Phenylalkali metal silsesquioxane-coated polyoxometalate submicron spheres, composites and applications

Abstract

The present application relates to the field of flame retardant, especially to a kind of phenyl alkali metal silsesquioxane coated polyoxometalate submicron sphere, composite material and application, the present application uses polyoxometalate, phenyl alkali metal silsesquioxane, reaction solvent as raw material, with phenyl alkali metal silsesquioxane as core, using the strong electronegativity of polyoxometalate, surface coating is prepared by strong electrostatic effect submicron sphere.Then the submicron sphere is compounded with EP, and EP / POM(Mo)@POSS(Li) composite material is obtained.The composite material prepared by the present application contains phenyl alkali metal silsesquioxane with smoke suppression carbonization effect, and polyoxometalate with promoting matrix catalytic carbonization, which can greatly reduce the release of heat, smoke and toxic gas of EP composite material in the combustion process, thereby providing protection for the life safety of personnel in fire scene.

Description

Technical Field

[0001] This invention relates to the field of flame retardants, and more particularly to a phenyl alkali metal silsesquioxane-coated polyoxometalate submicron sphere, composite material, and its application. Background Technology

[0002] Epoxy resin is a thermosetting resin with excellent adhesion, mechanical properties, corrosion resistance, and electrical insulation. It is a polymer formed by the reaction of epichlorohydrin with bisphenol A or polyols, containing two or more epoxy groups. During the curing process, epoxy resin undergoes a cross-linking reaction with the hardener to form a three-dimensional network structure, thus exhibiting good thermal stability, chemical stability, and dimensional stability. It has wide applications in electronics, coatings, composite materials, and adhesives. However, with the widespread use of polymer materials in people's lives, the number of casualties from residential fires remains high. Once a fire occurs, the high carbon content of polymer materials becomes one of the biggest contributors to the spread of fire. Therefore, the demand for functionalized epoxy resins is increasing daily, creating an urgent need for epoxy resins with flame-retardant properties.

[0003] Currently, the five most commonly used flame retardants are: halogenated flame retardants, phosphorus-based flame retardants, nitrogen-based flame retardants, inorganic metal flame retardants, and silicon-based flame retardants. Halogenated flame retardants have limited thermal stability and release toxic or even carcinogenic substances during combustion; therefore, many traditional halogenated flame retardants are banned and are undergoing toxicity assessments. While phosphorus-based flame retardants meet the requirements of being halogen-free and environmentally friendly, they still suffer from high volatility, low stability, and poor compatibility, and can produce molten droplets that cause secondary damage during combustion. Nitrogen-based flame retardants have poor thermal stability and decompose during processing; they also have poor water resistance, sedimentation resistance, and migration resistance. After prolonged heating or immersion in hot water, the flame retardant will precipitate on the surface or dissolve in water, thus losing its flame-retardant effect. While inorganic metal flame retardants do not release toxic gases during combustion and possess smoke-suppressing properties, their low flame-retardant efficiency and poor compatibility with polymers significantly reduce the mechanical properties of materials. Therefore, they are generally used as synergistic flame retardants in combination with other flame retardants. Silicon-based flame retardants, with their advantages of low smoke, non-toxicity, easy charring, and anti-dripping properties, have become "environmentally friendly" halogen-free flame retardants.

[0004] Phenyl alkali metal silsesquioxanes belong to the silicon-based flame retardant family. They are incompletely condensed cage-like phenyl silsesquioxanes containing alkali metals. The presence of the metal element endows them with the ability to catalyze carbonization within polymer materials. Furthermore, phenyl alkali metal silsesquioxanes contain seven rigid phenyl groups, typically 1-3 nm in size. When introduced into a polymer matrix, they not only enhance flame retardant properties but also significantly improve mechanical properties. Simultaneously, phenyl alkali metal silsesquioxanes possess a high specific surface area, making them suitable as a carrier.

[0005] Polyoxometalates, such as phosphomolybdic acid and phosphotungstic acid, are anionic metal-oxygen clusters with high electronegativity, thus they can be coated with phenylalkali metal silsesquioxanes under strong electrostatic interaction. Polyoxometalates contain several flame-retardant elements, including phosphorus, molybdenum, and tungsten. Phosphorus acts as an acid source in the flame-retardant system, while molybdenum and tungsten catalyze the polymer and phenylalkali metal silsesquioxanes, rapidly catalyzing char formation during combustion. Simultaneously, phenylalkali metal silsesquioxanes are excellent smoke suppressants and charring agents; the combined action of polyoxometalates and phenylalkali metal silsesquioxanes enhances their smoke suppression and charring effects.

