Alkyl hypophosphite aluminum and its preparation method and application

Abstract

This invention relates to the field of nylon flame retardant technology, and particularly to an alkyl aluminum hypophosphite, its preparation method, and its application. The invention provides a method for preparing alkyl aluminum hypophosphite, comprising the following steps: mixing an alkali metal hypophosphite salt, a free radical initiator, and water; sequentially introducing butene for butylation, introducing propylene for propylation, and introducing ethylene for ethylation, to obtain an aqueous solution of the alkyl alkali metal hypophosphite salt; mixing the aqueous solution of the alkyl alkali metal hypophosphite salt with a water-soluble aluminum salt, and performing a precipitation reaction to obtain the alkyl aluminum hypophosphite. The alkyl aluminum hypophosphite prepared by this method can achieve the V0 flame retardant standard with a relatively small amount added.

Description

Technical Field

[0001] This invention relates to the field of nylon flame retardant technology, and in particular to an alkyl aluminum hypophosphite, its preparation method, and its application. Background Technology

[0002] Diethylaluminum hypophosphite is a compound with the molecular formula Al(PO₂C₄H₂) 10 3. CAS No. 225789-38-8, molar mass 390.3 g / mol, structural formula as shown in Formula 1. The product is a white powder solid, suitable for high-temperature flame-retardant modification of nylon (both glass fiber reinforced and unreinforced). The flame-retardant modified material exhibits good physical and electrical properties. Simultaneously, diethylaluminum hypophosphite shell, combined with nitrogen-containing flame retardants, can be used for flame retardant modification of PA6 and PA66 (both glass fiber reinforced and unreinforced), achieving UL94 V-0 (0.4 mm) flame retardancy. Formula 1.

[0003] Chinese patent CN1660858A discloses a method for preparing diethyl hypophosphite, including an example of preparing aluminum diethyl hypophosphite. The method involves introducing ethylene into a high-pressure reactor at a pressure of 0.6 MPa, reacting at 100-110°C for 6 hours, followed by salt formation. While the preparation steps are simple, the resulting product contains approximately 2% butyl ethyl aluminum hypophosphite, indicating a high impurity content. This high impurity level negatively impacts the quality of the final product when used as a flame retardant additive for aluminum diethyl hypophosphite; only at higher addition levels can the V0 standard be achieved. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide an alkyl aluminum hypophosphite, its preparation method and application, wherein the alkyl aluminum hypophosphite prepared by the preparation method can achieve the V0 flame retardant standard with a small amount of addition.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing alkyl aluminum hypophosphite, comprising the following steps: An alkali metal hypophosphite salt, a free radical initiator, and water are mixed and then sequentially introduced into butene for butylation, propylene for propylation, and ethylene for ethylation to obtain an aqueous solution of an alkyl alkali metal hypophosphite salt. An aqueous solution of the alkyl hypophosphite alkali metal salt and a water-soluble aluminum salt are mixed and a precipitation reaction is carried out to obtain the alkyl hypophosphite aluminum.

[0006] Preferably, the free radical initiator includes one or more of ammonium persulfate, sodium persulfate, hydrogen peroxide, performic acid, and peracetic acid.

[0007] Preferably, the molar ratio of the hypophosphite alkali metal salt to the free radical initiator is (100~150):1.

[0008] The molar ratio of the alkali metal hypophosphite to butene is 1:(0~0.2), and is not 0; The butylation reaction is carried out at a pressure of 0~0.4MPa, and the pressure is not 0; the temperature of the butylation reaction is 100~130℃, and the time is 1~2h.

[0009] Preferably, the molar ratio of the alkali metal hypophosphite to propylene is 1:(0~0.2), and not 0; The propylation reaction is carried out at a pressure of 0~0.7 MPa, and the pressure is not 0; the temperature of the propylation reaction is 100~120℃, and the time is 1~2h.

[0010] Preferably, the molar ratio of the alkali metal hypophosphite to ethylene is 1:(0~0.8), and is not 0; The ethylation reaction is carried out at a pressure of 0.8~1.0 MPa; the temperature of the ethylation reaction is 90~100℃, and the time is 2~4h.

[0011] Preferably, the water-soluble aluminum salt is one or more of aluminum sulfate, aluminum nitrate, aluminum hydroxide, and alum; The molar ratio of the alkyl hypophosphite in the aqueous solution of the water-soluble aluminum salt and the alkyl hypophosphite is (1.1~2):6.

[0012] Preferably, the precipitation reaction is carried out at a temperature of 50-100°C, a pH value of 2-6, and a time of 2-4 hours.

