PP / PE-HIPS co-extrusion composite sheet and preparation method thereof

Abstract

The invention relates to the technical field of composite sheet processing, in particular to a PPPE-HIPS co-extrusion composite sheet and a preparation method thereof.The PPPE-HIPS co-extrusion composite sheet sequentially comprises a surface layer, a middle layer and a surface layer and is characterized in that the surface layer is prepared from, by weight, polypropylene A, polypropylene B, polypropylene C, a foaming agent and linear low-density polyethylene; the melt index under the test condition of 2.16 kg is 0.2 to 0.5 g / 10min; the melt index of the polypropylene B under the test conditions of 230 DEG C and 2.16 kg is 0.5-0.8 g / 10 min; the melt index of the polypropylene C under the test conditions of 230 DEG C and 2.16 kg is 1-1.5 g / 10 min; the middle layer is prepared from the following components in parts by weight: high-impact polystyrene A, high-impact polystyrene B, high-impact polystyrene C, high-impact polystyrene, filler and rubber; the relative molecular weight of the high impact polystyrene A is 80000 to 120000; the relative molecular weight of the high impact polystyrene B is 150000 to 220000; the relative molecular weight of the high impact polystyrene C is 250000 to 280000; and the relative molecular weight of the high impact polystyrene D is 290000 to 300000.

Description

Technical Field

[0001] This application relates to the technical field of composite sheet processing, and more specifically, to a PP / PE-HIPS co-extruded composite sheet and a preparation method thereof. Background Art

[0002] With the continuous development and popularization of electronic products, the selection and design of their packaging materials become particularly important. Electronic products usually have delicate appearance designs, and are prone to friction and collision during transportation and handling, resulting in scratches on the product surface, affecting the product aesthetics and the user's first impression. In addition, the surfaces of some electronic products, such as screens and lenses, have high requirements for optical performance and touch sensitivity, and scratching may affect these performances and reduce the user experience.

[0003] Among the existing packaging materials, PP (polypropylene) and HIPS (high impact polystyrene) are two commonly used materials. PP sheets have good toughness and impact resistance, and can protect products from damage to a certain extent during transportation. However, PP materials also have some disadvantages. For example, in a low-temperature environment, their impact strength will be significantly reduced, becoming brittle and easily broken, thus affecting the protection effect on electronic products.

[0004] HIPS materials have good processing properties, are easy to mold, and are suitable for large-scale production. Their excellent electrical insulation properties are suitable for the packaging of electronic products. However, HIPS is prone to friction and powder shedding during use, which not only affects the cleanliness of the packaging, but may also cause product surface contamination.

[0005] In order to improve the comprehensive performance of packaging materials, people have tried to use PP and HIPS in combination. However, it is found during the production process that due to the large difference in the molecular structures of PP and HIPS, their compatibility is poor, and surface defects such as delamination and pitting will occur after mixing, affecting product quality and appearance.

[0006] Furthermore, sheets are prepared by the method of multi-layer co-extrusion of PP and HIPS, and then blister processing is carried out according to requirements to obtain corresponding packaging products. This method combines the advantages of the two materials to a certain extent, but still faces some challenges in practical applications.

[0007] Firstly, PP has good toughness and impact resistance, while HIPS has a low elongation at break. The physical properties of the two are too different. In the co-extruded sheet, it is necessary to reasonably design the thickness and proportion of each layer to balance the overall mechanical properties of the sheet, and the requirements are extremely high. If the design is improper, the sheet may be prone to cracking or deformation when subjected to external forces during the processing, especially when a thinner sheet is required, this phenomenon is more likely to occur.

[0008] Secondly, the coefficients of thermal expansion of PP and HIPS are different. When the temperature changes, the degrees of expansion and contraction of each layer are different, which will generate thermal stress inside the sheet, affecting the dimensional stability and heat resistance of the sheet, and causing problems such as warping and cracking during the thermoforming process of the packaging product, thereby affecting the protection effect on electronic products.

