Metal-polyphosphazene flame retardant as well as preparation method and application thereof

Abstract

The invention discloses a metal-polyphosphazene flame retardant as well as a preparation method and application thereof. According to the method, aminated polyphosphazene is prepared through reaction of phosphonitrilic chloride trimer and branched polyethyleneimine, and the metal-polyphosphazene flame retardant is prepared by utilizing a polyamino functional group in the polyethyleneimine and adsorbing transition metal ions through coordination. And adding the metal-polyphosphazene flame retardant into the aqueous polyurethane solution, ultrasonically dispersing uniformly, and curing to obtain the flame-retardant aqueous polyurethane. On one hand, the dispersity of polyphosphazene in waterborne polyurethane is improved, and on the other hand, it is ensured that the flame retardant cannot be separated out or volatilized along with time, so that the flame retardant property is improved on the premise that the mechanical property is ensured. In addition, metal, a phosphazene ring and polyethyleneimine in the metal-polyphosphazene flame retardant have an excellent synergistic flame retardant effect, so that the fire safety of the waterborne polyurethane is improved.

Description

Technical Field

[0001] The present invention belongs to the field of flame retardants, and relates to a metal-polyphosphazene flame retardant, a preparation method thereof, and an application thereof. Background Art

[0002] As a new type of flame retardant material, phosphazene contains abundant phosphorus and nitrogen elements, has good thermal stability, and can effectively improve the flame retardant performance of materials. Cyclic crosslinked polyphosphazene is widely used in polymer materials due to its extremely high phosphorus and nitrogen content and simple synthesis method, achieving excellent flame retardant performance at a low addition amount. Polyphosphazene is often compounded with other materials such as black phosphorus (CN 109400956 B), or grafted with other substances such as silane on the surface of polyphosphazene nanoparticles (Composites Communications 2023, 38, 101504) for the synergistic flame retardancy of polymers. Currently, the preparation of polyphosphazene flame retardants mainly uses compounds containing bifunctional groups (hydroxyl and amino groups) as nucleophiles (CN 109181241 B) to prepare cyclic crosslinked polyphosphazene through substitution reaction with hexachlorocyclotriphosphazene. Therefore, polyphosphazene containing multi-functional groups is expected to be endowed with multiple functions to achieve the purpose of synergistic flame retardancy.

[0003] Branched polyethyleneimine (PEI) is an industrial polymer with abundant amino / imine groups and has great potential as a high-level adsorbent. However, due to its good water solubility, single PEI is difficult to be used as a flame retardant. Chinese patent CN 111171324 B discloses a metal-loaded environmentally friendly cyclic crosslinked porous polyphosphazene, a preparation method thereof, and an application thereof. This method involves three steps and uses a hydrothermal reaction. The reaction steps are cumbersome, and the flame retardant object is polypropylene. Summary of the Invention

[0004] The purpose of the present invention is to provide a metal-polyphosphazene flame retardant, a preparation method thereof, and an application thereof. This method uses PEI as a nucleophile, the reaction is simple and easy to operate, combines the structural advantages of polyphosphazene and PEI, obtains a polyphosphazene network with abundant amino groups, and then realizes the adsorption of the polyphosphazene network and metal ions by using the adsorption effect between the free amino groups of PEI and metal ions, greatly simplifying the preparation process of polyphosphazene adsorbing metal ions. And by using the water-soluble property of PEI, the compatibility of the metal-polyphosphazene flame retardant with waterborne polyurethane is improved, which is beneficial to the dispersion of the flame retardant and realizes efficient flame retardancy in waterborne polyurethane.

[0005] The technical solution for achieving the purpose of the present invention is as follows:

[0006] A preparation method of a metal-polyphosphazene flame retardant, comprising the following steps:

[0007] (1) Dissolve hexachlorocyclotriphosphazene (HCCP) and the acid-binding agent triethylamine in acetonitrile by ultrasonic treatment, then add PEI, and react with ultrasonic treatment and stirring to obtain amino-functionalized polyphosphazene;

[0008] (2) Add a transition metal salt to the amino-functionalized polyphosphazene solution, heat up to 60 ± 5 °C, react with ultrasonic stirring, after the reaction, perform suction filtration, wash with absolute ethanol, and dry in vacuum to obtain a metal-polyphosphazene flame retardant.

[0009] Furthermore, in step (1), the concentration of HCCP is 0.02 - 0.06 mol·L -1 .

[0010] Furthermore, in step (1), the weight-average molecular weight of PEI is 500 - 20000, preferably 1800 - 5000.

