Preparation method and application of high-purity melamine pyrophosphate

Abstract

The invention relates to a preparation method and application of high-purity melamine pyrophosphate, and belongs to the technical field of preparation of melamine pyrophosphate. The preparation method mainly comprises the following steps: heating and stirring pyrophosphoric acid and melamine, spraying and adding a heteropoly acid ethanol solution as a catalyst, stirring and reacting to obtain an intermediate, and sintering at 220-330 DEG C to obtain the product. The preparation method disclosed by the invention has the following advantages: (1) no wastewater, waste gas or solid waste is generated in the preparation process, and the preparation method is a green preparation route; (2) the preparation method disclosed by the invention has low requirements on raw materials, and pyrophosphoric acid and melamine which are conventionally available on the market are adopted; (3) the steps are simple, and the two steps are carried out in the same equipment, namely a spraying type reaction kettle; and (4) the reaction temperature in the process is relatively low, and the energy consumption is low. The melamine pyrophosphate prepared by the invention has high purity (the purity is not less than 99%) and high heat resistance, and has a good flame retardant effect (UL 94V-0) after being used for preparing a polyolefin material.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of melamine pyrophosphate and relates to a preparation method of high-purity melamine pyrophosphate and application thereof. Background Art

[0002] At present, melamine pyrophosphate is mainly prepared by the following three methods: (1) Aqueous phase synthesis: For example, Yunnan Yuntianhua Co., Ltd., application number (202311419035.4) adopts the aqueous phase synthesis method, but the steps are relatively complicated, centrifugal filtration is required, and the purity is not high. (2) Acidic liquid phase synthesis: For example, Qingyuan Pusaifu Phosphate Chemical Co., Ltd. (201310502575.9) uses hydrochloric acid as the acidic environment. This method is not environmentally friendly, and the by-products produced need to be specially treated, which undoubtedly increases the manufacturing cost. (3) Solid phase synthesis method: For example, the solid phase synthesis method adopted by Aidi Co., Ltd. (201480003375.1) directly uses orthophosphate for sintering, but the selected raw material orthophosphate is expensive, and the reaction temperature reaches 350°C, which has high requirements for equipment.

[0003] It can be seen that the current preparation methods of melamine pyrophosphate all have problems such as being environmentally unfriendly, complicated preparation process and low purity. It is necessary to develop a new method for preparing melamine pyrophosphate with high purity, high flame retardancy, no three wastes, simple preparation process and low cost. Summary of the invention

[0004] In view of this, one of the objects of the present invention is to provide a method for preparing high-purity melamine pyrophosphate; a second object of the present invention is to provide high-purity melamine pyrophosphate; a third object of the present invention is to provide an application of high-purity melamine pyrophosphate in the preparation of polyolefin materials.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] 1. A method for preparing high-purity melamine pyrophosphate, the method comprising the following steps:

[0007] (1) placing pyrophosphoric acid and melamine in a spray reactor, stirring and mixing them evenly after heating, spraying and adding a heteropoly acid ethanol solution under stirring conditions, stirring at a speed of 500 to 1500 r / min for 30 to 120 minutes, and obtaining an intermediate;

[0008] (2) heating the intermediate to 220-330° C. and sintering the intermediate for 30-120 min to obtain melamine pyrophosphate white powder;

[0009] During the preparation process of step (1) and step (2), a gas release treatment is performed to discharge gaseous ethanol.

[0010] Preferably, in step (1), the molar ratio of pyrophosphoric acid to melamine is 1:1.9-2.1.

[0011] Preferably, in step (1), the stirring after heating is specifically: heating to 50-120° C. and stirring for 10-60 min.

[0012] Preferably, in step (1), the heteropolyacid is a bifunctional green catalyst having both acidity and redox properties.

[0013] Preferably, the heteropoly acid is a Keggin type heteropoly acid;

[0014] The Keggin type heteropoly acid includes any one of phosphotungstic acid, phosphomolybdic acid or silicotungstic acid.

[0015] Preferably, in step (1), the mass ratio of the pyrophosphoric acid to the heteropoly acid in the heteropoly acid ethanol solution is 1:1 to 10%.

[0016] 2. The high-purity melamine pyrophosphate prepared according to the above preparation method.

[0017] 3. Application of the above high-purity melamine pyrophosphate in the preparation of polyolefin materials.

[0018] The beneficial effects of the present invention are as follows: the present invention discloses a method for preparing high-purity melamine pyrophosphate, which mainly comprises the following steps: heating pyrophosphoric acid and melamine, stirring and then spraying and adding a heteropolyacid ethanol solution as a catalyst, stirring and reacting to obtain an intermediate, and then sintering at 220-330°C. The preparation method of the present invention has the following advantages: (1) the preparation method of the present invention does not generate waste water, waste gas and solid waste during the preparation process, and is a green preparation route; (2) the preparation method of the present invention has low requirements for raw materials, and conventional pyrophosphoric acid and melamine on the market can be used; (3) the preparation method of the present invention has simple steps, and both steps are carried out in the same equipment of a spray reactor; (4) the reaction temperature during the preparation method of the present invention is relatively low, and the energy consumption is low. The melamine pyrophosphate prepared by the preparation method of the present invention has high purity (purity not less than 99%) and high heat resistance, and has good flame retardant effect (UL 94V-0) after being used to prepare polyolefin materials.

