Preparation method of an environment-friendly lightweight polypropylene composite material resistant to animal bites

Abstract

The present invention relates to a preparation method of an environment-friendly lightweight anti-animal-bite polypropylene composite material. The PP resin I, plant fiber masterbatch, bittering agent, antioxidant, dispersant I, compatibilizer I and weathering agent are mixed evenly and then melt-extruded and pelletized to obtain the environment-friendly lightweight anti-animal-bite polypropylene composite material. The plant fiber masterbatch is obtained by adding the PP resin II premix and the pre-infiltrated plant fiber into the main feeding port and the side feeding port of a twin-screw extruder respectively and then melt-extruding and pelletizing. The PP resin II premix is obtained by mixing the PP resin II, compatibilizer II, antioxidant and dispersant II evenly. In the preparation method of the present invention, the plant fiber is pre-infiltrated by an infiltrant, and through the combined action of the low-melting-point compatibilizer II and the polar dispersant II, the risk of carbonization is reduced, and a plant fiber masterbatch with good dispersibility is prepared, so that the prepared product has excellent performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of PP composite materials, and relates to a preparation method of an environment-friendly lightweight polypropylene composite material for preventing animal bites. Background Art

[0002] With the rapid development of the pet industry, accessories such as cat cages, dog cages, and hamster cages have attracted more and more attention. Colorful and various-shaped designs have become the top choices for people. However, since cats, dogs, hamsters, etc. are rodents and they like to chew on cages, most of the cages on the market are currently made of stainless steel. Because they cannot be painted (pets will chew and eat the paint), most of the cages are currently in the color of stainless steel. The single color cannot meet the current trend of younger pet breeding. Pet cages made of stainless steel are not only relatively heavy and not suitable for carrying, but also not suitable for making complex shapes, thus restricting their development towards diversification.

[0003] Due to its good chemical resistance, light weight, rich modification methods, and easy processing, polypropylene materials have become common materials in the fields of automobiles, small household appliances, pets, etc.; moreover, modified polypropylene materials can also achieve bright colors and rich shapes.

[0004] At present, research on preventing rodent bites and plant fiber-reinforced polypropylene has been reported. The Greek patent with the publication number GR20010100474A discloses a polymer mixture containing an animal repellent and a method for manufacturing pipes with higher animal bite resistance. By adding an animal repellent to the mixture for producing pipes or cables, the function of preventing animals from biting or chewing through is achieved, thereby manufacturing pipes with higher damage resistance. However, such materials generally have average mechanical strength and a strong smell and cannot be used in the pet field. The Chinese patent application with the publication number CN103571213A discloses a wood fiber-filled reinforced polypropylene composite material for automobile interior parts and its preparation method. By filling and reinforcing polypropylene with wood fibers, the performance of the prepared composite material is equivalent to that of talc-filled polypropylene, but its density is lower, which can achieve the purpose of lightweight. Moreover, wood fibers are renewable and can reduce environmental pollution. However, this composite material has no effect of preventing animals from chewing and cannot be used in pet cages. Even if a repellent such as a bitter agent is added during the processing, due to the one-step method of processing wood fiber-filled polypropylene, it cannot be well processed at a high filling amount, and the carbonization probability is relatively high when making light colors, resulting in obvious black spots and affecting the color effect. Moreover, the performance of the high-filling composite material prepared by this method is relatively low, and the dispersion of plant fibers is poor (poor dispersion leads to unstable composite material performance and easy appearance of floating fibers).

[0005] Therefore, it is of great significance to study a preparation method of an environment-friendly lightweight polypropylene composite material for preventing animal bites to solve the above problems. Summary of the Invention

[0006] The object of the present invention is to solve the problems existing in the prior art and provide a preparation method of an environmentally friendly lightweight anti-animal-bite polypropylene composite material.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A preparation method of an environmentally friendly lightweight anti-animal-bite polypropylene composite material, in which PP resin I, plant fiber masterbatch, bittering agent, antioxidant, dispersant I, compatibilizer I and weathering agent are mixed evenly and then melt-extruded and pelletized to obtain the environmentally friendly lightweight anti-animal-bite polypropylene composite material;

[0009] The plant fiber masterbatch is obtained by adding the PP resin II premix and the pre-impregnated plant fiber into the main feeding port and the side feeding port of a twin-screw extruder respectively and then melt-extruding and pelletizing;

[0010] The PP resin II premix is obtained by mixing PP resin II, compatibilizer II, antioxidant and dispersant II evenly; the compatibilizer II is maleic anhydride grafted PE or EVA grafted maleic anhydride, and the dispersant II is a mixture of maleic anhydride grafted polypropylene wax and oxidized polyethylene wax in a mass ratio of 1-3:1;

[0011] The pre-impregnated plant fiber is plant fiber treated with an impregnating agent, and the impregnating agent is a titanate coupling agent or a silane coupling agent;

[0012] The density of the environmentally friendly lightweight anti-animal-bite polypropylene composite material is 0.92-1.0 g / cm 3 , the tensile strength is 29-36 MPa, the flexural strength is 32-45 MPa, the flexural modulus is 1750-3100 MPa, and the notched impact strength is 3.2-10.5 KJ / m 2 .

[0013] As a preferred technical solution:

[0014] For the preparation method of the environmentally friendly lightweight anti-animal-bite polypropylene composite material as described above, the Vicat softening temperature of maleic anhydride grafted PE is 88-97 °C, and the grafting rate is 1.0-1.2%, preferably Lotte EM-400; the Vicat softening point of EVA grafted maleic anhydride is 43-72 °C, and the grafting rate is 1.2-1.6%, preferably SK T 9314; the grafting rate of maleic anhydride grafted polypropylene wax is 5-10%, and the weight average molecular weight is 3000-8000, preferably Honeywell A-C597P; the acid value of oxidized polyethylene wax is 15-25 mg KOH / g, preferably Licowax PED 521.

