Olefin polymerization catalyst component and process combination method

Abstract

The present application relates to the technical field of catalyst preparation, and discloses an olefin polymerization catalyst component and a process combination method. The catalyst comprises: (A) component 1: the component 1 comprises a solid titanium catalyst component of Mg, Ti, Si, Cl elements and tetrahydrofuran; (B) component 2: the component 2 is selected from one or more of thiophene, tetrahydrothiophene and trimethylene sulfide; (C) component 3: an organic aluminum compound with a general formula of AlR d X” 3‑d X” l -C 20 hydrocarbon group, and X”’ is a halogen atom, 0

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation technology, specifically to a method for combining catalyst components and processes for olefin polymerization. Background Technology

[0002] The biggest drawback of rotational molding is the need for prolonged high-temperature heating, resulting in high energy consumption and low efficiency. This is primarily due to the unique nature of its processing technology. Rotational molding raw materials must be powders, and the process is pressureless, inevitably leading to the presence of air bubbles. Current methods for eliminating air bubbles in the product mainly involve increasing the temperature and extending the heating time. Extending the time can expel air bubbles from the melt to some extent, but it easily leads to accelerated thermal oxidation of the material, causing discoloration at best and a decline in mechanical properties at worst. Increasing the temperature can theoretically reduce the viscosity of the melt, facilitating bubble expulsion, but it still faces degradation and high energy consumption issues. It is clear that extending the time and increasing the temperature cannot completely solve the air bubble problem; they can only control it to a certain extent. Because there is no pressure acting on the melt during processing, it is difficult to expel air bubbles through heating alone. Therefore, to achieve efficient rotational molding of products, breakthroughs are needed in the base resin. These breakthroughs in base resin performance must be achieved through the organic combination of catalyst systems and polymerization processes.

[0003] Over the past 60 years, thanks to continuous technological advancements, the activity, hydrogen sensitivity, copolymerization performance, and parameters of Ziegler-Natta type polyolefin catalysts, including the bulk density, melt index, molecular weight distribution, fine powder content, and copolymer unit distribution of their polymer powders, have all been significantly optimized. However, to better meet the demands of industrial production and produce products with superior performance, these parameters of such catalysts and their polymer powders still need further improvement.

[0004] In existing technologies, internal electron donors are typically introduced into catalysts to improve their hydrogen-modulated sensitivity. CN1958620A introduces siloxane electron donors; CN1743347A introduces ortho-alkoxy-substituted benzoic acid ester / carboxylic acid ester (or diether) complex electron donors; CN102295717A and CN103772536A introduce benzoic acid ester compounds as electron donors, thereby improving the catalyst's hydrogen-modulated sensitivity. The copolymerization performance of catalysts can also be improved by introducing internal / external electron donors, such as CN1726230A, CN1798774A, and CN101050248A, which introduce electron donors such as alcohols, ketones, amines, amides, nitriles, alkoxysilanes, aliphatic ethers, and aliphatic carboxylic acid esters, respectively.

[0005] According to published patents and literature, introducing external electron donors to adjust polymer properties during the polymerization of Ziegler-Natta type polypropylene catalysts is a well-known technique in this field. However, reports on introducing external electron donors during the polymerization of Ziegler-Natta type polyethylene catalysts are less common. The inventors conducted in-depth research on this topic, and the results show that if external electron donors are introduced during the polymerization of Ziegler-Natta type polyethylene catalysts, parameters such as catalyst activity, hydrogen sensitivity, copolymerization performance, and the bulk density and copolymer unit content of the polymer powder cannot all be optimized; some properties may even decrease. This may explain why the technology of external electron donors for Ziegler-Natta type polyethylene catalysts has not yet been industrialized and is rarely reported in literature and patents.

[0006] Therefore, if a special type of external electron donor can be found, and combined with specific process operations, the performance of a certain type of product can be improved, it is a technological development with very high practical value. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing technologies where the introduction of external electron donors in the polymerization process of Ziegler-Natta type polyethylene catalysts leads to the inability to fully optimize the performance parameters of the catalyst. This invention provides a method for combining catalyst components and processes in olefin polymerization. In this olefin polymer, an external electron donor (component 2) is used, and through external addition technology, it is mixed online with catalyst components (component 1) and a portion of catalyst component 3. Subsequently, it works together with another component 3, enabling the prepared olefin polymer to improve the crystalline structure of the ethylene copolymer. Finally, it combines with additives (auxiliaries) to enhance the processing performance and product properties of rotomolded plastics.

