Oil shale semi-coke / red phosphorus / DOPO flame retardant, and preparation method and application thereof

Abstract

The application discloses an oil shale semi-coke / red phosphorus / DOPO flame retardant. In the flame retardant, DOPO is grafted on the surfaces of oil shale semi-coke and red phosphorus, the mass percentage of DOPO grafted on the surfaces of oil shale semi-coke and red phosphorus is 3%-5% of the total mass of oil shale semi-coke and red phosphorus, and the mass ratio of oil shale semi-coke to red phosphorus is 5:1-25:1. Compared with the prior art, the flame retardant can not only realize resource recycling of oil shale semi-coke waste, but also has the characteristics of high flame retardation and low smoke generation.

Description

Technical Field

[0001] This invention relates to a flame retardant for oil shale semi-coke / red phosphorus / DOPO. Background Technology

[0002] Oil shale carbonization leaves behind oil shale semi-coke, a substance containing various toxic and harmful substances such as phenols, heavy metals, polycyclic aromatic hydrocarbons, and sulfur-containing compounds, resulting in low combustion value. The semi-coke itself has a high proportion of inorganic minerals, with aluminosilicates being the main component. It also contains unutilized residual carbon. Due to its porous structure, the semi-coke exhibits certain chemical activity. Theoretically, this material can be used as a polymer filler or a flame-retardant additive, transforming oil shale semi-coke into high-value-added functional materials. This achieves waste resource reuse, aligns with the development direction of the circular economy, meets environmental protection requirements, and can generate both environmental and economic benefits.

[0003] Red phosphorus is a highly efficient but flawed phosphorus-based flame retardant. It has a high phosphorus content (nearly 100%) and significant flame-retardant efficiency. While its combination with oil shale semi-coke can significantly improve the flame-retardant properties of polymer materials, it also leads to a sharp increase in flameless smoke density and a significant decrease in toughness. Summary of the Invention

[0004] In order to overcome the above-mentioned defects in the use of oil shale semi-coke and red phosphorus as flame retardants, the present invention provides an oil shale semi-coke / red phosphorus / DOPO flame retardant.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A flame retardant for oil shale semi-coke / red phosphorus / DOPO is characterized in that: DOPO is grafted onto the surface of oil shale semi-coke and red phosphorus, and the grafting of DOPO is carried out at 3% to 5% of the total mass of oil shale semi-coke and red phosphorus, and the mass ratio of oil shale semi-coke to red phosphorus is 5:1 to 25:1.

[0007] Preferably, the oil shale semi-coke is silane coupling agent modified oil shale semi-coke.

[0008] Preferably, the silane coupling agent is an aminosilane coupling agent, more preferably KH-550.

[0009] Preferably, the silane coupling agent modified oil shale semi-coke is obtained by a method including the following steps: the oil shale semi-coke is first acid-leached for a certain time, and then reacted with the silane coupling agent in an ethanol solvent by heating for a certain time.

[0010] Preferably, the amount of the silane coupling agent is 0.5-2.5% of the mass of oil shale semi-coke; more preferably, the reaction temperature is 60-80°C.

[0011] The preparation method of the above flame retardant includes: reacting oil shale semi-coke, red phosphorus and DOPO in acidic ethanol.

[0012] Preferably, the reaction temperature is 60~80℃ and the time is 12~24 hours.

[0013] Preferably, the pH value of the acidic ethanol is 3 to 5.

[0014] A polypropylene flame-retardant composite material, wherein the polypropylene flame-retardant composite material is mainly composed of polypropylene and the flame retardant as described above, wherein the content of the flame retardant is 10~30 wt%.

[0015] Preferably, the polypropylene flame-retardant composite material contains 1 wt% zinc hydroxystannate. Attached Figure Description

[0016] Figure 1 The images show the XRD patterns of red phosphorus / semi-coke powder before and after DOPO grafting, where a-DOPO grafted powder, b-red phosphorus / semi-coke powder, c-silane coupling agent modified oil shale semi-coke, d-DOPO, and e-red phosphorus.

[0017] Figure 2 XPS full scan spectra of red phosphorus / semi-coke powder before and after DOPO grafting. Detailed Implementation

[0018] The technical solution of the present invention will be further described in detail below with reference to the embodiments.