[0009] In summary, although PP and HIPS materials have certain application advantages in the packaging of electronic products, their respective disadvantages and compatibility problems when used in combination limit the improvement of their comprehensive performance. Although the method of multi-layer co-extrusion can improve these deficiencies to a certain extent, many technical problems still need to be overcome in the design and processing processes to achieve an ideal packaging effect. Summary of the Invention In order to solve the problems that it is difficult to maintain the balance of mechanical properties and easy to crack during the co-extrusion of PP and HIPS to prepare sheets, and the coefficients of expansion are different, resulting in warping and cracking easily when the temperature changes, the present application provides a PP / PE-HIPS co-extruded composite sheet and its preparation method.

[0011] In a first aspect, the present application provides a PP / PE-HIPS co-extruded composite sheet, adopting the following technical solution: A PP / PE-HIPS co-extruded composite sheet, successively including a surface layer, an intermediate layer, and a surface layer. The surface layer is prepared from the following raw materials by weight: Polypropylene A: 5 - 10 parts Polypropylene B: 10 - 20 parts Polypropylene C: 5 - 8 parts Blowing agent: 4 - 8 parts Linear low-density polyethylene: 5 - 10 parts The melt index of polypropylene A under the test conditions of 230°C and 2.16 kg is 0.2 - 0.5 g / 10 min; The melt index of polypropylene B under the test conditions of 230°C and 2.16 kg is 0.5 - 0.8 g / 10 min; The melt index of polypropylene C under the test conditions of 230°C and 2.16 kg is 1 - 1.5 g / 10 min; The intermediate layer is prepared from the following raw materials by weight: High-impact polystyrene A: 10 - 15 parts High-impact polystyrene B: 5 - 10 parts High-impact polystyrene C: 8 - 12 parts High-impact polystyrene D: 3 - 5 parts Filler: 3 - 5 parts Rubber: 3 - 5 parts; The relative molecular weight of high-impact polystyrene A is 80,000 - 120,000; The relative molecular weight of high impact polystyrene B is 150,000 - 220,000; The relative molecular weight of high impact polystyrene C is 250,000 - 280,000; The relative molecular weight of high impact polystyrene D is 290,000 - 300,000.

[0012] By adopting the above technical solutions, the combination of polypropylene with different melt indexes and linear low density polyethylene on the surface layer, and the combination of high impact polystyrene with different relative molecular weights, fillers and rubbers in the middle layer can effectively balance the overall mechanical properties of the sheet, avoid cracking or deformation problems caused by large differences in the physical properties of PP and HIPS, and maintain good mechanical properties especially when preparing thinner sheets. The thickness of the sheet can be 0.3 - 3.5 cm. Among them, the thicknesses of the surface layer and the middle layer can be adjusted arbitrarily without the need for fine design. After thermoforming, the obtained product has good impact resistance and integrity and is suitable for packaging various electronic products.

[0013] At the same time, through the above formula, the thermal stress caused by temperature changes can be alleviated, the thermal stress caused by the difference in the thermal expansion coefficients of PP and HIPS is reduced, the dimensional stability and heat resistance of the sheet are improved, and problems such as warping and cracking of the sheet during the processing process are reduced, thereby obtaining a complete packaging product.

[0014] The combination of polypropylene and linear low density polyethylene on the surface layer, and the synergistic effect of high impact polystyrene and rubber and other components in the middle layer can effectively improve the wear resistance of the sheet, reduce the situation of friction powder falling off during use, maintain the cleanliness of the packaging, and avoid product surface contamination.

[0015] The reasonable design of the surface layer and the middle layer enables the entire sheet to have good impact resistance, can effectively protect electronic products during transportation and handling, prevent scratches or damage to the product surface caused by external forces such as collision and friction, and enhance the user's first impression and usage experience of the product.

[0016] Preferably, the polypropylene A is at least one of isotactic polypropylene, atactic polypropylene and syndiotactic polypropylene.

