Metal ion modified melamine polyphosphate containing silane structure and preparation method thereof, and flame retardant

Abstract

The present invention provides a metal ion-modified melamine polyphosphate containing a silane structure, a preparation method thereof, and a flame retardant. The preparation method comprises: reacting polyphosphoric acid and alkylsiloxane to obtain a polyphosphate compound containing a silane structure, then adding a solvent and urea to react to obtain a polyphosphate urea salt mixture containing a silane structure; uniformly mixing the polyphosphate urea salt mixture containing a silane structure with melamine, then adding polyphosphoric acid to react to obtain a melamine polyphosphate prepolymer containing a silane structure; and reacting the obtained melamine polyphosphate prepolymer containing a silane structure, a metal compound, and melamine under nitrogen protection at 240-280°C for 2-10 hours to obtain the metal ion-modified melamine polyphosphate containing a silane structure.

Description

Technical Field

[0001] The invention relates to the technical field of melamine polyphosphate modification, in particular to a metal ion-modified melamine polyphosphate containing a silane structure, a preparation method thereof, and a flame retardant. Background Art

[0002] Melamine polyphosphate (MPP for short) is a phosphorus-nitrogen halogen-free flame retardant, generally used as a flame retardant synergist for aluminum diethylphosphinate (ADP), and is widely used in plastics, resins, polyurethane elastomers and other fields, such as nylon 66, PBT, TPU, epoxy and other polymer materials.

[0003] Currently, there are two main methods for synthesizing melamine polyphosphate: a one-step method and a two-step method. The one-step method involves the direct reaction of melamine and polyphosphoric acid at temperatures above 300°C, but this method suffers from slightly poor thermal stability. The two-step method involves first combining melamine and phosphoric acid in a certain ratio to produce melamine phosphate, which is then polycondensed at temperatures above 300°C to produce melamine polyphosphate. However, as an inorganic polymer, both the one-step and two-step methods present compatibility issues when used as flame retardants in polymers. Simple surface modification with silicone coupling agents cannot effectively address flame retardant precipitation issues under high temperature and humidity conditions. Furthermore, both the one-step and two-step methods require polycondensation at temperatures above 300°C, which inevitably leads to defects such as incomplete polycondensation, incomplete salt formation, and residual P-OH groups. Application in polymer materials can result in poor dispersibility, unstable flame retardancy, significant impact on material mechanical properties, and migration under high temperature and humidity conditions.

[0004] In order to solve the above problems, some people have improved the methods of melamine polyphosphate through modification and surface treatment.

[0005] For example, Chinese patent application number CN200510010255.7 discloses a metal modification method, in which a metal hydroxide, oxide, or carbonate is dissolved and dispersed in a phosphoric acid solution. Water and the phosphoric acid solution containing dihydrogen phosphate are reacted with melamine, followed by thermal polymerization for 8-12 hours to produce an improved product. Chinese patent application number CN201010040041.5 discloses a modification process, which uses type II ammonium polyphosphate, water, and phosphoric acid. After heating, melamine is added to react, filtered, dried, and the reaction is continued at 300-450°C to produce the modified product. Chinese patent application number CN202110851630.X discloses a method for synthesizing silane-modified melamine phosphate using melamine, dihydrogen ammonium phosphate, and a silane coupling agent in the presence of a catalyst.

[0006] Although the above method can improve the thermal stability of melamine polyphosphate to a certain extent and increase its compatibility with nylon and resin materials, the problem of polycondensation temperature above 300°C still exists. In addition, there is still the problem of melamine polyphosphate's resistance to precipitation and migration in polymers. When it is compounded with organic phosphonates (such as aluminum diethylphosphinate) for synergistic flame retardancy, the problems of easy migration under high temperature and high humidity and unstable flame retardancy have not been well solved. Summary of the Invention

[0007] The purpose of the present invention is to provide a metal ion-modified melamine polyphosphate containing a silane structure that can reduce the polycondensation temperature, is modified based on organosilane and metal ions, can improve the compatibility and dispersibility in polymers such as nylon, and solves the problems of material performance degradation and high-temperature and high-humidity migration caused by synergistic reaction with organic phosphonate resins to avoid mutual reaction.

[0008] In order to solve any of the above technical problems, the present invention provides a metal ion-modified melamine polyphosphate containing a silane structure. The structural formula of the metal ion-modified melamine polyphosphate containing a silane structure is as follows:

[0009]

[0010] Among them, the silane structure is located on the main chain;

[0011] Among them, M Z+ is a metal ion, and Z is the valence state of the metal ion;

[0012] Wherein, a and c are the average polymerization degrees of polyphosphoric acid, a and c are both ≥ 1.2, and b = 1 or 2;

[0013] Wherein, R1 and R2 are phenyl groups.

[0014] Optionally, the metal ion is a divalent or trivalent metal ion, for example, it can be one or more of zinc, magnesium, copper, aluminum, nickel, iron, and calcium, preferably one or more of zinc, magnesium, and aluminum.