[0015] For the preparation method of the environmentally friendly lightweight anti-animal-bite polypropylene composite material as described in any one of the above, the specific steps are as follows:

[0016] (1) Put the plant fiber and the sizing agent into a low-speed mixer with a speed of 50 - 80 rpm, mix at a temperature of 30 - 50 °C for 5 - 7 min, and then discharge to obtain pre-impregnated plant fiber;

[0017] (2) Put PP resin II, compatibilizer II, antioxidant, and dispersant II into a high-speed mixer with a speed of 220 - 400 rpm and mix for 6 - 12 min to form a pre-mixed PP resin II;

[0018] (3) Add the pre-mixed PP resin II from the main feeding port of the twin-screw extruder, and add the pre-impregnated plant fiber from the side feeding port of the twin-screw extruder. Conduct melt extrusion granulation in a twin-screw extruder with a processing temperature of 160 - 200 °C to obtain plant fiber masterbatch;

[0019] (4) Put PP resin I, plant fiber masterbatch, bittering agent, antioxidant, dispersant I, compatibilizer I, and weathering agent into a high-speed mixer with a speed of 220 - 480 rpm and mix evenly for 5 - 10 min to form a pre-mixed PP resin I;

[0020] (5) Add the pre-mixed PP resin I from the main feeding port of the twin-screw extruder, and conduct melt extrusion granulation in a twin-screw extruder with a processing temperature of 160 - 210 °C to prepare an environment-friendly lightweight anti-animal-bite polypropylene composite material.

[0021] For the preparation method of an environment-friendly lightweight anti-animal-bite polypropylene composite material as described above, by weight, the raw material formula of the plant fiber masterbatch is as follows:

[0022]

[0023] For the preparation method of an environment-friendly lightweight anti-animal-bite polypropylene composite material as described above, the melt index of PP resin II under the test conditions of 230 °C and 2.16 kg is 25 - 120 g / 10 min;

[0024] The plant fiber is one or more of wood fiber, bamboo fiber, hemp fiber, and cellulose fiber.

[0025] For the preparation method of an environment-friendly lightweight anti-animal-bite polypropylene composite material as described above, by weight, the raw material formula of the environment-friendly lightweight anti-animal-bite polypropylene composite material is as follows:

[0026]

[0027] For the preparation method of an environment-friendly lightweight anti-animal-bite polypropylene composite material as described above, the melt index of PP resin I under the test conditions of 230 °C and 2.16 kg is 10 - 60 g / 10 min;

[0028] The bittering agent is denatonium benzoate, and its melting point is 164 - 168 °C;

[0029] The dispersant I is a mixture of maleic anhydride grafted polypropylene wax and polyethylene wax in a mass ratio of 1:1. Among them, the maleic anhydride grafted polypropylene wax preferably belongs to the Clariant LICOCENE PP series; the Clariant LICOCENE PP series is a metallocene-catalyzed maleic anhydride polypropylene wax with a melting point of 85 - 95 °C, having fast dispersion effect and reaction speed, and a fast response to the dispersion of plant fibers;

[0030] The dispersants of polyethylene wax and maleic anhydride polypropylene wax have a small molecular weight and a low melting point, and melt in advance during the period with a relatively low temperature at the initial stage of processing. The pre-melted small molecules are similar to plasticizers, which can reduce the melt viscosity, reduce the shear heat generated by the screw due to the high melt viscosity, prevent overheating degradation, and can protect the bittering agent; among them, polyethylene wax is more economical and affordable, so the combination of maleic anhydride grafted polypropylene wax and polyethylene wax is selected;

[0031] The compatibilizer I is polypropylene grafted maleic anhydride (PP-g-MAH) or POE grafted maleic anhydride (POE-g-MAH);

[0032] The weathering agent is one or more of 2-(2'-hydroxy-5'-tert-octylphenyl) benzotriazole (UV-329), 2,2,6,6-tetramethyl-4-piperidyl stearate, bis(2,2,6,6-tetramethylpiperidyl) sebacate, and 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl) phenol.

[0033] For the preparation method of an environmentally friendly lightweight anti-animal-bite polypropylene composite material as described above, the antioxidant is a mixture of a hindered phenol antioxidant and a phosphite in a mass ratio of 1:2;

[0034] The hindered phenol antioxidant is one or more of pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxy) benzoate, n-octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, and triethylene glycol bis(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate, and the phosphite is one or more of tris(2,4-di-tert-butylphenyl) phosphite and bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite.

[0035] For the preparation method of an environmentally friendly lightweight anti-animal-bite polypropylene composite material as described above, in step (2), the temperatures set for the twin-screw extruder from the first zone to the ninth zone are 160 - 180 °C, 180 - 200 °C, 180 - 200 °C, 190 - 200 °C, 190 - 200 °C, 190 - 200 °C, 190 - 200 °C, 190 - 200 °C, and 180 - 190 °C in sequence.

[0036] For the preparation method of an environment-friendly lightweight anti-animal-bite polypropylene composite material as described above, the temperatures set for the twin-screw extruder from the first zone to the ninth zone in step (5) are successively: 160 - 180 °C, 180 - 200 °C, 180 - 200 °C, 190 - 210 °C, 190 - 210 °C, 190 - 210 °C, 190 - 210 °C, 190 - 210 °C, 190 - 200 °C.

[0037] Principle of the present invention:

[0038] The present invention first uses a sizing agent to perform pre-infiltration treatment on plant fibers to increase the surface polar groups of the plant fibers (polar groups are beneficial for polar compatibilizers and polar dispersants to quickly react with the surface of the plant fibers). Then, a low-melting-point dispersant and a compatibilizer (i.e., dispersant II and compatibilizer II) are used to improve the dispersibility of the plant fibers and the compatibility with the non-polar polypropylene matrix (i.e., PP resin II), reducing the risk of carbonization of the plant fibers during twin-screw extrusion processing due to poor compatibility, so that the prepared anti-animal-bite polypropylene composite material has high performance and excellent appearance. Because the bittering agent has a slight pungent smell, the present invention uses the natural smell of the plant fibers to cover the animal repellent, thereby reducing the impact of the smell on pets.

[0039] Among them, specifically, dispersant II is a mixture of maleic anhydride grafted polypropylene wax and oxidized polyethylene wax in a mass ratio of 1 - 3:1. This type of dispersant contains both dispersibility and polar groups and is used in mineral filling and reinforcement, but mainly to improve the dispersion of minerals in the resin, and there is no prior art of using a polar compatibilizer and a polar dispersant in combination.

