Polypropylene alloy bead foaming material as well as preparation method and application thereof

Abstract

The invention relates to the field of polymer foam materials, and discloses a polypropylene alloy bead foam material as well as a preparation method and application thereof. The foaming material is prepared from co-polypropylene and homo-polybutylene-1; wherein relative to 100 parts by weight of the co-polypropylene, the content of the homo-polybutylene-1 is 10-25 parts by weight. The preparation method of the polypropylene alloy bead foaming material comprises the step of physically foaming the co-polypropylene, the homo-polybutylene-1 and the auxiliaries. When the foaming material is used for preparing a foaming product, the steam forming pressure is relatively low (0.21-0.25 MPa), and relatively good rigidity and specific strength can be kept.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer foaming materials, and particularly relates to a polypropylene alloy bead foaming material, a preparation method thereof and an application thereof. Background Art

[0002] Polypropylene resin has excellent properties such as good processability, heat resistance, recyclability, and strong mechanical strength, and is the second largest general-purpose plastic in the world. Its foaming material also has characteristics such as lightweight, cushioning, heat insulation and sound insulation. In particular, bead foamed polypropylene has developed rapidly in recent years and has a wide range of applications in industries such as automobiles, packaging, toys, household appliances, and construction. However, the relatively high melting point of polypropylene makes its bead foaming material require a relatively high steam pressure in steam molding. The excessive molding pressure, on the one hand, places higher requirements on the molding equipment, and on the other hand, also increases the molding energy consumption. While the existing technology reduces the steam molding pressure of the bead foaming material, the rigidity and strength of the polypropylene bead foaming material will also decrease significantly. How to maintain the rigidity of the polypropylene bead foaming material on the basis of reducing steam molding is also a major problem in the industry.

[0003] To reduce the steam molding pressure of polypropylene bead foaming material, the first existing technical solution selects a terpolymerized polypropylene with relatively low modulus and melting point, such as the E800E series of Shanghai Petrochemical. Its flexural modulus is about 700 MPa and the melting point is about 142 °C. Although the obtained bead foaming material has a relatively low steam molding pressure, the hardness of the foaming material is often insufficient. The second existing technology also chooses to introduce polyethylene, ethylene-based elastomer / plastic (POE, POP) or propylene-based elastomer into the binary copolymerized polypropylene foaming base material with better rigidity to increase the low melting point components in the foaming matrix and reduce the steam molding pressure of the bead foaming material. However, the compatibility between polyethylene and polypropylene is poor, and a large amount of addition is likely to cause phase separation in the composite material, affecting the mechanical properties and product stability of the foamed product. This also results in the fact that the polyethylene-modified polypropylene foaming material has not been commercialized. And ethylene-based elastomer / plastic (POE, POP) or propylene-based elastomer has a relatively low crystallinity. On the one hand, it will significantly reduce the hardness of the foaming material, and on the other hand, the effect of reducing the steam molding pressure of the bead foaming material is relatively limited. Summary of the Invention

[0004] The purpose of the present invention is to overcome the problems of too high steam molding pressure and poor mechanical properties of the polypropylene foaming material existing in the prior art, and provide a polypropylene alloy bead foaming material, a preparation method thereof and an application thereof. The polypropylene alloy bead foaming material has a relatively low steam molding pressure and good mechanical properties.

[0005] To achieve the above object, a first aspect of the present invention provides a polypropylene alloy bead foaming material, which comprises a copolymerized polypropylene and a homopolymerized polybutene-1; wherein, relative to 100 parts by weight of the copolymerized polypropylene, the content of the homopolymerized polybutene-1 is 10-25 parts by weight.

[0006] A second aspect of the present invention provides a method for preparing a polypropylene alloy bead foaming material, and the preparation method includes: physically foaming the copolymerized polypropylene, the homopolymerized polybutene-1 and an auxiliary agent.

[0007] A third aspect of the present invention provides a polypropylene alloy bead foaming material prepared by the preparation method described in the second aspect.

