An ammonium phytate-modified silica flame retardant, its preparation method and application

Abstract

The present invention belongs to the technical field of flame retardant materials, and particularly relates to an ammonium phytate modified silica flame retardant, a preparation method thereof and an application. The ammonium phytate modified silica flame retardant provided by the present invention comprises silica and ammonium phytate chemically combined with the silica. The ammonium phytate modified silica flame retardant has good compatibility with PBAT. After being compounded with PBAT, it can not only significantly improve the flame retardancy, but also have the functions of strengthening and toughening.

Description

Technical Field

[0001] The present invention belongs to the technical field of flame retardant materials, and particularly relates to an ammonium phytate modified silica flame retardant, its preparation method and application. Background Art

[0002] Poly(butylene adipate-co-terephthalate) (PBAT), as a biodegradable and environmentally friendly polymer material, has become a research hotspot in the field of materials and attracted much attention in recent years. PBAT has good processing properties, mechanical properties, heat resistance and biocompatibility, and is widely used in fields such as agricultural films, lunch boxes, express packaging and thermal insulation materials. However, its disadvantages such as easy combustion, poor flame retardant performance, low strength and low modulus have become the main limiting factors for its comprehensive promotion and application.

[0003] Currently, according to literature reports, the phosphorus-nitrogen synergistic flame retardant system is still the best system applicable to PBAT flame retardants. Phytate, as an organic phosphorus compound extracted from plant seeds, has great potential to prepare nitrogen-phosphorus flame retardants for flame retardant modification of PBAT through molecular design or modification based on its biological origin and the advantage of rich phosphorus elements in the molecule.

[0004] Currently, the flame retardants applied to PBAT-based flame retardant composites are mainly traditional flame retardants such as ammonium phosphate and phosphate esters, or inorganic particles containing flame retardant elements such as carbon nanotubes (CNT), montmorillonite (OMMT) and silica. However, when the above flame retardants are applied to PBAT composites, the compatibility between the flame retardant and PBAT is poor. Although the flame retardancy of PBAT-based flame retardant composites is improved to a certain extent, their toughness is also damaged, and the strength or rigidity is significantly reduced. Summary of the Invention

[0005] The purpose of the present invention is to provide an ammonium phytate modified silica flame retardant, its preparation method and application. The ammonium phytate modified silica flame retardant provided by the present invention has good compatibility with PBAT, and the flame retardant composite obtained by compounding with PBAT has good flame retardant efficiency and toughness.

[0006] In order to achieve the above purpose, the present invention provides the following technical solutions:

[0007] The present invention provides an ammonium phytate modified silica flame retardant, which includes silica and ammonium phytate chemically combined with the silica.

[0008] Preferably, the mass ratio of ammonium phytate to silica is 1-2:1.

[0009] The present invention also provides a preparation method of the above-mentioned ammonium phytate modified silica flame retardant, which includes the following steps:

[0010] Mix the ammonium phytate solution and the silica aqueous dispersion, and carry out a substitution reaction to obtain the ammonium phytate-modified silica flame retardant; the pH value of the silica aqueous dispersion is 2-4.

[0011] Preferably, the ammonium phytate solution includes ammonium phytate, ethanol and water.

[0012] Preferably, the concentration of ammonium phytate in the ammonium phytate solution is 3-20 wt%; the volume ratio of ethanol to water in the ammonium phytate solution is 0.5:1-3:1.

[0013] Preferably, the temperature of the substitution reaction is 40-60 °C, and the time is 3-6 h.

[0014] The present invention also provides the application of the ammonium phytate-modified silica flame retardant described above or the ammonium phytate-modified silica flame retardant prepared by the above preparation method in flame retardant materials.

[0015] The present invention also provides a PBAT-based flame retardant composite material, which includes the following preparation raw materials by mass:

[0016] 80-95 parts of PBAT;

[0017] 5-20 parts of ammonium phytate-modified silica flame retardant;

[0018] The ammonium phytate-modified silica flame retardant is the ammonium phytate-modified silica flame retardant described above.

[0019] The present invention also provides a preparation method of the above-mentioned composite material, which includes the following steps:

[0020] After mixing PBAT and the ammonium phytate-modified silica flame retardant, carry out melt blending and extrusion molding in sequence to obtain the PBAT-based flame retardant composite material.

