High-flowability and high-impact polypropylene material based on annular pipe process and preparation method of high-flowability and high-impact polypropylene material

Abstract

The invention provides a high-flowability and high-impact polypropylene material based on a loop pipe process and a preparation method thereof, the preparation method comprises multiple steps of catalyst preparation, prepolymerization, loop pipe polymerization, gas phase polymerization, deactivation treatment and granulation, the process is simple, the cost is low, existing loop pipe process equipment is utilized, additional investment is not needed, and industrial production is easy to realize. The prepared polypropylene material product is excellent in performance, high-flowability and high-impact polypropylene is produced by optimizing a catalyst system, polymerization process parameters and an additive formula and adopting a hydrogen regulation method, the flowability and impact resistance of the polypropylene material can be effectively improved, and application requirements in different fields are met.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer material preparation, and particularly relates to a high-flow, high-impact polypropylene material based on a loop tube process and a preparation method thereof. Background Art

[0002] Polypropylene (PP) is an important thermoplastic resin with advantages such as low density, excellent mechanical properties, strong chemical resistance, and easy processing and molding. It is widely used in many fields, including automobiles, home appliances, packaging, and construction. For example, in automotive interiors, polypropylene is used to manufacture instrument panels and door trim panels; in the packaging field, it is used to produce various plastic films and woven bags.

[0003] Traditional polypropylene materials often struggle to simultaneously meet the requirements for high flow and high impact resistance. Generally speaking, increasing the flowability of polypropylene may lead to a decrease in its impact resistance, while increasing impact resistance may worsen its flowability. Earlier attempts to increase flowability through the addition of plasticizers reduced the mechanical properties of the material, especially its impact resistance. Furthermore, plasticizers may migrate and precipitate, affecting the performance and appearance of the finished product. While rubber toughening can improve impact resistance, it can also affect the material's rigidity and processing fluidity. Furthermore, compatibility issues between rubber and polypropylene can also affect the material's overall performance. Simply changing the processing technology to improve flowability and impact resistance has limited effectiveness and is unable to meet increasingly demanding performance requirements and production demands.

[0004] In modern industrial production, the increasing complexity and size of plastic products place higher demands on the processing fluidity of polypropylene materials. Good fluidity helps polypropylene fill mold cavities more smoothly during processes like injection molding, reducing molding defects such as short shots and weld marks, thereby improving production efficiency and product quality. High-flow polypropylene can better meet the demands of production schedules. Furthermore, in actual use, many polypropylene products, such as automotive bumpers and turnover boxes, need to withstand certain impact loads. Traditional polypropylene has limited impact resistance and is prone to cracking or damage when impacted, impacting the product's lifespan and safety. Improving the impact resistance of polypropylene can enhance the reliability and stability of products under various harsh operating conditions.

[0005] It is based on the above background that researchers have been continuously exploring and researching the preparation methods of high-flow, high-impact polypropylene materials to overcome the shortcomings of existing technologies and meet the high-performance requirements of polypropylene materials in different fields.

[0006] Chinese patent application CN119264567 A discloses a polypropylene composite material with high fluidity and high impact resistance, as well as its preparation method and application. The polypropylene composite material is prepared using a degradation method, and the raw materials used include 98.7-99.85 wt% polypropylene resin base material, 0.05-0.3 wt% anti-impact modifier DeltaMax 5000a, and 0.1-1 wt% free radical initiator. The prepared polypropylene composite material with high fluidity and high impact resistance is prepared by modifying the polypropylene resin base material with the toughening agent DeltaMax 5000a in combination with a degradation agent. It exhibits both excellent fluidity and impact resistance, meeting the high drop resistance and processing fluidity requirements of plastic parts for automobiles, home appliances, and other applications. The preparation method is simple and easy to operate, with low cost, and is easily promoted and used on a large scale.

[0007] However, existing technologies can only produce high-flow, high-impact polypropylene products using degradation methods using organic peroxide initiators. While the flowability of impact-resistant polypropylene produced by this degradation method meets user processing requirements, its impact performance is significantly reduced, failing to meet customer needs. This has become a major problem for raw material manufacturers. Summary of the Invention

[0008] (1) Technical issues to be resolved

[0009] The present invention provides a high-flow, high-impact polypropylene material based on a loop tube process and a preparation method thereof, in order to solve the technical problem of how to improve the fluidity and impact resistance of polypropylene.

