Synergistic flame retardant based on lanthanum-cerium tetravalent composite salt and preparation method thereof

Abstract

The invention relates to the technical field of flame-retardant materials, and discloses a synergistic flame retardant based on lanthanum-cerium tetravalent composite salt and a preparation method thereof.The synergistic flame retardant comprises a synergistic flame retardant body, the synergistic flame retardant body comprises lanthanum-cerium composite phosphate, ammonium polyphosphate and pentaerythritol, the chemical formula of the lanthanum-cerium composite phosphate is LaxCey (PO4) z.nH2O, and the value range of n is 0.5-1.2. Therefore, the flame-retardant efficiency is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of flame retardant materials, and particularly relates to a synergistic flame retardant based on lanthanum-cerium tetravalent composite salt and a preparation method thereof. Background Art

[0002] As a new type of flame retardant material, rare earth flame retardants exhibit significant synergistic combustion assistance effects, with outstanding advantages such as low addition amount and excellent flame retardant effect. However, current rare earth flame retardants generally have problems such as high price and unstable flame retardant effect, resulting in difficulty in large-scale promotion and application of rare earth flame retardants.

[0003] The following technical problems exist in existing rare earth flame retardants: The raw materials of traditional rare earth flame retardants are expensive. Especially for flame retardants based on cerium nitrate, the raw material price exceeds 5000 yuan / ton, which is much higher than the raw material cost of lanthanum-cerium carbonate in the present invention (less than 1500 yuan / ton), effectively reducing the cost; traditional rare earth salts (such as trivalent cerium salts) have large fluctuations in flame retardant effect during actual application, and poor anti-dripping and smoke suppression properties; most existing rare earth salt compound flame retardants only rely on a single rare earth element (such as lanthanum or cerium), and the synergistic effect between lanthanum and cerium cannot be fully utilized; traditional flame retardants often lack sufficient catalytic carbonization ability, making it difficult to effectively enhance the formation of the carbonized layer, resulting in a low char residue rate of the material. Summary of the Invention

[0004] This part of the present invention content is used to briefly introduce the concepts, which will be described in detail in the following specific implementation part. This part of the present invention content is not intended to identify the key features or essential features of the claimed technical solution, nor is it intended to limit the scope of the claimed technical solution.

[0005] The present invention proposes a synergistic flame retardant based on lanthanum-cerium tetravalent composite salt and a preparation method thereof to solve one or more of the technical problems mentioned in the above background art part.

[0006] In the first aspect, the present invention provides a synergistic flame retardant based on lanthanum-cerium tetravalent composite salt, including: a synergistic flame retardant, which includes lanthanum-cerium composite phosphate, ammonium polyphosphate, and pentaerythritol. Among them, the chemical formula of lanthanum-cerium composite phosphate is La x Ce y (PO4) z ·nH2O, where the value range of n is 0.5 to 1.2.

[0007] In the second aspect, a preparation method of a synergistic flame retardant based on lanthanum-cerium tetravalent composite salt of the present invention includes: Add lanthanum cerium carbonate powder to nitric acid solution, and add hydrogen peroxide for oxidation treatment to obtain a mixed solution; add an aqueous solution of sodium phosphate to the mixed solution and stir at room temperature to form a white precipitate; fully dry the white precipitate to obtain lanthanum cerium composite phosphate; Compound lanthanum cerium composite phosphate, ammonium polyphosphate and pentaerythritol in a certain mass ratio to obtain the synergistic flame retardant as claimed in claim 1.

[0008] Optionally, the reaction temperature of lanthanum cerium carbonate powder and nitric acid solution is room temperature, and the reaction time of lanthanum cerium carbonate powder and nitric acid solution is 1 hour to 3 hours.

[0009] Optionally, the concentration of hydrogen peroxide is 30%, and the addition amount of hydrogen peroxide is 1.2 times to 1.5 times the total molar amount of lanthanum cerium composite phosphate. Hydrogen peroxide is used to oxidize trivalent cerium ions in lanthanum cerium carbonate powder to tetravalent cerium ions.

[0010] Optionally, the nitric acid concentration is 20% to 40%.

[0011] Optionally, the mass ratio of compounding lanthanum cerium composite phosphate, ammonium polyphosphate and pentaerythritol is 1:4:2.

[0012] Optionally, the chemical formula includes trivalent lanthanum ions and tetravalent cerium ions, wherein the molar ratio of tetravalent cerium ions to trivalent lanthanum ions is (1.5 - 2.5):1.

