CN109054081B - Nitrogen-phosphorus synergistic flame retardant and preparation method thereof - Google Patents
Nitrogen-phosphorus synergistic flame retardant and preparation method thereof Download PDFInfo
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- CN109054081B CN109054081B CN201810612912.2A CN201810612912A CN109054081B CN 109054081 B CN109054081 B CN 109054081B CN 201810612912 A CN201810612912 A CN 201810612912A CN 109054081 B CN109054081 B CN 109054081B
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- C07D251/26—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings having three double bonds between ring members or between ring members and non-ring members with only hetero atoms directly attached to ring carbon atoms
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Abstract
The invention discloses a nitrogen-phosphorus synergistic flame retardant and a preparation method thereof, wherein the existing flame retardant is unbalanced in phosphorus-nitrogen content ratio, and the flame retardant performance of the flame retardant when the flame retardant is used independently is influenced, so that the addition amount of the flame retardant is increased, and the nitrogen-phosphorus synergistic flame retardant is prepared by the following steps: (1) the melamine and the urea react in equipment with temperature control and mixing functions under the conditions of heating and stirring, the reaction temperature is between 160 and 220 ℃, and the reaction time is 1 to 2 hours; (2) adding polyphosphoric acid and ammonium phosphate into the product obtained in the step (1), controlling the reaction temperature to be 240-300 ℃, reacting for 1-3 hours, and cooling to obtain a nitrogen-phosphorus synergistic flame retardant finished product. The flame retardant has good thermal stability and adjustable phosphorus and nitrogen content, so that the flame retardant can show the best phosphorus and nitrogen synergistic flame retardant performance in different polymers. Short technological process, simple and safe operation, high raw material yield and easy realization of industrialization.
Description
Technical Field
The invention belongs to the technical field of chemical industry, and relates to a nitrogen-phosphorus synergistic flame retardant and a preparation method thereof.
Background
Although the traditional halogen flame retardant is widely applied due to the excellent flame retardant efficiency, the high polymer using the traditional halogen flame retardant can generate a large amount of smoke and toxic and corrosive hydrogen halide gas when the high polymer is on fire, thereby causing damage to the environment and the life safety of people. And the high polymer containing the halogen flame retardant can generate carcinogenic dioxin in the subsequent recycling process, thereby causing pollution to the environment. Therefore, while the use of halogen-based flame retardants is restricted by several orders such as WEEE and ROHS, which are issued in our country, the use of halogen-based flame retardants is also restricted by the "pollution control and management method for electronic information products". The requirement that the flame retardant be non-halogenated is becoming more stringent. The phosphorus-nitrogen flame retardant shows good flame retardant performance based on the synergistic effect of phosphorus and nitrogen, and has the advantages of environmental friendliness, low smoke, low toxicity and the like, and becomes one of research hotspots.
The content of phosphorus and nitrogen in the flame retardant has direct influence on the flame retardant performance, and the reasonable proportion of the content of phosphorus and nitrogen can play a role in the synergy of phosphorus and nitrogen. The most widely used phosphorus-nitrogen synergistic flame retardant is long-chain ammonium polyphosphate (APP II type) and melamine polyphosphate (MPP). However, the theoretical phosphorus content of ammonium polyphosphate is about 32 percent, the nitrogen content is about 14 percent, and the ammonium polyphosphate is low in nitrogen and high in phosphorus; the theoretical phosphorus content in the polyphosphoric acid melamine salt is 15 percent, the nitrogen content is 41 percent, and the polyphosphoric acid melamine salt is high in nitrogen and low in phosphorus. The ratio imbalance of the phosphorus and nitrogen contents affects the flame retardant property when the flame retardant is used alone, so that the addition amount of the flame retardant is increased, the mechanical property and the like of the polymer are affected, and the application range of the flame retardant is limited. And the APP is low in decomposition temperature and poor in thermal stability, so that the APP is mainly suitable for flame retardance of low-processing-temperature polymers such as polyethylene, polypropylene, polyurethane and epoxy resin, but cannot be used for polymers with high processing temperatures such as PA, and the application range of the APP is greatly limited. In the literature, "Yunyan Xiang et al, the research on the combustion behavior and thermal cracking of polyphosphate melamine-based intumescent flame retardant PA6, Chinese plastics, 2003,17 (11): 61-64' adopts MPP or MPP to form the flame retardant PA6, when the MPP addition amount is 25%, the flame retardant grade only reaches UL 94V-1 grade. Therefore, APP and MPP are mostly compounded with other flame retardants at the present stage, so that the optimal flame retardant effect is achieved. The document "li lizhan, lujiangxin, etc., flame retardant property of APP/MPP/PER flame retardant pure cotton fabric, proceedings of tianjin university of industry, volume 30, phase 2, 2011: 54-56' introduction to flame retardant property comparison of flame retardant property of cotton fabric by APP and APP/MPP, the result shows that when the ratio of APP/MPP is 10:7, the flame retardant property is better than that of simple APP, and the phosphorus and nitrogen content is 25% and 30.5% respectively. In US4966931 melamine modified ammonium polyphosphate and melamine are described as flame retardants for flame retarding polypropylene or polyethylene as selective agents. CN01128575 introduces a halogen-free expansion type flame retardant of polyolefin prepared by compounding pentaerythritol phosphate and melamine polyphosphate.