[0015] The present application also provides a method for preparing a metal ion-modified melamine polyphosphate containing a silane structure, the preparation method comprising:

[0016] Preparation of polyphosphate urea salt mixture: first, polyphosphoric acid and alkylsiloxane react to obtain a polyphosphate compound containing a silane structure, and then solvent and urea are added to react to obtain a polyphosphate urea salt mixture containing a silane structure;

[0017] Preparation of prepolymer: after uniformly mixing the polyphosphate urea mixture containing silane structure and melamine, adding polyphosphoric acid, and reacting to obtain the melamine polyphosphate prepolymer containing silane structure;

[0018] Metal ion modification: The obtained melamine polyphosphate prepolymer containing a silane structure, a metal compound and melamine are reacted at 240° C. to 280° C. under nitrogen protection for 2 to 10 hours to obtain metal ion-modified melamine polyphosphate containing a silane structure.

[0019] This preparation method can lower the polycondensation temperature to 240°C to 280°C. Modification with organosilanes and metal ions, through dual organic-inorganic modification, improves compatibility and dispersibility in polymers such as nylon. The phenyl-containing siloxanes do not discolor at high temperatures, unaffecting the product's whiteness. The introduction of metal elements also enhances the polyphosphate's charring and precipitation resistance, addressing the issues of material performance degradation and migration during high-temperature and high-humidity conditions caused by synergistic reactions with organic phosphonate resins. This metal ion-modified melamine polyphosphate containing a silane structure addresses these issues.

[0020] The present application adopts silane modification of polyphosphoric acid first, introduces silane structure into the main chain, and then metal ion modification, which avoids the problem of first reacting with metal salt to form polyphosphate metal salt, which affects the polycondensation. In the preparation step of the polyphosphate urea salt mixture, polyphosphoric acid and alkylsiloxane are reacted first, and then urea is added to react, rather than adding the three reactants together, and the reaction result is more controllable. Preventing polyphosphoric acid from reacting with urea first to form polyphosphate urea affects the reaction rate of polyphosphoric acid and siloxane on the one hand, and polyphosphate urea has poor thermal stability on the other hand, and is easily decomposed at the reaction temperature of siloxane and polyphosphoric acid, causing interference with the reaction. .

[0021] In the preparation of the polyphosphate urea salt mixture, there are two reactions in which polyphosphoric acid and alkylsiloxane react to obtain a polyphosphate compound containing a silane structure. The first reaction mode is as follows:

[0022]

[0023] The second reaction mode is as follows:

[0024]

[0025] During the preparation of the polyphosphate urea salt mixture, a solvent and urea are added to react to obtain a polyphosphate urea salt mixture containing a silane structure, the structural formula of which is structure 1 or a mixture of structure 1 and structure 2, as follows:

[0026]

[0027] Optionally, the average degree of polymerization n of the polyphosphoric acid is ≥1.2, preferably 1.6-4, and correspondingly, a and c are preferably both 1.6-4. If the degree of polymerization is greater than 4, the viscosity is too high, it is difficult to disperse in the solvent, and it is easy to cause incomplete reaction. The size of b is related to the alkoxy group. When there are 2 alkoxy groups, b=1, and when there are 3 alkoxy groups, b=2. Optionally, the alkylsiloxane is diphenyldimethoxysilane and / or diphenyldiethoxysilane. Furthermore, the alkylsiloxane can also include one or more of phenyltrimethoxysilane and phenyltriethoxysilane, wherein the molar ratio of diphenylsilane to phenylsilane is 1:0-0.5, preferably 1:0-0.2. The thermal stability of the alkyl group with the addition of phenyl groups can meet the application requirements, and the thermal stability of the alkyl group is not enough. Phenylsilane refers to an alkylsiloxane with one phenyl group. Diphenylsilane refers to an alkylsiloxane with two phenyl groups.

[0028] Optionally, the molar ratio of polyphosphoric acid to alkylsiloxane in the preparation of the polyphosphate urea salt mixture is 1:0.02-1.00, preferably 1:0.05-0.3; the molar ratio of phosphorus to urea in the obtained polyphosphate urea salt mixture containing silane structure is 1:0.05-1.50, preferably 0.2-0.7.

[0029] Optionally, in the preparation of the prepolymer, the molar ratio of polyphosphoric acid and the mixture of polyphosphate urea salt containing a silane structure is 1:0.01 to 1, further, 1:0.02 to 1, preferably 1:0.1 to 0.8, and the molar ratio of the sum of the phosphorus in polyphosphoric acid and the phosphorus in the mixture of polyphosphate urea salt containing a silane structure to melamine is 1:0.8 to 1.50, preferably 1:1.00 to 1.20.

[0030] Optionally, in the metal ion modification step, the weight ratio of the melamine polyphosphate prepolymer containing a silane structure to the metal compound is 1:0.01-0.3, preferably 1:0.02-0.1, and the weight ratio of the melamine polyphosphate prepolymer containing a silane structure to melamine is 1:0.01-0.5, and further preferably 1:0.01-0.2, preferably 1:0.03-0.1. Because the reaction temperature at this time is higher than the sublimation temperature of melamine, the melamine is mainly used to form the melamine atmosphere, and very little participates in the reaction.

[0031] Optionally, the metal compound is one or more hydroxides or oxides of zinc, magnesium, copper, aluminum, nickel, iron, and calcium. Other metal compounds either do not participate in the reaction or, such as carbonates, have the risk of releasing a large amount of carbon dioxide, which can also make the reaction temperature unstable.

