A superhydrophobic and thermally stable piperazine pyrophosphate and its preparation method

Abstract

This invention discloses a superhydrophobic and thermally stable piperazine pyrophosphate and its preparation method. The superhydrophobic and thermally stable piperazine pyrophosphate comprises piperazine pyrophosphate with a vesicular structure coated on its surface. The vesicular structure is a self-assembled structure resulting from the alcoholysis reaction of a polysulfide silane compound with piperazine pyrophosphate. The piperazine pyrophosphate of this invention, coated with a vesicular structure, is a sulfur-containing silane material. This vesicular structure endows the piperazine pyrophosphate with superhydrophobic properties and achieves excellent hydrophobic durability. It maintains good water resistance and extremely low hygroscopicity in high humidity environments, solving the problem of moisture absorption and agglomeration of piperazine pyrophosphate powder. The vesicular structure also blocks heat and mass transfer, reducing the thermal oxidation rate of PAPP. Therefore, the piperazine pyrophosphate provided by this invention also has excellent thermal stability and final charring performance, which is beneficial for reducing the amount of piperazine pyrophosphate used in flame-retardant polymer materials.

Description

Technical Field

[0001] This invention belongs to the field of flame retardant technology, specifically relating to a superhydrophobic and highly thermally stable piperazine pyrophosphate and its preparation method. Background Technology

[0002] Piperazine pyrophosphate (PAPP) is a novel nitrogen-phosphorus-based single-component halogen-free intumescent flame retardant. It contains three components of an intumescent flame retardant system (IFR): acid source, gas source, and char source. It features high flame retardant efficiency, good heat resistance, low smoke, non-toxicity, and anti-dripping properties. It can be used in polymer materials such as polypropylene (PP), polyethylene (PE), epoxy resin (EP), and thermoplastic elastomers.

[0003] Compared to other flame retardants, such as ammonium polyphosphate (APP) and other intumescent flame retardants, novel piperazine-based intumescent flame retardants, represented by piperazine pyrophosphate, exhibit better thermal stability and excellent charring properties, effectively addressing the shortcomings of ammonium polyphosphate in applications. Therefore, piperazine pyrophosphate demonstrates significant performance advantages. However, similar to most flame retardants like ammonium polyphosphate, piperazine pyrophosphate also suffers from drawbacks such as hygroscopic agglomeration, easy migration and precipitation in humid and hot environments, and poor compatibility with polymer matrices, thereby reducing its flame retardant properties and limiting its applications.

[0004] Existing piperazine pyrophosphate modification technologies include: Patent CN110483898A uses lubricants and hydrogen-containing silicone oil to physically / chemically modify piperazine pyrophosphate, improving the shortcomings of flame retardant powder in terms of moisture absorption and agglomeration. However, the silicone oil surface coating treatment will cover the flame retardant surface with an oil film, which not only affects the appearance of the flame retardant but also easily causes the powder to clump after long-term storage. In addition, due to the low melting and boiling points of silicone oil, the product has poor water resistance in humid and hot environments. Patent CN115772285A uses aminosilane aqueous coupling agent and methyl hydrogen-containing silicone oil as surface modifier and water-resistant agent, respectively, to modify piperazine pyrophosphate. In these reaction processes, due to the lack of protection and introduction of low surface energy and hydrophobic groups, the hydrophobic efficiency is low, and the water resistance in humid and hot environments is poor. Hydrophobicity is only achieved at a higher content of silane coupling agent, which increases the production cost of PAPP and affects its application.

[0005] Furthermore, the superhydrophobic and thermally stable piperazine pyrophosphate obtained by existing patent solutions can usually only maintain good water resistance at room temperature, and its water resistance is insufficient in humid and hot environments. At the same time, the durability of hydrophobic modification is insufficient, and the modifier has a low boiling point, which makes the modifier of piperazine pyrophosphate easy to volatilize and escape when it is blended with polymers, thus losing the modification effect. Summary of the Invention

[0006] To overcome the problems existing in the prior art, this invention is based on elucidating the mechanism of the chemical reaction between polysulfide silane compounds and piperazine pyrophosphate. It precisely controls the alcoholysis reaction of a single sulfur silane compound and piperazine pyrophosphate in a highly efficient and rapid manner. While obtaining the chemical bond between the polysulfide silane compound and piperazine pyrophosphate, it achieves a vesicle structure with pyrophosphate as the core and hydrophobic polysulfide silane compound as the outer layer based on the hydrophilic-hydrophobic self-assembly driving force. This provides a superhydrophobic and thermally stable piperazine pyrophosphate and its preparation method.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] The first aspect of the present invention provides a superhydrophobic and thermally stable piperazine pyrophosphate, comprising piperazine pyrophosphate, wherein the surface of the piperazine pyrophosphate is coated with a vesicle structure, and the vesicle structure is a self-assembled structure after the alcoholysis reaction of a polysulfide silane compound and piperazine pyrophosphate.