[0008] To achieve the above objectives, a first aspect of the present invention provides an olefin polymer, wherein the olefin polymer comprises:

[0009] (A) Component 1: Component 1 contains solid titanium catalyst components of Mg, Ti, Si, Cl elements and tetrahydrofuran;

[0010] (B) Component 2: Component 2 is selected from one or more of thiophene, tetrahydrothiophene and trimethylene sulfide;

[0011] (C) Component 3: General formula AlR” d X”' 3-d Organoaluminum compounds, wherein R” is hydrogen or C l -C 20 Hydrocarbon group, X”' is a halogen atom, 0 <d≤3。

[0012] A second aspect of the present invention provides a method for preparing the aforementioned olefin polymer, wherein the preparation method comprises:

[0013] (1) Mix a portion of component 3 with component 2 and then mix it with component 1 to obtain component 4;

[0014] (2) Another part of component 3 is brought into contact with component 4 to react and obtain olefin polymer.

[0015] A third aspect of the present invention provides the application of the aforementioned olefin polymer in olefin homopolymerization and / or olefin copolymerization reactions.

[0016] A fourth aspect of the present invention provides an ethylene copolymer, wherein ethylene and α-olefin are copolymerized in the presence of an olefin polymerization catalyst to obtain the ethylene copolymer, wherein the olefin polymerization catalyst is the aforementioned olefin polymer.

[0017] A fifth aspect of the present invention provides a low-temperature rotational molding polyethylene composition, wherein the low-temperature rotational molding polyethylene composition comprises a polyethylene resin and an additive, wherein the polyethylene resin is the aforementioned ethylene copolymer.

[0018] The sixth aspect of the present invention provides a polyethylene rotational molding product, wherein the aforementioned low-temperature rotational molding polyethylene composition is granulated, ground, and rotationally molded to obtain the polyethylene rotational molding product.

[0019] Through the above technical solution, the present invention has the following beneficial effects:

[0020] Firstly, the catalyst employs an external electron donor (component 2). Due to the weak electron-donating property of heteroatoms in the external electron donor, the electron cloud density of the titanium active center can be moderately adjusted, which has the advantage of improving the copolymerization performance of the catalyst.

[0021] Secondly, through external addition technology, the external electron donor (component 2) and a portion of the catalyst (component 3) are mixed online with the catalyst component (component 1), and then introduced into the reactor together with another portion of the catalyst (component 3). This has the advantages of mild reaction conditions, timely and efficient operation, and few side reactions.

[0022] Thirdly, the production of rotational molding base resin, combined with selected additives, can reduce the processing temperature by 10-20°C, shorten the molding cycle by 10-20%, effectively improve the problems of degradation and high energy consumption, and reduce the risk of low-temperature brittleness of rotational molded products.

[0023] Fourthly, this raw material can be easily used to prepare one or more of recreational sports boats, military-grade boxes, and water tanks through rotational molding. The resulting products have good surface smoothness, no odor, good whiteness, good toughness, high stiffness, and are easy to demold. They also have good resistance to environmental stress and UV aging.

[0024] Fifthly, it improves production efficiency and has good economic benefits. Attached Figure Description

[0025] Figure 1 Product 1 prepared in Example 1: a 6.3-meter-long sports boat processed using the rotational molding raw material;

[0026] Figure 2 Product 2 is prepared in Example 2: a water tank processed using the rotational molding raw material. Detailed Implementation

[0027] 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.

[0028] A first aspect of the present invention provides an olefin polymer, wherein the olefin polymer comprises:

[0029] (A) Component 1: Component 1 contains solid titanium catalyst components of Mg, Ti, Si, Cl elements and tetrahydrofuran;

[0030] (B) Component 2: Component 2 is selected from one or more of thiophene, tetrahydrothiophene and trimethylene sulfide;

[0031] (C) Component 3: General formula AlR” d X”' 3-d Organoaluminum compounds, wherein R” is hydrogen or C l -C 20 Hydrocarbon group, X”' is a halogen atom, 0 <d≤3。

[0032] The inventors of this invention have discovered that by combining a specific component 2 (a sulfur-containing heterocyclic compound and an external electron donor) with a catalyst component (component 1) through an external addition technique, and by mixing a portion of catalyst component 3 online and then working together with another component 3, the responsiveness of the catalyst comonomer, such as ethylene copolymer, can be synergistically improved. Furthermore, by adjusting the process during polymerization production, the crystal structure of the base resin (ethylene copolymer) can be improved. Finally, by combining with additives, the processing performance and product performance of rotomolded plastics can be enhanced.

