Flame-retardant composite material as well as preparation method and application thereof

Abstract

The invention discloses a flame-retardant composite material as well as a preparation method and application thereof. The flame-retardant material comprises the following components in parts by weight: 40-60 parts of polypropylene resin, 3-8 parts of a charring agent, 8-18 parts of a composite flame retardant, 8-15 parts of a flexibilizer, 5-12 parts of a nano filler, 0.2-2 parts of an antioxidant and 0.5-2 parts of a lubricant, the composite flame retardant is prepared from the following raw materials: ammonium polyphosphate, melamine cyanurate and zinc borate. According to the flame-retardant composite material disclosed by the invention, the composite flame retardant, the charring agent and the nano filler are introduced, so that the flame-retardant composite material disclosed by the invention has the characteristics of excellent high flame retardance, low smoke density and excellent mechanical properties.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a flame-retardant composite material, its preparation method, and its application. Background Technology

[0002] Polypropylene (PP), a general-purpose plastic with excellent overall performance and low cost, is increasingly expanding its applications from everyday consumer goods to high-end sectors such as automobiles, home appliances, and rail transportation. However, PP has a limiting oxygen index (LOI) of only 17%–18%, classifying it as a flammable material. Furthermore, its combustion is accompanied by molten dripping, which can easily ignite and spread a fire. Therefore, flame-retardant modification of PP is crucial for broadening its application range.

[0003] To improve the flame retardant properties of PP materials and enable their application in other fields, traditional methods involve modifying PP with halogenated flame retardants. While these methods offer high flame retardant efficiency and require only small amounts, they release large quantities of corrosive and toxic hydrogen halide gases and soot during combustion. Alternatively, halogen-free flame retardant systems are used, but their flame retardant efficiency is extremely low, typically requiring 50% to 60% or more to achieve a certain flame retardant rating. This severely compromises the material's mechanical properties (especially impact strength and flowability), rendering the product unsuitable for structural applications.

[0004] Therefore, there is an urgent need to provide a polypropylene flame-retardant material with high flame retardancy, low smoke density, and excellent mechanical properties. Summary of the Invention

[0005] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the first aspect of the present invention proposes a flame-retardant composite material, which has the characteristics of high flame retardancy, low smoke density and excellent mechanical properties.

[0006] A second aspect of the present invention also provides a method for preparing a flame-retardant composite material.

[0007] A third aspect of the present invention also provides an application of a flame-retardant composite material.

[0008] The flame-retardant composite material provided according to a first aspect of the present invention comprises the following components in parts by weight: 40-60 parts polypropylene resin, 3-8 parts charring agent, 8-18 parts composite flame retardant, 8-15 parts toughening agent, 5-12 parts nanofiller, 0.2-2 parts antioxidant, and 0.5-2 parts lubricant; The raw materials for preparing the composite flame retardant include ammonium polyphosphate, melamine cyanurate, and zinc borate.

[0009] According to a preferred embodiment of the present invention, the mass ratio of ammonium polyphosphate, melamine cyanurate, and zinc borate is (3~4):(2~2.5):1. Therefore, the flame-retardant composite material of the present invention exhibits superior smoke suppression and flame-retardant effects.

[0010] According to a preferred embodiment of the present invention, the preparation method of the composite flame retardant is as follows: Ammonium polyphosphate, melamine cyanurate, zinc borate, and solvent are mixed and stirred to react; then spray-dried to obtain the composite flame retardant.

[0011] Therefore, the composite flame retardant of the present invention prepared by the above method can improve its compatibility and dispersibility with polypropylene resin, avoiding the problem of decreased mechanical properties after mixing with polypropylene resin in conventional physical mixing.

[0012] According to a preferred embodiment of the present invention, the charring agent is at least one selected from starch, glucose, sorbitol, and pentaerythritol.

[0013] According to a preferred embodiment of the present invention, the polypropylene resin is a copolymer polypropylene resin, and the melt flow rate of the copolymer polypropylene resin is 80-100 g / 10min at 230°C and 2.16 kg. (Standard ISO 1133) 1:2011).

[0014] According to a preferred embodiment of the present invention, the toughening agent is at least one of ethylene octene copolymer or ethylene butene copolymer.

[0015] According to a preferred embodiment of the present invention, the nanofiller includes at least one of talc powder, mica powder, and montmorillonite.

[0016] According to a preferred embodiment of the present invention, the antioxidant includes at least one of hindered amine antioxidants, hindered phenolic antioxidants, and phosphite antioxidants. In some preferred embodiments, antioxidants are used in combination, such as hindered amine antioxidants and hindered phenolic antioxidants, or hindered amine antioxidants and phosphite antioxidants, in a weight ratio of 1:(1 to 1.5).

