Phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid, polylactic acid composite material and preparation method
PLA is modified with ellagic acid and a phosphorus-silicon-nitrogen synergistic flame retardant to form a highly efficient expanded char layer, which solves the flammability problem of PLA, improves its flame retardant and mechanical properties, and provides UV resistance, making it suitable for applications in the fields of electronics, electrical appliances, and automotive interiors.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JIAXING UNIV
- Filing Date
- 2026-01-14
- Publication Date
- 2026-04-21
AI Technical Summary
Polylactic acid (PLA) is flammable and melts and drips during combustion. Existing flame retardants have a large impact on mechanical properties when added in large quantities. Furthermore, traditional flame retardants are not compatible with bio-based properties and have problems with migration and moisture absorption.
Ellagic acid was used as the core carbon source and phosphorus-silicon-nitrogen synergistic flame retardant to prepare polylactic acid composite materials through melt blending process, forming a high-quality expanded carbon layer to enhance flame retardant and mechanical properties.
It achieves UL-94 V-0 flame retardant performance with low additive levels, increases the limiting oxygen index to over 30%, improves tensile strength and impact toughness, has UV resistance, and meets sustainable development requirements.
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Figure CN121895367A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of flame retardant polymer technology, specifically to a phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid, a polylactic acid composite material, and a preparation method thereof. Background Technology
[0002] Polylactic acid (PLA) is an important biodegradable bio-based polymer material derived from renewable plant resources such as corn and cassava, and is widely used in packaging, fibers, and disposable products. However, PLA has a low limiting oxygen index (approximately 20%), is highly flammable, and produces significant molten dripping during combustion, posing a substantial fire hazard and severely limiting its application in fields with high flame-retardant requirements, such as electronics and automotive interiors. Therefore, flame-retardant modification of PLA has become a key technological challenge in expanding its application scope.
[0003] Currently, the most commonly used flame retardants for PLA flame retardant modification include metal oxide flame retardants, phosphorus-based flame retardants, and nitrogen-based flame retardants. However, in practical applications, metal oxide flame retardants often need to be added at a concentration of 50%-60% or more to achieve a flame retardant effect, which severely degrades the mechanical strength and processing performance of PLA. Although phosphorus-nitrogen synergistic flame retardant systems, such as ammonium polyphosphate / melamine systems, can effectively improve the flame retardant efficiency of PLA, their components are mainly derived from petrochemical products, which are incompatible with the bio-based characteristics of PLA and have problems such as easy migration and moisture absorption. In recent years, the development of natural bio-based flame retardants has become a research hotspot. For example, genistein and resveratrol have been explored for polymer flame retardancy. The molecular structure of bio-based flame retardants is similar to that of bio-based plastics such as PLA, resulting in better interfacial compatibility. In addition, biomass materials are derived from plants, animal chitin, or microorganisms, and are renewable biomass resources that replace non-renewable petroleum, conforming to the concepts of green chemistry and sustainable development.
[0004] Ellagic acid is a natural polyphenolic dicarboxylic acid widely found in various soft fruits, nuts, and other plant tissues. Its molecular structure serves as an ideal carbon and acid source, making it possible to construct highly efficient intumescent flame-retardant systems. More importantly, its molecular structure contains abundant phenolic hydroxyl groups, which can be molecularly designed with suitable phosphorus, nitrogen, and silicon sources to construct a novel, bio-based phosphorus-nitrogen-silicon synergistic flame-retardant system, and used to prepare high-performance flame-retardant polylactic acid composite materials.
[0005] Therefore, this application provides a phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid, a polylactic acid composite material, and a preparation method thereof. Summary of the Invention
[0006] The purpose of this invention is to provide a phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid, a polylactic acid composite material, and a preparation method thereof, which aims to improve the flame retardant properties of PLA while maintaining the good mechanical properties of PLA.
