Method for recycling mixed plastic and composite plastic

Abstract

The invention provides a method for recycling mixed plastic and composite plastic, and belongs to the technical field of compositions of high-molecular compounds. The method for recycling the mixed plastic comprises the following steps: uniformly mixing 100 parts by weight of mixed plastic, 1-5 parts by weight of a grafting functional monomer, 1-5 parts by weight of a grafting co-monomer and 0.1-0.3 part by weight of an initiator to obtain a mixed material; conveying the mixed material into a double-screw extruder for reactive blending extrusion to obtain composite plastic; wherein the mixed plastic is a mixture of at least two different plastics, the grafting functional monomer is as defined in the specification M1-M7, and under the condition that the grafting functional monomer is M7, the initiator and the grafting co-monomer are 0 part.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer compound compositions, and more particularly relates to a method for recycling and reusing mixed plastics and composite plastics. Background Art

[0002] Due to the many excellent properties of polyolefins, which are applied to various aspects of daily life, their large annual output and extensive use in disposable packaging have become the main components of post-consumer plastic waste. The production and consumption of polyolefins have caused a serious environmental burden, and recycling waste plastics is of great significance.

[0003] In practical applications, most plastics used in packaging, molds, and building applications exist in the form of mixed plastics. Traditional recycling mainly has two approaches: mechanical recycling and chemical recycling. Among them, side reactions including degradation and crosslinking will cause serious damage to the material properties, resulting in product quality being lower than that of the original material; the method of catalytic cracking to recycle polyolefins has problems such as low energy efficiency, poor product selectivity, and environmental pollution. In addition, due to the poor compatibility of different plastics, there is phase separation between mixed plastics, and the interfacial adhesion is weak, resulting in the performance of recycled materials being reduced by mixed plastic waste, making it difficult to directly recycle and reuse. Summary of the Invention

[0004] In view of the above technical problems, the present invention provides a method for recycling and reusing mixed plastics and composite plastics, in order to at least partially solve the above technical problems. For this, the technical solutions provided by the present invention are as follows.

[0005] As a first aspect of the present invention, a method for recycling and reusing mixed plastics is provided, including: by weight, mixing 100 parts of mixed plastics, 1 - 5 graft functional monomers, 1 - 5 parts of graft comonomers, and 0.1 - 0.3 parts of initiator evenly to obtain a mixed material; conveying the mixed material into a twin-screw extruder for reactive melt blending and extrusion to obtain composite plastics; wherein, the mixed plastics are a mixture of at least two different plastics, and the graft functional monomer is selected from any one of the following: M1, M2, M3, M4, M5, M6, M7, and when the graft functional monomer is M7, both the initiator and the graft comonomer are 0 parts.

[0006] As a second aspect of the present invention, a composite plastic prepared by using the above method for recycling and reusing mixed plastics is provided.

[0007] Based on the above technical solution, the method for recycling and reusing hybrid plastics provided by the present invention, and the composite plastics have at least one of the following beneficial effects:

[0008] (1) In the embodiments of the present invention, in the presence of an initiator, graft-functional monomers can be grafted onto the hybrid plastics, and the presence of graft comonomers can increase the grafting rate of the graft-functional monomers. By using a mixed material containing hybrid plastics, graft-functional monomers, graft comonomers, and an initiator, through a reactive twin-screw extrusion processing system, composite plastics can be obtained without additional post-treatment steps. Compared with the original hybrid plastics without graft-functional monomers, the mechanical properties such as tensile strength, elongation at break, and toughness of the obtained composite plastics are significantly improved, and the recycling rate of waste hybrid plastics is increased.

[0009] (2) Under the action of an initiator, the double bonds in the M1-M6 graft-functional monomers can be grafted onto the chain segments of different plastic polymers. The quadruple hydrogen bond unit ureidopyrimidinone (UPy) functional groups contained at the other end of the M1 and M2 graft-functional monomers have strong binding energy and can form an interlocked structure pairwise; the M3-M6 graft-functional monomers contain carboxyl and catechol group functional groups, which also have strong binding energy with Fe 3+ metal ions and can form an interlocked structure, thereby forming a new domain at the two-phase interface. Good interfacial interaction and dispersion effect improve the compatibility of the hybrid plastics, thus constructing a good blend system and improving the performance of the composite plastics. For the M7 graft-functional monomer, without the participation of an initiator and graft comonomers, the epoxy and hydroxyl groups in M7 can react with the hydroxyl or carboxyl groups at the chain ends of polar polymers, thereby being grafted onto the polymer chain. The quadruple hydrogen bond unit ureidopyrimidinone (UPy) (i.e., supramolecular structural unit) contained in M7 can form an interlocked structure pairwise, thereby improving the compatibility of the hybrid plastics.

[0010] (3) By grafting graft-functional monomers onto different plastics, a dynamic crosslinked network can be formed using the structure of the graft-functional monomers. While achieving compatibilization of various different plastics, it is also possible to perform multiple processing on the finally obtained composite plastics, and the composite plastics still have excellent mechanical properties after multiple processing. Description of the Drawings

[0011] Figure 1 Stress-strain curves of the composite plastics in Comparative Example 1, Example 1, and Example 2 prepared from hybrid plastics composed of polyethylene (PE) / polypropylene (PP) (70 / 30);

[0012] Figure 2 Stress-strain curves of the composite plastics in Comparative Example 2, Example 3, and Example 4 prepared from hybrid plastics composed of polyethylene (PE) / polypropylene (PP) (50 / 50);

[0013] Figure 3 Prepare the stress-strain curves of the composite plastics in Comparative Example 3, Example 5, and Example 6 from the mixed plastic composed of polyethylene (PE) / polypropylene (PP) (30 / 70).

[0014] Figure 4 Prepare the stress-strain curves of the composite plastics in Comparative Example 4 and Example 7 from the mixed plastic composed of polyethylene (PE) / polypropylene (PP) / ethylene-octene copolymer (POE) (65 / 30 / 5).

[0015] Figure 5 Prepare the stress-strain curves of the composite plastics in Comparative Example 5 and Example 8 from the mixed plastic composed of polyethylene (PE) / polystyrene (PS) (70 / 30).

[0016] Figure 6 Prepare the stress-strain curves of the composite plastics in Comparative Example 6 and Example 9 from the mixed plastic composed of polyethylene (PE) / polyamide (PA) (70 / 30).

[0017] Figure 7 Prepare the stress-strain curves of the composite plastics in Comparative Example 7 and Example 10 from the mixed plastic composed of polyethylene (PE) / thermoplastic polyurethane elastomer (TPU) (70 / 30).

[0018] Figure 8 Prepare the stress-strain curves of the composite plastics in Comparative Example 8 and Example 11 from the mixed plastic composed of polyethylene (PE) / polycaprolactone (PCL) (70 / 30).

[0019] Figure 9 Prepare the stress-strain curves of the composite plastics in Comparative Example 9 and Example 12 from the mixed plastic composed of polyethylene (PE) / polylactic acid (PLA) (70 / 30).

[0020] Figure 10 Prepare the stress-strain curves of the composite plastics in Comparative Example 10 and Example 13 from the mixed plastic composed of polypropylene (PP) / polylactic acid (PLA) (70 / 30).

[0021] Figure 11 Prepare the stress-strain curves of the composite plastics in Comparative Example 1, Example 14, and Example 15 from the mixed plastic composed of polyethylene (PE) / polypropylene (PP) (70 / 30).

[0022] Figure 12Prepare the stress-strain curves of the composite plastics in Comparative Example 1, Example 16, and Example 17 from a mixed plastic composed of polyethylene (PE) / polypropylene (PP) (70 / 30).

[0023] Figure 13 Prepare the stress-strain curves of the composite plastics in Comparative Example 11 and Example 18 from a mixed plastic composed of polyethylene terephthalate (PET) / polycarbonate (PC) (70 / 30).

[0024] Figure 14 Prepare the stress-strain curves of the composite plastics in Comparative Example 12 and Example 19 from a mixed plastic composed of polylactic acid (PLA) / polybutylene succinate (PBS) (70 / 30).

[0025] Figure 15 Prepare the stress-strain curves of the composite plastics in Comparative Example 13 and Example 20 from a mixed plastic composed of polylactic acid (PLA) / polyamide (PA) (70 / 30).

