High Thermal Conductivity Flame Retardant Products Based on Waste Aluminum-Plastic Packaging Materials and Preparation Methods Thereof

Abstract

The present invention provides a high thermal conductivity and flame retardant product based on waste aluminum-plastic packaging materials and a preparation method thereof. The raw materials of the high thermal conductivity and flame retardant product mainly include the following components by weight: 41-53 parts of waste aluminum-plastic ultrafine powder, 3 parts of compatibilizer, 32-40 parts of flame retardant filler, and 12-16 parts of double synergistic thermal conductive filler. The double synergistic thermal conductive filler is composed of unexpanded graphite and expanded graphite mixed in a mass ratio of (4-8):(7-10). When preparing the high thermal conductivity and flame retardant product, there is no need to separate the polymer and metallic aluminum in the waste aluminum-plastic packaging materials. The thermal conductivity characteristics of flaky metallic aluminum can be directly utilized, and by further improving the composition of the raw material components and through the double synergistic effect of the thermal conductive filler, the thermal conductivity and flame retardant performance of the product are further significantly improved, realizing the high-value recycling of waste aluminum-plastic materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of recycling of waste aluminum-plastic packaging materials, and particularly relates to a high thermal conductivity and flame retardant product based on waste aluminum-plastic packaging materials and a preparation method thereof, and particularly relates to the treatment of the above-mentioned waste aluminum-plastic packaging materials by using a mechanochemical reactor disclosed in the Chinese authorized invention patent ZL 95111258.9. Background Art

[0002] Aluminum-plastic packaging materials (also known as aluminum-plastic composite packaging materials) are composite materials prepared by hot pressing aluminum foil and polyethylene at high temperature. They have the high strength, corrosion resistance, and high tightness of aluminum, as well as the light weight, stable chemical properties, low temperature resistance, and impact resistance of polyethylene, and are widely used in the field of high-barrier packaging. In China, the output of aluminum-plastic exceeds 800,000 tons per year. A large amount of production scraps are stacked, occupying a large area, and landfill causes serious soil compaction. Their high-quality and efficient recycling is the key requirement for realizing resource recycling and promoting the green development of the industry.

[0003] A series of physical recycling technologies for waste aluminum-plastic packaging materials have been developed at home and abroad. For example, Mammem Company in Switzerland has developed a centrifugal separation recycling process. The high-speed rotor can peel off the short-piece multi-layer plastics. It mainly uses the difference in ductility between aluminum and PE materials to achieve separation, but the small-scale recycling efficiency is not high. Another example is that Yu Shaohuo et al. from Ningbo University of Technology have improved the mechanical multi-stage crushing-high voltage electrostatic separation recycling technology. Through the high-speed rotating multi-layer combined turbine rotor and stator, the materials are repeatedly impacted, rubbed, and sheared to achieve the dissociation of aluminum and plastic, and then the separation and recycling are realized by using the different electrostatic characteristics of aluminum and PE. However, the equipment specificity is high and the cost is high. Different from the physical recycling technology, the chemical separation method uses strong acid or strong alkali solvents to dissolve aluminum to achieve the separation of aluminum-plastic composite packaging, or uses solvents such as formic acid, acetic acid, and sodium silicate to dissolve the polymer binder between aluminum and PE to separate the aluminum foil and plastic. In recent years, there have been many technical improvements based on the chemical separation and recycling idea, but the problems such as long process flow, use of harmful chemical solvents, and environmental pollution still cannot be avoided.

[0004] Traditional methods represented by separation and recycling are based on chemical and physical separation. They can prepare recycled PE particles, but chemical reagents such as acids and alkalis are likely to cause secondary pollution. The recycling processes such as density separation and electrostatic separation are complex, energy-consuming, and the recycled PE contains difficult-to-separate impurities, and its application range is limited. There is an urgent need to establish new technologies and methods for high-value recycling of waste aluminum-plastic composite packaging films.

[0005] The applicant of the present invention's previously authorized patent "A High Thermal Conductivity Insulating Material Prepared from Waste Aluminum-Plastic Packaging Materials and Its Method" (CN108440824B) discloses a method for preparing a high thermal conductivity insulating material from waste aluminum-plastic packaging materials. The method is to add waste aluminum-plastic packaging materials and graphite into a solid-phase force chemical reactor and grind them 10-15 times to prepare a composite functional powder. During the grinding process, an alumina insulating layer is formed on the surface of the in-situ alumina flakes. Through extrusion or internal mixing, a thermally conductive insulating composite material with a conductivity lower than 10 -10 S / cm and a thermal conductivity not lower than 1.5 W / mK can be prepared.

[0006] The applicant of the present invention's previously authorized patent "Method for Preparing High Thermal Conductivity Insulating 3D Printing Products Using Waste Aluminum-Plastic Packaging" (CN112793152B) discloses a method for preparing high thermal conductivity insulating 3D printing products using waste aluminum-plastic packaging materials. This method selects expandable graphite with a highly oxidizing intercalating agent or oxidant, and blends and extrudes it with the aluminum-plastic ultrafine powder obtained by treating in a solid-phase force chemical reactor into a 3D printing filament. Through the unique process temperature conditions during the fused deposition modeling 3D printing process, the expandable graphite expands in-situ, and the intercalating agent is released in a confined space, causing an in-situ oxidation reaction on the surface of the aluminum metal. At the same time, by using the high shear force during the fused deposition modeling 3D printing process, the special orientation and network structure of two-dimensional nanomaterials are realized, thereby preparing high-performance thermally conductive insulating 3D printing products. The thermally conductive coefficient of the 3D printing products prepared by the present invention is not lower than 2.5 W / mK, the conductivity is less than 10 -10 S / cm, and the tensile strength is not lower than 12 Mpa.