[0017] Preferably, the polypropylene B is at least one of isotactic polypropylene, atactic polypropylene and syndiotactic polypropylene.

[0018] Preferably, the polypropylene C is at least one of isotactic polypropylene, atactic polypropylene and syndiotactic polypropylene.

[0019] By adopting the above technical solution, through the reasonable combination of isotactic, atactic and syndiotactic polypropylene, as well as polypropylenes A, B, and C with different melt indices, the surface layer can improve wear resistance, heat resistance and processing performance while maintaining good mechanical properties, thus effectively solving the problems of difficult balance of mechanical properties, easy cracking, warping and cracking caused by different coefficients of thermal expansion when preparing sheets by co-extrusion of PP and HIPS, and improving the overall performance and quality of the sheets.

[0020] Preferably, the linear low density polyethylene has a melt index of 1-2 g / 10 min under the test conditions of 230 °C and 2.16 kg.

[0021] By adopting the above technical solution, LLDPE has good flexibility and impact resistance. In the composite sheet, the addition of LLDPE can significantly improve the flexibility and impact resistance of the surface layer, enabling the sheet to better absorb and disperse energy when subjected to external force impact, reducing the risk of damage. The addition of LLDPE can, to a certain extent, balance the rigidity of polypropylene and the toughness of high impact polystyrene, making the composite sheet have good flexibility while maintaining high strength.

[0022] Preferably, the foaming agent is at least one of azo compounds, bicarbonates, carbonates and bicarbonates.

[0023] By adopting the above technical solution, a large number of tiny air bubbles are formed inside the surface layer, thereby reducing the density of the sheet. At the same time, it makes the packaging material lighter and more convenient for transportation and use. And the existence of tiny air bubbles increases the heat insulation and buffering performance of the sheet. The improvement of heat insulation means that the packaging material can better protect electronic products from the influence of temperature changes and reduce product damage caused by temperature fluctuations. The enhancement of buffering performance can effectively absorb and disperse external force impact and better protect electronic products from collision damage during transportation and handling.

[0024] Preferably, the filler is at least one of zinc oxide, silicon dioxide, zinc carbonate, carbon black, kaolin, montmorillonite, diatomaceous earth, acicular wollastonite and ceramic powder.

[0025] By adopting the above technical solution, the type of filler is optimized to further improve the strength and hardness of the inner layer, enhance the anti-deformation ability of the sheet, and at the same time be able to balance the thermal expansion difference between PP and HIPS, reduce the thermal stress generated by temperature changes, and improve the dimensional stability of the sheet.

[0026] Preferably, the rubber is at least one of polybutadiene, ethylene-propylene rubber, styrene-butadiene rubber and ethylene propylene diene monomer rubber.

[0027] By adopting the above technical solutions, optimizing the type of rubber, the flexibility of the rubber molecular chain and the interaction with materials such as HIPS can enhance the adhesion between the inner layer and the outer layer, reduce the risk of delamination, and improve the overall stability of the sheet. At the same time, the above rubber has good elasticity and toughness, can absorb and disperse external force impacts, enhance the impact resistance of the inner layer, and reduce the risk of damage caused by collisions. Moreover, the above rubber endows the inner layer with excellent flexibility and elasticity, enabling it to maintain good performance at different ambient temperatures, not easily becoming brittle, and improving the adaptability of the packaging material.

[0028] In a second aspect, the present application provides a method for preparing a PP / PE-HIPS coextruded composite sheet, adopting the following technical solutions: A method for preparing a PP / PE-HIPS coextruded composite sheet, comprising the following preparation steps: S1. Mix polypropylene A, polypropylene B, polypropylene C, linear low-density polyethylene and a foaming agent to obtain mixture A; S2. Mix high-impact polystyrene A, high-impact polystyrene B, high-impact polystyrene C, high-impact polystyrene D, a filler and rubber to obtain mixture B; S3. Divide mixture A into two parts, and then add the two divided parts of mixture A and mixture B to three extruders respectively. The melts extruded by the three extruders are compounded in a coextrusion head to obtain a PP / PE-HIPS coextruded composite sheet.

