Polypropylene composition as well as preparation method and application thereof

Abstract

The invention relates to a polypropylene composition as well as a preparation method and application thereof. The polypropylene composition is prepared from 54 to 92 parts of polypropylene resin, 0.01 to 31 parts of filler, 0.01 to 16 parts of elastomer and 0.4 to 2.3 parts of sodium bicarbonate, the sodium bicarbonate is added in the form of a sodium bicarbonate solution, and the mass concentration of the sodium bicarbonate in the sodium bicarbonate solution is 2-15%. According to the invention, carbon dioxide is introduced into the material by utilizing the characteristic that sodium bicarbonate is heated to decompose and release carbon dioxide, and the characteristics of extremely high saturated vapor pressure and excellent dissolving capacity of carbon dioxide are combined with a steam stripping devolatilization technology, so that volatile odor substances are efficiently removed from the product, the odor grade of the product is reduced, and the product quality is improved. And meanwhile, the glossiness of the product can be reduced, and the application requirements in automobile interiors are met.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a polypropylene composition and a preparation method and application thereof. Background Art

[0002] Polypropylene (PP) is a polymer compound obtained by polymerization of propylene. Due to its abundant raw materials and relatively simple synthesis process, compared with other general thermoplastics, PP has a relatively low density, low price, and outstanding stress resistance, cracking resistance and wear resistance. It is the fastest growing variety among general thermoplastics, and its position in economic construction and people's lives is becoming increasingly important. It has become the fastest growing variety in plastics and is widely used in various fields such as automobiles, home appliances, daily necessities and packaging.

[0003] The car interior environment is related to the car brand image and the first impression of consumers. Car OEMs need to improve quality as a standard response and sales selling point. In recent years, the demand for car interior odor by various car companies has continued to increase. For example, the odor requirements for car interior polypropylene materials such as door panels have gradually increased from level 4.2 to below level 3.5 in the past decade (the evaluation standard refers to Volkswagen PV3900).

[0004] The odor of polypropylene materials comes from complex sources. The catalyst and solvent residues used in the polymerization of the base resin, small molecules that are not fully polymerized, various additives used in the processing and modification process, and processing degradation can all lead to an increase in the odor of PP. At present, the main way to reduce the odor of polypropylene materials is to bake the material after extrusion, and to add water and other stripping agents for stripping and devolatilization during the extrusion process. For example, CN104311999A discloses a low-odor polypropylene material and a preparation method thereof, comprising the following components: 100 parts of polypropylene recycled material; 10-40 parts of talcum powder; 5-15 parts of water-absorbing resin; 3-8 parts of water; 1-5 parts of reactive castor oil; 2-5 parts of heat stabilizer; 2-5 parts of composite antioxidant; the water in the water-absorbing resin and the additional water added are vaporized during the melting process to bring out the small molecular substances that can produce odor in the polypropylene material, thereby preparing a polypropylene material with low odor; in addition, the active functional groups of the reactive castor oil chelate the amine, sulfur, and thiol odor substances in the material to form a stable new compound to improve the odor of the material; and the synergistic effect of each component optimizes the mechanical properties of the obtained polypropylene material. However, the use of stripping agents other than water has certain defects in terms of safety and cost, and can no longer meet the increasingly stringent requirements of the current industry for odor.

[0005] Therefore, there is an urgent need in the art to develop a low-odor polypropylene composition that has a simple, efficient, safe and inexpensive preparation method. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a polypropylene composition, which includes a polypropylene resin, a filler, an elastomer and a sodium bicarbonate solution. Sodium bicarbonate is used as a carrier, and its property of decomposing and releasing carbon dioxide is utilized to introduce carbon dioxide into production; the steam stripping and devolatilization technology is combined with the extremely high saturated vapor pressure and excellent solubility of carbon dioxide to realize a rapid dissolution-volatilization process in production, thereby efficiently removing volatile odor substances in the product and reducing the odor level of the product. The method is simple, safe and highly universal.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a polypropylene composition, which comprises, by weight, 54-92 parts of a polypropylene resin, 0.01-31 parts of a filler, 0.01-16 parts of an elastomer, and 0.4-2.3 parts of sodium bicarbonate; the sodium bicarbonate solution is added in the form of a sodium bicarbonate solution, and the mass concentration of sodium bicarbonate in the sodium bicarbonate is 2-15%.