[0019] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0021] Figure 1 The reaction formula for preparing the high-purity melamine pyrophosphate of the present invention is:

[0022] Figure 2 is the infrared spectrum of the high-purity melamine pyrophosphate prepared in Example 1;

[0023] Figure 3 This is the thermogravimetric spectrum of the high-purity melamine pyrophosphate prepared in Example 1. DETAILED DESCRIPTION

[0024] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0025] Example 1

[0026] A high-purity melamine pyrophosphate, the reaction formula is as follows Figure 1 The specific preparation method is as follows:

[0027] (1) placing pyrophosphoric acid and melamine in a molar ratio of 1:1.9 in a spray reactor, heating to 50° C. and stirring for 10 minutes to mix evenly, and then spraying phosphotungstic acid ethanol solution (wherein the mass ratio of phosphotungstic acid to ethanol is 1:1, and the phosphotungstic acid in the phosphotungstic acid ethanol solution is 2% of the mass of pyrophosphoric acid) under stirring conditions, and stirring at a speed of 800 r / min for 30 minutes to obtain an intermediate;

[0028] (2) heating the intermediate to 250° C. and sintering the intermediate for 60 minutes to obtain melamine pyrophosphate white powder;

[0029] During the preparation process of the above steps (1) and (2), a gas release treatment is performed to discharge gaseous ethanol.

[0030] Example 2

[0031] A high-purity melamine pyrophosphate, the specific preparation method is as follows:

[0032] (1) placing pyrophosphoric acid and melamine in a molar ratio of 1:2.0 in a spray reactor, heating to 120° C. and stirring for 10 min to mix evenly, adding phosphomolybdic acid ethanol solution (wherein the mass ratio of phosphomolybdic acid to ethanol is 1:1, and the phosphomolybdic acid in the phosphomolybdic acid ethanol solution is 1% of the mass of pyrophosphoric acid) by spraying under stirring, and stirring at a speed of 500 r / min for 120 min to obtain an intermediate;

[0033] (2) heating the intermediate to 250° C. and sintering the intermediate for 60 minutes to obtain melamine pyrophosphate white powder;

[0034] During the preparation process of the above steps (1) and (2), a gas release treatment is performed to discharge gaseous ethanol.

[0035] Example 3

[0036] A high-purity melamine pyrophosphate, the specific preparation method is as follows:

[0037] (1) Pyrophosphoric acid and melamine in a molar ratio of 1:2.1 are placed in a spray reactor, heated to 70°C and stirred for 60 minutes to mix evenly, and then silicotungstic acid ethanol solution (wherein the mass ratio of silicotungstic acid to ethanol is 1:1, and the mass of silicotungstic acid in the silicotungstic acid ethanol solution is 10% of the mass of pyrophosphoric acid) is sprayed under stirring conditions, and stirred at a speed of 1500 r / min for 30 minutes to obtain an intermediate;

[0038] (2) heating the intermediate to 220° C. and sintering the intermediate for 60 min to obtain melamine pyrophosphate white powder;

[0039] During the preparation process of the above steps (1) and (2), a gas release treatment is performed to discharge gaseous ethanol.

[0040] Example 4

[0041] Polyolefin flame retardant material, the specific preparation method is as follows:

[0042] The melamine pyrophosphate prepared in the above-mentioned Examples 1, 2 and 3 were respectively compounded with piperazine pyrophosphate (QZ10-2, provided by Chongqing Kejufu New Materials Co., Ltd.) in a mass ratio of 6:4, and then the compounded flame retardant was mixed with polypropylene in a mass ratio of 25:75, extruded into granules by a twin-screw extruder (35 machine, extrusion temperature 200°C), and then injection molded into flame-retardant strips (1.6mm) by an injection molding machine (injection molding temperature 200°C), so as to obtain different polyolefin flame retardant materials.

[0043] Comparative Example 1

[0044] The melamine pyrophosphate in the above Example 4 was replaced with commercially available melamine pyrophosphate with a phosphorus (P) content of 14.5%, a nitrogen (N) content of 36.0% and a purity of 99.5%, and a polyolefin flame retardant material was prepared according to the method of Example 4.

[0045] Performance Testing

[0046] Figure 2 is the infrared spectrum of the high-purity melamine pyrophosphate prepared in Example 1. Figure 2 It can be seen that the infrared spectrum of the high-purity melamine pyrophosphate prepared in Example 1 is consistent with the infrared spectrum of standard melamine pyrophosphate, indicating that the method of Example 1 of the present invention can indeed prepare melamine pyrophosphate.

