A novel polypropylene foaming material and a preparation method and application thereof

Abstract

The application belongs to the technical field of polyolefin foaming materials, and particularly relates to a novel polypropylene foaming material and a preparation method and application thereof. The material raw materials include, in terms of weight parts, 60-90 parts of random copolymerized polypropylene, 10-35 parts of polybutene, 1-5 parts of friction resistance aid, 0.5-3 parts of compatilizer, 0.1-0.5 parts of cell regulator. The novel polypropylene foaming material has excellent ultraviolet resistance, a yellowing resistance grade of 4 or more, a bonding strength of 1.3 MPa or more, and a friction resistance of delta L of 1.1 or less, and can be applied to the field of foaming materials for outdoor structures.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of polyolefin foaming materials, and particularly relates to a novel polypropylene foaming material and a preparation method and application thereof. BACKGROUND

[0002] The polypropylene foaming material maintains the excellent performance of polypropylene, can reduce weight, has good physical performance, thermal performance and recyclability, can be widely used in interior parts of automobiles, sound insulation and heat insulation parts, and can also be used in packaging materials of food, cosmetics and electronic products. The heat-resistant temperature of foaming PS is 80℃, the heat-resistant temperature of foaming PE is only 70-80℃, and the heat-resistant temperature of foaming PP can be as high as 120℃. The size shrinkage rate of foaming PP material is only 2% after being placed at 120℃ for 22 hours, so the foaming PP material is more suitable for use in high-temperature occasions. In addition, polypropylene has low water absorption, good insulation, good chemical stability and low dielectric constant.

[0003] At the same time, polystyrene foam material uses alkanes as a foaming agent, which is not conducive to environmental protection and is difficult to recycle. On the other hand, plastic foam made of polyurethane produces some toxic substances in the foaming process, and polyurethane foam material cannot be recycled, so compared with the above two, polypropylene foam plastic has obvious advantages. The polypropylene carbon dioxide foaming technology will gradually replace traditional polyethylene, polystyrene and polyurethane foam plastic due to its green, pollution-free and recyclable characteristics.

[0004] However, the polypropylene foaming material also has problems in application, such as poor ultraviolet aging resistance, poor wear resistance, short service life and poor bonding strength. For example, the ultraviolet resistance is poor, the service life is short when used outdoors, the main reason is that under the combined action of light, oxygen and heat, the polypropylene molecules undergo beta bond rupture, producing alkyl radicals, hydroxyl radicals and peroxides, causing molecular chain segment to decompose; the friction coefficient of random copolymer polypropylene is large, so the resistance to friction and scratch is poor. In the application process of polypropylene foaming material in offshore buoy, the polypropylene foaming material is worn or defective due to the impact of ocean tides and marine organisms such as fish, shrimps and crabs, reducing the service life of the product.

[0005] At present, the ultraviolet resistance of polypropylene is mainly improved by using ultraviolet absorbers or hindered amine light stabilizers, but the ultraviolet absorbers and hindered amine light stabilizers are organic small molecules, which have the disadvantages of easy volatilization and easy degradation. The wear resistance of polypropylene material is mainly improved by adding metal oxides and mineral powders, but for polypropylene foaming material, excessive addition of metal oxides or mineral powders will have adverse effects on the nucleation, growth and uniform distribution of the cells. SUMMARY

[0006] To address the above technical problems, this invention provides a novel polypropylene foam material, its preparation method, and its application. This EPP foam material has excellent UV resistance, high bonding strength, and good friction resistance. Furthermore, due to the presence of polybutene components, steam molding energy consumption is reduced, the material has low shrinkage, and the cell size and perforation distribution are uniform. It is a functional polymer foam material with excellent comprehensive performance.

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

[0008] A novel polypropylene foam material, by weight, comprises the following raw materials:

[0009]

[0010] Preferably, the friction-resistant agent is one or more of polyphenylene sulfide, polyketone, and benzoxazine. Polyphenylene sulfide, polyketone, and benzoxazine are high molecular weight polymers with good friction resistance. Compared with inorganic friction-resistant agents, they have better compatibility with the system. During the melting process, the high molecular weight polymers physically entangle with polypropylene and polybutene segments to form a spatial network structure. During the foaming process, this helps to improve the stability of the cell structure skeleton and makes it less likely for cell merging and collapse to occur, thereby enhancing the mechanical properties of the foamed material.

