A high-flow, high-impact polypropylene material and its preparation method

Abstract

This invention relates to the field of polymer technology, specifically disclosing a high-flow, high-impact polypropylene material and its preparation method. The preparation method includes the following steps: S1: Propylene and hydrogen are added to a loop reactor. A Ziegler-Natta catalyst is added to the first loop reactor. The hydrogen addition to both loop reactors is controlled at 4500 ppm-6500 ppm, and the slurry density is 470-495 kg / m³. 3 The temperature of two loop reactors is adjusted to 67-71℃ and the pressure to 3.8-4.0MPa. Homopolymer polypropylene powder is obtained by circulating the two loop reactors in series. S2: The homopolymer polypropylene powder is then fed into a gas-phase reactor, where ethylene is introduced. By controlling and adjusting the ethylene content to 12-16%, the ethylene / (ethylene + propylene) ratio to 0.25-0.40, and the hydrogen / ethylene ratio to 0.030-0.060, high-impact copolymer polypropylene powder is obtained. The polypropylene product provided by this invention has good toughness and flowability, effectively solving the problem of balancing rigidity and toughness in polypropylene materials without the addition of nucleating agents.

Description

Technical Field

[0001] This invention relates to the field of polymer technology, specifically disclosing a high-flow, high-impact polypropylene material and its preparation method. Background Technology

[0002] With the improvement of polypropylene production technology, PP products with higher melt flow rate (MFR) and better impact strength have been developed and applied, leading to rapid market demand growth. High-flow PP can reduce processing temperature, injection pressure, and clamping force during product manufacturing, thereby reducing energy consumption, shortening the product molding cycle, and significantly increasing product output. Furthermore, using high-flow PP allows for the injection molding of thin-walled products, reducing raw material usage and lowering costs. However, its impact strength is ≤12kJ / m². 2 High-flow PP has poor impact resistance and cannot meet the requirements of downstream markets.

[0003] High-flow, high-impact polypropylene possesses excellent flow properties and good toughness, making it widely used in automotive material modification, washing machine manufacturing, and other home appliance applications. As downstream modification plants continuously improve their technical formulations, the demands for raw material performance are becoming increasingly diverse.

[0004] In recent years, most large-capacity polypropylene producers have focused on developing impact copolymers. This indicates that improving both flow rate and impact performance is a growing trend. Currently, two main methods are used in China for preparation: 1. Using a melt index of 16-30 g / 10 min and an impact strength of 8-15 kJ / m². 2 1. The raw materials are obtained through subsequent modification and processing. 2. High-flow, high-impact polypropylene products are produced through a process of two gas-phase reactors connected in series. This production method generally adopts the Innovene gas-phase polypropylene process technology.

[0005] Chinese patent CN 109111643 A discloses a high-flow, high-impact polypropylene material and its preparation method. The method employs a stirred-bed reactor with a first and second reactor connected in series, and uses various additives including antioxidants, acid scavengers, slip agents, and nucleating agents. However, this preparation method is only applicable to process equipment with two gas-phase reactors connected in series; it is not suitable for other equipment. In particular, the Spheripol process, the mainstream polypropylene process in China, cannot be used to prepare high-flow, high-impact polypropylene materials due to differences in equipment and processes.

[0006] Chinese patent CN 115322482 A discloses a high-impact, high-flow homopolymer polypropylene material and its preparation method. The method involves mixing polypropylene powder, antioxidants, auxiliary antioxidants, nucleating agents, halogen absorbers, and antistatic agents in a high-speed mixer. The mixture is then extruded and granulated using a twin-screw extruder and dried to obtain the high-impact, high-flow homopolymer polypropylene material. However, this method requires secondary processing of the modified homopolymer polypropylene, increasing production costs and time. Summary of the Invention

[0007] The technical solution adopted in this invention is as follows:

[0008] In a first aspect, the present invention provides a method for preparing high-flow, high-impact polypropylene, using equipment including two loop reactors connected in series and one gas-phase fluidized bed reactor, the preparation method comprising the following steps:

[0009] S1: Propylene and hydrogen are added to a loop reactor. Ziegler-Natta catalyst is added to the first loop reactor. The hydrogen addition rate in both loop reactors is controlled at 4500ppm-6500ppm, and the slurry density is 470-495kg / m³. 3 The temperature of the two loop reactors was adjusted to 67-71℃ and the pressure to 3.8-4.0MPa. The two loop reactors were circulated in series to obtain homopolymer polypropylene powder with a melt index of 25-40g / 10min.

