Polypropylene composition and use thereof

Abstract

This application discloses a polypropylene composition and its application, belonging to the field of polymer materials technology. The polypropylene composition of this application comprises the following components in parts by weight: 46.5–60.5 parts polypropylene resin, 12.7–20.3 parts toughening agent, 14.7–30.5 parts talc, and 9.9–18.2 parts hollow glass microspheres. The hollow glass microspheres have a compressive strength of ≥11000 Psi and a particle size Dn50 of ≤35 μm. Under the combined effect of the specific amounts of each component, this polypropylene composition exhibits low density, high weld line tensile strength, and excellent mechanical properties, making it suitable for manufacturing automotive interior and exterior parts, etc.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a polypropylene composition and its applications. Background Technology

[0002] Polypropylene (PP) possesses advantages such as low density, ease of processing, and excellent mechanical properties, and has been widely used in the automotive industry and other fields. For larger parts, multiple gates are often required during injection molding. When the material flows into the gates simultaneously, they merge between two gates, forming weld lines. Weld lines not only affect the appearance but also result in lower strength at the weld line, impacting the mechanical properties of the part. Furthermore, lightweighting is a crucial direction for the automotive industry. Currently, some research utilizes low isotactic polypropylene with a high melt index to improve the appearance and tensile strength of weld lines; however, the resulting polypropylene materials have lower mechanical properties and do not achieve weight reduction. Therefore, there is a need to develop a polypropylene material with low density, excellent mechanical properties, and high tensile strength at the weld lines. Summary of the Invention

[0003] In view of the deficiencies of the existing technology, the purpose of this invention is to provide a polypropylene composition and its application. The polypropylene composition has low density, inconspicuous weld lines and high tensile strength of weld lines, and excellent mechanical properties, and is suitable for the preparation of automotive interior and exterior parts, etc.

[0004] To achieve the above objectives, the present invention provides a polypropylene composition comprising the following components in parts by weight:

[0005]

[0006] The hollow glass microspheres have a compressive strength of over 11000 Psi and a particle size Dn50 of less than 35 μm.

[0007] The compressive strength of the hollow glass microspheres was tested by the following method: the test was conducted according to the standard JC / T2285-2014 "Determination of Isostatic Strength (Air Pressure Method) of Hollow Glass Microspheres", and the test temperature was 23±5℃, the same below.

[0008] The particle size Dn50 of hollow glass microspheres refers to the particle size corresponding to a cumulative distribution percentage of 50% for hollow glass microspheres. It is determined by the following test method: the hollow glass microspheres are dispersed in water, and the particle size is measured using a Malvern particle size analyzer.

[0009] The polypropylene composition described above exhibits less noticeable weld lines, higher tensile strength, and lower density by adding the aforementioned specific hollow glass microspheres. This may be because the hollow glass microspheres of the specific particle size have high compressive strength, are not easily sheared during the composition preparation process, and when the material flow containing hollow glass microspheres encounters each other during injection molding, the hollow glass microspheres are spherical and non-oriented, thus making the weld lines less noticeable and significantly improving the strength at the weld lines.

[0010] The polypropylene composition described above, with the combined effect of its components in specific amounts, exhibits low density, high weld line tensile strength, and excellent mechanical properties, making it suitable for manufacturing automotive interior and exterior parts.

[0011] When the amount of hollow glass microspheres added is below the above range, the improvement effect on the density, weld line appearance, and weld line tensile strength of the composition is not significant. When the amount of hollow glass microspheres added exceeds the above range, the mechanical properties of the composition, such as the cantilever beam notched impact strength (Type A), decrease significantly, and the weld line tensile strength decreases instead. This may be because the amount of hollow glass microspheres added is too large, resulting in poor compatibility with the matrix resin, which is not conducive to improving the weld line tensile strength. Therefore, this application selects the content of hollow glass microspheres to be 9.9 to 18.2 parts by weight, such as 10 parts by weight, 12 parts by weight, 14 parts by weight, 16 parts by weight, 18 parts by weight, etc., so as to simultaneously obtain lower density, less noticeable weld lines, higher weld line tensile strength, and cantilever beam notched impact strength (Type A) and other mechanical properties.

[0012] When the compressive strength of hollow glass microspheres is below 11,000 Psi, they are easily sheared during the preparation process, resulting in a significant decrease in the mechanical properties of the composition, such as the notched impact strength (Type A). This does not significantly improve the appearance of the weld line or its tensile strength. Therefore, this application selects hollow glass microspheres with a compressive strength above 11,000 Psi, such as 11,000 Psi, 12,000 Psi, 15,000 Psi, 20,000 Psi, 25,000 Psi, 28,000 Psi, etc., so as to simultaneously obtain lower density, less noticeable weld lines, higher weld line tensile strength, and mechanical properties such as notched impact strength (Type A).

