A polypropylene composition containing plant fiber and its preparation method and application

Abstract

The present invention belongs to the field of polymer materials, and specifically discloses a polypropylene composition containing plant fibers, a preparation method thereof and an application thereof. The polypropylene composition containing plant fibers of the present invention comprises the following components by weight: 60-75 parts of polypropylene, 10-35 parts of plant fibers, 1-5 parts of a compatibilizer, 1-4 parts of a phenolic acid compound, and 0-5 parts of an auxiliary agent. The polypropylene composition containing plant fibers of the present invention has a high filling rate of plant fibers and excellent mechanical properties, and the water absorption rate of the material after secondary processing does not increase sharply, but is maintained in a relatively stable range, and has important practical application value.

Description

Technical Field

[0001] The invention belongs to the field of polymer materials, and in particular relates to a polypropylene composition containing plant fibers, a preparation method and an application thereof. Background Art

[0002] With the rapid development of the automobile industry in recent years, lightweight, quality, energy saving, environmental protection, and functionality have become the main goals of the current automobile industry. Polypropylene, as a general engineering plastic, has the characteristics of low price, light weight, solvent resistance, easy recycling, and non-toxicity. It is one of the important lightweight materials for automobiles.

[0003] Combining polypropylene with plant fibers (such as wood fibers, rice husk fibers, hemp fibers, etc.) to form polypropylene composite materials containing plant fibers, this composite material uses the advantages of polypropylene (such as low cost, good processing performance and mechanical properties) and the characteristics of plant fibers (such as light weight, environmental protection, and renewable) to achieve a variety of applications. Among them, it can be used for interior parts such as car seat backs, door panels, and dashboard trims. Because this type of composite material combines the advantages of polypropylene and plant fibers, it can replace traditional plastic materials to some extent to reduce dependence on non-renewable resources and reduce environmental impact.

[0004] For example, the patent document with patent announcement number CN115521534A discloses a polypropylene composition and its preparation method and application, the components of which include: polypropylene resin, p-toluidine, compatibilizer, polyethylene, plant cellulose, antioxidant, and weathering agent. Such polypropylene composition can be processed twice, and the performance of the secondary processing can also be well maintained. However, it is found in specific use that after the secondary processing of conventional polypropylene composite materials containing plant fibers, such composite materials can generally maintain a certain degree of original mechanical properties before use, including tensile and impact properties, but the water absorption rate of the material after the secondary processing will increase sharply, especially when it works for a long time in a relatively humid environment, the water absorption rate of the composite materials after the secondary processing will be significantly increased, thereby affecting the mechanical properties of the actual material, which is not conducive to the actual use and recycling of the material. Summary of the invention

[0005] The invention provides a polypropylene composition containing plant fibers, a preparation method and application thereof, so as to solve the problem that the water absorption rate of the polypropylene composition containing plant fibers will be sharply increased after secondary processing.

[0006] To achieve the above purpose, the following technical solutions are specifically included:

[0007] A polypropylene composition containing plant fibers comprises the following components in parts by weight: 60-75 parts of polypropylene, 10-35 parts of plant fibers, 1-5 parts of a compatibilizer, 1-4 parts of a phenolic acid compound, and 0-5 parts of an auxiliary agent.

[0008] Phenolic acid compounds are a class of organic compounds with phenolic groups and carboxylic acid groups. Their molecular structures usually contain one or more benzene rings, and one or more carboxylic acid groups are attached to the benzene rings. The present invention adds this special phenolic acid compound auxiliary agent to the polypropylene composition containing plant fibers, which has the following characteristics: (1) The phenolic acid compound has an active functional group and can react with the hydroxyl group in the plant fiber to form a cross-linked structure. This cross-linking can enhance the strength and temperature resistance of the material; (2) After secondary processing, the material is easily affected by oxidation, resulting in an increase in water absorption. The present invention introduces phenolic acid compounds, which have excellent antioxidant properties and can effectively delay the aging process of the material and effectively slow down the aging rate of the material, thereby reducing the increase in water absorption after secondary processing; (3) The phenolic acid compound can form a stable chemical bond in the material, enhance the molecular structure and stability of the material, and at the same time, the phenolic acid compound has good water resistance and moisture resistance, can effectively block moisture from entering the material, reduce the increase in water absorption of the material, and help improve the long-term stability of the polypropylene composition containing plant fibers, and reduce the performance degradation and water absorption increase of the material after secondary processing. (4) In addition, the addition of the phenolic acid compounds of the present invention also has a positive effect on the process performance of the polypropylene composition containing plant fibers. The small molecular structure of the phenolic acid compounds can improve the processing stability and fluidity of the materials and reduce the problems of hygroscopic deformation and poor fluidity of the materials during processing, which is of great significance for achieving efficient production and reducing manufacturing costs.

