Preparation method of homo-polypropylene and homo-polypropylene

Abstract

The invention provides a homo-polypropylene preparation method and homo-polypropylene, and 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-ring-tube reactor to carry out 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 in the double-ring-tube reactor, and carrying out a second polymerization reaction to obtain a second reaction product; obtaining a solid phase part in the second reaction product, and carrying out pre-treatment to obtain a homo-polypropylene base material; and mixing the homo-polypropylene base material with the beta nucleating agent, and extruding and granulating to obtain the homo-polypropylene. The impact strength index and the load thermal deformation temperature index of the homo-polypropylene prepared by the method are simultaneously improved, and the homo-polypropylene meets the performance requirements of a filter plate of a filter press, an electric conduit and the like.

Description

Technical Field

[0001] The present application relates to the technical field of polymer materials, and in particular to a preparation method of homopolypropylene and a homopolypropylene. Background Art

[0002] Polypropylene has the advantages of good mechanical properties, low relative density, corrosion resistance, and easy processing and molding. It has become one of the fastest growing and most actively developed varieties among synthetic resins. Its application range includes many fields such as home appliances, daily necessities, packaging, transportation, and building materials. The most common form of polypropylene resin is homopolymer polypropylene, which is a partially crystalline thermoplastic plastic, usually polymerized using Ziegler-Natta catalysts or metallocene catalysts.

[0003] Homopolymer polypropylene has high crystallinity and melting point, which can be as high as about 165°C. It is the hardest material among polypropylene products and has good heat resistance. However, this type of polypropylene has a significant disadvantage, that is, it is brittle, especially in low temperature environments, and has poor impact resistance. Therefore, its application in high-end fields such as filter press filter plates and power conduits is limited.

[0004] At present, in order to improve the impact resistance of homopolypropylene, physical modification or chemical modification is often used in the related art to improve the toughness of the product. In terms of physical modification, it mainly includes blending, filling, adding toughening agents, etc. In terms of chemical modification, it mainly includes adding comonomers such as ethylene and butene during the polymerization stage, and randomly distributing comonomers such as ethylene and butene on the main chain of polypropylene to reduce the crystallinity, thereby improving the impact resistance.

[0005] However, the modification method of the related art will reduce the load heat deformation temperature of the product while improving the impact toughness of polypropylene, thereby reducing the heat resistance of the product. Summary of the invention

[0006] In view of this, the present application provides a preparation method of homopolypropylene and homopolypropylene, aiming to solve at least one of the technical problems existing in the prior art or related technology.

[0007] Specifically, the present application is implemented through the following technical solutions: According to a first aspect of the present application, a method for preparing homopolypropylene is proposed, the preparation method comprising: 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 into the first reactor to obtain a first reaction product; adding a solid phase portion of the first reaction product to a second reactor of the double loop reactor to carry out a second polymerization reaction to obtain a second reaction product; obtaining a solid phase portion of the second reaction product and performing a preset treatment to obtain a homopolypropylene base material; mixing the homopolypropylene base material with a β-nucleating agent and then extruding and granulating to obtain a homopolypropylene.

[0008] The method for preparing homopolypropylene provided in the present application comprises adding a first catalyst, a second catalyst and a modifier into a first reactor, and simultaneously introducing propylene and hydrogen into the first reactor to carry out a first polymerization reaction to obtain a first reaction product.

[0009] The solid phase part of the first reaction product is collected, and the solid phase part of the first reaction product is added to a second reactor for a second polymerization reaction to obtain a second reaction product and the solid phase part of the second reaction product is collected, the solid phase part of the second reaction product is subjected to a preset treatment to obtain a homopolypropylene base material, the homopolypropylene base material is mixed with a β-nucleating agent and then extruded and granulated, thereby preparing homopolypropylene.

