Polypropylene foam material and preparation method thereof

Abstract

The invention relates to the technical field of foaming materials, in particular to a polypropylene foaming material and a preparation method thereof. The polypropylene foaming material comprises the following components in parts by weight: 88-96.5 parts of polypropylene resin, 0.5-2 parts of a sensitizing agent, 2-5 parts of a nucleating agent and 1-5 parts of other auxiliary agents. The preparation method of the polypropylene foaming material comprises the following steps: S101, uniformly mixing polypropylene resin, a sensitizing agent, a nucleating agent and a compound additive according to a ratio to obtain a mixed material; s103, feeding the mixed material into an extruder, and carrying out extrusion granulation; s105, carrying out irradiation crosslinking on the extrudate obtained in the step S103; and S107, performing blow molding, extruding and foaming to obtain the polypropylene foaming material. The polypropylene foaming material is high in foaming ratio.

Description

Technical Field

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

[0002] Polyethylene (PE) is a thermoplastic resin synthesized from ethylene monomers through polymerization. The maximum operating temperature of polyethylene foam material is around 80°C. When the temperature rises to a certain level, the polyethylene foam material will soften or even melt, and its operating temperature range is relatively narrow. In some high-temperature environments, such as in the engine compartment of a car, near high-temperature pipes, etc., the performance of polyethylene foam materials will be seriously affected, and even deformation, damage and other problems may occur. Under low temperature conditions, polyethylene foam materials will become brittle and hard, and their toughness and elasticity will drop significantly, making them prone to breakage. When used in cold areas or low-temperature environments, they need to be specially treated or modified materials with better low-temperature resistance should be selected.

[0003] Polypropylene (PP), as an important thermoplastic, is widely used in various fields due to its good processing performance, chemical stability and relatively low cost. However, traditional polypropylene foam materials often have problems such as low foaming efficiency, uneven cell structure, and insufficient mechanical properties. The foaming process of ordinary polypropylene needs to be carried out within a temperature range close to its crystalline melting point. Above this temperature, the melt viscosity will drop rapidly, making foaming molding very difficult. The melt strength of ordinary polypropylene resin is very low. During the foaming process, the cell wall often cannot support the growth of the cell, and the foaming efficiency is low.

[0004] Therefore, a foaming material with good heat resistance and high foaming performance and a preparation method thereof are needed to meet the requirements of high temperature resistance and high foaming performance. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a polypropylene foam material with improved heat resistance and foaming performance and a preparation method thereof.

[0006] In order to achieve the above purpose, the technical solution adopted by the present invention is: to provide a polypropylene foam material, comprising the following components in parts by weight: 88 to 96.5 parts of polypropylene resin, 0.5 to 2 parts of sensitizer, 2 to 5 parts of nucleating agent, and 1 to 5 parts of other additives.

[0007] Furthermore, the melt index of the polypropylene resin is ≤2g / 10min.

[0008] Furthermore, the sensitizer is trimethylol triacrylate.

[0009] Furthermore, the nucleating agent is composed of one or a combination of talc, calcium carbonate, wollastonite or barium sulfate, and the particle size of the talc is greater than 6000 mesh.

[0010] Furthermore, the other additives include antioxidants, lubricants and black powder; the antioxidants include primary antioxidants and secondary antioxidants, the primary antioxidants are amine antioxidants and / or phenolic antioxidants; the secondary antioxidants are phosphite antioxidants and / or thioester antioxidants.

[0011] The present invention also provides a method for preparing a polypropylene foam material, comprising the following steps:

[0012] S101: The polypropylene resin, the sensitizer, the nucleating agent and the composite auxiliary agent are uniformly mixed according to a proportion to obtain a mixed material.

[0013] S103: sending the mixed material into an extruder for extrusion granulation;

[0014] S105: irradiating and cross-linking the extrudate in step S103;

[0015] S107: Blow molding, extrusion and foaming to obtain a polypropylene foam material.

[0016] Furthermore, the extruder in step S103 uses a twin-screw extrusion granulation, the extrusion temperature is 180-230° C., and the rotation speed is 450 r / min.

[0017] Furthermore, during the radiation cross-linking process in step S105, the radiation dose is 100 to 200 Gy, and the gel volume is 30% to 40%.

[0018] Furthermore, the specific method of step S107 is: adopting chemical foaming, the foaming masterbatch is sodium bicarbonate masterbatch, and the proportion of mixed particles formed by blending the radiation cross-linked particles and the foaming masterbatch is 2% to 5%.