[0021] Preferably, the temperature of the melt blending is 150-200 °C.

[0022] The present invention provides an ammonium phytate-modified silica flame retardant, which includes silica and ammonium phytate chemically combined with the silica. Due to the presence of functional groups such as biomass phytate and amine groups in the flame retardant provided by the present invention, it can easily interact with the PBAT matrix surface and improve biocompatibility. In addition, the flame retardant is rich in flame retardant elements such as phosphorus, nitrogen and silicon. By introducing it into the matrix, it can significantly improve the flame retardant performance of the resin. Therefore, the ammonium phytate-modified silica flame retardant provided by the present invention has good compatibility with PBAT. After being compounded with PBAT, it can not only significantly improve the flame retardancy, but also have the functions of strengthening and toughening.

[0023] The data of the examples show that the flame retardant performance of the composite material obtained by compounding the flame retardant provided by the present invention with PBAT can reach V-1 level of UL-94. The elongation at break of the composite material is increased by 13.0% compared with pure PBAT, and the tensile strength and flexural strength can be increased by 31.4% and 44.4% respectively.

[0024] The present invention also provides a preparation method of the ammonium phytate-modified silica flame retardant described above, comprising the following steps: mixing an ammonium phytate solution and a silica aqueous dispersion, and carrying out a substitution reaction to obtain the ammonium phytate-modified silica flame retardant; the pH value of the silica aqueous dispersion is 2-4. The preparation method of the present invention is simple, easy to control, and convenient for industrial production. Description of the Drawings

[0025] Figure 1 It is the Mapping spectrum of the ammonium phytate-modified silica flame retardant of Example 1;

[0026] Figure 2 It is the Mapping spectrum of the ammonium phytate-modified silica flame retardant of Example 2;

[0027] Figure 3 It is the Mapping spectrum of the silica particles. Detailed Description of the Invention

[0028] The present invention provides an ammonium phytate-modified silica flame retardant, comprising silica and ammonium phytate chemically combined with the silica.

[0029] In the present invention, the mass ratio of the ammonium phytate to the silica is preferably 1-2:1, more preferably 1.5-2:1.

[0030] The present invention also provides a preparation method of the ammonium phytate-modified silica flame retardant described above, comprising the following steps:

[0031] Mixing an ammonium phytate solution and a silica aqueous dispersion, and carrying out a substitution reaction to obtain the ammonium phytate-modified silica flame retardant; the pH value of the silica aqueous dispersion is 2-4.

[0032] In the present invention, the ammonium phytate solution preferably comprises ammonium phytate, ethanol and water. In the present invention, the mass concentration of ammonium phytate in the ammonium phytate solution is preferably 3-20 wt%, more preferably 10 wt%. In the present invention, the mass ratio of ethanol to water in the ammonium phytate solution is preferably 0.5:1-3:1, more preferably 1:1. In the present invention, the preparation of the ammonium phytate solution is preferably dispersing ammonium phytate in a mixed solvent of ethanol and water.

[0033] In the present invention, the ammonium phytate is preferably prepared by self.

[0034] In the present invention, the preparation method of ammonium phytate preferably includes the following steps:

[0035] Mix an aqueous solution of an amine compound and an aqueous solution of phytic acid, and carry out an amidation reaction to obtain ammonium phytate.

[0036] In the present invention, the amine compound in the aqueous solution of the amine compound preferably includes a diamine and / or a polyamine. In the present invention, the diamine preferably includes one or more of adipic diamide, polyoxyethylene diamine, dicyandiamide, p-phenylenediamine and m-phenylenediamine, more preferably dicyandiamide; the triamine preferably includes one or more of diethylenetriamine, tris(4-aminophenyl)amine and tris(2-cyanoethyl)amine, more preferably tris(4-aminophenyl)amine. In the present invention, the concentration of the amine compound in the aqueous solution of the amine compound is preferably 0.1 - 1 mol / L, more preferably 0.4 - 0.6 mol / L.

[0037] In the present invention, the preparation of the aqueous solution of the amine compound is preferably obtained by dispersing the amine compound in deionized water. In the present invention, the dispersion method is preferably magnetic stirring, the temperature of the magnetic stirring is preferably 80 - 100 °C, more preferably 90 °C, and the time is preferably 1 - 2 h, more preferably 1.5 h.

