High-elongation polypropylene composite and method for producing the same

Abstract

The application discloses a high-yield elongation polypropylene composite material, which comprises the following raw materials in parts by mass: polypropylene 45-93 parts, modified inorganic filler 5-30 parts, toughening agent 1-20 parts, compatilizer 1-5 parts, and other auxiliary agents 0.5-2 parts. The application also discloses a preparation method of the high-yield elongation polypropylene composite material. In the application, nanocellulose fibers are selected to perform surface modification on inorganic filling powder under the cooperation of coupling agents and cross-linking agents, so that the nanocellulose is cross-linked and attached to the surface of the inorganic filling powder to obtain modified inorganic filling powder. The application can greatly improve the mechanical properties of the polypropylene composite material, and significantly improve the yield elongation of the polypropylene composite material, and has important application significance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer materials, in particular to a high-yield elongation polypropylene composite material and a preparation method thereof. BACKGROUND

[0002] Compared with other general thermoplastic resins, polypropylene resin has the advantages of relatively small density, low price, good processing performance and good comprehensive performance, but also has the disadvantages of poor rigidity, large molding shrinkage and easy aging. In the practical application of polypropylene materials, in order to improve the low-temperature toughness of polypropylene, ethylene / octene copolymer (POE) or LDPE and HDPE are usually added to toughen polypropylene, and in order to make up for the loss of rigidity caused by the addition of POE, inorganic fillers are usually added to increase the rigidity and improve the dimensional stability.

[0003] Before this, the breaking elongation has always been an important mechanical property index of modified polypropylene to control, and the traditional view believes that the higher the breaking elongation of the material is, the better the toughness of the material is, but the yield elongation, which is a more critical mechanical property index of the material, is rarely concerned, and there are very few research reports on the yield elongation of modified polypropylene. Through previous research, it is found that the yield strength and tensile strength of PP increase with the increase of the crystallinity of PP. For the material, exceeding the yield point means the irreversibility of deformation, and the yield means the failure. At present, there is no intuitive and effective scheme to improve the yield elongation, and as an extremely important mechanical property index, it is urgent to make a breakthrough in systematic research. SUMMARY

[0004] Based on the technical problems existing in the background art, the present application provides a high-yield elongation polypropylene composite material and a preparation method thereof, which can improve the strength, toughness and yield elongation of the material.

[0005] The high-yield elongation polypropylene composite material provided by the present application comprises the following raw materials in parts by mass: polypropylene 45-93 parts, modified inorganic filler 5-30 parts, toughening agent 1-20 parts, compatibilizer 1-5 parts, and other additives 0.5-2 parts.

[0006] The preparation method of the modified inorganic filler comprises: fully mixing a coupling agent, nanocellulose fibers, a peroxide crosslinking agent and an inorganic filler, and obtaining the modified inorganic filler.

[0007] The nanocellulose fibers (CNF) have an aspect ratio of 1000-3000.

[0008] Preferably, the mass ratio of the coupling agent, nanocellulose fibers, peroxide crosslinking agent and inorganic filler is (1-3) :(2-10) :(0.1-0.5) :(86.5-96.9).

[0009] Preferably, the inorganic filler is at least one of talcum powder, calcium carbonate, wollastonite, magnesium sulfate whisker, mica powder; the coupling agent is at least one of aluminate coupling agent, titanate coupling agent or a combination thereof; the peroxide crosslinking agent is at least one of dicumyl peroxide (DCP), di-tert-butyl peroxide (DTBP), tert-butyl peroxybenzoate (TPB).

[0010] Preferably, in the preparation method of the modified inorganic filler, the temperature of mixing is 50-70℃, and the time is 20-40min.

[0011] Preferably, the melt flow rate of the polypropylene under the test conditions of 230℃ and 2.16kg is 5-100g / 10min.

[0012] Preferably, the toughening agent is at least one of POE, EPDM, HDPE, LDPE, SEBS.

[0013] Preferably, the compatilizer is at least one of PP-g-MAH, POE-g-MAH, SEBS-g-MAH.