[0026] Figure 16 and Figure 19 The scanning electron microscope (SEM) image and atomic force microscope (AFM) image of the composite plastic prepared from polyethylene (PE) / polypropylene (PP) (PE / PP 70 / 30) in Comparative Example 1 are shown respectively;

[0027] Figure 17 and Figure 20 The SEM image and AFM image of composite plastic A in Example 1 are shown respectively;

[0028] Figure 18 and Figure 21 The SEM image and AFM image of composite plastic B in Example 2 are shown respectively. Detailed implementation manners

[0029] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In the following detailed description, for the sake of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present invention. However, obviously, one or more embodiments can be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0030] In the process of implementing the inventive concept, it is found that the incompatibility of different plastic polymers leads to phase separation between the mixed plastics and weak interfacial adhesion, resulting in a decline in the performance of the mixed plastics. In addition, there is a wide variety of commercial plastic polymers, and the composition of plastic polymers is relatively complex, resulting in a relatively complex composition of the waste mixed plastics generated. For example, it includes mixed plastics composed of polar plastics and non-polar plastics, mixed plastics composed of non-polar plastics and non-polar plastics, and mixed plastics composed of polar plastics and polar plastics. It is difficult to improve the compatibility between different plastics by a general method, and thus it is difficult to achieve the upgraded recycling of different plastics. In this regard, the present invention provides a method for recycling and reusing mixed plastics. By introducing graft functional monomers M1-M7, the compatibility between different plastics is improved, and the upgraded recycling of mixed plastics with different polarities or the same polarity is achieved.

[0031] Specifically, as the first aspect of the present invention, a method for recycling and reusing mixed plastics is provided, including: by weight, mixing 100 parts of mixed plastics, 1-5 graft functional monomers, 1-5 parts of graft comonomers, and 0.1-0.3 parts of initiator evenly to obtain a mixed material; conveying the mixed material into a twin-screw extruder for reactive co-blending and extrusion to obtain a composite plastic; wherein, the mixed plastics are a mixture of at least two different plastics, and the graft functional monomer is selected from any one of the following: M1, M2, M3, M4, M5, M6, M7. In the case where the graft functional monomer is M7, both the initiator and the graft comonomer are 0 parts.

[0032] In an embodiment of the present invention, in the presence of an initiator, a graft functional monomer can be grafted onto the mixed plastic, and the presence of a graft comonomer can increase the grafting rate of the graft functional monomer. By using a reactive twin-screw extrusion processing system with a mixed material comprising a mixed plastic, a graft functional monomer, a graft comonomer, and an initiator, and without the need for additional post-treatment steps, a composite plastic can be obtained. Compared with the original mixed plastic without grafted functional monomers, the mechanical properties such as tensile strength, elongation at break, and toughness of the obtained composite plastic are significantly improved, and the utilization rate of waste mixed plastic is increased. The double bonds contained in the graft functional monomers M1-M6 can be grafted onto the chain segments of different plastic polymers, and the functional groups in the graft functional monomers M1-M6 can form supramolecular structural units pairwise (the supramolecular hydrogen bond is formed between M1-M2, and the ionic bond is formed between M3-M6). The good interfacial interaction and dispersion effect improve the compatibility between different plastics, thereby constructing a good blend system. For the graft functional monomer M7, without the participation of an initiator and a graft comonomer, the epoxy and hydroxyl groups in M7 can react with the hydroxyl or carboxyl groups at the chain ends of polar polymers, thereby being grafted onto the polymer chain. The supramolecular structural units (i.e., supramolecular hydrogen bonds) contained in M7 can also form an interlocking structure, thereby improving the compatibility of the mixed plastic. In addition, when the graft functional monomer is grafted onto different plastics, a dynamic crosslinked network can be formed by using the graft functional monomer, which can not only achieve the compatibilization of various different plastics, but also enable the final obtained composite plastic to be processed multiple times, and still have excellent mechanical properties after multiple processing.

[0033] According to an embodiment of the present invention, when the graft functional monomer is selected from any one of M3-M6, the method for recycling and reusing the mixed plastic further includes: adding ferric chloride and blending it with the mixed plastic, the graft comonomer, and the initiator; wherein, by weight, the ferric chloride is 0.1-0.5 parts.

[0034] In an embodiment of the present invention, the added ferric chloride can form a metal coordination bond with the carboxyl or catechol group contained in the graft functional monomer in M3-M6. The graft functional monomer is grafted onto the chain segments of different polymers, and a dynamic crosslinked network can also be formed by using this metal coordination bond, realizing the compatibilization of different plastics, and also improving the mechanical properties such as tensile strength, elongation at break, and toughness of the final composite plastic.

[0035] According to an embodiment of the present invention, if the addition amounts of the graft functional monomer and the graft comonomer are too much, monomer self-polymerization will occur, and the compatibility cannot be improved; if they are too little, the graft reaction will be difficult to proceed; if the ferric chloride content is too much, it will agglomerate in the polymer, and if it is too little, a supramolecular interlocking structure cannot be formed.

[0036] For example: In some embodiments, by weight parts, the method for preparing composite plastics by recycling mixed plastics includes: 100 parts of mixed plastics, 1 - 5 parts of graft functional monomer (M1), 1 - 5 parts of graft comonomer, and 0.1 - 0.3 parts of initiator.

[0037] In some embodiments, by weight parts, the method for preparing composite plastics by recycling mixed plastics includes: 100 parts of mixed plastics, 1 - 5 parts of graft functional monomer (M2), 1 - 5 parts of graft comonomer, and 0.1 - 0.3 parts of initiator.

[0038] In other embodiments, by weight parts, the method for preparing composite plastics by recycling mixed plastics includes: 100 parts of mixed plastics, 1 - 5 parts of graft functional monomer (M3), 1 - 5 parts of graft comonomer, 0.1 - 0.3 parts of initiator, and 0.1 - 0.5 parts of ferric trichloride.

[0039] In other embodiments, by weight parts, the method for preparing composite plastics by recycling mixed plastics includes: 100 parts of mixed plastics, 1 - 5 parts of graft functional monomer (M4), 1 - 5 parts of graft comonomer, 0.1 - 0.3 parts of initiator, and 0.1 - 0.5 parts of ferric trichloride.

[0040] In other embodiments, by weight parts, the method for preparing composite plastics by recycling mixed plastics includes: 100 parts of mixed plastics, 1 - 5 parts of graft functional monomer (M5), 1 - 5 parts of graft comonomer, 0.1 - 0.3 parts of initiator, and 0.1 - 0.5 parts of ferric trichloride.

[0041] In other embodiments, by weight parts, the method for preparing composite plastics by recycling mixed plastics includes: 100 parts of mixed plastics, 1 - 5 parts of graft functional monomer (M6), 1 - 5 parts of graft comonomer, 0.1 - 0.3 parts of initiator, and 0.1 - 0.5 parts of ferric trichloride.

[0042] In some embodiments, by weight parts, the method for preparing composite plastics by recycling mixed plastics includes: 100 parts of mixed plastics, 1 - 5 parts of graft functional monomer (M7).

[0043] According to the embodiments of the present invention, the mixed plastics are a mixture of at least two plastics selected from A polar plastics, B polar plastics, C non - polar plastics, and D non - polar plastics; wherein, A polar plastics and B polar plastics are each independently and differently selected from at least one of polyamide, polycaprolactone, polyurethane, polylactic acid, polyethylene terephthalate, polycarbonate, and polybutylene succinate; C non - polar plastics and D non - polar plastics are each independently and differently selected from at least one of poly C2 - C8 olefins, copolymers of C2 - C8 olefins and C2 - C8 olefins.

[0044] According to an embodiment of the present invention, in 100 parts of the mixed plastic, the weight ratio of any two plastics is 30:70 - 70:30, the weight ratio of any three plastics is 65:30:5 - 5:30:65, and the weight ratio of any four plastics is 60:30:5:5 - 5:5:30:60.

