Phenyl alkali metal silsesquioxane coated polyoxometallate submicron sphere, composite material and application

Abstract

The invention relates to the field of flame retardants, in particular to a phenyl alkali metal silsesquioxane coated polyoxometallate submicron sphere, a phenyl alkali metal silsesquioxane coated polyoxometallate submicron sphere composite material and application. Polyoxometallate, phenyl alkali metal silsesquioxane and a reaction solvent are used as raw materials, phenyl alkali metal silsesquioxane is used as a core, high electronegativity of the polyoxometallate is utilized, and the polyoxometallate submicron sphere composite material is prepared. And carrying out surface coating under the action of strong static electricity to prepare the submicron sphere. And then compounding the submicrospheres with EP to obtain the EP / POM (Mo) (at) POSS (Li) composite material. The composite material prepared by the invention contains phenyl alkali metal silsesquioxane with smoke suppression and char formation effects and polyoxometallate capable of promoting catalytic char formation of a matrix, and the release of heat, smoke and toxic gas in the combustion process of the EP composite material can be greatly reduced, so that a guarantee is provided for the life safety of personnel in a fire scene.

Description

Technical Field

[0001] The invention relates to the field of flame retardants, and in particular to phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres, composite materials and applications. Background Art

[0002] Epoxy resin is a thermosetting resin with excellent adhesion, mechanical properties, corrosion resistance and electrical insulation. It is a polymer generated by the reaction of epichlorohydrin with bisphenol A or polyols, containing more than two epoxy groups. During the curing process, epoxy resin will undergo a cross-linking reaction with the hardener to form a three-dimensional network structure, so it has good thermal stability, chemical stability and dimensional stability. It is widely used in electronic appliances, coatings, composite materials, adhesives and other fields. However, with the widespread use of polymer materials in people's lives, the number of casualties in residential fires remains high. Once a fire occurs, the high carbon content of polymer materials will become one of the biggest accomplices in the spread of fire. Therefore, the demand for functionalized epoxy resins is increasing day by day, so there is an urgent need for epoxy resins with flame retardant properties.

[0003] There are five types of flame retardants commonly used today: halogen flame retardants, phosphorus flame retardants, nitrogen flame retardants, inorganic metal flame retardants, and silicon flame retardants. Halogen flame retardants have limited thermal stability and release toxic or even carcinogenic substances during combustion. Therefore, traditional halogen flame retardants are mostly banned, and more are undergoing toxicity assessments. Although phosphorus flame retardants meet the requirements of halogen-free and green environmental protection, they still have problems such as high volatility, low stability, and poor compatibility, and molten droplets that cause secondary damage will be produced during combustion. Nitrogen flame retardants have poor thermal stability and will decompose during processing; they have poor water resistance, precipitation resistance, and migration resistance. After long-term heating or long-term hot water immersion, the flame retardant will precipitate to the surface or dissolve in water, thereby losing its flame retardant effect. Although inorganic metal flame retardants do not release toxic gases when burned and have smoke suppression properties, they have low flame retardant effect rates and low compatibility with polymers, which will significantly reduce the mechanical properties of the material. Therefore, they are generally used as synergistic flame retardants in combination with other flame retardants. Silicon-based flame retardants have become "environmentally friendly" halogen-free flame retardants due to their low smoke, non-toxicity, easy carbonization and anti-drip properties.

[0004] Phenyl alkali silsesquioxane belongs to silicon-based flame retardants and is an incompletely polycondensed cage-shaped phenyl silsesquioxane containing alkali metals. Due to the presence of metal elements, it is endowed with the ability to catalyze carbonization in polymer materials. Phenyl alkali silsesquioxane contains seven rigid phenyl groups, and the size is usually 1-3 nm. When introduced into the polymer matrix, it can not only improve the flame retardant properties, but also significantly improve the mechanical properties. At the same time, phenyl alkali silsesquioxane has a high specific surface area and can be used as a carrier.

