Monophosphine halide, preparation method thereof and preparation method of polypropylene resin

Abstract

The invention relates to the technical field of organic synthesis, in particular to a monophosphine halide, a preparation method thereof and a preparation method of polypropylene resin. The monophosphine halide provided by the invention has a structure shown in the following formula: # imgabs0 #, n is an integer between 1 and 4, and X is any one selected from F, Cl, Br and I. The monophosphine halide provided by the invention has a specific structure and is used in a propylene polymerization reaction, the monophosphine halide and propylene are subjected to a polymerization reaction under the action of a catalyst, and high-melt-strength polypropylene resin with a long-chain branched structure can be obtained, so that low-cost and high-performance polypropylene resin can be prepared by a reactor method.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, in particular to a monophosphine halide and a preparation method thereof and a preparation method of a polypropylene resin. Background Art

[0002] Phosphine ligands are an important class of catalyst ligands. With the continuous development of the structure and types of phosphine ligands, they play an extremely important role in the field of catalysis. In the field of chiral catalysis, since the reports of Professor Knowles' DIPAMP ligand and Professor Noyori's BINAP ligand, various skeleton-based bisphosphine ligands have received extensive attention and research. Professor Zhang Xumu has made outstanding contributions in this regard, developing a series of highly efficient bidentate phosphine ligands with phosphine chirality and skeleton chirality, and establishing an asymmetric hydrogenation chiral ligand toolbox. In addition, various types of phosphine ligands have shown excellent catalytic activity and selectivity in olefin hydroformylation, carbonyl esterification, alkoxycarbonylation, hydrocarboxylation and hydrocyanation reactions after complexing with metals.

[0003] High melt strength polypropylene (HMSPP) is a new type of polypropylene material developed to address the shortcomings of ordinary polypropylene. Due to its low crystallinity and melting temperature, high melt strength and other characteristics, it solves the problems of edge curling and shrinkage during high-speed extrusion coating of ordinary linear polypropylene, cell collapse during extrusion foaming, and sag and local thinning during thermoforming. Because it still has tensile strain hardening in the molten state and has a wide processing temperature range, it can be used for thermoforming, extrusion foaming, coating, blow molding, etc., which will further expand its application in the fields of automobiles, household appliances, food packaging, building materials, etc.

[0004] At present, there are two main ways to prepare high melt strength polypropylene: post-reactor modification method and reactor method. The post-reactor modification method uses unstable tertiary carbon free radicals to react with other active free radical chains by controlling the reaction conditions (free radical decomposition rate, reaction temperature, monomer concentration, etc.) to form a long-chain branched structure. This method uses free radical reactions, so degradation and cross-linking reactions of polypropylene are inevitable, the controllability of the polymer structure is poor, and the production cost is high. The reactor method, as the name implies, directly forms long-chain branched polypropylene by regulating the polymerization reaction in the reactor. This type of method is characterized by simple operation, controllable product structure and stable performance, but the reactor method has more stringent requirements on catalysts and polymerization conditions. Methods suitable for preparing long-chain branched polyethylene often fail when preparing long-chain branched polypropylene.

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

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

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

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

[0009] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

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

[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] Further, X is selected from Cl or Br.

[0013] In a second aspect, the present invention also provides a method for preparing a monophosphine halide, comprising the following steps:

[0014] S1, reacting magnesium metal, α-olefin halogenated hydrocarbon and iodine in an organic solvent to obtain a Grignard reagent; wherein the α-olefin halogenated hydrocarbon 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, reacting a phosphine trihalide and the Grignard reagent in an organic solvent to obtain a reaction solution; removing the organic solvent in the reaction solution to obtain a solid; washing the solid with an alkane, and concentrating and distilling the washed alkane in turn to obtain the monophosphine halide; wherein the phosphine trihalide is selected from at least one of phosphine trichloride, phosphine tribromide, phosphine trifluoride and phosphine triiodide.

