A highly wear-resistant POM / TPU / graphene composite material and preparation method thereof

Abstract

The present invention provides a high wear-resistant POM / TPU / graphene composite material and a preparation method thereof. The preparation method comprises the following steps: melt-blending 89 to 91 parts of polyoxymethylene and 0.28 to 0.32 parts of graphene by weight to prepare a POM / graphene primary material; then adding the POM / graphene primary material and 9 to 11 parts of thermoplastic polyurethane elastomer into a grinding disc type solid phase force chemical reactor for co-grinding and pulverizing; collecting a composite powder; and melt-extruding and pelletizing the composite powder through a twin-screw extruder to obtain a high wear-resistant POM / TPU / graphene composite material. The present invention utilizes solid phase shear milling technology (S 3 M) While achieving uniform dispersion of graphene, when graphene is added in a specific amount, the friction coefficient and specific wear rate of the final sample prepared through the co-grinding preparation process with polyoxymethylene show unusually significant improvements, laying the foundation for subsequent research on the wear resistance of graphene-enhanced composite polymer materials.

Description

Technical Field

[0001] The present 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 and anti-friction materials are one of the key research areas. Polymer materials with low friction coefficients and low wear rates are rapidly developing in the field of wear-resistant materials due to their low cost and good processing properties. Among the many polymer materials, polyoxymethylene (POM) has earned the reputation of "steel-like" and "super steel" due to its excellent mechanical properties. At the same time, its self-lubrication, chemical corrosion resistance, and low cost make it a key candidate 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. However, in general, the reduction in the friction coefficient and wear rate is relatively 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 connected by sp 2 Hybridization forms a unique two-dimensional hexagonal honeycomb lattice structure. This single-atom layer structure makes graphene the thinnest and strongest material in the world. Graphene also possesses excellent physical and chemical properties, such as mechanical, thermal, electrical, and optical properties. However, due to its insolubility in the matrix, van der Waals forces, and the π-π stacking between graphene sheets, this interaction makes graphene prone to irreversible aggregation and precipitation in various matrices, greatly limiting its application as a reinforcement in composite materials.

[0005] Furthermore, while current research on graphene as a filler in composite materials focuses on its high mechanical properties, research on its contribution to composite material wear resistance is relatively rare and primarily focused on alloys and rubber materials. Furthermore, in this research literature, it is generally assumed that, in the absence of other carbon-based fillers, a high amount of graphene (typically greater than 5wt%) is required to improve the wear resistance of composite materials.

[0006] A search revealed a Chinese invention patent, "A Composite Material for a Motor Shaft and Its Preparation Method" (CN106496907B), which provides a composite material for a motor shaft and its preparation method. The raw materials, calculated by weight, consist of the following components: 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 a photoinitiator. The patent document's examples show that when graphene is added to the examples compared to those without, the friction coefficient of the examples with graphene added is not significantly improved, while friction loss is significantly limited by 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 utilizing solid phase shear milling technology (S 3 While achieving uniform dispersion of graphene, when a specific amount of graphene is added, the friction coefficient and specific wear rate of the sample finally prepared through the co-grinding preparation process with POM show unusually significant improvements, laying the 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 in parts 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 grinding 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 grinding disc type solid phase force chemical reactor are: grinding pressure of 2 to 3 MPa, grinding disc surface temperature controlled at 5 to 10° C. by passing circulating cooling liquid, cyclic grinding for 18 to 22 times, and grinding disc speed of 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 present invention, a highly wear-resistant POM / TPU / graphene composite material is prepared, and a highly wear-resistant POM / TPU / graphene composite product can be prepared by conventional thermoplastic processing.

[0014] The main invention of the present invention is that, when studying graphene enhanced POM / TPU system, in order to solve the defect that graphene cannot be fully dispersed in the POM matrix in conventional blending technology, the inventors used solid phase shear milling technology (S 3 M) to achieve uniform dispersion of graphene, and through variable comparison experiments, the effect of graphene addition on the mechanical properties of the composite material was studied. In this process, it was discovered that when the graphene addition was at a specific amount, the friction coefficient and specific wear rate of the prepared sample showed an unusually significant improvement. The friction coefficient was reduced from 0.32 (compared to the control sample without graphene addition) to 0.15, and the specific wear rate was reduced from 6.28×10 -6 mm 3 / Nm (comparison sample without graphene added) decreased to 8.5×10 -7 mm 3 / Nm, a decrease of about 86%. Further increasing or decreasing the amount of graphene added does not achieve this excellent wear resistance. It should be noted that this is high wear resistance achieved by adding graphene as the sole carbon filler at a specific dosage. This directly proves that graphene, when fully dispersed, makes a significant contribution to wear resistance, laying the foundation for subsequent research on the wear resistance of graphene-enhanced composite polymer materials.

