Flame retardant phosphoryl melamine compound and preparation method thereof

Abstract

The present invention relates to a flame retardant phosphoryl melamine compound and a preparation method thereof. The structure of the compound is shown in the following formula: #imgabs0# The preparation method is: in an organic solvent, sodium melamine reacts with 1 to 1.1 times mole of phosphorus oxychloride, and after purification treatment, phosphoryl melamine is obtained. The compound of the present invention has a stable structure, high flame retardant efficiency, good carbonization property, and a wide range of applications. It can be used as a flame retardant for materials such as epoxy resin, unsaturated polyester resin, and polyvinyl alcohol; it can also be used as a flame retardant for wood, cotton, linen, paper, cellulose, etc.; the process is simple, the equipment investment is small, and it is easy to realize industrial production.

Description

Technical Field

[0001] The present invention relates to a flame retardant phosphoryl melamine compound and a preparation method thereof, and more particularly to a flame retardant phosphoryl melamine compound and a preparation method thereof, wherein the compound can be used as a flame retardant for materials such as epoxy resin, unsaturated polyester resin, polyvinyl alcohol, etc.; and can also be used as a flame retardant for wood, cotton, linen, paper, cellulose, etc. Background Art

[0002] At present, with the improvement of environmental protection and human health awareness, the research of new high-efficiency, low-toxic, halogen-free and environmentally friendly flame retardants has become a hot topic. Among them, phosphorus-nitrogen flame retardants are widely developed and applied, such as melamine phosphate, melamine pyrophosphate, melamine polyphosphate, etc. Although the above compounds have good flame retardancy, they are easy to ionize due to their salt-bonded ionic compound structure, which makes them easy to absorb moisture, migrate, frost and have poor permanence in application. Therefore, in order to overcome the shortcomings brought by the above-mentioned ionic bonds, in the molecular structure design of the compound, only by changing the salt-bonded ion combination of the compound into a stable covalent bond structure can the great market application demand be met.

[0003] The invention discloses a flame retardant phosphoryl melamine compound and a preparation method thereof. The flame retardant phosphoryl melamine is prepared using melamine (melamine) sodium salt and phosphorus oxychloride as raw materials, with a simple process, low cost, and easy conversion to industrial production; the flame retardant of the invention has the advantages of high flame retardant efficiency, good carbonization property, good stability of phosphorus-nitrogen covalent bond bonding of amide structure, wide application range, and not easy migration when encountering deliquescence, etc. Therefore, the flame retardant of the invention has very good application development prospects. Summary of the invention

[0004] One of the purposes of the present invention is to propose a flame retardant phosphoryl melamine compound, which has the advantages of stable amide structure, anti-migration, containing two flame retardant elements of phosphorus and nitrogen in the molecule, high content of flame retardant elements, good compatibility with materials, wide application range, etc., which can overcome the shortcomings of the prior art.

[0005] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0006] A flame retardant phosphoryl melamine compound, characterized in that the structure of the compound is shown in the following formula:

[0007]

[0008] The second object of the present invention is to provide a method for preparing a flame retardant phosphoryl melamine compound, which has a simple process, is easy to mass produce, requires little equipment investment, and is low in cost.

[0009] The method is:

[0010] In a reactor equipped with a stirrer, a thermometer, a reflux condenser and a drying tube, under nitrogen protection, add dry sodium melamine and an organic solvent, and under stirring at room temperature, add 1 to 1.1 times the mole of phosphorus oxychloride dropwise within 30 minutes. After the addition is complete, raise the temperature to 60 to 100°C, reflux for 4 to 6 hours, add an equivalent amount of water for hydrolysis of phosphorus oxychloride dropwise, react for 1 hour until no hydrogen chloride gas is generated, cool to 30°C, add water to dissolve the generated sodium chloride, filter with suction, rinse the filter cake three times with ice water 1.5 to 2 times the theoretical mass of the product, compact and drain each time, and vacuum dry at 80°C to obtain white crystalline phosphoryl melamine.

[0011] The organic solvent as mentioned above is chloroform, ethylene dichloride, carbon tetrachloride, acetonitrile or dioxane, and its usage volume in milliliters is 6-8 times the mass in grams of melamine sodium salt.