[0032] Optionally, the reaction of polyphosphoric acid and alkylsiloxane in the preparation of the polyphosphate urea salt mixture, the reaction of adding solvent and urea in the preparation of the polyphosphate urea salt mixture, and the reaction in the preparation of the prepolymer are all two-step reactions, and the two-step reaction includes reacting at a first temperature first and then heating to continue reacting at a second temperature. Vacuum devolatilization can also be performed in the two-step reaction. For example, in the second step of the reaction of polyphosphoric acid and alkylsiloxane to obtain a polyphosphate compound containing a silane structure in the preparation of the polyphosphate urea salt mixture, vacuum devolatilization can be performed, and the vacuum degree can be controlled at 0.005MPa to 0.08MPa, and the reaction is continued for 1 hour to 10 hours. After the two-step reaction, it is cooled to 3°C-25°C. For example, in the second step of the reaction of adding solvent and urea to obtain a polyphosphate urea mixture containing a silane structure in the preparation of the polyphosphate urea salt mixture, the temperature is heated to 50°C to start vacuum devolatilization, and the temperature is gradually increased to 90°C and maintained for 2 hours to 5 hours. There is no specific requirement for the vacuum degree here.

[0033] Correspondingly, in the preparation of the urea polyphosphate mixture, the first step of the reaction of polyphosphoric acid and alkylsiloxane to obtain a polyphosphate compound containing a silane structure can be carried out for 1 to 3 hours at a temperature of 60° C. to 90° C. In the preparation of the urea polyphosphate mixture, a solvent and urea are added to react to obtain the urea polyphosphate mixture containing a silane structure, and the reaction is controlled at 3° C. to 25° C. for 0.5 to 3 hours.

[0034] Optionally, in the preparation of the polyphosphate urea salt mixture, polyphosphoric acid is first added, then heated to 40° C. to 50° C., stirred at a speed of 80 rpm to 150 rpm, and alkylsiloxane is added to start the second step reaction.

[0035] Optionally, the solvent may be ethanol with a relatively economical mass concentration of 65%-85%, preferably 70%-85%. Before adding the solvent, the vacuum needs to be turned off and vented, and then the urea is added after stirring evenly.

[0036] Vacuum devolatilization may not be used in the two-step reaction. For example, in the preparation of the prepolymer, a mixture of melamine and urea polyphosphate containing a silane structure is stirred for 0.2 to 1 hour to mix uniformly, and then polyphosphoric acid is added. The temperature is maintained at 80±5°C, and after stirring for 0.5 to 2 hours, the temperature is raised to 200°C for 2 to 5 hours, and the reaction is continued for 1 to 3 hours. The mixture is cooled and crushed to obtain a prepolymer.

[0037] The present application also provides a flame retardant comprising: any of the above-described metal ion-modified melamine polyphosphates containing a silane structure, aluminum diethylphosphinate, a polymer substrate, glass fiber, and a processing aid; wherein the polymer substrate is one or more of a thermoplastic, a thermosetting plastic, a rubber, and a thermoplastic elastomer. The metal ion-modified melamine polyphosphate containing a silane structure in the flame retardant does not react with an organic phosphonate resin to cause material performance degradation or migration issues under high temperature and humidity conditions, and exhibits excellent flame retardancy after high temperature and humidity testing.

[0038] Optionally, the polymer substrate may be one or more of nylon 6, nylon 66, polybutylene terephthalate, thermoplastic polyurethane, and epoxy resin.

[0039] In summary, the silane-containing melamine polyphosphate prepolymer of the present invention, modified with organosilane and metal ions, achieves dual organic-inorganic modification, improving compatibility and dispersibility in polymers such as nylon. The phenyl-containing siloxane does not discolor at high temperatures, unaffecting the product's whiteness, reaching over 90, with some even exceeding 95. Furthermore, the introduction of metal elements enhances the polyphosphate's charring and precipitation resistance, addressing the issues of material performance degradation and high-temperature and high-humidity migration caused by synergistic reactions with organic phosphonate resins.

[0040] Moreover, the entire preparation method can reduce the polycondensation temperature to 240°C to 280°C.

[0041] When the metal ion modified melamine polyphosphate containing silane structure in the flame retardant is combined with the organic phosphonate resin, the notched impact strength can reach 11.4kJ / m 2 As mentioned above, there is no migration or no obvious migration under high temperature and high humidity (85% humidity, 85°C constant temperature and humidity chamber for 168 hours). After high temperature and high humidity, the surface of the specimen is dried, and the UL94 flame retardancy reaches V1 or above after being placed in a desiccator for 72 hours. There is no mutual reaction that causes material performance degradation and high temperature and high humidity migration problems, and the flame retardancy after high temperature and high humidity is excellent. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is an infrared spectrum provided by Example 1 (zinc ion modification) of the present invention;

[0043] Figure 2 This is an infrared spectrum provided by Example 4 (aluminum ion modification) of the present invention. DETAILED DESCRIPTION

[0044] The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0045] Unless otherwise stated, all raw materials in this example are commercially available and percentages are by mass.

[0046] The whiteness is tested according to GB / T 23774-2009 standard.

