Halogen-free phosphonate hindered piperidine ammonium salt ionic liquid flame retardant, preparation method and application thereof, and flame-retardant polypropylene material and preparation method

Abstract

The application discloses a halogen-free phosphonate hindered piperidine ammonium salt ionic liquid flame retardant and a preparation method and application thereof, a flame-retardant polypropylene material and a preparation method, and belongs to the technical field of chemical synthesis. The preparation method of the halogen-free phosphonate hindered piperidine ammonium salt ionic liquid flame retardant comprises the following steps: performing a solvothermal reaction on di-ester phosphate and 4-amino hindered piperidine amine as raw materials, and then performing vacuum distillation to obtain the halogen-free phosphonate hindered piperidine ammonium salt ionic liquid flame retardant. That is, the halogen-free phosphonate hindered piperidine ammonium salt ionic liquid flame retardant is synthesized by a one-step method. The nitrogen and phosphorus synergistic effect is utilized to release organic phosphorus and nitrogen free radicals to capture gas phase free radicals during combustion, and the hindered piperidine amine is decomposed to generate non-combustible gas, thereby playing a role of heat absorption and combustible gas dilution. In daily use, the hindered piperidine amine can be converted into stable nitrogen-oxygen free radicals to play a catalytic anti-ultraviolet aging function, and the halogen-free phosphonate hindered piperidine ammonium salt ionic liquid flame retardant has the dual performance of high-efficiency flame retardation and anti-aging.

Description

Technical Field

[0001] This invention belongs to the field of chemical synthesis technology, and particularly relates to a halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant, its preparation method and application, and flame-retardant polypropylene materials and their preparation methods. Background Technology

[0002] Polypropylene (PP), a commonly used thermoplastic material, is widely used in many fields, such as product packaging, textiles, and food and pharmaceutical containers, due to its simple structure, low processing requirements, moderate mechanical properties, good insulation, recyclability, and low cost. However, the simple hydrocarbon main chain structure and side methyl groups of PP make it highly flammable and have poor resistance to ultraviolet aging. This limits the use of this low-cost, high-performance general-purpose plastic in specific scenarios, such as gas stations where static electricity accumulation needs to be avoided, computer rooms, and areas with increased surface area for synthetic fiber woven products. To improve the flame retardant and anti-aging properties of polypropylene products, the most common modification method in the industry is to add corresponding flame retardants and antioxidants.

[0003] To improve the flame retardancy of polypropylene (PP), general plastics manufacturers commonly add significant amounts (≥10%) of flame retardants or fillers with flame-retardant properties. However, many previously used high-efficiency flame retardants are halogenated, which release hydrogen halides during the flame-retardant process, severely polluting the atmosphere and thus facing increasingly stringent environmental regulations. Traditional phosphate ester flame retardants, due to their poor compatibility with polypropylene, gradually leach out and become ineffective when added in large quantities. Furthermore, using a single phosphate ester flame retardant yields poor flame-retardant efficiency, typically requiring the formulation with other additives and fillers to achieve flame-retardant modification. In addition, phosphate ester compounds, due to their poor water solubility, easily leach out and remain in the environment, posing a potential biological hazard.

[0004] PP materials are prone to UV aging due to the presence of side methyl groups. The industry often adds antioxidants to achieve basic UV aging resistance. However, most common antioxidants are flammable additives, and their use will further weaken the fire resistance of the composite material.

