Aluminum diethylphosphinate crystals with low fine powder content, their production method and use

Abstract

The present invention discloses a diethylphosphinate aluminum crystal with low content of fine powder, its preparation method, and its use in flame retarding glass fiber reinforced engineering plastics. The present invention uses phosphorus-containing aluminum salt complex as seed crystals to add in the process of preparing diethylphosphinate aluminum crystals, effectively controlling the crystallization process, and obtaining diethylphosphinic acid crystal particles with low content of fine powder, narrow distribution, and large particle size, which can solve the problems of conventional diethylphosphinate aluminum powder such as easy bridging and clogging, and can be applied to the processing process of non-halogen flame retardant glass fiber reinforced engineering plastics. The prepared diethylphosphinate aluminum contains a small amount of phosphorus-containing aluminum salt complex seed crystals, and its flame retardancy is not affected.

Description

[Technical Field]

[0001] The present invention relates to the field of new materials, and more particularly to aluminum diethylphosphinate crystals with a low fine powder content, and their preparation and use. The preparation method uses a phosphorus-containing aluminum salt complex as a seed crystal to obtain aluminum diethylphosphinate crystals with a low fine powder content that meets the powder flowability requirements of flame retardants in the production process of halogen-free flame-retardant glass fiber reinforced engineering plastics. [Background technology]

[0002] Glass fiber reinforced engineering plastics (such as various nylons and polyesters) are widely used in electronic devices due to their excellent rigidity, impact resistance, low warpage, and excellent appearance. Their use in these fields has increased the demand for flame retardancy in materials. While many engineering plastics are flammable, when blended with glass fiber, the wicking effect of the glass fiber makes them more flammable. Therefore, when using glass fiber reinforced engineering plastics in these fields, it is necessary to address the issue of flame retardancy, but the wicking effect makes flame retardancy even more difficult.

[0003] There are two basic types of flame retardants for glass fiber reinforced engineering plastics: halogenated and non-halogenated. Halogenated systems typically use a combination of brominated flame retardants and antimony trioxide. However, numerous studies have shown that when glass fiber reinforced engineering plastics are burned, they produce thick smoke and harmful substances such as hydrogen bromide, which can cause asphyxiation. Therefore, the development of safe, environmentally friendly non-halogenated flame retardants for glass fiber reinforced engineering plastics has become a hot research topic, and new non-halogen flame retardants or systems for glass fiber reinforced engineering plastics have emerged in recent years.

[0004] Currently, the mainstream non-halogen flame retardants used in glass fiber reinforced engineering plastics are aluminum diethylphosphinate-based composite systems, including combinations of aluminum diethylphosphinate with nitrogen-containing compounds, such as aluminum diethylphosphinate with melamine polyphosphate (MPP), and nitrogen-free aluminum diethylphosphinate with aluminum phosphite. These systems are still widely used due to their high flame retardancy, high temperature resistance, and lack of color. However, aluminum diethylphosphinate-based compound systems typically have too small particle size. When used in twin-screw extruders to produce flame retardants, they often suffer from flow problems, such as powder bridging and blockage, making long-cycle operation difficult. The typical solution to this problem is to produce a high-concentration flame retardant powder as a flame retardant masterbatch, but this solution has some obvious problems: (1) it increases the cost of each masterbatch production run. (2) Masterbatches require polymer carriers, which can limit the flexibility of downstream material formulations and affect the performance of the materials, making them unusable. Therefore, using high-concentration masterbatches to solve the blockage problem caused by aluminum diethylphosphinate is not the best solution. Instead, a solution to the blockage problem from aluminum diethylphosphinate itself needs to be found.

[0005] Research has found that the main cause of bridging and blockages when using aluminum diethylphosphinate particles is the fine powder present in the aluminum diethylphosphinate particles, and these fine powders have a very small particle size, usually less than 5 μm. The smaller the particle size, the larger the specific surface area and the greater the interparticle force. When the proportion of fine powder in this area exceeds a certain value, bridging and blockages are likely to occur. Therefore, the key to solving blockages is to control the proportion of fine powder in aluminum diethylphosphinate.

[0006] In terms of the production process of aluminum diethylphosphinate, aluminum diethylphosphinate particles are produced by utilizing the low water solubility and crystallization properties of aluminum diethylphosphinate, and are obtained by crystallization and precipitation in an aqueous phase through a metathesis reaction, and the actual particle formation process is a crystallization process. According to electron microscope observation, aluminum diethylphosphinate particles are obtained by stacking a large number of small flake-like small crystal particles, the size of these small crystal particles is very small, and the stacking is a random process, so in natural crystalline state, the size of the crystal particles has a wide distribution, and at the same time, the molecular structure of aluminum diethylphosphinate contains lipophilic ethyl groups and hydrophilic aluminum salt structures, that is, its molecular structure contains both lipophilic and hydrophilic parts, so when small crystal particles stack up, they repel each other, and the interaction force of the structure formed by the stacking of small crystal particles is weak, so when shear force such as a stirrer is applied, small particles are easily obtained, so the particle size of aluminum diethylphosphinate particles tends to be small, and in normal production process, the particle size distribution of the obtained particles is wide, that is, the characteristics of the conventional aluminum diethylphosphinate particles currently produced are small average particle size, wide distribution, and there are a large amount of ultrafine particles.This particle size characteristic causes the blockage of aluminum diethylphosphinate. Therefore, the key to solving this problem is to control the crystallization process in the production of aluminum diethylphosphinate, reduce the proportion of ultrafine particles, reduce the maximum particle size, appropriately increase the average particle size, distribute the particle sizes as close to the average particle size as possible, and narrow the particle size distribution. There have been no related reports on a method for effectively reducing the particle size of ultrafine particles. Summary of the Invention [Problem to be solved by the invention]

