Intumescent flame retardant, modified polylactic acid composite material and preparation method
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-04
- Publication Date
- 2026-03-06
Smart Images
Figure CN121609679A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of flame retardant technology, specifically relating to an intumescent flame retardant, a modified polylactic acid composite material, and a preparation method thereof. Background Technology
[0002] Polylactic acid (PLA) is a renewable, bio-based material widely used in packaging and other fields. However, PLA is extremely flammable, leaving almost no residue after combustion. Therefore, flame-retardant modification is needed to further expand its applications.
[0003] Flame retardant modification of polylactic acid (PLA) aims to improve its fire resistance and enhance its flame retardancy under fire conditions. Since PLA itself is highly flammable and does not possess natural flame retardant properties, it is necessary to achieve this goal by adding flame retardants or through modification. Currently, there are many methods for PLA modification, among which improving the flame retardant performance of PLA using intumescent flame retardants (IFR) is one of the research hotspots. Currently, the components of IFR are ammonium polyphosphate (APP), pentaerythritol (PER), and melamine (MEL), but when blended with polymer materials, it has the following disadvantages: (1) A large amount of flame retardant is required to obtain excellent flame retardant performance, which increases costs and reduces the mechanical properties of the material; (2) The flame retardant efficiency is low, mainly due to the "far" distance between the components in the matrix material. In other words, the components cannot react effectively during thermal degradation or reaction, resulting in low flame retardant efficiency. Summary of the Invention
[0004] The technical problem to be solved by the present invention is to provide an intumescent flame retardant, a modified polylactic acid composite material and a preparation method thereof, so as to improve the flame retardant effect and mechanical properties of the material.
[0005] This invention provides a method for preparing an intumescent flame retardant, comprising the following steps: 1) Mix cyanuric chloride, piperazine, carbonate and solvent, first control the temperature at 0-10℃ and react (preferably react for 8-12h), then raise the temperature to 50-60℃ and continue the reaction. The molar ratio of cyanuric chloride to piperazine is 1:2-2.2. After the reaction is complete, filter, wash and dry to obtain the first intermediate product. 2) Mix the first intermediate with the tris reagent (tris(hydroxymethyl)aminomethane) and an organic solvent, control the temperature at 80-90℃, and the molar ratio of cyanuric chloride to tris reagent is 1:1-1.1. After the reaction is complete, filter, wash and dry to obtain the second intermediate. 3) The second intermediate product, ammonium polyphosphate, and water are mixed. After the reaction is complete, the mixture is filtered, washed, and dried to obtain an intumescent flame retardant.
[0006] Preferably, step 1) is as follows: cyanuric chloride, piperazine, carbonate and solvent are mixed, the temperature is controlled at 0-10℃, and the molar ratio of cyanuric chloride to piperazine is 1:1-1.1; after the reaction is completed, the temperature is raised to 50-60℃, and piperazine is added, with the molar ratio of cyanuric chloride to added piperazine being 1:1-1.1; after the reaction is completed, the mixture is filtered, washed and dried to obtain the first intermediate product.
[0007] Preferably, the carbonate is potassium carbonate or sodium carbonate.
[0008] Preferably, the solvent is tetrahydrofuran.
[0009] Preferably, the molar ratio of cyanuric chloride to carbonate is 1:1.
[0010] Preferably, the organic solvent in step 2) is dichloromethane.
[0011] Preferably, in step 3), the reaction temperature is 60°C.
[0012] Preferably, in step 3), the molar ratio of ammonium polyphosphate to Tris reagent is 1:1.
[0013] Preferably, the washing process uses deionized water, and the drying temperature is 60°C.
[0014] This invention provides an intumescent flame retardant, which is prepared using the aforementioned preparation method.
[0015] This invention provides a method for preparing a modified polylactic acid composite material, which involves mixing polylactic acid and an intumescent flame retardant, melting and extruding, and molding to obtain the modified polylactic acid composite material.