[0038] In the present invention, the concentration of phytic acid in the aqueous solution of phytic acid is preferably 25 - 35 wt%, more preferably 30 wt%. In the present invention, the molar ratio of the amine compound in the aqueous solution of the amine compound to the phytic acid in the aqueous solution of phytic acid is preferably 2:1 - 10:1, more preferably 6:1.

[0039] In the present invention, the mixing of the aqueous solution of the amine compound and the aqueous solution of phytic acid is preferably adding the aqueous solution of phytic acid dropwise to the aqueous solution of the amine compound. In the present invention, the dropping speed is preferably 10 - 120 drops / min, more preferably 30 drops / min. In the present invention, the dropping is preferably carried out through a constant pressure dropping funnel.

[0040] In the present invention, the temperature of the amidation reaction is preferably 80 - 100 °C, more preferably 85 - 95 °C, and the heat preservation time is preferably 2 - 5 h, more preferably 3 - 4 h.

[0041] In the present invention, after the amidation reaction, it is preferably further included to sequentially carry out static precipitation, suction filtration, washing and drying on the system obtained from the amidation reaction. In the present invention, the time for the static precipitation is preferably 0.5 - 1 h, more preferably 0.6 - 0.7 h. The present invention does not make specific limitations on the suction filtration, and it can be carried out by using the operations well-known to those skilled in the art. In the present invention, the washing is preferably washing with deionized water, and the number of washing times is preferably ≥3, more preferably 3 - 5. The present invention does not make specific limitations on the drying, and the doped moisture after washing can be removed by using the operations well-known in the art.

[0042] In the present invention, the preparation of the silica aqueous dispersion preferably includes: dispersing silica in deionized water and adjusting the pH.

[0043] In the present invention, in the present invention, the mass concentration of silica in the silica aqueous dispersion is preferably 5 - 20%, more preferably 10%. The dispersion is preferably carried out under magnetic stirring conditions. In the present invention, the pH adjusting agent is preferably hydrochloric acid, and the mass concentration of the hydrochloric acid is preferably 37%. In the present invention, the pH value of the silica aqueous dispersion is preferably 2 - 4, more preferably 3.

[0044] In the present invention, the mass ratio of ammonium phytate in the ammonium phytate solution to silica in the silica aqueous dispersion is preferably 1 - 2:1, more preferably 1.2 - 1.5:1.

[0045] In the present invention, the mixing is preferably dropping the ammonium phytate solution into the silica aqueous dispersion.

[0046] In the present invention, the temperature of the substitution reaction is preferably 40 - 60 °C, more preferably 50 °C, and the time is preferably 3 - 6 h, more preferably 4 - 5 h. In the present invention, the substitution reaction is preferably carried out under magnetic stirring conditions. In the present invention, the substitution reaction is that NH4 in the ammonium phytate structure + reacts with the silanol groups on the surface of SiO2.

[0047] In the present invention, after the substitution reaction, it is preferably further included to sequentially carry out static precipitation, suction filtration, washing and drying on the suspension obtained from the substitution reaction. In the present invention, the time for the static precipitation is preferably 0.5 - 1 h, more preferably 0.6 - 0.7 h. The present invention does not make specific limitations on the suction filtration, and it can be carried out by using the operations well-known to those skilled in the art. In the present invention, the washing is preferably washing with deionized water, and the number of washing times is preferably ≥3, more preferably 3 - 5. In the present invention, the drying temperature is preferably 70 - 90 °C, more preferably 80 °C, and the time is preferably 12 - 24 h, more preferably 15 - 20 h.

[0048] The present invention also provides an application of the above-mentioned flame retardant in flame-retardant materials.

[0049] The present invention also provides a PBAT-based flame-retardant composite material, which comprises the following preparation raw materials in parts by mass:

[0050] 80-95 parts of PBAT;

[0051] 5-20 parts of ammonium phytate-modified silica flame retardant;

[0052] The ammonium phytate-modified silica flame retardant is the above-mentioned ammonium phytate-modified silica flame retardant.

