Super-hydrophobic high-thermal-stability piperazine pyrophosphate and preparation method thereof

Abstract

The invention discloses super-hydrophobic high-thermal-stability piperazine pyrophosphate and a preparation method thereof.The super-hydrophobic high-thermal-stability piperazine pyrophosphate comprises piperazine pyrophosphate, the surface of piperazine pyrophosphate is coated with a vesicle structure, and the vesicle structure is a self-assembly structure obtained after alcoholysis reaction of a polysulfide silane compound and piperazine pyrophosphate. According to the sulfur-containing silane material with piperazine pyrophosphate coated with the vesicle structure, piperazine pyrophosphate has super-hydrophobic performance due to the vesicle structure, super-hydrophobic durability is achieved, good water resistance and extremely low moisture absorption can be kept in a high-humidity environment, and the problem that piperazine pyrophosphate powder absorbs moisture and is agglomerated can be solved. The vesicle structure has the effects of blocking heat and substance transfer and reducing the thermal oxidation rate of PAPP, so that the piperazine pyrophosphate provided by the invention also has excellent thermal stability and final char forming performance, and is beneficial to reducing the dosage of the piperazine pyrophosphate in a flame-retardant high polymer material.

Description

Technical Field

[0001] The invention belongs to the technical field of flame retardants, and particularly relates to super-hydrophobic and highly thermally stable piperazine pyrophosphate and a preparation method thereof. Background Art

[0002] Piperazine pyrophosphate (PAPP) is a new type of nitrogen-phosphorus single-component halogen-free intumescent flame retardant. It contains the acid source, gas source and carbon source of the intumescent flame retardant system (IFR). It has the characteristics of high flame retardant efficiency, good heat resistance, low smoke, non-toxicity and anti-drip. It can be used for polymer materials such as polypropylene (PP), polyethylene (PE), epoxy resin (EP), thermoplastic elastomer, etc.

[0003] Compared with other flame retardants, such as ammonium polyphosphate (APP)-based ammonium polyphosphate intumescent flame retardants, new piperazine-based intumescent flame retardants represented by piperazine pyrophosphate have good thermal stability and excellent carbonization performance, which well solves the application problems of ammonium polyphosphate. Therefore, piperazine pyrophosphate has outstanding application performance advantages. However, similar to most flame retardants such as ammonium polyphosphate, piperazine pyrophosphate also has shortcomings such as easy hygroscopic agglomeration, easy migration and precipitation in a hot and humid environment, and poor compatibility with the polymer matrix, which reduces its flame retardant properties and limits its application.

[0004] Existing technical solutions for modifying piperazine pyrophosphate include: Patent CN110483898A uses lubricants and hydrogenated silicone oil to physically / chemically modify piperazine pyrophosphate, which improves the deficiency of moisture absorption and agglomeration of flame retardant powder, but the surface coating treatment of silicone oil will cover the surface of the flame retardant with an oil film, which not only affects the appearance of the flame retardant, but also easily causes the powder to agglomerate after long-term storage, and because the melting and boiling points of silicone oil are both low, the product has poor water resistance in a hot and humid environment; Patent CN115772285A uses aminosilane water-based coupling agent and methyl hydrogenated silicone oil as surface modifier and water-resistant agent respectively to modify piperazine pyrophosphate. In these reaction processes, since low surface energy and hydrophobic groups are not protected and introduced, the hydrophobic efficiency is low, the water resistance is poor in a hot and humid environment, and a higher content of silane coupling agent is required to have hydrophobicity, which increases the production cost of PAPP and affects its application.

[0005] In addition, the super-hydrophobic and highly thermally stable piperazine pyrophosphate obtained by the existing patent scheme can usually only maintain good water resistance at room temperature, and its water resistance is insufficient in a hot and humid environment; at the same time, the durability of the hydrophobic modification is insufficient, and the boiling point of the modifier is low, which causes the piperazine pyrophosphate modifier to easily volatilize and escape when it is blended with a polymer, thereby losing the modification effect. Summary of the invention

[0006] In order to overcome the problems existing in the above-mentioned prior art, the present invention is based on the exploration of the mechanism of the chemical reaction between polysulfur silane compounds and piperazine pyrophosphate, and accurately controls the alcoholysis reaction of a single sulfur silane compound and piperazine pyrophosphate in an efficient and fast manner to obtain the chemical bonding of the polysulfur silane compound and piperazine pyrophosphate. Based on the hydrophilic-hydrophobic self-assembly driving force, a vesicle structure with pyrophosphate as the inner core and the hydrophobic polysulfur silane compound as the outer layer is realized, thereby providing a super-hydrophobic and highly thermally stable piperazine pyrophosphate and a preparation method thereof.