[0047] Example 1

[0048] Step 1: Preparation of polyurea phosphate mixture containing silane structure

[0049] 1000 moles of polyphosphoric acid (average degree of polymerization 1.6) add in the reactor, be heated to 40~50 ℃, 120 rev / mins of stirring velocitys add 180 moles of diphenyldiethoxysilane, 20 moles of monophenyltrimethoxysilane, react 1.5 hours, temperature remains on 75-85 ℃, vacuumizes devolatilization simultaneously, vacuum tightness is 0.01MPa, continues reaction 4 hours, is cooled to 5-10 ℃, obtains containing the silane structure polyphosphoric acid compound.Add 35 kilograms of 75% ethanol after closing the vacuum venting, stir.Add 600 moles of urea, control 5-10 ℃ of following reactions 2 hours, heat temperature raising to 50 ℃ of beginning vacuum devolatilization, be warmed up to 90 ℃ gradually, kept 4 hours, obtain containing the silane structure polyphosphoric acid urea salt mixture.

[0050] Step 2: Preparation of melamine polyphosphate prepolymer containing silane structure

[0051] 3801 mol of melamine (the molar ratio of the sum of phosphorus in polyphosphoric acid and phosphorus in a mixture of polyphosphate urea containing a silane structure to melamine is 1:1.145) and 200 mol of a mixture of polyphosphate urea containing a silane structure are added into a horizontal kneader. After stirring for 0.5 hour to mix uniformly, 1000 mol of polyphosphoric acid (average degree of polymerization 3) is added. The temperature is maintained at 80±5°C and stirred for 1 hour. The temperature is then raised to 200°C over 5 hours, the reaction is continued for 3 hours, and the mixture is cooled and crushed to obtain a melamine polyphosphate prepolymer containing a silane structure.

[0052] Step 3: Preparation of metal ion modified melamine polyphosphate containing silane structure

[0053] Add 1000kg of melamine polyphosphate prepolymer containing silane structure, 50kg of zinc oxide and 50kg of melamine into a horizontal kneader and react at 240-260℃ for 5 hours under nitrogen protection to obtain metal ion modified melamine polyphosphate containing silane structure, which is a white flowable powder with a whiteness of 96. The infrared spectrum is as shown below: Figure 1 The generated tail gas is absorbed by a tail gas absorption device in multiple stages using 50% phosphoric acid.

[0054] Example 2

[0055] Step 1: Preparation of polyurea phosphate mixture containing silane structure

[0056] 1000 mol of polyphosphoric acid (average degree of polymerization 2) is added to a reactor, heated to 40-50° C., stirred at 120 rev / min, 300 mol of diphenyldimethoxysilane is added, and the reaction is continued for 2 hours. The temperature remains at 80-90° C., while vacuuming and devolatilizing at a vacuum degree of 0.01 MPa. The reaction is continued for 8 hours, and cooled to 10-20° C. to obtain a polyphosphoric acid compound containing a silane structure. After the vacuum is turned off and vented, 58 kg of 85% ethanol is added and stirred. 500 mol of urea is added, and the reaction is continued for 2.5 hours at a temperature of 10-20° C., heated to 50° C. and vacuum devolatilization is started, gradually warmed to 90° C., and maintained for 2 hours to obtain a polyphosphoric acid urea salt mixture containing a silane structure.

[0057] Step 2: Preparation of melamine polyphosphate prepolymer containing silane structure

[0058] 3388 mol of melamine (the molar ratio of the sum of phosphorus in polyphosphoric acid and phosphorus in a mixture of polyphosphate urea containing a silane structure to melamine is 1:1.1) and 440 mol of a mixture of polyphosphate urea containing a silane structure are added into a horizontal kneader. After stirring for 1 hour to mix uniformly, 1100 mol of polyphosphoric acid (average degree of polymerization 2) is added. The temperature is maintained at 80±5°C and stirred for 1.5 hours. The temperature is then raised to 200°C over 4 hours, the reaction is continued for 2.5 hours, and the mixture is cooled and crushed to obtain a melamine polyphosphate prepolymer containing a silane structure.

[0059] Step 3: Preparation of metal ion modified melamine polyphosphate containing silane structure

[0060] 1000 kg of silane-containing melamine polyphosphate prepolymer, 60 kg of zinc oxide, and 80 kg of melamine were added to a horizontal kneader and reacted at 260-280°C under nitrogen for 6 hours to obtain metal ion-modified silane-containing melamine polyphosphate as a white, flowable powder with a whiteness of 95%. The resulting exhaust gas was absorbed in a multi-stage exhaust gas absorption device using 50% phosphoric acid.

[0061] Example 3

[0062] Step 1: Preparation of polyurea phosphate mixture containing silane structure

[0063] 1000 moles of polyphosphoric acid (average degree of polymerization 2) add in the reactor, are heated to 40~50 ℃, 120 rev / mins of stirring velocitys add 180 moles of diphenyldimethoxysilane, 20 moles of monophenyltrimethoxysilane, reacted 2 hours, and temperature remained on 75-85 ℃, vacuumized devolatilization simultaneously, vacuum tightness is 0.01MPa, continued reaction 3 hours, was cooled to 3-10 ℃, obtained containing the silane structure polyphosphoric acid compound.Add 62 kilograms of 80% ethanol after closing the vacuum venting, stir.Add 400 moles of urea, controlled 5-10 ℃ of following reaction 2 hours, heat temperature raising to 50 ℃ of beginning vacuum devolatilization, be warmed up to 90 ℃ gradually, kept 3 hours, obtained containing the silane structure polyphosphoric acid urea salt mixture.