[0019] Furthermore, in step S107, the blow molding process temperature is 160-200° C., and the molding blowing pressure is ≤0.2 MPa.

[0020] The technical solution of the present invention has the following advantages:

[0021] 1. The melt index of the polypropylene resin in the present invention is ≤2g / 10min, indicating that the polypropylene resin has relatively moderate fluidity in a molten state, is suitable for processes such as injection molding and extrusion molding, and provides a suitable mixture for preparation in subsequent processes.

[0022] 2. The talcum powder with a particle size greater than 6000 mesh in the present invention can accelerate the crystallization of polypropylene, optimize the melting performance of polypropylene, and make it easier to process and shape. As a nucleating agent, talcum powder can ensure that the molten polymer solidifies more quickly during the cooling process, thereby shortening the injection molding cycle and improving production efficiency. Talcum powder can enhance the tensile strength, heat deformation temperature and hardness of polypropylene foam materials, while increasing transparency and reducing turbidity. Talcum powder also helps polypropylene foam materials form a finer and more uniform cell structure.

[0023] 3. The sensitizer of the present invention uses trimethylol triacrylate, which can greatly improve the crosslinking efficiency of polypropylene during irradiation. The degree of crosslinking of polypropylene is a function of the irradiation dose and the amount of sensitizer. Only when the amounts of the two are matched, the system will have a higher gel content and a low degree of degradation of the system. Using trimethylol triacrylate as a sensitizer under nitrogen protection can effectively reduce the irradiation dose and achieve a relatively high gel content.

[0024] 4. In the method of the present invention, the extrusion temperature is set at 180-230°C. Within this temperature range, the mixed material can be fully melted, ensuring the uniformity and stability of the molten state, which is beneficial to the subsequent extrusion and foaming process. The appropriate temperature can improve the plasticization effect of polypropylene, making it easier to process and shape, while ensuring the physical properties and appearance quality of the product. Controlling the temperature between 180 and 230°C can prevent polypropylene from degrading due to excessive temperature, thereby extending the service life of the product and maintaining its excellent performance.

[0025] 5. Under the combined effect of appropriate radiation dose and appropriate amount of gel, more crosslinking points can be formed between polypropylene molecular chains. The gel amount of the present invention is controlled at 30% to 40% to further ensure the perfection of the crosslinking network structure, thereby improving the crosslinking degree of the material. Radiation crosslinking can promote polypropylene to form a finer and more uniform pore structure during the foaming process, thereby improving the foaming ratio and pore density of polypropylene foam materials. Through radiation crosslinking, the melt strength of polypropylene is significantly improved, which is beneficial to gas retention and stable formation of pores during the foaming process, thereby improving the quality of the foaming material. Radiation crosslinking and an appropriate amount of gel can significantly improve the heat resistance and chemical stability of polypropylene materials.

[0026] It should be appreciated that all combinations of the foregoing concepts, as well as additional concepts described in greater detail below, may be considered to be part of the inventive subject matter of the present disclosure, provided such concepts are not mutually inconsistent.

[0027] The foregoing and other aspects, embodiments and features of the present invention will be more fully understood from the following description. Other additional aspects of the present invention, such as the features and / or beneficial effects of the exemplary embodiments, will be apparent from the following description or will be learned from the practice of the specific embodiments according to the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meaning understood by people with general skills in the field to which the present invention belongs.

[0029] The words "first", "second" and similar words used in the patent application specification and claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular forms of "a", "an" or "the" and other similar words do not indicate a quantitative limitation, but indicate the existence of at least one. Words such as "include" or "comprise" mean that the elements or objects appearing before "include" or "comprise" cover the features, wholes, steps, operations, elements and / or components listed after "include" or "comprise", and do not exclude the existence or addition of one or more other features, wholes, steps, operations, elements, components and / or their collections. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0030] The embodiment of the present invention provides a polypropylene foam material, comprising the following components in parts by weight: 88 to 96.5 parts of a polypropylene resin, 0.5 to 2 parts of a sensitizer, 2 to 5 parts of a nucleating agent, and 1 to 5 parts of other additives.

[0031] In some embodiments of the present invention, the melt index of the polypropylene resin is ≤2 g / 10 min.