[0040] In the production of plant fiber masterbatch, the present invention adopts a compatibilizer with a high grafting rate and a low melting point (i.e., compatibilizer II), which is melted in advance in the melting section of a twin-screw extruder. Through the reaction of the grafted maleic anhydride groups with polar groups such as hydroxyl, carboxyl, and carbonyl groups on the surface of plant fibers, the previously melted compatibilizer II quickly wraps the plant fibers. Then, maleic anhydride grafted polypropylene wax and oxidized polyethylene wax are used to quickly disperse the plant fibers into the polypropylene matrix. Among them, maleic anhydride grafted polypropylene wax has a high grafting rate but a high melting point, and oxidized polyethylene wax has a low melting point. Moreover, maleic anhydride grafted polypropylene wax has polarity, so that the plant fibers with the same polarity can be better dispersed in the polypropylene resin matrix. Since the plant fibers are wrapped by compatibilizer II and evenly dispersed, the viscosity difference between the plant fibers and PP resin II in the twin-screw is reduced. PP resin II can well wrap the plant fibers, making it difficult for the plant fibers to appear on the melt surface during the twin-screw processing, so that the plant fibers are not easily accumulated on the screw or in the barrel, reducing the risk of carbonization. The plant fibers are not easily carbonized during the processing, and can have a good fiber retention length, making the prepared composite material have high properties such as tensile strength and flexural strength.

[0041] Beneficial effects:

[0042] (1) The preparation method of an environmentally friendly lightweight anti-animal-bite polypropylene composite material of the present invention has low cost and good popularization value;

[0043] (2) The preparation method of an environmentally friendly lightweight anti-animal-bite polypropylene composite material of the present invention pre-infiltrates plant fibers with an infiltrant. Through the combined action of a low-melting-point compatibilizer II and a polar dispersant II, the risk of carbonization is reduced, and a plant fiber masterbatch with good dispersibility is prepared. Then, by adjusting different fiber addition amounts and compounding an animal repellent, environmentally friendly lightweight anti-animal-bite polypropylene composite materials with different strengths and excellent properties are prepared, which can be widely applied to the fields of pets, household appliances, and home furnishings. Specific embodiments

[0044] The following further elaborates the present invention in combination with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0045] The test methods related to the embodiments of the present invention are as follows:

[0046] Tensile strength: Tested with reference to ISO 527-2:2012, and the test speed is 50 mm / min;

[0047] Flexural strength and flexural modulus: Tested in accordance with ISO 178:2019 at a test speed of 2 mm / min;

[0048] Notched impact strength: Tested in accordance with ISO 179-1:2010.

[0049] Example 1

[0050] A preparation method of an environmentally friendly lightweight anti-animal bite polypropylene composite material, the specific steps are as follows:

[0051] (1) Preparation of raw materials:

[0052] Plant fiber: Lignocellulose fiber (manufacturer: JRS, product number: E140);

[0053] Sizing agent: Titanate coupling agent (manufacturer: Nanjing Tengchuan Technology Co., Ltd., brand: TC-27);

[0054] PP resin I: Manufacturer: SK, brand: BX3800, melt index under test conditions of 230 °C and 2.16 kg is 30 g / 10 min;

[0055] PP resin II: Manufacturer: Zhongsha Tianjin, brand: 511MK40T, melt index under test conditions of 230 °C and 2.16 kg is 28 g / 10 min;

[0056] Compatibilizer II: Maleic anhydride grafted PE (manufacturer: Jia Yirong Polymers (Shanghai) Co., Ltd., brand: CMG5904), Vicat softening temperature of maleic anhydride grafted PE is 88 °C, grafting rate is 1%;

[0057] Antioxidant: A mixture of a hindered phenol antioxidant and a phosphite in a mass ratio of 1:2; the hindered phenol antioxidant is pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxy)benzoate, and the phosphite is tris(2,4-di-tert-butylphenyl) phosphite;

[0058] Dispersant II: A mixture of maleic anhydride grafted polypropylene wax and oxidized polyethylene wax in a mass ratio of 1:1; the grafting rate of maleic anhydride grafted polypropylene wax is 10%, the weight average molecular weight is 5000, the manufacturer of maleic anhydride grafted polypropylene wax: Honeywell, brand: A-C597P; the acid value of oxidized polyethylene wax is 17 mg KOH / g, the manufacturer of oxidized polyethylene wax: Clariant, brand: Licowax PED 521;

[0059] Bitterness agent: Denatonium benzoate;

[0060] Dispersant Ⅰ: It is made by mixing maleic anhydride grafted polypropylene wax and polyethylene wax in a mass ratio of 1:1; Manufacturer of maleic anhydride grafted polypropylene wax: Clariant, Model: LICOCENE PP MA6252; Manufacturer of polyethylene wax: SCG, Grade: LP0040P;

[0061] Compatibilizer Ⅰ: Polypropylene grafted maleic anhydride, Manufacturer: Jia Yirong Polymer (Shanghai) Co., Ltd., Grade: CMG5001;

[0062] Weather resistance agent: 2-(2'-hydroxy-5'-tert-octylphenyl) benzotriazole (UV-329);

[0063] (2) By weight, 100 parts of plant fiber and 1 part of wetting agent are put into a low-speed mixer with a speed of 50 rpm, and mixed at a temperature of 30 °C for 7 minutes and then discharged to obtain pre-wetted plant fiber;

[0064] (3) By weight, 100 parts of PP resin Ⅱ, 2 parts of compatibilizer Ⅱ, 0.3 part of antioxidant and 0.6 part of dispersant Ⅱ are put into a high-speed mixer with a speed of 220 rpm and mixed for 12 minutes to form a pre-mixed PP resin Ⅱ;

[0065] (4) The pre-mixed PP resin Ⅱ is added from the main feeding port of the twin-screw extruder, and the pre-wetted plant fiber is added from the side feeding port of the twin-screw extruder, and melt extrusion granulation is carried out in the twin-screw extruder to obtain plant fiber masterbatch;

[0066] The temperatures of the twin-screw extruder are set from the first zone to the ninth zone as 160 °C, 180 °C, 180 °C, 190 °C, 190 °C, 190 °C, 190 °C, 190 °C, 180 °C in sequence;

[0067] (5) By weight, 100 parts of PP resin Ⅰ, 100 parts of plant fiber masterbatch, 0.3 part of bittering agent, 0.6 part of antioxidant, 0.6 part of dispersant Ⅰ, 6 parts of compatibilizer Ⅰ and 0.5 part of weather resistance agent are mixed evenly in a high-speed mixer with a speed of 220 rpm for 10 minutes to form a pre-mixed PP resin Ⅰ;

[0068] (6) The pre-mixed PP resin Ⅰ is added from the main feeding port of the twin-screw extruder, and melt extrusion granulation is carried out in the twin-screw extruder to obtain an environmentally friendly lightweight animal-bite-proof polypropylene composite material;

[0069] The temperatures of the twin-screw extruder are set from the first zone to the ninth zone as follows: 160 °C, 180 °C, 180 °C, 190 °C, 190 °C, 190 °C, 190 °C, 190 °C, 190 °C in sequence.