[0005] Polyoxometalates, such as phosphomolybdic acid and phosphotungstic acid, are anionic metal-oxygen clusters with high electronegativity, so they can be coated with phenyl alkali metal silsesquioxane under strong electrostatic action. Polyoxometalates contain several flame retardant elements, such as phosphorus, molybdenum, and tungsten. Phosphorus exists as an acid source in the flame retardant system. Molybdenum and tungsten have a catalytic effect on polymers and phenyl alkali metal silsesquioxane, and can quickly catalyze carbonization during the combustion process. At the same time, phenyl alkali metal silsesquioxane is an excellent smoke suppressant and carbon-forming agent. The simultaneous action of polyoxometalates and phenyl alkali metal silsesquioxane can exert a better smoke suppression and carbonization effect.

[0006] Therefore, the intermolecular force is used to combine the polyoxometalate with the phenyl alkali metal silsesquioxane, and the silicon-phosphorus flame retardant is used in combination to achieve a synergistic effect, while avoiding the respective defects of the phosphorus-based and silicon-based flame retardants. Summary of the invention

[0007] In order to solve the problem of low flame retardant effect of current flame retardants, the present invention provides a phenyl alkali metal silsesquioxane-coated polyoxometalate submicron sphere, a composite material and an application thereof.

[0008] The present invention is achieved through the following technical scheme: a method for preparing submicron spheres of polyoxometalate coated with phenyl alkali metal silsesquioxane, comprising the following steps: Phenyl alkali metal silsesquioxane, polyoxometalate and organic solvent are mixed and coated by intermolecular forces to obtain phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres POM(Mo)@POSS(Li).

[0009] The invention uses polyoxometalate, phenyl alkali metal silsesquioxane and reaction solvent as raw materials, uses phenyl alkali metal silsesquioxane as the core, utilizes the strong electronegativity of polyoxometalate, and performs surface coating through strong electrostatic action to prepare submicron spheres.

[0010] As a further improvement of the technical solution of the preparation method of the present invention, the phenyl alkali metal silsesquioxane is an incompletely polycondensed cage-shaped phenyl silsesquioxane containing alkali metal sodium or an incompletely polycondensed cage-shaped phenyl silsesquioxane containing alkali metal lithium.

[0011] As a further improvement of the technical solution of the preparation method of the present invention, the polyoxometalate is phosphomolybdic acid or phosphotungstic acid.

[0012] As a further improvement of the technical solution of the preparation method of the present invention, the organic solvent is ethanol, methanol, acetone, tetrahydrofuran, dichloromethane, chloroform or dimethyl sulfoxide.

[0013] As a further improvement of the technical solution of the preparation method of the present invention, the mass ratio of the phenyl alkali metal silsesquioxane to the polyoxometalate is 10-23:7-15.

[0014] As a further improvement of the technical solution of the preparation method of the present invention, the mixed reaction temperature of the phenyl alkali metal silsesquioxane, polyoxometalate and organic solvent is 50-80° C., and the reaction time is 18-25 hours.

[0015] In a second aspect, the present invention provides a method for preparing an EP / POM(Mo)@POSS(Li) composite material, wherein the phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres POM(Mo)@POSS(Li) are prepared by the method for preparing phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres; The method comprises the following steps: heating the epoxy resin to 120-150°C, adding POM(Mo)@POSS(Li) and stirring evenly, adding a curing agent 4,4'-diaminodiphenyl sulfone, and curing to obtain an EP / POM(Mo)@POSS(Li) composite material.

[0016] As a further improvement of the technical solution of the composite material preparation method of the present invention, the curing temperature is 150-200° C. and the curing time is 2-5 hours.

[0017] In a third aspect, the present invention further provides the use of phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres POM(Mo)@POSS(Li) prepared by the preparation method of the phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres as flame retardants.

[0018] In a fourth aspect, the present invention further provides a method for preparing an EP / POM(Mo)@POSS(Li) composite material and application of the prepared EP / POM(Mo)@POSS(Li) composite material as a flame retardant material.

[0019] The phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres, composite materials and applications provided by the present invention have the following advantages compared with the prior art: The preparation process of the present invention is simple, has good repeatability, uses green, environmentally friendly and sustainable raw materials, and the organic solvent can be used repeatedly. The morphology of the phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres POM(Mo)@POSS(Li) is a relatively smooth spherical shape, which avoids agglomeration. The EP / POM(Mo)@POSS(Li) composite material prepared by the present invention comprises phenyl alkali metal silsesquioxane with a smoke-suppressing carbonization effect, and a polyoxometalate with a matrix-catalyzed carbonization-promoting effect, which can greatly reduce the release of heat, smoke and toxic gases in the EP composite material during combustion, thereby providing protection for the life safety of personnel in the fire scene. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 Schematic diagram of the microscopic morphology of phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres (POM(Mo)@POSS(Li)) in Example 1.