[0064] Step 2: Preparation of melamine polyphosphate prepolymer containing silane structure

[0065] 3381 mol of melamine (the molar ratio of the sum of phosphorus in polyphosphoric acid and phosphorus in a mixture of polyurea phosphate containing a silane structure to melamine is 1:1.05) and 460 mol of a mixture of polyurea phosphate containing a silane structure are added into a horizontal kneader. After stirring for 0.5 hour to mix evenly, 1150 mol of polyphosphoric acid (average degree of polymerization 2) is added. The temperature is maintained at 80±5°C and stirred for 1 hour. The temperature is then raised to 200°C over 3 hours, the reaction is continued for 2 hours, and the mixture is cooled and crushed to obtain a melamine polyphosphate prepolymer containing a silane structure.

[0066] Step 3: Preparation of metal ion modified melamine polyphosphate containing silane structure

[0067] 1000 kg of silane-containing melamine polyphosphate prepolymer, 100 kg of zinc oxide, and 80 kg of melamine were added to a horizontal kneader and reacted at 260-280°C under nitrogen for 10 hours to obtain metal ion-modified silane-containing melamine polyphosphate as a white, flowable powder with a whiteness of 96. The resulting exhaust gas was absorbed in a multi-stage exhaust gas absorption device using 50% phosphoric acid.

[0068] Example 4

[0069] Step 1: Preparation of polyurea phosphate mixture containing silane structure

[0070] 1000 mole of polyphosphoric acid (average degree of polymerization 2) add in the reactor, be heated to 40~50 ℃, 120 rev / mins of stirring velocitys add 280 moles of diphenyldimethoxysilane, 20 moles of monophenyltrimethoxysilane, reacted 1.5 hours, and temperature remained on 75-85 ℃, vacuumized devolatilization simultaneously, vacuum tightness is 0.01MPa, continued reaction 6 hours, was cooled to 5-10 ℃, obtained containing the silane structure polyphosphoric acid compound.Add 60 kilograms of 80% ethanol after closing the vacuum venting, stir.Add 400 moles of urea, controlled 5-10 ℃ of following reaction 2 hours, heat temperature raising to 50 ℃ of beginning vacuum devolatilization, be warmed up to 90 ℃ gradually, kept 4 hours, obtained containing the silane structure polyphosphoric acid urea salt mixture.

[0071] Step 2: Preparation of melamine polyphosphate prepolymer containing silane structure

[0072] 3388 mol of melamine (the molar ratio of the sum of phosphorus in polyphosphoric acid and phosphorus in a mixture of polyurea phosphate containing a silane structure to melamine is 1:1.1) and 440 mol of a mixture of polyurea phosphate containing a silane structure are added into a horizontal kneader. After stirring for 1 hour to mix uniformly, 1100 mol of polyphosphoric acid (average degree of polymerization 2) is added. The temperature is maintained at 80±5°C and stirred for 1.5 hours. The temperature is then raised to 200°C over 3 hours, the reaction is continued for 2 hours, and the mixture is cooled and crushed to obtain a melamine polyphosphate prepolymer containing a silane structure.

[0073] Step 3: Preparation of metal ion modified melamine polyphosphate containing silane structure

[0074] Add 1000kg of silane-containing melamine polyphosphate prepolymer, 70kg of aluminum hydroxide, and 60kg of melamine into a horizontal kneader and react at 260-280°C for 7 hours under nitrogen protection to obtain metal ion-modified silane-containing melamine polyphosphate, a white flowable powder with a whiteness of 95. The infrared spectrum is shown in the figure below. Figure 2 The generated tail gas is absorbed by a tail gas absorption device in multiple stages using 50% phosphoric acid.

[0075] Example 5

[0076] Step 1: Preparation of polyurea phosphate mixture containing silane structure

[0077] 1000 mole of polyphosphoric acid (average degree of polymerization 2) adds in the reactor, is heated to 40~50 ℃, 120 rev / mins of stirring velocitys add 180 moles of diphenyldimethoxysilane, 20 moles of monophenyltrimethoxysilane, reacted 1.5 hours, and temperature remained on 80-90 ℃, vacuumized devolatilization simultaneously, vacuum tightness is 0.01MPa, continued reaction 5 hours, was cooled to 3-10 ℃, obtained containing the silane structure polyphosphoric acid compound.Close the vacuum venting back and add 90 kilograms of 80% ethanol, stir.Add 418 moles of urea, controlled 3-10 ℃ and reacted 2 hours down, heat temperature raising to 50 ℃ and begin vacuum devolatilization, be warming up to 90 ℃ gradually, kept 4 hours, obtained containing the silane structure polyphosphoric acid urea salt mixture.