[0010] (2) Technical solution

[0011] In order to solve the above technical problems, the present invention proposes a method for preparing a high-flow, high-impact polypropylene material based on a loop tube process, the preparation method comprising the following steps:

[0012] S1. Catalyst preparation: A Ziegler-Natta catalyst, an external electron donor, and an internal electron donor are mixed to prepare a catalyst system;

[0013] S2 prepolymerization: propylene monomer, a catalyst system and hydrogen are added to a prepolymerization reactor, and a prepolymerization reaction is carried out at low temperature and low pressure to generate a prepolymer;

[0014] S3 loop polymerization: The prepolymer, propylene monomer, hydrogen and a catalyst system are added to a loop reactor, and the loop polymerization reaction is carried out under heating and pressure conditions to generate homopolymer polypropylene powder;

[0015] S4 gas phase polymerization: homopolymer polypropylene powder, propylene monomer and ethylene are added to a gas phase reactor, and gas phase polymerization is carried out under heating and pressure conditions to generate copolymer polypropylene powder;

[0016] S5. Deactivation treatment: Deactivation treatment of the copolymerized polypropylene powder after gas phase polymerization to remove residual catalyst and monomer;

[0017] S6. Granulation: The deactivated copolymerized polypropylene powder is mixed with additives and granulated by extrusion to obtain a high-flow, high-impact polypropylene material.

[0018] Furthermore, in step S1, the Ziegler-Natta catalyst is a titanium-based catalyst, the external electron donor is an organosilicon compound, and the internal electron donor is an aromatic carboxylic acid ester.

[0019] Furthermore, in step S1, the Ziegler-Natta catalyst is a titanium-based catalyst, the external electron donor is diphenyldimethoxysilane, and the internal electron donor is diisobutyl phthalate.

[0020] Furthermore, in step S2, the temperature of the prepolymerization reaction is 0-20°C, and the pressure is 2.0-4.0 MPa.

[0021] Furthermore, in step S2, the degree of polymerization of the prepolymer is 100-500.

[0022] Furthermore, in step S3, the loop polymerization reaction is carried out in the loop reactor at a temperature of 60 to 80° C., a pressure of 2.0 to 4.0 MPa, and a hydrogen concentration of 0.1 to 0.5 mol%.

[0023] Furthermore, in step S4, the amount of ethylene used is 1 to 15 wt%.

[0024] Furthermore, in step S4, the additives include an antioxidant, a lubricant and a nucleating agent.

[0025] Furthermore, in step S4, the antioxidant is antioxidant 1010 or antioxidant 168; the lubricant is calcium stearate; and the nucleating agent is a sorbitol nucleating agent.

[0026] In addition, the present invention also proposes a high-flow, high-impact polypropylene material, which is prepared by the above method. The melt flow rate of the high-flow, high-impact polypropylene material is 30±5g / 10min, and the room temperature simple supported beam notched impact strength is ≥30kJ / m 2 , flexural modulus ≥750MPa.

[0027] (3) Beneficial effects

[0028] The present invention proposes a high-flow, high-impact polypropylene material based on a loop process and a method for preparing the same. The method comprises multiple steps: catalyst preparation, prepolymerization, loop polymerization, gas-phase polymerization, deactivation, and granulation. The process is simple and cost-effective, utilizing existing loop process equipment without the need for additional investment, making industrial production easy. The resulting polypropylene material exhibits excellent product performance. By optimizing the catalyst system, polymerization process parameters, and additive formulation, and employing a hydrogenation method to produce high-flow, high-impact polypropylene, the material's fluidity and impact resistance are effectively enhanced, meeting the application needs of diverse fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The present invention is a flow chart of the method for preparing high-flow, high-impact polypropylene materials based on the loop tube process. DETAILED DESCRIPTION

[0030] In order to make the purpose, content and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below with reference to the accompanying drawings and examples.

[0031] Example 1

[0032] This embodiment proposes a method for preparing a high-flow, high-impact polypropylene material based on a loop tube process, and the process is as follows: Figure 1 As shown, the specific steps include:

[0033] S1. Catalyst preparation: A titanium-based catalyst, diphenyldimethoxysilane, and diisobutyl phthalate were mixed in a certain ratio (1:2:1) to prepare a catalyst system.

[0034] S2. Prepolymerization: Propylene monomer and catalyst system are added to a prepolymerization reactor, and a prepolymerization reaction is carried out at 10°C and 4.0 MPa to generate a prepolymer having a degree of polymerization of 400.

