Barium-containing DOPO-derived flame retardants for flame retardant polyamides and methods thereof

Abstract

The invention discloses a barium-containing DOPO-derived flame retardant and a preparation method and application thereof. The method is to add itaconic acid and 1,6-hexamethylenediamine HMDA to a solvent in an inert gas atmosphere for salt reaction, then gradually add DOPO and keep it for several hours, then add barium hydroxide for reaction for several hours, and filter the obtained filtrate into a crystallization dish for crystallization, wash the crystals after crystallization with an organic solvent at least three times, and then dry to obtain a light pink block, and finally grind to obtain a final product of light yellow powder. The present invention adopts a three-step feeding and one-pot method, has a simple synthesis process, is halogen-free and formaldehyde-free in the structure, is environmentally friendly and pollution-free, and has low raw material prices and is suitable for industrial production, solves the problems of poor durability and severe strength loss of flame retardant materials, and can effectively improve the molecular weight of flame retardant polyamide after polymerization and the flame retardant properties of polyamide materials.

Description

Technical Field

[0001] The present invention relates to a flame retardant and a preparation method thereof in the technical field of flame retardant synthesis, and in particular to a barium-containing DOPO derivative flame retardant for flame retardant polyamide and a preparation method thereof. Background Art

[0002] Nylon is the trade name of polyamide, abbreviated as PA in English. Nylon has the advantages of light weight, wear resistance, and high impact toughness. It can be used as mechanical parts such as gears and bearings in the fields of construction, automobile industry, and aviation. It can be made into nylon fibers in the textile field. Nylon material is a flammable material. The molten droplets and thick smoke produced during its combustion will accelerate the spread of the fire in the event of a fire, reduce the survival rate of people at the fire scene, and bring great safety hazards to production and life.

[0003] The modification methods of nylon are divided into blending modification and copolymerization modification according to the principle. The blending method is to melt the additive flame retardant and nylon masterbatch at high temperature and mix them for extrusion and pelletization. The process is simple, the cost is low, the failure rate is low, and it meets the needs of large-scale production. However, there are also insurmountable shortcomings, such as the flame retardant cannot be well dispersed in the polymer, the flame retardant effect of the copolymer flame retardant polyamide finished product is general, the flame retardant durability is poor, the required amount of flame retardant addition is high, and the mechanical properties of the material are seriously reduced.

[0004] The copolymerization method is to involve reactive flame retardants in the polymerization reaction of nylon, and add elements that provide flame retardant effects such as nitrogen, phosphorus, metal hydroxides, etc. to the macromolecular chain of nylon. The copolymer flame retardant nylon material can have the advantages of good flame retardant effect and long-lasting flame retardancy with less addition of flame retardants.

[0005] Phosphorus flame retardants are one of the main flame retardants currently used to flame retard nylon 66. Compared with other flame retardants such as halogen flame retardants, they have advantages such as low toxicity and low smoke. Compared with inorganic phosphorus flame retardants, organophosphorus flame retardants have advantages such as good dispersibility and small addition amount. Organophosphorus flame retardants themselves have advantages such as high flame retardancy.

[0006] The current mainstream phosphorus-based reactive flame retardants have achieved ideal results in terms of flame retardant effect and addition amount control, but there are still problems such as insufficient reactivity of flame retardants and low molecular weight of the prepared copolymer flame retardant polyamide. The small molecular weight of the prepared flame retardant polyamide will lead to problems such as spinning difficulties and poor mechanical properties of the products. To solve this problem, it is necessary to add a solid phase viscosity enhancement process, which increases production time and economic costs.

[0007] Chinese patents (publication numbers CN 112048061 A, CN 112144141 A) and other invention patents have proposed that DDP (DOPO derivatives) reactive phosphorus-containing flame retardants have problems such as low molecular weight of copolymerized flame-retardant polyamide after polymerization (relative viscosity of about 1.8) and the need to add a solid phase polycondensation step to increase the molecular weight to produce polyamide plastics or fiber products with better mechanical properties. Summary of the invention

[0008] In order to solve the above technical problems, the present invention discloses a barium-containing DOPO-derived flame retardant for flame-retardant polyamide and a preparation method thereof. The novel DOPO-derived flame retardant is halogen-free and environmentally friendly. The flame retardant can be added to polyamide in the form of blending or copolymerization. The flame-retardant polyamide produced has the advantages of large molecular weight, excellent mechanical properties, good flame retardancy, and lasting flame retardant effect.