[0007] The above patent technologies propose a technical idea for the overall utilization of waste aluminum-plastic packaging materials, but there are still problems such as relatively complex processes or limited application fields of the products, and only small-scale recycling and treatment can be achieved. Summary of the Invention

[0008] In order to solve the problems of the above-mentioned existing technologies, the present invention provides a high thermal conductivity flame retardant product based on waste aluminum-plastic packaging materials and its preparation method. When preparing this high thermal conductivity flame retardant product, there is no need to separate the polymer and metallic aluminum in the waste aluminum-plastic packaging materials. The thermal conductivity characteristics of the flaky metallic aluminum can be directly utilized, and by further improving the composition of the raw material components, through the double synergistic effect of the thermal conductivity filler, the thermal conductivity and flame retardant performance of the product are further significantly improved, realizing the high-value recycling and utilization of waste aluminum-plastic.

[0009] To achieve the above object, the present invention is realized by a technical solution composed of the following technical measures.

[0010] On the one hand, the present invention provides a high thermal conductivity flame retardant product based on waste aluminum-plastic packaging materials. According to weight parts, its raw materials mainly include the following components:

[0011]

[0012] Among them, the waste aluminum-plastic ultrafine powder is obtained by grinding and pulverizing the recycled waste aluminum-plastic packaging materials or products in a disk-type solid-phase force chemical reactor.

[0013] The double synergistic thermal conductive filler is composed of unexpanded graphite and expanded graphite with a mass ratio of (4-8):(7-10).

[0014] The flame retardant filler is at least one of aluminum hydroxide and magnesium hydroxide.

[0015] It should be noted that the waste aluminum-plastic packaging materials or products described in this article have not undergone aluminum-plastic separation treatment.

[0016] In this article, the waste aluminum-plastic packaging materials or products are usually aluminum-plastic packaging materials, products, and scraps used in packaging on the market, such as milk packaging (after separating the paper), facial masks, toothpaste, etc.; among them, the waste aluminum-plastic packaging materials or products with an aluminum content of 10-20 wt% are suitable choices for the present invention. Those skilled in the art can query the specifications of the waste aluminum-plastic packaging materials or products to determine whether they meet the requirements for being used as raw materials for the present invention.

[0017] Generally speaking, conventional aluminum-plastic packaging materials with component compositions of polyethylene-based / aluminum, polypropylene-based / aluminum, polyethylene terephthalate-based / aluminum, polyethylene-based / aluminum / polyethylene terephthalate, polypropylene-based / aluminum / polyethylene terephthalate, polyethylene-based / aluminum / nylon / polyethylene terephthalate, polyamide / aluminum / polypropylene can all be used as choices for the waste aluminum-plastic packaging materials or products of the present invention.

[0018] In this article, the waste aluminum-plastic ultrafine powder is obtained by grinding and pulverizing the recycled waste aluminum-plastic packaging materials or products in a disk-type solid-phase force chemical reactor. The disk-type solid-phase force chemical reactor is the force chemical reactor disclosed in the prior authorized patent ZL 95111258.9 of the applicant of the present invention. For the specific methods and parameters involved in grinding and pulverizing by the disk-type solid-phase force chemical reactor, reference can be made to the methods disclosed in the inventor's prior authorized invention patent "Method for Preparing High Thermal Conductivity Insulating 3D Printing Products Using Waste Aluminum-Plastic Packaging" (CN112793152B), or the preparation methods disclosed below.

[0019] In this text, the compatibilizer is a conventional reactive compatibilizer, which plays a role in improving the compatibility between the double synergistic thermal conductive filler and the flame retardant filler, and ensures the synergistic thermal conductivity and flame retardancy between the double synergistic thermal conductive filler and the flame retardant filler. To better illustrate the present invention and provide a reference technical solution, the selected solubilizer includes but is not limited to at least one of polyethylene grafted maleic anhydride, chlorinated polyethylene, polyethylene grafted glycidyl methacrylate, and polyethylene grafted methyl methacrylate.

[0020] In this text, the flame retardant filler is at least one of aluminum hydroxide and magnesium hydroxide, and aluminum hydroxide and magnesium hydroxide are commercially available conventional powders. In one of the technical solutions, to improve the uniform mixing of the flame retardant filler and the waste aluminum-plastic ultrafine powder, the aluminum hydroxide is a powder with an average particle size of not less than 23 μm, and the magnesium hydroxide is a powder with an average particle size of not less than 23 μm.

[0021] In one of the preferred technical solutions, the flame retardant filler is obtained by compounding aluminum hydroxide powder and magnesium hydroxide powder in a mass ratio of 1:1.

[0022] In one of the more preferred technical solutions, the flame retardant filler is obtained by compounding two kinds of aluminum hydroxide powders with different average particle sizes in a mass ratio of 1:1, and the average particle size of the first aluminum hydroxide powder is 0.6 μm, and the average particle size of the second aluminum hydroxide powder is 23 μm.

[0023] In this text, the unexpanded graphite and the expandable graphite in the common knowledge of this technical field refer to the same thing, that is, when the unexpanded graphite is heated to an appropriate temperature, it can decompose instantaneously and rapidly, generating a large amount of gas, causing the graphite to expand axially into a worm-like new substance, obtaining the expanded graphite in the common knowledge of this technical field. In this text, the expanded graphite and the expanded graphite in the common knowledge of this technical field refer to the same thing, that is, the expanded graphite obtained after the expandable graphite is expanded. For the convenience of those skilled in the art to better understand the technical solution of the present invention and more clearly distinguish the concepts of the two fillers in the double synergistic thermal conductive filler, the unexpanded graphite and the expanded graphite are used for reference in this text, and those skilled in the art can clearly know the raw material selection adopted in the technical solution of the present invention through the above description.

[0024] In this text, both the unexpanded graphite and the expanded graphite can be obtained commercially, or prepared by those skilled in the art according to the common knowledge in this field. For example, the expanded graphite can be obtained by heating the unexpanded graphite to an appropriate temperature.

