A polyolefin resin composition, a method for producing the same, a polyolefin expanded bead, and a polyolefin molded body

Abstract

The application belongs to the technical field of high polymer materials, and discloses a polyolefin resin composition, a preparation method thereof, polyolefin foaming beads and a polyolefin molded body. The composition contains polyolefin, Janus sheets and optional functional additives. The thickness of the Janus sheets is less than or equal to 200 nm, and the cross-sectional side length is 100 nm to 2000 nm. The content of the Janus sheets is 0.008 to 0.1 parts by weight, and the content of the functional additives is 0 to 1 parts by weight, based on 100 parts by weight of the polyolefin. The composition has lower zero shear viscosity. The polyolefin foaming beads prepared by the composition have excellent cell structure, and the accumulation of the Janus sheets can be observed on the cell wall section, thereby playing a supporting and reinforcing role on the cells. The molded body prepared by the composition has excellent tensile properties, compression properties and thermal insulation properties.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of high polymer materials, and particularly relates to a polyolefin resin composition and a preparation method thereof, a polyolefin foamed bead and a polyolefin molded body. BACKGROUND

[0002] Polyolefin foamed materials have many advantages such as light weight, high strength, heat resistance and corrosion resistance, heat and shock insulation, sound absorption, multiple reuse, adjustable open and closed porosity, and green and environmentally friendly production process. The biggest advantage of autoclave foaming polyolefin beads (EPO beads) in application is its free formability. The uniform size and stable foaming ratio of EPO beads make them very suitable for molding, and products with complex geometric structures and high dimensional accuracy can be produced, which are mainly used in high-end markets.

[0003] In practical applications, the most concerned performance of polyolefin foamed beads and their molded bodies for downstream manufacturers and main machine manufacturers is their cushioning performance, which is often represented by the compression strength of foamed materials. Many institutions have carried out work to improve the mechanical properties such as compression strength of polyolefin foamed beads and molded products.

[0004] The autoclave foaming process is to immerse carbon dioxide foaming agent into molten / semi-molten polyolefin microparticles. With the increase of pressure and immersion time, carbon dioxide is dispersed in the melt to form a "homogeneous system". When the pressure is rapidly released and discharged, the phase transition and volume expansion of carbon dioxide occur, thereby obtaining autoclave foamed beads with full external appearance and uniform and delicate internal cells. The cell density, size, wall thickness, uniformity, open and closed porosity, and foaming ratio of polyolefin foamed materials determine the stress distribution and stress mode of the cell and pore wall connection structure, thereby determining the macroscopic properties of the material. Controlling the cell structure is a key factor to ensure the performance of foamed polypropylene.

[0005] At the same time, the rheological properties of the polyolefin matrix resin are also very important for its foaming ability. An ideal matrix resin should have sufficient fluidity to ensure the rapid generation and growth of cells during the above foaming process, but the means to improve the fluidity of the resin often weaken the foaming performance and physical properties of the resin. The fluidity of the matrix resin can be represented by its zero shear viscosity η0. The lower the η0 at a certain temperature, the better the fluidity of the resin at that temperature.

[0006] In order to improve the foaming ability of the polyolefin matrix resin and the physical properties of the polyolefin foamed beads, the method of introducing inorganic additives / fillers is tried. However, when the amount is small, it has no effect on the matrix resin and foamed beads, and when the amount is large, it reduces the fluidity of the matrix resin (increases viscosity) and destroys the cell structure of the foamed beads, which has a negative impact on the foaming ability of the polyolefin matrix resin and the physical properties of the polyolefin foamed beads.

[0007] The Janus particle concept was introduced by de Gennes, the Nobel Prize winner in Physics in 1991, referring to nano-particles with spatially segregated regions of different chemical composition and function. Due to the coexistence of polar (hydrophilic) and non-polar (hydrophobic) surfaces, Janus particles can be oriented and assembled at the interface of polar / non-polar (water / oil) two-phase interface. Among the Janus particles with various morphologies, Janus sheets, as a kind of two-dimensional material, have unique interfacial behaviors due to their topological morphology. When sheet-shaped (or disc-shaped) Janus particles are fixed at the interface of Pickering emulsion, the interfacial flipping of sheet-shaped particles caused by thermal motion is limited, so the sheet-shaped Janus particles can more efficiently stabilize the interface. SUMMARY

[0008] In view of the above problems existing in the prior art, the purpose of the present application is to provide a polyolefin resin composition and a preparation method thereof, polyolefin foamed beads and a polyolefin molded body, by adding Janus sheets, a polyolefin composition with lower zero shear viscosity than before modification is obtained, and by using it as raw material for autoclave foaming, the obtained polyolefin foamed beads have excellent cell structure, and the accumulation of Janus sheets can be observed on the cell wall section, which plays a supporting and reinforcing role on the cells, so the molded body of the above foamed beads has excellent tensile properties, compression properties and thermal insulation properties.

[0009] The first aspect of the present application provides a polyolefin resin composition containing polyolefin, Janus sheets and optional functional additives, the thickness of the Janus sheets is ≤200 nm, and the cross-sectional side length is 100-2000 nm.

[0010] The content of the Janus sheets is 0.008-0.1 parts by weight based on 100 parts by weight of the polyolefin, and the content of the functional additives is 0-1 parts by weight.

[0011] The second aspect of the present application provides a preparation method of the above-mentioned polyolefin resin composition, which comprises: mixing polyolefin, Janus sheets and optional functional additives, then extruding a wire and cutting to obtain composition microparticles.

[0012] The third aspect of the present application provides a polyolefin foamed bead prepared by the autoclave foaming process of the above-mentioned polyolefin resin composition.

[0013] The fourth aspect of the present application provides a polyolefin molded body prepared by molding the above-mentioned polyolefin foamed bead.

[0014] Compared with the prior art, the present application has the following beneficial effects:

[0015] 1. The polyolefin composition provided by the present application has lower η0 at the temperature of autoclave foaming process than the polyolefin composition with base polyolefin and other inorganic fillers, but still maintains the original foaming performance and physical properties.

[0016] 2. The polyolefin foamed beads provided by the present application have higher closed cell rate and cell density than the foamed beads prepared from base polyolefin, and the Janus particle aggregation can be observed on the cell wall section.

[0017] 3. The polyolefin foamed beads provided by the present application have higher tensile performance, compression performance and thermal insulation performance than the foamed beads prepared from base polyolefin.