[0009] To achieve the above object, the present invention adopts the following technical solutions:

[0010] 1. A barium-containing DOPO-derived flame retardant for flame-retardant polyamide, wherein the molecular structure of the flame retardant is:

[0011]

[0012] 2. The preparation method of the barium-containing DOPO-derived flame retardant according to claim 1, wherein the synthetic route of the preparation method is as follows:

[0013]

[0014] The method specifically comprises the following steps:

[0015] (1) in an inert gas atmosphere, adding a certain proportion of itaconic acid and 1,6-hexamethylenediamine HMDA into a solvent, so that itaconic acid reacts with 1,6-hexamethylenediamine HMDA in the solvent to form a salt, thereby obtaining an itaconic acid-hexamethylenediamine ITA-HMDA aqueous solution;

[0016] (2) When itaconic acid is completely dissolved, DOPO is gradually added to the aqueous solution of itaconic acid hexamethylenediamine ITA-HMDA, and the reaction is continued for several hours to obtain a water-soluble flame retardant DDP-HMDA;

[0017] (3) A certain proportion of barium hydroxide is added to the water-soluble flame retardant DDP-HMDA, the reaction is continued for several hours, and the filtrate is filtered at a certain temperature. The filtrate obtained by the filtration is placed in a crystallization dish for crystallization. The crystals after crystallization are washed at least three times with an organic solvent, and then dried to obtain a light pink block. Finally, the final product is ground to obtain a light yellow powder as a barium-containing DOPO-derived flame retardant.

[0018] In the steps (1) to (3), the solvent selected is one of ethanol and deionized water.

[0019] In the step (2), half of the mass of DOPO is added at the beginning of the reaction, and the other half of the mass of DOPO is added within 30 minutes thereafter.

[0020] In the step (3), the washing solvent is one or more of toluene, ethanol, and isopropanol.

[0021] In the step (1), the molar ratio of itaconic acid to hexamethylenediamine is 1:1. After the itaconic acid and 1,6-hexamethylenediamine HMDA are added dropwise, the mixture is heated to 60-90° C. in a water bath, stirred at 40-60 r / min, and reacted for 0.5-1.5 h under the conditions of nitrogen atmosphere protection.

[0022] In the step (2), the molar ratio of ITA-HMDA to DOPO is 1:1, and the reaction time is 2.0 to 3.0 hours.

[0023] In the step (3), the molar ratio of the flame retardant (DDP-HMDA) aqueous solution to Ba(OH)2 is 1:1.5, the reaction time is 2.0-3.0 hours, the filtration temperature is 80°C, and the grinding fineness is not less than 800 mesh.

[0024] The DOPO described in the present invention refers to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

[0025] The barium-containing DOPO derivative flame retardant of the present invention has a structural formula as shown in Formula I. In order to prepare the reactive flame retardant simply and efficiently, the present invention adopts a water bath heating method to react 1,6-hexanediamine (HMDA) with itaconic acid (ITA) to generate HMDA-ITA, and then adds 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) to react to generate [(6-oxo-6H-dibenzo[c,e][1,2]oxaphosphahexane-6-yl)methyl]succinic acid-hexanediamine (DDP-HMDA), and finally adds barium hydroxide (Ba(OH)2) to prepare a novel DOPO derivative flame retardant.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The invention discloses a barium-containing DOPO-derived flame retardant which is halogen-free and environmentally friendly. The flame retardant can be added to polyamide in the form of blending or copolymerization. The produced flame-retardant polyamide has the advantages of large molecular weight, good mechanical properties, good flame retardancy, and lasting flame retardancy, and meets the requirements of further industrial production such as injection molding, extrusion and spinning.