[0016] Furthermore, the trihalogenated phosphorus is trichloride phosphorus and / or tribromide phosphorus.

[0017] Furthermore, the molar ratio of the α-olefin halogenated hydrocarbon, the metallic magnesium and the trihalogenated phosphorus is 1:(1.05-1.3):(0.85-1.1).

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

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

[0020] In a third aspect, the present invention further provides a method for preparing a polypropylene resin, comprising the following steps:

[0021] The monophosphine halide and propylene as described above are polymerized under the action 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 a Ziegler-Natta catalyst, a metallocene catalyst and a non-metallocene catalyst.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The monophosphine halide provided by the present invention has a specific structure. When used in a propylene polymerization reaction, the monophosphine halide undergoes a copolymerization reaction 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-performance random copolymer polypropylenes. DETAILED DESCRIPTION

[0026] The technical scheme of the present invention will be clearly and completely described below in conjunction with specific embodiments, but it will be appreciated by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work, all belong to the scope of protection of the present invention. If specific conditions are not indicated in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0027] The monophosphine halide and its preparation method and the preparation method of the polypropylene resin of the present invention are specifically described below.

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

[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 the present invention has a specific structure, the carbon-phosphine bond of the monophosphine halide has a long bond length and a large bond angle, the bonding property of the monophosphine halide is between a covalent bond and an ionic bond, has a strong reaction activity, and is more likely to undergo a substitution reaction; in a propylene polymerization reaction, the monophosphine halide mainly participates in the reaction as a polymerization monomer, and the monophosphine halide undergoes a polymerization reaction with propylene under the action of a catalyst to obtain a polypropylene molecule with a slight branching structure, thereby obtaining a polypropylene resin with a high melt strength; the synthesis cost is low, industrial amplification is easy to achieve, and the activity to the original polymerization system is relatively small.

[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; 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 formula is

[0035] 4-Pentenylphosphine dichloride, chemical formula is

[0036] 5-Hexenylphosphine dichloride, chemical formula is

[0037] 6-Heptenylphosphine dichloride, chemical 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, reacting magnesium metal, α-olefin halogenated hydrocarbon and iodine in an organic solvent to obtain a Grignard reagent; wherein the α-olefin halogenated hydrocarbon is 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. Reacting a phosphine trihalide and a Grignard reagent in an organic solvent to obtain a reaction solution; removing the organic solvent from the reaction solution to obtain a solid; washing the solid with an alkane, and concentrating and distilling the washed alkane in turn 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 the monophosphine halide of the invention has high synthesis yield, few post-processing steps and is suitable for industrial production.

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

[0043] In some embodiments of the present invention, the molar ratio of the α-olefin halogenated hydrocarbon, metallic magnesium and trihalogenated phosphorus is 1:(1.05-1.3):(0.85-1.1); typically but not limiting, for example, the molar ratio of the α-olefin halogenated hydrocarbon, metallic magnesium and trihalogenated phosphorus can be 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 a range of any two thereof.

[0044] In some embodiments of the present invention, step S1 is performed under a protective atmosphere; preferably, the protective gas 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, dibutyl ether, tetrahydrofuran (THF), n-hexane and heptane.

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

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

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

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

[0050] In some embodiments of the present invention, in step S2, the organic solvent includes at least one of diethyl ether, dibutyl 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, a trihalogenated phosphine, a Grignard reagent and an organic solvent are mixed and reacted at 20-25° C. for 8 h to 12 h to obtain a reaction solution; the organic solvent in the reaction solution is removed under vacuum to obtain a solid, and the solid is washed with an alkane for 3 to 5 times, and 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 a polypropylene resin is also provided, comprising the following steps:

[0054] The monophosphine halide and propylene undergo polymerization reaction under the action of a catalyst to obtain a polypropylene resin.

