Ultrahigh-flowability and high-crystallinity polypropylene injection molding material and preparation method thereof

Abstract

The invention discloses an ultrahigh-flowability and high-crystallinity polypropylene injection molding material and a preparation method thereof, and belongs to the technical field of thermoplastic high polymer materials. According to the method disclosed by the invention, cheap and easily available materials are adopted as reaction raw materials, the reaction raw materials and the composite catalyst are subjected to a polymerization reaction in a hydrogen environment, specific extrusion granulation treatment is combined, the ultrahigh-flowability and high-crystallinity polypropylene special material is obtained, the whole preparation process is simple and convenient, the raw materials are easily available, and industrial production is easy; the prepared polypropylene injection molding material has the advantages of good fluidity, high transparency, high modulus, low VOCs, low odor, no plasticizer, less precipitation, rigidity and toughness balance, short injection molding period, fast molding, low warping rate, excellent crystallization performance and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of thermoplastic polymer materials, and in particular relates to an ultra-high flow and high crystallinity polypropylene injection molding material and a preparation method thereof. Background Art

[0002] Ultra-high melt index thin-wall injection molding products with a melt index of 90-110g / 10min have a greatly improved melt flow rate while maintaining the excellent properties of the original thin-wall injection molding products such as high rigidity, high modulus, and high crystallization. When used in traditional food packaging fields such as fast food boxes, beverage cups, and bottle caps, injection molding and filling are easier, which can further shorten the molding process cycle and improve production efficiency; and can significantly reduce processing temperature, injection pressure and energy consumption, and can reduce the injection temperature by 20-30℃, and reduce the injection pressure by 30% at the same temperature, which provides great help for energy conservation and emission reduction for processing enterprises and has good market prospects. On the other hand, this type of product can also be used as a modified base material in fields such as automobiles and small household appliances that require high rigidity and heat resistance. The main function is to increase fluidity, provide rigidity and heat resistance, and control shrinkage. The main application area is the thin-walling of large polypropylene automotive parts. The product has excellent crystallization performance, rigidity and toughness, low shrinkage and low warpage deformation. It is suitable for high-flow long glass fiber reinforced formulas, talc-filled formulas and POE toughening formulas. The product adopts hydrogen adjustment process, has no peroxide residue, low VOC, low odor, and does not contain plasticizers. It is used to produce door panels, instrument panels, door sills, pillars, bumpers and other automotive interior and exterior trims, and has good market prospects.

[0003] Existing polypropylene injection molding materials can be produced by oxide degradation and hydrogen adjustment. The peroxide method mainly involves adding peroxide during twin-screw extrusion granulation to break the molecular chains with larger molecular weights and degrade them into polypropylene with relatively lower molecular weights. The fiber material prepared by the degradation method has the advantages of narrow molecular weight distribution and good fluidity, but the presence of peroxide residues may cause the injection molding materials to have odor and fast aging. However, when using the existing method to prepare ultra-high fluidity polypropylene injection molding materials (90-110g / 10min), the preparation process is complicated and not easy to industrialize. Summary of the invention

[0004] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide an ultra-high flow, high crystallinity polypropylene injection molding material and a preparation method thereof, so as to solve the technical problems that the preparation process of the existing ultra-high flow polypropylene injection molding material is complicated and not easy for industrial production.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The invention discloses a method for preparing an ultra-high flow and high crystallinity polypropylene injection molding material, comprising the following steps:

[0007] S1: using the pretreated propylene and the composite catalyst as raw materials, sequentially performing a prepolymerization reaction, a first polymerization reaction, and a second polymerization reaction to obtain a polymerization product; wherein the first polymerization reaction and the second polymerization reaction are performed under hydrogen conditions;

[0008] S2: flash evaporation separation and drying of the polymerized product are performed in sequence, followed by extrusion granulation to obtain an ultra-high flow and high crystallinity polypropylene injection molding material;

[0009] The composite catalyst comprises a diether catalyst, a co-catalyst and an electron donor;

[0010] During the first polymerization reaction and the second polymerization reaction, the hydrogen concentration is 3200-3700 ppm.

[0011] Further, in S1, the pretreated propylene is obtained by sequentially subjecting liquid propylene to free water removal, desulfurization, carbon monoxide removal, and arsenic and phosphorus removal treatments;

[0012] The co-catalyst in the composite catalyst is triethylaluminum; and the electron donor is dicyclopentyldimethoxysilane.

