Halogen-free and fluorine-free flame-retardant polypropylene composite material, preparation method and application thereof

Abstract

The application provides a halogen-free and fluorine-free flame-retardant polypropylene composite material and a preparation method and application thereof, and the halogen-free and fluorine-free flame-retardant polypropylene composite material comprises, in parts by weight, 54-76 parts of polypropylene resin, 4-16 parts of a phosphate ester flame retardant, 4-17 parts of a melamine flame retardant and 4-22 parts of a piperazine flame retardant. In the application, the halogen-free and fluorine-free flame-retardant polypropylene composite material can have excellent fluidity, flame-retardant performance and mechanical properties, can realize non-ignition of degreasing cotton by promoting combustion dripping, so that the material can also reach a higher flame-retardant grade, and the material is environment-friendly.

Description

Technical Field

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

[0002] Polypropylene (PP) is a semi-crystalline thermoplastic with advantages such as good impact resistance and corrosion resistance, and is widely used in the manufacture of components for electronics, automotive parts, and modern office supplies. However, its flammability limits its application. Currently used flame-retardant polypropylene materials include halogenated and halogen-free flame-retardant polypropylene. However, halogenated polypropylene materials produce large amounts of corrosive and toxic gases and smoke during thermal cracking and combustion, which can easily cause secondary disasters and is not environmentally friendly. Therefore, it is receiving more attention, especially in the electronics and automotive parts industries.

[0003] However, existing halogen-free flame-retardant polypropylene materials often suffer from poor flowability and mechanical properties. Furthermore, fluoropolymers are often added during the preparation process as anti-dripping agents to reduce droplets produced after combustion, thereby improving the flame-retardant performance of the polypropylene material. According to the EU definition, such substances belong to PFAS, which pose a permanent hazard to the environment and human health. CN109486013A discloses a high-efficiency reinforced halogen-free flame-retardant functional masterbatch that can be directly applied to the injection molding of polypropylene products. It is composed of two masterbatches, A and B, to obtain a halogen-free NP-Si system of halogen-free flame-retardant PP. This avoids the modification efficiency loss caused by the shear friction and heat generated during the processing of reinforced halogen-free flame-retardant polypropylene modification systems, and also solves the problem of mutual loss of modification efficiency caused by the mismatch of processing temperatures between the two modification systems. However, it uses polytetrafluoroethylene as an anti-dripping agent, resulting in poor environmental performance, and the flowability and mechanical properties of the polypropylene need further improvement.

[0004] Therefore, developing a polypropylene material with excellent flowability and mechanical properties, environmental friendliness, and the ability to achieve a high flame retardancy rating without the addition of anti-dripping agents is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a halogen-free and fluorine-free flame-retardant polypropylene composite material, its preparation method, and its applications. This halogen-free and fluorine-free flame-retardant polypropylene composite material does not require the addition of anti-dripping agents; instead, it achieves a high flame-retardant rating by promoting the dripping of combustible materials. This overcomes the bias in existing technologies where flame-retardant performance can only be improved through anti-dripping agents, not by promoting the dripping of combustible materials. Simultaneously, it ensures that the polypropylene composite material possesses excellent flowability and mechanical properties, and is environmentally friendly.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a halogen-free and fluorine-free flame-retardant polypropylene composite material, wherein, by weight, the halogen-free and fluorine-free flame-retardant polypropylene composite material comprises 54 to 76 parts of polypropylene resin, 4 to 16 parts of phosphate ester flame retardant, 4 to 17 parts of melamine flame retardant and 4 to 22 parts of piperazine flame retardant.

[0008] In this invention, the melting temperature of phosphate ester flame retardants is close to that of polypropylene. During processing, they are liquid, acting as a lubricant and improving material flowability. Simultaneously, they release a large amount of gas during combustion, enhancing the flame retardant properties of the material. Melamine flame retardants possess a highly rigid, layered structure, allowing the material to maintain a certain degree of rigidity while providing flame retardancy. The combination of piperazine and melamine flame retardants facilitates rapid charring, while the added phosphate ester flame retardants promote dripping, causing burning material to drip quickly, carrying away heat and preventing the ignition of other materials, thus also preventing the spread of fire. By compounding the components in specific proportions, the polypropylene material possesses excellent flame retardant properties, mechanical properties, and flowability, without the need for fluorinated anti-dripping agents, making the material environmentally friendly.

