A fine-grained piperazine polyphosphate flame retardant and its preparation method and application

Abstract

The invention discloses a fine-grained piperazine polyphosphate flame retardant, wherein the particle size D50 of the fine-grained piperazine polyphosphate flame retardant is less than 20 μm; the invention also discloses a preparation method of the fine-grained piperazine polyphosphate flame retardant, wherein acetic acid is first added to a reaction device, piperazine is added under stirring conditions, and the temperature is increased; polyphosphoric acid is added, stirred, and reacted at 100 to 110° C.; the fine-grained piperazine polyphosphate flame retardant is obtained by cooling to room temperature, filtering, and drying. The method can directly prepare a piperazine polyphosphate flame retardant with a relatively fine particle size, and the product can be used after drying without undergoing a pulverization process, and the acetic acid filtrate obtained by filtering after the reaction can be directly used for the next reaction without treatment.

Description

Technical Field

[0001] The invention relates to the technical field of flame retardants, and in particular to a fine-grained piperazine polyphosphate flame retardant and a preparation method and application thereof. Background Art

[0002] With the rapid development of China's economy, the consumption of flame retardants has increased significantly. Piperazine phosphate (piperazine polyphosphate) flame retardants have the characteristics of halogen-free, low smoke, low toxicity, good thermal stability, excellent flame retardant properties, etc. They meet the requirements of green chemistry and have developed rapidly in recent years.

[0003] At present, polyphosphate piperazine with a phosphoric acid unit length of 2.2 to 10 is prepared by using polyphosphoric acid and piperazine as raw materials, and its particle size (D50) is less than 30μm. The reaction can be carried out in solvents such as alcohols, aromatic alkanes, and halogenated alkanes; the method of preparing polyphosphate piperazine directly using polyphosphoric acid and piperazine as raw materials in a solvent-free state has a coarse product particle size and needs to be crushed. In addition, the reaction is carried out at a high temperature, and there is a risk of the product turning yellow; polyphosphate piperazine with a high polymerization degree is synthesized by using polyphosphoric acid and anhydrous piperazine as starting materials and reacting at 230°C for 3h in a heated kneader. The obtained product needs to be crushed by a jet mill before it can be used in subsequent reactions.

[0004] The particle size and particle size distribution of polypiperazine phosphate are important technical indicators that affect its performance. As an inorganic additive flame retardant, polypiperazine phosphate has great differences in properties with organic polymer matrix and poor dispersibility. When polypiperazine phosphate with large particle size is mixed into the matrix, it will reduce the mechanical properties or processing properties of the flame retardant polymer. The polypiperazine phosphate flame retardant prepared by the prior art has a coarse particle size. At present, in order to promote the dispersion of polypiperazine phosphate, improve its compatibility with polymer materials, and improve flame retardant properties, the coarse particle size polypiperazine phosphate needs to be fine-grained, that is, it needs to be crushed before it can be used in flame retardant polymer materials. There are defects such as complicated process, high cost, and the polypiperazine phosphate obtained cannot be directly used in flame retardant polymer materials. Summary of the invention

[0005] In view of the above problems, the first object of the present invention is to provide a fine-grained piperazine polyphosphate flame retardant; the fine-grained piperazine polyphosphate flame retardant has a particle size D50 < 20 μm and does not need to be crushed, and can be directly used for flame retardant modification of polymer materials.

[0006] The second object of the present invention is to provide a method for preparing the above-mentioned fine-particle polyphosphate piperazine flame retardant. The method uses polyphosphoric acid and piperazine as raw materials and acetic acid (industrial grade) as solvent to directly prepare a polyphosphate piperazine flame retardant with a finer particle size without the need for crushing. The flame retardant modification of polymer materials can be directly used. The process is simple, easy to implement and low in cost.

[0007] The third object of the present invention is to provide the use of the above-mentioned fine-grained piperazine polyphosphate flame retardant, which can be directly used for flame retardant modification of polymer materials without crushing.

