A method for preparing high-strength heat-conducting composite nylon material by using waste carbon fiber reinforced epoxy resin material

Abstract

The application provides a method for preparing high-strength heat-conducting composite nylon material by using waste carbon fiber reinforced epoxy resin material. The method is that waste carbon fiber reinforced epoxy resin material or products are ground into mixed powder by a millstone type solid phase mechanochemical reactor, the mixed powder is added into nylon raw materials, and high-strength heat-conducting composite nylon material is prepared by a conventional screw extrusion granulation process. The method realizes high-value recycling of waste carbon fiber reinforced epoxy resin, conforms to the full recycling concept in the field of material recycling, and avoids environmental pollution caused by selective recycling in the prior art.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of recycling of polymer materials, and relates to a method for preparing high-strength and high-thermal-conductivity composite nylon material from waste carbon fiber reinforced epoxy resin material, in particular to the participation of a force chemical reactor disclosed in Chinese authorized invention patent ZL95111258.9 in the preparation. BACKGROUND

[0002] The carbon fiber reinforced epoxy resin material has excellent chemical corrosion resistance, high strength and fatigue resistance, and is one of the main manufacturing materials for wind turbine blade spars, high-end automobile chassis and high-end sports. In the recycling process of the waste carbon fiber reinforced epoxy resin material, the epoxy resin is a thermosetting resin with a three-dimensional highly cross-linked network structure, and is insoluble and infusible, which is difficult to recycle and utilize. At present, the recycling method for the carbon fiber reinforced epoxy resin material in the existing technology mainly degrades the epoxy resin to recover the carbon fiber by a chemical method. This method has been studied more, but the problem of secondary pollution of toxic and harmful chemical solvents needs to be solved. Another main recycling method is to prepare a powder by a physical method, and then directly fill the polymer to prepare a composite material. This method has the advantages of easy industrial implementation and strong operability, but has the problems of poor performance of the regenerated product and low added value.

[0003] Through retrieval, the current existing technology for recycling the carbon fiber reinforced epoxy resin material mainly uses the recycled carbon fiber after removing the epoxy resin, for example, the Chinese invention patent applications CN103709703A and CN113292817A both select the recycled carbon fiber after removing the epoxy resin as raw material. This is because the epoxy resin attached to the carbon fiber has too high cross-linking degree and too low reactivity, so it cannot be reused, and at the same time, the surface of the carbon fiber is covered with epoxy resin, which greatly affects the full play of the mechanical properties, thermal conductivity and other functional properties of the carbon fiber. Therefore, the epoxy resin needs to be removed in advance to facilitate subsequent utilization.

[0004] However, the above-mentioned existing technology needs to remove the epoxy resin from the carbon fiber reinforced epoxy resin material in advance, which undoubtedly greatly increases the process cost of recycling and reusing, and the product performance in the currently disclosed documents is not compared with the same specification product using non-recycled carbon fiber raw material, which indirectly indicates that the product performance may have performance deficiencies compared with the same specification product, and cannot be completely replaced. SUMMARY

[0005] The purpose of the present application is to solve the problems in the background art described above, and to provide a method for preparing high-strength heat-conducting composite nylon material by using waste carbon fiber reinforced epoxy resin material, which realizes the high-value recycling of waste carbon fiber reinforced epoxy resin, conforms to the full recycling concept in the field of material recycling, and avoids environmental pollution caused by selective recycling in the prior art.

[0006] To achieve the above-mentioned purpose, the present application is realized by adopting the technical scheme consisting of the following technical measures.

[0007] A method for preparing high-strength heat-conducting composite nylon material by using waste carbon fiber reinforced epoxy resin material, comprising the following steps:

[0008] (1) Selecting waste carbon fiber reinforced epoxy resin material or products, after pretreatment including washing, crushing the waste material to a particle size of not more than 2 cm;

[0009] (2) Adding the waste material obtained in step (1) to a grinding disc type force chemical reactor for grinding and crushing, and collecting the mixed powder after grinding is completed; wherein the process parameters of the grinding disc type force chemical reactor are: grinding pressure is 5-8 MPa, the disc surface temperature is controlled by circulating liquid medium with a temperature of 2℃ or lower, the grinding disc speed is 45-50 rpm, and the cycle grinding is 0-2 times;

[0010] (3) Mixing the following main raw material components including the mixed powder obtained in step (2) by weight fraction, as a mixture:

[0011] Mixed powder 10-30 parts,

[0012] Nylon 50-75 parts;

[0013] (4) The mixture obtained in step (3) is prepared into high-strength heat-conducting composite nylon material by conventional screw extrusion granulation process. The high-strength heat-conducting composite nylon material can be further prepared into high-strength heat-conducting composite nylon products by selecting conventional molding processes such as injection molding.