[0010] The homopolymer polypropylene prepared by the above method has the advantages of stable melt index control, good impact resistance, high load heat deformation temperature and good rigidity-toughness balance, that is, the impact strength index and load heat deformation temperature index of the homopolymer polypropylene can be improved at the same time, so that the contradiction that it is difficult to achieve simultaneous improvement of impact resistance and heat deformation temperature in polypropylene modification in the related technology can be solved, and the performance requirements of filter press filter plates, power conduits, etc. can be met. Moreover, the above preparation method can be stably produced in the ring pipe process, the process production process is controllable, and the production stability is high.

[0011] It can be understood 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 an asymmetric hydrogenation method.

[0012] In addition, the β-nucleating agent is one of the key factors that enable homopolypropylene to have both high impact resistance and high heat resistance. That is to say, by adding the β-nucleating agent, the impact resistance and heat resistance of the homopolypropylene product 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 beta nucleating agent is an organometallic salt-based beta nucleating agent.

[0016] In some embodiments, homopolypropylene base material is mixed with β-nucleating agent and then extruded and granulated to obtain homopolypropylene, which specifically includes: mixing homopolypropylene base material with β-nucleating agent, and then extruding and granulating with 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 double loop reactor is 500 kg / m 3 ~580kg / m 3 .

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

[0021] In some embodiments, the first catalyst is a titanium-based catalyst, specifically lynx1000HA.

[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 cyclohexylmethyldimethoxysilane to 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 predetermined treatment to obtain a homopolypropylene base material, specifically comprising: devolatilizing and deactivating the solid phase portion of the obtained second reaction product to obtain a homopolypropylene base material.

[0031] According to the second aspect of the present application, the present application provides a homopolypropylene, which is prepared by the preparation method of homopolypropylene provided by any of the above technical solutions.

[0032] The technical solution provided by this application brings at least the following beneficial effects: The homopolymer polypropylene prepared by the above method has the advantages of stable melt index control, good impact resistance, high load heat deformation temperature and good rigidity-toughness balance, that is, the impact strength index and load heat deformation temperature index of the homopolymer polypropylene can be improved at the same time, so that the contradiction that it is difficult to achieve simultaneous improvement of impact resistance and heat deformation temperature in polypropylene modification in the related technology can be solved, and the performance requirements of filter press filter plates, power conduits, etc. can be met. Moreover, the above preparation method can be stably produced in the ring pipe process, the process production process is controllable, and the production stability is high. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0034] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0035] Figure 1 A flow chart of a method for preparing homopolypropylene according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0037] Figure 1 The preparation method of homopolypropylene and homopolypropylene applicable to the embodiments of the present application are schematically shown.

[0038] In one embodiment according to the present application, Figure 1 As shown, a preparation method of homopolymer polypropylene is proposed, and the preparation method comprises: Step 102, 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 into the first reactor to obtain a first reaction product; Step 104, adding the solid phase part of the first reaction product to the second reactor in the double loop reactor to carry out a second polymerization reaction to obtain a second reaction product; Step 106, obtaining a solid phase portion of the second reaction product and performing a predetermined treatment to obtain a homopolymer polypropylene base material; Step 108, mixing the homopolypropylene base material and the β-nucleating agent, and then extruding and granulating to obtain homopolypropylene.

[0039] Polypropylene has the advantages of good mechanical properties, low relative density, corrosion resistance, and easy processing and molding. It has become one of the fastest growing and most actively developed varieties among synthetic resins. Its application range includes many fields such as home appliances, daily necessities, packaging, transportation, and building materials. The most common form of polypropylene resin is homopolymer polypropylene, which is a partially crystalline thermoplastic plastic, usually polymerized using Ziegler-Natta catalysts or metallocene catalysts.

[0040] Homopolymer polypropylene has high crystallinity and melting point, which can be as high as about 165°C. It is the hardest material among polypropylene products and has good heat resistance. However, this type of polypropylene has a significant disadvantage, that is, it is brittle, especially in low temperature environments, and has poor impact resistance. Therefore, its application in high-end fields such as filter press filter plates and power conduits is limited.

[0041] At present, in order to improve the impact resistance of homopolypropylene, physical modification or chemical modification is often used in the related art to improve the toughness of the product. In terms of physical modification, it mainly includes blending, filling, adding toughening agents, etc. In terms of chemical modification, it mainly includes adding comonomers such as ethylene and butene during the polymerization stage, and randomly distributing comonomers such as ethylene and butene on the main chain of polypropylene to reduce the crystallinity, thereby improving the impact resistance.