[0007] To solve the above-mentioned technical problems, the objective of this invention is achieved as follows: a phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid, with the following structural formula: , Wherein, the R1 group is selected from hydrogen, C1-C20 alkyl, C1-C20 aryl, C1-C20 alkoxy or C1-C20 aryloxy; the R2 group is selected from C1-C20 alkyl; and the R3 and R4 groups are selected from C1-C20 alkyl, C1-C20 alkoxy, C6-C20 aryl or C6-C20 aryloxy.
[0008] A method for preparing a phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid includes the following steps: Step 1: Dissolve 50 parts of dichlorophosphate and 30 parts of potassium carbonate in 100 ml of tetrahydrofuran by molar ratio, then add 50 parts of silane coupling agent dropwise. The reaction is maintained at reflux temperature of 60°C for 24 hours. Filter to remove solvent, and then place the product in a vacuum drying oven at 60°C for 6 hours. Step 2: By mass, place 10 parts of ellagic acid in a mixture of water and tetrahydrofuran in a 1:4 ratio, then add 50-80 parts of the product from the previous step, and react at reflux temperature of 60°C for 48 hours. Pour the solution into deionized water to stop the reaction, centrifuge to obtain the product, wash three times with deionized water, and then place the product in a vacuum drying oven at 60°C for 12 hours.
[0009] Based on the above scheme and as a preferred embodiment of the above scheme: the dichlorophosphate is diphenyl chlorophosphate, and the silane coupling agent is an aminoalkylsilane.
[0010] A polylactic acid composite material prepared using a phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid, comprising: 90-99.9 parts by weight of polylactic acid resin granules and 10-0.1 parts by weight of the phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid as described in claim 1.
[0011] A method for preparing polylactic acid composite material using a phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid, characterized in that the polylactic acid resin granules and the phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid as described in claim 1 are melt-blended at 180-200°C, then extruded and granulated in an extruder, and finally dried.
[0012] The beneficial effects of this invention are: compared with the prior art, the phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid, the polylactic acid composite material, and the preparation method of this invention are as follows: (1) This invention uses the natural polyphenol compound ellagic acid as the core carbon source and char-forming agent, and combines it with a self-designed phosphorus-silicon-nitrogen synergistic flame retardant intermediate at the molecular level to successfully construct a novel semi-bio-based intumescent flame retardant system; its core components are derived from renewable resources and are highly compatible with the biodegradable properties of PLA, realizing the greening of the entire life cycle from raw materials to finished products, which is in line with the "dual carbon" strategy and the requirements of sustainable development. (2) The flame retardant synthesis route of the present invention is mature and reliable, and the conditions are mild. When applied to PLA modification, it adopts conventional melt blending process, without the need for complex equipment modification or harsh process conditions. The production process is simple and the cost is controllable, which is very suitable for large-scale industrial production and provides a practical solution for developing high-performance green flame retardant PLA products. (3) This invention ingeniously integrates phosphorus (acid source, gas source), nitrogen (gas source), carbon (charring agent) and silicon into one unit. During combustion, ellagic acid rapidly dehydrates and crosslinks under the catalysis of the phosphorus source, forming a high-quality expanded char layer; the nitrogen source decomposes upon heating to release inert gas, causing the char layer to expand and foam; while silicon plays a synergistic flame-retardant role in both the gas phase and the condensed phase, and can significantly enhance the strength, density and thermal stability of the char layer. This synergistic effect of multiple elements and multiple phases enables the flame-retardant system to achieve the UL-94 V-0 level for PLA composite materials with a relatively low addition amount, and the limiting oxygen index is significantly increased to over 30%. (4) Compared with polylactic acid materials with the same amount of traditional flame retardant, the composite material prepared by the present invention can not only obtain excellent flame retardant performance, but also effectively improve its key mechanical properties such as tensile strength and impact toughness, thus avoiding excessive embrittlement of the material due to flame retardant modification. (5) Ellagic acid molecules themselves have excellent UV resistance. Introducing them into the flame retardant system allows the modified polylactic acid composite material to not only have high flame retardant performance, but also to acquire inherent UV resistance, which helps to extend the service life of the product. This is a unique advantage that traditional flame retardants do not have. Attached Figure Description
[0013] Figure 1 The diagram illustrates the reaction equation of the phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid involved in this invention. Figure 2 This is the 1H NMR spectrum of the phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid involved in this invention. Detailed Implementation
[0014] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.