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

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

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

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

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

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

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

[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 comprises the following steps: preparing an alcohol solution of a polysulfur silane compound, subjecting the alcohol solution of the sulfur silane compound to an efficient alcoholysis reaction with piperazine pyrophosphate, and forming a vesicle structure through a hydrophilic-hydrophobic self-assembly driving force to obtain the super-hydrophobic and highly 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 300-1000rpm;

[0023] Preferably, the method further comprises the following step: drying the obtained product after the alcoholysis reaction, and the drying temperature is 70-120°C.

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

[0025] The beneficial effects of the present invention are:

[0026] (1) The present invention provides a super-hydrophobic and highly thermally stable piperazine pyrophosphate, which forms a vesicle structure through an efficient alcoholysis reaction of piperazine pyrophosphate and a polysulfide silane compound. The material has super-hydrophobic properties and a water contact angle of up to 152°. Compared with unmodified piperazine pyrophosphate, it not only greatly reduces water absorption, but also achieves super strong hydrophobic durability, and can maintain good water resistance and extremely low moisture absorption in a high humidity environment, thereby solving the problem of moisture absorption and agglomeration of piperazine pyrophosphate powder.

[0027] (2) The super-hydrophobic and highly thermally stable piperazine pyrophosphate provided by the present invention also has excellent thermal stability and final carbonization performance. Compared with the pure sample before treatment, the 1% thermal weight loss temperature of the super-hydrophobic and highly thermally stable piperazine pyrophosphate is increased by 15°C, and the final residual carbon mass is increased by 94.2%-100%, which is beneficial to reduce the amount of piperazine pyrophosphate used in flame-retardant polymer materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a scanning electron microscope image of the super-hydrophobic and highly thermally stable piperazine pyrophosphate of Example 1;

[0029] Figure 2 Schematic diagram of the efficient alcoholysis reaction of piperazine pyrophosphate and polysulfur silane compounds;

[0030] Figure 3 This is the infrared spectrum of piperazine pyrophosphate before and after alcoholysis reaction;

[0031] Figure 4The water contact angle of the super hydrophobic and highly thermally stable piperazine pyrophosphate of Examples 1 and 2;

[0032] Figure 5 The results of the water floating test of piperazine pyrophosphate of Examples 1 and 2 and Comparative Example 1 are shown, wherein (a), (b), and (c) represent different observation angles, respectively. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below through specific examples. The raw materials used in the following examples, unless otherwise specified, can be obtained from conventional commercial sources or prepared and separated by simple synthesis; the processes used, unless otherwise specified, 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 Pusai Fulin Chemical Co., Ltd.

[0035] Example 1

[0036] This embodiment provides a super-hydrophobic and highly thermally stable piperazine pyrophosphate, and the preparation method thereof is as follows:

[0037] Bis-[γ-(triethoxysilyl)propyl]-tetrasulfide and anhydrous ethanol were mixed in a mass ratio of 4:1 to obtain a mixed solution, and then the mixed solution and piperazine pyrophosphate powder were poured into a reactor, wherein the mass ratio of bis-[γ-(triethoxysilyl)propyl]-tetrasulfide to piperazine pyrophosphate powder was 0.75:100, and an efficient alcoholysis reaction was carried out, wherein the reaction pH was 3.5, the reaction temperature was 80°C, the rotation speed was 800 rpm, the reaction was carried out for 3 minutes, the mixture was taken out, and dried in an oven at 80°C for 1 hour to obtain super-hydrophobic and highly thermally stable piperazine pyrophosphate.

[0038] Example 2

[0039] This embodiment provides a super-hydrophobic and highly thermally stable piperazine pyrophosphate, and the preparation method thereof is as follows:

[0040] Bis-[γ-(triethoxysilyl)propyl]-tetrasulfide and anhydrous ethanol were mixed in a mass ratio of 4:1 to obtain a mixed solution, and then the mixed solution and piperazine pyrophosphate powder were poured into a reactor, wherein the mass ratio of bis-[γ-(triethoxysilyl)propyl]-tetrasulfide to piperazine pyrophosphate powder was 1:100, and an efficient alcoholysis reaction was carried out, wherein the reaction pH was 3.5, the reaction temperature was 80°C, the rotation speed was 800 rpm, the reaction was carried out for 3 minutes, the mixture was taken out, and dried in an oven at 80°C for 1 hour to obtain super-hydrophobic and highly thermally stable piperazine pyrophosphate.