[0011] Preferably, the random copolymer polypropylene is one or more of ethylene-propylene copolymer polypropylene, propylene-butadiene copolymer polypropylene, and ethylene-propylene-butadiene copolymer polypropylene, and the number average molecular weight of the random copolymer polypropylene is 6 to 12 × 10⁻⁶. 4 The melt flow index is 6–10 g / 10 min. Random copolymer polypropylene is a copolymer of polypropylene monomers with polyethylene monomers or polybutene monomers. It has a wide molecular weight distribution and a wide melting range. In the autoclave foaming process, the lower melting point portion acts as the foaming phase, while the higher melting point portion acts as the structural phase to support the cells. Single homopolymer polypropylene has a narrow molecular weight distribution and a short melting range. When the foaming temperature is below the melting point, the cell growth resistance is large. When the foaming temperature rises, the melt strength drops sharply, and the cells rupture and collapse, making it difficult to achieve foaming.

[0012] Preferably, the number-average molecular weight of polybutene is 6–15 × 10⁻⁶. 4 The melt flow index is 0.5–2.5 g / 10 min.

[0013] Preferably, the compatibilizer is one or more of maleic anhydride-grafted polypropylene, acrylic acid-grafted polypropylene, and epoxy resin-grafted polypropylene; the compatibilizer mainly improves the compatibility between polypropylene and polybutene and the friction-resistant additives. Compared with other compatibilizers in the prior art, the compatibilizer of the present invention has a good effect on improving compatibility.

[0014] Preferably, the pore-forming agent is one or more of calcium carbonate, talc, kaolin, montmorillonite, and silica.

[0015] Preferably, the polybutene component has a crystal form of crystal form I'.

[0016] Preferably, the foamed material has a bimodal melt curve, a yellowing resistance grade of 4 or higher, a bond strength of ≥1.3MPa, and a friction resistance ΔL≤1.1.

[0017] Polybutene is a high-molecular-weight inert polymer material, formed by the stereopolymerization of 1-butene monomers. Its molecular chain has a linear structure, making it less prone to β-bond breakage compared to polypropylene, thus exhibiting excellent resistance to UV aging. In blends, polybutene exists in crystal form I', which has a smaller grain size. These smaller polybutene grains fill the gaps between larger polypropylene grains, resulting in a denser structure and reducing the reactive free radicals generated by the combined effects of sunlight, oxygen, and heat, further enhancing its UV aging resistance. Due to the good compatibility between polybutene and polypropylene, using polybutene to replace UV absorbers and light stabilizers to improve the UV aging resistance of polypropylene also provides other benefits. Polybutene possesses good impact resistance and can improve the toughness of polypropylene.

[0018] A method for preparing a novel polypropylene foam material includes the following steps:

[0019] S1. Random copolymer polypropylene, polybutene, abrasion resistant agent, compatibilizer, and cell regulator are mixed evenly and then extruded and granulated using a twin-screw extruder.

[0020] S2. The pre-foamed polypropylene particles obtained in step S1 are put into a high-pressure reaction vessel. After the temperature is constant, carbon dioxide fluid at a certain pressure is injected into the vessel. After maintaining the pressure for a period of time, the pressure is quickly released to obtain EPP primary foamed beads.

[0021] S3. The EPP primary foamed beads obtained in step S2 are pressurized with air and then fed into a secondary foaming machine to obtain EPP secondary foamed beads through steam foaming.

[0022] S4. The EPP secondary foamed beads obtained in step S3 are steam molded and cured to obtain UV-resistant high bonding strength EPP foam material.

[0023] Preferably, in step S2, the temperature range of the reaction vessel is 135℃~155℃, the carbon dioxide holding pressure is 1.5~4.5MPa, and the holding time is 10~60min; in step S3, the air carrier pressure is 0.4~1.0MPa, and the temperature control of the secondary foaming machine is 70~130℃; in step S4, the steam forming pressure is 1.2~3.5bar.