[0032] The melt index is an indicator for measuring the flow properties of polypropylene resin in a molten state. The larger the melt index, the better the melt flow properties of the polypropylene resin. Conversely, the smaller the melt index, the worse the melt flow properties of the polypropylene resin. The melt index of the polypropylene resin in the present invention is ≤2g / 10min, indicating that the polypropylene resin has relatively moderate flow properties in a molten state, is suitable for injection molding and extrusion molding processes, and provides a suitable mixture for preparation in subsequent processes.

[0033] In some embodiments of the present invention, the sensitizer is trimethylol triacrylate. The sensitizer in the present invention uses trimethylol triacrylate, which can greatly improve the crosslinking efficiency of polypropylene during irradiation. The degree of crosslinking of polypropylene is a function of the irradiation dose and the amount of the sensitizer. Only when the amounts of the two are matched, the system will have a higher gel content and a low degree of degradation of the system. Using trimethylol triacrylate as a sensitizer under nitrogen protection can effectively reduce the irradiation dose and achieve a relatively high gel content.

[0034] In some embodiments of the present invention, the nucleating agent is composed of one or more combinations of talcum powder, calcium carbonate, wollastonite or barium sulfate, and the talcum powder particle size is greater than 6000 mesh. Talcum powder greater than 6000 mesh particle size can accelerate the crystallization of polypropylene, optimize the melting properties of polypropylene, and make it easier to process and shape. As a nucleating agent, talcum powder can ensure that the molten polymer solidifies more rapidly during the cooling process, thereby shortening the injection molding cycle and improving production efficiency. Talcum powder can enhance the tensile strength, heat deformation temperature and hardness of polypropylene foam material, increase transparency and reduce turbidity. Talcum powder also helps polypropylene foam material to form a finer and more uniform pore structure.

[0035] In some embodiments of the present invention, the other additives include antioxidants, lubricants and black powder; the antioxidants include primary antioxidants and secondary antioxidants, the primary antioxidants are amine antioxidants and / or phenolic antioxidants; the secondary antioxidants are phosphite antioxidants and / or thioester antioxidants. Adding antioxidants to polypropylene foam materials can effectively inhibit the oxidation reaction of polypropylene, extend its service life, protect the physical properties of polypropylene, such as strength, toughness and rigidity, effectively protect the appearance quality of polypropylene, and prevent color changes, cracking, etc. Adding lubricants can improve the processing properties of polypropylene, reduce the viscosity and friction coefficient of the melt, improve the fluidity and uniformity of the melt, and also help reduce energy consumption and production costs in product production, and improve product production efficiency and quality.

[0036] The present invention also provides a method for preparing a polypropylene foam material, comprising the following steps:

[0037] S101: The polypropylene resin, the sensitizer, the nucleating agent and the composite auxiliary agent are uniformly mixed according to a proportion to obtain a mixed material.

[0038] S103: sending the mixed material into an extruder for extrusion granulation;

[0039] S105: performing radiation cross-linking on the extrudate in step S103 under nitrogen protection;

[0040] S107: Blow molding, extrusion and foaming to obtain a polypropylene foam material.

[0041] In some embodiments of the present invention, the extruder in step S103 uses a twin-screw extrusion granulation, and the extrusion temperature is 180-230°C and the rotation speed is 450r / min. The twin-screw granulation processing speed is faster, which can make the mixture more uniform and more conducive to subsequent processing and production. The extrusion temperature is set at 180-230°C. Within this temperature range, the mixture can be fully melted, ensuring the uniformity and stability of the molten state, which is conducive to the subsequent extrusion and foaming process. Appropriate temperature can improve the plasticizing effect of polypropylene, making it easier to process and shape, while ensuring the physical properties and appearance quality of the product. Controlling the temperature between 180 and 230°C can prevent polypropylene from degrading due to excessively high temperature, thereby extending the service life of the product and maintaining its excellent performance.

[0042] In some embodiments of the present invention, during the radiation cross-linking process in step S105, the radiation dose is 100 to 200 Gy, and the gel content is 30% to 40%. Under the combined effect of an appropriate radiation dose and an appropriate gel content, more cross-linking points can be formed between polypropylene molecular chains. The control of the gel content at 30% to 40% further ensures the perfection of the cross-linking network structure, thereby improving the cross-linking degree of the material. Radiation cross-linking can promote the formation of a finer and more uniform pore structure of polypropylene during the foaming process, thereby improving the foaming ratio and pore density of the polypropylene foam material. Through radiation cross-linking, the melt strength of polypropylene is significantly improved, which is beneficial to gas retention and stable formation of pores during the foaming process, thereby improving the quality of the foaming material. Radiation cross-linking and an appropriate amount of gel can significantly improve the heat resistance and chemical stability of polypropylene materials.