[0023] Figure 2 The transmission electron microscope image of the phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spherical flame retardant (POM(Mo)@POSS(Li)) in Example 1 and the element mapping of C, O, Si, P and Mo.

[0024] Figure 3 The raw materials Li-Ph-POSS and phosphomolybdic acid (H3PMo 12 O 40 ) and FT-IR spectra of the prepared submicron spheres (POM(Mo)@POSS(Li)).

[0025] Figure 4 The raw materials Li-Ph-POSS and phosphomolybdic acid (H3PMo 12 O 40 ) and XRD spectra of the prepared submicron spheres (POM(Mo)@POSS(Li)).

[0026] Figure 5 The raw materials Li-Ph-POSS and phosphomolybdic acid (H3PMo 12 O40 ) and TG spectra of the prepared submicron spheres (POM(Mo)@POSS(Li)) (nitrogen atmosphere).

[0027] Figure 6 This is a heat release rate curve of the EP / POM(Mo)@POSS(Li) composite material and EP with 2 wt% flame retardant added in Example 1.

[0028] Figure 7 This is a curve diagram of the smoke generation rate of the EP / POM(Mo)@POSS(Li) composite material and EP with 2 wt% flame retardant added in Example 1.

[0029] Figure 8 This is a curve diagram of the CO generation rate of the EP / POM(Mo)@POSS(Li) composite material and EP with 2 wt% flame retardant added in Example 1. DETAILED DESCRIPTION

[0030] In order to more clearly understand the above-mentioned objectives, features and advantages of the present invention, the scheme of the present invention will be further described below. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0031] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present invention, rather than all of the embodiments.

[0032] The present invention provides a specific embodiment of a method for preparing phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres, comprising the following steps: Phenyl alkali metal silsesquioxane, polyoxometalate and organic solvent are mixed and coated by intermolecular forces to obtain phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres POM(Mo)@POSS(Li).

[0033] 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.

[0034] In one embodiment provided by the present invention, the phenyl alkali metal silsesquioxane is an incomplete polycondensation cage-shaped phenyl silsesquioxane containing alkali metal sodium or an incomplete polycondensation cage-shaped phenyl silsesquioxane containing alkali metal lithium. Preferably, the present invention adopts a laboratory-made alkali metal silsesquioxane (Li-Ph-POSS), which belongs to an incomplete polycondensation cage-shaped phenyl silsesquioxane containing alkali metal lithium.

[0035] In another embodiment provided by the present invention, the polyoxometalate is phosphomolybdic acid or phosphotungstic acid.

[0036] In one embodiment provided by the present invention, the organic solvent is ethanol, methanol, acetone, tetrahydrofuran, dichloromethane, chloroform or dimethyl sulfoxide, preferably methanol.

[0037] In one embodiment provided by the present invention, the mass ratio of the phenyl alkali metal silsesquioxane to the polyoxometalate is 10-23:7-15.

[0038] In one embodiment provided by the present invention, the mixed reaction temperature of the phenyl alkali metal silsesquioxane, the polyoxometalate and the organic solvent is 50-80° C., and the reaction time is 18-25 hours.

[0039] In the present invention, when the phenyl alkali metal silsesquioxane is mixed with a polyoxometalate and an organic solvent, the phenyl alkali metal silsesquioxane and the organic solvent are first mixed, and after being uniformly mixed by ultrasonic dispersion, the mixture is heated to the reaction temperature in advance, and the polyoxometalate is dissolved in the mixed solution, 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 dried to obtain a dark green solid, which is a submicron sphere of polyoxometalate coated with phenyl alkali metal silsesquioxane.

[0040] The present invention further provides a method for preparing an EP / POM(Mo)@POSS(Li) composite material, wherein the phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres POM(Mo)@POSS(Li) are prepared by the method for preparing the phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres as described above; The method comprises the following steps: heating the epoxy resin to 120-150°C, adding POM(Mo)@POSS(Li) and stirring evenly, adding a curing agent 4,4'-diaminodiphenyl sulfone, and curing to obtain an EP / POM(Mo)@POSS(Li) composite material.