[0013] Optionally, the synergistic flame retardant is applied to each of a variety of polymer materials. The variety of polymer materials includes polyethylene terephthalate, polylactic acid, polypropylene and epoxy resin.

[0014] Optionally, the addition amount of the synergistic flame retardant in each polymer material is 1wt% to 5wt%.

[0015] The present invention has the following beneficial effects: The flame retardancy, anti-dripping and smoke suppression properties are improved. Specifically, lanthanum cerium carbonate is used as the basic raw material, and its raw material cost is only one-third of that of pure lanthanum compounds or pure cerium compounds, significantly reducing the production cost. Compared with traditional high-cost raw materials (such as cerium nitrate, etc.), this raw material is inexpensive. Through the synergistic effect of high-valent lanthanum cerium composite phosphate, the synergistic flame retardant can increase the limiting oxygen index of the polymer material to more than 32% with only 1.5% addition amount, and the vertical burning grade reaches V-0 level. The flame retardant effect is significantly better than that of single rare earth salts or traditional flame retardant systems; the high-valent lanthanum cerium composite phosphate shows a strong synergistic flame retardant effect, showing an effect of 1 + 1 > 2. Compared with the flame retardants of single lanthanum or cerium, the synergistic flame retardant has higher flame retardancy, anti-dripping and smoke suppression capabilities. The synergistic effect between lanthanum and cerium can enhance the ability to capture free radicals, thereby improving the flame retardancy performance; and the LaPO4 / CeP2O7 cross-linked network generated by the synergistic flame retardant during combustion significantly increases the char residue rate of the polymer material from 2.1% to 28.7%, while effectively inhibiting the dripping and smoke release, reducing the generation of harmful gases during the fire; the synergistic flame retardant is applicable to various polymer materials such as polyolefins and polyesters, can meet the flame retardant requirements of different materials, and has good industrial application prospects; the adopted process of "one-pot method of room-temperature acidolysis + hydrogen peroxide oxidation + phosphate precipitation" is simple and efficient, without complex equipment and high-temperature conditions, and is easy to be popularized and applied in industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In combination with the accompanying drawings and with reference to the following specific embodiments, the above and other features, advantages and aspects of the embodiments of the present invention will become more obvious. Throughout the drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic and the elements and elements are not necessarily drawn to scale.

[0017] Figure 1 is a flowchart of a preparation method of a synergistic flame retardant based on a tetravalent lanthanum cerium composite salt of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] The present invention will be described in more detail below with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. On the contrary, these embodiments are provided to more thoroughly and completely understand the present invention. It should be understood that the drawings and embodiments of the present invention are only for exemplary purposes and are not used to limit the protection scope of the present invention.

[0019] In addition, it should be noted that for the sake of convenience of description, only the parts related to the relevant invention are shown in the drawings. Without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0020] It should be noted that the concepts such as "first", "second", etc. mentioned in the present invention are only used to distinguish different devices, modules or units, and are not used to limit the order of functions executed by these devices, modules or units or their interdependent relationships.

[0021] It should be noted that the modification of "one" and "multiple" mentioned in the present invention is illustrative rather than restrictive. Those skilled in the art should understand that unless otherwise clearly specified in the context, it should be understood as "one or more".

[0022] The names of the messages or information exchanged between multiple devices of the present invention are only for illustrative purposes and are not used to limit the scope of these messages or information.

[0023] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0024] Embodiment 1: As Figure 1 shown, a flowchart of a preparation method of a synergistic flame retardant based on lanthanum cerium tetravalent composite salt of the present invention is shown, which specifically includes the following steps: Step 101, adding lanthanum cerium carbonate powder into a nitric acid solution, and adding hydrogen peroxide for oxidation treatment to obtain a mixed solution; adding an aqueous solution of sodium phosphate into the mixed solution and stirring at room temperature to generate a white precipitate; fully drying the white precipitate to obtain lanthanum cerium composite phosphate; Step 102, compounding lanthanum cerium composite phosphate, ammonium polyphosphate and pentaerythritol according to a certain mass ratio to obtain the synergistic flame retardant as claimed in claim 1.

