High-wear-resistance POM / TPU / graphene composite material and preparation method thereof

Abstract

The invention provides a high-wear-resistance POM / TPU / graphene composite material and a preparation method thereof.The preparation method comprises the steps that 89-91 parts by weight of polyformaldehyde and 0.28-0.32 part by weight of graphene are subjected to melt blending to prepare a POM / graphene primary material, then the POM / graphene primary material and 9-11 parts by weight of thermoplastic polyurethane elastomer are added into a millstone type solid-phase mechanochemical reactor for co-grinding and smashing, and the POM / TPU / graphene composite material is obtained; and carrying out melt extrusion on the obtained composite powder through a twin-screw extruder, and carrying out pelletizing so as to obtain the high-wear-resistance POM / TPU / graphene composite material. According to the preparation method disclosed by the invention, uniform dispersion of the graphene is realized by utilizing a solid-phase shearing and grinding technology (S3M), and meanwhile, when the graphene is in a specific addition amount, the friction coefficient and the specific wear rate of the finally prepared sample are abnormally and remarkably improved through a co-grinding preparation process of the graphene and the polyformaldehyde; a foundation is provided for subsequent research on the wear resistance of the graphene reinforced composite polymer material.

Description

Technical Field

[0001] The invention belongs to the technical field of graphene-reinforced polyoxymethylene composite materials, and relates to a highly wear-resistant POM / TPU / graphene composite material and a preparation method thereof, in particular to the preparation method using a mechanochemical reactor disclosed in Chinese authorized invention patent ZL 95111258.9. Background Art

[0002] In the field of tribology, wear-resistant materials are one of the key research areas, and polymer materials with low friction coefficient and low wear rate are developing rapidly in the field of wear-resistant materials due to their low cost and good processing performance. Among many polymer materials, polyoxymethylene (POM) has earned the reputation of "steel" and "super steel" due to its excellent mechanical properties. At the same time, its self-lubrication, chemical corrosion resistance and low cost make it one of the important candidates for wear-resistant polymer materials. Through modification, its friction coefficient and wear rate can be reduced, which is also a current research hotspot of polyoxymethylene composite materials.

[0003] In the modification research of polyoxymethylene wear-resistant composite materials, the most typical one that has also been realized in industrial production is the polyurethane elastomer (TPU) toughened POM system. In many TPU toughened POM studies, the toughness of POM will be greatly improved, and the friction coefficient and wear rate will show a trend of first decreasing and then increasing with the increase of TPU content, but in general, the reduction in the friction coefficient and wear rate is small, which limits the application of POM wear-resistant composite materials in many fields.

[0004] Since the discovery of graphene, research on graphene-reinforced composite materials has never stopped. As a two-dimensional carbon nanomaterial, the carbon atoms in graphene are sp 2 Hybridization forms a unique two-dimensional hexagonal honeycomb lattice structure. This single atomic layer structure makes graphene the thinnest and strongest material in the world. In addition, graphene also has excellent physical and chemical properties, such as mechanical properties, thermal properties, electrical properties and optical properties. However, due to its insolubility in the matrix, van der Waals forces and π-π stacking between graphene sheets, this interaction makes graphene easy to irreversibly aggregate and precipitate in various matrices, greatly limiting the application of graphene as a composite reinforcement.

[0005] In addition, the current research on the introduction of graphene as a filler into composite materials is mostly focused on utilizing its high mechanical properties, while the research on the contribution of graphene to the wear resistance of composite materials is relatively rare and mainly concentrated in the fields of alloys and rubber materials. At the same time, in such research literature, it is generally believed that in the absence of other carbon-based fillers, a large amount of graphene (usually greater than 5wt%) needs to be added to improve the wear resistance of the composite material.

[0006] After searching, the Chinese invention patent "A composite material for a motor shaft and its preparation method" (CN106496907B) provides a composite material for a motor shaft and its preparation method, and its raw materials are composed of the following components by weight: 54.5-67.8 parts of polytetrafluoroethylene, 20-25 parts of polyoxymethylene, 9-15 parts of modified nano-alumina, 3-5 parts of graphene and 0.2-0.5 parts of photoinitiator. It can be seen from the embodiment content of the patent document that the embodiment with added graphene is compared with the embodiment without added graphene, and it is found that the embodiment with added graphene has not been significantly improved in friction coefficient, while the friction loss is greatly limited by the change in the amount of other fillers added. Summary of the invention

[0007] In order to achieve the purpose of graphene-reinforced polyoxymethylene composite material with high wear resistance, the present invention provides a high wear-resistant POM / TPU / graphene composite material and a preparation method thereof, by using solid phase shear milling technology (S 3 M) While achieving uniform dispersion of graphene, when graphene is added in a specific amount, through the co-grinding preparation process with POM, the friction coefficient and specific wear rate of the final prepared sample showed an abnormally significant improvement, which laid a foundation for subsequent research on the wear resistance of graphene-enhanced composite polymer materials.

[0008] To achieve the above objectives, the present invention is implemented by adopting a technical solution consisting of the following technical measures.

[0009] In one aspect, the present invention provides a method for preparing a highly wear-resistant POM / TPU / graphene composite material, which mainly comprises the following steps by weight:

[0010] (1) preparing a POM / graphene raw material by melt blending 89-91 parts of polyoxymethylene (POM) and 0.28-0.32 parts of graphene;

[0011] (2) adding the POM / graphene raw material obtained in step (1) and 9 to 11 parts of thermoplastic polyurethane elastomer (TPU) into a disc-type solid phase force chemical reactor for co-grinding and pulverization, and collecting the composite powder after the grinding is completed; wherein the process parameters of the disc-type solid phase force chemical reactor are: grinding pressure of 2 to 3 MPa, the temperature of the grinding disc surface is controlled at 5 to 10° C. by passing a circulating cooling liquid, the grinding cycle is 18 to 22 times, and the grinding disc speed is 80 to 120 rpm;

[0012] (3) The composite powder obtained in step (2) is melt-extruded and pelletized through a twin-screw extruder to obtain a highly wear-resistant POM / TPU / graphene composite material.