[0005] Therefore, to overcome the limitations of traditional flame retardant additives, this invention proposes a halogen-free flame retardant based on a phosphate diester-hindered piperidine amine ionic liquid and its efficient preparation method. The ionic liquid is prepared by using specific raw materials in an aqueous or oily solvent environment for acid-base neutralization to form a salt, followed by vacuum distillation to remove unused small molecule raw materials and solvents. In terms of flame retardancy, the high viscosity and higher melting point of the ionic liquid replace traditional room-temperature flowing phosphate ester flame retardants, delaying the precipitation behavior of phosphate ester flame retardant additives in the polymer matrix. Simultaneously, a phosphorus-ammonium ionic compound with an alkyl structure is used to better disperse in the polymer matrix than traditional ammonium polyphosphate (APP). This will provide an optional solution for expanding the wider application of flame-retardant PP materials. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention proposes a halogen-free phosphate hindered piperidinium ammonium salt ionic liquid flame retardant, its preparation method and application, and a flame-retardant polypropylene material and its preparation method. Specifically, this invention synthesizes a halogen-free phosphate hindered piperidinium ammonium salt ionic liquid flame retardant in a one-step process. By introducing a hindered piperidinium amine structure onto the phosphate ester, under halogen-free conditions and with nitrogen-phosphorus synergistic flame retardancy, the organophosphorus nitrogen free radicals can effectively capture gaseous free radicals during combustion. Simultaneously, the hindered piperidinium amine thermally decomposes to produce nitrogen-containing non-flammable gas, which absorbs heat and dilutes the surrounding flammable gas atmosphere. Furthermore, under normal use conditions, the hindered piperidinium amine can be converted into stable nitric oxide free radicals with catalytic activity, improving the polymer's resistance to UV aging.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A halogen-free phosphate ester hindered piperidine ammonium salt ionic liquid flame retardant, with the structural formula as shown in Formula I:

[0009] ;

[0010] In Equation I, R1 and R2 are selected from C4-C8, respectively.

[0011] Optionally, the structural formula of the halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant is:

[0012] or .

[0013] The preparation method of the above-mentioned halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant includes the following steps:

[0014] The halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant was prepared by solvothermal reaction of phosphate diester and 4-aminohindered piperidine amine as raw materials, followed by vacuum distillation.

[0015] Optionally, the molar ratio of the phosphate diester to the 4-aminohedralized piperidine compound is 1:0.9 to 1:1.1.

[0016] Optionally, the phosphate diester is selected from either dibutyl phosphate or di(2-ethylhexyl) phosphate.

[0017] Optionally, the 4-aminohedralized piperidine is selected from 4-amino-2,2,6,6-tetramethylpiperidine (CAS No.: 36768-62-4) or 4-aminomethyl-2,2,6,6-tetramethylpiperidine.

[0018] Optionally, the specific process of the solvothermal reaction is as follows:

[0019] The phosphate diester and 4-aminohedralized piperidine were dissolved in solvents respectively, mixed evenly, and heated and stirred at 60°C for 2 hours.

[0020] Furthermore, the solvent is at least one selected from deionized water, tetrahydrofuran, anhydrous ethanol, ethyl acetate, dichloromethane, and cyclohexane.

[0021] Optionally, the conditions for vacuum distillation are: temperature below 160°C and vacuum degree of 0.05~0.08MPa.

[0022] The above-mentioned halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant is used in the preparation of flame-retardant polypropylene materials.

[0023] A flame-retardant polypropylene material, in addition to polypropylene resin, also includes the halogen-free phosphate hindered piperidinium salt ionic liquid flame retardant.

[0024] Optionally, the amount of the halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant added is 5-15 wt% of the polypropylene resin.

[0025] A method for preparing a flame-retardant polypropylene material includes the following steps:

[0026] The flame-retardant polypropylene material is prepared by melting and plasticizing polypropylene resin and then adding the halogen-free phosphate hindered piperidinium salt ionic liquid flame retardant.

[0027] Optionally, the blending temperature is 170–200°C, and the blending time is 10–15 minutes.

[0028] Compared with the prior art, the present invention has the following advantages and technical effects:

[0029] This invention synthesizes a halogen-free phosphate ester hindered piperidinium ammonium salt ionic liquid flame retardant via a one-step method. By introducing a hindered piperidinium amine structure onto the phosphate ester, under halogen-free conditions and while satisfying the requirements of nitrogen-phosphorus synergistic high-efficiency flame retardancy, the organophosphorus nitrogen free radicals can effectively capture gaseous free radicals during combustion. Simultaneously, the hindered piperidinium amine undergoes thermal decomposition to generate nitrogen-containing non-flammable gas, which absorbs heat and dilutes the surrounding flammable gas atmosphere. Under normal use conditions, the hindered piperidinium amine can be converted into stable nitrogen-oxygen free radicals with catalytic activity, improving the polymer's resistance to UV aging.

