Asymmetric alkyl phosphate compound, preparation method and application thereof

Abstract

The present invention provides an asymmetric alkyl phosphate compound, preparation method, and application thereof, belonging to the field of organic synthesis technology. The asymmetric alkyl phosphate compound has the following structural formula: #imgabs0# This invention synthesizes cyclohexyl-4-methoxyphenyl aluminum thiophosphate for the first time. Its structure contains the flame retardant elements sulfur, phosphorus, and aluminum. This asymmetric alkyl phosphate compound can be added to PA6 as a flame retardant to improve the flame retardancy and mechanical properties of the composite material.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic synthesis, and in particular relates to an asymmetric alkyl phosphate compound, a preparation method and an application thereof. Background Art

[0002] PA6 (Polyamide 6) is a material with excellent tensile strength, chemical resistance, impact resistance, and wear resistance. It is widely used in machinery, transportation, defense, and other fields, and is an indispensable member of the engineering plastics industry. However, due to its low content of flame-retardant elements and its rich, easily flammable carbon content, PA6 poses fire safety risks, which significantly limits its application and development in certain fields. This is particularly true in electronic and electrical products. During use, PA6 is highly susceptible to combustion and fires due to malfunctions, excessive temperatures, or high-voltage discharges. Therefore, the development of PA6 with excellent flame retardancy is urgent and necessary.

[0003] With the global environmental crisis looming, flame retardants are being developed towards lower toxicity, higher efficiency, and lower cost. Halogenated flame retardants produce large amounts of toxic gases when burned, and extensive evidence suggests that brominated flame retardants also produce large amounts of toxic substances when they decompose. This not only seriously pollutes the environment but also causes significant harm to the human body. Compared to traditional halogenated flame retardants, organophosphorus flame retardants offer advantages such as smoke suppression, low toxicity, non-corrosiveness, and excellent flame retardancy, leading to their widespread application.

[0004] Currently, the most widely used flame retardants for PA6 are alkyl hypophosphites. Among them, diethyl hypophosphite flame retardant is a typical organic hypophosphite flame retardant. Due to its high phosphorus content, it has the high flame retardant properties of phosphorus-based flame retardants, with advantages such as high flame retardancy, high decomposition temperature, and low water absorption. It has been widely used in flame-retardant polyester, flame-retardant polyamide, and flame-retardant polyurethane materials. However, the use of diethyl hypophosphite in flame-retardant polyamide has a negative impact on the mechanical properties of the composite material, which is not conducive to improving the performance of the composite material. Therefore, the development of new phosphate compounds for use in polyamide is of great significance for improving its flame retardant properties.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an asymmetric alkyl phosphate compound as a flame retardant for preparing PA6 flame retardant material in view of the deficiencies of the existing technology.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0008] The asymmetric alkyl phosphate compound has the following structural formula:

[0009]

[0010] The preparation method of an asymmetric alkyl phosphate compound comprises the following steps:

[0011] Step S1: Under an inert gas atmosphere, using Lawesson's reagent and cyclohexylmagnesium bromide as raw materials and anhydrous ether as the reaction solvent, the reaction is heated under reflux for a certain period of time, cooled in an ice bath, and then acidified with sulfuric acid. The organic phase is separated and dried to obtain a light yellow oily liquid;

[0012] Step S2: The light yellow oily liquid prepared in step S1 and aluminum nitrate are reacted in distilled water at room temperature to form a white precipitate, which is then dried to obtain the target product.

[0013] Preferably, in step S1, the molar feed ratio of Lawesson reagent to cyclohexylmagnesium bromide is 1:(1-1.5).

[0014] Preferably, in step S1, the inert gas is nitrogen, argon or helium.

[0015] Preferably, in step S1, the reaction temperature is 35-60° C., and the reaction time is 2-5 h.

[0016] Preferably, in step S1, the concentration of sulfuric acid is 4.5-5.5%, and the amount used is 50 ml or more; more preferably, the concentration of sulfuric acid is 5%, and the amount used is 50 ml.