[0043] In some embodiments of the present invention, the specific method of step S107 is: chemical foaming is adopted, the foaming masterbatch is sodium bicarbonate masterbatch, and the proportion of mixed particles formed by blending the irradiated cross-linked particles and the foaming masterbatch is 2% to 5%. Sodium bicarbonate generates carbon dioxide gas after thermal decomposition, thereby forming bubbles in polypropylene, which plays a foaming role.

[0044] In some embodiments of the present invention, the blow molding powder, calcium carbonate, wollastonite or barium sulfate in step S107 is composed of one or more of the combinations, and the talc powder particle size is greater than 6000 mesh; other additives include antioxidants, lubricants and black powder; the antioxidants include primary antioxidants and secondary antioxidants, the primary antioxidants are amine antioxidants and phenolic antioxidants; the secondary antioxidants are phosphite antioxidants and thioester antioxidants.

[0045] The technical solution of the present invention is described below through specific embodiments.

[0046] Example 1

[0047] 88 parts of polypropylene resin, 0.5 parts of sensitizer, 5 parts of nucleating agent, and 1 part of other auxiliary agents; the melt index of the polypropylene resin is 2g / 10min; the sensitizer is trimethylol triacrylate; the nucleating agent is composed of one or a combination of talcum powder, calcium carbonate, wollastonite or barium sulfate, and the particle size of the talcum powder is greater than 6000 mesh; other auxiliary agents include antioxidants, lubricants and black powder; the antioxidants include primary antioxidants and secondary antioxidants, the primary antioxidant is an amine antioxidant; the secondary antioxidants are phosphite antioxidants and thioester antioxidants.

[0048] The above polypropylene foam material is prepared by the following preparation method:

[0049] S101: The polypropylene resin, the sensitizer, the nucleating agent and the composite auxiliary agent are uniformly mixed according to a proportion to obtain a mixed material.

[0050] S103: sending the mixed material into an extruder for extrusion granulation;

[0051] S105: irradiating and cross-linking the extrudate in step S103;

[0052] S107: Blow molding, extrusion and foaming to obtain a polypropylene foam material.

[0053] The extruder in step S103 uses a twin-screw extrusion granulation, the extrusion temperature is 180° C., and the rotation speed is 450 r / min.

[0054] During the radiation cross-linking process in step S105, the radiation dose is 100 Gy and the gel volume is 35%.

[0055] The specific method of step S107 is: adopting chemical foaming, the foaming masterbatch is sodium bicarbonate masterbatch, and the proportion of mixed particles formed by blending the radiation cross-linked particles and the foaming masterbatch is 3%.

[0056] In step S107, the blow molding process temperature is 180° C., and the molding blowing pressure is 0.2 MPa.

[0057] Example 2

[0058] 90 parts of polypropylene resin, 1 part of sensitizer, 4 parts of nucleating agent, and 3 parts of other additives; the melt index of the polypropylene resin is 1.8g / 10min; the sensitizer is trimethylol triacrylate; the nucleating agent is composed of one or a combination of talcum powder, calcium carbonate, wollastonite or barium sulfate, and the particle size of the talcum powder is greater than 6000 mesh; other additives include antioxidants, lubricants and black powder; the antioxidants include primary antioxidants and secondary antioxidants, the primary antioxidants are amine antioxidants and / or phenolic antioxidants; the secondary antioxidants are phosphite antioxidants and / or thioester antioxidants.

[0059] The above polypropylene foam material is prepared by the following preparation method:

[0060] S101: The polypropylene resin, the sensitizer, the nucleating agent and the composite auxiliary agent are uniformly mixed according to a proportion to obtain a mixed material.

[0061] S103: sending the mixed material into an extruder for extrusion granulation;

[0062] S105: irradiating and cross-linking the extrudate in step S103;

[0063] S107: Blow molding, extrusion and foaming to obtain a polypropylene foam material.

[0064] The extruder in step S103 uses a twin-screw extrusion granulation, the extrusion temperature is 200° C., and the rotation speed is 450 r / min.

