Alkylphosphonous acid compound as well as preparation method therefor and use thereof

Abstract

Disclosed in the present invention are an alkylphosphonous acid compound as well as a preparation method therefor and the use thereof. The structure of the compound comprises aluminum alkylphosphinate, aluminum alkyl hydrogen phosphinate, aluminum phosphite and crystal water. The compound and aluminum diethylphosphinate are compounded to serve as a flame retardant, so that the problem that a foaming phenomenon and a mold fouling phenomenon are liable to occur during preparation processes of flame-retardant nylon can be effectively solved, and prepared materials have good mechanical properties and flame retardance.

Description

Alkylphosphonous acid compound and its preparation method and application Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and particularly relates to an alkyl phosphonous acid compound and a preparation method and application thereof. Background Art

[0002] Aluminum phosphite is currently widely used as a flame retardant synergist due to its good flame retardancy synergistic properties with aluminum diethylphosphinate, its low water solubility and acidity, and its application in glass fiber reinforced engineering plastics, such as nylon and polyester systems, with good flame retardancy. CN 104114485 A found that a mixture of aluminum hydrogen phosphite and aluminum salt is significantly more stable than pure aluminum phosphite. However, both aluminum phosphite and aluminum hydrogen phosphite contain strong reducing phosphorus-hydrogen bonds in their structures, so their heat stability is still poor. During high-temperature decomposition, it easily decomposes to produce highly toxic and flammable phosphine gas in the air, posing a major safety hazard. At the same time, aluminum phosphite is an inorganic salt with poor compatibility with the polymer matrix. As a synergistic flame retardant, increasing the amount added will significantly affect the mechanical properties and processing properties of the matrix, seriously limiting the application of aluminum phosphite.

[0003] Alkyl aluminum phosphites replace the phosphorus-hydrogen bonds in aluminum phosphite by introducing alkyl groups to form phosphorus-carbon bonds, thereby improving its compatibility with resin matrix materials. At the same time, because there are no reducing phosphorus-hydrogen bonds in the molecular structure, alkyl aluminum phosphites have higher thermal stability than phosphorous acid, and no highly toxic and flammable phosphine gas is produced during the decomposition process.

[0004] Aluminum phosphite and alkyl aluminum phosphites, as flame retardant synergists for aluminum diethylphosphinate, do not possess excellent flame retardancy on their own, but they can enhance the flame retardancy of diethylphosphinate to a certain extent. The flame retardant system of aluminum alkyl phosphites and aluminum diethylphosphinate can effectively reduce screw corrosion caused by resin processing, while also improving the whiteness of the flame-retardant polymer matrix.

[0005] However, in the actual production process, it was found that the use of aluminum phosphite or alkyl aluminum phosphite in combination with diethyl aluminum phosphinate for flame retardant PA66, PA6 and high-temperature nylon is prone to foaming during the entry and exit of the screw rod, and mold deposit is easily generated during the injection molding process.

[0006] Summary of the Invention

[0007] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide an alkyl phosphinate compound. The compound is compounded with aluminum diethylphosphinate as a flame retardant. The compound is applied to the injection molding process of flame-retardant PA66, PA6 and high-temperature nylon without foaming and is not prone to mold deposit. At the same time, the prepared material has good mechanical properties and flame retardant properties.

[0008] Another object of the present invention is to provide a method for preparing the compound.

[0009] Another object of the present invention is to provide use of the compound as a flame retardant synergist for aluminum diethylphosphinate.

[0010] To achieve the above object, the present invention is implemented through the following technical solutions:

[0011] An alkyl phosphonous acid compound, the structural formula of the compound is shown in formula (I):

[0012] Wherein, in formula (I), R is methyl or ethyl; x represents 2.6 to 2.98; y represents 0.01 to 0.39; z represents 0.01 to 0.10; and m represents 1.0 to 2.0.

[0013] The present invention provides an alkyl phosphite compound, which contains alkyl aluminum phosphite, alkyl aluminum hydrogen phosphite, aluminum phosphite and crystal water. The compound can effectively solve the foaming problem in the high-temperature nylon screw extrusion process. It can be used to flame-retard PA66, PA6 and high-temperature nylon to effectively solve the problem of mold deposit easily generated during the injection molding process.