[0008] A fourth aspect of the present invention provides an application of the polypropylene alloy bead foaming material described in the first aspect or the third aspect in packaging, automobiles, household or building materials.

[0009] Through the above technical solutions, the present invention introduces the homopolymerized polybutene-1 into the copolymerized polypropylene foaming material, which can form a stable and uniform structure, and is beneficial to obtaining a foamed product with stable properties; the cooperation of the homopolymerized polybutene-1 and the copolymerized polypropylene with specific structural parameters (such as high isotacticity and crystallinity) can reduce the steam molding pressure of the polypropylene bead foaming material, and at the same time avoid significantly reducing the rigidity and hardness of the foaming material. From the mechanical property test results of the foaming materials prepared in the examples, as shown in Table 2 and Table 3, the polypropylene bead foaming material of the present invention still has high rigidity and specific strength while reducing the steam molding pressure. In addition, the polypropylene bead foaming material of the present invention can save energy and reduce consumption and costs. Specific Embodiments

[0010] In the ranges disclosed herein, the endpoints and any value are not limited to the exact range or value, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range, between the endpoint values of each range and a single point value, and between single point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0011] The following will describe in detail the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only for the purpose of illustration and explanation of the present invention, and are not used to limit the present invention.

[0012] A first aspect of the present invention provides a polypropylene alloy bead foaming material, which comprises a copolymerized polypropylene and a homopolymerized polybutene-1; wherein, relative to 100 parts by weight of the copolymerized polypropylene, the content of the homopolymerized polybutene-1 is 10-25 parts by weight.

[0013] The inventors of the present invention have found that:

[0014] First, homopolymer polybutene-1 and copolymer polypropylene have good compatibility and can still form a stable homogeneous structure even when the addition amount is 10-25%, which is beneficial to obtaining a foamed product with stable properties;

[0015] Second, homopolymer polybutene-1 has a high crystallinity and a flexural modulus similar to that of polypropylene, which can avoid significantly reducing the rigidity and hardness of the foamed material;

[0016] Third, copolymer polypropylene has an appropriate melting point and a relatively high flexural modulus, making it expandable and ensuring that the foamed material has sufficient strength and rigidity;

[0017] Fourth, polybutene-1 has a high crystallinity, and its melting point is 18-27 °C lower than that of polypropylene. A small proportion of addition can significantly reduce the steam temperature during the steam molding process, save energy, reduce consumption, and reduce costs.

[0018] According to the present invention, the bead foamed material obtained by modifying copolymer polypropylene with high isotacticity homopolymer polybutene-1 can maintain good rigidity and specific strength of the foamed material while significantly reducing the steam molding pressure of the foamed material.

[0019] According to the present invention, preferably, relative to 100 parts by weight of the copolymer polypropylene, the content of the homopolymer polybutene-1 is 12-20 parts by weight. In the present invention, if the content of the homopolymer polybutene-1 is too low, the steam molding pressure cannot be reduced; if the content of the homopolymer polybutene-1 is too high, the raw material cost is relatively high, and the rigidity and specific strength of the foamed material will decrease to a certain extent.

[0020] According to the present invention, in order to make the polypropylene alloy bead foamed material modified with homopolymer polybutene-1 have a lower steam molding pressure and maintain high hardness and specific strength, preferably, the melting point of the homopolymer polybutene-1 is 128-130 °C.

[0021] Preferably, the flexural modulus of the homopolymer polybutene-1 is 600-700 MPa, and the crystallinity is 55-65%.

[0022] Preferably, the isotacticity of the homopolymer polybutene-1 is greater than or equal to 98%, and further preferably greater than or equal to 99%.

[0023] Preferably, the melt index of the homopolymer polybutene-1 at 190 °C and 2.16 kg is 1-4 g / 10 min.

[0024] According to the present invention, in order to enable the modified polypropylene alloy bead foaming material to have a lower steam molding pressure while also having high rigidity and specific strength, preferably, the copolymerized polypropylene is binary copolymerized polypropylene, and further preferably, the second comonomer is ethylene or butene-1.