[0041] 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.

[0042] Furthermore, the curing temperature is 150-200° C., and the curing time is 2-5 hours. The curing in this embodiment is carried out in a blast oven, and of course other equipment with heating function can also be used.

[0043] The present invention also provides the use of phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres POM(Mo)@POSS(Li) prepared by the preparation method of the phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres as flame retardants.

[0044] The present invention further provides a method for preparing the EP / POM(Mo)@POSS(Li) composite material and application of the prepared EP / POM(Mo)@POSS(Li) composite material as a flame retardant material.

[0045] The specific embodiments of the present invention are described in detail below. Example 1

[0046] A method for preparing an EP / POM(Mo)@POSS(Li) composite material comprises the following steps: 200 mL of anhydrous methanol was taken as the reaction solvent, and then 11.2 g of Li-Ph-POSS was weighed and added into a three-necked round-bottom flask. The oil bath temperature was heated to 65 °C. Then 7.3 g of phosphomolybdic acid (H3PMo 12 O 40 ) was dissolved in 100 mL of anhydrous methanol, and then slowly added dropwise to the reaction vessel within 30 min through a constant pressure dropping funnel. The reaction time was 22 h. After sufficient reaction, a light green mixed liquid was obtained. The obtained light green mixed liquid was filtered and the filtrate was taken. The obtained filtrate was subjected to reduced pressure distillation to obtain a light green viscous substance. Finally, the viscous substance was dried in a 70 ℃ forced air drying oven for 25 h. Finally, the mass was weighed and the bag was marked. The mass of the obtained product (phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres, POM(Mo)@POSS(Li)) was 8.8 g, and the yield was 48%.

[0047] 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 °C for 30 min, and the mixture was continued to be stirred in an oil bath at 140 °C for 1 h. Subsequently, 78 g of curing agent 4,4'-diaminodiphenyl sulfone (DDS) was added and stirred for 3 min. The mixture was poured into a polytetrafluoroethylene (PTFE) mold and cured in a 180 °C forced air oven 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 the mass of the flame retardant to the mass of the composite material).

[0048] Figure 2Transmission electron microscopy (TEM) images of the prepared submicron spheres (POM(Mo)@POSS(Li)) and elemental mapping of C, O, Si, P and Mo. Transmission electron microscopy (TEM) images of phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spherical flame retardant (POM(Mo)@POSS(Li)) and elemental mapping of C, O, Si, P and Mo. The morphology of POM(Mo)@POSS(Li) is roughly submicron spheres with a diameter of 500~600 nm. From elemental mapping, it can be seen that the interlayer of POM(Mo)@POSS(Li) is H3PMo. 12 O 40 The inner and outer skin are Li-Ph-POSS. The inner Li-Ph-POSS is due to its agglomeration characteristics, and the outer Li-Ph-POSS is due to the H3PMo 12 O 40 With negative charge, it acts as a binder between the internal and external Li-Ph-POSS. This strongly proves that the phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spherical flame retardant has been successfully prepared.

[0049] Figure 3 The raw materials are Li-Ph-POSS, phosphomolybdic acid (H3PMo 12 O 40 ) and FT-IR spectra of prepared submicron spheres (POM(Mo)@POSS(Li)). 3000~3700 cm -1 is the stretching vibration peak of -OH, 1130~1052 cm -1 The range includes the stretching vibration peaks of Si-O-Si, Si-O and PO, at 998 cm -1 The corresponding absorption peak is the characteristic absorption peak of Si-O-Li, 915 cm -1 is the vibration absorption peak of Mo=O, 883 cm -1 It is the characteristic vibration absorption peak of Mo-O-Mo.

[0050] Figure 4 The raw materials are Li-Ph-POSS, phosphomolybdic acid (H3PMo 12 O 40 ) and the XRD spectra of the prepared submicron spheres (POM(Mo)@POSS(Li)). It can be seen from the figure that 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°. The corresponding JCPDS cards show that there are no other elements in POM(Mo)@POSS(Li) except P, Mo, O, Si, C, and Li.