[0019] 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, abbreviated as DOPO.

[0020] Example 1

[0021] Pre-dried oil shale semi-coke was placed in a stirred mill and ball-milled at 400 r / min for 20 minutes (ball-to-material ratio 10:1).

[0022] Modification of oil shale semi-coke: 100 g of ball-milled oil shale semi-coke was added to 1 mol / L nitric acid and stirred for 2 h. The mixture was then filtered, washed repeatedly with deionized water and anhydrous ethanol, and dried in an oven at 60 ℃ for 24 h. The resulting dispersion was then dispersed in 450 mL of anhydrous ethanol to obtain an oil shale semi-coke dispersion. 2 g of silane coupling agent (KH-550) was added to 50 mL of anhydrous ethanol to obtain a coupling agent solution. This coupling agent solution was added to the oil shale semi-coke dispersion, and the mixture was heated and stirred at 70 ℃ for 2 h. After natural cooling, the mixture was filtered, washed repeatedly with deionized water and anhydrous ethanol, and dried in an oven at 60 ℃ for 24 h to obtain silane coupling agent modified oil shale semi-coke.

[0023] To prepare acidic ethanol: Slowly add nitric acid dropwise to anhydrous ethanol until pH=4.

[0024] The red phosphorus and silane coupling agent modified oil shale semi-coke were weighed and mixed at a mass ratio of 1:5. The mixture was placed in a ball mill and continuously ball-milled at a speed of 200 r / min for 1 h to obtain red phosphorus / semi-coke powder.

[0025] Weigh 100 g of red phosphorus / semi-coke powder and add it to 480 mL of acidic ethanol. Sonicate for 1 h, then heat to 70 °C with stirring. Slowly add 20 mL (containing 3 g) of DOPO ethanol solution, and continue stirring for 16 h after the addition is complete. After the reaction is complete, allow to cool naturally, wash three times each with anhydrous ethanol and deionized water, and dry at 60 °C to obtain DOPO grafted powder.

[0026] Figure 1 The XRD patterns of red phosphorus / semi-coke powder before and after DOPO grafting are shown. The XRD patterns reveal that all of DOPO's sharp crystalline peaks (12.1°, 13.5°, 16.0°, 19.5°, etc.) completely disappear after grafting, indicating that DOPO was not simply physically mixed, but rather grafted onto the surface of the red phosphorus / semi-coke powder in an amorphous state through a chemical reaction.

[0027] Figure 2 The images show the Fourier transform infrared (FTIR) spectra of red phosphorus / semi-coke powder before and after DOPO grafting. The peak changes in the 1200-900 cm⁻¹ range indicate the formation of new chemical bonds (such as PO-Si or POC) in the grafted powder, demonstrating that DOPO was successfully grafted onto the surface of the semi-coke / red phosphorus powder through chemical bonding (PO-Si or POC bonds).

[0028] Performance testing

[0029] The powders prepared in Example 1 were used as flame retardants. The flame retardant (30 wt%) and polypropylene (70 wt%, PP) were placed in a mixer and mixed for 10 min at a furnace temperature of 210 ℃. The composite material formed by mixing was then vulcanized for 5 min on a flat vulcanizing machine at 170 ℃ and 10 MPa pressure, and cooled for 3 min to obtain halogen-free flame-retardant composite polypropylene material.

[0030] (1) Mechanical property test standard GB-T 1040.3-2006, the tensile rate is set to 50 mm / min.

[0031] (2) The standard for flameless smoke density test is GB / T 8323.2-2008. The sample size is 75×75×1 mm³, and the heat flux intensity is set to 25 KW / m².

[0032] (3) Cone calorimetry (CCT) test conditions ISO 5660 – 1, sample size 100×100×3 mm³, heat flux intensity set to 50 KW / m².

[0033] (4) Limiting Oxygen Index (LOI) test standard GB / T 2406.2-2009.

[0034] (5) Horizontal and vertical burning (UL-94) test standard GB / T 2408-2021.

