuum drying conditions are: 70-90℃, 1-3h.

[0025] Finally, this invention provides the application of the above-mentioned DOPO phosphoramide derivative flame retardant in the preparation of waterborne polyurethane, comprising: dissolving isophorone diisocyanate, polypropylene alcohol, and catalyst in acetone, stirring and reacting at 80-90°C for 0.5-1.5 h, adding DOPO phosphoramide derivative flame retardant, stirring and reacting for 0.5-1.5 h, cooling to 65-75°C, adding 2,2-dimethylolpropionic acid, stirring for 0.5-1.5 h, then cooling to 35-45°C, adding triethylamine, stirring and reacting for 0.5-1.5 h, cooling to room temperature, adding water, stirring and emulsifying for 20-40 min to obtain an emulsion containing waterborne polyurethane.

[0026] Preferably, the amount of isophorone diisocyanate is 5-8g, the amount of polypropylene alcohol is 20-50g, the amount of 2,2-hydroxymethylpropionic acid is 0.5-2g, and the amount of DOPO phosphoramide derivative flame retardant is 0.2-2g.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] This invention uses p-aminophenol as the nitrogen component, and introduces a double-terminated hydroxyl structure through a reaction with benzoyl chloride, followed by a DOPO reaction to prepare a DOPO phosphoramide derivative. This DOPO phosphoramide derivative is halogen-free, smokeless, non-toxic, and exhibits long-lasting flame retardant properties. Furthermore, it can participate in the synthesis of waterborne polyurethane as a reactive flame retardant, thus demonstrating better stability and reduced migration within the polyurethane. Detailed Implementation

[0029] The present invention will be further described below with reference to embodiments.

[0030] Example 1

[0031] 1) Preparation of methoxybenzoamide-p-phenol (MBAP): In a round-bottom flask, a mixture of 3.5 ml of dichloromethane and 3.27 g (0.03 mol) of p-aminophenol was added to a solution dissolved in 30 ml of dichloromethane. Under ice bath conditions, at approximately 0°C, a mixed solution of 4.06 ml (0.03 mol) of methoxybenzoyl chloride dissolved in 10 ml of dichloromethane was slowly added dropwise, with dichloromethane solvent added as needed. The crude product was filtered, washed several times, and dried under vacuum to obtain a white powder.

[0032] 2) Preparation of methoxybenzamide-p-phenol demethoxylated intermediate: 1g of powder obtained in step 1 was added to 20ml of dichloromethane solution containing 0.75g (1.4 equivalents) AlCl3 and stirred at 0℃ for 2.5h. After stirring, the reaction was quenched with dilute hydrochloric acid, and the product was dried by vacuum filtration to obtain the intermediate product.

[0033] 3) Preparation of DOPO-MBAP: The temperature was controlled below 15℃. A mixture of 2.3g of methoxybenzamide-p-phenol demethoxylated intermediate and 1 equivalent of DOPO was added to 50ml of dichloromethane. At 5℃, 0.8ml of carbon tetrachloride was added to a dichloromethane solution containing 40ml of triethylamine. The temperature was then raised to room temperature and stirred overnight. The product was filtered, and the filtrate was evaporated under reduced pressure. The filtrate was washed repeatedly with saturated sodium bicarbonate, deionized water, acetone, and ethanol. Finally, it was dried under vacuum at 80℃ for 2 hours to obtain the final product, DOPO-MBAP.

[0034] 5) Preparation of DOPO-MBAP waterborne polyurethane: Weigh 6.968 g (0.031 mol) isophorone diisocyanate, 30 g (0.01 mol) polypropylene alcohol, three drops of dibutyltin dilaurate, and 0.397 g DOPO-MBAP and dissolve them in 50 ml acetone. Stir and react at 85 °C for 2 h. Then add 1.34 g (0.01 mol) 2,2-dimethylolpropionic acid and lower the temperature to 70 °C, stirring for 1 h. Then lower the temperature to 40 °C, add 1.39 ml (0.01 mol) triethylamine, paying attention to the viscosity of the system and adding acetone as needed, stirring and reacting for 1 h. Then lower to room temperature, add 100 ml deionized water, and emulsify under high-speed stirring for 0.5 h to obtain the waterborne polyurethane emulsion WPU / 1% DOPO-MBAP.

