Lightweight PP composite material with high elongation at break and preparation method thereof

Abstract

The invention discloses a light PP composite material with high elongation at break. The light PP composite material is prepared from the following raw materials in parts by weight: 30-45 parts of high-melt-index polypropylene resin, 5-15 parts of medium-melt-index polypropylene resin, 15-25 parts of hollow glass beads, 10-20 parts of a toughening agent, 5-15 parts of a compatilizer, 1.5-6 parts of glass fibers, 1-3 parts of glass fiber powder and 0.1-1.5 parts of an antioxidant. The lightweight PP composite material prepared by the invention has high elongation at break while significantly reducing the density of the polypropylene material, can maintain good mechanical properties, and can be applied to interior and exterior trim parts of automobiles.

Description

Technical Field

[0001] The invention relates to the field of preparation technology modification of high molecular weight polypropylene materials, and in particular to a lightweight PP composite material with higher elongation at break and a preparation method thereof. Background Art

[0002] Polypropylene (PP) is one of the most widely used thermoplastics. It is widely used in automotive interior and exterior decoration parts due to its good performance, easy processing and low price. In recent years, with the rapid development of the automotive industry, higher requirements have been put forward for the application performance of PP materials, especially in terms of lightweight.

[0003] Hollow glass microspheres (HGB) are a new type of lightweight material developed in recent years. Their closed spheres are filled with nitrogen and have the advantages of low density, good thermal stability, and corrosion resistance. In addition, due to their smooth spherical surface, HGB will not produce high stress concentration at the interface between the substrate and the material. Therefore, filling and modifying PP with HGB is expected to achieve the goal of lightweight products. Patent CN 116693974 A discloses a lightweight, low-surface floating fiber long glass fiber reinforced polypropylene composite material and its preparation method and application. By adding long glass fiber and HGB, the floating fiber problem on the surface of the product is effectively improved and the product is lightweight. Patent CN 117048160 A discloses a lightweight automotive interior material and its preparation method. By adding lightweight fillers and foaming molding, the lightweight product is achieved. Patent CN 117264323 A discloses a vacuum glass microsphere / glass fiber mixed reinforced polypropylene material and its preparation method. While reinforcing polypropylene, it ensures that the density of the material is not significantly increased. Generally speaking, the addition of HGB can significantly reduce the density of polypropylene materials, but often reduces the tensile yield strength and elongation at break of the materials. The introduction of glass fiber can increase the tensile yield strength of the material, but it has little effect on the elongation at break of the material. After a large amount of glass fiber is introduced, the density of the material increases, and it is impossible to achieve a balance between low density, strength and elongation at break of the material. Summary of the invention

[0004] The object of the present invention is to provide a lightweight PP composite material with high elongation at break and a preparation method thereof, thereby broadening the application scope of PP materials. The lightweight PP composite material prepared by the present invention has the characteristics of low density, high strength and high elongation.

[0005] The technical solution adopted by the present invention is as follows: A lightweight PP composite material with high elongation at break, comprising the following raw materials in parts by weight: 30 to 45 parts of high melt index polypropylene resin, 5 to 15 parts of medium melt index polypropylene resin, 15 to 25 parts of hollow glass microspheres, 10 to 20 parts of toughening agent, 5 to 15 parts of compatibilizer, 1.5 to 6 parts of glass fiber, 1 to 3 parts of glass fiber powder, and 0.1 to 1.5 parts of antioxidant.

[0006] The melt index of the high melt index polypropylene resin is 70-150 g / 10 min, and that of the medium melt index polypropylene resin is 10-50 g / 10 min. The test conditions of the melt index are 230° C. and a load of 2.16 kg.

[0007] Furthermore, the density of the hollow glass microspheres is 0.32 to 0.60 g / cm 3 It can be a single hollow glass microsphere or a combination of multiple hollow glass microspheres. The particle size of the hollow glass microspheres is 40 to 60 μm, and the compressive strength is 20 to 70 MPa.

[0008] Specifically, the hollow glass microspheres are hollow glass microspheres whose surfaces are pre-treated with a silane coupling agent.

[0009] Specifically, the toughening agent is one or both of POE and EPDM.

[0010] Specifically, the compatibilizer is one or both of maleic anhydride grafted polypropylene and maleic anhydride grafted POE.

[0011] Preferably, the compatibilizer is a mixture of maleic anhydride grafted polypropylene and maleic anhydride grafted POE, and in the mixture, the mass ratio of maleic anhydride grafted polypropylene to maleic anhydride grafted POE is equal to the mass ratio of the polypropylene matrix to the toughening agent.

[0012] Specifically, the glass fiber is an alkali-free glass short fiber with an aspect ratio of 150 to 200 and an average length of 3 to 6 mm.

