Bimodal polyethylene polymers, methods of making and using the same, and stone paper

Abstract

The application relates to the field of high polymer materials, and discloses a bimodal polyethylene polymer, a preparation method and application thereof, and stone paper. 4 The bimodal polyethylene polymer has a weight average molecular weight of 20-40*10 3 ; a molecular weight distribution of 10-30; a melt flow ratio (21.6 / 5.0) of 25-40; and a melt index under a 5.0kg load at 190 DEG C of 0.01-10g / 10min. The bimodal polyethylene polymer has a bimodal distribution and wide distribution of molecular weight, low fluidity, and good mechanical properties. The bimodal polyethylene polymer is used for the stone paper, has good compatibility with calcium carbonate, the prepared stone paper has a CV value of less than 3%, a density of up to 1.18g / cm 3 , and a stiffness of up to 0.4, and good technical effects are achieved.

Description

Technical Field

[0001] This invention relates to the field of polymer materials, specifically to a bimodal polyethylene polymer, its preparation method and application, and stone paper. Background Technology

[0002] Stone papermaking eliminates the need for water and chemical reagents, thus achieving pollution-free production and surpassing traditional papermaking methods. Stone paper products are 20%–30% cheaper than traditional paper products. Therefore, stone papermaking aligns with national initiatives for low-carbon and green environmental protection, reduces product costs, and enhances enterprise competitiveness, making it a promising trend for future papermaking technology research and development.

[0003] Stone paper is ultimately produced by blown film. Generally speaking, extruded products require a wider molecular weight distribution of polyethylene, injection molded products require a narrower molecular weight distribution of polyethylene, while blown products have a molecular weight distribution in between. However, because a large amount of inorganic calcium carbonate is added to the mixture of blown stone paper, accounting for 70-80%, only with good compatibility can the produced stone paper be of uniform thickness, and the printed text be clear and the pattern colors be bright. On the other hand, polyethylene material needs to have good film-forming properties. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of poor compatibility between polyethylene powder and calcium carbonate and poor stiffness of stone paper in the prior art. It provides a bimodal polyethylene polymer with a bimodal and wide molecular weight distribution and low flowability. When the bimodal polyethylene polymer is applied to stone paper, the stone paper has a CV value of <3% and high density and stiffness.

[0005] According to a first aspect of the present invention, the present invention provides a bimodal polyethylene polymer having a weight-average molecular weight of 20 × 10⁻⁶. 4 -40×10 4 The molecular weight distribution is 10-30; the melt flow ratio (21.6 / 5.0) of the polyethylene composition is 25-40.

[0006] The melt index of the bimodal polyethylene polymer at 190℃ and a load of 5.0 kg is 0.01-10 g / 10 min.

[0007] According to a second aspect of the present invention, the present invention provides a method for preparing the aforementioned polyethylene composition, the method comprising:

[0008] (1) In a reaction system containing a catalyst and a co-catalyst, ethylene is added to carry out a first homopolymerization reaction or ethylene and C3-C12 α-olefins are added to carry out a first copolymerization reaction, and hydrogen is used to adjust the molecular weight to obtain component A.

[0009] (2) In a reaction system containing a catalyst and a co-catalyst, a mixture of ethylene and / or C3-C12 α-olefins and hydrogen, component B1, is added, followed by component A to carry out a second copolymerization reaction to obtain a bimodal polyethylene polymer; or

[0010] In a reaction system containing a catalyst and a co-catalyst, ethylene, C3-C12 α-olefins and hydrogen are added to carry out a third copolymerization reaction to obtain polymer component B2, which is then carried out a second copolymerization reaction with component A to obtain bimodal polyethylene polymer.

[0011] Preferably, the mass ratio of component A to component B1 is 1.1 to 1.8:1; the mass ratio of component A to component B2 is 1.1 to 1.8:1.

[0012] According to a third aspect of the invention, the invention provides an application of the bimodal polyethylene polymer in stone paper.

[0013] According to a fourth aspect of the present invention, the present invention provides stone paper comprising the aforementioned bimodal polyethylene polymer.