[0028] The flame retardant of the present invention adopts a three-step feeding and one-pot method, has a simple synthesis process, is halogen-free and formaldehyde-free in the structure, is environmentally friendly and pollution-free, and has low raw material prices, making it suitable for industrial production. The new DOPO-derived flame retardant has good reactivity, solves the problems of poor durability and severe strength loss of flame retardant materials, and can effectively improve the molecular weight, mechanical properties and flame retardant properties of flame retardant polyamide after polymerization. DETAILED DESCRIPTION

[0029] The technical solution will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] The embodiments of the present invention are divided into a DDP flame retardant preparation embodiment, a DOPO derivative flame retardant preparation embodiment of the present invention, and a flame retardant nylon 66 preparation embodiment, which are as follows:

[0031] DDP flame retardant preparation example:

[0032] Embodiment 1

[0033] Add itaconic acid into a three-necked flask with a stirrer, a condenser reflux and nitrogen, stir to make itaconic acid completely dissolved in deionized water, gradually add 1,6-hexanediamine (HMDA), the molar ratio of itaconic acid to hexanediamine is 1:1, after the addition is completed, the water bath is heated to 60°C, the stirring speed is 40r / min, and the reaction is carried out for 0.5h under the conditions of nitrogen atmosphere protection to obtain ITA-HMDA aqueous solution, DOPO is added to the ITA-HMDA aqueous solution, the molar ratio of ITA-HMDA to DOPO is 1:1, keep the temperature, speed and nitrogen atmosphere conditions of the previous step unchanged, continue to react for 2.0h, keep above 70°C for suction filtration, cool and recrystallize, wash with ethanol, dry in a vacuum oven at 60°C for 12 hours, take out and grind to 800 mesh, and sieve to obtain a white powder product water-soluble flame retardant (DDP-HMDA).

[0034] Embodiment 2

[0035] Add itaconic acid into a three-necked flask with a stirrer, a condenser reflux and nitrogen, stir to make itaconic acid completely dissolved in deionized water, gradually add 1,6-hexanediamine (HMDA), the molar ratio of itaconic acid to hexanediamine is 1:1, after the addition is completed, the water bath is heated to 75°C, the stirring speed is 60r / min, and the reaction is carried out for 1h under the protection of nitrogen atmosphere to obtain ITA-HMDA aqueous solution, DOPO is added to the ITA-HMDA aqueous solution, the molar ratio of ITA-HMDA to DOPO is 1:1, keep the temperature, speed and nitrogen atmosphere conditions of the previous step unchanged, continue to react for 2.5h, keep above 70°C for suction filtration, cool and recrystallize, wash with ethanol, dry in a vacuum oven at 60°C for 12 hours, take out and grind to 800 mesh, and sieve to obtain a white powder product water-soluble flame retardant (DDP-HMDA).

[0036] Embodiment 3

[0037] Add itaconic acid into a three-necked flask with a stirrer, a condenser reflux and nitrogen, stir to make itaconic acid completely dissolved in ethanol, gradually add 1,6-hexanediamine (HMDA), the molar ratio of itaconic acid to hexanediamine is 1:1, after the addition is completed, the water bath is heated to 90°C, the stirring speed is 80r / min, and the reaction is carried out for 1.5 hours under the protection of nitrogen atmosphere to obtain ITA-HMDA aqueous solution, DOPO is added to the ITA-HMDA aqueous solution, the molar ratio of ITA-HMDA to DOPO is 1:1, keep the temperature, speed and nitrogen atmosphere conditions of the previous step unchanged, continue to react for 3.0 hours, maintain above 70°C for suction filtration, cool and recrystallize, wash with ethanol, dry in a vacuum oven at 60°C for 12 hours, take out and grind to 800 mesh, and sieve to obtain a white powder product water-soluble flame retardant (DDP-HMDA).