[0029] By adopting the above technical solutions, through the method of multi-layer coextrusion, the material advantages of the surface layer and the intermediate layer are combined to form a composite sheet with excellent comprehensive performance. The surface layer provides good impact resistance and wear resistance, and the intermediate layer provides high impact resistance and dimensional stability. The overall sheet performs excellently in terms of mechanical properties, thermal stability, wear resistance and cleanliness. This method for preparing a PP / PE-HIPS coextruded composite sheet effectively solves the problems such as difficult balance of mechanical properties, easy cracking, warping and cracking caused by different thermal expansion coefficients when preparing sheets by coextruding PP and HIPS through reasonable material selection and process design.

[0030] In summary, the present application has the following beneficial effects: 1. Excellent mechanical properties: Through the reasonable design of the surface layer and the intermediate layer, the composite sheet has good impact resistance, flexibility and strength. The combination of polypropylene and linear low-density polyethylene in the surface layer improves the impact resistance and flexibility, and components such as high-impact polystyrene and rubber in the intermediate layer further enhance the impact resistance and flexibility. At the same time, the filler improves the hardness and rigidity. This comprehensive mechanical property enables the sheet to effectively absorb and disperse energy when subjected to external force impacts, reducing the risk of cracking and deformation, and is especially suitable for the packaging of electronic products that require high mechanical properties.

[0031] 2. Convenient to use: Through the formula in this application, the surface layer and the intermediate layer can be of any thickness. Without the need for highly precise design of the thickness of the intermediate layer and the surface layer, a sheet material with excellent mechanical properties, stability, impact resistance, etc. can be obtained, overcoming problems such as unbalanced mechanical properties and warping caused by differences in the coefficient of thermal expansion that may occur in single materials and simple coextrusion. It provides a packaging material with excellent comprehensive performance, can better meet the high requirements of electronic product packaging, effectively protect the safety of products during transportation and use, and at the same time maintain the cleanliness and beauty of the packaging. Detailed implementation manners Examples

[0032] Polybutadiene was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., and the product model is P478063.

[0033] Ethylene-propylene rubber was purchased from Jilin Chemical Industry Company, China National Petroleum Corporation, and the grade is 1035.

[0034] Styrene-butadiene rubber was purchased from Jining Tangyi Chemical Co., Ltd., and the model is P28502115.

[0035] Example 1 A preparation method of a PP / PE-HIPS coextruded composite sheet, which is prepared by the following method: S1. Mix 500 g of polypropylene A, 1000 g of polypropylene B, 500 g of polypropylene C, 500 g of linear low-density polyethylene, and 400 g of blowing agent (azodicarbonamide) to obtain mixture A; S2. Mix 1000 g of high-impact polystyrene A, 500 g of high-impact polystyrene B, 800 g of high-impact polystyrene C, 300 g of high-impact polystyrene D, 300 g of filler (silica), and 300 g of rubber (polybutadiene) to obtain mixture B; S3. Divide mixture A into 2 parts, and then add the divided two parts of mixture A and mixture B to three extruders respectively. The melts extruded by the three extruders are compounded in the coextrusion head to obtain a PP / PE-HIPS coextruded composite sheet with a surface layer thickness of 0.5 cm and an intermediate layer thickness of 2.5 cm.

[0036] The melt index of polypropylene A (isotactic polypropylene) under the test conditions of 230 °C and 2.16 kg is 0.2 g / 10 min; The melt index of polypropylene B (syndiotactic polypropylene) under the test conditions of 230 °C and 2.16 kg is 0.5 g / 10 min; The melt index of polypropylene C (atactic polypropylene) under the test conditions of 230 °C and 2.16 kg is 1 g / 10 min; The molecular weight of high impact polystyrene A is 80,000; The molecular weight of high impact polystyrene B is 150,000; The molecular weight of high impact polystyrene C is 250,000; The molecular weight of high impact polystyrene D is 290,000; The melt index of linear low density polyethylene under the test conditions of 230 °C and 2.16 kg is 1 g / 10 min.