[0008] The first technical solution adopted by the present invention is: a fine-grained piperazine polyphosphate flame retardant, wherein the particle size D50 of the fine-grained piperazine polyphosphate flame retardant is less than 20 μm.

[0009] The second technical solution adopted by the present invention is: a method for preparing a fine-grained piperazine polyphosphate flame retardant, comprising the following steps:

[0010] S1: first add acetic acid into the reaction device, add piperazine under stirring conditions, and heat up;

[0011] S2: Add polyphosphoric acid, stir, and react at 100-110°C;

[0012] S3: Cool to room temperature, filter and dry to obtain fine-grained piperazine polyphosphate flame retardant.

[0013] Preferably, in step S1, the mass ratio of piperazine to acetic acid is 1:6 to 1:15.

[0014] Preferably, the temperature in step S1 is raised to 70-80°C.

[0015] Preferably, the molar ratio of piperazine to polyphosphoric acid in step S2 is 1.5:1-4:1.

[0016] Preferably, the reaction time in step S2 is 4 to 8 hours.

[0017] Preferably, the obtained piperazine polyphosphate has a particle size D50<20 μm.

[0018] Preferably, after the reaction is completed, the acetic acid filtrate obtained by filtration is reused as a reaction solvent for the next reaction.

[0019] The third technical solution adopted by the present invention is: application of a fine-grained piperazine polyphosphate flame retardant, wherein the fine-grained piperazine polyphosphate flame retardant is directly used for flame retardant modification of polymer materials.

[0020] Beneficial effects of the above technical solution:

[0021] (1) The fine-grained piperazine polyphosphate flame retardant prepared by the present invention has a particle size D50 <20 μm and can be directly used for flame retardant modification of polymer materials without the need for crushing.

[0022] (2) The method for preparing fine-grained polyphosphate piperazine flame retardant disclosed in the present invention uses polyphosphoric acid and piperazine as raw materials and acetic acid (industrial grade) as solvent to directly prepare polyphosphate piperazine flame retardant with finer particle size without the need for crushing. The process is simple, easy to implement and low in cost.

[0023] (3) The acetic acid (industrial grade) solvent of the present invention can be recovered by filtration and reused as a reaction solvent for the next reaction without any other treatment, thereby realizing solvent recycling and reducing production costs.

[0024] (4) The present invention does not require high-temperature condensation when preparing the fine-grained piperazine polyphosphate flame retardant, thereby avoiding yellowing of the piperazine polyphosphate. The fine-grained piperazine polyphosphate flame retardant prepared by the present invention has high whiteness.

[0025] (5) Fine-grained polypiperazine phosphate flame retardant has good flame retardant properties and charring properties. It has good flame retardant effect in PP, PE, EP, PU and other materials. It is a halogen-free flame retardant with great market potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention is a process flow chart for preparing a fine-grained piperazine polyphosphate flame retardant;

[0027] Figure 2 This is a particle size distribution diagram of the fine-grained piperazine polyphosphate flame retardant prepared in Example 1 of the present invention;

[0028] Figure 3 This is the TG-DSC spectrum of the fine-grained piperazine polyphosphate flame retardant prepared in Example 1 of the present invention;

[0029] Figure 4 This is a particle size distribution diagram of the fine-grained piperazine polyphosphate flame retardant prepared in Example 2 of the present invention;

[0030] Figure 5 This is the TG-DSC spectrum of the fine-grained piperazine polyphosphate flame retardant prepared in Example 2 of the present invention;

[0031] Figure 6 This is a particle size distribution diagram of the fine-grained piperazine polyphosphate flame retardant prepared in Example 3 of the present invention;

[0032] Figure 7 This is the TG-DSC spectrum of the fine-grained piperazine polyphosphate flame retardant prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0033] The present invention is further described below through specific embodiments. It should be pointed out that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the principle of the present invention, and these should also be regarded as belonging to the protection scope of the present invention.

