High-strength recycled polypropylene composite material and preparation method thereof

Abstract

The application discloses a kind of high-strength recycled polypropylene composite material and preparation method thereof, belong to high polymer material field.A kind of recycled polypropylene composite material, including following weight parts raw materials: polypropylene 6~74.5 parts, recycled polypropylene 10~50 parts, initiator A 0.01~1 part, silane coupling agent A 1~5 parts, functionalized graphene 1~3 parts, wherein, the preparation method of functionalized graphene includes the following steps: graphene, silane coupling agent B, initiator B, PE powder are placed in toluene solvent according to mass ratio (10~20) / (2~10) / (0.1~0.5) / (69.5~87.9) respectively, and suspension is prepared, and the total mass of graphene, silane coupling agent B, initiator B, PE powder is 1 / (3~8) compared with toluene solvent;Suspension is magnetically stirred and heated to reflux;The functionalized graphene is obtained.The application adopts functionalized graphene material, and it is evenly grafted and distributed in composite material system, forms crosslinked network structure, and the mechanical properties of recycled polypropylene composite material are greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of high molecular materials, and in particular to a high-strength recycled polypropylene composite material and a preparation method thereof. BACKGROUND

[0002] Polypropylene (PP) is one of the five general-purpose plastics, which is widely used in many fields such as automobiles, home appliances, electronics, electric tools, and medical treatment due to its good physical, chemical, mechanical, and processing properties. However, a large amount of waste plastics has also been generated. In recent years, the global response to the carbon neutral policy has also begun, and thus the use of these waste plastics will become a future development theme. Since the source of recycled materials is generally the disassembly of scrap plastic parts, and the recycled materials are obtained by cleaning and granulation, the recycled materials are degraded by multiple processes, which also leads to the addition of recycled products, affecting the mechanical properties of the products, and thus affecting the further expansion of their application fields. In order to expand the recycling range of recycled polypropylene materials, the present application provides a high-strength recycled polypropylene composite material and a preparation method thereof. SUMMARY

[0003] In view of the deficiencies of the prior art, the present application provides a high-strength recycled polypropylene composite material and a preparation method thereof.

[0004] The object of the present application can be achieved by the following technical solutions.

[0005] In a first aspect, the present application relates to a recycled polypropylene composite material, comprising the following raw materials by weight:

[0006] Polypropylene 6-74.5 parts, recycled polypropylene 10-50 parts, initiator A 0.01-1 parts, silane coupling agent B 1-5 parts, functionalized graphene 1-3 parts,

[0007] The preparation method of the functionalized graphene comprises the following steps:

[0008] The graphene, silane coupling agent B, initiator B, and PE powder are placed in toluene solvent in a mass ratio of (10-20) / (2-10) / (0.1-0.5) / (69.5-87.9) respectively to prepare a suspension, and the total mass of the graphene, silane coupling agent B, initiator B, and PE powder is 1 / (3-8) times the mass of the toluene solvent.

[0009] The suspension is magnetically stirred and heated to reflux.

[0010] The suspension is subjected to solid-liquid separation, washing, and drying to obtain the functionalized graphene.

[0011] Optionally, the polypropylene is at least one of homopolymer polypropylene, propylene-ethylene block copolymer, propylene-ethylene random copolymer, propylene-1-butene random block.

[0012] Optionally, further comprising the following auxiliary materials by weight:

[0013] Inorganic filler 5-30 parts, toughening agent 2-15 parts, odor removal agent 0.5-2 parts and processing aid 0.5-3 parts.

[0014] Optionally, the processing aid is at least one of antioxidant, weathering agent, lubricant, toner.

[0015] Optionally, the particle size D50 of the graphene is ≤5um; the silane coupling agent A or B is at least one of vinyl silane coupling agent or allyl silane coupling agent; the initiator A or B is at least one of dicumyl peroxide (DCP), bis-tert-butyl peroxide diisopropyl benzene (BIPB), azobis isobutyronitrile (AIBN); the PE powder is at least one of LDPE, HDPE.

[0016] Optionally, the recycled polypropylene is at least one of household appliance shell disassembling granulation material, battery shell crushing granulation material, ton bag crushing granulation material.