[0018] 4. The preparation process of the polyolefin composition, foamed beads and shaped body used by the present application is simple and easy to operate, and has no significant higher requirements on production equipment and operator training than the existing process method.

[0019] Other features and advantages of the present application will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 η* comparison curve of the polyolefin composition obtained from Example 1, Comparative Example 1 and Comparative Example 3.

[0021] Figure 2 Cell morphology photo of the foamed beads obtained from Example 1.

[0022] Figure 3 Cell morphology photo of the foamed beads obtained from Comparative Example 1.

[0023] Figure 4 Cell morphology photo of the foamed beads obtained from Comparative Example 3.

[0024] Figure 5 Cell wall section photo of the foamed beads obtained from Example 1.

[0025] Figure 6 Cell wall section photo of the foamed beads obtained from Comparative Example 1.

[0026] Figure 7 Cell wall section photo of the foamed beads obtained from Comparative Example 3. DETAILED DESCRIPTION

[0027] The specific embodiments of the present application are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0028] According to a first aspect of the present application, the present application provides a polyolefin resin composition, which contains a polyolefin, a Janus sheet and an optional functional aid, the Janus sheet having a thickness of ≤200 nm and a cross-sectional side length of 100-2000 nm;

[0029] The content of the Janus sheet is 0.008-0.1 parts by weight, and the content of the functional aid is 0-1 parts by weight, based on 100 parts by weight of the polyolefin.

[0030] In the present application, the Janus sheet can be a nanoscale sheet material containing a polar group and a non-polar group on both sides, and any Janus sheet with amphiphilic properties in the prior art can be used. Preferably, the Janus sheet is a silica nanosheet containing a polar amino group and a non-polar maleimide group on both sides, or a silica nanosheet containing a polar epoxy group and a non-polar alkane group on both sides. The Janus sheet can be obtained by various preparation methods such as paraffin protection method, Pickering emulsion method, block copolymer assembly-disassembly method, etc., and the specific preparation process is known to those skilled in the art, which will not be described here.

[0031] Preferably, the Janus sheet has a thickness of ≤100 nm and a cross-sectional side length of 200-1000 nm.

[0032] In the present application, the polyolefin can be selected from various polyolefins commonly used in the art, and can be at least one selected from polypropylene, propylene copolymer (such as ternary random copolymer polypropylene), polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic ester copolymer, polyvinyl chloride, poly-1-butene, poly-4-methyl-1-pentene and cyclic olefin polymer.

[0033] According to the present application, the functional aid can be various functional aids commonly used in the art, for example, can be at least one selected from antioxidants, ultraviolet absorbers, antistatic agents, flame retardants, metal deactivators, pigments, nucleating agents, foam control agents, fillers, stabilizers, reinforcing agents and lubricants.

[0034] In the present application, the antioxidant can be any antioxidant commonly used in the art. Preferably, the antioxidant is a mixture of a hindered phenolic antioxidant and a phosphite antioxidant at a mass ratio of 1-5:5-1. The hindered phenolic antioxidant can be selected from antioxidant 1010, antioxidant 1076, antioxidant 245 or antioxidant 246; the phosphite antioxidant can be selected from triphenyl phosphate, trimethyl phosphate or antioxidant 168.

[0035] Preferably, the content of the Janus sheet is 0.02 to 0.06 parts by weight and the content of the functional aid is 0 to 0.5 parts by weight, based on 100 parts by weight of the polyolefin.

[0036] The physical properties of the polyolefin composition of the present application do not change significantly (melting point ± 0.2°C, melt index, flexural modulus, Charpy impact strength ± 0.4%) compared to the unmodified polyolefin resin, and η0is reduced by 20%, preferably by 30%, compared to the unmodified polyolefin resin.

[0037] According to a second aspect of the present application, the present application provides a method for preparing the above-mentioned polyolefin resin composition, which comprises mixing the polyolefin, the Janus sheet and the optional functional aid, and then extruding the mixture into a strand and cutting the strand to obtain the composition microparticles.

[0038] In the present application, the mixing of the materials can be carried out using various mixing devices known in the art, such as a high-speed mixer, a kneader, etc. The extruding of the strand and the cutting can be carried out in an extrusion molding machine via one or more dies of a twin-screw or single-screw extruder to extrude the mixture into a strand and cut the strand to obtain the microparticles, and the particle size and the length / diameter ratio of the microparticles can be controlled by adjusting the feeding speed and the cutting speed, and the die temperature can be selected as needed. These are all routine selections that can be made by those skilled in the art with reference to the prior art, and will not be described here in detail.

[0039] According to the present application, the cutting of the composition microparticles can be carried out using an underwater microparticle cutting system. Specifically, the microparticle cutting can be carried out in water at a temperature of 70°C or lower, preferably 65°C or lower, and more preferably 45 to 55°C. In order to facilitate the foaming and molding of EPP, the length / diameter ratio of the composition microparticles can be 0.5 to 2.0, preferably 0.8 to 1.3, and more preferably 0.9 to 1.1, and the average weight of the microparticles can be 0.1 to 20 mg, preferably 0.2 to 10 mg, and more preferably 1 to 3 mg. The average weight is the average value of 200 microparticles selected at random.

[0040] According to a third aspect of the present application, the present application provides a polyolefin foamed bead prepared by the kettle foaming process of the above-mentioned polyolefin resin composition.

[0041] The microparticles are foamed using the kettle foaming process, which requires the use of auxiliary agents such as dispersing media, surfactants, dispersants, and dispersion enhancers. These are all known to those skilled in the art.

[0042] The specific steps for preparing the foamed bead can be as follows:

[0043] 1. In a pressure autoclave foaming device, the polyolefin composition microparticles are added with dispersing medium, surfactant, dispersant, dispersion enhancer and other additives at one time. The dispersion in the autoclave is stirred and mixed. The stirring speed is 50-300 rpm, preferably 150-250 rpm.

[0044] 2. The residual air in the reactor is discharged using a physical blowing agent. After the autoclave is sealed, the blowing agent is fed into the autoclave. After the pressure is preliminarily adjusted, the temperature in the autoclave is heated to the foaming process temperature, which is ±10°C, preferably ±5°C, of the melting point of the polypropylene microparticles. Then, the pressure in the autoclave is adjusted to the foaming process pressure, which is 0.5-16 MPa, preferably 2-8 MPa. Under the foaming temperature and pressure conditions, the stirring is continued for 0.1-2 hours, preferably 0.3-1 hour.