[0009] In this invention, 54 to 76 parts of polypropylene resin can be, for example, 54 parts, 55 parts, 56 parts, 58 parts, 60 parts, 62 parts, 64 parts, 66 parts, 68 parts, 70 parts, 72 parts, 74 parts, 75 parts, 76 parts, etc.

[0010] In this invention, 4 to 16 parts of phosphate ester flame retardant can be, for example, 4 parts, 5 parts, 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts, 8 parts, 8.5 parts, 9 parts, 9.5 parts, 10 parts, 10.5 parts, 11 parts, 11.5 parts, 12 parts, 12.5 parts, 13 parts, 13.5 parts, 14 parts, 14.5 parts, 15 parts, 15.5 parts, 16 parts, etc.

[0011] In this invention, both excessively high and excessively low content of the phosphate ester flame retardant will cause the flame retardant performance of the material to fail. Specifically, when the content of the phosphate ester flame retardant is too low, there is insufficient gas during the combustion process, and the material's fluidity is too low, preventing the material from carrying away heat through rapid dripping. This also results in insufficient expansion of the char layer, leading to a poor or failed flame retardant effect. When the content of the phosphate ester flame retardant is too high, the material's fluidity is too high, causing it to drip too quickly and carry flames with it during the dripping process. This can ignite the absorbent cotton during combustion, causing the flame retardant to fail. In addition, an excessively high content of the phosphate ester flame retardant will also lead to excessive gas release during combustion, damaging the char layer and affecting the flame retardant effect.

[0012] In this invention, 4 to 17 parts of melamine flame retardant can be, for example, 4 parts, 4.2 parts, 4.4 parts, 4.6 parts, 4.8 parts, 5 parts, 5.2 parts, 5.4 parts, 5.6 parts, 5.8 parts, 6 parts, 6.2 parts, 6.4 parts, 6.6 parts, 6.8 parts, 7 parts, 7.2 parts, 7.4 parts, 7.6 parts, 7.8 parts, 8 parts, 8.2 parts, 8.4 parts, 8.6 parts, 8.8 parts, 9 parts, 9.2 parts, 9.4 parts, 9.6 parts, 9.8 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 16.5 parts, 17 parts, etc.

[0013] In this invention, the content of the melamine flame retardant is within a limited range, which enables the material to have both good rigidity and fluidity. If the content is too high, the rigidity of the material is improved to a certain extent due to its lamellar structure, but at the same time, this lamellar structure will increase the friction during the material processing, thereby making the material's fluidity worse.

[0014] In this invention, 4 to 22 parts of piperazine flame retardant can be, for example, 4 parts, 4.5 parts, 5 parts, 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts, 8 parts, 8.5 parts, 9 parts, 9.5 parts, 10 parts, 10.5 parts, 11 parts, 11.5 parts, 12 parts, 12.5 parts, 13 parts, 13.5 parts, 14 parts, 14.5 parts, 15 parts, 15.5 parts, 16 parts, 16.5 parts, 17 parts, 17.5 parts, 18 parts, 18.5 parts, 19 parts, 19.5 parts, 20 parts, 21 parts, 21.5 parts, 22 parts, etc.

[0015] Preferably, the melt flow rate of the polypropylene resin is 5 to 17 g / 10 min, for example, it can be 5 g / 10 min, 6 g / 10 min, 7 g / 10 min, 8 g / 10 min, 9 g / 10 min, 10 g / 10 min, 11 g / 10 min, 12 g / 10 min, 13 g / 10 min, 14 g / 10 min, 15 g / 10 min, 16 g / 10 min, 17 g / 10 min, etc.

[0016] In this invention, the melt flow rate of the polypropylene resin was measured at 230°C and 2.16 kg.

[0017] Preferably, the phosphate ester flame retardant includes phenyl phosphate ester flame retardants.

[0018] Preferably, the phosphate ester flame retardant includes hydroquinone bis(diphenyl phosphate) and / or hydroquinone bis[di(1-methyl-2-phenyl) phosphate].

