Halogen-free flame-retardant polypropylene composite material and preparation method thereof
By adding magnesium hydroxide to polypropylene to coat expanded graphene, the problems of polypropylene's flammability and high cost in preparing black flame retardant fuel were solved, achieving both high efficiency in flame retardancy and maintenance of material properties.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HEFEI GENIUS NEW MATERIALS CO LTD
- Filing Date
- 2023-01-30
- Publication Date
- 2026-07-03
AI Technical Summary
Polypropylene is flammable, and the addition of a large amount of halogen-free flame retardant will affect the mechanical properties of the material. The preparation of black flame retardant is costly and difficult.
Adding a small amount of magnesium hydroxide to polypropylene to coat expanded graphene enhances the flame retardant effect in conjunction with a halogen-free flame retardant, and black flame-retardant polypropylene material is prepared by coating expanded graphene with magnesium hydroxide.
It achieves improved flame retardant effect with low flame retardant dosage, reduces material cost, maintains or improves mechanical properties, and avoids the disadvantages of using carbon black.
Smart Images
Figure BDA0004055341290000051 
Figure BDA0004055341290000061
Abstract
Description
Technical Field
[0001] This invention belongs to the field of polymer materials technology, and specifically relates to a halogen-free flame-retardant polypropylene composite material and its preparation method. Background Technology
[0002] Polypropylene (PP) is a thermoplastic. Due to its good balance of rigidity and toughness, weather resistance, and chemical corrosion resistance, it is one of the most commonly used general-purpose plastics.
[0003] However, polypropylene is flammable and lacks inherent flame retardancy, thus limiting its applications. Currently, commonly used halogen-free flame-retardant formulations involve adding intumescent halogen-free phosphorus and nitrogen-based flame retardants to polypropylene. However, the amount of these flame retardants added is usually quite large, generally 22-25% of the total amount, to achieve a relatively stable flame-retardant effect. Adding a large amount of flame retardant can significantly impact the material's mechanical properties, reducing their effectiveness. Furthermore, producing black flame-retardant flames is difficult, requiring an even higher proportion of flame retardant, leading to a substantial increase in cost. Summary of the Invention
[0004] In view of this, the present invention needs to provide a halogen-free flame-retardant polypropylene composite material, which improves the flame-retardant effect of the material by adding a small amount of magnesium hydroxide to the polypropylene system to coat expanded graphene, and at the same time facilitates the preparation of black flame-retardant polypropylene material.
[0005] To achieve the above objectives, the present invention adopts the following technical solution:
[0006] This invention provides a halogen-free flame-retardant polypropylene composite material, which is prepared by weight of 73-80.6 parts of polypropylene, 17-22 parts of halogen-free flame retardant, 2-4 parts of magnesium hydroxide-coated expanded graphene, 0.2-0.6 parts of heat stabilizer and 0.2-0.4 parts of processing aid.
[0007] In a further embodiment, the polypropylene is selected from at least one of copolymer polypropylene and homopolymer polypropylene.
[0008] In a further embodiment, the halogen-free flame retardant is a phosphorus-nitrogen intumescent flame retardant.
[0009] In a further embodiment, the magnesium hydroxide-coated expanded graphene is prepared according to the following method:
[0010] MgCl2·6H2O and expandable graphene were added to deionized water and stirred. The pH of the mixture was adjusted to 9-11. The reaction was heated to obtain magnesium hydroxide-coated expanded graphene.
[0011] In a further embodiment, the mass ratio of MgCl2·6H2O to expandable graphene is 50:3-5.
[0012] The heating reaction is carried out at a temperature of 75-85°C for 6-12 hours.
[0013] Preferably, the product after the heating reaction is filtered, washed 3-5 times with deionized water, dried in an oven at 50-60°C, and finally ground to obtain magnesium hydroxide-coated expanded graphene material.
[0014] In a further embodiment, the heat stabilizer is selected from at least one of phenol-resistant heat stabilizers, phosphite heat stabilizers, and thioester heat stabilizers.
[0015] In a further embodiment, the processing aid is a lubricant, and the lubricant is selected from at least one of metal soaps and silicones.
[0016] A second objective of this invention is to provide a method for preparing the above-mentioned flame-retardant polypropylene composite material, comprising the following steps:
[0017] Polypropylene, halogen-free flame retardant, magnesium hydroxide-coated expanded graphene, heat stabilizer and processing aids are thoroughly mixed according to the weight ratio to obtain a uniform mixture.
[0018] The mixture is added to a twin-screw extruder, melt-mixed and dispersed, and then extruded and granulated to obtain a modified flame-retardant polypropylene composite material.
