A monophosphine halide, its preparation method, and a method for preparing polypropylene resin.

Abstract

This invention relates to the field of organic synthesis technology, and in particular to a monophosphine halide and its preparation method, as well as a method for preparing polypropylene resin. The monophosphine halide provided by this invention has the following structure: where n is an integer between 1 and 4, and X is selected from any one of F, Cl, Br, and I. The monophosphine halide of this invention has a specific structure, and when used in the polymerization reaction of propylene, the monophosphine halide polymerizes with propylene under the action of a catalyst to obtain a high melt strength polypropylene resin with a long-chain branched structure, thereby achieving a low-cost, high-performance reactor method for preparing polypropylene resin.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, and in particular to a monophosphine halide and its preparation method and a method for preparing polypropylene resin. Background Technology

[0002] Phosphine ligands are an important class of catalyst ligands, and with the continuous development of their structure and types, they play a crucial role in the field of catalysis. In the field of chiral catalysis, since Professor Knowles' DIPAMP ligand and Professor Noyori's BINAP ligand, various skeletal bisphosphine ligands have received widespread attention and research. Professor Zhang Xumu has made outstanding contributions in this area, developing a series of highly efficient phosphine chiral and skeletal chiral bidentate phosphine ligands, and establishing a toolbox of asymmetric hydrogenation chiral ligands. Furthermore, various phosphine ligands, after complexation with metals, exhibit excellent catalytic activity and selectivity in olefin hydroformylation, carbonyl esterification, alkoxy carbonylation, hydrocarboxylation, and hydrocyanation reactions.

[0003] High melt strength polypropylene (HMSPP) is a novel polypropylene material developed to address the shortcomings of ordinary polypropylene. Due to its low crystallinity and melting temperature, as well as high melt strength, it solves the problems of edge curling and shrinkage during high-speed extrusion coating, cell collapse during extrusion foaming, and melt sagging and localized thinning during thermoforming of ordinary linear polypropylene. Because it still exhibits tensile strain hardening in the molten state and has a wide processing temperature range, it can be used in thermoforming, extrusion foaming, coating, blow molding, and other applications, further expanding its applications in the automotive, home appliance, food packaging, and building materials industries.

[0004] Currently, there are two main approaches to preparing high melt strength polypropylene: post-reactor modification and reactor method. The post-reactor modification method utilizes unstable tertiary carbon free radicals, controlling reaction conditions (free radical decomposition rate, reaction temperature, monomer concentration, etc.) to induce reactions with other reactive free radical chains, thereby forming a long-chain branched structure. This method relies on free radical reactions, inevitably leading to polypropylene degradation and cross-linking reactions, resulting in poor control over the polymer structure and high production costs. The reactor method, as the name suggests, directly forms long-chain branched polypropylene by controlling the polymerization reaction in a reactor. This method is characterized by its simple operation, controllable product structure, and stable performance. However, the reactor method has stringent requirements for catalysts and polymerization conditions, and methods suitable for preparing long-chain branched polyethylene often fail when preparing long-chain branched polypropylene.

[0005] In view of this, this invention is hereby proposed. Summary of the Invention

[0006] The first objective of this invention is to provide a monophosphine halide compound that can be used as a polymerization monomer to participate in the polymerization reaction of propylene to obtain a high melt strength polypropylene resin.

[0007] The second objective of this invention is to provide a method for preparing monophosphine halide compounds, which has a high synthesis yield, few post-processing steps, and is suitable for industrial production.

[0008] A third objective of this invention is to provide a method for preparing polypropylene, wherein a monophosphine halide undergoes a polymerization reaction with propylene under the action of a catalyst to obtain a polypropylene resin with high melt strength.

[0009] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0010] In a first aspect, the present invention provides a monophosphine halide having the following structure:

[0011] In the formula, n is an integer between 1 and 4, and X is selected from any one of F, Cl, Br and I.

[0012] Furthermore, X is selected from Cl or Br.