[0045] 3. Then, the discharge port of the autoclave is opened, and the material in the reactor is discharged into a collection tank to obtain foamed beads. While the discharge is being performed, compressed gas is fed to supplement the pressure, so that the pressure in the autoclave is maintained at about the foaming pressure before all the particles are completely foamed and enter the collection tank.

[0046] The physical blowing agent can be an organic physical blowing agent or an inorganic physical blowing agent. The organic physical blowing agent includes, but is not limited to, at least one of aliphatic hydrocarbons such as propane, butane, pentane, hexane and heptane, alicyclic hydrocarbons such as cyclobutane and cyclohexane, and halogenated hydrocarbons such as chlorofluoromethane, trifluoromethane, 1,2-difluoroethane, 1,2,2,2-tetrafluoroethane, methyl chloride, ethyl chloride and dichloromethane. The inorganic physical blowing agent includes, but is not limited to, at least one of air, nitrogen, carbon dioxide, oxygen and water. Supercritical carbon dioxide, supercritical nitrogen or a mixture gas of them in any ratio.

[0047] The apparent density of the autoclave-foamed beads is conventionally selected in the art and can include, but is not limited to, 10-200 g / L, preferably 15-180 g / L. Those skilled in the art are aware of this and it is not described here.

[0048] Under the same process conditions, the autoclave-foamed beads prepared from the polyolefin composition of the present application have an apparent density that is 10% lower, preferably 20% lower, than the beads prepared from unmodified polyolefin under the same process conditions. Under the same apparent density, the closed cell rate is increased by 8%, preferably 12%, and the average cell diameter is reduced by 20%, preferably 30%.

[0049] According to a fourth aspect of the present application, the present application provides a polyolefin molded body, which is obtained by molding the polyolefin foamed beads described above.

[0050] The specific foaming molding process conditions can be conventional selection in the art, and the specific process is known to those skilled in the art, which is not described here.

[0051] The apparent density of the foamed molding body which is conventional selection in the art can include but is not limited to 10-200 g / L, preferably 15-180 g / L. This is known to those skilled in the art, which is not described here.

[0052] Under the same process conditions, the polyolefin foamed bead molding body of the present application, compared with the foamed molding body prepared from unmodified polyolefin, the compression strength (50%) can be increased by ≥30%, preferably increased by ≥50%, under the same apparent density; the tensile strength can be increased by ≥30%, preferably increased by ≥50%; the thermal conductivity coefficient can be reduced by 10%, preferably reduced by 15%.

[0053] The substances and parameters not limited in the present application can be selected according to the prior art, which is a conventional technical means in the art.

[0054] The present application will be further described below in conjunction with examples, but is not limited by these examples.

[0055] In the following examples and comparative examples, the raw materials used and the instruments and equipment used include:

[0056] Kaolin: Bailingwei, ACROS, analytical pure.

[0057] Sodium dodecyl benzene sulfonate: Tianjin Guangfu Fine Chemical Research Institute, analytical pure.

[0058] Aluminum sulfate: Tianjin Guangfu Technology Development Co., Ltd., analytical pure.

[0059] Random terpolymer polypropylene E680E: melt index 7.5 g / 10 min, η0=1.19×10 4 Pa·s at foaming process temperature (145℃), produced by Sinopec Shanghai Petrochemical.

[0060] Random ethylene-propylene copolymer polypropylene B4908: melt index 7.5 g / 10 min, η0=1.21×10 4 Pa·s at foaming process temperature (145℃), produced by Sinopec Yanshan Petrochemical.

[0061] Random propylene-butylene copolymer polypropylene M850B: melt index 7.5 g / 10 min, η0=1.17×10 4 Pa·s at foaming process temperature (145℃), produced by Sinopec Shanghai Petrochemical.

[0062] Janus sheets and silica sheets are self-made, and the specific preparation method is as follows:

[0063] JanusA, JanusB, JanusC, JanusD and JanusE are silica nanoplatelets with polar amino groups and non-polar maleimide groups on both sides. The preparation method is as follows: 1500 mL of 10 wt% hydrolyzed styrene-maleic anhydride copolymer aqueous solution is prepared, and the solution is dissolved in 7500 mL of water. The pH of the mixture is adjusted to 2.5 with hydrochloric acid. Then 1000 grams of n-decane, 1100 g of (3-aminopropyl)triethoxysilane, 1240 g of 3-(trimethoxysilyl)propyl methacrylate, 5200 g of tetraethoxysilane, 10000 g of divinylbenzene and 100 g of 2,2'-azobis(2-methylpropionitrile) solution are mixed. The oil mixture is dispersed into the aqueous solution, stirred at 12000 rpm for 5 min to form an oil-in-water emulsion. The emulsifier is fixed below, stirred at 25°C for 7 h to obtain a self-organizing interfacial sol-gel silane process. Then, the emulsion is heated to 70°C to initiate the polymerization of divinylbenzene on the inner surface. Janus hollow spherical shells are obtained. Then they are crushed into Janus nanoplatelets with a colloidal mill.

[0064] The prepared Janus platelets are as follows: JanusA: thickness 50 nm, cross-sectional side length 750 nm; JanusB: thickness 125 nm, cross-sectional side length 1500 nm; JanusC: thickness 80 nm, cross-sectional side length 400 nm; JanusD: thickness 250 nm, cross-sectional side length 1500 nm; JanusE: thickness 180 nm, cross-sectional side length 2500 nm.

[0065] JanusF, JanusG are silica nanoplatelets with polar epoxy groups and non-polar alkane groups on both sides. The preparation method is as follows: 1500 mL of 10 wt% hydrolyzed styrene-epoxy copolymer aqueous solution is prepared, and the solution is dissolved in 7500 mL of water. The pH of the mixture is adjusted to 2.5 with hydrochloric acid. Then 1000 grams of n-decane, 1100 g of triethoxy(tetradecyl)silane, 1240 g of 3-(trimethoxysilyl)propyl methacrylate, 5200 g of tetraethoxysilane, 10000 g of divinylbenzene and 100 g of 2,2'-azobis(2-methylpropionitrile) solution are mixed. The oil mixture is dispersed into the aqueous solution, stirred at 12000 rpm for 5 min to form an oil-in-water emulsion. The emulsifier is fixed below, stirred at 25°C for 7 h to obtain a self-organizing interfacial sol-gel silane process. Then, the emulsion is heated to 70°C to initiate the polymerization of divinylbenzene on the inner surface. Janus hollow spherical shells are obtained. Then they are crushed into Janus nanoplatelets with a colloidal mill.