[0078] Step 2: Preparation of melamine polyphosphate prepolymer containing silane structure

[0079] 3480 mol of melamine (the molar ratio of the sum of phosphorus in polyphosphoric acid and phosphorus in a mixture of polyurea phosphate containing a silane structure to melamine is 1:1.13) and 440 mol of a mixture of polyurea phosphate containing a silane structure are added into a horizontal kneader. After stirring for 1 hour to mix uniformly, 1100 mol of polyphosphoric acid (average degree of polymerization 2) is added. The temperature is maintained at 80±5°C and stirred for 2 hours. The temperature is then raised to 200°C over 2 hours, the reaction is continued for 1 hour, and the mixture is cooled and crushed to obtain a melamine polyphosphate prepolymer containing a silane structure.

[0080] Step 3: Preparation of metal ion modified melamine polyphosphate containing silane structure

[0081] 1000 kg of silane-containing melamine polyphosphate prepolymer, 50 kg of magnesium hydroxide, and 50 kg of melamine were added to a horizontal kneader and reacted at 260-280°C for 4 hours under nitrogen to obtain a metal ion-modified silane-containing melamine polyphosphate as a white, flowable powder with a whiteness of 96. The resulting exhaust gas was absorbed in a multi-stage exhaust gas absorption device using 50% phosphoric acid.

[0082] Example 6

[0083] Step 1: Preparation of polyurea phosphate mixture containing silane structure

[0084] 700 moles of polyphosphoric acid (average degree of polymerization 3) add in the reactor, are heated to 40~50 ℃, 120 rev / mins of stirring velocitys add 140 moles of diphenyldimethoxysilane, 70 moles of monophenyltrimethoxysilane, reacted 3 hours, and temperature remained on 80-90 ℃, vacuumized devolatilization simultaneously, vacuum tightness is 0.01MPa, continued reaction 10 hours, was cooled to 20-25 ℃, obtained containing the silane structure polyphosphoric acid compound.Add 60 kilograms of 78% ethanol after closing the vacuum venting, stir.Add 350 moles of urea, controlled 5-10 ℃ of following reaction 3 hours, heat temperature raising to 50 ℃ of beginning vacuum devolatilization, be warmed up to 90 ℃ gradually, kept 5 hours, obtained containing the silane structure polyphosphoric acid urea salt mixture.

[0085] Step 2: Preparation of melamine polyphosphate prepolymer containing silane structure

[0086] 3591 mol of melamine (the molar ratio of the sum of phosphorus in polyphosphoric acid and phosphorus in a mixture of polyurea phosphate containing a silane structure to melamine is 1:1.05) and 540 mol of a mixture of polyurea phosphate containing a silane structure are added into a horizontal kneader. After stirring for 1 hour to mix uniformly, 900 mol of polyphosphoric acid (average degree of polymerization 2) is added. The temperature is maintained at 80±5°C and stirred for 2 hours. The temperature is then raised to 200°C over 2 hours, the reaction is continued for 3 hours, and the mixture is cooled and crushed to obtain a melamine polyphosphate prepolymer containing a silane structure.

[0087] Step 3: Preparation of metal ion modified melamine polyphosphate containing silane structure

[0088] 1000 kg of silane-containing melamine polyphosphate prepolymer, 50 kg of aluminum oxide, and 50 kg of melamine were added to a horizontal kneader and reacted at 260-280°C under nitrogen for 6 hours to obtain a metal ion-modified silane-containing melamine polyphosphate as a white, flowable powder with a whiteness of 94. The resulting exhaust gas was absorbed in a multi-stage exhaust gas absorption device using 50% phosphoric acid.

[0089] Example 7

[0090] Step 1: Preparation of polyurea phosphate mixture containing silane structure

[0091] 500 moles of polyphosphoric acid (average degree of polymerization 4) are added to the reactor, heated to 40-50 ℃, stirring velocity 120 rev / min, add 150 moles of diphenyldimethoxysilane, react 1 hour, temperature remains on 75-85 ℃, vacuumize and devolatilize simultaneously, vacuum degree is 0.01MPa, continue reaction 8 hours, cool to 3-10 ℃, obtain containing silane structure polyphosphoric acid compound. After closing vacuum vent, add 50 kilograms of 70% ethanol and stir. Add 350 moles of urea, control the reaction at 5-10 ℃ for 3 hours, heat temperature raising to 50 ℃ and start vacuum devolatilization, gradually be warmed up to 90 ℃, keep 4 hours, obtain containing silane structure polyphosphoric acid urea salt mixture.

[0092] Step 2: Preparation of melamine polyphosphate prepolymer containing silane structure

[0093] 3570 mol of melamine (the molar ratio of the sum of phosphorus in polyphosphoric acid and phosphorus in a mixture of polyurea phosphate containing a silane structure to melamine is 1:1.02) and 560 mol of a mixture of polyurea phosphate containing a silane structure are added into a horizontal kneader. After stirring for 1 hour to mix uniformly, 700 mol of polyphosphoric acid (average degree of polymerization 1.8) is added. The temperature is maintained at 80±5°C and stirred for 2 hours. The temperature is then raised to 200°C over 3 hours, the reaction is continued for 3 hours, and the mixture is cooled and crushed to obtain a melamine polyphosphate prepolymer containing a silane structure.