[0019] The present invention has the following beneficial effects:
[0020] The present invention adds a small amount of magnesium hydroxide to coat expanded graphene, which can help improve the strength of the surface carbon layer during the combustion process of the material, thereby playing a role in isolating oxygen and helping to improve the flame retardant effect.
[0021] The magnesium hydroxide coating of expanded graphene of the present invention reduces the high surface energy of the expanded graphene material, prevents agglomeration, and can be uniformly distributed inside the material. The magnesium hydroxide on its surface itself has a flame retardant effect and absorbs heat during combustion, which helps to improve the flame retardant effect.
[0022] Since black flame retardant flames mainly consist of black pigment, the primary component of which is carbon black, carbon black itself is combustible, has a large specific surface area, and contains numerous micropores that easily form a spatial network channel that is difficult to break down. The presence of these micropores affects the density of the flame-retardant carbon layer, preventing it from providing adequate insulation. Furthermore, the high specific surface area of carbon black easily adsorbs light stabilizers and antioxidants, causing these additives to agglomerate or partially fail, thus affecting their effectiveness. The magnesium hydroxide-coated expanded graphene material added in this invention is itself black and can also be used to prepare black flame-retardant polypropylene composite materials, thereby reducing or eliminating the need for coloring carbon black and avoiding the aforementioned drawbacks.
[0023] In addition, the low surface polarity of magnesium hydroxide-coated expanded graphene reduces the absorption of antioxidants and can further improve the mechanical properties and thermal stability of the material. Detailed Implementation
[0024] The present invention will be described below through specific embodiments. It should be noted that the specific embodiments below are for illustrative purposes only and do not limit the scope of the present invention in any way. In addition, unless otherwise specified, methods without specific conditions or steps are conventional methods, and the reagents and materials used are commercially available. In the following embodiments and comparative examples, unless otherwise specified, "parts," "number of parts," etc., refer to parts by weight; and it should be understood that the specific reagents used in the following embodiments are examples to make the technical solution of the present invention clearer, and do not mean that the present invention can only be carried out using the following reagents.
[0025] The preparation process of magnesium hydroxide-coated expanded graphene materials in the following embodiments is as follows:
[0026] 50g of MgCl2·6H2O and 4g of expandable graphene were added to 600mL of deionized water and mechanically stirred. The pH was adjusted to 10 with NaOH solution, and the mixture was heated to 80℃ and reacted for 10 hours. After the reaction was completed, the solution was cooled to room temperature, the product was filtered, washed four times with deionized water, dried in a 60℃ oven, and ground to obtain magnesium hydroxide-coated expanded graphene material.
[0027] Example 1
[0028] 76.3 parts of copolymer polypropylene PP BX3800 (SK, South Korea), 20 parts of halogen-free flame retardant FP-2200 (ADK, Japan), 3 parts of magnesium hydroxide-coated expanded graphene, 0.2 parts of heat stabilizer 1010 (BASF), 0.2 parts of heat stabilizer 168 (BASF), and 0.4 parts of processing aid silicone masterbatch E525 (Evonik, Germany) were mixed evenly in a high-speed mixer and then added to a twin-screw extruder with a length-to-diameter ratio of 38:1 for melt mixing and dispersion. The mixture was then extruded and granulated to obtain a halogen-free flame-retardant polypropylene composite material. The temperature of the twin-screw extruder from the feeding section to the die head was 180℃, 180℃, 185℃, 185℃, 190℃, 190℃, 190℃, 195℃, 195℃, and 195℃, respectively.
[0029] Example 2
[0030] 77.2 parts of homopolymer polypropylene PP S2040 (Shanghai SECCO), 19 parts of halogen-free flame retardant WR02B (Suzhou Anhongtai), 3 parts of magnesium hydroxide-coated expanded graphene, 0.2 parts of heat stabilizer 1010 (BASF), 0.3 parts of heat stabilizer 168 (BASF), and 0.3 parts of silicone masterbatch E525 (Evonik, Germany) were mixed evenly in a high-speed mixer and then added to a twin-screw extruder with a length-to-diameter ratio of 40:1 for melt mixing and dispersion. The mixture was then extruded and granulated to obtain a halogen-free flame-retardant polypropylene composite material. The temperature of the twin-screw extruder from the feeding section to the die head was 170℃, 170℃, 180℃, 180℃, 185℃, 185℃, 185℃, 185℃, 190℃, and 190℃, respectively.