[0038] Preparation Example of Novel DOPO-derived Flame Retardant

[0039] Embodiment 4

[0040] Take the flame retardant (DDP-HMDA) in Example 1, deionized water as a solvent, add Ba(OH)2, the molar ratio of the flame retardant (DDP-HMDA) aqueous solution to Ba(OH)2 is 1:1.5, the water bath temperature is raised to 80°C, the stirring speed is 40r / min and the reaction is continued for 3.0h. The solution obtained by the reaction is filtered at 80°C, the filtrate is taken, the bottle is left to stand, and the temperature is cooled to room temperature, and then the filtration bottle containing the flame retardant filtrate is placed in an ice water bath for 12.0h, the solution containing crystals is filtered, dissolved with deionized water and recrystallized 5 times, and finally dried to obtain a new DOPO-derived flame retardant.

[0041] Embodiment 5

[0042] Take the flame retardant (DDP-HMDA) in Example 2, deionized water as a solvent, add Ba(OH)2, the molar ratio of the flame retardant (DDP-HMDA) aqueous solution to Ba(OH)2 is 1:1.5, the water bath temperature is raised to 85°C, the stirring speed is 60r / min, and the reaction is continued for 3.0h. The solution obtained by the reaction is filtered at 80°C, the filtrate is taken, the bottle is left to stand, and the temperature is cooled to room temperature, and then the filtration bottle containing the flame retardant filtrate is placed in an ice water bath for 12.0h, the solution containing the crystals is filtered, dissolved with deionized water and recrystallized 5 times, and finally dried to obtain a new DOPO-derived flame retardant.

[0043] Embodiment 6

[0044] Take the flame retardant (DDP-HMDA) in Example 3, deionized water as solvent, add Ba(OH)2, the molar ratio of the flame retardant (DDP-HMDA) aqueous solution to Ba(OH)2 is 1:1.5, the water bath temperature is raised to 90°C, the stirring speed is 80r / min and the reaction is continued for 3.0h. The solution obtained by the reaction is filtered at 80°C, the filtrate is taken, the bottle is left to stand, and the temperature is cooled to room temperature, and then the filtration bottle containing the flame retardant filtrate is placed in an ice water bath for 12.0h, the solution containing crystals is filtered, dissolved with deionized water and recrystallized 5 times, and finally dried to obtain a new DOPO-derived flame retardant.

[0045] Preparation Example of Flame Retardant Nylon 66

[0046] Embodiment 7

[0047] The flame retardant (DDP-HMDA) prepared in Example 1 was manually ground to 800 mesh and sieved to remove impurities. Nylon 66 salt and flame retardant (DDP-HMDA) powder were added to a small polymerization reactor, and the flame retardant (DDP-HMDA) accounted for 4wt% of the total reactants. After the reaction was completed, the pellets were cut into reactive flame-retardant nylon 66, which were injection molded into standard specimens by a flat vulcanizer for testing.

[0048] Embodiment 8

[0049] The new DOPO-derived flame retardant prepared in Example 4 was manually ground to 800 mesh and sieved to remove impurities. Nylon 66 salt and new DOPO-derived flame retardant powder were added to a small polymerization reactor, and the new DOPO-derived flame retardant accounted for 2wt% of the total reactants. After the reaction was completed, the pellets were cut into reactive flame-retardant nylon 66, which were injection-molded into standard specimens by a flat vulcanizer for testing.

[0050] Embodiment 9

[0051] The new DOPO-derived flame retardant prepared in Example 5 was manually ground to 800 mesh and sieved to remove impurities. Nylon 66 salt and new DOPO-derived flame retardant powder were added to a small polymerization reactor, and the new DOPO-derived flame retardant accounted for 4wt% of the total reactants. After the reaction was completed, the pellets were cut into reactive flame-retardant nylon 66, which were injection-molded into standard specimens by a flat vulcanizer for testing.

[0052] Embodiment 10

[0053] The new DOPO-derived flame retardant prepared in Example 6 was manually ground to 800 mesh and sieved to remove impurities. Nylon 66 salt and new DOPO-derived flame retardant powder were added to a small polymerization reactor, and the new DOPO-derived flame retardant accounted for 6wt% of the total reactants. After the reaction was completed, the pellets were cut into reactive flame-retardant nylon 66, which were injection-molded into standard specimens by a flat vulcanizer for testing.