[0024] The crystallization temperature of polypropylene is 90–120℃, while that of polybutene is 50–80℃. Polypropylene has a faster crystallization rate, which has a certain inducing effect on the formation of polybutene crystal form. In the blend, polypropylene grains form and grow rapidly. Due to the steric hindrance effect, polybutene can only form smaller crystal form I', which inhibits the formation of polybutene crystal form II. Polybutene crystal form I' is a stable crystal form with a melting point of 95–105℃. Because polybutene crystal form I' has a low melting point, during the steam molding process of the extruded foam beads, the polybutene partially softens, forming adhesive bridges between polypropylene molecules. This enhances the adhesive strength of the EPP foam material. When EPP bead steam-molded products are damaged by external forces during use, the interface of the foam beads is the potential path for fracture. The adhesion condition at the bead interface determines the mechanical properties of the molded product, which in turn determines the number of reusables and the service life of the molded product. If the adhesive strength is low, fracture usually occurs at the bead interface. If the adhesive strength is high, the foam material can absorb more mechanical energy, thus ensuring the integrity of the entire product and extending its service life. At the same time, it allows for lower steam pressure, reducing the steam molding pressure by 0.5 to 1.5 bar, saving 5 tons of steam per ton of product, and reducing production costs by 1 / 4 to 1 / 3, which is beneficial for saving steam costs.

[0025] The application of the UV-resistant, high-adhesion-strength EPP product of this invention in the preparation of foamed materials for outdoor structures, such as marine buoys, 5G antenna covers, wind turbine blades, and external wall insulation materials.

[0026] The EPP product of this invention has excellent UV resistance, high bonding strength, and good abrasion resistance, which can solve the problems of poor UV resistance, short service life, and easy cracking and damage encountered by existing EPP foam materials during outdoor use.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] 1. This invention uses polybutene to replace organic small molecule ultraviolet absorbers and light stabilizers to enhance the UV aging resistance of polypropylene. Polybutene is a high molecular weight inert polymer whose chain segments are not easily β-degraded. At the same time, by utilizing the inductive effect and steric hindrance effect of the crystal formation process between polypropylene and polybutene, the bonding between different types of crystal grains is made more compact and perfect, reducing the defect of large porosity between polypropylene particles and further enhancing the UV aging resistance of EPP products.

[0029] 2. This invention uses polyphenylene sulfide, polyketone, or benzoxazine polymers as abrasion-resistant additives. Compared with inorganic abrasion-resistant agents, these additives have better compatibility with the system. During the melting process, the polymers physically entangle with polypropylene and polybutene segments to form a spatial network structure. During the foaming process, this helps to improve the stability of the cell structure skeleton and makes it less likely for cell merging and collapse to occur. This, in turn, helps to enhance the mechanical properties of the foamed material and extend its service life.

[0030] 3. In this invention, the polybutene phase exists in the form of polybutene crystal form I', which has a lower melting point. During the steam molding process of the extruded foamed beads of the blend, the polybutene partially softens and forms adhesive bridges between polypropylene molecules, which enhances the adhesive strength of the EPP product, improves the mechanical properties of the molded product, and extends its service life. At the same time, the steam pressure is lower, which helps to save steam energy consumption and reduce production costs.

[0031] 4. The EPP foam material of the present invention has excellent UV resistance, yellowing resistance grade 4 or above, bonding strength ≥1.3MPa, and abrasion resistance ΔL≤1.1. It can be applied to marine buoys, 5G antenna covers, wind turbine blades, external wall insulation materials and other fields. It can solve the problems of poor UV resistance, short service life and easy cracking and damage encountered by existing EPP foam materials in outdoor use. Attached Figure Description

[0032] Figure 1 The image shows a SEM image of the EPP foam material prepared in Example 1. Detailed Implementation

[0033] The present invention will be further illustrated below through embodiments. These embodiments are only examples of a part of the present invention and not the entire scope. Any changes to parameters, optimization of process conditions, or substitution of some raw materials made without departing from the principle of the present invention are all within the protection scope of the present invention.

[0034] In this embodiment, the weight of each component can be determined as 1 to 1000 kg / component, depending on the specifications and production capacity of the equipment.