[0011] Furthermore, in step (1), the molar ratio of HCCP to PEI is 1:(0.5 - 10).

[0012] Furthermore, in step (2), the molar ratio of the transition metal salt to PEI is (1 - 5):1.

[0013] Furthermore, in step (2), the transition metal salt is selected from one or more of nickel salts, cobalt salts, and ferrous salts.

[0014] Furthermore, in step (2), the reaction time is 6 - 8 h.

[0015] Furthermore, in step (2), the number of washing times is more than 3 times, and the vacuum drying temperature is 60 °C.

[0016] The present invention provides a metal-polyphosphazene flame retardant prepared by the above preparation method.

[0017] The present invention also provides the application of the above metal-polyphosphazene flame retardant as a flame retardant for waterborne polyurethane.

[0018] Furthermore, the specific application method is: add the metal-polyphosphazene flame retardant to the waterborne polyurethane solution, disperse it evenly by ultrasonic treatment, and then cure to obtain flame-retardant waterborne polyurethane.

[0019] Furthermore, in the above application, the addition amount of the metal-polyphosphazene flame retardant is 1.0 - 6.0 wt% of the waterborne polyurethane.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] (1) Through the nucleophilic reaction of HCCP and PEI, a polyethyleneimine-phosphazene network with a cyclic cross-linked structure is obtained. Metal ions are introduced by utilizing the coordination effect between the amino groups of PEI in the phosphazene network and the metal ions. The phosphazene ring structure in the metal-polyphosphazene flame retardant acts as the acid source in the intumescent flame retardant. The metal-polyphosphazene obtained by the reaction of PEI as a nucleophile has the function of the gas source in the intumescent flame retardant. Metal ions are introduced onto the surface of the polyphosphazene to obtain the metal-polyphosphazene flame retardant, which improves the smoke suppression and toxicity reduction effects of the metal-polyphosphazene flame retardant. Utilizing the water-soluble property of PEI, the compatibility between the prepared flame retardant and waterborne polyurethane is improved, which is beneficial to the dispersion of the flame retardant and realizes efficient flame retardancy in waterborne polyurethane.

[0022] (2) The present invention realizes the preparation of a composite system of metal ion smoke suppression and toxicity reduction and polyphosphazene high-efficiency flame retardancy. The whole process uses a single reaction solvent system, and the reaction steps are simple and feasible. The flame retardant modified waterborne polyurethane system has excellent flame retardant performance, and the heat release and smoke release behaviors are significantly inhibited. Brief Description of the Drawings

[0023] Figure 1 It is a schematic diagram of the preparation process of the metal-polyphosphazene flame retardant.

[0024] Figure 2 It is the infrared spectrum of Ni-PPZ in Example 1 and Co-PPZ in Example 2.

[0025] Figure 3 It is the XRD spectrum of NiCo-PPZ in Example 3.

[0026] Figure 4 It is the SEM image of FeNi-PPZ in Example 3.

[0027] Figure 5 It is the heat release and smoke release curves of the flame retardant WPU in Examples 1-4 and Comparative Examples 1-3. Detailed Embodiments

[0028] The technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments and drawings. The described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0029] Example 1

[0030] Take 3.48 g of HCCP and 6.07 g of triethylamine and dissolve them in 250 ml of acetonitrile. After the HCCP is completely dissolved, add 20 g of PEI (M w(with a molar mass of 1800), stir ultrasonically for 3 h. Then add 3.0 g of nickel(II) nitrate hexahydrate, raise the temperature to 60 °C, and stir and react ultrasonically for 6 h. After the reaction, perform suction filtration, wash three times with absolute ethanol, and then dry in a vacuum drying oven at 60 °C to obtain 13.1 g of green powder of metal-polyphosphazene, abbreviated as Ni-PPZ.

[0031] Take 1.5 g of Ni-PPZ and an aqueous polyurethane solution (the solid content of the aqueous polyurethane is 30 g), stir ultrasonically for 2 h, then pour it into a polytetrafluoroethylene mold, and dry it in a forced-air drying oven at 40 °C to obtain Ni-PPZ flame-retardant aqueous polyurethane (Ni-PPZ / WPU).

[0032] Example 2

[0033] Take 3.48 g of HCCP and 6.07 g of triethylamine and dissolve them in 250 ml of acetone. After HCCP is completely dissolved, add 20 g of PEI (M w is 5000), stir ultrasonically for 3 h. Then add 3.0 g of cobalt(II) nitrate hexahydrate, raise the temperature to 60 °C, and stir and react ultrasonically for 6 h. After the reaction, perform suction filtration, wash three times with absolute ethanol, and then dry in a vacuum drying oven at 60 °C to obtain 12.7 g of pink powder of metal-polyphosphazene, abbreviated as Co-PPZ.

