Flame-retardant polylactic acid composite material, preparation method and application thereof

Abstract

This invention provides a flame-retardant polylactic acid (PLA) composite material, its preparation method, and its application, belonging to the technical field of flame-retardant composite materials. The flame-retardant PLA composite material provided by this invention, by weight, comprises the following components: 100 parts PLA, 5-8 parts phosphorus-containing flame retardant, 1-3 parts graphene oxide, 0.5-5 parts hexagonal boron nitride, 2-6 parts montmorillonite, 0.1-0.6 parts antioxidant, and 1-10 parts plasticizer; the particle size of the hexagonal boron nitride is 1-10 μm; the particle size of the montmorillonite is <1 μm. This invention controls the composition of each component to construct a multi-layered defense system, significantly improving the flame-retardant properties of PLA.

Description

Technical Field

[0001] This invention belongs to the field of flame-retardant composite material technology, specifically relating to a flame-retardant polylactic acid composite material, its preparation method, and its application. Background Technology

[0002] Polylactic acid (PLA) is biodegradable, with degradation products being carbon dioxide and water, which do not pollute the environment. It also possesses excellent mechanical and processability properties, making it promising for applications in the packaging industry. However, PLA's flame retardancy is poor, limiting its application in certain areas. Current technologies typically involve adding phosphorus-based or phosphorus-nitrogen-based flame retardants to improve PLA's flame retardancy, but further improvements are needed. Summary of the Invention

[0003] The purpose of this invention is to provide a flame-retardant polylactic acid (PLA) composite material, its preparation method, and its applications. The PLA provided by this invention exhibits excellent flame-retardant properties.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a flame-retardant polylactic acid composite material, comprising the following components by weight: 100 parts polylactic acid, 5-8 parts phosphorus-containing flame retardant, 1-3 parts graphene oxide, 0.5-5 parts hexagonal boron nitride, 2-6 parts montmorillonite, 0.1-0.6 parts antioxidant, and 1-10 parts plasticizer; wherein the particle size of the hexagonal boron nitride is 1-10 μm; and the particle size of the montmorillonite is <1 μm.

[0005] Preferably, by weight, it comprises the following components: 100 parts polylactic acid, 6-8 parts phosphorus-containing flame retardant, 2-3 parts graphene oxide, 1-5 parts hexagonal boron nitride, 2-6 parts montmorillonite, 0.1-0.6 parts antioxidant, and 1-10 parts plasticizer.

[0006] Preferably, the phosphorus-containing flame retardant includes one or more of ammonium polyphosphate, triphenyl phosphate, melamine polyphosphate, and melamine orthophosphate.

[0007] Preferably, the graphene oxide has a particle size of 0.5~20μm.

[0008] Preferably, the antioxidant includes one or more of antioxidant 1010, antioxidant 168, and tert-butylhydroquinone.

[0009] Preferably, the antioxidant is antioxidant 1010 and antioxidant 168.

[0010] Preferably, the mass ratio of antioxidant 1010 to antioxidant 168 is (2~4):1.

[0011] Preferably, the plasticizer includes one or more of dioctyl phthalate, tributyl citrate, polyethylene glycol, and polypropylene glycol.

[0012] The present invention also provides a method for preparing the flame-retardant polylactic acid composite material described in the above technical solution, comprising: mixing polylactic acid, phosphorus-containing flame retardant, graphene oxide, hexagonal boron nitride, montmorillonite, antioxidant and plasticizer, and performing melt extrusion to obtain the flame-retardant polylactic acid composite material.

[0013] The present invention also provides the application of the flame-retardant polylactic acid composite material described in the above technical solution or the flame-retardant polylactic acid composite material prepared by the preparation method described in the above technical solution in candle containers.