[0014] Compared with existing technologies, the bimodal polyethylene polymer provided by this invention has a bimodal and broad molecular weight distribution, and exhibits low flowability. When used in stone paper, this bimodal polyethylene polymer shows good compatibility with calcium carbonate, and the resulting stone paper can have a CV value of less than 3% and a density as high as 1.15 g / cm³. 3 With a stiffness of up to 0.4, it has achieved good technical results. Detailed Implementation

[0015] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0016] In this invention, C3 to C12 α-olefins refer to α-olefins containing 3 to 12 carbon atoms.

[0017] According to a first aspect of the present invention, the present invention provides a bimodal polyethylene polymer having a weight-average molecular weight of 20 × 10⁻⁶. 4 -40×104 The molecular weight distribution is 10-30; the melt flow ratio (21.6 / 5.0) of the bimodal polyethylene polymer is 25-40, preferably 30-40; the melt index of the bimodal polyethylene polymer at 190℃ and a load of 5.0 kg is 0.01-10 g / 10 min. The melt flow ratio (21.6 / 5.0) represents the ratio of the melt index value at 190℃ and a load of 21.6 kg to the melt index value at 190℃ and a load of 5.0 kg. The aforementioned bimodal polyethylene polymer has a bimodal and broad molecular weight distribution and exhibits low fluidity.

[0018] According to a preferred embodiment of the present invention, the number-average molecular weight of the bimodal polyethylene polymer is 10,000-30,000, preferably 11,000-15,000, and more preferably 11,000-13,000. The aforementioned components are beneficial for achieving a wide distribution and low flowability of the bimodal polyethylene polymer.

[0019] According to a preferred embodiment of the present invention, the density of the bimodal polyethylene polymer is 0.95-0.96 g / cm³. 3 The aforementioned components are beneficial for achieving a wide distribution and low flowability of bimodal polyethylene polymers.

[0020] According to a preferred embodiment of the present invention, the degree of methyl branching of the bimodal polyethylene polymer is 0.2-0.5 methyl branches / 100°C; the aforementioned bimodal polyethylene polymer is beneficial for achieving a wide distribution and low flowability of the bimodal polyethylene polymer.

[0021] According to a preferred embodiment of the present invention, the melt index of the bimodal polyethylene polymer at 190°C and a load of 5.0 kg is 0.05-5 g / 10 min; preferably 0.05-1.8 g / 10 min; the aforementioned bimodal polyethylene polymer is beneficial for achieving a wide distribution and low flowability of the bimodal polyethylene polymer.

[0022] According to a preferred embodiment of the present invention, the melt index of the bimodal polyethylene polymer at 190°C and a load of 21.6 kg is 6-18 g / 10 min; preferably 10-14 g / 10 min; the aforementioned bimodal polyethylene polymer is beneficial for achieving a wide distribution and low flowability of the bimodal polyethylene polymer.

[0023] According to a preferred embodiment of the present invention, the melt index of the bimodal polyethylene polymer at 190°C and a load of 2.16 kg is 0.01-0.2 g / 10 min; the aforementioned bimodal polyethylene polymer is beneficial for achieving a wide distribution and low flowability of the bimodal polyethylene polymer.

[0024] According to a preferred embodiment of the present invention, the bimodal polyethylene polymer contains: ethylene homopolymer and / or ethylene copolymer; the ethylene copolymer is a copolymer of ethylene monomer and C3-C12 α-olefin.

[0025] According to a preferred embodiment of the present invention, the C3-C12 α-olefin is selected from C3-C8 α-olefins; preferably, the C3-C8 α-olefin is selected from one or more of propylene, 1-butene, 1-hexene, 4-methyl-1-pentene and 1-octene; this is beneficial for achieving a wide distribution and low flowability of bimodal polyethylene polymer.

[0026] All bimodal polyethylene polymers possessing the aforementioned features of this invention can achieve the objectives of this invention, and there are no special requirements for their preparation methods. According to a second aspect of this invention, this invention provides a method for preparing the aforementioned bimodal polyethylene polymer, the method comprising:

[0027] (1) In a reaction system containing a catalyst and a co-catalyst, ethylene is added to carry out a first homopolymerization reaction or ethylene and C3-C12 α-olefins are added to carry out a first copolymerization reaction, and hydrogen is used to adjust the molecular weight to obtain component A.

