Process for the preparation of homopolypropylene and homopolypropylene

Abstract

The application provides a preparation method of homopolypropylene and the homopolypropylene. The preparation method comprises the following steps: adding propylene, a first catalyst, a second catalyst and a modifier into a first reactor of a double-loop reactor to perform a first polymerization reaction, and introducing hydrogen into the first reactor to obtain a first reaction product; adding a solid phase part in the first reaction product into a second reactor of the double-loop reactor to perform a second polymerization reaction, and obtaining a second reaction product; obtaining a solid phase part in the second reaction product and performing preset treatment to obtain a homopolypropylene base material; and mixing the homopolypropylene base material with a beta nucleating agent, and then performing extrusion granulation to obtain the homopolypropylene. The impact strength index and the load heat deformation temperature index of the homopolypropylene prepared by the method are simultaneously improved, and the performance requirements of filter plates of filter presses, power conduits and the like are met.

Description

Technical Field

[0001] This application relates to the field of polymer materials technology, and more specifically, to a method for preparing homopolymer polypropylene and a homopolymer polypropylene. Background Technology

[0002] Polypropylene possesses advantages such as good mechanical properties, low relative density, corrosion resistance, and ease of processing and molding, making it one of the fastest-growing and most actively developed synthetic resins. Its applications span numerous fields, including home appliances, daily necessities, packaging, transportation, and building materials. The most common form of polypropylene resin is homopolymer polypropylene, a partially crystalline thermoplastic typically produced through polymerization using Ziegler-Natta catalysts or metallocene catalysts.

[0003] Homopolymer polypropylene has high crystallinity and a melting point that can reach around 165℃, making it the hardest polypropylene material and possessing good heat resistance. However, this type of polypropylene has a significant drawback: it is relatively brittle, especially at low temperatures, and its impact resistance is poor. This limits its application in high-end fields such as filter press plates and electrical conduits.

[0004] Currently, to improve the impact resistance of homopolymer polypropylene, physical or chemical modification methods are often used to enhance the product's toughness. Physical modification mainly involves blending, filling, and adding toughening agents. Chemical modification primarily involves adding comonomers such as ethylene and butene during the polymerization stage. By randomly distributing these comonomers along the polypropylene backbone, the crystallinity is reduced, thereby improving impact resistance.

[0005] However, while the modification methods of related technologies improve the impact toughness of polypropylene, they also reduce the product's load heat distortion temperature, thereby reducing the product's heat resistance. Summary of the Invention

[0006] In view of this, this application provides a method for preparing homopolymer polypropylene and homopolymer polypropylene, aiming to at least solve one of the technical problems existing in the prior art or related art.

[0007] Specifically, this application is implemented through the following technical solution: According to a first aspect of this application, a method for preparing homopolymer polypropylene is proposed. The method includes: adding propylene, a first catalyst, a second catalyst, and a modifier into a first reactor of a double-loop reactor to carry out a first polymerization reaction, and introducing hydrogen gas into the first reactor to obtain a first reaction product; adding the solid phase portion of the first reaction product into a second reactor of the double-loop reactor to carry out a second polymerization reaction to obtain a second reaction product; obtaining the solid phase portion of the second reaction product and performing a pre-treatment to obtain a homopolymer polypropylene base material; mixing the homopolymer polypropylene base material with a β-nucleating agent and then extruding and granulating to obtain homopolymer polypropylene.

[0008] The method for preparing homopolymer polypropylene provided in this application involves adding a first catalyst, a second catalyst, and a modifier into a first reactor, while simultaneously introducing propylene and hydrogen into the first reactor to carry out a first polymerization reaction, thereby obtaining a first reaction product.

[0009] The solid phase of the first reaction product is collected and added to the second reactor for a second polymerization reaction to obtain the second reaction product. The solid phase of the second reaction product is collected and subjected to a pre-treatment to obtain a homopolymer polypropylene base material. The homopolymer polypropylene base material is mixed with a β nucleating agent and then extruded and granulated to prepare homopolymer polypropylene.