[0025] Among them, the raw materials are: 100 g of lanthanum cerium carbonate (the mass percentage of La2O3 in REO in lanthanum cerium carbonate is 33% to 37%, the mass percentage of CeO2 in REO is 63% to 68%, and the molar ratio of La to Ce is 1:2), 250 mL of nitric acid solution with a concentration of 32%, 50 mL of hydrogen peroxide with a concentration of 30%, and 35 g of sodium phosphate.

[0026] Process: Add 100 g of lanthanum cerium carbonate powder into 250 mL of nitric acid solution. After fully stirring and reacting at room temperature for 1 hour, add 50 mL of 30% hydrogen peroxide, and continue stirring for 30 minutes to obtain a mixed solution. Add an aqueous solution of 35 g of sodium phosphate into the mixed solution, and stir at room temperature for 30 minutes to form a white precipitate. After solid-liquid separation of the white precipitate, dry it thoroughly to obtain lanthanum cerium composite phosphate. After obtaining the lanthanum cerium composite phosphate, compound the lanthanum cerium composite phosphate, ammonium polyphosphate, and pentaerythritol according to a mass ratio of 1:4:2. After compounding, add it to polyethylene terephthalate (PET). Among them, the lanthanum cerium carbonate powder is a mixed carbonate of lanthanum (La) and cerium (Ce). Lanthanum cerium carbonate is converted into rare earth oxides (REO) after high-temperature calcination. The rare earth oxides are a mixture of lanthanum sesquioxide (La2O3) and cerium dioxide (CeO2). Room temperature generally refers to the room temperature range between 20°C and 25°C. The concentration of the nitric acid solution is 32%. In practice, the reaction time of fully stirring at room temperature can be 1 hour to 3 hours. Among them, the lanthanum cerium composite phosphate is a phosphate compound containing lanthanum and cerium, which is a high-valence lanthanum cerium composite phosphate. The chemical formula of the lanthanum cerium composite phosphate is La x Ce y (PO4) z ·nH2O, where the value range of n is 0.5 to 1.2, and x and y are the molar ratios of the two elements lanthanum (La) and cerium (Ce). PO4 is a phosphate ion, and z is the number of phosphate units, indicating how many phosphate ions are contained in each unit of the lanthanum cerium composite phosphate. nH2O represents the water molecules (also called crystal water) that may be contained in the lanthanum cerium composite phosphate. n is the number of water molecules, and the value range is between 0.5 and 1.2. The chemical formula includes trivalent lanthanum ions (La 3+ ) and tetravalent cerium ions (Ce 4+ ). In practice, the molar ratio of Ce 4+ to La 3+ can be (1.5~2.5):1. Compared with trivalent cerium ions, tetravalent cerium ions show obvious advantages in flame retardancy, radical capture, crosslinking promotion, and carbon formation due to their stronger oxidizing property and efficient catalytic effect. Among them, hydrogen peroxide is used to oxidize trivalent cerium ions in the lanthanum cerium carbonate powder into tetravalent cerium ions. Among them, the total addition amount of the lanthanum cerium composite phosphate, ammonium polyphosphate, and pentaerythritol is 1.5%. In practice, the synergistic flame retardant is applied to each of a variety of polymer materials. The variety of polymer materials includes polyethylene terephthalate, polylactic acid, polypropylene, and epoxy resin, etc. The addition amount of the synergistic flame retardant in each polymer material is 1 wt% to 5 wt%. wt% is the weight percentage, indicating the mass percentage of a certain component (such as a certain element, compound, or ingredient) in the mixture.

[0027] Performance test results: PET added with a synergistic flame retardant was used as the first test sample for performance testing. The LOI of the first test sample was 33.2%, UL-94 was V-0 grade, the number of melt drops was 0, and the TSR was 145 m 2 / m 2 Among them, LOI (Limiting Oxygen Index) represents the lowest oxygen concentration required to maintain combustion of the test sample. The LOI value of a single lanthanum or cerium flame retardant is only 22% to 27%. UL-94 is an internationally common vertical combustion test standard, and V-0 is the highest grade under this standard. Among them, V-2 extinguishes within 10 seconds, and there is a melt drop igniting cotton; V-1 extinguishes within 30 seconds, without a melt drop igniting; V-0 extinguishes within 10 seconds and there is no melt drop. Melt drop refers to the phenomenon that a thermoplastic polymer material softens or melts during combustion or at high temperature and drips from the object. The number of melt drops being 0 means that the test sample has no melt drop behavior during combustion, indicating that the flame retardant system can form a good carbon layer barrier structure and effectively inhibit material melting. TSR (Total Smoke Release) refers to the total smoke amount generated per unit area of the material after combustion, with the unit of square meter / square meter. The test result of this test is only 145, indicating that the material has a good smoke suppression effect.