[0009] Preferably, the mass ratio of piperazine pyrophosphate to polysulfide silane compound is 100:(0.5-5).

[0010] More preferably, the mass ratio of the piperazine pyrophosphate to the polysulfide silane compound is 100:(0.5-2).

[0011] Preferably, the polysulfide silane compound includes at least one of bis-[γ-(triethoxysilane)propyl]-tetrasulfide and bis-[3-(triethoxysilane)propyl]-disulfide.

[0012] The second aspect of the present invention provides a method for preparing the superhydrophobic and thermally stable piperazine pyrophosphate of the first aspect, comprising the following steps: subjecting a thiosilane compound to a highly efficient alcoholysis reaction with piperazine pyrophosphate to obtain the superhydrophobic and thermally stable piperazine pyrophosphate.

[0013] Preferably, the reaction pH of the alcoholysis reaction is 1 to 6.

[0014] More preferably, the reaction pH of the alcoholysis reaction is 3-4.

[0015] Preferably, the reaction temperature of the alcoholysis reaction is 70–120°C.

[0016] More preferably, the reaction temperature of the alcoholysis reaction is 70–90°C.

[0017] Preferably, the reaction time of the alcoholysis reaction is 1 to 10 minutes.

[0018] Preferably, the reaction time of the alcoholysis reaction is 2 to 5 minutes.

[0019] Preferably, the method includes the following steps: preparing an alcohol solution of a polysulfide silane compound, then subjecting the alcohol solution of the polysulfide silane compound to a highly efficient alcoholysis reaction with piperazine pyrophosphate, and forming a vesicle structure through hydrophilic-hydrophobic self-assembly driving force to obtain the superhydrophobic and thermally stable piperazine pyrophosphate.

[0020] More preferably, the alcohol solvent of the alcohol solution is selected from one or more of ethanol, isopropanol, and n-butanol.

[0021] More preferably, the mass ratio of the sulfur silane compound to the alcohol solvent in the alcohol solution is (0.1-5):1.

[0022] Preferably, the mixing speed of the alcoholysis reaction is 300-1000 rpm;

[0023] Preferably, the process further includes the following steps: after the alcoholysis reaction, the obtained product is dried at a temperature of 70-120°C.

[0024] More preferably, the drying time is 0.5 to 3 hours.

[0025] The beneficial effects of this invention are:

[0026] (1) This invention provides a superhydrophobic and thermally stable piperazine pyrophosphate. The vesicle structure is formed by the efficient alcoholysis reaction of piperazine pyrophosphate with polysulfide silane compounds. The material has superhydrophobic properties and a water contact angle of up to 152°. It not only significantly reduces water absorption compared with unmodified piperazine pyrophosphate, but also achieves super hydrophobic durability. It can maintain good water resistance and extremely low moisture absorption in high humidity environments, which can solve the problem of moisture absorption and agglomeration of piperazine pyrophosphate powder.

[0027] (2) The superhydrophobic and thermally stable piperazine pyrophosphate provided by the present invention also has excellent thermal stability and final char formation performance. Compared with the pure sample before treatment, the 1% thermal weight loss temperature of the superhydrophobic and thermally stable piperazine pyrophosphate is increased by 15°C, and the final char mass is increased by 94.2%-100%, which is beneficial to reduce the amount of piperazine pyrophosphate used in flame-retardant polymer materials. Attached Figure Description

[0028] Figure 1 This is a scanning electron microscope image of piperazine pyrophosphate with superhydrophobicity and high thermal stability as described in Example 1.

[0029] Figure 2 This is a schematic diagram of the efficient alcoholysis reaction of piperazine pyrophosphate with polysulfide silane compounds;

[0030] Figure 3 The infrared spectra of piperazine pyrophosphate before and after the alcoholysis reaction are shown.