[0025] Preferably, the melting point of the copolymerized polypropylene is 148 - 155 °C.

[0026] Preferably, the flexural modulus of the copolymerized polypropylene is 1000 - 1200 MPa.

[0027] Preferably, the melt index of the copolymerized polypropylene at 230 °C and 2.16 kg is 3 - 10 g / 10 min.

[0028] According to the present invention, preferably, the polypropylene alloy bead foaming material further comprises additives; further preferably, the additives include an antioxidant, a nucleating agent, and an acid scavenger.

[0029] Preferably, the weight ratio of the antioxidant, the nucleating agent, and the acid scavenger is 1:(0.1 - 2):(0.1 - 2); more preferably 1:(0.5 - 1.5):(0.5 - 1.5); according to a preferred embodiment of the present invention, even more preferably, the weight ratio of the antioxidant, the nucleating agent, and the acid scavenger is 1:1:1 or 1:1.5:1.5.

[0030] The present invention does not particularly limit the composition of the antioxidant, the nucleating agent, and the acid scavenger, as long as it can promote the molding of the foaming material and improve the performance of the foaming material, and it can be some conventional antioxidants, nucleating agents, and acid scavengers in the field of foaming materials. Preferably, the antioxidant is selected from at least one of phosphite antioxidants, hindered phenol antioxidants, and hindered amine antioxidants; the nucleating agent is selected from at least one of zinc borate, montmorillonite, talc powder, nano-clay, and kaolin; the acid scavenger is selected from at least one of hydrotalcite, calcium stearate, and zinc stearate; according to a preferred embodiment of the present invention, further preferably, the antioxidant is antioxidant 1010 / 168; the nucleating agent is talc powder; the acid scavenger is calcium stearate.

[0031] According to the present invention, preferably, the content of the additives is 1 - 2 parts by weight relative to 100 parts by weight of the copolymerized polypropylene.

[0032] According to the present invention, preferably, the steam molding pressure of the foaming material is 0.21 - 0.25 MPa.

[0033] Preferably, the density of the foaming material is 0.100 - 0.032 g / mL.

[0034] Preferably, when the density of the foaming material is 0.100 ± 0.003 g / mL, the Shore hardness AO of the foaming material is greater than 85°, the 50% compressive strength is greater than 0.75 MPa, and the tensile strength is greater than 1.9 MPa.

[0035] Preferably, when the density of the foaming material is 0.05 ± 0.002 g / mL, the Shore hardness AO of the foaming material is greater than 70°, the 50% compressive strength is greater than 0.4 MPa, and the tensile strength is greater than 1.1 MPa.

[0036] Preferably, when the density of the foaming material is 0.033 ± 0.002 g / mL, the Shore hardness AO of the foaming material is greater than 62°, the 50% compressive strength is greater than 0.3 MPa, and the tensile strength is greater than 0.8 MPa.

[0037] The performance parameters of the foaming material of the present invention are obtained by a commercially available device according to a specific test method. Among them, the source and model of the commercially available device and the specific test method are as follows:

[0038] Density test equipment: METTLER-TOLEDO, Switzerland: ME104E + density module.

[0039] Mechanical properties: Instron, USA: 5567 universal testing machine.

[0040] Density: Using a density balance, the density of the polypropylene base resin and the foaming material is obtained by the drainage method. The foaming ratio formula of the foaming material is Where is the foaming ratio, ρ1 is the density of the base resin, and ρ2 is the density of the foaming material.

[0041] Compressive strength: Cut a specimen of 30 * 30 * 13 mm in the foaming material, and use a universal testing machine to perform a compression test at a compression speed of 2 mm / min to obtain the compressive strength when the sample is compressed by 50%.

[0042] Tensile strength: Prepare a spline according to GB / T 6344-2008, and use a universal testing machine to perform a tensile test at a tensile rate of 50 mm / min to obtain the tensile strength of the sample.