[0010] S2: Homopolymer polypropylene powder is fed into a gas phase reactor, and ethylene, propylene and hydrogen are introduced. By controlling and adjusting the ethylene molar content to 12-16%, the ethylene / (ethylene+propylene) molar ratio to 0.25-0.40 and the hydrogen / ethylene molar ratio to 0.030-0.060, high-impact copolymer polypropylene powder is obtained.

[0011] S3: Add compounding agents to the obtained high-impact polypropylene powder, mix evenly, and then granulate and extrude to produce high-flow, high-impact polypropylene material.

[0012] Preferably, the compounding additives include antioxidants and acid scavengers, and the amount of the compounding additives added is 0.1-0.3% of the mass of the high-impact polypropylene powder.

[0013] Furthermore, the mass ratio of the antioxidant to the acid absorber is 3 to 2:1.

[0014] Furthermore, the antioxidants are 1010 and 168 in a mass ratio of 1:2.

[0015] Furthermore, the acid absorbent is calcium stearate.

[0016] In a second aspect, the present invention provides a high-flow, high-impact polypropylene, which is prepared by the preparation method described in the first aspect.

[0017] Preferably, the high-flow, high-impact polypropylene melt flow rate (2.16 kg) is 30.00 ± 10 g / 10 min; impact strength: ≥ 30 KJ / m 2 Flexural modulus: ≥800MPa.

[0018] The beneficial effects achieved by this invention are as follows:

[0019] The polypropylene product provided by this invention has good toughness and flowability, and no nucleating agent is added, which solves the problems of high cost and complicated process caused by excessive use of additives. By controlling the ethylene content and ethylene / (ethylene+propylene) ratio in the gas phase reactor, the problem of balancing the rigidity and toughness of polypropylene materials is effectively solved. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the following embodiments. It should be noted that this invention is not limited to the following embodiments.

[0021] The following Examples 1-5 of the present invention are used to prepare the polypropylene polymer. Specifically, the polypropylene polymer is synthesized using a Sphripol polymerization apparatus with a dual-loop tube-single gas phase reactor, and a conventional amount of Ziegler-Natta catalyst is used in the Sphripol process.

[0022] Example 1

[0023] This invention provides a high-flow, high-impact polypropylene base material and its preparation method.

[0024] Includes the following steps:

[0025] Propylene and hydrogen were used as raw materials and added to a loop reactor. Ziegler-Natta catalyst was added to the first loop reactor. The hydrogen addition rate to the loop reactor was controlled at 4500 ppm and the slurry density at 490 kg / m³. 3 Homopolymer polypropylene powder with a melt index of 25 g / 10 min was obtained by circulating the material through two loop reactors in series.

[0026] Homopolymer polypropylene powder is fed into a gas phase reactor, and ethylene is introduced. By controlling the ethylene molar content to 15%, the ethylene / (ethylene + propylene) molar ratio to 0.35, and the hydrogen / ethylene molar ratio to 0.030, high-impact polypropylene powder is obtained.

[0027] Add compound additives (antioxidant 1010, antioxidant 168, and calcium stearate in a mass ratio of 1:2:1, with the total amount of compound additives being 0.15% of the mass of the high-impact polypropylene powder) to the obtained high-impact polypropylene powder. After mixing evenly, granulation and extrusion are used to produce high-flow, high-impact polypropylene material. The properties are shown in the table below.