[0009] The polypropylene composition provided by the present invention comprises sodium bicarbonate, which is heated and decomposed during production to release carbon dioxide. Carbon dioxide has the characteristics of high saturated vapor pressure and high solubility. By using the sodium bicarbonate as a stripping agent and through the stripping and devolatilization technology, carbon dioxide and odor substances in the polymer collide and dissolve during the extrusion process, and efficiently nucleate, grow, break, and enter the gas phase, so that volatiles are removed from the polymer melt.

[0010] The present invention uses sodium bicarbonate as a carbon dioxide carrier and introduces it into extrusion production. On the one hand, the raw materials are cheap and easy to obtain, which reduces the production cost and solves the problem that the carbon dioxide fluid is difficult to add to the extruder. On the other hand, sodium bicarbonate is different from calcium bicarbonate or magnesium bicarbonate. Calcium bicarbonate or magnesium bicarbonate is not stable enough and often decomposes itself before being added to the polymer melt. Both are prepared as aqueous solutions. After hydrolysis, insoluble solid precipitation similar to scale will be generated, which will quickly block the equipment pipeline. Sodium bicarbonate is relatively stable in nature and decomposes at a suitable temperature to produce carbon dioxide. It has a better effect of removing volatile odor substances. The overall process is efficient and safe, and the operation and maintenance costs are low. In addition, the applicant has found that adding a specific concentration of sodium bicarbonate can also significantly reduce the glossiness of the appearance of the product.

[0011] The polypropylene resin is 54-92 parts, for example, can be 55 parts, 58 parts, 60 parts, 62 parts, 65 parts, 68 parts, 70 parts, 72 parts, 75 parts, 78 parts, 80 parts, 85 parts, 88 parts or 90 parts, as well as specific point values ​​between the above points. 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.

[0012] The filler is 0.01-31 parts, for example, it can be 1 part, 2 parts, 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 28 parts or 30 parts, 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.

[0013] The elastomer is 0.01-16 parts, for example, it can be 0.05 parts, 0.1 parts, 0.2 parts, 0.5 parts, 1 parts, 2 parts, 5 parts, 8 parts, 10 parts, 12 parts or 15 parts, 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.

[0014] In the present invention, the sodium bicarbonate is 0.4 to 2.3 parts, for example, 0.4, 0.42, 0.45, 0.48, 0.5, 0.52, 0.55, 0.58, 0.6, 0.62, 0.65, 0.68, 0.7, 0.72, 0.75, 0.78, 0.8, 0.82, 0.85, 0.88, 0.9, 0.92, 0.95, 0.98 , 1 part, 1.1 parts, 1.15 parts, 1.2 parts, 1.25 parts, 1.3 parts, 1.35 parts, 1.4 parts, 1.45 parts, 1.5 parts, 1.55 parts, 1.6 parts, 1.65 parts, 1.7 parts, 1.8 parts, 1.9 parts, 2 parts, 2.1 parts, 2.2 parts or 2.3 parts, and 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 range; preferably 0.8 to 1.6 parts.

[0015] The mass concentration of sodium bicarbonate in the sodium bicarbonate solution is 2-15%, for example, it can be 3%, 4%, 5%, 6%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 11.8%, 12%, 12.5%, 12.8%, 13%, 13.5%, 13.8%, 14%, 14.2%, 14.5%, 14.8%, 15%, and specific values ​​between the above points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively enumerates the specific points included in the range; more preferably, it is 7.5-13.5%.

[0016] In the present invention, the sodium bicarbonate solution is 3.3-15.2 parts by weight, for example, 3.3 parts, 3.5 parts, 3.8 parts, 4 parts, 4.2 parts, 4.5 parts, 4.8 parts, 5 parts, 5.2 parts, 5.5 parts, 5.8 parts, 6 parts, 6.2 parts, 6.5 parts, 6.8 parts, 7 parts, 7.2 parts, 7.5 parts, 7.8 parts, 8 parts, 8.2 parts, 8.5 parts, 8.8 parts, 9 parts, 9.2 parts, 9.5 parts, 9.8 parts, 10 parts, 10. 2 parts, 10.5 parts, 10.8 parts, 11 parts, 11.2 parts, 11.5 parts, 11.8 parts, 12 parts, 12.2 parts, 12.5 parts, 12.8 parts, 13 parts, 13.2 parts, 13.5 parts, 13.8 parts, 14 parts, 14.2 parts, 14.5 parts, 14.8 parts, 15 parts, and specific point values ​​between the above points. 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; more preferably 6 to 13 parts.