[0014] Preferably, the particle size D50 of the compound is 1 to 100 μm.

[0015] Preferably, the content of sodium sulfate in the compound is 100 to 5000 ppm.

[0016] The preparation method of the compound comprises the following steps:

[0017] Alkyl phosphite and phosphite are mixed, and subjected to double decomposition reaction with aluminum salt aqueous solution, followed by precipitation, filtration, washing, and drying at 105-120° C. to obtain a compound; the temperature of the double decomposition reaction is 60-130° C.

[0018] Specifically, the preparation method of the alkyl phosphinate can be one of the following methods:

[0019] Method 1:

[0020] The alkylphosphinate diester is hydrolyzed under alkaline conditions to obtain the alkylphosphinate;

[0021] Or method 2:

[0022] S1. In the presence of an initiator, phosphorous acid reacts with gaseous ethylene in aqueous solution to produce an alkylphosphonous acid;

[0023] S2. reacting an alkylphosphonous acid with an equimolar alkaline solution to obtain an alkylphosphonite.

[0024] Preferably, the aluminum salt aqueous solution is an aluminum sulfate aqueous solution or an aluminum chloride aqueous solution.

[0025] Preferably, the aluminum salt aqueous solution is slowly added using a high-pressure metering pump over a period of 60 to 180 minutes.

[0026] Preferably, in step S2., the alkaline solution is an aqueous sodium hydroxide solution or an aqueous potassium hydroxide solution.

[0027] The compound is used as a flame retardant synergist for aluminum diethylphosphinate.

[0028] A composition comprises the following components in parts by weight: 1 to 7 parts of the above compound and 12 to 19 parts of aluminum diethylphosphinate.

[0029] The composition is used as a flame retardant in the flame retardancy of PA66, PA6 and high-temperature nylon.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention provides a compound containing alkyl aluminum phosphinate, alkyl aluminum hydrogen phosphinate, aluminum phosphite and crystal water. The compound is compounded with diethyl aluminum phosphinate as a flame retardant and applied to nylon flame retardant. The compound can effectively solve the foaming problem and mold deposit problem in the preparation process, and the obtained material has good mechanical properties and flame retardant properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a rendering of a no-foaming effect;

[0033] Figure 2 is a diagram showing a slight foaming effect;

[0034] Figure 3 is a diagram showing the obvious foaming effect. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below with reference to specific examples. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. Unless otherwise specified, the test methods used in the following examples are conventional methods; the materials, reagents, etc. used are reagents and materials that can be obtained from commercial channels unless otherwise specified. In Examples 1 to 4 and Comparative Examples 1 to 3, the compounds were prepared by the following method, comprising the following steps:

[0036] S1. Solid phosphorous acid, water and sodium persulfate were placed in an autoclave, replaced with nitrogen, ethylene was constant pressure was maintained at 1.6 MPa by a pressure reducer, heated to 85 ° C, and kept warm for 6 hours. The sodium persulfate aqueous solution was continuously fed during the 6-hour heat preservation process, and then kept warm at 90 ° C for 1 hour, cooled and vented to obtain an aqueous solution of ethylphosphonous acid; the sodium persulfate aqueous solution was prepared by 5g of sodium persulfate and 20g of water;

[0037] S2. Phosphorous acid was added to an aqueous solution of ethylphosphonous acid and neutralized with 20% aqueous sodium hydroxide solution to pH = 7 to obtain an aqueous solution of sodium ethylphosphonite / sodium phosphite;

[0038] S3. The sodium ethylphosphite / sodium phosphite aqueous solution was heated to T1, and the aluminum sulfate aqueous solution was continuously fed using a metering pump over 120 minutes to carry out a double decomposition reaction, followed by cooling and filtering. The filter cake was washed three times with 3 times the amount of water and then dried to constant weight at T2 to obtain the compound.

[0039] The raw material dosages and process parameters of Examples 1 to 4 and Comparative Examples 1 to 3 are shown in Table 1.