[0066] The prepared Janus sheet, Janus F: thickness 75 nm, cross-sectional side length 800 nm; Janus G: thickness 300 nm, cross-sectional side length 3000 nm.

[0067] The specific preparation method of the silica sheet A is as follows: 9000 mL of water is adjusted to pH 2.5 using a hydrochloric acid solution. Then 1000 grams of n-decane, 5200 g of tetraethoxysilane, 10000 g of divinylbenzene and 100 g of 2,2'-azo(2-methylpropionitrile) solution are mixed. The oil mixture is dispersed into the aqueous solution, stirred at 12000 rpm for 5 min to form an oil-in-water emulsion. The emulsifier is fixed below, stirred at 25°C for 7 h to obtain a self-organizing interfacial sol-gel silane process. Then, the emulsion is heated to 70°C to initiate the polymerization of divinylbenzene on the inner surface. The silica hollow shell is obtained. Then it is crushed into silica nanosheet by a colloidal mill. The silica sheet A has the same appearance size as Janus A, but does not contain functional groups on both sides.

[0068] The specific preparation method of the silica sheet B is as follows: 9000 mL of water is adjusted to pH 2.5 using a hydrochloric acid solution. Then 1000 grams of n-decane, 1100 g of (3-aminopropyl)triethoxysilane, 1240 g of 3-(trimethoxysilyl)methyl propyl methacrylate, 5200 g of tetraethoxysilane, 10000 g of divinylbenzene and 100 g of 2,2'-azo(2-methylpropionitrile) solution are mixed. The oil mixture is dispersed into the aqueous solution, stirred at 12000 rpm for 5 min to form an oil-in-water emulsion. The emulsifier is fixed below, stirred at 25°C for 7 h to obtain a self-organizing interfacial sol-gel silane process. Then, the emulsion is heated to 70°C to initiate the polymerization of divinylbenzene on the inner surface. The silica hollow shell is obtained. Then it is crushed into silica nanosheet by a colloidal mill. The silica sheet B has the same appearance size as Janus A, but contains amino polar functional groups on both sides;

[0069] The specific preparation method of silica sheet C is as follows: 9000 mL of water is adjusted to pH 2.5 using a hydrochloric acid solution. Then 1000 grams of n-decane, 1100 g of triethoxyl(tetradecyl)silane, 1240 g of 3-(trimethoxysilyl)methyl propyl methacrylate, 5200 g of tetraethoxysilane, 10000 g of divinylbenzene and 100 g of 2,2'-azobis(2-methylpropionitrile) solution are mixed. The oil mixture is dispersed into the aqueous solution, stirred at 12000 rpm for 5 min to form an oil-in-water emulsion. The emulsifier is fixed below, stirred at 25°C for 7 h to obtain a self-organizing interfacial sol-gel silane process. Then, the emulsion is heated to 70°C to initiate the polymerization of divinylbenzene on the inner surface. The silica hollow shell is obtained. Then it is crushed into silica nanosheets by a colloidal mill. Silica sheet C has the same appearance size as Janus A, but both sides contain alkane nonpolar functional groups.

[0070] Styrene-maleic anhydride copolymer, AR, Biotage reagent.

[0071] Styrene-epoxy copolymer, AR, Biotage reagent.

[0072] Hydrochloric acid, AR, Biotage reagent.

[0073] n-Decane, AR, Biotage reagent.

[0074] (3-aminopropyl)triethoxysilane, AR, Biotage reagent.

[0075] Triethoxyl(tetradecyl)silane, AR, Biotage reagent.

[0076] 3-(trimethoxysilyl)methyl propyl methacrylate, AR, Biotage reagent.

[0077] Tetraethoxysilane, AR, Biotage reagent.

[0078] Divinylbenzene, AR, Biotage reagent.

[0079] 2,2'-azobis(2-methylpropionitrile) solution, AR, Biotage reagent.

[0080] Underwater pelletizing system: Labline 1000, BKG company, Germany.

[0081] Autoclave foaming preparation of foamed beads device: COF5-250, Beijing Xindali company.

[0082] Foamed beads in-mold forming device: EHV-C-E-PP 000269 / 2019, Allround company, Germany.

[0083] In the following examples and comparative examples, the test methods for the data are as follows:

[0084] 1. Melt mass flow rate (MFR): tested according to the method specified in GB / T 3682, wherein the test temperature is 230 °C and the load is 2.16 kg.

[0085] 2. Melting point: tested according to the method specified in GB / T 28724.

[0086] 3. Flexural modulus of polyolefin composition: tested according to the method specified in GB / T 9341.

[0087] 4. Charpy impact strength of polypropylene composition: tested according to the method specified in GB / T 1943.

[0088] 5. η0 of polyolefin composition: the relationship curve between apparent viscosity η* and shear rate w is measured by using a rotational rheometer instrument at a foaming bead preparation temperature of 145 °C, a shear rate range of 0.01-100 rad / s, and a strain value of 5%. When η* no longer rises with the shear rate in the low frequency region, it is the η0 of the polyolefin composition.

[0089] 6. Apparent density of polyolefin foaming beads: CPA225D, density accessory YDK01, Satorius Company, Germany. Test method: the apparent density of the foaming beads is obtained by using the drainage method by using the density accessory of the Satorius balance.

[0090] 7. Closed cell rate of polyolefin foaming beads: ULTRAFOAM 1200e, Quantachrome Instrument Company, USA. Test method: according to GB / T 10799-2008.

[0091] 8. Test method for the density of foaming molded body: measured according to the method introduced in GB / T 6343.

[0092] 9. Compressive strength (50%) of foaming material: tested according to the method specified in ISO 844.

[0093] 10. Test method for the thermal insulation capacity of foaming material tensile strength: the thermal conductivity is tested according to the method specified in GB / T 10295.

[0094] 11. Test method for the average cell diameter of polyolefin foaming beads: the foaming material is quenched by liquid nitrogen, the section is sprayed with gold, and the internal cell structure of the foaming material is observed by using a scanning electron microscope (SEM). 20 cells in the field of view are randomly selected, the cell diameter is measured, and the average value is calculated.

