Low-temperature-impact-resistant polypropylene composition and preparation method thereof

Abstract

The invention discloses a low-temperature-impact-resistant polypropylene composition and a preparation method thereof. The low-temperature-impact-resistant polypropylene composition is prepared from the following components in parts by weight: 1000 parts of polypropylene, 12-25 parts of vinyl-terminated hyperbranched polyester, 5-30 parts of an ethylene-vinyl acetate copolymer and 1-15 parts of an antioxidant. The vinyl-terminated hyperbranched polyester is compact in molecular structure and less in intermolecular chain entanglement, and has a spatial three-dimensional structure similar to a sphere. The inner surface and the outer surface of the three-dimensional space contain a large amount of vinyl-terminated groups. When the polypropylene composition is subjected to melt extrusion, the ethylene-vinyl acetate copolymer occupies a three-dimensional internal space to form a space structure similar to a'core-shell '. When the composition is subjected to external impact at low temperature, the core-shell space structure still keeps good flexibility, so that the composition has excellent low-temperature impact resistance.

Description

Technical Field

[0001] The invention relates to the field of polymer material modification, and in particular to a polypropylene composition with excellent low-temperature impact resistance and a preparation method thereof. Background Art

[0002] Polypropylene is abbreviated as PP. It is a polymer formed by the addition polymerization of propylene. It is a white waxy material with a transparent and light appearance. Polypropylene is a thermoplastic synthetic resin with excellent performance. It is a colorless, translucent, thermoplastic, lightweight general-purpose plastic with chemical resistance, heat resistance, electrical insulation, high-strength mechanical properties and good high-wear processing performance. It is currently widely used in fiber products such as clothing and blankets, as well as medical equipment, automobiles, bicycles, parts, pipelines, chemical containers, food, pharmaceutical packaging, home appliances, electronic and electrical fields.

[0003] my country's automobile, electrical appliance and other industries are developing rapidly, especially the production and sales of cars and home appliances have maintained a high growth rate. China has become a global important consumer market for automobiles and home appliances. Under the premise of safety assurance, lightweight and plastic integration are the development trend. Polypropylene has abundant sources of raw materials, simple synthesis process and modern large-scale production, lower density than metal, and good strength and processing performance. Therefore, polypropylene materials account for more than 40% of automotive plastics, and the total consumption has reached 500,000 tons. Among them, more than 80% of polypropylene materials are suitable for the production of automobile bumpers, automobile dashboards, automobile door panels and other parts. However, the temperature in the north in winter is often minus ten degrees or even minus dozens of degrees. The impact strength of automobile parts such as bumpers and home appliance shells made of polypropylene materials will drop significantly at low temperatures. Summary of the invention

[0004] The purpose of the present invention is to overcome the above-mentioned defects and provide a polypropylene composition with excellent low-temperature impact resistance and a preparation method thereof.

[0005] The technical solution of the present invention is as follows:

[0006] A low-temperature impact-resistant polypropylene composition is prepared from the following components in parts by weight:

[0007]

[0008] The melting index of the polypropylene under the conditions of 230°C / 2.16Kg is 20-60g / 10min.

[0009] The terminal vinyl hyperbranched polyester is liquid, has a vinyl number of 4-8 mol / mol, and a number average molecular weight of 400-1800 g / mol.

[0010] The melt index of the ethylene-vinyl acetate copolymer is 2-40 g / 10 min at 190° C. / 2.16 kg.

[0011] The ethylene-vinyl acetate copolymer is a homopolymer in the form of white powder.

[0012] The antioxidant is selected from at least one of hindered amine antioxidants, hindered phenol antioxidants, thio antioxidants and phosphite antioxidants.

[0013] Furthermore, the antioxidant is preferably at least one of antioxidant 1010, antioxidant 1076, antioxidant 1098 or antioxidant 168.

[0014] A method for preparing a polypropylene composition having excellent low-temperature impact resistance comprises the following steps:

[0015] (1) spraying 12-25 parts of the vinyl-terminated hyperbranched polyester uniformly on the surface of 5-30 parts of ethylene-vinyl acetate copolymer;

[0016] (2) adding the above mixture, 1000 parts of polypropylene and 1-15 parts of antioxidant into a high-speed mixer and mixing them uniformly at room temperature; then adding the uniformly mixed materials into a twin-screw extruder for mixing and extrusion to obtain a polypropylene composition with excellent low-temperature impact resistance;

[0017] In a further embodiment, the temperature of the twin-screw extruder from the feeding section to the die is 100-130°C, 170-190°C, 180-200°C, 190-210°C, 200-220°C, 210-225°C, and 210-225°C, respectively.

