Heat-resistant low-density high-rigidity-toughness balanced polypropylene material and preparation method thereof

Abstract

The invention discloses a heat-resistant low-density high-rigidity-toughness balance polypropylene material and a preparation method thereof. The composite material is prepared from the following raw materials in percentage by weight: 40-80% of homo-polypropylene I; 0-50% of second homo-polypropylene; 20 to 60% of impact-resistant co-polypropylene; 0.1-2% of a stabilizer; and 0-5% of other additives. Under the condition that other fillers and toughening agents are not added into the material, through blending of several kinds of polypropylene, the surface hardness of the material is improved, the toughness of the material is improved while the strength of a workpiece is improved, and the trend of high performance is met. In addition, due to the structure of the homo-polypropylene, the blending material introduced with the homo-polypropylene has higher thermal deformation temperature, and the application range of the product is expanded.

Description

Technical Field

[0001] The invention relates to a method for preparing a polypropylene material. The obtained material has the characteristics of low density, high hardness and high toughness, and belongs to the technical field of polymer material processing and modification. Background Art

[0002] At present, with the rapid development of my country's home appliance industry, people have put forward higher requirements for the energy saving, environmental protection and durability of home appliances. For the product shell, the combination of home appliance plastic materials with rubber, metal, etc. makes the design of home appliances more advanced, so the aesthetics and durability of home appliance plastics also need higher requirements. However, it is difficult for ordinary plastics to meet the requirements of high hardness and high toughness at the same time. They are easily damaged by external forces during use, affecting their aesthetics and normal use. Modified plastics filled with fillers such as talcum powder have a high density and are prone to pollution during the production process. They cannot well meet the needs of lightweight home appliances and are not in line with the development concept of green environmental protection.

[0003] Polypropylene has low density, chemical corrosion resistance, excellent mechanical properties, and excellent processing performance. It is widely used in electronic appliances, automobiles, and home appliances. It is the thermoplastic plastic with the largest consumption and fastest development speed among home appliance plastics. Homopolymer polypropylene has a high heat deformation temperature, high hardness, but large shrinkage rate, and insufficient toughness; impact copolymer polypropylene has good toughness, small dimensional deformation, but low hardness, and low heat deformation temperature. The performance of single polypropylene is gradually unable to meet the requirements of home appliance shells, so it is necessary to concentrate on blending and modifying different types of polypropylene. In order to improve the problems existing in single polypropylene materials, without adding fillers and toughening agents, and ensuring low cost and low density, several types of polypropylene are blended. While meeting the basic mechanical properties of the material, it not only ensures the rigidity and toughness balance of the material, but also expands its application range, and makes later recycling easier, which is in line with the direction of green environmental protection. Summary of the invention

[0004] The purpose of the present invention is to develop a heat-resistant, low-density, high-rigidity-toughness balanced polypropylene material. The obtained material can be applied to the housing of household appliances, has excellent mechanical properties, a high heat deformation temperature, does not add any filler, and the obtained product has a low density.

[0005] Another object of the present invention is to provide a method for preparing the polypropylene composite material.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A heat-resistant, low-density, high-rigidity-toughness balanced polypropylene material, composed of the following raw materials in percentage by weight:

[0008] Homopolymer polypropylene: 0-80%; impact-resistant copolymer polypropylene: 0-60%; high-impact block copolymer polypropylene; stabilizer: 0.1-2%; other additives: 0-5%.

[0009] The polypropylene described as homopolymer polypropylene has a melt flow rate of 0.5-15g / 10min.

[0010] The melt flow rate of the impact-resistant copolymer polypropylene is 1-30 g / 10 min.

[0011] The stabilizer is a primary antioxidant and a secondary antioxidant that are considered necessary by those skilled in the art, wherein the primary antioxidant is a hindered phenol or thioester antioxidant, and the secondary antioxidant is a phosphite or lipid antioxidant.

[0012] The other additives are one or a combination of anti-light additives, flame retardants, antistatic additives, surfactants, plasticizers, and antimicrobial additives that are considered necessary by those skilled in the art.