[0013] Further, in S1, using the pretreated propylene and the composite catalyst as raw materials, sequentially performing a prepolymerization reaction, a first polymerization reaction, and a second polymerization reaction comprises the following steps:

[0014] The pretreated propylene is placed in a pre-contact tank and subjected to a prepolymerization reaction with a composite catalyst to obtain a prepolymerization product; the obtained prepolymerization product enters a first loop polymerization reactor, and after adding propylene and hydrogen, a first polymerization reaction is carried out to obtain a first polymerization product; the obtained first polymerization product enters a second loop polymerization reactor, and after adding propylene and hydrogen, a second polymerization reaction is carried out to obtain a polymerization product.

[0015] Furthermore, the mass ratio of the diether catalyst to the total propylene feed amount of the whole process is (0.000014-0.000016):1; the mass ratio of the co-catalyst to the total propylene feed amount of the whole process is (0.0001-0.00017):1;

[0016] The mass ratio of the co-catalyst to the total propylene feed amount in the whole process is (60-100): 1;

[0017] The mass of the electron donor is 3.5% of the mass of the composite catalyst.

[0018] Furthermore, the temperature of the prepolymerization reaction is 20±1° C., the pressure is 3.9±0.1 MPa, the amount of propylene added is 1000-1100 kg / h, and the reaction time is 10-15 min.

[0019] Furthermore, the reaction temperature of the first prepolymerization reaction is 69-70°C, the pressure is 3.3-4.3Mpa, the propylene addition amount is 14500-15500kg / h, the reaction time is 1.5-2.0h, and the hydrogen is controlled to a stable hydrogenation amount of 3300±50ppm.

[0020] Furthermore, the reaction temperature of the second prepolymerization reaction is 69-70°C, the pressure is 3.3-4.3Mpa, the propylene addition amount is 8500-10500kg / h, the reaction time is 1.0-1.5h, and the hydrogen is controlled to maintain the hydrogenation amount at 3300±50ppm.

[0021] Furthermore, in S2, a compounding auxiliary agent is also added during the extrusion granulation process, and the compounding auxiliary agent consists of antioxidant 1010, antioxidant 168, calcium stearate and nucleating agent; wherein the mass ratio of antioxidant 1010, antioxidant 168, calcium stearate and nucleating agent is 2:4:2:2.

[0022] Further, in S2, the extrusion granulation is carried out using the first to seventh sections of the granulator, and the temperatures of the first to seventh sections of the granulator are 215°C, 225°C, 235°C, 235°C, 225°C, 210°C, and 200°C during the extrusion granulation;

[0023] The throttle valve opening during the extrusion granulation is 15%-30%, the pelletizing water flow is 240-255 kg / h, the pelletizing temperature is 44-48° C., and the pelletizer speed is 680-850 rpm.

[0024] The invention also discloses an ultra-high flow and high crystallinity polypropylene injection molding material prepared by the preparation method.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] A method for preparing an ultra-high flow and high crystallinity polypropylene injection molding material, using cheap and readily available materials as reaction raw materials, carrying out polymerization reaction together with a composite catalyst in a hydrogen environment, and combining with a specific extrusion granulation process to obtain an ultra-high flow and high crystallinity polypropylene special material, the whole preparation process is simple, the raw materials are readily available, and it is easy to industrialize production; the composite catalyst used has the advantages of high activity, good hydrogen adjustment sensitivity and high stereospecificity, and is very conducive to the production of high melt flow products by hydrogen adjustment.

[0027] Furthermore, by using compound additives in the extrusion granulation process, the functional additives are mixed with main and auxiliary antioxidants and calcium stearate in a certain proportion to form compound granules for use, and the main parameters of the extrusion granulation system are adjusted appropriately, so as to achieve the production of high-flow and high-crystallization injection molding materials, and the products have the advantages of no peroxide residue and low odor.