[0055] In the propylene polymerization reaction, monophosphine halide mainly participates in the reaction as a polymerization monomer, and copolymerizes with propylene under the action of an appropriate catalyst to obtain a 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-performance random copolymer polypropylenes.

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

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

[0058] In some embodiments of the present invention, the catalyst includes but is not limited to at least one of a Ziegler-Natta catalyst (ZN catalyst), a metallocene catalyst, and a non-metallocene catalyst; preferably, the catalyst includes MgCl 2 Supported catalyst system and / or VOCl 3 -AlEt 2 Cl catalytic system; specifically, MgCl 2 Supported catalyst systems include MgCl2 、TiCl 4 , at least one of alkyl aluminum, alkoxy aluminum, internal electron donor and external electron donor.

[0059] The present invention does not impose strict restrictions on the type of catalyst, and the catalyst may be 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 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, the co-catalyst alkyl aluminum, the ZN catalyst, the external electron donor, propylene and the monophosphine halide compound react to obtain the polypropylene resin.

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

[0064] Example 1

[0065] The monophosphine halogen compound provided in this embodiment is 3-butenylphosphine dichloride, and its chemical structure is

[0066]

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

[0068] S1. A three-necked flask equipped with a reflux condenser and a constant pressure dropping funnel was evacuated and filled with nitrogen for 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 in sequence, heated to 40°C, stirred and 1 grain (5-8 mg) of iodine was added. When the reaction solution was bubbling 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 reaction was refluxed for 6 hours; the residual solid was filtered out 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 phosphorus trichloride were added to a Shrek flask and stirred. Subsequently, the THF solution of 3-butenylmagnesium bromide was slowly added dropwise to the reaction system (injected with a syringe). After the addition was completed, the reaction was stirred at 25°C for 12 hours to obtain an off-white reaction solution; THF in the off-white reaction solution was removed by vacuum to obtain a white solid; the white solid was washed 3 times with n-hexane, the n-hexane after washing was combined, filtered, the filtrate was concentrated in vacuo, and then the concentrated solution was distilled under reduced pressure to collect a colorless distillate (oil bath temperature 116°C) to obtain 11.6 g of a colorless liquid, i.e., 3-butenylphosphine dichloride (hex-DCP), with a yield of 61%.

[0070] The mass spectrum results of 3-butenylphosphine dichloride obtained in this example are as follows:

[0071] 1HNMR(C 6 D 6 ,400MHz,298K),δ,ppm:5.89-5.5.92(m,1H,=CH), 4.98-5.02(q,2H,CH 2 ), 1.42-1.60(m,2H,CH 2 ), 1.07-1.18(t,2H,PCH 2 ); 31PNMR(C 6 D 6 ,400MHz,298K),δ,ppm:35.5.

[0072] Example 2

[0073] The monophosphine halogen compound provided in this embodiment is 5-hexenylphosphine dichloride, and its chemical structure is

[0074]

[0075] The preparation method of 5-hexenylphosphonic acid dichloride comprises the following steps:

[0076] S1. A three-necked flask equipped with a reflux condenser and a constant pressure dropping funnel was evacuated and filled with nitrogen for three times. Under the protection of nitrogen, 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 in sequence, heated to 40°C, stirred and 1 grain (5-8 mg) of iodine was added. When the reaction solution was bubbling 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 reaction was refluxed for 6 hours; the residual solid was filtered out under the protection of nitrogen to obtain a THF solution of 5-hexenylmagnesium bromide;

[0077] S2. Under a nitrogen atmosphere, 100 mL of anhydrous THF and 17.85 g (0.13 mol) of phosphorus trichloride were added to a Shrek flask and stirred. Subsequently, the THF solution of 5-hexenylmagnesium bromide was slowly added dropwise to the reaction system (injected with a syringe). After the addition was completed, the reaction was stirred at 25°C for 12 hours to obtain an off-white reaction solution; THF in the off-white reaction solution was removed by vacuum to obtain a white solid; the white solid was washed 3 times with n-hexane, the n-hexane after washing was combined, filtered, the filtrate was concentrated in vacuo, and then the concentrated solution was distilled under reduced pressure to collect a colorless distillate (oil bath temperature 116°C) to obtain 14.43 g of a colorless liquid, i.e., 5-hexenylphosphine dichloride (hex-DCP), with a yield of 65%.

