Polypropylene composition as well as preparation method and application thereof

Abstract

The invention discloses a polypropylene composition as well as a preparation method and application thereof, and belongs to the field of high polymer materials and molding processing thereof. The second polypropylene, the orientation modifier and the melt strength stabilizer are adopted to modify the glass fiber reinforced polypropylene composition, the polypropylene composition with small burr length and high stability is obtained, and the cooling effect of the prepared waterway manifold is improved. The polypropylene composition provided by the invention is suitable for the field of preparation of automobile waterway manifold parts, and has a good market application prospect.

Description

Technical Field

[0001] The present invention belongs to the field of polymer materials and their processing, and particularly relates to a polypropylene composition, a preparation method thereof, and an application thereof. Background Art

[0002] With the development of the automotive industry, the design of automotive parts shows an integrated trend. Taking the expansion tank of the cooling system as an example, the traditional expansion tank is gradually transitioning to a waterway manifold. The waterway manifold integrates the functions of the expansion tank and the waterway pipeline, reducing the number, weight, and assembly process of parts, and making an important contribution to cost reduction and lightweighting of the cooling system. As a new type of part emerging in the automotive industry, the waterway manifold is generally made of 20% glass fiber reinforced polypropylene. There is no mature experience to draw on in terms of structure and design. Its complex structure and integrated functions pose higher requirements for design, materials, welding, etc. For example, in the welding of the waterway manifold, hot plate welding is usually used. The complex internal structure limits the design of the traditional overflow groove, resulting in inevitable welding burrs (flash). In the actual production process, it is found that under the premise of unchanged materials, structure, and welding process, the welding burrs show an unstable state. Larger burrs affect the flow of the coolant in the waterway manifold, thereby reducing the cooling effect. Regarding the influence of welding burrs on the waterway manifold, current relevant patents and papers all aim to reduce the generation of burrs. However, at present, it is difficult to completely reduce the generation of burrs. Therefore, researchers hope to avoid the appearance of large burrs by controlling the stability of the burrs. Regarding the problem of burr stability, there are no relevant patents and papers to solve it.

[0003] The prior art discloses a blow-molded glass fiber reinforced polypropylene composite material for automotive pipes, which contains low-flow polypropylene and high-density polyethylene, and is modified with a grafted polypropylene compatibilizer and short-cut glass fibers. The obtained material has high rigidity, high heat resistance, aging resistance, and good three-dimensional blow molding performance, and has few burrs (flash). However, this prior art does not study the problem of burr stability.

[0004] Therefore, it is of great research significance and application value to develop a polypropylene composition with a small burr length and high burr stability, as well as a preparation method and an application thereof. Summary of the Invention

[0005] In order to solve the technical problems of large welding burr length and low stability of burr length in continuous production of glass fiber reinforced polypropylene for waterway manifolds in the prior art, the primary object of the present invention is to provide a polypropylene composition. The polypropylene composition provided by the present invention modifies the glass fiber reinforced polypropylene composition with a second polypropylene, an orientation regulator, and a melt strength stabilizer, obtaining a polypropylene composition with a small burr length and high stability, and improving the cooling effect of the prepared waterway manifold.

[0006] Another object of the present invention is to provide a method for preparing the above-mentioned polypropylene composition.

[0007] Another object of the present invention is to provide the application of the above-mentioned polypropylene composition in the preparation of automotive waterway manifolds.

[0008] To achieve the above-mentioned invention objects, the present invention adopts the following technical solutions:

[0009] The present invention protects a polypropylene composition, comprising the following components in parts by weight:

[0010] 9 - 45 parts of the first polypropylene, 30 - 67 parts of the second polypropylene, 3 - 10 parts of an orientation regulator, 2 - 10 parts of a compatibilizer, 18 - 22 parts of glass fiber, 0.29 - 0.75 parts of a melt strength stabilizer;

[0011] Among them, the first polypropylene is at least one of block copolymerized polypropylene or random copolymerized polypropylene, and the melt flow rate at 230 °C and 2.16 kg is 0.6 - 3 g / 10 min;

[0012] The orientation regulator is SEBS;

[0013] The melt strength stabilizer is polytetrafluoroethylene;

[0014] The melt flow rate of the second polypropylene at 230 °C and 2.16 kg is 0.2 - 0.5 g / 10 min.