[0013] The preparation method of the above-mentioned low-density, high-rigidity and high-toughness polypropylene material comprises the following specific steps:

[0014] Homopolymer polypropylene, impact copolymer polypropylene, stabilizer and other additives are mixed evenly in a high-speed mixer according to the ratio, and then added to a twin-screw extruder from the main feed, and cooled and granulated after melt extrusion. The process is: the temperature of the first zone is 60-190°C, the temperature of the second to eighth zones is 190-240°C, the extrusion temperature is 230±10°C, and the main screw speed is 250-350r / min. After melt extrusion, cooling, granulation, and drying, a low-density, high-rigidity and high-toughness polypropylene material is obtained.

[0015] The advantages of the present invention are:

[0016] (1) Without introducing other fillers, blending several polypropylenes not only improves the surface hardness of the material and the toughness of the parts, but also does not change the density of the material, maintaining the advantage of low density of polypropylene materials, which is in line with the trend of lightweight materials.

[0017] (2) Due to the cross-linked structure of several polypropylenes and the higher heat deformation temperature of homopolymer polypropylene, the resulting material has a wider operating temperature range. In addition, the rubber phase in the copolymer polypropylene optimizes the situation where the shrinkage rate of different parts of the single homopolymer polypropylene material is inconsistent due to orientation, thereby improving the dimensional stability of the finished product. DETAILED DESCRIPTION

[0018] The following is a further detailed description of the embodiments of the present invention by way of examples and comparative examples, but the present invention is not limited to the scope of the embodiments.

[0019] In the composite material formulations of the comparative examples and the embodiments, the melt flow rate of the homopolypropylene 1 used is about 0.3 g / 10 min, the melt flow rate of the homopolypropylene 2 is about 3 g / 10 min, and the melt flow rate of the impact copolymer polypropylene is about 2.5 g / 10 min.

[0020] The stabilizers used are provided by SONGWON of South Korea, and are DSTDP (chemical name: distearyl thiodipropionate), 1010 (chemical name: pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) and 1680 (chemical name: tris(2,4-di-tert-butylphenyl) phosphite). Other additives used mainly refer to color components, light stabilizers, etc.

[0021] Comparative Example 1

[0022] Homopolymer polypropylene 98.5%, stabilizer 0.5%, other additives 1% are weighed by weight percentage, placed in a high-speed mixer and mixed evenly, then added from the main feeding port of a twin-screw extruder, and cooled and granulated after melt extrusion to prepare a PP composite material. The process is: zone one temperature 60-190°C, zone two to eight temperature 190-240°C, extrusion temperature 230±10°C; main screw speed 250-350r / min.

[0023] Comparative Example 2

[0024] 98.5% of homopolymer polypropylene, 0.5% of stabilizer and 1% of other additives are weighed by weight, placed in a high-speed mixer and mixed evenly, then added from the main feeding port of a twin-screw extruder, and cooled and granulated after melt extrusion to prepare a PP composite material. The process is: zone one temperature 60-190°C, zone two to eight temperature 190-240°C, extrusion temperature 230±10°C; main screw speed 250-350r / min.

[0025] Comparative Example 3

[0026] 98.5% of impact copolymer polypropylene, 0.5% of stabilizer and 1% of other additives are weighed by weight, placed in a high-speed mixer and mixed evenly, then added from the main feeding port of a twin-screw extruder, and cooled and granulated after melt extrusion to prepare a PP composite material. The process is as follows: temperature of zone 1 is 60-190°C, temperature of zones 2-8 is 190-240°C, extrusion temperature is 230±10°C; main screw speed is 250-350r / min.

[0027] Example 1

[0028] 49.5% of homopolymer polypropylene, 49% of impact copolymer polypropylene, 0.5% of stabilizer and 1% of other additives are weighed by weight, placed in a high-speed mixer and mixed evenly, then added from the main feeding port of a twin-screw extruder, and cooled and granulated after melt extrusion to prepare a low-density, high-rigidity and high-toughness polypropylene material. The process is as follows: temperature of zone 1 is 60-190°C, temperature of zones 2-8 is 190-240°C, extrusion temperature is 230±10°C; main screw speed is 250-350r / min.