[0014] Preferably, the other auxiliary agent is at least one of antioxidant, lubricant, UV-resistant agent, pigment.

[0015] Preferably, the antioxidant is antioxidant 1010, antioxidant 168 and a combination thereof.

[0016] Preferably, the lubricant is calcium stearate.

[0017] A preparation method of the high-elongation-at-yield polypropylene composite material, comprising the following steps: weighing raw materials according to mass fraction, fully blending polypropylene, modified inorganic filler, toughening agent, compatilizer and other auxiliary agent, and then adding them into an extruder, and then melting extruding, granulating, cooling, drying, and finally obtaining the product.

[0018] Preferably, the extruder is a double-screw extruder, and the temperature of melting extrusion is 190-220℃.

[0019] Preferably, the double-screw extruder comprises ten zones, wherein the first zone is a feeding zone, and the temperature of the second to tenth zones is controlled to be 190-220℃.

[0020] Preferably, the screw rotation speed of the extruder is 300-500r / min.

[0021] The beneficial effects of the present application are as follows:

[0022] The present application utilizes the firm chemical bond of coupling agent molecules and inorganic filler surface, and a certain amount of hydroxyl (-OH) exists on the surface of inorganic filler, the hydrophilic group in the coupling agent reacts with the hydroxyl to form firm chemical bond; the hydrophobic group at the other end is long chain structure, and cross-linking reaction is carried out with nanocellulose fiber under the action of cross-linking agent, so that the nanocellulose is firmly cross-linked and attached to the surface of inorganic filler, and better interface reinforcing effect is obtained, which helps to improve the mechanical properties of the material; the modified inorganic filler is added in the polypropylene composite system, on the one hand, the dispersion of nanocellulose fiber is ensured, and the compatibility of the modified inorganic filler and polypropylene resin is better; on the other hand, the disordered arrangement of nanocellulose fiber and its own toughness make the composite material gradually regularize, stretch, straighten and develop during the stretching process, not only the yield elongation of the composite material is improved, but also the mechanical properties are greatly increased; in addition, the addition of the compatibilizer can further improve the compatibility of the modified inorganic filler, nanocellulose fiber on the surface of the inorganic filler and polypropylene resin, reduce the generation of internal stress concentration points, and further improve the yield elongation. In summary, the preparation method of the present application can greatly improve the mechanical properties of the polypropylene composite material, and significantly improve the yield elongation of the polypropylene composite material, which has important application significance. DETAILED DESCRIPTION

[0023] The technical solutions of the present application will be described in detail below through specific examples.

[0024] In the following examples and comparative examples, the polypropylene brand is M60RHC, and the manufacturer is Yanshan Petrochemical; the talc brand is AHCP250, and the manufacturer is Liaoning Aihai Talc Co., Ltd.; the calcium carbonate brand is VS-625C, and the manufacturer is Dongguan Wuguan Plastic Products Co., Ltd.; the mica powder brand is AY-03N, and the manufacturer is Jiangmen Jingda Mica Material Co., Ltd.; the wollastonite brand is EP-215, and the manufacturer is Ningbo Enpai New Material Technology Co., Ltd.; the magnesium sulfate whisker brand is WS-1S, and the manufacturer is Yingkou Wesker Chemical Co., Ltd. The coupling agent, cross-linking agent, toughening agent, compatibilizer, antioxidant, lubricant, pigment and weather resistant agent are all conventional commercially available materials.

[0025] Example 1

[0026] A high yield elongation polypropylene composite material, comprising the following raw materials in parts by mass: polypropylene 68 parts, modified inorganic filler 20 parts, POE 5 parts, LDPE 5 parts, PP-g-MAH 2 parts, antioxidant 1010 0.25 parts, antioxidant 168 0.25 parts, calcium stearate 0.2 parts, black masterbatch 1 part;

[0027] The preparation method of the modified inorganic filler is as follows: aluminate coupling agent, nanocellulose fiber, peroxide crosslinking agent DCP and talc are added into a high-speed mixer at a mass ratio of 2:6:0.2:91.8, and mixed at 60°C for 30 min, and then the modified inorganic filler is obtained; wherein the nanocellulose fiber is of MFC brand, and the manufacturer is Zhejiang Hangzhou New Material Technology Co., Ltd., and the aspect ratio is 1000-3000.