[0037] The difference between Example 2-3 and Example 1 lies in that the types, dosages and parameters of the raw materials for preparing the P / PE-HIPS co-extruded composite sheet are different, and the specific differences are shown in Table 1: Table 1 Types, dosages and parameters of raw materials for preparing P / PE-HIPS co-extruded composite sheets in Examples 1-3 Example 4 A method for preparing a PP / PE-HIPS co-extruded composite sheet. The difference between this example and Example 1 is that the surface layer thickness is 0.05 cm and the intermediate layer thickness is 0.2 cm.

[0038] Example 5 A method for preparing a PP / PE-HIPS co-extruded composite sheet. The difference between this example and Example 1 is that the surface layer thickness is 1 cm and the intermediate layer thickness is 1 cm.

[0039] Comparative Example Comparative Example 1 A method for preparing a PP / PE-HIPS co-extruded composite sheet. The difference between this comparative example and Example 1 is that low density polyethylene is used instead of linear low density polyethylene.

[0040] The melt index of low density polyethylene under the test conditions of 230 °C and 2.16 kg is 2.0 g / 10 min.

[0041] Comparative Example 2 A method for preparing a PP / PE-HIPS co-extruded composite sheet. The difference between this comparative example and Example 1 is that low density polyethylene is used instead of polypropylene A.

[0042] The melt index of low density polyethylene under the test conditions of 230 °C and 2.16 kg is 2.0 g / 10 min.

[0043] Comparative Example 3 A preparation method of a PP / PE-HIPS co-extruded composite sheet. The difference between this comparative example and Example 1 is that the dosage of polypropylene A is 1000 g, the dosage of polypropylene B is 0, and the dosage of polypropylene C is 1000 g.

[0044] Comparative Example 4 A preparation method of a PP / PE-HIPS co-extruded composite sheet. The difference between this comparative example and Example 1 is that the dosage of polypropylene A is 0 g, the dosage of polypropylene B is 667 g, and the dosage of polypropylene C is 1333 g.

[0045] Comparative Example 5 A preparation method of a PP / PE-HIPS co-extruded composite sheet. The difference between this comparative example and Example 1 is that high-density polyethylene is used instead of high-impact polystyrene A.

[0046] The specific gravity of high-density polyethylene is 0.952 g / cm 3 , and its melt index under the test conditions of 230 °C and 2.16 kg is 2.0 g / 10 min.

[0047] Comparative Example 6 A preparation method of a PP / PE-HIPS co-extruded composite sheet. The difference between this comparative example and Example 1 is that the dosage of high-impact polystyrene A is 0 g, the dosage of high-impact polystyrene B is 0, the dosage of high-impact polystyrene C is 1891 g, and the dosage of high-impact polystyrene D is 709 g.

[0048] Comparative Example 7 A preparation method of a PP / PE-HIPS co-extruded composite sheet. The difference between this comparative example and Example 1 is that the dosage of high-impact polystyrene A is 1733 g, the dosage of high-impact polystyrene B is 867 g, the dosage of high-impact polystyrene C is 0 g, and the dosage of high-impact polystyrene D is 0 g.

[0049] Comparative Example 8 A preparation method of a PP / PE-HIPS co-extruded composite sheet. The difference between this comparative example and Example 1 is that the dosage of high-impact polystyrene A is 0 g, the dosage of high-impact polystyrene B is 1400 g, the dosage of high-impact polystyrene C is 600 g, and the dosage of high-impact polystyrene D is 600 g.

[0050] Comparative Example 9 A preparation method of a PP / PE-HIPS co-extruded composite sheet. The difference between this comparative example and Example 1 is that high-density polyethylene is used instead of rubber.

[0051] The specific gravity of high-density polyethylene is 0.952 g / cm 3, the melt index under the test conditions of 230 °C and 2.16 kg is 2.0 g / 10 min.

