A preparation method of hydrolysis-resistant TCPP flame retardant

Abstract

The invention provides a method for preparing a hydrolysis-resistant TCPP flame retardant. The method uses an activated carbon-supported modified Lewis acid catalyst to catalyze the reaction of phosphorus oxychloride and propylene oxide to generate a TCPP flame retardant. The method of the invention can increase the content of tri-(2-chloroisopropyl) phosphate in the TCPP product to 85-95wt%, and the mass ratio of tri-(2-chloroisopropyl) phosphate to di-(2-chloroisopropyl) (2-chloropropyl) phosphate is greater than 7, which effectively improves the hydrolysis resistance of the TCPP flame retardant, and the full process yield of the TCPP product is more than 95%.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical engineering, and particularly relates to a method for preparing a hydrolysis-resistant TCPP flame retardant. Background Art

[0002] TCPP is an organic phosphate flame retardant with the chemical name tris(2-chloropropyl) phosphate. It is used as an additive flame retardant and is widely used in polyurethane soft foam, rigid foam plastics, epoxy resin, phenolic resin and other polymer materials. It has significant flame retardant effect and certain plasticizing effect.

[0003] The industrial preparation method of TCPP is well known to those skilled in the art, that is, phosphorus oxychloride and propylene oxide are used as raw materials and synthesized by reaction under Lewis acid catalysis. The TCPP prepared by the above method has the following four isomeric structures:

[0004]

[0005] (a) Tris-(2-chloroisopropyl) phosphate

[0006]

[0007] (b) Di-(2-chloroisopropyl)(2-chloropropyl) phosphate

[0008]

[0009] (c) Di-(2-chloropropyl) (2-chloroisopropyl) phosphate

[0010]

[0011] (d) Tris-(2-chloropropyl) phosphate

[0012] The molecular structures of the above four TCPP isomers contain different proportions of (2-chloroisopropyl) and (2-chloropropyl) groups. Among them, the (2-chloroisopropyl) group has a relatively large steric hindrance due to its branched structure, which is not conducive to the attack of water molecules and the occurrence of hydrolysis reaction.

[0013] The hydrolysis of TCPP will lead to an increase in the acid value of the product, affecting the downstream application and shelf life of the product. Therefore, hydrolysis resistance is an important indicator of TCPP products. In the molecular structure of each TCPP isomer, there are (2-chloroisopropyl) and (2-chloropropyl) groups respectively. Compared with (2-chloropropyl), (2-chloroisopropyl) has a larger steric hindrance effect because of its branched structure, which can effectively hinder the attack of water molecules, so it is not easy to undergo hydrolysis reaction. In the above isomers (a) and (b), the (2-chloroisopropyl) group accounts for a relatively higher proportion, and its hydrolysis resistance is better than that of isomers (c) and (d). Therefore, in theory, the higher the proportion of isomers (a) and (b) in TCPP products, the better the hydrolysis resistance of the product.

[0014] CN101235050 reports that in a TCPP product prepared using aluminum chloride as a catalyst, the content of isomer (a) can be increased to 70-80 wt%, and the ratio of isomer (a) to isomer (b) is greater than 4. However, it does not mention that a high ratio of isomers (a) to (b) is beneficial to the hydrolysis resistance of TCPP.

[0015] CN103408584 reports that in the post-processing process of TCPP crude product, hydrolysis treatment is first carried out under acidic conditions, isomers (b), (c), and (d) are selectively partially hydrolyzed, and then removed by washing, thereby increasing the proportion of isomer (a) in the product and improving the hydrolysis resistance of the TCPP product. Although the above method can obtain a highly hydrolysis-resistant TCPP product, it will greatly reduce the product yield, increase production costs, and reduce product profits.

[0016] Therefore, in view of the problems existing in the prior art, it is very necessary to develop a preparation method that can ensure a high product yield and greatly improve the hydrolysis resistance of the product. Summary of the invention

[0017] The purpose of the present invention is to provide a method for preparing a hydrolysis-resistant TCPP flame retardant. The flame retardant prepared by the method has significantly improved hydrolysis resistance.