[0025] In one of the technical solutions, the unexpanded graphite is selected with an initial expansion temperature of 160 - 170°C and an expansion ratio of 200 - 500 ml / g. It should be noted that the selected expansion temperature condition is not higher than the extrusion temperature applicable to subsequent screw extrusion processing and forming. Therefore, based on this selection of the expansion temperature, the unexpanded graphite actually expands during the subsequent processing and forming process.

[0026] In one of the technical solutions, the expanded graphite is selected as the expanded graphite with a volume expansion ratio of 50 - 300 times.

[0027] In one of the preferred technical solutions, for the convenience of co-extrusion molding with waste aluminum-plastic ultrafine powder, the particle size of the unexpanded graphite powder is 50 - 100 mesh.

[0028] In one of the preferred technical solutions, for the convenience of co-extrusion molding with waste aluminum-plastic ultrafine powder, the particle size of the expanded graphite powder is 50 - 2000 mesh.

[0029] In one of the technical solutions, the raw materials may further include fillers or / and additives commonly used in plastic-based recycled products to achieve further functional expansion / process assistance / enhancement of the product. For the specific selection of fillers or / and additives, those skilled in the art can refer to the existing technology or existing literature, such as antioxidants, lubricants, carbon-based fillers, coatings, flame retardants, anti-aging agents, heat stabilizers, coupling agents, compatibilizers, plasticizers, processing aids, etc. It should be noted that the raw materials may or may not include fillers or / and additives commonly used in plastic-based recycled products.

[0030] It is worth noting that generally, after those skilled in the art know the above raw material components and ratios, they can prepare high thermal conductivity and flame retardant products consistent with those of the present invention according to the common general knowledge in the art or the disclosed existing technology. For example, conventional screw extrusion granulation or mixing and extrusion granulation processes can be used to obtain high thermal conductivity and flame retardant products, or high thermal conductivity and flame retardant intermediate products can also be obtained and then prepared into finished products through conventional forming processes.

[0031] To better illustrate the present invention and provide a reference technical solution, the present invention also provides a preparation method of the above high thermal conductivity and flame retardant products as a preference and reference. It should be noted that the main inventive point of the present invention lies in discovering and defining the raw material components of the above high thermal conductivity and flame retardant products, thereby further significantly improving the thermal conductivity and flame retardant performance of the products, and its preparation method is not unique.

[0032] On the other hand, the present invention provides a preparation method of a high thermal conductivity and flame retardant product based on waste aluminum-plastic packaging materials, mainly including the following steps:

[0033] (1) Select waste aluminum-plastic packaging materials or products. After pretreatment including washing, crush them into waste aluminum-plastic packaging powder with an average particle size not higher than 100 um.

[0034] (2) Add the waste aluminum-plastic packaging powder into a disk-type solid-phase force chemical reactor for grinding and crushing. After grinding is completed, collect the waste aluminum-plastic ultrafine powder. Among them, the process parameters of the disk-type solid-phase force chemical reactor are: the grinding pressure is 3 - 8 MPa, the temperature of the disk surface is controlled at 0 - 15 °C by introducing circulating cooling liquid, and the circulating grinding is carried out 2 - 15 times.

[0035] (3) Prepare raw materials mainly including the following components by weight:

[0036]

[0037] The double synergistic heat-conducting filler is composed of unexpanded graphite and expanded graphite with a mass ratio of (4 - 8):(7 - 10).

[0038] The flame-retardant filler is at least one of aluminum hydroxide and magnesium hydroxide.

[0039] (4) After mixing the raw materials prepared in step (3) evenly, add them to a twin-screw extrusion platform for melt blending. After extrusion, water cooling, and strand pelletizing, a high heat-conducting and flame-retardant product is obtained. Among them, the process parameters of the twin-screw extrusion platform are: the extrusion temperature is 170 - 180 °C, and the rotation speed is 20 - 50 r / min.

[0040] In this article, the pretreatment including washing in step (1) mainly removes the surface impurities of the waste aluminum-plastic packaging materials or products. If necessary, the non-aluminum-plastic packaging material part also needs to be removed. Those skilled in the art can carry out specific treatment according to the actual situation of the waste aluminum-plastic packaging materials or products to be recycled and utilized according to the existing technology.

[0041] Generally, the waste aluminum-plastic packaging powder with an average particle size not higher than 100 um obtained by the treatment and crushing in step (1) can be processed by existing conventional crushing equipment such as jaw crushers, planetary ball mills, and cryogenic ball mills.

[0042] In this article, the disk-type solid-phase force chemical reactor in step (2) is the force chemical reactor disclosed in the prior authorized patent ZL 95111258.9 of the applicant of the present invention.

[0043] Generally, the actual operation of the above-mentioned circulating grinding is to place the material in the disk-type force chemical reactor for grinding, collect the product at the discharge end, and then place it in the disk-type force chemical reactor for grinding again. The above process is regarded as one time of circulating grinding.

[0044] In one of the technical solutions, the temperature of the grinding disc surface in step (2) is controlled at 0-15°C by introducing circulating cooling liquid, and the cooling liquid is ethylene glycol or water.

[0045] Generally, the process parameters of the grinding disc type solid-phase force chemical reactor further include process conditions such as the rotational speed of the grinding disc. Except for the process parameters defined in the present invention, those skilled in the art can select other suitable process conditions such as the rotational speed of the grinding disc according to the force chemical reactor disclosed in Patent ZL 95111258.9.

[0046] In this article, the uniform mixing described in step (4) is a conventional process method in the art, for example, it is dispersed uniformly by mechanical stirring means such as a high-speed rotating mixer.