[0013] Secondly, the present invention also provides a method for preparing monophosphine halides, comprising the following steps:

[0014] S1. Reaction of metallic magnesium, α-olefin haloalkane, and iodine in an organic solvent yields a Grignard reagent; wherein the α-olefin haloalkane is selected from at least one of 4-bromo-1-butene, 5-bromo-1-pentene, 6-bromo-1-hexene, and 7-bromo-1-heptene.

[0015] S2. React the trihalomethane trihalide and the Grignard reagent in an organic solvent to obtain a reaction solution; remove the organic solvent from the reaction solution to obtain a solid; wash the solid with an alkane, and then concentrate and distill the washed alkane to obtain the monophosphine halide; wherein the trihalomethane trihalide is selected from at least one of phosphine trichloride, phosphine tribromide, phosphine trifluoride and phosphine triiodide.

[0016] Furthermore, the trihalomethane is phosphine trichloride and / or phosphine tribromide.

[0017] Further, the molar ratio of the α-olefin haloalkane, the metallic magnesium, and the trihalomethane is 1:(1.05-1.3):(0.85-1.1).

[0018] Further, in step S1, the reaction includes: reflux reaction for 4 to 6 hours.

[0019] Further, in step S2, the reaction includes reacting at 20–25°C for 8–12 hours.

[0020] Thirdly, the present invention also provides a method for preparing polypropylene resin, comprising the following steps:

[0021] The monophosphine halide and propylene, as described above, undergo a polymerization reaction in the presence of a catalyst to obtain the polypropylene resin.

[0022] Furthermore, the mass ratio of the monophosphine halide to the propylene is (0.001–20):100.

[0023] Furthermore, the catalyst includes at least one of Ziegler-Natta catalyst, metallocene catalyst, and non-metallocene catalyst.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] The monophosphine halide provided by this invention has a specific structure. When used in the polymerization reaction of propylene, the monophosphine halide copolymerizes with propylene under the action of a catalyst to obtain a high melt strength polypropylene resin with a long-chain branched structure. A series of high melt strength random copolymer polypropylenes with controllable melt strength and controllable mechanical properties can be obtained according to actual application needs, thereby realizing the reactor method preparation of low-cost, high-performance, and diverse random copolymer polypropylenes. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0027] The following provides a detailed description of a monophosphine halide, its preparation method, and the preparation method of polypropylene resin according to the present invention.

[0028] In some embodiments of the present invention, a monophosphine halide is provided having the following structure:

[0029] In the formula, n is an integer between 1 and 4, and X is selected from any one of F, Cl, Br and I.

[0030] The monophosphine halide provided by this invention has a specific structure. The carbon-phosphine bond of the monophosphine halide has a relatively long bond length and a large bond angle. Its bonding properties are between those of covalent and ionic bonds, exhibiting strong reactivity and being more prone to substitution reactions. In propylene polymerization, it mainly participates in the reaction as a monomer. Under the action of a catalyst, the monophosphine halide polymerizes with propylene to obtain polypropylene molecules with a slightly branched structure, thus yielding polypropylene resin with high melt strength. The synthesis cost is low, it is easy to scale up industrially, and its activity towards the original polymerization system is relatively low.

[0031] In some embodiments of the present invention, when n=1, the monophosphine halide is 3-butenyl diphosphine halide; when n=2, the monophosphine halide is 4-pentenyl diphosphine halide; when n=3, the monophosphine halide is 5-hexenyl diphosphine halide; and when n=4, the monophosphine halide is 6-heptenyl diphosphine halide.

[0032] In some embodiments of the present invention, X is selected from Cl or Br; preferably, X is Cl.

