Polymer composite material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of high-molecular material processing methods, and discloses a high-molecular composite material as well as a preparation method and application thereof. The method comprises the following steps: freezing and crushing a thermoplastic elastomer, and sieving by using a screen to obtain thermoplastic elastomer powder; carrying out ball milling on the thermoplastic elastomer powder and graphite to obtain a master batch; carrying out melt blending on a high polymer material and the master batch to obtain a premix; and extruding the premix, stretching and shearing, and calendering and extruding. According to the preparation method of the polymer composite material, the mechanical strength and the impact resistance of the thermoplastic material are synchronously improved by optimizing the preparation method of the reinforcing and toughening agent and combining with composite force field processing assistance.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer material processing methods, and in particular to a polymer composite material and a preparation method and application thereof. Background Art

[0002] Thermoplastics are widely used in automotive, home appliances, packaging, medical devices, textiles, and other fields due to their excellent chemical stability, heat resistance, moldability, low density, and good electrical insulation. Thermoplastics such as polypropylene, polystyrene, and rigid polyvinyl chloride offer advantages such as low processing temperatures, short processing cycles, good recyclability, and environmental friendliness. However, thermoplastics inherently suffer from low impact toughness and poor low-temperature performance, limiting their use in some demanding applications.

[0003] In order to improve the mechanical properties of thermoplastics such as polypropylene, polystyrene and rigid polyvinyl chloride, researchers have proposed a variety of reinforcement and toughening methods, which can be roughly divided into two categories: one is to improve the strength of thermoplastics by reinforcing fillers, and the other is to improve the impact strength and toughness of thermoplastics by toughening modification.

[0004] Research on thermoplastic reinforcements primarily focuses on improving their strength through the use of inorganic fillers (such as glass fiber, mineral fillers, and nanofillers). Glass fiber, currently the most widely used reinforcing filler, can significantly increase the tensile strength and rigidity of thermoplastics. However, this reinforcement is often accompanied by increased brittleness and a decrease in impact toughness. Therefore, while glass fiber-reinforced thermoplastics can significantly increase their strength, their poor toughness limits their widespread use in applications requiring toughness and impact resistance, such as automotive and home appliances.

[0005] Toughening thermoplastics such as polypropylene, polystyrene, and rigid polyvinyl chloride typically involves adding toughening agents to improve their impact strength. Common toughening agents include rubber-based materials (e.g., EPDM, SBS), polyolefin elastomers (e.g., POE, PPE), and others. The addition of toughening agents can effectively improve the impact strength and low-temperature toughness of thermoplastics. However, these methods often sacrifice the tensile strength and rigidity of the thermoplastic. Therefore, single toughening or reinforcement measures often fail to achieve an ideal balance between strength and toughness. Summary of the Invention

[0006] The present invention aims to overcome the difficulty in balancing toughness, tensile strength, and rigidity in existing toughening and modification methods for thermoplastic materials. The present invention provides a polymer composite material, its preparation method, and its application. This polymer composite material preparation method optimizes the preparation method of the toughening agent and combines it with composite force field processing to simultaneously enhance the mechanical strength and impact resistance of the thermoplastic material.

[0007] In order to achieve the above object, the present invention provides a first aspect of a method for preparing a polymer composite material, the method comprising the following steps: (1) Freezing and crushing the thermoplastic elastomer, and then sieving it through a sieve to obtain thermoplastic elastomer powder; (2) ball milling the thermoplastic elastomer powder and graphite to obtain a masterbatch; (3) melt-blending the polymer material and the masterbatch to obtain a premix; (4) The premix is ​​extruded, stretched, sheared, and then calendered.

[0008] Preferably, in step (1), the thermoplastic elastomer is selected from at least one of POE, POE-g-MAH and SEBS-g-MAH.

[0009] Preferably, the melt index of the thermoplastic elastomer is 1 to 20 g / 10 min, more preferably 1 to 10 g / 10 min.

[0010] Preferably, in step (1), the freeze-drying conditions include: a temperature of -80°C to -20°C, more preferably -50°C to -30°C; and a time of 5 to 20 minutes, more preferably 5 to 10 minutes.

[0011] Preferably, the mesh size of the sieve is 20-70 meshes, more preferably 40-60 meshes.

[0012] Preferably, in step (2), the average particle size of the graphite is 1-50 μm, more preferably 1-30 μm.