[0034] The invention discloses a fine-grained piperazine polyphosphate flame retardant. The particle size D50 of the fine-grained piperazine polyphosphate flame retardant is less than 20 μm.

[0035] like Figure 1 As shown, the fine-grained piperazine polyphosphate flame retardant is prepared by the following steps:

[0036] S1: first add acetic acid into a reaction device, add piperazine under stirring conditions, and heat to 70-80° C.; the mass ratio of piperazine to acetic acid is 1:6-1:15; the reaction device is a device that can be heated and refluxed, such as a reaction bottle, a reaction kettle, etc.;

[0037] S2: Add polyphosphoric acid, stir, and react at 100-110°C for 4-8h; the molar ratio of piperazine to polyphosphoric acid is 1.5:1-4:1;

[0038] S3: Cool to room temperature, filter and dry to obtain fine-grained piperazine polyphosphate flame retardant; the particle size D50 of the obtained fine-grained piperazine polyphosphate flame retardant is less than 20 μm. After the reaction is completed, the acetic acid filtrate obtained by filtering is used as a reaction solvent for the next reaction.

[0039] Example 1

[0040] 338g of acetic acid (industrial grade) and 22.5g of piperazine were added to a 500ml three-necked flask, the temperature was raised to 80°C, 59.0g of polyphosphoric acid was added, the resulting mixture was reacted at 100°C for 8h, heating was stopped, the mixture was cooled to room temperature, filtered, and dried to obtain 67.3g of fine-grained polyphosphate piperazine flame retardant with a yield of 82.5%.

[0041] The particle size of the fine-grained piperazine polyphosphate flame retardant was measured by a laser particle size analyzer. The test results are shown in Table 1. The particle size D50 of the product is 18.2 μm. The particle size distribution of the fine-grained piperazine polyphosphate flame retardant is as shown in Table 1. Figure 2 Its thermal decomposition temperature is shown as Figure 3 As shown, from Figure 3 It can be concluded that the initial decomposition temperature of 5% fine-grained piperazine polyphosphate flame retardant is higher than 300°C, and has good flame retardant properties.

[0042] The whiteness of the fine-grained polypiperazine phosphate flame retardant was tested using a whiteness measuring instrument (M11 type, produced by Qingdao Ruiming Instrument Equipment Co., Ltd.), and the whiteness was measured to be 98.2.

[0043] Table 1 Particle size of fine-grained piperazine polyphosphate flame retardant

[0044] Particle size distribution D10 D25 D50 D75 D90 Particle size 8.260μm 12.969μm 18.162μm 24.562μm 31.390μm

[0045] Example 2

[0046] In a 500ml three-necked flask, 155g of the recovered acetic acid filtrate and 25.75g of piperazine were added, the temperature was raised to 70°C, 25.30g of polyphosphoric acid was added, the resulting mixture was reacted at 105°C for 6h, heating was stopped, the mixture was cooled to room temperature, filtered, and dried to obtain 47.1g of fine-grained polyphosphate piperazine flame retardant with a yield of 92.3%.

[0047] The particle size of the fine-grained piperazine polyphosphate flame retardant was measured by a laser particle size analyzer. The test results are shown in Table 2. The product particle size D50 is 17.7 μm. The particle size distribution of the fine-grained piperazine polyphosphate flame retardant is as shown in Table 2. Figure 4 Its thermal decomposition temperature is shown as Figure 5 As shown, from Figure 5 It can be concluded that the initial decomposition temperature of 5% fine-grained piperazine polyphosphate flame retardant is higher than 300°C, and has good flame retardant properties.

[0048] The whiteness of the fine-grained polypiperazine phosphate flame retardant was tested using a whiteness measuring instrument (M11 type, produced by Qingdao Ruiming Instrument Equipment Co., Ltd.), and the whiteness was measured to be 97.6.