[0010] The homopolymer polypropylene prepared by the above method possesses advantages such as stable melt index control, good impact resistance, high heat distortion temperature under load, and a good balance of rigidity and toughness. This means that both the impact strength and heat distortion temperature of homopolymer polypropylene can be improved simultaneously, resolving the contradiction in related technologies where it is difficult to simultaneously improve impact resistance and heat distortion temperature in polypropylene modification. This meets the performance requirements of filter press plates, power conduits, and other applications. Furthermore, the above preparation method allows for stable production in a loop process, with controllable process flow and high production stability.

[0011] It is understandable that hydrogen is introduced into the first reactor, but not into the second reactor, that is, the flow rate of the melt in the first reactor is controlled by asymmetric hydrogenation.

[0012] In addition, β-nucleating agents are one of the key factors that enable homopolymer polypropylene to have both high impact resistance and high heat resistance. In other words, by adding β-nucleating agents, the impact resistance and heat resistance of homopolymer polypropylene products can be improved.

[0013] In some embodiments, the reaction temperature of the first reactor is 69°C to 72°C, and the reaction pressure is 3.3 MPa to 3.5 MPa.

[0014] In some embodiments, the reaction temperature of the second reactor is 69°C to 72°C, and the reaction pressure is 3.3 MPa to 3.5 MPa.

[0015] In some embodiments, the β-nucleating agent is an organometallic salt β-nucleating agent.

[0016] In some embodiments, homopolymer polypropylene base material is mixed with β nucleating agent and then extruded and granulated to obtain homopolymer polypropylene. Specifically, this includes: mixing homopolymer polypropylene base material with β nucleating agent and then extruding and granulating using an extruder, wherein the heating temperature of the extruder is 170°C to 290°C.

[0017] In some embodiments, the ratio of hydrogen to propylene is 0.005% to 0.05%.

[0018] In some embodiments, the ratio of hydrogen to propylene is 0.01% to 0.03%.

[0019] In some embodiments, the slurry concentration of the dual-loop reactor is 500 kg / m³. 3 ~580kg / m 3 .

[0020] In some embodiments, the slurry concentration of the dual-loop reactor is 540 kg / m³. 3 ~560kg / m 3 .

[0021] In some embodiments, the first catalyst is a titanium-based catalyst, specifically Lynx 1000HA.

[0022] In some embodiments, the activity of the first catalyst is ≥20000 kgPP / kgCat.

[0023] In some embodiments, the activity of the first catalyst is ≥25000 kgPP / kgCat.

[0024] In some embodiments, the second catalyst is triethylaluminum.

[0025] In some embodiments, the ratio of triethylaluminum to propylene is 0.1 kg / t to 0.24 kg / t.

[0026] In some embodiments, the ratio of triethylaluminum to propylene is 0.12 kg / t to 0.2 kg / t.

[0027] In some embodiments, the modifier is cyclohexylmethyldimethoxysilane or dicyclopentyldimethoxysilane.

[0028] In some embodiments, when the modifier is cyclohexylmethyldimethoxysilane, the ratio of the amount of cyclohexylmethyldimethoxysilane to the amount of propylene is 0.008 kg / t to 0.08 kg / t.

[0029] In some embodiments, the ratio of the amount of cyclohexylmethyldimethoxysilane to the amount of propylene is 0.01 kg / t to 0.08 kg / t.

[0030] In some embodiments, the solid phase portion of the second reaction product is obtained and subjected to a preset treatment to obtain a homopolymer polypropylene base material, specifically including: devolatilizing and deactivating the solid phase portion of the obtained second reaction product to obtain a homopolymer polypropylene base material.

[0031] According to a second aspect of this application, this application provides a homopolymer polypropylene, which is prepared by the preparation method of homopolymer polypropylene as provided in any of the above technical solutions.