[0040] Table 1 Raw material dosage and process parameters of Examples 1 to 4 and Comparative Examples 1 to 3

[0041] Example 5

[0042] S1. Dimethyl ethylphosphite was mixed with 120 mol% of a 20 wt% aqueous sodium hydroxide solution, stirred at 80 ° C for 3 h, cooled to room temperature and neutralized with 10% aqueous sulfuric acid to pH = 7 to obtain an aqueous solution of sodium ethylphosphite;

[0043] S2 was added to an aqueous solution of sodium ethylphosphite 3.45 mol% phosphorous acid, using 20% ​​aqueous sodium hydroxide solution neutralized to pH = 7 to obtain an aqueous solution of sodium ethylphosphite / sodium phosphite;

[0044] S3. Heat the sodium ethylphosphite / sodium phosphite aqueous solution to 60°C, and continuously add the aluminum sulfate aqueous solution using a metering pump over 120 minutes to carry out a double decomposition reaction. Then cool and filter in sequence. Wash the filter cake three times with 3 times the amount of water, and then dry at 120°C to constant weight to obtain the compound.

[0045] The particle size D50 of the compounds obtained in Examples 1 to 5 above is 1 to 100 μm, and the content of sodium sulfate is 100 to 5000 ppm. The determination method is:

[0046] 1) Particle size: Take an appropriate amount of sample, moisten it with a small amount of ethanol, add water and stir gently with a glass rod, and measure it using a Malvern laser particle size analyzer.

[0047] 2) Sodium sulfate content: After digestion, take an appropriate amount of sample and test the sulfate content using an ICP instrument to calculate the sodium sulfate content.

[0048] The specific results of the particle size D50 and sodium sulfate content of the compounds obtained in Examples 1 to 5 are shown in Table 2:

[0049] Table 2

[0050] The compounds obtained in Examples 1 to 5 and Comparative Examples 1 to 3 were measured using H NMR spectroscopy, where the method for determining the crystalline water content was as follows:

[0051] The compounds prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were dried, quickly removed, placed in a desiccator, cooled to room temperature, and weighed to obtain m1. The compounds were then dried at 150°C to constant weight, removed, quickly placed in a desiccator, cooled to room temperature, and weighed to obtain m0. The crystal water content was calculated as (m1-m0)*M / (18*m0), where M is the molecular weight of the compound in the absence of crystal water. The test results are shown in Table 3.

[0052] Table 3 Test results of Examples 1 to 5 and Comparative Examples 1 to 3

[0053] As can be seen from Table 3, the compounds prepared by the present invention contain alkyl aluminum phosphites, alkyl aluminum hydrogen phosphites, aluminum phosphite, and water of crystallization. As can be seen from Comparative Example 1, when the metathesis reaction temperature and the drying temperature are high and phosphorous acid is not added during the metathesis process, the obtained compound contains only alkyl aluminum phosphites; as can be seen from Comparative Example 2, when the drying temperature is high and phosphorous acid is not added during the metathesis process, the obtained compound does not contain aluminum phosphite and water of crystallization; as can be seen from Comparative Example 3, when the metathesis reaction temperature is high and phosphorous acid is not added during the metathesis process, the obtained compound does not contain alkyl aluminum hydrogen phosphites and aluminum phosphite.

[0054] application

[0055] Aluminum diethylphosphinate, glass fiber, PA66, PA6, and high-temperature nylon (PA10T) are all commercially available.

[0056] In Comparative Examples 4 to 7, commercially available aluminum phosphite and the compounds prepared in Comparative Examples 1 to 3 were used as flame retardant synergists. In Examples 6 to 12, Compounds 1 to 5 prepared in Examples 1 to 5 were used as flame retardant synergists and were blended and extruded with aluminum ethylphosphinate, glass fiber, PA66, and PA6. The amounts of the components used in Comparative Examples 4 to 7 and Examples 6 to 12 are shown in Table 4. The raw materials used in all parallel experiments were the same.

[0057] In Comparative Examples 8 to 11, commercially available aluminum phosphite and the compounds prepared in Comparative Examples 1 to 3 were used as flame retardant synergists. In Examples 15 to 19, Compounds 1 to 5 prepared in Examples 1 to 5 were used as flame retardant synergists and were blended and extruded with aluminum ethylphosphinate, glass fiber, and high-temperature nylon (PA10T). The amounts of the components used in Comparative Examples 8 to 11 and Examples 13 to 19 are shown in Table 5. The raw materials used in all parallel experiments were the same.