[0047] Figure 3 The thermogravimetric spectrum of the high-purity melamine pyrophosphate prepared in Example 1. Figure 3 It can be seen that the high-purity melamine pyrophosphate prepared in Example 1 has good stability, so that it can withstand higher processing temperatures in subsequent applications.

[0048] The performance of the melamine pyrophosphate in Example 1, Example 2 and Example 3 was tested, and the results are shown in Table 1. The polyolefin flame retardant materials prepared by melamine pyrophosphate in different embodiments of Example 4 and the polyolefin flame retardant materials prepared in the comparative example were tested by a horizontal vertical combustion tester, and the results are shown in Table 2.

[0049] Table 1 Performance test results of melamine pyrophosphate in different embodiments

[0050] index Commercially available Example 1 Example 2 Example 3 P(％) 14.5 14.8 14.6 14.6 N(％) 36.0 39.7 38.9 39.3 purity(%) 99.5 99.3 99.4 99.7 1% thermal decomposition temperature (℃) 275.0 315.0 312.1 314.4 5% thermal decomposition temperature (℃) 306.5 372.1 370.7 372.1

[0051] Note: Phosphorus (P) and nitrogen (N) contents were determined by Agilent gas chromatography (G1534-60570), purity was determined by Agilent high performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (LC-Q-TOF), thermal decomposition temperature was determined by German Netzsch thermogravimetric analyzer (TG209F3), infrared analysis was performed by Agilent infrared spectrometer (Agilent Cary 630).

[0052] Table 2 Flame retardant properties test results of polyolefin flame retardant materials prepared from melamine pyrophosphate in different embodiments

[0053]

[0054]

[0055] As can be seen from Table 1, the method of the present invention can prepare high-purity melamine pyrophosphate with a purity greater than 99% under different conditions, and has a higher thermal decomposition temperature, so that it can be used in material preparation scenarios with more stringent processing temperatures. As can be seen from Table 2, the melamine pyrophosphate prepared under different conditions by the present invention can be used to prepare polyolefin materials. Compared with the polyolefin flame retardant material prepared by the existing commercially available melamine pyrophosphate, under the same addition ratio, it has better flame retardant properties and can reduce the preparation cost of olefin materials.

[0056] In summary, the present invention discloses a method for preparing high-purity melamine pyrophosphate, which mainly comprises the following steps: heating and stirring pyrophosphoric acid and melamine, spraying and adding a heteropolyacid ethanol solution as a catalyst, stirring and reacting to obtain an intermediate, and then sintering at 220-330°C. The preparation method of the present invention has the following advantages: (1) the preparation method of the present invention does not generate waste water, waste gas and solid waste during the preparation process, and is a green preparation route; (2) the preparation method of the present invention has low requirements for raw materials, and conventional pyrophosphoric acid and melamine on the market can be used; (3) the preparation method of the present invention has simple steps, and both steps are carried out in the same equipment of a spray reactor; (4) the reaction temperature during the preparation method of the present invention is relatively low, and the energy consumption is low. The melamine pyrophosphate prepared by the preparation method of the present invention has high purity (purity not less than 99%) and high heat resistance, and has good flame retardant effect (UL 94V-0) after being used to prepare polyolefin materials.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A method for preparing high-purity melamine pyrophosphate, characterized in that: The preparation method comprises the following steps: (1) placing pyrophosphoric acid and melamine in a spray reactor, stirring and mixing them evenly after heating, spraying and adding a heteropoly acid ethanol solution under stirring conditions, stirring at a speed of 500 to 1500 r / min for 30 to 120 minutes, and obtaining an intermediate; (2) heating the intermediate to 220-330° C. and sintering the intermediate for 30-120 min to obtain melamine pyrophosphate white powder; During the preparation process of step (1) and step (2), a gas release treatment is performed to discharge gaseous ethanol.

2. The preparation method according to claim 1, characterized in that: In step (1), the molar ratio of pyrophosphoric acid to melamine is 1:1.9-2.

1.

3. The preparation method according to claim 1, characterized in that: In step (1), the stirring after heating specifically comprises: heating to 50-120° C. and stirring for 10-60 min.

4. The preparation method according to claim 1, characterized in that: In step (1), the heteropolyacid is a bifunctional green catalyst having both acidity and redox properties.

5. The preparation method according to claim 1, characterized in that: The heteropoly acid is a Keggin type heteropoly acid; The Keggin type heteropoly acid includes any one of phosphotungstic acid, phosphomolybdic acid or silicotungstic acid.

6. The preparation method according to claim 1, characterized in that: In step (1), the mass ratio of the pyrophosphoric acid to the heteropoly acid in the heteropoly acid ethanol solution is 1:1 to 10%.

7. High-purity melamine pyrophosphate prepared according to the preparation method according to any one of claims 1 to 6.

8. Use of the high-purity melamine pyrophosphate according to claim 7 in the preparation of polyolefin materials.

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