[0029] Example 2

[0030] 49.5% of homopolymer polypropylene, 49% of impact copolymer polypropylene, 0.5% of stabilizer and 1% of other additives are weighed by weight, placed in a high-speed mixer and mixed evenly, then added from the main feeding port of a twin-screw extruder, and cooled and granulated after melt extrusion to prepare a low-density, high-rigidity and high-toughness polypropylene material. The process is as follows: temperature of zone 1 is 60-190°C, temperature of zones 2-8 is 190-240°C, extrusion temperature is 230±10°C; main screw speed is 250-350r / min.

[0031] Example 3

[0032] 58.5% of homopolymer polypropylene, 40% of impact copolymer polypropylene, 0.5% of stabilizer and 1% of other additives are weighed by weight, placed in a high-speed mixer and mixed evenly, then added from the main feeding port of a twin-screw extruder, and cooled and granulated after melt extrusion to prepare a low-density, high-rigidity and high-toughness polypropylene material. The process is as follows: zone one temperature 60-190°C, zone two to eight temperature 190-240°C, extrusion temperature 230±10°C; main screw speed 250-350r / min.

[0033] Example 4

[0034] 30.5% of homopolypropylene 1, 30% of homopolypropylene 2, 38.5% of impact copolymer polypropylene, 0.5% of stabilizer and 1% of other additives are weighed by weight, placed in a high-speed mixer and mixed evenly, then added from the main feeding port of a twin-screw extruder, and cooled and granulated after melt extrusion to prepare a low-density, high-rigidity and high-toughness polypropylene material. The process is as follows: temperature of zone 1 is 60-190°C, temperature of zones 2-8 is 190-240°C, extrusion temperature is 230±10°C, and main screw speed is 250-350r / min.

[0035] Example 5

[0036] 50.5% of homopolypropylene I, 30% of homopolypropylene II, 18.5% of impact copolymer polypropylene, 0.5% of stabilizer and 1% of other additives are weighed by weight, placed in a high-speed mixer and mixed evenly, then added from the main feeding port of a twin-screw extruder, and cooled and granulated after melt extrusion to prepare a low-density, high-rigidity and high-toughness polypropylene material. The process is as follows: zone one temperature 60-190°C, zone two to zone eight temperature 190-240°C, extrusion temperature 230±10°C; main screw speed 250-350r / min.

[0037] Performance evaluation method and implementation standards:

[0038] The material particles prepared by the above method were placed in a 90° C. forced air oven to dry for 2-3 hours, and then the dried particles were injection molded into standard specimens and subjected to performance testing.

[0039] Performance evaluation method: The tensile performance test is carried out according to GB / T 1040.2 standard, the test speed is 50mm / min, and the sample size is 170mm×10mm×4mm; the bending performance test is carried out according to GB / T 9341 standard, the test speed is 2mm / min, the span is 64mm, and the sample size is 80mm×10mm×4mm; the cantilever beam notch impact test is carried out according to GB / T 1843 standard, the sample size is 80mm×10mm×4mm, the notch retention width is 8.0±0.2mm, and the notch type is A; the heat deformation temperature test is carried out according to GB / T1634.2 standard.

[0040] The formulas (weight percentage) of the comparative examples and embodiments of the present invention are shown in Table 1, and the corresponding performance test results are shown in Table 2.

[0041] Table 1 Material composition of comparative examples 1-3 and embodiments 1-5

[0042]

[0043] Table 2 Performance test results of comparative examples 1-3 and embodiments 1-5

[0044]

[0045] It can be seen from the above comparative examples 1-3 and examples 1-5 that the polypropylene material blended with multiple polypropylenes has excellent performance in the material's rigidity and toughness balance performance, which not only greatly increases the material's heat deformation temperature, but also improves the processing performance. And because it is a single polypropylene type material, the material density remains at 0.9g / cm 3 While improving its mechanical properties, it maintains the lightweight advantages of polypropylene materials and is also easy to recycle.