[0033] Furthermore, the inventors of this invention have discovered that using one or more sulfur-containing heterocyclic compounds selected from thiophene, tetrahydrothiophene, and trimethylene sulfide as external electron donors has the advantages of small molecular volume and low steric hindrance after coordination. Moreover, the inventors of this invention have discovered that using "organosiloxane compounds containing two thiophene substituents" or "compounds containing two thiophene substituents," due to their large molecular volume and the presence of multiple heteroatoms, resulting in strong coordination ability, is suitable for improving the orientation ability in propylene polymerization. However, in ethylene polymerization (where there is no requirement for stereoregularity because polyethylene lacks chiral carbon), this does not provide a beneficial effect and severely reduces the copolymerization performance of the catalyst.

[0034] The inventors employed a special type of external electron donor—sulfur-containing heterocyclic compounds. These external electron donors possess unique properties, and when used in conjunction with BSG catalysts, they can significantly improve the crystallization characteristics of the catalyst in the production of rotomolded resins in a gas-phase fluidized bed apparatus.

[0035] According to the present invention, and preferably in a further embodiment, component 1 comprises one or more of magnesium chloride, titanium chloride, silica gel, and tetrahydrofuran. In this invention, tetrahydrofuran acts as an internal electron donor, acting as a catalyst to protect magnesium chloride, titanium chloride, and silica gel, and can be prepared according to the catalyst preparation method described in CN106543316A.

[0036] According to the present invention, the weight ratio of the content of element S in component 2 to that of element titanium in component 1 is 1:(5-100), preferably 1:(10-30).

[0037] According to the present invention, the weight ratio of aluminum in component 3 to titanium in component 1 is (1-10):1, preferably (3-6):1.

[0038] In addition, it should be noted that the present invention uses an industrially available BSG catalyst, and the contents of the three main elements Ti, Mg and Si in component 1 are relatively fixed, and are implemented in accordance with the contents described in CN106543316A.

[0039] According to the present invention, the organoaluminum compound is selected from alkylaluminum compounds such as Al(CH3)3, Al(CH2CH3)3, Al(i-Bu)3, AlH(CH2CH3)2, AlH(i-Bu)2, AlCl(CH2CH3)2, Al2Cl3(CH2CH3)3, AlCl(CH2CH3)2, AlCl2(CH2CH3), and Al(CH2CH2CH2CH2CH2CH3)3, preferably Al(CH2CH3)3 and / or Al(i-Bu)3.

[0040] In this invention, it should be noted that i-Bu is CH3CH(CH3)CH2 (isobutyl).

[0041] A second aspect of the present invention provides a method for preparing the aforementioned olefin polymer, wherein the preparation method comprises:

[0042] (1) Mix a portion of component 3 with component 2 and then mix it with component 1 to obtain component 4;

[0043] (2) Another part of component 3 is brought into contact with component 4 to react and obtain an olefin polymerization catalyst.

[0044] In this invention, component 2 is not introduced during the catalyst preparation process, but rather after catalyst component 1 is prepared and before entering the reactor, it is pre-reacted with a suitable alkyl aluminum (component 3) with catalyst component 1 in a special pipeline system outside the reactor at a suitable temperature and for a suitable reaction time. After the reaction is complete, component 4 is generated and enters the main reactor to catalyze olefin polymerization.

[0045] In this invention, the catalyst component 4 is obtained by external supply. The molar ratio of the previously mentioned component 2 (sulfur-containing heterocyclic compound) to magnesium chloride in component 4 can be 0.01-0.1 mol, preferably 0.02-0.05 mol.

[0046] According to the present invention, component 1 is prepared as a white oil slurry with a concentration of 25-30 wt%; component 2 is prepared as a white oil slurry with a concentration of 0.1-3 wt%; preferably, component 2 is prepared as a white oil slurry with a concentration of 0.2-0.8 wt%.

[0047] According to the present invention, the component 3 includes tri-n-hexyl aluminum and diethylaluminum chloride, which are respectively prepared as white oil slurry with a concentration of 13-15 wt% and 49-51 wt%.

[0048] According to the present invention, the other component 3 is composed of triethylaluminum, which does not need to be prepared and is directly injected into the reactor by a reciprocating pump. The feed amount of the other component 3 is 0.01 wt% of the total ethylene feed amount.

[0049] According to the present invention, the feed flow rate of component 1 is 3-15 kg slurry / hour; the feed flow rate of component 2 is 0.1-2 kg slurry / hour; the feed flow rate of a portion of component 3 is 1-20 kg slurry / hour; and the feed flow rate of another portion of component 3 is 4-6 kg slurry / hour.