[0017] According to a preferred embodiment of the present invention, the lubricant is a commonly used lubricant, such as ethyl bis-stearamide (EBS), Struktol TR451, erucamide, etc.

[0018] The flame-retardant composite material according to embodiments of the present invention has at least the following beneficial effects: This invention introduces composite flame retardants, charring agents, and nanofillers, enabling the flame-retardant composite material of this invention to possess excellent high flame retardancy, low smoke density, and superior mechanical properties.

[0019] This is because the ammonium polyphosphate, melamine cyanurate, and zinc borate in the composite flame retardant of this invention form a ternary synergistic flame retardant system, solving compatibility and dispersibility issues. Furthermore, when heated, the ammonium polyphosphate decomposes to generate phosphoric acid and polyphosphoric acid, promoting polymer dehydration and char formation while releasing non-flammable gases; it also forms a zinc borophosphate glass layer with zinc borate, enhancing the density of the char layer. Melamine cyanurate decomposes upon heating, absorbing heat and releasing nitrogen gas, diluting flammable gases. After dispersion in the polymer, the nanofiller forms a robust carbon-silicate composite layer during combustion, effectively blocking the entry of heat and oxygen, as well as the escape of flammable gases. In addition, the charring agent synergistically with the composite flame retardant system promotes the formation of a denser and more stable char layer, thereby improving flame retardant performance and reducing smoke density.

[0020] According to a second aspect of the present invention, a method for preparing a flame-retardant composite material as described in the first aspect of the present invention is provided, comprising the following steps: Mix all components evenly, then knead, melt, and extrude granulate at 80~230℃ to obtain the final product.

[0021] According to a preferred embodiment of the present invention, the length-to-diameter ratio of the extrusion screw in the extrusion granulation is 36 to 48:1.

[0022] According to a preferred embodiment of the present invention, the 80-230°C range is divided into the following sections: Zone 1: 80-120°C; Zones 2-5: 180-200°C; and other zones: 200-230°C.

[0023] The third aspect of this invention provides an application of the flame-retardant composite material described in the first aspect of this invention in the fields of automobiles, electrical appliances, construction, and packaging.

[0024] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Detailed Implementation

[0025] The following are specific embodiments of the present invention, and the technical solutions of the present invention will be further described in conjunction with the embodiments, but the present invention is not limited to these embodiments.

[0026] Unless otherwise specified, the reagents, methods and equipment used in this invention are all conventional reagents, methods and equipment in this technical field.

[0027] In some embodiments of the present invention, a flame-retardant composite material is provided, comprising the following components in parts by weight: 40-60 parts polypropylene resin, 3-8 parts charring agent, 8-18 parts composite flame retardant, 8-15 parts toughening agent, 5-12 parts nanofiller, 0.2-2 parts antioxidant, and 0.5-2 parts lubricant; The raw materials for preparing the composite flame retardant include ammonium polyphosphate, melamine cyanurate, and zinc borate.

[0028] In this invention, by introducing composite flame retardants, charring agents and nanofillers, the flame-retardant composite material of this invention has the characteristics of excellent high flame retardancy, low smoke density and excellent mechanical properties.

[0029] This is because the ammonium polyphosphate, melamine cyanurate, and zinc borate in the composite flame retardant of this invention form a ternary synergistic flame retardant system, solving compatibility and dispersibility issues. Furthermore, when heated, the ammonium polyphosphate decomposes to generate phosphoric acid and polyphosphoric acid, promoting polymer dehydration and char formation while releasing non-flammable gases; it also forms a zinc borophosphate glass layer with zinc borate, enhancing the density of the char layer. Melamine cyanurate decomposes upon heating, absorbing heat and releasing nitrogen gas, diluting flammable gases. After dispersion in the polymer, the nanofiller forms a robust carbon-silicate composite layer during combustion, effectively blocking the entry of heat and oxygen, as well as the escape of flammable gases. In addition, the charring agent synergistically with the composite flame retardant system promotes the formation of a denser and more stable char layer, thereby improving flame retardant performance and reducing smoke density.

[0030] In some embodiments of the present invention, the mass ratio of ammonium polyphosphate, melamine cyanurate, and zinc borate is (3~4):(2~2.5):1. Therefore, the flame-retardant composite material of the present invention exhibits superior smoke suppression and flame-retardant effects.

[0031] In some embodiments of the present invention, the preparation method of the composite flame retardant is as follows: Ammonium polyphosphate, melamine cyanurate, zinc borate, and solvent are mixed and stirred to react; then spray-dried to obtain the composite flame retardant.