[0045] Specifically, the mixed plastic composed of non-polar plastics and non-polar plastics includes: the mixed plastic of polyethylene (PE) and polypropylene (PP); the mixed plastic of polyethylene (PE), polypropylene (PP) and ethylene-octene copolymer (POE); the mixed plastic of polyethylene (PE) and polystyrene (PS). Further, by weight, in 100 parts of the mixed plastic, the weight ratio of polyethylene (PE) and polypropylene (PP) can be 70:30, 50:50, 30:70, which can be expressed as PE / PP70 / 30, PE / PP50 / 50, PE / PP30 / 70. By weight, in 100 parts of the mixed plastic, the weight ratio of polyethylene (PE), polypropylene (PP) and ethylene-octene copolymer (POE) can be 65:30:5, which can be expressed as PE / PP / POE65 / 30 / 5. By weight, in 100 parts of the mixed plastic, the weight ratio of polyethylene (PE) and polystyrene (PS) can be 70:30, which can be expressed as PE / PS70 / 30.

[0046] Mixed plastics composed of non-polar plastics and polar plastics, including: mixed plastics of polyethylene (PE) and polyamide (PA); mixed plastics of polyethylene (PE) and polycaprolactone (PCL); mixed plastics of polyethylene (PE) and thermoplastic polyurethane elastomer (TPU); mixed plastics of polyethylene (PE) and polylactic acid (PLA); mixed plastics of polypropylene (PP) and polylactic acid (PLA). Further, by weight, in 100 parts of the mixed plastics, the weight ratio of polyethylene (PE) and polyamide (PA) is 70:30, 50:50, 30:70, which can be expressed as PE / PA70 / 30, PE / PA50 / 50, PE / PA30 / 70. By weight, in 100 parts of the mixed plastics, the weight ratio of polyethylene (PE) and polycaprolactone (PCL) is 70:30, 50:50, 30:70, which can be expressed as PE / PCL70 / 30, PE / PCL50 / 50, PE / PCL30 / 70. By weight, in 100 parts of the mixed plastics, the weight ratio of polyethylene (PE) and thermoplastic polyurethane elastomer (TPU) is 70:30, 50:50, 30:70, which can be expressed as PE / TPU70 / 30, PE / TPU50 / 50, PE / TPU30 / 70. By weight, in 100 parts of the mixed plastics, the mixing ratio of polyethylene (PE) and polylactic acid (PLA) is 70:30, 50:50, 30:70, which can be expressed as PE / PLA70 / 30, PE / PLA50 / 50, PE / PLA30 / 70. By weight, in 100 parts of the mixed plastics, the weight ratio of polypropylene (PP) and polylactic acid (PLA) is 70:30, 50:50, 30:70, which can be expressed as PP / PLA70 / 30, PP / PLA50 / 50, PP / PLA30 / 70.

[0047] Mixed plastics composed of polar plastics and polar plastics, including: mixed plastics of polyethylene terephthalate (PET) / polycarbonate (PC); mixed plastics of polylactic acid (PLA) and polybutylene succinate (PBS); mixed plastics of polylactic acid (PLA) and polyamide (PA). Further, by weight, in 100 parts of the mixed plastics, the weight ratio of polyethylene terephthalate (PET) and polycarbonate (PC) is 70:30, which can be expressed as PET / PC70 / 30. By weight, in 100 parts of the mixed plastics, the weight ratio of polylactic acid (PLA) / polybutylene succinate (PBS) is 70:30, which can be expressed as PLA / PBS70 / 30. By weight, in 100 parts of the mixed plastics, the weight ratio of polylactic acid (PLA) / polyamide (PA) is 70:30, which can be expressed as PLA / PA70 / 30.

[0048] According to an embodiment of the present invention, the graft co-monomer is selected from , , , , any one of them. The double bond contained in the graft co-monomer promotes the grafting of the graft functional monomer onto the plastic polymer under the action of the initiator. In addition, during the free radical grafting reaction, the graft co-monomer combines with free radicals (initiator) first, which can effectively inhibit the breakage and degradation of the plastic polymer chains.

[0049] According to an embodiment of the present invention, the initiator is selected from at least one of dicumyl peroxide, benzoyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, and azobisisobutyronitrile. In the present invention, the initiator is mainly used to initiate the grafting of the graft functional monomer onto the mixed plastic through a grafting reaction.

[0050] According to an embodiment of the present invention, before the mixed plastic is blended, it is dried at 60 - 100 °C for 4 - 8 h to remove the moisture in the mixed plastic.

[0051] According to an embodiment of the present invention, the mixed plastic is conveyed into a twin-screw extruder for reactive blending, where the reactive blending is carried out at 150 - 260 °C at 60 - 100 r / min for 5 - 10 min to make the mixed plastic, the graft functional monomer, the graft co-monomer, and the initiator mix uniformly, and at the same time, a grafting reaction occurs to form a composite plastic.

[0052] According to an embodiment of the present invention, the reactive blending and extrusion are repeated 3 - 5 times. In the embodiment of the present invention, due to the presence of the quadruple hydrogen bond unit ureidopyrimidinone (UPy) in the M1 - M2 and M7 graft functional monomers, stable supramolecular hydrogen bonds can be formed. When the graft functional monomer is grafted onto the mixed plastic, a dynamic crosslinked network can be constructed, enabling compatibilization while allowing multiple reactive blending and extrusion processes. Alternatively, by using the metal coordination bonds formed by the added ferric chloride with the carboxyl or catechol groups in the M3 - M6 graft functional monomers, when the graft functional monomer is grafted onto the mixed plastic, a dynamic crosslinked network can also be constructed, enabling compatibilization while allowing multiple reactive blending and extrusion processes.

[0053] Specifically, in some embodiments of the present invention, the method for recycling and reusing mixed plastics includes: putting the mixed plastics into a vacuum oven and drying them at a temperature of 60 - 100°C for 4 - 8 hours for later use. Subsequently, by weight, 100 parts of the dried mixed plastics are evenly stirred with 1 - 5 parts of graft functional monomers (M1 or M2), 1 - 5 parts of graft comonomers, and 0.1 - 0.3 parts of initiator to obtain a mixed material. The mixed material is added into a twin-screw extruder and subjected to melt reactive blending at 150 - 260°C and 60 - 100 r / min for 5 - 10 minutes. The mixture after melt reactive blending is placed in a vacuum press and molded at 150 - 260°C to obtain composite plastics.

[0054] Specifically, in some other embodiments of the present invention, the method for recycling and reusing mixed plastics includes: putting the mixed plastics into a vacuum oven and drying them at a temperature of 60 - 100°C for 4 - 8 hours for later use. Subsequently, by weight, 100 parts of the dried mixed plastics are evenly stirred with 1 - 5 parts of graft functional monomers (M3 - M6), 1 - 5 parts of graft comonomers, 0.1 - 0.3 parts of initiator, and 0.1 - 0.5 parts of ferric chloride to obtain a mixed material. The mixed material is added into a twin-screw extruder and subjected to melt reactive blending at 150 - 260°C and 60 - 100 r / min for 5 - 10 minutes. Finally, the mixture after melt reactive blending is placed in a vacuum press and molded at 150 - 260°C to obtain composite plastics.

[0055] As the second aspect of the present invention, there is provided a composite plastic prepared by the method in the above embodiments.

[0056] In the embodiments of the present invention, compared with the original mixed plastics (i.e., mixed plastics without graft functional monomers), the mechanical properties such as tensile strength, elongation at break, and toughness of the composite plastics obtained by reactive extrusion using the above method are significantly improved, the utilization rate of waste mixed plastics is increased, and at the same time, it helps to broaden the application fields of mixed plastics.

[0057] The following will specifically describe the method for recycling and reusing mixed plastics and the composite plastics of the present invention in combination with specific examples and drawings.

[0058] The test materials and reagents used in the following examples, unless otherwise specified, can all be obtained from commercial channels. For those not specifying specific techniques or conditions in the examples, they can all be carried out according to the techniques or conditions described in the literature in this field or according to the product specifications.