[0070] The density of the finally obtained environmentally friendly lightweight animal-bite-proof polypropylene composite material is 1 g / cm3 with a tensile strength of 36 MPa, a flexural strength of 45 MPa, a flexural modulus of 3100 MPa, and a notched impact strength of 3.2 KJ / m 2 。

[0071] Comparative Example 1

[0072] A preparation method of a polypropylene composite material is basically the same as that of Example 1, except that compatibilizer II is omitted.

[0073] The density of the finally prepared environmentally friendly lightweight anti-animal-bite polypropylene composite material is 1.0 g / cm 3 with a tensile strength of 30 MPa, a flexural strength of 38 MPa, a flexural modulus of 2650 MPa, and a notched impact strength of 2.4 KJ / m 2 。

[0074] Comparing Comparative Example 1 with Example 1, it can be seen that due to the absence of compatibilizer II in Comparative Example 1, the mechanical properties of the prepared composite material are significantly lower than those of Example 1. This is because without the addition of compatibilizer II, the plant fibers cannot be effectively coated by the low-melting polymer during the preparation of the plant fiber masterbatch, resulting in easy carbonization during the heating process and easy to be shredded by the twin-screw during the extrusion process. Therefore, the retained length of the fibers in the prepared plant fiber masterbatch is shorter, and the mechanical properties of the subsequent prepared composite material decrease significantly.

[0075] Comparative Example 2

[0076] A preparation method of a polypropylene composite material is basically the same as that of Example 1, except that dispersant II is omitted.

[0077] The density of the finally prepared environmentally friendly lightweight anti-animal-bite polypropylene composite material is 1 g / cm 3 with a tensile strength of 32 MPa, a flexural strength of 40 MPa, a flexural modulus of 2830 MPa, and a notched impact strength of 2.7 KJ / m 2 。

[0078] Comparing Comparative Example 2 with Example 1, it can be seen that due to the absence of the polar dispersant II in the preparation process of the plant fiber masterbatch, the performance of the composite material prepared in Comparative Example 1 is lower than the mechanical properties of the composite material prepared in Example 1. This is because the maleic anhydride grafted polypropylene wax and oxidized polyethylene wax of dispersant II disperse the plant fibers into the polypropylene matrix quickly. Among them, the maleic anhydride grafted polypropylene wax has a high grafting rate but a high melting point, and the oxidized polyethylene wax has a low melting point, and both have polarity. Therefore, during the preparation of the masterbatch, it can not only play a role in rapid dispersion, but also pre-coat the plant fibers, which has a positive effect on the retained length of the plant fibers after twin-screw extrusion processing, thereby improving the mechanical properties of the composite material.

[0079] Example 2

[0080] A preparation method of an environmentally friendly lightweight polypropylene composite material resistant to animal bites, and the specific steps are as follows:

[0081] (1) Preparation of raw materials:

[0082] Plant fiber: Moso bamboo fiber (manufacturer: Sichuan Changsheng New Material Technology Co., Ltd.);

[0083] Sizing agent: Silane coupling agent (manufacturer: Shandong Huachen New Material Co., Ltd., grade: KH550);

[0084] PP resin I: Manufacturer: CNOOC and Shell, grade: EP300M, melt index under the test conditions of 230°C and 2.16 kg is 10 g / 10 min;

[0085] PP resin II: Manufacturer: South Korea SK, grade: BX3920, melt index under the test conditions of 230°C and 2.16 kg is 100 g / 10 min;

[0086] Compatibilizer II: EVA grafted maleic anhydride (manufacturer: SK, grade: 18211), Vicat softening point of EVA grafted maleic anhydride is 51°C, grafting rate is 1.2%;

[0087] Antioxidant: A mixture of hindered phenol antioxidant and phosphite in a mass ratio of 1:2; The hindered phenol antioxidant is n-octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and the phosphite is bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite;

[0088] Dispersant II: A mixture of maleic anhydride grafted polypropylene wax and oxidized polyethylene wax in a mass ratio of 2:1; The grafting rate of maleic anhydride grafted polypropylene wax is 5%, the weight average molecular weight is 3000, manufacturer: Honeywell, grade: A-C907P; The acid value of oxidized polyethylene wax is 25 mg KOH / g, manufacturer of oxidized polyethylene wax: Clariant, grade: Licowax PED 522;

[0089] Bitterness agent: Denatonium benzoate;

[0090] Dispersant I: A mixture of maleic anhydride grafted polypropylene wax and polyethylene wax in a mass ratio of 1:1; Manufacturer of maleic anhydride grafted polypropylene wax: Clariant, grade: LICOCENE PP MA6452; Manufacturer of polyethylene wax: Clariant, grade: PE520;

[0091] Compatibilizer I: POE grafted maleic anhydride, manufacturer: Jia Yirong Polymer (Shanghai) Co., Ltd., grade: CMG5805;

[0092] Weathering agent: 2,2,6,6-tetramethyl-4-piperidyl stearate;

[0093] (2) By weight, put 60 parts of plant fiber and 3 parts of sizing agent into a low-speed mixer with a speed of 55 rpm, mix at a temperature of 35 °C for 7 minutes and then discharge to obtain pre-impregnated plant fiber;

[0094] (3) By weight, put 100 parts of PP resin II, 5 parts of compatibilizer II, 0.5 part of antioxidant and 1.5 parts of dispersant II into a high-speed mixer with a speed of 260 rpm and mix for 11 minutes to form a PP resin II premix;

[0095] (4) Add the PP resin II premix from the main feed port of the twin-screw extruder, add the pre-impregnated plant fiber from the side feed port of the twin-screw extruder, and carry out melt extrusion granulation in the twin-screw extruder to obtain plant fiber masterbatch;

[0096] The temperatures of the twin-screw extruder from the first zone to the ninth zone are set as 165 °C, 185 °C, 185 °C, 192 °C, 192 °C, 192 °C, 192 °C, 192 °C, 182 °C in sequence;

[0097] (5) By weight, put 100 parts of PP resin I, 40 parts of plant fiber masterbatch, 0.4 part of bittering agent, 0.3 part of antioxidant, 0.2 part of dispersant I, 3 parts of compatibilizer I and 0.3 part of weathering agent into a high-speed mixer with a speed of 280 rpm and mix evenly for 9 minutes to form a PP resin I premix;

[0098] (6) Add the PP resin I premix from the main feed port of the twin-screw extruder, and carry out melt extrusion granulation in the twin-screw extruder to prepare an environmentally friendly lightweight anti-animal-bite polypropylene composite material;

[0099] The temperatures of the twin-screw extruder from the first zone to the ninth zone are set as follows: 165 °C, 185 °C, 185 °C, 195 °C, 195 °C, 195 °C, 195 °C, 195 °C, 192 °C in sequence.