[0032] The technical solution provided in this application brings at least the following beneficial effects: The homopolymer polypropylene prepared by the above method possesses advantages such as stable melt index control, good impact resistance, high heat distortion temperature under load, and a good balance of rigidity and toughness. This means that both the impact strength and heat distortion temperature of homopolymer polypropylene can be improved simultaneously, resolving the contradiction in related technologies where it is difficult to simultaneously improve impact resistance and heat distortion temperature in polypropylene modification. This meets the performance requirements of filter press plates, power conduits, and other applications. Furthermore, the above preparation method allows for stable production in a loop process, with controllable process flow and high production stability. Attached Figure Description

[0033] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0034] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0035] Figure 1 A flowchart illustrating a method for preparing homopolymer polypropylene according to an embodiment of this application is shown. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0037] Figure 1 The illustration schematically shows a method for preparing homopolymer polypropylene and homopolymer polypropylene applicable to embodiments of this application.

[0038] In one embodiment according to this application, such as Figure 1 As shown, a method for preparing homopolymer polypropylene is proposed, the method including: Step 102: Propylene, the first catalyst, the second catalyst and the modifier are added to the first reactor of the double loop reactor to carry out the first polymerization reaction, and hydrogen is introduced into the first reactor to obtain the first reaction product; Step 104: The solid phase of the first reaction product is added to the second reactor in the double-loop reactor to carry out the second polymerization reaction, and the second reaction product is obtained. Step 106: Obtain the solid phase portion of the second reaction product and perform a preset treatment to obtain homopolymer polypropylene base material; Step 108: The homopolymer polypropylene base material is mixed with the β nucleating agent and then extruded and granulated to obtain homopolymer polypropylene.

[0039] Polypropylene possesses advantages such as good mechanical properties, low relative density, corrosion resistance, and ease of processing and molding, making it one of the fastest-growing and most actively developed synthetic resins. Its applications span numerous fields, including home appliances, daily necessities, packaging, transportation, and building materials. The most common form of polypropylene resin is homopolymer polypropylene, a partially crystalline thermoplastic typically produced through polymerization using Ziegler-Natta catalysts or metallocene catalysts.

[0040] Homopolymer polypropylene has high crystallinity and a melting point that can reach around 165℃, making it the hardest polypropylene material and possessing good heat resistance. However, this type of polypropylene has a significant drawback: it is relatively brittle, especially at low temperatures, and its impact resistance is poor. This limits its application in high-end fields such as filter press plates and electrical conduits.

[0041] Currently, to improve the impact resistance of homopolymer polypropylene, physical or chemical modification methods are often used to enhance the product's toughness. Physical modification mainly involves blending, filling, and adding toughening agents. Chemical modification primarily involves adding comonomers such as ethylene and butene during the polymerization stage. By randomly distributing these comonomers along the polypropylene backbone, the crystallinity is reduced, thereby improving impact resistance.

[0042] However, while modifying polypropylene to improve its impact toughness, this process also reduces the product's heat distortion temperature under load, thus decreasing its heat resistance. Applications such as filter press plates and electrical conduits require polypropylene to possess both high impact resistance and high heat resistance; generally, a simply supported beam impact strength greater than 90 kJ / m² and a heat distortion temperature greater than 90°C are needed. However, achieving both simultaneously is difficult and presents significant production challenges.

[0043] The method for preparing homopolymer polypropylene provided in this application involves adding a first catalyst, a second catalyst, and a modifier into a first reactor, while simultaneously introducing propylene and hydrogen into the first reactor to carry out a first polymerization reaction, thereby obtaining a first reaction product.

[0044] The solid phase of the first reaction product is collected and added to the second reactor for a second polymerization reaction to obtain the second reaction product. The solid phase of the second reaction product is collected and subjected to a pre-treatment to obtain a homopolymer polypropylene base material. The homopolymer polypropylene base material is mixed with a β nucleating agent and then extruded and granulated to prepare homopolymer polypropylene.

[0045] The homopolymer polypropylene prepared by the above method possesses advantages such as stable melt index control, good impact resistance, high heat distortion temperature under load, and a good balance of rigidity and toughness. This means that both the impact strength and heat distortion temperature of homopolymer polypropylene can be improved simultaneously, resolving the contradiction in related technologies where it is difficult to simultaneously improve impact resistance and heat distortion temperature in polypropylene modification. This meets the performance requirements of filter press plates, power conduits, and other applications. Furthermore, the above preparation method allows for stable production in a loop process, with controllable process flow and high production stability.