[0042] However, the modification method of the related technology will reduce the load heat deformation temperature of the product while improving the impact toughness of polypropylene, thereby reducing the heat resistance of the product. In the fields of filter press filter plates, power conduits, etc., polypropylene must have both high impact and high heat resistance. Generally, the simply supported beam impact strength is greater than 90 kJ / m2 and the heat deformation temperature is greater than 90°C. However, it is difficult to achieve the above two points at the same time, and the production is difficult.

[0043] The method for preparing homopolypropylene provided in the present application comprises adding a first catalyst, a second catalyst and a modifier into a first reactor, and simultaneously introducing propylene and hydrogen into the first reactor to carry out a first polymerization reaction to obtain a first reaction product.

[0044] The solid phase part of the first reaction product is collected, and the solid phase part of the first reaction product is added to a second reactor for a second polymerization reaction to obtain a second reaction product and the solid phase part of the second reaction product is collected, the solid phase part of the second reaction product is subjected to a preset treatment to obtain a homopolypropylene base material, the homopolypropylene base material is mixed with a β-nucleating agent and then extruded and granulated, thereby preparing homopolypropylene.

[0045] The homopolymer polypropylene prepared by the above method has the advantages of stable melt index control, good impact resistance, high load heat deformation temperature and good rigidity-toughness balance, that is, the impact strength index and load heat deformation temperature index of the homopolymer polypropylene can be improved at the same time, so that the contradiction that it is difficult to achieve simultaneous improvement of impact resistance and heat deformation temperature in polypropylene modification in the related technology can be solved, and the performance requirements of filter press filter plates, power conduits, etc. can be met. Moreover, the above preparation method can be stably produced in the ring pipe process, the process production process is controllable, and the production stability is high.

[0046] It can be understood 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 an asymmetric hydrogenation method.

[0047] In addition, the β-nucleating agent is one of the key factors that enable homopolypropylene to have both high impact resistance and high heat resistance. That is to say, by adding the β-nucleating agent, the impact resistance and heat resistance of the homopolypropylene product can be improved.

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

[0049] Among them, the melt flow rate of the high impact and high heat resistance homopolymer polypropylene special material is 0.15 g / 10min~0.35g / 10min (230℃, 2.16kg), and further, the melt flow rate is 0.2~0.3g / 10min; the simply supported beam impact strength is ≥90kJ / m 2 , further, simply supported beam impact strength ≥ 100 kJ / m 2 ; β crystal content ≥ 80%, further, β crystal content ≥ 90%, heat deformation temperature ≥ 90, further, heat deformation 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, by controlling the reaction temperature and reaction pressure of the first reactor and the second reactor, and adopting asymmetric hydrogenation to prepare homopolypropylene, the content of block material, sticky material and fine powder in the polymerization process is small, the process production process is controllable, and the production stability is high. The prepared homopolypropylene has the advantages of stable melt index control, good impact resistance, high load heat deformation temperature and good rigidity-toughness balance, and meets the performance requirements of filter press filter plates, power conduits, etc.

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

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

[0055] The β nucleating agent is an organic metal salt β nucleating agent. The selected β nucleating agent can not only ensure the stability of the β crystal form, but also keep the pressure of the extruder barrel stable.

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

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

[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 double loop reactor is 500 kg / m 3 ~580kg / m 3 .

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

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

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

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

[0065] In this embodiment, the first catalyst is a main catalyst, specifically, the first catalyst is a new catalyst system, that is, an imported titanium catalyst, wherein the first catalyst is Lynx1000Ha from Grace Catalyst Company of the United States. The specific configuration can be based on 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 a molecular formula of (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, that is, an external electron donor, and specifically, the modifier may be cyclohexylmethyldimethoxysilane or dicyclopentyldimethoxysilane, which may 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 cyclohexylmethyldimethoxysilane to 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 predetermined treatment to obtain a homopolypropylene base material, specifically comprising: devolatilizing and deactivating the solid phase portion of the obtained second reaction product to obtain a homopolypropylene base material.

