Polypropylene and its application, method and device for continuously preparing polypropylene

Abstract

The present invention relates to the field of polymer production technology, and discloses a polypropylene and its application, as well as a method and apparatus for continuously preparing polypropylene. The method is carried out in an apparatus comprising at least two reactors connected in series, and comprises: (1) introducing propylene or a first monomer composition containing propylene into reactor I in the presence of a catalyst I for polymerization reaction to obtain a first stream; and (2) introducing the first stream and a second monomer composition into reactor II in the presence of a catalyst II for contact reaction. The method of the present invention can effectively solve the problems of poor rigidity-toughness balance and low notched impact strength of polypropylene materials. The prepared polypropylene material has a uniform phase state, excellent rigidity-toughness balance, high notched impact strength, and good cohesive properties and surface tension.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer production, in particular to polypropylene and application thereof, and a method and device for continuously preparing polypropylene. Background Art

[0002] Due to its low specific gravity, low price, stable chemical properties, and high fabric filling effect, polypropylene is often used in the preparation of waterproof membranes in existing technologies. The main method is to mix polypropylene with asphalt and add antioxidants, flame retardants, fillers and other compounding agents for blending and modification.

[0003] However, polypropylene has a poor balance of stiffness and toughness and low notched impact strength, especially at low temperatures. These significant shortcomings limit its wider application. Therefore, improving the impact properties of polypropylene has become an important topic in polypropylene modification research.

[0004] At present, blending modification and catalytic polymerization are often used to improve the impact properties of polypropylene. Among them, the blending modified polypropylene is limited by the degree of dispersion of its system, which affects the overall performance, and increases the post-processing steps, resulting in higher costs. The traditional catalytic polymerization method mostly adopts dual-reactor multi-stage polymerization and introduces ethylene copolymerization. When the alloy content of the copolymer reaches a certain level, the balance of polypropylene rigidity and toughness can be achieved. However, when the ethylene content in the polypropylene is too high, it will lead to problems such as lower operating temperature.

[0005] Therefore, developing a method for continuously preparing polypropylene to obtain polypropylene materials with excellent rigidity-toughness balance and high notched impact strength is crucial for the industrial production of polypropylene materials. Summary of the Invention

[0006] The purpose of the present invention is to solve the problems of poor rigidity-toughness balance and low notched impact strength of polypropylene in the prior art.

[0007] In order to achieve the above object, the present invention provides a method for continuously preparing polypropylene in a first aspect, wherein the method is carried out in a device comprising at least two reactors connected in series, the method comprising:

[0008] (1) In the presence of a catalyst I, propylene or a first monomer composition containing propylene is introduced into a reactor I for polymerization reaction to obtain a first stream;

[0009] (2) In the presence of catalyst II, introducing the first stream and the second monomer composition into reactor II for contact reaction;

[0010] The catalyst I and the catalyst II are the same and are Ziegler-Natta type catalysts, wherein the catalyst I contains an organoaluminum compound, an external electron donor compound, an internal electron donor compound, and a titanium-containing solid active center component;

[0011] The first monomer composition further comprises ethylene and / or alpha olefin;

[0012] The second monomer composition contains propylene, ethylene and alpha olefin;

[0013] The alpha olefin is selected from C6-C 20 At least one of the alpha olefins.

[0014] The second aspect of the present invention provides polypropylene produced by the method described in the first aspect.

[0015] The third aspect of the present invention provides the use of the polypropylene described in the second aspect in a building waterproof membrane.

[0016] A fourth aspect of the present invention provides an apparatus for continuously preparing polypropylene, comprising a reactor I and a reactor II connected in series, wherein the reactor I is provided with a catalyst I inlet, a propylene inlet or a first monomer composition inlet, and a first logistics outlet, and the reactor II is provided with a catalyst II inlet, a second monomer composition inlet, and a first logistics inlet connected to the first logistics outlet.

[0017] The method of the present invention is used to prepare polypropylene, which can effectively solve the problems of poor rigidity-toughness balance and low notched impact strength of polypropylene materials. The prepared polypropylene material has a uniform phase state and not only has the advantages of excellent rigidity-toughness balance and high notched impact strength, but also has good cohesiveness and surface tension.