[0050] A third aspect of the present invention provides the application of the aforementioned olefin polymer in olefin homopolymerization and / or olefin copolymerization reactions.

[0051] A fourth aspect of the present invention provides an ethylene copolymer, wherein ethylene and α-olefin are copolymerized in the presence of an olefin polymerization catalyst to obtain the ethylene copolymer, wherein the olefin polymerization catalyst is the aforementioned olefin polymer.

[0052] According to the present invention, the α-olefin includes one or more of propylene, butene, pentene, hexene, and 4-methyl-1-pentene.

[0053] According to the present invention, hydrogen is used as a molecular weight regulator in order to adjust the molecular weight of the final polymer.

[0054] A fifth aspect of the present invention provides a low-temperature rotational molding polyethylene composition, wherein the composition comprises a polyethylene resin and an additive, wherein the polyethylene resin is the aforementioned ethylene copolymer.

[0055] According to the present invention, based on the total weight of the low-temperature rotationally molded polyethylene composition, the content of the polyethylene resin is 97-99.9% by weight, and the content of the additives is 0.1-3% by weight.

[0056] According to the present invention, the additives include one or more of the following: composite antioxidants, lubricants, antistatic agents, composite light stabilizers, and high-temperature defoaming agents.

[0057] According to the present invention, based on the total weight of the additives, the content of the composite antioxidant is 20-35% by weight, the content of the lubricant is 4-15% by weight, the content of the antistatic agent is 3-12% by weight, the content of the composite light stabilizer is 20-35% by weight, and the content of the high-temperature defoaming agent is 6-15% by weight; preferably, based on the total weight of the additives, the content of the composite antioxidant is 25-30% by weight, the content of the lubricant is 7-12% by weight, the content of the antistatic agent is 5-12% by weight, the content of the composite light stabilizer is 25-32% by weight, and the content of the high-temperature defoaming agent is 8-15% by weight.

[0058] According to the present invention, the composite antioxidant comprises a primary antioxidant and a secondary antioxidant, wherein the primary antioxidant is selected from one or more of 1076, 1010, 1330 and BHT; and the secondary antioxidant is preferably selected from one or more of 168, 626, 618 and DLTP.

[0059] According to the present invention, the weight ratio of the primary antioxidant to the secondary antioxidant is 1:(0.3-3).

[0060] According to the present invention, the lubricant is selected from one or more of zinc stearate, pentaerythritol stearate, magnesium stearate, calcium stearate and barium stearate.

[0061] According to the present invention, the antistatic agent is selected from one or more of ethoxylated aliphatic alkylamines, ethoxylated alkyl acid amines, and fatty acid polyol esters, wherein the aliphatic alkyl, alkyl acid, and fatty acid preferably have a carbon number of C. 10 -C 25 Further preferably, it is one or more of N,N-dihydroxyethyl octadecylamine, N,N-dimethyl laurylamine, and glyceryl monostearate.

[0062] According to the present invention, the composite light stabilizer is selected from two or more of UV531, UV329, UV1577, UV770, UV622, UV2020, UV944 and UV3346.

[0063] According to the present invention, the composite light stabilizer has an ash content of ≤0.1 parts by weight and a volatile content of ≤0.5 parts by weight.

[0064] According to the present invention, the high-temperature defoaming agent is selected from one or more of amides, polysiloxanes and wax oils, preferably one or more of ethylene bis-stearamide, erucamide, oleamide, PE wax and white oil.

[0065] According to the present invention, the weight ratio of the external lubricant to the antistatic agent and the high-temperature defoaming agent is 1:(0.8-1.5):(1.0-1.5).

[0066] According to the present invention, the density of the polyethylene resin is 0.925-0.945 g / cm³. 3 The melt flow index is 2-8 g / 10 min, the number average molecular weight (Mn) is 21000-31000, the molecular weight distribution is 4.5-4.6, the weight average molecular weight (Mw) is 85000-113000, the melting point is 125-129℃, and the crystallinity is 50-60%; preferably, the number average molecular weight (Mn) is 23500-24500 and the weight average molecular weight (Mw) is 95000-110000.

[0067] The sixth aspect of the present invention provides a polyethylene rotational molding product, wherein the aforementioned low-temperature rotational molding polyethylene composition is granulated, ground, and rotationally molded to obtain the polyethylene rotational molding product.

[0068] According to the present invention, the granulation is carried out using a twin-screw granulator, and the granulated material is ground into 35-mesh fine powder in a grinding mill to obtain a polyethylene composition powder for low-temperature rotational molding. A polyethylene rotationally molded product is obtained from the polyethylene composition powder for low-temperature rotational molding.