[0018] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solution:

[0019] A method for preparing a hydrolysis-resistant TCPP flame retardant, the method comprising the following steps:

[0020] S1: adding Lewis acid and 1,4-naphthalene dicarboxylic acid into a solvent, adding activated carbon, standing, drying, and calcining to prepare an activated carbon-supported modified Lewis acid catalyst;

[0021] S2: The supported catalyst of S1 is uniformly dispersed in phosphorus oxychloride, and propylene oxide is introduced into the reaction to obtain a crude flame retardant;

[0022] S3: The crude flame retardant product of S2 is filtered, alkali washed, water washed and dehydrated to obtain the target flame retardant product.

[0023] In some embodiments, in the preparation process of the supported modified Lewis acid catalyst, 1,4-naphthalene dicarboxylic acid is specifically selected to react with anhydrous magnesium chloride and (or) anhydrous zinc chloride to obtain a complex, and because the naphthalene structure is introduced into the molecule, it has a higher selectivity for tri-(2-chloroisopropyl) phosphate and di-(2-chloroisopropyl) (2-chloropropyl) phosphate. The method of the present invention can increase the content of tri-(2-chloroisopropyl) phosphate in the TCPP product to 85% to 95wt%, and the mass ratio of tri-(2-chloroisopropyl) phosphate to di-(2-chloroisopropyl) (2-chloropropyl) phosphate is greater than 7, effectively improving the hydrolysis resistance of the TCPP flame retardant.

[0024] In the present invention, the Lewis acid described in S1 is a chloride of a transition metal, preferably one or more of anhydrous magnesium chloride, anhydrous zinc chloride, anhydrous aluminum chloride, and anhydrous ferric chloride, more preferably anhydrous magnesium chloride and / or anhydrous zinc chloride; preferably, the mass ratio of 1,4-naphthalene dicarboxylic acid to Lewis acid is (0.1-1.0):1, preferably (0.2-0.8):1.

[0025] In the present invention, the solvent described in S1 is a saturated aliphatic alcohol of C1 to C4, preferably one or more of methanol, ethanol, and isopropanol, and more preferably ethanol; preferably, the mass fraction of the solvent is 60 to 80%, calculated as an ethanol solution containing Lewis acid and 1,4-naphthalene dicarboxylic acid.

[0026] In the present invention, the mass ratio of the Lewis acid to the activated carbon in S1 is (0.1-0.8):1, preferably (0.3-0.6):1.

[0027] In the present invention, the standing time in S1 is 5-10 hours.

[0028] In the present invention, the drying in S1 is drying in a rotary kiln at 80-120°C.

[0029] In the present invention, the calcination in S1 is calcination at 200-300°C for 3-5h.

[0030] In the present invention, the mass ratio of Lewis acid to phosphorus oxychloride in the supported catalyst described in S2 is (0.001-0.005):1, preferably (0.002-0.004):1.

[0031] In the present invention, the molar ratio of propylene oxide to phosphorus oxychloride in S2 is (3.01-3.05):1, preferably (3.02-3.04):1.

[0032] In the present invention, the reaction temperature of phosphorus oxychloride and propylene oxide in S2 is 30-80°C, preferably 40-60°C.

[0033] In the present invention, the alkali washing in S3 uses a 3-5wt% sodium hydroxide aqueous solution, the amount of alkali solution used is 20-30wt% of the quality of the crude flame retardant, and the alkali washing temperature is 50-70°C.

[0034] In the present invention, the water washing in S3 uses deionized water, preferably the amount of deionized water is 10-20wt% of the crude flame retardant quality, and the water washing temperature is 50-70°C.

[0035] In the present invention, the dehydration temperature in S3 is 90-110° C., and the vacuum degree is 2-5 KPaA.

[0036] Another object of the present invention is to provide a hydrolysis-resistant TCPP flame retardant.