[0016] This invention provides a modified polylactic acid composite material, which is prepared using the aforementioned preparation method.
[0017] The beneficial effects of this invention are that it involves reacting cyanuric chloride with piperazine and then with a Tris reagent to obtain an intermediate product rich in hydroxyl and nitrogen, which is then combined with APP to synthesize an intumescent flame retardant. The intumescent flame retardant can solve the distance problem between components, improving flame retardant efficiency. At high temperatures, the intumescent flame retardant expands to form a heat-insulating protective layer (charred layer). This charred layer effectively isolates oxygen and heat, thereby slowing flame propagation and protecting the substrate from direct ablation. This charred layer also reduces the release of harmful gases during a fire. It effectively prevents flame spread and enhances the flame retardant properties of PLA. Simultaneously, it does not significantly affect the mechanical properties of PLA, ensuring the overall strength and toughness of the material.
[0018] The reaction of cyanuric chloride with piperazine and then with Tris reagent in this application has better results than the reaction of cyanuric chloride with piperazine or Tris reagent alone. The possible reason is that the product after the reaction has moderate hydroxyl groups and viscosity, and has a better flame retardant effect. Attached Figure Description
[0019] Figure 1 The infrared spectra of MAPP, raw materials and intermediate products of the present invention are shown.
[0020] Figure 2 The images shown are SEM images and mapping images of the APP and MAPP of this invention. (a) is the SEM image of the APP at a scale of 100 μm, (b) is the SEM image of the APP at a scale of 10 μm, (c) is the mapping image of the APP, (d) is the SEM image of the MAPP at a scale of 100 μm, (e) is the SEM image of the MAPP at a scale of 10 μm, and (f) is the mapping image of the MAPP.
[0021] Figure 3 The TGA and DTG diagrams for the APP and MAPP of this invention are shown. (a) is the TGA diagram for the APP and MAPP, and (b) is the DTG diagram for the APP and MAPP.
[0022] Figure 4 The figures are the heat release and total heat release curves of PLA and its composites. (a) is the HRR (heat release curve) of PLA and its composites of the present invention. Figure 4 (b) is the total heat release (THR) of PLA and its composites. Detailed Implementation
[0023] Example 1 A method for preparing an intumescent flame retardant includes the following steps: 1) Mix 0.5 mol cyanuric chloride (CC), 1.02 mol piperazine (PIP), 0.5 mol sodium carbonate and 80 mL tetrahydrofuran (THF), and react in an ice bath (temperature 0-10℃) for 5 h. After the reaction is complete, raise the temperature to 50-60℃ and continue the reaction for 5 h. Filter, wash 3 times with deionized water, and dry at 60℃ for 12 h to obtain the first intermediate product (Mid-1). 2) Mix 0.3 mol of the first intermediate product with 0.31 mol of Tris reagent (tris(hydroxymethyl)aminomethane) and 60 mL of dichloromethane (the Tris reagent is added slowly over 1-2 hours), control the temperature at 80-90℃, and react for 8 hours. After the reaction is complete, filter, wash three times with deionized water, and dry at 60℃ for 12 hours to obtain the second intermediate product (Mid-2). 3) Mix 0.2 mol of the second intermediate product, 0.2 mol of ammonium polyphosphate (APP) and 60 mL of water (APP is added slowly over 2 hours), control the temperature at 60°C, and react for 6 hours. After the reaction is complete, filter, wash three times with deionized water, and dry at 60°C for 12 hours to obtain the intumescent flame retardant (MAPP).
[0024] Example 2 Example 2 differs from Example 1 in that step 1) is different; everything else is the same as in Example 1. Step 1) of Example 2 is as follows: Mix 0.5 mol cyanuric chloride, 0.51 mol piperazine, 0.5 mol sodium carbonate, and 80 mL tetrahydrofuran (THF), and react in an ice bath (temperature 0-10℃) for 4 h. After the reaction is complete, raise the temperature to 50-60℃ and continue to add 0.51 mol piperazine (piperazine is added slowly over 0.5-1 h). React for 6 h. After the reaction is complete, filter, wash three times with deionized water, and dry at 60℃ for 12 h to obtain the first intermediate product.