[0028] (2) In a reaction system containing a catalyst and a co-catalyst, a mixture of ethylene and / or C3-C12 α-olefins and hydrogen, component B1, is added, followed by component A to carry out a second copolymerization reaction to obtain a bimodal polyethylene polymer; or

[0029] In a reaction system containing a catalyst and a co-catalyst, ethylene, C3-C12 α-olefins and hydrogen are added to carry out a third copolymerization reaction to obtain polymer component B2, which is then carried out a second copolymerization reaction with component A to obtain bimodal polyethylene polymer.

[0030] Preferably, the mass ratio of component A to component B1 is 1.1 to 1.8:1; the mass ratio of component A to component B2 is 1.1 to 1.8:1.

[0031] In this invention, the aforementioned preparation method can be carried out using a series reactor method, for example,

[0032] (1) Add a catalyst and a co-catalyst to the first reactor, add ethylene to carry out the first homopolymerization reaction or add ethylene and C3-C12 α-olefins to carry out the first copolymerization reaction, and use hydrogen to adjust the molecular weight to obtain component A;

[0033] (2) Add catalyst and co-catalyst to the second reactor, add a mixture of ethylene and / or C3-C12 α-olefins and hydrogen B1, add component A to carry out the second copolymerization reaction to obtain bimodal polyethylene polymer.

[0034] In this invention, the aforementioned preparation method can be carried out in two or more parallel reactors, for example,

[0035] (1) Add a catalyst and a co-catalyst to the first reactor, add ethylene to carry out the first homopolymerization reaction or add ethylene and C3-C12 α-olefins to carry out the first copolymerization reaction, and use hydrogen to adjust the molecular weight to obtain component A;

[0036] (2) Add catalyst and co-catalyst to the second reactor, add ethylene and / or C3-C12 α-olefins and hydrogen to carry out the third polymerization reaction to obtain polymer component B2; then carry out the second copolymerization reaction with component A to obtain bimodal polyethylene polymer.

[0037] According to the present invention, an inert liquid, such as a C5-C10 alkane, can be added to the reactor used to prepare the bimodal polyethylene polymer for cooling the reactor. For example, hexane can be added to the reactor before the polymerization reaction for cooling. Those skilled in the art can choose whether to add an inert liquid according to the reactor temperature control requirements. Using an inert liquid or not using an inert liquid are both conventional choices in the art, as long as the temperature of each polymerization reaction in the present invention can be guaranteed.

[0038] According to a preferred embodiment of the present invention, the mass ratio of component A to component B1 is 1.1 to 1.8:1; the mass ratio of component A to component B2 is 1.1 to 1.8:1.

[0039] According to a preferred embodiment of the present invention, the first homopolymerization or first copolymerization reaction conditions include: a reaction temperature of 60-100°C and a reaction time of 0.5-6 hours.

[0040] According to a preferred embodiment of the present invention, the second copolymerization reaction conditions include: a reaction temperature of 60-100°C and a reaction time of 0.5-6 hours.

[0041] According to a preferred embodiment of the present invention, the third copolymerization reaction conditions include: a reaction temperature of 60-100°C and a reaction time of 0.5-6 hours.

[0042] According to a preferred embodiment of the present invention, in the first homopolymerization reaction or the first copolymerization reaction, the mass ratio of hydrogen to the C3-C12 α-olefin to ethylene is (0.002-7.0):(0-3):1.

[0043] According to a preferred embodiment of the present invention, in the second copolymerization reaction, the mass ratio of hydrogen to the C3-C12 α-olefin to ethylene is (0.002-0.3):(0.002-1):1.

[0044] According to a preferred embodiment of the present invention, the catalyst comprises a metal coordination catalyst; preferably, the catalyst is selected from at least one of Ziegler-Natta catalysts (ZN catalysts), metallocene catalysts, non-metallocene catalysts, and chromium catalysts; most preferably, it is a Ziegler-Natta catalyst. Using the aforementioned catalysts to prepare polyethylene compositions is advantageous for achieving a wide distribution and low flowability of bimodal polyethylene polymers.

[0045] According to the present invention, the co-catalyst is selected from one or more of trialkylaluminum and alkylaluminum halides, preferably, the co-catalyst is selected from triethylaluminum; using the aforementioned co-catalyst to prepare the polyethylene composition is beneficial to achieving a wide distribution and low flowability of bimodal polyethylene polymer.