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

[0078] Example 1 The raw material propylene was placed in a double loop reactor, and the new catalyst used was Lynx1000Ha from Grace Catalyst Company of the United States. The co-catalyst was TEAL, the silane modifier was DONOR-C, TEAL / C3=0.16kg / t, DONOR / C3=0.06kg / t, the reaction temperature was 69°C, the reaction pressure was 3.3MPa, H2 / C3=0.02%, and the polymerization reaction was carried out. The A additive was added to the polymerization product, and the finished particles were formed by granulation through an extruder.

[0079] Example 2 The raw material propylene is placed in a double loop reactor, and the new catalyst used is Lynx1000Ha from Grace Catalyst Company of the United States. The co-catalyst is TEAL, the silane modifier is DONOR-C, TEAL / C3=0.16kg / t, DONOR / C3=0.07kg / t, the reaction temperature is 70°C, the reaction pressure is 3.4MPa, H2 / C3=0.019%, and the polymerization reaction is carried out. The polymer product is added with additive A and granulated by an extruder to form finished particles.

[0080] Example 3 The raw material propylene was placed in a double loop reactor, and the new catalyst used was Lynx1000Ha from Grace Catalyst Company of the United States. The co-catalyst was TEAL, the silane modifier was DONOR-C, TEAL / C3=0.16kg / t, DONOR / C3=0.05kg / t, the reaction temperature was 71°C, the reaction pressure was 3.4MPa, H2 / C3=0.021%, and the polymerization reaction was carried out. The A additive was added to the polymerization product, and the finished particles were formed by granulation through an extruder.

[0081] Example 4 The raw material propylene was placed in a double loop reactor, and the new catalyst used was Lynx1000Ha from Grace Catalyst Company of the United States. The co-catalyst was TEAL, the silane modifier was DONOR-C, TEAL / C3=0.16kg / t, DONOR / C3=0.08kg / t, the reaction temperature was 69°C, the reaction pressure was 3.3MPa, H2 / C3=0.022%, and the polymerization reaction was carried out. The polymer product was added with additive A and granulated by an extruder to form finished particles.

[0082] Example 5 The raw material propylene was placed in a double loop reactor, and the new catalyst used was Lynx1000Ha from Grace Catalyst Company of the United States. The co-catalyst was TEAL, the silane modifier was DONOR-C, TEAL / C3=0.16kg / t, DONOR / C3=0.04kg / t, the reaction temperature was 69°C, the reaction pressure was 3.3MPa, H2 / C3=0.023%, and the polymerization reaction was carried out. The A additive was added to the polymerization product, and the finished particles were formed by granulation through an extruder.

[0083] Comparative Example 6 The raw material propylene is placed in a double loop reactor, and the new catalyst used is Lynx1000Ha from Grace Catalyst Company of the United States. The co-catalyst is TEAL, the silane modifier is DONOR-C, TEAL / C3=0.16kg / t, DONOR / C3=0.06kg / t, the reaction temperature is 69°C, the reaction pressure is 3.3MPa, H2 / C3=0.018%, and the polymerization reaction is carried out. The polymer product is added with additive B and granulated by an extruder to form finished particles.

[0084] Among them, the homopolymer polypropylene material products prepared in Examples 1 to 5 and the comparative example were tested for performance, and the results are shown in Table 1: .

[0085] It can be understood that the A additive is an organic metal salt β-nucleating agent, and the B additive is a non-organic metal salt β-nucleating agent.

[0086] According to the second aspect of the present application, the present application provides a homopolypropylene, which is prepared by the preparation method of homopolypropylene provided by any of the above embodiments. Therefore, the homopolypropylene has all the beneficial effects of any of the above preparation methods of homopolypropylene.