[0009] The weight of the polypropylene of the present invention is between 60 and 75 parts, and the weight of the plant fiber is between 10 and 35 parts. Such a ratio selection can give full play to the advantages of polypropylene and plant fiber and achieve a balance of material properties. Within the above content range, by increasing the content of plant fiber, the strength, rigidity and heat resistance of the composition can be improved, while reducing the amount of polypropylene used, thereby achieving more effective utilization of sustainable resources.

[0010] The weight parts of polypropylene can be 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 63, 74, 75, etc., as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the said range.

[0011] The weight percentage of plant fiber can be 12.5, 15, 17.5, 20, 22.5, 25, 27.5, 30, 32.5, 35, etc., as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the said range.

[0012] As a preferred embodiment of the present invention, the polypropylene composition containing plant fibers comprises the following components in parts by weight: 62-70 parts of polypropylene, 20-30 parts of plant fibers, 2-3.5 parts of compatibilizer, 1.5-2.5 parts of phenolic acid compounds, and 0.2-1 part of additives.

[0013] As a preferred embodiment of the present invention, the phenolic acid compound includes at least one of 6-hydroxy-2-naphthoic acid, 1-naphthol-2-carboxylic acid, p-hydroxybenzoic acid, 2,5-dihydroxybenzoic acid, and cinnamphenolic acid.

[0014] The phenolic acid compounds mentioned above can achieve better bonding between the fibers and the matrix in the polypropylene composition by reacting with hydroxyl groups in materials such as plant fibers, thereby improving the strength and durability of the material.

[0015] Further preferred is p-hydroxybenzoic acid, which has excellent antioxidant properties and can more effectively inhibit the oxidation reaction of oxygen on materials.

[0016] As a preferred embodiment of the present invention, the mass ratio of the phenolic acid compounds to the plant fibers is 1:6-30.

[0017] As a further preferred embodiment of the present invention, the mass ratio of the phenolic acid compounds to the plant fibers is 1:10-20.

[0018] As a preferred embodiment of the present invention, the plant fiber includes one or more of unmodified plant fiber and surface-modified plant fiber, and the plant fiber includes at least one of bamboo fiber, flax fiber, pine fiber, palm fiber, cotton stalk fiber, wheat straw fiber, rice straw fiber and reed stalk fiber.

[0019] As a further preferred embodiment of the present invention, the plant fiber includes flax fiber and bamboo fiber, and the mass ratio of the flax fiber to the bamboo fiber is 1:(0.5-4).

[0020] The mass ratio of the flax fiber to the bamboo fiber can be (1:0.5), (1:1), (1:1.5), (1:2), (1:2.5), (1:3), (1:3.5), (1:4), (1:4.5), (1:5), etc., as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively enumerates the specific point values ​​included in the said range.

[0021] As a further preferred embodiment of the present invention, the mass ratio of the flax fiber to the bamboo fiber is 1:(1-2).

[0022] The plant fibers added to the polypropylene composition of the present invention have good hygroscopicity and humidity regulating properties. They can absorb and release moisture in the air, which helps to regulate the humidity and temperature of the material, and also helps to improve the comfort and stability of the material. Moreover, plant fibers such as flax fibers, bamboo fibers and pine fibers have good plasticity and processability during processing, and they can be well compatible with base materials such as polypropylene.

[0023] By mixing flax fiber and bamboo fiber in the above specific weight ratio, the mechanical properties of the polypropylene composition can be optimized and the strength, stiffness and toughness of the material can be balanced.