[0033] In some embodiments of the present invention, the monophosphine halide is at least one of the following compounds;

[0034] 3-Butenylphosphine dichloride, chemical structural formula is

[0035] 4-Pentenylphosphine dichloride, with the following chemical structural formula:

[0036] 5-Hexenylphosphine dichloride, with the chemical structural formula as follows:

[0037] 6-Heptenylphosphine dichloride, chemical structural formula is

[0038] In some embodiments of the present invention, a method for preparing the above-mentioned monophosphine halide is also provided, comprising the following steps:

[0039] S1. Reaction of metallic magnesium, α-olefin haloalkanes and iodine in an organic solvent to obtain a Grignard reagent; wherein the α-olefin haloalkanes are selected from at least one of 4-bromo-1-butene, 5-bromo-1-pentene, 6-bromo-1-hexene and 7-bromo-1-heptene.

[0040] S2. React phosphine trihalide and Grignard reagent in an organic solvent to obtain a reaction solution; remove the organic solvent from the reaction solution to obtain a solid; wash the solid with alkane, and then concentrate and distill the washed alkane to obtain a monophosphine halide; the phosphine trihalide is selected from at least one of phosphine trichloride, phosphine tribromide, phosphine trifluoride and phosphine triiodide.

[0041] The method for preparing monophosphine halides of the present invention has high synthesis yield, few post-processing steps, and is suitable for industrial production.

[0042] In some embodiments of the present invention, the trihalomethane is phosphine trichloride and / or phosphine tribromide.

[0043] In some embodiments of the present invention, the molar ratio of α-olefin halocarbon, metallic magnesium, and phosphine trihalide is 1:(1.05 to 1.3):(0.85 to 1.1); typically, but not limitingly, for example, the molar ratio of α-olefin halocarbon, metallic magnesium, and phosphine trihalide may be a range of 1:1.05:0.85, 1:1.05:0.95, 1:1.05:1.05, 1:1.1:0.9, 1:1.1:1.1, 1:1.3:1.1, or any combination thereof.

[0044] In some embodiments of the present invention, step S1 is performed under a protective atmosphere; preferably, the protective atmosphere includes at least one of nitrogen and an inert gas.

[0045] In some embodiments of the present invention, in step S1, the organic solvent includes at least one of diethyl ether, butyl ether, tetrahydrofuran (THF), n-hexane, and heptane.

[0046] In some embodiments of the present invention, step S1 includes a reflux reaction for 4 to 6 hours; typically, but not limitingly, the reaction time can be a range of 4 hours, 5 hours, 6 hours, or any combination thereof.

[0047] In some specific embodiments of the present invention, in step S1, under a protective atmosphere, metallic magnesium, organic solvent and a small amount of α-olefin haloalkane are mixed and heated to 30-50°C. Iodine is added to initiate the reaction. When the reaction solution bubbles and the color of the solution fades, the α-olefin haloalkane is slowly added dropwise. After the addition is completed, the reaction is refluxed for 4-6 hours to obtain the Grignard reagent.

[0048] In some embodiments of the present invention, step S2 is performed under a protective atmosphere; preferably, the protective atmosphere includes at least one of nitrogen and an inert gas.

[0049] In some embodiments of the present invention, step S2 includes reacting at 20–25°C for 8–12 hours; typically, but not limitingly, for example, the reaction time can be a range of 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, or any combination thereof.

[0050] In some embodiments of the present invention, in step S2, the organic solvent includes at least one selected from diethyl ether, butyl ether, tetrahydrofuran (THF), n-hexane, and heptane.

[0051] In some embodiments of the present invention, in step S2, the alkane includes n-hexane and / or heptane.

[0052] In some specific embodiments of the present invention, in step S2, under a protective atmosphere, phosphine trihalide, Grignard reagent and organic solvent are mixed and reacted at 20-25°C for 8-12 hours to obtain a reaction solution; the organic solvent in the reaction solution is removed under vacuum to obtain a solid, the solid is washed with alkanes 3-5 times, the washed alkanes are combined, concentrated and distilled under reduced pressure to obtain a colorless liquid, which is a monophosphine halide.

[0053] In some embodiments of the present invention, a method for preparing polypropylene resin is also provided, comprising the following steps:

[0054] The above-mentioned monophosphine halide and propylene undergo a polymerization reaction in the presence of a catalyst to obtain polypropylene resin.