[0015] Herein, the polyoxymethylene (POM) in step (1) is a conventional polyoxymethylene industrial raw material, such as conventional homopolymer polyoxymethylene or copolymer polyoxymethylene; those skilled in the art can select a suitable polyoxymethylene raw material according to actual product requirements 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 more uniformly dispersed, 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 technical solution, 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;

[0019] The graphene is immersed in the decarboxylation treatment solution at a liquid-to-material 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 with preliminary dispersion of graphene, for example, 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, the polyoxymethylene and graphene are melt-blended and extruded through a twin-screw extruder to prepare the POM / graphene primary material;

[0022] The process parameters of the twin-screw extruder are: melting temperature 160-180° C., and 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) selected 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.

[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 milling 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 milling.

[0027] Herein, the temperature of the grinding disc surface in step (2) is controlled by introducing a circulating cooling liquid, wherein 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 force chemical reactor is 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 through a twin-screw extruder as described in step (3). The process parameters during the melt extrusion process of the twin-screw extruder can be directly based on the conventional process parameters for melt extrusion 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, and 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 on 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.

[0033] In this article, the mixing and drying are carried out in accordance with conventional principles in 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 utilizing 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 was discovered that when a specific amount of graphene was added, the friction coefficient and specific wear rate of the sample obtained by co-grinding with POM showed an unusually significant improvement. The friction coefficient was reduced from 0.32 (compared to the control sample without graphene addition) to 0.15, and the specific wear rate was reduced from 6.28×10 -6 mm 3 / Nm (comparison sample without graphene added) decreased to 8.5×10 -7 mm 3 / Nm, a decrease of about 86%. This demonstrates that graphene achieves high wear resistance when used as a single carbon filler, and directly proves that graphene has a significant contribution to wear resistance when fully dispersed, laying the 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 highly wear-resistant POM / TPU / graphene composite products through conventional thermoplastic processing. The highly wear-resistant POM / TPU / graphene composite products have excellent mechanical properties and high wear resistance. This 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 to prepare wear-reducing and wear-resistant products. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Transmission electron microscopy images of samples prepared in Example 1 and Comparative Example 8. The left image is a transmission electron microscopy image of the highly wear-resistant POM / TPU / graphene composite sample prepared in Example 1, with the uniformly dispersed graphene indicated by a red circle. The right image is a transmission electron microscopy image of a POM / TPU / graphene composite comparison sample prepared using a traditional melt method in Comparative Example 8, showing severe graphene agglomeration and no visible dispersed graphene.

[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 graphene thickness is about 2.0 nm, proving that the graphene is uniformly dispersed.

[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. The graphene thickness is found to be about 40.0 nm, indicating that it has 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 are plotted against 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 and black lines on the far left of the horizontal axis corresponds to the sample prepared in Example 1.

[0042] Figure 5 This is a comparative line graph of the elongation at break 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 are plotted against 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 and black lines on the far left of the horizontal axis corresponds to the sample prepared in Example 1.

[0043] Figure 6 This is a line graph comparing the impact strength 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 are plotted against 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 and black lines on the far left of the horizontal axis corresponds to the sample prepared in Example 1.