[0046] According to the present invention, each catalyst can be independently loaded or unloaded on a support. According to a preferred embodiment of the present invention, the catalyst is loaded on a support selected from one or more of aluminum-containing supports, silica-containing supports, and magnesium dichloride-based supports. Loading the catalyst on a support is beneficial for achieving a wide distribution and low flowability of bimodal polyethylene polymer.

[0047] According to a preferred embodiment of the present invention, the catalyst is a TiCl4 catalyst supported on MgCl2; preferably, the co-catalyst is triethylaluminum.

[0048] According to a third aspect of the invention, the invention provides an application of the bimodal polyethylene polymer in stone paper.

[0049] According to a fourth aspect of the present invention, the present invention provides stone paper comprising the bimodal polyethylene polymer described in the first aspect of the present invention and the bimodal polyethylene polymer prepared by the preparation method of the present invention; the bimodal polyethylene polymer provided by the present invention is used in stone paper and has good compatibility with calcium carbonate, so that the produced stone paper is of uniform thickness, and the printed text is clear and the pattern is brightly colored.

[0050] According to a preferred embodiment of the present invention, the CV value of the stone paper is 1%-4.5, preferably 1%-3%; within this range of CV values, the stone paper has a uniform thickness.

[0051] According to the present invention, the density of stone paper is related to the amount of polyethylene added; the greater the amount added, the higher the density of the blown film. Preferably, the density of the stone paper is 1.15 g / cm³. 3 .

[0052] According to a preferred embodiment of the present invention, the stiffness of the stone paper is 0.1-0.6, preferably 0.3-0.5.

[0053] The present invention will be described in detail below through embodiments, but it should be understood that the scope of protection of the present invention is not limited to the embodiments.

[0054] In the following examples, the testing method for bimodal polyethylene polymers includes:

[0055] 1) Test method for melt flow rate; GB / T3682-2000.

[0056] 2) Density test method: GB / T 1033-1996D method.

[0057] 3) Molecular weight correlation test: The test method used was gel permeation chromatography: ASTM 6474-12;

[0058] 4) Test method for methyl branching degree: GB / T 6040-2002.

[0059] Example 1

[0060] (1) Hexane was added to the first closed polymerization reactor. Under stirring, triethylaluminum co-catalyst and TiCl4 catalyst supported on MgCl2 were added. Ethylene was added to carry out homopolymerization. Hydrogen was used to adjust the molecular weight. The mass ratio of hydrogen to ethylene was 6:1. The reaction pressure was 0.6 MPa and the reaction temperature was 85 °C. After reacting for 1 h, polymer component A was obtained.

[0061] (2) Hexane was added to the second closed polymerization reactor. While stirring, triethylaluminum and TiCl4 supported on MgCl2 were added, along with ethylene, 1-butene, and hydrogen (hydrogen:1-butene:ethylene mass ratio of 0.02:0.006:1). Component A was then added to initiate a copolymerization reaction. The mass ratio of polymer component A to the materials in the second closed polymerization reactor before mixing was 1.8:1. The reaction pressure was 0.2 MPa, the reaction temperature was 78 °C, and the reaction time was 1.2 h to obtain a bimodal polyethylene polymer. The test results of the bimodal polyethylene polymer are shown in Table 1.

[0062] Example 2

[0063] (1) Hexane was added to the first closed polymerization reactor. Under stirring, triethylaluminum co-catalyst and TiCl4 catalyst supported on MgCl2 were added. Ethylene and 1-butene were added to carry out copolymerization reaction. The molecular weight was adjusted with hydrogen. The mass ratio of hydrogen to 1-butene to ethylene was 0.11:0.004:1. The reaction pressure was 0.6 MPa, the reaction temperature was 84 °C, and the reaction was carried out for 0.7 h to obtain component A.