[0017] Optionally, the PE powder is at least one of LDPE, HDPE.

[0018] Optionally, the inorganic filler is at least one of talc powder, whisker, mica, wollastonite, calcium carbonate.

[0019] Optionally, the toughening agent is at least one of POE, LDPE, HDPE, SEBS, EPDM.

[0020] Optionally, the odor removal agent is porous silicate.

[0021] The second aspect of the application relates to a preparation method of a polypropylene composite material, comprising the following steps:

[0022] The graphene, silane coupling agent B, initiator B and PE powder are placed in toluene solvent according to the mass ratio (10-20) / (2-10) / (0.1-0.5) / (69.5-87.9) respectively to prepare a suspension, and the total mass of the added graphene, silane coupling agent B, initiator B and PE powder is 1 / (3-8) times that of the toluene solvent.

[0023] The suspension is magnetically stirred and heated to reflux;

[0024] The suspension is subjected to solid-liquid separation, washing and drying to obtain functionalized graphene.

[0025] Polypropylene 6-74.5 parts by weight, recycled polypropylene 10-50 parts by weight, functionalized graphene 1-3 parts by weight, silane coupling agent A 1-5 parts by weight, initiator A 0.01-1 parts by weight are uniformly mixed, and the polypropylene composite material is obtained by melting, extrusion and cooling.

[0026] Further, the extrusion process is carried out in a twin-screw extruder, which is divided into ten zones from the feeding port to the die head, and the temperatures are 160-210 DEG C respectively; the rotation speed of the extruder is 300-500 rpm / min, double vacuum, and the vacuum degree is-0.07 to-0.03 MPa.

[0027] The beneficial effects of the present application are:

[0028] (1) The present application uses PE, silane coupling agent and initiator to treat the surface of graphene under certain conditions to obtain functionalized graphene powder. The active groups such as hydroxyl groups on the surface of graphene are grafted and crosslinked with PE molecular chains through silane to improve the compatibility of graphene and polypropylene resin, and also improve the dispersibility of graphene.

[0029] (2) In the process of twin-screw extrusion granulation, organic silane is used as a coupling agent, and melt extrusion is carried out in the presence of a free radical initiator. The double bond on the silane molecular chain is opened by PP macromolecular free radicals, and the unsaturated silane is grafted onto the PP chain. At the same time, the hydroxyl groups are generated by the hydrolysis of the alkoxy groups grafted on PP. Then, the silanol is dehydrated to form Si-O-Si bond, thereby crosslinking PP. In this process, the PE molecular chains grafted on the surface of functionalized graphene also participate in the crosslinking reaction, so that the graphene is uniformly grafted and distributed in the composite material system, forming a crosslinked network structure, and greatly improving the mechanical properties of the recycled polypropylene composite material. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0031] Unless otherwise specified, the raw materials and reagents used in the embodiments of the present application are commonly purchased raw materials and reagents.

[0032] Polypropylene, brand M60RHC, Zhenhai Refining and Chemical;

[0033] Recycled polypropylene, battery shell material, Jiangxi Greenmee;

[0034] Talc, 1250 mesh talc 90-20-A, Guangxi Longsheng Huamei Talc;

[0035] Toughening agent, POE, grade LC565, LG Chem;

[0036] Graphene, grade NO-C-068-1, Shanghai Naio Nanotechnology Co., Ltd.;

[0037] Porous silicate, grade JH-200A, with an average pore size of 5nm, produced by Ningbo Jiahe New Materials.

[0038] Other processing aids are commercially available conventional aids;

[0039] Silane coupling agent, vinyltriethoxysilane, brand name KH-151, Hangzhou Jessica Chemical Co., Ltd.

[0040] Initiator, DCP, Akzo.

[0041] Regarding initiators, it should be noted that although the initiators and silane coupling agents are distinguished in the invention description for clarity and limitation by initiator A and initiator B, and silane coupling agent A and silane coupling agent B (used in the preliminary preparation of functionalized graphene and in the preparation of polypropylene composite materials), in actual implementation, initiator A and initiator B, as well as silane coupling agent A and silane coupling agent B, can use the same components or different components.