[0046] It is understandable that hydrogen is introduced into the first reactor, but not into the second reactor, that is, the flow rate of the melt in the first reactor is controlled by asymmetric hydrogenation.

[0047] In addition, β-nucleating agents are one of the key factors that enable homopolymer polypropylene to have both high impact resistance and high heat resistance. In other words, by adding β-nucleating agents, the impact resistance and heat resistance of homopolymer polypropylene products can be improved.

[0048] In detail, propylene is added to a double-loop reactor. Polymerization is carried out in the presence of a catalyst (first catalyst), an alkylaluminum co-catalyst (second catalyst), and a silane modifier (modifier) ​​under the conditions of a reaction temperature of 69℃~72℃ and a reaction pressure of 3.3MPa~3.5MPa in the first reactor and a reaction temperature of 69℃~72℃ and a reaction pressure of 3.3MPa~3.5MPa in the second reactor. During the polymerization process, H2 is introduced into the reactor to control the melt flow rate, resulting in a β-crystalline low-melting homopolymer polypropylene material with a melt flow rate of 0.15 g / 10min~0.35 g / 10min (230℃, 2.16 kg), a weight-average molecular weight of 450,000~550,000, a molecular weight distribution of 3.5~5.5, a β-crystal content ≥70%, a simply supported beam impact strength ≥90 kJ / m2, and a heat distortion temperature ≥90℃. This material meets the performance requirements for filter plates in filter presses, power conduits, etc.

[0049] Among them, the melt flow rate of the high-impact, high-heat-resistant homopolymer polypropylene special material is 0.15 g / 10min to 0.35 g / 10min (230℃, 2.16 kg), and further, the melt flow rate is 0.2 to 0.3 g / 10min; the simply supported beam impact strength is ≥90 kJ / m. 2 Furthermore, the impact strength of the simply supported beam is ≥100 kJ / m. 2 ; β crystal content ≥80%, further, β crystal content ≥90%, heat distortion temperature ≥90%, further, heat distortion temperature ≥95%.

[0050] In some embodiments, the reaction temperature of the first reactor is 69°C to 72°C, and the reaction pressure is 3.3 MPa to 3.5 MPa.

[0051] In some embodiments, the reaction temperature of the second reactor is 69°C to 72°C, and the reaction pressure is 3.3 MPa to 3.5 MPa.

[0052] In this embodiment, homopolymer polypropylene is prepared by controlling the reaction temperature and pressure of the first and second reactors and using asymmetric hydrogenation. This results in low content of lumps, sticky materials, and fine powder during polymerization, making the process controllable and highly stable. Furthermore, the prepared homopolymer polypropylene possesses advantages such as stable melt index control, good impact resistance, high load heat distortion temperature, and good rigidity-toughness balance, meeting the performance requirements of filter press plates, power conduits, and other applications.

[0053] In some embodiments, the β-nucleating agent is an organometallic salt β-nucleating agent.

[0054] In this embodiment, it is understood that the β-nucleating agent is one of the key factors that enables homopolymer polypropylene to possess both high impact resistance and high heat resistance. However, the addition of the β-nucleating agent will cause changes in the rheological properties of polypropylene, resulting in excessively high melt temperature, increased power, and increased current in the extruder during the extrusion granulation process.

[0055] The β-nucleating agent is an organometallic salt β-nucleating agent. The selected β-nucleating agent ensures both the stability of the β-crystal form and the stability of the extruder barrel pressure.

[0056] In some embodiments, homopolymer polypropylene base material is mixed with β nucleating agent and then extruded and granulated to obtain homopolymer polypropylene. Specifically, this includes: mixing homopolymer polypropylene base material with β nucleating agent and then extruding and granulating using an extruder, wherein the heating temperature of the extruder is 170°C to 290°C.