[0013] On the other hand, based on the high wear-resistant POM / TPU / graphene composite material prepared by the present invention, a high wear-resistant POM / TPU / graphene composite product can be prepared by conventional thermoplastic processing.

[0014] The main inventive point of the present invention is that, when studying the graphene-enhanced POM / TPU system, in order to solve the defect that graphene cannot be fully dispersed in the POM matrix in the conventional blending technology, the inventors adopted the solid phase shear milling technology (S 3 M) to achieve uniform dispersion of graphene, and through variable comparison experiments to study the effect of graphene addition on the mechanical properties of composite materials. In this process, it was discovered that when graphene was added in a specific amount, the friction coefficient and specific wear rate of the prepared sample showed an abnormally significant improvement, with the friction coefficient reduced from 0.32 (comparison sample without graphene addition) to 0.15, and the specific wear rate from 6.28×10 -6 mm 3 / Nm (comparative sample without graphene added) decreased to 8.5×10 -7 mm 3 / Nm, a decrease of about 86%. When the amount of graphene added is further increased or decreased, this excellent wear resistance effect cannot be achieved. It should be noted that this is a high wear resistance achieved by adding a specific amount of graphene as a single carbon filler, and it directly proves that graphene has a significant contribution to wear resistance when fully dispersed, which provides a foundation for subsequent research on the wear resistance of graphene-enhanced composite polymer materials.

[0015] Herein, the polyoxymethylene (POM) in step (1) is selected from conventional polyoxymethylene industrial raw materials, such as conventional homopolymer polyoxymethylene or copolymer polyoxymethylene; those skilled in the art can select appropriate polyoxymethylene raw materials according to actual product needs or process requirements.

[0016] In one of the technical solutions, the polyoxymethylene (POM) selected in step (1) includes any one of M90 of Yunnan Yuntianhua Group Co., Ltd., 100P of DuPont China Group Co., Ltd., 5010 of Asahi Kasei Corporation of Japan, and M90-44 of Baotailing Engineering Plastics Co., Ltd.

[0017] In one technical solution, in order to make the graphene dispersed more uniformly, the density of the graphene in step (1) is less than 0.1 g / cm 3 Specific surface area 180~280m 2 / g, average particle size <10μm.

[0018] In one of the technical solutions, in order to make the graphene more evenly dispersed, the graphene in step (1) is graphene that has been decarboxylated, and the decarboxylation treatment is to remove the carboxyl groups on the graphene using a silane coupling agent. Furthermore, the decarboxylation treatment is specifically as follows: silane coupling agent, water, and ethanol are mixed in a mass ratio of 1:10:90 to prepare a decarboxylation treatment solution, the graphene is immersed in the decarboxylation treatment solution for at least 24 hours with stirring, and then filtered, washed, and dried to obtain the decarboxylation treated graphene;

[0019] The graphene is immersed in the decarboxylation treatment solution at a liquid-to-solid ratio of 100 mL: (5-10) g.

[0020] In this article, the POM / graphene primary material is prepared by melt blending in step (1). A conventional melt blending process technology known in the art can be selected, which is intended to make POM and graphene form a mixture in which graphene is preliminarily dispersed, such as using a screw extruder or an internal mixer for melt blending.

[0021] In one technical solution, in step (1), 89 to 91 parts of polyoxymethylene (POM) and 0.28 to 0.32 parts of graphene are melt-blended to prepare a POM / graphene primary material, specifically, polyoxymethylene and graphene are melt-blended and extruded through a twin-screw extruder to prepare a POM / graphene primary material;

[0022] The process parameters of the twin-screw extruder are: melting temperature 160-180°C, rotation speed 30-50 rpm.

[0023] Herein, the thermoplastic polyurethane elastomer (TPU) in step (2) is a conventional commercially available industrial raw material. Those skilled in the art can select a suitable polyurethane raw material according to actual product needs or process requirements.

[0024] In one of the technical solutions, the thermoplastic polyurethane elastomer (TPU) in step (1) is selected from any one of WHT-1570 of Yantai Wanhua Chemical Group Co., Ltd., 2792A of Covestro, Germany, 58284 of Lubrizol Specialty Chemicals Co., Ltd., and 1185A of BASF, Germany.

[0025] Herein, the grinding disc type solid phase mechanochemical reactor in step (2) is the mechanochemical reactor disclosed in the prior authorized patent ZL 95111258.9 of the applicant of the present invention.

[0026] In this article, the actual operation of the cyclic grinding process described in step (2) is to grind the material through a disc-type mechanochemical reactor, collect the product at the discharge end, and then place it in a disc-type mechanochemical reactor for grinding again. The above process is regarded as one cyclic grinding.

[0027] Herein, the temperature of the grinding disc surface in step (2) is controlled by introducing circulating cooling liquid, and the cooling liquid is water, ethylene glycol or glycerol.

[0028] In one of the technical solutions, since the particle size of the composite powder obtained after grinding and pulverization in a disc-type solid phase chemical reactor is relatively small, it is easy to regain moisture during storage and transportation. Therefore, before the composite powder is melt-extruded and pelletized by a twin-screw extruder in step (3), it is advisable to dry the composite powder at a temperature of 80 to 100°C for 18 to 24 hours.