[0030] The halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant disclosed in this invention can maintain good stability at the processing temperature of polyolefin materials, and also has good resistance to hydrolysis.

[0031] The halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant disclosed in this invention does not contain halogen components and does not release halogen-containing toxic fumes during combustion. This flame retardant has good hydrophilicity and is easy to dissolve or disperse once it enters the environment. It is difficult to accumulate in organisms or ecosystems, which significantly reduces the potential pollution risk from long-term exposure and shows excellent environmentally friendly characteristics.

[0032] Compared to traditional triphosphate flame retardants that release irritating gases during plastic processing and molding, the halogen-free phosphate hindered piperidinium salt ionic liquid flame retardant disclosed in this invention does not release irritating gases during plastic processing and molding, thus providing better protection for relevant workers.

[0033] The raw materials used in the halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant disclosed in this invention are readily available, and the synthesis process is simple. It has good application prospects in flame retardancy and UV aging resistance enhancement of polypropylene materials. Attached Figure Description

[0034] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0035] Figure 1 This is a photograph of the room temperature physical sample of the halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant of Example 1 of the present invention;

[0036] Figure 2 The infrared spectrum of the halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant of Example 1 of the present invention is shown below.

[0037] Figure 3 This is the 1H NMR spectrum of the halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant of Example 1 of the present invention;

[0038] Figure 4The NMR phosphorus spectrum of the halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant of Example 1 of the present invention;

[0039] Figure 5 The TGA thermogravimetric curve of the halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant of Example 1 of the present invention is shown. Detailed Implementation

[0040] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0041] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0042] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0043] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0044] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0045] In a first aspect, embodiments of the present invention provide a method for preparing a halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant, comprising the following steps:

[0046] Phosphate diester was placed in a three-necked flask and dissolved in solvent A. 4-Aminohedral piperidineamine was dissolved in solvent B and transferred to a constant pressure titration funnel, then slowly added dropwise to the mixed solution. The mixture was heated and stirred at 60°C, and then slowly added dropwise to the three-necked flask at a certain rate under a nitrogen atmosphere for 2 hours to obtain a pale yellow liquid. The mixed solution was then subjected to vacuum distillation under a nitrogen atmosphere to remove the solvent, yielding a viscous yellow liquid product, which is the halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant.

[0047] In a preferred embodiment of the invention, the molar ratio of phosphate diester to 4-aminohedrin is 1:1.

[0048] In a preferred embodiment of the present invention, solvent B is deionized water, and the molar ratio of deionized water to 4-aminohedralized piperidine is 100:1.

[0049] In a preferred embodiment of the present invention, the phosphate diester is either dibutyl phosphate or di(2-ethylhexyl) phosphate; the 4-amino-hindered piperidineamine compound is either 4-amino-2,2,6,6-tetramethylpiperidine or 4-aminomethyl-2,2,6,6-tetramethylpiperidine.

[0050] Secondly, the present invention provides a halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant prepared by the above preparation method. When the phosphate diester is dibutyl phosphate and 4-amino-2,2,6,6-tetramethylpiperidine, its chemical structure is shown in Formula II; when the phosphate diester is di(2-ethylhexyl) phosphate and 4-amino-2,2,6,6-tetramethylpiperidine, its chemical structure is shown in Formula III.

[0051] Thirdly, the present invention provides the application of the above-mentioned halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant in the preparation of flame-retardant polypropylene materials.

[0052] Fourthly, the present invention provides a flame-retardant polypropylene material comprising the above-mentioned halogen-free phosphate hindered piperidinium salt ionic liquid flame retardant; wherein, the halogen-free phosphate hindered piperidinium salt ionic liquid flame retardant is added in the flame-retardant polypropylene material at a dosage of 5 to 15 parts based on 100 parts of polypropylene resin.