[0013] Specifically, the glass fiber powder is alkali-free glass fiber powder, and the mesh size of the alkali-free glass fiber powder is 1000-2000 mesh, preferably 1200-1500 mesh.

[0014] Furthermore, the mass ratio of the glass fiber to the glass fiber powder is preferably 1.5 to 5:1, more preferably 2 to 4:1.

[0015] Specifically, the antioxidant is one or more of antioxidant 168, antioxidant 1010, and antioxidant 1076.

[0016] The lightweight PP composite material with high elongation at break provided by the present invention has a density of ≤0.8g / cm 3, elongation at break ≥ 20%, tensile yield strength ≥ 20MPa, flexural modulus ≥ 1200MPa.

[0017] The present invention also provides application of the lightweight PP composite material with high elongation at break in the preparation of automobile interior and exterior trims.

[0018] The lightweight PP composite material with high elongation at break can be prepared by the following method: S1, weighing a high melt index polypropylene resin, a medium melt index polypropylene resin, a toughening agent, a compatibilizer, and an antioxidant according to the ratio, and mixing them evenly with a high-speed stirrer to obtain a mixed raw material A; S2, weighing hollow glass microspheres, glass fibers, and glass fiber powder according to the ratio, and mixing them evenly with a low-speed mixer to obtain a mixed raw material B; the low-speed mixer is used in this step to prevent the hollow glass microspheres from breaking during the stirring process to obtain a mixed filler; S3. Add the mixed raw material A obtained in step S1 from the main feeding port of the twin-screw extruder, and add the mixed filler B obtained in step S2 from the side feeding port. After melting, extrusion, cooling, granulation and drying, the lightweight PP composite material with high elongation at break is obtained.

[0019] Further, the twin-screw extruder in step S3 can adopt a typical extrusion process: conveying section temperature 90~140°C, melting section temperature 160~230°C (preferably 180~220°C), homogenizing section temperature 180~230°C (preferably 200~220°C), die temperature 180~230°C (preferably 200~220°C), and screw speed 100~200rpm.

[0020] In step S2, the rotation speed of the low-speed mixer is generally 30 to 60 rpm.

[0021] The beneficial effects of the present invention are: The present invention uses hollow glass microspheres to reduce the material density, uses glass fiber and glass fiber powder to match high and low aspect ratios, improves the strength and elongation at break of PP, and through the compounding of high melt index PP and low melt index PP, improves the melt index of the product (10-12g / 10min, meeting the normal injection molding requirements), which is conducive to processing, and high melt index PP is conducive to the uniform dispersion of glass microspheres, glass fiber and glass fiber powder, prevents the agglomeration of fillers, and is conducive to improving the elongation at break. Finally, the lightweight PP composite material prepared by the present invention has a high elongation at break while significantly reducing the density of polypropylene materials, can maintain good mechanical properties, expands its application scenarios, and can be used in automotive interior and exterior decorative parts. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is further described in detail below in conjunction with specific implementations, but the protection scope of the present invention is not limited thereto.

[0023] In the embodiment of the present invention, the high melt index polypropylene resin is Yangzi Petrochemical M100 (melt index is 100g / 10min), the medium melt index polypropylene resin is Shanghai Petrochemical M2600R (melt index is 26g / 10min), and the hollow glass microspheres are B-40 (density is 0.40 g / cm 3 , D50 is 55 μm), the toughening agent is Dow POE2300; the compatibilizer is a mixture of maleic anhydride grafted polypropylene and maleic anhydride grafted POE, and the mass ratio of maleic anhydride grafted polypropylene and maleic anhydride grafted POE in the mixture is equal to the mass ratio of polypropylene matrix and toughening agent, the glass fiber is 3 mm long chopped alkali-free glass fiber, the aspect ratio is 150, the particle size of glass fiber powder is 1250-1500 mesh, and the antioxidant is 1010 and 1076 compounded in a ratio of 1:1.

[0024] Embodiment 1: 40 parts of high melt index polypropylene resin, 10 parts of medium melt index polypropylene resin, 15 parts of toughening agent, 10 parts of compatibilizer and 0.5 parts of antioxidant are mixed evenly by a high-speed mixer and added from the main feeding port of a twin-screw extruder; 20 parts of hollow glass microspheres, 3.5 parts of glass fiber and 1.5 parts of glass fiber powder (1250 mesh) are mixed evenly at a speed of 50 rpm by a low-speed mixer and added from the side feeding port; after melting, extrusion, cooling, granulation and drying, a lightweight PP composite material is finally obtained.

[0025] The extrusion conditions are as follows: conveying section temperature 100°C, melting section temperature 220°C, homogenizing section temperature 220°C, die temperature 220°C, and screw speed 120 rpm.