[0029] In this article, the composite powder obtained in step (2) is melt-extruded and pelletized by a twin-screw extruder as described in step (3). The process parameters in the melt-extrusion process of the twin-screw extruder can be directly based on the conventional process parameters of polyoxymethylene (POM) in a twin-screw extruder.

[0030] In order to better illustrate the present invention and provide a technical solution for reference, the composite powder obtained in step (2) is melt-extruded and pelletized through a twin-screw extruder in step (3), wherein the process parameters of the twin-screw extruder are: melting temperature 160-180°C, rotation speed 30-50 rpm.

[0031] In this article, the highly wear-resistant POM / TPU / graphene composite product is prepared by conventional thermoplastic processing. The selection of the thermoplastic processing method can directly refer to the process method and process parameters of polyoxymethylene (POM) during thermoplastic processing and molding. For example, a highly wear-resistant POM / TPU / graphene composite product is prepared by hot pressing molding on a flat vulcanizer.

[0032] In one application method, the high wear-resistant POM / TPU / graphene composite material obtained in step (3) is hot-pressed by a flat-plate vulcanizer to prepare a high wear-resistant POM / TPU / graphene composite sheet, wherein the process parameters of the flat-plate vulcanizer are: temperature of 160-180°C, pressure of 5-10MPa, and hot pressing time of 10-20 minutes.

[0033] In this article, the mixing and drying are carried out in accordance with the conventional principles of chemical processes, and those skilled in the art can perform specific operations according to common knowledge.

[0034] The present invention has the following beneficial effects:

[0035] 1. The present invention provides a highly wear-resistant POM / TPU / graphene composite material and a preparation method thereof, by using solid phase shear milling technology (S 3 M) achieves uniform dispersion of graphene, solving the defect that graphene cannot be fully dispersed in the POM matrix in conventional blending technology.

[0036] 2. The present invention provides a highly wear-resistant POM / TPU / graphene composite material and a preparation method thereof. It is accidentally discovered that when a specific amount of graphene is added, the friction coefficient and specific wear rate of the sample finally prepared by the co-grinding preparation process with POM show an abnormally significant improvement. The friction coefficient is reduced from 0.32 (comparison sample without graphene addition) to 0.15, and the specific wear rate is reduced from 6.28×10 -6 mm 3 / Nm (comparative sample without graphene added) decreased to 8.5×10 -7 mm 3 / Nm, a decrease of about 86%. It has achieved high wear resistance when graphene is used as a single carbon filler, and directly proved that graphene has a significant contribution to wear resistance when fully dispersed, which lays a foundation for subsequent research on the wear resistance of graphene-enhanced composite polymer materials.

[0037] 3. The present invention provides a highly wear-resistant POM / TPU / graphene composite material and a preparation method thereof. The composite material can be used to prepare a highly wear-resistant POM / TPU / graphene composite product by conventional thermoplastic processing. The product has excellent mechanical properties and high wear resistance, which fully proves that the highly wear-resistant POM / TPU / graphene composite material provided by the present invention can be directly used as a raw material for preparing wear-reducing and wear-resistant products. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The transmission electron microscope images of the samples prepared in Example 1 and Comparative Example 8 of the present invention are shown. The left image is a transmission electron microscope image of the highly wear-resistant POM / TPU / graphene composite sample prepared in Example 1, and the graphene uniformly dispersed therein is marked with a red circle; the right image is a transmission electron microscope image of the POM / TPU / graphene composite comparison sample prepared by the traditional melting method in Comparative Example 8, and it is found that the graphene has a serious agglomeration phenomenon, and the dispersed graphene cannot be observed.

[0039] Figure 2 This is an atomic force microscope image of graphene in the highly wear-resistant POM / TPU / graphene composite sample prepared in Example 1 of the present invention. It can be found that the thickness of the graphene is about 2.0 nm, proving that the graphene is in a uniformly dispersed state.

[0040] Figure 3 This is an atomic force microscope image of graphene in the POM / TPU / graphene composite comparative sample prepared by the traditional melting method in Comparative Example 8 of the present invention. It is found that the graphene thickness is about 40.0nm, indicating that it has been agglomerated.

[0041] Figure 4The tensile strength comparison line graph of the samples prepared in Example 1 and Comparative Examples 1 to 10. 3 M) The samples prepared in Example 1 and Comparative Examples 2 to 5 correspond to the horizontal axis according to the addition ratio of graphene (0.1 part corresponds to 0.1%); the black line (Without S 3 M) corresponds to the samples prepared in Examples 6 to 10; the intersection of the red line and the black line on the far left of the horizontal axis corresponds to the sample prepared in Example 1.

[0042] Figure 5 The elongation at break of the samples prepared in Example 1 and Comparative Examples 1 to 10 is compared in a linear graph. 3 M) The samples prepared in Example 1 and Comparative Examples 2 to 5 correspond to the horizontal axis according to the addition ratio of graphene (0.1 part corresponds to 0.1%); the black line (Without S 3 M) corresponds to the samples prepared in Examples 6 to 10; the intersection of the red line and the black line on the far left of the horizontal axis corresponds to the sample prepared in Example 1.

[0043] Figure 6 The impact strength comparison line graph of the samples prepared in Example 1 and Comparative Examples 1 to 10. 3 M) The samples prepared in Example 1 and Comparative Examples 2 to 5 correspond to the horizontal axis according to the addition ratio of graphene (0.1 part corresponds to 0.1%); the black line (Without S 3 M) corresponds to the samples prepared in Examples 6 to 10; the intersection of the red line and the black line on the far left of the horizontal axis corresponds to the sample prepared in Example 1.