[0013] Preferably, the mass ratio of the graphite to the thermoplastic elastomer powder is 1:(5-50), more preferably 1:(10-30).

[0014] Preferably, the ball milling conditions include: a rotation speed of 100-1000 rpm, more preferably 300-700 rpm; and a time of 5-15 h, more preferably 9-13 h.

[0015] Preferably, in step (3), the polymer material is selected from polypropylene and / or polystyrene.

[0016] Preferably, in step (3), the melt index of the polymer material is 1 to 20 g / 10 min, more preferably 1 to 10 g / 10 min.

[0017] Preferably, the weight ratio of the masterbatch to the polymer material is 1:(1-30), more preferably 1:(1-10).

[0018] Preferably, in step (3), the melt blending process is carried out in a twin-screw extruder.

[0019] Preferably, the operating conditions of the twin-screw extruder include: the temperature of the feeding section is 150~180℃, the temperature of the conveying section is 180~220℃, the temperature of the melting section is 180~220℃, the temperature of the homogenizing section is 180~220℃, and the extrusion speed is 50~300rpm.

[0020] Preferably, in step (4), the stretching and shearing process is carried out in a continuous force field module, wherein the continuous force field module includes at least six composite force field modules, and the premix can be sequentially split, stretched / sheared and merged in each composite force field module.

[0021] Preferably, the operating temperature of the continuous force field module is 170-230°C.

[0022] Preferably, in step (4), the calendering extrusion conditions include: a rotation speed of 50-300 rpm and a temperature of 20-50°C.

[0023] The second aspect of the present invention provides a polymer composite material prepared by the method described above.

[0024] A third aspect of the present invention provides a use of the aforementioned polymer composite material in the preparation of automotive components and / or household appliance housings.

[0025] The toughening and reinforcing agent obtained by optimizing the preparation method of the polymer composite material of the present invention can be diluted into different proportions according to use requirements and filled into general plastics, which can significantly improve the mechanical strength and impact resistance of general plastics.

[0026] The polymer composite preparation method of the present invention also utilizes a composite force field module to achieve uniform dispersion of components within a general-purpose plastic filling system, fully utilizing the functional components. Furthermore, the integrated uniform dispersion equipment enables continuous, solvent-free, and large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the masterbatch preparation process.

[0028] Figure 2 Schematic diagram of an exemplary uniformly dispersed integrated device.

[0029] Figure 3 These are the Raman spectra images of the graphite in Test Example 1 and the graphite after ball milling for 13 hours.

[0030] Figure 4 This is the SEM image of the masterbatch prepared in step (2) of Example 1.

[0031] Reference numerals 1. Twin-screw extruder; 2. Connector; 3. Continuous force field module; 31. Composite force field module; 4. Calender. DETAILED DESCRIPTION

[0032] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0033] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0034] The method for preparing the polymer composite material of the present invention comprises the following steps: (1) Freezing and crushing the thermoplastic elastomer, and then sieving it through a sieve to obtain thermoplastic elastomer powder; (2) ball milling the thermoplastic elastomer powder and graphite to obtain a masterbatch; (3) melt-blending the polymer material and the masterbatch to obtain a premix; (4) The premix is ​​extruded, stretched, sheared, and then calendered.

[0035] In the present invention, in step (1), the thermoplastic elastomer may be at least one of POE, POE-g-MAH, and SEBS-g-MAH. In the present invention, when the thermoplastic elastomer is selected from the above, the toughness and strength of the polymer composite material can be further improved.

[0036] In the present invention, the melt index of the thermoplastic elastomer can be 1 to 20 g / 10 min, preferably 1 to 10 g / 10 min. In the present invention, when the melt index of the thermoplastic elastomer is within the above range (especially within the preferred range), the toughness and strength of the polymer composite material can be further improved.

[0037] In the method of the present invention, in step (1), the freeze-drying conditions may include: a temperature of -80°C to -20°C, preferably -50°C to -30°C; and a time of 5 to 20 minutes, preferably 5 to 10 minutes. In the method of the present invention, when the freeze-drying conditions are within the above range (especially within the preferred range), the particles of the thermoplastic elastomer are smaller, which is conducive to the subsequent ball milling process.

[0038] In the method of the present invention, the mesh size of the sieve can be 20-70 meshes, preferably 40-60 meshes.