[0013] The present invention also provides alkyl aluminum hypophosphite prepared by the preparation method described above, including alkyl aluminum hypophosphite with the structure shown in formula a, alkyl aluminum hypophosphite with the structure shown in formula b, and alkyl aluminum hypophosphite with the structure shown in formula c; Formula a; Formula b; Formula c.

[0014] This invention also provides the application of the alkyl aluminum hypophosphite described in the above technical solution in the field of nylon flame retardancy.

[0015] This invention provides a method for preparing alkyl aluminum hypophosphite, comprising the following steps: mixing an alkali metal hypophosphite salt, a free radical initiator, and water; introducing butene for butylation; introducing propylene for propylation; and introducing ethylene for ethylation, to obtain an aqueous solution of the alkyl aluminum hypophosphite salt; mixing the aqueous solution of the alkyl aluminum hypophosphite salt with a water-soluble aluminum salt and performing a precipitation reaction to obtain the alkyl aluminum hypophosphite. Compared to diethylaluminum hypophosphite, the mixture has a higher carbon content (propyl and butyl have two more carbons than ethyl). The increased carbon content is beneficial for char formation and flame retardancy, as substances with higher carbon content are more prone to char formation. Char formation is key to condensed phase flame retardancy. Using different temperatures and pressures for stepwise reactions reduces impurities and makes the reaction easier to control, which is more convenient and controllable than simultaneously introducing gas. The alkyl aluminum hypophosphite prepared by the method of this invention achieves the V0 flame retardancy standard with an addition amount of only 10% relative to PA66, demonstrating high flame retardancy efficiency and saving production costs for downstream customers. Detailed Implementation

[0016] This invention provides a method for preparing alkyl aluminum hypophosphite, comprising the following steps: An alkali metal hypophosphite salt, a free radical initiator, and water are mixed and then sequentially introduced into butene for butylation, propylene for propylation, and ethylene for ethylation to obtain an aqueous solution of an alkyl alkali metal hypophosphite salt. An aqueous solution of the alkyl hypophosphite alkali metal salt and a water-soluble aluminum salt are mixed and a precipitation reaction is carried out to obtain the alkyl hypophosphite aluminum.

[0017] In this invention, unless otherwise specified, all raw materials used in the preparation are commercially available products well known to those skilled in the art.

[0018] In this invention, the process flow for preparing the alkyl aluminum hypophosphite is shown in Formulas I to II: Formula I; Formula II; This invention involves mixing an alkali metal hypophosphite salt, a free radical initiator, and water, then sequentially introducing butene for butylation, propylene for propylation, and ethylene for ethylation, to obtain an aqueous solution of an alkyl alkali metal hypophosphite salt.

[0019] In this invention, the alkali metal hypophosphite is preferably sodium hypophosphite, and more preferably sodium hypophosphite monohydrate.

[0020] In this invention, the free radical initiator preferably includes one or more of ammonium persulfate, sodium persulfate, hydrogen peroxide, performic acid, and peracetic acid, more preferably ammonium persulfate; when the free radical initiator is two or more of the above-mentioned specific selections, this invention does not impose any special limitation on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio.

[0021] In this invention, the molar ratio of the hypophosphite alkali metal salt and the free radical initiator is preferably (100~150):1, more preferably 100:1, 105:1, 110:1, 115:1, 120:1, 125:1, 130:1, 135:1, 140:1, 145:1 or 150:1.

[0022] The present invention does not impose any special limitation on the amount of water used; any amount known to those skilled in the art can be used.

[0023] The present invention does not impose any special limitations on the mixing process; any process well known to those skilled in the art can be used. In an embodiment of the present invention, the mixing process specifically involves dissolving the alkali metal hypophosphite in water, replacing the gas environment with ammonia, then evacuating to a vacuum and introducing butene, followed by the addition of a free radical initiator.

[0024] In this invention, the molar ratio of the alkali metal hypophosphite to butene is preferably 1:(0~0.2), and not 0; more preferably 1:0.05, 1:0.1, 1:0.15, or 1:0.2. In this invention, the butylation reaction is preferably carried out at a pressure of 0~0.4 MPa, and the pressure is not 0; more preferably 0.1 MPa, 0.2 MPa, 0.3 MPa, or 0.4 MPa; the temperature of the butylation reaction is preferably 100~130℃, more preferably 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, or 130℃; the time of the butylation reaction is preferably 1~2 h, more preferably 1 h, 1.2 h, 1.4 h, 1.6 h, 1.8 h, or 2 h.

[0025] In this invention, the molar ratio of the alkali metal hypophosphite to propylene is preferably 1:(0~0.2), and not 0; more preferably 1:0.05, 1:0.1, 1:0.15, or 1:0.2. In this invention, the propylation reaction is preferably carried out at a pressure of 0~0.7 MPa, and the pressure is not 0; more preferably 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, or 0.7 MPa; the temperature of the propylation reaction is preferably 100~120℃, more preferably 100℃, 105℃, 110℃, 115℃, or 120℃; the time is preferably 1~2 h, more preferably 1 h, 1.2 h, 1.4 h, 1.6 h, 1.8 h, or 2 h.