[0100] The density of the finally prepared environmentally friendly lightweight anti-animal-bite polypropylene composite material is 0.92 g / cm 3 , the tensile strength is 29 MPa, the flexural strength is 32 MPa, the flexural modulus is 1750 MPa, and the notched impact strength is 10.5 KJ / m 2 .

[0101] Example 3

[0102] A preparation method of an environmentally friendly lightweight anti-animal-bite polypropylene composite material, the specific steps are as follows:

[0103] (1) Preparation of raw materials:

[0104] Plant fiber: hemp staple fiber (manufacturer: Linyi Yuanma Crafts Co., Ltd.);

[0105] Wetting agent: titanate coupling agent (manufacturer: Nanjing Tengchuan Technology Co., Ltd., brand: TC-114);

[0106] PP resin I: Manufacturer: Zhenhai Refining and Chemical, brand: MR60HC, melt index at 230°C, 2.16kg test conditions: 60g / 10min;

[0107] PP resin II: Manufacturer: Lanzhou Petrochemical, brand: EP708N, melt index: 70g / 10min at 230℃, 2.16kg test conditions;

[0108] Compatibilizer II: maleic anhydride grafted PE (manufacturer: Coase Chemical Co., Ltd., brand: W1L). The Vicat softening temperature of maleic anhydride grafted PE is 97°C, and the grafting rate is 1%;

[0109] Antioxidant: A hindered phenol antioxidant and a phosphite are mixed in a mass ratio of 1:2; the hindered phenol antioxidant is triethylene glycol ether-bis(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate, and the phosphite is tris(2,4-di-tert-butylbenzene) phosphite and bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite in a mass ratio of 1:1;

[0110] Dispersant II: Maleic anhydride-grafted polypropylene wax and oxidized polyethylene wax mixed in a mass ratio of 3:1; the grafting rate of the maleic anhydride-grafted polypropylene wax is 8%, and the weight-average molecular weight is 5000. The maleic anhydride-grafted polypropylene wax is manufactured by Clariant, and the brand is LICOCENE PP MA 6452. The acid value of the oxidized polyethylene wax is 18 mg KOH / g. The manufacturer of the oxidized polyethylene wax is Clariant, and the brand is Licowax PED 121.

[0111] Bittering agent: Denatonium Benzyl;

[0112] Dispersant I: Maleic anhydride grafted polypropylene wax and polyethylene wax mixed in a mass ratio of 1:1; Maleic anhydride grafted polypropylene wax manufacturer: Clariant, brand: LICOCENE PP MA7452 TP; Polyethylene wax manufacturer: Qingdao Sino, brand: SN118;

[0113] Compatibilizer I: Polypropylene grafted maleic anhydride, manufacturer of polypropylene grafted maleic anhydride: Coase Chemical Co., Ltd., brand: B2;

[0114] Weathering agent: bis-2,2,6,6-tetramethylpiperidinol sebacate;

[0115] (2) Weighing by parts by weight, put 80 parts of plant fiber and 2 parts of sizing agent into a low-speed mixer with a speed of 60 rpm, mix at a temperature of 40 °C for 6.5 min and then discharge to obtain pre-impregnated plant fiber;

[0116] (3) Weighing by parts by weight, put 100 parts of PP resin II, 3.5 parts of compatibilizer II, 0.4 parts of antioxidant and 1 part of dispersant II into a high-speed mixer with a speed of 300 rpm and mix for 10 min to form a pre-mixed PP resin II;

[0117] (4) Add the pre-mixed PP resin II into the main feeding port of the twin-screw extruder, and add the pre-impregnated plant fiber into the side feeding port of the twin-screw extruder, and carry out melt extrusion granulation in the twin-screw extruder to obtain plant fiber masterbatch;

[0118] The temperatures of the twin-screw extruder are set from the first zone to the ninth zone as 170 °C, 190 °C, 190 °C, 194 °C, 194 °C, 194 °C, 194 °C, 194 °C, 184 °C in sequence;

[0119] (5) Weighing by parts by weight, put 100 parts of PP resin I, 50 parts of plant fiber masterbatch, 0.5 parts of bittering agent, 0.4 parts of antioxidant, 0.3 parts of dispersant I, 4 parts of compatibilizer I and 0.4 parts of weathering agent into a high-speed mixer with a speed of 340 rpm and mix evenly for 8 min to form a pre-mixed PP resin I;

[0120] (6) Add the pre-mixed PP resin I into the main feeding port of the twin-screw extruder, and carry out melt extrusion granulation in the twin-screw extruder to obtain an environment-friendly lightweight anti-animal-bite polypropylene composite material;

[0121] The temperatures of the twin-screw extruder are set from the first zone to the ninth zone as: 170 °C, 190 °C, 190 °C, 200 °C, 200 °C, 200 °C, 200 °C, 200 °C, 194 °C in sequence.

[0122] The density of the finally obtained environment-friendly lightweight anti-animal-bite polypropylene composite material is 0.94 g / cm 3 , the tensile strength is 31 MPa, the flexural strength is 34 MPa, the flexural modulus is 1970 MPa, and the notch impact strength is 9.1 KJ / m 2 .