[0034] Take 1.5 g of Co-PPZ and an aqueous polyurethane solution (the solid content of the aqueous polyurethane is 30 g), stir ultrasonically for 2 h, then pour it into a polytetrafluoroethylene mold, and dry it in a forced-air drying oven at 40 °C to obtain Co-PPZ flame-retardant aqueous polyurethane (Co-PPZ / WPU).

[0035] Example 3

[0036] Take 3.48 g of HCCP and 6.07 g of triethylamine and dissolve them in 250 ml of acetonitrile. After HCCP is completely dissolved, add 20 g of PEI (M w is 5000), stir ultrasonically for 3 h. Then add 3.0 g of cobalt(II) nitrate hexahydrate and 3.0 g of nickel(II) nitrate hexahydrate, raise the temperature to 60 °C, and stir and react ultrasonically for 6 h. After the reaction, perform suction filtration, wash three times with absolute ethanol, and then dry in a vacuum drying oven at 60 °C to obtain 15.2 g of pink powder of metal-polyphosphazene, abbreviated as NiCo-PPZ.

[0037] Take 1.5 g of NiCo-PPZ and an aqueous polyurethane solution (the solid content of the aqueous polyurethane is 30 g), stir ultrasonically for 2 h, then pour it into a polytetrafluoroethylene mold, and dry it in a forced-air drying oven at 40 °C to obtain NiCo-PPZ flame-retardant aqueous polyurethane.

[0038] Example 4

[0039] Dissolve 3.48 g of HCCP and 6.07 g of triethylamine in 250 ml of acetonitrile. After the HCCP is completely dissolved, add 20 g of PEI (M w is 600), and stir ultrasonically for 3 h. Then add 1.26 g of ferrous chloride and 3.0 g of nickel nitrate hexahydrate, heat up to 60 °C, and react with ultrasonic stirring for 6 h. After the reaction is completed, perform suction filtration, wash three times with absolute ethanol, and then dry in a vacuum drying oven at 60 °C to obtain 13.8 g of red powder of metal-polyphosphazene, briefly denoted as FeNi-PPZ.

[0040] Take 1.5 g of FeNi-PPZ and an aqueous polyurethane solution (the solid content of the aqueous polyurethane is 30 g), stir ultrasonically for 2 h, then pour it into a polytetrafluoroethylene mold, and dry it in a blast dryer at 40 °C to obtain FeNi--PPZ flame-retardant aqueous polyurethane.

[0041] Comparative Example 1

[0042] Stir an aqueous polyurethane solution (the solid content of the aqueous polyurethane is 30 g) ultrasonically for 2 h, then pour it into a polytetrafluoroethylene mold, and dry it in a blast dryer at 40 °C to obtain a blank sample of aqueous polyurethane (WPU).

[0043] Comparative Example 2

[0044] Dissolve 3.48 g of HCCP and 6.07 g of triethylamine in 250 ml of acetonitrile. After the HCCP is completely dissolved, add 20 g of PEI (M w is 1800), and stir ultrasonically for 3 h. After the reaction is completed, perform suction filtration, wash three times with absolute ethanol, and then dry in a vacuum drying oven at 60 °C to obtain 8 g of white polyethyleneimine-polyphosphazene (PPZ) powder, briefly denoted as PPZ.

[0045] Take 1.5 g of PPZ and an aqueous polyurethane solution (the solid content of the aqueous polyurethane is 30 g), stir ultrasonically for 2 h, then pour it into a polytetrafluoroethylene mold, and dry it in a blast dryer at 40 °C to obtain PPZ flame-retardant aqueous polyurethane (WPU / PPZ).

[0046] Comparative Example 3

[0047] Dissolve 3.48 g of HCCP and 6.07 g of triethylamine in 250 ml of acetonitrile. After the HCCP is completely dissolved, add 6.2 g of 4,4'-diaminodiphenyl ether (ODA), and stir ultrasonically for 3 h. Then add 3.0 g of cobalt nitrate hexahydrate and 3.0 g of nickel nitrate hexahydrate, heat up to 60 °C, and react with ultrasonic stirring for 6 h. After the reaction is completed, perform suction filtration, wash three times with absolute ethanol, and after the reaction is completed, perform suction filtration, wash three times with absolute ethanol, and then dry in a vacuum drying oven at 60 °C to obtain 7 g of pink powder of metal-polyphosphazene, briefly denoted as NiCo-PZS.