[0007] In response to the above technical problems and shortcomings of the field, the present invention uses phosphorus-containing aluminum salt complex as seed crystals to add during the production of aluminum diethylphosphinate crystals, thereby effectively controlling the crystallization process and obtaining diethylphosphinic acid crystal particles with a low fine powder content, narrow distribution, and large particle size, thereby solving the problems of conventional aluminum diethylphosphinate powder, such as the tendency to bridge and blockage, and can be applied to the processing of halogen-free flame-retardant glass fiber reinforced engineering plastics. The produced aluminum diethylphosphinate contains a small amount of phosphorus-containing aluminum salt complex seed crystals, and its flame retardancy is not affected.

[0008] The main object of the present invention is to provide a method for producing aluminum diethylphosphinate that overcomes the defects of conventional aluminum diethylphosphinate. The production method of the present invention can produce aluminum diethylphosphinate crystalline particles with a low fine powder content, narrow distribution, and large particle size, thereby solving flowability problems such as bridging and blockage, eliminating the need to produce a masterbatch containing a high concentration of carrier, and allowing the powder to be directly applied to the processing of non-halogen flame-retardant glass fiber reinforced engineering plastics while maintaining high flame retardancy.

[0009] The present invention relates to the preparation of aluminum diethylphosphinate with a low content of fine powder, and by adding a small amount of a phosphorus-containing aluminum salt complex of aluminum diethylphosphinate and aluminum ethylbutylphosphinate as seed crystals during the preparation of aluminum diethylphosphinate, the crystallization process of aluminum diethylphosphinate can be effectively controlled to obtain aluminum diethylphosphinate crystalline powder with a low content of fine powder, a narrow distribution, and a large particle size, thereby solving the problems of aluminum diethylphosphinate obtained by conventional preparation methods, such as a high content of small particle size powder and a wide distribution, and solving the problems of flowability during use, such as the tendency to bridge and blockage. [Means for solving the problem]

[0010] The specific technical solutions are as follows:

[0011] A method for producing aluminum diethylphosphinate crystals having a low content of fine powder, comprising the steps of: uniformly dispersing a phosphorus-containing aluminum salt complex as seed crystals in an aqueous solution of a soluble diethylphosphinate salt; then adding a water-soluble aluminum salt solution containing a strong acid; reacting at 70 to 95°C; and after the reaction, washing and drying the solid product to obtain aluminum diethylphosphinate crystals having a low content of fine powder; The phosphorus-containing aluminum salt complex has a structure represented by the following formula (I): [ka] (In formula (I), a, b, c, d, and e are all molar ratios, a is 0.1 to 0.5, b is 0.5 to 0.9, c, d, and e are 0 to 0.3, and a+b+c+d+e=1; R1 and R2 are each independently selected from H and C1-C6 alkyl; and when either R1 or R2 is ethyl, the other is not ethyl or butyl, and R3 is C1-C6 alkyl.)

[0012] The present invention will be described in detail below.

[0013] The present invention aims to solve the flowability problems, such as the tendency for bridging and clogging to occur in halogen-free flame retardant systems using aluminum diethylphosphinate, which have been widely used in glass fiber reinforced engineering plastics up to now, and the present inventors have conducted extensive research into this matter.

[0014] As a result of research, it was found that the crystal transition of the phosphorus-containing aluminum salt complex with aluminum ethylbutylphosphinate is different from that of aluminum diethylphosphinate, and that under certain conditions, the crystal transition disappears. a phosphorus-containing structure of structural formula (II) and one or more phosphorus-containing structures represented by structural formula (III) and / or structural formula (IV). [ka] In structural formula (III), R1 and R2 are each independently selected from H or C1-C6 alkyl, and when either R1 or R2 is ethyl, the other is not butyl; In structural formula (IV), R3 is H or C1-C6 alkyl.

[0015] The phosphorus-containing aluminum salt complex is a compound having a novel structure and exhibiting properties different from those of a single aluminum salt or a mixture of multiple aluminum salts.

[0016] DSC characterization was performed on phosphorus-containing aluminum salt complexes. Figure 2 shows the DSC chart of the ethylbutylphosphinate aluminum (0.7)-diethylphosphinate aluminum (0.3) complex (the numbers represent the molar ratios of the aluminum complex salts, as shown below) with the molecular structure shown in Figure 1. As can be seen from the DSC chart, this ethylbutylphosphinate aluminum-diethylphosphinate aluminum complex does not exhibit a crystal transition peak. Figure 3 shows the DSC chart of a mixture of ethylbutylphosphinate aluminum and diethylphosphinate aluminum (mixing molar ratio 0.7:0.3), while Figures 4 and 5 show the DSC charts of ethylbutylphosphinate aluminum and diethylphosphinate aluminum, respectively. These results demonstrate that the complex with the novel structure shown in Figure 1 is distinct from both mixtures. For both mixtures, the DSC chart exhibits the characteristics of the mixture, with the crystal transition temperature being that of aluminum diethylphosphinate. The enthalpy value of the crystal transition decreases as the ratio decreases. On the other hand, for the complex, the characteristic crystal transition peak of aluminum diethylphosphinate disappears at the same ratio. Therefore, the complex salt is not a mixture of both but a novel structure.