[0019] Preferably, the mass ratio of hydroquinone bis(diphenyl phosphate) to hydroquinone bis[di(1-methyl-2-phenyl) phosphate] is (0.2-4.2):1, wherein the specific values ​​of (0.2-4.2) can be, for example, 0.2, 0.4, 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8, 4, 4.2, etc.; more preferably, it is (2-4):1.

[0020] Preferably, the melamine flame retardant includes melamine pyrophosphate and / or melamine polyphosphate.

[0021] Preferably, the mass ratio of melamine pyrophosphate to melamine polyphosphate is 1:(0.5-3.2), wherein the specific values ​​of (0.5-3.2) can be, for example, 0.5, 0.6, 0.7, 0.8, 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, etc.; more preferably, it is 1:(1.2-3).

[0022] Preferably, the piperazine flame retardant includes piperazine pyrophosphate.

[0023] Preferably, the mass ratio of the melamine flame retardant to the piperazine flame retardant is 1:(0.3-4.2), wherein the specific values ​​in (0.3-4.2) can be, for example, 0.3, 0.5, 0.6, 0.8, 1, 1.2, 1.4, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, 1.85, 1.9, 1.95, 2, 2.1, 2.15, 2.2, 2.25, 2.3, 2.35, 2.4, 2.45, 2.5, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8, 4, 4.2, etc., and more preferably 1:(1.5-2.5).

[0024] In this invention, melamine flame retardant can also act as a gas source, while piperazine flame retardant mainly plays the role of char formation. When the mass ratio of the two is within the range specified above, the combination of the two has a better effect and the flame retardant performance of the material is superior. Polypropylene, as a polymer that decomposes to produce combustible gas, cannot char itself. Therefore, if the proportion of piperazine flame retardant is too small, the char formation effect will be poor. On the other hand, if the proportion of piperazine flame retardant is too large, the gas source will be reduced and the char layer will not expand well.

[0025] Preferably, the halogen-free and fluorine-free flame-retardant polypropylene composite material further includes 0 to 5 parts of other additives, for example, 0 parts, 0.1 parts, 0.5 parts, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, etc., by mass percentage.

[0026] Preferably, the other additives include at least one of antioxidants, ultraviolet absorbers, or lubricants.

[0027] In this invention, the antioxidants include, but are not limited to, antioxidant 1010, antioxidant 168, antioxidant 164, antioxidant DLTP, antioxidant TPP, antioxidant MB, etc.

[0028] In this invention, the ultraviolet absorbers include, but are not limited to, ultraviolet absorbers UV-P, UV-O, UV-9, UV-531, UVP-327, etc.

[0029] In this invention, the lubricant includes, but is not limited to, ethylene bis-stearamide, erucamide, zinc stearate, or silicone oil.

[0030] In a second aspect, the present invention provides a method for preparing a halogen-free and fluorine-free flame-retardant polypropylene composite material according to the first aspect, the method comprising the following steps:

[0031] Polypropylene resin, phosphate ester flame retardant, melamine flame retardant and piperazine flame retardant are mixed and melt-extruded to obtain the halogen-free and fluorine-free flame-retardant polypropylene composite material.

[0032] Preferably, the mixed material also includes other additives.

[0033] Preferably, the temperature of the melt extrusion is 60–250°C.

[0034] In this invention, the melt extrusion is carried out in a twin-screw extruder; the process parameters of the twin-screw extruder are: screw length-to-diameter ratio of 25 to 48:1; the specific temperatures of each zone of the twin-screw extruder are: zone 1 is 80 to 120°C, zones 2 to 6 are 160 to 200°C, and zone 7 is 180 to 200°C.

[0035] Thirdly, the present invention provides an electrical material comprising the halogen-free and fluorine-free flame-retardant polypropylene composite material according to the first aspect.