[0018] In particular, the inventors also found that the present invention prepares polypropylene materials in an apparatus containing at least two reactors connected in series, which is not limited by the output of the screw extruder, effectively solving the problem of limited processing capacity of traditional methods. In addition, the preparation process is simple, no by-products are generated throughout the entire process, the cleanliness level is high, and the production cost can be effectively reduced, which is conducive to large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a polarizing microscope image of the polypropylene obtained in Example 1 of the present invention. DETAILED DESCRIPTION

[0020] The endpoints of the ranges and any values ​​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 endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0021] In the present invention, unless otherwise stated, the material level refers to the height occupied by the solid in the reactor.

[0022] In the present invention, unless otherwise stated, the pressures mentioned are gauge pressures.

[0023] As mentioned above, the first aspect of the present invention provides a method for continuously preparing polypropylene, which is carried out in a device comprising at least two reactors connected in series, and the method comprises:

[0024] (1) In the presence of a catalyst I, propylene or a first monomer composition containing propylene is introduced into a reactor I for polymerization reaction to obtain a first stream;

[0025] (2) In the presence of catalyst II, introducing the first stream and the second monomer composition into reactor II for contact reaction;

[0026] The catalyst I and the catalyst II are the same and are Ziegler-Natta type catalysts, wherein the catalyst I contains an organoaluminum compound, an external electron donor compound, an internal electron donor compound, and a titanium-containing solid active center component;

[0027] The first monomer composition further comprises ethylene and / or alpha olefin;

[0028] The second monomer composition contains propylene, ethylene and alpha olefin;

[0029] The alpha olefin is selected from C6-C 20 At least one of the alpha olefins.

[0030] Preferably, the α-olefin is selected from C8-C 12 At least one of the alpha olefins.

[0031] According to a particularly preferred embodiment, the α-olefin is selected from at least one of n-decene, 1-undecene, 1-octene, and 1-nonene. The inventors have found that in this preferred embodiment, a polypropylene material with higher notched impact strength and better stiffness-toughness balance can be obtained.

[0032] Preferably, in step (1), the method further comprises: first contacting and mixing the catalyst I with a solvent to obtain a first suspension, and then introducing the first suspension into the reactor I to participate in the polymerization reaction. The inventors have found that by adopting this preferred embodiment, a polypropylene material with better flexural modulus mechanical properties can be obtained.

[0033] The present invention has no particular limitation on the contact mixing, as long as the catalyst I can be uniformly dispersed in the solvent. Stirring, ultrasound, or vibration can be used. Preferably, in step (1), the contact mixing conditions include at least: a stirring speed of 5-50 rpm, a temperature of 10-90° C., and an average residence time of 2-200 min. More preferably, in step (1), the contact mixing conditions include at least: a stirring speed of 20-50 rpm, a temperature of 20-60° C., and an average residence time of 100-150 min.

[0034] Preferably, in step (1), the weight ratio of the catalyst I to the solvent is 0.0003-0.0008:1.

[0035] Preferably, in step (1), the solvent is a combination of white oil and vaseline in a weight ratio of 0.5-2:1.

[0036] More preferably, in step (1), in the solvent, the weight ratio of the white oil to the vaseline is 0.8-2: 1. In this preferred embodiment, a polypropylene material with better mechanical properties can be obtained.

[0037] According to a particularly preferred embodiment, in step (1), the first monomer composition is a combination of propylene and ethylene in a molar ratio of 1:0.001-0.2.

[0038] More preferably, in step (1), in the first monomer composition, the molar ratio of the propylene to the ethylene is 1:0.05-0.1.

[0039] According to another particularly preferred embodiment, in step (1), the first monomer composition is a combination of propylene and α-olefin in a molar ratio of 1:0.001-0.1.

[0040] More preferably, in step (1), in the first monomer composition, the molar ratio of the propylene to the α-olefin is 1:0.005-0.08.

[0041] According to another particularly preferred embodiment, in step (1), the first monomer composition is a combination of propylene, ethylene and α-olefin in a molar ratio of 1:0.001-0.2:0.001-0.1.