[0017] As a result of research, it was found that aluminum ethylbutylphosphinate-aluminum diethylphosphinate complexes could be obtained regardless of the ratio of aluminum ethylbutylphosphinate and aluminum diethylphosphinate. Further research revealed that aluminum ethylbutylphosphinate can form aluminum complex salts with aluminum dialkylphosphinates, aluminum monoalkylphosphonites, and inorganic aluminum phosphites, or can be complexed with various aluminum dialkylphosphinates, aluminum monoalkylphosphonites, inorganic aluminum phosphites, etc. to obtain phosphorus-containing aluminum salt complexes.

[0018] Surprisingly, when a small amount of phosphorus-containing aluminum salt complex is added to aluminum diethylphosphinate, the crystal transition of aluminum diethylphosphinate is significantly changed, the crystal transition temperature is lowered, and the amount of heat absorbed / released during the crystal transition is reduced. It has also been found that, at a certain ratio, the crystal transition of aluminum diethylphosphinate disappears. Figure 6 shows a DSC chart of a mixture (weight ratio 8:92) formed by adding the above-prepared aluminum ethylbutylphosphinate-aluminum diethylphosphinate complex to aluminum diethylphosphinate. As can be seen from this chart, when 8 wt% of the complex is added, the crystal transition temperature of aluminum diethylphosphinate is lowered from 179°C to 171.3°C, indicating a significant change in the crystal transition of aluminum diethylphosphinate and a corresponding decrease in the crystal transition temperature. Furthermore, research results showed that the crystal transition temperature decreased as the addition ratio of the phosphorus-containing aluminum salt complex increased, and when the addition ratio reached 30 wt%, the crystal transition of aluminum diethylphosphinate disappeared, i.e., no crystal transition occurred within the temperature range under consideration, and the DSC chart for this is shown in Figure 7.

[0019] These results clearly show that the phosphorus-containing aluminum salt complex has a significant effect on the crystal transition process of aluminum diethylphosphinate, and the crystal transition is closely related to crystallization. Therefore, the present inventors proposed that the phosphorus-containing aluminum salt complex affects the crystallization process for producing aluminum diethylphosphinate, and further affects the particle size and distribution of the crystal particles.

[0020] As a result of research, it was found that by adding a phosphorus-containing aluminum salt complex during the preparation of aluminum diethylphosphinate, the phosphorus-containing aluminum salt complex acts as a seed crystal, affects the crystallization process, and can control the size and distribution of the crystal particle size, and more importantly, can reduce the content of fine powder, increase the particle size, and narrow the particle size distribution, thereby achieving the object of the present invention. As a result of research, it was found that the phosphorus-containing aluminum salt complex has a molecular structure represented by formula (I):

[0021] Formula (I) shows a complex formed with other phosphorus-containing aluminum salts in the presence of aluminum ethylbutylphosphinate and aluminum diethylphosphinate, and the other phosphorus-containing aluminum salts include aluminum dialkylphosphinates / monoalkyl aluminum hypophosphites other than aluminum ethylbutylphosphinate and aluminum diethylphosphinate, monoalkyl aluminum phosphonites, inorganic aluminum phosphites, etc. Aluminum ethylbutylphosphinate and aluminum diethylphosphinate can form phosphorus-containing aluminum salt complexes with one or more of the other phosphorus-containing aluminum salts mentioned above.

[0022] The present invention also provides Step (1) of dissolving ethylbutylphosphinic acid and / or soluble ethylbutylphosphinic acid salts containing an anion moiety of structural formula (II) and other acids and / or soluble salts containing anion moieties of structural formula (III) and / or structural formula (IV) involved in complexation (phosphorus-containing complexing anion donors) in water (which may or may not contain a small amount of strong acid), and then adding an aluminum-containing compound (aluminum ion donor) to react at 80 to 90°C; and (2) a step of, after completion of the reaction, performing solid-liquid separation, washing and drying the solid, and then treating it at a high temperature of 180 to 450°C to obtain the phosphorus-containing aluminum salt complex.

[0023] In the above manufacturing method, The soluble salt is typically a sodium salt or a potassium salt, The aluminum-containing compound is preferably at least one of aluminum sulfate, aluminum nitrate, aluminum chloride, aluminum hydroxide, and alumina; The end point of the washing is preferably when the conductivity of the washing water becomes lower than 500 μs / cm.

[0024] In step (1), the phosphorus-containing complexing anion donor and the aluminum ion donor may be added in an equimolar ratio to ensure complete reaction.

[0025] In step (1), the strong acid may include concentrated sulfuric acid, concentrated nitric acid, concentrated hydrochloric acid, and concentrated phosphoric acid, and the amount of the strong acid added may be 2% to 5% of the mass of the phosphorus-containing complexing anion donor.

[0026] When the aluminum-containing compound is water-insoluble, it may be dispersed in water to form a suspended dispersion, in which case the aluminum-containing compound reacts with the phosphorus-containing complexing anion donor added in the form of an acid, without the need for a high concentration of strong acid.When the aluminum-containing compound is a water-soluble compound, it is preferable to react in the presence of a high concentration of strong acid, in which case the aluminum-containing compound may react with the phosphorus-containing complexing anion donor added in the form of a salt.

[0027] The concentration of the aluminum-containing compound in the reactants is preferably 15% by mass to 50% by mass.

[0028] In step (1), the reaction time may be 1 to 5 hours.

[0029] In step (2), After the reaction is completed, the pH of the liquid phase is controlled to less than 4 to obtain a solid precipitate, and the pH control can be achieved by adding an alkali or a metal oxide, for example.