[0047] It is worth noting that during the extrusion molding process in step (3), the aluminum-plastic ultrafine powder is blended with the flame retardant filler, unexpanded graphite, and expanded graphite. If the extrusion temperature is too low, it is easy to cause the aluminum-plastic ultrafine powder and the filler to not completely melt; if the extrusion temperature is too high, problems such as the decomposition of aluminum hydroxide and the over-expansion of unexpanded graphite may occur, which will lead to a decrease in the flame retardant performance and thermal conductivity of the composite material. After multiple comparative experiments of the present invention, it is considered that in order to cooperate with the unexpanded graphite with an initial expansion temperature of 160-170°C, the composite material with the best performance of thermal conductive flame retardant can be obtained when the extrusion temperature is 170-180°C.

[0048] One of the main inventive points of the present invention is to provide a way to highly value and reuse waste aluminum-plastic packaging. The traditional waste aluminum-plastic packaging recycling technologies generally have problems such as high energy consumption, high cost, and low recycling efficiency. The present invention uses aluminum hydroxide and / or magnesium hydroxide as the main flame retardant for the first time, and cooperates with unexpanded graphite and expanded graphite to directly prepare a high-performance thermal conductive flame retardant composite material. The material reaches the V-0 flame retardant grade of the UL94 standard, and the thermal conductivity coefficient reaches 2.74 W / mK. It has the advantages of good thermal conductivity, excellent flame retardant performance, and simple preparation process, and has significant economic and social value.

[0049] Another main inventive point of the present invention is to propose a method system for improving the flame retardant performance and thermal conductivity coefficient of polymer-based composite materials for the first time: In one of the preferred technical solutions, the present invention uses aluminum hydroxide with different particle sizes compounded as the main flame retardant, and at the same time utilizes the cooperation of unexpanded graphite, expanded graphite and compounded aluminum hydroxide to further significantly improve the flame retardant performance of the composite material. The present invention cleverly utilizes the double synergistic thermal conductive fillers constructed by unexpanded graphite and expanded graphite to synergistically achieve the high flame retardant performance of the composite material. Through retrieval, it is found that the technical solution of the present invention uses two thermal conductive fillers, unexpanded graphite and expanded graphite, to synergistically achieve the high thermal conductivity performance of the composite material for the first time.

[0050] The present invention has the following beneficial effects:

[0051] (1) Compared with traditional waste aluminum-plastic packaging recycling methods, the present invention adopts the solid-phase shear milling processing technology, without the need to separate the polymer and metallic aluminum in the aluminum-plastic composite packaging. The recycling process has low energy consumption and no secondary pollution, conforming to the concept of efficient recycling of full recycling. Moreover, the recycling process is relatively simple, with low costs and is easy to scale up production.

[0052] (2) The present invention verifies through experiments that waste aluminum-plastic composite packaging films can be directly recycled to prepare thermally conductive and flame-retardant composite materials, achieving the high-value recycling of waste aluminum-plastic.

[0053] (3) The thermally conductive and flame-retardant composite materials prepared by the present invention have good mechanical properties, flame-retardant properties, and thermal conductivity. The composite materials reach the V-0 flame-retardant grade of the UL94 standard, with a thermal conductivity of 2.74 W / mK, and the preparation process is simple. It is expected to achieve industrial production and has good market prospects. Description of the Drawings

[0054] Figure 1 It is a physical photo of the waste aluminum-plastic ultrafine powder obtained in Example 1 of the present invention.

[0055] Figure 2 It is a physical photo of the composite material splines prepared in the examples and comparative examples of the present invention.

[0056] Figure 3 It is a scanning electron microscope photo of the high-thermal conductivity and flame-retardant product spline prepared in Example 1 of the present invention. It can be clearly seen that the unexpanded graphite lamellae are attached to the micron-sized aluminum flakes, improving the three-dimensional network structure in the composite material and enhancing the thermal conductivity of the spline to a certain extent. And after adding the double synergistic thermal conductive fillers, there is a certain overlap between the fillers, which can form a good thermal conduction path and effectively promote the heat transfer inside the matrix and the fillers.

[0057] Figure 4 It is a photo of the high-thermal conductivity and flame-retardant product sample prepared in Example 1 of the present invention during the measurement of thermal conductivity.

[0058] Figure 5 It is a photo of the high-thermal conductivity and flame-retardant product sample prepared in Example 1 of the present invention during the vertical burning test.

[0059] Figure 6 It is a photo of the high-thermal conductivity and flame-retardant product sample prepared in Example 1 of the present invention during the limiting oxygen index test. Detailed Embodiments

[0060] To further understand the present invention, the preferred embodiments of the present invention will be described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the invention. Those skilled in the art can draw on the content of this article and appropriately modify the process parameters to achieve. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art, and they are all considered to be included in the present invention. The methods and applications of the present invention have been described through preferred embodiments, and those related can obviously make changes or appropriate alterations and combinations to the methods and applications described herein without departing from the content, spirit, and scope of the present invention to implement and apply the technology of the present invention. Although it is believed that those of ordinary skill in the art are fully aware of the following terms, the following definitions are still presented to help illustrate the subject matter disclosed by the present invention.

[0061] In one aspect, the present invention provides a highly thermally conductive and flame-retardant product based on waste aluminum-plastic packaging materials. According to the parts by weight, its raw materials mainly include the following components:

[0062]

[0063] Among them, the waste aluminum-plastic ultrafine powder is obtained by grinding and pulverizing the recycled waste aluminum-plastic packaging materials or products with a disk-type solid-phase force chemical reactor.

[0064] The double synergistic thermal conductive filler is composed of unexpanded graphite and expanded graphite with a mass ratio of (4-8):(7-10).

[0065] The flame-retardant filler is at least one of aluminum hydroxide and magnesium hydroxide.

[0066] It should be noted that the waste aluminum-plastic packaging materials or products described herein have not undergone aluminum-plastic separation treatment.

