A method for preparing lightweight polypropylene plastic

Abstract

The present invention provides a method for preparing a lightweight polypropylene plastic, belonging to the technical field of polypropylene plastic preparation. The preparation method comprises the following steps: heating polypropylene to 170-180°C and performing a first stirring step; adding micron-sized spherical hollow powder; heating to 260-300°C and mixing uniformly; naturally cooling to 200-220°C and allowing to stand; then adding a lubricant, an antioxidant, a light stabilizer, and a masterbatch; and finally forming the lightweight polypropylene plastic. The present invention introduces a micron-sized spherical hollow powder material. Due to its spherical shape and unique hollow structure, it possesses excellent properties such as good dispersibility, low density, and a large specific surface area. This significantly reduces the overall density of the material, while also forming a strong link with the polypropylene molecular chain through its surface open pore structure, thereby improving the mechanical strength of the composite material.

Description

Technical Field

[0001] The invention belongs to the technical field of polypropylene plastic preparation, and in particular relates to a method for preparing lightweight polypropylene plastic. Background Art

[0002] Polypropylene (PP) is one of the five most common plastics. It boasts abundant resources, low cost, excellent mechanical properties, good electrical insulation, resistance to stress cracking, and good chemical stability. Lightweighting technology aims to reduce material density and usage while maintaining or improving its mechanical properties, heat resistance, and functionality.

[0003] Currently, lightweighting technologies primarily include foaming, lightweight filling materials, thin-walling and structural optimization, blending and alloying, and nanocomposites. Each of these technologies presents certain drawbacks. For example, foaming can reduce material strength and make cell control difficult; hollow glass microsphere fillings exhibit poor interface bonding with the matrix, resulting in low impact strength; thin-walling carries the risk of warping; blending and modification pose compatibility issues and reduced temperature resistance; and nanocomposites exhibit poor dispersibility and high cost. Polypropylene lightweighting technology has been widely adopted in the automotive and packaging sectors, but the performance-cost balance still needs to be addressed, with future development oriented towards high-performance and sustainable development.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing lightweight polypropylene plastic. By introducing a micron-sized spherical hollow powder material, due to its spherical shape and unique hollow structure, it has excellent properties such as good dispersibility, low density, and large specific surface area. The overall density of the material can be greatly reduced. At the same time, the surface open pore structure forms a strong link with the polypropylene molecular chain, thereby improving the mechanical strength of the composite material.

[0006] In order to achieve the above objectives, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for preparing a lightweight polypropylene plastic, which is characterized by comprising the following steps:

[0008] S1: Heat polypropylene to 170-180°C and perform a first stirring, then add micron-sized spherical hollow powder, heat to 260-300°C and perform a second stirring to mix evenly.

[0009] Optionally, the micron-sized spherical hollow powder has multiple closed small cavities inside, an overall porosity of 20-50%, an average particle size of 5-50 μm, an average surface pore size of 2-5 μm, and a bulk density of 0.4-0.8 g / cm 3The micron-sized spherical hollow powder is prepared according to the preparation method of Chinese patent CN116422225B.

[0010] Furthermore, in terms of weight, the polypropylene and micron-sized spherical hollow powder are 70-90 parts and 10-30 parts respectively.

[0011] Furthermore, the first stirring rate is 500-800 r / min; the second stirring rate is 1000-1500 r / min.

[0012] Polypropylene is first heated to 170-180°C and stirred to melt the polypropylene particles evenly. At this time, the micron-sized spherical hollow powder is added. During the process of gradually heating to 260-300°C, more molecular chains are broken, more combined with the hollow powder, entering the micropores on its surface and entangled together.

[0013] S2: The mixture obtained in step S1 is naturally cooled to 200-220°C and kept at this temperature for standing.

[0014] Furthermore, the heat preservation and standing time is 30-90 minutes.

[0015] The present invention has found that keeping the hollow powder at a temperature of 200-220°C and letting it stand can further stabilize the entanglement between the hollow powder and the polypropylene molecular chains. If the process is not allowed to stand, some molecular chains may shrink due to a rapid decrease in their activity, thereby withdrawing from the hollow powder and affecting the strength of the product.

[0016] S3: adding a lubricant, an antioxidant, a light stabilizer and a color masterbatch to the product of step S2 and mixing them under a third stirring process.

[0017] Optionally, the lubricant includes one or more of oxidized polyethylene wax, paraffin wax or EBS.

[0018] Optionally, the antioxidant includes one or more of antioxidant 1010 , antioxidant 168 , or antioxidant 1076 .

[0019] Optionally, the light stabilizer includes one or more of pyridine, benzotriazole, titanium oxide or zinc oxide.

[0020] Furthermore, in parts by weight, the product of step S2, lubricant, antioxidant, light stabilizer and masterbatch are 100 parts, 0.1-0.5 parts, 0.1-0.5 parts, 0.1-0.3 parts and 1-3 parts respectively.