[0069] According to the present invention, the polyethylene rotationally molded product includes one or more of a sports boat, a military-grade box, and a water tank; preferably a sports boat.

[0070] The present invention will be described in detail below through embodiments.

[0071] In the following examples and comparative examples:

[0072] (1) Relative weight percentage of titanium in the catalyst system: determined by spectrophotometry;

[0073] (2) Composition of catalyst components: Liquid NMR was used. 1 H-NMR;

[0074] (3) Determination of polymer melt index (MI): According to GB / T 3682, load 2.16Kg;

[0075] (4) Content of copolymer units in powder: measured by liquid NMR. 13 C-NMR;

[0076] (5) All parameters inside the reactor are measured by online detectors and transmitted online to the main unit in the central control room;

[0077] (6) Determination of polymer density (D method): according to GB / T 1033.2;

[0078] (7) Low-temperature impact performance (-40℃): GB / T 39933-2021, "Low-temperature impact test for rotational molding";

[0079] (8) Powder flowability: GB / T 40934-2021, "Test method for flowability of rotational molding powder";

[0080] (9) Odor test: The products obtained during and after the production process are subjected to sensory testing by 10 people. If more than 2 people think that there is an odor, it is recorded as having an odor; otherwise, it is recorded as having no odor.

[0081] (10) Surface smoothness: The smoothness and flatness of the surface are observed by the naked eye, including whether there are a few small air bubbles. Combined with the feel of the surface, it is compared with the same product made of the control material to comprehensively evaluate the smoothness of the inner and outer surfaces of the product. If it is obviously smooth, free of small air bubbles, and has a relatively flat feel, it is rated as excellent; if it is relatively smooth, has a relatively flat feel, and has occasional small air bubbles on the edges, it is rated as good; if it does not look smooth enough, does not feel very flat, and has a few small air bubbles on the edges, it is rated as medium.

[0082] (11) Heating time (de-bubbling time): The time from when the mold frame (the mold filled with rotational molding powder is installed on the mold frame) is moved into the furnace cavity until the raw material is completely melted, the bubbles are eliminated, and the mold frame is removed from the heating furnace. The unit is minutes;

[0083] (12) Cooling time: The time from when the mold frame is removed from the heating furnace to when the product is removed from the mold, in minutes; Note: This product is cooled by a fan.

[0084] (13) Demolding ability: The degree of difficulty of pulling the product out of the mold by the uniform operator is judged and directly given as easy, medium and difficult.

[0085] (14) Rigidity: The stability of the boat and the degree of deformation of the hull are assessed when the boat travels at a certain speed on the river. Small deformation and high speed are rated as excellent. Relatively obvious deformation with some impact on speed is rated as good; significant deformation with a noticeable impact on speed is rated as average.

[0086] (15) Heat resistance: The engine part does not heat up or deform for a long time, which is recorded as excellent; the engine part is slightly deformed, which is recorded as good; the engine part is obviously deformed, which is recorded as medium.

[0087] Example 1

[0088] (I) Preparation of olefin polymers

[0089] (1) Preparation of catalyst component 1

[0090] The catalyst described in CN106543316A (application number 201510589972.3) has the following composition: Table 1 shows the composition of the catalyst slurry entering the reactor.

[0091] (2) Polymerization reaction

[0092] The main reactor is a gas-phase fluidized bed with a diameter of 5.5 meters and a straight section height of 17 meters.

[0093] During the trial, the production load remained stable at 52-60 tons of polyethylene per hour.

[0094] During the experiment, the ethylene feed rate was maintained at 53 tons / hour, the reactor temperature at 87℃, the total pressure at 2.2 MPa, and the ethylene partial pressure at 0.72 MPa. These data were required to remain stable. The product was required to have a density between 0.925 and 0.945 g / cm³. 3 The melt flow index at 190℃ under a 2.16 kg load is in the range of 2-8 g / 10 min. Based on the online test feedback of density and melt flow index, the feed rates of hydrogen and butene are automatically adjusted to adjust the hydrogen-to-ethylene ratio (hydrogen to ethylene ratio, used to adjust the product melt flow index) and the butene-to-ethylene ratio (butene to ethylene ratio, used to adjust the product density) in the reactor.

[0095] Catalyst component 1 was fed with a 28% concentration of white oil slurry at a feed flow rate of 8 kg slurry / hour.

[0096] Catalyst component 2 is thiophene, which is injected into the feed line of component 1 at a feed rate of 0.5 kg slurry / hour as a 3% concentration of white oil of the same grade, and then mixed evenly through static mixer 1.