[0057] In this embodiment, it is understood that thermal shearing can cause a loss of β-crystal form. By controlling the temperature of each section of the extruder between 170°C and 290°C, polypropylene with a high β-crystal content can be obtained, thereby improving the toughness and heat resistance of the homopolymer polypropylene product.

[0058] In some embodiments, the ratio of hydrogen to propylene is 0.005% to 0.05%.

[0059] In some embodiments, the ratio of hydrogen to propylene is 0.01% to 0.03%.

[0060] In some embodiments, the slurry concentration of the dual-loop reactor is 500 kg / m³. 3 ~580kg / m 3 .

[0061] In this embodiment, by adjusting the reaction temperature, reaction pressure, amount and method of hydrogen addition in the first and second reactors, as well as the slurry concentration in the double-loop reactor, the content of lumps, sticky materials and fine powders during the polymerization process is reduced, the process is controllable, and the production stability is high, thus successfully achieving the industrial-scale long-cycle production of β-crystalline low-melting homopolymer polypropylene.

[0062] The prepared high-impact and high-heat-resistant homopolymer polypropylene material has advantages such as stable melt index control, high impact strength, high load heat distortion temperature, good β-crystal stability, and good rigidity-toughness balance, which can meet the requirements of downstream filter press filter plates, power pipes, etc.

[0063] In some embodiments, the slurry concentration of the dual-loop reactor is 540 kg / m³. 3 ~560kg / m 3 .

[0064] In some embodiments, the first catalyst is a titanium-based catalyst.

[0065] In this embodiment, the first catalyst is the main catalyst. Specifically, the first catalyst is a novel catalyst system, namely an imported titanium-based catalyst, wherein the first catalyst is Lynx1000Ha from Grace Catalysts Inc. of the United States. The specific settings can be adjusted according to actual needs.

[0066] In some embodiments, the activity of the first catalyst is ≥20000 kgPP / kgCat.

[0067] In some embodiments, the activity of the first catalyst is ≥25000 kgPP / kgCat.

[0068] In some embodiments, the second catalyst is triethylaluminum.

[0069] In this embodiment, the second catalyst is a co-catalyst, specifically, the second catalyst is triethylaluminum (TEAL), with the molecular formula (C2H5)3Al.

[0070] In some embodiments, the ratio of triethylaluminum to propylene is 0.1 kg / t to 0.24 kg / t.

[0071] In some embodiments, the ratio of triethylaluminum to propylene is 0.12 kg / t to 0.2 kg / t.

[0072] In some embodiments, the modifier is cyclohexylmethyldimethoxysilane or dicyclopentyldimethoxysilane.

[0073] In this embodiment, the modifier is a silane modifier, i.e., an external electron donor. Specifically, the modifier can be cyclohexylmethyldimethoxysilane or dicyclopentyldimethoxysilane. The specific modifier can be set according to actual needs.

[0074] In some embodiments, when the modifier is cyclohexylmethyldimethoxysilane, the ratio of the amount of cyclohexylmethyldimethoxysilane to the amount of propylene is 0.008 kg / t to 0.08 kg / t.

[0075] In some embodiments, the ratio of the amount of cyclohexylmethyldimethoxysilane to the amount of propylene is 0.01 kg / t to 0.08 kg / t.

[0076] In some embodiments, the solid phase portion of the second reaction product is obtained and subjected to a preset treatment to obtain a homopolymer polypropylene base material, specifically including: devolatilizing and deactivating the solid phase portion of the obtained second reaction product to obtain a homopolymer polypropylene base material.

[0077] In this embodiment, the solid phase of the second reaction product is sequentially devolatilized and deactivated to obtain homopolymer polypropylene base material, that is, the solid phase of the second reaction product is subjected to a pre-treatment.

[0078] Example 1 Propylene raw material was placed in a double-loop reactor, using a novel catalyst, Lynx1000Ha from Grace Catalysts Inc. (USA). The co-catalyst was TEAL, and the silane modifier was DONOR-C. TEAL / C3 = 0.16 kg / t, DONOR / C3 = 0.06 kg / t. The reaction temperature was 69℃, the reaction pressure was 3.3 MPa, and the H2 / C3 ratio was 0.02%. Polymerization was carried out, and additive A was added to the polymerization product. The product was then granulated using an extruder to form finished particles.