Because the proportional relation of the phosphorus and nitrogen contents of the APP and MPP flame retardant monomers cannot well play the synergistic effect of the phosphorus and nitrogen. And if the APP and the MPP are mixed to obtain the better phosphorus and nitrogen content, the APP is limited to be extremely limited in application range due to poor thermal stability. The preparation of flame retardants with reasonable phosphorus-nitrogen content ratios is also one of the research hotspots. Chinese patent CN200510049426.7 proposes the preparation of a compound having a hydroxyl group, using phosphorus pentoxide, ammonium dihydrogen phosphate, melamine or morpholine, piperazine or alkyl hydroxyl-containing polyamine
Wherein M is melamine group or morpholine group or piperidine group or piperazine group or alkyl hydroxyl-containing polyamine group, etc. The n + m is more than 1000, however, from the description of the preparation process and the examples, the essence is to prepare a flame retardant material with a reasonable phosphorus-nitrogen ratio or expansion performance, thereby improving the related flame retardant performance of the polyphosphate.
Disclosure of Invention
Aiming at the defect of inconsistent phosphorus-nitrogen content ratio in phosphorus-nitrogen flame retardants such as APP, MPP and the like, the invention provides a phosphorus-nitrogen synergistic flame retardant with adjustable phosphorus-nitrogen content ratio and stronger polymer adaptability and a preparation technology thereof.
In order to achieve the purpose, the invention adopts the following technical means: the nitrogen-phosphorus synergistic flame retardant has the following molecular formula:
(NH4)xM(1-x)PO3
wherein M represents melamine and x is between 0 and 1.
The nitrogen-phosphorus synergistic flame retardant is prepared by the following steps:
(1) the melamine and the urea react in equipment with temperature control and mixing functions under the conditions of heating and stirring, the reaction temperature is controlled between 160 ℃ and 220 ℃, and the reaction time is 1-2 hours;
(2) in equipment with temperature control and mixing functions, adding polyphosphoric acid and ammonium phosphate obtained in the step (3) into the product obtained in the step (1) under the conditions of heating and stirring, controlling the reaction temperature to be 240-300 ℃, reacting for 1-3 hours, and cooling to obtain a nitrogen-phosphorus synergistic flame retardant finished product;
(3) and (3) absorbing the ammonia gas overflowing in the reaction processes of the steps (1) and (2) by using phosphoric acid to obtain ammonium phosphate, and adding the ammonium phosphate serving as a reaction raw material into the reaction of the step (2).
In the present invention, the equipment with temperature control and mixing functions can be a ribbon mixer, an internal mixer, a kneader or the like.
In the reaction of the step (1), the molar ratio of urea to melamine is 1:1-4:1, the molar ratio of polyphosphoric acid and ammonium phosphate salt added in the step (2) is 1:1-3:1, and serial products with different nitrogen and phosphorus contents can be obtained by adjusting the ratio of melamine to urea and the ratio of ammonium phosphate salt added in the step (2).
In the invention, the concentration of the polyphosphoric acid added in the step (2) is 105-110%. The high concentration of polyphosphoric acid is beneficial to the reaction and the quality of a final finished product, but the polyphosphoric acid is difficult to prepare and high in price, so that the economical efficiency of the process is reduced; the polyphosphoric acid concentration is too low, the corrosion of equipment is increased due to the existence of free phosphoric acid in the reaction process, more water needs to be removed in the polymerization of a finished product, the energy consumption is increased, the polymerization degree of the obtained final product is lower, the pH value is reduced, the solubility is increased, and the flame retardant property is poorer.