[0028] The present invention also discloses a polypropylene injection molding material prepared by the above-mentioned preparation method. The ultra-high flow and high-crystallization polypropylene special material has the advantages of good fluidity, high transparency, high modulus, low VOCs, low odor, no plasticizer, less precipitation, rigidity-toughness balance, short injection molding cycle, fast molding, low warpage, excellent crystallization performance, etc. It is mainly used in high-end consumer goods such as automobiles and small household appliances, and in fields with high rigidity and heat resistance requirements, to increase product fluidity, provide rigidity and heat resistance, and control shrinkage. Secondly, it can be used as a modified material, with formulas such as high-flow long-wave fiber reinforcement, talcum powder filling, and POE toughening, and can also be used in thin-wall injection molding fields such as traditional food packaging. Due to its more excellent melt flow performance, the injection molding process is easier to fill the mold, which can further shorten the molding processing cycle and reduce production energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A system structure diagram for preparing the ultra-high flow and high crystallinity polypropylene injection molding material of the present invention;

[0030] Among them: D201-pre-contact tank; R200-prepolymerization reactor; R201-first loop polymerization reactor; R202-second loop polymerization reactor; D301-flash tank; D501-steaming tank; P201-first loop circulation axial flow pump; P202-second loop circulation axial flow pump; F301-low-pressure degassing filter; P808-extruder screen changer heat transfer oil circulation pump; P809-extruder die head heat transfer oil circulation pump. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0032] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0033] Herein, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0034] In this document, unless otherwise specified, “includes,” “including,” “contains,” “has,” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0035] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0036] The preparation of polypropylene injection molding materials with a melt index of up to 90-110g / 10min places higher requirements on the catalyst system, polymerization process control under high hydrogen concentration, and extrusion granulation. At the same time, the product needs to have good crystallization performance, rigidity, heat resistance, and dimensional stability. It is necessary to add high-efficiency nucleating agents to accurately control the aggregate structure of the base resin and make the resin have low VOCs and low odor. During production, it is necessary to evaluate the catalyst, polymerization reaction, and additive formula, optimize the polymerization process parameters and extrusion granulation process parameters, and ensure stable production.

[0037] The present invention provides a polypropylene material with high fluidity, high crystallinity, high rigidity, high heat resistance and dimensional stability, so as to improve the melt index of polypropylene, add a high-efficiency nucleating agent to accurately control the aggregate structure of the base resin, and improve the impact resistance of the material and the toughness of the product. Another object of the present invention is to provide a method for preparing an ultra-high fluidity, high crystallinity polypropylene material.

[0038] The present invention provides a method for preparing an ultra-high flow and high crystallinity polypropylene injection molding material (the preparation system used is as follows Figure 1 As shown), comprising the following steps:

[0039] 1. Composite catalyst: It uses diether internal electron donors, which have the advantages of high activity, good hydrogen adjustment sensitivity and high stereospecificity, which is conducive to the production of high-efficiency catalysts using hydrogen adjustment method;

[0040] A high-efficiency catalyst with a mass of 40 kg is mixed with 117.5 L of vaseline oil and 55 L of vaseline fat and stored at a constant temperature of 10° C. for later use;

[0041] The composite catalyst also includes a diether catalyst, a co-catalyst and an electron donor; the co-catalyst in the composite catalyst is triethylaluminum; and the electron donor is dicyclopentyldimethoxysilane.

[0042] 2. Raw material refining

[0043] Fresh liquid propylene passes through a molecular sieve tower to remove free water contained in the raw material, and a desulfurization tower removes organic sulfur and sulfide to reduce the total sulfur content to less than 1ppm. The desulfurized propylene passes through a propylene light component stripping tower to remove light components such as carbon monoxide and water in the propylene, and passes through a catalyst tower to remove arsenic and phosphorus in the raw material to obtain pretreated propylene, which then enters the feed tank D302 and is pumped into the loop reactor by a high-speed pump.