[0039] In the present invention, in step (2), the average particle size of the graphite may be 1-50 μm, preferably 1-30 μm. In the present invention, when the average particle size of the graphite is within the above range (especially within the preferred range), the graphite can be exfoliated into graphene during ball milling and coated in the thermoplastic elastomer.

[0040] In the method of the present invention, the mass ratio of the graphite to the thermoplastic elastomer powder can be 1:(1-30), preferably 1:(1-10). In the method of the present invention, when the mass ratio of the graphite to the thermoplastic elastomer powder is within the above range (especially within the preferred range), the graphene formed by the graphite can be more uniformly coated in the thermoplastic elastomer.

[0041] In the method of the present invention, the ball milling conditions may include: a rotation speed of 100 to 1000 rpm, preferably 300 to 700 rpm, and a time of 5 to 15 hours, preferably 9 to 13 hours. In the method of the present invention, when the ball milling conditions are within the above ranges (especially within the preferred ranges), the graphite can be exfoliated into graphene during the ball milling process and uniformly encapsulated in the thermoplastic elastomer.

[0042] like Figure 1 As shown, during the masterbatch preparation process, the present invention utilizes ball milling to exfoliate graphite into graphene, which is then effectively encapsulated within the thermoplastic elastomer, avoiding the graphene agglomeration that would result from direct melt blending of the graphene and thermoplastic elastomer. During melt blending and stretching / shearing of the polymer material and masterbatch, the graphene and thermoplastic elastomer are uniformly dispersed within the polymer matrix, further enhancing the strength and toughness of the polymer composite material.

[0043] In the present invention, in step (3), the polymer material may be polypropylene and / or polystyrene.

[0044] In the present invention, in step (3), the melt index of the polymer material may be 1 to 20 g / 10 min, preferably 1 to 10 g / 10 min.

[0045] In a preferred embodiment, when the polymer material is polypropylene, the melt index of the polypropylene is 5 to 10 g / 10 min. In these preferred embodiments, when the melt index of the polypropylene is within the above range, the toughness and strength of the polypropylene composite material can be further improved.

[0046] In a preferred embodiment, when the polymer material is polystyrene, the melt index of the polystyrene is 5 to 10 g / 10 min. In these preferred embodiments, when the melt index of the polystyrene is within the above range, the toughness and strength of the polystyrene composite material can be further improved.

[0047] In the method of the present invention, the weight ratio of the masterbatch to the polymer material can be 1:(4-50), preferably 1:(10-30). In the present invention, when the weight ratio of the masterbatch to the polymer material is within the above range (especially within the preferred range), the prepared polymer composite material has even better mechanical properties.

[0048] In some embodiments, in step (3), the melt blending process can be performed in a twin-screw extruder 1 .

[0049] In a preferred embodiment, the operating conditions of the twin-screw extruder 1 include: a temperature of 150-180°C in the feeding section, a temperature of 180-220°C in the conveying section, a temperature of 180-220°C in the melting section, a temperature of 180-220°C in the homogenizing section, and an extrusion speed of 50-300 rpm. In these preferred embodiments, when the operating conditions of the twin-screw extruder 1 are within the above ranges, the melt blending of the masterbatch and the polymer material is more uniform and efficient.

[0050] In some embodiments, in step (4), the stretching and shearing processes are performed in a continuous force field module 3, wherein the continuous force field module 3 includes at least six composite force field modules 31, and the premix can be sequentially split, stretched / sheared, and merged in each composite force field module 31. When the premix is ​​processed according to this embodiment, the continuous force field module 3 can simultaneously stretch and shear the premix, efficiently mix the components in the premix, and thereby improve the toughness and strength of the polymer composite material.

[0051] In a more preferred embodiment, the operating temperature of the continuous force field module 3 can be 170-230°C.

[0052] In the method described in the present invention, in step (4), the calendering extrusion conditions may include: a rotation speed of 50-300 rpm and a temperature of 20-50°C.

