A lightweight PP composite material with high elongation at break and its preparation method

Abstract

The present invention discloses a lightweight PP composite material with high elongation at break, which comprises 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 microspheres, 10-20 parts of toughening agent, 5-15 parts of compatibilizer, 1.5-6 parts of glass fiber, 1-3 parts of glass fiber powder, and 0.1-1.5 parts of antioxidant. The lightweight PP composite material prepared by the present invention has a high elongation at break while significantly reducing the density of the polypropylene material, and can maintain good mechanical properties at the same time, and can be applied to the interior and exterior decorative parts of automobiles.

Description

Technical Field

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

[0002] Polypropylene (PP) is one of the most widely used thermoplastic plastics, and is widely used in automotive interior and exterior trim parts due to its good performance, easy processing, low price and other characteristics. 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 lightweighting.

[0003] Hollow glass beads (HGB) are a new type of lightweight material developed in recent years. Its sealed spheres are filled with nitrogen, and it has the advantages of low density, good thermal stability, corrosion resistance, etc. In addition, due to its smooth spherical surface, HGB will not generate high stress concentration at the interface with the matrix. Therefore, it is expected to achieve the goal of product lightweighting by filling and modifying PP with HGB. Patent CN 116693974 A discloses a lightweight low-surface floating fiber long glass fiber reinforced polypropylene composite material, its preparation method and application. By adding long glass fibers and HGB, the floating fiber problem on the surface of the product is effectively improved and product lightweighting is achieved. Patent CN 117048160 A discloses an automotive lightweight interior material and its preparation method. By adding lightweight fillers and foaming molding, product lightweighting is achieved. Patent CN 117264323 A discloses a vacuum glass bead / glass fiber hybrid reinforced polypropylene material and its preparation method. While enhancing polypropylene, it ensures that the density of the material does not increase significantly. Generally speaking, the addition of HGB can significantly reduce the density of polypropylene materials, but often makes the tensile yield strength and elongation at break of the materials decrease. By introducing glass fibers, the tensile yield strength of the material can be improved, but it is almost useless for the elongation at break of the material. Moreover, after a large amount of glass fibers are introduced, the density of the material increases again, and the balance of low density, strength and elongation at break of the material cannot be achieved. Summary of the Invention

[0004] The purpose of the present invention is to provide a lightweight PP composite material with a high elongation at break and a preparation method thereof, so as to broaden the application range 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:

[0006] A lightweight PP composite material with a high elongation at break, comprising the following raw materials in parts by weight:

[0007] 30-45 parts of high melt index polypropylene resin, 5-15 parts of medium melt index polypropylene resin, 15-25 parts of hollow glass microspheres, 10-20 parts of toughening agent, 5-15 parts of compatibilizer, 1.5-6 parts of glass fiber, 1-3 parts of glass fiber powder, and 0.1-1.5 parts of antioxidant.

[0008] 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.

[0009] Furthermore, the density of the hollow glass microspheres is 0.32 to 0.60 g / cm 3 The hollow glass microspheres can be a single type or a combination of multiple types. The hollow glass microspheres have a particle size of 40 to 60 μm and a compressive strength of 20 to 70 MPa.

[0010] Specifically, the hollow glass microspheres are hollow glass microspheres whose surfaces are pre-treated with a silane coupling agent.

[0011] Specifically, the toughening agent is one or both of POE and EPDM.

[0012] Specifically, the compatibilizer is one or both of maleic anhydride grafted polypropylene and maleic anhydride grafted POE.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] Specifically, the antioxidant is one or more of antioxidant 168, antioxidant 1010, and antioxidant 1076.

[0018] The lightweight PP composite material with high elongation at break provided by the present invention has a density of ≤0.8g / cm 3, the elongation at break ≥ 20%, the tensile yield strength ≥ 20 MPa, and the flexural modulus ≥ 1200 MPa.

[0019] The present invention also provides the application of the lightweight PP composite material with high elongation at break in the preparation of interior and exterior automotive trim parts.

[0020] The lightweight PP composite material with high elongation at break can be prepared by the following method:

[0021] S1. Weigh the high melt index polypropylene resin, medium melt index polypropylene resin, toughening agent, compatibilizer, and antioxidant according to the above ratios, and mix them evenly through a high-speed mixer to obtain the mixed raw material A;

[0022] S2. Weigh the hollow glass microspheres, glass fibers, and glass fiber powder according to the above ratios, and mix them evenly through a low-speed mixer to obtain the mixed raw material B; In this step, a low-speed mixer is used to prevent the hollow glass microspheres from being broken during the mixing process to obtain the mixed filler;

[0023] 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, and after melting, extrusion, cooling, pelletizing, and drying, the lightweight PP composite material with high elongation at break is prepared.