[0035] The following raw materials include, but are not limited to, those from the manufacturer and brand name: Polyphenylene sulfide, Toray Industries, Ltd. A604; Polyketone, Hyosung Group, Korea M710F; Benzooxazine, Puyang Enwin Polymer Materials Co., Ltd. BZ5400; Maleic anhydride-grafted polypropylene, Co., Ltd. B1.

[0036] The acrylic acid-grafted polypropylene and epoxy resin-grafted polypropylene described below can be prepared by the following methods, or by other preparation methods disclosed in the prior art.

[0037] Preparation method of acrylic acid grafted polypropylene:

[0038] Five parts of acrylic acid, 100 parts of polypropylene resin (T30S), 0.5 parts of bis-tert-butyl peroxide (BIPB), and 0.3 parts of zinc dimethyl dithiocarbamate were mixed evenly and then melt-extruded through a twin-screw extruder to obtain an acrylic acid-grafted polypropylene product. The extruder melt zone temperature was 200℃ and the main extruder speed was 240 r / min.

[0039] Preparation method of epoxy resin grafted polypropylene:

[0040] Five parts of glycidyl methacrylate, 100 parts of polypropylene resin (T30S), 0.5 parts of bis-tert-butyl peroxide (BIPB), and 0.3 parts of zinc dimethyl dithiocarbamate were mixed evenly and then melt-extruded through a twin-screw extruder to obtain an epoxy resin grafted polypropylene product. The extruder melt zone temperature was 200℃ and the main extruder speed was 240 r / min.

[0041] Example 1

[0042] A novel method for preparing polypropylene foam material:

[0043] (1) 80 parts of random copolymer polypropylene, 20 parts of polybutene, 2 parts of polyphenylene sulfide, 1 part of maleic anhydride-grafted polypropylene, and 0.15 parts of calcium carbonate (D97≤5μm) were mixed in a high-speed mixer and then granulated by twin-screw extrusion. The melting temperature of the extruder was 200℃. The number average molecular weight of the random copolymer polypropylene was 8×10⁻⁶. 4 The melt index is 6.5 g / 10 min, and the number-average molecular weight of polybutene is 12 × 10⁻⁶. 4 The melt flow index is 1.5 g / 10 min;

[0044] (2) The pre-foamed polypropylene particles obtained in step S1 are put into a high-pressure reactor. After the temperature is kept constant at 146°C, 2.5 MPa of carbon dioxide fluid is injected into the reactor. After maintaining the pressure for 30 minutes, the pressure is quickly released through the pressure relief valve to obtain EPP primary foamed beads.

[0045] (3) The EPP primary foaming beads obtained in step S2 are fed into a secondary foaming machine after being pressurized with air at 0.4 MPa. The EPP secondary foaming beads are obtained by steam foaming. The temperature of the secondary foaming agent is controlled at 90°C.

[0046] (4) The EPP secondary foamed beads obtained in step S3 are steam molded on a steam molding equipment at a molding pressure of 2.0 bar. After curing, a UV-resistant, high-adhesion-strength, low-friction EPP foam material is obtained.

[0047] Example 2

[0048] A novel method for preparing polypropylene foam material:

[0049] (1) 75 parts of random copolymer polypropylene, 25 parts of polybutene, 3 parts of polyphenylene sulfide, 1 part of acrylic acid-grafted polypropylene, and 0.2 parts of kaolin (D97≤5μm) were mixed in a high-speed mixer and then granulated by twin-screw extrusion. The melt temperature of the extruder was 195℃. The number average molecular weight of the random copolymer polypropylene was 9.5×10⁻⁶. 4 The melt index is 7.5 g / 10 min, and the number average molecular weight of polybutene is 10 × 10⁻⁶. 4 The melt flow index is 1.8 g / 10 min;

[0050] (2) The pre-foamed polypropylene particles obtained in step S1 are put into a high-pressure reactor. After the temperature is kept constant at 142°C, 3.5 MPa of carbon dioxide fluid is injected into the reactor. After maintaining the pressure for 20 minutes, the pressure is quickly released through the pressure relief valve to obtain EPP primary foamed beads.

[0051] (3) The EPP primary foaming beads obtained in step S2 are fed into a secondary foaming machine after being pressurized with air at 0.5 MPa. The EPP secondary foaming beads are obtained by steam foaming. The temperature of the secondary foaming agent is controlled at 100℃.