[0044] Figure 7 This is a comparison chart of the friction coefficients of the samples prepared in Example 1 and Comparative Examples 1 to 5. 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 following are a line graph comparing the specific wear rates of the samples prepared in Example 1 and Comparative Examples 1-5, along with photographs of the samples. In the line graph, the horizontal axis corresponds to the graphene addition ratio (0.1 part corresponds to 0.1%), with 0.0% corresponding to the specific wear rate of the sample prepared in Comparative Example 1. In the photographs, the samples are arranged from left to right in increasing order of graphene addition, with the sample on the far left being the sample prepared in Comparative Example 1. DETAILED DESCRIPTION

[0046] In order to further understand the present invention, 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 for limiting the claims of the invention. Those skilled in the art can refer to the contents of this article and appropriately improve the process parameters for implementation. It is particularly important to point out that all similar replacements 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 modify 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 in parts 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 grinding 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 grinding disc type solid phase force chemical reactor are: grinding pressure of 2 to 3 MPa, grinding disc surface temperature controlled at 5 to 10° C. by passing circulating cooling liquid, cyclic grinding for 18 to 22 times, and grinding disc speed of 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 present invention, a highly wear-resistant POM / TPU / graphene composite material is prepared, and a highly wear-resistant POM / TPU / graphene composite product can be prepared by conventional thermoplastic processing.

[0052] The main invention of the present invention is that, when studying graphene enhanced POM / TPU system, in order to solve the defect that graphene cannot be fully dispersed in the POM matrix in conventional blending technology, the inventors used solid phase shear milling technology (S 3M) to achieve uniform dispersion of graphene, and through variable comparison experiments, the effect of graphene addition on the mechanical properties of the composite material was studied. In this process, it was discovered that when the graphene addition was at a specific amount, the friction coefficient and specific wear rate of the prepared sample showed an unusually significant improvement. The friction coefficient was reduced from 0.32 (compared to the control sample without graphene addition) to 0.15, and the specific wear rate was reduced from 6.28×10 -6 mm 3 / Nm (comparison sample without graphene added) decreased to 8.5×10 -7 mm 3 / Nm, a decrease of about 86%. Further increasing or decreasing the amount of graphene added does not achieve this excellent wear resistance. It should be noted that this is high wear resistance achieved by adding graphene as the sole carbon filler at a specific dosage. This directly proves that graphene, when fully dispersed, makes a significant contribution to wear resistance, laying the foundation for subsequent research on the wear resistance of graphene-enhanced composite polymer materials.

[0053] Herein, the polyoxymethylene (POM) in step (1) is a conventional polyoxymethylene industrial raw material, such as conventional homopolymer polyoxymethylene or copolymer polyoxymethylene; those skilled in the art can select a suitable polyoxymethylene raw material according to actual product requirements 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 more uniformly dispersed, 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-material ratio of 100 mL: (5-10) g.

[0058] 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 with preliminary dispersion of graphene. 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, the polyoxymethylene and graphene are melt-blended and extruded through a twin-screw extruder to prepare the POM / graphene primary material;

[0060] The process parameters of the twin-screw extruder are: melting temperature 160-180° C., and 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 milling 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 milling.

[0065] Herein, the temperature of the grinding disc surface in step (2) is controlled by introducing a 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 force chemical reactor is small and is easily moisture-recovered during storage and transportation, the composite powder should be dried at a temperature of 80 to 100° C. for 18 to 24 hours before being melt-extruded and pelletized by a twin-screw extruder in step (3).

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

[0068] In order to better illustrate the present invention and provide an embodiment 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 using a flat-plate vulcanizer.

[0070] In one embodiment, the high wear-resistant POM / TPU / graphene composite material obtained in step (3) is hot-pressed on 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 conventional principles in 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 below with reference to the examples. However, it will be appreciated 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 merely illustrative of the present application and should not be considered as limiting the scope of the present application. In the examples, if no specific conditions are indicated, the conditions are carried out according to normal conditions or manufacturer recommendations. The reagents used or the instruments that are not indicated by the manufacturer are 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, with a density of 1.42g / cm3 .

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

[0078] The graphene is provided by Changzhou Sixth Element Material Technology Co., Ltd., with the brand name SE1430, a particle size of 7.12 μm, 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 were melt-blended and extruded through a twin-screw extruder to prepare a POM / graphene raw material;

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

[0084] The decarboxylation-treated graphene is specifically prepared by mixing a silane coupling agent, water, and ethanol in a mass ratio of 1:10:90 to form a decarboxylation treatment solution, immersing the graphene in the decarboxylation treatment solution for 24 hours while stirring, and then filtering, washing, and drying 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 grinding 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 grinding disc type solid phase force chemical reactor are: grinding pressure of 2-3 MPa, grinding disc surface temperature controlled by circulating cooling liquid at 5-10°C, cyclic grinding for 20 times, and grinding disc speed of 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] To facilitate testing, the high-wear-resistant POM / TPU / graphene composite material obtained in step (3) was hot-pressed on a flat-plate vulcanizer to prepare a high-wear-resistant POM / TPU / graphene composite sample, wherein the process parameters of the flat-plate vulcanizer were as follows: 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 200 N, a rotation speed of 200 r / min, and a wear time of 2 h.