[0053] In some embodiments, the method for preparing the polymer composite material of the present invention can be implemented in a uniformly dispersed integrated device, such as Figure 2 As shown, the device includes a twin-screw extruder 1, a connector 2, a continuous force field module 3 and a calender 4 connected in sequence, wherein the twin-screw extruder 1 is used to melt-blend the polymer material and the masterbatch to obtain a premix and extrude the premix; The connector 2 is configured to connect the discharge port of the twin-screw extruder 1 and the feed port of the continuous force field module 3, and to feed the extruded premix into the continuous force field module 3; The continuous force field module 3 includes at least six compound force field modules 31, each compound force field module 31 contains n branch channels, and the extruded premix from the connector 2 is divided into n streams of premix fluid by the n branch channels of the first-stage compound force field module 31. Each of the branch channels is configured to generate a two-dimensional force field to stretch and shear the premix fluid. The n streams of premix fluid merge at the ends of the n branch channels and enter the next-stage compound force field module 31. The calender 4 is used to calender and extrude the material from the continuous force field module 3 .

[0054] In this exemplary embodiment, in the composite force field module 31, the n diversion channels can be configured as cavities with the same structure whose thickness gradually decreases and whose width gradually increases, and the positions of the n diversion channels gradually change from horizontal arrangement to vertical arrangement, wherein the thickness of each diversion channel at the outlet is 1 / n of the thickness at the inlet, and the width at the outlet is n times the width at the inlet.

[0055] In this exemplary embodiment, in the composite force field module 31, the value of n can be adjusted according to the volume change rate of the premixture fluid to achieve efficient dispersion of the premixture fluid, and is preferably an integer greater than or equal to 2. For example, if n is 4, then in each composite force field module 31, the thickness of the premixture fluid becomes 1 / 4 of the original thickness, the width becomes 4 times the original width, and the volume change rate is 16 times.

[0056] In this exemplary embodiment, the volume change rate of the premix fluid in the uniformly dispersed integrated device is greatly increased, which can generate a huge tensile and shear composite force field, promote the two-dimensional orientation of the thermoplastic elastomer and graphene along the flow direction, achieve efficient dispersion of the premix fluid, effectively exert the high toughness performance of the thermoplastic elastomer and the high strength performance of the graphene, and achieve a certain synergistic effect, thereby improving the tensile strength and impact strength of the prepared polymer composite material.

[0057] The polymer composite material described in the present invention has excellent tensile strength and notched impact strength. Its tensile strength can reach 55.7 MPa and its notched impact strength can reach 48.3 MPa. It can be used in the fields of automobiles, home appliances, packaging, medical devices, textiles, etc., especially in the preparation of automotive components and home appliance casings, while meeting their requirements for toughness and strength of polymer materials.

[0058] The following examples further illustrate the polymer composite material, its preparation method and application of the present invention. The examples are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operating processes, but the scope of protection of the present invention is not limited to the following examples.

[0059] Unless otherwise specified, the experimental methods in the following examples are conventional methods in the art.

[0060] Unless otherwise specified, the experimental materials used in the following examples are commercially available.

[0061] The following examples and comparative examples are Figure 2 The method is implemented in the uniformly dispersed integrated device shown, which includes a twin-screw extruder 1, a connector 2, a continuous force field module 3 and a calender 4 connected in sequence, wherein the twin-screw extruder 1 is used to melt-blend the polymer material and the masterbatch to obtain a premix and extrude the premix; The connector 2 is configured to connect the discharge port of the twin-screw extruder 1 and the feed port of the continuous force field module 3, and to feed the extruded premix into the continuous force field module 3; The continuous force field module 3 includes at least six compound force field modules 31, each of which contains two branch channels. The extruded premix from the connector 2 is divided into two premix fluids by the two branch channels of the first-stage compound force field module 31. Each of the branch channels is configured to generate a two-dimensional force field to stretch and shear the premix fluid. The two premix fluids merge at the ends of the two branch channels and enter the next-stage compound force field module 31. The calender 4 is used to calender and extrude the material from the continuous force field module 3 .

[0062] In the composite force field module 31, the two diversion channels can be configured as cavities with the same structure whose thickness gradually decreases and whose width gradually increases, and the positions of the two diversion channels gradually change from horizontal arrangement to vertical arrangement, wherein the thickness at the outlet of each diversion channel is 1 / 2 of the thickness at the inlet, and the width at the outlet is twice the width at the inlet.