[0013] If the particle size Dn50 of hollow glass microspheres is too large, the interface between the glass microspheres and PP will be larger, resulting in lower cantilever beam notched impact strength (Type A) and weld line tensile strength. Therefore, it is necessary to control the particle size Dn50 to below 35μm, such as 35μm, 30μm, 25μm, 20μm, 15μm, 10μm, 5μm, etc.

[0014] In some embodiments, the hollow glass microspheres have a compressive strength of 14,900–25,100 Psi (e.g., 15,000 Psi, 18,000 Psi, 19,000 Psi, 20,000 Psi, 21,000 Psi, 22,000 Psi, 23,000 Psi, 24,000 Psi, 25,000 Psi, etc.) and a particle size Dn50 of 11.8–20.2 μm (e.g., 12 μm, 15 μm, 17 μm, 19 μm, 20 μm, etc.) to better reduce the density of the composition and improve the appearance and strength of the weld lines.

[0015] In some embodiments, the true density of the hollow glass microspheres is 0.4–1.6 g / cm³. 3 For example, 0.4g / cm 3 0.7g / cm 3 1.0g / cm 3 1.2g / cm 3 1.5g / cm 3 The true density of the hollow glass microspheres can be obtained by the following method: after crushing them, the density is tested according to GB / T 21782.3-2008 Powder Coatings Part 3: Liquid Displacement Specific Gravity Bottle Method.

[0016] In some embodiments, the average particle size of the talc powder is 1–10 μm, such as 1 μm, 2 μm, 5 μm, 7 μm, 10 μm, etc. In one embodiment, the average particle size of the talc powder is 2.8–8.2 μm, such as 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, etc., to enable the composition to obtain higher weld line tensile strength and cantilever beam notched impact strength (Type A) and other mechanical properties. The average particle size of the talc powder is tested as follows: the talc powder is dispersed in water, and the particle size corresponding to the cumulative distribution percentage of talc powder reaching 50% is tested using a Malvern particle size analyzer.

[0017] In one embodiment, the polypropylene in the polypropylene composition has a mass fraction of 43% or more, such as 44%, 45%, 50%, 55%, 60%, etc.

[0018] In one embodiment, the melt flow rate of the polypropylene resin under test conditions of 230°C / 2.16kg is 9.7–30.5 g / 10 min, so that the composition obtains higher weld line tensile strength and cantilever beam notched impact strength (Type A) and other mechanical properties. The melt flow rate of the polypropylene resin is measured according to standard GB / T 3682.2-2018 "Determination of Melt Index Mass Flow Rate and Melt Volume Flow Rate of Thermoplastic Plastics".

[0019] In one embodiment, the polypropylene resin includes at least one of homopolymer polypropylene resin and copolymer polypropylene resin.

[0020] In one embodiment, the toughening agent includes at least one selected from ethylene-butene copolymer elastomer, ethylene-octene copolymer elastomer, and styrene copolymer elastomer.

[0021] In one embodiment, the component further includes the following components in parts by weight: 0.18 to 2.2 parts of additives. Appropriate additives, such as at least one of antioxidants, light stabilizers, and colorants, can be added according to actual needs.

[0022] In one embodiment, the additive includes at least one of antioxidants, light stabilizers, etc. As an example, the antioxidant includes hindered phenolic and phosphite antioxidants in a mass ratio of 1:1 to 2:1. Hindered phenolic antioxidants include, but are not limited to, at least one of pentaerythritol ester, octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanuric acid; phosphite antioxidants include, but are not limited to, at least one of tris(2,4-di-tert-butylphenyl) phosphite and cyclic pentapentanetetramethyldi(2,6-di-tert-butyl-4-methylphenyl phosphite). As an example, the light stabilizer includes, but is not limited to, hindered amine light stabilizers, including, but not limited to, at least one of nickel dibutyldithiocarbamate and triazine-containing hindered amine condensates.

[0023] In one embodiment, the preparation method of the polypropylene composition includes the following steps: mixing the component raw materials, adding them to a screw extruder, melt-blending, extruding and granulating to obtain the polypropylene composition. The screw extruder can be a twin-screw extruder, etc.; the melt-blending temperature can be selected as 170–220°C; and the screw speed can be selected as 350–450 rpm.

[0024] This application also provides the application of the polypropylene composition in the preparation of automotive interior and exterior trim parts, such as door panels, pillars, instrument panels, side skirts, and body kits.

[0025] Compared with the prior art, the beneficial effects of this application are as follows:

[0026] (1) This application ensures that hollow glass microspheres are not easily sheared during the preparation process by adding hollow glass microspheres with specific compressive strength and average particle size to the polypropylene composition, so that when the material flow containing hollow glass microspheres meets during the injection molding process, the non-oriented characteristics of the hollow glass microspheres can be fully utilized, resulting in inconspicuous weld lines and significantly high strength at the weld lines.