[0026] In this invention, the molar ratio of the alkali metal hypophosphite to ethylene is preferably 1:(0~0.8), and not 0; more preferably 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7 or 1:0.8; the ethylation reaction is preferably carried out at a pressure of 0.8~1.0 MPa, more preferably 0.8 MPa, 0.9 MPa or 1.0 MPa; the temperature of the ethylation reaction is preferably 90~100℃, more preferably 90℃, 92℃, 94℃, 96℃, 98℃ or 100℃; the time is preferably 2~4h, more preferably 2h, 2.5h, 3h, 3.5h or 4h.

[0027] After obtaining the aqueous solution of the alkyl hypophosphite alkali metal salt, the present invention mixes the aqueous solution of the alkyl hypophosphite alkali metal salt with a water-soluble aluminum salt to carry out a precipitation reaction to obtain the alkyl hypophosphite aluminum.

[0028] In this invention, the water-soluble aluminum salt is preferably one or more of aluminum sulfate, aluminum nitrate, aluminum hydroxide and alum, more preferably aluminum sulfate; when the water-soluble aluminum salt is two or more of the above-mentioned specific selections, this invention does not have any special limitation on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio.

[0029] In this invention, the water-soluble aluminum salt is preferably mixed with the aqueous solution of the alkyl hypophosphite alkali metal salt in the form of an aqueous solution. In this invention, the mass percentage concentration of the aqueous solution of the water-soluble aluminum salt is preferably 10-50%, more preferably 10%, 20%, 30%, 40%, or 50%. In an embodiment of this invention, the mass percentage concentration of the aqueous solution of the water-soluble aluminum salt can be 20%.

[0030] In this invention, the molar ratio of the water-soluble aluminum salt in the aqueous solution of the water-soluble aluminum salt to the alkyl hypophosphite in the aqueous solution of the alkyl hypophosphite is preferably (1.1~2):6, more preferably 1.1:6, 1.2:6, 1.3:6, 1.4:6, 1.5:6, 1.6:6, 1.7:6, 1.8:6, 1.9:6 or 2:6. In an embodiment of this invention, the molar ratio of the water-soluble aluminum salt in the aqueous solution of the water-soluble aluminum salt to the alkyl hypophosphite in the aqueous solution of the alkyl hypophosphite is specifically 1.93:6.

[0031] In this invention, the mixing is preferably performed by adding an aqueous solution of the water-soluble aluminum salt dropwise to an aqueous solution of the alkyl hypophosphite alkali metal salt. This invention does not impose any special limitations on the dropwise addition process; any process well-known to those skilled in the art can be used.

[0032] In this invention, the temperature of the precipitation reaction is preferably 50~100℃, more preferably 50℃, 60℃, 70℃, 80℃, 90℃ or 100℃; the pH value is preferably 2~6, more preferably 2, 3, 4, 5 or 6; the time is preferably 2~4h, more preferably 2h, 2.5h, 3h, 3.5h or 4h.

[0033] After the precipitation reaction is completed, the present invention preferably includes sequential filtration and drying. The present invention does not impose any special limitations on the filtration and drying process, and any process known to those skilled in the art can be used.

[0034] The present invention also provides alkyl aluminum hypophosphite prepared by the preparation method described above, including alkyl aluminum hypophosphite with the structure shown in formula a, alkyl aluminum hypophosphite with the structure shown in formula b, and alkyl aluminum hypophosphite with the structure shown in formula c; Formula a; Formula b; Formula c.

[0035] This invention also provides the application of the alkyl aluminum hypophosphite described in the above-described technical solution in the field of nylon flame retardancy. This invention does not impose any special limitations on the method of application; any method well-known to those skilled in the art can be used.

[0036] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0037] Example 1 500g of sodium hypophosphite monohydrate was dissolved in 2500g of water and pumped into a 5L high-pressure reactor. The gas inside the reactor was then replaced with ammonia and evacuated to a complete vacuum. Butene was then pressurized to 0.4MPa and heated to 100℃. 252g of 5% ammonium persulfate was then pumped into the reactor using a high-pressure pump to carry out the reaction, consuming a total of 26g of butene. The reaction was then stopped. Propylene was then introduced at 0.8MPa for propylation (reaction temperature 100℃), consuming 20g of propylene. Ethylene was then introduced at 0.8MPa for vinylation (reaction temperature 100℃), consuming 106g of ethylene. The reaction was carried out for 3 hours to obtain an aqueous solution of an alkyl alkali metal salt. The aqueous solution of the alkyl alkali metal salt was transferred to a precipitation vessel and heated to 80°C. 1047 g of a 50% (w / w) aluminum sulfate aqueous solution was added dropwise over 4 hours to induce precipitation. The mixture was then filtered and dried to obtain a white solid powder (including...). , and The yield was 95.1%.