[0006] Therefore, by using intermolecular forces to combine polyoxometalates with phenyl alkali metal silsesquioxanes, the silicon-phosphorus flame retardants can be combined to achieve a synergistic effect, while avoiding the individual defects of phosphorus-based and silicon-based flame retardants. Summary of the Invention

[0007] To address the problem of low flame retardant performance in current flame retardants, this invention provides a phenyl alkali metal silsesquioxane-coated polyoxometalate submicron sphere, a composite material, and its applications.

[0008] This invention is achieved through the following technical solution: a method for preparing phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres, comprising the following steps:

[0009] A mixture of phenyl alkali metal silsesquioxane, polyoxometalate, and organic solvent was used to coat the polyoxometalate submicron spheres POM(Mo)@POSS(Li) by intermolecular forces.

[0010] This invention uses polyoxometalates, phenyl alkali metal silsesquioxane, and reaction solvent as raw materials, with phenyl alkali metal silsesquioxane as the core. It utilizes the strong electronegativity of polyoxometalates to prepare submicron spheres through surface coating via strong electrostatic interaction.

[0011] As a further improvement to the preparation method of the present invention, the phenyl alkali metal silsesquioxane is an incompletely condensed cage-like phenyl silsesquioxane containing sodium alkali metal or an incompletely condensed cage-like phenyl silsesquioxane containing lithium alkali metal.

[0012] As a further improvement to the preparation method of the present invention, the polyoxometalate is phosphomolybdic acid or phosphotungstic acid.

[0013] As a further improvement to the preparation method of the present invention, the organic solvent is ethanol, methanol, acetone, tetrahydrofuran, dichloromethane, chloroform or dimethyl sulfoxide.

[0014] As a further improvement to the preparation method of the present invention, the mass ratio of the phenyl alkali metal silsesquioxane to the polyoxometalate is 10~23:7~15.

[0015] As a further improvement to the preparation method of the present invention, the reaction temperature of the phenyl alkali metal silsesquioxane, polyoxometalate and organic solvent is 50~80 ℃ and the reaction time is 18~25 h.

[0016] Secondly, the present invention provides a method for preparing EP / POM(Mo)@POSS(Li) composite material, wherein the phenyl alkali metal silicon silsesquioxane-coated polyoxometalate submicron spheres POM(Mo)@POSS(Li) are prepared by the method described above.

[0017] The process includes the following steps: heating the epoxy resin to 120~150 ℃, adding POM(Mo)@POSS(Li) and stirring until homogeneous, then adding the curing agent 4,4'-diaminodiphenyl sulfone and curing to obtain the EP / POM(Mo)@POSS(Li) composite material.

[0018] As a further improvement to the technical solution of the composite material preparation method of the present invention, the curing temperature is 150~200℃ and the curing time is 2~5h.

[0019] Thirdly, the present invention further provides the application of the phenyl alkali metal silicon silsesquioxane-coated polyoxometalate submicron spheres POM(Mo)@POSS(Li) prepared by the method of preparing the phenyl alkali metal silicon silsesquioxane-coated polyoxometalate submicron spheres as a flame retardant.

[0020] Fourthly, the present invention further provides a method for preparing EP / POM(Mo)@POSS(Li) composite material and its application as a flame retardant material.

[0021] The phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres, composite materials, and applications provided by this invention have the following advantages compared to existing technologies:

[0022] The preparation process of this invention is simple, reproducible, and uses environmentally friendly and sustainable raw materials. The organic solvent is reusable. The phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres POM(Mo)@POSS(Li) have a smooth spherical morphology, preventing agglomeration. The EP / POM(Mo)@POSS(Li) composite material prepared by this invention contains phenyl alkali metal silsesquioxane with smoke-suppressing and char-forming properties, as well as polyoxometalates that promote matrix catalytic char formation. This significantly reduces the release of heat, smoke, and toxic gases during the combustion process of the EP composite material, thereby ensuring the safety of personnel in fire situations. Attached Figure Description

[0023] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the microstructure of the phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres (POM(Mo)@POSS(Li)) in Example 1.

[0026] Figure 2 The image shows a transmission electron microscope (TEM) image of the phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spherical flame retardant (POM(Mo)@POSS(Li)) in Example 1, along with elemental mapping diagrams of C, O, Si, P, and Mo.