[0123] Example 4

[0124] A preparation method of an environment-friendly lightweight anti-animal-bite polypropylene composite material, the specific steps are as follows:

[0125] (1) Preparation of raw materials:

[0126] Plant fiber: Pine wood fiber (manufacturer: Shandong Baoxiang Engineering Materials Co., Ltd.);

[0127] Sizing agent: Silane coupling agent (manufacturer: Shandong Huachen New Materials Co., Ltd., grade: KH560);

[0128] PP resin I: Manufacturer: Zhongsha Petrochemical, grade: EP5074X, melt index under test conditions of 230°C and 2.16 kg is 30 g / 10 min;

[0129] PP resin II: Manufacturer: Ningbo Taifu, grade: 3029, melt index under test conditions of 230°C and 2.16 kg is 29 g / 10 min;

[0130] Compatibilizer II: EVA grafted maleic anhydride (manufacturer: DOW, grade: 30E868), Vicat softening point of EVA grafted maleic anhydride is 65°C, grafting rate is 1.3%;

[0131] Antioxidant: Composed of hindered phenolic antioxidant and phosphite ester mixed in a mass ratio of 1:2; The hindered phenolic antioxidant is pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxy)benzoate, and the phosphite ester is tris(2,4-di-tert-butylphenyl) phosphite;

[0132] Dispersant II: Composed of maleic anhydride grafted polypropylene wax and oxidized polyethylene wax mixed in a mass ratio of 1:1; The grafting rate of maleic anhydride grafted polypropylene wax is 6%, the weight average molecular weight is 8000, manufacturer of maleic anhydride grafted polypropylene wax: Clariant, grade: LICOCENE PP MA 6252; The acid value of oxidized polyethylene wax is 20 mg KOH / g, manufacturer of oxidized polyethylene wax: Qingdao Saino, grade: 3316;

[0133] Bittering agent: Denatonium benzoate;

[0134] Dispersant I: Composed of maleic anhydride grafted polypropylene wax and polyethylene wax mixed in a mass ratio of 1:1; Manufacturer of maleic anhydride grafted polypropylene wax: Clariant, grade: LICOCENE PP MA 1332TP; Manufacturer of polyethylene wax: Qingdao Saino, grade: SN110D;

[0135] Compatibilizer I: POE grafted maleic anhydride, manufacturer: Mitsui Chemicals, Japan, grade: MA8510;

[0136] Weathering agent: 2-(2H-benzotriazol-2)-4,6-bis(1-methyl-1-phenylethyl)phenol;

[0137] (2) Weigh 70 parts by weight of plant fiber and 1.5 parts of sizing agent, and put them into a low-speed mixer with a speed of 65 revolutions per minute. After mixing at a temperature of 45°C for 6 minutes, discharge the material to obtain pre-infiltrated plant fiber;

[0138] (3) Weigh 100 parts by weight of PP resin II, 3 parts of compatibilizer II, 0.5 part of antioxidant, and 0.8 part of dispersant II, and put them into a high-speed mixer with a speed of 340 revolutions per minute to mix for 9 minutes to form a pre-mixed material of PP resin II;

[0139] (4) Add the pre-mixed material of PP resin II from the main feeding port of the twin-screw extruder, and add the pre-infiltrated plant fiber from the side feeding port of the twin-screw extruder. Then, carry out melt extrusion granulation in the twin-screw extruder to obtain plant fiber masterbatch;

[0140] The temperatures set from the first zone to the ninth zone of the twin-screw extruder are 175°C, 195°C, 195°C, 196°C, 196°C, 196°C, 196°C, 196°C, and 186°C in sequence;

[0141] (5) Weigh 100 parts by weight of PP resin I, 60 parts of plant fiber masterbatch, 0.7 part of bittering agent, 0.5 part of antioxidant, 0.4 part of dispersant I, 4 parts of compatibilizer I, and 0.4 part of weather resistance agent, and mix them evenly in a high-speed mixer with a speed of 400 revolutions per minute for 7 minutes to form a pre-mixed material of PP resin I;

[0142] (6) Add the pre-mixed material of PP resin I from the main feeding port of the twin-screw extruder, and carry out melt extrusion granulation in the twin-screw extruder to obtain an environmentally friendly lightweight anti-animal-bite polypropylene composite material;

[0143] The temperatures set from the first zone to the ninth zone of the twin-screw extruder are as follows: 175°C, 195°C, 195°C, 205°C, 205°C, 205°C, 205°C, 205°C, and 196°C.

[0144] The density of the finally obtained environmentally friendly lightweight anti-animal-bite polypropylene composite material is 0.96 g / cm 3 , the tensile strength is 32 MPa, the flexural strength is 36 MPa, the flexural modulus is 2140 MPa, and the notched impact strength is 8.2 KJ / m 2 .

[0145] Example 5

[0146] A preparation method of an environmentally friendly lightweight anti-animal-bite polypropylene composite material is as follows:

[0147] (1) Preparation of raw materials:

[0148] Plant fibers: Mass ratio 1:1 of pine wood fibers (manufacturer: Shandong Baoxiang Engineering Materials Co., Ltd.) and bamboo fibers (manufacturer: Sichuan Changsheng New Material Technology Co., Ltd.);

[0149] Sizing agent: Titanate coupling agent (manufacturer: Nanjing Tengchuan Technology Co., Ltd., grade: TC-27);

[0150] PP resin I: Manufacturer: Dushanzi Petrochemical, grade: K9928, melt index of 28 g / 10 min under test conditions of 230°C and 2.16 kg;

[0151] PP resin II: Manufacturer: Zhenhai Refining & Chemical, grade: ZH7555, melt index of 55 g / 10 min under test conditions of 230°C and 2.16 kg;

[0152] Compatibilizer II: Maleic anhydride grafted PE (manufacturer: Arkema, grade: 18341), Vicat softening temperature of maleic anhydride grafted PE is 93°C, grafting rate is 1.2%;

[0153] Antioxidant: A mixture of hindered phenolic antioxidant and phosphite in a mass ratio of 1:2; The hindered phenolic antioxidant is n-octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and the phosphite is bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite;

[0154] Dispersant II: A mixture of maleic anhydride grafted polypropylene wax and oxidized polyethylene wax in a mass ratio of 2:1; The grafting rate of maleic anhydride grafted polypropylene wax is 8%, the weight average molecular weight is 6000, the manufacturer of maleic anhydride grafted polypropylene wax: CERONAS, grade: ADDIMER 840R; The acid value of oxidized polyethylene wax is 15 mg KOH / g, the manufacturer of oxidized polyethylene wax: Honeywell, grade: A-C629;

[0155] Bittering agent: Denatonium benzoate;

[0156] Dispersant I: A mixture of maleic anhydride grafted polypropylene wax and polyethylene wax in a mass ratio of 1:1; The manufacturer of maleic anhydride grafted polypropylene wax: Honeywell, grade: A-C597P; The manufacturer of polyethylene wax: SCG, grade: LP0100P;

[0157] Compatibilizer I: Polypropylene grafted maleic anhydride, manufacturer: DuPont, grade: P613;

[0158] Weathering agent: A mass ratio of 1:1 of 2-(2'-hydroxy 5'-tert-octylphenyl)benzotriazole (UV-329) and 2,2,6,6-tetramethyl-4-piperidine stearate;