[0024] As a preferred embodiment of the present invention, the surface modification includes modifying the plant fiber with a surfactant, and the surfactant includes at least one of fatty alcohol polyoxyethylene ether, fatty alcohol polyether sulfate, and polycarboxylate surfactants.

[0025] The general formula of the fatty alcohol polyoxyethylene ether is RO(CH2CH2O)nH, where R is generally a saturated or unsaturated C12-C18 hydrocarbon group, which can be a straight-chain hydrocarbon group or a branched hydrocarbon group, and n is the addition number of ethylene oxide, n≥2, such as dodecaned / tetradecane fatty alcohol polyoxyethylene ether (5EO), dodecaned / tetradecane fatty alcohol polyoxyethylene ether (7EO), dodecaned / tetradecane fatty alcohol polyoxyethylene ether (9EO), etc.

[0026] The general formula of the fatty alcohol polyether sulfate is RO(CH2CH2O)nSO3M, R is a saturated or unsaturated C12-C14 hydrocarbon group, which can be a straight-chain hydrocarbon group or a branched hydrocarbon group, n is the addition number of ethylene oxide, n≥2, and M is a cation, including sodium ions, ammonium ions, etc., such as being selected from any one or more of dodecaned / tetradecanoic alcohol polyoxyethylene ether (2EO) sodium sulfate, dodecaned / tetradecanoic alcohol polyoxyethylene ether (3EO) sodium sulfate, dodecaned / tetradecanoic alcohol polyoxyethylene ether (5EO) sodium sulfate, dodecaned / tetradecanoic alcohol polyoxyethylene ether (7EO) sodium sulfate and dodecaned / tetradecanoic alcohol polyoxyethylene ether (9EO) sodium sulfate, alkyl alcohol polyoxyethylene (1-4) ether ammonium sulfate (DNS-360), etc.

[0027] As a preferred embodiment of the present invention, the polycarboxylates include at least one of polyacrylamide carboxylates and polymethacrylates, and the polycarboxylates include but are not limited to sodium polyacrylamide carboxylate, potassium polyacrylamide carboxylate, sodium polymethacrylate and potassium polymethacrylate.

[0028] As a preferred embodiment of the present invention, in the surfactant-modified plant fiber, the surfactant added in the process of using the surfactant to modify the plant fiber accounts for 0.1-4% of the mass of the plant fiber.

[0029] As a preferred embodiment of the present invention, the preparation method of the surfactant-modified plant fiber comprises the following steps:

[0030] (1) immersing the plant fiber in a cleaning agent to clean and remove impurities, then washing with water and drying;

[0031] (2) adding the plant fiber dried in step (1) into a surfactant solution to carry out a surface modification reaction, and drying to obtain the surfactant-modified plant fiber.

[0032] The amount of surfactant used can be any amount commonly used in the art, and preferably the added surfactant accounts for 0.1-4% of the mass of the plant fiber.

[0033] As a further preferred embodiment of the present invention, the cleaning agent in step (1) is a sodium hexametaphosphate aqueous solution, and the mass percentage of sodium hexametaphosphate in the sodium hexametaphosphate aqueous solution is 4-8%.

[0034] As a further preferred embodiment of the present invention, the mass ratio of the plant fiber to the cleaning agent in step (1) is 1:15-30.

[0035] As a further preferred embodiment of the present invention, the time for cleaning and removing impurities in step (1) is 5-30 minutes.

[0036] As a further preferred embodiment of the present invention, the drying temperature in steps (1) and (2) is 80-120°C.

[0037] As a further preferred embodiment of the present invention, the temperature of the surface modification reaction in step (2) is 70-90° C., and the time of the surface modification reaction is 10-20 min.

[0038] As a further preferred embodiment of the present invention, the mass ratio of the dried plant fiber to the surfactant solution in step (2) is 1:15-40.

[0039] Plant fibers usually have high hydrophilicity, while hydrophobic matrix materials such as polypropylene have low hydrophilicity. The present invention uses surfactant active pretreatment to allow the surfactant to be fully chemically adsorbed on the surface of the plant fiber, which can improve the compatibility between the plant fiber and polypropylene, increase the adhesion and interaction between them, and thus achieve better fiber reinforcement effect.