[0059] Example 1

[0060] Composite plastic A was prepared by a method of recycling and reusing mixed plastics. By weight, it included: drying 100 parts of mixed plastics (70 wt% PE and 30 wt% PP, abbreviated as PE / PP 70 / 30) in a vacuum oven at 80 °C for 6 h. Subsequently, the dried mixed plastics were uniformly mixed with 2 parts of graft functional monomer (M1), 2 parts of graft comonomer (styrene), and 0.2 part of initiator (diisopropylbenzene peroxide), added into a twin-screw extruder, and reactive blending was carried out at 180 °C and a rotation speed of 80 r / min for 10 min. Finally, the mixture after reactive mixing was placed in a vacuum press and molded at 180 °C to obtain composite plastic A.

[0061] Example 2

[0062] Composite plastic B was prepared by a method of recycling and reusing mixed plastics. By weight, it included: drying 100 parts of mixed plastics (70 wt% PE and 30 wt% PP, abbreviated as PE / PP 70 / 30) in a vacuum oven at 80 °C for 6 h. Subsequently, the dried mixed plastics were uniformly mixed with 2 parts of graft functional monomer (M2), 2 parts of graft comonomer (styrene), and 0.2 part of initiator (diisopropylbenzene peroxide), added into a twin-screw extruder, and reactive blending was carried out at 180 °C and a rotation speed of 80 r / min for 10 min. Finally, the mixture after reactive mixing was placed in a vacuum press and molded at 180 °C to obtain composite plastic B.

[0063] Example 3

[0064] Composite plastic C was prepared by a method of recycling and reusing mixed plastics. By weight, it included: drying 100 parts of mixed plastics (50 wt% PE and 50 wt% PP, abbreviated as PE / PP 50 / 50) in a vacuum oven at 80 °C for 6 h. Subsequently, the dried mixed plastics were uniformly mixed with 2 parts of graft functional monomer (M1), 2 parts of graft comonomer (styrene), and 0.2 part of initiator (diisopropylbenzene peroxide), added into a twin-screw extruder, and reactive blending was carried out at 180 °C and a rotation speed of 80 r / min for 10 min. Finally, the mixture after reactive mixing was placed in a vacuum press and molded at 180 °C to obtain composite plastic C.

[0065] Example 4

[0066] Composite plastic D was prepared by a method of recycling and reusing mixed plastics. By weight, it included: 100 parts of mixed plastics (50 wt% PE and 50 wt% PP, abbreviated as PE / PP 50 / 50) were dried in a vacuum oven at 80 °C for 6 h. Subsequently, the dried mixed plastics were mixed evenly with 2 parts of graft functional monomer (M2), 2 parts of graft comonomer (styrene), and 0.2 part of initiator (diisopropylbenzene peroxide), added into a twin-screw extruder, and reactive blending was carried out at 180 °C and a rotation speed of 80 r / min for 10 min. Finally, the mixture after reactive mixing was placed in a vacuum press and molded at 180 °C to obtain composite plastic D.

[0067] Example 5

[0068] Composite plastic E was prepared by a method of recycling and reusing mixed plastics. By weight, it included: 100 parts of mixed plastics (30 wt% PE and 70 wt% PP, abbreviated as PE / PP 30 / 70) were dried in a vacuum oven at 80 °C for 6 h. Subsequently, the dried mixed plastics were mixed evenly with 2 parts of graft functional monomer (M1), 2 parts of graft comonomer (styrene), and 0.2 part of initiator (diisopropylbenzene peroxide), added into a twin-screw extruder, and reactive blending was carried out at 180 °C and a rotation speed of 80 r / min for 10 min. Finally, the mixture after reactive mixing was placed in a vacuum press and molded at 180 °C to obtain composite plastic E.

[0069] Example 6

[0070] Composite plastic F was prepared by a method of recycling and reusing mixed plastics. By weight, it included: 100 parts of mixed plastics (30 wt% PE and 70 wt% PP, abbreviated as PE / PP 30 / 70) were dried in a vacuum oven at 80 °C for 6 h. Subsequently, the dried mixed plastics were mixed evenly with 2 parts of graft functional monomer (M2), 2 parts of graft comonomer (styrene), and 0.2 part of initiator (diisopropylbenzene peroxide), added into a twin-screw extruder, and reactive blending was carried out at 180 °C and a rotation speed of 80 r / min for 10 min. Finally, the mixture after reactive mixing was placed in a vacuum press and molded at 180 °C to obtain composite plastic F.

[0071] Example 7

[0072] Composite plastic G is prepared by a method of recycling and reusing mixed plastics. By weight, it includes: drying 100 parts of mixed plastics (65wt% PE, 30wt% PP, and 5wt% POE, abbreviated as PE / PP / POE 65 / 30 / 5) in a vacuum oven at 80 °C for 6 h. Subsequently, the dried mixed plastics are mixed evenly with 2 parts of graft functional monomer (M2), 2 parts of graft comonomer (styrene), and 0.2 part of initiator (dicumyl peroxide), added to a twin-screw extruder, and reactive blending is carried out at 180 °C and a rotation speed of 80 r / min for 10 min. Finally, the mixture after reactive mixing is placed in a vacuum press and molded at 180 °C to obtain composite plastic G.

[0073] Example 8

[0074] Composite plastic H is prepared by a method of recycling and reusing mixed plastics. By weight, it includes: drying 100 parts of mixed plastics (70wt% PE and 30wt% PS, abbreviated as PE / PS 70 / 30) in a vacuum oven at 80 °C for 6 h. Subsequently, the dried mixed plastics are mixed evenly with 2 parts of graft functional monomer (M2), 2 parts of graft comonomer (styrene), and 0.2 part of initiator (dicumyl peroxide), added to a twin-screw extruder, and reactive blending is carried out at 220 °C and a rotation speed of 80 r / min for 8 min. Finally, the mixture after reactive mixing is placed in a vacuum press and molded at 220 °C to obtain composite plastic H.

[0075] Example 9

[0076] Composite plastic I is prepared by a method of recycling and reusing mixed plastics. By weight, it includes: drying 100 parts of mixed plastics (70wt% PE and 30wt% PA, abbreviated as PE / PA 70 / 30) in a vacuum oven at 80 °C for 6 h. Subsequently, the dried mixed plastics are mixed evenly with 2 parts of graft functional monomer (M2), 2 parts of graft comonomer (styrene), and 0.2 part of initiator (dicumyl peroxide), added to a twin-screw extruder, and reactive blending is carried out at 180 °C and a rotation speed of 80 r / min for 10 min. Finally, the mixture after reactive mixing is placed in a vacuum press and molded at 180 °C to obtain composite plastic I.

[0077] Example 10

[0078] Composite plastic J was prepared by a method of recycling and reusing mixed plastics. By weight, it included: drying 100 parts of mixed plastics (70 wt% PE and 30 wt% TPU, abbreviated as PE / TPU 70 / 30) in a vacuum oven at 80 °C for 6 h. Subsequently, the dried mixed plastics were mixed evenly with 2 parts of graft functional monomer (M2), 2 parts of graft comonomer (styrene), and 0.2 part of initiator (dicumyl peroxide), added into a twin-screw extruder, and reactive blending was carried out at 180 °C and a rotation speed of 80 r / min for 10 min. Finally, the mixture after reactive mixing was placed in a vacuum press and molded at 180 °C to obtain composite plastic J.

[0079] Example 11

[0080] Composite plastic K was prepared by a method of recycling and reusing mixed plastics. By weight, it included: drying 100 parts of mixed plastics (70 wt% PE and 30 wt% PCL, abbreviated as PE / PCL 70 / 30) in a vacuum oven at 80 °C for 6 h. Subsequently, the dried mixed plastics were mixed evenly with 2 parts of graft functional monomer (M2), 2 parts of graft comonomer (styrene), and 0.2 part of initiator (dicumyl peroxide), added into a twin-screw extruder, and reactive blending was carried out at 150 °C and a rotation speed of 80 r / min for 10 min. Finally, the mixture after reactive mixing was placed in a vacuum press and molded at 150 °C to obtain composite plastic K.

[0081] Example 12

[0082] Composite plastic L was prepared by a method of recycling and reusing mixed plastics. By weight, it included: drying 100 parts of mixed plastics (70 wt% PE and 30 wt% PLA, abbreviated as PE / PLA 70 / 30) in a vacuum oven at 80 °C for 6 h. Subsequently, the dried mixed plastics were mixed evenly with 2 parts of graft functional monomer (M2), 2 parts of graft comonomer (styrene), and 0.2 part of initiator (dicumyl peroxide), added into a twin-screw extruder, and reactive blending was carried out at 200 °C and a rotation speed of 80 r / min for 8 min. Finally, the mixture after reactive mixing was placed in a vacuum press and molded at 200 °C to obtain composite plastic L.