[0014] Generally, the waste carbon fiber reinforced epoxy resin material or product in step (1) includes industrial waste with large amount of waste such as scrap, waste, etc. produced during the synthesis and production of carbon fiber reinforced epoxy resin, and waste products such as wind turbine blades, automobile bumpers, rocket engine shells and sports equipment, etc. made of carbon fiber reinforced epoxy resin material. Those skilled in the art can query whether the specifications of the waste carbon fiber reinforced epoxy resin material or product meet the selection as raw materials of the present application.

[0015] In this context, the pretreatment in step (1) includes washing, which is mainly to remove the surface impurities of the waste carbon fiber reinforced epoxy resin material or product, and if necessary, to remove part of the non-epoxy resin and carbon fiber. Those skilled in the art can refer to the actual situation of the waste carbon fiber reinforced epoxy resin material or product to be recycled, and perform specific treatment according to the prior art.

[0016] Generally, the waste coarse material in step (1) is crushed to a particle size of not more than 2 cm, which can be processed by existing conventional crushing equipment such as a jaw crusher.

[0017] In this context, the millstone type force chemical reactor in step (2) is the force chemical reactor disclosed in the previously granted patent ZL95111258.9 of the applicant, and the temperature of the millstone is controlled by circulating a constant-temperature liquid medium in the millstone. Generally, the liquid medium is water.

[0018] Generally, the circulating grinding process in step (2) is that after the mixture is ground in the millstone type force chemical reactor, the product at the discharge end is collected and then placed in the millstone type force chemical reactor for grinding treatment again. The above process is considered as one cycle of circulating grinding. Similarly, when the circulating grinding is 0 times, it means that only one grinding is performed without two times of grinding.

[0019] In this context, the nylon in step (3) is a conventional nylon selected in the technical field, and those skilled in the art can select appropriate nylon varieties according to specific needs and process requirements, or refer to the conventional nylon selection in the application field of the final product.

[0020] In one of the technical solutions, the nylon in step (3) is any one of nylon-6, nylon-66, nylon-610, nylon-612, nylon-46, and nylon-1010.

[0021] In one of the technical solutions, the main raw material component in step (3) can also include fillers or / and auxiliaries commonly used in nylon composites to achieve further functional expansion / process assistance / enhancement of the product. The specific selection of fillers or / and auxiliaries can be referred to the prior art or existing literature, such as antioxidants, lubricants, carbon fillers, coatings, flame retardants, anti-aging agents, thermal stabilizers, coupling agents, plasticizers, compatibilizers, processing aids, etc. It is noted that the main raw material component in step (3) can include or not include fillers or / and auxiliaries commonly used in nylon composites.

[0022] In one preferred embodiment, the main raw material component in step (3) further comprises 15-20 parts of modified boron nitride to block the conductive path of carbon fibers and impart excellent insulation properties.

[0023] In one preferred embodiment, the modified boron nitride is boron nitride modified with a silane coupling agent to improve compatibility with nylon, and the silane coupling agent can be any one of KH550, KH560, KH570, A-187, Z-7076. To better illustrate the present application, a preparation method of modified boron nitride is provided for reference. The preparation method of the modified boron nitride is as follows: KH550 is prepared into a 1-3 wt% KH550 aqueous solution, then boron nitride is added, the mass ratio of boron nitride to KH550 is 33-40:1, stirring is carried out at 80-90°C for 6-8h, and the modified boron nitride is obtained after filtration and drying.

[0024] In this context, the mixture obtained in step (3) is prepared into a high-strength heat-conducting composite nylon material by a conventional screw extrusion granulation process, which is a conventional granulation process selection in the technical field. To better illustrate the present application, a granulation process selection is provided for reference. The screw extrusion granulation process is as follows: the mixture is extruded through a twin-screw extruder, then drawn, water-cooled, air-blasted, granulated, and dried.