[0026] Embodiment 2: 40 parts of high melt index polypropylene resin, 10 parts of medium melt index polypropylene resin, 15 parts of toughening agent, 10 parts of compatibilizer and 0.5 parts of antioxidant are mixed evenly by a high-speed mixer and added from the main feeding port of a twin-screw extruder; 20 parts of hollow glass microspheres, 4 parts of glass fiber and 1 part of glass fiber powder (1250 mesh) are mixed evenly by a low-speed mixer and added from the side feeding port; after melting, extrusion, cooling, granulation and drying, a lightweight PP composite material is finally obtained.

[0027] Embodiment 3: 40 parts of high melt index polypropylene resin, 10 parts of medium melt index polypropylene resin, 15 parts of toughening agent, 10 parts of compatibilizer and 0.5 parts of antioxidant are mixed evenly by a high-speed mixer and added from the main feeding port of a twin-screw extruder; 20 parts of hollow glass microspheres, 3.5 parts of glass fiber and 1.5 parts of glass fiber powder (1500 mesh) are mixed evenly by a low-speed mixer and added from the side feeding port; after melting, extrusion, cooling, granulation and drying, a lightweight PP composite material is finally obtained.

[0028] Embodiment 4: 40 parts of high melt index polypropylene resin, 10 parts of medium melt index polypropylene resin, 15 parts of toughening agent, 10 parts of compatibilizer and 0.5 parts of antioxidant are mixed evenly by a high-speed mixer and added from the main feeding port of a twin-screw extruder; 20 parts of hollow glass microspheres, 4 parts of glass fiber and 1 part of glass fiber powder (1500 mesh) are mixed evenly by a low-speed mixer and added from the side feeding port; after melting, extrusion, cooling, granulation and drying, a lightweight PP composite material is finally obtained.

[0029] Comparative Example 1: 40 parts of high melt index polypropylene resin, 10 parts of medium melt index polypropylene resin, 15 parts of toughening agent, 10 parts of compatibilizer and 0.5 parts of antioxidant are mixed evenly by a high-speed mixer and added from the main feed port of a twin-screw extruder; 20 parts of hollow glass microbeads are added from the side feed port; after melting, extrusion, cooling, granulation and drying, a lightweight PP composite material is finally obtained.

[0030] Comparative Example 2: 40 parts of high melt index polypropylene resin, 10 parts of medium melt index polypropylene resin, 15 parts of toughening agent, 10 parts of compatibilizer and 0.5 parts of antioxidant are mixed evenly by a high-speed mixer and added from the main feeding port of a twin-screw extruder; 20 parts of hollow glass microbeads and 5 parts of glass fiber are added from the side feeding port; after melting, extrusion, cooling, granulation and drying, a lightweight PP composite material is finally obtained.

[0031] Comparative Example 3: 40 parts of high melt index polypropylene resin, 10 parts of medium melt index polypropylene resin, 15 parts of toughening agent, 10 parts of compatibilizer and 0.5 parts of antioxidant are mixed evenly by a high-speed mixer and added from the main feeding port of a twin-screw extruder; 20 parts of hollow glass microbeads and 10 parts of glass fiber are added from the side feeding port; after melting, extrusion, cooling, granulation and drying, a lightweight PP composite material is finally obtained.

[0032] Comparative Example 4: 40 parts of high melt index polypropylene resin, 10 parts of medium melt index polypropylene resin, 15 parts of toughening agent, 10 parts of compatibilizer and 0.5 parts of antioxidant are mixed evenly by a high-speed mixer and added from the main feeding port of a twin-screw extruder; 20 parts of hollow glass microbeads and 5 parts of glass fiber powder are added from the side feeding port; after melting, extrusion, cooling, granulation and drying, a lightweight PP composite material is finally obtained.