[0040] 2,5-Dihydroxybenzoic acid is a preferred embodiment of the present invention. The compatibilizer includes maleic anhydride grafted product. Further, the compatibilizer can be selected from maleic anhydride grafted polyolefin, and further can be selected from at least one of maleic anhydride grafted polyethylene and maleic anhydride grafted polypropylene.

[0041] Polypropylene and plant fibers have large differences in chemical properties and hydrophilicity, so the compatibility between them is limited. The above-mentioned compatibilizer can be introduced to help improve the compatibility between polypropylene and plant fibers, enhance the adhesion and interaction between them, which helps to improve the comprehensive performance of the composition and ensure its stability and consistency during the secondary processing. Therefore, the polypropylene composition provided by the present invention has a high plant fiber filling rate and excellent mechanical properties, and the water absorption rate of the material after secondary processing will not increase sharply, and it is maintained in a relatively stable range, which has important practical application value.

[0042] Maleic anhydride grafted polyethylene is a hydrophilic and hydrophobic amphiphilic molecule with good compatibility. By introducing it into the polypropylene composition as a compatibilizer, the compatibility between polypropylene and plant fibers can be more significantly increased, the mixing and interaction between the two can be promoted, and the impact resistance of the material can be balanced. Because maleic anhydride grafted polyethylene is more fluid than maleic anhydride grafted polypropylene, the improvement in fluidity helps to more evenly disperse stress under impact loading and slow down crack propagation, so the compatibilizer is further preferably maleic anhydride grafted polyethylene.

[0043] As a preferred embodiment of the present invention, the polypropylene includes homopolypropylene, and the melt flow rate of the polypropylene is 2 to 6 g / 10 min under the conditions of 220° C. and 10 kg, and the test standard is ISO1133-2005.

[0044] As a preferred embodiment of the present invention, the auxiliary agent includes at least one of an antioxidant, a UV stabilizer, a toughening agent, a flame retardant, and a lubricant. Further, the auxiliary agent includes 0.2-0.4 parts by weight of a phenolic primary antioxidant, 0.2-0.4 parts by weight of a phosphite secondary antioxidant, and 0.4-0.8 parts by weight of a UV stabilizer.

[0045] In the polypropylene composition of the present invention, the mass content of the polypropylene resin is not less than 55%.

[0046] The present invention also provides a method for preparing the polypropylene composition containing plant fibers, comprising the following steps: mixing polypropylene and a compatibilizer to obtain a first premix; mixing plant fibers and / or surfactant-modified plant fibers, phenolic acid compounds and additives to obtain a second premix; and uniformly mixing the first premix and the second premix, performing melt blending and extrusion granulation to obtain the polypropylene composition.

[0047] As a preferred embodiment of the present invention, the extrusion temperature is 200°C-240°C.

[0048] The present invention also provides an application of the polypropylene composition containing plant fibers in the field of automobile interior decoration, such as automobile seat back panels, door panels, instrument panel trim panels and other parts.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] (1) The present invention achieves a polypropylene composition having a high plant fiber filling rate and excellent mechanical properties by compounding multiple components such as polypropylene, plant fiber, compatibilizer, phenolic acid compound, etc. At the same time, the water absorption rate of the material after secondary processing will not increase sharply, but remain in a relatively stable range, which has important practical application value.

[0051] (2) The method for preparing the polypropylene composition containing plant fibers of the present invention is simple and easy to implement, and is suitable for mass production. DETAILED DESCRIPTION

[0052] In order to better illustrate the purpose, technical scheme and advantages of the present invention, the present invention will be further described below through specific examples. The test methods used in the examples and / or comparative examples are conventional methods unless otherwise specified; the materials, reagents, etc. used can be obtained from commercial channels unless otherwise specified.

[0053] The following Table 1 lists the sources and types of raw materials used in the examples and comparative examples of the present application. Unless otherwise specified, the reagents were all commercially available.