[0028] Example 2

[0029] Propylene and hydrogen were used as raw materials and added to a loop reactor. Ziegler-Natta catalyst was added to the first loop reactor. The hydrogen addition rate to the loop reactor was controlled at 5000 ppm and the slurry density at 490 kg / m³. 3 Homopolymer polypropylene powder with a melt index of 30 g / 10 min was obtained by circulating the material through two loop reactors in series.

[0030] Homopolymer polypropylene powder is fed into a gas phase reactor, ethylene is introduced, and high-impact polypropylene powder is obtained by controlling the ethylene molar content to 15%, the ethylene / (ethylene + propylene) molar ratio to 0.33, and the hydrogen / ethylene molar ratio to 0.035.

[0031] Add compound additives (antioxidant 1010, antioxidant 168, and calcium stearate in a mass ratio of 1:2:1, with the total amount of compound additives being 0.1% of the mass of the high-impact polypropylene powder) to the obtained high-impact polypropylene powder. After mixing evenly, granulation and extrusion are used to produce high-flow, high-impact polypropylene material. The properties are shown in the table below.

[0032] Example 3

[0033] Propylene and hydrogen were used as raw materials and added to a loop reactor. Ziegler-Natta catalyst was added to the first loop reactor. The hydrogen addition rate to the loop reactor was controlled at 6000 ppm and the slurry density at 495 kg / m³. 3 Homopolymer polypropylene powder with a melt index of 32 g / 10 min was obtained by circulating the material through two loop reactors in series.

[0034] Homopolymer polypropylene powder is fed into a gas phase reactor, ethylene is introduced, and high-impact polypropylene powder is obtained by controlling the ethylene molar content to 15%, the ethylene / (ethylene + propylene) molar ratio to 0.32, and the hydrogen / ethylene molar ratio to 0.040.

[0035] Add compound additives (antioxidant 1010, antioxidant 168, and calcium stearate in a mass ratio of 1:2:1, with the total amount of compound additives being 0.3% of the mass of the high-impact polypropylene powder) to the obtained high-impact polypropylene powder. After mixing evenly, granulation and extrusion are performed to produce high-flow, high-impact polypropylene material. The properties are shown in the table below.

[0036] Example 4

[0037] Propylene and hydrogen were used as raw materials and added to a loop reactor. Ziegler-Natta catalyst was added to the first loop reactor. The hydrogen addition rate to the loop reactor was controlled at 6000 ppm and the slurry density at 490 kg / m³. 3 Homopolymer polypropylene powder with a melt index of 33 g / 10 min was obtained by circulating the material through two loop reactors in series.

[0038] Homopolymer polypropylene powder is fed into a gas phase reactor, ethylene is introduced, and high-impact polypropylene powder is obtained by controlling the ethylene molar content to 16%, the ethylene / (ethylene + propylene) molar ratio to 0.33, and the hydrogen / ethylene molar ratio to 0.045.

[0039] Add compound additives (antioxidant 1010, antioxidant 168, and calcium stearate in a mass ratio of 1:2:1, with the total amount of compound additives being 0.2% of the mass of the high-impact polypropylene powder) to the obtained high-impact polypropylene powder. After mixing evenly, granulation and extrusion are used to produce high-flow, high-impact polypropylene material. The properties are shown in the table below.

[0040] Example 5

[0041] Propylene and hydrogen were used as raw materials and added to a loop reactor. Ziegler-Natta catalyst was added to the first loop reactor. The hydrogen addition rate to the loop reactor was controlled at 5000 ppm and the slurry density at 495 kg / m³. 3 Homopolymer polypropylene powder with a melt index of 31 g / 10 min was obtained by circulating the material through two loop reactors in series.

[0042] Homopolymer polypropylene powder is fed into a gas phase reactor, ethylene is introduced, and high-impact polypropylene powder is obtained by controlling the ethylene molar content to 15%, the ethylene / (ethylene + propylene) molar ratio to 0.32, and the hydrogen / ethylene molar ratio to 0.040.