[0030] The drying may be performed using various ovens, drying chambers, dryers, etc., and the drying temperature may be 100-130°C. The high-temperature treatment is a critical step in the manufacturing process, and the treatment process is related to the composition, proportion, and treatment amount of the phosphorus-containing aluminum salt complex. The high-temperature treatment temperature is a key factor, and research has shown that if the treatment temperature is below 180°C, the phosphorus-containing aluminum salt complex of the present application cannot be obtained. The upper limit of the high-temperature treatment temperature is the decomposition temperature of the complex, which is usually below 450°C. The high-temperature treatment process is as follows: the temperature is raised to 180-450°C over 0.5-10 hours, and the high-temperature treatment is continued for 1-300 minutes.

[0031] The high temperature treatment process in step (2) may be carried out under an inert atmosphere (such as a nitrogen atmosphere or a rare gas atmosphere) or under vacuum conditions.

[0032] After step (2), the resulting phosphorus-containing aluminum salt complex may be pulverized to a desired particle size, if necessary.

[0033] Research has shown that two steps in the preparation method are essential to obtain the phosphorus-containing aluminum salt complex of the present invention. That is, the phosphorus-containing aluminum salt complex of the present invention cannot be obtained without high-temperature treatment (including treatment temperatures below 180°C) or by dry-mixing some of the phosphorus-containing aluminum salts and then heat-treating them at high temperatures.

[0034] Hereinafter, the parameter conditions for the method for producing aluminum diethylphosphinate crystals having a low fine powder content of the present invention will be explained in detail, and preferred embodiments will be explained.

[0035] The phosphorus-containing aluminum salt complex has a structure represented by formula (I), and its molecular structure includes at least a complex of aluminum ethylbutylphosphinate and aluminum diethylphosphinate. In addition, the complex may contain one or more other phosphorus-containing aluminum salts. The resulting complexes all affect the crystallization process in the production of aluminum diethylphosphinate, effectively controlling the particle size and distribution of the crystals and significantly reducing the content of fine powder. On the other hand, phosphorus-containing aluminum salt complexes that do not have the structure represented by formula (I) affect the crystallization process but cannot significantly reduce the content of fine powder, making it impossible to achieve the objectives of the present application.

[0036] The water-soluble aluminum salt, soluble diethylphosphinate, may be charged in a stoichiometric molar ratio to the product aluminum diethylphosphinate.

[0037] The soluble diethylphosphinate may be a sodium salt, a potassium salt, or the like, and the concentration in the aqueous solution may be 20% by mass to 60% by mass.

[0038] Taking the theoretical mass of aluminum diethylphosphinate as the product to be 100%, the addition amount of the phosphorus-containing aluminum salt complex is preferably 0.01% to 10%, more preferably 0.1% to 5%. At an appropriate addition amount, the crystallization process can be effectively controlled and the content of fine powder can be controlled without causing a significant change in the crystal properties of aluminum diethylphosphinate. When the phosphorus-containing aluminum salt complex is added in excess, an effective reduction in the content of fine powder cannot be further obtained, and it also clearly affects the crystal transition of aluminum diethylphosphinate, resulting in significantly different crystal properties of the obtained substance compared to pure aluminum diethylphosphinate, which is not the purpose of this application. When the addition amount of the phosphorus-containing aluminum salt complex is too low, the controlling effect of the phosphorus-containing aluminum salt complex is limited, and the purpose of this application to significantly reduce the content of fine powder cannot be achieved.

[0039] The average particle size D50 of the phosphorus-containing aluminum salt complex preferably satisfies 10 μm < D50 < 50 μm, more preferably 20 μm < D50 < 40 μm. As a result of research, the particle size of the phosphorus-containing aluminum salt complex affects the controlling effect on the crystallization process. If the particle size is too small or too large, the content of fine powder cannot be reduced, and the purpose of this application cannot be achieved.

[0040] The phosphorus-containing aluminum salt complex further contains at least one of the following components (A) to (C). (A) One or more non-complex salts of ethylbutylphosphinate, butylbutylphosphinate, ethylhexylphosphinate, butylhexylphosphinate, and hexylhexylphosphinate (B) Alkyl phosphonite (C) One or more of sulfate, chloride, phosphate, phosphite, hypophosphite, nitrate, acetate, nitrogen-containing compound, iron-containing compound, calcium-containing compound, magnesium-containing compound, titanium-containing compound, sodium-containing compound, and potassium-containing compound.

[0041] The presence of small amounts of the above components (A) to (C) does not affect the effectiveness of the crystallization process by the phosphorus-containing aluminum salt complex, and it is still possible to significantly reduce the content of fine powder.

[0042] The strong acid includes at least one of sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, and the like.

[0043] The amount of the strong acid added may be 1% to 5%, with the theoretical mass of the product aluminum diethylphosphinate being 100%.

[0044] The aluminum salt in the aqueous aluminum salt solution preferably includes at least one of aluminum sulfate, aluminum nitrate, and aluminum chloride.

[0045] The concentration of the aluminum salt in the water-soluble aluminum salt solution in the reaction system is preferably 15% by mass to 50% by mass.

[0046] The reaction time may be 1 to 5 hours.

[0047] After the reaction is completed, the pH of the liquid phase is controlled to less than 4 to obtain a solid precipitate, and the pH control can be achieved by adding an alkali or a metal oxide, for example.

[0048] The end point of the washing is preferably when the conductivity of the washing water becomes lower than 500 μs / cm.