[0018] Beneficial effects:

[0019] The terminal vinyl hyperbranched polyester has a compact molecular structure, less intermolecular chain entanglement, and has a spherical three-dimensional spatial structure. The inner and outer surfaces of the three-dimensional space contain a large number of terminal vinyl groups. When the polypropylene composition is melt-extruded, the ethylene-vinyl acetate copolymer will occupy the three-dimensional internal space to form a spatial structure similar to a "core-shell". When the composition is impacted by the outside world at low temperatures, this "core-shell" spatial structure will still maintain good flexibility, thereby having excellent low-temperature impact resistance.

[0020] The purpose of uniformly spraying the terminal vinyl hyperbranched polyester on the surface of the ethylene-vinyl acetate copolymer is to enable the two to be mixed more quickly and uniformly during melt extrusion, and finally to be uniformly dispersed in the polypropylene matrix, thereby improving the impact resistance of the polypropylene. DETAILED DESCRIPTION

[0021] If not specifically stated, the various raw materials of the present invention can be obtained commercially or prepared according to conventional methods in the art. Unless otherwise defined or stated, all professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any method and material similar or equivalent to the described content can be applied to the method of the present invention. Other aspects of the present invention are obvious to those skilled in the art due to the disclosure of this article. The present invention is 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.

[0022] The materials used in the embodiments and comparative examples are as follows. It should be noted that the following are for illustrative purposes only, and the same products produced by other manufacturers are also suitable for the technology of this application.

[0023] The polypropylene grade is PP 48M40, the melt index at 230°C / 2.16Kg is 15g / 10min, and the supplier is SABIC.

[0024] The vinyl number of the terminal vinyl hyperbranched polyester is 6 mol / mol, the number average molecular weight is 1200 g / mol, and the supplier is Shanghai Ziyi Reagent Factory.

[0025] The melt index of the ethylene-vinyl acetate copolymer under the conditions of 190°C / 2.16Kg is 8g / 10min, Shanghai Kaiyin Chemical Co., Ltd.

[0026] The antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1, and the supplier is DuPont Company of the United States.

[0027] Example 1

[0028] (1) spraying 15 parts of vinyl-terminated hyperbranched polyester uniformly on the surface of 6 parts of ethylene-vinyl acetate copolymer;

[0029] (2) adding the above mixture, 1000 parts of polypropylene and 3 parts of antioxidant into a high-speed mixer and mixing them uniformly at room temperature; then adding the uniformly mixed materials into a twin-screw extruder for mixing and extrusion to obtain a polypropylene composition with excellent low-temperature impact resistance;

[0030] The temperatures of the twin-screw extruder from the feeding section to the die are 120°C, 180°C, 190°C, 200°C, 210°C, 220°C, and 225°C, respectively.

[0031] Example 2

[0032] (1) spraying 15 parts of vinyl-terminated hyperbranched polyester uniformly on the surface of 15 parts of ethylene-vinyl acetate copolymer;

[0033] (2) adding the above mixture, 1000 parts of polypropylene and 3 parts of antioxidant into a high-speed mixer and mixing them uniformly at room temperature; then adding the uniformly mixed materials into a twin-screw extruder for mixing and extrusion to obtain a polypropylene composition with excellent low-temperature impact resistance;

[0034] The temperatures of the twin-screw extruder from the feeding section to the die are 120°C, 180°C, 190°C, 200°C, 210°C, 220°C, and 225°C, respectively.

[0035] Example 3

[0036] (1) 18 parts of vinyl-terminated hyperbranched polyester are uniformly sprayed on the surface of 8 parts of ethylene-vinyl acetate copolymer.

[0037] (2) adding the above mixture, 1000 parts of polypropylene and 5 parts of antioxidant into a high-speed mixer and mixing them uniformly at room temperature; then adding the uniformly mixed materials into a twin-screw extruder for mixing and extrusion to obtain a polypropylene composition with excellent low-temperature impact resistance;

[0038] The temperatures of the twin-screw extruder from the feeding section to the die are 120°C, 180°C, 190°C, 200°C, 210°C, 220°C, and 225°C, respectively.

[0039] Example 4

[0040] (1) 18 parts of vinyl-terminated hyperbranched polyester are uniformly sprayed on the surface of 20 parts of ethylene-vinyl acetate copolymer.

[0041] (2) adding the above mixture, 1000 parts of polypropylene and 5 parts of antioxidant into a high-speed mixer and mixing them uniformly at room temperature; then adding the uniformly mixed materials into a twin-screw extruder for mixing and extrusion to obtain a polypropylene composition with excellent low-temperature impact resistance;

[0042] The temperatures of the twin-screw extruder from the feeding section to the die are 120°C, 180°C, 190°C, 200°C, 210°C, 220°C, and 225°C, respectively.