[0065] During the radiation cross-linking process in step S105, the radiation dose is 200 Gy and the gel volume is 30%.

[0066] The specific method of step S107 is: adopting chemical foaming, the foaming masterbatch is sodium bicarbonate masterbatch, and the proportion of mixed particles formed by blending the radiation cross-linked particles and the foaming masterbatch is 2%.

[0067] In step S107, the blow molding process temperature is 200° C., and the molding blowing pressure is 0.1 MPa.

[0068] Example 3

[0069] 96.5 parts of polypropylene resin, 2 parts of sensitizer, 5 parts of nucleating agent, and 5 parts of other additives; the melt index of the polypropylene resin is 1.5g / 10min; the sensitizer is trimethylol triacrylate; the nucleating agent is composed of one or a combination of talcum powder, calcium carbonate, wollastonite or barium sulfate, and the particle size of the talcum powder is greater than 6000 mesh; other additives include antioxidants, lubricants and black powder; the antioxidants include primary antioxidants and secondary antioxidants, the primary antioxidant is an amine antioxidant; the secondary antioxidant is a phosphite antioxidant.

[0070] The above polypropylene foam material is prepared by the following preparation method:

[0071] S101: The polypropylene resin, the sensitizer, the nucleating agent and the composite auxiliary agent are uniformly mixed according to a proportion to obtain a mixed material.

[0072] S103: sending the mixed material into an extruder for extrusion granulation;

[0073] S105: irradiating and cross-linking the extrudate in step S103;

[0074] S107: Blow molding, extrusion and foaming to obtain a polypropylene foam material.

[0075] The extruder in step S103 uses a twin-screw extrusion granulation, the extrusion temperature is 230° C., and the rotation speed is 450 r / min.

[0076] During the radiation cross-linking process in step S105, the radiation dose is 150 Gy and the gel volume is 40%.

[0077] The specific method of step S107 is: adopting chemical foaming, the foaming masterbatch is sodium bicarbonate masterbatch, and the proportion of mixed particles formed by blending the radiation cross-linked particles and the foaming masterbatch is 2%.

[0078] In step S107, the blow molding process temperature is 200° C., and the molding blowing pressure is 0.2 MPa.

[0079] Example 4

[0080] 92 parts of polypropylene resin, 0.5 parts of sensitizer, 3 parts of nucleating agent, and 4 parts of other additives; the melt index of the polypropylene resin is 1.6 g / 10 min; the sensitizer is trimethylol triacrylate; the nucleating agent is composed of one or a combination of talcum powder, calcium carbonate, wollastonite or barium sulfate, and the particle size of the talcum powder is greater than 6000 mesh; other additives include antioxidants, lubricants and black powder; the antioxidants include primary antioxidants and secondary antioxidants, the primary antioxidants are amine antioxidants and phenolic antioxidants; the secondary antioxidants are phosphite antioxidants.

[0081] The above polypropylene foam material is prepared by the following preparation method:

[0082] S101: The polypropylene resin, the sensitizer, the nucleating agent and the composite auxiliary agent are uniformly mixed according to a proportion to obtain a mixed material.

[0083] S103: sending the mixed material into an extruder for extrusion granulation;

[0084] S105: irradiating and cross-linking the extrudate in step S103;

[0085] S107: Blow molding, extrusion and foaming to obtain a polypropylene foam material.

[0086] The extruder in step S103 uses a twin-screw extrusion granulation, the extrusion temperature is 210° C., and the rotation speed is 450 r / min.

[0087] During the radiation cross-linking process in step S105, the radiation dose is 200 Gy and the gel volume is 38%.

[0088] The specific method of step S107 is: chemical foaming is adopted, the foaming masterbatch is sodium bicarbonate masterbatch, and the proportion of mixed particles formed by blending the radiation cross-linked particles and the foaming masterbatch is 4%.

[0089] In step S107, the blow molding process temperature is 190° C., and the molding blowing pressure is 0.2 MPa.

[0090] Example 5

[0091] 94 parts of polypropylene resin, 1 part of sensitizer, 4 parts of nucleating agent, and 3 parts of other additives; the melt index of the polypropylene resin is 2g / 10min; the sensitizer is trimethylol triacrylate; the nucleating agent is composed of one or a combination of talcum powder, calcium carbonate, wollastonite or barium sulfate, and the particle size of the talcum powder is greater than 6000 mesh; other additives include antioxidants, lubricants and black powder; the antioxidants include primary antioxidants and secondary antioxidants, the primary antioxidants are amine antioxidants and phenolic antioxidants; the secondary antioxidants are phosphite antioxidants.