[0053] Unless otherwise specified, "room temperature" in this invention refers to 20-30℃.

[0054] Unless otherwise specified, the term "parts" in this invention refers to parts by weight.

[0055] All raw materials used in this invention were purchased from the market.

[0056] The technical solution of the present invention will be further illustrated by the following embodiments.

[0057] Example 1

[0058] A method for preparing a halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant includes the following steps:

[0059] Place 21g (0.1mol) of dibutyl phosphate in a three-necked flask and add 10mL of deionized water to dissolve it;

[0060] 15.6 g (0.1 mol) of 4-amino-2,2,6,6-tetramethylpiperidine was added dropwise to 60 mL of deionized water to prepare a mixed solution, which was then transferred to a constant pressure titration funnel. The solution was heated and stirred at 60 °C, and slowly added dropwise to a three-necked flask at a rate of 0.3 mL / s to 2 mL / s under a nitrogen atmosphere for 2 hours to obtain a pale yellow liquid.

[0061] The mixed solution (pale yellow liquid) was subjected to vacuum distillation at 160°C and 0.05-0.08 MPa under nitrogen atmosphere to remove the solvent, resulting in a viscous yellow liquid product, which is the halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant.

[0062] The chemical structure of the halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant in this embodiment is shown in Formula II.

[0063]

[0064] Figure 1 This is a photograph of the halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant prepared in this embodiment at room temperature.

[0065] Figure 2-4 The infrared spectrum, proton NMR spectrum, and phosphorus NMR spectrum of the polypropylene resin flame retardant prepared in this embodiment are shown below. Figure 2-4 This demonstrates that the method described in this embodiment successfully prepared a halogen-free phosphate-hindered piperidine ammonium salt ionic liquid flame retardant. Figure 2 It can be seen that it is located between 3100 and 2400 cm. -1 The region exhibits a significant bulge in the infrared signal, characteristic of ammonium salt compounds. (Original value: 3300 cm⁻¹) -1 The amino group signal disappears at 1071 cm. -1 The presence of a phosphate PO- anion structure signal at the ion site confirms that the obtained compound is an ammonium phosphate compound.

[0066] Depend on Figure 3The 1H-NMR spectrum of the obtained ammonium phosphate diester compound can be observed. After dissolving the compound in deuterated chloroform, only characteristic carbon atom signals of the original dibutyl phosphate and 4-amino-2,2,6,6-tetramethylpiperidine were observed; no new compound carbon atom signals were detected. This indicates that the obtained product has a simple structure and that no rearrangement, transesterification, or other side reactions occurred during the synthesis process.

[0067] Depend on Figure 4 The 31P-NMR spectrum of the obtained ammonium phosphate diester salt compound can be observed. After dissolving in deuterated chloroform, the compound exhibits only one main phosphorus signal peak, indicating that the obtained product has high purity and a simple structure, and no other phosphorus-containing byproducts are observed to form or remain.

[0068] The TGA thermogravimetric curve of the halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant prepared in this embodiment is shown in the figure below. Figure 5 ,Depend on Figure 5 It can be seen that the thermal decomposition initiation temperature of this ionic liquid is approximately 240℃, which meets the processing thermal stability requirements of common polypropylene materials below 200℃. This ionic liquid flame retardant reaches its maximum thermal decomposition temperature at 260℃, undergoing a β-elimination reaction to produce 1-n-butene as the main thermal weight loss product in the first stage. It then reaches its second thermal decomposition temperature at 300℃, undergoing a reverse ammoniation reaction to release 4-amino-2,2,6,6-tetramethylpiperidine as the main thermal weight loss product in the second stage.

[0069] Example 2

[0070] A method for preparing a halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant includes the following steps:

[0071] Place 21g of dibutyl phosphate in a three-necked flask and dissolve it in 25mL of tetrahydrofuran.