[0095] Example 1

[0096] (1) Preparation of polyolefin composition:

[0097] The amount of Janus A added was 0.05 parts by weight, the amount of antioxidant 1010 added was 0.2 parts by weight, and the amount of antioxidant 168 added was 0.1 parts by weight, based on 100 parts by weight of the random terpolymer polypropylene E680E. After that, the mixture was added to a high-speed stirrer and mixed uniformly, and then the mixed material was added to the feeder of a twin-screw extruder. The material entered the twin screw through the feeder, and the temperature of the screw during processing was maintained at 160-200°C. After being melted, mixed uniformly, extruded, and molded at 260°C, the polyolefin composition microparticles were obtained, with a length / diameter ratio of 1.0 and an average weight of 2 mg.

[0098] The composition microparticles of Test Example 1 had a melting point of 140.3°C, a melting index of 7.1 g / 10 min, a flexural modulus of 766 MPa, and a room temperature simple supported beam impact strength of 6.3 kJ / m 2 . The η0 thereof is shown in Table 1, and the η* is shown in Figure 1 .

[0099] (2) Preparation of polyolefin foamed beads:

[0100] 100 parts by weight of the composition microparticles prepared in Step 1, 300 parts by weight of a dispersion medium, deionized water, 0.3 parts by weight of a surfactant, sodium dodecyl benzene sulfonate, 5 parts by weight of a dispersant, kaolin, and 0.13 parts by weight of a dispersion enhancer, aluminum sulfate, and other auxiliary agents were added at one time to a kettle pressure foaming device, and the dispersion in the autoclave was mixed at a stirring speed of 80 rpm. 99.99 wt% carbon dioxide was used as a foaming agent to discharge the residual air in the reaction kettle, and after the pressure kettle was sealed, the foaming agent was fed into the autoclave, and the pressure was initially adjusted to 2.0 MPa. Subsequently, the temperature was increased to 145°C at a constant rate. Then, the pressure in the kettle was adjusted to 4.0 MPa. Under the foaming temperature and pressure conditions, the stirring was continued for 0.5 hours. Then, the discharge port of the autoclave was opened, and the material in the reaction kettle was discharged into a collection tank to obtain polyolefin composition foamed beads. After the beads were collected, they were dehydrated and dried.

[0101] The apparent density, closed cell rate, and average cell diameter of the foamed beads of Test Example 1 were tested, and the results are shown in Table 1. The cell morphology and cell wall section are shown in Figure 2 、 Figure 5 .

[0102] (3) Preparation of polyolefin foamed molded body:

[0103] The foamed beads prepared above were fed into a molding machine and molded into a molding die under a steam pressure of 2.0 bar for 15 minutes, and then the molded body obtained was cured at a temperature of 100°C and a pressure of standard atmospheric pressure for 24 hours to obtain a foamed molded body. The apparent density of the molded body was adjusted to be the same as that of the foamed beads, and the compression strength, tensile strength and thermal conductivity of the molded body were tested. The results are shown in Table 1.

[0104] Example 2

[0105] (1) Preparation of polyolefin composition:

[0106] The preparation process was the same as step (1) of Example 1. The difference was that Janus A was replaced by Janus B.

[0107] The melting point of the micro-particles of the composition of Example 2 was 140.4°C, the melting index was 7.1 g / 10 min, the flexural modulus was 769 MPa, and the Charpy impact strength at room temperature was 6.2 kJ / m 2 . Its η0is shown in Table 1.

[0108] (2) Preparation of polyolefin foamed beads:

[0109] The preparation process was the same as step (2) of Example 1.

[0110] The apparent density, closed cell rate and average cell diameter of the foamed beads of Example 2 were tested. The results are shown in Table 1.

[0111] (3) Preparation of polyolefin foamed molded body:

[0112] The preparation process was the same as step (3) of Example 1. The compression strength, tensile strength and thermal conductivity of the molded body were tested. The results are shown in Table 1.

[0113] Example 3

[0114] (1) Preparation of polyolefin composition:

[0115] The preparation process was the same as step (1) of Example 1. The difference was that Janus A was replaced by Janus C.

[0116] The melting point of the micro-particles of the composition of Example 3 was 140.5°C, the melting index was 7.0 g / 10 min, the flexural modulus was 764 MPa, and the Charpy impact strength at room temperature was 6.3 kJ / m 2 . Its η0is shown in Table 1.

[0117] (2) Preparation of polyolefin foamed beads:

[0118] The preparation process was the same as step (2) of Example 1.

[0119] The apparent density, closed cell ratio and average cell diameter of the expanded beads of Example 3 were tested, and the results are shown in Table 1.

[0120] (3) Preparation of the polyolefin expanded molded body:

[0121] The preparation procedure was the same as Step (3) of Example 1. The compression strength, tensile strength and thermal conductivity of the molded body were tested, and the results are shown in Table 1.

[0122] Example 4

[0123] (1) Preparation of the polyolefin composition:

[0124] The preparation procedure was the same as Step (1) of Example 1. The difference was that Janus A was replaced by Janus F.

[0125] The melting point of the microparticles of the composition of Example 4 was 140.6°C, the melt index was 7.2 g / 10 min, the flexural modulus was 762 MPa, and the Charpy impact strength at room temperature was 6.4 kJ / m 2 . Its η0is shown in Table 1.

[0126] (2) Preparation of the polyolefin expanded beads:

[0127] The preparation procedure was the same as Step (2) of Example 1.

[0128] The apparent density, closed cell ratio and average cell diameter of the expanded beads of Example 4 were tested, and the results are shown in Table 1.

[0129] (3) Preparation of the polyolefin expanded molded body:

[0130] The preparation procedure was the same as Step (3) of Example 1. The compression strength, tensile strength and thermal conductivity of the molded body were tested, and the results are shown in Table 1.

[0131] Example 5

[0132] (1) Preparation of the polyolefin composition:

[0133] The preparation procedure was the same as Step (1) of Example 1. The difference was that 0.05 parts by weight of Janus A was replaced by a combination of 0.02 parts by weight of Janus A, 0.15 parts by weight of Janus B and 0.15 parts by weight of Janus C.

[0134] The melting point of the microparticles of the composition of Example 5 was 140.7°C, the melt index was 6.9 g / 10 min, the flexural modulus was 769 MPa, and the Charpy impact strength at room temperature was 6.3 kJ / m 2 . Its η0is shown in Table 1.

[0135] (2) Preparation of the polyolefin expanded beads:

[0136] The procedure was the same as step (2) of Example 1.

[0137] The apparent density, closed cell ratio and average cell diameter of the expanded beads of Example 5 were tested, and the results are shown in Table 1.