[0035] Table 1 Mechanical properties of halogen-free flame-retardant composite polypropylene materials

[0036]

[0037] As shown in Table 1, compared with silane coupling agent modified oil shale semi-coke, the elongation at break of silane coupling agent modified oil shale semi-coke after being compounded with red phosphorus decreased significantly. When DOPO was grafted onto the surface of red phosphorus / semi-coke powder, the decrease in elongation at break was significantly reduced, indicating that grafting DOPO onto the surface of red phosphorus / semi-coke powder can effectively overcome the problem of significant deterioration of the toughness of polypropylene materials when semi-coke is compounded with red phosphorus.

[0038] Table 2 Flameless smoke density of halogen-free flame-retardant composite polypropylene materials

[0039]

[0040] Table 2 shows that the flameless smoke density increased significantly after silane coupling agent-modified oil shale semi-coke was compounded with red phosphorus. When DOPO was grafted onto the surface of the red phosphorus / semi-coke powder, the flameless smoke density decreased significantly and was significantly lower than that of silane coupling agent-modified oil shale semi-coke. This indicates that grafting DOPO onto the surface of red phosphorus / semi-coke powder can effectively overcome the problem of impaired smoke suppression performance when semi-coke is compounded with red phosphorus.

[0041] Table 3. Cone calorimetry results of halogen-free flame-retardant composite polypropylene materials

[0042]

[0043] Fire performance index (FPI), which is the ratio of ignition time (TTI) to peak heat release rate (PHHR), is a measure of the time it takes for a fire to spread to the flashover threshold in a confined space. A lower FPI value means the material can quickly reach a high heat release rate during a fire, thus increasing the fire risk. Table 3 shows that compared to silane coupling agent-modified oil shale semi-coke, the FPI after compounding with red phosphorus decreased from 0.034 s·m 2 / kW increased to 0.042 s·m 2 / kW, which further increases to 0.056 s·m after grafting DOPO. 2 / kW.

[0044] The higher the Fire Spread Index (FGI) (the ratio of PHRR to time to peak heat release rate (tPHRR), the shorter the time it takes for the material to reach a high heat release rate, and the higher the fire spread rate and the greater the danger. Table 3 shows that after compounding with red phosphorus, the FGI of the silane coupling agent-modified oil shale semi-coke is 9.66 kW / s·m. 2 Reduced to 8.97 kW / s·m 2 After grafting DOPO, the power further decreased to 6.58 kW / s·m 2 .

[0045] The above cone calorimetry test results show that the flame retardant of the present invention can effectively reduce the risk of fire and slow down the spread of fire, which will allow more time for the safe evacuation of trapped personnel and the implementation of rescue measures in the event of an actual fire.

[0046] Table 4. UL-94 and LOI results for halogen-free flame-retardant composite polypropylene materials

[0047]

[0048] As can be seen from Table 4, the flame retardant of the present invention has excellent flame retardancy.

[0049] Example 2

[0050] The red phosphorus / semi-coke powder (30 wt%), zinc hydroxystannate (1 wt%), and PP (balance) prepared in Example 1 were placed in a Banbury mixer and mixed for 10 min at a furnace temperature of 210 ℃. The resulting composite material was then vulcanized for 5 min on a flat vulcanizing machine at 170 ℃ and 10 MPa pressure, followed by cooling for 3 min to obtain a halogen-free flame-retardant composite polypropylene material. The performance test results are as follows:

[0051] Tensile strength: 20.26 MPa; Elongation at break: 70.44%;

[0052] LOI 27.7%;

[0053] UL-94 V0;

[0054] Flameless smoke density: 291.06;

[0055] Cone calorimetry: TTI 33s, PHRR 428.93 KW / m 2 , tPHRR 75s, THR 100.96 MJ / m 2 , EHC41.97 MJ / kg, TSP 19.26m 3 , TOC 63.72g, FPI 0.077 s·m 2 / kW, FGI 5.72 kW / s·m 2 .

[0056] Example 3

[0057] Pre-dried oil shale semi-coke was placed in a stirred mill and ball-milled at 400 r / min for 20 minutes (ball-to-material ratio 10:1).