[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 cannot be understood as indicating or implying relative importance unless otherwise clearly specified and limited; the terms "connection", "installation", "fixation", etc. should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0088] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "specific embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0089] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing homopolypropylene, characterized in that: The preparation method comprises: Propylene, a first catalyst, a second catalyst and a modifier are added into a first reactor of a double loop reactor to carry out a first polymerization reaction, and hydrogen is introduced into the first reactor to obtain a first reaction product; adding the solid phase part of the first reaction product into the second reactor in the double loop reactor to carry out a second polymerization reaction to obtain a second reaction product; Obtaining a solid phase portion of the second reaction product and performing a predetermined treatment to obtain a homopolymer polypropylene base material; The homopolypropylene base material is mixed with a β-nucleating agent and then extruded and granulated to obtain the homopolypropylene.

2. The method for preparing homopolypropylene according to claim 1, characterized in that: 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.

3. The method for preparing homopolypropylene according to claim 1, characterized in that: 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.

4. The method for preparing homopolypropylene according to any one of claims 1 to 3, characterized in that: The β-nucleating agent is an organic metal salt β-nucleating agent.

5. The method for preparing homopolypropylene according to any one of claims 1 to 3, characterized in that: The homopolymer polypropylene base material is mixed with a β-nucleating agent and then extruded and granulated to obtain the homopolymer polypropylene, specifically comprising: After the homopolymer polypropylene base material is mixed with the β-nucleating agent, an extruder is used to extrude and granulate the mixture. Wherein, the heating temperature of the extruder is 170°C~290°C.

6. The method for preparing homopolypropylene according to any one of claims 1 to 3, characterized in that: The ratio of the amount of hydrogen to the amount of propylene is 0.005% to 0.05%.

7. The method for preparing homopolypropylene according to claim 6, characterized in that: The ratio of the amount of hydrogen to the amount of propylene is 0.01% to 0.03%.

8. The method for preparing homopolypropylene according to any one of claims 1 to 3, characterized in that: The slurry concentration of the double loop reactor is 500 kg / m 3 ~580kg / m 3 .

9. The method for preparing homopolypropylene according to claim 8, characterized in that: The slurry concentration of the double loop reactor is 540 kg / m 3 ~560kg / m 3 .

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

11. The method for preparing homopolypropylene according to any one of claims 1 to 3, characterized in that: The activity of the first catalyst is ≥20000kgPP / kgCat.

12. The method for preparing homopolypropylene according to claim 11, characterized in that: The activity of the first catalyst is ≥25000kgPP / kgCat.

13. The method for preparing homopolypropylene according to any one of claims 1 to 3, characterized in that: The second catalyst is triethylaluminum.

14. The method for preparing homopolypropylene according to claim 13, characterized in that: The ratio of the amount of triethylaluminum to the amount of propylene is 0.1kg / t to 0.24kg / t.

15. The method for preparing homopolypropylene according to claim 14, characterized in that: The ratio of the amount of triethylaluminum to the amount of propylene is 0.12kg / t to 0.2kg / t.

16. The method for preparing homopolypropylene according to any one of claims 1 to 3, characterized in that: The modifier is cyclohexylmethyldimethoxysilane or dicyclopentyldimethoxysilane.

17. The method for preparing homopolypropylene according to claim 16, characterized in that: When the modifier is cyclohexylmethyldimethoxysilane, the ratio of the amount of the cyclohexylmethyldimethoxysilane to the amount of the propylene is 0.008kg / t to 0.08kg / t.

18. The method for preparing homopolypropylene according to claim 17, characterized in that: The ratio of the amount of the cyclohexylmethyldimethoxysilane to the amount of the propylene is 0.01 kg / t to 0.08 kg / t.

19. The method for preparing homopolypropylene according to any one of claims 1 to 3, characterized in that: The step of obtaining the solid phase portion of the second reaction product and performing a preset treatment to obtain a homopolymerized polypropylene base material specifically includes: The solid phase part of the obtained second reaction product is devolatilized and deactivated to obtain the homopolypropylene base material.

20. A homopolymer polypropylene, characterized in that: The homopolypropylene is prepared by the method for preparing homopolypropylene according to any one of claims 1 to 19.

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