[0041] Comparative Example 1

[0042] This comparative example provides a kind of piperazine pyrophosphate, and its preparation method is as follows:

[0043] Pour piperazine pyrophosphate powder into a reactor and perform a high-speed mixing reaction, wherein the reaction temperature is 80° C., the rotation speed is 800 rpm, the reaction is performed for 3 minutes, the mixture is taken out, 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 piperazine pyrophosphate mixture, and its preparation method is as follows:

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

[0047] Comparative Example 3

[0048] This comparative example provides a piperazine pyrophosphate mixture, and its preparation method is as follows:

[0049] γ-Glycidyloxypropyltrimethoxysilane and anhydrous ethanol are mixed in a mass ratio of 4:1 to obtain a mixed solution, and then the mixed solution and piperazine pyrophosphate powder are poured into a reactor, wherein the mass ratio of γ-aminopropyltriethoxysilane to piperazine pyrophosphate powder is 1:100, and a high-speed mixing reaction is carried out, wherein the reaction temperature is 80°C, the rotation speed is 800 rpm, the reaction is performed for 3 minutes, and the mixture is taken out and dried in an oven at 80°C for 1 hour to obtain a piperazine pyrophosphate mixture.

[0050] Comparative Example 4

[0051] This comparative example provides a piperazine pyrophosphate mixture, and its preparation method is as follows:

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

[0053] Material characterization

[0054] Figure 1This is a scanning electron microscope (SEM) image of the super-hydrophobic and highly thermally stable piperazine pyrophosphate in Example 1. It can be seen from the figure that the piperazine pyrophosphate powder is coated with a vesicle structure generated by an alcoholysis reaction with a polysulfide silane compound through a hydrophilic-hydrophobic self-assembly driving force. The present invention adopts an alcoholysis reaction to generate vesicles in situ to achieve super-hydrophobic modification of piperazine pyrophosphate.

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

[0056] Figure 2 The reaction mechanism flow chart of the alcoholysis reaction of piperazine pyrophosphate and polysulfur silane compounds used in Examples 1 and 2. Some of the hydrophilic groups -OH on piperazine pyrophosphate are removed by alcoholysis reaction, and the remaining hydrophilic groups are self-assembled to form a core, while the long-chain hydrophobic groups of the polysulfur silane compound are coated with a shell on the surface of piperazine pyrophosphate, thereby forming a vesicle structure, achieving super hydrophobicity and high thermal stability of piperazine pyrophosphate.

[0057] Figure 3 1 is the infrared spectra of piperazine pyrophosphate of Examples 1 and 2 and Comparative Example 1. By comparing the infrared spectra of piperazine pyrophosphate before and after alcoholysis reaction, it can be seen that the infrared spectra of piperazine pyrophosphate after alcoholysis reaction in Examples 1 and 2 are at 700 cm -1 , 864cm -1 , 1210cm -1 New absorption peaks appeared at the positions, and the positions of these absorption peaks were exactly the positions of characteristic absorption peaks of SC, Si-C, Si-O, etc. of polysulfur silane compounds. Since the unreacted polysulfur silane compounds in Examples 1 and 2 and Comparative Example 1 tested by infrared spectroscopy were washed with anhydrous ethanol in a Soxhlet extraction apparatus, the infrared spectrum results showed that the characteristic groups of polysulfur silane compounds were attached to the piperazine pyrophosphate after the alcoholysis reaction, confirming the chemical bonding process of the alcoholysis reaction.

[0058] Experimental analysis

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

[0060] 1. Test method:

[0061] Contact angle: Use double-sided tape to spread piperazine pyrophosphate powder onto a glass slide, and test and calculate the water contact angle from 1s to 300s.

[0062] Water absorption: Using a constant temperature and humidity test box, set the temperature to 25°C and the humidity to 100%, spread the piperazine pyrophosphate powder of the embodiment and the comparative example of equal mass on a surface dish, and test the water absorption rate under the same time.

[0063] Thermogravimetric analysis: 5-10 mg of piperazine pyrophosphate powder was measured and the temperature was raised from room temperature to 800°C at a rate of 20°C / min in an air atmosphere.

[0064] Water resistance: It is characterized by the solubility of piperazine pyrophosphate powder in water. Different masses of powder are added into 100 ml of water until dissolved. The greater the solubility, the worse the water resistance.