[0035] S3. Loop polymerization: The prepolymer, propylene monomer, hydrogen and catalyst system are added to a loop reactor and a loop polymerization reaction is carried out at 68°C and 4.0 MPa to produce homopolymerized polypropylene powder. The hydrogen concentration is 0.3 mol%.

[0036] S4. Gas phase polymerization: Homopolymer polypropylene powder, propylene monomer and ethylene are added to a gas phase reactor and subjected to gas phase polymerization at 75°C and 1.3 MPa to generate copolymer polypropylene powder. The amount of ethylene used is 15.0 wt%.

[0037] S5. Deactivation treatment: Deactivate the copolymerized polypropylene powder after the polymerization reaction to remove residual catalyst and monomer.

[0038] S6. Granulation: The deactivated copolymerized polypropylene powder is mixed with 0.2 wt% of antioxidant 1010, 0.1 wt% of calcium stearate, and 0.3 wt% of a sorbitol nucleating agent, and granulated by extrusion to obtain a high-flow, high-impact polypropylene material.

[0039] Example 2

[0040] S1. Catalyst preparation: A titanium-based catalyst, diphenyldimethoxysilane, and diisobutyl phthalate are mixed in a certain proportion to prepare a catalyst system.

[0041] S2. Prepolymerization: Propylene monomer and catalyst system are added to a prepolymerization reactor, and a prepolymerization reaction is carried out at 10°C and 3.9 MPa to generate a prepolymer having a degree of polymerization of 300.

[0042] S3. Loop polymerization: The prepolymer, propylene monomer, hydrogen and catalyst system are added to a loop reactor and a loop polymerization reaction is carried out at 68°C and 3.9 MPa to produce homopolymerized polypropylene powder. The hydrogen concentration is 0.3 mol%.

[0043] S4. Gas phase polymerization: Homopolymer polypropylene powder, propylene monomer and ethylene are added to a gas phase reactor and subjected to gas phase polymerization at 75°C and 1.3 MPa to generate copolymer polypropylene powder. The amount of ethylene used is 14.0 wt%.

[0044] S5. Deactivation treatment: Deactivate the copolymerized polypropylene powder after the polymerization reaction to remove residual catalyst and monomer.

[0045] S6. Granulation: The deactivated copolymerized polypropylene powder is mixed with 0.2 wt% of antioxidant 1010, 0.1 wt% of calcium stearate, and 0.3 wt% of a sorbitol nucleating agent, and granulated by extrusion to obtain a high-flow, high-impact polypropylene material.

[0046] Example 3

[0047] S1. Catalyst preparation: A titanium-based catalyst, diphenyldimethoxysilane, and diisobutyl phthalate are mixed in a certain proportion to prepare a catalyst system.

[0048] S2. Prepolymerization: Propylene monomer and catalyst system are added to a prepolymerization reactor, and a prepolymerization reaction is carried out at 10°C and 3.9 MPa to generate a prepolymer having a degree of polymerization of 300.

[0049] S3. Loop polymerization: The prepolymer, propylene monomer, hydrogen and catalyst system are added to a loop reactor and a loop polymerization reaction is carried out at 68°C and 3.9 MPa to produce homopolymerized polypropylene powder. The hydrogen concentration is 0.4 mol%.

[0050] S4. Gas phase polymerization: Homopolymer polypropylene powder, propylene monomer and ethylene are added to a gas phase reactor and subjected to gas phase polymerization at 75°C and 1.3 MPa to generate copolymer polypropylene powder. The amount of ethylene used is 14.0 wt%.

[0051] S5. Deactivation treatment: Deactivate the copolymerized polypropylene powder after the polymerization reaction to remove residual catalyst and monomer.

[0052] S6. Granulation: The deactivated copolymerized polypropylene powder is mixed with 0.3 wt% of antioxidant 1010, 0.2 wt% of calcium stearate, and 0.4 wt% of a sorbitol nucleating agent, and granulated by extrusion to obtain a high-flow, high-impact polypropylene material.

[0053] Example 4

[0054] S1. Catalyst preparation: A titanium-based catalyst, dicyclopentyldimethoxysilane, and diisobutyl phthalate are mixed in a certain proportion to prepare a catalyst system.

[0055] S2. Prepolymerization: Propylene monomer and catalyst system are added to a prepolymerization reactor, and a prepolymerization reaction is carried out at 10°C and 4.0 MPa to generate a prepolymer having a degree of polymerization of 400.

[0056] S3. Loop polymerization: The prepolymer, propylene monomer, hydrogen and catalyst system were added to the loop reactor and polymerization was carried out at 68°C and 4.0 MPa to produce polypropylene powder. The hydrogen concentration was 0.4 mol%.