[0052] (4) The EPP secondary foamed beads obtained in step S3 are steam molded on a steam molding equipment at a molding pressure of 2.2 bar. After curing, a UV-resistant, high-adhesion-strength, low-friction EPP foam material is obtained.

[0053] Example 3

[0054] A novel method for preparing polypropylene foam material:

[0055] (1) 70 parts of random copolymer polypropylene, 30 parts of polybutene, 2.5 parts of benzoxazine, 1.5 parts of epoxy resin grafted polypropylene, and 0.25 parts of montmorillonite (D97≤5μm) were mixed in a high-speed mixer and then granulated by twin-screw extrusion. The melting temperature of the extruder was 190℃. The number average molecular weight of the random copolymer polypropylene was 12×10⁻⁶. 4 The melt index is 8.5 g / 10 min, and the number-average molecular weight of polybutene is 11 × 10⁻⁶. 4 The melt flow index is 2.0 g / 10 min;

[0056] (2) The pre-foamed polypropylene particles obtained in step S1 are put into a high-pressure reactor. After the temperature is kept constant at 148°C, 1.5 MPa of carbon dioxide fluid is injected into the reactor. After maintaining the pressure for 35 minutes, the pressure is quickly released through the pressure relief valve to obtain EPP primary foamed beads.

[0057] (3) The EPP primary foaming beads obtained in step S2 are fed into a secondary foaming machine after being pressurized with air at 0.7MPa. The EPP secondary foaming beads are obtained by steam foaming. The temperature of the secondary foaming agent is controlled at 70℃.

[0058] (4) The EPP secondary foamed beads obtained in step S3 are steam molded on a steam molding equipment at a molding pressure of 1.8 bar. After curing, a UV-resistant, high-adhesion-strength, low-friction EPP foam material is obtained.

[0059] Example 4

[0060] A novel method for preparing polypropylene foam material:

[0061] (1) 90 parts of random copolymer polypropylene, 10 parts of polybutene, 5 parts of polyketone, 2 parts of maleic anhydride-grafted polypropylene, and 0.2 parts of talc (D97≤5μm) were mixed in a high-speed mixer and then granulated by twin-screw extrusion. The melt temperature of the extruder was 205℃. The number average molecular weight of the random copolymer polypropylene was 8.5×10⁻⁶. 4 The melt index is 9.5 g / 10 min, and the number-average molecular weight of polybutene is 14 × 10⁻⁶. 4 The melt flow index is 0.5 g / 10 min;

[0062] (2) The pre-foamed polypropylene particles obtained in step S1 are put into a high-pressure reactor. After the temperature is kept constant at 140°C, 3.5 MPa of carbon dioxide fluid is injected into the reactor. After maintaining the pressure for 20 minutes, the pressure is quickly released through the pressure relief valve to obtain EPP primary foamed beads.

[0063] (3) The EPP primary foaming beads obtained in step S2 are fed into a secondary foaming machine after being pressurized with air at 0.6 MPa. The EPP secondary foaming beads are obtained by steam foaming. The temperature of the secondary foaming agent is controlled at 110℃.

[0064] (4) The EPP secondary foamed beads obtained in step S3 are steam molded on a steam molding equipment at a molding pressure of 2.0 bar. After curing, a UV-resistant, high-adhesion-strength, low-friction EPP foam material is obtained.

[0065] Comparative Example 1

[0066] A novel method for preparing polypropylene foam material:

[0067] (1) 100 parts of random copolymer polypropylene, 2 parts of polyphenylene sulfide, 1 part of maleic anhydride-grafted polypropylene, and 0.15 parts of calcium carbonate (D97≤5μm) were mixed in a high-speed mixer and then granulated by twin-screw extrusion. The melting temperature of the extruder was 200℃. The number average molecular weight of the random copolymer polypropylene was 8×10⁻⁶. 4 The melt flow index is 6.5 g / 10 min;

[0068] (2) The pre-foamed polypropylene particles obtained in step S1 are put into a high-pressure reactor. After the temperature is kept constant at 146°C, 2.5 MPa of carbon dioxide fluid is injected into the reactor. After maintaining the pressure for 30 minutes, the pressure is quickly released through the pressure relief valve to obtain EPP primary foamed beads.