[0063] In the following examples and comparative examples, polypropylene was purchased from Ningxia Coal Industry Co., Ltd. of the State Energy Group, with a melt flow index of 2.8 g / 10 min; general-purpose polystyrene was purchased from Zhenjiang Chimei Chemical Co., Ltd., with a melt flow index of 4.2 g / 10 min; polyolefin elastomer (POE) was purchased from The Dow Chemical Company, USA, with a melt flow index of 14 g / 10 min; polyolefin elastomer grafted with maleic anhydride (POE-g-MAH) was purchased from The Dow Chemical Company, USA, with a melt flow index of 1.25 g / 10 min; styrene-ethylene-butylene-styrene block copolymer grafted with maleic anhydride (SEBS-g-MAH) was purchased from Kraton Polymers, USA, with a melt flow index of 14 g / 10 min; graphite was purchased from Qingdao Xingyuan Graphite Co., Ltd., with an average particle size of 10-15 μm and a density of 2.2 g / cm 3 Graphene was purchased from Changzhou Sixth Element Material Technology Co., Ltd. with the brand name SE1430.

[0064] Example 1 (1) The thermoplastic elastomer POE was frozen and crushed at -40°C, and then filtered through a 50-mesh sieve to obtain POE powder; (2) placing the POE powder and graphite in a ball mill at a weight ratio of 19:3, and subjecting them to mechanical ball milling and blending to obtain a masterbatch, wherein the conditions for the mechanical ball milling and blending are: a rotation speed of 500 rpm and a time of 13 h; (3) feeding the masterbatch and polypropylene into the uniform dispersion integrated device at a weight ratio of 1:4, and melt-blending them in the twin-screw extruder 1 to obtain a premix, wherein the operating conditions of the twin-screw extruder 1 include: the temperatures of the feeding section, the conveying section, the melting section, and the homogenizing section are 160°C, 190°C, 190°C, and 190°C, respectively, and the extrusion speed is 150 rpm; (4) The premix is ​​extruded through the connector 2 and sent into the continuous force field module 3. The premix is ​​split into two streams in the composite force field module 31. The two streams are stretched and sheared respectively, and the thickness gradually becomes 1 / 2 of the original, and the width gradually becomes 2 times of the original. Then the two streams merge and restore the original thickness and width. The merged fluid enters the next level composite force field module 31 and repeats the above process. After passing through six composite force field modules 31, the merged fluid obtained in the last level composite force field module 31 is stretched and enters the calender 4 for calendering extrusion; wherein, the operating temperature of the connector 2 is 190°C; the operating conditions of the continuous force field module 3 include: temperature of 190°C, extrusion speed of 100 rpm; the operating conditions of the calender 4 include: rotation speed of 100 rpm, temperature of 20°C. The prepared polymer composite material is recorded as A1.

[0065] Example 2 This example was carried out according to the method described in Example 1, except that in step (1), the thermoplastic elastomer was replaced with POE-g-MAH. The prepared polymer composite material is designated as A2.

[0066] Example 3 This example was carried out according to the method described in Example 1, except that in step (1), the thermoplastic elastomer was replaced with SEBS-g-MAH. The prepared polymer composite material was designated A3.

[0067] Example 4 (1) The thermoplastic elastomer POE was frozen and crushed at -80°C, and then filtered through a 20-mesh sieve to obtain POE powder; (2) placing the POE powder and graphite in a ball mill at a weight ratio of 30:1, and subjecting them to mechanical ball milling and blending to obtain a masterbatch, wherein the conditions for the mechanical ball milling and blending are: a rotation speed of 300 rpm and a time of 15 h; (3) The masterbatch and general-purpose polystyrene are fed into the uniform dispersion integrated device at a weight ratio of 1:10, and melt-blended in the twin-screw extruder 1 to obtain a premix, wherein the operating conditions of the twin-screw extruder 1 include: the temperatures of the feeding section, the conveying section, the melting section, and the homogenizing section are 150°C, 180°C, 180°C, and 180°C, respectively, and the extrusion speed is 50 rpm; (4) The premix is ​​extruded through the connector 2 and sent into the continuous force field module 3. The premix is ​​split into two streams in the composite force field module 31. The two streams are stretched and sheared respectively, and the thickness gradually becomes 1 / 2 of the original, and the width gradually becomes 2 times the original. Then the two streams merge and restore the original thickness and width. The merged fluid enters the next composite force field module 31 and repeats the above process. After passing through six composite force field modules 31, the merged fluid obtained in the last composite force field module 31 is stretched and enters the calender 4 for calendering extrusion; wherein, the operating temperature of the connector 2 is 170°C; the operating conditions of the continuous force field module 3 include: temperature of 170°C, extrusion speed of 100 rpm; the operating conditions of the calender 4 include: rotation speed of 50 rpm, temperature of 50°C. The prepared polymer composite material is recorded as A4.