[0025] The main point of the present application is that, based on the conventional method of removing epoxy resin from carbon fiber reinforced epoxy resin materials in the prior art, the inventors of the present application attempt to use a pure force chemical method of a mill-type force chemical reactor to remove the epoxy resin attached to the carbon fibers at a lower cost and in an environmentally friendly manner.

[0026] However, during the trial and exploration process of removing epoxy resin using a mill-type force chemical reactor, the inventors accidentally discovered that under special grinding process parameters, the nylon composite material sample prepared from the ground mixed powder showed a significant improvement in mechanical properties, which far exceeded the expectations of those skilled in the art and exceeded the nylon composite material sample prepared from the same proportion of non-recycled carbon fiber raw materials in the comparative experiment, showing excellent replaceability.

[0027] In the subsequent repeated experiments and verification experiments, through electron microscope observation and analysis, it is found that under the above special grinding process parameters, the mixed powder after grinding is mainly composed of carbon fibers with a small amount of spot-shaped epoxy resin attached to the surface and part of the carbon fibers and epoxy resin ultrafine powder, which shows that although a large amount of epoxy resin has been removed, it is not completely removed, so that the surface area and roughness of the carbon fiber surface are significantly increased due to the embedded epoxy resin, thereby affecting the mechanical properties of the subsequent sample, and showing better technical effect than new carbon fiber. The electron micrograph corresponding to this phenomenon can be seen in the drawings shown in the specification. This unexpected discovery by those skilled in the art greatly facilitates the promotion of the replacement of waste carbon fiber reinforced epoxy resin material regenerated products.

[0028] In addition, the technical scheme of the present application can utilize the waste carbon fiber reinforced epoxy resin material completely, which is different from the existing technology which still needs to process the removed epoxy resin material part, has better recycling efficiency, meets the full recycling concept in the material recycling field, and has significant environmental and cost advantages compared with the prior art.

[0029] However, considering that the epoxy resin ultrafine powder may affect the performance of the final product, the mixed powder in step (2) can also be additionally selected to retain only the carbon fiber part with a small amount of spot-shaped epoxy resin attached to the surface by sieving or other methods.

[0030] The present application has the following beneficial effects:

[0031] (1) The technical scheme provided by the present application realizes the high-value recycling of waste carbon fiber reinforced epoxy resin, meets the full recycling concept in the material recycling field, and avoids environmental pollution caused by selective recycling in the prior art.

[0032] (2) In the technical scheme provided by the present application, the epoxy resin attached to the surface of the waste carbon fiber in a small amount of spot shape can form more effective contact with the nylon matrix, so that the product prepared by the technical scheme of the present application has excellent heat conduction performance and high mechanical strength, and can be used in environments with more mechanical fields.

[0033] (3) In the preferred technical scheme, boron nitride can be additionally added to construct an efficient heat conduction network, while also blocking the conductive path between carbon fibers, realizing heat conduction and insulation, which is beneficial to use in the field of electronic and electrical appliances.

[0034] (4) The technical scheme provided by the present application does not need to use any chemical means, and can be used directly after grinding, which is simple to prepare and low in cost. The prepared material has good chemical stability and temperature resistance, and is expected to realize industrialized production and has good market prospect. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 Process flow diagram of Example 7 of the present application.

[0036] Figure 2 The electron microscope images of the carbon fibers in the mixed powders obtained in Example 1, 2 and Comparative Example 1 of the present application. In the images, (c) is the electron microscope image of the carbon fibers in the mixed powder obtained in Comparative Example 1 by the conventional pulverization method, and it can be seen that the surface of the carbon fibers is uniformly covered with a layer of epoxy resin; (f) is the electron microscope image of the carbon fibers in the mixed powder obtained after 0 cycles of the cyclic milling in Example 1, and it can be seen that the surface of the carbon fibers presents a small amount of spot-shaped epoxy resin; and (i) is the electron microscope image of the carbon fibers in the mixed powder obtained after 1 cycle of the cyclic milling in Example 2, and it can be seen that only a very small amount of epoxy resin is attached to the surface of the carbon fibers, indicating that the epoxy resin is basically stripped.