[0051] Figure 5 The raw materials are Li-Ph-POSS, phosphomolybdic acid (H3PMo 12 O 40 TG spectra of the prepared submicron spherical flame retardant (POM(Mo)@POSS(Li)) (nitrogen atmosphere, heating rate of 10 ºC / min). The TG image shows that the T 95% The temperature of the sintered carbon is 123 ℃, and the residual carbon content at 800 ℃ is 69.5 wt%. It has strong high temperature resistance and therefore has high thermal stability.

[0052] Figure 6 The heat release rate curves of pure epoxy resin (EP) and EP / POM(Mo)@POSS(Li) composite material (EP-2) with an addition amount of 2 wt%. The maximum heat release rate of pure epoxy resin is 1065 KW / m 2 The maximum heat release rate of EP / POM(Mo)@POSS(Li) composite material is 420 KW / m 2 . It shows that the addition of nano flame retardant can effectively reduce the heat release rate of epoxy resin materials and enhance their flame retardant properties.

[0053] Figure 7 The smoke generation rate curves of pure epoxy resin and EP / POM(Mo)@POSS(Li) composite material with 2 wt% addition are shown in Figure 2. The maximum smoke generation rate of pure epoxy resin is 0.312 m 2 / s, and the maximum smoke generation rate of the EP / POM(Mo)@POSS(Li) composite material is 0.0973 m 2 / s. This shows that the addition of nano flame retardant can effectively reduce the smoke generation rate of epoxy resin materials and enhance their flame retardant properties.

[0054] Figure 8 The following is the CO generation rate curve of pure epoxy resin and EP / POM(Mo)@POSS(Li) composite material with 2 wt% addition. The maximum CO generation rate of pure epoxy resin is 0.038 g / s, and the maximum CO generation rate of EP / POM(Mo)@POSS(Li) composite material is 0.0180 g / s. This shows that the addition of nano flame retardant can effectively reduce the CO generation rate of epoxy resin material and enhance its flame retardant properties.

[0055] The above is only a specific implementation of the present invention, which enables those skilled in the art to understand or implement the present invention. Although detailed descriptions are given with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments, and they should all be covered by the protection scope of the claims.

Claims

1. A method for preparing submicron spheres of polyoxometalate coated with phenyl alkali metal silsesquioxane, characterized in that: The following steps are involved: Phenyl alkali metal silsesquioxane, polyoxometalate and organic solvent are mixed and coated by intermolecular forces to obtain phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres POM(Mo)@POSS(Li).

2. The method for preparing phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres according to claim 1, characterized in that: The phenyl alkali metal silsesquioxane is an incompletely polycondensed cage-shaped phenyl silsesquioxane containing alkali metal sodium or an incompletely polycondensed cage-shaped phenyl silsesquioxane containing alkali metal lithium.

3. The method for preparing phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres according to claim 1, characterized in that: The polyoxometalate is phosphomolybdic acid or phosphotungstic acid.

4. The method for preparing phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres according to claim 1, characterized in that: The organic solvent is ethanol, methanol, acetone, tetrahydrofuran, dichloromethane, chloroform or dimethyl sulfoxide.

5. The method for preparing 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.

6. The method for preparing phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres according to claim 1, characterized in that: The phenyl alkali metal silsesquioxane, polyoxometalate and organic solvent are mixed and reacted at a temperature of 50-80° C. for a reaction time of 18-25 hours.

7. A method for preparing an EP / POM(Mo)@POSS(Li) composite material, characterized in that: Phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres POM(Mo)@POSS(Li) prepared by the method for preparing phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres as claimed in any one of claims 1 to 6; The steps include: The epoxy resin was heated to 120-150 °C, POM(Mo)@POSS(Li) was added and stirred evenly, and then the curing agent 4,4'-diaminodiphenyl sulfone was added and cured to obtain EP / POM(Mo)@POSS(Li) composite materials.

8. The method for preparing an EP / POM(Mo)@POSS(Li) composite material according to claim 7, characterized in that: The curing temperature is 150-200°C and the curing time is 2-5h.

9. Use of phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres POM(Mo)@POSS(Li) prepared by the method for preparing phenyl alkali metal silsesquioxane-coated polyoxometalate submicron spheres according to any one of claims 1 to 6 as flame retardants.

10. Use of the EP / POM(Mo)@POSS(Li) composite material prepared by the preparation method of the EP / POM(Mo)@POSS(Li) composite material according to claim 7 as a flame retardant material.

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