[0042] More preferably, in step (1), the first monomer composition is a combination of propylene, ethylene and α-olefin in a molar ratio of 1:0.001-0.1:0.001-0.05.

[0043] Preferably, in step (1), the method further comprises: before introducing the first suspension into the reactor I, dispersing the α-olefin in the first suspension to obtain a second suspension, and then introducing the second suspension into the reactor I.

[0044] Preferably, in step (1), the polymerization reaction conditions include: pressure of 2.0-2.4 MPa, temperature of 55-75° C., average residence time of 0.2-1.2 h, and material level of 55-87%.

[0045] More preferably, in step (1), the polymerization reaction conditions include: pressure of 2.2-2.4 MPa, temperature of 60-75°C, average residence time of 0.8-1.2 hours, and material level of 60-87%. In this preferred embodiment, a polypropylene material with better rigidity-toughness balance can be obtained.

[0046] Preferably, in step (2), the second monomer composition is a combination of propylene, ethylene and α-olefin in a molar ratio of 1:0.1-0.3:0.01-0.1.

[0047] More preferably, in step (2), the second monomer composition is a combination of propylene, ethylene and α-olefin in a molar ratio of 1:0.15-0.2:0.02-0.06.

[0048] Preferably, in step (2), the contact reaction conditions include: pressure of 2.0-2.4 MPa, temperature of 55-85° C., average residence time of 0.4-1.4 h, and material level of 55-87%.

[0049] More preferably, in step (2), the contact reaction conditions include: pressure of 2.1-2.4 MPa, temperature of 70-85°C, average residence time of 1-1.4 hours, and material level of 80-87%. In this preferred embodiment, polypropylene with better mechanical properties such as notched impact strength and flexural modulus can be obtained.

[0050] Preferably, in the catalyst I, the molar ratio of the titanium-containing solid active center component calculated as titanium element to the organoaluminum compound calculated as aluminum element is 2-4:1.

[0051] Preferably, the internal electron donor compound is a phthalate and / or ether compound.

[0052] Preferably, the organoaluminum compound is at least one selected from triethylaluminum, triisobutylaluminum, tri-n-butylaluminum and trihexylaluminum.

[0053] Preferably, the external electron donor compound is at least one selected from 1,3-dialkoxypropane, 2-ethyl-2-butyl-1,3-dimethoxypropane, cyclohexylmethyldimethoxysilane, diisobutyldimethoxysilane, and 9,9-bis(methoxymethyl)fluorene.

[0054] As mentioned above, the second aspect of the present invention provides a polypropylene produced by the method described in the first aspect.

[0055] As mentioned above, the third aspect of the present invention provides the use of the polypropylene described in the second aspect in a building waterproof membrane.

[0056] As described above, the fourth aspect of the present invention provides an apparatus for continuously preparing polypropylene, which comprises a reactor I and a reactor II connected in series, wherein the reactor I is provided with a catalyst I inlet, a propylene inlet or a first monomer composition inlet, and a first logistics outlet, and the reactor II is provided with a catalyst II inlet, a second monomer composition inlet, and a first logistics inlet connected to the first logistics outlet.

[0057] The present invention will be described in detail below by way of examples. In the following examples, unless otherwise specified, all raw materials used are commercially available.

[0058] Propylene: Purity is 99.95%, produced by Beijing Yanshan Branch of Sinopec;

[0059] Ethylene: Purity is 99.95%, produced by Beijing Yanshan Branch of Sinopec;

[0060] α-olefin: 1-undecene, 97% purity, purchased from Sigma-Aldrich Trading Company;

[0061] α-Olefins: 1-octene, analytical grade, purchased from Sigma-Aldrich Trading Company;

[0062] α-olefins: 1-nonene, purity 96%, purchased from Sigma-Aldrich Trading Company;

[0063] α-olefins: 1-butene, analytical grade, purchased from Sigma-Aldrich Trading Company;

[0064] Catalyst-1: The internal electron donor is di-n-butyl phthalate, the external electron donor compound is 2-ethyl-2-butyl-1,3-dimethoxypropane, the organoaluminum compound is triethylaluminum, and the molar ratio of the titanium-containing solid active center component calculated as titanium element to the organoaluminum compound calculated as aluminum element is 3:1;

[0065] Catalyst-2: Similar to Catalyst-1, except that the external electron donor compound is cyclohexylmethyldimethoxysilane;

[0066] Catalyst-3: Similar to Catalyst-1, except that the external electron donor compound is diisobutyldimethoxysilane.