[0014] This invention provides a flame-retardant polylactic acid composite material, comprising the following components by weight: 100 parts polylactic acid, 5-8 parts phosphorus-containing flame retardant, 1-3 parts graphene oxide, 0.5-5 parts hexagonal boron nitride, 2-6 parts montmorillonite, 0.1-0.6 parts antioxidant, and 1-10 parts plasticizer; the particle size of the hexagonal boron nitride is 1-10 μm; the particle size of the montmorillonite is <1 μm. The phosphorus-containing flame retardant in this composite material generates phosphoric acid during combustion, and metaphosphoric acid at higher temperatures, causing polylactic acid to dehydrate and carbonize, preventing the generation of flammable gases. Simultaneously, the formation of a coke layer can block the contact between flammable gases and the flame, preventing further combustion of the material. Graphene oxide has a huge specific surface area and extremely high aspect ratio, enabling it to form a dense film layer on the material surface, blocking the transfer of heat and flammable gases. It also serves as a skeleton for the carbon layer, improving the strength and continuity of the carbon layer, further enhancing the flame-retardant performance; hexagonal boron nitride also... It is a layered material with extremely high thermal stability and oxidation resistance. It maintains its layered structure even in the later stages of combustion, improving flame retardant performance. Furthermore, hexagonal boron nitride has excellent thermal conductivity, dispersing heat and preventing localized overheating. Montmorillonite is also a layered material. By controlling the particle size of montmorillonite and hexagonal boron nitride, smaller particle sizes of montmorillonite can fill the interlayer gaps formed by the hexagonal boron nitride, improving the density of the protective layer and thus enhancing flame retardant performance. This invention controls the composition of each component to construct a multi-layered defense system, significantly improving the flame retardant performance of polylactic acid. The results of the embodiments show that the polylactic acid composite material provided by this invention can achieve an oxygen index of 35.1 and a vertical burning rating of V-0. Detailed Implementation

[0015] This invention provides a flame-retardant polylactic acid composite material, comprising the following components by weight: 100 parts polylactic acid, 5-8 parts phosphorus-containing flame retardant, 1-3 parts graphene oxide, 0.5-5 parts hexagonal boron nitride, 2-6 parts montmorillonite, 0.1-0.6 parts antioxidant, and 1-10 parts plasticizer; wherein the particle size of the hexagonal boron nitride is 1-10 μm; and the particle size of the montmorillonite is <1 μm.

[0016] Unless otherwise specified, the present invention does not have any special limitations on the source of each component, and commercially available products well known to those skilled in the art can be used.

[0017] The flame-retardant polylactic acid composite material provided by the present invention comprises 100 parts by weight of polylactic acid. In the present invention, the polylactic acid is the matrix material.

[0018] Based on 100 parts by weight of polylactic acid, the flame-retardant polylactic acid composite material provided by the present invention further includes 5 to 8 parts of a phosphorus-containing flame retardant. As one embodiment, the amount of the phosphorus-containing flame retardant can specifically be 5, 6, 7, or 8 parts.

[0019] In this invention, the phosphorus-containing flame retardant preferably includes one or more of ammonium polyphosphate, triphenyl phosphate, melamine polyphosphate, and melamine orthophosphate.

[0020] In this invention, the phosphorus-containing flame retardant generates phosphoric acid during combustion, and metaphosphoric acid at higher temperatures, causing polylactic acid to dehydrate and carbonize, thus preventing the generation of flammable gases. Simultaneously, the formation of a coke layer can block the contact between flammable gases and the flame, preventing further combustion of the material. This invention controls the type and amount of phosphorus-containing flame retardant within the aforementioned range, further improving the flame-retardant properties of the composite material.

[0021] Based on 100 parts by weight of polylactic acid, the flame-retardant polylactic acid composite material provided by the present invention further includes 1 to 3 parts of graphene oxide. As one embodiment, the amount of graphene oxide may specifically be 1 part, 2 parts, or 3 parts.

[0022] In this invention, the preferred particle size of the graphene oxide is 0.5~20μm.

[0023] In this invention, the graphene oxide possesses a large specific surface area and an extremely high aspect ratio, enabling it to form a dense film layer on the material surface. This film layer blocks the transfer of heat and combustible gases, while also serving as a framework for the carbon layer, improving its strength and continuity, thereby enhancing its flame-retardant properties. By controlling the particle size and dosage of graphene oxide within the aforementioned range, this invention further improves the flame-retardant properties of the composite material.

[0024] Based on 100 parts by weight of polylactic acid, the flame-retardant polylactic acid composite material provided by the present invention further includes 0.5 to 5 parts of hexagonal boron nitride. As one embodiment, the amount of hexagonal boron nitride can specifically be 0.5 parts, 1 part, 2 parts, 3 parts, 4 parts, or 5 parts.

[0025] In this invention, the particle size of the hexagonal boron nitride is 1~10 μm.

[0026] In this invention, the hexagonal boron nitride is a layered material with extremely high thermal stability and oxidation resistance. It maintains its layered structure even in the later stages of combustion, improving flame retardant performance. Furthermore, hexagonal boron nitride has excellent thermal conductivity, which disperses heat and prevents localized overheating. By controlling the particle size and dosage of hexagonal boron nitride within the aforementioned range, this invention further enhances the flame retardant properties of the composite material.