[0094] Step 3: Preparation of metal ion modified melamine polyphosphate containing silane structure

[0095] 1000 kg of silane-containing melamine polyphosphate prepolymer, 50 kg of zinc oxide, and 100 kg of melamine were added to a horizontal kneader and reacted at 260-280°C under nitrogen for 8 hours to obtain metal ion-modified silane-containing melamine polyphosphate as a white, flowable powder with a whiteness of 93. The resulting exhaust gas was absorbed in a multi-stage exhaust gas absorption device using 50% phosphoric acid.

[0096] Comparative Example 1

[0097] 1000 kg of polyphosphate melamine JLS-PNA350 (Hangzhou Jieersi) and 50 kg of zinc oxide were added to a reactor, and the mixture was reacted at 300-320°C under nitrogen for 3 hours. The mixture was cooled to obtain metal ion-modified polyphosphate melamine PNA-Zn. PNA-Zn was added to the reactor and stirred, sprayed with 30 kg of 70% diphenyldimethoxysilane alcohol (85 alcohol), and heated to 85-95°C for 1 hour. The temperature was then further increased to 135-155°C for 2 hours, and the mixture was pulverized to obtain silane-surface-modified metal ion-modified polyphosphate melamine as a white, flowable powder with a whiteness of 94.

[0098] Comparative Example 2

[0099] In a reactor, 5 kg of zinc oxide and 100 kg of melamine pyrophosphate (commercially available) were stirred and sprayed with 3 kg of 70% diphenyldimethoxysilane alcohol (85 alcohol). The temperature was raised to 85-95°C and maintained for 1 hour. The temperature was further raised to 135-155°C and maintained for 2 hours. The mixture was then crushed to obtain silane-surface-modified zinc oxide-containing melamine pyrophosphate as a white flowable powder with a whiteness of 96.

[0100] Comparative Example 3

[0101] Step 1: Preparation of polyurea phosphate mixture containing silane structure

[0102] 1000 mol of polyphosphoric acid (average degree of polymerization 2) is added to a reactor, heated to 40-50°C, stirred at 120 rpm, and then 300 mol of 3-aminopropyltriethoxysilane is added. The reaction is continued for 2 hours while the temperature is maintained at 80-90°C. Vacuum devolatilization is performed simultaneously at a vacuum degree of 0.01 MPa. The reaction is continued for 8 hours and then cooled to 10-20°C to obtain a polyphosphoric acid compound containing a silane structure. After the vacuum is turned off and the reactor is vented, 58 kg of 85% ethanol by mass is added and stirred uniformly. 500 mol of urea is added and the reaction is continued at 10-20°C for 2.5 hours. The reaction is then heated to 50°C and vacuum devolatilization is initiated. The temperature is gradually raised to 90°C and maintained for 2 hours to obtain a polyphosphoric acid urea salt mixture containing a silane structure.

[0103] Step 2: Preparation of melamine polyphosphate prepolymer containing silane structure

[0104] 3388 mol of melamine (the molar ratio of the sum of phosphorus in polyphosphoric acid and phosphorus in a mixture of polyphosphate urea containing a silane structure to melamine is 1:1.1) and 440 mol of a mixture of polyphosphate urea containing a silane structure are added into a horizontal kneader. After stirring for 1 hour to mix uniformly, 1100 mol of polyphosphoric acid (average degree of polymerization 2) is added. The temperature is maintained at 80±5°C and stirred for 1.5 hours. The temperature is then raised to 200°C over 4 hours, the reaction is continued for 2.5 hours, and the mixture is cooled and pulverized to obtain a slightly gray melamine polyphosphate prepolymer powder containing a silane structure.

[0105] Step 3: Preparation of metal ion modified melamine polyphosphate containing silane structure

[0106] 1000 kg of melamine polyphosphate prepolymer containing a silane structure, 60 kg of zinc oxide, and 80 kg of melamine were added to a horizontal kneader. After reacting at 260-280°C under nitrogen protection for 6 hours, the generated tail gas was absorbed by a multi-stage tail gas absorption device with 50% phosphoric acid to obtain a gray-brown powder.

[0107] Application Examples

[0108] The flame retardant nylon 66 (PA66) of the embodiment and the comparative embodiment is prepared according to the following formula:

[0109] Samples obtained from Examples and Comparative Examples: 6 wt%

[0110] Aluminum diethylphosphinate (OP1240): 10 wt%

[0111] PA66 (EP158, Huafeng Chemical) 45.6 wt%

[0112] PA6 (m2500, Xinhui Meida): 7wt%

[0113] Glass fiber (ecs10-03-568h, Jushi): 30wt%

[0114] Processing aids such as antioxidants: 1.4wt%.

[0115] The above formula, except for the glass fiber, was mixed evenly and added to the main feed of a 45 twin-screw extruder. The glass fiber was added at the glass fiber feed port. The screw speed was 200 rpm, the screw aspect ratio was 44D, and the screw heating temperature was set within the range of 180-260°C.