[0017] Preferably, in step S2, the molar ratio of the light yellow oily liquid to aluminum nitrate is 3:1.

[0018] Preferably, in step S2, the amount of distilled water used is 50 ml or more, and the reaction time is 2-2.5 hours; more preferably, the amount of distilled water used is 50 ml, and the reaction time is 2 hours.

[0019] The reaction principle of the asymmetric alkyl phosphate compound of the present invention is as follows:

[0020]

[0021] The present invention also provides the use of the asymmetric alkyl phosphate compound in the preparation of PA6 flame retardant material.

[0022] The present invention also provides the use of the asymmetric alkyl phosphate compound prepared by the above preparation method in the preparation of PA6 flame retardant material.

[0023] The PA6 flame retardant material is prepared from raw materials containing the above-mentioned asymmetric alkyl phosphate compound.

[0024] Preferably, the PA6 flame retardant material is prepared from PA6 and an asymmetric alkyl phosphate compound, wherein the weight proportion of the PA6 is 75-85 parts, and the weight proportion of the asymmetric alkyl phosphate compound is 15-25 parts.

[0025] Preferably, the preparation method of the PA6 flame retardant material is to melt-extrude the uniformly mixed raw materials in parts by weight into granules using a twin-screw extruder, and then inject the granules into an injection molding machine to obtain a finished product.

[0026] Preferably, the temperature of the melt extrusion is 210-250°C.

[0027] Preferably, the injection molding temperature is 210-250°C.

[0028] Currently, there is no known asymmetric alkyl phosphate compound proposed in the present invention, namely, cyclohexyl-4-methoxyphenyl aluminum thiophosphate, nor is there a synthetic process for preparing the aforementioned phosphate compound using Lawesson reagent and cyclohexylmagnesium bromide as raw materials, nor is there a known method for using the aforementioned phosphate compound as a flame retardant to produce PA6 flame retardant materials. Therefore, for the structural formula: The phosphate compound, preparation method and application shown are all original to the present invention.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] First, the present invention synthesizes cyclohexyl-4-methoxyphenyl aluminum thiophosphate for the first time using Lawesson reagent, cyclohexylmagnesium bromide and aluminum nitrate as raw materials. The cyclohexyl-4-methoxyphenyl aluminum thiophosphate is an asymmetric alkyl phosphate compound whose structure contains sulfur, phosphorus and aluminum flame retardant elements at the same time, thereby enhancing the flame retardant performance.

[0031] Secondly, the present invention uses Lawesson reagent and cyclohexylmagnesium bromide as starting raw materials for synthesis, the raw materials are easily available, the process flow is simple, the product can be obtained in two steps, and the product is easy to separate, the reaction conditions are mild, and the product is easy to industrialize and produce.

[0032] Furthermore, the present invention, for the first time, incorporates synthesized cyclohexyl-4-methoxyphenyl aluminum thiophosphate as a flame retardant into PA6, producing a PA6 flame-retardant material with excellent flame retardancy. Compared to existing technologies, the PA6 flame-retardant material prepared according to the composition and proportions provided by the present invention exhibits significantly improved flame retardancy, achieving vertical combustion performance of FV-0 and successfully passing various glow-wire temperature tests. More importantly, while improving flame retardancy, the mechanical properties of the composite material are also maintained, with significant increases in tensile strength and impact strength, achieving remarkable technical results. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 is the infrared spectrum of the target product C1 prepared in Example 1;

[0035] Figure 2 is the H NMR spectrum of the target product C1 prepared in Example 1;

[0036] Figure 3 This is the carbon NMR spectrum of the target product C1 prepared in Example 1. DETAILED DESCRIPTION

[0037] In order to better understand the present invention, the content of the present invention is further clearly set forth below in conjunction with the examples, but the protection content of the present invention is not limited to the following examples. In the following description, a large number of specific details are provided in order to provide a more thorough understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details.

