Polypropylene composition and use thereof

Abstract

This invention provides a polypropylene composition and its application. By weight, the polypropylene composition comprises 51-73 parts polypropylene resin, 9-21 parts mica, 4-11 parts polyolefin elastomer, 9-21 parts glass fiber, 0.9-5.1 parts compatibilizer, and 0.08-0.22 parts nucleating agent; the mica has a mesh size of 210-390 mesh; and the nucleating agent is a saturated alicyclic dicarboxylic acid soap. This polypropylene composition solves the problem in the prior art that glass fiber reinforced polypropylene materials cannot simultaneously achieve low shrinkage, low warpage, and high toughness.

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] As the most widely used general-purpose plastic, polypropylene (PP) is widely used in the automotive and home appliance industries due to its ease of modification, lightweight, and low cost. Currently, common methods for modifying PP typically include mineral fillers such as talc, calcium carbonate, and wollastonite; toughening with materials like EPDM; fiber reinforcement with glass fiber and carbon fiber; and imparting new properties such as electrical and thermal conductivity to PP through various modifying agents. Among these, glass fiber-modified PP holds an important position in the substitution of many engineering plastics and materials like ABS due to its lower overall cost, significant stiffening effect, and high degree of toughness retention. However, limited by the unique one-dimensional linear structure of glass fiber, glass fiber-reinforced PP often exhibits severe warping problems when replacing materials like ABS due to the significant difference in shrinkage rates between the transverse and longitudinal directions. Therefore, reducing the warping of glass fiber-reinforced PP while maintaining product properties is particularly important.

[0003] Currently, methods to reduce the warpage of glass fiber reinforced polypropylene (PVP) materials often involve using flat glass fibers. However, the significantly higher cost of flat glass fibers compared to ordinary glass fibers severely limits their applicability. Patent CN118027456A discloses a method that reduces the orientation of glass fibers in the PVP matrix through a combination of main and side feeders, thereby reducing product warpage. However, while this method can improve warpage to some extent, it results in a substantial decrease in the product's toughness, making it unsuitable for applications requiring alternatives such as low-shrinkage, low-warpage, and high-toughness materials like ABS.

[0004] Therefore, developing a glass fiber reinforced polypropylene material that meets the requirements of low shrinkage, low warpage, minimal impact on toughness, and still maintains high toughness is an urgent problem to be solved in this field. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a polypropylene composition and its applications. This polypropylene composition solves the problem that existing glass fiber reinforced polypropylene materials cannot simultaneously achieve low shrinkage, low warpage, and high toughness.

[0006] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a polypropylene composition, wherein, by weight, the polypropylene composition comprises 51-73 parts polypropylene resin, 9-21 parts mica, 4-11 parts polyolefin elastomer, 9-21 parts glass fiber, 0.9-5.1 parts compatibilizer and 0.08-0.22 parts nucleating agent; the mica has a mesh size of 210-390 mesh; and the nucleating agent is a saturated alicyclic dicarboxylic acid soap nucleating agent.

[0007] In this invention, firstly, mica possesses high rigidity. Using mica of a specific mesh size allows for secondary shearing of glass fibers during extrusion, thereby reducing the difference in glass fiber orientation along the flow direction and perpendicular to the flow direction within the polypropylene matrix. Secondly, the polyolefin elastomer has toughening and shrinkage-regulating effects, which helps reduce material shrinkage and warpage while improving material toughness. Finally, the nucleating agent can induce the crystallization orientation of polypropylene molecular chains. Specific types of nucleating agents can maintain relatively uniform crystallization of the polypropylene matrix in both the flow direction (longitudinal) and perpendicular direction (transverse), thus making the shrinkage rate of the product more consistent in both directions, further improving shrinkage and warpage during cooling after molding, and simultaneously enhancing product toughness. By combining mica of a specific mesh size, polyolefin elastomer, glass fiber, specific types of nucleating agents, and polypropylene, along with the addition of a compatibilizer, the warpage problem of the product is significantly improved, the shrinkage rate is reduced, and the toughness of the material is enhanced. This allows the polypropylene composition to directly replace ABS materials requiring toughness without the need for mold adjustments.

[0008] In this invention, compared with other conventional nucleating agents, such as sorbitol-based nucleating agents, saturated alicyclic dicarboxylic acid soap-based nucleating agents are used, resulting in materials with lower warpage and better toughness. The mechanism is as follows: Sorbitol-based nucleating agents exhibit oriented crystallization, with inconsistent crystallization in the transverse and longitudinal directions. Therefore, they do not significantly improve warpage and may even lead to increased warpage. In addition, the grain size formed by the crystallization of sorbitol-based nucleating agents is small, resulting in poor toughness.