[0027] Figure 3 The raw materials in Example 1 are Li-Ph-POSS and phosphomolybdic acid (H3PMo). 12 O 40 FT-IR spectra of the prepared submicron spheres (POM(Mo)@POSS(Li)).

[0028] Figure 4 The raw materials in Example 1 are Li-Ph-POSS and phosphomolybdic acid (H3PMo). 12 O 40 XRD patterns of the prepared submicron spheres (POM(Mo)@POSS(Li)).

[0029] Figure 5 The raw materials in Example 1 are Li-Ph-POSS and phosphomolybdic acid (H3PMo). 12 O40 TG spectra of the prepared submicron spheres (POM(Mo)@POSS(Li)) and (under nitrogen atmosphere).

[0030] Figure 6 The graph shows the heat release rate curves of EP / POM(Mo)@POSS(Li) composite material and EP with 2 wt% flame retardant added in Example 1.

[0031] Figure 7 The graph shows the smoke generation rate curves of EP / POM(Mo)@POSS(Li) composite material and EP with 2 wt% flame retardant added in Example 1.

[0032] Figure 8 The graph shows the CO generation rate of EP / POM(Mo)@POSS(Li) composite material and EP with 2 wt% flame retardant added in Example 1. Detailed Implementation

[0033] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0034] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.

[0035] This invention provides a specific embodiment of a method for preparing phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres, comprising the following steps:

[0036] A mixture of phenyl alkali metal silsesquioxane, polyoxometalate, and organic solvent was used to coat the polyoxometalate submicron spheres POM(Mo)@POSS(Li) by intermolecular forces.

[0037] The phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres POM(Mo)@POSS(Li) prepared by the above method are spherical materials with a submicron scale.

[0038] In one embodiment of the present invention, the phenyl alkali metal silsesquioxane is an incompletely condensed cage-like phenyl silsesquioxane containing sodium alkali metal or an incompletely condensed cage-like phenyl silsesquioxane containing lithium alkali metal. Preferably, the present invention uses a laboratory-prepared alkali metal silsesquioxane (Li-Ph-POSS), which belongs to the category of incompletely condensed cage-like phenyl silsesquioxanes containing lithium alkali metal.

[0039] In another embodiment of the present invention, the polyoxometalate is phosphomolybdic acid or phosphotungstic acid.

[0040] In one embodiment of the present invention, the organic solvent is ethanol, methanol, acetone, tetrahydrofuran, dichloromethane, chloroform, or dimethyl sulfoxide. Methanol is preferred.

[0041] In one embodiment of the present invention, the mass ratio of the phenyl alkali metal silsesquioxane to the polyoxometalate is 10~23:7~15.

[0042] In one embodiment of the present invention, the phenyl alkali metal silsesquioxane, polyoxometalate and organic solvent are mixed and reacted at a temperature of 50-80 °C for a time of 18-25 h.

[0043] In this invention, when the phenyl alkali metal silsesquioxane is mixed with polyoxometalates and organic solvents, the phenyl alkali metal silsesquioxane is first mixed with the organic solvent, and then ultrasonically dispersed and mixed evenly. After preheating to the reaction temperature, the polyoxometalates are dissolved in the mixture, reacted at a constant temperature, filtered, and the filtrate is rotary distilled to obtain a light green viscous substance. The light green viscous substance is then dried to obtain a dark green solid, which is a phenyl alkali metal silsesquioxane-coated polyoxometalate submicron sphere.

[0044] The present invention further provides a method for preparing EP / POM(Mo)@POSS(Li) composite material, wherein the phenyl alkali metal silicon silsesquioxane-coated polyoxometalate submicron spheres POM(Mo)@POSS(Li) are prepared by the method described above for preparing phenyl alkali metal silicon silsesquioxane-coated polyoxometalate submicron spheres.

[0045] The process includes the following steps: heating the epoxy resin to 120~150 ℃, adding POM(Mo)@POSS(Li) and stirring until homogeneous, then adding the curing agent 4,4'-diaminodiphenyl sulfone and curing to obtain the EP / POM(Mo)@POSS(Li) composite material.

[0046] Preferably, the mass ratio of the epoxy resin, POM(Mo)@POSS(Li), and curing agent 4,4'-diaminodiphenyl sulfone is 100~200:1~11:30~60. Preferably, the epoxy resin matrix is ​​DGEBA.

[0047] Furthermore, the curing temperature is 150~200 ℃, and the curing time is 2~5 hours. In this embodiment, the curing is carried out in a forced-air oven, but other equipment with heating functions can also be used.