[0049] The drying may be performed using various ovens, drying chambers, dryers, etc., and the drying temperature may be 100 to 130° C. The drying process in step (4) may be performed in an inert atmosphere (such as a nitrogen atmosphere or a rare gas atmosphere) or under vacuum conditions.

[0050] The aluminum diethylphosphinate crystals with a low content of fine powder produced by the present invention may contain one or a mixture of impurities such as aluminum diethylphosphinate, aluminum ethylbutylphosphinate, aluminum butylbutylphosphinate, aluminum ethylhexylphosphinate, aluminum butylhexylphosphinate, and aluminum hexylhexylphosphinate.

[0051] The aluminum diethylphosphinate crystals with a low content of fine powder contain seed crystals of a phosphorus-containing aluminum salt complex, satisfy 20μm < D50 < 50μm in average particle size, have a bulk density of 500 - 700 g / L, and have a content of fine powder with a particle size of less than 5μm of less than 10 wt%.

[0052] The present invention also provides aluminum diethylphosphinate crystals with a low content of fine powder produced by the above manufacturing method.

[0053] The present invention also provides the use of the aluminum diethylphosphinate crystals with a low content of fine powder in the flame retardation of glass fiber reinforced engineering plastics.

[0054] The glass fiber reinforced engineering plastics may use at least one of polyurethane, thermoplastic elastomer, epoxy resin, thermosetting unsaturated polyester, nylon, thermoplastic polyester, and POK (polyketone) as a polymer matrix.

[0055] The aluminum diethylphosphinate crystals with a low content of fine powder are used as a flame retardant or a flame retardant synergist, in the flame retardation of varnishes or foamed paints, in the flame retardation of wood or products containing cellulose, and can be used in the production of flame retardant polymer molding materials, flame retardant polymer films, and flame retardant polymer fibers.

[0056] In the flame-retardant polymer molding material, the flame-retardant polymer film, and the flame-retardant polymer fiber, the composition of the raw materials, with the total mass being 100%, is preferably: It comprises 55% to 99.9% of a polymer matrix, 0.1% to 45% of a flame retardant system, 0 to 44.9% of a filler or reinforcing material, and 0 to 44.9% of an additive.

[0057] The flame retardant system comprises: The composition contains 1% to 100% by mass of the aluminum diethylphosphinate crystals with a low content of fine powder, and 0 to 99% by mass of other flame retardant synergists.

[0058] In the flame retardant system, other flame retardants, flame retardant synergists are Dialkylphosphinic acids and / or their salts; condensation products of melamine and / or reaction products of melamine with phosphoric acid and / or reaction products of condensation products of melamine with polyphosphoric acid or mixtures thereof; nitrogen-containing phosphates; benzoguanamine, tris(hydroxyethyl)isocyanurate, allantoin, glycoluril, melamine, melamine cyanurate, dicyandiamide and / or guanidine; magnesium oxide, calcium oxide, alumina, zinc oxide, manganese oxide, tin oxide, aluminum hydroxide, boehmite, dihydrotalcite, hydrocalumite, magnesium hydroxide, calcium hydroxide, zinc hydroxide, tin oxide hydrate, manganese hydroxide, zinc borate, alkali zinc silicate and / or zinc stannate; phosphites, hydrogen phosphites or condensates thereof; phosphates and derivatives thereof; Melam, melem, melon, dimelamine pyrophosphate, melamine polyphosphate, melam polyphosphate, melon polyphosphate and / or melem polyphosphate and / or mixed polysalts thereof and / or ammonium hydrogen phosphate, ammonium dihydrogen phosphate and / or ammonium polyphosphate; The phosphinic acid may be selected from aluminum hypophosphite, zinc hypophosphite, calcium hypophosphite, sodium phosphite, monophenylphosphinic acid and its salts, mixtures of dialkylphosphinic acids and their salts and monoalkylphosphinic acids and their salts, 2-carboxyethylalkylphosphinic acids and their salts, 2-carboxyethylmethylphosphinic acid and its salts, 2-carboxyethylarylphosphinic acids and their salts, 2-carboxyethylphenylphosphinic acid and its salts, and adducts of DOPO and its salts with p-benzoquinone. [Effects of the Invention]

[0059] Compared with the prior art, the main advantages of the present invention are as follows: The method for producing aluminum diethylphosphinate according to the present invention overcomes the drawbacks of conventional methods, and the produced aluminum diethylphosphinate has particle characteristics of low fine powder content, large particle size and narrow particle distribution, which solves flowability problems such as easy bridging and blockage, and can be directly applied to the processing of halogen-free flame-retardant glass fiber reinforced engineering plastics, realizing long-term operation. [Brief explanation of the drawings]

[0060] [Figure 1] Molecular structure of the ethylbutylphosphinate aluminum(0.7)-diethylphosphinate aluminum(0.3) complex. [Figure 2] FIG. 2 is a DSC chart of the aluminum ethylbutylphosphinate-aluminum diethylphosphinate complex shown in FIG. 1. [Figure 3] 1 is a DSC chart of a mixture of aluminum ethylbutylphosphinate and aluminum diethylphosphinate (molar ratio 0.7:0.3). [Figure 4] 1 is a DSC chart of aluminum ethylbutylphosphinate. [Figure 5] 1 is a DSC chart of aluminum diethylphosphinate. [Figure 6]1 is a DSC chart of aluminum diethylphosphinate to which 8% of a phosphorus-containing aluminum salt complex has been added (based on the total mass of the phosphorus-containing aluminum salt complex, aluminum diethylphosphinate being 100%). [Figure 7] 1 is a DSC chart of aluminum diethylphosphinate to which 30% of a phosphorus-containing aluminum salt complex has been added (with the total mass of the phosphorus-containing aluminum salt complex, aluminum diethylphosphinate, being 100%). DETAILED DESCRIPTION OF THE INVENTION