[0072] 15.6 g of 4-amino-2,2,6,6-tetramethylpiperidine was added dropwise to 75 mL of tetrahydrofuran to prepare a mixed solution, which was then transferred to a constant pressure titration funnel. The solution was heated and stirred at 60 °C, and then slowly added dropwise to a three-necked flask at a certain rate under a nitrogen atmosphere for 2 h to obtain a pale yellow liquid.

[0073] The mixed solution was subjected to vacuum distillation at 55°C and 0.05-0.08 MPa for about 3 hours in a rotary evaporator water bath to remove the solvent, resulting in a viscous yellow liquid product, which is the halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant.

[0074] Example 3

[0075] A method for preparing a halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant includes the following steps:

[0076] Place 21g of dibutyl phosphate in a three-necked flask and dissolve it in 25mL of tetrahydrofuran.

[0077] 15.6 g of 4-amino-2,2,6,6-tetramethylpiperidine was added dropwise to 75 mL of tetrahydrofuran to prepare a mixed solution, which was then transferred to a constant pressure titration funnel. The solution was heated and stirred at 60 °C, and then slowly added dropwise to a three-necked flask at a certain rate under a nitrogen atmosphere for 2 h to obtain a pale yellow liquid.

[0078] The mixed solution was subjected to vacuum distillation at 45°C and 0.05-0.08 MPa for about 3 hours in a rotary evaporator water bath to remove the solvent, resulting in a viscous yellow liquid product, which is the halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant.

[0079] The chemical structure of the halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant in this embodiment is shown in Formula II.

[0080] Example 4

[0081] A method for preparing a halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant includes the following steps:

[0082] Place 32.2 g of di(2-ethylhexyl) phosphate in a three-necked flask and dissolve it in 30 mL of cyclohexane;

[0083] 14.04 g of 4-amino-2,2,6,6-tetramethylpiperidine was added dropwise to 70 mL of cyclohexane to prepare a mixed solution, which was then transferred to a constant pressure titration funnel. The solution was heated and stirred at 60 °C, and then slowly added dropwise to a three-necked flask at a certain rate under a nitrogen atmosphere for 2 h to obtain a pale yellow liquid.

[0084] The mixed solution was subjected to vacuum distillation at 80°C and 0.08 MPa for about 1 hour in a rotary evaporator water bath to remove the solvent, resulting in a viscous yellow liquid product, which is the halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant.

[0085] The chemical structure of the halogen-free phosphate hindered piperidineamine salt ionic liquid flame retardant in this embodiment is shown in Formula III.

[0086]

[0087] Example 5

[0088] A method for preparing a halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant includes the following steps:

[0089] Place 21g of dibutyl phosphate in a three-necked flask and add 40ml of deionized water to dissolve it.

[0090] 18.7 g of 4-aminomethyl-2,2,6,6-tetramethylpiperidine was added dropwise to 30 mL of anhydrous ethanol to prepare a mixed solution, which was then transferred to a constant pressure titration funnel. The solution was heated and stirred at 60 °C, and then slowly added dropwise to a three-necked flask at a certain rate under a nitrogen atmosphere for 1 h to obtain a pale yellow liquid.

[0091] The mixed solution was subjected to vacuum distillation at 70°C and 0.05-0.08 MPa for about 3 hours in a rotary evaporator water bath to remove the solvent, resulting in a viscous yellow liquid product, which is the halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant.

[0092] Effect verification

[0093] Example 1

[0094] A method for preparing a modified polypropylene flame-retardant material includes the following steps:

[0095] 120g of polypropylene resin was placed in a Shanghai Kechuang LH300 internal mixing equipment and mixed and plasticized at 180℃ for 5 minutes. Then, 1.2g of the ionic liquid flame retardant prepared in Example 1 was added and the mixing time was 15 minutes to obtain a modified polypropylene flame retardant material containing 1% by mass of ionic liquid flame retardant with chemical structure formula II.