[0043] Hardness: Cut a specimen of 30 * 30 * 13 mm in the foaming material, and according to GB / T 531.1-2008, use an AO type hardness tester to measure the Shore hardness of the material.

[0044] The composition of the foaming material of the present invention can be obtained by the feeding amount.

[0045] The composition components of the foaming material of the present invention can be commercially available products or prepared by any existing method.

[0046] The present invention does not particularly limit the preparation method of the foaming material, as long as the foaming material having the above composition and properties can be obtained. According to a preferred embodiment of the present invention, a second aspect of the present invention provides a preparation method of a polypropylene alloy bead foaming material, and the preparation method includes: physically foaming a copolymerized polypropylene, a homopolymerized polybutene-1, and an auxiliary agent.

[0047] According to a preferred embodiment of the present invention, preferably, the preparation method specifically includes the following steps:

[0048] (S1) Mix the copolymerized polypropylene, the homopolymerized polybutene-1, and the auxiliary agent, and then perform melt extrusion, cooling, strand drawing, and pelletizing to obtain blend microparticles;

[0049] (S2) Place the microparticles in a high-pressure reactor to contact with a foaming agent, heat, maintain the pressure, and then place the microparticles in the high-pressure reactor at atmospheric pressure at a set foaming pressure relief rate, and dehydrate and dry to obtain polypropylene alloy foaming beads;

[0050] (S3) Place the foaming beads in a molding die, introduce high-pressure steam, keep warm for a set time, and open the die to obtain a polypropylene alloy bead foaming material.

[0051] In the preparation method of the present invention, all raw materials can be commercially available products or prepared by any existing method.

[0052] According to the preparation method of the present invention, preferably, in step (S1), the weight ratio of the copolymerized polypropylene, the homopolymerized polybutene-1, and the auxiliary agent is 1:0.1-0.25:0.01-0.02, and further preferably 1:0.12-0.2:0.01-0.02.

[0053] According to the preparation method of the present invention, in order to make the obtained foaming material have a particle size suitable for steam molding, preferably, the length of the blend microparticles is 1.5-3 mm, the diameter is 1-1.5 mm, and the aspect ratio is 1.5-2.1.

[0054] According to the preparation method of the present invention, preferably, the foaming agent is selected from one or more of carbon dioxide, nitrogen, isobutene, and n-heptane; further preferably, the foaming agent is selected from one or more of carbon dioxide, nitrogen, and n-heptane.

[0055] According to the preparation method of the present invention, in step (S2), preferably, the conditions of the contact include: the foaming pressure is 0.5-2.5 MPa; the foaming temperature is 147-156 °C; maintain the pressure for 30-60 minutes.

[0056] Preferably, the foaming pressure relief rate is 0.1-1 MPa / min.

[0057] According to the preparation method of the present invention, preferably, in step (S3), the steam forming pressure is 0.21 - 0.25 MPa, and the forming heat preservation time is 45 - 60 s.

[0058] According to a preferred specific embodiment of the present invention, the preparation method specifically includes:

[0059] (S1) Mix copolymerized polypropylene, homopolymerized polybutene - 1 and additives in a high - speed mixer, then add them into a twin - screw extruder for melt extrusion, cooling, strand - drawing and pelletizing to obtain blend microparticles with a length of 1.5 - 3 mm, a diameter of 1 - 1.5 mm, and an aspect ratio of 1.5 - 2:1.

[0060] (S2) Place the blend microparticles obtained in (S1) in a high - pressure reactor, introduce a foaming agent, heat, and after reaching the set foaming temperature, maintain the pressure for a period of time, and then place the microparticles in the high - pressure reactor into the atmosphere at a set pressure - relief rate for dehydration and drying to obtain polypropylene alloy foamed beads.

[0061] (S3) Place the polypropylene alloy foamed beads obtained in (S2) in a forming mold, introduce high - pressure steam, keep warm for a set time, and open the mold to obtain a polypropylene alloy bead foamed material.