[0036] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] The halogen-free and fluorine-free flame-retardant polypropylene composite material provided by this invention uses a specific amount of phosphate ester flame retardants, melamine flame retardants and piperazine flame retardants to make the polypropylene material have excellent flame retardant properties, flowability and mechanical properties. The polypropylene material can achieve a high flame retardant rating by promoting the rapid dripping of burning materials without igniting degreased cotton, without the need to add fluorine-containing anti-dripping agents, which is environmentally friendly. Detailed Implementation

[0039] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0040] The materials used in all embodiments and comparative examples of this invention are as follows:

[0041] polypropylene

[0042] PP-1: Homopolymer polypropylene, Sinopec, PP HP500N, melt index is 10g / 10min (230℃, 2.16kg, standard ISO 1133:2022);

[0043] PP-2: PP K1215 Shanghai SECCO, melt index is 15g / 10min (230℃, 2.16kg, standard ISO 1133:2022);

[0044] Phosphate ester flame retardants

[0045] P1: Hydroquinone bis(diphenyl phosphate), Wansheng Chemical, PX-220, molecular weight 574;

[0046] P2: Hydroquinone bis[di(1-methyl-2-phenyl)phosphate];

[0047] P3: Triphenyl phosphate;

[0048] Melamine flame retardants

[0049] N1: Melamine polyphosphate, Budenheim, Bubit 314S;

[0050] N2: Melamine pyrophosphate, Sichuan Fine Chemical Research and Design Institute, DMPY;

[0051] Piperazine flame retardants

[0052] Piperazine pyrophosphate, Sichuan Fine Chemical Research and Design Institute, JNP-2;

[0053] Both aluminum hypophosphite and aluminum hydroxide were purchased commercially.

[0054] Other additives: Pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] (antioxidant 1010) and 2-(2′-hydroxy-5′-methylphenyl)benzotriazole (ultraviolet absorber UV-P) in a mass ratio of 1:1.

[0055] Examples 1-13, Comparative Examples 1-8

[0056] Examples 1-13 and Comparative Examples 1-8 each provide a halogen-free and fluorine-free flame-retardant polypropylene composite material. The specific formulations, by weight, are shown in Table 1 (" / " indicates that the component is not in the formulation). The preparation method of the halogen-free and fluorine-free flame-retardant polypropylene composite material includes: mixing polypropylene resin, phosphate ester flame retardants, melamine flame retardants, piperazine flame retardants, and optional other additives in a twin-screw extruder, followed by melt extrusion to obtain the halogen-free and fluorine-free flame-retardant polypropylene composite material. The process parameters of the twin-screw extruder are: screw length-to-diameter ratio of 35:1; and the specific temperatures of each zone of the twin-screw extruder are: zone 1 at 100℃, zones 2-6 at 180℃, and zone 7 at 190℃.

[0057] Table 1

[0058]

[0059]

[0060] Performance testing

[0061] The halogen-free and fluorine-free flame-retardant polypropylene composite materials provided in Examples 1-13 and Comparative Examples 1-8 were subjected to the following performance tests:

[0062] (1) Flexural modulus: tested according to ISO 178:2019 standard;

[0063] (2) Melt flow rate: Tested at 230℃ and 2.16kg, with reference to standard ISO 1133:2022;

[0064] (3) 1.5mm flame retardant rating: tested according to UL94 test standard; “NG” indicates that the flame retardant performance fails.

[0065] The specific test results are shown in Table 2.

[0066] Table 2

[0067]

[0068]

[0069] As shown in Table 2, the halogen-free and fluorine-free flame-retardant polypropylene composite material provided by the present invention improves the flame retardant performance of the polypropylene composite material by using a specific content of phosphate ester flame retardant and a specific ratio of melamine flame retardant and piperazine flame retardant, while ensuring that its mechanical properties and flowability remain basically unchanged or even improved. This makes the polypropylene composite material have excellent flame retardant performance, flowability and mechanical properties. The halogen-free and fluorine-free flame-retardant polypropylene composite material has a flexural modulus ≥1300MPa, a melt flow rate of 10~18g / 10min, and a flame retardant rating of V-1 or above at 1.5mm.

[0070] Comparing Examples 1, 6, 7, and 8, it can be seen that the flame retardant performance is best when the mass ratio of melamine flame retardant to piperazine flame retardant is within a further optimized range. This is because melamine flame retardant also acts as a gas source, while piperazine flame retardant mainly plays the role of char formation. If the proportion of piperazine flame retardant is too high, the gas source will be reduced and the char layer will not expand well; if the proportion is too low, the char formation effect of polypropylene will be poor, affecting the flame retardant efficiency.