[0044] 3. Hydrogenation reaction

[0045] The reaction system was operated at high pressure, and the hydrogen concentrations of the first loop polymerization reactor R201 and the second loop polymerization reactor R202 were adjusted to 3200-3700 ppm. At the same time, it was confirmed that the axial flow pump power of the first loop polymerization reactor R201 and the second loop polymerization reactor R202 was stable. The mass ratio of the diether catalyst to the total propylene feed in the prepolymerization and polymerization process is controlled to be 0.000014-0.000016:1; the mass ratio of the co-catalyst to the total propylene feed in the prepolymerization and polymerization process is controlled to be 0.0001-0.00017:1; the mass ratio of the co-catalyst to the external electron donor is 60-100:1; the diether catalyst, 3.5% external electron donor and the co-catalyst are fully reacted in the pre-contact tank D201 and then enter the prepolymerization reactor R200, the reaction temperature of the prepolymerization reactor R200 is controlled to be 20±1°C, the pressure is 3.9±0.1Mpa, the propylene addition amount is 1000-1100kg / h, and the reaction time is 10-15 minutes; the polymer in the prepolymerization reactor R200 enters the first loop polymerization reactor R201, and the first polymerization reaction is carried out after hydrogen is added (hydrogenation polymerization reaction), control the reaction temperature of the first loop polymerization reactor R201 to be: 70±0.5℃, pressure to be: 3.85±0.1Mpa, propylene addition to be: 14500-15500kg / h, reaction time to be 1.5-2.0 hours; hydrogen is controlled to be: 3300±50ppm stable hydrogenation amount; the polymer produced by the first loop polymerization reactor R201 enters the second loop polymerization reactor R202 through a belt connection, and continues the second polymerization reaction (hydrogenation polymerization reaction) after adding hydrogen, control the reaction temperature of the second loop polymerization reactor R202 to be: 70±0.5℃, pressure to be: 3.80±0.1Mpa, propylene addition to be: 8500-10500kg / h, reaction time to be 1.0-1.5 hours hydrogen is controlled to be: 3300±50ppm to maintain the hydrogenation amount temperature;

[0046] 4. Flash and steam drying

[0047] The polymer slurry from the second loop polymerization reactor R202 is flashed on the large flash line and then enters the flash tank D301 for separation, and the high-pressure propylene recovery system recovers the flashed propylene; the slurry from the flash tank D301 enters the low-pressure degassing system F301 and then enters the steam tank D501 for polymer steaming inactivation, and then is dried by the polymer drying system to produce ultra-high fluidity, high-crystalline polypropylene to the extrusion granulation system.

[0048] 5. Extrusion granulation

[0049] Due to the high melt mass flow rate and very low melt strength of thin-walled injection molding products, the barrel temperature (Table 1) and heat transfer oil temperature of the extrusion granulator were appropriately lowered based on the wire drawing material, the speed of the pelletizer was increased, and the throttle valve opening, pelletizing water flow, water temperature, etc. were adjusted synchronously. Specifically: ① Heat transfer oil temperature: extruder screen changer heat transfer oil circulation pump P808 outlet control: 205℃, extruder die head heat transfer oil circulation pump P809 outlet control: 195℃; ② Throttle valve opening: 15%-30%; ③ Pelletizing water flow: 240-255kg / h, temperature: 44-48℃ (determined according to the operation of the pelletizer); ④ Pelletizer speed: 680-850rpm, knife feed air pressure: 0.43-0.51MPa (determined according to pelletizer current and pellet shape and size).

[0050] Table 1 Barrel temperature of extrusion granulator

[0051] Section 1 Section 2 Section 3 Section 4 Section 5 Section 6 Section 7 215 225 235 235 225 210 200

[0052] At the same time, in the backlog granulation process, compound additives are used, that is, functional additives, main and auxiliary antioxidants and calcium stearate are made into compound agent particles in a certain proportion for use. Among them, QY100G with blue phase function adopts Milliken's HPN-900ei compound additive, and QY100G-1 without blue phase function adopts Milliken's HPN-20E compound additive. The addition amount of compound additives is 2000-3000ppm, preferably 2500-2800ppm; at the same time, 200-300ppm of antistatic agent GMS is added, preferably 200ppm. In actual production, the addition amount of additives needs to be adjusted in time according to the test values ​​of mechanical properties. The product specifications and indicators of compound additives are shown in Table 2. Among them, the mass ratio of antioxidant 1010, antioxidant 168, calcium stearate and nucleating agent is 2:4:2:2.

[0053] Table 2 Specifications and indicators of compound additives

[0054]

[0055] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0056] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples where specific conditions are not specified are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples are conventional commercial products unless otherwise specified, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" means weight percentage, "part" means weight part, and ratio means weight ratio.