[0055] In propylene polymerization, monophosphine halides mainly participate in the reaction as polymerizing monomers. Under the action of appropriate catalysts, they undergo copolymerization with propylene to obtain high melt strength polypropylene resin with long-chain branched structure characteristics. A series of high melt strength random copolymer polypropylenes with controllable melt strength and controllable mechanical properties can be obtained according to actual application needs, thereby realizing the reactor method preparation of low-cost, high-performance, and diverse random copolymer polypropylene.

[0056] In some embodiments of the present invention, the mass ratio of monophosphine halide to propylene is (0.001 to 20):100; typically, but not limitingly, for example, the mass ratio of monophosphine halide to propylene can be 0.001:100, 1:100, 5:100, 10:100, 15:100, 20:100, or any combination thereof; preferably, the mass ratio of monophosphine halide to propylene is (0.001 to 0.5):100; this can further improve the melt strength and mechanical strength of the obtained polypropylene resin.

[0057] In some embodiments of the present invention, a monophosphine halide is added to the polymerization reaction system before and / or during the propylene polymerization reaction; the addition can be selected before or during the reaction depending on the actual operating conditions of the apparatus.

[0058] In some embodiments of the present invention, the catalyst includes, but is not limited to, at least one of Ziegler-Natta catalyst (ZN catalyst), metallocene catalyst, and non-metallocene catalyst; preferably, the catalyst includes a MgCl2 supported catalytic system and / or a VOCl3-AlEt2Cl catalytic system; specifically, the MgCl2 supported catalytic system includes at least one of MgCl2, TiCl4, alkylaluminum, alkoxyaluminum, internal electron donor, and external electron donor.

[0059] The present invention does not strictly limit the type of catalyst, and can use any existing catalyst that can be used to catalyze the polymerization reaction of olefin monomers.

[0060] In some embodiments of the present invention, the polymerization reaction temperature is 50–60°C.

[0061] In some embodiments of the present invention, the polymerization reaction time is 0.1 to 5 hours; preferably, the polymerization reaction time is 0.5 to 2 hours.

[0062] In some specific embodiments of the present invention, a co-catalyst alkylaluminum, a Zn catalyst, an external electron donor, propylene, and a monophosphine halide compound are reacted to obtain a polypropylene resin.

[0063] The catalyst includes a co-catalyst (alkylaluminum), a main catalyst (ZN catalyst), and an external electron donor; preferably, the mass ratio of propylene to the main catalyst is 5000 to 100000, and the molar ratio of Ti element in the co-catalyst to the main catalyst is 10 to 10000:1.

[0064] Example 1

[0065] The monophosphine halide compound provided in this embodiment is 3-butenylphosphine dichloride, with the chemical structural formula as follows:

[0066]

[0067] The preparation method of 3-butenylphosphine dichloride includes the following steps:

[0068] S1. Vacuum and nitrogen gas were repeatedly applied to a three-necked flask equipped with a reflux condenser and a constant pressure dropping funnel three times. Under nitrogen protection, 3.6 g (0.15 mol) of magnesium powder, 3 drops (0.1 mL) of 4-bromo-1-butene, and 120 mL of anhydrous THF were added sequentially. The mixture was heated to 40 °C, stirred, and 1 grain (5-8 mg) of iodine was added. When the reaction solution bubbled and the color of the solution faded, 16.2 g (0.12 mol) of 4-bromo-1-butene was slowly added dropwise. After the addition was completed, the mixture was refluxed for 6 h. The residual solid was removed by filtration under nitrogen protection to obtain a THF solution of 3-butenyl magnesium bromide.