[0057] S4. Gas phase polymerization: Homopolymer polypropylene powder, propylene monomer and ethylene are added to a gas phase reactor and subjected to gas phase polymerization at 75°C and 1.3 MPa to generate copolymer polypropylene powder. The amount of ethylene used is 15.0 wt%.

[0058] S5. Deactivation treatment: Deactivate the copolymerized polypropylene powder after the polymerization reaction to remove residual catalyst and monomer.

[0059] S6 granulation: The deactivated copolymer polypropylene powder was mixed with 0.3wt% of antioxidant 168, 0.2wt% of calcium stearate and 0.4wt% of a sorbitol nucleating agent and extruded and granulated to obtain a high flow, high impact polypropylene material.

[0060] The properties of the high flow, high impact polypropylene materials prepared in Examples 1 to 4 are shown in the table below.

[0061] Table 1 Performance test results of Examples 1 to 4

[0062]

[0063] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing high-flow, high-impact polypropylene material based on a loop tube process, characterized in that: The preparation method comprises the following steps: S1. Catalyst preparation: A Ziegler-Natta catalyst, an external electron donor, and an internal electron donor are mixed to prepare a catalyst system; S2 prepolymerization: propylene monomer, a catalyst system and hydrogen are added to a prepolymerization reactor, and a prepolymerization reaction is carried out at low temperature and low pressure to generate a prepolymer; S3 loop polymerization: The prepolymer, propylene monomer, hydrogen and a catalyst system are added to a loop reactor, and the loop polymerization reaction is carried out under heating and pressure conditions to generate homopolymer polypropylene powder; S4 gas phase polymerization: homopolymer polypropylene powder, propylene monomer and ethylene are added to a gas phase reactor, and gas phase polymerization is carried out under heating and pressure conditions to generate copolymer polypropylene powder; S5. Deactivation treatment: Deactivation treatment of the copolymerized polypropylene powder after gas phase polymerization to remove residual catalyst and monomer; S6. Granulation: The deactivated copolymerized polypropylene powder is mixed with additives and granulated by extrusion to obtain a high-flow, high-impact polypropylene material.

2. The method for preparing high-flow, high-impact polypropylene material based on the loop tube process according to claim 1, characterized in that: In step S1, the Ziegler-Natta catalyst is a titanium-based catalyst, the external electron donor is an organosilicon compound, and the internal electron donor is an aromatic carboxylic acid ester.

3. The method for preparing high-flow, high-impact polypropylene material based on the loop tube process according to claim 2, characterized in that: In step S1, the Ziegler-Natta catalyst is a titanium-based catalyst, the external electron donor is diphenyldimethoxysilane, and the internal electron donor is diisobutyl phthalate.

4. The method for preparing high-flow, high-impact polypropylene material based on the loop tube process according to claim 1, characterized in that: In step S2, the temperature of the prepolymerization reaction is 0-20°C and the pressure is 2.0-4.0 MPa.

5. The method for preparing high-flow, high-impact polypropylene material based on the loop tube process according to claim 1, characterized in that: In step S2, the degree of polymerization of the prepolymer is 100-500.

6. The method for preparing high-flow, high-impact polypropylene material based on the loop process according to claim 1, characterized in that: In step S3, the loop polymerization reaction is carried out in the loop reactor at a temperature of 60 to 80° C., a pressure of 2.0 to 4.0 MPa, and a hydrogen concentration of 0.1 to 0.5 mol%.

7. The method for preparing high-flow, high-impact polypropylene material based on the loop process according to claim 1, characterized in that: In step S4, the amount of ethylene used is 1 to 15 wt%.

8. The method for preparing high-flow, high-impact polypropylene material based on the loop tube process according to claim 1, characterized in that: In step S4, the additives include an antioxidant, a lubricant, and a nucleating agent.

9. The method for preparing a high-flow, high-impact polypropylene material based on a loop tube process according to claim 8, characterized in that: In step S4, the antioxidant is antioxidant 1010 or antioxidant 168; the lubricant is calcium stearate; and the nucleating agent is a sorbitol nucleating agent.

10. A high-flow, high-impact polypropylene material, characterized in that: The high-flow, high-impact polypropylene material is prepared by the method according to any one of claims 1 to 8, and the melt flow rate of the high-flow, high-impact polypropylene material is 30±5g / 10min, and the room temperature simple supported beam notched impact strength is ≥30kJ / m 2 , flexural modulus ≥750MPa.

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