[0043] Example 5

[0044] (1) 22 parts of vinyl-terminated hyperbranched polyester are uniformly sprayed on the surface of 10 parts of ethylene-vinyl acetate copolymer.

[0045] (2) adding the above mixture, 1000 parts of polypropylene and 8 parts of antioxidant into a high-speed mixer and mixing them uniformly at room temperature; then adding the uniformly mixed materials into a twin-screw extruder for mixing and extrusion to obtain a polypropylene composition with excellent low-temperature impact resistance;

[0046] The temperatures of the twin-screw extruder from the feeding section to the die are 120°C, 180°C, 190°C, 200°C, 210°C, 220°C, and 225°C, respectively.

[0047] Example 6

[0048] (1) 22 parts of vinyl-terminated hyperbranched polyester are uniformly sprayed on the surface of 25 parts of ethylene-vinyl acetate copolymer.

[0049] (2) adding the above mixture, 1000 parts of polypropylene and 8 parts of antioxidant into a high-speed mixer and mixing them uniformly at room temperature; then adding the uniformly mixed materials into a twin-screw extruder for mixing and extrusion to obtain a polypropylene composition with excellent low-temperature impact resistance;

[0050] The temperatures of the twin-screw extruder from the feeding section to the die are 120°C, 180°C, 190°C, 200°C, 210°C, 220°C, and 225°C, respectively.

[0051] Comparative Example 1

[0052] 1000 parts of polypropylene and 8 parts of antioxidant are added into a high-speed mixer and mixed evenly at room temperature; then the evenly mixed materials are added into a twin-screw extruder for mixing and extrusion to obtain a polypropylene composition with excellent low-temperature impact resistance;

[0053] The temperatures of the twin-screw extruder from the feeding section to the die are 120°C, 180°C, 190°C, 200°C, 210°C, 220°C, and 225°C, respectively.

[0054] Comparative Example 2

[0055] 1000 parts of polypropylene, 47 parts of ethylene-vinyl acetate copolymer and 8 parts of antioxidant are added into a high-speed mixer and mixed evenly at room temperature; then the evenly mixed materials are added into a twin-screw extruder for mixing and extrusion to obtain a polypropylene composition with excellent low-temperature impact resistance;

[0056] The temperatures of the twin-screw extruder from the feeding section to the die are 120°C, 180°C, 190°C, 200°C, 210°C, 220°C, and 225°C, respectively.

[0057] Comparative Example 3

[0058] 1000 parts of polypropylene, 47 parts of terminal vinyl hyperbranched polyester and 8 parts of antioxidant are added into a high-speed mixer and mixed evenly at room temperature; then the evenly mixed materials are added into a twin-screw extruder for mixing and extrusion to obtain a polypropylene composition with excellent low-temperature impact resistance;

[0059] The temperatures of the twin-screw extruder from the feeding section to the die are 120°C, 180°C, 190°C, 200°C, 210°C, 220°C, and 225°C, respectively.

[0060] Comparative Example 4

[0061] 1000 parts of polypropylene, 47 parts of toughening agent POE and 8 parts of antioxidant are added into a high-speed mixer and mixed evenly at room temperature; then the evenly mixed materials are added into a twin-screw extruder for mixing and extrusion to obtain a polypropylene composition with excellent low-temperature impact resistance;

[0062] The temperatures of the twin-screw extruder from the feeding section to the die are 120°C, 180°C, 190°C, 200°C, 210°C, 220°C, and 225°C, respectively.

[0063] Comparative Example 5

[0064] 1000 parts of polypropylene, 47 parts of ethylene propylene diene monomer rubber (EPDM), and 8 parts of antioxidant are added into a high-speed mixer and mixed evenly at room temperature; then the evenly mixed materials are added into a twin-screw extruder for mixing and extrusion to obtain a polypropylene composition with excellent low-temperature impact resistance;

[0065] The temperatures of the twin-screw extruder from the feeding section to the die are 120°C, 180°C, 190°C, 200°C, 210°C, 220°C, and 225°C, respectively.

[0066] Comparative Example 6

[0067] 1000 parts of polypropylene, 22 parts of terminal vinyl hyperbranched polyester, 25 parts of toughening agent POE, and 8 parts of antioxidant are added to a high-speed mixer and mixed evenly at room temperature; then the evenly mixed materials are added to a twin-screw extruder for mixing and extrusion to obtain a polypropylene composition with excellent low-temperature impact resistance;

[0068] The temperatures of the twin-screw extruder from the feeding section to the die are 120°C, 180°C, 190°C, 200°C, 210°C, 220°C, and 225°C, respectively.