[0079] Example 2 Propylene raw material was placed in a double-loop reactor, using a novel catalyst, Lynx1000Ha from Grace Catalysts Inc. (USA). The co-catalyst was TEAL, and the silane modifier was DONOR-C. TEAL / C3 = 0.16 kg / t, DONOR / C3 = 0.07 kg / t. The reaction temperature was 70℃, the reaction pressure was 3.4 MPa, and the H2 / C3 ratio was 0.019%. Polymerization was carried out, and additive A was added to the polymerization product. The product was then granulated using an extruder to form finished particles.

[0080] Example 3 Propylene raw material was placed in a double-loop reactor, using a novel catalyst, Lynx1000Ha from Grace Catalysts Inc. (USA). The co-catalyst was TEAL, and the silane modifier was DONOR-C. TEAL / C3 = 0.16 kg / t, DONOR / C3 = 0.05 kg / t. The reaction temperature was 71℃, the reaction pressure was 3.4 MPa, and the H2 / C3 ratio was 0.021%. Polymerization was carried out, and additive A was added to the polymerization product. The product was then granulated using an extruder to form finished particles.

[0081] Example 4 Propylene raw material was placed in a double-loop reactor, using a novel catalyst, Lynx1000Ha from Grace Catalysts Inc. (USA). The co-catalyst was TEAL, and the silane modifier was DONOR-C. TEAL / C3 = 0.16 kg / t, DONOR / C3 = 0.08 kg / t, the reaction temperature was 69℃, the reaction pressure was 3.3 MPa, and the H2 / C3 ratio was 0.022%. Polymerization was carried out, and additive A was added to the polymerization product. The product was then granulated using an extruder to form finished particles.

[0082] Example 5 Propylene raw material was placed in a double-loop reactor, using a novel catalyst, Lynx1000Ha from Grace Catalysts Inc. (USA). The co-catalyst was TEAL, and the silane modifier was DONOR-C. TEAL / C3 = 0.16 kg / t, DONOR / C3 = 0.04 kg / t. The reaction temperature was 69℃, the reaction pressure was 3.3 MPa, and the H2 / C3 ratio was 0.023%. Polymerization was carried out, and additive A was added to the polymerization product. The product was then granulated using an extruder to form finished particles.

[0083] Comparative Example 6 Propylene raw material was placed in a double-loop reactor, using a novel catalyst, Lynx1000Ha from Grace Catalysts Inc. (USA). The co-catalyst was TEAL, and the silane modifier was DONOR-C. TEAL / C3 = 0.16 kg / t, DONOR / C3 = 0.06 kg / t, the reaction temperature was 69℃, the reaction pressure was 3.3 MPa, and the H2 / C3 ratio was 0.018%. Polymerization was carried out, and additive B was added to the polymerization product. The product was then granulated using an extruder to form finished particles.

[0084] The homopolymer polypropylene materials prepared in Examples 1 to 5 and the comparative examples were tested, and the results are shown in Table 1. .

[0085] It is understandable that additive A is an organometallic salt β-nucleating agent, while additive B is an organometallic salt β-nucleating agent.

[0086] According to a second aspect of this application, a homopolymer polypropylene is provided, which is prepared using the preparation method of homopolymer polypropylene as provided in any of the above embodiments. Therefore, this homopolymer polypropylene possesses all the beneficial effects of the preparation method of homopolymer polypropylene described in any of the above embodiments.