[0042] The preparation process of a high-strength recycled polypropylene composite material is as follows:

[0043] S1. Graphene, silane coupling agent, initiator DCP, and PE powder are placed in toluene solvent in a mass ratio of 15 / 3 / 0.2 / 81.8 to prepare a suspension. The total mass of the added graphene, silane coupling agent, initiator DCP, and PE powder is 1 / 5 of the solid-liquid ratio of the toluene solvent. Magnetic stirring and reflux heating are then started for 2 hours. Finally, the prepared mixed suspension is placed in a solid-liquid separation device, cooled, filtered, washed with ethanol and water, dried, and ground to prepare functionalized graphene composite material powder.

[0044] S2. Polypropylene, recycled polypropylene, talc, toughening agent POE, deodorizing agent, functionalized graphene, silane coupling agent, initiator DCP, antioxidant 1010, antioxidant 168, lubricant calcium stearate, and black masterbatch are mixed evenly in proportion and placed in a twin-screw extruder for melting, extrusion, cooling, and granulation to obtain a high-strength recycled polypropylene composite material. The extruder is divided into ten zones from the feed port to the die head, with temperatures of 160℃, 210℃, 210℃, 210℃, 200℃, 200℃, 200℃, 200℃, 200℃, and 210℃ respectively in zones one through ten; the main extruder speed is 400 rpm / min, with double vacuum and a vacuum degree of -0.08 MPa.

[0045] The specific formulations for Examples 1-5 are shown in Table 1.

[0046] Table 1

[0047]

[0048]

[0049] Comparative Example 1

[0050] 36 parts polypropylene, 30 parts recycled polypropylene, 15 parts talc, 10 parts toughening agent POE, 1 part deodorizing agent, 3 parts graphene, 3 parts silane coupling agent, 0.2 parts initiator DCP, 0.2 parts antioxidant 1010, 0.3 parts lubricant calcium stearate, and 1 part black masterbatch were mixed evenly in a specific ratio and placed in a twin-screw extruder for melting, extrusion, cooling, and granulation to obtain a high-strength recycled polypropylene composite material. The extruder was divided into ten zones from the feed port to the die head, with temperatures of 160℃, 210℃, 210℃, 210℃, 200℃, 200℃, 200℃, 200℃, 200℃, and 210℃ respectively. The main extruder speed was 400 rpm / min, with double vacuum and a vacuum degree of -0.08 MPa.

[0051] Comparative Example 2

[0052] S1. Graphene, initiator DCP, and PE powder are placed in toluene solvent at a mass ratio of 15 / 0.2 / 84.8 to prepare a suspension, wherein the total mass of the added graphene, initiator DCP, and PE powder is 1 / 5 of the solid-liquid ratio of the toluene solvent; magnetic stirring and reflux are started for 2 hours; finally, the prepared mixed suspension is placed in a solid-liquid separation device, cooled, filtered, washed with ethanol and water, dried, and ground to prepare surface-modified graphene composite material powder;

[0053] S2. Mix 36 parts polypropylene, 30 parts recycled polypropylene, 15 parts talc, 10 parts toughening agent POE, 1 part deodorizing agent, 3 parts functionalized graphene, 3 parts silane coupling agent, 0.2 parts initiator DCP, 0.2 parts antioxidant 1010, 0.3 parts lubricant calcium stearate, and 1 part black masterbatch in a specific ratio until homogeneous. Place the mixture in a twin-screw extruder, melt, extrude, cool, and granulate to obtain a high-strength recycled polypropylene composite material. The extruder is divided into ten zones from the feed port to the die head. The temperatures of zones one through ten are 160℃, 210℃, 210℃, 210℃, 200℃, 200℃, 200℃, 200℃, and 210℃, respectively. The main extruder speed is 400 rpm / min, with double vacuum and a vacuum degree of -0.08 MPa.