[0028] Preparation of high yield elongation polypropylene composite material:

[0029] The polypropylene, the modified inorganic filler, the POE, the LDPE, the PP-g-MAH, the antioxidant 1010, the antioxidant 168, the calcium stearate and the black masterbatch are fully blended, and then added into a main feeding port of a double-screw extruder, and then subjected to melt extrusion, granulation, cooling and drying, and then the high yield elongation polypropylene composite material is obtained; wherein the screw rotating speed of the double-screw extruder is 400 r / min, and the double-screw extruder comprises ten zones, wherein the first zone is a feeding zone, and the temperatures of the second zone to the tenth zone are controlled to be 190°C, 200°C, 210°C, 210°C, 210°C, 210°C, 210°C, 200°C and 200°C, respectively.

[0030] Example 2

[0031] A high yield elongation polypropylene composite material comprises the following raw materials in parts by mass: polypropylene 93 parts, modified inorganic filler 5 parts, SEBS 1 part, SEBS-g-MAH 1 part, antioxidant 1010 0.2 part, antioxidant 168 0.2 part, calcium stearate 0.1 part.

[0032] The preparation method of the modified inorganic filler is as follows: aluminate coupling agent, nanocellulose fiber, peroxide crosslinking agent DTBP and wollastonite are added into a high-speed mixer at a mass ratio of 1:2:0.1:96.9, and mixed at 60°C for 30 min, and then the modified inorganic filler is obtained; wherein the nanocellulose fiber is of MFC brand, and the manufacturer is Zhejiang Hangzhou New Material Technology Co., Ltd., and the aspect ratio is 1000-3000.

[0033] Preparation of high yield elongation polypropylene composite material:

[0034] The polypropylene, the modified inorganic filler, the SEBS, the SEBS-g-MAH, the antioxidant 1010, the antioxidant 168 and the calcium stearate are fully blended, and then added into a main feeding port of a double-screw extruder, and then subjected to melt extrusion, granulation, cooling and drying, and then the high yield elongation polypropylene composite material is obtained; wherein the screw rotating speed of the double-screw extruder is 400 r / min, and the double-screw extruder comprises ten zones, wherein the first zone is a feeding zone, and the temperatures of the second zone to the tenth zone are controlled to be 190°C, 200°C, 210°C, 210°C, 210°C, 210°C, 220°C, 210°C and 200°C, respectively.

[0035] Example 3

[0036] A high yield elongation polypropylene composite material, comprising the following raw materials by mass fraction: polypropylene 45 parts, modified inorganic filler 30 parts, POE 10 parts, HDPE 10 parts, PP-g-MAH 5 parts, antioxidant 1010 0.25 parts, antioxidant 168 0.25 parts, UV resistant agent 0.25 parts, calcium stearate 0.25 parts, black masterbatch 1 part;

[0037] The preparation method of the modified inorganic filler is: aluminum ester coupling agent, nanocellulose fiber, peroxide crosslinking agent TPB and calcium carbonate are added into a high-speed mixer at a mass ratio of 3:10:0.5:86.5, and mixed at 60°C for 30 min, and then obtained; wherein the nanocellulose fiber is of MFC brand, the manufacturer is Zhejiang Hangzhou New Material Technology Co., Ltd., and the aspect ratio is 1000-3000.

[0038] Preparation of a high yield elongation polypropylene composite material:

[0039] After the polypropylene, modified inorganic filler, POE, HDPE, PP-g-MAH, antioxidant 1010, antioxidant 168, UV resistant agent, calcium stearate, and black masterbatch are fully blended, they are added into the main feeding port of a double-screw extruder, and then subjected to melt extrusion, granulation, cooling, and drying, and then obtained; wherein the screw rotation speed of the double-screw extruder is 450 r / min, and the double-screw extruder comprises ten zones, wherein the first zone is a feeding zone, and the temperatures of the second to tenth zones are controlled to be 190°C, 200°C, 210°C, 220°C, 220°C, 210°C, 210°C, 200°C, and 200°C, respectively.