[0062] In the preparation method of the present invention, the polypropylene, polybutene - 1, and additives are the same as those described above, and will not be elaborated here.

[0063] The third aspect of the present invention provides a polypropylene alloy bead foamed material prepared by the preparation method described in the second aspect.

[0064] The fourth aspect of the present invention provides an application of the polypropylene alloy bead foamed material described in the first aspect or the third aspect in packaging, automobiles, household items or building materials.

[0065] The present invention will be described in detail below through examples.

[0066] In the following examples and comparative examples, the sources and performance parameters of the main raw materials are specifically as follows:

[0067] F03BT: Binary copolymerized polypropylene with butene - 1 as a comonomer, the butene - 1 content is 2.5 wt.%, produced by Zhenhai Refining and Chemical Company, China Petroleum and Chemical Corporation, melting point 155 °C, melt index 3.0 g / 10 min (230 °C / 2.16 kg), flexural modulus 1200 MPa.

[0068] W331: Binary copolymerized polypropylene with ethylene as comonomer, ethylene content 3.5 wt.%, from TPC in Singapore, melting point 148 °C, melt index 8.0 g / 10 min (230 °C / 2.16 kg), flexural modulus 1000 MPa;

[0069] E800E: Terpolymerized polypropylene, from Sinopec Shanghai Petrochemical Co., Ltd., melting point 142 °C, melt index 8.0 g / 10 min (230 °C / 2.16 kg), flexural modulus 700 PMa;

[0070] PBH-F01: High isotacticity homopolymer polybutene-1, from the 3000-ton / year high isotactic polybutene-1 industrial demonstration plant of Sinopec Ningbo New Materials Research Institute Co., Ltd., melt index 1.0 g / 10 min (190 °C / 2.16 kg), melting point 128 °C, isotacticity 98%, crystallinity 55%, modulus 600 MPa;

[0071] PBH-E04: Homopolymer polybutene-1, from the 3000-ton / year high isotactic polybutene-1 industrial demonstration plant of Sinopec Ningbo New Materials Research Institute Co., Ltd., melt index 3.5 g / 10 min (190 °C / 2.16 kg), melting point 130 °C, isotacticity 99%, crystallinity 65%, modulus 700 MPa;

[0072] PBR-F04: Copolymerized polybutene-1 with ethylene as the second monomer, from the 3000-ton / year high isotactic polybutene-1 industrial demonstration plant of Sinopec Ningbo New Materials Research Institute Co., Ltd., melt index 4.0 g / 10 min (190 °C / 2.16 kg), melting point 110 °C, crystallinity 40%, modulus 300 MPa;

[0073] LC175: Vinyl elastomer, from LG Chem in Korea, melt index 1.1 g / 10 min (190 °C / 2.16 kg), melting point 42 °C, crystallinity 11%, modulus 17 MPa;

[0074] 3980FL: Propylene elastomer, from ExxonMobil in the US, melt index 3.6 g / 10 min (190 °C / 2.16 kg), melting point 66 °C, crystallinity 14%, flexural modulus 110 MPa;

[0075] 7042: Linear low density polyethylene, from Zhenhai Refining & Chemical Co., Ltd., of Sinopec, melt index 2.0 g / 10 min (190 °C / 2.16 kg), melting point 124 °C, crystallinity 34%, flexural modulus 450 MPa.

[0076] In the preparation method of the present invention, the equipment and sources used for preparing the polypropylene alloy bead foaming material of the present invention are specifically as follows:

[0077] Autoclave pressure foaming equipment: Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences: self-developed;

[0078] Molding equipment: Suzhou Xinshun Machinery Co., Ltd.

[0079] The foamed beads are composed as shown in Table 1; the autoclave pressure foaming and molding process parameters are shown in Table 2; the density and properties of the foamed microparticles are shown in Table 3.

[0080] Example 1

[0081] This example is to illustrate the polypropylene alloy bead foaming material prepared by the present invention.