[0037] Figure 3 The mechanical property test results of the composite nylon products prepared in Example 1, 6-7 and Comparative Examples 4-6 under different contents of the modified boron nitride. In the images, PA is the sample prepared in Comparative Example 4 using pure nylon 6, and 0, 5, 10, 15 and 20 are the samples prepared when the content of the modified boron nitride is 0wt%, 5wt%, 10wt%, 15wt% and 20wt%, respectively.

[0038] Figure 4 The thermal conductivity test results of the composite nylon products prepared in Example 1, 6-7 and Comparative Examples 4-10 under different contents of the modified boron nitride. In the left image, Comparative Examples 4, 7-10 are the samples prepared using nylon-6 and different proportions of the modified boron nitride; and in the right image, PA is the sample prepared in Comparative Example 4 using pure nylon 6, and 0, 5, 10, 15 and 20 are the samples prepared when the content of the modified boron nitride is 0wt%, 5wt%, 10wt%, 15wt% and 20wt%, respectively.

[0039] Figure 5 The infrared thermal imaging comparison of the composite nylon products prepared in Example 7, Comparative Example 4 and Comparative Example 10 under different contents of the modified boron nitride. In the images, PA is the sample prepared in Comparative Example 4 using pure nylon 6, PA / BN is the sample prepared in Comparative Example 10 by blending nylon 6 and the modified boron nitride, and WFRE / PA / BN is the sample prepared in Example 7.

[0040] Figure 6The figure of the test results of the electric conductivity of the composite nylon products prepared in Examples 6-7, Comparative Examples 5-6 and Comparative Example 10 under the condition of different contents of the modified boron nitride. In the figure, PA / BN20 is the sample prepared by blending nylon 6 and the modified boron nitride in Comparative Example 10, and BN-5, 10, 15 and 20 are the samples prepared when the content of the modified boron nitride is 5wt%, 10wt%, 15wt% and 20wt%, respectively. DETAILED DESCRIPTION

[0041] In order to further understand the present application, the preferred embodiments of the present application are described below in conjunction with the examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present application, and are not limitations to the claims of the present application. The skilled in the art can modify the process parameters according to the content herein. It is particularly pointed out that all similar replacements and changes are obvious to the skilled in the art, and they are considered to be included in the present application. The method and application of the present application have been described by the preferred embodiments, and the related personnel can obviously modify or appropriately change and combine the method and application described herein without departing from the content, spirit and scope of the present application, to realize and apply the present application technology. Although it is believed that the following terms are well understood by the ordinary skilled in the art, the following definitions are stated to facilitate the explanation of the disclosed subject matter.

[0042] A method for preparing a high-strength and high-thermal-conductivity composite nylon material by using waste carbon fiber reinforced epoxy resin material, comprising the following steps:

[0043] (1) selecting waste carbon fiber reinforced epoxy resin material or products, after pretreatment including washing, the waste coarse material is processed and crushed to a particle size of not more than 2 cm;

[0044] (2) the waste coarse material obtained in step (1) is added to a mill-type force chemical reactor for grinding and crushing, and after grinding is completed, the mixed powder is collected; wherein the process parameters of the mill-type force chemical reactor are: the grinding pressure is 5-8 MPa, the disc surface temperature is controlled by circulating liquid medium with a temperature of 2℃ or lower, the mill disc speed is 45-50 rpm, and the circulation grinding is 0-2 times;

[0045] (3) the following main raw material components including the mixed powder obtained in step (2) are mixed by weight fraction as a mixture:

[0046] mixed powder 10-30 parts,

[0047] nylon 50-75 parts;

[0048] (4) The mixture obtained in step (3) is prepared into high-strength heat-conducting composite nylon material by a conventional screw extrusion granulation process. The high-strength heat-conducting composite nylon material can be further prepared into high-strength heat-conducting composite nylon products by a conventional molding process such as injection molding.