[0067] In this article, the waste aluminum-plastic packaging materials or products are usually the aluminum-plastic packaging materials, products, and scraps applied in the market for packaging, such as milk packaging (after separating the paper), facial masks, toothpaste, etc.; among them, the waste aluminum-plastic packaging materials or products with an aluminum content of 10-20 wt% are the preferred choices of the present invention. Those skilled in the art can query the specifications of the waste aluminum-plastic packaging materials or products to determine whether they meet the requirements for being used as the raw material selection of the present invention.

[0068] Generally speaking, the conventional aluminum-plastic packaging materials, whose component compositions are polyethylene-based / aluminum, polypropylene-based / aluminum, polyethylene terephthalate-based / aluminum, polyethylene-based / aluminum / polyethylene terephthalate, polypropylene-based / aluminum / polyethylene terephthalate, polyethylene-based / aluminum / nylon / polyethylene terephthalate, polyamide / aluminum / polypropylene, can all be used as the choices of the waste aluminum-plastic packaging materials or products of the present invention.

[0069] In one of the embodiments, the waste aluminum-plastic ultrafine powder is 41 to 53 parts, such as 41 parts, 42 parts, 43 parts, 44 parts, 45 parts, 46 parts, 47 parts, 48 parts, 49 parts, 50 parts, 51 parts, 52 parts, 53 parts or any range or point value therebetween.

[0070] In this article, the waste aluminum-plastic ultrafine powder is obtained by grinding and pulverizing the recycled waste aluminum-plastic packaging materials or products with a disk-type solid-phase force chemical reactor, where the disk-type solid-phase force chemical reactor is the force chemical reactor disclosed in the prior authorized patent ZL 95111258.9 of the applicant of the present invention. For the specific methods and parameters involved in grinding and pulverizing with the disk-type solid-phase force chemical reactor, reference can be made to the methods disclosed in the inventor's prior authorized invention patent "Method for Preparing High Thermal Conductivity Insulating 3D Printing Products by Using Waste Aluminum-Plastic Packaging" (CN112793152B), or the preparation methods disclosed below.

[0071] In this article, the compatibilizer is a conventional reactive compatibilizer, which plays a role in improving the compatibility between the double synergistic thermal conductive filler and the flame retardant filler, and ensures the synergistic thermal conduction and flame retardant effect between the double synergistic thermal conductive filler and the flame retardant filler. To better illustrate the present invention and provide a reference implementation, the selected compatibilizer includes but is not limited to at least one of polyethylene grafted maleic anhydride, chlorinated polyethylene, polyethylene grafted glycidyl methacrylate, and polyethylene grafted methyl methacrylate.

[0072] In this article, the flame retardant filler is at least one of aluminum hydroxide and magnesium hydroxide, where aluminum hydroxide and magnesium hydroxide are commercially available conventional powders. In one of the embodiments, to improve the uniform mixing of the flame retardant filler and the waste aluminum-plastic ultrafine powder, the aluminum hydroxide is a powder with an average particle size of not less than 23 μm, and the magnesium hydroxide is a powder with an average particle size of not less than 23 μm.

[0073] In one of the embodiments, the flame retardant filler is 32 to 40 parts, such as 32 parts, 33 parts, 34 parts, 35 parts, 36 parts, 37 parts, 38 parts, 39 parts, 40 parts or any range or point value therebetween.

[0074] In one of the preferred embodiments, the flame retardant filler is obtained by compounding aluminum hydroxide powder and magnesium hydroxide powder according to a mass ratio of 1:1.

[0075] In one of the more preferred embodiments, the flame retardant filler is obtained by compounding two different aluminum hydroxide powders with different average particle sizes according to a mass ratio of 1:1, and the average particle size of the first aluminum hydroxide powder is 0.6 μm, and the average particle size of the second aluminum hydroxide powder is 23 μm.

[0076] In this text, the unexpanded graphite and the expandable graphite in the common general knowledge of the technical field are the same referent, that is, when the unexpanded graphite is heated to an appropriate temperature, it can decompose instantaneously and rapidly, generating a large amount of gas, causing the graphite to expand axially into a new substance in the shape of a worm, and obtaining the expanded graphite in the common general knowledge of the technical field. In this text, the expanded graphite and the expanded graphite in the common general knowledge of the technical field are the same referent, that is, the expanded graphite obtained after the expandable graphite is expanded. For the convenience of those skilled in the art to better understand the technical solution of the present invention and to more clearly distinguish the concepts of the two fillers in the double synergistic thermal conductive filler, the unexpanded graphite and the expanded graphite are used for reference in this text. Those skilled in the art can clearly know the raw material selection adopted in the technical solution of the present invention through the above description.

[0077] In this text, both the unexpanded graphite and the expanded graphite can be obtained by purchasing commercially, or prepared by those skilled in the art according to the common general knowledge in the art. For example, the expanded graphite can be obtained by heating the unexpanded graphite to an appropriate temperature.

[0078] In one of the embodiments, the double synergistic thermal conductive filler is 12 to 16 parts, such as 12 parts, 13 parts, 14 parts, 15 parts, 16 parts or any range or point value therebetween; the double synergistic thermal conductive filler is composed of a mixture of unexpanded graphite and expanded graphite with a mass ratio of (4 to 8):(7 to 10), such as a mass ratio of 4:7, 4:8, 4:9, 4:10, 5:7, 5:8, 5:9, 5:10, 6:7, 6:8, 6:9, 6:10, 7:7, 7:8, 7:9, 7:10, 8:7, 8:8, 8:9, 8:10 or any range or point value therebetween.

[0079] In one of the embodiments, the selected unexpanded graphite has an initial expansion temperature of 160 to 170 °C and an expansion ratio of 200 to 500 ml / g. It should be noted that the selection of this expansion temperature condition is not higher than the extrusion temperature applicable to the subsequent screw extrusion processing and forming. Therefore, based on the selection of this expansion temperature, the unexpanded graphite is actually expanded during the subsequent processing and forming process.