[0083] Example 13

[0084] Composite plastic M was prepared by a method of recycling and reusing mixed plastics. By weight, it included: 100 parts of mixed plastics (70 wt% PP and 30 wt% PLA, abbreviated as PP / PLA 70 / 30) were dried in a vacuum oven at 80 °C for 6 h. Subsequently, the dried mixed plastics were mixed evenly with 2 parts of graft functional monomer (M2), 2 parts of graft comonomer (styrene), and 0.2 part of initiator (dicumyl peroxide), and added into a twin-screw extruder. At a temperature of 200 °C and a rotation speed of 80 r / min, reactive blending was carried out for 8 min. Finally, the mixture after reactive mixing was placed in a vacuum press and molded at 200 °C to obtain composite plastic M.

[0085] Example 14

[0086] Composite plastic N was prepared by a method of recycling and reusing mixed plastics. By weight, it included: 100 parts of mixed plastics (70 wt% PE and 30 wt% PP, abbreviated as PE / PP 70 / 30) were dried in a vacuum oven at 80 °C for 6 h. Subsequently, the dried mixed plastics were mixed evenly with 2 parts of graft functional monomer (M3), 2 parts of graft comonomer (styrene), 0.2 part of initiator (dicumyl peroxide), and 0.4 part of ferric chloride, and added into a twin-screw extruder. At a temperature of 150 °C and a rotation speed of 80 r / min, reactive blending was carried out for 10 min. Finally, the mixture after reactive mixing was placed in a vacuum press and molded at 150 °C to obtain composite plastic N.

[0087] Example 15

[0088] Composite plastic O was prepared by a method of recycling and reusing mixed plastics. By weight, it included: 100 parts of mixed plastics (70 wt% PE and 30 wt% PP, abbreviated as PE / PP 70 / 30) were dried in a vacuum oven at 80 °C for 6 h. Subsequently, the dried mixed plastics were mixed evenly with 2 parts of graft functional monomer (M4), 2 parts of graft comonomer (styrene), 0.2 part of initiator (dicumyl peroxide), and 0.5 part of ferric chloride, and added into a twin-screw extruder. At a temperature of 150 °C and a rotation speed of 80 r / min, reactive blending was carried out for 10 min. Finally, the mixture after reactive mixing was placed in a vacuum press and molded at 150 °C to obtain composite plastic O.

[0089] Example 16

[0090] Composite plastic P is prepared by a method of recycling and reusing mixed plastics. By weight, it includes: drying 100 parts of mixed plastics (70 wt% PE and 30 wt% PP, abbreviated as PE / PP70 / 30) in a vacuum oven at 80 °C for 6 h. Subsequently, the dried mixed plastics are mixed evenly with 2 parts of graft functional monomer (M5), 2 parts of graft comonomer (styrene), 0.2 part of initiator (dicumyl peroxide), and 0.3 part of ferric trichloride, and added into a twin-screw extruder. At a temperature of 150 °C and a rotational speed of 80 r / min, reactive blending is carried out for 10 min. Finally, the mixture after reactive mixing is placed in a vacuum press and molded at 150 °C to obtain composite plastic P.

[0091] Example 17

[0092] Composite plastic Q is prepared by a method of recycling and reusing mixed plastics. By weight, it includes: drying 100 parts of mixed plastics (70 wt% PE and 30 wt% PP, abbreviated as PE / PP70 / 30) in a vacuum oven at 80 °C for 6 h. Subsequently, the dried mixed plastics are mixed evenly with 2 parts of graft functional monomer (M6), 2 parts of graft comonomer (styrene), 0.2 part of initiator (dicumyl peroxide), and 0.3 part of ferric trichloride, and added into a twin-screw extruder. At a temperature of 150 °C and a rotational speed of 80 r / min, reactive blending is carried out for 10 min. Finally, the mixture after reactive mixing is placed in a vacuum press and molded at 150 °C to obtain composite plastic Q.

[0093] Example 18

[0094] Composite plastic R is prepared by a method of recycling and reusing mixed plastics. By weight, it includes: drying 100 parts of mixed plastics (70 wt% PET and 30 wt% PC, abbreviated as PET / PC70 / 30) in a vacuum oven at 100 °C for 6 h. Subsequently, the dried mixed plastics are mixed evenly with 1 part of graft functional monomer (M7), and added into a twin-screw extruder. At a temperature of 260 °C and a rotational speed of 80 r / min, reactive blending is carried out for 5 min. Finally, the mixture after reactive mixing is placed in a vacuum press and molded at 260 °C to obtain composite plastic R.

[0095] Example 19

[0096] Composite plastic S is prepared by a method of recycling and reusing mixed plastics. By weight, it includes: drying 100 parts of mixed plastics (70 wt% PLA and 30 wt% PBS, abbreviated as PLA / PBS 70 / 30) in a vacuum oven at 100 °C for 6 h. Subsequently, the dried mixed plastics are evenly mixed with 1 part of graft functional monomer (M7), added to a twin-screw extruder, and subjected to reactive blending at 200 °C and a rotation speed of 80 r / min for 5 min. Finally, the mixture after reactive mixing is placed in a vacuum press and molded at 200 °C to obtain composite plastic S.

[0097] Example 20

[0098] Composite plastic T is prepared by a method of recycling and reusing mixed plastics. By weight, it includes: drying 100 parts of mixed plastics (70 wt% PLA and 30 wt% PA, abbreviated as PLA / PA 70 / 30) in a vacuum oven at 100 °C for 6 h. Subsequently, the dried mixed plastics are evenly mixed with 1 part of graft functional monomer (M7), added to a twin-screw extruder, and subjected to reactive blending at 200 °C and a rotation speed of 80 r / min for 5 min. Finally, the mixture after reactive mixing is placed in a vacuum press and molded at 200 °C to obtain composite plastic T.

[0099] Comparative example

[0100] Comparative example 1

[0101] Composite plastic A1 is prepared by the same method as in Example 1, with the only difference being that: only 100 parts of mixed plastics (PE and PP) are used to prepare composite plastic A1, where PE is 70 wt% (weight percentage) and PP is 30 wt%.

[0102] Comparative example 2

[0103] Composite plastic A2 is prepared by the same method as in Example 3, with the only difference being that: only 100 parts of mixed plastics (PE and PP) are used to prepare composite plastic A2, where PE is 50 wt% (weight percentage) and PP is 50 wt%.

[0104] Comparative example 3

[0105] Composite plastic A3 is prepared by the same method as in Example 5, with the only difference being that: only 100 parts of mixed plastics (PE and PP) are used to prepare composite plastic A3, where PE is 30 wt% (weight percentage) and PP is 70 wt%.

[0106] Comparative example 4

[0107] The composite plastic A4 was prepared by the same method as in Example 7, and the only difference was that: only 100 parts of the mixed plastic (PE, PP, and POE) were used to prepare the composite plastic A4, where PE was 65 wt% (weight percentage), PP was 30 wt%, and POE was 5 wt%.

[0108] Comparative Example 5

[0109] The composite plastic A5 was prepared by the same method as in Example 8, and the only difference was that: only 100 parts of the mixed plastic (PE and PS) were used to prepare the composite plastic A5, where PE was 70 wt% (weight percentage) and PS was 30 wt%.

[0110] Comparative Example 6

[0111] The composite plastic A6 was prepared by the same method as in Example 9, and the only difference was that: only 100 parts of the mixed plastic (PE and PA) were used to prepare the composite plastic A6, where PE was 70 wt% (weight percentage) and PA was 30 wt%.

[0112] Comparative Example 7

[0113] The composite plastic A7 was prepared by the same method as in Example 10, and the only difference was that: only 100 parts of the mixed plastic (PE and TPU) were used to prepare the composite plastic A7, where PE was 70 wt% (weight percentage) and TPU was 30 wt%.

