Preparation method of high-content tris-(2-chloroisopropyl) phosphate flame retardant

Abstract

The present invention belongs to the field of chemical engineering technology, particularly to the field of C07F9 / 09, and more specifically relates to a preparation method of a high-content tris-(2-chloroisopropyl) phosphate flame retardant. Mainly, during the reaction of phosphorus oxychloride with propylene oxide, an appropriate amount of phosphorus oxychloride is used as the bottom layer, a Lewis acid is used as the catalyst, and the crude TCPP is synthesized by a double-drop addition method at a certain temperature. After the crude product undergoes processes such as alkali washing, water washing, dehydration, and filtration, TCPP is obtained, and the content of TCPP reaches more than 83%. By optimizing the reaction process conditions and flow, the content of the main product of TCPP is greatly increased in the present invention, solving problems such as a large acid value and easy hydrolysis of the product caused by instability factors during the use of TCPP. At the same time, in the post-treatment process, the alkali washing water and water washing water are recycled, reducing the amount of washing water used and lowering the generation and treatment costs of wastewater.

Description

Technical Field

[0001] The present invention belongs to the field of chemical engineering technology, particularly to the field of C07F9 / 09, and more specifically relates to a preparation method of a high-content tris(2-chloroisopropyl) phosphate flame retardant. Background Art

[0002] TCPP (Tris(1-Chloro-2-Propyl)Phosphate), whose full name is tris(2-chloroisopropyl) phosphate and CAS number is 13674-84-5, is an additive low-molecular-weight halogen phosphorus-based flame retardant. It has unique properties such as flame retardancy, plasticization, and antistatic properties, and belongs to a fine chemical product with relatively high cost performance. TCPP is mainly used for the flame retardancy of polyvinyl chloride, polystyrene, phenolic resin, propylene resin, rubber, and coatings, and is also widely used in polyurethane flexible foams, rigid foams, and plastic products.

[0003] TCPP is mainly prepared by the ring-opening reaction of phosphorus oxychloride and propylene oxide under the action of Lewis acid catalysts such as anhydrous aluminum chloride and titanium tetrachloride to obtain a crude product, and the crude product is then synthesized into a TCPP finished product through post-treatment processes such as alkali washing, water washing, dehydration, and filtration.

[0004] Currently, TCPP is also widely used as a formulation raw material for combined polyethers. However, due to long-term storage, TCPP may undergo hydrolysis, resulting in an increase in the acid value of TCPP and a decrease in quality. Acidic substances such as phosphorus oxychloride produced by hydrolysis will undergo an acid-base neutralization reaction with the basic amine catalysts in the polyether, and the stability of the combined polyether system is damaged. Therefore, the hydrolysis resistance of TCPP prepared by the existing technology has not been fully developed. At the same time, the amount of washing water required in the post-treatment process of crude TCPP is too large, and the phosphorus content and organic matter content in the washing wastewater exceed the standard, greatly increasing the workload of wastewater treatment.

[0005] The prior arts CN102775439A, US3100220A, and CN111892108B briefly describe the use of different Lewis acid catalysts to synthesize TCPP, but do not mention the content of various isomers in the synthesized TCPP, nor do they mention how to improve the hydrolysis resistance of TCPP by reducing the easily hydrolyzable components in the isomers; the prior art CN103408584B briefly describes the proportion of various isomers in the TCPP product and mentions how to reduce the isomer components to improve the hydrolysis resistance of TCPP, but the post-treatment operation steps are cumbersome, the amount of equipment used is large, the cost is high, and it is difficult to continuously achieve industrial mass production. Summary of the Invention

[0006] The present invention aims to provide a preparation method of a high-content tris-(2-chloroisopropyl) phosphate flame retardant, so as to solve the problem that in the prior art, TCPP undergoes hydrolysis reaction during long-term storage, resulting in an increase in the acid value of TCPP and a decline in quality, and to ensure the high hydrolysis stability of TCPP products.

[0007] The preparation method of a high-content tris-(2-chloroisopropyl) phosphate flame retardant described in the present invention is realized through the following technical solutions:

[0008] During the reaction of phosphorus oxychloride and propylene oxide, an appropriate amount of phosphorus oxychloride and a Lewis acid catalyst are used as the bottom layer, and then the remaining phosphorus oxychloride and propylene oxide are added dropwise by a double-drop method. After the ring-opening reaction, a crude TCPP product is obtained, and TCPP is obtained after the post-treatment process of the crude product.

[0009] Preferably, the mass of the phosphorus oxychloride used as the bottom layer is 25-45% of the total mass of phosphorus oxychloride.