[0025] The infrared spectra of the intermediate and final products of Example 2 were measured, and the results are as follows: Figure 1 As shown. It can be seen that: 1. After the reaction of cyanuric chloride (CC) with piperazine (PIP), no NH bonds of PIP were found in the first intermediate product (1557 and 3204 cm⁻¹). -1 ), at the same time, at 840cm -1 The C-cl bond of CC can also be found at 848cm. -1 PIP CN (1264cm) -1 The key was also moved to 1256cm. -1 ; at 1535, 1487 and 1434 cm -1 The characteristic peaks of the Qin-Shaanxi ring appeared.
[0026] 2. After the Tris reagent reacted with the first intermediate, no NH2 peaks (1592, 3294, 3347) of the Tris reagent were found in the second intermediate; an OH peak (3193) of the Tris reagent was found at 3351 cm⁻¹, and a CO peak (originating from the Tris reagent, 1022 cm⁻¹) was found near 1034 cm⁻¹. -1 ); at 1535, 1487 and 1434 cm -1 The characteristic peaks of the Qinling Mountains appeared, but the intensity of the peaks varied; at 1398 cm⁻¹ -1 A newly generated CN bond was discovered. However, 840cm -1 The disappearance of the C-cl bond at that point in the second intermediate product indicates that the second step was successful.
[0027] 3. After the second intermediate reacted with APP, we found that no NH4 of APP was detected in MAPP. + Peaks (3201 and 3047) did not show the hydroxyl group of the second intermediate (3351), but -NH3 was found at 3423. + ·O - The characteristic peaks indicate that APP's NH 4+ It reacted with the hydroxyl group (derived from Tris) in the second intermediate; and the positions of bonds such as PO (1081) and P=O (1257) found by MAPP showed a blue shift relative to APP (1074-1253), but the shift was small, indicating that the hydroxyl group (derived from Tris) in the second intermediate had a weak potential effect on it, such as hydrogen bonding. The triazine ring positions were (1564, 1495, 1434).
[0028] The SEM / EDS of the APP and the final product in Example 2 were measured, and the results are as follows: Figure 2 As shown. It can be seen that: Microstructural analysis of APP revealed a smooth surface, and mapping results showed a uniform distribution of elements. In contrast, MAPP exhibited surface fragmentation, and the elemental content varied, with increased C and N compared to APP, while decreased P and O. Mapping results indicated that P and N were more uniformly dispersed within MAPP.
[0029] After tensile fracture, SEM-EDS showed that the total amount of PN was greater and the distribution was more uniform, APP had many pores, and MAPP had good compatibility and no pores.
[0030] The TGA / DTG ratios of the APP and the final product in Example 2 were measured, and the results are as follows: Figure 3 As shown. It can be seen that: Both APP and MAPP undergo thermal degradation primarily in two stages, but their thermal decomposition temperatures differ significantly. The first stage of APP (at the temperature of maximum loss rate of 360.1°C) lasts from approximately 270°C to 530°C, mainly involving the thermal decomposition of APP into NH3, H2O, and cross-linked phosphoric acid. The second stage (at the temperature of maximum loss rate of 669.9°C) begins at 530°C and continues to 770°C. This stage primarily involves the further decomposition of phosphoric acid into phosphorus oxides, ultimately resulting in a char residue of 17.1% at 800°C. Due to the premature decomposition of the surface-modified substances in MAPP (180-330°C), generating char residue to protect the overall system and prevent subsequent thermal degradation, the loss in the second stage (330-580°C) is significantly less than that of APP, and further degradation of APP is inhibited. However, in the high-temperature stage (660-800°C), the char residue of MAPP is much higher than that of pure APP, which is beneficial for improving flame retardant properties.