[0012] The flame retardant phosphoryl melamine compound of the present invention is a white solid, with a starting decomposition temperature of 275±5°C, a rapid decomposition temperature of 320±5°C, and a product yield of 86.0-93.5%. It can be used as a flame retardant for materials such as epoxy resin, unsaturated polyester resin, and polyvinyl alcohol; it can also be used as a flame retardant for wood, cotton, linen, paper, cellulose, etc. The preparation principle of the flame retardant phosphoryl melamine compound is shown in the following formula:

[0013]

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] ① The flame retardant phosphomelamine of the present invention is an amide compound, phosphorus and nitrogen are covalently bonded, the product has good structural stability, and can overcome the disadvantage of easy deliquesce and ionization migration of phosphomelamine salt.

[0016] ② The flame retardant phosphoryl melamine of the present invention is an amide, which can be used as a flame retardant for polymer materials, and can also be used as a flame retardant for wood, paper, fiber, etc., and has a wide range of applications.

[0017] ③ The flame retardant phosphoryl melamine of the present invention is an amide compound, has good expansion and carbonization properties, is a high-efficiency environmentally friendly flame retardant, has a good anti-melting dripping effect, and can overcome the deficiency of secondary ignition of dripping.

[0018] ④ The flame retardant phosphoryl melamine of the present invention is an amide compound. Studies have shown that the use of phosphoryl melamine in unsaturated polyester resin fiberglass can give the material better toughness, indicating that the flame retardant phosphoryl melamine has a certain plasticity.

[0019] ⑤ The flame retardant phosphoryl melamine of the present invention is an amide compound with a high content of effective flame retardant elements (nitrogen content 40.78%, phosphorus content 15.05%) reaching 55.83%, meeting the requirements of green chemical synthesis, with high atomic utilization and less pollution.

[0020] ⑥ The preparation method of the flame retardant phosphoryl melamine compound of the present invention is a one-step reaction, the raw materials are easily available, the process is simple, the equipment investment is small, the operation is convenient, and it is easy to mass produce. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to further illustrate the structure and performance of the flame retardant phosphoryl melamine of the present invention, the following drawings are provided.

[0022] Figure 1 This is the infrared spectrum of phosphomelamine;

[0023] Figure 1 It shows that 3467cm -1 is the stretching vibration absorption peak of NH2 of melamine, 1590cm -1 is the NH bending vibration absorption peak, 1500cm -1 is the stretching vibration absorption peak of the triazine ring C=N, 1170cm -1 is the stretching vibration absorption peak of P=0, 1050cm -1 is the stretching vibration absorption peak of P-0, 820cm -1 The vibration absorption peak of the PN bond appearing at further proves that the molecular structure of phosphomelamine has determined the formation of a new covalent bond.

[0024] Figure 2 It is the NMR spectrum of phosphoramidite;

[0025] Figure 2 It shows that when deuterated DMSO is used as solvent, δ=2.5 is the solvent proton peak of deuterated DMSO; δ=3.3 is the water peak of deuterated DMSO as solvent; δ=5.62 is the hydrogen peak of the amino group (NH2) of phosphomelamine; δ=7.69 is the hydrogen peak of the imino group (NH) of phosphomelamine; at the same time, since the hydroxyl group (OH) in phosphomelamine is a more active phosphate hydroxyl group, it is easily masked by the water in deuterated DMSO, so it may not be displayed. The theoretical value of the ratio of the number of hydrogens of the imino group to the amino group in phosphomelamine is 1:4, and the ratio of the peak areas obtained by actual integration is close to it.

[0026] Figure 3 This is the thermal analysis curve of phosphoryl melamine; Figure 3 It shows that when phosphomelamine is placed in a micro differential thermal balance, the heating rate is controlled at 10℃ / min and the scanning range is 0~800℃ under nitrogen atmosphere, phosphomelamine begins to decompose at about 275℃ and decomposes rapidly at 320℃. When heated to 800℃, 18% of carbon remains. Figure 3It also shows that before rapid decomposition, the endothermic and exothermic conditions are stable or balanced. After rapid decomposition, an endothermic peak is generated at 355°C, which may be caused by the dehydration of phosphoryl hydroxyl groups to take away the heat. It can be seen from the figure that the product is relatively stable under high temperature conditions and has good flame retardant application prospects.

[0027] Figure 4 This is the morphology of phosphoramidite used in the combustion of unsaturated resin; Figure 4 It shows that a is the combustion photo of the blank sample, b is the combustion photo of the 10% added amount, c is the combustion photo of the 20% added amount, and d is the combustion photo of the 25% added amount; Figure 4 It shows that phosphomelamine has good expansion and carbon-forming properties when used in the combustion of unsaturated resins.