[0061] The present invention will be further described below with reference to the accompanying drawings and specific examples. It should be understood that these examples are only used to explain the present invention and are not used to limit the scope of the present invention. In the following examples, the operation method without specific conditions is usually in accordance with the usual conditions or the conditions proposed by the manufacturer. Synthesis of ethylbutylphosphinate aluminum(0.2)-diethylphosphinate aluminum(0.8) complex

[0062] The molecular structure of the ethylbutylphosphinate aluminum(0.2)-diethylphosphinate aluminum(0.8) complex is as follows: [ka] manufacturing process

[0063] In a 2L reactor, 34.4g (0.2mol) of sodium ethylbutylphosphinate and 115.2g (0.8mol) of sodium diethylphosphinate were dissolved in 381.7g of water and stirred thoroughly to obtain a mixed solution of sodium ethylbutylphosphinate and sodium diethylphosphinate. In a 500mL beaker, 57g of aluminum sulfate was dissolved in 133g of water. 4.0g of concentrated sulfuric acid (98wt%) was then added to the aluminum sulfate solution and stirred thoroughly to homogenize it. The mixture was then transferred to a dropping funnel. The reactor was heated to 90°C, and the sulfuric acid-containing aluminum sulfate solution was added dropwise over 2 hours. The mixture was then allowed to react for 1 hour while maintaining the temperature. The mixture was filtered while still hot, and the precipitate was washed multiple times. Washing was stopped when the conductivity of the wash water reached less than 200μs / cm. The material was transferred to an oven, heated to 120°C, and dried for 60 minutes. When the moisture content of the solid matter reached 0.1 wt%, the temperature was increased to 180°C at a rate of 2°C / min and held for 60 minutes. After that, the temperature was increased to 320°C at 1°C / min and maintained for 30 minutes. The temperature was then lowered to room temperature, and the material was removed to obtain an ethylbutylphosphinate aluminum (0.2)-diethylphosphinate aluminum (0.8) complex, designated Complex-1. The material was pulverized to an average particle size D50 of 38.0 μm. By referring to the above production process, other complexes were obtained by changing the types and molar ratios of raw materials.

[0064] Complex-2: ethylbutylphosphinate aluminum (0.3)-diethylphosphinate aluminum (0.7) complex, average particle size D50 after grinding 35.2 μm. Complex-3: ethylbutylphosphinate aluminum (0.2)-diethylphosphinate aluminum (0.7)-ethylhexylphosphinate aluminum (0.1) complex, average particle size D50 after grinding 36.1 μm. Complex-4: aluminum ethylbutylphosphinate (0.2%) - aluminum diethylphosphinate (0.7%) - aluminum phosphite (0.1%) complex, average particle size D50 after grinding: 37.4 μm. Complex-5: ethylbutylphosphinate aluminum (0.2)-diethylphosphinate aluminum (0.7)-ethylphosphonite aluminum (0.1) complex, average particle size D50 after grinding 35.8 μm. Complex-6: aluminum ethylbutylphosphinate (0.2)-aluminum diethylphosphinate (0.7)-aluminum ethylhexylphosphinate (0.05)-aluminum phosphite (0.05) complex, average particle size D50 after grinding 38.5 μm. Complex-7: aluminum ethylbutylphosphinate (0.2)-aluminum diethylphosphinate (0.7)-aluminum ethylhexylphosphinate (0.05)-aluminum ethylphosphonite (0.05) complex, average particle size D50 after grinding 37.6 μm. Complex-8: aluminum ethylbutylphosphinate (0.2)-aluminum diethylphosphinate (0.7)-aluminum ethylphosphonite (0.05)-aluminum phosphite (0.05) complex, average particle size D50 after grinding 37.0 μm. Complex-9: aluminum ethylbutylphosphinate (0.2)-aluminum diethylphosphinate (0.65)-aluminum ethylhexylphosphinate (0.05)-aluminum ethylphosphonite (0.05)-aluminum phosphite (0.05) complex, average particle size D50 after grinding 38.4 μm. Complex-10: ethylbutylphosphinate aluminum (0.7)-diethylphosphinate aluminum (0.3) complex, average particle size D50 after grinding 37.7 μm. Aluminum diethylphosphinate, LFR-8003, average particle size D50 39.2 μm, manufactured by Jiangsu Liside New Materials Co., Ltd. Aluminum ethylbutylphosphinate, average particle size D50 42.6 μm, homemade. Example 1 manufacturing process

[0065] In a 2L reactor, 144g (1mol) of sodium diethylphosphinate was dissolved in 336g of water and stirred thoroughly to obtain a sodium diethylphosphinate solution. Next, 12.6g (2wt%) of complex-1 was added and stirred thoroughly to uniformly disperse the complex in the solution. In a 500mL beaker, 57g of aluminum sulfate was dissolved in 133g of water. Next, 3.0g of concentrated sulfuric acid (98wt%) was added to the aluminum sulfate solution and stirred thoroughly to uniformly mix, then transferred to a dropping funnel. The reactor was heated to 90°C, and the sulfuric acid-containing aluminum sulfate solution was added dropwise over 2 hours. The reaction was continued for 1 hour while maintaining the temperature. The solution was filtered while hot, and the precipitate was washed multiple times. Washing was stopped when the conductivity of the wash water became less than 200μs / cm. The material was transferred to an oven, heated to 120°C, and dried for 60 minutes. When the moisture content of the solid matter reached 0.1 wt%, the temperature was lowered to room temperature and the material was removed to obtain aluminum diethylphosphinate. The particle size was tested, and the results are shown in Table 1. Particle size test method: Tested using a laser particle size distribution analyzer. The powder was dispersed in a 95 vol% ethanol solution and processed under ultrasonic treatment to obtain the particle size and distribution results, and the content of fine powder less than 5 μm was statistically calculated. Example 2