[0046] In Comparative Examples 1-2 and Examples 1-2, it can be seen that the selection of homopolypropylene types and their addition amount have a great influence on the heat deformation temperature and notched impact strength of the material. Comparative Example 3 and Example 3, in which homopolypropylene II is added, have better heat deformation temperature and notched impact strength than Comparative Example 2 and Example 2. This is because, compared with homopolypropylene I, homopolypropylene II has higher crystallinity, better molecular chain regularity, and its own special crystal form, which can effectively increase the heat deformation temperature of the material, so that the material has a higher use temperature while maintaining good impact resistance. Similarly, compared with homopolypropylene I and homopolypropylene II, impact copolymer polypropylene can greatly improve the notched impact strength of the material, and the notched impact strength is significantly improved with the increase in the addition amount. In addition, due to the lower melt index of homopolypropylene II, its own molecular weight is higher, the molecular chain is very long, and the degree of entanglement is significantly improved. After blending with impact copolymer polypropylene, a synergistic effect is produced. The simultaneous addition of the two can greatly improve the toughness of the material surface, exceeding the performance of the original single material, so that the obtained material has excellent mechanical properties.

[0047] It can be seen from Comparative Example 4 and Example 4 that by adding a certain amount of highly crystalline homopolymer polypropylene II, the bending modulus and heat deformation temperature of the material are improved without changing the density of the polypropylene material. Its mechanical properties are equivalent to those of PP-T10 material, which effectively reduces the weight of the product and is also conducive to recycling.

[0048] By comparing Example 3 and Example 4, it can be seen that adding a certain amount of ordinary homopolymer polypropylene has little effect on the rigidity and toughness of the material, and can further increase the bending modulus of the material and the heat deformation temperature of the material, which can better meet the requirements of the parts.

[0049] The above is only a specific embodiment of the present invention, which is to illustrate the technical concept and features of the present invention, and is intended to enable those skilled in the art to understand the ideas and contents of the present invention. Therefore, all those defined by the claims should be included in the protection scope of the present invention.

Claims

1. A heat-resistant, low-density, high-rigidity-toughness balanced polypropylene material, characterized in that: The invention is composed of the following raw materials in weight percentage: homopolypropylene: homopolypropylene 1: 40-80%; homopolypropylene 2: 0-50%; impact-resistant copolymer polypropylene: 20-60%; stabilizer: 0.1-2%; other additives: 0-5%.

2. The heat-resistant, low-density, high-rigidity-toughness balanced polypropylene material according to claim 1, characterized in that: The homopolymer polypropylene has a melt flow rate of 3-15 g / 10 min.

3. The heat-resistant, low-density, high-rigidity-toughness balanced polypropylene material according to claim 1, characterized in that: The homopolymer polypropylene has a melt flow rate of 0.5-2 g / 10 min.

4. The heat-resistant, low-density, high-rigidity-toughness balanced polypropylene material according to claim 1, characterized in that: The melt flow rate of the impact-resistant copolymer polypropylene is 1-30 g / 10 min.

5. The heat-resistant, low-density, high-rigidity-toughness-balanced polypropylene material according to claim 1, characterized in that: The stabilizer is a primary antioxidant and a secondary antioxidant that are considered necessary by those skilled in the art, wherein the primary antioxidant is a hindered phenol or thioester antioxidant, and the secondary antioxidant is a phosphite or lipid antioxidant.

6. The heat-resistant, low-density, high-rigidity-toughness-balanced polypropylene material according to claim 1, characterized in that: The other additives are one or a combination of anti-light additives, flame retardants, antistatic additives, surfactants, plasticizers, and antimicrobial additives that are considered necessary by those skilled in the art.

7. The method for preparing the low-density, high-rigidity and high-toughness polypropylene material according to any one of claims 1 to 10, characterized in that: The specific steps are as follows: Homopolymer polypropylene, impact copolymer polypropylene, stabilizer and other additives are mixed evenly in a high-speed mixer according to the ratio, and then added to a twin-screw extruder from the main feed. The remaining compatibilizer, coupling agent and part of the filler are mixed evenly, and then added to the twin-screw extruder from the side feed port of the middle part of the screw. After melt extrusion, cooling and granulation are performed. The process is: the temperature of the first zone is 60-190℃, the temperature of the second to eighth zones is 190-240℃, the extrusion temperature is 230±10℃; the main screw speed is 250-350r / min. After melt extrusion, cooling, granulation and drying, a low-density, high-rigidity and high-toughness polypropylene material is obtained.

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