[0053] In the present invention, the preparation raw materials of the PBAT-based flame-retardant composite material preferably comprise 80-95 parts of PBAT in parts by mass, more preferably 85-90 parts. In the present invention, the melt index of the PBAT is preferably 5-7 g / 10 min. In the present invention, the PBAT is preferably one or more of TH801T PBAT provided by Jinhui Zhaolong High-Tech Co., Ltd., 1908PBAT provided by Jinhui Zhaolong High-Tech Co., Ltd., and Ecoflex PBAT provided by BASF Company of Germany, and more preferably 1908PBAT provided by Jinhui Zhaolong High-Tech Co., Ltd.

[0054] In the present invention, the preparation raw materials of the PBAT-based flame-retardant composite material preferably comprise 5-20 parts of ammonium phytate-modified silica flame retardant in parts by mass, more preferably 10-15 parts.

[0055] The present invention also provides a preparation method of the above-mentioned PBAT-based flame-retardant composite material, which comprises the following steps:

[0056] After mixing the PBAT matrix resin and the ammonium phytate-modified silica flame retardant, melt blending and extrusion molding are carried out in sequence to obtain the PBAT-based flame-retardant composite material.

[0057] In the present invention, before the mixing, it is preferably further included to dry the PBAT and the ammonium phytate-modified silica flame retardant respectively. In the present invention, the drying temperature is independently preferably 60-100 °C, more preferably 70-90 °C, and the drying time is independently preferably 6-10 h, more preferably 8-9 h.

[0058] In the present invention, the preferred way to mix the PBAT and the ammonium phytate-modified silica flame retardant is stirring, and the rotation speed of the stirring is preferably 500 - 2000 rpm, more preferably 1000 rpm. In the present invention, the temperature of the melt blending is preferably 150 - 200 °C, more preferably 170 - 180 °C. In the present invention, the extrusion molding is preferably carried out in a twin-screw extruder, and the extrusion conditions of the extrusion molding preferably include: the rotation speed of the screw is preferably 80 - 200 rpm, more preferably 150 rpm, and the feeding rate is 10 - 15 rpm. In the present invention, the injection molding temperature of the extrusion molding is specifically preferably: the temperature of zone 1 is preferably 145 ± 10 °C, the temperature of zone 2 is preferably 160 ± 10 °C, the temperature of zone 3 is preferably 175 ± 10 °C, the temperature of zone 4 is preferably 190 ± 10 °C, and the temperature of zone 5 is preferably 205 ± 10 °C.

[0059] To further illustrate the present invention, the following describes the solutions of the present invention in detail with reference to the examples, but they should not be construed as limiting the protection scope of the present invention.

[0060] Example 1

[0061] ① Disperse 0.1 moL of tris(4-aminophenyl)amine in 1 L of deionized water, and magnetically stir for 2 h at 100 °C to obtain a stable 0.1 mol / L aqueous solution of tris(4-aminophenyl)amine;

[0062] ② Slowly add 12 mL of a 30% by mass aqueous solution of phytic acid dropwise (the dropping rate is 30 drops / min) through a constant pressure dropping funnel into 100 mL of the aqueous solution of (4-aminophenyl)amine, magnetically stir and mix evenly, then carry out an amidation reaction at 100 °C for 3 h. Subsequently, let the product obtained from the amidation reaction stand for precipitation for 1 h, vacuum filter, wash with deionized water 3 times, and dry to obtain ammonium phytate;

[0063] ③ Disperse 10 g of dry silica in deionized water under magnetic stirring, and adjust the pH value to 2 - 3 with 37 wt% hydrochloric acid to obtain a 10 wt% aqueous dispersion of silica.

[0064] ④ Disperse 5 g of ammonium phytate in 50 mL of a mixed solvent of ethanol and water with a mass ratio of 1:1, and magnetically stir at room temperature for 1 h to obtain an ammonium phytate solution;

[0065] ⑤ Slowly add the ammonium phytate solution dropwise (the dropping rate is 50 drops / min) to the aqueous dispersion of silica, raise the temperature to 50 °C and magnetically stir for 5 h. After the obtained suspension stands for 1 h, vacuum filter, wash with deionized water 5 times, and dry at 80 °C for 24 h to obtain the ammonium phytate-modified silica flame retardant.

[0066] Example 2

[0067] The difference from Example 1 is only that: the mass of ammonium phytate in step ④ is 10 g.

[0068] Application Example 1

[0069] PBAT and the ammonium phytate-modified silica flame retardant prepared in Example 1 were dried in a vacuum drying oven at 80 °C for 6 h.