[0032] Therefore, the composite flame retardant of the present invention prepared by the above method can improve its compatibility and dispersibility with polypropylene resin, avoiding the problem of decreased mechanical properties after mixing with polypropylene resin in conventional physical mixing.

[0033] In some embodiments of the present invention, the charring agent is at least one of starch, glucose, sorbitol, and pentaerythritol.

[0034] In some embodiments of the present invention, the polypropylene resin is a copolymer polypropylene resin, and the melt flow rate of the copolymer polypropylene resin is 80-100 g / 10 min at 230°C and 2.16 kg. (Standard ISO 1133) 1:2011).

[0035] In some embodiments of the present invention, the melt flow rate of the copolymer polypropylene resin is 80 g / 10 min, 82 g / 10 min, 85 g / 10 min, 88 g / 10 min, 90 g / 10 min, 92 g / 10 min, 95 g / 10 min, 98 g / 10 min, 100 g / 10 min, or a subrange consisting of any two of the above values.

[0036] In some embodiments of the present invention, the toughening agent is at least one of ethylene octene copolymer or ethylene butene copolymer.

[0037] In some embodiments of the present invention, the nanofiller includes at least one selected from talc, mica powder, and montmorillonite. As an example, when the nanofiller of the present invention is selected from montmorillonite, it forms a barrier in the polymer, delaying the transfer of heat and mass, while simultaneously producing a synergistic effect with the composite flame retardant.

[0038] In some embodiments of the present invention, the antioxidant includes at least one of hindered amine antioxidants, hindered phenolic antioxidants, and phosphite antioxidants. In some preferred embodiments, antioxidants are used in combination, such as hindered amine antioxidants and hindered phenolic antioxidants, or hindered amine antioxidants and phosphite antioxidants, in a weight ratio of 1:(1 to 1.5).

[0039] In some embodiments of the present invention, the weight ratio used in the compounding is 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5 or any sub-range composed of two of the above values.

[0040] In some embodiments of the present invention, the lubricant is a commonly used lubricant, such as ethyl bis-stearamide (EBS), Struktol TR451, erucamide, etc.

[0041] In some embodiments of the present invention, a method for preparing a flame-retardant composite material as described in the first aspect of the present invention is provided, comprising the following steps: Mix all components evenly, then knead, melt, and extrude granulate at 80~230℃ to obtain the final product.

[0042] In some embodiments of the present invention, the length-to-diameter ratio of the extrusion screw in the extrusion granulation is 36 to 48:1.

[0043] In some embodiments of the present invention, the 80-230°C range is divided into the following sections: Zone 1: 80-120°C; Zones 2-5: 180-200°C; and other zones: 200-230°C.

[0044] In some embodiments of the present invention, an application of the flame-retardant composite material described in the first aspect of the present invention is provided in the fields of automobiles, electrical appliances, construction, and packaging.

[0045] The raw materials used in some embodiments and comparative examples of this invention are as follows: Polypropylene resin: Copolymerized polypropylene resin, with a melt flow rate characteristic value of 100 g / 10 min (standard ISO 1133). 1: 2011, conditions 230℃, 2.16kg), grade: PP 640V, source: purchased from Basel.

[0046] Toughening agent: Ethylene octene copolymer, grade POE 7447, source: purchased from DuPont.

[0047] Charring agent: Pentaerythritol, commercially available; Nanofiller: Montmorillonite, commercially available; Ammonium polyphosphate, melamine cyanurate, and zinc borate are commercially available. Antioxidants: Antioxidants 1010 and 168 are mixed in a 1:1 weight ratio; Lubricant: Ethyl bis-stearamide (EBS), commercially available.

[0048] Preparation method of composite flame retardant A: Ammonium polyphosphate, melamine cyanurate, and zinc borate were dissolved in an aqueous ethanol solution at a mass ratio of 3:2:1. The mixture was stirred at 60°C for 2 hours to obtain a composite. The composite was then spray-dried to obtain the final product.

[0049] Composite flame retardant B: The mass ratio of ammonium polyphosphate, melamine cyanurate, and zinc borate is 4:2.5:1. The preparation method is the same as that of composite flame retardant A.

[0050] Composite flame retardant C: The mass ratio of ammonium polyphosphate, melamine cyanurate, and zinc borate is 1:1:1. The preparation method is the same as that for composite flame retardant A.

[0051] Composite flame retardant D: a physical mixture of melamine cyanurate and zinc borate in a 2:1 ratio.

[0052] Composite flame retardant E: a physical mixture of ammonium polyphosphate and melamine cyanurate in a 3:2 ratio.