[0078] The mass spectrum results of 5-hexenylphosphine dichloride obtained in this example are as follows:

[0079] 1HNMR(C 6 D 6 ,400MHz,298K),δ,ppm:5.75-5.85(m,1H,=CH), 4.94-5.04(q,2H,=CH 2 ), 2.04-2.15(q,2H,CH 2 =CHCH 2 ), 1.42-1.60(m,4H,CH 2 ), 1.07-1.18(t,2H,PCH 2 ); 31PNMR(C 6 D 6 ,400MHz,298K),δ,ppm:37.5.

[0080] Example 3

[0081] The monophosphine halogen compound provided in this embodiment is 4-pentenylphosphine dichloride, and its chemical structure is

[0082]

[0083] The preparation method of 4-pentenylphosphonic acid dichloride is similar to that of Example 1, except that, in step S1, 0.12 mol of 4-bromo-1-butene is replaced by 0.12 mol of 5-bromo-1-pentene.

[0084] Example 4

[0085] The monophosphine halogen compound provided in this embodiment is 6-heptenylphosphine dichloride, and its chemical structure is

[0086]

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

[0088] Example 5

[0089] The monophosphine halogen compound provided in this embodiment is 3-butenylphosphine dibromide, and its chemical structure is

[0090]

[0091] The preparation method of 3-butenylphosphine dibromide is similar to that of Example 1, except that, in step S2, 0.13 mol of phosphine trichloride is replaced by 0.13 mol of phosphine tribromide.

[0092] Example 6

[0093] The preparation method of the polypropylene resin provided in this embodiment comprises the following steps:

[0094] The polymerization kettle was heated to 60° C. and evacuated for 60 min, and then replaced with propylene for 3 times; 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) of Example 1 were flushed into the polymerization kettle using 200 mL of anhydrous n-hexane, and stirred for 3 min, and then 11 mg of ZN catalyst was flushed into the polymerization kettle using 200 mL of anhydrous n-hexane, propylene was introduced, the pressure in the polymerization kettle was maintained at 5 bar, and the polymerization reaction was carried out at 50-60° C. for 2 h; after the polymerization reaction was completed, the temperature of the polymerization kettle was lowered to room temperature, the residual propylene was vented, an acid-alcohol solution was added, filtered, washed with ethanol and water for 3 times respectively, and vacuum dried at 60° C. for 20 h to obtain 208 g of white powder, which was a polypropylene resin; the polypropylene resin contained a branched or cross-linked structure, and the gel content was 3% by weight.

[0095] Example 7

[0096] The preparation method of the polypropylene resin provided in this embodiment comprises the following steps:

[0097] After heating the polymerization kettle to 60°C and evacuating for 60 minutes, propylene was used for replacement 3 times; 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) of Example 2 were flushed into the polymerization kettle using 200 mL of anhydrous n-hexane, stirred for 3 minutes, and then 11 mg of ZN catalyst was flushed into the polymerization kettle using 200 mL of anhydrous n-hexane, propylene was introduced, the pressure in the polymerization kettle was maintained at 5 bar, and the polymerization reaction was carried out at 50-60°C for 2 hours; after the polymerization reaction was completed, the temperature of the reactor was lowered to room temperature, the residual propylene was vented, the acid alcohol solution was added, filtered, washed 3 times with ethanol and water respectively, and dried under vacuum at 60°C for 20 hours. 198 g of white powder was obtained, which was 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 based on Example 6, except that the 3-butenylphosphine dichloride of Example 1 is not added to obtain a reference homopolymer polypropylene resin.