[0031] Figure 4The water contact angle of piperazine pyrophosphate with superhydrophobic and high thermal stability in Examples 1 and 2;

[0032] Figure 5 The images show the floating test results of piperazine pyrophosphate in Examples 1 and 2 and Comparative Example 1, where (a), (b), and (c) represent different viewing angles. Detailed Implementation

[0033] The present invention will be further described in detail below through specific embodiments. Unless otherwise specified, the raw materials used in the following embodiments can be obtained from conventional commercial channels or prepared and isolated through simple synthesis; unless otherwise specified, the processes employed are conventional processes in the art.

[0034] The piperazine pyrophosphate used in the following examples and comparative examples is EPFR-110DL, EPFR-110DM or EPFR-110DN produced by Qingyuan Pusefur Phosphate Chemical Co., Ltd.

[0035] Example 1

[0036] This embodiment provides a superhydrophobic and thermally stable piperazine pyrophosphate, the preparation method of which is as follows:

[0037] Bis-[γ-(triethoxysilyl)propyl]-tetrasulfide was mixed with anhydrous ethanol at a mass ratio of 4:1 to obtain a mixed solution. The mixed solution and piperazine pyrophosphate powder were then poured into a reactor, with the mass ratio of bis-[γ-(triethoxysilyl)propyl]-tetrasulfide to piperazine pyrophosphate powder being 0.75:100, to carry out an efficient alcoholysis reaction. The reaction pH was 3.5, the reaction temperature was 80℃, the rotation speed was 800 rpm, and the reaction time was 3 min. The mixture was then removed and dried in an oven at 80℃ for 1 h to obtain superhydrophobic and thermally stable piperazine pyrophosphate.

[0038] Example 2

[0039] This embodiment provides a superhydrophobic and thermally stable piperazine pyrophosphate, the preparation method of which is as follows:

[0040] Bis-[γ-(triethoxysilyl)propyl]-tetrasulfide was mixed with anhydrous ethanol at a mass ratio of 4:1 to obtain a mixed solution. The mixed solution and piperazine pyrophosphate powder were then poured into a reactor, wherein the mass ratio of bis-[γ-(triethoxysilyl)propyl]-tetrasulfide to piperazine pyrophosphate powder was 1:100, to carry out an efficient alcoholysis reaction. The reaction pH was 3.5, the reaction temperature was 80℃, the rotation speed was 800 rpm, and the reaction time was 3 min. The mixture was then removed and dried in an oven at 80℃ for 1 h to obtain superhydrophobic and thermally stable piperazine pyrophosphate.

[0041] Comparative Example 1

[0042] This comparative example provides a piperazine pyrophosphate, the specific preparation method of which is as follows:

[0043] Piperazine pyrophosphate powder was poured into a reactor and subjected to a high-speed mixing reaction at a reaction temperature of 80°C and a rotation speed of 800 rpm. After reacting for 3 minutes, the mixture was removed and dried in an oven at 80°C for 1 hour to obtain piperazine pyrophosphate.

[0044] Comparative Example 2

[0045] This comparative example provides a mixture of piperazine pyrophosphate, the specific preparation method of which is as follows:

[0046] γ-aminopropyltriethoxysilane and anhydrous ethanol were mixed at a mass ratio of 4:1 to obtain a mixed solution. The mixed solution and piperazine pyrophosphate powder were then poured into a reactor, wherein the mass ratio of γ-aminopropyltriethoxysilane to piperazine pyrophosphate powder was 1:100. A high-speed mixing reaction was carried out at a reaction temperature of 80℃ and a rotation speed of 800 rpm for 3 minutes. The mixture was then removed and dried in an oven at 80℃ for 1 hour to obtain a piperazine pyrophosphate mixture.

[0047] Comparative Example 3

[0048] This comparative example provides a mixture of piperazine pyrophosphate, the specific preparation method of which is as follows:

[0049] γ-glycidoxypropyltrimethoxysilane and anhydrous ethanol were mixed at a mass ratio of 4:1 to obtain a mixed solution. The mixed solution and piperazine pyrophosphate powder were then poured into a reactor, wherein the mass ratio of γ-aminopropyltriethoxysilane to piperazine pyrophosphate powder was 1:100. The mixture was subjected to a high-speed mixing reaction at a reaction temperature of 80℃ and a rotation speed of 800 rpm for 3 minutes. The mixture was then removed and dried in an oven at 80℃ for 1 hour to obtain a piperazine pyrophosphate mixture.