[0031] Example 3
[0032] 74.2 parts of copolymer polypropylene PP K9829H (Yanshan Petrochemical), 21 parts of halogen-free flame retardant WR02B (Suzhou Anhongtai), 4 parts of magnesium hydroxide-coated expanded graphene, 0.2 parts of heat stabilizer 1010 (BASF), 0.2 parts of heat stabilizer DSTDP (Tianjin Lisheng Chemical Co., Ltd.), and 0.4 parts of processing aid silicone masterbatch E525 (Evonik, Germany) were mixed evenly in a high-speed mixer and then added to a twin-screw extruder with a length-to-diameter ratio of 42:1 for melt mixing and dispersion. The mixture was then extruded and granulated to obtain a halogen-free flame-retardant polypropylene composite material. The temperatures of the twin-screw extruder from the feeding section to the die head were 180℃, 180℃, 185℃, 185℃, 185℃, 190℃, 190℃, 190℃, 195℃, and 195℃, respectively.
[0033] Example 4
[0034] 80.6 parts of copolymer polypropylene PP EA5075 (Basel), 17 parts of halogen-free flame retardant WR02B (Suzhou Anhongtai), 2 parts of magnesium hydroxide-coated expanded graphene, 0.1 parts of heat stabilizer 1010 (BASF), 0.1 parts of heat stabilizer 168 (BASF), and 0.2 parts of processing aid silicone masterbatch E525 (Evonik, Germany) were mixed evenly in a high-speed mixer and then added to a twin-screw extruder with an aspect ratio of 36:1 for melt mixing and dispersion. The mixture was then extruded and granulated to obtain a halogen-free flame-retardant polypropylene composite material. The temperatures of the twin-screw extruder from the feeding section to the die head were 170℃, 170℃, 180℃, 180℃, 185℃, 185℃, 190℃, 195℃, 195℃, and 190℃, respectively.
[0035] Example 5
[0036] 73 parts of copolymer polypropylene PP EA5075 (Basel), 22 parts of halogen-free flame retardant FP-2200 (ADK Japan), 4 parts of magnesium hydroxide-coated expanded graphene, 0.3 parts of heat stabilizer 1010 (BASF), 0.3 parts of heat stabilizer 168 (BASF), 0.2 parts of processing aid zinc stearate (Jiangxi Hongyuan Chemical), and 0.4 parts of processing aid silicone masterbatch E525 (Evonik Germany) were mixed evenly in a high-speed mixer and then added to a twin-screw extruder with a length-to-diameter ratio of 38:1 for melt mixing and dispersion. The mixture was then extruded and granulated to obtain a halogen-free flame-retardant polypropylene composite material. The temperatures of the twin-screw extruder from the feeding section to the die head were 170℃, 180℃, 185℃, 185℃, 190℃, 200℃, 195℃, 195℃, 190℃, and 190℃, respectively.
[0037] Comparative Example 1
[0038] 79.3 parts of copolymer polypropylene PP BX3800 (SK Korea), 20 parts of halogen-free flame retardant FP-2200 (ADK Japan), 0.2 parts of heat stabilizer 1010 (BASF), 0.2 parts of heat stabilizer 168 (BASF), and 0.4 parts of processing aid silicone masterbatch E525 (Evonik Germany) were mixed evenly in a high-speed mixer and then added to a twin-screw extruder with a length-to-diameter ratio of 38:1 for melt mixing and dispersion. The mixture was then extruded and granulated to obtain a halogen-free flame-retardant polypropylene composite material. The temperature of the twin-screw extruder from the feeding section to the die head was 180℃, 180℃, 185℃, 185℃, 190℃, 190℃, 190℃, 195℃, 195℃, and 195℃, respectively.
[0039] Comparative Example 2
[0040] 76.3 parts of copolymer polypropylene PP BX3800 (SK Korea), 20 parts of halogen-free flame retardant FP-2200 (ADK Japan), 3 parts of expanded graphene, 0.2 parts of heat stabilizer 1010 (BASF), 0.2 parts of heat stabilizer 168 (BASF), and 0.4 parts of processing aid silicone masterbatch E525 (Evonik Germany) were mixed evenly in a high-speed mixer and then added to a twin-screw extruder with a length-to-diameter ratio of 38:1 for melt mixing and dispersion. The mixture was then extruded and granulated to obtain a halogen-free flame-retardant polypropylene composite material. The temperature of the twin-screw extruder from the feeding section to the die head was 180℃, 180℃, 185℃, 185℃, 190℃, 190℃, 190℃, 195℃, 195℃, and 195℃, respectively.
[0041] Comparative Example 3
[0042] 76.3 parts of copolymer polypropylene PP BX3800 (SK Korea), 20 parts of halogen-free flame retardant FP-2200 (ADK Japan), 3 parts of carbon black, 0.2 parts of heat stabilizer 1010 (BASF), 0.2 parts of heat stabilizer 168 (BASF), and 0.4 parts of processing aid silicone masterbatch E525 (Evonik Germany) were mixed evenly in a high-speed mixer and then added to a twin-screw extruder with a length-to-diameter ratio of 38:1 for melt mixing and dispersion. The mixture was then extruded and granulated to obtain a halogen-free flame-retardant polypropylene composite material. The temperature of the twin-screw extruder from the feeding section to the die head was 180℃, 180℃, 185℃, 185℃, 190℃, 190℃, 190℃, 195℃, 195℃, and 195℃, respectively.