[0058] Modification of oil shale semi-coke: 100 g of ball-milled oil shale semi-coke was added to 1 mol / L nitric acid and stirred for 2 h. The mixture was then filtered, washed repeatedly with deionized water and anhydrous ethanol, and dried in an oven at 60 ℃ for 24 h. The resulting dispersion was then dispersed in 450 mL of anhydrous ethanol to obtain an oil shale semi-coke dispersion. 2 g of silane coupling agent (KH-550) was added to 50 mL of anhydrous ethanol to obtain a coupling agent solution. This coupling agent solution was added to the oil shale semi-coke dispersion, and the mixture was heated and stirred at 70 ℃ for 2 h. After natural cooling, the mixture was filtered, washed repeatedly with deionized water and anhydrous ethanol, and dried in an oven at 60 ℃ for 24 h to obtain silane coupling agent modified oil shale semi-coke.

[0059] To prepare acidic ethanol: Slowly add nitric acid dropwise to anhydrous ethanol until pH=4.

[0060] The red phosphorus and silane coupling agent modified oil shale semi-coke were weighed and mixed at a mass ratio of 3:25. The mixture was then placed in a ball mill and continuously ball-milled at a speed of 200 r / min for 1 h to obtain red phosphorus / semi-coke powder.

[0061] Weigh 100 g of red phosphorus / semi-coke powder and add it to 480 mL of acidic ethanol. Sonicate for 1 h, then heat to 70 °C with stirring. Slowly add 20 mL (containing 3 g) of DOPO ethanol solution, and continue stirring for 16 h after the addition is complete. After the reaction is complete, allow to cool naturally, wash three times each with anhydrous ethanol and deionized water, and dry at 60 °C to obtain DOPO grafted powder.

[0062] Example 4

[0063] Pre-dried oil shale semi-coke was placed in a stirred mill and ball-milled at 400 r / min for 20 minutes (ball-to-material ratio 10:1).

[0064] Modification of oil shale semi-coke: 100 g of ball-milled oil shale semi-coke was added to 1 mol / L nitric acid and stirred for 2 h. The mixture was then filtered, washed repeatedly with deionized water and anhydrous ethanol, and dried in an oven at 60 ℃ for 24 h. The resulting dispersion was then dispersed in 450 mL of anhydrous ethanol to obtain an oil shale semi-coke dispersion. 2 g of silane coupling agent (KH-550) was added to 50 mL of anhydrous ethanol to obtain a coupling agent solution. This coupling agent solution was added to the oil shale semi-coke dispersion, and the mixture was heated and stirred at 70 ℃ for 2 h. After natural cooling, the mixture was filtered, washed repeatedly with deionized water and anhydrous ethanol, and dried in an oven at 60 ℃ for 24 h to obtain silane coupling agent modified oil shale semi-coke.

[0065] To prepare acidic ethanol: Slowly add nitric acid dropwise to anhydrous ethanol until pH=4.

[0066] The red phosphorus and silane coupling agent modified oil shale semi-coke were weighed and mixed at a mass ratio of 1:25. The mixture was then placed in a ball mill and continuously ball-milled at a speed of 200 r / min for 1 h to obtain red phosphorus / semi-coke powder.

[0067] Weigh 100 g of red phosphorus / semi-coke powder and add it to 480 mL of acidic ethanol. Sonicate for 1 h, then heat to 70 °C with stirring. Slowly add 20 mL (containing 3 g) of DOPO ethanol solution, and continue stirring for 16 h after the addition is complete. After the reaction is complete, allow to cool naturally, wash three times each with anhydrous ethanol and deionized water, and dry at 60 °C to obtain DOPO grafted powder.

[0068] Example 5

[0069] Pre-dried oil shale semi-coke was placed in a stirred mill and ball-milled at 400 r / min for 20 minutes (ball-to-material ratio 10:1).

[0070] Modification of oil shale semi-coke: 100 g of ball-milled oil shale semi-coke was added to 1 mol / L nitric acid and stirred for 2 h. The mixture was then filtered, washed repeatedly with deionized water and anhydrous ethanol, and dried in an oven at 60 ℃ for 24 h. The resulting dispersion was then dispersed in 450 mL of anhydrous ethanol to obtain an oil shale semi-coke dispersion. 2 g of silane coupling agent (KH-540) was added to 50 mL of anhydrous ethanol to obtain a coupling agent solution. This coupling agent solution was added to the oil shale semi-coke dispersion, and the mixture was heated and stirred at 75 ℃ for 2 h. After natural cooling, the mixture was filtered, washed repeatedly with deionized water and anhydrous ethanol, and dried in an oven at 60 ℃ for 24 h to obtain silane coupling agent modified oil shale semi-coke.