[0031] Comparative Example 1 A method for preparing an intumescent flame retardant includes the following steps: 1) Mix 0.5 mol cyanuric chloride, 0.51 mol piperazine, 0.5 mol sodium carbonate and 80 mL tetrahydrofuran (THF), and react in an ice bath (temperature 0-10℃) for 4 h. After the reaction is complete, raise the temperature to 50-60℃ and continue to add 1.02 mol piperazine (piperazine is added slowly over 0.5-1 h). React for 6 h. After the reaction is complete, filter, wash 3 times with deionized water, and dry at 60℃ for 12 h to obtain the first intermediate product.
[0032] 2) Mix 0.2 mol of the first intermediate product, 0.2 mol of ammonium polyphosphate (APP) and 60 mL of water (APP is added slowly over 2 hours), control the temperature at 60°C, and react for 6 hours. After the reaction is complete, filter, wash three times with deionized water, and dry at 60°C for 12 hours to obtain the intumescent flame retardant (MAPP).
[0033] Comparative Example 2 A method for preparing an intumescent flame retardant includes the following steps: 1) Mix 0.5 mol cyanuric chloride, 1.51 mol Tris reagent (tris(hydroxymethyl)aminomethane), and 100 mL dichloromethane, and react at 80-90 °C (the Tris reagent is added slowly over 1-2 h). After the reaction is complete, filter the mixture, wash it three times with deionized water, and dry it at 60 °C for 12 h to obtain the first intermediate product (Mid-1). 2) Mix 0.2 mol of the first intermediate product, 0.2 mol of ammonium polyphosphate (APP) and 60 mL of water (APP is added slowly over 2 hours), control the temperature at 60°C, and react for 6 hours. After the reaction is complete, filter, wash three times with deionized water, and dry at 60°C for 12 hours to obtain the intumescent flame retardant (MAPP).
[0034] Example 3 The preparation method of PLA / APP is as follows: 90g of polylactic acid (PLA) and 10g of ammonium polyphosphate (APP) are dried to remove moisture, and then melt-mixed at 170-200℃ through a twin-screw extruder. APP is uniformly dispersed in the PLA matrix to obtain a blend. The blend is then injection molded and cooled to obtain the PLA / APP composite material.
[0035] The preparation method of PLA / IFR is as follows: 90g of polylactic acid (PLA) and 10g of IFR (IFR is composed of ammonium polyphosphate and pentaerythritol in a mass ratio of 2:1) are dried to remove moisture, and then melt-mixed at 170-200℃ through a twin-screw extruder. APP is uniformly dispersed in the PLA matrix to obtain a blend. The blend is then injection molded and cooled to obtain the PLA / IFR composite material.
[0036] The preparation method of PLA / MAPP is as follows: 90g of polylactic acid (PLA) and 10g of MAPP from Example 2 are dried to remove moisture, and then melt-mixed at 170-200℃ through a twin-screw extruder. APP is uniformly dispersed in the PLA matrix to obtain a blend. The blend is then injection molded and cooled to obtain the PLA / MAPP composite material.
[0037] The heat release curves and total heat release of PLA, PLA / APP, PLA / IFR, and PLA / MAPP were measured, and the results are as follows: Figure 4 As shown.
[0038] from Figure 4 (a) It can be seen that the peak heat release (pHRR) of pure PLA is 831.5 kW / m 2 When 10 wt% APP was introduced, the pHRR of PLA / APP was 714.7 kW / m³. 2 The decrease was 14%; when 10 wt% of the conventional intumescent flame retardant IFR (APP and PER in a mass ratio of 3:1) was introduced, the pHRR of PLA / IFR was 689.4 kW / m³. 2 The decrease was 17.1%; when 10 wt% MAPP was introduced, the pHRR of PLA / IFR was 551.9 kW / m 2 The decrease was 33.6%, and the curve showed two distinct peaks, indicating that a high-quality carbon layer was formed in the early stage to resist high temperatures. Only when the high temperature continued to rise did the residual carbon break down, resulting in the second peak. The curve also showed that MAPP was more effective than APP and the traditional IFR. Its relative total heat release value ( Figure 4 (b) is the same.