[0054] Table 1 - Source and type of raw materials in the examples and comparative examples

[0055]

[0056]

[0057] Examples 1-14 and Comparative Examples 1-3

[0058] A polypropylene composition comprises polypropylene, plant fiber, phenolic acid compound, compatibilizer and other additives, wherein the content of each component is as shown in Tables 2 and 3, and the preparation method comprises the following steps:

[0059] (1) mixing polypropylene and a compatibilizer to obtain a first premix;

[0060] (2) combining plant fiber, phenolic acid compound and auxiliary agent to obtain a second premix;

[0061] (3) Then, the first premix and the second premix are uniformly mixed and added into a twin-screw extruder, and after melt blending and extrusion granulation, the extrusion temperature of the twin-screw extruder is 200°C to 240°C, the temperature of the first section is 200°C, the temperature of the 2nd to 4th sections is 240°C, the temperature of the 5th to 8th sections is 220°C, and the temperature of the 9th section of the die head is 240°C, to obtain the polypropylene composition.

[0062] Table 2 - Content of each component in Examples 1-12

[0063]

[0064] Table 3 Content of each component in Examples 13-14 and Comparative Examples 1-3

[0065]

[0066]

[0067] Embodiment 15

[0068] A polypropylene composition, wherein each step, reagents used in each step, and process parameters in the preparation method are the same as those in Example 1, except that the plant fiber is subjected to active pretreatment, and the active pretreatment specifically comprises the following steps:

[0069] (1) immersing the plant fiber in a 5% by weight sodium hexametaphosphate aqueous solution at a mass ratio of 1:20 to clean and remove impurities for 15 minutes, then washing with water, and drying at 100° C.;

[0070] (2) The dried plant fibers are added to an aqueous solution of a fatty alcohol polyoxyethylene ether AEO-9 surfactant at a mass ratio of 1:20, and the mixture is placed in a water bath at 80° C. for 10 minutes to allow the surfactant to be fully adsorbed on the surface of the plant fibers, thereby obtaining surfactant-modified plant fibers, wherein the mass of the surfactant used accounts for 1.5% of the mass of the plant fibers.

[0071] Example 16

[0072] A polypropylene composition, wherein each step in the preparation method and the reagents and process parameters used in each step are the same as those in Example 15, except that the surfactant is alkyl alcohol polyoxyethylene (1-4) ether ammonium sulfate DNS-360.

[0073] Embodiment 17

[0074] A polypropylene composition, wherein each step in the preparation method and the reagents and process parameters used in each step are the same as those in Example 15, except that the surfactant is sodium polyacrylamide carboxylate 5040.

[0075] Embodiment 18

[0076] A polypropylene composition, wherein the process parameters of each step in the preparation method are the same as those in Example 16, except that the reagents used in each step are the same as those in Example 9.

[0077] Performance testing

[0078] 1. Tensile strength: tested in accordance with ISO 527-2-2016, with a tensile speed of 50 mm / min;

[0079] 2. Simply supported beam notched impact strength: tested in accordance with ISO179-2010 standard, specimen size is 80=10=4mm, A-type notch;

[0080] 3. Water absorption: Determined according to ISO 62-2008 Plastics - Water absorption;

[0081] 4. The material performance test items and methods after secondary processing are the same as above.

[0082] Among them, the secondary processing process is: after the polypropylene composition is injection molded into a seat back panel, it is crushed again and put into a twin-screw extruder for melt blending and secondary extrusion granulation, and the parameters are the same as the first processing.

[0083] The test results are shown in Table 4.

[0084] Table 4 - Performance test results of Examples 1-18 and Comparative Examples 1-3

[0085]

[0086]

[0087] As shown in Table 4, the tensile strength of the polypropylene composite prepared by the present invention is 42-48 MPa, and the Izod notched impact strength is 13.5-18 (KJ / m 2 ), the water absorption rate is 0.7-1.1%. After secondary processing, the tensile strength of the polypropylene combination is still maintained at 42-48MPa, and the cantilever beam notch impact strength is still maintained at 13.5-18 (KJ / m 2 ), the water absorption rate remains at 0.7-1.1%.

[0088] Combining the performance test results of Example 1 and Comparative Examples 1 and 3 in Table 4, it can be seen that the present invention uses an appropriate amount of phenolic acid compounds as special linkers to form stable chemical bonds in the material, enhance the molecular structure and stability of the material, and reduce the performance degradation and water absorption increase of the material after secondary processing; however, if the phenolic acid compounds are too little, the effect is not significant and basically has no effect in the composition; if the phenolic acid compounds are too much, they are polyhydroxy substances themselves and will absorb water instead, resulting in an increase in water absorption.