[0049] Generally, the waste carbon fiber reinforced epoxy resin material or product in step (1) includes a large amount of industrial waste such as offcuts, waste materials and the like generated in the synthesis and production process of carbon fiber reinforced epoxy resin, and waste products such as wind turbine blades, automobile bumpers, rocket engine casings and sports equipment, etc. made of carbon fiber reinforced epoxy resin material. Those skilled in the art can determine whether the specifications of the waste carbon fiber reinforced epoxy resin material or product meet the selection criteria for raw materials of the present application.

[0050] In this context, the pre-treatment in step (1) includes washing and cleaning, which mainly removes impurities on the surface of the waste carbon fiber reinforced epoxy resin material or product, and if necessary, removes part of the non-epoxy resin and carbon fiber. Those skilled in the art can perform specific treatment according to existing technologies based on the actual conditions of the waste carbon fiber reinforced epoxy resin material or product to be recycled.

[0051] In one embodiment, the waste coarse material in step (1) is processed to a uniform particle size of not more than 2 cm by using existing conventional crushing equipment such as a jaw crusher. For example, the waste coarse material can be processed to a uniform particle size of not more than 2 cm, 1.5 cm, 1 cm, 0.5 cm, 0.4 cm, 0.3 cm, 0.2 cm, 0.1 cm or any range or point value therebetween.

[0052] In this context, the millstone type mechanochemical reactor in step (2) is the mechanochemical reactor disclosed in the previously granted patent ZL95111258.9 of the present applicant, and the temperature of the millstone is controlled by circulating a constant-temperature liquid medium through the millstone. Generally, the liquid medium is water.

[0053] Generally, the process of circulating grinding in step (2) is that after the mixture is ground in the millstone type mechanochemical reactor, the product is collected from the discharge end and then placed in the millstone type mechanochemical reactor for grinding again. The above process is considered as one cycle of circulating grinding. Similarly, when the circulating grinding is 0 times, it means that only one grinding is performed without two times of grinding.

[0054] In one embodiment, the process parameters of the attrition disc type mechanochemical reactor in step (2) are as follows: the milling pressure is 5-8 MPa, such as 5 MPa, 5.5 MPa, 6 MPa, 6.5 MPa, 7 MPa, 7.5 MPa, 8 MPa, or any range or point value therebetween; the attrition disc surface temperature is controlled by circulating a liquid medium at a temperature of 2°C or lower, such as 2°C, 1.5°C, 1°C, 0.5°C, 0°C, -1°C, -2°C, -4°C, or any range or point value therebetween; the attrition disc rotation speed is 45-50 rpm, such as 45 rpm, 46 rpm, 47 rpm, 48 rpm, 49 rpm, 50 rpm, or any range or point value therebetween; and the circulation milling is 0-2 times, such as 0 times, 1 time, 2 times.

[0055] In this context, the nylon in step (3) is a conventional nylon selected in the art, and a person skilled in the art can select an appropriate nylon variety according to specific needs and process requirements, or can refer to conventional nylon selection in the field of application of the final product.

[0056] In one embodiment, the nylon in step (3) is any one of nylon-6, nylon-66, nylon-610, nylon-612, nylon-46, and nylon-1010.

[0057] In one embodiment, the mixed powder in step (3) is 10-30 parts, such as 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, 30 parts, or any range or point value therebetween; and the nylon is 50-75 parts, such as 50 parts, 51 parts, 52 parts, 53 parts, 54 parts, 55 parts, 56 parts, 57 parts, 58 parts, 59 parts, 60 parts, 61 parts, 62 parts, 63 parts, 64 parts, 65 parts, 66 parts, 67 parts, 68 parts, 69 parts, 70 parts, 71 parts, 72 parts, 73 parts, 74 parts, 75 parts, or any range or point value therebetween.

[0058] In one embodiment, the main raw material component in step (3) can also include fillers or / and auxiliaries commonly used in nylon composites to achieve further functional expansion / process assistance / enhancement of the product. The specific selection of fillers or / and auxiliaries can be referred to existing technologies or existing literature, such as antioxidants, lubricants, carbon fillers, coatings, flame retardants, anti-aging agents, thermal stabilizers, coupling agents, plasticizers, compatibilizers, processing aids, etc. It is noted that the main raw material component in step (3) can or can not include fillers or / and auxiliaries commonly used in nylon composites.