[0050] Comparative Example 4

[0051] This comparative example provides a mixture of piperazine pyrophosphate, the specific preparation method of which is as follows:

[0052] 3-Mercaptopropyltrimethoxysilane and anhydrous ethanol were mixed at a mass ratio of 4:1 to obtain a mixed solution. The mixed solution and piperazine pyrophosphate powder were then poured into a reactor, wherein the mass ratio of γ-aminopropyltriethoxysilane to piperazine pyrophosphate powder was 1:100. A high-speed mixing reaction was carried out at a reaction temperature of 80℃ and a rotation speed of 800 rpm for 3 minutes. The mixture was then removed and dried in an oven at 80℃ for 1 hour to obtain a piperazine pyrophosphate mixture.

[0053] Material characterization

[0054] Figure 1The image shows a scanning electron microscope (SEM) image of piperazine pyrophosphate with superhydrophobic and high thermal stability in Example 1. As can be seen from the image, the piperazine pyrophosphate powder is coated with vesicle structures generated by hydrophilic-hydrophobic self-assembly driven by the alcoholysis reaction with polysulfide silane compounds. The present invention achieves superhydrophobic modification of piperazine pyrophosphate by using an alcoholysis reaction and in-situ vesicle coating method.

[0055] The superhydrophobic and thermally stable piperazine pyrophosphate of Example 2 was subjected to SEM testing, and the results were the same as above.

[0056] Figure 2 The diagram shows the reaction mechanism of the alcoholysis reaction between piperazine pyrophosphate and polysulfide silane compounds used in Examples 1 and 2. By removing some of the hydrophilic -OH groups on piperazine pyrophosphate through alcoholysis, the remaining hydrophilic groups self-assemble to form a core, while the long-chain hydrophobic groups of the polysulfide silane compound form a shell on the surface of piperazine pyrophosphate, thereby forming a vesicle structure and achieving the superhydrophobicity and high thermal stability of piperazine pyrophosphate.

[0057] Figure 3 The images show the infrared spectra of piperazine pyrophosphate in Examples 1 and 2, and Comparative Example 1. Comparing the infrared spectra of piperazine pyrophosphate before and after the alcoholysis reaction, it can be seen that the infrared spectra of piperazine pyrophosphate in Examples 1 and 2 after the alcoholysis reaction are higher at 700 cm⁻¹. -1 864cm -1 1210cm -1 New absorption peaks appeared, and these peaks corresponded to the characteristic absorption peaks of polysulfide silane compounds, such as SC, Si-C, and Si-O. Since the piperazine pyrophosphate in Examples 1 and 2, as well as Comparative Example 1, was washed with anhydrous ethanol in a Soxhlet extraction apparatus to remove unreacted polysulfide silane compounds, the infrared spectral results indicate that the piperazine pyrophosphate after the alcoholysis reaction was attached with characteristic groups of the polysulfide silane compounds, confirming the chemical bonding process of the alcoholysis reaction.

[0058] Experimental analysis

[0059] The hydrophobic and flame retardant properties of the products from Examples 1-2 and Comparative Examples 1-4 were tested. The specific test methods and results are as follows:

[0060] 1. Testing method:

[0061] Contact angle: Piperazine pyrophosphate powder was spread evenly onto a glass slide using double-sided tape, and the water contact angle from 1s to 300s was measured and recorded.

[0062] Water absorption: Using a constant temperature and humidity test chamber, the temperature was set to 25℃ and the humidity to 100%. Equal masses of piperazine pyrophosphate powder from the example and the comparative example were spread evenly on a petri dish, and the water absorption rate was tested for the same amount of time.

[0063] Thermogravimetric analysis: Measure 5-10 mg of piperazine pyrophosphate powder, set the heating rate to 20 °C / min, and heat from room temperature to 800 °C in air atmosphere.

[0064] Water resistance: Characterized by the solubility of piperazine pyrophosphate powder in water. Different masses of powder were added to 100 ml of water until dissolved. The greater the solubility, the worse the water resistance.

[0065] 2. Figure 4 The water contact angle of piperazine pyrophosphate with superhydrophobic and high thermal stability in Examples 1 and 2 is shown in Table 1. The hydrophobic properties of the products of Examples 1-2 and Comparative Examples 1-4 are shown in Table 1.