[0067] The relevant data of the polymers in the examples and comparative examples were obtained by the following test methods:

[0068] The crystallization temperature and melting temperature were tested using the GB / T 19466.3-2004 method;

[0069] The glass transition temperature was tested using the GB / T 19466.3-2004 method;

[0070] The flexural modulus is tested according to the method specified in GB / T 9341-2008;

[0071] The notched impact strength of the charpy beam is measured according to the impact strength method of GB / T 1043.1-2008 Plastics - Determination of impact properties of charpy beam - Part 1: Non-instrumented impact test;

[0072] The contact angle between the sheet and water was tested using the method specified in ASTM D 7334-2008;

[0073] Shore hardness is measured using the method specified in GB / T 2411-2008 and the reading is taken for 15 seconds;

[0074] The load deformation temperature is tested using the GB / T 1634.2-2019 method with a load of 0.45 MPa.

[0075] In the following examples, talc was purchased from Zhengzhou Xigui Chemical Company;

[0076] Light stabilizer: 770, purchased from Qingdao Huaen Company;

[0077] Ethylene propylene rubber: 4045, purchased from Jilin Petrochemical Company.

[0078] Example 1

[0079] The catalyst used in the method of this embodiment is catalyst-1.

[0080] This embodiment provides a method for continuously preparing polypropylene, the method comprising:

[0081] (1) At a stirring speed of 20 rpm, the catalyst and the solvent are contacted and mixed in a weight ratio of 0.0003:1 (temperature of 40°C, average residence time of 120 min), so that the catalyst is uniformly dispersed in the solvent (the weight ratio of white oil and vaseline is 2:1) to obtain a first suspension, and then the first suspension is pumped into a reactor I with a pressure pump. At a temperature of 75°C and a pressure of 2.4 MPa, propylene and ethylene in a molar ratio of 1:0.08 are introduced into the reactor I for polymerization reaction. The material level is 87%, and the average polymerization residence time is 1.2 h to obtain a first stream;

[0082] (2) At a temperature of 85° C. and a pressure of 2.4 MPa, the first stream and propylene, ethylene, and 1-undecene in a molar ratio of 1:0.17:0.05 were introduced into reactor II for contact reaction. The material level was 87%, and the average polymerization residence time was 1.4 h to obtain polypropylene S1.

[0083] Example 2

[0084] The catalyst used in the method of this embodiment is Catalyst-2.

[0085] This embodiment provides a method for continuously preparing polypropylene, the method comprising:

[0086] (1) At a stirring speed of 30 rpm, the catalyst and the solvent are contacted and mixed in a weight ratio of 0.0005:1 (temperature of 50°C, average residence time of 150 min), so that the catalyst is uniformly dispersed in the solvent (the weight ratio of white oil and vaseline is 1:1) to obtain a first suspension, and then 1-undecene is dispersed in the first suspension to obtain a second suspension, and then the second suspension is pumped into a reactor I with a pressure pump, and propylene and 1-undecene in a molar ratio of 1:0.005 are introduced into the reactor I at a temperature of 70°C and a pressure of 2.2 MPa to carry out polymerization reaction, the material level is 60%, and the average polymerization residence time is 0.8 h, to obtain a first stream;

[0087] (2) Under the conditions of temperature of 80°C and pressure of 2.2 MPa, the first logistics and propylene, ethylene and 1-octene in a molar ratio of 1:0.2:0.04 were introduced into reactor II for contact reaction. The material level was 80% and the average polymerization residence time was 1 hour to obtain polypropylene S2.

[0088] Example 3

[0089] The catalyst used in the method of this embodiment is Catalyst-3.