[0038] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of steps, operations, devices, components and / or combinations thereof.

[0039] In all examples shown and discussed herein, any specific values should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0040] Unless otherwise specified, all raw materials are derived from commercially available products and do not contain other unspecified components except inevitable impurities.

[0041] In the following examples, room temperature refers to 23±2°C.

[0042] Example 1: Preparation of target product C1

[0043] To a 500 ml four-necked flask equipped with a thermometer, a nitrogen inlet device, a 100 ml constant pressure dropping funnel, a magnet, and a reflux condenser were added 12.13 g (0.03 mol) of Lawesson's reagent, 5.62 g (0.03 mol) of cyclohexylmagnesium bromide, and 50 ml of anhydrous ether. The reaction temperature was controlled at 35°C and allowed to react for 5 hours. The mixture was then cooled in an ice bath and then acidified with 50 ml of 5% sulfuric acid. The organic phase was separated and dried over anhydrous sodium sulfate to obtain a light yellow oily liquid A.

[0044] A pale yellow oily liquid A (8.58 g, 0.03 mol) and aluminum nitrate (2.13 g, 0.01 mol) were reacted in 50 ml of distilled water at room temperature for 2 hours to obtain a white precipitate. The precipitate was washed and dried to obtain the target product C1 with a yield of 97% (based on aluminum nitrate).

[0045] The target product C1 was tested using Nicoleti S10 infrared spectrometer, and the test results are as follows: Figure 1 shown. Figure 1 Data shows: 2800-3000cm -1 The broad peak at 3050 cm is the characteristic absorption peak of methylene and methyl. -1 and 3016cm -1 The absorption peak of CH stretching vibration of benzene ring is at 1585-1600cm -1 The stretching vibration peak of the benzene ring skeleton can be observed at 1610 cm -1 The left and right peaks are P=S absorption peaks, 2600-2550cm -1 The weak peak is the SH absorption peak, which indicates that the molecular structure of the target product C1 includes the skeleton coordination monomers in each raw material.

[0046] The target product C1 was tested by nuclear magnetic resonance hydrogen spectrum, and the test results were as follows Figure 2 shown. Figure 2 The data show that the characteristic peak at δ = 8.16-6.91ppm corresponds to the hydrogen on the benzene ring; δ = 3.83ppm corresponds to the hydrogen on -O-CH3; δ = 0.8-2.3ppm corresponds to the hydrogen on H2C-C on the cyclohexyl group.

[0047] The target product C1 was tested by carbon nuclear magnetic resonance spectroscopy, and the test results were as follows: Figure 3 shown. Figure 3 The data show that the characteristic peaks with δ above 110 ppm correspond to the carbon on the benzene ring, and the characteristic peaks with δ below 58 ppm correspond to the carbon on the cyclohexyl group.

[0048] The target product C1 was subjected to elemental analysis, and the detection result was: m / e: 882.13 (C, 163.56; H, 17.04; O, 16.77; P, 32.46; S, 67.17; Al, 27.05).

[0049] Based on the above test results, it can be determined that the target product C1 is cyclohexyl-4-methoxyphenyl aluminum thiophosphate.

[0050] Example 2: Preparation of target product C1

[0051] To a 500 ml four-necked flask equipped with a thermometer, a nitrogen inlet device, a 100 ml constant pressure dropping funnel, a magnet, and a reflux condenser were added 12.13 g (0.03 mol) of Lawesson's reagent, 5.62 g (0.03 mol) of cyclohexylmagnesium bromide, and 50 ml of anhydrous ether. The reaction temperature was controlled at 60°C and allowed to react for 2 hours. The mixture was then cooled in an ice bath and then acidified with 50 ml of 5% sulfuric acid. The organic phase was separated and dried over anhydrous sodium sulfate to obtain a light yellow oily liquid A.