[0021] Furthermore, the mixing temperature is 155-180° C.; and the third stirring speed is 500-600 r / min.

[0022] S4: molding the mixed product obtained in step S3 to obtain the lightweight polypropylene plastic.

[0023] Optionally, the molding may be extrusion molding, injection molding or other molding methods.

[0024] Furthermore, the molding temperature is 200-220°C.

[0025] Compared to existing technologies, this invention introduces micron-sized spherical hollow powder materials. Through stirring and mixing at different temperatures, the polypropylene organic molecular chains are fully entangled with the micropores on the hollow powder surface, significantly improving the bonding between the two. Due to its spherical shape and unique hollow structure, it possesses excellent properties such as good dispersibility, low density, and large specific surface area, significantly reducing the overall density of the material. At the same time, the surface open pores form a strong link with the polypropylene molecular chains, improving the mechanical strength of the composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 This is a photo of an experimental sample of the lightweight polypropylene plastic of Example 1 of the present invention;

[0028] Figure 2 This is a photo of a plastic pipe made of lightweight polypropylene plastic according to Example 1 of the present invention. DETAILED DESCRIPTION

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0030] Example 1

[0031] A method for preparing lightweight polypropylene plastic:

[0032] (1) 900 g of polypropylene granules were placed in a high-temperature container, heated to 170 ° C, and stirred at a rate of 800 r / min for 20 min. Then, 100 g of micron-sized spherical hollow powder (K990 provided by Tianjin Zhiqing Future Technology Co., Ltd., prepared according to the preparation method of Example 4 of Chinese patent CN116422225B, with multiple closed small cavities inside, an overall porosity of 46%, an average particle size of 45 μm, an average surface pore size of 2.6 μm, and a bulk density of 0.46 g / cm) was added. 3 ), adjust the stirring rate to 1500r / min and heat to 260℃, stir for 20min and mix well.

[0033] (2) The mixture of step (1) was naturally cooled to 200°C and kept at this temperature for 60 minutes.

[0034] (3) The product of step (2) was placed in a mixer with 3 g of paraffin wax, 3 g of antioxidant 1010, 3 g of zinc oxide, and 20 g of masterbatch. The speed was set to 500 r / min and the high-speed mixing time was 1 min at 170°C.

[0035] (4) The mixed material in step (3) is extruded or injection molded at 200°C to obtain a product. The test performance is shown in Table 1. Figure 1 Some molding experimental samples are shown. Figure 2 Some of the plastic tubes are shown after being formed.

[0036] Example 2

[0037] A method for preparing lightweight polypropylene plastic:

[0038] (1) Place 700 g of polypropylene granules in a high-temperature container, heat to 175 ° C, and stir at a rate of 600 r / min. Then add 300 g of the same micron-sized spherical hollow powder as in Example 1, adjust the stirring rate to 1400 r / min and heat to 280 ° C. Stir for 20 min and mix evenly.

[0039] (2) The mixture of step (1) was naturally cooled to 220°C and kept at this temperature for 30 minutes.

[0040] (3) The product of step (2) was placed in a mixer with 1.5 g of polyethylene wax, 1.5 g of antioxidant 168, 1.5 g of pyridine, and 10 g of masterbatch. The speed was set to 550 r / min and the high-speed mixing time was 1 min at 180°C.

[0041] (4) The mixed material in step (3) is extruded or injection molded at 220°C to obtain a product. The test performance is shown in Table 1.

[0042] Example 3

[0043] A method for preparing lightweight polypropylene plastic:

[0044] (1) 800 g of polypropylene granules were placed in a high-temperature container, heated to 180 ° C, and stirred at a rate of 700 r / min. Then, 200 g of the same micron-sized spherical hollow powder as in Example 1 was added. The powder had multiple closed small cavities inside, an overall porosity of 46%, an average particle size of 45 μm, an average surface pore size of 2.6 μm, and a bulk density of 0.46 g / cm 3 ), adjust the stirring rate to 1300r / min and heat to 270℃, stir for 20min and mix well.

[0045] (2) The mixture of step (1) was naturally cooled to 210°C and kept at this temperature for 90 minutes.

[0046] (3) The product of step (2) was placed in a mixer with 1 g of EBS, 1 g of antioxidant 1076, 1 g of benzotriazole, and 15 g of masterbatch. The speed was set to 600 r / min and the high-speed mixing time was 1 min at 175°C.

[0047] (4) The mixed material in step (3) is extruded or injection molded at 210°C to obtain a product. The test performance is shown in Table 1.

[0048] Comparative Example 1

[0049] The difference from Example 1 is that 100 g of hollow glass microspheres (HM10 product provided by Zhengzhou Shenglait Hollow Microsphere New Materials Co., Ltd.) are used instead of 100 g of micron-sized spherical hollow powder in Example 1.