[0015] Example 1 A method for preparing a phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid includes the following steps: Step 1: Dissolve 50 parts of diphenyl chlorophosphate and 30 parts of potassium carbonate in 100 ml of tetrahydrofuran by molar ratio, then add 50 parts of KH550 silane coupling agent dropwise. The reaction is maintained at reflux temperature of 60°C for 24 hours. After filtration to remove the solvent, the product is placed in a vacuum drying oven and dried at 60°C for 6 hours. Step 2: By mass, 10 parts of ellagic acid were placed in a mixture of water and tetrahydrofuran in a 1:4 ratio, and then 60 parts of the product from the previous step were added. The mixture was then reacted at reflux temperature of 60°C for 48 hours. The solution was poured into deionized water to stop the reaction. The product was centrifuged to obtain the phosphorus-nitrogen-silicon synergistic flame retardant EGP based on ellagic acid. The product was washed three times with deionized water and then dried in a vacuum drying oven at 60°C for 12 hours.
[0016] Figure 2 The two sets of multiplets at 0.7 ppm and 2.7 ppm correspond to the peaks of the ethoxy group directly bonded to the silicon atom; the three sets of multiplets at 2.9, 1.7 and 1.6 ppm correspond to the three CH2 peaks of the propyl group on the silane coupling agent, with the peak at 2.9 ppm being the CH2 peak bonded to the nitrogen atom and the peak at 1.6 being the CH2 peak bonded to the silicon atom.
[0017] Example 2 A polylactic acid composite material C1 prepared using a phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid is made from 99.5g of polylactic acid resin granules and 0.5g of the phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid from Example 1.
[0018] A method for preparing polylactic acid composite material using a phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid is as follows: 99.5g of pure polylactic acid and 0.5g of the phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid from Example 1 are added to a high-speed mixer and initially mixed at 300rpm / min for 5min to obtain a premix. The premix is then extruded and granulated in an extruder at 190℃, and finally dried to obtain polylactic acid composite material C1 granules.
[0019] Example 3 The difference from Example 2 is that a polylactic acid composite material C2 prepared using a phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid is made from 99g of polylactic acid resin granules and 1g of the phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid in Example 1.
[0020] Example 4 The difference from Example 2 is that the polylactic acid composite material C3 prepared using a phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid is made from 98g of polylactic acid resin granules and 2g of the phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid in Example 1.
[0021] Example 5 The difference from Example 2 is that the polylactic acid composite material C4 prepared using a phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid is made from 97g of polylactic acid resin granules and 3g of the phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid in Example 1.
[0022] Example 6 The difference from Example 2 is that a polylactic acid composite material C5 prepared using a phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid is made from 95g of polylactic acid resin granules and 5g of the phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid in Example 1.
[0023] Comparative Example 1 100g of pure polylactic acid was extruded and granulated in an extruder at 190℃, and finally dried to obtain pure polylactic acid granules, which served as control sample 1.
[0024] Comparative Example 2 95g of polylactic acid pure material and 5g of traditional flame retardant ammonium polyphosphate were extruded and granulated in an extruder at 190℃, and finally dried to obtain control sample 2.
[0025] The polylactic acid raw materials used in the above embodiments and comparative examples were all NatureWorks, No. 4032D.