[0082] The formula of the foaming material includes:

[0083] Ethylene-based binary copolymerized polypropylene, W331, 100 parts by weight;

[0084] High isotactic homopolymer polybutene-1, PBH-E04, 12 parts by weight;

[0085] Auxiliaries: Antioxidant 1010 / 168, talcum powder and calcium stearate in total 2 parts by weight, wherein the weight ratio of the amounts of antioxidant 1010 / 168, talcum powder and calcium stearate is 1:0.5:0.5;

[0086] The specific preparation method is as follows:

[0087] (S1) Mix the above resins and auxiliaries in a high-speed mixer and then add them to a twin-screw extruder, melt extrude, cool, pelletize, and obtain blend microparticles with a length of 1.5 - 3 mm, a diameter of 1 - 1.5 mm, and a length-to-diameter ratio of 1.5 - 2:1;

[0088] (S2) Place the blend microparticles obtained in (S1) in a high-pressure reactor, introduce a foaming agent, heat, and after reaching the set foaming temperature, hold the pressure for a period of time, and then place the microparticles in the autoclave at atmospheric pressure at a set pressure relief rate, dehydrate and dry to obtain polypropylene alloy foamed beads;

[0089] (S3) Place the polypropylene alloy foamed beads obtained in (S2) in a molding die, introduce high-pressure steam, keep warm for a set time, and open the die to obtain a polypropylene alloy bead foaming material.

[0090] The foaming agent is n-heptane, the foaming pressure is 0.5 MPa, the foaming temperature is 147 °C, the pressure holding time is 30 min, the foaming pressure relief rate is 0.1 MPa / min, the steam molding pressure is 0.24 MPa, and the molding heat preservation time is 60 s.

[0091] Examples 2 - 3

[0092] This example is to illustrate the polypropylene alloy bead foaming material prepared by the present invention.

[0093] The polypropylene alloy bead foaming material was prepared in the same manner as in Example 1, except that: the formulation of the foaming material, the foaming agent, and the foaming conditions (steam molding conditions) were different, as specifically shown in Tables 1 and 2.

[0094] Comparative Examples 1-8

[0095] The polypropylene alloy bead foaming material was prepared in the same manner as in Example 1, except that: the formulation of the foaming material, the foaming agent, and the foaming conditions (steam molding conditions) were different, as specifically shown in Tables 1 and 2.

[0096] Table 1

[0097]

[0098]

[0099] Table 2

[0100]

[0101]

[0102] Test Example

[0103] The properties of the polypropylene alloy bead foaming materials prepared in Examples 1-3 and Comparative Examples 1-8 were tested, and the results are shown in Table 3:

[0104] Table 3

[0105]

[0106] It can be seen from Table 3 that:

[0107] Examples 1-3 have lower steam molding pressure and higher compressive strength, tensile strength, and hardness.

[0108] In Comparative Example 1, compared with Example 1, traditional terpolymerized polypropylene was used as the foaming substrate. Although the steam molding pressure was lower, the strength and hardness of the foaming material were insufficient.

[0109] In Comparative Example 2, copolymerized polypropylene with butene-1 as the second monomer, F03BT, was used without modification with homopolymerized polybutene-1. Compared with Example 2, the resulting foaming material had a higher steam molding pressure.

[0110] In Comparative Example 3, the addition amount of homopolymerized polybutene-1 was too large. Compared with Example 1, the strength and hardness of the resulting foaming material decreased significantly.

[0111] In Comparative Example 4, the addition amount of homopolymer polybutene-1 was too small. Compared with Example 3, the steam molding pressure of the obtained foamed material was too high.

[0112] In Comparative Example 5, linear low-density polyethylene was used to modify polypropylene. Due to insufficient stability of the material, compared with Example 1, the hardness and rigidity of the obtained foamed material were both smaller.