[0038] Example 2 Referring to Example 1, the difference is that the 5% ammonium persulfate solution was replaced with 5% sodium persulfate, and the product yield was 94.5%.

[0039] Example 3 Referring to Example 1, the difference is that 252g of 5% ammonium persulfate solution was replaced with 250g of 5% hydrogen peroxide, and the product yield was 96.2%.

[0040] Example 4 Referring to Example 1, the difference is that the precipitation reaction temperature was 80°C and the time was 5 hours, and the product yield was 93.0%.

[0041] The preparation method described in this invention can effectively control the generation of impurities, with impurities less than 1%, greatly improving purity. At the same time, the mother liquor solution can be effectively recycled and reused, significantly reducing energy consumption and environmental pollution, achieving the development trend of green and environmentally friendly composite green chemistry.

[0042] Application Example 1 Polyamide PA66 and a compound antioxidant (the compound antioxidant accounts for 0.5% of the mass of polyamide PA66, and antioxidant 168 and antioxidant 1010 are mixed in a 1:1 mass ratio) were mixed with the alkyl aluminum hypophosphite obtained in Examples 1-4 in a Banbury mixer at 50 rpm. The temperature was set at 280°C, and after 5 minutes, the mixture was removed, cooled, and dried. The mixture was then filled into a mold, preheated in a flat vulcanizing machine at 280°C for 10 minutes, held at 10 MPa for 5 minutes, and then cold-pressed. After cooling, samples were cut and tested.

[0043] The flame retardancy rating of the 1.6 mm sample was tested using the GB / 8624 method, and the results are shown in Table 1.

[0044] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing alkyl aluminum hypophosphite, characterized in that, Includes the following steps: An alkali metal hypophosphite salt, a free radical initiator, and water are mixed and then sequentially introduced into butene for butylation, propylene for propylation, and ethylene for ethylation to obtain an aqueous solution of an alkyl alkali metal hypophosphite salt. An aqueous solution of the alkyl hypophosphite alkali metal salt and a water-soluble aluminum salt are mixed and a precipitation reaction is carried out to obtain the alkyl hypophosphite aluminum.

2. The preparation method according to claim 1, characterized in that, The free radical initiator includes one or more of ammonium persulfate, sodium persulfate, hydrogen peroxide, performic acid, and peracetic acid.

3. The preparation method according to claim 1, characterized in that, The molar ratio of the hypophosphite alkali metal salt to the free radical initiator is (100~150):

1.

4. The preparation method according to claim 1, characterized in that, The molar ratio of the alkali metal hypophosphite to butene is 1:(0~0.2), and is not 0; The butylation reaction is carried out at a pressure of 0~0.4MPa, and the pressure is not 0; the temperature of the butylation reaction is 100~130℃, and the time is 1~2h.

5. The preparation method according to claim 1, characterized in that, The molar ratio of the alkali metal hypophosphite to propylene is 1:(0~0.2), and is not 0; The propylation reaction is carried out at a pressure of 0~0.7 MPa, and the pressure is not 0; the temperature of the propylation reaction is 100~120℃, and the time is 1~2h.

6. The preparation method according to claim 1, characterized in that, The molar ratio of the alkali metal hypophosphite to ethylene is 1:(0~0.8), and is not 0; The ethylation reaction is carried out at a pressure of 0.8~1.0 MPa; the temperature of the ethylation reaction is 90~100℃, and the time is 2~4h.

7. The preparation method according to claim 1, characterized in that, The water-soluble aluminum salt is one or more of aluminum sulfate, aluminum nitrate, aluminum hydroxide, and alum; The molar ratio of the alkyl hypophosphite in the aqueous solution of the water-soluble aluminum salt and the alkyl hypophosphite is (1.1~2):

6.

8. The preparation method according to claim 1, characterized in that, The precipitation reaction is carried out at a temperature of 50-100℃, a pH of 2-6, and a time of 2-4 hours.

9. The alkyl aluminum hypophosphite prepared by the preparation method according to any one of claims 1 to 8, characterized in that, Including the alkyl aluminum hypophosphite structure shown in formula a, the alkyl aluminum hypophosphite structure shown in formula b, and the alkyl aluminum hypophosphite structure shown in formula c; Formula a; Formula b; Formula c.

10. The application of the alkyl aluminum hypophosphite according to claim 9 in the field of nylon flame retardancy.

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