[0009] In this invention, 51 to 73 parts of polypropylene resin can be, for example, 52 parts, 54 parts, 56 parts, 58 parts, 60 parts, 62 parts, 64 parts, 66 parts, 68 parts, 70 parts, 72 parts, or any range between the above values.

[0010] In this invention, the polypropylene composition contains ≥50% polypropylene resin by mass, for example, 51-72%.

[0011] In this invention, 9 to 21 parts of mica can be, for example, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 parts or any range of the above values.

[0012] In this invention, the mica content in the polypropylene composition is 9-20% by mass.

[0013] In this invention, 4 to 11 parts of polyolefin elastomer can be, for example, 4.5 parts, 5 parts, 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts, 8 parts, 8.5 parts, 9 parts, 9.5 parts, 10 parts, 10.5 parts, or any range of the above values.

[0014] In this invention, the polyolefin elastomer in the polypropylene composition has a mass percentage content of 4.5-10.5%.

[0015] In this invention, 9 to 21 parts of glass fiber, for example, can be 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 parts or any range of the above values.

[0016] In this invention, the mass percentage of glass fiber in the polypropylene composition is 9-20%.

[0017] In this invention, 0.9 to 5.1 parts of compatibilizer can be, for example, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, or any range of the above values.

[0018] In this invention, 0.08 to 0.22 parts of nucleating agent can be, for example, 0.1 parts, 0.12 parts, 0.14 parts, 0.16 parts, 0.18 parts, 0.2 parts, or any range of the above values.

[0019] In this invention, the mesh size of the mica is 210 to 390 mesh, for example, it can be 220 mesh, 240 mesh, 260 mesh, 280 mesh, 300 mesh, 320 mesh, 340 mesh, 360 mesh, 380 mesh or any range between the above values, preferably 270 to 380 mesh, more preferably 275 to 355 mesh.

[0020] In this invention, the mesh count of the mica can be confirmed based on information provided by the manufacturer, or it can be obtained by testing using conventional methods, such as the mesh sieving method.

[0021] Preferably, the polypropylene resin comprises copolymer polypropylene.

[0022] Preferably, at 230°C and 2.16 kg, the melt index of the polypropylene resin is 7~30 g / 10 min, for example, it can be 8 g / 10 min, 10 g / 10 min, 12 g / 10 min, 14 g / 10 min, 16 g / 10 min, 18 g / 10 min, 20 g / 10 min, 22 g / 10 min, 24 g / 10 min, 26 g / 10 min, 28 g / 10 min or any range between the above values.

[0023] In this invention, the melt index of the polypropylene resin can be obtained by testing according to the ISO 1133-1:2022 standard.

[0024] Preferably, the polyolefin elastomer includes ethylene-butene copolymer and / or ethylene-octene copolymer, more preferably ethylene-butene copolymer and ethylene-octene copolymer.

[0025] In this invention, the melt index of the polyolefin elastomer is 1~20g / 10min under the conditions of 190℃ and 2.16kg.

[0026] In this invention, the melt index of the polypropylene resin can be obtained by testing according to the ASTM D1238-23a standard.

[0027] Preferably, the polyolefin elastomer comprises ethylene-butene copolymer and ethylene-octene copolymer, wherein the mass ratio of ethylene-butene copolymer to ethylene-octene copolymer is 1:(0.1~1.5), wherein the specific value of (0.1~1.5) can be, for example, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 1, 1.1, 1.2, 1.3, 1.4 or any range between the above values; to further balance toughness and warpage, a ratio of 1:(0.2~0.8) is more preferred.

[0028] Preferably, the diameter of the glass fiber is 9~14μm, for example, it can be 9.5μm, 10.2μm, 10.5μm, 10.8μm, 11μm, 11.2μm, 11.5μm, 11.8μm, 12μm, 12.5μm, 12.8μm, 13μm, 13.5μm or any range of the above values.

[0029] Preferably, the chopped length of the glass fiber is 2.8 to 4.6 mm, for example, it can be 2.9 mm, 3 mm, 3.2 mm, 3.4 mm, 3.6 mm, 3.8 mm, 4 mm, 4.2 mm, 4.4 mm or any of the above values.

[0030] In this invention, the diameter and chopped length of the glass fiber can be confirmed based on information provided by the manufacturer; or the diameter information can be obtained by testing according to the GB / T 7690.5-2013 standard, and the chopped length information can be obtained by testing according to the JC / T 896-2002 standard.

[0031] Preferably, the compatibilizer includes at least one of maleic anhydride-grafted polypropylene, maleic anhydride-grafted polyolefin elastomer, and glycidyl methacrylate-grafted polypropylene.

[0032] In this invention, the saturated alicyclic dicarboxylic acid soap nucleating agent includes at least one of cyclohexyl dicarboxylic acid salt nucleating agents and hexahydrophthalic acid salt nucleating agents.