[0069] S2. Under a nitrogen atmosphere, 100 mL of anhydrous THF and 17.85 g (0.13 mol) of phosphine trichloride were added to a Shrek flask and stirred. Then, the above-mentioned 3-butenyl magnesium bromide THF solution was slowly added dropwise to the reaction system (using a syringe). After the addition was complete, the reaction was stirred at 25 °C for 12 h to obtain a grayish-white reaction solution. The THF in the grayish-white reaction solution was removed under vacuum to obtain a white solid. The white solid was washed three times with n-hexane, the n-hexane residues were combined, filtered, and the filtrate was concentrated under vacuum. The concentrate was then distilled under reduced pressure, and the colorless distillate was collected (oil bath temperature 116 °C) to obtain 11.6 g of colorless liquid, which is 3-butenyl dichloride (hex-DCP), with a yield of 61%.

[0070] The mass spectrometry results of the 3-butenylphosphine dichloride prepared in this example are as follows:

[0071] 1HNMR (C6D6, 400MHz, 298K), δ, ppm: 5.89-5.5.92 (m, 1H, = CH), 4.98-5.02 (q, 2H, CH2), 1. 42-1.60 (m, 2H, CH2), 1.07-1.18 (t, 2H, PCH2); 31PNMR (C6D6, 400MHz, 298K), δ, ppm: 35.5.

[0072] Example 2

[0073] The monophosphine halide compound provided in this embodiment is 5-hexenylphosphine dichloride, with the chemical structural formula as follows:

[0074]

[0075] The preparation method of 5-hexenylphosphine dichloride includes the following steps:

[0076] S1. Vacuum and nitrogen gas were repeatedly applied to a three-necked flask equipped with a reflux condenser and a constant pressure dropping funnel three times. Under nitrogen protection, 3.6 g (0.15 mol) of magnesium powder, 3 drops (0.1 mL) of 6-bromo-1-hexene, and 120 mL of anhydrous THF were added sequentially. The mixture was heated to 40 °C, stirred, and 1 grain (5-8 mg) of iodine was added. When the reaction solution bubbled and the color of the solution faded, 21.5 g (0.12 mol) of 6-bromo-1-hexene was slowly added dropwise. After the addition was completed, the mixture was refluxed for 6 h. The residual solid was removed by filtration under nitrogen protection to obtain a THF solution of 5-hexenyl magnesium bromide.

[0077] S2. Under a nitrogen atmosphere, 100 mL of anhydrous THF and 17.85 g (0.13 mol) of phosphine trichloride were added to a Shrek flask and stirred. Then, the above-mentioned 5-hexenyl magnesium bromide THF solution was slowly added dropwise to the reaction system (using a syringe). After the addition was complete, the reaction was stirred at 25 °C for 12 h to obtain a grayish-white reaction solution. The THF in the grayish-white reaction solution was removed under vacuum to obtain a white solid. The white solid was washed three times with n-hexane, the n-hexane residues were combined, filtered, and the filtrate was concentrated under vacuum. The concentrate was then distilled under reduced pressure, and the colorless distillate was collected (oil bath temperature 116 °C) to obtain 14.43 g of colorless liquid, which is 5-hexenyl dichloride (hex-DCP), with a yield of 65%.

[0078] The mass spectrometry results of the 5-hexenylphosphine dichloride prepared in this example are as follows:

[0079] 1HNMR (C6D6, 400MHz, 298K), δ, ppm: 5.75-5.85 (m, 1H, = CH), 4.94-5.04 (q, 2H, = CH2), 2.04-2.15 (q, 2H, C H2=CHCH2), 1.42-1.60 (m, 4H, CH2), 1.07-1.18 (t, 2H, PCH2); 31PNMR (C6D6, 400MHz, 298K), δ, ppm: 37.5.

[0080] Example 3

[0081] The monophosphine halide compound provided in this embodiment is 4-pentenylphosphine dichloride, with the chemical structural formula as follows:

[0082]

[0083] The preparation method of 4-pentenylphosphine dichloride is the same as in Example 1, except that in step S1, 0.12 mol of 4-bromo-1-butene is replaced with 0.12 mol of 5-bromo-1-pentene.