[0097] A portion of the catalyst component 3 consists of tri-n-hexyl aluminum and diethylaluminum chloride, which are prepared as white oil slurries with concentrations of 14% and 50%, respectively. They are injected into the feed line of component 1 at feed rates of 10 kg slurry / hour and 3 kg slurry / hour, respectively, and mixed evenly through static mixers 2 and 3. The slurry is then injected into the reactor.

[0098] The other catalyst component 3 consists of triethylaluminum, which does not require preparation and is directly injected into the reactor at a feed rate of 5 kg / h.

[0099] The test lasted 72 hours. After the product indicators stabilized, the parameters inside the reactor were collected. See Table 2 for catalyst activity and sensitivity to slight adjustment.

[0100] (II) Preparation of Resin Products:

[0101] Step 1: Using the Unipol gas-phase process, ethylene and α-olefins were copolymerized to prepare a product with a melt index of 3.2 g / 10 min and a density of 0.938 g / cm³ at 190 °C under a load of 2.16 kg. 3 Linear medium-density polyethylene (powder), i.e. polyethylene resin.

[0102] Step 2: The 99.1 wt% linear medium-density polyethylene obtained in Step 1 and 0.9 wt% of an additive composition (22 wt% of composite antioxidants specifically 1010 and 168, 9 wt% of lubricant zinc stearate, 8 wt% of antistatic agent N,N-dihydroxyethyloctadecylamine, 25 wt% of composite light stabilizers UV2020 and UV944, and 11 wt% of defoaming agent erucamide) are blended and granulated using a twin-screw extruder (manufactured by CWP GmbH, Germany, model ZSK350) to obtain linear medium-density polyethylene composition granules. The extruder temperature is 240°C and the power is 6600 kW.

[0103] (III) Preparation of rotomolded plastic products:

[0104] The prepared polyethylene composition granules are ground into powder of about 35 mesh. A certain proportion of color powder is added, and the powdered material is injected into a mold. The mold is heated directly by an open flame and rotated longitudinally and laterally, so that the material is evenly distributed and melted in the inner cavity of the mold by its own gravity and centrifugal force. After cooling, the product is demolded to obtain a hollow product. Figure 1 As shown.

[0105] Example 2

[0106] The olefin polymer was prepared using the same method as in Example 1, except that the composition of catalyst component 1 is shown in Table 1.

[0107] In addition, the feed flow rate of catalyst component 2 is adjusted to 0.15 kg slurry / hour and injected into the feed pipeline of component 1, and then mixed evenly through static mixer 1.

[0108] A portion of the catalyst component 3 consists of tri-n-hexyl aluminum and diethylaluminum chloride, which are prepared as white oil slurries with concentrations of 14% and 50%, respectively. They are injected into the feed line of component 1 at feed rates of 11 kg slurry / hour and 3 kg slurry / hour, respectively, and mixed evenly through static mixers 2 and 3. The slurry is then injected into the reactor.

[0109] The other catalyst component, 3, consists of triethylaluminum and does not require preparation; it is directly injected into the reactor at a feed rate of 5.5 kg / hour.

[0110] The experiment lasted 72 hours. After the product indicators stabilized, the parameters inside the reactor were collected, as shown in Table 2.

[0111] The resin product was prepared using the same components and methods as in Example 1, and its characterization is shown in Table 3.

[0112] Rotational molding products were prepared using the same components and methods as in Example 1, and their characterization is shown in Table 4. Additionally, water tanks processed from this rotational molding material, such as… Figure 2 As shown.

[0113] Example 3

[0114] The system polymer was prepared using the same method as in Example 1, except that the composition of catalyst component 1 is shown in Table 1.

[0115] In addition, catalyst component 2 was replaced with tetrahydrothiophene, and the feed flow rate was the same as in Example 1.

[0116] The composition and dosage of one part of catalyst component 3 and the other part of catalyst component 3 are the same as in Example 1.

[0117] The experiment lasted 72 hours. After the product indicators stabilized, the parameters inside the reactor were collected, as shown in Table 2.

[0118] The resin product was prepared using the same components and methods as in Example 1, and its characterization is shown in Table 3.

[0119] Roller-on plastic articles were prepared using the same components and methods as in Example 1, and their characterization is shown in Table 4.

[0120] Example 4

[0121] The olefin polymer was prepared using the same method as in Example 1, except that the composition of catalyst component 1 is shown in Table 1.