[0027] (2) The polypropylene composition of this application has low density, high weld line tensile strength and excellent mechanical properties under the combined effect of the components in a specific amount. It is suitable for preparing automotive interior and exterior parts, such as door panels, pillars, instrument panels, side skirts and body kits. Detailed Implementation

[0028] To better illustrate the purpose, technical solution, and advantages of this invention, the invention will be further described below with reference to specific embodiments and comparative examples. The purpose of this description is to provide a detailed understanding of the invention, not to limit its scope. All other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of this invention. Unless otherwise specified, the experimental reagents and instruments involved in the implementation of this invention are commonly used reagents and instruments.

[0029] Examples and Comparative Examples

[0030] Each embodiment and comparative example provides a polypropylene composition, the composition of which is shown in Tables 1-3. The preparation method includes the following steps: mixing the components evenly and then adding them to a twin-screw extruder for melt mixing, extrusion granulation, and obtaining the polypropylene composition. The melt mixing temperature is 210°C and the screw speed is 400 rpm. Unless otherwise specified, the preparation methods of each embodiment and comparative example use the same steps and process parameters.

[0031] The component information used in the above embodiments and comparative examples is as follows:

[0032] Copolymer polypropylene resin 1: melt flow rate 3g / 10min, PP K8003, Maoming Petrochemical;

[0033] Copolymer polypropylene resin 2: melt flow rate 10g / 10min, PP SP179, Lanzhou Petrochemical;

[0034] Copolymer polypropylene resin 3: melt flow rate 17g / 10min, PP K9017, Formosa Plastics, Taiwan;

[0035] Copolymer polypropylene resin 4: melt flow rate 30g / 10min, PP EP548R, CNOOC Shell;

[0036] Copolymer polypropylene resin 5: melt flow rate 45 g / 10 min, PP 7555KNE2, ExxonMobil;

[0037] Homopolymer polypropylene resin: melt flow rate 20g / 10min, PP MM20-S, Maoming Petrochemical;

[0038] Toughening agent 1: Ethylene-butene copolymer elastomer, POE ENGAGE 7467, Dow Chemical;

[0039] Toughening agent 2: Ethylene-octene copolymer elastomer, POE ENGAGE 8842, Dow Chemical;

[0040] Toughening agent 3: Styrene copolymer elastomer, SEBS G1657, Kraton Chemicals;

[0041] Talc powder 1: obtained by grinding and sieving with HAR T84 talc, with an average particle size of 1μm;

[0042] Talc powder 2: obtained by grinding and sieving with HAR T84 talc, with an average particle size of 3μm;

[0043] Talc powder 3: obtained by grinding and sieving with HAR T84 of Yirui stone, with an average particle size of 5μm;

[0044] Talc powder 4: obtained by grinding and sieving with HAR T84 talc, with an average particle size of 8μm;

[0045] Talc 5: Average particle size 10μm, HAR T84, Yirui Stone;

[0046] Hollow glass microspheres 1: compressive strength 16000Psi, Dn50 20μm, HS46, Zhengzhou Shenglait;

[0047] Hollow glass microspheres 2: compressive strength 28000Psi, Dn50 is 16μm, HS60, Zhengzhou Shenglait;

[0048] Hollow glass microspheres 3: compressive strength 18000Psi, Dn50 12μm, HM20, Zhengzhou Shenglait;

[0049] Hollow glass microspheres 4: compressive strength 30000Psi, Dn50 10μm, HS70, Zhengzhou Shenglait;

[0050] Hollow glass microspheres 5: compressive strength 18000Psi, Dn50 35μm, HL60S, Zhengzhou Shenglait;

[0051] Hollow glass microspheres 6: compressive strength 12000Psi, Dn50 20μm, HM30, Zhengzhou Shenglait;

[0052] Hollow glass microspheres 7: compressive strength 8000Psi, Dn50 25μm, HS42, Zhengzhou Shenglait;

[0053] Hollow glass microspheres 8: compressive strength 12000Psi, Dn50 40μm, HL60, Zhengzhou Shenglait;

[0054] Antioxidants: Antioxidant 1010 and Antioxidant 168, in a mass ratio of 1:1;

[0055] Light stabilizer: nickel dibutyldithiocarbamate.

[0056] The melt flow rates of the above-mentioned copolymer polypropylene resins 1 to 5 and homopolymer polypropylene resin were measured according to the standard GB / T3682.2-2018 "Determination of melt flow rate and melt volume flow rate of thermoplastic plastics" under the conditions of 230℃ / 2.16kg.

[0057] Unless otherwise specified, all components and raw materials used in the embodiments and comparative examples of this application are commercially available, and the same type of components and raw materials are used in each parallel experiment.