[0024] Furthermore, the typical extrusion process that can be adopted for the twin-screw extruder in step S3 is: the temperature of the conveying section is 90 - 140 °C, the temperature of the melting section is 160 - 230 °C (preferably 180 - 220 °C), the temperature of the homogenization section is 180 - 230 °C (preferably 200 - 220 °C), the temperature of the die is 180 - 230 °C (preferably 200 - 220 °C), and the screw speed is 100 - 200 rpm.

[0025] In the said step S2, the rotation speed of the low-speed mixer is generally 30 - 60 revolutions per minute.

[0026] The beneficial effects of the present invention are as follows:

[0027] The present invention selects hollow glass microspheres to reduce the material density, uses glass fibers and glass fiber powder for high and low aspect ratio matching to improve the strength and elongation at break of PP, and through the compounding of high melt index PP and low melt index PP, the melt index of the product is increased (10 - 12 g / 10 min, meeting the normal injection molding requirements), which is beneficial to processing, and the high melt index PP is conducive to the uniform dispersion of hollow glass microspheres, glass fibers, and glass fiber powder, preventing the filler from agglomerating, and is beneficial 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 the polypropylene material, can maintain good mechanical properties, expands its application scenarios, and can be used in automotive interior and exterior trim parts. Detailed Embodiments

[0028] The technical solutions of the present invention will be further described in detail below in conjunction with specific embodiments. However, the protection scope of the present invention is not limited thereto.

[0029] In the embodiments of the present invention, the high melt index polypropylene resin is Yangzi Petrochemical M100 (melt index is 100 g / 10 min), the medium melt index polypropylene resin is Shanghai Petrochemical M2600R (melt index is 26 g / 10 min), the hollow glass microspheres are B-40 of Sinosteel Maanshan Institute of Mining New Materials Technology Co., Ltd. (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 in this 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, the glass fiber is a 3 mm long chopped E-glass fiber with an aspect ratio of 150, the particle size of the glass fiber powder is 1250 - 1500 mesh, and the antioxidant is a 1:1 compound of 1010 and 1076.

[0030] Example 1:

[0031] 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 part of antioxidant are mixed evenly by a high-speed mixer and added from the main feeding port of the 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 by a low-speed mixer at a rotation speed of 50 rpm and added from the side feeding port; after melting, extrusion, cooling, pelletizing, and drying, a lightweight PP composite material is finally obtained.

[0032] The extrusion conditions are: the temperature of the conveying section is 100 °C, the temperature of the melting section is 220 °C, the temperature of the homogenizing section is 220 °C, the temperature of the die is 220 °C, and the screw speed is 120 rpm.

[0033] Example 2:

[0034] 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 part of antioxidant are mixed evenly by a high-speed mixer and added from the main feeding port of the 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 and added from the side feeding port; after melting, extrusion, cooling, pelletizing, and drying, a lightweight PP composite material is finally obtained.

[0035] Example 3:

[0036] Mix 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 part of antioxidant evenly through a high-speed mixer, and add them from the main feeding port of the twin-screw extruder; mix 20 parts of hollow glass microspheres, 3.5 parts of glass fiber, and 1.5 parts of glass fiber powder (1500 mesh) evenly through a low-speed mixer, and add them from the side feeding port; after melting, extrusion, cooling, pelletizing, and drying, finally obtain a lightweight PP composite material.

[0037] Example 4:

[0038] Mix 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 part of antioxidant evenly through a high-speed mixer, and add them from the main feeding port of the twin-screw extruder; mix 20 parts of hollow glass microspheres, 4 parts of glass fiber, and 1 part of glass fiber powder (1500 mesh) evenly through a low-speed mixer, and add them from the side feeding port; after melting, extrusion, cooling, pelletizing, and drying, finally obtain a lightweight PP composite material.

[0039] Comparative Example 1:

[0040] Mix 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 part of antioxidant evenly through a high-speed mixer, and add them from the main feeding port of the twin-screw extruder; add 20 parts of hollow glass microspheres from the side feeding port; after melting, extrusion, cooling, pelletizing, and drying, finally obtain a lightweight PP composite material.