[0114] Comparative Example 8

[0115] The composite plastic A8 was prepared by the same method as in Example 11, and the only difference was that: only 100 parts of the mixed plastic (PE and PCL) were used to prepare the composite plastic A8, where PE was 70 wt% (weight percentage) and PCL was 30 wt%.

[0116] Comparative Example 9

[0117] The composite plastic A9 was prepared by the same method as in Example 12, and the only difference was that: only 100 parts of the mixed plastic (PE and PLA) were used to prepare the composite plastic A9, where PE was 70 wt% (weight percentage) and PLA was 30 wt%.

[0118] Comparative Example 10

[0119] The composite plastic A10 was prepared by the same method as in Example 13, and the only difference was that: only 100 parts of the mixed plastic (PP and PLA) were used to prepare the composite plastic A10, where PP was 70 wt% (weight percentage) and PLA was 30 wt%.

[0120] Comparative Example 11

[0121] The composite plastic A11 was prepared by the same method as in Example 18, and the only difference was that only 100 parts of the mixed plastics (PET and PC) were used to prepare the composite plastic A11, wherein PET was 70 wt% (weight percentage) and PC was 30 wt%.

[0122] Comparative Example 12

[0123] The composite plastic A12 was prepared by the same method as in Example 19, and the only difference was that only 100 parts of the mixed plastics (PLA and PBS) were used to prepare the composite plastic A12, wherein PLA was 70 wt% (weight percentage) and PBS was 30 wt%.

[0124] Comparative Example 13

[0125] The composite plastic A13 was prepared by the same method as in Example 20, and the only difference was that only 100 parts of the mixed plastics (PLA and PA) were used to prepare the composite plastic A13, wherein PLA was 70 wt% (weight percentage) and PA was 30 wt%.

[0126] The properties such as Young's modulus, tensile strength, elongation at break, and toughness of the composite plastics in the above Examples 1 - 20 were tested, and the specific test results are shown in Table 1.

[0127] Table 1

[0128]

[0129] Table 2

[0130]

[0131] As can be seen from Table 1, the composite plastics prepared by the method of recycling and reusing the mixed plastics provided by the present invention all have good tensile strength, Young's modulus, elongation at break, and toughness. The two-phase size of PE / PP 50 / 50 is the largest, and the compatibilization difficulty is also great; the toughness of PE / PP 70 / 30 is better than that of PE / PP 30 / 70 because during the free radical grafting process, PP is more likely to break the chain, affecting the mechanical properties. Among the monomer compatibilizations of M1 - M6, the effects of M1 and M2 are better than those of M3 - M6 because M1 and M2 are pairwise complementary combinations with the quadruple hydrogen bond unit ureidopyrimidinone (UPy), belonging to the supramolecular hydrogen bond type structure; M3 - M6 is the combination of carboxyl or catechol groups with metal ions, belonging to the ionic bond type structure, and ionic bonds are prone to form clusters during the compatibilization process, resulting in local aggregation, which may affect the compatibilization effect.

[0132] Furthermore, the stress - strain curves of the composite plastics in the above Examples 1 - 20 were measured, and the specific test results are as Figures 1 - 15 .

[0133] Figure 1 Prepare the stress-strain curves of the composite plastics in Comparative Example 1, Example 1, and Example 2 from the mixed plastic composed of polyethylene (PE) / polypropylene (PP) (70 / 30).

[0134] From Table 1 and Figure 1 It can be seen that compared with the composite plastic A1 in Comparative Example 1 prepared only from the mixed plastic (PE / PP 70 / 30), after adding the graft functional monomer M1, graft comonomer, and initiator to the mixed plastic (PE / PP 70 / 30), the elongation at break of the composite plastic A in Example 1 prepared can be increased to 576.7%, the tensile toughness can reach 91.3 MJ / m³, and the yield strength is still 22.3 MPa, which is difficult to achieve for the composite plastic A1 in Comparative Example 1.

[0135] Furthermore, after adding the graft functional monomer M2, graft comonomer, and initiator to the mixed plastic (PE / PP 70 / 30), the elongation at break of the composite plastic B in Example 2 prepared can be increased to 710.1%, the tensile toughness can reach 107.5 MJ / m³, and the yield strength is still 21.1 Mpa. This shows that by introducing the graft functional monomer M1 or M2 into the mixed plastic, the elongation at break and toughness of the recycled polyolefin mixed plastic are significantly improved, and it can still maintain relatively high rigidity and strength, which helps to improve the recycling rate of the mixed plastic and has great industrial prospects and commercial value. In addition, the present invention is applicable to both the graft functional monomers M1 and M2, having a certain generality.

[0136] Figure 2 Prepare the stress-strain curves of the composite plastics in Comparative Example 2, Example 3, and Example 4 from the mixed plastic composed of polyethylene (PE) / polypropylene (PP) (50 / 50).

[0137] From Table 1 and Figure 2It can be seen that compared with the composite plastic A2 in Comparative Example 2 prepared only from the mixed plastic (PE / PP 50 / 50), after adding the graft functional monomer M1, the graft comonomer and the initiator to the mixed plastic (PE / PP 50 / 50), the elongation at break of the composite plastic C in Example 3 prepared can be increased to 280.8%, the tensile toughness can reach 48.1 MJ / m³, and the yield strength is still 18.6 MPa, which is difficult to achieve for the composite plastic A2 in Comparative Example 2. Further, after adding the graft functional monomer M2, the graft comonomer and the initiator to the mixed plastic (PE / PP 50 / 50), the elongation at break of the composite plastic D in Example 4 prepared can be increased to 414.5%, the tensile toughness can reach 73.1 MJ / m³, and the yield strength is still 20.5 Mpa. This shows that by changing the ratio of PE and PP, the prepared composite plastic still has a high elongation at break and good toughness, improving the recycling rate of the polyolefin mixed plastic, and this method has universality.

[0138] Figure 3 Stress-strain curve graphs of the composite plastics in Comparative Example 3, Example 5, and Example 6 prepared from the mixed plastic composed of polyethylene (PE) / polypropylene (PP) (30 / 70).

[0139] From Table 1 and Figure 3 It can be seen that compared with the composite plastic A3 in Comparative Example 3 prepared only from the mixed plastic (PE / PP 30 / 70), after adding the graft functional monomer M1, the graft comonomer and the initiator to the mixed plastic (PE / PP 30 / 70), the elongation at break of the composite plastic E in Example 5 prepared can be increased to 464.1%, the tensile toughness can reach 81.2 MJ / m³, and the yield strength is still 18.9 MPa, which is difficult to achieve for the composite plastic A3 in Comparative Example 3. Further, after adding the graft functional monomer M2, the graft comonomer and the initiator to the mixed plastic (PE / PP 50 / 50), the elongation at break of the composite plastic F in Example 6 prepared can be increased to 551.6%, the tensile toughness can reach 100.1 MJ / m³, and the yield strength is still 21.5 Mpa. This shows that by reducing the proportion of PE and increasing the proportion of PP at the same time, the prepared composite plastic still has a high elongation at break and good toughness, and can also improve the recycling rate of the polyolefin mixed plastic, and this method has universality.

[0140] Figure 4 Stress-strain curve graphs of the composite plastics in Comparative Example 4 and Example 7 prepared from the mixed plastic composed of polyethylene (PE) / polypropylene (PP) / ethylene-octene copolymer (POE) (65 / 30 / 5).

[0141] From Table 1 andFigure 4 It can be seen that, compared with the composite plastic A4 in Comparative Example 4 prepared only from the mixed plastic (PE / PP / POE 65 / 30 / 5), after adding the graft functional monomer M2, graft comonomer and initiator to the mixed plastic (PE / PP / POE 65 / 30 / 5), the elongation at break of the composite plastic G in Example 7 prepared can be increased to 631.4%, the tensile toughness can reach 75.6 MJ / m³, and the yield strength is still 17.4 MPa, which is difficult to achieve for the composite plastic A4 in Comparative Example 4. In other words, by using the graft functional monomer M2, the compatibility between PE, PP and POE is improved, so that different non-polar plastics have more excellent properties after being mixed and processed, significantly improving the recycling rate of polyolefin mixed plastics, and this method has universality.

[0142] Figure 5 Stress-strain curves of the composite plastics in Comparative Example 5 and Example 8 prepared from the mixed plastic composed of polyethylene (PE) / polystyrene (PS) (70 / 30).