[0089] From the comparison of the data of Examples 1 and 6, it can be seen that the phenolic acid compounds can improve the performance and stability of the composition, and further optimize the mechanical properties and water absorption performance of the polypropylene composition. 2,5-Dihydroxybenzoic acid can enhance the combination of polypropylene and plant fibers at high temperature, thereby improving the performance and stability of the composition, and further optimizing the mechanical properties and water absorption performance of the polypropylene composition.

[0090] From the comparison of the data of Examples 1-3 and 7-9, it can be seen that when the plant fiber is a compound of flax fiber and bamboo fiber, the mechanical properties and water absorption properties of the polypropylene composition can be further regulated, and the weight ratio of flax fiber to bamboo fiber is preferably 1:(1-2).

[0091] It can be seen from Examples 15-18 that when the plant fiber is subjected to active pretreatment, the mechanical properties are better and the water absorption rate after secondary processing is lower, which is a better optimization scheme. In the active pretreatment, in addition to the fatty alcohol polyoxyethylene ether in the embodiment, the surfactants, fatty alcohol polyether sulfates and polycarboxylates also meet the pretreatment requirements and achieve the same technical effect.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A polypropylene composition containing plant fibers, characterized in that: The invention comprises the following components in parts by weight: 60-75 parts of polypropylene, 10-35 parts of plant fiber, 1-5 parts of compatibilizer, 1-4 parts of phenolic acid compound and 0-5 parts of auxiliary agent; the auxiliary agent is at least one of an antioxidant, an ultraviolet stabilizer, a toughening agent, a flame retardant and a lubricant.

2. The polypropylene composition containing plant fibers according to claim 1, characterized in that The plant fiber includes surfactant-modified plant fiber, and the plant fiber includes at least one of bamboo fiber, flax fiber, pine fiber, palm fiber, cotton stalk fiber, wheat straw fiber, rice straw fiber and reed stalk fiber.

3. The polypropylene composition containing plant fibers according to claim 2, characterized in that: The plant fibers include flax fibers and bamboo fibers, and the mass ratio of the flax fibers to the bamboo fibers is 1:(0.5-4).

4. The polypropylene composition containing plant fibers according to claim 2, characterized in that: The surfactant in the surfactant-modified plant fiber includes at least one of fatty alcohol polyoxyethylene ether, fatty alcohol polyether sulfate, and polycarboxylate surfactants.

5. The polypropylene composition containing plant fibers according to claim 2, characterized in that: In the surfactant-modified plant fiber, the surfactant added in the process of using the surfactant to modify the plant fiber accounts for 0.1-4% of the mass of the plant fiber.

6. The polypropylene composition containing plant fibers according to claim 1, characterized in that: The phenolic acid compound includes at least one of 6-hydroxy-2-naphthoic acid, 1-naphthol-2-carboxylic acid, p-hydroxybenzoic acid, 2,5-dihydroxybenzoic acid and cinnamphenolic acid.

7. The polypropylene composition containing plant fibers according to claim 1, characterized in that: The compatibilizer includes at least one of maleic anhydride grafted polyethylene and maleic anhydride grafted polypropylene.

8. The polypropylene composition containing plant fibers according to claim 1, characterized in that: Include at least one of the following: The melt flow rate of the polypropylene is 2-6 g / 10 min at 220° C. and 10 kg, and the test standard is ISO1133-2005; The auxiliary agent comprises 0.2-0.4 parts by weight of a phenolic primary antioxidant, 0.2-0.4 parts by weight of a phosphite secondary antioxidant and 0.4-0.8 parts by weight of an ultraviolet stabilizer.

9. A method for preparing a polypropylene composition containing plant fibers according to any one of claims 1 to 8, characterized in that: The steps include: The polypropylene and the compatibilizer are mixed to obtain a first premix; the plant fiber and / or the surfactant-modified plant fiber, the phenolic acid compound and the auxiliary agent are mixed to obtain a second premix; the first premix and the second premix are mixed evenly, melt-blended and extruded to granulate to obtain the polypropylene composition.

10. Use of the polypropylene composition containing plant fibers according to any one of claims 1 to 8 in the field of automobile interior decoration.

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