[0044] Figure 7 The friction coefficient comparison diagram of the samples prepared in Example 1 and Comparative Examples 1 to 5 is shown. Among them, 0% Ge corresponds to the sample prepared in Comparative Example 1; 0.1% Ge corresponds to the sample prepared in Comparative Example 2; 0.2% Ge corresponds to the sample prepared in Comparative Example 3; 0.3% Ge corresponds to the sample prepared in Example 1; 0.4% Ge corresponds to the sample prepared in Comparative Example 4; and 0.5% Ge corresponds to the sample prepared in Comparative Example 5.

[0045] Figure 8 The comparative line graph and physical comparison photos of the specific wear rate of the samples prepared in Example 1 and Comparative Examples 1 to 5 are shown. In the comparative line graph, the addition ratio of graphene (0.1 part corresponds to 0.1%) corresponds to the horizontal axis, and 0.0% corresponds to the specific wear rate of the sample prepared in Comparative Example 1; in the physical photo, the samples are arranged from left to right in the order of the addition amount of graphene from small to large, and the physical sample on the far left is the sample prepared in Comparative Example 1. DETAILED DESCRIPTION

[0046] In order to further understand the present invention, the preferred embodiments of the present invention are described below in conjunction with examples, but 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 refer to the content of this article and appropriately improve the process parameters to achieve it. It is particularly important to point out 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 relevant personnel can obviously change or appropriately change and combine 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 fully understand the following terms, the following definitions are still stated to help illustrate the subject matter disclosed by the present invention.

[0047] In one aspect, the present invention provides a method for preparing a highly wear-resistant POM / TPU / graphene composite material, which mainly comprises the following steps by weight:

[0048] (1) preparing a POM / graphene raw material by melt blending 89-91 parts of polyoxymethylene (POM) and 0.28-0.32 parts of graphene;

[0049] (2) adding the POM / graphene raw material obtained in step (1) and 9 to 11 parts of thermoplastic polyurethane elastomer (TPU) into a disc-type solid phase force chemical reactor for co-grinding and pulverization, and collecting the composite powder after the grinding is completed; wherein the process parameters of the disc-type solid phase force chemical reactor are: grinding pressure of 2 to 3 MPa, the temperature of the grinding disc surface is controlled at 5 to 10° C. by passing a circulating cooling liquid, the grinding cycle is 18 to 22 times, and the grinding disc speed is 80 to 120 rpm;

[0050] (3) The composite powder obtained in step (2) is melt-extruded and pelletized through a twin-screw extruder to obtain a highly wear-resistant POM / TPU / graphene composite material.

[0051] On the other hand, based on the high wear-resistant POM / TPU / graphene composite material prepared by the present invention, a high wear-resistant POM / TPU / graphene composite product can be prepared by conventional thermoplastic processing.

[0052] The main inventive point of the present invention is that, when studying the graphene-enhanced POM / TPU system, in order to solve the defect that graphene cannot be fully dispersed in the POM matrix in the conventional blending technology, the inventors adopted the solid phase shear milling technology (S 3M) to achieve uniform dispersion of graphene, and through variable comparison experiments to study the effect of graphene addition on the mechanical properties of composite materials. In this process, it was discovered that when graphene was added in a specific amount, the friction coefficient and specific wear rate of the prepared sample showed an abnormally significant improvement, with the friction coefficient reduced from 0.32 (comparison sample without graphene addition) to 0.15, and the specific wear rate from 6.28×10 -6 mm 3 / Nm (comparative sample without graphene added) decreased to 8.5×10 -7 mm 3 / Nm, a decrease of about 86%. When the amount of graphene added is further increased or decreased, this excellent wear resistance effect cannot be achieved. It should be noted that this is a high wear resistance achieved by adding a specific amount of graphene as a single carbon filler, and it directly proves that graphene has a significant contribution to wear resistance when fully dispersed, which provides a foundation for subsequent research on the wear resistance of graphene-enhanced composite polymer materials.

[0053] Herein, the polyoxymethylene (POM) in step (1) is selected from conventional polyoxymethylene industrial raw materials, such as conventional homopolymer polyoxymethylene or copolymer polyoxymethylene; those skilled in the art can select appropriate polyoxymethylene raw materials according to actual product needs or process requirements.

[0054] In one embodiment, the polyoxymethylene (POM) in step (1) is selected from any one of M90 of Yunnan Yuntianhua Group Co., Ltd., 100P of DuPont China Group Co., Ltd., 5010 of Asahi Kasei Corporation, and M90-44 of Baotailing Engineering Plastics Co., Ltd.

[0055] In one embodiment, in order to make the graphene dispersed more uniformly, the density of the graphene in step (1) is less than 0.1 g / cm 3 Specific surface area 180~280m 2 / g, average particle size <10μm.

[0056] In one embodiment, in order to make the graphene more uniformly dispersed, the graphene in step (1) is graphene that has been decarboxylated, and the decarboxylation treatment is to remove the carboxyl groups on the graphene using a silane coupling agent. Furthermore, the decarboxylation treatment is specifically as follows: silane coupling agent, water, and ethanol are mixed in a mass ratio of 1:10:90 to prepare a decarboxylation treatment solution, the graphene is immersed in the decarboxylation treatment solution for at least 24 hours with stirring, and then filtered, washed, and dried to obtain the decarboxylation treated graphene;

[0057] The graphene is immersed in the decarboxylation treatment solution at a liquid-to-solid ratio of 100 mL: (5-10) g.