[0028] Figure 5 This is a scanning electron microscope (SEM) image of the carbon residue formed after phosphoryl melamine was used in the combustion of unsaturated resin; Figure 5 It shows that e is the SEM photo of the blank sample combustion, and f is the SEM photo of the combustion with 20% addition. The contrast between the blank sample picture and the sample picture is very obvious. After the blank sample is burned, glass fibers are left, and all organic matter is burned out. After the sample is burned, a solid and dense covering layer is formed. This is a dense expanded carbon layer connected by the polyphosphonic acid membrane, which can prevent the invasion of heat and oxygen, thereby protecting the internal material from further combustion, laying the foundation for the excellent expanded carbon flame retardant effect. Specific embodiments

[0029] The technical solution of the present invention is further described below in conjunction with specific implementation methods.

[0030] Example 1 In a 500mL four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a drying tube, 29.62g (0.2mol) of dried melamine sodium salt and 150mL of chloroform were added under nitrogen protection, and 30.66g (17.1mL, 0.2mol) of phosphorus oxychloride was added dropwise at room temperature within 30 minutes. After the addition was completed, the temperature was raised to 60°C, and the reaction was refluxed for 6 hours. 3.6mL of water was added dropwise, and the reaction was continued for 1 hour until no hydrogen chloride gas was generated. The temperature was lowered to 30°C, and 18mL of water was added to dissolve the generated sodium chloride. The filter cake was rinsed with 60mL of ice water three times, and each rinse was compacted and drained, and vacuum dried at 80°C to obtain white crystalline phosphoryl melamine. The product yield was 88.3%.

[0031] Example 2 In a 500mL four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a drying tube, 29.62g (0.2mol) of dried melamine sodium salt and 180mL of dichloroethane were added under nitrogen protection, and 30.66g (17.1mL, 0.2mol) of phosphorus oxychloride was added dropwise at room temperature within 30 minutes. After the addition was completed, the temperature was raised to 80°C, and the reaction was refluxed for 6 hours. 3.6mL of water was added dropwise, and the reaction was continued for 1 hour until no hydrogen chloride gas was generated. The temperature was lowered to 30°C, and 18mL of water was added to dissolve the generated sodium chloride. The filter cake was rinsed with 60mL of ice water three times, and each rinse was compacted and drained, and vacuum dried at 80°C to obtain white crystalline phosphoryl melamine. The product yield was 90.5%.

[0032] Example 3 In a 500mL four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a drying tube, 29.62g (0.2mol) of dried melamine sodium salt and 180mL of carbon tetrachloride were added under nitrogen protection, and 30.66g (17.1mL, 0.2mol) of phosphorus oxychloride was added dropwise at room temperature within 30 minutes. After the addition was completed, the temperature was raised to 75°C, and the reaction was refluxed for 5 hours. 3.6mL of water was added dropwise, and the reaction was continued for 1 hour until no hydrogen chloride gas was generated. The temperature was lowered to 30°C, and 18mL of water was added to dissolve the generated sodium chloride. The filter cake was rinsed with 60mL of ice water three times, and each rinse was compacted and drained, and vacuum dried at 80°C to obtain white crystalline phosphoryl melamine. The product yield was 86.0%.

[0033] Example 4 In a 500mL four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a drying tube, 29.62g (0.2mol) of dried melamine sodium salt and 160mL of acetonitrile were added under nitrogen protection, and 32.19g (17.96mL, 0.21mol) of phosphorus oxychloride was added dropwise at room temperature within 30 minutes. After the addition was completed, the temperature was raised to 80°C, and the reaction was refluxed for 5 hours. 4.15mL of water was added dropwise, and the reaction was continued for 1 hour until no hydrogen chloride gas was generated. The temperature was lowered to 30°C, and 18mL of water was added to dissolve the generated sodium chloride. The filter cake was rinsed with 60mL of ice water three times, and each rinse was compacted and drained, and vacuum dried at 80°C to obtain white crystalline phosphoryl melamine. The product yield was 87.5%.