[0058] The polypropylene compositions obtained in each embodiment and comparative example were injection molded into standard test strips and subjected to the following tests:

[0059] (1) Cantilever beam notched impact strength: Tested according to ISO 180-2000 "Determination of impact strength of plastics", type A notch, 23℃, injection molding with one end of the plastic, the obtained sample has no weld line;

[0060] (2) Tensile strength of weld line: Tested according to ISO 527-2012 "Determination of tensile properties of plastics", 23℃, tensile rate of 50mm / min, injection molding with both ends, forming a weld line in the middle of the sample, the sample is 1A sample;

[0061] (3) Density: The density of the material was tested according to ISO 1183-2019 "Determination of density of plastics" at 23°C. During injection molding, the material was injected from both ends, and a weld line was formed in the middle of the sample.

[0062] The test results are shown in Table 4.

[0063] Table 1

[0064]

[0065]

[0066] Table 2

[0067]

[0068]

[0069] Table 3

[0070]

[0071] Table 4

[0072]

[0073]

[0074] As shown in Table 4, the density of the polypropylene compositions obtained in each embodiment of this application is 1.045 g / cm³. 3 Below, the notched impact strength (Type A) of the cantilever beam is 20 KJ / m. 2 The above-mentioned weld lines have a tensile strength of over 12MPa, making them suitable for manufacturing automotive interior and exterior trim parts, such as door panels, pillars, instrument panels, side skirts, and body kits.

[0075] As can be seen from Examples 3-6 compared with Comparative Example 1, adding hollow glass microspheres can reduce density and increase the tensile strength of the weld line.

[0076] Comparing Examples 3-6 with Comparative Example 2, it can be seen that the amount of hollow glass microspheres used is too low, and the improvement effect on density and tensile strength of weld lines is not obvious.

[0077] As can be seen from the comparison of Examples 3-6 with Comparative Example 3, when the amount of hollow glass microspheres is too high, not only does it lead to a significant decrease in mechanical properties such as the notched impact strength (Type A) of the cantilever beam, but it also has no significant effect on improving the tensile strength of the weld line.

[0078] A comparison of Examples 3, 7-10, and Comparative Examples 4-5 shows that a low compressive strength of the hollow glass microspheres leads to a significant decrease in the notched impact strength (Type A) of the cantilever beam, with little effect on improving the tensile strength of the weld line. A high particle size (Dn50) of the hollow glass microspheres results in lower notched impact strength (Type A) and weld line tensile strength of the composition. When the compressive strength of the hollow glass microspheres is 15000-25000 Psi and the particle size (Dn50) is 12-20 μm, the resulting composition not only has higher notched impact strength (Type A) and less machine wear, but also lower density and higher weld line tensile strength.

[0079] A comparison of Examples 4 and Examples 12-15 shows that when the average particle size of talc powder is in the range of 2.8-8.2 μm, the resulting composition exhibits higher cantilever beam notched impact strength (Type A) and weld line tensile strength.

[0080] A comparison of Examples 4 with Examples 16-19 shows that when the melt flow rate of polypropylene is in the range of 9.7-30.5 g / 10 min (test conditions 230℃ / 2.16 kg), the resulting composition has higher cantilever beam notched impact strength (Type A) and weld line tensile strength.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention 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 by weight: The hollow glass microbead has a compressive strength of 11000 Psi or more and a particle size Dn50 in the range of 10-35 μm.

2. The polypropylene composition according to claim 1, characterized in that The hollow glass microbead has a compressive strength of 14900-28100 Psi and a particle size Dn50 of 11.8-20.2 μm.

3. The polypropylene composition according to claim 1, wherein The talc has an average particle size of 1-10 μm.

4. The polypropylene composition according to claim 1, wherein The polypropylene resin has a melt flow rate of 9.7-30.5 g / 10 min under the test conditions of 230°C / 2.16 kg.

5. The polypropylene composition according to claim 1, wherein The polypropylene resin comprises at least one of a homopolymer polypropylene resin and a copolymer polypropylene resin.

6. The polypropylene composition according to claim 1, wherein The toughening agent comprises at least one of an ethylene-butene copolymer elastomer, an ethylene-octene copolymer elastomer and a styrene copolymer elastomer.

7. The polypropylene composition according to claim 1, wherein The composition further comprises the following components by weight: an auxiliary 0.18-2.2 parts.

8. The polypropylene composition according to claim 7, wherein the polypropylene composition has a melt flow rate MFR2 (230 °C, 2.16 kg) of 0.5 to 5 g / 10 min. The auxiliary comprises at least one of an antioxidant and a light stabilizer.

9. Use of the polypropylene composition according to any one of claims 1-8 for the preparation of automotive interior and exterior parts.

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