[0070] By mass, 95 parts of PBAT and 5 parts of the ammonium phytate-modified silica flame retardant were weighed and mixed in a high-speed mixer at a speed of 1000 rpm for 15 min. The obtained mixed material was melt-blended at 180 °C and then extrusion-molded to obtain a PBAT-based flame-retardant composite material. The heating zone temperatures for extrusion molding were set as 145 °C in zone 1, 160 °C in zone 2, 175 °C in zone 3, 190 °C in zone 4, and 205 °C in zone 5. The main screw speed was 150 rpm, and the feeding rate was 15 rpm.

[0071] Application Example 2

[0072] The difference from Application Example 1 is only that: there are 90 parts of PBAT and 10 parts of the ammonium phytate-modified silica flame retardant.

[0073] Application Example 3

[0074] The difference from Application Example 1 is only that: there are 85 parts of PBAT and 15 parts of the ammonium phytate-modified silica flame retardant.

[0075] Application Example 4

[0076] The difference from Application Example 1 is only that: there are 80 parts of PBAT and 20 parts of the ammonium phytate-modified silica flame retardant.

[0077] Application Example 5

[0078] The difference from Application Example 1 is only that: the ammonium phytate-modified silica flame retardant prepared in Example 1 is replaced with the ammonium phytate-modified silica flame retardant prepared in Example 2.

[0079] Application Example 6

[0080] The difference from Application Example 2 is only that: the ammonium phytate-modified silica flame retardant prepared in Example 1 is replaced with the ammonium phytate-modified silica flame retardant prepared in Example 2.

[0081] Application Example 7

[0082] The difference from Application Example 3 is only that: the ammonium phytate-modified silica flame retardant prepared in Example 1 is replaced with the ammonium phytate-modified silica flame retardant prepared in Example 2.

[0083] Application Example 8

[0084] The difference from Application Example 4 is only that: the ammonium phytate-modified silica flame retardant prepared in Example 1 is replaced with the ammonium phytate-modified silica flame retardant prepared in Example 2.

[0085] Comparative Application Example 1

[0086] The difference from Application Example 1 is only that: the comparative application example does not contain ammonium phytate-modified silica flame retardant.

[0087] Comparative Application Example 2

[0088] The difference from Application Example 2 is only that: the ammonium phytate-modified silica flame retardant prepared in Example 1 is replaced with silica particles.

[0089] Comparative Application Example 3

[0090] The difference from Application Example 2 is only that: the ammonium phytate-modified silica flame retardant prepared in Example 1 is replaced with ammonium phytate.

[0091] Comparative Application Example 4

[0092] The difference from Application Example 2 is only that: the ammonium phytate-modified silica flame retardant prepared in Example 1 is replaced with a commercially available ammonium polyphosphate intumescent flame retardant.

[0093] Comparative Application Example 5

[0094] The difference from Comparative Application Example 2 is only that: there are 85 parts of PBAT and 15 parts of silica particles.

[0095] Comparative Application Example 6

[0096] The difference from Comparative Application Example 3 is only that: there are 85 parts of PBAT and 15 parts of ammonium phytate.

[0097] Comparative Application Example 7

[0098] The difference from Comparative Application Example 4 is only that: there are 85 parts of PBAT and 15 parts of ammonium polyphosphate flame retardant.

[0099] Test Example

[0100] The products prepared in Application Examples 1-8 and Comparative Application Examples 1-7 were made into test specimens for flame retardancy and mechanical properties testing. Among them, the size of the test specimen for flame retardancy testing was length×width×thickness = 130 mm×10 mm×3.2 mm, and the size of the standard test specimen for mechanical properties was a dumbbell-shaped plastic tensile property test specimen of 150 mm×20 mm×4 mm and a plastic flexural property test specimen of 80 mm×10 mm×4 mm. Test method: Vertical burning (UL-94) test was carried out in accordance with the GB / T 2408 2008 standard, and mechanical property test was carried out in accordance with the GB / T 1040 2006 standard. The flame retardancy test data and mechanical property test results are shown in Table 1 and Table 2 respectively.