[0037] A hydrolysis-resistant TCPP flame retardant is prepared according to the above method, wherein the flame retardant is a mixture of TCPP isomer products obtained by reacting phosphorus oxychloride with propylene oxide. Schematically, the mixture has the following structures (a) to (d);

[0038]

[0039] (a) Tris-(2-chloroisopropyl) phosphate

[0040]

[0041] (b) Di-(2-chloroisopropyl)(2-chloropropyl) phosphate

[0042]

[0043] (c) Di-(2-chloropropyl) (2-chloroisopropyl) phosphate

[0044]

[0045] (d) Tris-(2-chloropropyl) phosphate

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] (1) The method of the present invention can increase the content of tri-(2-chloroisopropyl) phosphate in the TCPP product to 85% to 95% by weight, and the mass ratio of tri-(2-chloroisopropyl) phosphate to di-(2-chloroisopropyl) (2-chloropropyl) phosphate is greater than 7, thereby effectively improving the hydrolysis resistance of the TCPP flame retardant;

[0048] (2) The method of the present invention has a full-process yield of more than 95%. Under the condition of ensuring a high yield, a highly hydrolysis-resistant TCPP product can be prepared without additional processes;

[0049] (3) The catalyst preparation process of the present invention is simple. After the reaction is completed, the catalyst can be separated from the reaction liquid by simple filtration, which greatly reduces the large amount of process wastewater generated by treating the catalyst and effectively reduces production costs. DETAILED DESCRIPTION

[0050] The present invention is further described below by means of specific examples. The examples described in the present invention are only used to illustrate the present invention and do not limit the scope of the present invention.

[0051] 1. Analysis and experimental methods:

[0052] Analysis of the content of each isomer in TCPP: gas chromatography area normalization method (GC), instrument: Agilent 7980:

[0053] Gas chromatography analysis conditions

[0054]

[0055] TCPP acid value determination: Test according to HG / T2708.

[0056] TCPP hydrolysis resistance test method description:

[0057] Add 100 g TCPP and 10 g deionized water into a four-necked bottle, stir and heat to 60°C, keep warm and stir continuously for 7 days, take samples every 24 hours to analyze the acid value of the product, the higher the acid value, the worse the hydrolysis resistance of the product.

[0058] (II) Sources of raw materials and reagents in various embodiments of the present invention:

[0059] Anhydrous magnesium chloride: 99.9%, Aladdin

[0060] Anhydrous zinc chloride: 99.95%, Aladdin

[0061] Anhydrous aluminum chloride: AR, 99%, Aladdin

[0062] Anhydrous ferric chloride: 98%, Aladdin

[0063] 1,4-Naphthalene dicarboxylic acid: 95%, Aladdin

[0064] Phosphorus oxychloride: 99.5%, Yanfeng Technology

[0065] Propylene oxide: >99.5%, Wanhua Chemical

[0066] Activated carbon: AR≥100 mesh, Aladdin

[0067] Unless otherwise specified, other raw materials and reagents were purchased from commercial sources.

[0068] Example 1

[0069] Synthesis of activated carbon supported catalyst:

[0070] Weigh 6.01 g of anhydrous magnesium chloride and 3.16 g of 1,4-naphthalenedicarboxylic acid and add them to 21.38 g of anhydrous ethanol. After mixing evenly, weigh 15 g of activated carbon and add it to the above solution. After fully stirring, let it stand for 8 hours, dry it in a rotary kiln at 100° C. until the mass is constant, and calcine it at 270° C. for 4 hours to obtain 19.3 g of supported modified Lewis acid catalyst A, with an anhydrous magnesium chloride loading of 17.38%;

[0071] TCPP flame retardant synthesis and post-treatment:

[0072] 154.1g of phosphorus oxychloride (purity 99.5%) and 2.6g of catalyst A were added to a four-necked flask, and the temperature was slowly raised to 50°C. 176.9g of propylene oxide was added dropwise to the flask, and the reaction temperature was controlled at 50-55°C (the reaction was a strong exothermic process during the PO addition stage, and it was difficult to control the reaction temperature to be stable in both small tests and industrialization, and it was generally controlled within a certain range; the temperature was relatively stable during the insulation stage and could be controlled at a relatively stable value, the same below). After the propylene oxide addition was completed, the insulation reaction was continued for 3h to obtain 333.6g of crude TCPP;

[0073] The crude TCPP product was filtered through a sand core funnel, 83.4 g of a 5 wt% sodium hydroxide aqueous solution was added to the filtrate, stirred at 60°C for 0.5 h, and allowed to stand for stratification. 50.0 g of deionized water was added to the organic phase after alkali washing, stirred at 60°C for 0.5 h, and allowed to stand for stratification. The organic phase was dehydrated at 100°C and a vacuum degree of 3 KPaA for 1 h to obtain pure TCPP. The isomer composition and acid value of the product were tested, and the results are listed in Table 1. The results of the hydrolysis resistance test are listed in Table 2.