[0010] Preferably, the mass ratio of the total mass of phosphorus oxychloride to propylene oxide is 1:(1-1.5).

[0011] More preferably, the mass ratio of the total mass of phosphorus oxychloride to propylene oxide is 1:1.2.

[0012] Preferably, the mass of the Lewis acid is 0.1-5% of the total mass of phosphorus oxychloride.

[0013] Preferably, the Lewis acid is one or more of anhydrous aluminum chloride, titanium tetrachloride, anhydrous stannous chloride, and zinc chloride.

[0014] Preferably, the dropping temperature of the double-drop method is 35-55°C, and the dropping time is 1-3 h.

[0015] Preferably, after the remaining phosphorus oxychloride and the Lewis acid are added dropwise by the double-drop method, a heat preservation operation is carried out, and the heat preservation time is 1-3 h.

[0016] Preferably, the post-treatment steps include: alkali washing, water washing, dehydration, and filtration.

[0017] Preferably, the alkali washing water used in the alkali washing and the water washing water used in the water washing in the post-treatment adopt a circulating and nested usage method, which can reduce the amount of washing water. The first batch uses fresh alkali washing water and water washing water; the second batch uses the circulating and nested usage method, where the alkali washing water 2 is nested with the alkali washing water 1, the water washing water 1 is nested with the alkali washing water 2, the water washing water 2 is nested with the water washing water 1, and the water washing water 2 uses fresh washing water; subsequent batches are carried out in the same way.

[0018] Preferably, the concentration of the alkali washing water is a 1.5-5.0 wt% sodium hydroxide aqueous solution, and the dosage is 20-30% of the mass of the crude TCPP product.

[0019] Preferably, the amount of the washing water is 25-35% of the mass of the crude TCPP.

[0020] Beneficial effects

[0021] (1) The tris(2-chloroisopropyl) phosphate prepared by the specific preparation method in the present invention has excellent water resistance. The main reason is that the inventor of the present invention found that the hydrolysis resistance of TCPP is closely related to the content of its various components. TCPP is formed by the ring-opening reaction of propylene oxide under a Lewis acid catalyst with phosphorus oxychloride. There are four isomers, namely (I): tris(2-chloroisopropyl) phosphate; (II): bis(2-chloroisopropyl)(2-chloropropyl) phosphate; (III): bis(2-chloropropyl)(2-chloroisopropyl) phosphate; (IV): tris(2-chloropropyl) phosphate. The branched-chain structure (2-chloroisopropyl) has a larger steric hindrance effect compared to (2-chloropropyl), effectively hindering the attack of water molecules. Therefore, the molecule itself is not easily hydrolyzed, and the hydrolysis resistance is arranged as follows: (I) > (II) > (III) > (IV). The preparation method described in the present invention can improve the hydrolysis resistance of TCPP by reducing the content of (II) and (III) and increasing the relative content of (I).

[0022] (2) The TCPP prepared in the present invention has excellent hydrolysis resistance, mainly by reducing the by-products bis(2-chloroisopropyl)(2-chloropropyl) phosphate and bis(2-chloropropyl)(2-chloroisopropyl) phosphate formed by the reaction of phosphorus oxychloride containing 2-chloropropyl and propylene oxide. In addition, the inventor of the present invention found that the TCPP prepared by this preparation method also has a lower acid value and can be applied to a system containing basic substances, such as a combined polyether containing an amine catalyst, and can stably exist, playing the role of a functional flame retardant auxiliary. It solves the problems that TCPP in the combined polyether formula undergoes hydrolysis during long-term storage, resulting in an increase in acid value, a decrease in quality, and the destruction of the combined polyether.

[0023] (3) In the present invention, the post-treatment includes alkali washing, water washing, dehydration, and filtration. The washing water used in the alkali washing water and water washing adopts a circulating and recycling method, which can reduce the consumption of washing water and alkali solution, thereby effectively reducing costs and reducing pollution, and can increase the economic return.

[0024] (4) In the process of preparing TCPP by the present inventors, an appropriate amount of phosphorus oxychloride and Lewis acid are first laid as the bottom layer, and then the remaining phosphorus oxychloride and propylene oxide are added by a double-dropwise addition method. By strictly controlling the dropping time and reaction temperature, the forward reaction rate of the reaction can be effectively increased, and the side reactions in the reaction can be reduced. If the one-pot feeding method is adopted, that is, all phosphorus oxychloride, propylene oxide, and catalyst are added in one batch, since the reaction itself is an exothermic reaction, it is difficult to control the reaction rate, and the amount of by-products is relatively large, which is not conducive to the hydrolysis resistance and low acid value of the product.