[0096] Example 2

[0097] A method for preparing a modified polypropylene flame-retardant material includes the following steps:

[0098] 120g of polypropylene resin was placed in a Shanghai Kechuang LH300 internal mixing equipment and mixed and plasticized at 180°C for 5 minutes. Then, 6g of the ionic liquid flame retardant prepared in Example 2 was added and the mixing time was 15 minutes to obtain a modified polypropylene flame retardant material containing 5% by mass of the ionic liquid flame retardant with chemical structure formula II.

[0099] Example 3

[0100] A method for preparing a modified polypropylene flame-retardant material includes the following steps:

[0101] 120g of polypropylene resin was placed in a Shanghai Kechuang LH300 internal mixing equipment and mixed and plasticized at 180°C for 5 minutes. Then, 12g of the ionic liquid flame retardant prepared in Example 3 was added and the mixing time was 15 minutes to obtain a modified polypropylene flame retardant material containing 10% by mass of ionic liquid flame retardant with chemical structure formula II.

[0102] Example of effect 4

[0103] 120g of polypropylene resin was placed in a Shanghai Kechuang LH300 internal mixing equipment and mixed and plasticized at 180°C for 5 minutes. Then, 6g of the ionic liquid flame retardant prepared in Example 4 was added and the mixing time was 15 minutes to obtain a modified polypropylene flame retardant material containing 5% by mass of the ionic liquid flame retardant with chemical structure formula II.

[0104] Example 5

[0105] 120g of polypropylene resin was placed in a Shanghai Kechuang LH300 internal mixing equipment and mixed and plasticized at 180°C for 5 minutes. Then, 6g of the ionic liquid flame retardant prepared in Example 5 was added and the mixing time was 15 minutes to obtain a modified polypropylene flame retardant material containing 5% by mass of the ionic liquid flame retardant with chemical structure formula II.

[0106] Comparative Example 1

[0107] 120g of polypropylene resin was placed in a Shanghai Kechuang LH300 internal mixer and mixed at 180℃ for 5 minutes without adding any plastic additives. The mixing time was then 15 minutes to obtain the polypropylene material for the blank background plate.

[0108] Comparative Example 2

[0109] 120g of polypropylene resin was placed in a Shanghai Kechuang LH300 internal mixer and plasticized at 180℃ for 5 minutes. Then, 6g of ammonium polyphosphate APP (degree of polymerization n>1000) powder flame retardant (Beyotime - brand, Y012095-500g - item number, 68333-79-9 CAS number, degree of polymerization n>1000) was added and the mixing time was 15 minutes to obtain a polypropylene material with a conventional flame retardant comparison version.

[0110] I. Flame retardant effect

[0111] The combustion performance of the polypropylene materials prepared in Examples 1-5 and Comparative Examples 1 and 2 was tested, and the results are shown in Table 1. The limiting oxygen index (LOI) was determined according to GB / T 2406.2-2009, with sample dimensions prepared according to Type I. The test was conducted using Method A – Top-Surface Ignition Method, employing an XYC series JF-5 fully automatic oxygen index analyzer, with sample dimensions of 80 × 10 × 4 mm.

[0112] Table 1 shows the properties of the polypropylene materials prepared in Examples 1-5 and Comparative Examples 1-2.

[0113]

[0114] As can be seen from the test results in Table 1, the addition of halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant can improve the limiting oxygen index of polypropylene materials to a certain extent. When the addition amount of this flame retardant reaches 5%, its flame retardant effect is similar to that of directly adding ammonium polyphosphate (APP) powder. When the addition amount reaches 10%, the LOI value of the polypropylene composite material is about 30% higher than that of pure PP material, and the LOI reaches 22.8%, which can achieve limited self-extinguishing after flame removal in atmospheric environment, so that the polypropylene material has good flame retardant performance.