[0138] (3) Preparation of the polyolefin expanded molded body:

[0139] The procedure was the same as step (3) of Example 1. The compression strength, tensile strength and thermal conductivity of the molded body were tested, and the results are shown in Table 1.

[0140] Example 6

[0141] (1) Preparation of the polyolefin composition:

[0142] The procedure was the same as step (1) of Example 1. The difference was that 0.05 parts by weight of Janus A was replaced by 0.09 parts by weight of Janus B.

[0143] The melting point of the microparticles of the composition of Example 6 was 140.7°C, the melt index was 6.9 g / 10 min, the flexural modulus was 769 MPa, and the Charpy impact strength at room temperature was 6.2 kJ / m 2 . Its η0is shown in Table 1.

[0144] (2) Preparation of the polyolefin expanded beads:

[0145] The procedure was the same as step (2) of Example 1.

[0146] The apparent density, closed cell ratio and average cell diameter of the expanded beads of Example 6 were tested, and the results are shown in Table 1.

[0147] (3) Preparation of the polyolefin expanded molded body:

[0148] The procedure was the same as step (3) of Example 1. The compression strength, tensile strength and thermal conductivity of the molded body were tested, and the results are shown in Table 1.

[0149] Example 7

[0150] (1) Preparation of the polyolefin composition:

[0151] The procedure was the same as step (1) of Example 1. The difference was that 0.05 parts by weight of Janus A was replaced by 0.01 parts by weight of Janus B.

[0152] The melting point of the microparticles of the composition of Example 7 was 140.5°C, the melt index was 7.0 g / 10 min, the flexural modulus was 766 MPa, and the Charpy impact strength at room temperature was 6.3 kJ / m 2 . Its η0is shown in Table 1.

[0153] (2) Preparation of the polyolefin expanded beads:

[0154] The procedure was the same as step (2) of Example 1.

[0155] The apparent density, closed cell ratio and average cell diameter of the expanded beads of Example 7 were measured, and the results are shown in Table 1.

[0156] (3) Preparation of the polyolefin expanded molded body:

[0157] The procedure was the same as step (3) of Example 1. The compression strength, tensile strength and thermal conductivity of the molded body were measured, and the results are shown in Table 1.

[0158] Example 8

[0159] (1) Preparation of the polyolefin composition:

[0160] The procedure was the same as step (1) of Example 1. The difference was that E680E was replaced by B4908.

[0161] The melting point of the microparticles of the composition of Example 8 was 140.5°C, the melt index was 7.1 g / 10 min, the flexural modulus was 771 MPa, and the notched Charpy impact strength at room temperature was 6.0 kJ / m 2 . The η0 thereof is shown in Table 1.

[0162] (2) Preparation of the polyolefin expanded beads:

[0163] The procedure was the same as step (2) of Example 1.

[0164] The apparent density, closed cell ratio and average cell diameter of the expanded beads of Example 8 were measured, and the results are shown in Table 1.

[0165] (3) Preparation of the polyolefin expanded molded body:

[0166] The procedure was the same as step (3) of Example 1. The compression strength, tensile strength and thermal conductivity of the molded body were measured, and the results are shown in Table 1.

[0167] Example 9

[0168] (1) Preparation of the polyolefin composition:

[0169] The procedure was the same as step (1) of Example 1. The difference was that E680E was replaced by M850B.

[0170] The melting point of the microparticles of the composition of Example 9 was 140.2°C, the melt index was 7.1 g / 10 min, the flexural modulus was 766 MPa, and the notched Charpy impact strength at room temperature was 6.2 kJ / m 2 . The η0 thereof is shown in Table 1.

[0171] (2) Preparation of the polyolefin expanded beads:

[0172] The procedure was the same as step (2) of Example 1.

[0173] The apparent density, closed cell ratio and average cell diameter of the foamed beads of Example 9 were tested, and the results are shown in Table 1.

[0174] (3) Preparation of polyolefin foamed molded body:

[0175] The procedure was the same as step (3) of Example 1. The compression strength, tensile strength and thermal conductivity of the molded body were tested, and the results are shown in Table 1.

[0176] Comparative Example 1

[0177] (1) Preparation of polyolefin composition:

[0178] The procedure was the same as step (1) of Example 1. The difference was that Janus A was not added.

[0179] The melting point of the microparticles of the composition of Comparative Example 1 was 140.5°C, the melt index was 7.0 g / 10 min, the flexural modulus was 768 MPa, and the room temperature Charpy impact strength was 6.3 kJ / m 2 . Figure 1 .

[0180] (2) Preparation of polyolefin foamed beads:

[0181] The procedure was the same as step (2) of Example 1. The difference was that the foaming pressure was 5 MPa.

[0182] The apparent density, closed cell ratio and average cell diameter of the foamed beads of Comparative Example 1 were tested, and the results are shown in Table 1. The cell morphology and the cross section of the cell wall are shown in Figure 3 , Figure 6 .

[0183] (3) Preparation of polyolefin foamed molded body:

[0184] The procedure was the same as step (3) of Example 1. The compression strength, tensile strength and thermal conductivity of the molded body were tested, and the results are shown in Table 1.

[0185] Comparative Example 2

[0186] (1) Preparation of polyolefin composition:

[0187] The procedure was the same as step (1) of Example 1. The difference was that Janus A was replaced by silica flake A.

[0188] The melting point of the microparticles of the composition of Comparative Example 2 was 140.5°C, the melt index was 7.0 g / 10 min, the flexural modulus was 768 MPa, and the room temperature Charpy impact strength was 6.3 kJ / m 2 .

[0189] (2) Preparation of polyolefin foamed beads:

[0190] The preparation procedure was the same as step (2) of Comparative Example 1.

[0191] The apparent density, closed cell ratio and average cell diameter of the foamed beads of Comparative Example 2 were tested, and the results are shown in Table 1.

[0192] (3) Preparation of polyolefin foamed molded body:

[0193] The preparation procedure was the same as step (3) of Comparative Example 1. The compression strength, tensile strength and thermal conductivity of the molded body were tested, and the results are shown in Table 1.

[0194] Comparative Example 3

[0195] (1) Preparation of polyolefin composition:

[0196] The preparation procedure was the same as step (1) of Example 1. The difference was that 0.05 parts by weight of Janus A was replaced by 0.15 parts by weight of Janus A.