[0122] In addition, catalyst component 2 was replaced with trimethylene sulfide, and the feed flow rate was the same as in Example 1.

[0123] The composition and dosage of one part of catalyst component 3 and the other part of catalyst component 3 are the same as in Example 1.

[0124] The experiment lasted 72 hours. After the product indicators stabilized, the parameters inside the reactor were collected, as shown in Table 2.

[0125] The resin product was prepared using the same components and methods as in Example 1, and its characterization is shown in Table 3.

[0126] Roller-on plastic articles were prepared using the same components and methods as in Example 1, and their characterization is shown in Table 4.

[0127] Example 5

[0128] The olefin polymer was prepared using the same method as in Example 1, except that the composition of catalyst component 1 is shown in Table 1.

[0129] In addition, catalyst component 2 was replaced with tetrahydrothiophene, and the feed flow rate was the same as in Example 2.

[0130] The composition and dosage of one part of catalyst component 3 and the other part of catalyst component 3 are the same as in Example 2.

[0131] The experiment lasted 72 hours. After the product indicators stabilized, the parameters inside the reactor were collected, as shown in Table 2.

[0132] The resin product was prepared using the same components and methods as in Example 1, and its characterization is shown in Table 3.

[0133] Roller-on plastic articles were prepared using the same components and methods as in Example 1, and their characterization is shown in Table 4.

[0134] Comparative Example 1

[0135] The olefin polymer was prepared using the same method as in Example 1, except that the composition of catalyst component 1 is shown in Table 1.

[0136] The experimental conditions were the same as in Example 1, but catalyst component 2 was not added.

[0137] The composition and dosage of one part of catalyst component 3 and the other part of catalyst component 3 are the same as in Example 1.

[0138] The experiment lasted 72 hours. After the product indicators stabilized, the parameters inside the reactor were collected, as shown in Table 2.

[0139] The resin product was prepared using the same components and methods as in Example 1, and its characterization is shown in Table 3.

[0140] Roller-on plastic articles were prepared using the same components and methods as in Example 1, and their characterization is shown in Table 4.

[0141] Comparative Example 2

[0142] The olefin polymer was prepared using the same method as in Example 1, except that the composition of catalyst component 1 is shown in Table 1.

[0143] The experimental conditions were the same as in Example 1, but the main catalyst was replaced with other domestically produced industrial catalysts for comparison.

[0144] The composition and dosage of one part of catalyst component 3 and the other part of catalyst component 3 are the same as in Example 2.

[0145] The experiment lasted 72 hours. After the product indicators stabilized, the parameters inside the reactor were collected, as shown in Table 2.

[0146] The resin product was prepared using the same components and methods as in Example 1, and its characterization is shown in Table 3.

[0147] Roller-on plastic articles were prepared using the same components and methods as in Example 1, and their characterization is shown in Table 4.

[0148] Table 1

[0149]

[0150]

[0151] Table 2

[0152]

[0153] Note: All the above data were obtained from online reactor testing after the reaction stabilized and the product's melt index and density were within the required range.

[0154] As shown in Table 2:

[0155] 1. Introducing sulfur-containing heterocyclic compounds as external electron donors into the catalyst polymerization system can improve the butene responsiveness of the catalyst in a fluidized bed reactor, resulting in a lower butene concentration in the reactor while obtaining products of the same density. This will bring benefits such as reduced butene consumption and improved powder flowability.

[0156] 2. The results of stable catalyst feed flow and stable reactor load clearly show that the introduction of such external electron donors has no impact on catalyst activity, and the catalyst activity remains stable, which is beneficial for stable reactor control.

[0157] 3. Increasing the amount of this type of external electron donor can, to some extent, improve the responsiveness of the comonomer.

[0158] Table 3

[0159]

[0160] Table 3 shows that the resin product obtained using the composite catalyst system has a slightly higher number-average molecular weight but a slightly wider molecular weight distribution, laying the foundation for simultaneously achieving good mechanical and processing properties. The flowability test of the powder after grinding indicates good particle size uniformity and distribution. According to domestic and international data, the optimal flowability is generally within the range of 22-28. Powder within this size range exhibits good flowability, indicating good resin grinding and molding properties. This lays the foundation for powder spreading and air bubble removal during subsequent rotational molding.

[0161] Table 4

[0162]

[0163] As can be seen from Table 4, the use of the new composite catalyst system improves the performance of rotational molding products from molding to product performance. The heating and cooling times of rotational molding are shortened, and the low-temperature impact performance of rotational molding products at -40℃ is improved.