[0025] (5) In the present invention, the raw materials for preparation are widely sourced, with low cost, and the preparation method is simple. The entire process does not require a large number of complex instrument and equipment process operations, can achieve continuous production, and has low pollution, realizing the recycling of raw materials, and has excellent practical application prospects. Specific Embodiments

[0026] Example 1

[0027] This embodiment provides a preparation method of a high-content tris(2-chloroisopropyl) phosphate flame retardant, specifically including the following steps: 1 kg of phosphorus oxychloride, 25% of the total mass of phosphorus oxychloride and 0.5% of anhydrous aluminum chloride based on the total mass of phosphorus oxychloride are laid as the bottom layer and stirred, the temperature is controlled at 45 - 50 °C, and the remaining phosphorus oxychloride and 1.2 kg of propylene oxide are added by a double-dropwise addition method. The dropping temperature is 50 °C, the dropping time is 2 h, and the reaction is kept warm for 1 h to obtain the crude product TCPP. Then, it is subjected to alkali washing, water washing, dehydration, and filtration to obtain TCPP. Among them, it is alkali-washed 2 times with a 2.5 wt% sodium hydroxide aqueous solution, and the mass of the alkali-washing water is 25% of the mass of the crude product TCPP, and it is water-washed 2 times, and the mass of the water-washing water is 30% of the mass of the crude product TCPP. The alkali-washing water used for alkali washing and the water-washing water used for water washing adopt a circulating and nested usage method. Alkali-washing water 1 is nested with alkali-washing water 2, alkali-washing water 2 is nested with water-washing water 1, water-washing water 1 is nested with upper water-washing water 2, and water-washing water 2 is fresh water.

[0028] Example 2

[0029] This embodiment provides a preparation method of a high-content tris(2-chloroisopropyl) phosphate flame retardant, specifically including the following steps: 1 kg of phosphorus oxychloride. 20% of the total mass of phosphorus oxychloride and 1.0% of the total mass of phosphorus oxychloride of anhydrous aluminum chloride are spread at the bottom and stirred, the temperature is controlled at 45 - 50 °C, and the remaining phosphorus oxychloride and 1.2 kg of propylene oxide are added dropwise by a double-dropwise method. The dropping temperature is 50 °C, the dropping time is 2 h, and the reaction is kept warm for 1 h to obtain the crude product TCPP. Then, it is subjected to alkali washing, water washing, dehydration, and filtration to obtain TCPP. Among them, it is alkali-washed 2 times with a 2.5 wt% sodium hydroxide aqueous solution, the mass of the alkali-washing water is 30% of the mass of the crude product TCPP, water-washed 2 times, the mass of the water-washing water is 30% of the mass of the crude product TCPP, and the alkali-washing water used for alkali washing and the water-washing water used for water washing adopt the circulating and recycling method. Alkali-washing water 1 is recycled with alkali-washing water 2, alkali-washing water 2 is recycled with water-washing water 1, water-washing water 1 is recycled with upper water-washing water 2, and water-washing water 2 is fresh water.

[0030] Example 3

[0031] The specific implementation manner of this embodiment is the same as that of Embodiment 2, the difference being that the dropping time is 3 h and the heat preservation time is 1.5 h.

[0032] Example 4

[0033] The specific implementation manner of this embodiment is the same as that of Embodiment 2, the difference being that 30% of the total mass of phosphorus oxychloride and 0.5% of the total mass of phosphorus oxychloride of anhydrous aluminum chloride are spread at the bottom and stirred.

[0034] Example 5

[0035] The specific implementation manner of this embodiment is the same as that of Embodiment 2, the difference being that the dropping time is 2 h, the heat preservation time is 2 h, and the mass concentration of the sodium hydroxide aqueous solution is 2 wt%.

[0036] Example 6

[0037] The specific implementation manner of this embodiment is the same as that of Embodiment 2, the difference being that the mass concentration of the sodium hydroxide aqueous solution is 3 wt% and the mass of the alkali-washing water is 20% of the mass of the crude product TCPP.

[0038] Example 7

[0039] The specific implementation manner of this embodiment is the same as that of Embodiment 2, the difference being that the mass concentration of the sodium hydroxide aqueous solution is 5 wt%, the mass of the alkali-washing water is 20% of the mass of the crude product TCPP, and the mass of the water-washing water is 20% of the mass of the crude product TCPP.