[0040] Example 4

[0041] A high yield elongation polypropylene composite material, comprising the following raw materials by mass fraction: polypropylene 78 parts, modified inorganic filler 15 parts, EPDM 3 parts, SEBS 2 parts, PP-g-MAH 2 parts, antioxidant 1010 0.25 parts, antioxidant 168 0.25 parts, calcium stearate 0.2 parts, and black masterbatch 1 part;

[0042] The preparation method of the modified inorganic filler is: titanium ester coupling agent, nanocellulose fiber, peroxide crosslinking agent DCP, and mica powder are added into a high-speed mixer at a mass ratio of 1:8:0.3:90.7, and mixed at 60°C for 30 min, and then obtained; wherein the nanocellulose fiber is of MFC brand, the manufacturer is Zhejiang Hangzhou New Material Technology Co., Ltd., and the aspect ratio is 1000-3000.

[0043] Preparation of a high yield elongation polypropylene composite material:

[0044] The polypropylene, modified inorganic filler, EPDM, SEBS, PP-g-MAH, antioxidant 1010, antioxidant 168, calcium stearate and black masterbatch are fully blended and then added into the main feeding port of the double screw extruder, and then melt extruded, granulated, cooled and dried to obtain the product; wherein the screw rotation speed of the double screw extruder is 500 r / min, and the double screw extruder comprises ten zones, wherein the first zone is a feeding zone, and the temperatures of the second to tenth zones are controlled to be 190℃, 200℃, 210℃, 210℃, 220℃, 220℃, 210℃, 210℃, 200℃, respectively.

[0045] Example 5

[0046] A high yield elongation polypropylene composite material, comprising the following raw materials by mass fraction: polypropylene 62 parts, modified inorganic filler 25 parts, POE 8 parts, LDPE 2 parts, POE-g-MAH 3 parts, antioxidant 1010 0.25 parts, antioxidant 168 0.25 parts, calcium stearate 0.2 parts, and black masterbatch 1 part.

[0047] The preparation method of the modified inorganic filler is as follows: titanium ester coupling agent, nanocellulose fiber, peroxide crosslinking agent DCP and magnesium sulfate whisker are added into a high-speed mixer at a mass ratio of 2:4:0.4:93.6, and mixed at 60℃ for 30 min to obtain the product; wherein the nanocellulose fiber is of MFC brand, manufactured by Zhejiang Hangzhou New Material Technology Co., Ltd., and the aspect ratio is 1000-3000.

[0048] Preparation of a high yield elongation polypropylene composite material:

[0049] The polypropylene, modified inorganic filler, POE, LDPE, POE-g-MAH, antioxidant 1010, antioxidant 168, calcium stearate and black masterbatch are fully blended and then added into the main feeding port of the double screw extruder, and then melt extruded, granulated, cooled and dried to obtain the product; wherein the screw rotation speed of the double screw extruder is 300 r / min, and the double screw extruder comprises ten zones, wherein the first zone is a feeding zone, and the temperatures of the second to tenth zones are controlled to be 190℃, 200℃, 210℃, 210℃, 220℃, 210℃, 210℃, 210℃, 200℃, respectively.

[0050] Comparative Example 1

[0051] A polypropylene composite material, comprising the following raw materials by mass fraction: polypropylene 68 parts, talcum powder 20 parts, POE 5 parts, LDPE 5 parts, PP-g-MAH 2 parts, antioxidant 1010 0.25 parts, antioxidant 168 0.25 parts, calcium stearate 0.2 parts, and black masterbatch 1 part.