[0159] (2) By weight, 90 parts of plant fiber and 3 parts of sizing agent are put into a low-speed mixer with a speed of 70 rpm, mixed at a temperature of 50 °C for 5.5 min, and then discharged to obtain pre-impregnated plant fiber;

[0160] (3) By weight, 100 parts of PP resin II, 4.5 parts of compatibilizer II, 0.35 part of antioxidant, and 1.3 parts of dispersant II are put into a high-speed mixer with a speed of 380 rpm and mixed for 8 min to form a pre-mixed PP resin II;

[0161] (4) The pre-mixed PP resin II is added from the main feeding port of the twin-screw extruder, and the pre-impregnated plant fiber is added from the side feeding port of the twin-screw extruder, and melt extrusion granulation is carried out in the twin-screw extruder to obtain plant fiber masterbatch;

[0162] The temperatures of the twin-screw extruder from the first zone to the ninth zone are set as 178 °C, 198 °C, 198 °C, 198 °C, 198 °C, 198 °C, 198 °C, 198 °C, and 188 °C in sequence;

[0163] (5) By weight, 100 parts of PP resin I, 70 parts of plant fiber masterbatch, 0.9 part of bittering agent, 0.35 part of antioxidant, 0.5 part of dispersant I, 5 parts of compatibilizer I, and 0.3 part of weathering agent are mixed evenly in a high-speed mixer with a speed of 450 rpm for 6 min to form a pre-mixed PP resin I;

[0164] (6) The pre-mixed PP resin I is added from the main feeding port of the twin-screw extruder, and melt extrusion granulation is carried out in the twin-screw extruder to obtain an environmentally friendly lightweight animal-bite-proof polypropylene composite material;

[0165] The temperatures of the twin-screw extruder from the first zone to the ninth zone are set as follows: 178 °C, 198 °C, 198 °C, 198 °C, 208 °C, 208 °C, 208 °C, 208 °C, and 198 °C.

[0166] The density of the finally obtained environmentally friendly lightweight animal-bite-proof polypropylene composite material is 0.98 g / cm 3 , the tensile strength is 34 MPa, the flexural strength is 40 MPa, the flexural modulus is 2710 MPa, and the notched impact strength is 6.3 KJ / m 2 .

[0167] Example 6

[0168] A preparation method of an environmentally friendly lightweight animal-bite-proof polypropylene composite material is as follows:

[0169] (1) Preparation of raw materials:

[0170] Plant fiber: Flax short fibers with a mass ratio of 1:1 (manufacturer: Linyi Yuanma Arts & Crafts Co., Ltd.) and wood cellulose fibers (manufacturer: JRS, product number: E140);

[0171] Sizing agent: Silane coupling agent (manufacturer: Shandong Huachen New Materials Co., Ltd., brand: KH560);

[0172] PP resin I: Manufacturer: Zhenhai Petrochemical, brand: MP17, melt index under test conditions of 230°C and 2.16 kg is 17 g / 10 min;

[0173] PP resin II: Manufacturer: South Korea Hyosung, brand: HJ8280, melt index under test conditions of 230°C and 2.16 kg is 80 g / 10 min;

[0174] Compatibilizer II: EVA grafted maleic anhydride (manufacturer: Arkema, brand: T9304), Vicat softening point of EVA grafted maleic anhydride is 43°C, grafting rate is 1.6%;

[0175] Antioxidant: A mixture of hindered phenol antioxidant and phosphite in a mass ratio of 1:2; The hindered phenol antioxidant is a mixture of n-octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and triethylene glycol bis(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate in a mass ratio of 1:1, and the phosphite is a mixture of tris(2,4-di-tert-butylphenyl)phosphite and bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite in a mass ratio of 1:1;

[0176] Dispersant II: A mixture of maleic anhydride grafted polypropylene wax and oxidized polyethylene wax in a mass ratio of 3:1; The grafting rate of maleic anhydride grafted polypropylene wax is 5%, the weight average molecular weight is 3000, manufacturer: Honeywell, brand: A-C596P; The acid value of oxidized polyethylene wax is 16 mg KOH / g; Manufacturer of oxidized polyethylene wax: Honeywell, brand: A-C655;

[0177] Bittering agent: Denatonium benzoate;

[0178] Dispersant I: A mixture of maleic anhydride grafted polypropylene wax and polyethylene wax in a mass ratio of 1:1; Manufacturer of maleic anhydride grafted polypropylene wax: Honeywell, brand: A-C907P, manufacturer of polyethylene wax: Honeywell, brand: AC-6A;

[0179] Compatibilizer I: POE grafted maleic anhydride, manufacturer: DuPont, brand: N216;

[0180] Weathering agent: A mixture of bis(2,2,6,6-tetramethylpiperidin-4-yl) sebacate and 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol in a mass ratio of 1:1;

[0181] (2) By weight, 85 parts of plant fiber and 2.5 parts of sizing agent are put into a low-speed mixer with a speed of 80 rpm, mixed at a temperature of 50 °C for 5 min, and then discharged to obtain pre-impregnated plant fiber;

[0182] (3) By weight, 100 parts of PP resin II, 4 parts of compatibilizer II, 0.45 part of antioxidant, and 1.2 parts of dispersant II are put into a high-speed mixer with a speed of 400 rpm and mixed for 6 min to form a pre-mixed PP resin II;

[0183] (4) The pre-mixed PP resin II is added from the main feeding port of the twin-screw extruder, and the pre-impregnated plant fiber is added from the side feeding port of the twin-screw extruder, and melt extrusion granulation is carried out in the twin-screw extruder to obtain plant fiber masterbatch;

[0184] The temperatures of the twin-screw extruder from the first zone to the ninth zone are set as 180 °C, 200 °C, 200 °C, 200 °C, 200 °C, 200 °C, 200 °C, 200 °C, and 190 °C in sequence;

[0185] (5) By weight, 100 parts of PP resin I, 90 parts of plant fiber masterbatch, 1 part of bittering agent, 0.55 part of antioxidant, 0.35 part of dispersant I, 5.5 parts of compatibilizer I, and 0.5 part of weathering agent are mixed evenly in a high-speed mixer with a speed of 480 rpm for 5 min to form a pre-mixed PP resin I;

[0186] (6) The pre-mixed PP resin I is added from the main feeding port of the twin-screw extruder, and melt extrusion granulation is carried out in the twin-screw extruder to obtain an environment-friendly lightweight polypropylene composite material resistant to animal bites;

[0187] The temperatures of the twin-screw extruder from the first zone to the ninth zone are set as follows: 180 °C, 200 °C, 200 °C, 210 °C, 210 °C, 210 °C, 210 °C, 210 °C, and 200 °C in sequence.