[0026] Performance testing: 1. Flame retardant performance evaluation: Polylactic acid composite materials C1, C2, C3, C4, C5, control sample 1, and control sample 2 were thoroughly dried and then injection molded at 190℃ to prepare sample strips (125mm*13mm*1.6mm) for flame retardant performance evaluation. Based on UL (Underwriters Laboratories)-94 (standard shown in Table 1), a 20mm vertical burning test was conducted on the sample strips, and the burning test results are shown in Table 2. 2. Limiting Oxygen Index Evaluation: Polylactic acid composite materials C1, C2, C3, C4, C5, control sample 1, and control sample 2 were thoroughly dried and then injection molded at 190℃ to prepare test strips (100mm*6.5mm*3mm) for limiting oxygen index (LOI) evaluation. The LOI values were tested using an oxygen index meter, and the LOI values are shown in Table 2. 3. Mechanical property evaluation: Polylactic acid composite materials C1, C2, C3, C4, C5, control sample 1, and control sample 2 were injection molded at 190℃ to obtain tensile standard test specimens and standard impact test specimens with automatically generated notches. The tensile properties were then tested using a 5569 Instron universal tensile testing machine according to the national standard GB / T1040.2-2006, and the impact strength was tested using a JXUD5.5 pendulum impact tester according to the national standard GB / T1843-2008. The mechanical property test results are shown in Table 3.
[0027] 4. Evaluation of UV resistance performance Polylactic acid composite material C5 and control samples 1 and 2 were hot-pressed at 190℃ to obtain samples 30×30×0.3mm. 3 The sample thin films were then tested using a UV / Vis spectrophotometer (Lambda 365, PerkinElmer) in the 200-800 nm wavelength range. The transmittance test results are shown in Table 4.
[0028] Table 1 Flame retardancy test UL-94 standard Table 2. Sample combustion test results and LOI values Table 3 Test results of mechanical properties of the specimens Table 4. Test results of UV / Vis spectrophotometer The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.
Claims
1. A phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid, characterized in that, The structural formula is: ， Wherein, the R1 group is selected from hydrogen, C1-C20 alkyl, C1-C20 aryl, C1-C20 alkoxy or C1-C20 aryloxy; the R2 group is selected from C1-C20 alkyl; and the R3 and R4 groups are selected from C1-C20 alkyl, C1-C20 alkoxy, C6-C20 aryl or C6-C20 aryloxy.
2. A method for preparing a phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid as described in claim 1, characterized in that, Includes the following steps: Step 1: Dissolve 50 parts of dichlorophosphate and 30 parts of potassium carbonate in 100 ml of tetrahydrofuran by molar ratio, then add 50 parts of silane coupling agent dropwise. The reaction is maintained at reflux temperature of 60°C for 24 hours. Filter to remove solvent, and then place the product in a vacuum drying oven at 60°C for 6 hours. Step 2: By mass, place 10 parts of ellagic acid in a mixture of water and tetrahydrofuran in a 1:4 ratio, then add 50-80 parts of the product from the previous step, and react at reflux temperature of 60°C for 48 hours. Pour the solution into deionized water to stop the reaction, centrifuge to obtain the product, wash three times with deionized water, and then place the product in a vacuum drying oven at 60°C for 12 hours.
3. The preparation method of the phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid according to claim 2, characterized in that, The dichlorophosphate is diphenyl chlorophosphate, and the silane coupling agent is KH550 silane coupling agent.
4. A polylactic acid composite material prepared using a phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid, characterized in that, include: By weight, 90-99.9 parts of polylactic acid resin granules and 10-0.1 parts of the ellagic acid-based phosphorus-nitrogen-silicon synergistic flame retardant as described in claim 1.
5. A method for preparing polylactic acid composite material using a phosphorus-nitrogen-silicon synergistic flame retardant based on ellagic acid as described in claim 4, characterized in that, The polylactic acid resin granules and the ellagic acid-based phosphorus-nitrogen-silicon synergistic flame retardant of claim 1 are melt-blended at 180-200°C, then extruded and granulated in an extruder, and finally dried.