[0053] Example 1 This example provides a flame-retardant composite material, the dosage of each component of which is shown in Table 1, and its preparation method is as follows: S1. Add polypropylene resin, charring agent, toughening agent, composite flame retardant, antioxidant and lubricant into the mixer in sequence, mix for 3 minutes to achieve a uniform mixture. S2. Feed the mixed material into the extruder through the main feed port. Add montmorillonite through the side feed port of the extruder. Use an extrusion screw with a length-to-diameter ratio of 36 to 48:1. Set the extruder temperature to 100℃ in zone 1, 200℃ in zones 2 to 5, and 230℃ in other zones. After mixing, melting, and homogenizing, extrude and granulate to obtain the final product.

[0054] Examples 2-5 Examples 2-5 provide a series of flame-retardant composite materials, the amounts of each component of which are shown in Table 1, and the preparation method is the same as in Example 1. Table 1 (parts by weight)

[0055] Comparative Example 1 This example provides a flame-retardant composite material, whose component dosage and preparation method are the same as in Example 1, except that composite flame retardant D is used instead of composite flame retardant A.

[0056] Comparative Example 2 This example provides a flame-retardant composite material, whose component dosage and preparation method are the same as in Example 1, except that composite flame retardant E is used instead of composite flame retardant A.

[0057] Comparative Example 3 This example provides a flame-retardant composite material, whose component dosage and preparation method are the same as in Example 1, except that no charring agent is added.

[0058] Performance testing The mechanical and flame-retardant properties of the flame-retardant composite materials prepared in Examples 1-5 and Comparative Examples 1-3 of this invention were determined. Impact strength was measured according to ISO 180:2023 standard; fire resistance rating UL. 94 Test: Flame-retardant composite material is injection molded into 1.6mm thick burning test strips, and tested according to UL fire resistance rating. Flame retardancy was tested according to the 2016 standard test method; smoke density rating was tested according to GB8627. Smoke density rating of materials tested according to the 2007 standard. Results are shown in Table 2.

[0059] Table 2

[0060] As can be seen from the data in Table 2, the flame-retardant composite material of the present invention has good mechanical properties, flame-retardant properties and low smoke density.

[0061] Furthermore, the data from Comparative Examples 1 to 3 show that the synergistic effect of the composite flame retardant, charring agent, and nanofiller in the embodiments of the present invention can not only achieve high flame retardancy and low smoke density, but also does not reduce the mechanical properties of the composite material.

[0062] The present invention has been described in detail above with reference to the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A flame-retardant composite material, characterized in that, Includes the following components, calculated in parts by weight: 40-60 parts polypropylene resin, 3-8 parts charring agent, 8-18 parts composite flame retardant, 8-15 parts toughening agent, 5-12 parts nanofiller, 0.2-2 parts antioxidant, and 0.5-2 parts lubricant; The raw materials for preparing the composite flame retardant include ammonium polyphosphate, melamine cyanurate, and zinc borate.

2. The flame-retardant composite material according to claim 1, characterized in that, The mass ratio of ammonium polyphosphate, melamine cyanurate, and zinc borate is (3~4):(2~2.5):

1.

3. The flame-retardant composite material according to claim 1 or 2, characterized in that, The preparation method of the composite flame retardant is as follows: Ammonium polyphosphate, melamine cyanurate, zinc borate, and solvent are mixed and stirred to react; then spray-dried to obtain the composite flame retardant.

4. The flame-retardant composite material according to claim 1, characterized in that, The charring agent is at least one of starch, glucose, sorbitol, and pentaerythritol.

5. The flame-retardant composite material according to claim 1, characterized in that, The polypropylene resin is a copolymer polypropylene resin, and the melt flow rate of the copolymer polypropylene resin is 80-100 g / 10min at 230℃ and 2.16 kg.

6. The flame-retardant composite material according to claim 1, characterized in that, The toughening agent is at least one of ethylene octene copolymer or ethylene butene copolymer.

7. The flame-retardant composite material according to claim 1, characterized in that, The antioxidant includes at least one of hindered amine antioxidants, hindered phenolic antioxidants, and phosphite antioxidants.

8. The flame-retardant composite material according to claim 1, characterized in that, The nanofiller includes at least one of talc, mica powder, and montmorillonite.

9. A method for preparing the flame-retardant composite material as described in any one of claims 1 to 8, characterized in that, Includes the following steps: Mix all components evenly, then knead, melt, and extrude granulate at 80~230℃ to obtain the final product.

10. The application of the flame-retardant composite material according to any one of claims 1 to 8 in the fields of automobiles, electrical appliances, construction, and packaging.

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