[0094] According to GB / T 229-2007, the impact properties of the samples were tested. The simply supported beam 2J mode was selected, and all samples were pre-ground with a notch 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 high wear-resistant POM / TPU / graphene composite sample obtained in this example shows that compared with the sample prepared in Comparative Example 1, its friction coefficient is reduced from 0.32 to 0.15, and the 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 comparative sample prepared by a traditional melt method. Specifically, 90 parts of copolymerized polyoxymethylene (POM) and 10 parts of thermoplastic polyurethane elastomer (TPU) are mixed uniformly by weight, 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 was then hot-pressed using a flat-plate vulcanizer to prepare a POM / TPU composite comparison sample, wherein the process parameters of the flat-plate vulcanizer were as follows: 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 melt 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 uniformly 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-treated graphene is specifically prepared by mixing a silane coupling agent, water, and ethanol in a mass ratio of 1:10:90 to form a decarboxylation treatment solution, immersing the graphene in the decarboxylation treatment solution for 24 hours while stirring, and then filtering, washing, and drying 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 was 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 were as follows: 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 comparative sample prepared by a traditional melt 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 uniformly 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-treated graphene is specifically prepared by mixing a silane coupling agent, water, and ethanol in a mass ratio of 1:10:90 to form a decarboxylation treatment solution, immersing the graphene in the decarboxylation treatment solution for 24 hours while stirring, and then filtering, washing, and drying 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 was 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 were as follows: 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 melt 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 uniformly 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-treated graphene is specifically prepared by mixing a silane coupling agent, water, and ethanol in a mass ratio of 1:10:90 to form a decarboxylation treatment solution, immersing the graphene in the decarboxylation treatment solution for 24 hours while stirring, and then filtering, washing, and drying 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 was 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 were as follows: 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 melt 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 uniformly 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-treated graphene is specifically prepared by mixing a silane coupling agent, water, and ethanol in a mass ratio of 1:10:90 to form a decarboxylation treatment solution, immersing the graphene in the decarboxylation treatment solution for 24 hours while stirring, and then filtering, washing, and drying 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 was 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 were as follows: 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 melt 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 uniformly 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-treated graphene is specifically prepared by mixing a silane coupling agent, water, and ethanol in a mass ratio of 1:10:90 to form a decarboxylation treatment solution, immersing the graphene in the decarboxylation treatment solution for 24 hours while stirring, and then filtering, washing, and drying 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 was 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 were as follows: 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 that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for preparing a highly wear-resistant POM / TPU / graphene composite material, characterized in that Mainly comprise 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 grinding 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 grinding disc type solid phase force chemical reactor are: grinding pressure of 2 to 3 MPa, grinding disc surface temperature controlled at 5 to 10° C. by introducing circulating cooling liquid, cyclic grinding for 18 to 22 times, and grinding disc speed of 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, wherein: The polyformaldehyde 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 of Japan, and M90-44 of Baotailing Engineering Plastics Co., Ltd.

3. The preparation method according to claim 1, wherein: 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, wherein: 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, the polyoxymethylene and graphene are melt-blended and extruded through a twin-screw extruder to prepare the POM / graphene primary material; The process parameters of the twin-screw extruder are: melting temperature 160-180° C., and 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 decarboxylated, 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 high wear-resistant POM / TPU / graphene composite material prepared by the method for preparing the high wear-resistant POM / TPU / graphene composite material according to 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 is prepared by hot pressing on a flat vulcanizer to obtain a high wear-resistant POM / TPU / graphene composite plate, wherein the process parameters of the flat vulcanizer are: temperature of 160-180°C, pressure of 5-10 MPa, and hot pressing time of 10-20 minutes.

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