[0068] Example 5 This example was carried out according to the method described in Example 1, except that in step (2), the ball milling conditions included a rotation speed of 1200 rpm and a time of 2 h. The prepared polymer composite material was designated A6.

[0069] Comparative Example 1 Thermoplastic elastomer (POE), graphite, and polypropylene were melt-mixed in a twin-screw extruder at a ratio of 5:1:40. The operating conditions for the twin-screw extruder included temperatures of 160°C, 190°C, 190°C, and 190°C in the feeding, conveying, melting, and homogenizing sections, respectively, and an extrusion speed of 150 rpm. The resulting polymer composite material is designated D-A1.

[0070] Comparative Example 2 This comparative example was carried out according to the method described in Comparative Example 1, except that the thermoplastic elastomer POE was replaced with POE-g-MAH. The prepared polymer composite material was designated D-A2.

[0071] Comparative Example 3 This comparative example was carried out in accordance with the method described in Comparative Example 1, except that the thermoplastic elastomer POE was replaced with SEBS-g-MAH. The prepared polymer composite material was designated D-A3.

[0072] Comparative Example 4 This comparative example was carried out according to the method described in Example 1, except that step (4) was not performed. The prepared polymer composite material was recorded as D-A4.

[0073] Comparative Example 5 This comparative example was carried out according to the method described in Example 2, except that step (4) was not performed. The prepared polymer composite material was recorded as D-A5.

[0074] Comparative Example 6 This comparative example was carried out according to the method described in Example 3, except that step (4) was not performed. The prepared polymer composite material was designated as D-A6.

[0075] Comparative Example 7 This comparative example was carried out according to the method described in Example 1, except that in step (2), the POE powder and graphene were uniformly mixed in a weight ratio of 19:3 to obtain a masterbatch. The prepared polymer composite material was designated D-A7.

[0076] Test Example 1 In this test example, Raman spectroscopy was used to characterize graphite and graphite after ball milling for 1.3 hours. The obtained Raman spectral images are as follows: Figure 2 shown.

[0077] Depend on Figure 2 It can be seen that after 13 h of ball milling, a D peak (1350 cm -1 ), 2D peak related to the number of GT layers (2700 cm -1 ), the G peak (1580 cm) related to the first-order scattering of the E2g model, which reflects the degree of graphitization of carbon materials -1 ), D' peak associated with few-layer G defects (1625 cm -1 ) four characteristic peaks. After 13h of ball milling, the peak at 1600cm -1 A D' peak appears near the G band, and the D' peak is a characteristic peak of graphene. Therefore, during the ball milling process, graphite is exfoliated into graphene.

[0078] Test Example 2 In this test example, SEM was used to characterize the morphology and structure of the masterbatch prepared in step (2) of Example 1. The obtained SEM image is as follows: Figure 4 shown.

[0079] Depend on Figure 4 It can be seen that a small amount of multi-layered flake graphene is stacked on the surface of the thermoplastic elastomer. During the ball milling process, the graphene obtained by exfoliation of graphite is coated in the thermoplastic elastomer.

[0080] Test Example 3 This test example tests the tensile strength and notched impact strength of the polymer composite materials A1 to A7 of the present invention prepared in Examples 1 to 7, and the polymer composite materials D-A1 to D-A7 prepared in Comparative Examples 1 to 7. The specific experimental steps are as follows: Composite materials A1~A7 and D-A1~D-A7 were hot pressed in a plate vulcanizer at 180℃ and 10MPa for 8min to obtain the corresponding 250×250×1mm 3 Sheet and 80×10×4mm 3 Impact test strips were then cut and notched to produce strips that met the test standards. Tensile strength tests were conducted on a tensile testing machine according to GB / T1040-92, and notched impact strength tests were conducted on a pendulum impact testing machine according to GB / 1943-2008. Five strips were tested in each group, and the average value was calculated.

[0081] The results are shown in Table 1.