[0059] In one preferred embodiment, the main raw material component in step (3) further comprises 15-20 parts of modified boron nitride, such as 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, or any range or point value therebetween; to block the conductive channel of carbon fibers, and give it excellent insulation.

[0060] In one preferred embodiment, the modified boron nitride is boron nitride modified with a silane coupling agent to improve compatibility with nylon, and the silane coupling agent can be any one of KH550, KH560, KH570, A-187, Z-7076. In order to better illustrate the present application, and provide a reference for the preparation of modified boron nitride, the preparation method of the modified boron nitride is as follows: KH550 is prepared into a 1-3wt% KH550 aqueous solution, then boron nitride is added and the mass ratio of boron nitride to KH550 is 33-40:1, stirring at 80-90℃ for 6-8h, filtering and drying to obtain modified boron nitride.

[0061] In this paper, the mixture obtained in step (3) is prepared into a high-strength heat-conducting composite nylon material by a conventional screw extrusion granulation process, which is a conventional granulation process selection in the technical field. In order to better illustrate the present application, and provide a reference for the granulation process selection, the screw extrusion granulation process is as follows: the mixture is extruded through a double-screw extruder, then pulled, water-cooled, air-blasted, granulated, and dried.

[0062] The main point of the present application is that based on the conventional method of removing epoxy resin from carbon fiber reinforced epoxy resin material in the prior art, the inventors of the present application attempt to use a pure force chemical method of a mill-type force chemical reactor to remove the epoxy resin attached to the carbon fiber in a more cost-effective and environmentally friendly way.

[0063] However, during the trial and exploration process of removing epoxy resin by using a mill-type force chemical reactor, the inventors accidentally found that under special grinding process parameters, the nylon composite material sample prepared from the ground mixed powder showed a significant improvement in mechanical properties, and the improvement was far beyond the expectation of the skilled person in the art, exceeding the nylon composite material sample prepared from the same proportion of non-recycled carbon fiber raw material in the comparative experiment, showing excellent replaceability.

[0064] In the subsequent repeated experiments and verification experiments, through electron microscope observation and analysis, it is found that under the above special grinding process parameters, the mixed powder after grinding is mainly composed of carbon fibers with a small amount of spot-shaped epoxy resin attached to the surface and part of the carbon fibers and epoxy resin ultrafine powder, which indicates that although a large amount of epoxy resin has been removed, it is not completely removed, so that the surface area and roughness of the carbon fiber surface are significantly increased due to the embedded epoxy resin, thereby affecting the mechanical properties of the subsequent sample, and showing better technical effect than the new carbon fiber. The electron micrograph corresponding to this phenomenon can be seen in the drawings shown in the specification. This unexpected discovery by those skilled in the art greatly facilitates the promotion of the replacement of waste carbon fiber reinforced epoxy resin material regenerated products.

[0065] In addition, the technical scheme of the present application can utilize the waste carbon fiber reinforced epoxy resin material completely, which is different from the prior art which still needs to process the removed epoxy resin material part, has better recycling efficiency, meets the full recycling concept in the material recycling field, and has significant environmental protection and cost advantages compared with the prior art.

[0066] However, considering that the epoxy resin ultrafine powder may affect the performance of the final product, the mixed powder in step (2) can also be additionally selected to retain only the carbon fiber part with a small amount of spot-shaped epoxy resin attached to the surface by sieving or other methods.

[0067] The present application will be further explained in detail with reference to the following examples. However, those skilled in the art will understand that these examples are provided only for illustrative purposes, and are not intended to limit the scope of the present application.

[0068] Examples

[0069] The embodiments of the present application will be described in detail below with reference to examples, but those skilled in the art will understand that the following examples are only for the purpose of illustration, and should not be regarded as limiting the scope of the present application. If no specific conditions are specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are used. If no manufacturer of the reagent or instrument is specified, it is a conventional product that can be obtained by purchase. The present application should not be interpreted as being limited to the specific examples described.

[0070] 1. Raw materials

[0071] Waste carbon fiber reinforced epoxy resin (Chengdu Lucheng New Material Technology Co., Ltd.)

[0072] Nylon-6 (BL3280H, China Petroleum Chemical Industry Co., Ltd. Balin Branch)

[0073] Boron nitride (Shanghai Pantian Powder Material Co., Ltd.)