[0027] Based on 100 parts by weight of polylactic acid, the flame-retardant polylactic acid composite material provided by the present invention further includes 2 to 6 parts of montmorillonite. As one embodiment, the amount of montmorillonite can be specifically 2, 3, 4, 5, or 6 parts.

[0028] In this invention, the particle size of the montmorillonite is <1 μm.

[0029] In this invention, the montmorillonite is a layered material. By controlling the particle size of the montmorillonite and hexagonal boron nitride, a combination of large-particle-size hexagonal boron nitride with excellent thermal stability and small-particle-size montmorillonite is used. The small-particle-size montmorillonite can fill the interlayer gaps formed by the hexagonal boron nitride, improving the density of the protective layer and thus enhancing the flame retardant performance. This invention, by controlling the particle size and dosage of montmorillonite, can further improve the flame retardant performance of the composite material.

[0030] Based on 100 parts by weight of polylactic acid, the flame-retardant polylactic acid composite material provided by the present invention further includes 0.1 to 0.6 parts of antioxidant. As one embodiment, the amount of antioxidant may specifically be 0.1, 0.2, 0.3, 0.4, 0.5, or 0.6 parts.

[0031] In this invention, the antioxidant preferably includes one or more of antioxidant 1010, antioxidant 168 and tert-butylhydroquinone, more preferably antioxidant 1010 and antioxidant 168.

[0032] In this invention, when the antioxidants are antioxidant 1010 and antioxidant 168, the preferred mass ratio of antioxidant 1010 to antioxidant 168 is (2~4):1. As one embodiment, the mass ratio of antioxidant 1010 to antioxidant 168 can specifically be 2:1, 3:1, or 4:1. By controlling the type and amount of antioxidants within the above range, this invention can further improve the antioxidant properties of the composite material.

[0033] Based on 100 parts by weight of polylactic acid, the flame-retardant polylactic acid composite material provided by the present invention further includes 1 to 10 parts of plasticizer. As one embodiment, the amount of plasticizer may be 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, or 10 parts.

[0034] In this invention, the plasticizer preferably includes one or more of dioctyl phthalate, tributyl citrate, polyethylene glycol, and polypropylene glycol. This invention controls the type and amount of plasticizer to further improve the flexibility and processability of the composite material.

[0035] This invention controls the composition of each component in the composite material to construct a multi-layer defense system, significantly improving the flame retardant properties of polylactic acid.

[0036] The present invention also provides a method for preparing the flame-retardant polylactic acid composite material described in the above technical solution, comprising: mixing polylactic acid, phosphorus-containing flame retardant, graphene oxide, hexagonal boron nitride, montmorillonite, antioxidant and plasticizer, and performing melt extrusion to obtain the flame-retardant polylactic acid composite material.

[0037] The present invention does not have any special limitations on the melt extrusion operation, and the melt extrusion technology of polylactic acid composite materials well known to those skilled in the art can be used.

[0038] In one embodiment, the temperature of the melt extrusion can be 170°C, 175°C, 180°C, 185°C, 190°C, or 195°C.

[0039] The present invention also provides the application of the flame-retardant polylactic acid composite material described in the above technical solution or the flame-retardant polylactic acid composite material prepared by the preparation method described in the above technical solution in candle containers.

[0040] The polylactic acid composite material provided by this invention has excellent flame retardant properties, and therefore can be used as a candle container.

[0041] The present invention does not impose any special limitations on the operation of the application, and any technical solution known to those skilled in the art can be used.

[0042] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0043] Example 1 A flame-retardant polylactic acid composite material, by weight, comprises the following components: 100 parts polylactic acid, 5 parts ammonium polyphosphate, 1 part graphene oxide (particle size 0.5~20μm), 0.5 parts hexagonal boron nitride (particle size 1~10μm), 2 parts montmorillonite (particle size <1μm), 0.4 parts antioxidant (antioxidant 1010 and antioxidant 168 in a mass ratio of 3:1), and 5 parts tributyl citrate; The flame-retardant polylactic acid composite material is prepared by mixing polylactic acid, ammonium polyphosphate, graphene oxide, hexagonal boron nitride, montmorillonite, antioxidant and tributyl citrate, and then performing melt extrusion at 185°C to obtain the flame-retardant polylactic acid composite material.

[0044] Example 2 A flame-retardant polylactic acid composite material, by weight, is composed of the following components: 100 parts polylactic acid, 6 parts ammonium polyphosphate, 2 parts graphene oxide (particle size 0.5~20μm), 2 parts hexagonal boron nitride (particle size 1~10μm), 3 parts montmorillonite (particle size <1μm), 0.4 parts antioxidant (antioxidant 1010 and antioxidant 168 in a mass ratio of 3:1), and 5 parts tributyl citrate; The preparation method of the flame-retardant polylactic acid composite material is the same as in Example 1.