[0113] In Comparative Examples 6 and 7, vinyl elastomer or propylene-based elastomer was used to modify polypropylene. The crystallinity of the elastomer was relatively low, and the hardness of the material was too small. Compared with Example 1, the hardness and rigidity of the obtained foamed material were insufficient, and the steam molding pressure was relatively high.

[0114] In Comparative Example 8, polypropylene was modified with copolymer polybutene-1 with lower crystallinity and modulus. Compared with Comparative Example 1, the hardness and strength of the foamed material were lower.

[0115] It can be seen from the above examples and comparative examples that the copolymer polypropylene foamed material modified with homopolymer polybutene-1 of the present invention has a relatively low steam molding pressure, and at the same time can maintain the rigidity of the foamed material and has a high specific strength.

[0116] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A polypropylene alloy bead foaming material, characterized in that, the foaming material comprises a copolymerized polypropylene and a homopolymerized polybutene-1; wherein, relative to 100 parts by weight of the copolymerized polypropylene, the content of the homopolymerized polybutene-1 is 10-25 parts by weight.

2. The foaming material according to claim 1, wherein, relative to 100 parts by weight of the copolymerized polypropylene, the content of the homopolymerized polybutene-1 is 12-20 parts by weight.

3. The foaming material according to claim 1 or 2, wherein, the melting point of the homopolymerized polybutene-1 is 128-130 °C; preferably, the flexural modulus of the homopolymerized polybutene-1 is 600-700 MPa, and the crystallinity is 55-65%; preferably, the isotacticity of the homopolymerized polybutene-1 is greater than or equal to 98%, preferably greater than or equal to 99%; and / or, the melt index of the homopolymerized polybutene-1 at 190 °C and 2.16 kg is 1-4 g / 10 min.

4. The foaming material according to claim 1 or 2, wherein, the copolymerized polypropylene is a binary copolymerized polypropylene, and the second comonomer is ethylene or butene-1. Based on the total weight of the binary copolymerized polypropylene, the content of ethylene is 2-3.5 wt.% or the content of butene-1 is 2-5.5 wt.%; preferably, the melting point of the copolymerized polypropylene is 148-155 °C; preferably, the flexural modulus of the copolymerized polypropylene is 1000-1200 MPa; and / or, the melt index of the copolymerized polypropylene at 230 °C and 2.16 kg is 3-10 g / 10 min.

5. The foaming material according to any one of claims 1-4, wherein, the foaming material further comprises an additive; preferably, the additive includes an antioxidant, a nucleating agent and an acid scavenger; preferably, the weight ratio of the antioxidant, the nucleating agent and the acid scavenger is 1:(0.1-2):(0.1-2); preferably 1:(0.5-1.5):(0.5-1.5); preferably, the antioxidant is selected from at least one of phosphite antioxidants, hindered amine antioxidants and hindered phenol antioxidants; preferably, the nucleating agent is selected from at least one of zinc borate, montmorillonite, talc, nano-clay, kaolin; preferably, the acid scavenger is selected from at least one of hydrotalcite, calcium stearate and zinc stearate; preferably, relative to 100 parts by weight of the copolymerized polypropylene, the content of the additive is 1-2 parts by weight.

6. The foaming material according to any one of claims 1-5, wherein, the steam forming pressure of the foaming material is 0.21-0.25 MPa; preferably, when the density of the foaming material is 0.100 ± 0.003 g / mL, the Shore hardness AO of the foaming material is greater than 85°, the 50% compressive strength is greater than 0.75 MPa, and the tensile strength is greater than 1.9 MPa; preferably, when the density of the foaming material is 0.05 ± 0.002 g / mL, the Shore hardness AO of the foaming material is greater than 70°, the 50% compressive strength is greater than 0.4 MPa, and the tensile strength is greater than 1.1 MPa; Preferably, when the density of the foaming material is 0.033 ± 0.002 g / mL, the Shore hardness AO of the foaming material is greater than 62°, the 50% compressive strength is greater than 0.3 MPa, and the tensile strength is greater than 0.8 MPa; Preferably, the density of the foaming material is 0.100 - 0.032 g / mL.