[0052] A pale yellow oily liquid A (8.58 g, 0.03 mol) and aluminum nitrate (2.13 g, 0.01 mol) were reacted in 50 ml of distilled water at room temperature for 2 hours to obtain a white precipitate. The precipitate was washed and dried to obtain the target product C1 with a yield of 98% (based on aluminum nitrate).

[0053] Example 3: Preparation of target product C1

[0054] To a 500 ml four-necked flask equipped with a thermometer, a nitrogen inlet device, a 100 ml constant pressure dropping funnel, a magnet, and a reflux condenser were added 12.13 g (0.03 mol) of Lawesson's reagent, 5.62 g (0.03 mol) of cyclohexylmagnesium bromide, and 50 ml of anhydrous ether. The reaction temperature was controlled at 50°C and allowed to react for 3 hours. The mixture was then cooled in an ice bath and then acidified with 50 ml of 5% sulfuric acid. The organic phase was separated and dried over anhydrous sodium sulfate to obtain a light yellow oily liquid A.

[0055] A pale yellow oily liquid A (8.58 g, 0.03 mol) and aluminum nitrate (2.13 g, 0.01 mol) were reacted in 50 ml of distilled water at room temperature for 2 hours to obtain a white precipitate. The precipitate was washed and dried to obtain the target product C1 with a yield of 98% (based on aluminum nitrate).

[0056] Example 4: Preparation of target product C1

[0057] To a 500 ml four-necked flask equipped with a thermometer, a nitrogen inlet device, a 100 ml constant pressure dropping funnel, a magnet, and a reflux condenser were added 12.13 g (0.03 mol) of Lawesson's reagent, 6.74 g (0.036 mol) of cyclohexylmagnesium bromide, and 50 ml of anhydrous ether. The reaction temperature was controlled at 40°C and allowed to react for 4 hours. The mixture was then cooled in an ice bath and acidified with 50 ml of 5% sulfuric acid. The organic phase was separated and dried over anhydrous sodium sulfate to obtain a light yellow oily liquid A.

[0058] A pale yellow oily liquid A (8.58 g, 0.03 mol) and aluminum nitrate (2.13 g, 0.01 mol) were reacted in 50 ml of distilled water at room temperature for 2 hours to obtain a white precipitate. The precipitate was washed and dried to obtain the target product C1 in a yield of 96% (based on aluminum nitrate).

[0059] Example 5: Preparation of target product C1

[0060] To a 500 ml four-necked flask equipped with a thermometer, a nitrogen inlet device, a 100 ml constant pressure dropping funnel, a magnet, and a reflux condenser were added 12.13 g (0.03 mol) of Lawesson's reagent, 8.43 g (0.045 mol) of cyclohexylmagnesium bromide, and 50 ml of anhydrous ether. The reaction temperature was controlled at 40°C and allowed to react for 4 hours. The mixture was then cooled in an ice bath and then acidified with 50 ml of 5% sulfuric acid. The organic phase was separated and dried over anhydrous sodium sulfate to obtain a light yellow oily liquid A.

[0061] A pale yellow oily liquid A (8.58 g, 0.003 mol) and aluminum nitrate (2.13 g, 0.01 mol) were reacted in 50 ml of distilled water at room temperature for 2 hours to obtain a white precipitate. The precipitate was washed and dried to obtain the target product C1 with a yield of 98% (based on aluminum nitrate).

[0062] Example 6: Preparation of PA6 flame retardant material

[0063] 15 parts by weight of the target product C1 prepared in Example 1 and 85 parts by weight of PA6 were added to a high-speed mixer and mixed evenly. After drying, the mixture was fed into a twin-screw extruder, the temperature was controlled at 250°C, and the mixture was extruded and granulated at a speed of 450 rpm. The obtained pellets were dried and injection molded at 210°C by an injection molding machine to obtain a PA6 flame retardant material.