[0197] The melting point of the microparticles of the composition of Comparative Example 3 was tested to be 140.8°C, the melting index was 6.8 g / 10 min, the flexural modulus was 767 MPa, the room temperature simple support impact strength was 6.4 kJ / m 2 , and η* was seen Figure 1 .

[0198] (2) Preparation of polyolefin foamed beads:

[0199] The preparation procedure was the same as step (2) of Comparative Example 1.

[0200] The apparent density, closed cell ratio and average cell diameter of the foamed beads of Comparative Example 3 were tested, and the results are shown in Table 1, and the cell morphology and pore wall section are shown in Figure 4 , Figure 7 .

[0201] (3) Preparation of polyolefin foamed molded body:

[0202] The preparation procedure was the same as step (3) of Comparative Example 1. The compression strength, tensile strength and thermal conductivity of the molded body were tested, and the results are shown in Table 1.

[0203] Comparative Example 4

[0204] (1) Preparation of polyolefin composition:

[0205] The preparation procedure was the same as step (1) of Example 1. The difference was that 0.05 parts by weight of Janus A was replaced by 0.005 parts by weight of Janus A.

[0206] The test comparative example 4 composition microparticles had a melting point of 140.5°C, a melt index of 7.0 g / 10 min, a flexural modulus of 768 MPa, and a room temperature Charpy impact strength of 6.3 kJ / m 2 .

[0207] (2) Preparation of polyolefin foamed beads:

[0208] The preparation process was the same as step (2) of Comparative Example 1.

[0209] The apparent density, closed cell ratio, and average cell diameter of the foamed beads of Comparative Example 4 were tested, and the results are shown in Table 1.

[0210] (3) Preparation of polyolefin foamed molded bodies:

[0211] The preparation process was the same as step (3) of Comparative Example 1. The compression strength, tensile strength, and thermal conductivity of the molded bodies were tested, and the results are shown in Table 1.

[0212] Comparative Example 5

[0213] (1) Preparation of polyolefin composition:

[0214] The preparation process was the same as step (1) of Example 1. The difference was that Janus A was replaced by Janus D.

[0215] The test comparative example 4 composition microparticles had a melting point of 140.5°C, a melt index of 7.0 g / 10 min, a flexural modulus of 768 MPa, and a room temperature Charpy impact strength of 6.3 kJ / m 2 .

[0216] (2) Preparation of polyolefin foamed beads:

[0217] The preparation process was the same as step (2) of Comparative Example 1.

[0218] The apparent density, closed cell ratio, and average cell diameter of the foamed beads of Comparative Example 5 were tested, and the results are shown in Table 1.

[0219] (3) Preparation of polyolefin foamed molded bodies:

[0220] The preparation process was the same as step (3) of Comparative Example 1. The compression strength, tensile strength, and thermal conductivity of the molded bodies were tested, and the results are shown in Table 1.

[0221] Comparative Example 6

[0222] (1) Preparation of polyolefin composition:

[0223] The preparation process was the same as step (1) of Example 1. The difference was that Janus A was replaced by Janus E.

[0224] The test comparative example 6 composition microparticles had a melting point of 140.7°C, a melt index of 6.9 g / 10 min, a flexural modulus of 763 MPa, and a room temperature Charpy impact strength of 6.4 kJ / m 2 .

[0225] (2) Preparation of polyolefin foamed beads:

[0226] The preparation process was the same as step (2) of Comparative Example 1.

[0227] The apparent density, closed cell ratio, and average cell diameter of the foamed beads of the test comparative example 6 were tested, and the results are shown in Table 1.

[0228] (3) Preparation of polyolefin foamed molded bodies:

[0229] The preparation process was the same as step (3) of Comparative Example 1. The compression strength, tensile strength, and thermal conductivity of the molded bodies were tested, and the results are shown in Table 1.

[0230] Comparative Example 7

[0231] (1) Preparation of polyolefin composition:

[0232] The preparation process was the same as step (1) of Example 1. The difference was that Janus A was replaced by Janus G.

[0233] The test comparative example 7 composition microparticles had a melting point of 140.7°C, a melt index of 6.9 g / 10 min, a flexural modulus of 771 MPa, and a room temperature Charpy impact strength of 6.3 kJ / m 2 .

[0234] (2) Preparation of polyolefin foamed beads:

[0235] The preparation process was the same as step (2) of Comparative Example 1.

[0236] The apparent density, closed cell ratio, and average cell diameter of the foamed beads of the test comparative example 7 were tested, and the results are shown in Table 1.

[0237] (3) Preparation of polyolefin foamed molded bodies:

[0238] The preparation process was the same as step (3) of Comparative Example 1. The compression strength, tensile strength, and thermal conductivity of the molded bodies were tested, and the results are shown in Table 1.

[0239] Comparative Example 8

[0240] (1) Preparation of polyolefin composition:

[0241] The preparation process was the same as step (1) of Example 1. The difference was that Janus A was replaced by silica flake B.

[0242] The test comparative example 8 composition microparticles had a melting point of 140.5°C, a melt index of 7.0 g / 10 min, a flexural modulus of 768 MPa, and a room temperature Charpy impact strength of 6.3 kJ / m 2 .

[0243] (2) Preparation of polyolefin foamed beads:

[0244] The preparation procedure was the same as step (2) of Comparative Example 1.

[0245] The apparent density, closed cell ratio, and average cell diameter of the foamed beads of the test comparative example 8 were tested, and the results are shown in Table 1.

[0246] (3) Preparation of polyolefin foamed molded bodies:

[0247] The preparation procedure was the same as step (3) of Comparative Example 1. The compression strength, tensile strength, and thermal conductivity of the molded bodies were tested, and the results are shown in Table 1.

[0248] Comparative Example 9

[0249] (1) Preparation of polyolefin composition:

[0250] The preparation procedure was the same as step (1) of Example 1. The difference was that Janus A was replaced with 3 parts by weight of silica flake C.

[0251] The test comparative example 8 composition microparticles had a melting point of 140.5°C, a melt index of 7.0 g / 10 min, a flexural modulus of 768 MPa, and a room temperature Charpy impact strength of 6.3 kJ / m 2 .

[0252] (2) Preparation of polyolefin foamed beads:

[0253] The preparation procedure was the same as step (2) of Comparative Example 1.

[0254] The apparent density, closed cell ratio, and average cell diameter of the foamed beads of the test comparative example 8 were tested, and the results are shown in Table 1.