[0034] Example 5 In a 500mL four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a drying tube, 29.62g (0.2mol) of dried melamine sodium salt and 200mL of dioxane were added under nitrogen protection, and 33.72g (18.82mL, 0.22mol) of phosphorus oxychloride was added dropwise at room temperature within 30 minutes. After the addition was completed, the temperature was raised to 100°C, and the mixture was refluxed for 4 hours. 4.7mL of water was added dropwise, and the mixture was reacted for 1 hour until no hydrogen chloride gas was generated. The temperature was lowered to 30°C, and 18mL of water was added to dissolve the generated sodium chloride. The mixture was filtered by suction, and the filter cake was rinsed three times with 60mL of ice water. Each rinse was compacted and drained, and vacuum dried at 80°C to obtain white crystalline phosphoryl melamine. The product yield was 91.2%.

[0035] Example 6 In a 500mL four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a drying tube, 29.62g (0.2mol) of dried melamine sodium salt and 190mL of chloroform were added under nitrogen protection, and 32.19g (17.96mL, 0.21mol) of phosphorus oxychloride was added dropwise at room temperature within 30 minutes. After the addition was completed, the temperature was raised to 60°C, and the reaction was refluxed for 5 hours. 4.15mL of water was added dropwise, and the reaction was continued for 1 hour until no hydrogen chloride gas was generated. The temperature was lowered to 30°C, and 18mL of water was added to dissolve the generated sodium chloride. The filter cake was filtered by suction, and the filter cake was rinsed three times with 60mL of ice water. Each rinse was compacted and drained, and vacuum dried at 80°C to obtain white crystalline phosphoryl melamine. The product yield was 92.2%.

[0036] Example 7 In a 500mL four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a drying tube, 29.62g (0.2mol) of dried melamine sodium salt and 170mL of dichloroethane were added under nitrogen protection, and 32.19g (17.96mL, 0.21mol) of phosphorus oxychloride was added dropwise at room temperature within 30 minutes. After the addition was completed, the temperature was raised to 80°C, and the reaction was refluxed for 5 hours. 4.15mL of water was added dropwise, and the reaction was continued for 1 hour until no hydrogen chloride gas was generated. The temperature was lowered to 30°C, and 18mL of water was added to dissolve the generated sodium chloride. The filter cake was rinsed with 60mL of ice water three times, and each rinse was compacted and drained, and vacuum dried at 80°C to obtain white crystalline phosphoryl melamine. The product yield was 93.5%.

[0037] Example 8 In a 500mL four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a drying tube, 29.62g (0.2mol) of dried melamine sodium salt and 180mL of acetonitrile were added under nitrogen protection, and 33.72g (18.82mL, 0.22mol) of phosphorus oxychloride was added dropwise at room temperature within 30 minutes. After the addition was completed, the temperature was raised to 80°C, and the reaction was refluxed for 6 hours. 4.7mL of water was added dropwise, and the reaction was continued for 1 hour until no hydrogen chloride gas was generated. The temperature was lowered to 30°C, and 18mL of water was added to dissolve the generated sodium chloride. The filter cake was rinsed with 60mL of ice water three times, and each rinse was compacted and drained, and vacuum dried at 80°C to obtain white crystalline phosphoryl melamine. The product yield was 91.2%.

[0038] Example 9 In a 500mL four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a drying tube, 29.62g (0.2mol) of dried melamine sodium salt and 170mL of carbon tetrachloride were added under nitrogen protection, and 33.72g (18.82mL, 0.22mol) of phosphorus oxychloride was added dropwise at room temperature within 30 minutes. After the addition was completed, the temperature was raised to 75°C, and the reaction was refluxed for 4 hours. 4.7mL of water was added dropwise, and the reaction was continued for 1 hour until no hydrogen chloride gas was generated. The temperature was lowered to 30°C, and 18mL of water was added to dissolve the generated sodium chloride. The filter cake was rinsed with 60mL of ice water three times, and each rinse was compacted and drained, and vacuum dried at 80°C to obtain white crystalline phosphoryl melamine. The product yield was 90.4%.

[0039] Example 10 In a 500mL four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a drying tube, 29.62g (0.2mol) of dried melamine sodium salt and 150mL of dioxane were added under nitrogen protection, and 32.19g (17.96mL, 0.21mol) of phosphorus oxychloride was added dropwise at room temperature within 30 minutes. After the addition was completed, the temperature was raised to 100°C, and the mixture was refluxed for 5 hours. 4.15mL of water was added dropwise, and the mixture was reacted for 1 hour until no hydrogen chloride gas was generated. The temperature was lowered to 30°C, and 18mL of water was added to dissolve the generated sodium chloride. The mixture was filtered by suction, and the filter cake was rinsed three times with 60mL of ice water. Each rinse was compacted and drained, and vacuum dried at 80°C to obtain white crystalline phosphoryl melamine. The product yield was 89.4%.