[0017] In the present invention, if the sodium bicarbonate content is low or the concentration of the sodium bicarbonate solution is too low, the odor improvement is not obvious and the product has high gloss. If the content is too high or the concentration is too high, the odor substances cannot be discharged smoothly due to excessive gas release or too fast speed, which also causes the odor to deteriorate and the gloss to increase.

[0018] In the present invention, the "parts" and "parts by weight" involved in the non-solution components are calculated based on the solid content and do not include the solvent, dispersant, medium, etc.

[0019] Preferably, the mass ratio of the polypropylene resin to the sodium bicarbonate is (50-90):1, for example, it can be 50:1, 52:1, 55:1, 58:1, 60:1, 62:1, 65:1, 68:1, 70:1, 72:1, 75:1, 78:1, 80:1, 82:1, 85:1 or 88:1, 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 range.

[0020] As a preferred technical solution of the present invention, when the mass ratio of the polypropylene resin to sodium bicarbonate is (50-90):1, the low-odor polypropylene prepared from the polypropylene composition has a lower odor level, which is more in line with the development direction of the automotive industry for interior materials.

[0021] Preferably, the mass ratio of the sodium bicarbonate to the filler is 1:(4-20), for example, it can be 1:4, 1:5, 1:6, 1:8, 1:10, 1:12, 1:14, 1:15, 1:16 or 1:18, 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 range.

[0022] In the present invention, different filler contents are used according to different product requirements, but fillers have a negative impact on odor, that is, as the filler ratio increases, the product odor level increases accordingly. Therefore, the present invention optimizes the filler addition ratio to obtain a polypropylene product with a lower odor level, which is suitable for application in automotive interiors.

[0023] Preferably, the solvent of the sodium bicarbonate solution comprises water.

[0024] Preferably, the polypropylene resin is copolymer polypropylene.

[0025] Preferably, the copolymerized polypropylene comprises a propylene-ethylene copolymer.

[0026] Preferably, the molar content of propylene-based structural units in the propylene-ethylene copolymer is 85-95%, for example, it can be 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93% or 94%, 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 range.

[0027] Preferably, the melt index of the polypropylene resin is 30-100 g / 10min, for example, it can be 35 g / 10min, 40 g / 10min, 45 g / 10min, 50 g / 10min, 55 g / 10min, 60 g / 10min, 65 g / 10min, 70 g / 10min, 75 g / 10min, 80 g / 10min, 85 g / 10min, 90 g / 10min or 95 g / 10min, 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 range.

[0028] The melt index of the present invention is measured at 230° C. and 2.16 kg weight with reference to ISO 1133-1:2022 standard.

[0029] Preferably, the filler includes any one of talc, mica or wollastonite or a combination of at least two thereof, and more preferably talc.

[0030] Preferably, the particle size of the talc is 1000-3000 mesh, for example, 1200 mesh, 1500 mesh, 1800 mesh, 2000 mesh, 2200 mesh, 2500 mesh or 2800 mesh, 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 range.

[0031] Preferably, the elastomer comprises a polyolefin elastomer.

[0032] Preferably, the polyolefin elastomer comprises ethylene-butene copolymer and / or ethylene-octene copolymer.

[0033] Preferably, the polypropylene composition further comprises 0.2-1 parts of antioxidants, for example, 0.25 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts or 0.9 parts, and specific values ​​between the above points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively enumerates the specific points included in the range, and 0.4-0.6 parts is further preferred.

[0034] Preferably, the antioxidant comprises a combination of a primary antioxidant and a secondary antioxidant.

[0035] Preferably, the mass ratio of the primary antioxidant to the secondary antioxidant is 1:(0.8-1.2), for example, it can be 1:0.85, 1:0.9, 1:0.95, 1:1, 1:1.05, 1:1.1 or 1:1.15, as well as specific values ​​between the above values. Due to space limitations and for the sake of simplicity, the present invention will no longer exhaustively list the specific values ​​included in the range. Preferably, the primary antioxidant includes a hindered phenolic antioxidant.