[0052] Preparation of a polypropylene composite material:

[0053] The polypropylene, talcum powder, POE, LDPE, PP-g-MAH, antioxidant 1010, antioxidant 168, calcium stearate, and black masterbatch are fully blended and then added to the main feeding port of a double screw extruder, and then melt extruded, granulated, cooled, and dried to obtain the product; the screw rotation speed of the double screw extruder is 400 r / min, and the double screw extruder comprises ten zones, wherein the first zone is a feeding zone, and the temperatures of the second to tenth zones are controlled to be 190℃, 200℃, 210℃, 210℃, 210℃, 210℃, 210℃, 200℃, and 200℃, respectively.

[0054] Comparative Example 2

[0055] A polypropylene composite material comprises the following raw materials by mass: polypropylene 68 parts, modified inorganic filler 20 parts, POE 5 parts, LDPE 5 parts, PP-g-MAH 2 parts, antioxidant 1010 0.25 parts, antioxidant 168 0.25 parts, calcium stearate 0.2 parts, and black masterbatch 1 part.

[0056] The modified inorganic filler is prepared by adding nanocellulose fiber, peroxide crosslinking agent DCP, and talcum powder in a mass ratio of 6:0.2:91.8 into a high-speed mixer and mixing at 60℃ for 30 min to obtain the product; the nanocellulose fiber has a brand of MFC and is produced by Zhejiang Hangzhou New Material Technology Co., Ltd., and has an aspect ratio of 1000-3000.

[0057] Preparation of a polypropylene composite material:

[0058] The polypropylene, modified inorganic filler, POE, LDPE, PP-g-MAH, antioxidant 1010, antioxidant 168, calcium stearate, and black masterbatch are fully blended and then added to the main feeding port of a double screw extruder, and then melt extruded, granulated, cooled, and dried to obtain the product; the screw rotation speed of the double screw extruder is 400 r / min, and the double screw extruder comprises ten zones, wherein the first zone is a feeding zone, and the temperatures of the second to tenth zones are controlled to be 190℃, 200℃, 210℃, 210℃, 210℃, 210℃, 210℃, 200℃, and 200℃, respectively.

[0059] Comparative Example 3

[0060] A polypropylene composite material comprises the following raw materials by mass: polypropylene 68 parts, modified inorganic filler 20 parts, POE 5 parts, LDPE 5 parts, PP-g-MAH 2 parts, antioxidant 1010 0.25 parts, antioxidant 168 0.25 parts, calcium stearate 0.2 parts, and black masterbatch 1 part.

[0061] The preparation method of the modified inorganic filler is as follows: titanate coupling agent, nanocellulose fiber and talcum powder are added into a high-speed mixer at a mass ratio of 2:6:91.8, and mixed at 60°C for 30 min, and the modified inorganic filler is obtained; wherein the nanocellulose fiber is of MFC brand, the manufacturer is Zhejiang Hangzhou New Material Technology Co., Ltd., and the aspect ratio is 1000-3000.

[0062] The polypropylene composite material is prepared by the following steps:

[0063] The polypropylene, the modified inorganic filler, the POE, the LDPE, the PP-g-MAH, the antioxidant 1010, the antioxidant 168, the calcium stearate and the black masterbatch are fully blended, and then added into a main feeding port of a double-screw extruder, and then subjected to melt extrusion, granulation, cooling and drying, and the polypropylene composite material is obtained; wherein the screw rotation speed of the double-screw extruder is 400 r / min, and the double-screw extruder comprises ten zones, wherein the first zone is a feeding zone, and the temperatures of the second zone to the tenth zone are controlled to be 190°C, 200°C, 210°C, 210°C, 210°C, 210°C, 210°C, 200°C and 200°C, respectively.

[0064] Comparative Example 4

[0065] The polypropylene composite material comprises the following raw materials in parts by mass: polypropylene 68 parts, modified inorganic filler 20 parts, POE 5 parts, LDPE 5 parts, PP-g-MAH 2 parts, antioxidant 1010 0.25 parts, antioxidant 168 0.25 parts, calcium stearate 0.2 parts and black masterbatch 1 part.