[0080] In one of the embodiments, the selected expanded graphite is the expanded graphite with a volume expansion ratio of 50 to 300 times.

[0081] In one of the preferred embodiments, for the convenience of co-extrusion molding with the waste aluminum-plastic ultrafine powder, the particle size of the unexpanded graphite powder is 50 to 100 mesh.

[0082] In one of the preferred embodiments, for the convenience of co-extrusion molding with the waste aluminum-plastic ultrafine powder, the particle size of the expanded graphite powder is 50 to 2000 mesh.

[0083] In one of the embodiments, the raw materials may further include fillers and / or additives commonly used in plastic recycled products to achieve further functional expansion / process assistance / enhancement of the products. For the specific selection of fillers and / or additives, those skilled in the art can refer to the prior art or existing literature, such as antioxidants, lubricants, carbon-based fillers, coatings, flame retardants, anti-aging agents, heat stabilizers, coupling agents, compatibilizers, plasticizers, processing aids, etc. It should be noted that the raw materials may or may not include fillers and / or additives commonly used in plastic recycled products.

[0084] It is worth noting that generally, after knowing the above raw material components and ratios, those skilled in the art can prepare high thermal conductivity and flame retardant products consistent with those of the present invention according to the common general knowledge in the art or the disclosed prior art. For example, conventional screw extrusion granulation or mixing and extrusion granulation processes can be used to obtain high thermal conductivity and flame retardant products, or high thermal conductivity and flame retardant intermediate products can be obtained and then prepared into finished products through conventional forming processes.

[0085] To better illustrate the present invention and provide a reference implementation method, the present invention also provides a preparation method of the above high thermal conductivity and flame retardant products as a preference and reference. It should be noted that the main inventive point of the present invention lies in discovering and defining the raw material components of the above high thermal conductivity and flame retardant products, thereby further significantly improving the thermal conductivity and flame retardant performance of the products, and its preparation method is not unique.

[0086] On the other hand, the present invention provides a preparation method of high thermal conductivity and flame retardant products based on waste aluminum-plastic packaging materials, mainly including the following steps:

[0087] (1) Select waste aluminum-plastic packaging materials or products. After pretreatment including washing, crush them into waste aluminum-plastic packaging powders with an average particle size not higher than 100 μm.

[0088] (2) Add the waste aluminum-plastic packaging powders into a disk-type solid-phase force chemical reactor for grinding and crushing. After the grinding is completed, collect the waste aluminum-plastic ultrafine powders. Among them, the process parameters of the disk-type solid-phase force chemical reactor are: the grinding pressure is 3-8 MPa, the temperature of the disk surface of the grinding disk is controlled at 0-15 °C by introducing circulating cooling liquid, and the circulating grinding is carried out 2-15 times.

[0089] (3) Prepare raw materials mainly including the following components by weight:

[0090]

[0091] The double synergistic thermal conductive filler is composed of unexpanded graphite and expanded graphite mixed in a mass ratio of (4-8):(7-10).

[0092] The flame retardant filler is at least one of aluminum hydroxide and magnesium hydroxide;

[0093] (4) After uniformly mixing the raw materials prepared in step (3), add them to a twin-screw extrusion platform for melt blending. After extrusion, water cooling, and strand pelletizing, a highly thermally conductive flame retardant product is obtained; among them, the process parameters of the twin-screw extrusion platform are: extrusion temperature 170 - 180 °C, rotation speed 20 - 50 r / min.

[0094] In one implementation, the pre-treatment described in step (1) includes washing, which mainly removes impurities on the surface of waste aluminum-plastic packaging materials or products. If necessary, parts that are not aluminum-plastic packaging materials also need to be removed. Those skilled in the art can perform specific treatments according to the actual conditions of the waste aluminum-plastic packaging materials or products that need to be recycled and utilized, in accordance with existing technologies.

[0095] In one implementation, the waste aluminum-plastic packaging powder obtained by crushing the material in step (1) to an average particle size not higher than 100 μm can be processed by existing conventional crushing equipment such as jaw crushers, planetary ball mills, and cryogenic ball mills.

[0096] In this article, the disk-type solid-phase force chemical reactor described in step (2) is the force chemical reactor disclosed in the prior authorized patent ZL 95111258.9 of the applicant of the present invention.

[0097] Generally, the actual operation of the above-mentioned cyclic grinding process is to grind the material through a disk-type force chemical reactor, collect the product at the discharge end, and then place it in the disk-type force chemical reactor again for grinding treatment. The above process is regarded as 1 cycle of cyclic grinding.

[0098] In one implementation, the temperature of the disk surface in step (2) is controlled to be 0 - 15 °C by introducing a circulating cooling liquid, and the cooling liquid is ethylene glycol or water.

[0099] Generally, the process parameters of the disk-type solid-phase force chemical reactor also include process conditions such as the disk rotation speed. Except for the process parameters defined in the present invention, those skilled in the art can select appropriate other process conditions such as the disk rotation speed according to the force chemical reactor disclosed in patent ZL 95111258.9.

[0100] In this article, the "uniform mixing" described in step (4) is a conventional process method in the art, for example, dispersed uniformly by mechanical stirring such as a high-speed rotating mixer.

[0101] It should be noted that during the extrusion molding process in step (3), the aluminum-plastic ultrafine powder is blended with the flame retardant filler, unexpanded graphite, and expanded graphite. If the extrusion temperature is too low, it is easy to cause incomplete melting of the aluminum-plastic ultrafine powder and the filler; if the extrusion temperature is too high, problems such as the decomposition of aluminum hydroxide and excessive expansion of unexpanded graphite may occur, resulting in a decrease in the flame retardancy and thermal conductivity of the composite material. Through multiple comparative experiments of the present invention, it is considered that in order to cooperate with the unexpanded graphite with an initial expansion temperature of 160-170°C, the thermal conductive and flame retardant composite material obtained at an extrusion temperature of 170-180°C has the best performance.