[0015] The present invention provides a polypropylene composition, which is modified on the basis of a glass fiber reinforced polypropylene material. By adding a second polypropylene with low flowability, a higher viscosity is provided. During hot plate welding, it is difficult for the polypropylene melt to flow during the pressing process, reducing the phenomenon of melt overflow and reducing welding flash. The addition of the melt strength stabilizer can make the melt strength of the material higher and uniform, reducing the inconsistent size of the flash during the welding process, that is, improving the stability of the welding flash, ensuring the uniform uniformity of the parts, and being beneficial to production. The combination of copolymerized polypropylene and the orientation regulator can adjust the orientation of the glass fiber in the parts, reduce the warping deformation of the parts, and reduce the probability of large flash occurring during the welding process.

[0016] Specifically, the measurement method of the melt flow rate of the first polypropylene and the second polypropylene in the present invention refers to GB / T - 3682 - 2000.

[0017] Preferably, the melt flow rate of the first polypropylene is 0.6 g / 10 min - 3.0 g / 10 min.

[0018] Preferably, the melt flow rate of the first polypropylene is one or more of 0.6 g / 10 min, 0.8 g / 10 min, 1.0 g / 10 min, 1.2 g / 10 min, 1.5 g / 10 min, 1.8 g / 10 min, 2.0 g / 10 min, 2.5 g / 10 min or 3.0 g / 10 min.

[0019] Preferably, the melt flow rate of the second polypropylene is 0.2 g / 10 min to 0.5 g / 10 min.

[0020] Preferably, the melt flow rate of the second polypropylene is one or more of 0.2 g / 10 min, 0.3 g / 10 min, 0.4 g / 10 min or 0.5 g / 10 min.

[0021] Preferably, the sum of the total masses of the first polypropylene and the second polypropylene accounts for more than 60% of the total mass of the polypropylene composition.

[0022] Preferably, the compatibilizer is maleic anhydride grafted polypropylene.

[0023] Preferably, the weight parts of the compatibilizer are 5 to 10 parts.

[0024] More preferably, the grafting rate of the maleic anhydride grafted polypropylene is 0.4 to 1.5%.

[0025] Preferably, the viscosity of the 10 wt% toluene solution of the SEBS at 25 °C is 280 to 2000 cp.

[0026] More preferably, the viscosity of the 10 wt% toluene solution of the SEBS at 25 °C is 1700 to 1900 cp.

[0027] The viscosity of the 10 wt% toluene solution of the SEBS at 25 °C is tested according to GB / T 2794-2013. <>

[0028] Preferably, the glass fiber is one or both of long alkali-free glass fiber or chopped alkali-free glass fiber. <>

[0029] More preferably, the glass fiber is chopped alkali-free glass fiber, that is, chopped E glass fiber.

[0030] Preferably, the chopped length of the chopped alkali-free glass fiber is 3.0 to 4.5 mm.

[0031] Preferably, the fiber diameter of the chopped alkali-free glass fiber is 10 to 13 μm.

[0032] Preferably, the average particle size of the polytetrafluoroethylene is 20 to 300 μm.

[0033] The test method for the average particle size of the polytetrafluoroethylene is in accordance with the test method for the particle size of polytetrafluoroethylene resin HG / T 2901-1997.

[0034] Preferably, the polypropylene composition further comprises an antioxidant.

[0035] Preferably, the antioxidant comprises a primary antioxidant and / or a secondary antioxidant.

[0036] Specifically, the antioxidant comprises 0.1-0.6 parts of a primary antioxidant and 0.1-0.6 parts of a secondary antioxidant.

[0037] Preferably, the primary antioxidant is at least one of an antioxidant with a double structure of hindered phenol and acyl hydrazine or an amine antioxidant.

[0038] Preferably, the secondary antioxidant is at least one of a phosphite antioxidant or a thioether antioxidant.

[0039] The present invention also provides a method for preparing a polypropylene composition, comprising the following steps:

[0040] Mix the first polypropylene, the second polypropylene, the compatibilizer, the orientation regulator, and the melt strength stabilizer; subject the mixed raw materials and glass fiber to melt extrusion and cooling pelletization to obtain the polypropylene composition.