[0101] Table 1 Flame retardancy test data of Application Examples 1-8 and Comparative Application Examples 1-7

[0102]

[0103]

[0104] In Table 1, t1 a (s) is the average time of the first combustion, and t1 b (s) is the average time of the second combustion, and NR c means that the flame retardancy level cannot be achieved, and the LOI value is the limiting oxygen index value.

[0105] It can be seen from Table 1 that the material prepared from pure PBAT resin (Comparative Application Example 1) is easy to burn, has serious dripping, has no flame retardancy level, and the LOI value is 20.1%; when silica particles are introduced alone (Comparative Application Examples 2 and 5), the material is still easy to burn and fails to reach the flame retardancy level; while after adding ammonium phytate flame retardant alone (Comparative Application Examples 3 and 6), the dripping phenomenon of the material is improved to a certain extent, and Comparative Application Examples 3 and 6 reach the V-2 flame retardancy level of UL94, and the LOI increases slightly; when adding commercially available ammonium polyphosphate flame retardant alone (Comparative Application Examples 4 and 7), the flame retardancy of the material is improved, and among them, Comparative Application Example 7 can reach the V-1 flame retardancy level of UL94, and the LOI value reaches 23.5%.

[0106] Adding ammonium phytate-coated silica flame retardant (mass ratio of silica to ammonium phytate is 2:1) (Application Examples 1-4), the material can significantly inhibit melt dripping, and the LOI value increases with the increase of the hybrid flame retardant. Application Examples 3 and 4 can reach the V-1 flame retardant grade, and the LOI value is 23.6%; while adding the flame retardant prepared with a mass ratio of silica to ammonium phytate of 1:1, the flame retardant effect of the composite material (Application Examples 5-8) is more significant. With the increase of the content of the hybrid flame retardant, the flame retardant grade also gradually improves. Among them, Application Examples 6-8 all reach the V-1 flame retardant grade, and the effect of inhibiting dripping is obvious. The LOI value of Application Example 8 increases to 25.1%. Comparing the two hybrid flame retardant systems of ammonium phytate-coated silica with different mass ratios, under the condition of the same addition amount, the hybrid flame retardant prepared with a mass ratio of silica to ammonium phytate of 1:1 has better anti-melt dripping performance, longer inhibition of flame combustion time, and higher LOI value than the hybrid particle flame retardant system prepared with a mass ratio of silica to ammonium phytate of 2:1 in the PBAT composite material.

[0107] It can be seen from Table 1 that under the condition of the same addition amount, the ability to inhibit dripping, flame retardant grade, LOI value, etc. of the composite material prepared by adding ammonium phytate-coated silica flame retardant are significantly better than those of adding silica, ammonium phytate, and commercially available ammonium polyphosphate flame retardant systems alone.

[0108] Table 2 Mechanical property test data of Application Examples 1-8 and Comparative Application Examples 1-7

[0109]

[0110]

[0111] It can be seen from Table 2 that the pure PBAT resin (Comparative Application Example 1) has a high elongation at break, showing excellent ductility, but low strength and modulus; when introducing silica particles alone (Comparative Application Examples 2 and 5), the strength and modulus of the material increase, and the elongation at break decreases slightly; while after adding ammonium phytate or ammonium polyphosphate flame retardant alone, the performance of the material does not improve significantly.

[0112] Adding ammonium phytate-coated silica flame retardant (Application Examples 1-8), the tensile strength, elastic modulus, and flexural strength of the composite material are significantly higher than those of Comparative Application Examples 1-7. Among them, when the addition amount of ammonium phytate-coated silica flame retardant is 15 parts (Application Examples 3 and 7), the tensile strength and flexural strength of the material reach the maximum values. Application Example 3 is increased by 31.4% and 44.4% respectively compared with Comparative Application Example 1. The elongation at break of the composite material shows a trend of first increasing and then decreasing with the increase of the content of the hybrid flame retardant. When the addition amount of the hybrid flame retardant is 10 parts, the elongation at break of the material can reach the best value. Application Example 2 is increased by 13.0% compared with Comparative Application Example 1.