[0041] Comparative Example 2:

[0042] Mix 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 part of antioxidant evenly through a high-speed mixer, and add them from the main feeding port of the twin-screw extruder; add 20 parts of hollow glass microspheres and 5 parts of glass fiber from the side feeding port; after melting, extrusion, cooling, pelletizing, and drying, finally obtain a lightweight PP composite material.

[0043] Comparative Example 3:

[0044] Mix 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 part of antioxidant evenly through a high-speed mixer, and add them from the main feeding port of the twin-screw extruder; add 20 parts of hollow glass microspheres and 10 parts of glass fiber from the side feeding port; after melting, extrusion, cooling, pelletizing, and drying, finally obtain a lightweight PP composite material.

[0045] Comparative Example 4:

[0046] 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 were 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 and 5 parts of glass fiber powder were added from the side feeding port; after melting, extrusion, cooling, pelletizing, and drying, a lightweight PP composite material was finally obtained.

[0047] The component ratios of the polypropylene materials in Examples 1 to 4 and Comparative Examples 1 to 4 are shown in Table 1 below:

[0048] Table 1 Raw material composition (by weight)

[0049] Component 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 Glass fiber 3.5 4 3.5 4 0 5 10 0 Glass fiber powder 1.5 1 1.5 1 0 0 0 5 Mesh number of glass fiber powder 1250 1250 1500 1500 / / / 1250 Antioxidant 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5

[0050] 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:

[0051] Table 2 Test results

[0052] Test item 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

[0053] From the test results of Comparative Example 1, it can be seen that in the case of containing a large amount of hollow glass microspheres, the density of the material 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 smaller than that of the unfilled modified PP with the same elastomer content (the elongation at break of the unfilled modified PP with the same elastomer content can reach more than 100%). Therefore, the sample of Comparative Example 1 cannot be applied due to its too low yield strength. From the test results of Comparative Example 2 and Comparative Example 3, it can be known that after introducing glass fiber into the system, the tensile yield strength of the material can be greatly improved. However, along with the further decrease of the elongation at break and the increase of the density, a lightweight PP functional material with low density, high yield strength, and high elongation at break cannot be obtained. From the results of Comparative Example 2 and Comparative Example 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 decreased because the reinforcing effect of fiber powder on the material is far less significant than that of glass fiber. In Examples 1-4, by replacing part of the glass fiber with glass fiber powder, the tensile yield strength can be increased above 20 MPa while maintaining a low density and a high elongation rate. And as the mesh number of the glass fiber powder increases, it is beneficial to improve the elongation at break, but the strength of the material has little difference. By compounding glass fiber and glass fiber powder, the present invention improves the elongation at break and strength, and the hollow glass microspheres reduce the density of the material, making the material have good comprehensive properties and can be applied in a wide range of scenarios to 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 light 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, 0.1 to 1.5 parts of antioxidant; the glass fiber is alkali-free glass short fiber, with a length-to-diameter ratio of 150 to 200 and an average length of 3 - 6 mm; the glass fiber powder is alkali-free glass fiber powder, and the mesh number of the alkali-free glass fiber powder is 1000 - 2000 mesh; the lightweight PP composite material with high elongation at break, density ≤ 0.8 g / cm 3 , elongation at break ≥ 20%, tensile yield strength ≥ 20 MPa, flexural modulus ≥ 1200 MPa; the melt index of the high melt index polypropylene resin is 70 - 150 g / 10 min, the medium melt index polypropylene resin is 10 - 50 g / 10 min, and the test condition for the melt index is 230 °C with a load of 2.16 kg; The toughening agent is one or two of POE and EPDM; the compatibilizer is one or two of maleic anhydride grafted polypropylene and maleic anhydride grafted POE.

2. The light-weight 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 , and the particle size is 40 to 60 μm.

3. The light-weight 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.

4. 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.

5. Application of the light PP composite material with high elongation at break according to any one of claims 1-4 in the preparation of automotive interior and exterior parts.

6. The preparation method of the light-weight PP composite material with high elongation at break according to any one of claims 1 to 4, characterized in that The method is as follows: S1. Weigh high melt index polypropylene resin, medium melt index polypropylene resin, toughening agent, compatibilizer, and antioxidant in proportion, and mix them evenly through a high-speed mixer to obtain mixed raw material A; S2. Weigh hollow glass microspheres, glass fiber, and glass fiber powder in proportion, and mix them evenly through a low-speed mixer to obtain 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, add the mixed filler B obtained in step S2 from the side feeding port, and through melting, extrusion, cooling, pelletizing, and drying, the light PP composite material with high elongation at break is prepared.