In the present invention, the reaction temperature of the step (1) is 160-220 ℃, preferably 180-200 ℃, and the reaction time is 1-2 hours, preferably 1-1.5 hours. The reaction temperature in the step (2) is 240-300 ℃, preferably 280-300 ℃, and the reaction time is 1-3 hours, preferably 2-3 hours. The temperature is lower, the polymerization degree of the finished product is low, and the flame retardant property is reduced; the ammonia gas is decomposed from the finished product at an over-high temperature, so that the nitrogen content of the finished product is reduced, and the flame retardant property is reduced. The reaction time is short, the polymerization degree is low, and the flame retardance is reduced; the reaction time is long, the finished product is decomposed, ammonia gas overflows, and the nitrogen content and the flame retardant property of the finished product are reduced.
The phosphorus-nitrogen synergistic flame retardant disclosed by the invention has good thermal stability and adjustable phosphorus-nitrogen content, so that the phosphorus-nitrogen synergistic flame retardant can show the optimal phosphorus-nitrogen synergistic flame retardant performance in different polymers. Short technological process, simple and safe operation, high raw material yield and easy realization of industrialization.
Drawings
FIG. 1 shows a process for preparing a flame retardant according to the present invention.
Detailed Description
The invention has been described in detail with reference to specific embodiments thereof, and it is intended that the specific details described herein be interpreted as exemplary only and within the scope of the appended claims.
All the steps (2) of the embodiment are carried out in a 20-liter kneader with a jacket, the jacket is heated by adopting heat conducting oil, and a temperature detection display device is arranged; the kneader is cooled by adopting an indirect cooling mode of cooling heat-conducting oil. And pressurizing reaction overflow gas by a Roots blower, absorbing the reaction overflow gas by two absorbers which are connected in series and are filled with phosphoric acid solution, wherein the bottoms of the absorbers are provided with phosphate ammonium salt discharge outlets, emptying, concentrating and crystallizing absorption liquid to obtain phosphate ammonium salt, and mixing crystallization mother liquor and phosphoric acid to obtain absorption liquid.
The following raw materials were used in all examples:
urea, yunnan chemical company limited, with a total nitrogen content of not less than 46.4%.
Melamine, Sichuan gold elephant chemical Co., Ltd., content 99.8%.
Industrial phosphoric acid, produced by Yunnan Jiang phosphorus group GmbH, with a concentration of 85%.
The polyphosphoric acid is prepared by phosphorus pentoxide and industrial phosphoric acid which are produced by Yunnan JiangPho group Limited company, and the concentrations of the polyphosphoric acid are respectively 105 percent and 110 percent.
The method for analyzing the components of the phosphorus-nitrogen synergistic flame retardant of the final product obtained in the embodiment comprises the following steps:
accurately weighing 2 g of the final product, accurately weighing to 0.0002 g, placing the final product in a 100 ml beaker, adding 20 ml of distilled water and 5 ml of perchloric acid, heating the sample until the excessive perchloric acid is removed after the sample is completely dissolved, cooling the sample, transferring the sample to a 500 ml volumetric flask, adding 10 ml of hydrochloric acid, diluting the sample with water to a scale, and shaking the sample uniformly. The method is used for measuring the content of phosphorus and nitrogen in the product.
The analysis of the phosphorus content in the final product comprises the steps of transferring 10 ml of sample solution, and analyzing according to a method specified in the general method for measuring the content of phosphorus pentoxide in inorganic chemical products (GB/T23843-2009);
and (3) analyzing the nitrogen content in the final product, namely transferring 100 ml of sample liquid, and analyzing according to a method specified in general method distillation-acid-base titration method for measuring the total nitrogen content in inorganic chemical products (GB/T23952-.
In the embodiment, the physical and chemical indexes of the final product are analyzed:
and (3) measuring the pH value, namely accurately weighing 10.0 g of the final product in a 200 ml beaker, adding 90 ml of distilled water, stirring for 30 minutes, and measuring the pH value by using a PHSJ-4A type laboratory pH meter produced by Shanghai apparatus and electronic science instruments, Inc.
Water solubility analysis 10.0 g of the final powder product in the examples was placed in a 200 ml beaker, 90 g of distilled water was added, stirred at room temperature for 30 minutes, filtered through a pre-dried, constant weight No. 4 sand core funnel, dried, weighed and the solubility calculated.
Measurement of thermal decomposition temperature: about 10 mg of the final product is put in a crucible, and the temperature is increased from room temperature to 700 ℃ in the air environment by adopting an HTG-1 type microcomputer differential thermal balance produced by Beijing Hengjiu scientific instrument factory for measurement. The thermal stability of the product was judged as the temperature at which 2% weight loss occurred.