[0036] Preferably, the hindered phenol antioxidant includes any one of antioxidant 1010, antioxidant 1076, antioxidant 330 or antioxidant 1790, or a combination of at least two thereof.

[0037] Preferably, the secondary antioxidant comprises a phosphite antioxidant.

[0038] Preferably, the phosphite antioxidant includes antioxidant 168 and / or antioxidant 627A.

[0039] In a second aspect, the present invention provides a low-odor polypropylene, wherein the low-odor polypropylene is prepared from the polypropylene composition described in the first aspect.

[0040] In a third aspect, the present invention provides a method for preparing the low-odor polypropylene as described in the second aspect, characterized in that the preparation method comprises the following steps:

[0041] Sodium bicarbonate is dissolved in water to obtain a sodium bicarbonate solution; the sodium bicarbonate solution is mixed with a polypropylene resin, a filler, an elastomer, an optional primary antioxidant, and an optional secondary antioxidant, and extruded to obtain the low-odor polypropylene.

[0042] The low-odor polypropylene preparation method provided by the present invention utilizes the characteristic that sodium bicarbonate is easily soluble in water, and adds sodium bicarbonate in the form of an aqueous solution instead of sodium bicarbonate powder, thereby effectively ensuring good dispersion of the sodium bicarbonate, facilitating the contact of carbon dioxide generated by its decomposition with odor substances in the polymer, and further removing volatiles from the polymer melt.

[0043] Preferably, the mass concentration of sodium bicarbonate in the sodium bicarbonate solution is 2-15%, for example, it can be 3%, 4%, 5%, 6%, 8%, 10%, 12% or 14%, and 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 range, and it is further preferably 8-12%.

[0044] Preferably, the extrusion is carried out in a twin-screw extruder. Preferably, the extrusion temperature is 190-250°C, for example, 200°C, 210°C, 220°C, 230°C or 240°C, and specific values ​​between the above values. Due to space limitations and for simplicity, the present invention no longer exhaustively lists the specific values ​​included in the range.

[0045] Preferably, the twin-screw extruder includes 10-13 sections of the barrel, for example, 10, 11, 12, 13, etc. Preferably, the temperature of the twin-screw extruder is set to 200-220°C for the first section; 240-260°C for the second section; 220-240°C for the third section; 200-220°C for the fourth section; 190-210°C for the fifth section; and 180-200°C for sections 6-13, each independently.

[0046] Preferably, the mixing comprises injecting the sodium bicarbonate solution into the 3rd to 7th sections of the screw, for example, the 4th, 5th or 6th section.

[0047] The present invention further improves the odor effect by injecting sodium bicarbonate solution into the 3rd to 7th sections of the screw. When sodium bicarbonate is added in advance or in a delayed manner, the devolatilization effect is weak, which affects the odor level of the product.

[0048] In a fourth aspect, the present invention provides a use of the polypropylene composition as described in the first aspect or the low-odor polypropylene as described in the second aspect in automobile interior decoration.

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

[0050] The present invention provides a polypropylene composition, which uses the characteristics of high saturated vapor pressure and high solubility of carbon dioxide as the main component of the stripping agent; through the characteristic of sodium bicarbonate releasing carbon dioxide when decomposed by heat, carbon dioxide is introduced into the material, and combined with the stripping devolatilization technology, the volatiles and the stripping agent nucleate, grow, and break during the extrusion process, enter the gas phase, and the volatiles are removed from the polymer melt, reducing the odor level of the product, and the odor level of the obtained low-odor polypropylene is low. In addition, the applicant has found that the addition of a specific concentration of sodium bicarbonate can also significantly reduce the glossiness of the appearance of the product, thereby effectively reducing the "plastic feel" of the appearance of automotive interior parts. The method is simple and efficient, cheap and safe, and has high universality. DETAILED DESCRIPTION

[0051] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0052] In the following specific implementation of the present invention, the materials involved are as follows:

[0053] 1) Polypropylene resin

[0054] EP548R, copolymer polypropylene resin, melt index 30g / 10min (230℃, 2.16kg weight), provided by CNOOC Shell

[0055] EP640V, copolymer polypropylene resin, melt index 100g / 10min (230℃, 2.16kg weight), provided by CNOOC Shell

[0056] 2) Filling

[0057] Talc powder, brand TYT-777A, 3000 mesh talc powder, provided by Haicheng Tianyuan