[0033] In this invention, the polypropylene composition may also include other additives as needed, including but not limited to lubricants, antioxidants, colorants, flame retardants, etc.

[0034] For example, the lubricant includes, but is not limited to, at least one of erucamide, oleamide, glyceryl monostearate, pentaerythritol stearate, PE wax, ethylene bis-stearamide (EBS), or silicone lubricants.

[0035] Exemplary examples include, but are not limited to, primary antioxidants such as any one or a combination of at least two of the following: 2,6-di-tert-butyl-p-cresol (BHT), 2,2'-methylene-bis(4-ethyl-6-tert-butylphenol), 2,2'-methylene-bis(4-methyl-6-tert-butylphenol), 2,2'-methylene-bis(4-methyl-6-cyclohexylphenol), 2,2'-methylene-bis(4-methyl-6-nonylphenol), octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 1,1,3-tris(5-tert-butyl-4-hydroxy-2-methylphenyl)butane, and pentaerythritol tetra(3,5-di-tert-butyl-4-hydroxyhydrocinnamate). Secondary antioxidants may include, for example, tris(nonylphenyl) phosphite and / or dilauryl thiodipropionate.

[0036] For example, the flame retardant includes, but is not limited to, nitrogen-based flame retardants (such as melamine cyanurate), phosphorus-based flame retardants (such as triphenyl phosphate), and nitrogen-phosphorus composite flame retardants (such as ammonium polyphosphate).

[0037] In this invention, the preparation method of the polypropylene composition includes: adding polypropylene resin, polyolefin elastomer, compatibilizer and nucleating agent into the main feed port of a twin-screw extruder, and adding glass fiber and mica into the side feed port, followed by melting and extrusion to obtain the polypropylene composition; wherein the extrusion temperature is set to 180℃~240℃, the screw speed is 400~700rpm, and the feed rate is 800~900kg / h.

[0038] In a second aspect, the present invention provides a plastic article comprising the polypropylene composition described in the first aspect.

[0039] In this invention, the warpage of the plastic product is ≤1.6mm.

[0040] Preferably, the notched impact strength of the simply supported beam of the plastic product is ≥24 kJ / m. 2 .

[0041] Thirdly, the present invention provides a plastic article according to the first aspect, the plastic article comprising a planar component.

[0042] Preferably, the plastic product includes a spare tire cover and / or a storage box cover.

[0043] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0044] Compared with the prior art, the beneficial effects of the present invention are as follows: The polypropylene composition provided by this invention uses mica of a specific mesh size, polyolefin elastomer, glass fiber, a specific type of nucleating agent and polypropylene compounded together, and a compatibilizer is added at the same time, which greatly improves the warpage problem of polypropylene materials, reduces shrinkage rate and improves the toughness of materials. Detailed Implementation

[0045] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0046] All materials used in this invention can be purchased commercially or prepared using conventional methods. Unless otherwise specified, the materials used in this invention are as follows.

[0047] Table 1 Examples 1-19, Comparative Examples 1-7 Examples 1-19 and Comparative Examples 1-7 each provide a polypropylene composition, and the formulations of the polypropylene compositions are shown in Tables 2-4 by weight.

[0048] Unless otherwise specified, the preparation method of the polypropylene composition in this invention includes the following steps: Polypropylene resin, polyolefin elastomer, compatibilizer, and nucleating agent are added to the main feed port of a twin-screw extruder, while glass fiber and mica powder are added to the side feed port. After melting and extrusion, the polypropylene composition is obtained. The extrusion temperature is set to 180℃~240℃ (zone 1: 180℃, zones 2~9: 240℃, zone 10: 200℃, zone 11: 180℃), the screw speed is 550 rpm, and the feed rate is 850 kg / h.

[0049] Performance testing The obtained polypropylene composition was subjected to the following performance tests.

[0050] 1. Warpage test: The polypropylene composition was injection molded into a 150mm×150mm×2mm square plate at 230℃. After being placed at 23℃ for 48 hours, the square plate was placed on a horizontal surface, the flatness of the sample was observed, and the maximum height of the edge of the square plate from the plane was measured.

[0051] 2. Shrinkage test: Refer to ISO 294-3:2020. After the injection molding shrinkage test sample is conditioned at 23℃ for 48 hours, the length and width of the sample are measured, and the shrinkage rate is calculated according to the theoretical dimensions of the mold cavity.

[0052] 3. Toughness test: Refer to ISO 179-1:2023, injection mold ISO standard mechanical specimen, and measure the notched impact strength of the product in a simply supported beam at 23°C.

[0053] The specific test results are shown in Table 2-4.