[0045] Example 3 A flame-retardant polylactic acid composite material, by weight, is composed of the following components: 100 parts polylactic acid, 6 parts ammonium polyphosphate, 3 parts graphene oxide (particle size 0.5~20μm), 3 parts hexagonal boron nitride (particle size 1~10μm), 4 parts montmorillonite (particle size <1μm), 0.4 parts antioxidant (antioxidant 1010 and antioxidant 168 in a mass ratio of 3:1), and 5 parts tributyl citrate; The preparation method of the flame-retardant polylactic acid composite material is the same as in Example 1.

[0046] Comparative Example 1 In Example 3, the graphene oxide was omitted, the amount of hexagonal boron nitride was changed to 6 parts, and all other parameters were the same as in Example 1.

[0047] Comparative Example 2 In Example 3, hexagonal boron nitride was omitted, and the amount of graphene oxide was changed to 6 parts. All other parameters were the same as in Example 1.

[0048] Comparative Example 3 In Example 3, montmorillonite was omitted, and the amount of graphene oxide was changed to 7 parts. All other parameters were the same as in Example 1.

[0049] Comparative Example 4 The particle size of montmorillonite in Example 3 was modified to 1~10μm, while other parameters were the same as in Example 1.

[0050] Comparative Example 5 In Example 3, the particle size of montmorillonite was modified to 1~10μm, the particle size of hexagonal boron nitride was modified to <1μm, and other parameters were the same as in Example 1.

[0051] The oxygen index and vertical burning rating of the composite materials in Examples 1-3 and Comparative Examples 1-5 were tested, and the results are shown in Table 1.

[0052] Table 1. Oxygen index and vertical combustion rating of the composite materials in Examples 1-3 and Comparative Examples 1-5.

[0053] As can be seen from the data in Table 1, the polylactic acid composite material provided by the present invention has better flame retardant properties.

[0054] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A flame-retardant polylactic acid composite material, comprising the following components by weight: 100 parts polylactic acid, 5-8 parts phosphorus-containing flame retardant, 1-3 parts graphene oxide, 0.5-5 parts hexagonal boron nitride, 2-6 parts montmorillonite, 0.1-0.6 parts antioxidant, and 1-10 parts plasticizer; wherein the particle size of the hexagonal boron nitride is 1-10 μm; and the particle size of the montmorillonite is <1 μm.

2. The flame retardant polylactic acid composite according to claim 1, characterized in that, By weight, it includes the following components: 100 parts polylactic acid, 6-8 parts phosphorus-containing flame retardant, 2-3 parts graphene oxide, 1-5 parts hexagonal boron nitride, 2-6 parts montmorillonite, 0.1-0.6 parts antioxidant, and 1-10 parts plasticizer.

3. The flame-retardant polylactic acid composite material according to claim 1, characterized in that, The phosphorus-containing flame retardant includes one or more of ammonium polyphosphate, triphenyl phosphate, melamine polyphosphate, and melamine orthophosphate.

4. The flame-retardant polylactic acid composite material according to claim 1, characterized in that, The graphene oxide has a particle size of 0.5~20μm.

5. The flame-retardant polylactic acid composite material according to claim 1, characterized in that, The antioxidants include one or more of antioxidant 1010, antioxidant 168, and tert-butylhydroquinone.

6. The flame-retardant polylactic acid composite material according to claim 5, characterized in that, The antioxidants are antioxidant 1010 and antioxidant 168.

7. The flame-retardant polylactic acid composite material according to claim 6, characterized in that, The mass ratio of antioxidant 1010 to antioxidant 168 is (2~4):

1.

8. The flame-retardant polylactic acid composite material according to claim 1, characterized in that, The plasticizer includes one or more of dioctyl phthalate, tributyl citrate, polyethylene glycol, and polypropylene glycol.

9. A method for preparing the flame-retardant polylactic acid composite material according to any one of claims 1 to 8, comprising: Polylactic acid, phosphorus-containing flame retardant, graphene oxide, hexagonal boron nitride, montmorillonite, antioxidant and plasticizer are mixed and melt extruded to obtain flame-retardant polylactic acid composite material.

10. The application of the flame-retardant polylactic acid composite material according to any one of claims 1 to 8 or the flame-retardant polylactic acid composite material prepared by the preparation method according to claim 9 in candle containers.

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