[0071] Comparing Example 1 with Comparative Examples 1-8, it can be seen that the flame retardant is not a combination of phosphate ester flame retardant, melamine flame retardant and piperazine flame retardant, and the three are not combined in specific amounts. The resulting composite material has poor flame retardant properties, and its mechanical properties and flowability are also reduced.

[0072] In summary, it has long been believed that halogen-free flame-retardant polypropylene cannot achieve a high flame retardant rating by dripping onto non-igniting absorbent cotton. However, the polypropylene composite material provided by this invention is fluorine-free. By compounding three flame retardants with different functions, it achieves the preparation of drip-type high flame-retardant PP, and also breaks free from the limitations of polytetrafluoroethylene, thus achieving halogen-free and fluorine-free flame retardancy. At the same time, it increases the fluidity of the material, accelerates the molding process, and reduces environmental damage.

[0073] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A halogen-free, fluorine-free flame-retardant polypropylene composite, characterized in that, The halogen-free and fluorine-free flame-retardant polypropylene composite material comprises 54-76 parts by weight of polypropylene resin, 4-16 parts by weight of phosphate ester flame retardant, 4-17 parts by weight of melamine flame retardant and 4-22 parts by weight of piperazine flame retardant; The phosphate ester flame retardant comprises hydroquinone bis(diphenyl phosphate) and / or hydroquinone bis[dio(1-methyl-2-phenyl) phosphate]; The mass ratio of the melamine flame retardant to the piperazine flame retardant is 1:(1.5-2.5); The melamine flame retardant comprises melamine pyrophosphate and / or melamine polyphosphate; The piperazine flame retardant comprises piperazine pyrophosphate.

2. The halogen-free, fluorine-free flame retardant polypropylene composite material according to claim 1, characterized in that, The polypropylene resin has a melt flow rate of 5-17 g / 10 min.

3. The halogen-free, fluorine-free flame retardant polypropylene composite of claim 1, wherein, The mass ratio of the hydroquinone bis(diphenyl phosphate) to the hydroquinone bis[dio(1-methyl-2-phenyl) phosphate] is (0.2-4.2):

1.

4. The halogen-free, fluorine-free flame retardant polypropylene composite according to claim 3, characterized in that, The mass ratio of the hydroquinone bis(diphenyl phosphate) to the hydroquinone bis[dio(1-methyl-2-phenyl) phosphate] is (2-4):

1.

5. The halogen-free, fluorine-free flame retardant polypropylene composite of claim 1, wherein, The melamine flame retardant comprises melamine pyrophosphate and melamine polyphosphate, and the mass ratio of the melamine pyrophosphate to the melamine polyphosphate is 1:(0.5-3.2).

6. The halogen-free, fluorine-free flame retardant polypropylene composite of claim 5, wherein, The mass ratio of the melamine pyrophosphate to the melamine polyphosphate is 1:(1.2-3).

7. The halogen-free, fluorine-free flame retardant polypropylene composite of claim 1, wherein, The halogen-free and fluorine-free flame-retardant polypropylene composite material further comprises 0-5 parts by weight of other auxiliary agents.

8. The halogen-free, fluorine-free flame retardant polypropylene composite of claim 7, wherein, The other auxiliary agents comprise at least one of antioxidant, ultraviolet absorber or lubricant.

9. A process for the preparation of a halogen-free, fluorine-free flame-retardant polypropylene composite material according to any one of claims 1 to 8, characterized in that, The preparation method comprises the following steps: The polypropylene resin, the phosphate ester flame retardant, the melamine flame retardant and the piperazine flame retardant are mixed and melt-extruded to obtain the halogen-free and fluorine-free flame-retardant polypropylene composite material.

10. The method of claim 9, wherein, The mixed material further comprises other auxiliary agents.

11. The preparation method according to claim 9, characterized in that, The temperature for the melt-extrusion is 60-250 ℃.

12. An electrical material, characterized by, The electrical appliance material comprises the halogen-free and fluorine-free flame-retardant polypropylene composite material according to any one of claims 1-8.

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