[0143] From Table 1 and Figure 5 It can be seen that, compared with the composite plastic A5 in Comparative Example 5 prepared only from the mixed plastic (PE / PS 70 / 30), after adding the graft functional monomer M2, graft comonomer and initiator to the mixed plastic (PE / PS 70 / 30), the elongation at break of the composite plastic H in Example 8 prepared can be increased to 23.3%, the tensile toughness can reach 4.1 MJ / m³, and the yield strength is still 19.1 MPa, which is difficult to achieve for the composite plastic A5 in Comparative Example 5. In other words, by using the graft functional monomer M2, the compatibility between the non-polar plastics PE and PS is improved, so that different non-polar plastics have more excellent properties after being mixed and processed, significantly improving the recycling rate of polyolefin mixed plastics, and this method has universality.

[0144] Figure 6 Stress-strain curves of the composite plastics in Comparative Example 6 and Example 9 prepared from the mixed plastic composed of polyethylene (PE) / polyamide (PA) (70 / 30).

[0145] From Table 1 and Figure 6It can be seen that, compared with the composite plastic A6 in Comparative Example 6 prepared only from the mixed plastic (PE / PA70 / 30), after adding the graft functional monomer M2, graft comonomer and initiator to the mixed plastic (PE / PA70 / 30), the elongation at break of the composite plastic I in Example 9 prepared can be increased to 1004.8%, the tensile toughness can reach 133.4 MJ / m³, and the yield strength is still 15.9 MPa, which is difficult to achieve for the composite plastic A6 in Comparative Example 6. In other words, by using the graft functional monomer M2, the compatibility between the non-polar plastic PE and the polar plastic PA is improved, so that the non-polar plastic and the polar plastic have more excellent properties after being mixed and processed, significantly improving the recycling rate of polyolefin mixed plastics, and this method has universality.

[0146] Figure 7 The stress-strain curves of the composite plastics in Comparative Example 7 and Example 10 are prepared from the mixed plastic composed of polyethylene (PE) / thermoplastic polyurethane elastomer (TPU) (70 / 30).

[0147] As can be seen from Table 1 and Figure 7 It can be seen that, compared with the composite plastic A7 in Comparative Example 7 prepared only from the mixed plastic (PE / TPU70 / 30), after adding the graft functional monomer M2, graft comonomer and initiator to the mixed plastic (PE / TPU70 / 30), the elongation at break of the composite plastic J in Example 10 prepared can be increased to 99.5%, the tensile toughness can reach 13.6 MJ / m³, and the yield strength is still 16.6 MPa, which is difficult to achieve for the composite plastic A7 in Comparative Example 7. In other words, by using the graft functional monomer M2, the compatibility between the non-polar plastic PE and the polar plastic TPU is improved, so that the non-polar plastic and the polar plastic have more excellent properties after being mixed and processed, significantly improving the recycling rate of polyolefin mixed plastics, and this method has universality.

[0148] Figure 8 The stress-strain curves of the composite plastics in Comparative Example 8 and Example 11 are prepared from the mixed plastic composed of polyethylene (PE) / polycaprolactone (PCL) (70 / 30).

[0149] As can be seen from Table 1 and Figure 8It can be seen that, compared with the composite plastic A8 in Comparative Example 8 prepared only from the mixed plastic (PE / PCL 70 / 30), after adding the graft functional monomer M2, graft comonomer and initiator to the mixed plastic (PE / PCL 70 / 30), the elongation at break of the composite plastic K in Example 11 prepared can be increased to 130.3%, the tensile toughness can reach 25.6 MJ / m³, and the yield strength is still 24.3 MPa, which is difficult to achieve for the composite plastic A8 in Comparative Example 8. In other words, by using the graft functional monomer M2, the compatibility between the non-polar plastic PE and the polar plastic PCL is improved, so that the non-polar plastic and the polar plastic have more excellent properties after being mixed and processed, significantly improving the recycling rate of polyolefin mixed plastics, and this method has universality.

[0150] Figure 9 Stress-strain curves of the composite plastics in Comparative Example 9 and Example 12 prepared from the mixed plastic composed of polyethylene (PE) / polycaprolactone (PLA) (70 / 30).

[0151] From Table 1 and Figure 9 It can be seen that, compared with the composite plastic A9 in Comparative Example 9 prepared only from the mixed plastic (PE / PLA 70 / 30), after adding the graft functional monomer M2, graft comonomer and initiator to the mixed plastic (PE / PLA 70 / 30), the elongation at break of the composite plastic L in Example 12 prepared can be increased to 17.6%, the tensile toughness can reach 3.1 MJ / m³, and the yield strength is still 19.2 MPa, which is difficult to achieve for the composite plastic A9 in Comparative Example 9. In other words, by using the graft functional monomer M2, the compatibility between the non-polar plastic PE and the polar plastic PLA is improved, so that the non-polar plastic and the polar plastic have more excellent properties after being mixed and processed, significantly improving the recycling rate of polyolefin mixed plastics, and this method has universality.

[0152] Figure 10 Stress-strain curves of the composite plastics in Comparative Example 10 and Example 13 prepared from the mixed plastic composed of polypropylene (PP) / polylactic acid (PLA) (70 / 30).

[0153] From Table 1 and Figure 10It can be seen that, compared with the composite plastic A10 in Comparative Example 10 prepared only from the mixed plastic (PP / PLA 70 / 30), after adding the graft functional monomer M2, graft comonomer and initiator to the mixed plastic (PP / PLA 70 / 30), the elongation at break of the composite plastic M in Example 13 prepared can be increased to 105.8%, the tensile toughness can reach 14.2 MJ / m³, and the yield strength is still 15.2 MPa, which is difficult to achieve for the composite plastic A10 in Comparative Example 10. In other words, by using the graft functional monomer M2, the compatibility between the non-polar plastic PP and the polar plastic PLA is improved, so that the non-polar plastic and the polar plastic have more excellent properties after being mixed and processed, significantly improving the recycling rate of the polyolefin mixed plastic, and this method is applicable to both PE / PLA and PP / PLA, with universality. The reason for the slight decrease in the yield strength is that the grafting of the graft functional monomer M2 increases the flexibility of the polymer chain, improves the toughness, and slightly decreases the strength.

[0154] Figure 11 Stress-strain curves of the composite plastics in Comparative Example 1, Example 14, and Example 15 prepared from the mixed plastic composed of polyethylene (PE) / polypropylene (PP) (70 / 30).

[0155] As can be seen from Table 1 and Figure 11 It can be seen that, compared with the composite plastic A1 in Comparative Example 1 prepared only from the mixed plastic (PE / PP 70 / 30), after adding the graft functional monomer M3, graft comonomer, ferric trichloride and initiator to the mixed plastic (PE / PP 70 / 30), the elongation at break of the composite plastic N in Example 14 prepared can be increased to 198.3%, the tensile toughness can reach 35.4 MJ / m³, and the yield strength is still 23.2 MPa, which is difficult to achieve for the composite plastic A1 in Comparative Example 1.

[0156] Furthermore, by replacing the graft functional monomer M3 with the graft functional monomer M4, the elongation at break of the composite plastic O in Example 15 prepared can be increased to 340.7%, the tensile toughness can reach 58.7 MJ / m³, and the yield strength is still 24.1 MPa, which is difficult to achieve for the composite plastic A1 in Comparative Example 1. In other words, by using the graft functional monomer M3 or the graft functional monomer M4, the compatibility between the non-polar plastic PE and the non-polar plastic PP is improved, so that the non-polar plastic and the non-polar plastic have more excellent properties after being mixed and processed, significantly improving the recycling rate of the polyolefin mixed plastic, and also indicating that the method provided by the present invention has universality.

[0157] Figure 12Prepare the stress-strain curves of the composite plastics in Comparative Example 1, Example 16, and Example 17 from the mixed plastic composed of polyethylene (PE) / polypropylene (PP) (70 / 30).