[0040] The inventors also applied the above-prepared product phosphomelamine to 886 unsaturated resin, mixed phosphomelamine and 886 unsaturated resin in different proportions, added 0.2% methyl ethyl ketone peroxide as an initiator, stirred and mixed, and poured into a mold with a length of 15 cm, a width of 1.0 cm, and a thickness of 0.3 cm, added glass fiber cloth as an inner lining, and then made into standard specimens, and studied the flame retardant properties and carbonization of the product. The test data are shown in Table 1-2.

[0041] Table 1 Oxygen index test data and phenomena of phosphoramidite used in 886 unsaturated resin

[0042]

[0043] Table 1 shows that the limiting oxygen index of 886 unsaturated resin itself is 18%. When 10% of phosphoryl melamine is added to 886 unsaturated resin, the LOI is 22%. When 20% is added, the LOI reaches 27%, reaching the flame retardant level. Flame retardant phosphoryl melamine has a good flame retardant effect on 886 unsaturated resin, and the material has a good expansion and carbonization performance when burning.

[0044] Table 2 Vertical combustion test data and phenomena of phosphoryl melamine in 886 unsaturated resin

[0045]

[0046] Table 2 shows that when the flame retardant phosphoryl melamine is added in an amount of 10% in 886 unsaturated resin, a good flame retardant effect of V-1 level is achieved. When the addition amount reaches 20%, an ideal flame retardant effect of V-0 level is achieved. Therefore, the flame retardant phosphoryl melamine has good flame retardant properties.

[0047] The inventors also applied the above-prepared product phosphomelamine to 886 unsaturated resin, added the flame retardant phosphomelamine to 886 unsaturated resin in different proportions, and made 15 cm long, 1 cm wide, 0.3 cm thick strips for tensile testing. The mechanical properties of the composite material are shown in Table 3.

[0048] Table 3 Mechanical test data of phosphoramidite added to 886 unsaturated resin

[0049]

[0050] It can be seen from Table 3 that as the addition amount of the flame retardant phosphamide increases, the tensile strength decreases, but the elongation at break of the material increases and the toughness of the material increases, indicating that the flame retardant phosphamide has a certain plasticity.

[0051] The inventors also applied the above-prepared product phosphatidyl melamine to the flame retardancy of wood. The phosphatidyl melamine was added to water, concentrated ammonia was added to assist dissolution and the pH was adjusted to 7 to prepare a 20% solution. The prepared 15 cm long, 1 cm wide, and 0.3 cm thick pine wood strips were soaked in the solution for 20 minutes, taken out and naturally dried. The limiting oxygen index was measured to be 51%, indicating that the product phosphatidyl melamine has a good flame retardant effect on wood.

Claims

1. A method for preparing a flame retardant phosphoryl melamine compound, characterized in that: The method is: In a reactor equipped with a stirrer, a thermometer, a reflux condenser and a drying tube, dry melamine sodium salt and an organic solvent are added under nitrogen protection. The chemical structure of the melamine sodium salt is: Under stirring at room temperature, 1 to 1.1 times the mole of phosphorus oxychloride is added dropwise within 30 minutes. After the addition is completed, the temperature is raised to 60 to 100°C, and the reaction is refluxed for 4 to 6 hours. An equivalent amount of water is added dropwise to hydrolyze phosphoryl chloride, and the reaction is carried out for 1 hour until no hydrogen chloride gas is generated. The temperature is lowered to 30°C, and water is added to dissolve the generated sodium chloride. The filter cake is filtered by suction, and the filter cake is rinsed three times with ice water 1.5 to 2 times the theoretical mass of the product. Each rinsing is compacted and drained, and vacuum dried at 80°C to obtain white crystalline phosphoryl melamine, which has a chemical structure shown in the following formula:

2. A method for preparing a flame retardant phosphoryl melamine compound as claimed in claim 1, characterized in that: The method is: The organic solvent is chloroform, ethylene dichloride, carbon tetrachloride, acetonitrile or dioxane, and its usage volume in milliliters is 6-8 times the mass in grams of melamine sodium salt.

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