[0064] Example 7: Preparation of PA6 flame retardant material

[0065] Take 25 parts by weight of the flame retardant prepared in Example 2 and 75 parts by weight of PA6 and add them to a high-speed mixer and mix evenly. After drying, send them into a twin-screw extruder, control the temperature at 210°C, and extrude granules at a speed of 350 rpm. After drying, the obtained pellets are injection molded at 250°C by an injection molding machine to obtain PA6 flame retardant material.

[0066] Example 8: Preparation of PA6 flame retardant material

[0067] Take 20 parts by weight of the flame retardant prepared in Example 3 and 80 parts by weight of PA6 and add them to a high-speed mixer and mix them evenly. After drying, they are sent to a twin-screw extruder, the temperature is controlled at 220°C, and the speed is 400 rpm for extrusion granulation. After drying, the obtained pellets are injection molded by an injection molding machine at 220°C to obtain PA6 flame retardant material.

[0068] Example 9: Preparation of PA6 flame retardant material

[0069] 23 parts by weight of the flame retardant prepared in Example 4 were added to 77 parts by weight of PA6 in a high-speed mixer and mixed evenly. After drying, the mixture was fed into a twin-screw extruder, the temperature was controlled at 230°C, and the mixture was extruded and granulated at a speed of 380 rpm. The obtained pellets were dried and injection molded at 230°C by an injection molding machine to obtain a PA6 flame retardant material.

[0070] Example 10: Preparation of PA6 flame retardant material

[0071] 28 parts by weight of the flame retardant prepared in Example 5 were added to 72 parts by weight of PA6 in a high-speed mixer and mixed evenly. After drying, the mixture was fed into a twin-screw extruder, the temperature was controlled at 240°C, and the mixture was extruded and granulated at a speed of 420 rpm. The obtained pellets were dried and injection molded at 240°C by an injection molding machine to obtain a PA6 flame retardant material.

[0072] Comparative Example 1

[0073] Take 100 parts by weight of PA6 and add it to a high-speed mixer and mix evenly. After drying, send it into a twin-screw extruder, control the temperature at 250°C, and extrude granules at a speed of 450 rpm. After drying, the obtained pellets are injection molded by an injection molding machine at 250°C to obtain pure PA6 material.

[0074] Comparative Example 2

[0075] Take 75 parts by weight of PA6 and 25 parts by weight of diethyl aluminum hypophosphite and add them to a high-speed mixer and mix them evenly. After drying, send them into a twin-screw extruder, control the temperature at 250°C, and extrude granules at a speed of 450 rpm. After drying, the obtained pellets are injection molded by an injection molding machine at 250°C to obtain PA6 flame retardant material.

[0076] Effect evaluation:

[0077] The materials prepared in Examples 6 to 10, Comparative Example 1 and Comparative Example 2 were respectively taken as samples, and the tensile strength, impact strength, glow-wire flame retardant temperature, limiting oxygen index and vertical burning grade of the samples were tested.

[0078] The tensile strength was tested according to the GB / T1040-92 method, where: Type I specimen, the test speed was 5 mm / min, and the test was carried out in an environment with a temperature of 23°C and a relative humidity of 50%;

[0079] Impact strength was tested according to GB1843-2008. The specimen dimensions were 80 mm long, 10 mm wide, and 4 mm thick, with an A-notch. The impact velocity was 3.5 m / s, the nominal energy of the pendulum was 5.5 J, and the test was conducted at a temperature of 23°C and a relative humidity of 50%.

[0080] The glow-wire flame retardant temperature is tested according to GB / T5169.11-1997, and the test duration is 30s;

[0081] The limiting oxygen index test was conducted according to GB / T10707-2008 Method A. The sample size was 100 mm long, 10 mm wide, and 3 mm thick. The gas type was natural gas. The test was conducted in an environment with a temperature of 23°C and a relative humidity of 50%.

[0082] The vertical combustion test was conducted in accordance with GB / T10707-2008 Method B. The sample size was 130 mm long, 13 mm wide, and 3 mm thick. The gas type was natural gas. The test was conducted in an environment with a temperature of 23°C and a relative humidity of 50%.