[0064] (2) Hexane was added to the second closed polymerization reactor. While stirring, triethylaluminum co-catalyst and TiCl4 catalyst supported on MgCl2 were added, along with ethylene, 1-butene, and hydrogen (hydrogen:1-butene:ethylene mass ratio of 0.0014:0.006:1). Component A was then added to initiate a copolymerization reaction. The mass ratio of polymer component A to the materials in the second closed polymerization reactor before mixing was 1.1:1. The reaction pressure was 0.2 MPa, the reaction temperature was 76 °C, and the reaction time was 1.4 h to obtain bimodal polyethylene polymer. The test results of the bimodal polyethylene polymer are shown in Table 1.

[0065] Example 3

[0066] (1) Hexane was added to the first closed polymerization reactor. Under stirring, triethylaluminum co-catalyst and TiCl4 catalyst supported on MgCl2 were added. Ethylene was added to carry out homopolymerization reaction, and hydrogen was used to adjust the molecular weight. The mass ratio of hydrogen to 1-butene to ethylene was 0.11:0.003:1. The reaction pressure was 0.6 MPa and the reaction temperature was 85 °C. The reaction was carried out for 1 h to obtain component A.

[0067] (2) Hexane was added to the second closed polymerization reactor. While stirring, triethylaluminum and TiCl4 supported on MgCl2 were added, along with ethylene, 1-hexene, and hydrogen (hydrogen:1-hexene:ethylene mass ratio of 0.02:0.004:1). Component A was then added to initiate a copolymerization reaction. The mass ratio of polymer component A to the materials in the second closed polymerization reactor before mixing was 1.5:1. The reaction pressure was 0.2 MPa, the reaction temperature was 78 °C, and the reaction time was 1.2 h to obtain a bimodal polyethylene polymer. The test results of the bimodal polyethylene polymer are shown in Table 1.

[0068] Example 4

[0069] (1) Hexane was added to the first closed polymerization reactor. Under stirring, triethylaluminum co-catalyst and TiCl4 catalyst supported on MgCl2 were added. Ethylene and 1-butene were added to carry out copolymerization reaction. The molecular weight was adjusted with hydrogen. The mass ratio of hydrogen to 1-butene to ethylene was 0.09:0.01:1. The reaction pressure was 0.6 MPa, the reaction temperature was 84 °C, and the reaction was carried out for 0.7 h to obtain component A.

[0070] (2) Hexane was added to the second closed polymerization reactor. While stirring, triethylaluminum co-catalyst and TiCl4 catalyst supported on MgCl2 were added, along with ethylene, 1-butene, and hydrogen (hydrogen:1-butene:ethylene mass ratio of 0.01:0.006:1). Component A was then added to initiate a copolymerization reaction. The mass ratio of polymer component A to the materials in the second closed polymerization reactor before mixing was 1.1:1. The reaction pressure was 0.2 MPa, the reaction temperature was 76 °C, and the reaction time was 1.4 h to obtain a bimodal polyethylene polymer. The test results of the bimodal polyethylene polymer are shown in Table 1.

[0071] Table 1 shows the test results of the bimodal polyethylene polymers prepared in each example.

[0072]

[0073]

[0074] Examples 5-8 describe stone paper production processes involving the bimodal polyethylene polymers described in Examples 1-4, and the operations are as follows:

[0075] Phase 1: Internal mixing and extrusion granulation. Bimodal polyethylene polymer, processing aids, and stone powder are metered and fed into three separate feed tanks. The raw materials are internally mixed using a counter-rotating twin-screw extruder. The resulting lumpy material is then fed into a single-screw extruder, granulated, dried, and packaged for use in the next stage.

[0076] The second stage: blown film. The products from the mixing and extrusion are blown into a film with a thickness of 100 μm. The blown film machine used in this invention has a screw diameter of 200 mm, and the maximum blown film width can reach 1140 mm. The blown film temperatures are 135, 145, 142, 148, 150×3, 140×4, 155, 150, and 150℃.

[0077] (2) Parameter testing method for stone paper:

[0078] 1) CV value test method: The ratio of the standard deviation to the mean is called the coefficient of variation;

[0079] 2) Opacity test method: GB / T1543;

[0080] 3) Volatile matter: Calcination in a muffle furnace, and testing the amount that evaporates;

[0081] 4) Stiffness test method: GB / T 12914;

[0082] 5) Whiteness test method: GB / T 7974.

[0083] Table 2. Parameters of stone paper products prepared in each embodiment.