[0084] Example 4

[0085] The monophosphine halide compound provided in this embodiment is 6-heptenylphosphine dichloride, with the chemical structural formula as follows:

[0086]

[0087] The preparation method of 6-heptenylphosphine dichloride is the same as in Example 1, except that in step S1, 0.12 mol of 4-bromo-1-butene is replaced with 0.12 mol of 7-bromo-1-heptene.

[0088] Example 5

[0089] The monophosphine halide compound provided in this embodiment is 3-butenylphosphine dibromide, with the chemical structural formula as follows:

[0090]

[0091] The preparation method of 3-butenylphosphine dibromide is the same as in Example 1, except that in step S2, 0.13 mol of phosphine trichloride is replaced with 0.13 mol of phosphine tribromide.

[0092] Example 6

[0093] The method for preparing polypropylene resin provided in this embodiment includes the following steps:

[0094] After heating the polymerization reactor to 60°C and evacuating it for 60 min, the reactor was replaced three times with propylene. At 50°C, 3.0 mL of triisobutylaluminum (1 mol / L), 0.1 mL of external electron donor CMMS, and 20 μmol of 3-butenylphosphine dichloride (0.1 mol / L, 200 μL) from Example 1 were added to the polymerization reactor using 200 mL of anhydrous n-hexane. After stirring for 3 min, 11 mg of Zn catalyst was added to the polymerization reactor using 200 mL of anhydrous n-hexane. Propylene was then introduced, and the pressure inside the polymerization reactor was maintained at 5 bar. The polymerization reaction was carried out at 50–60°C for 2 h. After the polymerization reaction was completed, the temperature of the polymerization reactor was lowered to room temperature, the residual propylene was vented, an acid-alcohol solution was added, the mixture was filtered, and washed three times with ethanol and water, respectively. The mixture was then vacuum dried at 60°C for 20 h to obtain 208 g of white powder, which is the polypropylene resin. The polypropylene resin contains branched or cross-linked structures, and the gel content is 3% by weight.

[0095] Example 7

[0096] The method for preparing polypropylene resin provided in this embodiment includes the following steps:

[0097] After heating the polymerization reactor to 60°C and evacuating it for 60 min, the mixture was replaced three times with propylene. At 50°C, 3.0 mL of triisobutylaluminum (1 mol / L), 0.1 mL of external electron donor CMMS, and 20 μmol of 5-hexenylphosphine dichloride (0.1 mol / L, 200 μL) from Example 2 were added to the polymerization reactor using 200 mL of anhydrous n-hexane. After stirring for 3 min, 11 mg of Zn catalyst was added to the polymerization reactor using 200 mL of anhydrous n-hexane. Propylene was then introduced, and the pressure inside the polymerization reactor was maintained at 5 bar. The polymerization reaction was carried out at 50–60°C for 2 h. After the polymerization reaction was completed, the temperature of the reactor was lowered to room temperature, the residual propylene was vented, an acid-alcohol solution was added, the mixture was filtered, and washed three times with ethanol and water respectively. The mixture was then vacuum dried at 60°C for 20 h. 198 g of white powder was obtained, which was the polypropylene resin. The polypropylene resin contained branched or cross-linked structures, and the gel content was 5% by weight.

[0098] Comparative Example 1

[0099] The preparation method of the polypropylene resin provided in this comparative example is the same as that in Example 6, except that 3-butenylphosphine dichloride of Example 1 was not added, and a reference homopolymer polypropylene resin was obtained.

[0100] Comparative Example 2

[0101] The preparation method of the polypropylene resin provided in this comparative example is the same as that in Example 7, except that 3-butenylphosphine dichloride of Example 2 was not added, and a reference homopolymer polypropylene resin was obtained.

[0102] Test case

[0103] The properties of the polypropylene resins prepared in Examples 6, 7, Comparative Example 1, and Comparative Example 2 were tested, and the results are shown in Table 1.