[0102] One of the main inventive points of the present invention is to provide a way to highly value-added reuse waste aluminum-plastic packaging. Traditional waste aluminum-plastic packaging recycling technologies generally have problems such as high energy consumption, high cost, and low recycling efficiency. The present invention uses aluminum hydroxide and / or magnesium hydroxide as the main flame retardant for the first time, and cooperates with unexpanded graphite and expanded graphite to directly prepare a high-performance thermal conductive and flame retardant composite material. The material reaches the V-0 flame retardant grade of the UL94 standard, and the thermal conductivity reaches 2.74 W / mK. It has the advantages of good thermal conductivity, excellent flame retardancy, and simple preparation process, and has significant economic and social value.

[0103] Another main inventive point of the present invention is to first propose a method system for improving the flame retardancy and thermal conductivity of polymer-based composite materials: in one of the preferred technical solutions, the present invention uses compound aluminum hydroxide with different particle sizes as the main flame retardant, and at the same time utilizes the cooperation of unexpanded graphite, expanded graphite and compound aluminum hydroxide to further significantly improve the flame retardancy of the composite material. The present invention cleverly utilizes the double synergistic thermal conductive filler constructed by unexpanded graphite and expanded graphite to synergistically achieve the high flame retardancy of the composite material. Through retrieval, it is found that the technical solution of the present invention first utilizes the mutual cooperation of two thermal conductive fillers, unexpanded graphite and expanded graphite, to achieve the high thermal conductivity of the composite material.

[0104] The following will further explain the present application with reference to the embodiments. However, those skilled in the art should understand that these embodiments are provided only for the purpose of illustration and are not intended to limit the present application.

[0105] Embodiment

[0106] The following will describe the implementation scheme of the present application in detail in conjunction with the embodiments. However, those skilled in the art will understand that the following embodiments are only used to illustrate the present application and should not be regarded as limiting the scope of the present application. For those not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. Those reagents or instruments not specified by the manufacturer can be obtained through commercial purchases and are conventional products. The present application should not be construed as being limited by the specific embodiments described.

[0107] 1. Raw materials

[0108] Aluminum-plastic packaging film waste (APPW), Xiamen LuHaiHuan Co., Ltd.;

[0109] Polyethylene-graft-maleic anhydride, Dongguan Dingsheng Plastic Co., Ltd.;

[0110] Aluminium hydroxide, Yangzhou Dilan Chemical Raw Materials Co., Ltd., with an average particle size of 23um and 0.6um;

[0111] Expandable graphite (EG, D300), Qingdao Yanhai Carbon Materials Co., Ltd., with an average particle size of 80 mesh and an expansion ratio greater than 300ml / g;

[0112] Expanded graphite, Qingdao Yanhai Carbon Materials Co., Ltd., with an average particle size of 140 mesh and a volume expansion ratio of 300 times.

[0113] 2. Preparation method

[0114] (Ⅰ) Select waste aluminum-plastic packaging materials or products. After pretreatment including washing, crush them into waste aluminum-plastic packaging powder with an average particle size not higher than 100um;

[0115] (Ⅱ) Add the waste aluminum-plastic packaging powder into a disk-type solid-phase force chemical reactor for grinding and crushing. After grinding is completed, collect the waste aluminum-plastic ultrafine powder; among them, the process parameters of the disk-type solid-phase force chemical reactor are: the grinding pressure is 5 - 8MPa, the temperature of the disk surface is controlled at 4℃ by introducing circulating cooling liquid, the cycle grinding is 10 times, and the disk rotation speed is 30rpm;

[0116] (Ⅲ) Prepare raw materials mainly including the following components by weight:

[0117]

[0118] The double synergistic thermal conductive filler is composed of unexpanded graphite and expanded graphite with a mass ratio of (4 - 8):(7 - 10),

[0119] The flame retardant filler is obtained by compounding two different aluminum hydroxide powders with different average particle sizes according to a mass ratio of 1:1, and the average particle size of the first aluminum hydroxide powder is 0.6um, and the average particle size of the second aluminum hydroxide powder is 23um;

[0120] (Ⅳ) After uniformly mixing the raw materials prepared in step (Ⅲ), add them to a twin-screw extrusion platform for melt blending. After extrusion, water cooling, and strand pelletizing, a highly thermally conductive and flame-retardant product is obtained. Among them, the process parameters of the twin-screw extrusion platform are: extrusion temperature 180 °C, rotation speed 40 r / min.

[0121] 3. Test methods

[0122] The flexural properties are tested according to ASTM Standard D638-10 and ASTM Standard D790-10, and the impact test is tested according to ASTM D6110-2010 standard.

[0123] The vertical burning test is tested according to UL94-2010 standard.

[0124] The oxygen index is tested according to GB2406—80 standard.

[0125] The thermal conductivity is tested according to ISO22007-2.2 standard, and a Hot Disk constant analyzer (2500-OT Hot Disk, Sweden) based on the transient plane heat source method is used.