[0033] The proportions of the components of the polypropylene material in Examples 1 to 4 and Comparative Examples 1 to 4 are shown in Table 1 below: Table 1 Raw material composition (by weight) Components Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 High Melt Index Polypropylene Resin 40 40 40 40 40 40 40 40 Medium melt index polypropylene resin 10 10 10 10 10 10 10 10 Hollow glass microspheres 20 20 20 20 20 20 20 20 Toughening agent 15 15 15 15 15 15 15 15 Compatibilizer 10 10 10 10 10 10 10 10 Fiberglass 3.5 4 3.5 4 0 5 10 0 Glass fiber powder 1.5 1 1.5 1 0 0 0 5 Glass fiber powder number 1250 1250 1500 1500 / / / 1250 Antioxidants 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 The test results of the relevant properties of the polypropylene materials in Examples 1 to 4 and Comparative Examples 1 to 4 are shown in Table 2 below: Table 2 Test results Test items Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Tensile yield strength (MPa) 21 23 22 23 15 24 32 16 Elongation at break (%) 25 20 28 22 30 8 6 45 Flexural modulus (MPa) 1250 1300 1300 1350 1200 1400 1800 1220 <![CDATA[Density (g / cm 3 )]]> 0.75 0.76 0.77 0.79 0.74 0.8 0.92 0.79 From the test results of Comparative Example 1, it can be seen that when a large amount of hollow glass microspheres are contained, the material density can be reduced, but at the same time, the tensile yield strength of the material is significantly reduced, and the elongation at break is much lower than that of the non-filled modified PP with the same elastomer content (the elongation at break of the non-filled modified PP with the same elastomer content can reach more than 100%). Therefore, the sample of Comparative Example 1 cannot be used because its yield strength is too low. From the test results of Comparative Examples 2 and 3, it can be seen that after the glass fiber is introduced into the system, the tensile yield strength of the material can be greatly improved. However, with the further decrease in elongation at break and the increase in density, it is impossible to obtain a lightweight PP functional material with low density, high yield strength and high elongation at break. From the results of Comparative Examples 2 and 4, if all the glass fibers are replaced with fiber powder, although the elongation at break can be significantly improved, the strength and modulus of the material will be significantly reduced. This is because the reinforcing effect of fiber powder on the material is far less significant than that of glass fiber. In Examples 1-4, part of the glass fiber is replaced with glass fiber powder, which can increase the tensile yield strength to above 20 MPa while maintaining a relatively low density and a relatively high elongation, and the mesh number of the glass fiber powder becomes larger, which is beneficial to improving the elongation at break, but the strength difference of the material is not large. The present invention improves the elongation at break and the strength by compounding glass fiber and glass fiber powder, and the hollow glass microspheres reduce the material density, so that the material has better comprehensive performance, can be applied to a wider range of scenarios, and meet the requirements of light weight, strength, and toughness of automotive interior and exterior decorative parts.

Claims

1. A lightweight PP composite material with high elongation at break, characterized in that The lightweight PP composite material comprises the following raw materials in parts by weight: 30 to 45 parts of high melt index polypropylene resin, 5 to 15 parts of medium melt index polypropylene resin, 15 to 25 parts of hollow glass microspheres, 10 to 20 parts of toughening agent, 5 to 15 parts of compatibilizer, 1.5 to 6 parts of glass fiber, 1 to 3 parts of glass fiber powder, and 0.1 to 1.5 parts of antioxidant.

2. The lightweight PP composite material with high elongation at break according to claim 1, characterized in that The melt index of the high melt index polypropylene resin is 70-150 g / 10 min, and that of the medium melt index polypropylene resin is 10-50 g / 10 min. The test conditions of the melt index are 230° C. and a load of 2.16 kg.

3. The lightweight PP composite material with high elongation at break according to claim 1, characterized in that The density of the hollow glass microspheres is 0.32 to 0.60 g / cm 3 , particle size is 40 ~ 60 μm.

4. The lightweight PP composite material with high elongation at break according to claim 1, characterized in that The mass ratio of the glass fiber to the glass fiber powder is 1.5-5:

1.

5. The lightweight PP composite material with high elongation at break according to claim 1, characterized in that The toughening agent is one or both of POE and EPDM; the compatibilizer is one or both of maleic anhydride grafted polypropylene and maleic anhydride grafted POE.

6. The lightweight PP composite material with high elongation at break according to claim 1, characterized in that The glass fiber is an alkali-free glass short fiber with an aspect ratio of 150 to 200 and an average length of 3-6 mm; the glass fiber powder is an alkali-free glass fiber powder with a mesh size of 1000-2000 meshes.

7. The lightweight PP composite material with high elongation at break according to claim 1, characterized in that The antioxidant is one or more of antioxidant 168, antioxidant 1010, and antioxidant 1076.

8. The lightweight PP composite material with high elongation at break according to claim 1, characterized in that The lightweight PP composite material with high elongation at break has a density of ≤0.8g / cm 3 , elongation at break ≥ 20%, tensile yield strength ≥ 20MPa, flexural modulus ≥ 1200MPa.

9. Use of the lightweight PP composite material with high elongation at break as claimed in any one of claims 1 to 7 in the preparation of automotive interior and exterior trims.

10. The method for preparing a lightweight PP composite material with high elongation at break according to any one of claims 1 to 7, characterized in that The method is: S1, weighing high melt index polypropylene resin, medium melt index polypropylene resin, toughening agent, compatibilizer, and antioxidant according to proportion, and mixing them evenly with a high-speed stirrer to obtain a mixed raw material A; S2, weighing hollow glass microspheres, glass fibers, and glass fiber powder according to a proportion, and mixing them evenly with a low-speed mixer to obtain a mixed raw material B; S3. Add the mixed raw material A obtained in step S1 from the main feeding port of the twin-screw extruder, and add the mixed filler B obtained in step S2 from the side feeding port. After melting, extrusion, cooling, granulation and drying, the lightweight PP composite material with high elongation at break is obtained.