[0035] Example 2

[0036] 1) The preparation of DOPO-MBAP is the same as in Example 1.

[0037] 2) Preparation of DOPO-MBAP waterborne polyurethane: Weigh 8.279 g (0.037 mol) isophorone diisocyanate, 30 g (0.01 mol) polypropylene alcohol, three drops of dibutyltin dilaurate, and 2.139 g DOPO-MBAP and dissolve them in 50 ml acetone. Stir and react at 85 °C for 2 h. Then add 1.34 g (0.01 mol) 2,2-dimethylolpropionic acid and lower the temperature to 70 °C, stirring for 1 h. Then lower the temperature to 40 °C, add 1.39 ml (0.01 mol) triethylamine, paying attention to the viscosity of the system and adding acetone as needed, stirring and reacting for 1 h. Then lower to room temperature, add 100 ml deionized water, and emulsify under high-speed stirring for 0.5 h to obtain the waterborne polyurethane emulsion WPU / 5% DOPO-MBAP.

[0038] Example 3

[0039] 1) The preparation of DOPO-MBAP is the same as in Example 1.

[0040] 2) Preparation of DOPO-MBAP waterborne polyurethane: Weigh 10.230 g (0.046 mol) isophorone diisocyanate, 30 g (0.01 mol) polypropylene alcohol, three drops of dibutyltin dilaurate, and 4.74 g DOPO-MBAP and dissolve them in 50 ml acetone. Stir and react at 85 °C for 2 h. Then add 1.34 g (0.01 mol) 2,2-dimethylolpropionic acid and lower the temperature to 70 °C, stirring for 1 h. Then lower the temperature to 40 °C, add 1.39 ml (0.01 mol) triethylamine, paying attention to the viscosity of the system and adding acetone as needed, stirring and reacting for 1 h. Then lower to room temperature, add 100 ml deionized water, and emulsify under high-speed stirring for 0.5 h to obtain the waterborne polyurethane emulsion WPU / 10% DOPO-MBAP.

[0041] Example 4

[0042] 1) The preparation of DOPO-MBAP is the same as in Example 1.

[0043] 2) Preparation of DOPO-MBAP waterborne polyurethane: Weigh 12.644 g (0.057 mol) isophorone diisocyanate, 30 g (0.01 mol) polypropylene alcohol, three drops of dibutyltin dilaurate, and 7.94 g DOPO-MBAP and dissolve them in 50 ml acetone. Stir and react at 85 °C for 2 h. Then add 1.34 g (0.01 mol) 2,2-dimethylolpropionic acid and lower the temperature to 70 °C, stirring for 1 h. Then lower the temperature to 40 °C, add 1.39 ml (0.01 mol) triethylamine, paying attention to the viscosity of the system and adding acetone as needed, stirring and reacting for 1 h. Then lower to room temperature, add 100 ml deionized water, and emulsify under high-speed stirring for 0.5 h to obtain the waterborne polyurethane emulsion WPU / 10% DOPO-MBAP.

[0044] Comparative Example 1

[0045] Preparation of nitrogen- and phosphorus-free flame retardant waterborne polyurethane: Weigh 6.283 ml (0.03 mol) isophorone diisocyanate, 30 g (0.01 mol) polypropylene alcohol, and three drops of dibutyltin dilaurate and dissolve them in 50 ml of acetone. Stir and react at 85 °C for 2 h. Then add 1.34 g (0.01 mol) 2,2-dimethylolpropionic acid and lower the temperature to 70 °C, stirring for 1 h. Then lower the temperature to 40 °C, add 1.39 ml (0.01 mol) triethylamine, paying attention to the viscosity of the system and adding acetone as needed, stirring and reacting for 1 h. Then lower to room temperature, add 100 ml of deionized water, and emulsify under high-speed stirring for 0.5 h to obtain waterborne polyurethane emulsion WPU.