[0066] The preparation method of the modified inorganic filler is as follows: titanate coupling agent, peroxide crosslinking agent DCP and talcum powder are added into a high-speed mixer at a mass ratio of 2:0.2:91.8, and mixed at 60°C for 30 min, and the modified inorganic filler is obtained.

[0067] The polypropylene composite material is prepared by the following steps:

[0068] The polypropylene, the modified inorganic filler, the POE, the LDPE, the PP-g-MAH, the antioxidant 1010, the antioxidant 168, the calcium stearate and the black masterbatch are fully blended, and then added into a main feeding port of a double-screw extruder, and then subjected to melt extrusion, granulation, cooling and drying, and the polypropylene composite material is obtained; wherein the screw rotation speed of the double-screw extruder is 400 r / min, and the double-screw extruder comprises ten zones, wherein the first zone is a feeding zone, and the temperatures of the second zone to the tenth zone are controlled to be 190°C, 200°C, 210°C, 210°C, 210°C, 210°C, 210°C, 200°C and 200°C, respectively.

[0069] Comparative Example 5

[0070] A polypropylene composite material, comprising the following raw materials by mass fraction: polypropylene 68 parts, modified inorganic filler 20 parts, POE 5 parts, LDPE 5 parts, PP-g-MAH 2 parts, antioxidant 1010 0.25 parts, antioxidant 168 0.25 parts, calcium stearate 0.2 parts, black masterbatch 1 part.

[0071] The preparation method of the modified inorganic filler is: titanium ester coupling agent, nanocellulose fiber, peroxide crosslinking agent DCP and talc powder are added into a high-speed mixer at a mass ratio of 2:6:0.2:91.8, and mixed at 60°C for 30min, and then obtained; wherein the nanocellulose fiber is KEXLAN nanocellulose fiber, and the aspect ratio of the KEXLAN nanocellulose fiber is 50-200.

[0072] Preparation of a polypropylene composite material:

[0073] After the polypropylene, modified inorganic filler, POE, LDPE, PP-g-MAH, antioxidant 1010, antioxidant 168, calcium stearate and black masterbatch are fully blended, they are added into the main feeding port of a double-screw extruder, and then subjected to melt extrusion, granulation, cooling and drying, and then obtained; wherein the screw rotation speed of the double-screw extruder is 300-500r / min, and the double-screw extruder comprises ten zones, wherein the first zone is a feeding zone, and the temperatures of the second to tenth zones are controlled to be 190°C, 200°C, 210°C, 210°C, 210°C, 210°C, 210°C, 200°C and 200°C, respectively.

[0074] Comparative Example 6

[0075] A polypropylene composite material, comprising the following raw materials by mass fraction: polypropylene 68 parts, modified inorganic filler 20 parts, POE 5 parts, LDPE 5 parts, antioxidant 1010 0.25 parts, antioxidant 168 0.25 parts, calcium stearate 0.2 parts, black masterbatch 1 part.

[0076] The preparation method of the modified inorganic filler is: titanium ester coupling agent, nanocellulose fiber, peroxide crosslinking agent DCP and talc powder are added into a high-speed mixer at a mass ratio of 2:6:0.2:91.8, and mixed at 60°C for 30min, and then obtained; wherein the nanocellulose fiber is KEXLAN nanocellulose fiber, and the aspect ratio of the KEXLAN nanocellulose fiber is 50-200.

[0077] Preparation of a polypropylene composite material:

[0078] The polypropylene, modified inorganic filler, POE, LDPE, antioxidant 1010, antioxidant 168, calcium stearate and black masterbatch are sufficiently blended and then added into the main feeding port of a double screw extruder, and then melt extruded, granulated, cooled, and dried to obtain the product; wherein the screw rotation speed of the double screw extruder is 400 r / min, and the double screw extruder comprises ten zones, wherein the first zone is a feeding zone, and the temperature of the second zone to the tenth zone is controlled to be 190℃, 200℃, 210℃, 210℃, 210℃, 210℃, 210℃, 200℃, and 200℃, respectively.