[0043] Add compound additives (antioxidant 1010, antioxidant 168, and calcium stearate in a mass ratio of 1:2:1, with the total amount of compound additives being 0.3% of the mass of the high-impact polypropylene powder) to the obtained high-impact polypropylene powder. After mixing evenly, granulation and extrusion are performed to produce high-flow, high-impact polypropylene material. The properties are shown in the table below.

[0044] Comparative Example

[0045] The implementation conditions are the same as those in Examples 1-5, with the only difference being the following parameters:

[0046] Propylene and hydrogen were used as raw materials and added to a loop reactor. Ziegler-Natta catalyst was added to the first loop reactor. The hydrogen addition rate to the loop reactor was controlled at 3000 ppm and the slurry density at 470 kg / m³.3 Homopolymer polypropylene powder with a melt index of 20 g / 10 min was obtained by circulating the material through two loop reactors in series.

[0047] Homopolymer polypropylene powder is fed into a gas phase reactor, ethylene is introduced, and polypropylene powder is obtained by controlling the ethylene molar content to 13%, the ethylene / (ethylene + propylene) molar ratio to 0.38, and the hydrogen / ethylene molar ratio to 0.040.

[0048] Add compounding agents (antioxidant 1010, antioxidant 168, and calcium stearate in a mass ratio of 1:2:1, with the total amount of compounding agents being 0.15% of the mass of the polypropylene powder) to the obtained polypropylene powder. After mixing evenly, granulation and extrusion are used to produce high-flow, high-impact polypropylene material. The properties are shown in Table 1 below.

[0049] Table 1 Test Results

[0050]

[0051] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A process for the preparation of a high flow high impact polypropylene, characterized in that, The preparation method comprises the following steps: S1: taking propylene and hydrogen as raw materials, adding them into a loop reactor, adding a Ziegler Natta catalyst into the first loop reactor, controlling the hydrogen addition amount of the two loop reactors to be 4500-6500 ppm, the slurry density to be 490-495 kg / m 3 , adjusting the temperature of the two loop reactors to be 67-71 ℃, the pressure to be 3.8-4.0 MPa, and circulating through the two loop reactors in series to obtain a homopolypropylene powder with a melt index of 25-40 g / 10 min; S2: delivering the homopolymer polypropylene powder into the gas phase reactor, feeding ethylene, propylene and hydrogen, and adjusting the molar content of ethylene to 12-16%, the molar ratio of ethylene / (ethylene+propylene) to 0.25-0.40, and the molar ratio of hydrogen / ethylene to 0.030-0.060 to obtain high-impact copolymer polypropylene powder; S3: adding compounded additives into the obtained high-impact polypropylene powder, uniformly mixing, and then granulating and extruding to produce high-flow high-impact polypropylene material.

2. Process for the preparation of a high flow high impact polypropylene according to claim 1, characterized in that, The compounded additives comprise antioxidants and acid absorbents, and the adding amount of the compounded additives is 0.1-0.3% of the mass of the high-impact polypropylene powder.

3. Process for the preparation of a high flow high impact polypropylene according to claim 2, characterized in that, The mass ratio of the antioxidants to the acid absorbents is 3:1-2:

1.

4. The process for the preparation of a high flow high impact polypropylene according to claim 3, characterized in that, The antioxidants are 1010 and 168, and the mass ratio is 1:

2.

5. The process for the preparation of a high flow high impact polypropylene according to claim 4, characterized in that, The acid absorbent is calcium stearate.

6. A high flow high impact polypropylene characterized in that, The preparation method is prepared by any one of claims 1-5.

7. The high flow high impact polypropylene according to claim 6, characterized in that The high-flow high-impact polypropylene has a melt flow rate of 30.00±10 g / 10 min under a 2.16 Kg load.

8. The high flow high impact polypropylene according to claim 7, characterized in that, The high flow high impact polypropylene has an impact strength > 30 KJ / m 2 .

9. The high flow high impact polypropylene according to claim 8, characterized in that, The high-flow high-impact polypropylene has a flexural modulus of ≥800 MPa.

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