[0041] Preferably, the conditions for melt extrusion are as follows: the ratio of the length to the diameter of the twin-screw extruder is (40-56):1, the twin-screw extruder includes at least one exhaust hole and one side feeding port, wherein the temperature of the feeding section ≤ 100 °C, the temperature of the conveying section is 100-200 °C, and the temperature of the shearing section is 180-220 °C. The vacuum degree of the vacuum hole ≤ -0.08 MPa.

[0042] Specifically, the glass fiber is added at the side feeding port of the twin-screw extruder.

[0043] The application of the above polypropylene composition in the preparation of automotive waterway manifold parts is also within the protection scope of the present invention.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The polypropylene composition provided by the present invention selects low-flow polypropylene to reduce welding flash, adds a melt strength stabilizer, an orientation regulator, and copolymer polypropylene, reduces the length of the flash, and improves the flash stability, making the quality of the parts more uniform and enhancing the cooling effect of the prepared waterway manifold. Description of the Drawings

[0046] Figure 1 : Schematic diagram of welding flash and test points;

[0047] Figure 2 : Schematic diagram of burrs before and after welding and burr length. Specific implementation manners

[0048] The present invention will be further described below in conjunction with embodiments. These embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. For the experimental methods without specific conditions in the following embodiments, they are usually carried out according to the conventional conditions in the art or according to the conditions recommended by the manufacturer; the raw materials, reagents, etc. used, unless otherwise specified, are all raw materials and reagents that can be obtained from commercial channels such as the conventional market. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention fall within the scope of protection required by the present invention.

[0049] Some reagents selected in the embodiments and comparative examples of the present invention are described as follows:

[0050] First polypropylene 1#: Random copolymerized polypropylene resin, PP-R 4220, with a melt flow rate of 0.6 g / 10 min under the conditions of 230 °C and 2.16 kg, from Yanshan Petrochemical, China;

[0051] First polypropylene 2#: Block copolymerized polypropylene resin, PP EP300H, with a melt flow rate of 1.8 g / 10 min under the conditions of 230 °C and 2.16 kg, from CNOOC and Shell Petrochemical Company Limited, China;

[0052] First polypropylene 3#: Block copolymerized polypropylene resin, PPB-M02-G(K8003), with a melt flow rate of 3.0 g / 10 min under the conditions of 230 °C and 2.16 kg, from Zhenhai Refining & Chemical Company, China;

[0053] First polypropylene 4#: Homopolymerized polypropylene resin, PP T30S, with a melt flow rate of 3.4 g / 10 min under the conditions of 230 °C and 2.16 kg, from Hohhot Petrochemical Company, China;

[0054] Second polypropylene 1#: Homopolymerized polypropylene resin, PP B1101, with a melt flow rate of 0.3 g / 10 min under the conditions of 230 °C and 2.16 kg, from Formosa Chemicals & Fibre Corporation, Taiwan, China;

[0055] Second polypropylene 2#: Copolymerized polypropylene resin, PP 8001, with a melt flow rate of 0.28 g / 10 min under the conditions of 230 °C and 2.16 kg, from Formosa Plastics Corporation, Taiwan, China;

[0056] Second polypropylene 3#: Copolymerized polypropylene resin, PP B8101, with a melt flow rate of 0.4 g / 10 min under the conditions of 230 °C and 2.16 kg, from Yanshan Petrochemical, China;

[0057] Second polypropylene 4#: copolymerized polypropylene resin, PP 7123KNE1, with a melt flow rate of 10 g / 10 min at 230°C and 2.16 kg, from ExxonMobil, USA;

[0058] Second polypropylene 5#: copolymer polypropylene resin, PP-R Q802, melt flow rate of 0.15 g / 10 min at 230°C and 2.16 kg, Daqing Huake, China;

[0059] Orientation regulator 1#: SEBS 6151, 10 wt% toluene solution viscosity 1700 cp at 25°C, Taiwan Rubber Corporation, China;

[0060] Orientation regulator 2#: SEBS 6154, 10 wt% toluene solution viscosity 280 cp at 25°C, Taiwan Rubber Corporation, China;