[0039] Example 4 The limiting oxygen index (LOI) of PLA, PLA / APP, and PLA / MAPP was determined according to the test method published in GB / T2406-1993 "Test Method for Burning Performance of Plastics - Oxygen Index Method". We found that the limiting oxygen index (LOI) of pure PLA was 19.5%. When 10 wt% APP was added to the PLA matrix, the LOI increased to 27.0%; when 10 wt% MAPP from Example 2 was added to the PLA matrix, the LOI increased to 33.0%; when 10 wt% MAPP from Comparative Example 1 was added to the PLA matrix, the LOI was 27.2%; and when 10 wt% MAPP from Comparative Example 2 was added to the PLA matrix, the LOI was 27.9%.
[0040] Example 5 The mechanical properties of PLA, PLA / APP, PLA / IFR, and PLA / MAPP were determined according to the test methods published in GB / T1040-2006 "Determination of Tensile Properties of Plastics". The results are shown in Table 1.
[0041] Table 1 Product Mechanical Properties
[0042] As can be seen, the PLA / MAPP of this application has significantly higher tensile strength and elongation at break.
[0043] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of protection of this application is limited to these examples; within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of one or more embodiments of this application as described above, which are not provided in detail for the sake of brevity.
[0044] One or more embodiments in this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of this application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments in this application should be included within the protection scope of this application.
Claims
1. A method for producing an intumescent flame retardant, characterized by, The preparation method comprises the following steps: 1) mixing cyanuric chloride, piperazine, carbonate and solvent, controlling the temperature at 0-10 ℃, then increasing the temperature to 50-60 ℃, and continuing the reaction, the molar ratio of cyanuric chloride to piperazine being 1:2-2.2, after the reaction is completed, filtering, washing and drying to obtain a first intermediate product; 2) mixing the first intermediate product, tris reagent and organic solvent, controlling the temperature at 80-90 ℃, the molar ratio of cyanuric chloride to tris reagent being 1:1-1.1, after the reaction is completed, filtering, washing and drying to obtain a second intermediate product; 3) mixing the second intermediate product, ammonium polyphosphate and water, after the reaction is completed, filtering, washing and drying to obtain the intumescent flame retardant.
2. The production method according to claim 1, wherein Step 1) is: mixing cyanuric chloride, piperazine, carbonate and solvent, controlling the temperature at 0-10 ℃, the molar ratio of cyanuric chloride to piperazine being 1:1-1.1; after the reaction is completed, increasing the temperature to 50-60 ℃, continuing to add piperazine, the molar ratio of cyanuric chloride to the added piperazine being 1:1-1.1, after the reaction is completed, filtering, washing and drying to obtain the first intermediate product.
3. The production method according to claim 1 or 2, wherein In step 1), the carbonate is potassium carbonate or sodium carbonate, and the solvent is tetrahydrofuran.
4. The production method according to claim 1, wherein In step 1), the molar ratio of cyanuric chloride to carbonate is 1:
1.
5. The production method according to claim 1, wherein In step 2), the organic solvent is dichloromethane.
6. The production method according to claim 1, wherein In step 3), the reaction temperature is 60 ℃, and the molar ratio of ammonium polyphosphate to tris reagent is 1:
1.
7. The production method according to claim 1, wherein The washing is performed by using deionized water, and the drying temperature is 60 ℃.
8. An intumescent flame retardant characterized by, The intumescent flame retardant is prepared by using the preparation method in any one of claims 1-7.
9. A method for producing a modified polylactic acid composite material, characterized by, The polylactic acid and the intumescent flame retardant in claim 8 are mixed, melt-extruded, and molded to obtain a modified polylactic acid composite material.
10. A modified polylactic acid composite, characterized by, The modified polylactic acid composite material is prepared by using the preparation method in claim 9.