[0058] Table 4 Amount of each component used in Comparative Examples 4 to 7 and Examples 6 to 12 (parts by weight)

[0059] Table 5 Amount of each component used in Comparative Examples 8 to 11 and Examples 13 to 19 (parts by weight)

[0060] Performance Analysis:

[0061] The mechanical properties of the materials prepared in Comparative Examples 4 to 7 and Examples 5 to 19 were measured, and the foaming and mold deposit phenomena during the injection molding process were observed. A "no" foaming phenomenon indicates that the material does not foam at all during the injection molding process, as shown in Figure 1, which is the best result. A "slight" foaming phenomenon indicates that the material produces fewer bubbles and fewer holes between the particles during the injection molding process, as shown in Figure 2, which is the second best result. A "significant" foaming phenomenon indicates that the material produces more bubbles and more holes between the particles during the injection molding process, as shown in Figure 3, which is the worst result. A "no" mold deposit phenomenon indicates that the material does not produce any mold deposit during the injection molding process, which is the best result. A "little" foaming phenomenon indicates that the material produces a small amount of mold deposit during the injection molding process, which is the second best result. A "large" foaming phenomenon indicates that the material produces more mold deposit during the injection molding process, which is the worst result.

[0062] (1) Tensile strength: The tensile strength of the material was measured using a microcomputer-controlled electronic universal testing machine in accordance with GB / T 1040-1992, Test Method for Tensile Properties of Plastics, at a tensile rate of 50 mm / min.

[0063] (2) Vertical Burning: Tested according to UL94-2006, with five specimens per group. The self-extinguishing time after primary and secondary ignition, as well as any molten metal dripping or cotton ignition during combustion, was recorded. The results are shown in Tables 6 and 7.

[0064] Table 6 Measurement results of Comparative Examples 4 to 7 and Examples 6 to 12

[0065] As can be seen from Table 6, when the compound of the present invention and aluminum diethylphosphinate are compounded as a flame retardant, in the flame retardant application of PA6 and PA66, no mold deposit is generated during the injection molding process and no foaming occurs, and the mechanical properties and flame retardant properties of the obtained material are good; as can be seen from Comparative Example 4, when aluminum phosphite and aluminum diethylphosphinate are compounded as a flame retardant, in the flame retardant application of PA6 and PA66, mold deposit is generated during the injection molding process, and the flame retardant property of the obtained material can only reach V-1 level; as can be seen from Comparative Example 5, when the compound in Comparative Example 1 and aluminum diethylphosphinate are compounded as a flame retardant, that is, the compound contains only alkyl aluminum phosphinate, in the flame retardant application of PA6 and PA66, mold deposit is generated during the injection molding process, and the flame retardant property of the obtained material can only reach V-1 level. During the injection molding process of flame-retardant applications of PA66, mold deposits were generated, and the flame retardant properties of the resulting material could only reach V-1 level. Comparative Example 6 shows that when the compound in Comparative Example 2 and aluminum diethylphosphinate were compounded as a flame retardant, that is, when the compound did not contain aluminum phosphite and water of crystallization, mold deposits were generated during the injection molding process of flame-retardant applications of PA6 and PA66. Comparative Example 7 shows that when the compound in Comparative Example 3 and aluminum diethylphosphinate were compounded as a flame retardant, that is, when the compound did not contain alkyl aluminum hydrogen phosphite and aluminum phosphite, mold deposits were generated during the injection molding process of flame-retardant applications of PA6 and PA66. This indicates that the compound must contain alkyl aluminum phosphite, alkyl aluminum hydrogen phosphite, aluminum phosphite, and water of crystallization, and then be compounded with aluminum diethylphosphinate to achieve a better flame retardant effect.