[0058] Herein, the POM / graphene raw material is prepared by melt blending in step (1). A conventional melt blending process technology known in the art can be selected, which is intended to make POM and graphene form a mixture in which graphene is preliminarily dispersed. In one embodiment, for example, a screw extruder or an internal mixer is used for melt blending.

[0059] In one embodiment, in step (1), 89 to 91 parts of polyoxymethylene (POM) and 0.28 to 0.32 parts of graphene are melt-blended to prepare a POM / graphene primary material, specifically, polyoxymethylene and graphene are melt-blended and extruded through a twin-screw extruder to prepare a POM / graphene primary material;

[0060] The process parameters of the twin-screw extruder are: melting temperature 160-180°C, rotation speed 30-50 rpm.

[0061] Herein, the thermoplastic polyurethane elastomer (TPU) in step (2) is a conventional commercially available industrial raw material. Those skilled in the art can select a suitable polyurethane raw material according to actual product needs or process requirements.

[0062] In one embodiment, the thermoplastic polyurethane elastomer (TPU) in step (1) is selected from any one of WHT-1570 of Yantai Wanhua Chemical Group Co., Ltd., 2792A of Covestro, Germany, 58284 of Lubrizol Specialty Chemicals Co., Ltd., and 1185A of BASF, Germany.

[0063] Herein, the grinding disc type solid phase mechanochemical reactor in step (2) is the mechanochemical reactor disclosed in the prior authorized patent ZL 95111258.9 of the applicant of the present invention.

[0064] In this article, the actual operation of the cyclic grinding process described in step (2) is to grind the material through a disc-type mechanochemical reactor, collect the product at the discharge end, and then place it in a disc-type mechanochemical reactor for grinding again. The above process is regarded as one cyclic grinding.

[0065] Herein, the temperature of the grinding disc surface in step (2) is controlled by introducing circulating cooling liquid. In one embodiment, the cooling liquid is water, ethylene glycol or glycerol.

[0066] In one embodiment, since the particle size of the composite powder obtained after grinding and pulverization in a disc-type solid phase chemical reactor is relatively small, it is easy to regain moisture during storage and transportation. Therefore, before the composite powder is melt-extruded and pelletized by a twin-screw extruder in step (3), it is advisable to dry the composite powder at a temperature of 80 to 100°C for 18 to 24 hours.

[0067] In this article, the composite powder obtained in step (2) is melt-extruded and pelletized by a twin-screw extruder as described in step (3). The process parameters in the melt-extrusion process of the twin-screw extruder can be directly based on the conventional process parameters of polyoxymethylene (POM) in a twin-screw extruder.

[0068] In order to better illustrate the present invention and provide an implementation method for reference, the composite powder obtained in step (2) is melt-extruded and pelletized through a twin-screw extruder in step (3), wherein the process parameters of the twin-screw extruder are: melting temperature 160-180°C, rotation speed 30-50 rpm.

[0069] In this article, the highly wear-resistant POM / TPU / graphene composite product is prepared by conventional thermoplastic processing. The selection of the thermoplastic processing method can directly refer to the process method and process parameters of polyoxymethylene (POM) during thermoplastic processing. In one embodiment, for example, a highly wear-resistant POM / TPU / graphene composite product is prepared by hot pressing molding on a flat vulcanizer.

[0070] In one embodiment, the high wear-resistant POM / TPU / graphene composite material obtained in step (3) is hot-pressed using a flat-plate vulcanizer to prepare a high wear-resistant POM / TPU / graphene composite sheet, wherein the process parameters of the flat-plate vulcanizer are: temperature of 160-180°C, pressure of 5-10 MPa, and hot pressing time of 10-20 minutes.

[0071] In this article, the mixing and drying are carried out in accordance with the conventional principles of chemical processes, and those skilled in the art can perform specific operations according to common knowledge.

[0072] The present invention will be further explained in detail with reference to the following examples. However, it should be understood by those skilled in the art that these examples are provided for illustrative purposes only and are not intended to limit the present invention.

[0073] Example

[0074] The embodiments of the present application will be described in detail below in conjunction with the examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. The specific conditions not specified in the examples are carried out according to the conditions recommended by normal conditions or manufacturers. The reagents used or the instruments not specified by the manufacturer are all conventional products that can be obtained commercially. The application should not be construed as being limited to the specific examples described.

[0075] 1. Raw materials

[0076] Copolymer polyoxymethylene (POM) is provided by Yuntianhua Group Co., Ltd., brand M90, density 1.42g / cm3 .

[0077] Thermoplastic polyurethane elastomer (TPU) was provided by Wanhua Chemical Group Co., Ltd. Its hardness is 73A and its density is 1.19g / cm 3 .

[0078] Graphene is provided by Changzhou Sixth Element Material Technology Co., Ltd., with the brand name SE1430, a particle size of 7.12um, and a carbon content of 79.8%.

[0079] The antioxidant was provided by Shanghai Titan Technology Co., Ltd. under the brand name XH-245 with a purity of 98%.

[0080] The silane coupling agent is provided by Jiangxi Chenguang New Materials Co., Ltd., the brand name is KH-570, and the density is 1.04g / cm 3 , flash point 108℃.