Example 1
2400 g of urea and 2520 g of melamine are put into a kneader, heated to 180 ℃ under the stirring condition, reacted for 1.5 hours, added with 7127 g of polyphosphoric acid with the concentration of 110%, heated to 280 ℃, reacted for 2.5 hours, and cooled to obtain 9940 g of phosphorus-nitrogen synergistic flame retardant finished product. The reaction overflow gas is pressurized by a Roots blower, is absorbed by 2000 g of 85% phosphoric acid solution, and then is evacuated, and 2000 g of ammonium phosphate is obtained by concentrating and crystallizing the absorption liquid. The results of the finished product testing are shown in Table 1.
Example 2
1800 g of urea and 2520 g of melamine are put into a kneader, heated to 200 ℃ under the stirring condition to react for 1 hour, 5890 g of 105% polyphosphoric acid and 2000 g of ammonium phosphate obtained in example 1 are added, heated to 300 ℃, reacted for 2 hours, and cooled to obtain 10550 g of phosphorus-nitrogen synergistic flame retardant finished product. After the reaction overflow gas is pressurized by a Roots blower, 2310 g of 85% phosphoric acid mixed solution is added into the concentrated mother liquor in the embodiment 1 for absorption, and 2300 g of ammonium phosphate salt is obtained by crystallization of the absorption solution. The results of the finished product testing are shown in Table 1.
Example 3
600 g of urea and 5040 g of melamine are put into a kneader, heated to 160 ℃ under the stirring condition to react for 1.5 hours, 5345 g of 110% polyphosphoric acid and 2300 g of ammonium phosphate salt obtained in example 2 are added, heated to 300 ℃, reacted for 3 hours, and cooled to obtain 12330 g of phosphorus-nitrogen synergistic flame retardant finished product. After the reaction overflow gas is pressurized by a Roots blower, 1500 g of 85% phosphoric acid mixed solution is added into the concentrated mother liquor of the embodiment 2 for absorption, and 1610 g of ammonium phosphate is obtained by crystallizing the absorption solution. The results of the finished product testing are shown in Table 1.
Example 4
600 g of urea and 5040 g of melamine are put into a kneader, heated to 180 ℃ under the stirring condition, reacted for 1 hour, added with 6250 g of 105% polyphosphoric acid and 1610 g of ammonium phosphate salt obtained in example 3, kept at 300 ℃ for reaction for 2.5 hours, and cooled to obtain 12410 g of phosphorus-nitrogen synergistic flame retardant finished product. After the reaction overflow gas was pressurized by a roots blower, 2000 g of 85% phosphoric acid mixed solution was added to the concentrated mother liquor of example 3 to absorb the reaction overflow gas, thereby obtaining 2040 g of ammonium phosphate. The results of the finished product testing are shown in Table 1.
TABLE 1 analysis results of examples
Claims (5)
1. The preparation method of the nitrogen-phosphorus synergistic flame retardant is characterized by comprising the following steps: the product is prepared by the following steps:
(1) the mol ratio of urea to melamine is 1:1-4:1, reacting in equipment with temperature control and mixing functions under the conditions of heating and stirring, wherein the reaction temperature is 160-220 ℃ and the reaction time is 1-2 hours;
(2) in equipment with temperature control and mixing functions, under the conditions of heating and stirring, adding polyphosphoric acid with the concentration of 105-110% in the product obtained in the step (1) and ammonium phosphate obtained in the step (3) according to the molar ratio of 1:1-3:1, controlling the reaction temperature to be 240-300 ℃, reacting for 1-3 hours, and cooling to obtain a nitrogen-phosphorus synergistic flame retardant finished product, wherein the flame retardant has the following molecular formula:
(NH4)xM(1-x)PO3
wherein M represents melamine, x is between 0 and 1 and is not equal to 0 or 1;
(3) and (3) absorbing ammonia gas overflowing in the reaction processes of the steps (1) and (2) by using phosphoric acid to obtain ammonium phosphate, and adding the ammonium phosphate serving as a reaction raw material into the reaction of the step (2) in the next batch.
2. The method for preparing nitrogen-phosphorus synergistic flame retardant of claim 1, characterized in that: the reactions in the steps (1) and (2) can be finished in the same equipment or can be finished in different equipment in sequence.
3. The method for preparing nitrogen-phosphorus synergistic flame retardant of claim 2, characterized in that: the equipment with temperature control and mixing functions is a ribbon mixer, an internal mixer or a kneader.
4. The method for preparing nitrogen-phosphorus synergistic flame retardant of claim 1, characterized in that: the reaction temperature in the step (1) is 180-.
5. The method for preparing nitrogen-phosphorus synergistic flame retardant of claim 1, characterized in that: the reaction temperature in the step (2) is 280-300 ℃, and the reaction time is 2-3 hours.
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