[0057] The preparation method adopted by the present invention comprises Figure 1 The preparation system shown is completed, as Figure 1 As shown, the system mainly includes a propylene refining system, a catalyst preparation system, a prepolymerization reaction system, a first and a second polymerization reaction system, a polymer degassing and monomer recovery system, a polymer steam drying system, an extrusion granulation system, etc.; wherein the catalyst storage tank, the activator storage tank and the electron donor storage tank in the catalyst preparation system are connected to the catalyst pre-reduction tank, the catalyst pre-reduction tank is connected to the prepolymerization reactor R200 through the catalyst pre-contact tank D201, the prepolymerization reactor R200 is connected to the first loop polymerization reactor R201 and the second loop polymerization reactor R202 in sequence, and the reaction material outlet of the second loop polymerization reactor R202 is connected to the drying system through the flash tank D301, the bag filter, and the steaming tank D501 in sequence. The drying system is provided with a propylene powder outlet, and the powder outlet is connected to a further refining process. The propylene feed pipeline is respectively connected to the catalyst online mixer, the first loop polymerization reactor R201 and the second loop polymerization reactor R202, and the hydrogen pipeline is connected to the first loop polymerization reactor R201. Switching the prepolymerization and polymerization reactions to high pressure operation of 3.8Mpa-3.9Mpa can increase the hydrogen content in the loop reactor, expand the range of melt flow rate, and be more conducive to the control of morphology, isotacticity and molecular weight, thereby increasing the strength of the product and improving the performance of the product.

[0058] Example 1

[0059] An ultra-high flow, high crystallinity polypropylene injection molding material and a preparation method thereof, comprising the following steps:

[0060] At the beginning of the preparation, the hydrogen concentration of the first loop polymerization reactor R201 and the second loop polymerization reactor R202 is adjusted to 3500ppm, and the power of the first loop circulation axial flow pump P201 and the second loop circulation axial flow pump P202 is confirmed to be stable. The mass ratio of the catalyst to the total propylene feed in the prepolymerization and polymerization process is controlled to be: 0.000014-0.000016:1, the mass ratio of the activator to the total propylene feed in the prepolymerization and polymerization process is controlled to be: 0.0001-0.00017:1, and the mass ratio of the activator to the external electron donor is: 60-100:1; ZN-127 catalyst, 3.5% external electron donor and activator are fully reacted in the pre-contact tank D201 and then enter the prepolymerization reactor R200, and the prepolymerization reactor R2 is controlled to be: 00 reaction temperature: 20±1℃, pressure: 3.9±0.1Mpa, propylene addition amount: 1000-1100kg / h, reaction time: 10-15 minutes; the polymer in the prepolymerization reactor R200 reactor enters the first loop polymerization reactor R201, and hydrogenation polymerization reaction is carried out after adding hydrogen. The reaction temperature of the first loop polymerization reactor R201 is controlled to be 70±0.5℃, pressure: 3.85±0.1Mpa, propylene addition amount: 14500-15500kg / h, reaction time is 1.5-2.0 hours; hydrogen control is: 3200-3700ppm; the polymer produced by the first loop polymerization reactor R201 enters the second loop polymerization reactor R202 through a belt connection, and continues to carry out hydrogenation polymerization after adding hydrogen. The reaction temperature of the second loop polymerization reactor R202 is controlled to: 70±0.5℃, the pressure is: 3.80±0.1Mpa, the amount of propylene added is: 8500-10500kg / h, and the reaction time is 1.0-1.5 hours. Hydrogen control The polymer slurry of R202 is: 3200-3700ppm; the polymer slurry of R202 is flashed on the large flash line and then enters the flash tank D301 for separation, and the high-pressure propylene recovery system recovers the flashed propylene; the slurry in the flash tank D301 enters the low-pressure degassing filter F301 and then enters the steam tank D501 for polymer steaming inactivation, and then is dried by the polymer drying system to produce ultra-high fluidity, high-crystallization polypropylene to the extrusion granulation system; the production of 302 tons of ultra-high fluidity, high-crystallization QY100G-1 was completed, and the product quality was qualified.

[0061] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing an ultra-high flow and high crystallinity polypropylene injection molding material, It is characterized in that The following steps are involved: S1: using the pretreated propylene and the composite catalyst as raw materials, sequentially performing a prepolymerization reaction, a first polymerization reaction, and a second polymerization reaction to obtain a polymerization product; wherein the first polymerization reaction and the second polymerization reaction are carried out under hydrogen conditions; S2: flash evaporation separation and drying of the polymerized product are performed in sequence, followed by extrusion granulation to obtain an ultra-high flow and high crystallinity polypropylene injection molding material; The composite catalyst comprises a diether catalyst, a co-catalyst and an electron donor; During the first polymerization reaction and the second polymerization reaction, the hydrogen concentration is 3200-3700 ppm.