[0043] Comparative Example 4
[0044] 75.3 parts of copolymer polypropylene PP BX3800 (SK Korea), 24 parts of halogen-free flame retardant FP-2200 (ADK Japan), 0.2 parts of heat stabilizer 1010 (BASF), 0.2 parts of heat stabilizer 168 (BASF), and 0.4 parts of processing aid silicone masterbatch E525 (Evonik Germany) were mixed evenly in a high-speed mixer and then added to a twin-screw extruder with a length-to-diameter ratio of 38:1 for melt mixing and dispersion. The mixture was then extruded and granulated to obtain a halogen-free flame-retardant polypropylene composite material. The temperature of the twin-screw extruder from the feeding section to the die head was 180℃, 180℃, 185℃, 185℃, 190℃, 190℃, 190℃, 195℃, 195℃, and 195℃, respectively.
[0045] Test case
[0046] The flame retardancy of materials was measured according to UL94 standard;
[0047] Tensile strength was tested according to ISO 527; flexural strength and flexural modulus were tested according to ISO 178.
[0048] The notched impact strength of the cantilever beam was tested according to ISO 180.
[0049] The test results of the materials in Examples 1-5 and Comparative Examples 1-4 are shown in Table 1.
[0050] Table 1 Performance Test Results
[0051]
[0052]
[0053] As can be seen from the table above, Comparative Example 1 only added flame retardant, while Comparative Example 3 added both flame retardant and carbon black, resulting in materials that were ultimately "non-flame retardant." Comparative Example 2 added expanded graphene, and compared to Example 1, the flame retardant performance significantly decreased, reaching only "V-1." Comparative Example 4 increased the amount of halogen-free flame retardant to 24%, finally achieving the same flame retardant performance as Example 1, but the mechanical properties of the material significantly decreased. In contrast, Example 1 achieved the same flame retardant effect with only 20% halogen-free flame retardant, meaning the amount of flame retardant used was reduced by 16%.
[0054] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0055] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.
Claims
1. A halogen-free flame-retardant polypropylene composite material, characterized in that, It is prepared by weight of 73-80.6 parts polypropylene, 17-22 parts halogen-free flame retardant, 2-4 parts magnesium hydroxide-coated expanded graphene, 0.2-0.6 parts heat stabilizer and 0.2-0.4 parts processing aid; the processing aid is a lubricant and the halogen-free flame retardant is a phosphorus-nitrogen intumescent flame retardant. The preparation steps of the magnesium hydroxide-coated expanded graphene are as follows: MgCl2•6H2O and expandable graphene were added to deionized water and stirred. The pH of the mixture was adjusted to 9-11. The reaction was heated to obtain magnesium hydroxide-coated expandable graphene. The mass ratio of MgCl2•6H2O to expandable graphene was 50:3-5.
2. The halogen-free flame-retardant polypropylene composite material as described in claim 1, characterized in that, The polypropylene is selected from at least one of copolymer polypropylene and homopolymer polypropylene.
3. The halogen-free flame-retardant polypropylene composite material as described in claim 1, characterized in that, The heating reaction is carried out at a temperature of 75-85°C for 6-12 hours.
4. The halogen-free flame-retardant polypropylene composite material as described in claim 1, characterized in that, The product after the heating reaction is filtered, washed 3-5 times with deionized water, dried in an oven at 50-60℃, and finally ground to obtain magnesium hydroxide-coated expanded graphene material.
5. The halogen-free flame-retardant polypropylene composite material as described in claim 1, characterized in that, The heat stabilizer is selected from at least one of hindered phenolic heat stabilizers, phosphite heat stabilizers, and thioester heat stabilizers.
6. The halogen-free flame-retardant polypropylene composite material as described in claim 1, characterized in that, The lubricant is selected from at least one of metal soaps and silicones.
7. A method for preparing a halogen-free flame-retardant polypropylene composite material as described in any one of claims 1-6, characterized in that, Includes the following steps: According to the weight parts, polypropylene, halogen-free flame retardant, magnesium hydroxide-coated expanded graphene, heat stabilizer and processing aid are thoroughly mixed to obtain a uniform mixture. The mixture is added to a twin-screw extruder, and after melt mixing, dispersion, extrusion granulation, flame-retardant polypropylene composite material is obtained.