[0028] Comparative Example 1 Raw materials: 100 g of lanthanum cerium carbonate (the mass percentage of La2O3 in REO in lanthanum cerium carbonate is 33% to 37%, the mass percentage of CeO2 in REO is 63% to 68%, and the molar ratio of La to Ce is 1:2), 250 mL of nitric acid solution with a concentration of 32%, and 35 g of sodium phosphate.

[0029] Process: Basically the same as in Example 1, but the hydrogen peroxide oxidation step is omitted, that is, after adding lanthanum cerium carbonate powder to the nitric acid solution, hydrogen peroxide is not added, and sodium phosphate precipitation is directly added to obtain a composite salt mainly composed of cerium phosphate in the trivalent cerium form. After obtaining the composite salt mainly composed of cerium phosphate in the trivalent cerium form, the composite salt mainly composed of cerium phosphate in the trivalent cerium form, ammonium polyphosphate, and pentaerythritol are compounded according to a mass ratio of 1:4:2 and added to polyethylene terephthalate (PET) to obtain the second test sample. The total addition amount of the composite salt mainly composed of cerium phosphate in the trivalent cerium form, ammonium polyphosphate, and pentaerythritol in the second test sample is 1.5%.

[0030] Performance test results: The second test sample was subjected to performance testing. The LOI of the second test sample was 26.5%, UL-94 was V-2 grade, the number of melt drops was 5, and the TSR was 220 m 2 / m 2 。

[0031] Comparative Example 2 Raw materials: Pure lanthanum carbonate.

[0032] Process: Basically the same as in Example 1, that is, pure lanthanum carbonate is added to nitric acid solution, then hydrogen peroxide is added for oxidation, and then sodium phosphate is added for precipitation to obtain lanthanum phosphate-based composite salts. After obtaining the lanthanum phosphate-based composite salts, the lanthanum phosphate-based composite salts, ammonium polyphosphate and pentaerythritol are compounded according to a mass ratio of 1:4:2 and added to polyethylene terephthalate (PET) to obtain the third test sample. The total addition amount of the lanthanum phosphate-based composite salts, ammonium polyphosphate and pentaerythritol in the third test sample is 1.5%.

[0033] Performance test results: The third test sample was subjected to performance tests. The LOI of the third test sample was 23.5%, UL-94 was V-2 level, the number of dripping times was 7, and the TSR was 235 m 2 / m 2 。

[0034] Comparative Example 3 Raw materials: Pure cerium carbonate.

[0035] Process: Basically the same as in Example 1, that is, pure cerium carbonate is added to nitric acid solution, then hydrogen peroxide is added for oxidation, and then sodium phosphate is added for precipitation to obtain cerium phosphate-based composite salts. After obtaining the cerium phosphate-based composite salts, the cerium phosphate-based composite salts, ammonium polyphosphate and pentaerythritol are compounded according to a mass ratio of 1:4:2 and added to polyethylene terephthalate (PET) to obtain the fourth test sample. The total addition amount of the cerium phosphate-based composite salts, ammonium polyphosphate and pentaerythritol in the fourth test sample is 1.5%.

[0036] Performance test results: The fourth test sample was subjected to performance tests. The LOI of the fourth test sample was 29.1%, UL-94 was V-2 level, the number of dripping times was 4, and the TSR was 205 m 2 / m 2 。

[0037] Comparative Example 4 Raw materials and process: Without adding rare earth flame retardants, only equal amounts of ammonium polyphosphate and pentaerythritol are compounded to obtain a composite flame retardant and added to polyethylene terephthalate (PET) to obtain the fifth test sample. Among them, the addition amount of the composite flame retardant in the fifth test sample is 1.5%.