[0115] II. Anti-UV Effect

[0116] The UV aging resistance of the polypropylene materials prepared in Examples 1-5 and Comparative Examples 1 and 2 was tested, and the results are shown in Table 2. Tensile strength and elongation at break were used as mechanical comparison parameters for anti-aging performance. Tensile strength testing was conducted according to GB / T 1040.1-2018, with sample size based on type 5B. A UTM-1432 universal testing machine was used to determine tensile strength and elongation at break, with a tensile speed set to 10 mm / min. Impact strength testing was performed according to GB / T 1043.1-2008, using a simply supported beam impact test. A type A single-notch specimen was used, with dimensions of 10 mm * 4 mm * 80 mm, a notch depth of 1 mm, and a remaining thickness of 9 mm. Multiple groups of samples underwent indoor UV aging tests using method C in GB / T 16422.3. Mechanical properties were tested at 0 h, 72 h, and 144 h, and the degree of change was calculated.

[0117] Table 2 shows the properties of the polypropylene materials prepared in Examples 1-5 and Comparative Examples 1-2.

[0118]

[0119] As can be seen from the test results in Table 2, the halogen-free phosphate hindered piperidinium salt ionic liquid flame retardant protects the polypropylene substrate from aging failure due to the high content of hindered amine light stabilizer groups. In contrast, traditional polyphosphate flame retardants cause chain breakage and generate more phosphate acid groups due to UV aging, which accelerates the aging of polypropylene materials. Therefore, under subsequent photo-aging conditions, the polypropylene material modified with the halogen-free phosphate hindered piperidinium salt ionic liquid flame retardant prepared in this invention can achieve a better advantage over traditional polyphosphate flame retardant-modified polypropylene materials with a smaller decrease in mechanical properties.

[0120] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A halogen-free phosphate ester hindered piperidine ammonium salt ionic liquid flame retardant, characterized in that, The general structural formula is as follows: In Equation I, R1 and R2 are independently selected from C4-C8.

2. A halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant, characterized in that, The structural formula of the halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant is: , or .

3. A method for preparing the halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant as described in claim 2, characterized in that, Includes the following steps: The halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant was prepared by solvothermal reaction of phosphate diester and 4-amino hindered piperidine ammonium as raw materials, followed by vacuum distillation. The phosphate diester is selected from either dibutyl phosphate or di(2-ethylhexyl) phosphate; The 4-aminohedralized piperidine is selected from 4-amino-2,2,6,6-tetramethylpiperidine or 4-aminomethyl-2,2,6,6-tetramethylpiperidine.

4. The method for preparing the halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant according to claim 3, characterized in that, The molar ratio of the phosphate diester to 4-aminohedrinamine is 1:0.9~1.

1.

5. The method for preparing the halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant according to claim 3, characterized in that, The specific process of the solvothermal reaction is as follows: The phosphate diester and 4-aminohedralized piperidine were dissolved in solvents respectively, mixed evenly, and heated and stirred at 60°C for 2 hours.

6. The method for preparing the halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant according to claim 5, characterized in that, The solvent is at least one of water, tetrahydrofuran, anhydrous ethanol, ethyl acetate, dichloromethane, or cyclohexane; and / or the conditions for vacuum distillation are: temperature 45-160℃, vacuum degree 0.05-0.08MPa.

7. The application of the halogen-free phosphate hindered piperidinium salt ionic liquid flame retardant as described in any one of claims 1-2 in the preparation of flame-retardant polypropylene materials.

8. A flame-retardant polypropylene material, characterized in that, apart from polypropylene resin, The raw materials also include the halogen-free phosphate hindered piperidine ammonium salt ionic liquid flame retardant as described in any one of claims 1-2; The amount of the halogen-free phosphate hindered piperidinium salt ionic liquid flame retardant added is 5-15 wt% of the polypropylene resin.

9. A method for preparing a flame-retardant polypropylene material, characterized in that, Includes the following steps: The flame-retardant polypropylene material is prepared by blending polypropylene resin after it has been melt-plasticized with the halogen-free phosphate hindered piperidinium salt ionic liquid flame retardant described in any one of claims 1-2.

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