[0066] The procedure was almost the same as in Example 1, except that the amount of Complex-1 added was changed to 5.2 g (4 wt%). The results are shown in Table 1. Example 3

[0067] The procedure was almost the same as in Example 1, except that the average particle size of the added complex-1 was changed to 25 μm. The results are shown in Table 1. Example 4

[0068] The procedure was almost the same as in Example 1, except that the same mass of Complex-2 was added, and the remaining conditions were the same. The results are shown in Table 1. Comparative Example 1

[0069] The procedure was almost the same as in Example 1, except that no complex was added, and the remaining conditions were the same. The results are shown in Table 1.

[0070] Comparative Example 2 The procedure was almost the same as in Example 1, except that the same mass of aluminum diethylphosphinate was added instead of Complex-1. The results are shown in Table 1.

[0071] Comparative Example 3 The procedure was almost the same as in Example 1, except that the same mass of aluminum ethylbutylphosphinate was added instead of Complex-1. The results are shown in Table 1. Comparative Example 4

[0072] The procedure was almost the same as in Example 1, except that the same mass of a mixture of aluminum ethylbutylphosphinate and aluminum diethylphosphinate (molar ratio 0.2:0.8) was added instead of Complex-1. The results are shown in Table 1. Comparative Example 5

[0073] The procedure was almost the same as in Example 1, except that the average particle size of the added complex-1 was 5 μm. The results are shown in Table 1. Comparative Example 6

[0074] The procedure was almost the same as in Example 1, except that 10.01 g of the complex was added, and the remaining conditions were the same. The results are shown in Table 1. Comparative Example 7

[0075] The procedure was almost the same as in Example 1, except that the same mass of Complex-10 was added, and the remaining conditions were the same. The results are shown in Table 1. [Table 1] The results clearly show that the particles obtained using the phosphorus-containing aluminum salt complex of the present invention have larger particle sizes, a narrower distribution, and a significantly reduced content of fines. Example 5

[0076] The procedure was almost the same as in Example 1, except that the same mass of Complex-3 was added, and the remaining conditions were the same. The results are shown in Table 2. Example 6

[0077] The procedure was almost the same as in Example 1, except that the same mass of Complex-4 was added, and the remaining conditions were the same. The results are shown in Table 2. Example 7

[0078] The procedure was almost the same as in Example 1, except that the same mass of Complex-5 was added, and the remaining conditions were the same. The results are shown in Table 2. Example 8

[0079] The procedure was almost the same as in Example 1, except that the same mass of Complex-6 was added, and the remaining conditions were the same. The results are shown in Table 2. Example 9

[0080] The procedure was almost the same as in Example 1, except that the same mass of Complex-7 was added, and the remaining conditions were the same. The results are shown in Table 2. Example 10

[0081] The procedure was almost the same as in Example 1, except that the same mass of Complex-8 was added, and the remaining conditions were the same. The results are shown in Table 2. Example 11

[0082] The procedure was almost the same as in Example 1, except that the same mass of Complex-9 was added, and the remaining conditions were the same. The results are shown in Table 2. [Table 2] It is clear from the results in Table 2 that the multi-element phosphorus-containing aluminum salt complex of aluminum ethylbutylphosphinate and aluminum diethylphosphinate similarly affects the crystallization process in the preparation of aluminum diethylphosphinate, and can produce aluminum diethylphosphinate crystals with a low fine powder content, large particle size, and narrow particle size distribution. Example 12

[0083] The procedure was almost the same as in Example 1, except that 2.5 g of Complex-1 and 0.1 g of aluminum ethylbutylphosphinate were added, and the remaining conditions were the same. The results are shown in Table 3. Example 13

[0084] The procedure was almost the same as in Example 1, except that 2.5 g of Complex-1 and 0.1 g of aluminum phosphonite were added, and the remaining conditions were the same. The results are shown in Table 3. Example 14

[0085] The procedure was almost the same as in Example 1, except that 2.5 g of Complex-1 and 0.1 g of aluminum phosphate were added, and the remaining conditions were the same. The results are shown in Table 3. [Table 3] It is clear from the results in Table 3 that the phosphorus-containing aluminum salt complex of the present invention does not affect the control of the crystallization process in the production of aluminum diethylphosphinate by the method of the present invention, even if a small amount of other non-complex salt is present. Uses of aluminum diethylphosphinate Example 15

[0086] A flame-retardant glass fiber reinforced PPA was manufactured according to a specified process using 50% wt high-temperature nylon PPA, 30% wt glass fiber, and 20% wt aluminum diethylphosphinate manufactured in Example 1. The results were analyzed after 10 hours of continuous operation, and samples were also prepared and tested for flame retardancy. The results showed that the PPA did not stop due to bridging or other failures even after 10 hours of operation, and the flame retardancy of the material reached UL94 V0 (0.8 mm). Comparative Example 8

[0087] A flame-retardant glass fiber reinforced PPA was manufactured according to a specified process using 50% wt high-temperature nylon PPA, 30% wt glass fiber, and 20% wt aluminum diethylphosphinate manufactured in Comparative Example 1. The results were analyzed after 10 hours of continuous operation, and samples were also manufactured to test the flame retardancy. After 10 hours of operation, the PPA stopped three times due to failures such as bridging, and the flame retardancy of the material reached UL94 V0 (0.8 mm).