[0065] 2. Figure 4 The water contact angle of the super-hydrophobic and highly thermally stable piperazine pyrophosphate of Examples 1 and 2; 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 characterization of water contact angle, comparative example 1 is that the piperazine pyrophosphate powder that has not been hydrophobically treated is hydrophilic and has no water contact angle; by comparing examples 1-2 with comparative examples 2-4, it can be seen that after the piperazine pyrophosphate is coated with in situ generated vesicles using a polysulfur silane compound, the hydrophobicity of the piperazine pyrophosphate powder is greatly improved, and the water resistance is also significantly improved with the increase in the amount of sulfur-containing silane derivatives, indicating the efficient preparation of superhydrophobic piperazine pyrophosphate, while conventional silane coupling agents cannot achieve the same hydrophobic modification efficiency as sulfur-containing silane derivatives. Figure 5 The results of the water floating test of piperazine pyrophosphate of Examples 1 and 2 and Comparative Example 1 are shown, wherein (a), (b), and (c) represent different observation angles, respectively. It can also be verified that the piperazine pyrophosphate products of Examples 1 and 2 have excellent hydrophobicity.

[0070] As can be seen from Table 1, in the water absorption characterization, the modified products of Examples 1-2 exhibited super strong hydrophobic durability and could maintain good water resistance in a high humidity environment. After a constant temperature and humidity test at 100% humidity for 16 hours, 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 of Examples 1-2 and Comparative Examples 1 and 3 are shown in Table 2:

[0072] Table 2

[0073]

[0074] The vesicle structure has the functions of blocking heat and material transfer, and reducing the thermal oxidation rate of PAPP. As can be seen from Table 2, after the in-situ generation of vesicles for piperazine pyrophosphate by polysulfur silane compounds can significantly improve the thermal stability of piperazine pyrophosphate powder, the 1% thermal weight loss temperature of the modified products of Examples 1 and 2 is increased by 15°C; the residual carbon mass of Examples 1-2 at 800°C is higher than that of Comparative Examples 1 and 3. When the residual carbon rate of the flame retardant is high, a thicker carbonized protective layer can be formed, which effectively hinders the spread of fire and improves the fire resistance of the material. It can be seen that the in-situ generation of vesicles for piperazine pyrophosphate can improve its final carbonization performance, thereby improving the flame retardant properties of piperazine pyrophosphate, which is beneficial to reduce the amount of piperazine pyrophosphate used in flame retardant materials.

[0075] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A super-hydrophobic and highly thermally stable piperazine pyrophosphate, characterized in that: The invention comprises piperazine pyrophosphate, the surface of which is coated with a vesicle structure, and the vesicle structure is a self-assembled structure after the alcoholysis reaction of a polysulfur silane compound and piperazine pyrophosphate.

2. The super-hydrophobic, highly thermally stable piperazine pyrophosphate according to claim 1, wherein The mass ratio of the piperazine pyrophosphate to the polysulfide silane compound is 100:(0.5-5).

3. The super-hydrophobic high thermal stability piperazine pyrophosphate according to claim 1, characterized in that, The polysulfur silane compound includes at least one of bis-[γ-(triethoxysilyl)propyl]-tetrasulfide and bis-[3-(triethoxysilyl)propyl]-disulfide.

4. The method for preparing the super-hydrophobic and highly thermally stable piperazine pyrophosphate according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: subjecting an organic solution of a polysulfur silane compound to an efficient alcoholysis reaction with piperazine pyrophosphate to obtain the super-hydrophobic piperazine pyrophosphate with high thermal stability.

5. according to the preparation method of the super hydrophobic high thermal stability piperazine pyrophosphate of claim 4, it is characterized in that, The reaction pH of the alcoholysis reaction is 1-6.

6. The preparation method of the super-hydrophobic high thermal stability piperazine pyrophosphate according to claim 4, characterized in that, The reaction time of the alcoholysis reaction is 1 to 10 minutes, and the reaction temperature of the alcoholysis reaction is 70 to 120°C.

7. The preparation method of the super-hydrophobic high thermal stability piperazine pyrophosphate according to claim 4, characterized in that, The solvent of the organic solution of the polysulfur silane compound is an alcohol solvent.

8. The preparation method of the super-hydrophobic high thermal stability piperazine pyrophosphate according to claim 4, characterized in that, The alcoholysis reaction is carried out at a rotation speed of 300-1000 rpm.

9. The method for preparing the super-hydrophobic and highly thermally stable piperazine pyrophosphate according to claim 4, wherein: The method further comprises the following steps: after the mixing reaction, drying the obtained product at a drying temperature of 70-120°C.

10. Use of the super-hydrophobic and highly thermally stable piperazine pyrophosphate according to any one of claims 1 to 3 in polymer flame-retardant products.

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