[0100] Comparative Example 2

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

[0102] Test example

[0103] The properties of the polypropylene resins obtained in Example 6, Example 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 in a vacuum drying oven at 50°C to constant weight, and the weight was recorded as W1. The dried polypropylene resin was then dissolved in xylene, and the resin was fully dissolved by oscillation at 135°C. The resin was filtered through a 200-mesh stainless steel mesh, and the insoluble polymer remaining on the stainless steel mesh was collected. The insoluble polymer on the stainless steel mesh was dried in a vacuum drying oven at 100°C for 4 hours, and the weight was recorded as W2. The formula for calculating the gel content of the polypropylene resin is as follows: Gel content (weight %) = (W2 / W1) × 100 (weight %).

[0105] Melt strength: The experimental device for determining melt strength consists of a single screw extruder equipped with a capillary and a Gottfert Rheotens melt strength tester. First, the polypropylene resin melt to be tested for melt strength is extruded from the extruder die, and then the obtained extruded melt beam spline is pulled by two rollers with opposite movement directions mounted on a balance beam. The force applied to the melt beam when it is stretched is a function of the roller speed and time. The rollers are uniformly accelerated until the melt beam breaks, and the force applied to the melt beam when it breaks is defined as the melt strength.

[0106] Mechanical properties: The impact strength was measured according to the method specified in ASTM D256A.

[0107] Table 1

[0108] Gel content (weight %) 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] It can be seen from Table 1 that 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 into the propylene polymerization process, the melt properties (melt strength) and impact toughness (impact strength) of the obtained polypropylene resin are greatly improved; the determination of gel content shows 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, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements 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 monophosphine halide, characterized in that Has the following structure: In the formula, n is an integer between 1 and 4, and X is selected from any one of F, Cl, Br and I.

2. The monophosphine halide according to claim 1, characterized in that X is selected from Cl or Br.

3. The method for preparing the monophosphine halide according to claim 1 or 2, characterized in that: The steps include: S1, reacting magnesium metal, α-olefin halogenated hydrocarbon and iodine in an organic solvent to obtain a Grignard reagent; wherein the α-olefin halogenated hydrocarbon 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, reacting a phosphine trihalide and the Grignard reagent in an organic solvent to obtain a reaction solution; removing the organic solvent in the reaction solution to obtain a solid; washing the solid with an alkane, and concentrating and distilling the washed alkane in turn to obtain the monophosphine halide; wherein the phosphine trihalide is selected from at least one of phosphine trichloride, phosphine tribromide, phosphine trifluoride and phosphine triiodide.

4. The method for preparing monophosphine halide according to claim 3, characterized in that: The phosphine trihalide is phosphine trichloride and / or phosphine tribromide.

5. The method for preparing monophosphine halide according to claim 3, characterized in that: The molar ratio of the α-olefin halogenated hydrocarbon, the metal magnesium and the trihalogenated phosphorus is 1:(1.05-1.3):(0.85-1.1).

6. The method for preparing monophosphine halide according to claim 3, characterized in that: In step S1, the reaction includes: reflux reaction for 4 to 6 hours.

7. The method for preparing monophosphine halide according to claim 3, characterized in that: In step S2, the reaction includes: reacting at 20-25° C. for 8-12 hours.

8. A method for preparing a polypropylene resin, characterized in that: The steps include: The monophosphine halide according to claim 1 or 2 and propylene are polymerized under the action of a catalyst to obtain the polypropylene resin.

9. The method for preparing a polypropylene resin according to claim 8, characterized in that: The mass ratio of the monophosphine halide to the propylene is (0.001-20):

100.

10. The method for preparing a polypropylene resin according to claim 8, characterized in that: The catalyst includes at least one of a Ziegler-Natta catalyst, a metallocene catalyst and a non-metallocene catalyst.

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