[0050] The test performance is shown in Table 1.

[0051] Comparative Example 2

[0052] The difference from Example 1 is that in step (1), 1000 g of polypropylene particles are added, but no micron-sized spherical hollow powder is added.

[0053] The test performance is shown in Table 1.

[0054] Comparative Example 3

[0055] The difference from Example 1 is that in step (1), 900 g of polypropylene particles are placed in a high-temperature container, and then 100 g of the same micron-sized spherical hollow powder as in Example 1 is added, and the mixture is heated to 260° C. at a stirring rate of 1500 r / min, stirred for 20 min, and mixed evenly.

[0056] The test performance is shown in Table 1.

[0057] Comparative Example 4

[0058] The difference from Example 1 is that in step (1), 900 g of polypropylene particles are placed in a high-temperature container, heated to 170° C., and stirred at a rate of 800 r / min for 20 min, and then 100 g of the same micron-sized spherical hollow powder as in Example 1 is added, and stirring is continued for 20 min.

[0059] The test performance is shown in Table 1.

[0060] Comparative Example 5

[0061] The difference from Example 1 is that step (2) is omitted, and the product of step (1) is directly cooled to 170° C. to perform step (3).

[0062] The test performance is shown in Table 1.

[0063] Table 1 Comparison of properties of polypropylene plastics obtained in Examples 1-3 and Comparative Examples 1-5

[0064]

[0065] A comparison of Examples 1-3 and Comparative Example 1 in Table 1 shows that the addition of the micron-sized spherical hollow powder in the present invention results in lower density and higher strength. This is because the hollow glass microspheres added in Comparative Example 1 break during the molding process (especially extrusion molding), resulting in increased material density, poor bonding with the polypropylene matrix, and reduced strength.

[0066] From the comparison of Example 1 and Comparative Example 2 in Table 1, it can be seen that since the micron-sized spherical hollow powder is not added in Comparative Example 2, its matrix strength is lower and its matrix density is greater than the lightweight polypropylene plastic of the present invention.

[0067] By comparing Example 1 and Comparative Examples 3-5 in Table 1, it can be seen that Comparative Example 3 was not stirred and heated at 170°C, Comparative Example 4 was not stirred when heated to 260°C, and Comparative Example 5 was not kept warm and allowed to stand at 200°C. Compared with Example 1, the strength of the samples decreased, and the degree of decrease was: Comparative Example 4>Comparative Example 5>Comparative Example 3.

[0068] Please note that the technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. The above embodiments only express several implementation methods of the present application. The description is relatively specific and detailed, but it cannot be understood as a limitation on the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of this application, several variations and improvements can be made, which all fall within the scope of protection of this application. Therefore, the scope of protection of the patent in this application shall be based on the attached claims.

Claims

1. A method for preparing lightweight polypropylene plastic, characterized in that: The steps include: S1: Heat polypropylene to 170-180°C and perform a first stirring, then add micron-sized spherical hollow powder, heat to 260-300°C and mix evenly under a second stirring; S2: The mixture obtained in step S1 is naturally cooled to 200-220°C and kept still; S3: adding a lubricant, an antioxidant, a light stabilizer, and a masterbatch to the product of step S2 and mixing them under a third stirring; S4: molding the mixed product obtained in step S3 to obtain the lightweight polypropylene plastic; In step S1, the micron-sized spherical hollow powder has multiple closed small cavities inside, an overall porosity of 20-50%, an average particle size of 5-50 μm, an average surface pore size of 2-5 μm, and a bulk density of 0.4-0.8 g / cm 3 ; According to parts by weight, the polypropylene and micron-sized spherical hollow powder are 70-90 parts and 10-30 parts respectively.

2. The preparation method according to claim 1, characterized in that In step S1, the first stirring rate is 500-800 r / min; And / or, the second stirring rate is 1000-1500 r / min.

3. The preparation method according to claim 1, characterized in that In step S2, the heat preservation and standing time is 30-90 minutes.

4. The preparation method according to claim 1, characterized in that In step S3, the lubricant includes one or more of oxidized polyethylene wax, paraffin wax, or EBS; and / or, the antioxidant includes one or more of antioxidant 1010, antioxidant 168, or antioxidant 1076; And / or, the light stabilizer includes one or more of pyridine, benzotriazole, titanium oxide or zinc oxide.

5. The preparation method according to claim 1, characterized in that In step S3, the product of step S2, lubricant, antioxidant, light stabilizer and masterbatch are 100 parts, 0.1-0.5 parts, 0.1-0.5 parts, 0.1-0.3 parts and 1-3 parts respectively in parts by weight.

6. The preparation method according to claim 1, characterized in that In step S3, the mixing temperature is 155-180°C; And / or, the third stirring speed is 500-600 r / min.

7. The preparation method according to claim 1, characterized in that In step S4, the molding temperature is 200-220°C.

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