[0088] From the above results, it is clear that the aluminum diethylphosphinate produced by the method of the present invention does not stop due to breakdown such as bridging and maintains its flame retardancy.

[0089] Furthermore, it should be understood that, after reading the above description of the present invention, one skilled in the art may make various changes or modifications to the present invention, and that equivalent forms thereof are also included within the scope defined by the claims of this application.

Claims

1. A method for producing aluminum diethylphosphinate crystals having a low content of fine powder, comprising: The method comprises the steps of uniformly dispersing a phosphorus-containing aluminum salt complex as seed crystals in an aqueous solution of a soluble diethylphosphinate salt, then adding a water-soluble aluminum salt solution containing a strong acid, and reacting at 70 to 95°C, and after the reaction is completed, washing and drying the solid product to obtain the aluminum diethylphosphinate crystals with a low content of fine powder, The phosphorus-containing aluminum salt complex has a structure represented by the following formula (I): The amount of the phosphorus-containing aluminum salt complex added is 0.01% to 10% based on the theoretical mass of the product aluminum diethylphosphinate being 100%; The method for producing the phosphorus-containing aluminum salt complex, wherein the average particle size satisfies 10 μm<D50<50 μm. 【Chemistry 1】 (In formula (I), a, b, c, d, and e are all molar ratios, a is 0.1 to 0.5, b is 0.5 to 0.9, c, d, and e are 0 to 0.3, and a+b+c+d+e=1; R １ , R ２ are each independently selected from H and C1-C6 alkyl, and R １ , R ２ When either of R is ethyl, the other is not ethyl and butyl. ３ is C1-C6 alkyl.

2. 2. The method according to claim 1, wherein the amount of the phosphorus-containing aluminum salt complex added is 0.1% to 5% of the theoretical mass of the product aluminum diethylphosphinate, which is taken as 100%.

3. 2. The method according to claim 1, wherein the average particle diameter D50 of the phosphorus-containing aluminum salt complex satisfies 20 μm<D50<40 μm.

4. 2. The method according to claim 1, wherein the phosphorus-containing aluminum salt complex further contains at least one of the following components (A) to (C): (A) one or more non-complex salts of ethylbutylphosphinate, butylbutylphosphinate, ethylhexylphosphinate, butylhexylphosphinate, and hexylhexylphosphinate (B) Alkyl phosphonite (C) One or more of sulfates, chlorides, phosphates, phosphites, hypophosphites, nitrates, acetates, nitrogen-containing compounds, iron-containing compounds, calcium-containing compounds, magnesium-containing compounds, titanium-containing compounds, sodium-containing compounds, and potassium-containing compounds.

5. the strong acid includes at least one of sulfuric acid, nitric acid, hydrochloric acid, and phosphoric acid; 2. The method according to claim 1, wherein the amount of the strong acid added is 1% to 5% of the theoretical mass of the product aluminum diethylphosphinate, which is taken as 100%.

6. 2. The method according to claim 1, wherein the aluminum salt in the aqueous aluminum salt solution contains at least one of aluminum sulfate, aluminum nitrate, and aluminum chloride.

7. 2. The method according to claim 1, wherein the produced aluminum diethylphosphinate crystals with a low content of fine powder contain one or more mixed impurities selected from the group consisting of aluminum diethylphosphinate, aluminum ethylbutylphosphinate, aluminum butylbutylphosphinate, aluminum ethylhexylphosphinate, aluminum butylhexylphosphinate, and aluminum hexylhexylphosphinate.

8. The method according to claim 1, wherein the aluminum diethylphosphinate crystals having a low content of fine powder contain seed crystals of a phosphorus-containing aluminum salt complex, have an average particle size D50 that satisfies the condition 20 μm<D50<50 μm, a bulk density of 500 to 700 g / L, and a content of fine powder having a particle size of less than 5 μm that is less than 10 wt %.

9. The aluminum diethylphosphinate crystals having a low content of fine powder contain seed crystals of a phosphorus-containing aluminum salt complex, have an average particle size D50 that satisfies 20 μm<D50<50 μm, have a bulk density of 500-700 g / L, and contain less than 10 wt% of fine powder having a particle size of less than 5 μm; The phosphorus-containing aluminum salt complex has a structure represented by the following formula (I): 【Chemistry 2】 (In formula (I), a, b, c, d, and e are all molar ratios, a is 0.1 to 0.5, b is 0.5 to 0.9, c, d, and e are 0 to 0.3, and a+b+c+d+e=1; R 1 and R 2 are each independently selected from H and C1 to C6 alkyl; and when either R 1 or R 2 is ethyl, the other is neither ethyl nor butyl; and R 3 is C1 to C6 alkyl.)

10. 10. Use of the aluminum diethylphosphinate crystals with a low fine powder content as claimed in claim 9 in making glass fiber reinforced engineering plastics flame retardant, wherein the glass fiber reinforced engineering plastics have a polymer matrix of at least one of polyurethane, thermoplastic elastomer, epoxy resin, thermosetting unsaturated polyester, nylon, thermoplastic polyester, and POK.

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