[0126] Examples 1-3, Comparative Examples 1-6

[0127] Examples 1-3 and Comparative Examples 1-6 are based on the above preparation methods (Ⅰ)-(Ⅳ), and with each raw material component in step (Ⅲ) as variables, an orthogonal experiment is carried out. The performance comparisons of the prepared samples are shown in Tables 1 and 2 below:

[0128] Table 1

[0129]

[0130] Table 2

[0131]

[0132] Table 1 shows the results of the limiting oxygen index and thermal conductivity of the samples prepared in the present invention. By comparing Example 1 and Comparative Example 1, it can be seen that due to the presence of aluminum sheets, the thermal conductivity of Comparative Example 1 is 1.12 W / mK. As the graphite content increases, the limiting oxygen index and thermal conductivity of the samples gradually increase. When the graphite content increases to 15 wt.%, the limiting oxygen index of the sample in Example 3 can reach 54.7%, and the thermal conductivity can reach more than 2.5 W / mK. However, for Comparative Example 3 with the same graphite content of 15 wt.%, its thermal conductivity is significantly inferior to that of Example 3, which fully demonstrates the synergistic thermal conductivity effect of unexpanded graphite and expanded graphite. By comparing Example 1, 3 and Comparative Examples 2, 3, 4, 5, 6, it can be seen that as the ratio of unexpanded graphite to expanded graphite changes, there is an optimal range for the thermal conductivity of the samples, that is, when the mass ratio of unexpanded graphite to expanded graphite is 1:1 to 1:2, the thermal conductivity of the samples in the examples is greater than 2.5 W / mK, and the thermal conductivity of Example 1 can reach 2.74 W / mK.

[0133] Table 2 shows the results of the mechanical properties of the samples prepared in the present invention. By comparing Example 1, 2, 3 and Comparative Examples 1, 2, it can be seen that as the graphite content increases, the tensile strength and flexural strength of the samples increase. Among them, the tensile strength of Example 2 is 13.4 MPa and the flexural strength is 18.4 MPa.

[0134] The above embodiments are the preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A highly thermally conductive and flame - retardant product based on waste aluminum - plastic packaging materials, characterized in that its raw materials mainly include the following components by weight parts: 41 - 53 parts of waste aluminum - plastic ultrafine powder, 3 parts of compatibilizer, 32 - 40 parts of flame - retardant filler, 12 - 16 parts of double - synergistic thermal - conductive filler, a total of 100 parts; wherein, the waste aluminum - plastic ultrafine powder is obtained by grinding and pulverizing the recycled waste aluminum - plastic packaging materials or products through a disk - type solid - phase force chemical reactor, the double - synergistic thermal - conductive filler is composed of unexpanded graphite and expanded graphite mixed in a mass ratio of (4 - 8):(7 - 10), and the flame - retardant filler is at least one of aluminum hydroxide and magnesium hydroxide.

2. The highly thermally conductive and flame - retardant product according to claim 1, characterized in that: the compatibilizer includes at least one of maleic anhydride - grafted polyethylene, chlorinated polyethylene, glycidyl methacrylate - grafted polyethylene, and methyl methacrylate - grafted polyethylene.

3. The highly thermally conductive and flame - retardant product according to claim 1, characterized in that: the aluminum hydroxide is a powder with an average particle size of not less than 23 μm, and the magnesium hydroxide is a powder with an average particle size of not less than 23 μm.

4. The highly thermally conductive and flame - retardant product according to claim 1, characterized in that: the flame - retardant filler is obtained by compounding aluminum hydroxide powder and magnesium hydroxide powder in a mass ratio of 1:

1.

5. The highly thermally conductive and flame - retardant product according to claim 1, characterized in that: the flame - retardant filler is obtained by compounding two kinds of aluminum hydroxide powders with different average particle sizes in a mass ratio of 1:1, and the average particle size of the first kind of aluminum hydroxide powder is 0.6 μm, and the average particle size of the second kind of aluminum hydroxide powder is 23 μm.

6. The highly thermally conductive and flame - retardant product according to claim 1, characterized in that: the unexpanded graphite is selected with an initial expansion temperature of 160 - 170 °C and an expansion ratio of 200 - 500 ml / g.

7. The highly thermally conductive and flame - retardant product according to claim 1, characterized in that: the expanded graphite is selected as the expanded graphite with a volume expansion ratio of 50 - 300 times.

8. The highly thermally conductive and flame - retardant product according to claim 1, characterized in that: the particle size of the unexpanded graphite powder is 50 - 100 mesh; the particle size of the expanded graphite powder is 50 - 2000 mesh.

9. The highly thermally conductive and flame - retardant product according to claim 1, characterized in that: the raw materials also include any one or more of coatings, anti - aging agents, coupling agents, and processing aids.

10. A preparation method of a highly thermally conductive and flame - retardant product based on waste aluminum - plastic packaging materials, characterized in that it mainly includes the following steps: (1) Select waste aluminum - plastic packaging materials or products. After pretreatment including washing, crush them into waste aluminum - plastic packaging powder with an average particle size of not higher than 100 μm. (2) Add the waste aluminum-plastic packaging powder into a disk-type solid-phase force chemical reactor for grinding and pulverization. After the grinding is completed, collect the waste aluminum-plastic ultrafine powder. Among them, the process parameters of the disk-type solid-phase force chemical reactor are as follows: the grinding pressure is 3-8 MPa, the temperature of the disk surface is controlled at 0-15 °C by introducing circulating cooling liquid, and the circulating grinding is carried out 2-15 times; (3) Prepare the raw materials mainly including the following components according to parts by weight: 41-53 parts of waste aluminum-plastic ultrafine powder, 3 parts of compatibilizer, 32-40 parts of flame retardant filler, 12-16 parts of double synergistic heat conductive filler, A total of 100 parts; The double synergistic heat conductive filler is composed of unexpanded graphite and expanded graphite mixed in a mass ratio of (4-8):(7-10), The flame retardant filler is at least one of aluminum hydroxide and magnesium hydroxide; (4) After mixing the raw materials prepared in step (3) evenly, add them to a twin-screw extrusion platform for melt blending. After extrusion, water cooling, and strand pelletization, a high thermal conductivity and flame retardant product is obtained. Among them, the process parameters of the twin-screw extrusion platform are as follows: the extrusion temperature is 170-180 °C, and the rotation speed is 20-50 r / min.

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