[0188] The density of the finally obtained environment-friendly lightweight polypropylene composite material resistant to animal bites is 0.99 g / cm 3 , the tensile strength is 35 MPa, the flexural strength is 42 MPa, the flexural modulus is 2935 MPa, and the notched impact strength is 4.5 KJ / m 2 .

Claims

1. A preparation method of an environment-friendly lightweight polypropylene composite material resistant to animal bites, characterized in that: Mix PP resin I, plant fiber masterbatch, bittering agent, antioxidant, dispersant I, compatibilizer I and weathering agent evenly, and then carry out melt extrusion granulation to obtain an environmentally friendly lightweight anti-animal-bite polypropylene composite material; By weight, the raw material formula of the environmentally friendly lightweight anti-animal-bite polypropylene composite material is as follows: The plant fiber masterbatch is obtained by adding the PP resin II premix and the pre-infiltrated plant fiber into the main feeding port and the side feeding port of a twin-screw extruder respectively, and carrying out melt extrusion granulation; By weight, the raw material formula of the plant fiber masterbatch is as follows: The PP resin II premix is obtained by mixing PP resin II, compatibilizer II, antioxidant and dispersant II evenly; the compatibilizer II is maleic anhydride grafted PE or EVA grafted maleic anhydride, and the dispersant II is a mixture of maleic anhydride grafted polypropylene wax and oxidized polyethylene wax in a mass ratio of 1-3:1; The pre-infiltrated plant fiber is plant fiber treated with an infiltrant, and the infiltrant is a titanate coupling agent or a silane coupling agent; The density of the environmentally friendly lightweight polypropylene composite material resistant to animal bites is 0.92 - 1.0 g / cm 3 , the tensile strength is 29 - 36 MPa, the flexural strength is 32 - 45 MPa, the flexural modulus is 1750 - 3100 MPa, and the notched impact strength is 3.2 - 10.5 KJ / m 2 .

2. The preparation method of an environmentally friendly lightweight polypropylene composite material resistant to animal bites according to claim 1, characterized in that, The Vicat softening temperature of maleic anhydride grafted PE is 88-97 °C, and the grafting rate is 1.0-1.2%; the Vicat softening point of EVA grafted maleic anhydride is 43-65 °C, and the grafting rate is 1.2-1.6%; the grafting rate of maleic anhydride grafted polypropylene wax is 5-10%, and the weight average molecular weight is 3000-8000; the acid value of oxidized polyethylene wax is 15-25 mg KOH / g.

3. The preparation method of an environmentally friendly lightweight polypropylene composite material for preventing animal bites according to claim 1 or 2, characterized in that, The specific steps are as follows: (1) Put the plant fiber and the infiltrant into a low-speed mixer with a speed of 50-80 r / min, mix at a temperature of 30-50 °C for 5-7 min, and then discharge to obtain pre-infiltrated plant fiber; (2) Put PP resin II, compatibilizer II, antioxidant and dispersant II into a high-speed mixer with a speed of 220-400 r / min and mix for 6-12 min to form a PP resin II premix; (3) Add the PP resin II premix into the main feeding port of the twin-screw extruder, and add the pre-infiltrated plant fiber into the side feeding port of the twin-screw extruder, and carry out melt extrusion granulation in a twin-screw extruder with a processing temperature of 160-200 °C to obtain the plant fiber masterbatch; (4) Mix PP resin I, plant fiber masterbatch, bittering agent, antioxidant, dispersant I, compatibilizer I and weathering agent evenly in a high-speed mixer with a speed of 220-480 r / min for 5-10 min to form a PP resin I premix; (5) Add the PP resin I premix into the main feeding port of the twin-screw extruder, and carry out melt extrusion granulation in a twin-screw extruder with a processing temperature of 160-210 °C to obtain the environmentally friendly lightweight anti-animal-bite polypropylene composite material.

4. The preparation method of an environmentally friendly lightweight polypropylene composite material resistant to animal bites according to claim 1, characterized in that, The melt index of PP resin II under the test conditions of 230 °C and 2.16 kg is 25-120 g / 10 min; The plant fiber is one or more of wood fiber, bamboo fiber, hemp fiber and cellulose fiber.

5. The preparation method of an environmentally friendly lightweight polypropylene composite material resistant to animal bites according to claim 1, characterized in that, The melt index of PP resin I under the test conditions of 230 °C and 2.16 kg is 10-60 g / 10 min; The bittering agent is denatonium benzoate; The dispersant I is a mixture of maleic anhydride grafted polypropylene wax and polyethylene wax in a mass ratio of 1:1; The compatibilizer I is polypropylene grafted maleic anhydride or POE grafted maleic anhydride; The weathering agent is one or more of 2-(2'-hydroxy-5'-tert-octylphenyl) benzotriazole (UV-329), 2,2,6,6-tetramethyl-4-piperidyl stearate, bis(2,2,6,6-tetramethylpiperidyl) sebacate, and 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl) phenol.

6. The preparation method of an environmentally friendly lightweight polypropylene composite material resistant to animal bites according to claim 1, characterized in that, The antioxidant is a mixture of a hindered phenol antioxidant and a phosphite in a mass ratio of 1:2; The hindered phenol antioxidant is one or more of pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), n-octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, and triethylene glycol bis(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate, and the phosphite is one or more of tris(2,4-di-tert-butylphenyl) phosphite and bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite.

7. The preparation method of an environmentally friendly lightweight polypropylene composite material resistant to animal bites according to claim 3, characterized in that, In step (2), the temperatures set for the twin-screw extruder from the first zone to the ninth zone are 160 - 180 °C, 180 - 200 °C, 180 - 200 °C, 190 - 200 °C, 190 - 200 °C, 190 - 200 °C, 190 - 200 °C, 190 - 200 °C, 180 - 190 °C in sequence.

8. The preparation method of an environment-friendly lightweight anti-animal-bite polypropylene composite material according to claim 3, wherein In step (5), the temperatures set for the twin-screw extruder from the first zone to the ninth zone are: 160 - 180 °C, 180 - 200 °C, 180 - 200 °C, 190 - 210 °C, 190 - 210 °C, 190 - 210 °C, 190 - 210 °C, 190 - 210 °C, 190 - 200 °C in sequence.

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