[0082] Table 1

[0083] As shown in Table 1, by adopting the technical solution of the present invention, the polymer composite materials A1 to A5 prepared in Examples 1-5 all have good mechanical properties. Among them, the tensile strength of A1 can reach 55.7 MPa, and the notched impact strength of A2 can reach 48.3 kJ / m 2 ; Example 5 is not preferred because its ball milling speed is too high and the time is too short, the graphite cannot be effectively converted into graphene, and thus cannot be evenly coated in the thermoplastic elastomer powder. Compared with A1~A4, the tensile strength of A5 is poor. In Comparative Examples 1-3, due to the direct use of graphite as filler and the lack of multi-stage stretching and shearing, its mechanical properties are far inferior to those of A1-A5. In Comparative Examples 4-6, due to the lack of multi-stage stretching and shearing, only a twin-screw extruder is used to perform limited stretching and shearing on the polymer melt. Its tensile strength is inferior to that of A1-A4, and the loss of notched impact strength is more obvious, far inferior to that of A1-A5. In Comparative Example 7, graphene is directly used to prepare the polymer composite material. Due to the agglomeration of graphene during the melt mixing and extrusion process, it cannot be effectively dispersed in the polymer melt to exert its high strength performance and synergistic effect with the thermoplastic elastomer. The mechanical properties of D-A7 are far inferior to those of A1~A5.

[0084] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for preparing a polymer composite material, characterized in that: The method comprises the following steps: (1) Freezing and crushing the thermoplastic elastomer, and then sieving it through a sieve to obtain thermoplastic elastomer powder; (2) ball milling the thermoplastic elastomer powder and graphite to obtain a masterbatch; (3) melt-blending the polymer material and the masterbatch to obtain a premix; (4) The premix is ​​extruded, stretched, sheared, and then calendered.

2. The method according to claim 1, characterized in that In step (1), the thermoplastic elastomer is selected from at least one of POE, POE-g-MAH and SEBS-g-MAH; and / or, The melt index of the thermoplastic elastomer is 1-20 g / 10 min, preferably 1-10 g / 10 min.

3. The method according to claim 1 or 2, characterized in that In step (1), the freeze-crushing conditions include: a temperature of -80°C to -20°C, preferably -50°C to -30°C; a time of 5 to 20 minutes, preferably 5 to 10 minutes; and / or, The mesh number of the sieve is 20-70 meshes, preferably 40-60 meshes.

4. The method according to any one of claims 1 to 3, characterized in that In step (2), the average particle size of the graphite is 1-50 μm, preferably 1-30 μm; and / or, The mass ratio of the graphite to the thermoplastic elastomer powder is 1:(5-50), preferably 1:(10-30); and / or, The ball milling conditions include: a rotation speed of 100-1000 rpm, preferably 300-700 rpm; and a time of 5-15 h, preferably 9-13 h.

5. The method according to any one of claims 1 to 4, characterized in that In step (3), the polymer material is selected from polypropylene and / or polystyrene; and / or, The melt index of the polymer material is 1 to 20 g / 10 min, preferably 1 to 10 g / 10 min; and / or, The weight ratio of the masterbatch to the polymer material is 1:(1-30), preferably 1:(1-10).

6. The method according to claim 1 or 5, characterized in that In step (3), the melt blending process is carried out in a twin-screw extruder (1); Preferably, the operating conditions of the twin-screw extruder (1) include: a feeding section temperature of 150-180°C, a conveying section temperature of 180-220°C, a melting section temperature of 180-220°C, a homogenizing section temperature of 180-220°C, and an extrusion speed of 50-300 rpm.

7. The method according to any one of claims 1 to 4, characterized in that In step (4), the stretching and shearing process is performed in a continuous force field module (3), wherein the continuous force field module (3) includes at least six composite force field modules (31), and the premix can be sequentially split, stretched / sheared, and merged in each composite force field module (31); Preferably, the operating temperature of the continuous force field module (3) is 170-230°C.

8. The method according to any one of claims 1 to 4, characterized in that In step (4), the calendering extrusion conditions include: a rotation speed of 50-300 rpm and a temperature of 20-50°C.

9. A polymer composite material prepared by the method according to any one of claims 1 to 8.

10. Use of the polymer composite material according to claim 9 in the preparation of automobile components and / or household appliance housings.

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