[0164] 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. A process for the preparation of an olefin polymer, characterized by, The preparation method comprises: (1) mixing a part of component 3 with component 2 and then mixing with component 1 to obtain component 4; (2) contacting another part of component 3 with component 4 to react to obtain an olefin polymer; wherein the component 1 is prepared as a white oil slurry with a concentration of 25-30 wt%; the feeding flow rate of the component 1 is 3-15 kg slurry / hour; the component 2 is prepared as a white oil slurry with a concentration of 0.1-3 wt%; the feeding flow rate of the component 2 is 0.1-2 kg slurry / hour; in step (1), the part of component 3 comprises tri-n-hexylaluminum and dichlorodiethylaluminum, which are prepared as white oil slurries with concentrations of 13-15 wt% and 49-51 wt%, respectively; the feeding flow rate of the part of component 3 is 1-20 kg slurry / hour; in step (2), the other part of component 3 is triethylaluminum, and the feeding flow rate of the other part of component 3 is 4-6 kg slurry / hour; wherein the olefin polymer comprises: (A) component 1: the component 1 comprises a solid titanium catalyst component of Mg, Ti, Si, Cl elements and tetrahydrofuran; (B) component 2: the component 2 is selected from one or more of thiophene, tetrahydrothiophene and trimethylene sulfide; (C) Component 3: an organoaluminum compound of the formula AlR" d X" 3-d X" is a halogen atom, 0 < d < 3. l -C 20 hydrocarbyl group, X" is a halogen atom, 0 < d < 3.

2. The production method according to claim 1, wherein wherein, the weight ratio of the content of S element in the component 2 to the content of titanium element in the component 1 is 1:(5-100); and / or, the weight ratio of the content of aluminum element in the component 3 to the content of titanium element in the component 1 is (1-10):

1.

3. The production method according to claim 2, wherein wherein, the weight ratio of the content of S element in the component 2 to the content of titanium element in the component 1 is 1:(10-30); and / or, the weight ratio of the content of aluminum element in the component 3 to the content of titanium element in the component 1 is (3-6):

1.

4. The production method according to claim 1, wherein The organoaluminum compound is selected from one or more of Al(CH3)3, Al(CH2CH3)3, Al(i-Bu)3, AlH(CH2CH3)2, AlH(i-Bu)2, AlCl(CH2CH3)2, Al2Cl3(CH2CH3)3, AlCl2(CH2CH3), Al(CH2CH2CH2CH2CH2CH3)3 alkylaluminum compounds.

5. Use of the olefin polymer prepared by the preparation method of any one of claims 1-4 in olefin homopolymerization and / or olefin copolymerization reactions.

6. An ethylene copolymer, characterized in that, Ethylene and alpha-olefin are copolymerized in the presence of an olefin polymerization catalyst to obtain an ethylene copolymer, wherein the olefin polymerization catalyst is the olefin polymer prepared by the preparation method of any one of claims 1-4.

7. A low temperature rotational moulding polyethylene composition, characterized in that, The low-temperature rotational molding polyethylene composition comprises a polyethylene resin and an auxiliary agent, wherein the polyethylene resin is the ethylene copolymer of claim 6.

8. The composition of claim 7, wherein, The polyethylene resin has a density of 0.925 to 0.945 g / cm 3 a melt flow index of 2 to 8 g / 10 min, a number average molecular weight of 21,000 to 31,000, a molecular weight distribution of 4.5 to 4.6, and a weight average molecular weight of 85,000 to 113,000.

9. The composition of claim 7, wherein, The content of the polyethylene resin is 97-99.9 wt% and the content of the auxiliary agent is 0.1-3% based on the total weight of the low-temperature rotational molding polyethylene composition.

10. The composition of claim 9, wherein, The auxiliary agent comprises one or more of a composite antioxidant, a lubricant, an antistatic agent, a composite light stabilizer and a high-temperature bubble-removing agent.

11. The composition of claim 10, wherein, The content of the composite antioxidant is 20-35% by weight, the content of the lubricant is 4-15% by weight, the content of the antistatic agent is 3-12% by weight, the content of the composite light stabilizer is 20-35% by weight, and the content of the high-temperature bubble-removing agent is 6-15% by weight, based on the total weight of the auxiliary agent.

12. A polyethylene rotomoulded article characterised in that, The low-temperature rotational molding polyethylene composition in any one of claims 7-11 is subjected to granulation, grinding, rotational molding processing and molding treatment to obtain a polyethylene rotational molding product.

13. The polyethylene rotomolded article of claim 12, wherein, The polyethylene rotational molding product comprises one or more of a sports boat, a military box and a water tank.

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