[0048] The present invention also provides the application of the prepared phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres POM(Mo)@POSS(Li) as a flame retardant.

[0049] The present invention further provides a method for preparing EP / POM(Mo)@POSS(Li) composite material and its application as a flame retardant material.

[0050] The specific embodiments of the present invention will be described in detail below. Example 1

[0051] A method for preparing an EP / POM(Mo)@POSS(Li) composite material includes the following steps:

[0052] Measure 200 mL of anhydrous methanol as the reaction solvent, then weigh 11.2 g of Li-Ph-POSS and add it to a three-necked round-bottom flask. Heat in an oil bath to 65 °C. Then weigh 7.3 g of phosphomolybdic acid (H3PMo). 12 O 40 Dissolve 100 mL of anhydrous methanol and slowly add it dropwise into the reaction vessel over 30 min using a constant pressure dropping funnel. The reaction time is 22 h. After sufficient reaction, a light green mixture is obtained. Filter the light green mixture and collect the filtrate. Distill the filtrate under reduced pressure to obtain a light green viscous substance. Finally, dry the viscous substance in a 70 ℃ forced-air drying oven for 25 h. Weigh the product and label it in a bag. The mass of the obtained product (phenyl alkali metal silsesquioxane coated polyoxometalate submicron spheres, POM(Mo)@POSS(Li)) is 8.8 g, with a yield of 48%.

[0053] 6.9 g of the prepared flame retardant POM(Mo)@POSS(Li) was added to 260 g of epoxy resin (EP) after mechanical stirring in an oil bath at 140 ℃ for 30 min. The mixture was stirred in the oil bath at 140 ℃ for 1 h. Then, 78 g of curing agent 4,4'-diaminodiphenyl sulfone (DDS) was added and stirred for another 3 min. The mixture was then poured into a polytetrafluoroethylene (PTFE) mold and cured in a forced-air oven at 180 ℃ for 4 h to obtain an EP / POM(Mo)@POSS(Li) composite material (i.e., EP-2) with excellent flame retardant properties and an addition amount of 2 wt% (i.e., the ratio of flame retardant to the mass of the composite material).

[0054] Figure 2 Transmission electron microscopy (TEM) images and elemental mapping diagrams of C, O, Si, P, and Mo are shown for the prepared submicron spheres (POM(Mo)@POSS(Li)). TEM images and elemental mapping diagrams of C, O, Si, P, and Mo are also shown for the phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spherical flame retardant (POM(Mo)@POSS(Li)). The morphology of POM(Mo)@POSS(Li) is approximately submicron spheres with a diameter of 500–600 nm. Elemental mapping reveals that the intermediate interlayer of POM(Mo)@POSS(Li) is H3PMo. 12 O 40 The inner and outer layers are Li-Ph-POSS. The inner Li-Ph-POSS is due to its aggregation properties, while the outer Li-Ph-POSS is due to the H3PMo in the middle. 12 O 40 It possesses negative charge and acts as a binder between the internal and external Li-Ph-POSS. This strongly demonstrates the successful preparation of phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spherical flame retardants.

[0055] Figure 3 The raw materials are Li-Ph-POSS and phosphomolybdic acid (H3PMo). 12 O 40 FT-IR spectra of the prepared submicron spheres (POM(Mo)@POSS(Li)) and the prepared submicron spheres (POM(Mo)@POSS(Li)). 3000~3700 cm⁻¹ -1 The peak represents the stretching vibration of -OH, 1130–1052 cm⁻¹. -1 The range includes stretching vibration peaks corresponding to Si-O-Si, Si-O, and PO, with a peak at 998 cm⁻¹. -1 This corresponds to the characteristic absorption peak of Si-O-Li, at 915 cm⁻¹. -1 The vibrational absorption peak for Mo=O is 883 cm⁻¹. -1 These are characteristic vibrational absorption peaks of Mo-O-Mo.

[0056] Figure 4 The raw materials are Li-Ph-POSS and phosphomolybdic acid (H3PMo). 12 O 40 The XRD patterns of the prepared submicron spheres (POM(Mo)@POSS(Li)) are shown in the figure. As can be seen from the figure, the diffraction peaks in the POM(Mo)@POSS(Li) sample appear at 8.60°, 9.48°, 11.55°, 12.83°, 18.08°, 23.79°, 26.05°, 28.64°, and 30.54°. Corresponding to the JCPDS card, it can be seen that POM(Mo)@POSS(Li) contains no other elements besides P, Mo, O, Si, C, and Li.