[0083] The test results are shown in Table 1.

[0084] Table 1 Performance test results

[0085]

[0086] As can be seen from Table 1, the PA6 materials prepared in Examples 6-10 of the present invention do not ignite within 30 seconds when a glow wire is in contact with the material at 960°C, the limiting oxygen index is greater than 29, and the vertical combustion grade is FV-0, showing excellent flame retardant properties. At the same time, the tensile strength is higher than 110 MPa and the impact strength is greater than 7.0 KJm -2 , with outstanding mechanical properties.

[0087] In addition, compared with Comparative Example 1, the flame retardant grade, maximum glow-wire passing temperature and limiting oxygen index of the PA6 materials prepared in Examples 6-10 of the present invention are significantly improved, and the tensile strength and impact strength are also significantly improved, among which Example 7 has the largest improvement.

[0088] Compared with Comparative Example 2, the flame retardant grade, maximum glow-wire passing temperature and limiting oxygen index of the PA6 materials prepared in Examples 6-10 of the present invention have no significant difference, but the tensile strength and impact strength are significantly improved, showing obvious advantages in mechanical properties.

[0089] The above test results prove that adding an appropriate amount of cyclohexyl-4-methoxyphenyl aluminum thiophosphate prepared by the present invention to PA6 can not only greatly improve the flame retardant properties of the PA6 material and exert a good flame retardant effect, but also significantly improve the mechanical properties of the composite material, making its performance more advantageous and having significant progress.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention and are not limiting. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in this field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. An asymmetric alkyl phosphate compound, characterized in that: Its structural formula is shown below: 。 2. The method for preparing an asymmetric alkyl phosphate compound according to claim 1, wherein: The steps include: Step S1: Under an inert gas atmosphere, using Lawesson's reagent and cyclohexylmagnesium bromide as raw materials and anhydrous ether as the reaction solvent, the reaction is heated under reflux for a certain period of time, cooled in an ice bath, and then acidified with sulfuric acid. The organic phase is separated and dried to obtain a light yellow oily liquid; Step S2: The light yellow oily liquid prepared in step S1 and aluminum nitrate are reacted in distilled water at room temperature to form a white precipitate, which is then dried to obtain the target product.

3. The method for preparing the asymmetric alkyl phosphate compound according to claim 2, wherein: In step S1, the molar feed ratio of Lawesson reagent to cyclohexylmagnesium bromide is 1:(1-1.5).

4. The method for preparing an asymmetric alkyl phosphate compound according to claim 2, wherein: In step S1, the reaction temperature is 35-60° C., and the reaction time is 2-5 h.

5. The method for preparing the asymmetric alkyl phosphate compound according to claim 2, wherein: In step S2, the molar ratio of the light yellow oily liquid to aluminum nitrate is 3:1; The reaction time is 2-2.5 hours.

6. Use of the asymmetric alkyl phosphate compound according to claim 1 in the preparation of PA6 flame retardant materials.

7. PA6 flame retardant material, characterized by: The raw materials for its preparation comprise the asymmetric alkyl phosphate compound according to any one of claims 1 to 5.

8. The PA6 flame retardant material according to claim 7, characterized in that: The invention is prepared from PA6 and the asymmetric alkyl phosphate compound, wherein the weight proportion of the PA6 is 75-85 parts, and the weight proportion of the asymmetric alkyl phosphate compound is 15-25 parts.

9. The method for preparing the PA6 flame retardant material according to claim 8, wherein: The raw materials in parts by weight uniformly mixed are melt-extruded into granules using a twin-screw extruder, and the granules are then injection-molded by an injection molding machine to obtain finished products.

10. The method for preparing the PA6 flame retardant material according to claim 9, wherein: The temperature of the melt extrusion is 210-250°C, and the temperature of the injection molding is 210-250°C.

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