[0158] From Table 1 and Figure 12 It can be seen that compared with the composite plastic A1 in Comparative Example 1 prepared only from the mixed plastic (PE / PP 70 / 30), after adding the graft functional monomer M5, graft comonomer, ferric trichloride, and initiator to the mixed plastic (PE / PP 70 / 30), the elongation at break of the composite plastic P in Example 16 prepared can be increased to 310.5%, the tensile toughness can reach 51.2 MJ / m³, and the yield strength is still 21.4 MPa, which is difficult to achieve for the composite plastic A1 in Comparative Example 1.

[0159] Furthermore, by replacing the graft functional monomer M5 with the graft functional monomer M6, the elongation at break of the composite plastic Q in Example 17 prepared can be increased to 379.9%, the tensile toughness can reach 67.3 MJ / m³, and the yield strength is still 24.5 MPa, which is difficult to achieve for the composite plastic A1 in Comparative Example 1. In other words, by using the graft functional monomer M5 or the graft functional monomer M6, the compatibility between the non-polar plastic PE and the non-polar plastic PP is improved, so that the non-polar plastics and non-polar plastics have more excellent properties after being mixed and processed, significantly improving the recycling rate of polyolefin mixed plastics, and also indicating that the method provided by the present invention has universality.

[0160] Figure 13 Prepare the stress-strain curves of the composite plastics in Comparative Example 11 and Example 18 from the mixed plastic composed of polyethylene terephthalate (PET) / polycarbonate (PC) (70 / 30).

[0161] From Table 1 and Figure 13 It can be seen that compared with the composite plastic A11 in Comparative Example 11 prepared only from the mixed plastic (PET / PC 70 / 30), after adding the graft functional monomer M7 to the mixed plastic (PET / PC 70 / 30), the elongation at break of the composite plastic R in Example 18 prepared can be increased to 31.6%, the tensile toughness can reach 13.2 MJ / m³, and the yield strength is still 62.3 MPa, which is difficult to achieve for the composite plastic A11 in Comparative Example 11. In other words, by using the graft functional monomer M7, the compatibility between the polar plastic PET and the polar plastic PC is improved, so that the polar plastics have more excellent properties after being mixed and processed, significantly improving the recycling rate of polyolefin mixed plastics, and the method provided by the present invention also has universality for other polar mixed plastics.

[0162] Figure 14Prepare the stress-strain curves of the composite plastics in Comparative Example 12 and Example 19 from the mixed plastic composed of polylactic acid (PLA) / polybutylene succinate (PBS) (70 / 30).

[0163] From Table 1 and Figure 14 It can be seen that, compared with the composite plastic A12 in Comparative Example 12 prepared only from the mixed plastic (PLA / PBS 70 / 30), after adding the graft functional monomer M7 to the mixed plastic (PLA / PBS 70 / 30), the elongation at break of the composite plastic S in Example 19 prepared can be increased to 25.6%, the tensile toughness can reach 8.0 MJ / m³, and the yield strength is still 48.8 MPa, which is difficult to achieve for the composite plastic A12 in Comparative Example 12. In other words, by using the graft functional monomer M7, the compatibility between the polar plastic PLA and the polar plastic PBS is improved, so that the polar plastics have more excellent properties after being mixed and processed, significantly improving the recycling rate of the polyolefin mixed plastic, and the method provided by the present invention is also universal for other polar mixed plastics.

[0164] Figure 15 Prepare the stress-strain curves of the composite plastics in Comparative Example 13 and Example 20 from the mixed plastic composed of polylactic acid (PLA) / polyamide (PA) (70 / 30).

[0165] From Table 1 and Figure 16 It can be seen that, compared with the composite plastic A13 in Comparative Example 13 prepared only from the mixed plastic (PLA / PA 70 / 30), after adding the graft functional monomer M7 to the mixed plastic (PLA / PA 70 / 30), the elongation at break of the composite plastic T in Example 20 prepared can be increased to 148.2%, the tensile toughness can reach 30.5 MJ / m³, and the yield strength is still 20.1 MPa, which is difficult to achieve for the composite plastic A13 in Comparative Example 13. In other words, by using the graft functional monomer M7, the compatibility between the polar plastic PLA and the polar plastic PA is improved, so that the polar plastics have more excellent properties after being mixed and processed, significantly improving the recycling rate of the polyolefin mixed plastic, and the method provided by the present invention is also universal for other polar mixed plastics.

[0166] Figure 16 and Figure 19 are respectively the scanning electron microscope (SEM) image and atomic force microscope (AFM) image of the composite plastic prepared from polyethylene (PE) / polypropylene (PP) (PE / PP 70 / 30) in Comparative Example 1, Figure 17 and Figure 20 are respectively the SEM image and AFM image of the composite plastic A in Example 1, Figure 18 andFigure 21 They are respectively the SEM image and AFM image of composite plastic B in Example 2.

[0167] As Figures 16 - 21 shown, for the composite plastic prepared only from the blended plastic (PE / PP 70 / 30), there is obvious phase separation in its cross-section, that is, PE and PP are incompatible systems. With the addition of the graft functional monomer, PP expands from particles to a continuous structure, and the phase separation between the two phases of PE and PP is significantly improved. This is beneficial to the tensile and bending properties of the PE / PP (70 / 30) composite plastic, can play a role in absorbing energy, and further improves the mechanical properties of the composite plastic.

[0168] In summary, adding a small amount of graft functional monomer to the blended plastic can greatly improve the mechanical properties such as the tensile strength, elongation at break, and toughness of the composite plastic prepared from the blended plastic. The graft functional monomer in the present invention can be commercially available or simply synthesized, the raw materials are inexpensive, the performance is good, and the compatibilization and toughening effects are remarkable. In addition, in the present invention, the composite plastic is prepared by reactive melt blending of the blended plastic with the same polarity and / or different polarities. The preparation process has a low investment in equipment, is simple to operate, and this method is applicable to the existing industrial twin-screw processing system without additional post-treatment steps.

[0169] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for recycling mixed plastics, characterized in that: The method comprises: By weight, 100 parts of mixed plastic, 1-5 parts of grafted functional monomers, 1-5 parts of grafted comonomers and 0.1-0.3 parts of initiator are mixed evenly to obtain a mixed material; The mixed material is conveyed to a twin-screw extruder for reactive blending and extrusion to obtain a composite plastic; Wherein, the mixed plastic is a mixture of at least two different plastics, and the grafting functional monomer is selected from any one of the following: <h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr"> M1<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr"> M2 <h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr"> M3、<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr"> M4 M5、 M6、 M7； When the grafting functional monomer is M7, the initiator and the grafting comonomer are both 0 parts.

2. The method according to claim 1, characterized in that In the case where the grafting functional monomer is selected from any one of M3-M6, the method further comprises: adding ferric chloride to blend with the mixed plastic, grafting comonomer, and initiator; Wherein, the ferric chloride is 0.1-0.5 parts by weight.

3. The method according to claim 1 or 2, characterized in that: The mixed plastic is a mixture of at least two of the following plastics: A polar plastic, B polar plastic, C non-polar plastic, and D non-polar plastic; Wherein, the polar plastic A and the polar plastic B are independently and differently selected from at least one of polyamide, polycaprolactone, polyurethane, polylactic acid, polyethylene terephthalate, polycarbonate, and polybutylene succinate; The C non-polar plastic and the D non-polar plastic are each independently and differently selected from at least one of poly-C2-C8 olefins, C2-C8 olefins and copolymers of C2-C8 olefins.

4. The method according to claim 3, characterized in that In 100 parts of the mixed plastics, the weight ratio of any two plastics is 30:70-70:30, the weight percentage of any three plastics is 65:30:5-5:30:65, and the weight ratio of any four plastics is 60:30:5:5-5:5:30:

60.

5. The method according to claim 1, characterized in that The grafted comonomer is selected from , , , Any one of .

6. The method according to claim 1, characterized in that The initiator is selected from at least one of dicumyl peroxide, dibenzoyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and azobisisobutyronitrile.

7. The method according to claim 1, characterized in that The mixed plastics are dried at 60-100° C. for 4-8 hours before being blended.

8. The method according to claim 1, characterized in that The reactive blending is carried out at 150-260° C. and 60-100 r / min for 5-10 min.

9. The method according to any one of claims 1 to 8, characterized in that The reactive blending extrusion was repeated 3-5 times.

10. A composite plastic prepared by the method according to any one of claims 1 to 9.

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