[0113] Based on the test results in Table 1 and Table 2, the flame-retardant composite of ammonium phytate-modified silica-reinforced PBAT can not only significantly improve the flame-retardant grade and anti-dripping ability of the matrix resin, showing a remarkable flame-retardant effect, but also improve the strength and modulus of the material, while maintaining excellent elongation at break and toughness, showing good compatibility with PBAT resin. Among them, when the hybrid flame retardant prepared with a mass ratio of silica to ammonium phytate of 1:1 is used to modify PBAT, the flame-retardant effect of the composite material is more significant. This shows that the ammonium phytate-coated silica-modified and reinforced PBAT flame-retardant composite provided by the present invention can significantly improve the defects of low strength and insufficient rigidity of PBAT, can improve the comprehensive mechanical properties of the system, and at the same time endow the composite system with excellent flame-retardant properties.

[0114] The present invention also carried out characteristic spectrum analysis (Mapping spectrum) on the ammonium phytate-modified silica flame retardant and silica particles prepared in Example 1 and Example 2, and the test results are shown in Figures 1 to 3 . Among them Figure 1 (a) is the SEM morphology diagram of Example 1, Figure 1 (b) is the nitrogen element distribution diagram of Mapping of Example 1, Figure 1 (c) is the phosphorus element distribution diagram of Mapping of Example 1, Figure 1 (d) is the total energy spectrum diagram of element distribution of Example 1. Figure 2 (a) is the SEM morphology diagram of Example 2, Figure 2 (b) is the nitrogen element distribution diagram of Mapping of Example 2, Figure 2 (c) is the phosphorus element distribution diagram of Mapping of Example 2, Figure 2 (d) is the total energy spectrum diagram of element distribution of Example 2. Figure 3 (a) is the SEM morphology diagram of silica particles, Figure 3 (b) is the oxygen element distribution diagram of Mapping of silica particles, Figure 3 (c) is the silicon element distribution diagram of Mapping of silica particles, Figure 3 (d) is the total energy spectrum diagram of element distribution of silica particles.

[0115] It can be seen from Figures 1 to 3 that the surface of pure silica particles is smooth and composed of Si and O elements; after the silica particles are coated and modified with ammonium phytate, the surface of the hybrid particles is covered and wrapped by organic substances. Especially for the hybrid flame retardant prepared with a mass ratio of silica to ammonium phytate of 1:1, the surface organic covering is dense, complete and evenly wrapped on the particle surface. After elemental analysis and testing, the main components of the surface organic substances are P, N, and C elements, which are all the main components of ammonium phytate organic substances. The test results show that ammonium phytate can be evenly and completely coated on the surface of silica.

[0116] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, rather than all embodiments. Other embodiments can also be obtained based on these embodiments without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. Application of ammonium phytate-modified silica as a flame retardant in flame-retardant materials, characterized in that, The ammonium phytate-modified silica flame retardant includes silica and ammonium phytate chemically bonded to the silica; The mass ratio of the ammonium phytate to the silica is 1:1; The flame retardant material is a PBAT-based flame retardant composite material; The raw materials for preparing the PBAT-based flame retardant composite material are: 85 parts of PBAT; 15 parts of ammonium phytate-modified silica flame retardant; The preparation method of the ammonium phytate is: mixing an aqueous solution of an amine compound and an aqueous solution of phytic acid, and carrying out an amidation reaction to obtain ammonium phytate; the amine compound in the aqueous solution of the amine compound is tris(4-aminophenyl)amine.

2. The application according to claim 1, wherein The preparation method of the ammonium phytate-modified silica flame retardant includes the following steps: Mixing the ammonium phytate solution and the silica aqueous dispersion, and carrying out a substitution reaction to obtain the ammonium phytate-modified silica flame retardant; the pH value of the silica aqueous dispersion is 2-4.

3. The application according to claim 2, characterized in that The ammonium phytate solution includes ammonium phytate, ethanol and water.

4. The application according to claim 2 or 3, characterized in that, The concentration of ammonium phytate in the ammonium phytate solution is 3-20 wt%; the volume ratio of ethanol to water in the ammonium phytate solution is 0.5:1-3:

1.

5. The application according to claim 2, wherein The temperature of the substitution reaction is 40-60 °C, and the time is 3-6 h.

6. The application according to claim 1, characterized in that, The preparation method of the PBAT-based flame retardant composite material includes the following steps: After mixing PBAT and the ammonium phytate-modified silica flame retardant, successively carry out melt blending and extrusion molding to obtain the PBAT-based flame retardant composite material.

7. The application according to claim 6, characterized in that, The temperature of the melt blending is 150-200 °C.

Images