[0074] Anhydrous ethanol, KH550, deionized water (analytical pure, Chengdu Kolon Chemicals Co., Ltd.)

[0075] 2. Preparation method

[0076] (1) Selecting waste carbon fiber reinforced epoxy resin material or product, after pretreatment including washing, it is treated and crushed to waste coarse material with uniform particle size not higher than 2 cm;

[0077] (2) The waste coarse material obtained in step (1) is added to the mill type force chemical reactor for grinding and crushing, after grinding is completed, the mixed powder is collected; wherein the process parameters of the mill type force chemical reactor are: the grinding pressure is 6 MPa, the mill disc surface temperature is controlled by circulating liquid medium with temperature below 2℃, the mill disc rotating speed is 50 rpm, and the circulating grinding is 0-2 times;

[0078] (3) The following main raw material components including the mixed powder obtained in step (2) are mixed according to weight fraction, as the mixed material:

[0079] Mixed powder 10-30 parts,

[0080] Nylon-6 50-75 parts;

[0081] (4) The mixed material obtained in step (3) is prepared into high-strength heat-conducting composite nylon material through conventional screw extrusion granulation process, and then the sample is obtained by injection molding.

[0082] 3. Test method

[0083] Mechanical properties: according to ISO 527 and ISO 178 standards, the tensile properties and bending properties of the composite material were tested by electronic universal testing machine (RGL-10 and De Xiangke DWD-10). According to ISO 179 standard, impact test was carried out by Zwick impact tester.

[0084] Thermal conductivity coefficient test: the transient position source method of ISO 22007-2.2 standard was adopted, the thermal conductivity of the sample with thickness of 2 mm was studied by Hot Disk thermal analyzer (2600-OT, Sweden), and the test condition was room temperature. Infrared thermal imager (Testo 870-2, Germany) was used to study the infrared thermal imaging of the composite material.

[0085] Insulation test: The electrical properties of the polymer matrix were tested using a high insulation resistance meter (ZC36, China). The sample was a plate with a length of 100 mm, a width of 100 mm, and a thickness of 4 mm. The resistivity of the composite material with high electrical conductivity was characterized by a digital source meter (Keithley 2400, USA). The sample was a disc with a diameter of 20 mm and a thickness of 2 mm. The surface of the sample was coated with conductive silver paste before testing.

[0086] Examples 1-3, Comparative Example 1

[0087] Examples 1-3, Comparative Example 1 are when the proportion of mixed powder in the mixture is 30wt%, the number of cycles of milling is used as a variable, and the mechanical properties of the prepared samples are compared as shown in Table 1 below:

[0088] Table 1

[0089]

[0090] Among them, Comparative Example 1 is to use a conventional milling device to mill the waste carbon fiber reinforced epoxy resin to a particle size close to the particle size when the number of cycles of milling is 0.

[0091] It is obvious to see that when the number of cycles of milling is 0, the mechanical properties of the prepared sample are the best. By observing the electron microscope image, the epoxy resin on the surface of the carbon fiber of the mixed powder obtained after 0 cycles of milling presents a spotted attachment, which greatly increases the surface area.

[0092] Examples 4-5, Comparative Examples 2-3

[0093] Examples 4-5, Comparative Examples 2-3 are when the number of cycles of milling is 0, the mechanical properties of the samples prepared by using waste carbon fiber reinforced epoxy resin as raw material are compared with those prepared by using non-waste carbon fiber and epoxy resin as raw material, as shown in Table 2 below:

[0094] Table 2

[0095]

[0096] It is obvious to see that the tensile properties, bending properties and impact properties of the samples prepared in Examples 4 and 5 are higher than those of the corresponding comparative samples. It is speculated that this may be due to the fact that there is still some epoxy resin on the surface of the carbon fiber in the waste carbon fiber reinforced epoxy resin powder after solid-phase shear milling, which makes the surface rougher and the surface area larger than that of pure carbon fiber, enabling better contact and intercalation with the nylon-6 matrix, thereby exhibiting better mechanical properties.

[0097] Examples 6-7, Comparative Examples 4-6

[0098] In Example 1, Example 6-7 and Comparative Example 3-5, the mechanical properties, thermal conductivity and insulation properties of the prepared samples were compared when the modified boron nitride was also included in the mixture in step (3).