[0054] Table 2 Table 3 Table 4 As shown in Tables 2-4, the polypropylene composition provided by this invention uses mica of a specific mesh size, polyolefin elastomer, glass fiber, a specific type of nucleating agent, and polypropylene compounded together, with the addition of compatibilizers and other additives. This allows the polypropylene composition to significantly improve the warpage problem of the product, reduce shrinkage, and improve the toughness of the material while maintaining high strength and rigidity. The material made from the polypropylene composition has a warpage ≤1.6mm and a notched impact strength of a simply supported beam ≥24kJ / m. 2 .

[0055] As can be seen from Examples 1 and 2, with the total amount of the composition remaining unchanged, the polyolefin elastomer content increases, resulting in reduced warpage and improved toughness.

[0056] As can be seen from Examples 2 and 3, with the total amount of the composition remaining unchanged, the mica content increases, resulting in reduced warpage and decreased toughness.

[0057] As can be seen from Examples 2, 8, and 9, with the total amount of the composition remaining unchanged, the glass fiber content increases, resulting in increased warping and decreased toughness.

[0058] As can be seen from Examples 2 and 7, when the type of glass fiber is changed, i.e. the chopped length and diameter are changed, warping increases and toughness decreases.

[0059] As can be seen from Examples 2 and 10 and 11, both a decrease and an increase in the compatibilizer content will lead to increased warping and decreased toughness.

[0060] As can be seen from Examples 2 and 12, an increase in nucleating agent content leads to increased warping and decreased toughness.

[0061] A comparison of Examples 2 and 14-16 with Examples 17 and 18 shows that using a specific ratio of ethylene-butene copolymer and ethylene-octene copolymer is beneficial for balancing the low warpage and high toughness of the polypropylene composition; a higher content of ethylene-butene copolymer results in poorer toughness, but better improvement in warpage; a higher content of ethylene-octene copolymer results in better toughness, but worse warpage.

[0062] As can be seen from Example 2 and Comparative Examples 1 and 2, the polypropylene composition does not contain mica and / or polyolefin elastomers, resulting in increased warpage.

[0063] As can be seen from Example 2 and Comparative Example 3, the warpage increases when EPDM is used instead of polyolefin elastomer.

[0064] As can be seen from Examples 2, 4-6 and Comparative Examples 4, 5, when the mesh count of the mica is not in the range of 210-390 mesh, the warpage increases and / or the toughness deteriorates; when the mesh count is too low, the warpage improvement effect is acceptable, but the toughness is poor; when the mesh count is too high, the toughness can be maintained, but the warpage improvement is poor.

[0065] As can be seen from Examples 2 and Comparative Examples 6 and 7, without adding a nucleating agent, or with adding a non-specific type of nucleating agent, the warpage and shrinkage rate will increase, and the toughness will be poor.

[0066] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A polypropylene composition, characterized in that, The polypropylene composition comprises, by weight, 51-73 parts polypropylene resin, 9-21 parts mica, 4-11 parts polyolefin elastomer, 9-21 parts glass fiber, 0.9-5.1 parts compatibilizer and 0.08-0.22 parts nucleating agent; The mesh size of the mica is 210-390 mesh; The nucleating agent is a saturated alicyclic dicarboxylic acid soap.

2. The polypropylene composition according to claim 1, characterized in that, The mica has a mesh size of 270-380. Preferably, the polypropylene resin comprises copolymer polypropylene.

3. The polypropylene composition according to claim 1, characterized in that, At 230°C and 2.16 kg, the melt index of the polypropylene resin is 7~30 g / 10 min.

4. The polypropylene composition according to claim 1, characterized in that, The polyolefin elastomer includes ethylene-butene copolymer and / or ethylene-octene copolymer, more preferably ethylene-butene copolymer and ethylene-octene copolymer.

5. The polypropylene composition according to claim 4, characterized in that, The polyolefin elastomer includes ethylene-butene copolymer and ethylene-octene copolymer, wherein the mass ratio of ethylene-butene copolymer to ethylene-octene copolymer is 1:(0.1~1.5), more preferably 1:(0.2~0.8).

6. The polypropylene composition according to claim 1, characterized in that, The diameter of the glass fiber is 9~14μm; Preferably, the chopped length of the glass fiber is 2.8~4.6mm.

7. The polypropylene composition according to claim 1, characterized in that, The compatibilizer includes at least one of maleic anhydride-grafted polypropylene, maleic anhydride-grafted polyolefin elastomer, and glycidyl methacrylate-grafted polypropylene.

8. A plastic product, characterized in that, The plastic article comprises the polypropylene composition according to any one of claims 1 to 7.

9. The plastic article according to claim 8, characterized in that, The warpage of the plastic product is ≤1.6mm; Preferably, the notched impact strength of the simply supported beam of the plastic product is ≥24kJ / m. 2 .

10. The plastic article according to claim 8 or 9, characterized in that, The plastic product includes planar components; Preferably, the plastic product includes a spare tire cover and / or a storage box cover.

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