[0058] Talc powder, brand TY90-13-C, 1250 mesh talc powder, provided by Guangxi Longguang

[0059] 3) Elastomer

[0060] POE ENGAGE 7447, ethylene-butene copolymer, supplied by The Dow Chemical Company

[0061] POE ENGAGE 8842, ethylene-octene copolymer, supplied by The Dow Chemical Company

[0062] 4) Primary antioxidant

[0063] SONOX 1010 hindered phenol antioxidant, provided by Sanfeng Chemical

[0064] 5) Secondary antioxidant

[0065] SONOX 168 phosphite antioxidant, provided by Sanfeng Chemical

[0066] Examples 1-26, Comparative Examples 1-5

[0067] A polypropylene composition, the types and amounts of various components are shown in Table 1 and Table 2, and the units of the amounts of various components are all "parts".

[0068] Application Example 1-26, Comparative Application Example 1-5

[0069] A low-odor polypropylene, wherein the low-odor polypropylene is prepared from the polypropylene composition of Examples 1-26 or Comparative Examples 1-5;

[0070] The preparation method of the low-odor polypropylene comprises the following steps:

[0071] Sodium bicarbonate is prepared into a sodium bicarbonate aqueous solution with a concentration as shown in Tables 1 and 2, and is melt-blended and extruded with a polypropylene resin, a filler, an elastomer, a primary antioxidant, and a secondary antioxidant according to a ratio using a twin-screw extruder to obtain the low-odor polypropylene, wherein the sodium bicarbonate aqueous solution or the aqueous solution is injected at a position as shown in Tables 1 and 2, and the temperature of the twin-screw extruder is set to 210°C for section 1; 250°C for section 2; 230°C for section 3; 210°C for section 4; 200°C for section 5; 190°C for section 6; 190°C for section 7; 190°C for section 8; 190°C for section 9; 190°C for section 10; 190°C for section 11; 190°C for section 12; and 190°C for section 13; the aspect ratio of the screw is 56:1, the diameter is 90.4 mm, and the rotation speed is 500 r / min.

[0072] The only difference between Comparative Example 1 and Example 4 is that there is no sodium bicarbonate in the polypropylene composition, and the sodium bicarbonate solution is replaced by water of equal mass.

[0073] The low odor polypropylene obtained in Example 1-26 and Comparative Application Example 1-5 was tested as follows:

[0074] 1) Smell test

[0075] According to the Volkswagen PV3900 standard, 20g of the product is weighed and sealed in a 1-liter glass container with an odor-neutralizing seal and lid, and placed in a heating box with circulating air at (80±2)℃ for 2h±10min. After being taken out, it is cooled to the experimental temperature (60±5)℃ before being identified. After identification by three appraisers, the container is placed back in the (80±2)℃ environment for 30min, and then identified by other appraisers. The identification work is completed by at least three appraisers. If the score difference is ≥2, at least five appraisers must retest.

[0076] 2) Gloss characterization

[0077] According to GB / 8807-1988 standard, the sample is injection molded into a 100*100*2mm flat plate. The surface of the test piece is ensured to be smooth and flat, without dirt, scratches and other defects. After the gloss meter is calibrated with a reference plate, the gloss is measured on the test piece at an incident angle of 60 degrees. Each group of test pieces is no less than three, and the measurement average is taken. To ensure the stability of the test, the mold surface used to prepare the test sample should be polished regularly with 1000 mesh sandpaper. The test results are summarized in Table 1 and Table 2.

[0078] Table 1

[0079]

[0080]

[0081]

[0082] Table 2

[0083]

[0084] The test results show that the polypropylene composition provided by the present invention adopts a polypropylene resin, a filler, an elastomer and sodium bicarbonate in a specific ratio, and introduces carbon dioxide into the material by utilizing the property that sodium bicarbonate releases carbon dioxide when decomposed by heat. The carbon dioxide is used as the main component of the stripping agent, and the stripping and devolatilization technology is used to remove volatiles from the polymer melt, thereby reducing the odor level of the product. The odor level of the obtained low-odor polypropylene is ≤4.25, and the glossiness can also be effectively reduced. The method is simple, efficient, inexpensive, safe and has high universality.