2. A method for preparing an ultra-high flow, high crystallinity polypropylene injection molding material according to claim 1, It is characterized in that In S1, the pretreated propylene is obtained by sequentially subjecting liquid propylene to free water removal, desulfurization, carbon monoxide removal, and arsenic and phosphorus removal treatments; The co-catalyst in the composite catalyst is triethylaluminum; and the electron donor is dicyclopentyldimethoxysilane.

3. A method for preparing an ultra-high flow, high crystallinity polypropylene injection molding material according to claim 2, It is characterized in that In S1, the pre-treated propylene and the composite catalyst are used as raw materials to sequentially carry out a prepolymerization reaction, a first polymerization reaction, and a second polymerization reaction, which includes the following steps: The pretreated propylene is placed in a pre-contact tank and subjected to a prepolymerization reaction with a composite catalyst to obtain a prepolymerization product; the obtained prepolymerization product enters a first loop polymerization reactor, and after adding propylene and hydrogen, a first polymerization reaction is carried out to obtain a first polymerization product; the obtained first polymerization product enters a second loop polymerization reactor, and after adding propylene and hydrogen, a second polymerization reaction is carried out to obtain a polymerization product.

4. A method for preparing an ultra-high flow, high crystallinity polypropylene injection molding material according to claim 3, It is characterized in that The mass ratio of the diether catalyst to the total propylene feed amount of the whole process is (0.000014-0.000016):1; the mass ratio of the co-catalyst to the total propylene feed amount of the whole process is (0.0001-0.00017):1; The mass ratio of the co-catalyst to the total propylene feed amount in the whole process is (60-100): 1; The mass of the electron donor is 3.5% of the mass of the composite catalyst.

5. A method for preparing an ultra-high flow, high crystallinity polypropylene injection molding material according to claim 3, It is characterized in that The temperature of the prepolymerization reaction is 20±1° C., the pressure is 3.9±0.1 MPa, the amount of propylene added is 1000-1100 kg / h, and the reaction time is 10-15 min.

6. A method for preparing an ultra-high flow, high crystallinity polypropylene injection molding material according to claim 3, It is characterized in that The reaction temperature of the first prepolymerization reaction is 69-70°C, the pressure is 3.3-4.3Mpa, the propylene addition amount is 14500-15500kg / h, the reaction time is 1.5-2.0h, and the hydrogen is controlled to a stable hydrogenation amount of 3300±50ppm.

7. A method for preparing an ultra-high flow, high crystallinity polypropylene injection molding material according to claim 3, It is characterized in that The reaction temperature of the second prepolymerization reaction is 69-70°C, the pressure is 3.3-4.3Mpa, the propylene addition amount is 8500-10500kg / h, the reaction time is 1.0-1.5h, and the hydrogen is controlled to maintain the hydrogenation amount at 3300±50ppm.

8. A method for preparing an ultra-high flow, high crystallinity polypropylene injection molding material according to claim 1, It is characterized in that In S2, a compounding auxiliary agent is also added during the extrusion granulation process, and the compounding auxiliary agent consists of antioxidant 1010, antioxidant 168, calcium stearate and nucleating agent; wherein the mass ratio of antioxidant 1010, antioxidant 168, calcium stearate and nucleating agent is 2:4:2:

2.

9. The method for preparing an ultra-high flow and high crystallinity polypropylene injection molding material according to claim 1, It is characterized in that In S2, the extrusion granulation is carried out using the first to seventh sections of the granulator, and the temperatures of the first to seventh sections of the granulator are 215°C, 225°C, 235°C, 235°C, 225°C, 210°C, and 200°C during the extrusion granulation. The throttle valve opening during the extrusion granulation is 15%-30%, the pelletizing water flow is 240-255 kg / h, the pelletizing temperature is 44-48° C., and the pelletizer speed is 680-850 rpm.

10. An ultra-high flow, high crystallinity polypropylene injection molding material, It is characterized in that The ultra-high flowability and high crystallinity polypropylene injection molding material is prepared by the preparation method described in any one of claims 1 to 9.

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