[0069] Comparative Example 7

[0070] 1000 parts of polypropylene, 22 parts of ethylene-vinyl acetate copolymer, 25 parts of toughening agent POE, and 8 parts of antioxidant are added to a high-speed mixer and mixed evenly at room temperature; then the evenly mixed materials are added to a twin-screw extruder for mixing and extrusion to obtain a polypropylene composition with excellent low-temperature impact resistance;

[0071] The temperatures of the twin-screw extruder from the feeding section to the die are 120°C, 180°C, 190°C, 200°C, 210°C, 220°C, and 225°C, respectively.

[0072] The composite materials prepared in the above-mentioned embodiments and comparative examples were injection molded into specimens according to ASTM standards, and the relevant properties were tested as shown in Table 1 below.

[0073] The dimensions of the splines (length × width × thickness) are: tensile spline (dumbbell shape), 170 mm × 13 mm × 3.2 mm; notched impact spline, 127 mm × 13 mm × 3.2 mm, V-notch, notch depth of 1 / 5.

[0074] Tensile strength: tested according to ASTM D638, tensile speed is 20mm / min.

[0075] Charpy notched impact strength: tested according to ASTM D6110.

[0076] Table 1

[0077]

[0078] In the present invention, the terminal vinyl hyperbranched polyester has a close molecular structure, less intermolecular chain entanglement, has a spherical three-dimensional structure, and the inner surface and outer surface of the three-dimensional space contain a large number of terminal vinyl groups. When the polypropylene composition is melt-extruded, the ethylene-vinyl acetate copolymer occupies the three-dimensional internal space to form a spatial structure similar to a "core-shell". When the composition is impacted by the outside world at low temperatures, this "core-shell" spatial structure still maintains good flexibility and has excellent low-temperature impact resistance.

[0079] Comparison of Example 6 with Comparative Examples 1-7 revealed that: no terminal vinyl hyperbranched polyester and ethylene-vinyl acetate copolymer were added to Comparative Example 1, no terminal vinyl hyperbranched polyester was added to Comparative Example 2, and no ethylene-vinyl acetate copolymer was added to Comparative Example 3, so the impact strength and low-temperature impact properties of the materials were very poor.

[0080] Although two common toughening agents were added in Comparative Examples 4 and 5, the impact strength and low-temperature impact strength of the materials were still much lower than those of Example 6.

[0081] In Comparative Example 6, terminal vinyl hyperbranched polyester and a toughening agent were added, and in Comparative Example 7, ethylene-vinyl acetate copolymer and a toughening agent were added, but there was no synergistic effect between them, resulting in poor low-temperature toughness of the materials.

[0082] The above description of the embodiments is to facilitate the understanding and application of the present invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the embodiments herein, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A low temperature impact resistant polypropylene composition, characterized in that: It is prepared from the following components by weight:

2. The polypropylene composition according to claim 1, characterized in that: The melting index of the polypropylene under the conditions of 230°C / 2.16Kg is 20-60g / 10min.

3. The polypropylene composition according to claim 1, characterized in that: The terminal vinyl hyperbranched polyester is liquid, wherein the vinyl number is 4-8 mol / mol and the number average molecular weight is 400-1800 g / mol.

4. The polypropylene composition according to claim 1, characterized in that: The melt index of the ethylene-vinyl acetate copolymer is 2-40 g / 10 min at 190° C. / 2.16 kg.

5. The polypropylene composition according to claim 1, characterized in that: The antioxidant is selected from at least one of hindered amine antioxidants, hindered phenol antioxidants, thio antioxidants and phosphite antioxidants.

6. The polypropylene composition according to claim 5, characterized in that: The antioxidant is at least one of antioxidant 1010, antioxidant 1076, antioxidant 1098 or antioxidant 168.

7. The method for preparing the polypropylene composition according to claim 1, characterized in that: The following steps are involved: (1) spraying 12-25 parts of the vinyl-terminated hyperbranched polyester uniformly on the surface of 5-30 parts of ethylene-vinyl acetate copolymer; (2) The above mixture, 1000 parts of polypropylene and 1-15 parts of antioxidant are added to a high-speed mixer and mixed uniformly at room temperature; then the uniformly mixed materials are added to a twin-screw extruder for mixing and extrusion to obtain a polypropylene composition resistant to low-temperature impact.

8. The preparation method according to claim 7, characterized in that: The temperatures of the twin-screw extruder from the feeding section to the die are 100-130°C, 170-190°C, 180-200°C, 190-210°C, 200-220°C, 210-225°C, and 210-225°C, respectively.

Images