[0087] In the description of this specification, all quantities involving temperature, including expressions, are in degrees Celsius. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance unless otherwise expressly specified and limited. The terms "connection," "installation," and "fixing," etc., should be interpreted broadly. For example, "connection" can mean a fixed connection, a detachable connection, or an integral connection; it can mean a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0088] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0089] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing homopolymer polypropylene, characterized in that, The preparation method includes: Propylene, a first catalyst, a second catalyst, and a modifier are added to the first reactor of a double-loop reactor to carry out a first polymerization reaction, and hydrogen is introduced into the first reactor to obtain the first reaction product. The solid phase of the first reaction product is added to the second reactor in the double loop reactor to carry out a second polymerization reaction. No hydrogen gas is introduced into the second reactor to obtain the second reaction product. The solid phase of the second reaction product is obtained and subjected to a preset treatment to obtain homopolymer polypropylene base material; The homopolymer polypropylene base material is mixed with a β nucleating agent and then extruded and granulated to obtain the homopolymer polypropylene. The preset treatment includes devolatilization and deactivation of the solid phase portion in the obtained second reaction product. The homopolymer polypropylene has a melt flow rate of 0.2–0.3 g / 10 min; and a simply supported beam impact strength ≥100 kJ / m. 2 β crystal content ≥80%; heat distortion temperature ≥95℃; The reaction temperature of the first reactor is 69℃~72℃, and the reaction pressure is 3.3MPa~3.5MPa; The reaction temperature in the second reactor is 69℃~72℃, and the reaction pressure is 3.3MPa~3.5MPa; The β-nucleating agent is an organometallic salt β-nucleating agent.

2. The method for preparing homopolymer polypropylene according to claim 1, characterized in that, The process of mixing the homopolymer polypropylene base material with a β-nucleating agent and then extruding and granulating it to obtain the homopolymer polypropylene specifically includes: The homopolymer polypropylene base material was mixed with a β-nucleating agent and then extruded and granulated using an extruder. The extruder is heated at a temperature of 170℃ to 290℃.

3. The method for preparing homopolymer polypropylene according to claim 1, characterized in that, The ratio of the amount of hydrogen to the amount of propylene is 0.005% to 0.05%.

4. The method for preparing homopolymer polypropylene according to claim 3, characterized in that, The ratio of the amount of hydrogen to the amount of propylene is 0.01% to 0.03%.

5. The method for preparing homopolymer polypropylene according to any one of claims 1 to 3, characterized in that, The slurry concentration of the dual-loop reactor is 500 kg / m³. 3 ~580kg / m 3 .

6. The method for preparing homopolymer polypropylene according to claim 5, characterized in that, The slurry concentration of the dual-loop reactor is 540 kg / m³. 3 ~560kg / m 3 .

7. The method for preparing homopolymer polypropylene according to any one of claims 1 to 3, characterized in that, The first catalyst is a titanium-based catalyst.

8. The method for preparing homopolymer polypropylene according to claim 7, characterized in that, The activity of the first catalyst is ≥20000kgPP / kgCat.

9. The method for preparing homopolymer polypropylene according to claim 8, characterized in that, The activity of the first catalyst is ≥25000kgPP / kgCat.

10. The method for preparing homopolymer polypropylene according to any one of claims 1 to 3, characterized in that, The second catalyst is triethylaluminum.

11. The method for preparing homopolymer polypropylene according to claim 10, characterized in that, The ratio of the amount of triethylaluminum used to the amount of propylene used is 0.1 kg / t to 0.24 kg / t.

12. The method for preparing homopolymer polypropylene according to claim 11, characterized in that, The ratio of the amount of triethylaluminum used to the amount of propylene used is 0.12 kg / t to 0.2 kg / t.

13. The method for preparing homopolymer polypropylene according to any one of claims 1 to 3, characterized in that, The modifier is cyclohexylmethyldimethoxysilane or dicyclopentyldimethoxysilane.

14. The method for preparing homopolymer polypropylene according to claim 13, characterized in that, When the modifier is cyclohexylmethyldimethoxysilane, the ratio of the amount of cyclohexylmethyldimethoxysilane to the amount of propylene is 0.008 kg / t to 0.08 kg / t.

15. The method for preparing homopolymer polypropylene according to claim 14, characterized in that, The ratio of the amount of cyclohexylmethyldimethoxysilane used to the amount of propylene used is 0.01 kg / t to 0.08 kg / t.

16. A homopolymer polypropylene, characterized in that, The homopolymer polypropylene is prepared by the method for preparing homopolymer polypropylene as described in any one of claims 1 to 15.

Images