[0074] Example 2

[0075] Synthesis of activated carbon supported catalyst:

[0076] Weigh 6 g of anhydrous zinc chloride and 5.05 g of 1,4-naphthalenedicarboxylic acid and add them to 16.58 g of anhydrous ethanol. After mixing evenly, weigh 10 g of activated carbon and add it to the above solution. After fully stirring, let it stand for 6 hours, dry it in a rotary kiln at 90° C. until the mass is constant, and calcine it at 220° C. for 5 hours to obtain 16.8 g of supported modified Lewis acid catalyst B, with an anhydrous zinc chloride loading of 19.95%;

[0077] TCPP flame retardant synthesis and post-treatment:

[0078] 154.1g of phosphorus oxychloride (purity 99.5%) and 1.5g of catalyst B were added to a four-necked flask, and the temperature was slowly raised to 40°C. 176.3g of propylene oxide was added dropwise to the flask, and the reaction temperature was controlled at about 40-45°C. After the addition of propylene oxide was completed, the reaction was continued for 3h at the temperature to obtain 331.9g of crude TCPP;

[0079] The crude TCPP product was filtered through a sand core funnel, 83.0 g of a 5 wt% sodium hydroxide aqueous solution was added to the filtrate, stirred at 60°C for 0.5 h, and allowed to stand for stratification. 49.8 g of deionized water was added to the organic phase after alkali washing, stirred at 60°C for 0.5 h, and allowed to stand for stratification. The organic phase was dehydrated at 100°C and a vacuum degree of 3 KPaA for 1 h to obtain pure TCPP. The isomer composition and acid value of the product were tested, and the results are listed in Table 1. The results of the hydrolysis resistance test are listed in Table 2.

[0080] Example 3

[0081] Synthesis of activated carbon supported catalyst:

[0082] Weigh 6.01 g of anhydrous magnesium chloride and 1.26 g of 1,4-naphthalenedicarboxylic acid and add them to 29.08 g of anhydrous ethanol. After mixing evenly, weigh 20 g of activated carbon and add it to the above solution. After fully stirring, let it stand for 8 hours, dry it in a rotary kiln at 110° C. until the mass is constant, and calcine it at 290° C. for 3 hours to obtain 21.8 g of supported modified Lewis acid catalyst C, with an anhydrous magnesium chloride loading of 15.40%;

[0083] TCPP flame retardant synthesis and post-treatment:

[0084] 154.1 g of phosphorus oxychloride (purity 99.5%) and 4.0 g of catalyst C were added into a four-necked flask, and the temperature was slowly raised to 60°C. 177.5 g of propylene oxide was added dropwise into the flask, and the reaction temperature was controlled at about 60-65°C. After the addition of propylene oxide was completed, the reaction was continued at the temperature for 3 h to obtain 335.5 g of crude TCPP;

[0085] The crude TCPP product was filtered through a sand core funnel, 83.9 g of a 5 wt% sodium hydroxide aqueous solution was added to the filtrate, the mixture was stirred at 60°C for 0.5 h, and the mixture was allowed to stand for stratification. 50.3 g of deionized water was added to the organic phase after alkali washing, the mixture was stirred at 60°C for 0.5 h, and the mixture was allowed to stand for stratification. The organic phase was dehydrated at 100°C and a vacuum degree of 3 KPaA for 1 h to obtain pure TCPP. The isomer composition and acid value of the product were tested, and the results are listed in Table 1. The results of the hydrolysis resistance test are listed in Table 2.