[0057] Figure 5 The raw materials are Li-Ph-POSS and phosphomolybdic acid (H3PMo). 12 O 40 TG spectra of the prepared submicron spherical flame retardant (POM(Mo)@POSS(Li)) (nitrogen atmosphere, heating rate 10 ºC / min), the TG images show the T values ​​of POM(Mo)@POSS(Li). 95% The temperature is 123 °C, and the carbon residue at 800 °C is 69.5 wt%. It has strong high-temperature resistance and therefore high thermal stability.

[0058] Figure 6 The graphs show the heat release rate curves of pure epoxy resin (EP) and the EP / POM(Mo)@POSS(Li) composite material (EP-2) with an addition of 2 wt%. The maximum heat release rate of pure epoxy resin is 1065 KW / m. 2 The maximum heat release rate of the EP / POM(Mo)@POSS(Li) composite material is 420 KW / m. 2 This indicates that the addition of nano flame retardants can effectively reduce the heat release rate of epoxy resin materials and enhance their flame retardant properties.

[0059] Figure 7 The graphs show the smoke generation rate curves for pure epoxy resin and EP / POM(Mo)@POSS(Li) composite material with an addition of 2 wt%. The maximum smoke generation rate for pure epoxy resin is 0.312 m. 2 The maximum smoke generation rate of the EP / POM(Mo)@POSS(Li) composite material is 0.0973 m / s. 2 / s. This indicates that the addition of nano flame retardants can effectively reduce the smoke generation rate of epoxy resin materials and enhance their flame retardant properties.

[0060] Figure 8The figures show the CO generation rate curves for pure epoxy resin and the EP / POM(Mo)@POSS(Li) composite material with an addition of 2 wt%. The maximum CO generation rate for pure epoxy resin is 0.038 g / s, while that for the EP / POM(Mo)@POSS(Li) composite material is 0.0180 g / s. This indicates that the addition of nano-flame retardants can effectively reduce the CO generation rate of epoxy resin materials and enhance their flame retardant properties.

[0061] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the present invention. Although detailed descriptions have been provided with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments, and they should all be covered within the protection scope of the claims.

Claims

1. A method for preparing a composite material of epoxy resin / phenyl alkali metal silsesquioxane coated polyoxometalate submicron spheres, characterized in that, Includes the following steps: Epoxy resin is heated to 120~150℃, phenyl alkali metal silsesquioxane-coated polyoxoate submicron spheres are added and stirred evenly, and then 4,4'-diaminodiphenyl sulfone is added as curing agent and cured to obtain a composite material of epoxy resin / phenyl alkali metal silsesquioxane-coated polyoxoate submicron spheres. The preparation method of the phenyl alkali metal silsesquioxane-coated polyoxoate submicron spheres includes the following steps: mixing phenyl alkali metal silsesquioxane, polyoxoate and organic solvent, and coating by intermolecular forces to obtain phenyl alkali metal silsesquioxane-coated polyoxoate submicron spheres; wherein the polyoxoate is phosphomolybdic acid or phosphotungstic acid.

2. The method for preparing a composite material of epoxy resin / phenyl alkali metal silsesquioxane coated with polyoxometalate submicron spheres according to claim 1, characterized in that, The phenyl alkali metal silsesquioxane is an incompletely condensed cage-like phenyl silsesquioxane containing sodium alkali metal or an incompletely condensed cage-like phenyl silsesquioxane containing lithium alkali metal.

3. The method for preparing a composite material of epoxy resin / phenyl alkali metal silsesquioxane coated with polyoxometalate submicron spheres according to claim 1, characterized in that, The organic solvent is ethanol, methanol, acetone, tetrahydrofuran, dichloromethane, chloroform, or dimethyl sulfoxide.

4. The method for preparing a composite material of epoxy resin / phenyl alkali metal silsesquioxane coated polyoxometalate submicron spheres according to claim 1, characterized in that, The mass ratio of the phenyl alkali metal silsesquioxane to the polyoxometalate is 10~23:7~15.

5. The method for preparing a composite material of epoxy resin / phenyl alkali metal silsesquioxane coated with polyoxometalate submicron spheres according to claim 1, characterized in that, The reaction of the phenyl alkali metal silsesquioxane, polyoxometalate and organic solvent is carried out at a temperature of 50-80°C and a reaction time of 18-25 h.

6. The method for preparing a composite material of epoxy resin / phenyl alkali metal silsesquioxane coated with polyoxometalate submicron spheres according to claim 1, characterized in that, The curing temperature is 150~200℃, and the curing time is 2~5h.

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