[0090] This embodiment provides a method for continuously preparing polypropylene, the method comprising:

[0091] (1) At a stirring speed of 40 rpm, the catalyst and the solvent are contacted and mixed in a weight ratio of 0.0003:1 (temperature of 60° C., average residence time of 100 min), so that the catalyst is uniformly dispersed in the solvent (the weight ratio of white oil and vaseline is 0.8:1) to obtain a first suspension, and then the first suspension is pumped into a reactor I with a pressure pump. At a temperature of 73° C. and a pressure of 2.3 MPa, propylene, ethylene and 1-nonene in a molar ratio of 1:0.005:0.05 are introduced into the reactor I for polymerization reaction, the material level is 75%, and the average polymerization residence time is 1 h, to obtain a first stream;

[0092] (2) Under the conditions of temperature of 70°C and pressure of 2.1 MPa, the first stream and propylene, ethylene and 1-nonene in a molar ratio of 1:0.2:0.06 were introduced into reactor II for contact reaction. The material level was 85%, and the average polymerization residence time was 1.2 h to obtain polypropylene S3.

[0093] Example 4

[0094] This embodiment refers to the method of Example 3, except that in step (1), in the first monomer composition, the molar ratio of propylene, ethylene and 1-nonene is 1:0.005:0.08.

[0095] The remaining steps are the same as those in Example 3.

[0096] Polypropylene S4 was obtained.

[0097] Example 5

[0098] This example refers to the method of Example 3, except that in step (1), the polymerization reaction temperature is 55°C.

[0099] The remaining steps are the same as those in Example 3.

[0100] Polypropylene S5 was obtained.

[0101] Example 6

[0102] This example refers to the method of Example 3, except that in step (2), the contact reaction temperature is 65°C.

[0103] The remaining steps are the same as those in Example 3.

[0104] Polypropylene S6 was obtained.

[0105] Example 7

[0106] This example refers to the method of Example 3, except that in step (1), the components of catalyst I are directly introduced into reactor I;

[0107] Specifically:

[0108] (1) In the presence of catalyst I, propylene and ethylene in a molar ratio of 1:0.08 were introduced into reactor I for polymerization reaction (temperature of 75° C., pressure of 2.4 MPa), with a material level of 87% and an average polymerization residence time of 1.2 h to obtain a first stream;

[0109] (2) At a temperature of 85° C. and a pressure of 2.4 MPa, the first stream and propylene, ethylene, and 1-undecene in a molar ratio of 1:0.17:0.05 were introduced into reactor II for contact reaction. The material level was 87%, and the average polymerization residence time was 1.4 h, thereby obtaining polypropylene S7.

[0110] Example 8

[0111] This example follows the method of Example 3, except that in step (2), 1-nonene is replaced with an equimolar amount of 1-butene.

[0112] The remaining steps are the same as those in Example 3.

[0113] Polypropylene S8 was obtained.

[0114] Comparative Example 1 (using screw extrusion method)

[0115] This comparative example adopts the screw extrusion method to prepare polypropylene, and the specific steps include:

[0116] (1) Dissolve 0.1 g of initiator dicumyl peroxide, 1 g of grafting monomer pentaerythritol triacrylate, and 0.1 g of free radical activity regulator zinc dithiocarbamate in an appropriate amount of acetone to obtain a mixed solution:

[0117] (2) The resulting mixture was then evenly sprayed onto the surface of 100 g of polypropylene pellets. Antioxidant B215 was added and mixed thoroughly. The pellets were then placed in a vacuum oven at 80°C for 2 hours and then loaded into a twin-screw extruder with a screw length-to-diameter ratio of 35. The extruder section temperatures were 160°C, 170°C, 175°C, 170°C, and 165°C, respectively, and the screw speed was 70 r / min, to obtain polypropylene DS1. The properties of the resulting product are shown in Table 1.