[0046] Comparative Example 2

[0047] Preparation of nitrogen-containing flame retardant waterborne polyurethane: 9.905 g (0.045 mol) of isophorone diisocyanate, 30 g (0.01 mol) of polypropylene alcohol, three drops of dibutyltin dilaurate, and 2.224 g of MBAP (prepared according to step 1 of Example 1) were weighed and dissolved in 50 ml of acetone. The mixture was stirred at 85 °C for 2 h, then 1.34 g (0.01 mol) of 2,2-dimethylolpropionic acid was added and the temperature was lowered to 70 °C, and stirred for 1 h. The temperature was then lowered to 40 °C, and 1.39 ml (0.01 mol) of triethylamine was added. Acetone was added as needed, and the mixture was stirred for 1 h. The mixture was then cooled to room temperature, and 100 ml of deionized water was added. The mixture was emulsified at high speed for 0.5 h to obtain the waterborne polyurethane emulsion WPU / 5% MBAP.

[0048] Comparative Example 3

[0049] Preparation of nitrogen-containing flame retardant waterborne polyurethane: 14.149 g (0.063 mol) of isophorone diisocyanate, 30 g (0.01 mol) of polypropylene alcohol, three drops of dibutyltin dilaurate, and 2.447 g of p-aminophenol were weighed and dissolved in 50 ml of acetone. The mixture was stirred at 85 °C for 2 h, then 1.34 g (0.01 mol) of 2,2-dimethylolpropionic acid was added and the temperature was lowered to 70 °C, and stirred for 1 h. The temperature was then lowered to 40 °C, and 1.39 ml (0.01 mol) of triethylamine was added. The viscosity of the system was monitored, and acetone was added as needed. The mixture was stirred for 1 h. The mixture was then cooled to room temperature, and 100 ml of deionized water was added. The mixture was emulsified at high speed for 0.5 h to obtain the waterborne polyurethane emulsion WPU / 5% AP.

[0050] Comparative Example 4

[0051] Preparation of waterborne polyurethane containing phosphorus flame retardant: Weigh 6.283 ml (0.03 mol) isophorone diisocyanate, 30 g (0.01 mol) polypropylene alcohol, and three drops of dibutyltin dilaurate and dissolve them in 50 ml acetone. Stir and react at 85 °C for 2 h. Then add 1.34 g (0.01 mol) 2,2-dimethylolpropionic acid and lower the temperature to 70 °C, stirring for 1 h. Then lower the temperature to 40 °C, add 1.39 ml (0.01 mol) triethylamine, paying attention to the viscosity of the system and adding acetone as needed, stirring and reacting for 1 h. Then lower to room temperature, add 1.951 g DOPO dissolved in 10 ml acetone, add 100 ml deionized water, and emulsify under high-speed stirring for 0.5 h to obtain waterborne polyurethane emulsion WPU / 5% DOPO.

[0052] Performance testing

[0053] The performance of the products obtained in each embodiment and comparative example was tested, and the results are shown in the table below:

[0054]

[0055] As shown in the table above, the flame retardant performance of waterborne polyurethane significantly improved after adding the DOPO-MBAP flame retardant of this invention, reaching a V-0 level at 10% DOPO-MBAP, while comparative examples 1, 2, and 3 showed no significant improvement in flame retardant performance. This is because MBAP and AP only introduce an aniline structure, which, on its own, is not an excellent flame retardant and cannot significantly increase the nitrogen content of polyurethane, thus offering little improvement in flame retardant performance. However, waterborne polyurethane with DOPO miscibility benefits from the higher chemical and thermal stability of the biphenyl and phenanthrene rings in the DOPO molecule, especially the phosphorus element present in a cyclic O=PO bond, which enhances flame retardant performance to some extent. Furthermore, after synthesis into DOPO-MBAP, the addition of PN bonds further enhances the synergistic effect of the direct connection between nitrogen and phosphorus elements, improving their respective flame retardant properties. DOPO-MBAP also significantly increases the nitrogen and phosphorus components in the polyurethane, effectively improving the flame retardant performance of waterborne polyurethane.