[0086] Example 4

[0087] Synthesis of activated carbon supported catalyst:

[0088] Weigh 6.06 g of anhydrous aluminum chloride and 6.32 g of 1,4-naphthalenedicarboxylic acid and add them to 49.51 g of anhydrous methanol. After mixing evenly, weigh 60 g of activated carbon and add them to the above solution. After fully stirring, let it stand for 8 hours, dry it in a rotary kiln at 100° C. until the mass is constant, and calcine it at 270° C. for 4 hours to obtain 57.9 g of supported modified Lewis acid catalyst D, with an anhydrous zinc chloride loading of 5.80%;

[0089] TCPP flame retardant synthesis and post-treatment:

[0090] 154.1 g of phosphorus oxychloride (purity 99.5%) and 13.2 g of catalyst D were added to a four-necked flask, and the temperature was slowly raised to 30°C. 175.7 g of propylene oxide was added dropwise to the flask, and the reaction temperature was controlled at about 30-35°C. After the addition of propylene oxide was completed, the reaction was continued for 3 hours to obtain 343.0 g of crude TCPP;

[0091] The crude TCPP product was filtered through a sand core funnel, 85.7 g of a 5 wt% sodium hydroxide aqueous solution was added to the filtrate, the mixture was stirred at 60°C for 0.5 h, and the mixture was allowed to stand for stratification. 51.4 g of deionized water was added to the organic phase after alkali washing, the mixture was stirred at 60°C for 0.5 h, and the mixture was allowed to stand for stratification. The organic phase was dehydrated at 100°C and a vacuum degree of 3 KPaA for 1 h to obtain pure TCPP. The isomer composition and acid value of the product were tested, and the results are listed in Table 1. The results of the hydrolysis resistance test are listed in Table 2.

[0092] Example 5

[0093] Synthesis of activated carbon supported catalyst:

[0094] Weigh 6.12 g of anhydrous ferric chloride and 0.63 g of 1,4-naphthalenedicarboxylic acid and add them to 27.02 g of anhydrous ethanol. After mixing evenly, weigh 7.5 g of activated carbon and add them to the above solution. After fully stirring, let it stand for 8 hours, dry it in a rotary kiln at 100° C. until the mass is constant, and calcine it at 270° C. for 4 hours to obtain 11.4 g of supported modified Lewis acid catalyst E, with an anhydrous zinc chloride loading of 29.47%;

[0095] TCPP flame retardant synthesis and post-treatment:

[0096] 154.1 g of phosphorus oxychloride (purity 99.5%) and 0.5 g of catalyst E were added to a four-necked flask, and the temperature was slowly raised to 80°C. 178.0 g of propylene oxide was added dropwise to the flask, and the reaction temperature was controlled at about 80-85°C. After the addition of propylene oxide was completed, the reaction was continued at the temperature for 3 h to obtain 332.6 g of crude TCPP;

[0097] The crude TCPP product was filtered through a sand core funnel, 83.2 g of a 5 wt% sodium hydroxide aqueous solution was added to the filtrate, stirred at 60°C for 0.5 h, and allowed to stand for stratification. 49.9 g of deionized water was added to the organic phase after alkali washing, stirred at 60°C for 0.5 h, and allowed to stand for stratification. The organic phase was dehydrated at 100°C and a vacuum degree of 3 KPaA for 1 h to obtain pure TCPP. The isomer composition and acid value of the product were tested, and the results are listed in Table 1. The results of the hydrolysis resistance test are listed in Table 2.

[0098] Comparative Example 1

[0099] Compared with Example 1, the catalyst was replaced with AlCl3, and the other reaction conditions were exactly the same.

[0100] 154.1g of phosphorus oxychloride (purity 99.5%) and 0.47g of catalyst AlCl3 were added into a four-necked flask, and the temperature was slowly raised to 50°C. 176.9g of propylene oxide was added dropwise into the flask, and the reaction temperature was controlled at about 50-55°C. After the addition of propylene oxide was completed, the reaction was continued for 3h at the temperature, and 331.47g of crude TCPP was obtained;

[0101] To the crude product, 82.9 g of 5% aqueous sodium hydroxide solution was added, the mixture was stirred at 60° C. for 0.5 h, and the mixture was allowed to stand for stratification. To the organic phase after alkali washing, 49.7 g of deionized water was added, the mixture was stirred at 60° C. for 0.5 h, and the mixture was allowed to stand for stratification. The organic phase was dehydrated at 100° C. and a vacuum degree of 3 KPaA for 1 h to obtain pure TCPP. The isomer composition and acid value of the product were tested, and the results are listed in Table 1. The results of the hydrolysis resistance test are listed in Table 2.