[0054] Comparative Example 3

[0055] S1. Graphene, silane coupling agent, and PE powder are placed in toluene solvent at a mass ratio of 15 / 3 / 82 to prepare a suspension, wherein the total mass of the added graphene, silane coupling agent, and PE powder is 1 / 5 of the solid-liquid ratio of the toluene solvent; magnetic stirring and reflux heating are started for 2 hours; finally, the prepared mixed suspension is placed in a solid-liquid separation device, cooled, filtered, washed with ethanol and water, dried, and ground to prepare surface-modified graphene composite material powder;

[0056] S2. Polypropylene 36 powder, 30 parts recycled polypropylene, 15 parts talc, 10 parts toughening agent POE, 1 part deodorizing agent, 3 parts functionalized graphene, 3 parts silane coupling agent, 0.2 parts initiator DCP, 0.2 parts antioxidant 1010, 0.3 parts lubricant calcium stearate, and 1 part black masterbatch are mixed evenly in a specified ratio and placed in a twin-screw extruder. The mixture is then melted, extruded, cooled, and granulated to obtain a high-strength recycled polypropylene composite material. The extruder is divided into ten zones from the feed port to the die head. The temperatures of zones one through ten are 160℃, 210℃, 210℃, 210℃, 200℃, 200℃, 200℃, 200℃, and 210℃, respectively. The main extruder speed is 400 rpm / min, with double vacuum and a vacuum degree of -0.08 MPa.

[0057] Comparative Example 4

[0058] S1. Graphene, silane coupling agent, initiator DCP, and PE powder are placed in toluene solvent in a mass ratio of 15 / 3 / 0.2 / 81.8 to prepare a suspension. The total mass of the added graphene, silane coupling agent, initiator DCP, and PE powder is 1 / 5 of the solid-liquid ratio of the toluene solvent. Magnetic stirring and reflux heating are then started for 2 hours. Finally, the prepared mixed suspension is placed in a solid-liquid separation device, cooled, filtered, washed with ethanol and water, dried, and ground to prepare surface-modified graphene composite material powder.

[0059] S2. Mix 36 parts polypropylene, 30 parts recycled polypropylene, 15 parts talc, 10 parts toughening agent POE, 1 part deodorizing agent, 3 parts functionalized graphene, 3 parts silane coupling agent, 0.2 parts antioxidant 1010, 0.3 parts lubricant calcium stearate, and 1 part black masterbatch in a specific ratio until homogeneous. Place the mixture in a twin-screw extruder, melt, extrude, cool, and granulate to obtain a high-strength recycled polypropylene composite material. The extruder is divided into ten zones from the feed port to the die head. The temperatures of zones one through ten are 160℃, 210℃, 210℃, 210℃, 200℃, 200℃, 200℃, 200℃, and 210℃, respectively. The main extruder speed is 400 rpm / min, with double vacuum and a vacuum degree of -0.08 MPa.

[0060] Comparative Example 5

[0061] S1. Graphene, silane coupling agent, initiator, and PE powder are placed in toluene solvent in a mass ratio of 15 / 3 / 0.2 / 81.8 to prepare a suspension. The total mass of the added graphene, silane coupling agent, initiator DCP, and PE powder is 1 / 5 of the solid-liquid ratio of the toluene solvent. Magnetic stirring and reflux heating are started for 2 hours. Finally, the prepared mixed suspension is placed in a solid-liquid separation device, cooled, filtered, washed with ethanol and water, dried, and ground to prepare surface-modified graphene composite material powder.

[0062] S2. Mix 36 parts polypropylene, 30 parts recycled polypropylene, 15 parts talc, 10 parts toughening agent POE, 1 part deodorizing agent, 3 parts functionalized graphene, 0.2 parts initiator DCP, 0.2 parts antioxidant 1010, 0.3 parts lubricant calcium stearate, and 1 part black masterbatch in a specific ratio until homogeneous. Place the mixture in a twin-screw extruder, melt, extrude, cool, and granulate to obtain a high-strength recycled polypropylene composite material. The extruder is divided into ten zones from the feed port to the die head. The temperatures of zones one through ten are 160℃, 210℃, 210℃, 210℃, 200℃, 200℃, 200℃, 200℃, and 210℃, respectively. The main extruder speed is 400 rpm / min, with double vacuum and a vacuum degree of -0.08 MPa.