[0099] The modified boron nitride was prepared by preparing a 2wt% KH550 aqueous solution, then adding boron nitride with a boron nitride to KH550 mass ratio of 33:1, stirring and reacting at 80°C for 8h, and then filtering and drying to obtain the modified boron nitride.

[0100] No modified boron nitride was added in Example 1.

[0101] Comparative Example 4 was prepared using pure nylon 6.

[0102] In Comparative Example 5, the ratio of the mixed powder to nylon 6 was consistent with Example 1, and a total amount of 5wt% modified boron nitride was added, and the rest was consistent with Example 1.

[0103] In Comparative Example 6, the ratio of the mixed powder to nylon 6 was consistent with Example 1, and a total amount of 10wt% modified boron nitride was added, and the rest was consistent with Example 1.

[0104] In Example 6, the ratio of the mixed powder to nylon 6 was consistent with Example 1, and a total amount of 15wt% modified boron nitride was added, and the rest was consistent with Example 1.

[0105] In Example 7, the ratio of the mixed powder to nylon 6 was consistent with Example 1, and a total amount of 20wt% modified boron nitride was added, and the rest was consistent with Example 1.

[0106] Comparative Examples 7-10 were based on Comparative Example 4, and a total amount of 5wt%, 10wt%, 15wt%, and 20wt% modified boron nitride was added, respectively, to prepare the samples.

[0107] The test results are shown in the accompanying drawings Figures 3 to 6 It is fully proved that the performance of the composite nylon material is significantly improved after adding the mixed powder.

Claims

1. A method for preparing high-strength, thermally conductive composite nylon material using waste carbon fiber reinforced epoxy resin material, characterized in that... Includes the following steps: (1) Select waste carbon fiber reinforced epoxy resin materials or products, and after pretreatment including washing, process and crush them into waste coarse materials with an average particle size of no more than 2 cm. (2) The waste coarse material obtained in step (1) is added to the grinding disc type mechanical chemical reactor and ground into powder. After grinding is completed, the mixed powder is collected. The process parameters of the grinding disc type mechanical chemical reactor are: grinding pressure is 5~8MPa, grinding disc surface temperature is controlled by introducing a constant temperature circulating liquid medium with a temperature below 2℃, grinding disc speed is 45~50rpm, and grinding is 0~2 times. The actual operation of the cyclic milling process is to mill the material in a disc-type mechanochemical reactor, collect the product at the discharge end, and then put it back into the disc-type mechanochemical reactor for milling. The above process is considered as one cycle of milling. (3) Mix the following raw material components, including the mixed powder obtained in step (2), by weight to form a mixture: Mix 10-30 parts of powder. 50-75 parts nylon; (4) The mixture obtained in step (3) is processed by conventional screw extrusion granulation process to prepare high-strength thermally conductive composite nylon material.

2. The method according to claim 1, characterized in that: The nylon used in step (3) is selected from any one of nylon-6, nylon-66, nylon-610, nylon-612, nylon-46, and nylon-1010.

3. The method according to claim 1, characterized in that: The raw material components mentioned in step (3) also include any one or more of the following: antioxidants, lubricants, carbon-based fillers, coatings, flame retardants, anti-aging agents, heat stabilizers, coupling agents, plasticizers, and compatibilizers.

4. The method according to claim 1, characterized in that: The raw material components in step (3) also include 15 to 20 parts of modified boron nitride.

5. The method according to claim 4, characterized in that: The modified boron nitride is boron nitride modified with a silane coupling agent, which includes any one of KH550, KH560, KH570, and A-187.

6. The method according to claim 5, characterized in that: The modified boron nitride is prepared by preparing a 1-3 wt% aqueous solution of KH550, then adding boron nitride at a mass ratio of 33-40:1 to KH550, stirring and reacting at 80-90°C for 6-8 hours, and then filtering and drying to obtain modified boron nitride.

7. The method according to claim 1, characterized in that: The cyclic grinding in step (2) is 0 times.

8. The high-strength thermally conductive composite nylon material prepared by the method for preparing high-strength thermally conductive composite nylon material using waste carbon fiber reinforced epoxy resin material as described in claim 1.

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