[0102] Table 1 Experimental results of Examples 1 to 5 and Comparative Example 1

[0103]

[0104] Table 2 Hydrolysis resistance test results of products of Examples 1 to 5 and Comparative Example 1

[0105] Hydrolysis time (days) 0 1 2 3 4 5 6 7 Example 1 0.015 0.017 0.019 0.020 0.022 0.024 0.025 0.027 Example 2 0.016 0.018 0.020 0.021 0.023 0.025 0.026 0.029 Example 3 0.015 0.017 0.019 0.020 0.023 0.024 0.025 0.027 Example 4 0.015 0.017 0.019 0.020 0.022 0.024 0.025 0.028 Example 5 0.017 0.019 0.021 0.022 0.024 0.025 0.027 0.029 Comparative Example 1 0.027 0.12 0.25 0.39 0.68 0.81 1.03 1.65

Claims

1. A method for preparing a hydrolysis-resistant TCPP flame retardant, characterized in that: The method comprises the following steps: S1: adding Lewis acid and 1,4-naphthalene dicarboxylic acid into a solvent, adding activated carbon, standing, drying, and calcining to prepare an activated carbon-supported modified Lewis acid catalyst; S2: The supported catalyst of S1 is uniformly dispersed in phosphorus oxychloride, and propylene oxide is introduced into the reaction to obtain a crude flame retardant; S3: The crude flame retardant product of S2 is filtered, alkali washed, water washed, and dehydrated to obtain the target flame retardant product; Wherein, the Lewis acid described in S1 is one or more of anhydrous magnesium chloride, anhydrous zinc chloride, anhydrous aluminum chloride, and anhydrous ferric chloride.

2. The method according to claim 1, characterized in that: The solvent in S1 is a C1-C4 saturated aliphatic alcohol; And / or, the mass ratio of the Lewis acid to the activated carbon in S1 is (0.1-0.8):1; And / or, the standing time in S1 is 5-10h; And / or, the drying in S1 is drying in a rotary kiln at 80-120° C.; And / or, the calcination in S1 is calcination at 200-300° C. for 3-5 hours.

3. The method according to claim 2, characterized in that: The Lewis acid in S1 is anhydrous magnesium chloride and / or anhydrous zinc chloride; The mass ratio of 1,4-naphthalene dicarboxylic acid to Lewis acid is (0.1-1.0):1; And / or, the solvent in S1 is one or more of methanol, ethanol, and isopropanol; The mass fraction of the solvent is 60 to 80%, calculated as a solution containing Lewis acid and 1,4-naphthalene dicarboxylic acid; And / or, the mass ratio of the Lewis acid to the activated carbon in S1 is (0.3-0.6):

1.

4. The method according to claim 3, characterized in that: The mass ratio of 1,4-naphthalene dicarboxylic acid to Lewis acid in S1 is (0.2-0.8):1; And / or, the solvent in S1 is ethanol.

5. The method according to claim 1 or 2, characterized in that: The mass ratio of Lewis acid to phosphorus oxychloride in the supported catalyst S2 is (0.001-0.005):1; And / or, the molar ratio of propylene oxide to phosphorus oxychloride in S2 is (3.01-3.05):1; And / or, the reaction temperature of phosphorus oxychloride and propylene oxide in S2 is 30-80°C.

6. The method according to claim 5, characterized in that: The mass ratio of Lewis acid to phosphorus oxychloride in the supported catalyst S2 is (0.002-0.004):1; And / or, the molar ratio of propylene oxide to phosphorus oxychloride in S2 is (3.02-3.04):1; And / or, the reaction temperature of phosphorus oxychloride and propylene oxide in S2 is 40-60°C.

7. The method according to claim 1, characterized in that: The alkali washing in S3 adopts 3-5wt% sodium hydroxide aqueous solution, the amount of alkali solution is 20-30wt% of the quality of the crude flame retardant, and the alkali washing temperature is 50-70°C; And / or, the washing in S3 uses deionized water; And / or, the dehydration temperature in S3 is 90-110° C., and the vacuum degree is 2-5 KPa absolute pressure.

8. The method according to claim 7, characterized in that: The amount of deionized water in S3 is 10-20wt% of the crude flame retardant quality, and the water washing temperature is 50-70°C.

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