[0038] Performance test results: The fifth test sample was subjected to performance tests. The LOI of the fifth test sample was 21%, UL-94 was V-2 level, the number of dripping times was 11, and the TSR was 310 m 2 / m 2 。

[0039] In these embodiments, lanthanum cerium carbonate is used as a raw material. After lanthanum cerium carbonate is fully dissolved in nitric acid by a one-pot method, hydrogen peroxide is added for oxidation treatment to convert Ce 3+ to Ce 4+ . Then sodium phosphate is added for coprecipitation to generate a high-valence lanthanum cerium composite phosphate. After being compounded with ammonium polyphosphate and pentaerythritol according to a certain mass ratio, it is added to the polymer material, thus achieving the following breakthroughs: Ce 4+ captures free radicals through a redox reaction (Ce 4+ +e - →Ce 3+ ), La 3+ adsorbs PO free radicals through empty orbitals; the free radical capture ability is synergistically enhanced by the valence states of lanthanum and cerium; when the lanthanum cerium composite phosphate burns, a LaPO4 / CeP2O7 cross-linked network is formed, which can increase the char residue rate of PET from 2.1% to 28.7%; when the total addition amount of the lanthanum cerium composite phosphate, ammonium polyphosphate and pentaerythritol is 1.5%, the LOI can be greater than 32%, UL-94 reaches V-0 level, and the smoke suppression rate increases by 40%.

[0040] The above description is only some preferred embodiments of the present invention and an explanation of the applied technical principles. Those skilled in the art should understand that the scope of the invention involved in the present invention is not limited to the technical solutions formed by the specific combination of the above technical features, and should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above inventive concept. For example, the technical solutions formed by mutually replacing the above features with the (but not limited to) technical features with similar functions disclosed in the present invention.

Claims

1. A synergistic flame retardant based on a lanthanum-cerium tetravalent composite salt, characterized in that: include: A synergistic flame retardant, the synergistic flame retardant comprises lanthanum cerium composite phosphate, ammonium polyphosphate and pentaerythritol, wherein the chemical formula of the lanthanum cerium composite phosphate is La x Ce y (PO4) z nH2O, where n ranges from 0.5 to 1.

2.

2. A method for preparing a synergistic flame retardant based on a lanthanum-cerium tetravalent composite salt, characterized in that: include: Adding lanthanum carbonate cerium powder to a nitric acid solution, and adding hydrogen peroxide for oxidation treatment to obtain a mixed solution; adding an aqueous solution of sodium phosphate to the mixed solution and stirring at room temperature to generate a white precipitate; and fully drying the white precipitate to obtain a lanthanum cerium composite phosphate; The lanthanum-cerium composite phosphate, ammonium polyphosphate and pentaerythritol are compounded in a certain mass ratio to obtain the synergistic flame retardant as claimed in claim 1.

3. The method for preparing a synergistic flame retardant based on a tetravalent lanthanum-cerium composite salt according to claim 2, characterized in that: The reaction temperature of the lanthanum cerium carbonate powder and the nitric acid solution is room temperature, and the reaction time of the lanthanum cerium carbonate powder and the nitric acid solution is 1 hour to 3 hours.

4. The method for preparing a synergistic flame retardant based on a lanthanum-cerium tetravalent composite salt according to claim 2, characterized in that: The concentration of the hydrogen peroxide is 30%, and the amount of the hydrogen peroxide added is 1.2 to 1.5 times the total molar amount of the lanthanum-cerium composite phosphate. The hydrogen peroxide is used to oxidize the trivalent cerium ions in the lanthanum cerium carbonate powder into tetravalent cerium ions.

5. The method for preparing a synergistic flame retardant based on a lanthanum-cerium tetravalent composite salt according to claim 2, characterized in that: The nitric acid concentration is 20% to 40%.

6. The method for preparing a synergistic flame retardant based on a tetravalent lanthanum-cerium composite salt according to claim 2, characterized in that: The mass ratio of the lanthanum-cerium composite phosphate, ammonium polyphosphate and pentaerythritol is 1:4:

2.

7. The synergistic flame retardant based on lanthanum-cerium tetravalent composite salt according to claim 1, characterized in that: The chemical formula includes trivalent lanthanum ions and tetravalent cerium ions, wherein the molar ratio of the tetravalent cerium ions to the trivalent lanthanum ions is (1.5-2.5):

1.

8. The use of the synergistic flame retardant based on lanthanum-cerium tetravalent composite salt according to claim 1, characterized in that: The synergistic flame retardant is applied to each polymer material in a plurality of polymer materials, and the plurality of polymer materials include polyethylene terephthalate, polylactic acid, polypropylene and epoxy resin.

9. The use of the synergistic flame retardant based on the tetravalent lanthanum-cerium composite salt according to claim 8, characterized in that: The synergistic flame retardant is added in an amount of 1 wt % to 5 wt % in each polymer material.

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