[0092] The above polypropylene foam material is prepared by the following preparation method:

[0093] S101: The polypropylene resin, the sensitizer, the nucleating agent and the composite auxiliary agent are uniformly mixed according to a proportion to obtain a mixed material.

[0094] S103: sending the mixed material into an extruder for extrusion granulation;

[0095] S105: irradiating and cross-linking the extrudate in step S103;

[0096] S107: Blow molding, extrusion and foaming to obtain a polypropylene foam material.

[0097] The extruder in step S103 uses a twin-screw extrusion granulation, the extrusion temperature is 200° C., and the rotation speed is 450 r / min.

[0098] During the radiation cross-linking process in step S105, the radiation dose is 170 Gy and the gel volume is 35%.

[0099] The specific method of step S107 is: adopting chemical foaming, the foaming masterbatch is sodium bicarbonate masterbatch, and the proportion of mixed particles formed by blending the radiation cross-linked particles and the foaming masterbatch is 4.5%.

[0100] In step S107, the blow molding process temperature is 165° C., and the molding blowing pressure is 0.16 MPa.

[0101] Table 1 is a performance comparison table of Examples 1 to 5 of the present invention and polyethylene foam material.

[0102]

[0103] It can be seen from Table 1 that the polypropylene foam material of the embodiment of the present invention has obvious improvements in foaming ratio, tensile strength and elongation at break, especially heat resistance, compared with ordinary PE foam material.

[0104] The polypropylene foam material with a high foaming ratio in the embodiment of the present invention can be widely used in packaging materials such as electronic communication equipment, liquid crystal displays, and precision electronic components, and also has application prospects in automobile shockproof cores, advanced safety seats, and instrument panels.

[0105] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. A person with ordinary knowledge in the technical field to which the present invention belongs may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the definition of the claims.

Claims

1. A polypropylene foam material, characterized in that: The invention comprises the following components in parts by weight: 88 to 96.5 parts of polypropylene resin, 0.5 to 2 parts of sensitizer, 2 to 5 parts of nucleating agent and 1 to 5 parts of other auxiliary agents.

2. The polypropylene foam material according to claim 1, characterized in that: The melt index of the polypropylene resin is ≤2g / 10min.

3. The polypropylene foam material according to claim 1, characterized in that: The sensitizer is trimethylol triacrylate.

4. The polypropylene foam material according to claim 1, characterized in that: The nucleating agent is composed of one or a combination of talc, calcium carbonate, wollastonite or barium sulfate, and the particle size of the talc is greater than 6000 meshes.

5. The polypropylene foam material according to claim 1, characterized in that: The other additives include antioxidants, lubricants and black powder; the antioxidants include primary antioxidants and secondary antioxidants, the primary antioxidants are amine antioxidants and / or phenolic antioxidants; the secondary antioxidants are phosphite antioxidants and / or thioester antioxidants.

6. A method for preparing a polypropylene foam material, characterized in that: The following steps are involved: S101: mixing polypropylene resin, sensitizer, nucleating agent and composite additive uniformly according to a proportion to obtain a mixed material; S103: sending the mixed material into an extruder for extrusion granulation; S105: irradiating and cross-linking the extrudate in step S103; S107: Blow molding, extrusion and foaming to obtain a polypropylene foam material.

7. The method for preparing a polypropylene foam material according to claim 6, characterized in that: The extruder in step S103 uses a twin-screw extrusion granulation, the extrusion temperature is 180-230° C., and the rotation speed is 450 r / min.

8. The method for preparing a polypropylene foam material according to claim 6, characterized in that: During the radiation cross-linking process in step S105, the radiation dose is 100 to 200 Gy, and the gel volume is 30% to 40%.

9. The method for preparing a polypropylene foam material according to claim 6, characterized in that: The specific method of step S107 is: adopting chemical foaming, the foaming masterbatch is sodium bicarbonate masterbatch, and the proportion of mixed particles formed by blending the radiation cross-linked particles and the foaming masterbatch is 2% to 5%.

10. The method for preparing a polypropylene foam material according to claim 6, characterized in that: In the step S107, the blow molding process temperature is 160-200° C., and the molding blowing pressure is ≤0.2 MPa.

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