[0085] By comparing the examples, it can be seen that the present invention can more efficiently remove volatile odor substances and reduce the odor level of the product by further adjusting the ratio of sodium bicarbonate to filler, the ratio of sodium bicarbonate to polypropylene resin, the amount of antioxidant and the injection position of the sodium bicarbonate solution.

[0086] By comparing the examples with comparative example 1, it can be seen that the present invention uses sodium bicarbonate as a carrier and introduces carbon dioxide into the material for stripping and devolatilization to obtain low-odor polypropylene. However, when sodium bicarbonate is lacking, the obtained polypropylene material has a higher odor level and the gloss of the product is higher, which is difficult to meet the application requirements in automotive interiors.

[0087] By comparing the embodiment with comparative examples 2-5, it can be seen that the present invention obtains a polypropylene material with good appearance and low odor level by compounding polypropylene resin, filler, elastomer and sodium bicarbonate, and further optimizing the concentration and content of the sodium bicarbonate solution, which is suitable for automotive interior.

[0088] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A polypropylene composition, characterized in that The polypropylene composition comprises, by weight: 54-92 parts of polypropylene resin, 0.01-31 parts of filler, 0.01-16 parts of elastomer and 0.4-2.3 parts of sodium bicarbonate; The sodium bicarbonate is added in the form of a sodium bicarbonate solution, and the mass concentration of the sodium bicarbonate in the sodium bicarbonate solution is 2-15%.

2. The polypropylene composition according to claim 1, characterized in that The mass ratio of the polypropylene resin to sodium bicarbonate is (50-90):1; Preferably, the mass ratio of the sodium bicarbonate to the filler is 1:(4-20); Preferably, the solvent of the sodium bicarbonate solution comprises water.

3. The polypropylene composition according to claim 1, characterized in that The polypropylene resin is copolymerized polypropylene; Preferably, the copolymerized polypropylene comprises a propylene-ethylene copolymer; Preferably, the molar content of propylene-based structural units in the propylene-ethylene copolymer is 85-95%; Preferably, the melt index of the polypropylene resin is 30-100 g / 10 min, and the melt index is measured at 230° C. and 2.16 kg weight.

4. The polypropylene composition according to claim 1, characterized in that The filler comprises any one of talc, mica or wollastonite or a combination of at least two thereof, preferably talc; Preferably, the particle size of the talc is 1000-3000 mesh.

5. The polypropylene composition according to claim 1, characterized in that The elastomer comprises a polyolefin elastomer; Preferably, the polyolefin elastomer comprises ethylene-butene copolymer and / or ethylene-octene copolymer.

6. The polypropylene composition according to claim 1, characterized in that The polypropylene composition further comprises 0.2-1 parts of antioxidant in parts by weight; Preferably, the antioxidant comprises a combination of a primary antioxidant and a secondary antioxidant; Preferably, the mass ratio of the primary antioxidant to the secondary antioxidant is 1:(0.8-1.2); Preferably, the primary antioxidant comprises a hindered phenol antioxidant; Preferably, the hindered phenol antioxidant includes any one of antioxidant 1010, antioxidant 1076, antioxidant 330 or antioxidant 1790, or a combination of at least two thereof; Preferably, the secondary antioxidant comprises a phosphite antioxidant; Preferably, the phosphite antioxidant includes antioxidant 168 and / or antioxidant 627A.

7. A low-odor polypropylene, characterized in that: The low-odor polypropylene is prepared from the polypropylene composition according to any one of claims 1 to 6.

8. A method for preparing low-odor polypropylene as claimed in claim 7, characterized in that: The preparation method comprises the following steps: Sodium bicarbonate is dissolved in water to obtain a sodium bicarbonate solution; the sodium bicarbonate solution is mixed with a polypropylene resin, a filler, an elastomer, an optional primary antioxidant, and an optional secondary antioxidant, and extruded to obtain the low-odor polypropylene.

9. The preparation method according to claim 8, characterized in that: The mass concentration of sodium bicarbonate in the sodium bicarbonate solution is 2-15%, preferably 8-12%; Preferably, the extrusion is carried out in a twin-screw extruder; Preferably, the extrusion temperature is 190-250°C; Preferably, the mixing comprises injecting sodium bicarbonate solution into screw sections 3-7.

10. Use of the polypropylene composition according to any one of claims 1 to 6 or the low-odor polypropylene according to claim 7 in automobile interior decoration.

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