[0118] Table 1

[0119] Example 1 Example 2 Example 3 Example 4 Example 5 Crystallization temperature / ℃ 115 117 110 108 119 Melting temperature / ℃ 154 158 145 148 152 Glass transition temperature / ℃ -39.6 -35.2 -32.0 -34.1 -28.9 Flexural modulus / MPa 533 480 576 512 650 <![CDATA[Notched impact strength of simply supported beam / kJ / m 2 , -20 °C]]> C7.2 C8.5 C8.7 C6.3 C7.2 Contact angle between sheet and water / ° 53 51 59 55 60 Shore hardness 56 55 53 50 60 Deformation temperature under load / ℃ 533 480 576 512 650

[0120] Table 1 (Continued 1)

[0121] Example 6 Example 7 Example 8 Comparative Example 1 Crystallization temperature / ℃ 114 118 121 128 Melting temperature / ℃ 153 158 161 167 Glass transition temperature / ℃ -23.1 -20.3 -25.6 -30.2 Flexural modulus / MPa 542 484 513 1290 <![CDATA[Notched impact strength of simply supported beam / kJ / m 2 , -20 °C]]> C6.3 C6.2 C5.2 C6.2 Contact angle between sheet and water / ° 76 86 92 104 Shore hardness 62 64 65 87 Deformation temperature under load / ℃ 63 67 66 85

[0122] From the results in Table 1, it can be seen that the polypropylene prepared by the method of the present invention has higher notched impact strength and flexural modulus, and the polypropylene prepared by the present invention has good hardness and load deflection temperature.

[0123] The present invention provides a polarizing microscope image of the polypropylene product obtained in Example 1, see Figure 1 .

[0124] from Figure 1 It can be seen that the polypropylene prepared by the present invention has fine crystals inside, and this structure is helpful to achieve a balance between rigidity and toughness.

[0125] Test Case

[0126] The polypropylene products prepared in the examples and comparative examples were used to prepare waterproof membranes, and the prepared waterproof membranes were subjected to performance tests, including tensile strength, elongation at break and other properties. The tensile strength retention rate and elongation at break retention rate after aging treatment (heat aging test chamber, temperature of 115±2°C, aging time of 224 days) were calculated. The specific test results are shown in Table 2.

[0127] Among them, the preparation method of waterproof membrane-1 is as follows: at 180°C, 75g of polypropylene prepared in the embodiment, 25g of talcum powder and 7g of light stabilizer are introduced into the screw (extrusion temperature is 180°C, rotation speed is 65rpm) for stable extrusion, and enter the calendering roller (temperature is 60°C, pressure is 5MPa, and winding speed is 2m / min). After cooling to room temperature, it is cut to obtain an anti-seepage sheet with a thickness of 2mm.

[0128] The preparation method of waterproof membrane-2 is similar to that of waterproof membrane-1, except that EPDM is added to the formula. Specifically:

[0129] 30 g of polypropylene prepared in Comparative Example 1, 45 g of ethylene propylene rubber, 25 g of talc and 7 g of light stabilizer were introduced into a screw (extrusion temperature of 180 ° C, rotation speed of 65 rpm) for stable extrusion, and entered into a calendering roller (temperature of 60 ° C, pressure of 5 MPa, and curling speed of 2 m / min). After cooling to room temperature, it was cut to obtain an anti-seepage sheet with a thickness of 2 mm.

[0130] The tensile strength and elongation at break are tested according to the method specified in GB / T328.9-2007;

[0131] The calculation formula of tensile strength retention rate is: (tensile strength after aging treatment / tensile strength before aging treatment) × 100%;

[0132] The calculation formula for the elongation at break retention rate is: (elongation at break after aging treatment / elongation at break before aging treatment)×100%.

[0133] Table 2

[0134]

[0135] From the results in Table 2, it can be seen that the waterproof roll formed by the polypropylene prepared by the method of the present invention requires fewer feeding times and does not require blending of two basic materials. While maintaining comparable mechanical properties, it has more excellent anti-aging performance.

[0136] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for continuously preparing polypropylene, characterized in that: The method includes: (1) first contacting and mixing the catalyst I with a solvent to obtain a first suspension, and then introducing propylene or a first monomer composition containing propylene and the first suspension into a reactor I in the presence of the catalyst I to carry out a polymerization reaction to obtain a first stream; the solvent is a combination of white oil and vaseline in a weight ratio of 0.5-2:1; (2) In the presence of catalyst II, introducing the first stream and the second monomer composition into reactor II for contact reaction; The catalyst I and the catalyst II are the same and are Ziegler-Natta type catalysts, wherein the catalyst I contains an organoaluminum compound, an external electron donor compound, an internal electron donor compound, and a titanium-containing solid active center component; The first monomer composition further comprises ethylene and / or alpha olefin; The second monomer composition contains propylene, ethylene and alpha olefin; The alpha olefin is selected from C8-C 12 At least one of the alpha olefins.