[0084]

[0085]

[0086] The bimodal polyethylene polymer provided by this invention is suitable for use in stone paper. It exhibits good compatibility with calcium carbonate, and the resulting stone paper can have a CV value of less than 3% and a density as high as 1.18 g / cm³. 3 With a stiffness of up to 0.4, it has achieved good technical results.

[0087] 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 inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An application of a bimodal polyethylene polymer in stone paper, characterized in that, The weight-average molecular weight of this bimodal polyethylene polymer is 20 × 10⁻⁶. 4 -40×10 4 Molecular weight distribution is 10-30; melt flow ratio (21.6 / 5.0) is 25-40; The melt index of the bimodal polyethylene polymer at 190℃ and a load of 5.0 kg is 0.05-1.8 g / 10 min; the melt index of the bimodal polyethylene polymer at 190℃ and a load of 21.6 kg is 10-14 g / 10 min; and the melt index of the bimodal polyethylene polymer at 190℃ and a load of 2.16 kg is 0.01-0.2 g / 10 min.

2. The application according to claim 1, wherein, The density of the bimodal polyethylene polymer is 0.95-0.96 g / cm³. 3 ; and / or The degree of methyl branching is 0.2-0.5 per 100°C.

3. The application according to claim 1, wherein, The bimodal polyethylene polymer contains: ethylene homopolymer and / or ethylene copolymer; the ethylene copolymer is a copolymer of ethylene monomer and C3-C12 α-olefin.

4. The application according to claim 3, wherein, The C3-C12 α-olefins are selected from C3-C8 α-olefins.

5. The application according to claim 4, wherein, The C3-C8 α-olefins are selected from one or more of propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene.

6. The application according to any one of claims 1-5, wherein, The preparation method of the bimodal polyethylene polymer includes: (1) In a reaction system containing a catalyst and a co-catalyst, ethylene is added to carry out a first homopolymerization reaction or ethylene and C3-C12 α-olefins are added to carry out a first copolymerization reaction, and the molecular weight is adjusted with hydrogen to obtain component A; (2) In a reaction system containing a catalyst and a co-catalyst, a mixture of ethylene and / or C3-C12 α-olefins and hydrogen, component B1, is added, followed by component A to carry out a second copolymerization reaction to obtain a bimodal polyethylene polymer; or In a reaction system containing a catalyst and a co-catalyst, ethylene, C3-C12 α-olefins and hydrogen are added to undergo a third copolymerization reaction to obtain polymer component B2, which is then subjected to a second copolymerization reaction with component A to obtain bimodal polyethylene polymer.

7. The application according to claim 6, wherein, The mass ratio of component A to component B1 is 1.1~1.8:1; the mass ratio of component A to component B2 is 1.1~1.8:

1.

8. The application according to claim 6, wherein, The conditions for the first homopolymerization and the first copolymerization each include: a reaction temperature of 60-100℃; a reaction time of 0.5-6 hours; and / or The second copolymerization reaction conditions include: a reaction temperature of 60-100℃; a reaction time of 0.5-6 hours; and / or The third copolymerization reaction conditions include: a reaction temperature of 60-100℃ and a reaction time of 0.5-6 hours.

9. The application according to claim 6, wherein, In the first homopolymerization reaction or the first copolymerization reaction, the mass ratio of hydrogen to the C3-C12 α-olefin to ethylene is (0.002-7.0):(0-3):1; and / or In the second copolymerization reaction, the mass ratio of hydrogen to the C3-C12 α-olefin to ethylene is (0.002-0.3):(0.002-1):

1.

10. The application according to claim 6, wherein, In steps (1) and (2), The catalyst is selected from at least one of Ziegler-Natta catalysts, metallocene catalysts, non-metallocene catalysts, and chromium catalysts; The co-catalyst is selected from one or more of trialkylaluminum and alkylaluminum halides; The catalyst is supported on a support selected from one or more of aluminum-containing supports, silica-containing supports, and magnesium dichloride-based supports.

11. The application according to claim 10, wherein, The catalyst is a Ziegler-Natta catalyst; the co-catalyst is selected from triethylaluminum.

12. A type of stone paper, characterized in that, The stone paper comprises the bimodal polyethylene polymer as described in any one of claims 1-11.

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