[0081] 2. Preparation method

[0082] (1) by weight, 90 parts of copolymerized polyoxymethylene (POM) and 0.3 parts of decarboxylated graphene are melt-blended and extruded through a twin-screw extruder to prepare a POM / graphene primary material;

[0083] The process parameters of the twin-screw extruder are: melt temperature 170°C, speed 50 rpm;

[0084] The decarboxylation treatment of the graphene is specifically as follows: a silane coupling agent, water, and ethanol are mixed in a mass ratio of 1:10:90 to prepare a decarboxylation treatment solution, the graphene is immersed in the decarboxylation treatment solution for 24 hours with stirring, and then filtered, washed, and dried to obtain the decarboxylation treated graphene;

[0085] The graphene is immersed in the decarboxylation treatment solution at a liquid-to-solid ratio of 100 mL: 5 g;

[0086] (2) adding the POM / graphene raw material obtained in step (1) and 10 parts of thermoplastic polyurethane elastomer (TPU) into a disc-type solid phase force chemical reactor for co-grinding and pulverization, and collecting the composite powder after the grinding is completed; wherein the process parameters of the disc-type solid phase force chemical reactor are: grinding pressure of 2-3 MPa, the temperature of the grinding disc surface is controlled at 5-10° C. by passing a circulating cooling liquid, the grinding cycle is repeated 20 times, and the grinding disc speed is 100 rpm;

[0087] (3) melt-extruding and pelletizing the composite powder obtained in step (2) through a twin-screw extruder to obtain a highly wear-resistant POM / TPU / graphene composite material;

[0088] The process parameters of the twin-screw extruder are: melting temperature 170°C, rotation speed 50 rpm.

[0089] For the convenience of testing, the high wear-resistant POM / TPU / graphene composite material obtained in step (3) was prepared by hot pressing on a flat-plate vulcanizer to obtain a high wear-resistant POM / TPU / graphene composite sample, wherein the process parameters of the flat-plate vulcanizer were: temperature of 170°C, pressure of 10 MPa, and hot pressing time of 15 minutes.

[0090] 3. Test methods

[0091] According to GB / T 528-2009, the tensile strength of the sample was tested at a stretching rate of 5 mm / min.

[0092] According to GB / T 10401-2018, the elongation at break of the sample was tested at a tensile rate of 5 mm / min.

[0093] According to GB 3960-2016, the tribological properties of the samples were tested with a load of 200N, a rotation speed of 200r / min, and a wear time of 2h.

[0094] According to GB / T 229-2007, the impact properties of the samples were tested. The mode was simply supported beam 2J, and all samples were pre-ground with a notch of about 2 mm deep.

[0095] Example 1

[0096] Example 1 refers to the above-mentioned "2. Preparation method" steps to finally prepare a highly wear-resistant POM / TPU / graphene composite sample.

[0097] The friction performance test of the highly wear-resistant POM / TPU / graphene composite sample obtained in this embodiment shows that, compared with the sample prepared in Comparative Example 1, its friction coefficient is reduced from 0.32 to 0.15, and its specific wear rate is reduced from 6.28×10 -6 mm 3 / Nm is reduced to 8.5×10 -7 mm 3 / Nm, a decrease of about 86%.

[0098] Comparative Example 1

[0099] Comparative Example 1 is a POM / TPU composite comparison sample prepared by a traditional melting method, specifically, by weight, 90 parts of copolymer polyoxymethylene (POM) and 10 parts of thermoplastic polyurethane elastomer (TPU) are mixed evenly, and then melt-extruded and pelletized by a twin-screw extruder to obtain a POM / TPU composite material;

[0100] The process parameters of the twin-screw extruder are: melt temperature 170°C, speed 50 rpm;

[0101] The obtained POM / TPU composite material is then hot-pressed by a flat-plate vulcanizer to prepare a POM / TPU composite comparison sample, wherein the process parameters of the flat-plate vulcanizer are: temperature of 170° C., pressure of 10 MPa, and hot-pressing time of 15 minutes.

[0102] The friction coefficient of the POM / TPU composite sample obtained in this comparative example is 0.32, and the specific wear rate is 6.28×10 - 6 mm 3 / Nm.

[0103] Comparative Example 2

[0104] Comparative Example 2 refers to the above-mentioned "2. Preparation method" steps, but the amount of decarboxylated graphene added is 0.1 parts, and finally a wear-resistant POM / TPU / graphene composite sample is prepared.

[0105] The friction performance test of the wear-resistant POM / TPU / graphene composite sample obtained in this comparative example shows that compared with the sample prepared in comparative example 1, its friction coefficient is reduced from 0.32 to 0.25, and the specific wear rate is reduced from 6.28×10 -6 mm 3 / Nm is reduced to 3.12×10 -6 mm 3 / Nm, reduced by about 50%.

[0106] Comparative Example 3

[0107] Comparative Example 3 refers to the above-mentioned "2. Preparation method" steps, but the amount of decarboxylated graphene added is 0.2 parts, and finally a wear-resistant POM / TPU / graphene composite sample is prepared.

[0108] The friction performance test of the wear-resistant POM / TPU / graphene composite sample obtained in this comparative example shows that compared with the sample prepared in comparative example 1, its friction coefficient is reduced from 0.32 to 0.21, and the specific wear rate is reduced from 6.28×10 -6 mm 3 / Nm is reduced to 2.23×10 -6 mm 3 / Nm, a decrease of about 64%.

[0109] Comparative Example 4

[0110] Comparative Example 4 refers to the above-mentioned "2. Preparation method" steps, but the amount of decarboxylated graphene added is 0.4 parts, and finally a wear-resistant POM / TPU / graphene composite sample is prepared.

[0111] The friction performance test of the wear-resistant POM / TPU / graphene composite sample obtained in this comparative example shows that compared with the sample prepared in comparative example 1, its friction coefficient is reduced from 0.32 to 0.26, and the specific wear rate is reduced from 6.28×10 -6 mm 3 / Nm is reduced to 3.67×10 -6 mm 3 / Nm, a decrease of about 41%.