[0255] (3) Preparation of polyolefin foamed molded bodies:

[0256] The preparation procedure was the same as step (3) of Comparative Example 1. The compression strength, tensile strength, and thermal conductivity of the molded bodies were tested, and the results are shown in Table 1.

[0257] Comparative Example 10

[0258] (1) Preparation of polyolefin composition:

[0259] The preparation procedure was the same as step (1) of Example 1. The difference was that 0.05 parts by weight of Janus A was replaced with 3 parts by weight of dihydroxypropyl octadecanoate.

[0260] The test comparative example 10 composition microparticles had a melting point of 143.5°C, a melt index of 8.1 g / 10 min, a flexural modulus of 657 MPa, and a room temperature Charpy impact strength of 6.8 kJ / m 2 .

[0261] (2) Preparation of polyolefin foamed beads:

[0262] The preparation procedure was the same as step (2) of Comparative Example 1.

[0263] The apparent density, closed cell ratio, and average cell diameter of the foamed beads of the test comparative example 10 were measured, and the results are shown in Table 1.

[0264] (3) Preparation of polyolefin foamed molded body:

[0265] The preparation procedure was the same as step (3) of Example 1. The compression strength, tensile strength, and thermal conductivity of the molded body were measured, and the results are shown in Table 1.

[0266] Comparative Example 11

[0267] (1) Preparation of polyolefin composition:

[0268] The preparation procedure was the same as step (1) of Comparative Example 1.

[0269] The test comparative example 11 composition microparticles had a melting point of 140.5°C, a melt index of 7.0 g / 10 min, a flexural modulus of 768 MPa, and a room temperature Charpy impact strength of 6.3 kJ / m 2 .

[0270] (2) Preparation of polyolefin foamed beads:

[0271] The preparation procedure was the same as step (2) of Comparative Example 1.

[0272] The apparent density, closed cell ratio, and average cell diameter of the foamed beads of the test comparative example 11 were measured, and the results are shown in Table 1.

[0273] (3) Preparation of polyolefin foamed molded body:

[0274] The preparation procedure was the same as step (3) of Example 1. The compression strength, tensile strength, and thermal conductivity of the molded body were measured, and the results are shown in Table 1.

[0275] Table 1

[0276]

[0277]

[0278] From the results of Examples 1-3, Comparative Examples 1, 5-7, 11, it can be seen that the Janus sheet with proper size specification can effectively reduce the η0of the base polyolefin resin, improve the foaming ability of the composition, and does not affect the properties of the base resin. The weight reduction performance, cell quality, tensile properties, compression properties and thermal insulation capacity of the autoclave foamed product are significantly improved. From Comparative Example 10, it can be seen that other ways to reduce η0can significantly reduce the foaming performance of the polyolefin composition.

[0279] From the results of Examples 4, 5, Comparative Examples 2, 8, 9, it can be seen that the Janus sheet needs to have different polar functional groups on both sides, and the type of functional groups has no significant effect on the viscosity reduction effect, the foaming ability of the composition and the properties of the foamed product. The silica sheet without functional groups on both sides or with the same polar functional groups on both sides has no effect on the properties of the composition and the foamed product.

[0280] From the results of Examples 6, 7 and Comparative Examples 3, 4, it can be seen that too high or too low addition amount of the Janus sheet will affect the viscosity reduction effect of the polyolefin composition and the improvement effect on the properties of the foamed product.

[0281] From the results of Comparative Example 10, it can be seen that by adding a lubricant such as glycerol monostearate, the flowability of the polyolefin composition can be reduced, but the properties of the polyolefin composition, the foamed beads and the foamed product will be significantly weakened.

[0282] From Figures 2-7 It can be seen that the cells of Example 1 are the most regular and delicate, and there is no inorganic particle to destroy the cell structure in the cells. A large number of Janus sheets are observed to accumulate on the cut cell wall.

[0283] No inorganic particles are observed in the cells and on the cell walls of Comparative Example 1. In the cells of Comparative Example 3, inorganic particle agglomeration can be observed, but no Janus sheet accumulation is observed on the cut cell wall.

[0284] The above has described various embodiments of the present application, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A polyolefin resin composition, characterized by, The composition contains a polyolefin, Janus sheets having a thickness of ≤200 nm and a cross-sectional side length of 100-2000 nm, and optionally a functional aid; The content of the Janus sheets is 0.008-0.1 parts by weight based on 100 parts by weight of the polyolefin, and the content of the functional aid is 0-1 parts by weight. The Janus sheets are silica nanosheets containing a polar amino group and a non-polar maleimide group on two sides, or silica nanosheets containing a polar epoxy group and a non-polar alkane group on two sides.

2. The polyolefin resin composition according to claim 1, wherein, The Janus sheets have a thickness of ≤100 nm and a cross-sectional side length of 200-1000 nm.

3. The polyolefin resin composition according to claim 1, wherein, The polyolefin is at least one selected from the group consisting of polypropylene, propylene copolymer, polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic ester copolymer, polyvinyl chloride, poly-1-butene, poly-4-methyl-1-pentene, and cyclic olefin polymer.

4. The polyolefin resin composition according to claim 1, wherein, The functional aid is at least one selected from the group consisting of an antioxidant, a UV absorber, an antistatic agent, a flame retardant, a metal deactivator, a pigment, a nucleating agent, a foam control agent, a filler, a stabilizer, a reinforcing agent, and a lubricant.

5. The polyolefin resin composition according to claim 4, wherein, The antioxidant is a mixture of a hindered phenolic antioxidant and a phosphite antioxidant at a mass ratio of 1-5:5-1; the hindered phenolic antioxidant is selected from antioxidant 1010, antioxidant 1076, antioxidant 245, or antioxidant 246; and the phosphite antioxidant is selected from triphenyl phosphate, trimethyl phosphate, or antioxidant 168.

6. The polyolefin resin composition according to claim 1, wherein, The content of the Janus sheets is 0.02-0.06 parts by weight based on 100 parts by weight of the polyolefin, and the content of the functional aid is 0-0.5 parts by weight.

7. The process for producing the polyolefin resin composition according to any one of claims 1 to 6, characterized by, The preparation method comprises mixing a polyolefin, Janus sheets, and optionally a functional aid, extruding a wire, and cutting to obtain composition microparticles.

8. A polyolefin expanded bead characterized by, The foamed beads are prepared by a kettle pressure foaming process using the polyolefin resin composition of any one of claims 1-6.

9. A polyolefin shaped body, characterized by, The molded body is obtained by molding the polyolefin foamed beads of claim 8.

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