[0069] (3) The EPP primary foaming beads obtained in step S2 are fed into a secondary foaming machine after being pressurized with air at 0.4 MPa. The EPP secondary foaming beads are obtained by steam foaming. The temperature of the secondary foaming agent is controlled at 90℃.

[0070] (4) The EPP secondary foamed beads obtained in step S3 are steam molded on a steam molding equipment at a molding pressure of 3.0 bar. After curing, EPP foam material is obtained.

[0071] Comparative Example 2

[0072] A novel method for preparing polypropylene foam material:

[0073] (1) 80 parts of random copolymer polypropylene, 20 parts of polybutene, 1 part of maleic anhydride-grafted polypropylene, and 0.15 parts of calcium carbonate (D97≤5μm) were mixed in a high-speed mixer and then granulated by twin-screw extrusion. The melting temperature of the extruder was 200℃. The number average molecular weight of the random copolymer polypropylene was 8×10⁻⁶. 4 The melt index is 6.5 g / 10 min, and the number-average molecular weight of polybutene is 12 × 10⁻⁶. 4 The melt flow index is 1.5 g / 10 min;

[0074] (2) The pre-foamed polypropylene particles obtained in step S1 are put into a high-pressure reactor. After the temperature is kept constant at 146°C, 2.5 MPa of carbon dioxide fluid is injected into the reactor. After maintaining the pressure for 30 minutes, the pressure is quickly released through the pressure relief valve to obtain EPP primary foamed beads.

[0075] (3) The EPP primary foaming beads obtained in step S2 are fed into a secondary foaming machine after being pressurized with air at 0.4 MPa. The EPP secondary foaming beads are obtained by steam foaming. The temperature of the secondary foaming agent is controlled at 90℃.

[0076] (4) The EPP secondary foamed beads obtained in step S3 are steam molded on a steam molding equipment at a molding pressure of 2.0 bar. After curing, EPP foam material is obtained.

[0077] Comparative Example 3

[0078] A method for preparing a novel polypropylene foam material:

[0079] Comparative Example 3 illustrates the process of obtaining EPP foam material from ordinary polypropylene through primary foaming, secondary foaming, and steam molding.

[0080] (1) 100 parts of polypropylene (Yanshan Petrochemical polypropylene B5008M) and 0.5 parts of calcium carbonate (D97≤5μm) were mixed in a high-speed mixer and then granulated by twin-screw extrusion. The temperature of the melting section of the extruder was 200℃.

[0081] (2) The pre-foamed polypropylene particles obtained in step S1 are put into a high-pressure reactor. After the temperature is kept constant at 146°C, 2.5 MPa of carbon dioxide fluid is injected into the reactor. After maintaining the pressure for 30 minutes, the pressure is quickly released through the pressure relief valve to obtain EPP primary foamed beads.

[0082] (3) The EPP primary foaming beads obtained in step S2 are fed into a secondary foaming machine after being pressurized with air at 0.8 MPa. The EPP secondary foaming beads are obtained by steam foaming. The temperature of the secondary foaming agent is controlled at 90℃.

[0083] (4) The EPP secondary foamed beads obtained in step S3 are steam molded on a steam molding equipment at a molding pressure of 3.0 bar. After curing, EPP foam material is obtained.

[0084] Test case

[0085] The performance of the EPP foam materials prepared in the examples and comparative examples was tested, and the test results are shown in Table 1 below:

[0086] Yellowing resistance rating: The UV resistance and aging resistance of foamed materials are evaluated using a gray scale according to standard ISO105 / A02.

[0087] Bond strength: According to standard QB / T 4878-2015, the EPP foam product is cut into standard dumbbell-shaped strips, and the tensile strength of the material is tested. The strength of the bond is judged by the tensile strength value.

[0088] Scratch resistance: The scratch resistance of the material is tested by evaluating the ΔL after scratching according to standard PV3952 with a load of 10N.

[0089] Table 1. Performance test data of EPP foam materials prepared in the examples and comparative examples.