[0066] Table 1

[0067]

[0068]

[0069] As can be seen from Table 1, in the water contact angle characterization, Comparative Example 1, which is piperazine pyrophosphate powder without hydrophobic treatment, is hydrophilic and has no water contact angle. Comparing Examples 1-2 with Comparative Examples 2-4, it can be seen that after using polysulfide silane compounds to generate vesicles in situ to coat piperazine pyrophosphate, the hydrophobicity of piperazine pyrophosphate powder is greatly improved. At the same time, the water resistance is also significantly improved with the increase of the amount of sulfur-containing silane derivative, indicating the efficient preparation of superhydrophobic piperazine pyrophosphate. Conventional silane coupling agents cannot achieve the same hydrophobic modification efficiency as sulfur-containing silane derivatives. Figure 5 The images show the water flotation test results of piperazine pyrophosphate in Examples 1 and 2 and Comparative Example 1, where (a), (b), and (c) represent different viewing angles. These results also verify that the piperazine pyrophosphate products of Examples 1 and 2 possess excellent hydrophobicity.

[0070] As can be seen from Table 1, in the water absorption characterization, the modified products of Examples 1-2 exhibited superior hydrophobic durability and maintained good water resistance in high humidity environments. After 16 hours of constant temperature and humidity test at 100% humidity, the water absorption rate of the modified product of Example 2 was reduced by 92.6% compared with the unmodified pure sample, which can solve the problem of moisture absorption and agglomeration of piperazine pyrophosphate powder.

[0071] 3. The flame retardant performance test results of piperazine pyrophosphate powder in Examples 1-2 and Comparative Examples 1 and 3 are shown in Table 2:

[0072] Table 2

[0073]

[0074] The vesicle structure can block heat and mass transfer, and reduce the thermal oxidation rate of PAPP. As shown in Table 2, the in-situ vesicle coating of piperazine pyrophosphate with polysulfide silane compounds can significantly improve the thermal stability of piperazine pyrophosphate powder. The 1% thermal weight loss temperature of the modified products in Examples 1 and 2 increased by 15°C. The char residue mass of Examples 1-2 at 800°C is higher than that of Comparative Examples 1 and 3. When the char residue rate of the flame retardant is high, a thicker char protective layer can be formed, which can effectively hinder the spread of fire and improve the fire resistance of the material. It can be seen that the in-situ vesicle coating of piperazine pyrophosphate can improve its final char formation performance, thereby improving the flame retardant performance of piperazine pyrophosphate, which is beneficial to reducing the amount of piperazine pyrophosphate used in flame retardant materials.

[0075] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A superhydrophobic and thermally stable piperazine pyrophosphate, characterized in that, The invention includes piperazine pyrophosphate, wherein the surface of the piperazine pyrophosphate is coated with a vesicle structure, and the vesicle structure is a self-assembled structure formed by the alcoholysis reaction of a polysulfide silane compound with piperazine pyrophosphate.

2. The superhydrophobic and thermally stable piperazine pyrophosphate according to claim 1, characterized in that, The mass ratio of piperazine pyrophosphate to polysulfide silane compound is 100:(0.5-5).

3. The superhydrophobic and thermally stable piperazine pyrophosphate according to claim 1, characterized in that, The polysulfide silane compound includes at least one of bis-[γ-(triethoxysilane)propyl]-tetrasulfide and bis-[3-(triethoxysilane)propyl]-disulfide.

4. The method for preparing the superhydrophobic and highly thermally stable piperazine pyrophosphate according to any one of claims 1 to 3, characterized in that, The process includes the following steps: reacting an organic solution of a polysulfide silane compound with piperazine pyrophosphate via an efficient alcoholysis reaction to obtain the superhydrophobic and thermally stable piperazine pyrophosphate.

5. The method for preparing superhydrophobic and highly thermally stable piperazine pyrophosphate according to claim 4, characterized in that, The reaction pH for the alcoholysis reaction is 1-6.

6. The method for preparing superhydrophobic and highly thermally stable piperazine pyrophosphate according to claim 4, characterized in that, The reaction time for the alcoholysis reaction is 1 to 10 minutes, and the reaction temperature is 70 to 120°C.

7. The method for preparing superhydrophobic and highly thermally stable piperazine pyrophosphate according to claim 4, characterized in that, The solvent for the organic solution of the polysulfide silane compound is an alcohol solvent.

8. The method for preparing superhydrophobic and highly thermally stable piperazine pyrophosphate according to claim 4, characterized in that, The alcoholysis reaction was carried out at a rotation speed of 300-1000 rpm.

9. The method for preparing superhydrophobic and highly thermally stable piperazine pyrophosphate according to claim 4, characterized in that, It also includes the following steps: after the mixing reaction, the obtained product is dried at a temperature of 70-120℃.

10. The application of the superhydrophobic and thermally stable piperazine pyrophosphate as described in any one of claims 1 to 3 in polymer flame retardant products.

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