[0079] Test example

[0080] The polypropylene composite materials prepared in Examples 1-5 and Comparative Examples 1-6 are subjected to mechanical property testing, and the results are shown in Table 1.

[0081] Table 1

[0082]

[0083]

[0084] As can be seen from Table 1, by comparing Example 1 with Comparative Examples 1-4, it can be seen that the yield elongation of the polypropylene composite material prepared from the talc powder after surface modification is significantly improved, and the mechanical properties are also obviously improved. This is because the nanocellulose fiber modifies the surface of the talc powder under the synergistic effect of the coupling agent and the crosslinking agent. On the one hand, the prepared modified talc powder ensures the sufficient dispersion of the nanocellulose, and makes the compatibility of the talc powder after modification with the polypropylene resin better. On the other hand, the disordered arrangement of the nanocellulose and its own toughness significantly improve the yield elongation of the material during the stretching process. As can be seen from the comparison of Example 1 with Comparative Example 5, the aspect ratio of the nanocellulose fiber also plays a key role in improving the yield elongation of the material. As can be seen from the comparison of Example 1 with Comparative Example 6, the addition of the compatilizer can further improve the compatibility of the modified filler powder and the nanocellulose fiber on the surface of the powder with the polypropylene resin, reduce the generation of internal stress concentration points, and thus improve the yield elongation.

[0085] The above merely describes the preferred embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can make equivalent substitutions or changes to the technical solutions and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A high-elongation-at-yield polypropylene composite, characterized in that, The raw materials include the following mass parts: polypropylene 45-93 parts, modified inorganic filler 5-30 parts, toughening agent 1-20 parts, compatibilizer 1-5 parts, and other auxiliary agents 0.5-2 parts; The preparation method of the modified inorganic filler comprises the following steps: fully mixing a coupling agent, nanocellulose fibers, a peroxide crosslinking agent, and an inorganic filler, and obtaining the modified inorganic filler. The aspect ratio of the nanocellulose fibers is 1000-3000. The mass ratio of the coupling agent, nanocellulose fibers, peroxide crosslinking agent, and inorganic filler is (1-3) :(2-10) :(0.1-0.5) :(86.5-96.9). The inorganic filler is at least one of talc, calcium carbonate, wollastonite, magnesium sulfate whisker, and mica powder; the coupling agent is an aluminic ester coupling agent, a titanate coupling agent, or a combination thereof; and the peroxide crosslinking agent is at least one of dicumyl peroxide, di-tert-butyl peroxide, and tert-butyl peroxybenzoate.

2. The high elongation at yield polypropylene composite of claim 1, wherein In the preparation method of the modified inorganic filler, the mixing temperature is 50-70 DEG C, and the mixing time is 20-40 min.

3. The high elongation at yield polypropylene composite of claim 1, wherein The melt flow rate of the polypropylene under the test conditions of 230 DEG C and 2.16 kg is 5-100 g / 10 min.

4. The high elongation at yield polypropylene composite of claim 1, wherein The toughening agent is at least one of POE, EPDM, HDPE, LDPE, and SEBS.

5. The high elongation at yield polypropylene composite of claim 1, wherein The compatibilizer is at least one of PP-g-MAH, POE-g-MAH, and SEBS-g-MAH.

6. The high elongation at yield polypropylene composite of claim 1, wherein The other auxiliary agents are at least one of antioxidants, lubricants, UV-resistant agents, and pigments.

7. A process for the preparation of a high-elongation-at-yield polypropylene composite according to any one of claims 1 to 6, characterized in that, The method comprises the following steps: weighing the raw materials according to the mass parts, fully blending the polypropylene, modified inorganic filler, toughening agent, compatibilizer, and other auxiliary agents, and then adding them into an extruder to melt extrude, granulate, cool, and dry.

8. The process for the preparation of high yield elongation polypropylene composites as claimed in claim 7, wherein, The extruder is a double-screw extruder, and the temperature for melt extrusion is 190-220 DEG C. The screw rotation speed of the extruder is 300-500 r / min.

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