[0090] Yellowness resistance rating Adhesion strength (MPa) Friction resistance ΔL Example 1 5 1.42 1.1 Example 2 5 1.35 1.0 Example 3 5 1.53 0.9 Example 4 5 1.57 1.0 Comparative Example 1 3 0.87 1.0 Comparative Example 2 5 1.12 2.3 Comparative Example 3 3 0.79 2.5

[0091] The test data in the table show that, compared with the examples, Comparative Example 1, without the addition of polybutene, exhibits significantly lower yellowing resistance and bond strength; Comparative Example 2, without the addition of abrasion-resistant additives, shows significantly lower bond strength and abrasion resistance; Comparative Example 3, as a conventional polypropylene foam abrasion material, shows far inferior yellowing resistance, bond strength, and abrasion resistance compared to the examples. The EPP product prepared by this invention has a yellowing resistance grade of 5, a high bond strength ≥1.5, and an abrasion resistance ≤1.1.

[0092] The EPP product prepared by this invention has excellent UV resistance, high bonding strength, and good friction resistance. It is a functional polymer foam material with excellent comprehensive performance. It can solve the problems of poor UV resistance, short service life, and easy cracking and damage encountered by existing EPP products during outdoor use. It can be applied to fields such as marine buoys, 5G antenna covers, wind turbine blades, and external wall insulation materials.

Claims

1. A novel polypropylene foam material, characterized in that, By weight, the raw materials include: Random copolymer polypropylene 60-90 parts; 10-35 parts of polybutene; 1-3 parts of abrasion-resistant additive; Compatibilizer 0.5-3 parts; 0.1-0.5 parts of bubble conditioner; The friction-resistant additive is one or two of polyphenylene sulfide and benzoxazine; The random copolymer polypropylene is one or more of ethylene-propylene copolymer polypropylene, propylene-butadiene copolymer polypropylene, and ethylene-propylene-butadiene copolymer polypropylene, and the number average molecular weight of the random copolymer polypropylene is 6-12×10⁻⁶. 4 The melt flow index is 6-10 g / 10 min; The polybutene has a number-average molecular weight of 6-15×10⁻⁶. 4 The melt flow index is 0.5-2.5 g / 10 min; The polybutene has a crystal form of I'.

2. The novel polypropylene foam material according to claim 1, characterized in that, The compatibilizer is one or more of maleic anhydride-grafted polypropylene, acrylic acid-grafted polypropylene, and epoxy resin-grafted polypropylene.

3. The novel polypropylene foam material according to claim 1, characterized in that, The pore-forming agent is one or more of calcium carbonate, talc, kaolin, montmorillonite, and silica.

4. The novel polypropylene foam material according to claim 1, characterized in that, The foamed material has a bimodal melt curve, a yellowing resistance grade of 4 or higher, a bond strength of ≥1.3MPa, and a friction resistance ΔL≤1.

1.

5. A method for preparing a novel polypropylene foam material according to any one of claims 1-4, characterized in that, Includes the following steps: S1. Random copolymer polypropylene, polybutene, abrasion resistant agent, compatibilizer, and cell regulator are mixed evenly and then extruded and granulated by a twin-screw extruder. S2. The pre-foamed polypropylene particles obtained in step S1 are put into a high-pressure reaction vessel. After the temperature is constant, a certain pressure of carbon dioxide fluid is injected into the vessel. After maintaining the pressure for a period of time, the pressure is quickly released to obtain EPP primary foamed beads. S3. The EPP primary foamed beads obtained in step S2 are pressurized with air and then fed into a secondary foaming machine to obtain EPP secondary foamed beads through steam foaming. S4. The EPP secondary foamed beads obtained in step S3 are steam molded and cured to obtain UV-resistant high bonding strength EPP foam material.

6. The method for preparing a novel polypropylene foam material according to claim 5, characterized in that, In step S2, the temperature range of the reaction vessel is 135℃~155℃, the carbon dioxide holding pressure is 1.5-4.5MPa, and the holding time is 10-60min; in step S3, the air carrier pressure is 0.4-1.0MPa, and the temperature control of the secondary foaming machine is 70-130℃; in step S4, the steam forming pressure is 1.2-3.5bar.

7. The application of any novel polypropylene foam material as described in claims 1-4 in the preparation of foam materials for outdoor structures.

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