[0112] Comparative Example 5

[0113] Comparative Example 5 refers to the above-mentioned "2. Preparation method" steps, but the amount of decarboxylated graphene added is 0.5 parts, and finally a wear-resistant POM / TPU / graphene composite sample is prepared.

[0114] The friction performance test of the wear-resistant POM / TPU / graphene composite sample obtained in this comparative example shows that compared with the sample prepared in comparative example 1, its friction coefficient is reduced from 0.32 to 0.3, and the specific wear rate is reduced from 6.28×10 -6 mm 3 / Nm is reduced to 4.23×10 -6 mm 3 / Nm, a decrease of about 32%.

[0115] Comparative Example 6

[0116] Comparative Example 6 is a POM / TPU / graphene composite comparative sample prepared by a traditional melting method, specifically, by weight, 90 parts of copolymerized polyoxymethylene (POM), 0.1 parts of decarboxylated graphene and 10 parts of thermoplastic polyurethane elastomer (TPU) are mixed evenly, and then melt-extruded and pelletized by a twin-screw extruder to obtain a POM / TPU / graphene composite material;

[0117] The process parameters of the twin-screw extruder are: melt temperature 170°C, speed 50 rpm;

[0118] The decarboxylation treatment of the graphene is specifically as follows: a silane coupling agent, water, and ethanol are mixed in a mass ratio of 1:10:90 to prepare a decarboxylation treatment solution, the graphene is immersed in the decarboxylation treatment solution for 24 hours with stirring, and then filtered, washed, and dried to obtain the decarboxylation treated graphene;

[0119] The graphene is immersed in the decarboxylation treatment solution at a liquid-to-solid ratio of 100 mL: 5 g;

[0120] The obtained POM / TPU / graphene composite material is then hot-pressed using a flat-plate vulcanizer to prepare a POM / TPU / graphene composite comparison sample, wherein the process parameters of the flat-plate vulcanizer are: temperature of 170°C, pressure of 10 MPa, and hot-pressing time of 15 minutes.

[0121] Comparative Example 7

[0122] Comparative Example 7 is a POM / TPU / graphene composite comparison sample prepared by a traditional melting method, specifically, by weight, 90 parts of copolymerized polyoxymethylene (POM), 0.2 parts of decarboxylated graphene and 10 parts of thermoplastic polyurethane elastomer (TPU) are mixed evenly and then melt-extruded and pelletized by a twin-screw extruder to obtain a POM / TPU / graphene composite material;

[0123] The process parameters of the twin-screw extruder are: melt temperature 170°C, speed 50 rpm;

[0124] The decarboxylation treatment of the graphene is specifically as follows: a silane coupling agent, water, and ethanol are mixed in a mass ratio of 1:10:90 to prepare a decarboxylation treatment solution, the graphene is immersed in the decarboxylation treatment solution for 24 hours with stirring, and then filtered, washed, and dried to obtain the decarboxylation treated graphene;

[0125] The graphene is immersed in the decarboxylation treatment solution at a liquid-to-solid ratio of 100 mL: 5 g;

[0126] The obtained POM / TPU / graphene composite material is then hot-pressed using a flat-plate vulcanizer to prepare a POM / TPU / graphene composite comparison sample, wherein the process parameters of the flat-plate vulcanizer are: temperature of 170°C, pressure of 10 MPa, and hot-pressing time of 15 minutes.

[0127] Comparative Example 8

[0128] Comparative Example 8 is a POM / TPU / graphene composite comparative sample prepared by a traditional melting method, specifically, by weight, 90 parts of copolymerized polyoxymethylene (POM), 0.3 parts of decarboxylated graphene and 10 parts of thermoplastic polyurethane elastomer (TPU) are mixed evenly, and then melt-extruded and pelletized by a twin-screw extruder to obtain a POM / TPU / graphene composite material;

[0129] The process parameters of the twin-screw extruder are: melt temperature 170°C, speed 50 rpm;

[0130] The decarboxylation treatment of the graphene is specifically as follows: a silane coupling agent, water, and ethanol are mixed in a mass ratio of 1:10:90 to prepare a decarboxylation treatment solution, the graphene is immersed in the decarboxylation treatment solution for 24 hours with stirring, and then filtered, washed, and dried to obtain the decarboxylation treated graphene;

[0131] The graphene is immersed in the decarboxylation treatment solution at a liquid-to-solid ratio of 100 mL: 5 g;

[0132] The obtained POM / TPU / graphene composite material is then hot-pressed using a flat-plate vulcanizer to prepare a POM / TPU / graphene composite comparison sample, wherein the process parameters of the flat-plate vulcanizer are: temperature of 170°C, pressure of 10 MPa, and hot-pressing time of 15 minutes.

[0133] Comparative Example 9

[0134] Comparative Example 9 is a POM / TPU / graphene composite comparative sample prepared by a traditional melting method, specifically, by weight, 90 parts of copolymerized polyoxymethylene (POM), 0.4 parts of decarboxylated graphene and 10 parts of thermoplastic polyurethane elastomer (TPU) are mixed evenly, and then melt-extruded and pelletized by a twin-screw extruder to obtain a POM / TPU / graphene composite material;

[0135] The process parameters of the twin-screw extruder are: melt temperature 170°C, speed 50 rpm;

[0136] The decarboxylation treatment of the graphene is specifically as follows: a silane coupling agent, water, and ethanol are mixed in a mass ratio of 1:10:90 to prepare a decarboxylation treatment solution, the graphene is immersed in the decarboxylation treatment solution for 24 hours with stirring, and then filtered, washed, and dried to obtain the decarboxylation treated graphene;

[0137] The graphene is immersed in the decarboxylation treatment solution at a liquid-to-solid ratio of 100 mL: 5 g;

[0138] The obtained POM / TPU / graphene composite material is then hot-pressed using a flat-plate vulcanizer to prepare a POM / TPU / graphene composite comparison sample, wherein the process parameters of the flat-plate vulcanizer are: temperature of 170°C, pressure of 10 MPa, and hot-pressing time of 15 minutes.