[0049] Table 2 Particle size of fine-grained piperazine polyphosphate flame retardant

[0050] Particle size distribution D10 D25 D50 D75 D90 Particle size 7.807μm 12.609μm 17.715μm 23.972μm 30.622μm

[0051] Example 3

[0052] Add 230g acetic acid (industrial grade) and 22.6g piperazine into a 500ml three-necked flask, heat to 77°C, add 34.7g polyphosphoric acid, react the resulting mixture at 110°C for 4h, stop heating, cool to room temperature, filter, and dry to obtain 48.7g fine-grained polyphosphate piperazine flame retardant with a yield of 85.0%.

[0053] The particle size of the fine-grained piperazine polyphosphate flame retardant was measured by a laser particle size analyzer. The test results are shown in Table 3. The product particle size D50 is 13.2 μm. The particle size distribution of the fine-grained piperazine polyphosphate flame retardant is as shown in Table 3. Figure 6 Its thermal decomposition temperature is shown as Figure 7 As shown, from Figure 7 It can be concluded that the initial decomposition temperature of 5% fine-grained piperazine polyphosphate flame retardant is higher than 300°C, and has good flame retardant properties.

[0054] The whiteness of the fine-grained polypiperazine phosphate flame retardant was tested using a whiteness measuring instrument (M11 type, produced by Qingdao Ruiming Instrument Equipment Co., Ltd.), and the whiteness was measured to be 98.0.

[0055] Table 3 Particle size of fine-grained piperazine polyphosphate flame retardant

[0056] Particle size distribution D10 D25 D50 D75 D90 Particle size 5.770μm 8.841μm 13.155μm 19.051μm 26.075μm

[0057] The fine-grained piperazine polyphosphate flame retardant prepared by the invention has a particle size D50 less than 20 μm, does not need to be crushed, and can be directly used for flame retardant modification of polymer materials. The method for preparing the fine-grained piperazine polyphosphate flame retardant uses polyphosphoric acid and piperazine as raw materials and acetic acid (industrial grade) as a solvent to directly prepare piperazine polyphosphate with a relatively fine particle size without crushing, has a simple process, is easy to implement, and has a low cost.

[0058] Compared with the polypiperazine phosphate with finer particle size prepared by other methods, the acetic acid (industrial grade) solvent of the present invention can be recovered by filtration and reused as a reaction solvent for the next reaction without other treatment, thereby realizing solvent recycling and reducing production costs; the present invention does not require high-temperature condensation when preparing the fine-grained polypiperazine phosphate flame retardant, thereby avoiding yellowing of the polypiperazine phosphate, and the fine-grained polypiperazine phosphate flame retardant prepared by the present invention has high whiteness.

[0059] Fine-grained piperazine polyphosphate flame retardant has good flame retardant properties and charring properties. It has good flame retardant effect in PP, PE, EP, PU and other materials. It is a halogen-free flame retardant with great market potential.

Claims

1. A method for preparing a fine-grained piperazine polyphosphate flame retardant, characterized in that: The raw materials consist of acetic acid, piperazine and polyphosphoric acid and are prepared by the following steps: S1: first add acetic acid into the reaction device, add piperazine under stirring conditions, and heat to 70-80°C; S2: Add polyphosphoric acid, stir, and react at 100-110°C for 4-8h; S3: Cooling to room temperature, filtering and drying to obtain a fine-grained piperazine polyphosphate flame retardant; Wherein, the particle size D50 of the prepared piperazine polyphosphate is less than 20 μm.

2. The method for preparing a fine-grained piperazine polyphosphate flame retardant according to claim 1, characterized in that: In the step S1, the mass ratio of piperazine to acetic acid is 1:6 to 1:

15.

3. The method for preparing a fine-grained piperazine polyphosphate flame retardant according to claim 1, characterized in that: The molar ratio of piperazine to polyphosphoric acid in step S2 is 1.5:1-4:

1.

4. The method for preparing a fine-grained piperazine polyphosphate flame retardant according to claim 1, characterized in that: After the reaction is completed, the acetic acid filtrate obtained by filtration is reused as the reaction solvent in the reaction.

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