[0061] Orientation regulator 3#: SEBS 6551, 10 wt% toluene solution viscosity 1900 cp at 25°C, Taiwan Rubber Corporation, China;

[0062] Orientation regulator 4#: SEBS YH-602, 10 wt% toluene solution with a viscosity of 800 cp at 25°C, from China Baling Petrochemical;

[0063] Orientation regulator 5#: SEBS YH-503, 10 wt% toluene solution viscosity 1500 cp at 25°C, China Baling Petrochemical;

[0064] Compatibilizer: Maleic anhydride grafted polypropylene, LEP-1A, Ketong, Shenyang, China, grafting rate 0.6%;

[0065] Glass fiber: Chopped glass fiber ECS13-4.5-T438R, chopped length 4.5 mm, fiber diameter 13 μm, Taishan Fiberglass, China;

[0066] Melt strength stabilizer 1#: polytetrafluoroethylene, DF-106, average particle size 225 μm, Dongyue, Shandong, China;

[0067] Melt strength stabilizer 2#: polytetrafluoroethylene, DF-162, average particle size 25 μm, Dongyue, Shandong, China;

[0068] Melt strength stabilizer 3#: polytetrafluoroethylene, DF-102, average particle size 275 μm, Dongyue, Shandong, China;

[0069] Primary antioxidant: antioxidant 1076, commercially available;

[0070] Secondary antioxidant: antioxidant 168, commercially available;

[0071] The polypropylene compositions of the embodiments and comparative examples of the present invention were prepared through the following process:

[0072] S1. Mix the first polypropylene, the second polypropylene, a compatibilizer, a primary antioxidant, a secondary antioxidant, and a melt strength stabilizer, and add them to a high-speed mixer for mixing to obtain a uniformly mixed polypropylene mixture;

[0073] S2. Add the mixture obtained in step S1 to a twin-screw extruder, add it through the main feeding port of the twin-screw extruder, add glass fiber through the side feeding port, and obtain a glass fiber reinforced polypropylene composite material through extrusion and pelletizing.

[0074] Among them, the temperatures of each zone of the twin-screw extruder are 80°C, 120°C, 160°C, 170°C, 180°C, 200°C, 200°C, 200°C, 200°C, 200°C, 200°C, 200°C in sequence. The vacuum degree of the vacuum holes is -0.08 MPa.

[0075] The performance test methods and standards of the polypropylene compositions of the embodiments and comparative examples of the present invention are as follows:

[0076] Welding flash: Inject test specimens with the materials prepared above. The size of the specimens is 100×40×4 mm, and then perform hot plate welding. The welding process is a welding temperature of 270°C, a melting time of 6 s, a curing time of 30 s, and a welding depth of 2 mm. After welding, test the length L of the welding flash, that is, the thickness of the flash formed by the overflow of the solder after welding two specimens. The flash is the part where the solder protrudes from the surface of the specimen. Test two points on each specimen, and calculate the qualified rate of the flash length = (the number of L≤2 mm) / total number × 100%. The qualified rate of the flash length is required to be ≥90%, and the probability of the flash length L>4 mm is required to be 0. Weld 10 specimens, each specimen has two sides (such as Figure 2 ), measure the flash length at one position on each side, and there are a total of 20 data for 10 specimens. Count the number of ≤2 mm, and the ratio of the number of qualified flashes to the total number is the qualified rate of the flash length, which characterizes the flash stability;

[0077] (1) Flash length L (mm): The flash length is the average value of testing one position on each of the two sides of each specimen, measured with a ruler, and is the length from the top to the bottom of the flash;

[0078] (2) Flash qualified rate (%): The proportion of the number of flashes with a flash length ≤2 mm among the total number of flashes in the 20 data of 10 specimens.

[0079] Examples 1 to 14

[0080] This embodiment provides a series of polypropylene compositions, and the weight parts of each component in the formula are shown in Table 1 and Table 2.

[0081] Table 1 Formulations of Examples 1 - 7 (parts)

[0082]

[0083]

[0084] Table 2 Formulations of Examples 8 - 14 (parts)

[0085]

[0086] Comparative Examples 1 - 8

[0087] This comparative example provides a series of polypropylene compositions, and each component in the formula is shown in Table 3.