[0048] After taking 1.5 g of NiCo-PZS and an aqueous polyurethane solution (the solid content of the aqueous polyurethane is 30 g) and ultrasonically stirring for 2 h, it was poured into a polytetrafluoroethylene mold and dried in a blast oven at 40 °C to obtain NiCo-PZS flame-retardant aqueous polyurethane (NiCo-PZS / WPU).

[0049] Figure 2 It is the infrared spectrum of Ni-PPZ in Example 1 and Co-PPZ in Example 2. It can be seen that the infrared absorptions of P=N and P-N bonds in the metal-polyphosphazene are at 1209 and 956 cm -1 , and the infrared characteristic absorption of the amino group in the PEI structure in the metal-polyphosphazene is at 3300 - 3400 cm -1 , and the infrared characteristic absorption peak of the M-O bond (M is Ni or Co) in the metal-polyphosphazene is 1385 cm -1 and 500 - 800 cm -1 . These infrared characteristics indicate that the metal-polyphosphazene was successfully prepared, and its composition is a phosphazene ring structure, an amino structure and a metal ion structure.

[0050] Figure 3 It is the XRD spectrum of NiCo-PPZ in Example 3. It can be seen that the crystal diffraction of the metal-polyphosphazene is near 26°, which is an amorphous crystalline state.

[0051] Figure 4 It is the SEM image of FeNi-PPZ in Example 3. It can be seen that the microscopic morphology of the metal-polyphosphazene is solid particles below 10 μm.

[0052] Figure 5 They are the heat release and smoke release curves of the flame-retardant WPU in Examples 1 - 4 and Comparative Examples 1 - 3. The blank sample is Comparative Example 1. Figure 5 The maximum heat release and smoke release rates of a-b Comparative Example 1 are 2307 kW / m 2 , 0.71 m 2 / s. The flame-retardant effect of Example 3 is the best. The maximum heat release rate and smoke release rate are 1124 kW / m 2 , 0.10 m 2 / s, a decrease of 51.2% and 85.7%. After the metal-polyphosphazene flame-retards WPU, the heat release and smoke release of the WPU sample are significantly inhibited, mainly due to the synergistic flame-retardant effect of the phosphorus-nitrogen-rich and metal ions in the metal-polyphosphazene.

Claims

1. A method for preparing a metal-polyphosphazene flame retardant, characterized in that, It includes the following steps: (1) Ultrasonically dissolve HCCP and the acid-binding agent triethylamine in acetonitrile, then add PEI, ultrasonically agitate and react to obtain amino-functionalized polyphosphazene; (2) Add a transition metal salt to the amino-functionalized polyphosphazene solution, heat to 60 ± 5 °C, ultrasonically agitate and react. After the reaction, perform suction filtration, wash with absolute ethanol, and vacuum dry to obtain a metal-polyphosphazene flame retardant.

2. The preparation method according to claim 1, wherein In step (1), the concentration of HCCP is 0.02 - 0.06 mol∙L -1 .

3. The preparation method according to claim 1, wherein In step (1), the weight-average molecular weight of PEI is 500 - 20000.

4. The preparation method according to claim 1, characterized in that, In step (1), the weight-average molecular weight of PEI is 1800 - 5000.

5. The preparation method according to claim 1, characterized in that, In step (1), the molar ratio of HCCP to PEI is 1:(0.5 - 10); in step (2), the molar ratio of the transition metal salt to PEI is (1 - 5):1, and the transition metal salt is selected from one or more of nickel salts, cobalt salts, and ferrous salts.

6. The preparation method according to claim 1, characterized in that, In step (2), the reaction time is 6 - 8 h, the number of washing times is more than 3 times, and the vacuum drying temperature is 60 °C.

7. A metal-polyphosphazene flame retardant prepared by the preparation method according to any one of claims 1 to 6.

8. Application of the metal-polyphosphazene flame retardant according to claim 7 as a flame retardant for waterborne polyurethane.

9. The application according to claim 8, characterized in that, The specific application method is: add the metal-polyphosphazene flame retardant to the waterborne polyurethane solution, ultrasonically disperse it evenly, and then cure to obtain flame-retardant waterborne polyurethane.

10. The application according to claim 9, wherein The addition amount of the metal-polyphosphazene flame retardant is 1.0 - 6.0 wt% of the waterborne polyurethane.

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