[0063] The recycled polypropylene composite materials obtained in Examples 1-5 and Comparative Examples 1-5 were subjected to tests for tensile strength, flexural strength, flexural modulus, and notched impact strength. It is worth noting that these tests are familiar to those skilled in the art, and the specific testing methods are not detailed here. The test results are shown in Table 2 below:

[0064] Table 2

[0065]

[0066] As can be seen from the data in Table 2 above, the recycled polypropylene composite material prepared by this invention through crosslinking reaction of functionalized graphene prepared in a specific manner with the polypropylene system, as well as through self-crosslinking between polypropylene itself, exhibits excellent tensile strength, flexural strength, flexural modulus, and impact strength. From Example 3 and Comparative Examples 1 and 2, it can be seen that when the functionalized graphene prepared in the specific manner is not added, the mechanical properties of the final recycled polypropylene composite material are significantly reduced. Furthermore, according to Example 3 and Comparative Examples 4 and 5, if sufficient crosslinking reaction cannot occur between polypropylene resins and between polypropylene resin and functionalized graphene during melt extrusion to form a network structure, the mechanical strength of the composite material cannot achieve superior performance. Based on the above summary, compared with the comparative examples, this invention significantly improves the mechanical properties of the recycled polypropylene composite material system. Therefore, the recycled polypropylene composite material prepared by this invention can be adapted to meet customer needs by expanding its performance range.

[0067] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0068] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A recycled polypropylene composite material, characterized in that, Including the following parts by weight of raw materials: Polypropylene 6-74.5 parts, recycled polypropylene 10-50 parts, initiator A 0.01-1 part, silane coupling agent A 1-5 parts, Functionalized graphene 1-3 parts, The preparation method of the functionalized graphene includes the following steps: Graphene, silane coupling agent B, initiator B, and PE powder were placed in toluene solvent at a mass ratio of (10~20) / (2~10) / (0.1~0.5) / (69.5~87.9) to prepare a suspension. The total mass of graphene, silane coupling agent B, initiator B, and PE powder was added to the toluene solvent at a ratio of 1 / (3~8). The suspension is magnetically stirred and heated under reflux. The functionalized graphene is then obtained through solid-liquid separation, washing, and drying. The graphene particle size D50 ≤ 5 μm; the silane coupling agent A and silane coupling agent B are selected from at least one of vinyl silane coupling agent or allyl silane coupling agent; the initiator A and initiator B are selected from at least one of dicumyl peroxide, di-tert-butyl peroxide, and azobisisobutyronitrile.

2. The polypropylene composite material according to claim 1, characterized in that, The polypropylene is at least one of homopolymer polypropylene, propylene-ethylene block copolymer, propylene-ethylene random copolymer, and propylene-1-butene random block copolymer.

3. The polypropylene composite material according to claim 1, characterized in that, It also includes the following excipients by weight: 5-30 parts inorganic filler, 2-15 parts toughening agent, 0.5-2 parts deodorizing agent, and 0.5-3 parts processing aid.

4. The polypropylene composite material according to claim 3, characterized in that, The processing aid is at least one of antioxidants, weather resistant agents, lubricants, and colorants.

5. The polypropylene composite material according to claim 1, characterized in that, The PE powder is at least one of LDPE and HDPE.

6. The polypropylene composite material according to claim 3, characterized in that, The inorganic filler is at least one of talc, whiskers, mica, wollastonite, and calcium carbonate.

7. The polypropylene composite material according to claim 3, characterized in that, The toughening agent is at least one of POE, SEBS, and EPDM.

8. The polypropylene composite material according to claim 3, characterized in that, The deodorizing agent is a porous silicate.

9. A method for preparing the recycled polypropylene composite material according to any one of claims 1 to 8, characterized in that, Includes the following steps: A suspension was prepared by placing graphene, silane coupling agent B, initiator B, and PE powder in toluene solvent at a mass ratio of (10~20) / (2~10) / (0.1~0.5) / (69.5~87.9). The total mass ratio of the added graphene, silane coupling agent B, initiator B, and PE powder to the toluene solvent was 1 / (3~8). The suspension is magnetically stirred and heated under reflux. Functionalized graphene is then obtained through solid-liquid separation, washing, and drying. The polypropylene composite material is obtained by uniformly mixing 6-74.5 parts by weight of polypropylene, 10-50 parts by weight of recycled polypropylene, 1-3 parts by weight of functionalized graphene, 1-5 parts by weight of silane coupling agent A, and 0.01-1 parts by weight of initiator A, followed by melting, extrusion, and cooling.

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