[0088] Table 3 Formulations of Comparative Examples 1 - 8 (parts)

[0089]

[0090]

[0091] According to the method mentioned above, the performance test results of the polypropylene compositions in each example and comparative example are shown in Table 3.

[0092] Table 4 Performance Test Results of Each Example and Comparative Example

[0093] Performance Flash Length (mm) Flash Pass Rate (%) Example 1 0.9 100％ Example 2 0.6 100％ Example 3 1.8 100％ Example 4 0.7 100％ Example 5 1.1 100％ Example 6 1.2 100％ Example 7 1.5 100％ Example 8 1.0 100％ Example 9 0.8 100％ Example 10 1.8 100％ Example 11 1.5 100％ Example 12 0.7 100％ Example 13 1.2 100％ Example 14 1.0 100％ Comparative Example 1 1.9 70％ Comparative Example 2 2.4 40％ Comparative Example 3 2.3 45％ Comparative Example 4 4.7 0％ Comparative Example 5 5.2 0％ Comparative Example 6 1.4 50％ Comparative Example 7 0.9 60％ Comparative Example 8 3.8 40％

[0094] As can be seen from Table 4, the flash lengths of the polypropylene compositions prepared in Examples 1 - 14 of the present invention are small, the flash pass rate reaches 100%, and the flash lengths are all below 1.8 mm.

[0095] In Comparative Example 1, no melt strength stabilizer was added, and the flash appeared unstable; in Comparative Example 2, no orientation regulator and melt strength stabilizer were used, the flash length was unqualified, and its qualified probability decreased significantly; in Comparative Example 3, no orientation regulator was used, the flash length was large, and the qualified rate was 45%; in Comparative Example 4, the first polypropylene used was homopolypropylene, the flash length was large and the qualified rate was poor; in Comparative Example 5, the melt flow rate of the second polypropylene used was outside the range, the flash length was large and the qualified rate was poor; in Comparative Example 6, low-flow polypropylene with a melt flow rate outside the range was used, and the flash pass rate could not be improved; in Comparative Examples 7 and 8, the added parts of the raw materials were outside the range, and the flash pass rate did not meet the requirements.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A polypropylene composition, characterized in that The composition comprises the following components in parts by weight: 9-45 parts of the first polypropylene, 30-67 parts of the second polypropylene, 3-10 parts of the orientation regulator, 2-10 parts of the compatibilizer, 18-22 parts of the glass fiber, and 0.29-0.75 parts of the melt strength stabilizer; Wherein, the first polypropylene is at least one of block copolymer polypropylene or random copolymer polypropylene, and has a melt flow rate of 0.6 to 3 g / 10 min at 230° C. and 2.16 kg; The orientation regulator is SEBS; The melt strength stabilizer is polytetrafluoroethylene; The melt flow rate of the second polypropylene at 230° C. and 2.16 kg is 0.2 to 0.5 g / 10 min.

2. The polypropylene composition according to claim 1, characterized in that The viscosity of the SEBS solution in 10 wt% toluene at 25° C. is 280-2000 cp.

3. The polypropylene composition according to claim 1, characterized in that The average particle size of the polytetrafluoroethylene is 20 to 300 μm.

4. The polypropylene composition according to claim 1, characterized in that The polypropylene composition further comprises an antioxidant.

5. The polypropylene composition according to claim 1, characterized in that The compatibilizer is maleic anhydride grafted polypropylene.

6. The polypropylene composition according to claim 5, characterized in that The grafting rate of the maleic anhydride grafted polypropylene is 0.4-1.5%.

7. The polypropylene composition according to claim 1, characterized in that The glass fiber is one or both of long alkali-free glass fiber and short alkali-free glass fiber.

8. The polypropylene composition according to claim 7, characterized in that The fiber diameter of the chopped alkali-free glass fiber is 10 to 13 μm.

9. The method for preparing the polypropylene composition according to any one of claims 1 to 8, characterized in that: The following steps are involved: The first polypropylene, the second polypropylene, a compatibilizer, an orientation regulator, and a melt strength stabilizer are mixed; the mixed raw materials and glass fibers are melt-extruded, cooled, and granulated to obtain the polypropylene composition.

10. An automobile waterway manifold, prepared using the polypropylene composition according to any one of claims 1 to 8.

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