[0104] Gel content: The polypropylene resin was dried to constant weight in a vacuum drying oven at 50℃, weighed, and recorded as W1. Then, the dried polypropylene resin was dissolved in xylene and shaken at 135℃ to fully dissolve it. The solution was filtered through a 200-mesh stainless steel mesh, and the undissolved polymer remaining on the stainless steel mesh was collected. The undissolved polymer on the stainless steel mesh was dried in a vacuum drying oven at 100℃ for 4 hours, weighed, and recorded as W2. The formula for calculating the gel content of polypropylene resin is as follows: Gel content (wt%) = (W2 / W1) × 100 (wt%).

[0105] Melt strength: The experimental setup for determining melt strength consists of a single-screw extruder equipped with a capillary tube and a Gottfert-Rheotens melt strength tester. First, the polypropylene resin melt to be tested is extruded from the extruder die. Then, the resulting extruded melt bundle is pulled by two rollers moving in opposite directions on a balance beam. The force acting on the melt bundle during stretching is a function of roller speed and time. The rollers rotate at a uniform acceleration until the melt bundle breaks; the force acting on the melt bundle at break is defined as the melt strength.

[0106] Mechanical properties: Impact strength was determined according to the method specified in ASTM D256A.

[0107] Table 1

[0108] Gel content (wt%) Melt strength (CN) <![CDATA[Impact strength (kJ / m 2 )]]> Example 6 3 65 13.8 Example 7 5 78 15.1 Comparative Example 1 / 5.8 1.9 Comparative Example 2 / 6.0 2.1

[0109] As can be seen from Table 1, the polypropylene resin provided by the present invention has high melt strength and impact strength; when the monophosphine halide of the present invention is added to the propylene polymerization process, the melt properties (melt strength) and impact toughness (impact strength) of the resulting polypropylene resin are greatly improved; the determination of gel content indicates that a branched or cross-linked structure is formed in the molecular chain of the polypropylene resin.

[0110] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing polypropylene resin, characterized in that, Includes the following steps: Monophosphine halide and propylene undergo a polymerization reaction in the presence of a catalyst to obtain the polypropylene resin. The monophosphine halide has the following structure: In the formula, n is an integer between 1 and 4, and X is selected from Cl or Br.

2. The method for preparing polypropylene resin according to claim 1, characterized in that, The method for preparing the monophosphine halide includes the following steps: S1. Reaction of metallic magnesium, α-olefin haloalkane, and iodine in an organic solvent yields a Grignard reagent; wherein the α-olefin haloalkane is selected from at least one of 4-bromo-1-butene, 5-bromo-1-pentene, 6-bromo-1-hexene, and 7-bromo-1-heptene. S2. The trihalomethane and the Grignard reagent are reacted in an organic solvent to obtain a reaction solution; the organic solvent in the reaction solution is removed to obtain a solid; the solid is washed with alkane, and the washed alkane is concentrated and distilled in sequence to obtain the monophosphine halide; wherein the trihalomethane is selected from phosphine trichloride or phosphine tribromide.

3. The method for preparing polypropylene resin according to claim 2, characterized in that, The molar ratio of the α-olefin halocarbon, the metallic magnesium, and the trihalomethane is 1:(1.05~1.3):(0.85~1.1).

4. The method for preparing polypropylene resin according to claim 2, characterized in that, In step S1, the reaction includes: reflux reaction for 4-6 hours.

5. The method for preparing polypropylene resin according to claim 2, characterized in that, In step S2, the reaction includes reacting at 20~25℃ for 8~12 hours.

6. The method for preparing polypropylene resin according to claim 1, characterized in that, The mass ratio of the monophosphine halide to the propylene is (0.001~20):

100.

7. The method for preparing polypropylene resin according to claim 1, characterized in that, The catalyst includes at least one of a metallocene catalyst and a non-metallocene catalyst.

8. The method for preparing polypropylene resin according to claim 7, characterized in that, The non-metallocene catalyst includes a Ziegler-Natta catalyst.

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