[0116] Table 1: Properties of Examples and Comparative Examples and Their Performance Indices in Nylon 66

[0117]

[0118] Remark:

[0119] 1. After the specimens were subjected to thermal aging treatment at 300°C in an air oven for 30 minutes, the color change was compared using a colorimeter. △E represents the total color difference. The test was conducted using the CS-821N equipment from Hangzhou Color Spectrum Technology Co., Ltd., in accordance with the GB / T7921-2008 uniform color formula and the color difference company standard.

[0120] 2. Place the specimen in a constant temperature and humidity chamber at 85% humidity and 85°C for 168 hours to observe the surface precipitation.

[0121] 3. After high temperature and high humidity, the surface of the specimen is dried and placed in a desiccator for 72 hours to test the UL94 flame retardancy.

[0122] 4. Notched impact strength: GB-T1843-2008 Determination of cantilever beam impact strength of plastics

[0123] By comparing the application data of Examples 1-7 with those of Comparative Examples 1-2, the high-temperature discoloration is significantly improved, the notched impact strength is also significantly enhanced, and the precipitation phenomenon is not obvious or even absent. This also proves that simple surface modification with an organosilicon coupling agent cannot effectively solve the problem of flame retardant precipitation under high temperature and high humidity.

[0124] By comparing the experimental data of Examples 1-7 and Comparative Example 3, the gray-brown powder obtained in Comparative Example 3 cannot be used and its whiteness is far inferior to that of Examples 1-7, which proves that the use of phenyl-free silane has a certain impact on stability.

[0125] Although the present invention has been disclosed above by means of preferred embodiments, this is not intended to limit the present invention. Anyone skilled in the art may make slight changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope of protection required by the claims.

Claims

1. A metal ion modified melamine polyphosphate containing a silane structure, characterized in that: The structural formula of the metal ion modified melamine polyphosphate containing a silane structure is as follows: ； Among them, the silane structure is located on the main chain. Among them, M Z+ is a metal ion, and Z is the valence state of the metal ion; Wherein, a and c are the average polymerization degrees of polyphosphoric acid, and the range of a and c are both 1.6-4, and b=1 or 2; Wherein, R1 and R2 are phenyl groups; Wherein, the metal ions are one or more of zinc, magnesium, copper, aluminum, nickel, iron and calcium.

2. A method for preparing the metal ion-modified melamine polyphosphate containing a silane structure according to claim 1, characterized in that: The preparation method comprises: Preparation of polyphosphate urea salt mixture: polyphosphoric acid and alkylsiloxane are reacted to obtain a polyphosphate compound containing a silane structure, and then a solvent and urea are added to react to obtain a polyphosphate urea salt mixture containing a silane structure; Preparation of prepolymer: uniformly mixing a polyphosphate urea mixture containing a silane structure and melamine, and then adding polyphosphoric acid to react to obtain a melamine polyphosphate prepolymer containing a silane structure; Metal ion modification step: reacting the obtained silane structure-containing melamine polyphosphate prepolymer, the metal compound, and melamine at 240° C. to 280° C. under nitrogen protection for 2 to 10 hours to obtain metal ion-modified silane structure-containing melamine polyphosphate; Wherein, the alkylsiloxane includes one or more of diphenyldimethoxysilane and diphenyldiethoxysilane; Wherein, the metal compound is one or more hydroxides or oxides of zinc, magnesium, copper, aluminum, nickel, iron, and calcium.

3. The method for preparing the metal ion-modified melamine polyphosphate containing a silane structure according to claim 2, wherein: The molar ratio of polyphosphoric acid to alkylsiloxane in the preparation of the polyphosphate urea salt mixture is 1:0.02-1.00, and the molar ratio of phosphorus to urea in the obtained polyphosphate urea salt mixture containing a silane structure is 1:0.05-1.

50.

4. The method for preparing the metal ion-modified melamine polyphosphate containing a silane structure according to claim 2 or 3, wherein: In the preparation of the prepolymer, the molar ratio of polyphosphoric acid to the urea polyphosphate mixture containing a silane structure is 1:0.01-1, and the molar ratio of the sum of phosphorus in polyphosphoric acid and phosphorus in the urea polyphosphate mixture containing a silane structure to melamine is 1:0.8-1.

50.

5. The method for preparing the metal ion-modified melamine polyphosphate containing a silane structure according to claim 2 or 3, characterized in that: In the metal ion modification step, the weight ratio of the melamine polyphosphate prepolymer containing a silane structure to the metal compound is 1:0.01-0.3, and the weight ratio of the melamine polyphosphate prepolymer containing a silane structure to melamine is 1:0.01-0.

5.

6. The method for preparing the metal ion-modified melamine polyphosphate containing a silane structure according to claim 2 or 3, wherein: The reaction of polyphosphoric acid and alkylsiloxane in the preparation of the polyphosphate urea salt mixture, the reaction of adding solvent and urea in the preparation of the polyphosphate urea salt mixture, and the reaction in the preparation of the prepolymer are all two-step reactions, and the two-step reaction includes reacting at a first temperature and then heating and continuing to react at a second temperature.

7. A flame retardant, characterized in that: include: The metal ion-modified melamine polyphosphate containing a silane structure according to claim 1; Aluminum diethylphosphinate; polymer substrate fiberglass; processing aids; Wherein, the polymer substrate is one or more of thermoplastic plastics, thermosetting plastics, rubber, and thermoplastic elastomer.

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