[0071] To prepare acidic ethanol: Slowly add nitric acid dropwise to anhydrous ethanol until pH=4.

[0072] The red phosphorus and silane coupling agent modified oil shale semi-coke were weighed and mixed at a mass ratio of 1:5. The mixture was placed in a ball mill and continuously ball-milled at a speed of 200 r / min for 1 h to obtain red phosphorus / semi-coke powder.

[0073] Weigh 100 g of red phosphorus / semi-coke powder and add it to 480 mL of acidic ethanol. Sonicate for 1 h, then heat to 75 °C with stirring. Slowly add 20 mL (containing 5 g) of DOPO ethanol solution, and continue stirring for 16 h after the addition is complete. After the reaction is complete, allow to cool naturally, wash three times each with anhydrous ethanol and deionized water, and dry at 60 °C to obtain DOPO grafted powder.

[0074] Example 6

[0075] Pre-dried oil shale semi-coke was placed in a stirred mill and ball-milled at 400 r / min for 20 minutes (ball-to-material ratio 10:1).

[0076] To prepare acidic ethanol: Slowly add nitric acid dropwise to anhydrous ethanol until pH=4.

[0077] The red phosphorus and oil shale semi-coke were weighed and mixed at a mass ratio of 1:5. The mixture was then placed in a ball mill and continuously milled at a speed of 200 r / min for 1 h to obtain red phosphorus / semi-coke powder.

[0078] Weigh 100 g of red phosphorus / semi-coke powder and add it to 480 mL of acidic ethanol. Sonicate for 1 h, then heat to 70 °C with stirring. Slowly add 20 mL (containing 3 g) of DOPO ethanol solution, and continue stirring for 16 h after the addition is complete. After the reaction is complete, allow to cool naturally, wash three times each with anhydrous ethanol and deionized water, and dry at 60 °C to obtain DOPO grafted powder.

[0079] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A flame retardant for oil shale semi-coke / red phosphorus / DOPO, characterized in that: DOPO is grafted onto the surface of oil shale semi-coke and red phosphorus. DOPO is grafted at 3% to 5% of the total mass of oil shale semi-coke and red phosphorus, with a mass ratio of oil shale semi-coke to red phosphorus of 5:1 to 25:

1.

2. The flame retardant according to claim 1, characterized in that: The oil shale semi-coke is a silane coupling agent modified oil shale semi-coke.

3. The flame retardant according to claim 2, characterized in that: The silane coupling agent is an aminosilane coupling agent, preferably KH-550.

4. The flame retardant according to claim 2 or 3, characterized in that: The silane coupling agent modified oil shale semi-coke is obtained by a method including the following steps: the oil shale semi-coke is first acid-leached for a certain time, and then reacted with the silane coupling agent in an ethanol solvent by heating for a certain time.

5. The flame retardant according to claim 4, characterized in that: The amount of the silane coupling agent is 0.5-2.5% of the mass of oil shale semi-coke, and preferably, the reaction temperature is 60-80℃.

6. A method for preparing the flame retardant according to any one of claims 1 to 5, comprising: Oil shale semi-coke, red phosphorus, and DOPO are reacted in a mixture in acidic ethanol.

7. The preparation method according to claim 6, characterized in that: The reaction is carried out at a temperature of 60-80°C for 12-24 hours.

8. The preparation method according to claim 6, characterized in that: The pH value of the acidic ethanol is 3 to 5.

9. A flame-retardant polypropylene composite material, characterized in that: The polypropylene flame-retardant composite material is mainly composed of polypropylene and the flame retardant as described in any one of claims 1 to 5, wherein the content of the flame retardant is 10 to 30 wt.

10. The polypropylene flame-retardant composite material according to claim 9, characterized in that: The polypropylene flame-retardant composite material contains 1 wt% zinc hydroxystannate.

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