2. The method according to claim 1, wherein The alpha olefin is at least one selected from n-decene, 1-undecene, 1-octene, and 1-nonene.

3. The method according to claim 1 or 2, wherein: In step (1), the weight ratio of the catalyst I to the solvent is 0.0003-0.0008:

1.

4. The method according to claim 1 or 2, wherein: In the solvent, the weight ratio of the white oil to the vaseline is 0.8-2:

1.

5. The method according to claim 1 or 2, wherein: In step (1), the first monomer composition is a combination of propylene and ethylene in a molar ratio of 1:0.001-0.

2.

6. The method according to claim 5, wherein: In step (1), in the first monomer composition, the molar ratio of the propylene to the ethylene is 1:0.05-0.

1.

7. The method according to claim 1 or 2, wherein: In step (1), the first monomer composition is a combination of propylene and α-olefin in a molar ratio of 1:0.001-0.

1.

8. The method according to claim 7, wherein: In step (1), in the first monomer composition, the molar ratio of the propylene to the α-olefin is 1:0.005-0.

08.

9. The method according to claim 1 or 2, wherein: In step (1), the first monomer composition is a combination of propylene, ethylene and α-olefin in a molar ratio of 1:0.001-0.2:0.001-0.

1.

10. The method according to claim 9, wherein: In step (1), the first monomer composition is a combination of propylene, ethylene and α-olefin in a molar ratio of 1:0.001-0.1:0.001-0.

05.

11. The method according to claim 1 or 2, wherein: In step (1), the method further includes: before introducing the first suspension into the reactor I, dispersing the α-olefin in the first suspension to obtain a second suspension, and then introducing the second suspension into the reactor I.

12. The method according to claim 1 or 2, wherein: In step (1), the polymerization reaction conditions include: pressure of 2.0-2.4 MPa, temperature of 55-75° C., average residence time of 0.2-1.2 h, and material level of 55-87%.

13. The method according to claim 12, wherein: In step (1), the polymerization reaction conditions include: pressure of 2.2-2.4 MPa, temperature of 60-75° C., average residence time of 0.8-1.2 h, and material level of 60-87%.

14. The method according to claim 1 or 2, wherein: In step (2), the second monomer composition is a combination of propylene, ethylene and α-olefin in a molar ratio of 1:0.1-0.3:0.01-0.

1.

15. The method according to claim 14, wherein In step (2), the second monomer composition is a combination of propylene, ethylene and α-olefin in a molar ratio of 1:0.15-0.2:0.02-0.

06.

16. The method according to claim 1 or 2, wherein: In step (2), the contact reaction conditions include: pressure of 2.0-2.4 MPa, temperature of 55-85° C., average residence time of 0.4-1.4 h, and material level of 55-87%.

17. The method according to claim 16, wherein In step (2), the contact reaction conditions include: pressure of 2.1-2.4 MPa, temperature of 70-85° C., average residence time of 1-1.4 h, and material level of 80-87%.

18. The method according to claim 1 or 2, wherein: In the catalyst I, the molar ratio of the titanium-containing solid active center component calculated as titanium element to the organoaluminum compound calculated as aluminum element is 2-4:

1.

19. The method according to claim 1 or 2, wherein: The internal electron donor compound is a phthalate ester and / or ether compound.

20. The method according to claim 1 or 2, wherein: The organoaluminum compound is at least one selected from triethylaluminum, triisobutylaluminum, tri-n-butylaluminum and trihexylaluminum.

21. The method according to claim 1 or 2, wherein The external electron donor compound is selected from at least one of 1,3-dialkoxypropane, 2-ethyl-2-butyl-1,3-dimethoxypropane, cyclohexylmethyldimethoxysilane, diisobutyldimethoxysilane, and 9,9-bis(methoxymethyl)fluorene.

22. Polypropylene obtained by the process according to any one of claims 1 to 21.

23. Use of the polypropylene according to claim 22 in building waterproof membranes.

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