[0139] Comparative Example 10

[0140] Comparative Example 10 is a POM / TPU / graphene composite comparative sample prepared by a traditional melting method, specifically, by weight, 90 parts of copolymerized polyoxymethylene (POM), 0.5 parts of decarboxylated graphene and 10 parts of thermoplastic polyurethane elastomer (TPU) are mixed evenly, and then melt-extruded and pelletized by a twin-screw extruder to obtain a POM / TPU / graphene composite material;

[0141] The process parameters of the twin-screw extruder are: melt temperature 170°C, speed 50 rpm;

[0142] The decarboxylation treatment of the graphene is specifically as follows: a silane coupling agent, water, and ethanol are mixed in a mass ratio of 1:10:90 to prepare a decarboxylation treatment solution, the graphene is immersed in the decarboxylation treatment solution for 24 hours with stirring, and then filtered, washed, and dried to obtain the decarboxylation treated graphene;

[0143] The graphene is immersed in the decarboxylation treatment solution at a liquid-to-solid ratio of 100 mL: 5 g;

[0144] The obtained POM / TPU / graphene composite material is then hot-pressed using a flat-plate vulcanizer to prepare a POM / TPU / graphene composite comparison sample, wherein the process parameters of the flat-plate vulcanizer are: temperature of 170°C, pressure of 10 MPa, and hot-pressing time of 15 minutes.

[0145] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention shall be equivalent replacement methods and shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a highly wear-resistant POM / TPU / graphene composite material, characterized in that Mainly comprising the following steps by weight: (1) preparing a POM / graphene raw material by melt blending 89-91 parts of polyoxymethylene and 0.28-0.32 parts of graphene; (2) adding the POM / graphene raw material obtained in step (1) and 9 to 11 parts of thermoplastic polyurethane elastomer into a disc-type solid phase force chemical reactor for co-grinding and pulverization, and collecting the composite powder after the grinding is completed; wherein the process parameters of the disc-type solid phase force chemical reactor are: grinding pressure of 2 to 3 MPa, the temperature of the grinding disc surface is controlled at 5 to 10° C. by passing a circulating cooling liquid, the grinding cycle is repeated 18 to 22 times, and the grinding disc speed is 80 to 120 rpm; (3) The composite powder obtained in step (2) is melt-extruded and pelletized through a twin-screw extruder to obtain a highly wear-resistant POM / TPU / graphene composite material.

2. The preparation method according to claim 1, characterized in that: The polyoxymethylene described in step (1) includes any one of M90 of Yuntianhua Group Co., Ltd., 100P of DuPont China Group Co., Ltd., 5010 of Asahi Kasei Corporation, and M90-44 of Baotailing Engineering Plastics Co., Ltd.

3. The preparation method according to claim 1, characterized in that: The density of the graphene in step (1) is less than 0.1 g / cm 3 Specific surface area 180~280m 2 / g, average particle size <10μm.

4. The preparation method according to claim 1, characterized in that: In step (1), 89 to 91 parts of polyoxymethylene and 0.28 to 0.32 parts of graphene are melt-blended to prepare a POM / graphene primary material, specifically, polyoxymethylene and graphene are melt-blended and extruded through a twin-screw extruder to prepare a POM / graphene primary material; The process parameters of the twin-screw extruder are: melting temperature 160-180°C, rotation speed 30-50 rpm.

5. The preparation method according to claim 1, characterized in that: The thermoplastic polyurethane elastomer described in step (1) includes any one of WHT-1570 of Yantai Wanhua Chemical Group Co., Ltd., 2792A of Covestro, Germany, 58284 of Lubrizol Specialty Chemicals Co., Ltd., and 1185A of BASF, Germany.

6. The preparation method according to claim 1, characterized in that: The graphene in step (1) is graphene that has been subjected to a decarboxylation treatment, and the decarboxylation treatment is to remove the carboxyl groups on the graphene using a silane coupling agent.

7. The preparation method according to claim 1, characterized in that: In step (3), the composite powder obtained in step (2) is melt-extruded and pelletized through a twin-screw extruder, wherein the process parameters of the twin-screw extruder are: melting temperature 160-180° C., and rotation speed 30-50 rpm.

8. The highly wear-resistant POM / TPU / graphene composite material prepared by the method for preparing the highly wear-resistant POM / TPU / graphene composite material as claimed in claim 1.

9. The highly wear-resistant POM / TPU / graphene composite material as claimed in claim 8 is used as a raw material for the preparation of wear-reducing and wear-resistant products.

10. A highly wear-resistant POM / TPU / graphene composite sheet, characterized in that The high wear-resistant POM / TPU / graphene composite material described in claim 8 is used as a raw material, and a high wear-resistant POM / TPU / graphene composite plate is prepared by hot pressing molding using a flat vulcanizer, wherein the process parameters of the flat vulcanizer are: temperature of 160-180°C, pressure of 5-10MPa, and hot pressing time of 10-20 minutes.

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