[0040] Example 8

[0041] The specific implementation method of this example is the same as that of Example 2, the difference is that the mass concentration of the sodium hydroxide aqueous solution is 1.5 wt%, the mass of the alkali-washing water is 30% of the mass of the crude TCPP, and the mass of the water-washing water is 30% of the mass of the crude TCPP.

[0042] Example 9

[0043] The specific implementation method of this example is the same as that of Example 1, the difference is that there is no phosphorus oxychloride bottom layer in the four-neck flask of the reaction vessel, and 1 kg of phosphorus oxychloride and 1.2 kg of propylene oxide are simultaneously added dropwise at a temperature of 50 - 60 °C.

[0044] Example 10

[0045] The specific implementation method of this example is the same as that of Example 1, the difference is that it is alkali-washed twice with an 8 wt% sodium hydroxide aqueous solution, the mass of the alkali-washing water is 30% of the mass of the crude TCPP, and it is water-washed once, and the mass of the water-washing water is 25% of the mass of the crude TCPP.

[0046] Example 11

[0047] The specific implementation method of this example is the same as that of Example 2, the difference is that there is no phosphorus oxychloride bottom layer in the four-neck flask of the reaction vessel, 1 kg of phosphorus oxychloride and 1.2 kg of propylene oxide are simultaneously added dropwise, and the dropping time of propylene oxide is 0.5 h less than that of phosphorus oxychloride.

[0048] Example 12

[0049] The specific implementation method of this example is the same as that of Example 2, the difference is that there is no phosphorus oxychloride bottom layer in the four-neck flask, the heat preservation time is 3 h, and the concentration of sodium hydroxide alkali-washing is 5.0 wt%.

[0050] Performance evaluation

[0051] The contents of various isomers of TCPP in the products obtained in Examples 1 - 12 were quantitatively analyzed by gas chromatography, and the acid value of TCPP was measured by acid-base neutralization potentiometric titration. The test results are shown in Table 1.

[0052] Table 1

[0053]

[0054]

Claims

1. A method for preparing a high-content tris-(2-chloroisopropyl) phosphate flame retardant, characterized in that: At least the following steps are included: In the reaction process of phosphorus oxychloride and propylene oxide, an appropriate amount of phosphorus oxychloride and Lewis acid catalyst are used as the bottom, and then the remaining amount of phosphorus oxychloride and propylene oxide are added dropwise by double drop method, and a TCPP crude product is obtained by ring opening reaction, and TCPP is obtained after the crude product post-treatment process; The mass of the phosphorus oxychloride as the base is 25-45% of the total mass of the phosphorus oxychloride; The dropping temperature of the double dropping method is 35-55° C., and the dropping time is 1-3 hours.

2. The method for preparing a high-content tris-(2-chloroisopropyl) phosphate flame retardant according to claim 1, characterized in that: The mass of the Lewis acid is 0.1-5% of the total mass of phosphorus oxychloride.

3. The method for preparing a high-content tris-(2-chloroisopropyl) phosphate flame retardant according to claim 2, characterized in that: The Lewis acid is one or more of anhydrous aluminum chloride, titanium tetrachloride, anhydrous tin chloride and zinc chloride.

4. The method for preparing a high-content tris-(2-chloroisopropyl) phosphate flame retardant according to claim 3, characterized in that: After the remaining phosphorus oxychloride and Lewis acid are added dropwise by the double-drop method, a heat preservation operation is performed for 1 to 3 hours.

5. The method for preparing a high-content tris-(2-chloroisopropyl) phosphate flame retardant according to claim 4, characterized in that: The post-treatment steps include: alkali washing, water washing, dehydration and filtration.

6. The method for preparing a high-content tris-(2-chloroisopropyl) phosphate flame retardant according to claim 5, characterized in that: The alkaline washing water used for alkaline washing in the post-treatment and the water washing water used for water washing are recycled. The first batch uses fresh alkaline washing water and water washing water, and the second batch adopts the recycling method. Alkaline washing water 2 uses alkaline washing water 1, water washing water 1 uses alkaline washing water 2, water washing water 2 uses water washing water 1, and water washing water 2 uses fresh washing water.

7. The method for preparing a high-content tris-(2-chloroisopropyl) phosphate flame retardant according to claim 6, characterized in that: The concentration of the alkali washing water is 1.5-5.0wt% of sodium hydroxide aqueous solution, and the amount used is 20-30% of the quality of crude TCPP.

8. The method for preparing a high-content tris-(2-chloroisopropyl) phosphate flame retardant according to claim 7, characterized in that: The amount of washing water used is 25-35% of the quality of crude TCPP.

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