[0054] Table 1 Comparison of properties of flame retardant copolymer polyamide and pure polyamide

[0055]

[0056] The control group experiment in Table 1 above proves that the present invention improves the performance of DDP flame retardant. By comparing the addition of the same content of DDP and the new DOPO-derived flame retardant, the new DOPO-derived flame retardant can increase the flame retardant performance without losing much physical and mechanical properties. In terms of viscosity, the addition of DDP will cause the viscosity of nylon 66 to decrease, and the molecular weight cannot meet the requirements of spinning. The nylon added with the new DOPO-derived flame retardant can reach a relative viscosity of more than 2.6 between 0% and 6wt%, which can fully meet the requirements of spinning and meet the needs of industrial production.

[0057] In summary, the present invention synthesizes a new barium-containing DOPO derivative flame retardant based on the structural design of the traditional flame retardant DDP, fully absorbs the flame retardant advantages of the DDP flame retardant, greatly improves the reactivity of the DDP flame retardant, and the new barium-containing DOPO derivative flame retardant has excellent reactivity and good water solubility, which has been verified in nylon 66 and meets the needs of industrial production. It provides a new idea for the modification of nylon 66 materials.

[0058] To sum up, the above are only preferred specific implementation modes of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A barium-containing DOPO-derived flame retardant for flame-retardant polyamide, characterized in that: The flame retardant molecular structure formula is:

2. The method for preparing the barium-containing DOPO-derived flame retardant according to claim 1, characterized in that: The synthetic route of the preparation method is as follows:

3. A method for preparing the barium-containing DOPO-derived flame retardant according to claim 1, characterized in that: The method specifically comprises the following steps: (1) in an inert gas atmosphere, adding a certain proportion of itaconic acid and 1,6-hexamethylenediamine HMDA into a solvent, so that itaconic acid reacts with 1,6-hexamethylenediamine HMDA in the solvent to form a salt, thereby obtaining itaconic acid hexamethylenediamine ITA-HMDA; (2) When itaconic acid is completely dissolved, DOPO is gradually added to itaconic acid hexamethylenediamine ITA-HMDA, and the reaction is continued for several hours to obtain a water-soluble flame retardant DDP-HMDA; (3) A certain proportion of barium hydroxide is added to the water-soluble flame retardant DDP-HMDA, the reaction is continued for several hours, and the filtrate is filtered at a certain temperature. The filtrate obtained by the filtration is placed in a crystallization dish for crystallization. The crystals after crystallization are washed at least three times with an organic solvent, and then dried to obtain a light pink block. Finally, the final product is ground to obtain a light yellow powder as a barium-containing DOPO-derived flame retardant.

4. A preparation method according to claim 3, characterized in that: In the step (2), half of the mass of DOPO is added at the beginning of the reaction, and the other half of the mass of DOPO is added within 30 minutes thereafter.

5. A preparation method according to claim 3, characterized in that: In the step (1), the molar ratio of itaconic acid to hexamethylenediamine is 1:

1. After the itaconic acid and 1,6-hexamethylenediamine HMDA are added dropwise, the mixture is heated to 60-90° C. in a water bath, stirred at 40-60 r / min, and reacted for 0.5-1.5 h under the conditions of nitrogen atmosphere protection.

6. A preparation method according to claim 3, characterized in that: In the step (2), the molar ratio of ITA-HMDA to DOPO is 1:1, and the reaction time is 2.0 to 3.0 hours.

7. A preparation method according to claim 3, characterized in that: In the step (3), the molar ratio of the flame retardant DDP-HMDA aqueous solution to Ba(OH)2 is 1:1.5, the reaction time is 2.0-3.0 hours, the filtration temperature is 80°C, and the grinding fineness is not less than 800 mesh.

8. Use of the DOPO-derived flame retardant as claimed in claim 1 in flame retardant polyamide.

Images