[0056] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A DOPO phosphoramide derivative flame retardant, characterized in that: The chemical structural formula is as follows:

2. A method for preparing the DOPO phosphoramide derivative flame retardant according to claim 1, characterized in that... Includes the following steps: Step 1: Using p-aminophenol and methoxybenzoyl chloride as raw materials, methoxybenzoamide p-phenol is obtained after reaction; Step 2: Using methoxybenzamide p-phenol as a raw material, react in the presence of AlCl3 and anhydrous ethanethiol, and extract with dichloromethane to obtain the methoxybenzamide p-phenol demethoxylated intermediate; Step 3: Using methoxybenzamide-p-phenol demethoxylated intermediate and DOPO as raw materials, a DOPO phosphoramide derivative flame retardant is obtained after reaction.

3. The preparation method according to claim 2, characterized in that... Specifically, it includes: Step 1: Add ethyl acetate containing 4-6 ml of triethylamine and 2-4 g of p-aminophenol to a reaction vessel, add 4-6 ml of methoxybenzoyl chloride at 0-5℃, stir the reaction, filter and wash the crude product, and dry it under vacuum to obtain methoxybenzoamide p-phenol. Step 2: Add methoxybenzamide p-phenol to dichloromethane containing 30-50 mg AlCl3 and 1-3 ml anhydrous ethanethiol and stir at 0-5 °C. Extract the reaction mixture with dichloromethane, take the organic layer, and dry it under vacuum to obtain the methoxybenzamide p-phenol demethoxylated intermediate. Step 3: At 1-10℃, add dichloromethane containing triethylamine to carbon tetrachloride, control the temperature at 10-15℃, add the methoxybenzamide-p-phenol demethoxylated intermediate and DOPO, raise the temperature to 20-30℃ and stir to react; filter the product and evaporate the filtrate under reduced pressure, wash with ethanol, and dry under vacuum to obtain DOPO phosphoramide derivative flame retardant; the amount of DOPO used is 1-1.3 times the amount reacted with the methoxybenzamide-p-phenol demethoxylated intermediate.

4. The preparation method according to claim 3, characterized in that: In step 1: the amount of ethyl acetate used is 30-50 ml.

5. The preparation method according to claim 3, characterized in that: In step 2: the amount of dichloromethane used is 10-30 ml.

6. The preparation method according to claim 3, characterized in that: In step 2: the reaction time of the stirring reaction is 2-3 hours.

7. The preparation method according to claim 3, characterized in that: In step 3: the amount of carbon tetrachloride used is 2-3 ml, the amount of triethylamine used is 2-4 ml, and the amount of dichloromethane used is 20-30 mL.

8. The preparation method according to claim 3, characterized in that: In step 3, the vacuum drying conditions are: 70-90℃, 1-3h.

9. The application of the DOPO phosphoramide derivative flame retardant as described in claim 1 or the DOPO phosphoramide derivative flame retardant obtained by the preparation method according to any one of claims 2-8 in the preparation of waterborne polyurethane, characterized in that... include: Isophorone diisocyanate, polypropylene alcohol, and catalyst were dissolved in acetone and reacted with stirring at 80-90°C. DOPO phosphoramide derivative flame retardant was added and the mixture was stirred. The temperature was lowered to 65-75°C, 2,2-dimethylolpropionic acid was added, and the mixture was stirred. The temperature was then lowered to 35-45°C, triethylamine was added, and the mixture was stirred. The mixture was cooled to room temperature, water was added, and the mixture was stirred to emulsify, thus obtaining an emulsion containing waterborne polyurethane.

10. The application according to claim 9, characterized in that: The amount of isophorone diisocyanate used is 5-8g, the amount of polypropylene alcohol used is 20-50g, the amount of 2,2-hydroxymethylpropionic acid used is 0.5-2g, and the amount of DOPO phosphoramide derivative flame retardant used is 0.2-2g.

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