7. A method for preparing a polypropylene alloy bead foaming material, characterized in that, the preparation method includes: physically foaming a copolymerized polypropylene, a homopolymerized polybutene-1 and an auxiliary agent.

8. According to the preparation method of claim 7, the preparation method specifically includes: (S1) Mixing the copolymerized polypropylene, the homopolymerized polybutene-1 and the auxiliary agent, followed by melt extrusion, cooling, strand drawing, and pelletizing to obtain blend microparticles; (S2) Placing the microparticles in a high-pressure reactor to contact with a foaming agent, heating, maintaining pressure, and then placing the microparticles in the high-pressure reactor into the atmosphere at a set foaming pressure relief rate, dehydrating and drying to obtain polypropylene alloy foamed beads; (S3) Placing the foamed beads in a molding die, introducing high-pressure steam, maintaining the temperature for a set time, and opening the die to obtain a polypropylene alloy bead foaming material.

9. According to the preparation method of claim 8, wherein, in step (S1), the weight ratio of the copolymerized polypropylene, the homopolymerized polybutene-1, and the auxiliary agent is 1: 0.1 - 0.25: 0.01 - 0.02, preferably 1: 0.12 - 0.2: 0.01 - 0.02; Preferably, the length of the blend microparticles is 1.5 - 3 mm, the diameter is 1 - 1.5 mm, and the aspect ratio is 1.5 - 2.1; Preferably, the copolymerized polypropylene is a binary copolymerized polypropylene, and the second comonomer is ethylene or butene-1; Preferably, the melting point of the copolymerized polypropylene is 148 - 155 °C; Preferably, the flexural modulus of the copolymerized polypropylene is 1000 - 1200 MPa; Preferably, the melt index of the copolymerized polypropylene at 230 °C and 2.16 kg is 3 - 10 g / 10 min; Preferably, the melting point of the homopolymerized polybutene-1 is 128 - 130 °C; Preferably, the flexural modulus of the homopolymerized polybutene-1 is 600 - 700 MPa, and the crystallinity is 55 - 65%; Preferably, the isotacticity of the homopolymerized polybutene-1 is greater than or equal to 98%, preferably greater than or equal to 99%; Preferably, the melt index of the homopolymerized polybutene-1 at 190 °C and 2.16 kg is 1 - 4 g / 10 min; Preferably, the auxiliary agent is a mixture of an antioxidant, a nucleating agent, and an acid scavenger; Preferably, the weight ratio of the antioxidant, the nucleating agent, and the acid scavenger is 1: (0.1 - 2): (0.1 - 2); preferably 1: (0.5 - 1.5): (0.5 - 1.5); Preferably, the antioxidant is selected from at least one of phosphite antioxidants, hindered phenol antioxidants, and hindered amine antioxidants; Preferably, the nucleating agent is selected from at least one of zinc borate, montmorillonite, talc, nano-clay, and kaolin; Preferably, the acid scavenger is selected from at least one of hydrotalcite, calcium stearate, and zinc stearate.

10. The preparation method according to claim 8, wherein, in step (S2), the blowing agent is selected from one or more of carbon dioxide, nitrogen, isobutene and n-heptane; and / or, the conditions of the contact include: the foaming pressure is 0.5 - 2.5 MPa; the foaming temperature is 147 - 156 °C; the pressure is maintained for 30 - 60 min; and / or, the foaming pressure relief rate is 0.1 - 1 MPa / min.

11. The preparation method according to any one of claims 8 - 10, wherein, in step (S3), the steam molding pressure is 0.21 - 0.25 MPa, and the molding heat preservation time is 45 - 60 s.

12. A polypropylene alloy bead foaming material prepared by the preparation method according to any one of claims 7 - 11.

13. An application of the polypropylene alloy bead foaming material according to any one of claims 1 - 6 and 12 in packaging, automobiles, household or building materials.

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