[0066] Table 7 Measurement results of Comparative Examples 8 to 11 and Examples 13 to 19

[0067] As can be seen from Table 7, when the compound of the present invention and aluminum diethylphosphinate are compounded as a flame retardant, in the flame retardant application of high-temperature nylon, no mold deposit is generated during the injection molding process, no foaming occurs during the preparation process, and the mechanical properties and flame retardant properties of the obtained material are good. As can be seen from Comparative Example 8, when aluminum phosphite and aluminum diethylphosphinate are compounded as a flame retardant, in the flame retardant application of high-temperature nylon, obvious foaming occurs during the preparation process, mold deposit is generated during the injection molding process, and the flame retardant properties of the obtained material can only reach V-1 level; as can be seen from Comparative Example 9, when the compound in Comparative Example 1 and aluminum diethylphosphinate are compounded as a flame retardant, that is, the compound contains only alkyl aluminum phosphinate, in the flame retardant application of high-temperature nylon, foaming occurs during the preparation process, and mold deposit is generated during the injection molding process; Comparative Example 10 shows that when the compound in Comparative Example 2 and aluminum diethylphosphinate are compounded as a flame retardant, that is, when the compound does not contain aluminum phosphite and water of crystallization, mold deposit is generated during the injection molding process of flame-retardant applications of high-temperature nylon. Comparative Example 11 shows that when the compound in Comparative Example 3 and aluminum diethylphosphinate are compounded as a flame retardant, that is, when the compound does not contain alkyl aluminum phosphite hydrogen and aluminum phosphite, foaming occurs during the preparation process and mold deposit is generated during the injection molding process of flame-retardant applications of high-temperature nylon. This indicates that the compound must contain alkyl aluminum phosphite, alkyl aluminum phosphite hydrogen, aluminum phosphite, and water of crystallization, and then compounded with aluminum diethylphosphinate as a flame retardant to avoid foaming during the preparation process of flame-retardant high-temperature nylon and mold deposit is not generated during the injection molding process, and the resulting material has good mechanical properties and flame retardant properties.

[0068] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. An alkylphosphonate complex, having a structural formula shown in formula (I):(I)wherein in the formula (I), R is ethyl; x represents 2.6-2.98; y represents 0.01-0.39, z represents 0.01-0.10; and m represents 1.0-2.0.

2. The complex according to claim 1, wherein a median particle diameter, D50, of the alkylphosphonate complex is in a range of from 1 pm to 100 pm.

3. The complex according to claim 1 or 2, wherein a content of sodium sulfate in the alkylphosphonate complex is in a range of from 100 ppm to 5,000 ppm.

4. A preparation method of the alkylphosphonate complex according to any one of claims 13, comprising following steps:mixing an alkylphosphonate and a phosphite to obtain a mixture, subjecting the mixture to a metathesis reaction with an aqueous aluminum salt solution, and then subjecting a resulting mixture to precipitation, filtration, washing, and drying at a temperature of 105-120 °C successively to obtain the alkylphosphonate complex; the metathesis reaction is conducted at a temperature of 60-130 °C.

5. The preparation method of the alkylphosphonate complex according to claim 4, wherein the aqueous aluminum salt solution is an aqueous aluminum sulfate solution or an aqueous aluminum chloride solution.2023369828   07 Oct 20266. The preparation method of the alkylphosphonate complex according to claim 4, wherein the alkylphosphonate is prepared by one of the following methods:Method 1:hydrolyzing a diester of an alkylphosphonic acid under an alkaline condition to obtain the alkylphosphonate;or, Method 2:S1. in the presence of an initiator, allowing a phosphorous acid in an aqueous solution to react with gas-phase ethylene so as to obtain an alkylphosphonic acid;S2. allowing the alkylphosphonic acid to react with an alkaline solution in an equimolar ratio to obtain the alkylphosphonate.

7. The preparation method of the alkylphosphonate complex according to claim 6, wherein in step S2, the alkaline solution is an aqueous sodium hydroxide solution or an aqueous potassium hydroxide solution.

8. A use of the alkylphosphonate complex according to any one of claims 1-3, serving as a flame retardant synergist of aluminum diethylphosphinate.

9. A composition, comprising following components by weight: 1 to 7 parts of the alkylphosphonate complex according to any one of claims 1-3; and 12 to 19 parts of aluminum diethylphosphinate.

10. A use of the composition according to claim 9, serving as a flame retardant in flame retardation of PA66, PA6, or high-temperature nylon.

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