[0052] Detection method / Test method Dart impact strength: Refer to ASTM D1708-03 Method B.

[0053] Adjust the surface layer thickness in Comparative Examples 1, 2, 5, 6 and 9 to 0.05 cm and the intermediate layer thickness to 0.2 cm to obtain Comparative Examples 10-14. Blister experiment: The PP / PE-HIPS co-extruded composite sheets prepared in Examples 1-5 and Comparative Examples 1-14 were subjected to blistering to form packaging boxes, and whether there were cracks, warping or deformation on the packaging boxes was observed. The experimental data are shown in Table 2: Table 2 Experimental data of Examples 1-5 and Comparative Examples 1-14 Example or Comparative Example Dart Impact Strength (g) Blister Experiment Example 1 1100 Intact Example 2 1200 Intact Example 3 1340 Intact Example 4 1100 Intact Example 5 1100 Intact Comparative Example 1 900 Intact Comparative Example 2 1020 Intact Comparative Example 3 960 Intact Comparative Example 4 860 Warpage Comparative Example 5 980 Deformation Comparative Example 6 910 Cracking Comparative Example 7 890 Cracking Comparative Example 8 900 Cracking Comparative Example 9 1010 Cracking Comparative Example 10 / Deformation Comparative Example 11 / Deformation Comparative Example 12 / Cracking Comparative Example 13 / Cracking Comparative Example 14 / Deformation From the experimental data of Example 1 and Comparative Examples 1-4, it can be seen that by using polypropylene with different melt indexes in combination with linear low-density polyethylene in a specific ratio to prepare the PP / PE-HIPS co-extruded composite sheet, the sheet can be ensured to have good resistance to mechanical impact, and there will be no cracks, warping or deformation during the processing.

[0054] From the experimental data of Example 1 and Comparative Examples 5-9, it can be seen that by using high-impact polystyrene with different molecular weights in combination with rubber in a specific ratio to prepare the PP / PE-HIPS co-extruded composite sheet, the sheet can be ensured to have good resistance to mechanical impact, and there will be no cracks, warping or deformation during the processing.

[0055] From the experimental data of Comparative Examples 1, 2, 5, 6 and 9, Comparative Examples 10-14, Example 1, and Examples 4-5, it can be seen that the sheet with different thicknesses can be prepared by the formula of the present application. Without being limited by the thickness, the sheet can also be ensured to have good resistance to mechanical impact, and there will be no cracks, warping or deformation during the processing.

[0056] This specific embodiment is only an explanation of the present application, and it is not a limitation of the present application. Those skilled in the art can make modifications to this embodiment without creative contributions according to needs after reading this specification, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A PP / PE-HIPS co-extruded composite sheet, comprising a surface layer, an intermediate layer and a surface layer in sequence, characterized in that: The surface layer is prepared from the following raw materials in parts by weight: Polypropylene A 5-10 parts Polypropylene B 10-20 parts Polypropylene C 5-8 parts 4-8 parts of foaming agent Linear low density polyethylene 5-10 parts The melt index of polypropylene A under the test conditions of 230°C and 2.16 kg is 0.2-0.5 g / 10 min; The melt index of polypropylene B under the test conditions of 230°C and 2.16 kg is 0.5-0.8 g / 10 min; The melt index of polypropylene C under the test conditions of 230°C and 2.16 kg is 1-1.5 g / 10 min; The intermediate layer is prepared from the following parts by weight: High impact polystyrene A 10-15 parts High impact polystyrene B 5-10 parts High impact polystyrene C 8-12 parts High impact polystyrene D 3-5 parts 3-5 servings of filling 3-5 parts of rubber; The relative molecular weight of high impact polystyrene A is 80000-120000; The relative molecular weight of high impact polystyrene B is 150000-220000; The relative molecular weight of high impact polystyrene C is 250000-280000; The relative molecular weight of high impact polystyrene D is 290,000-300,000.

2. The PP / PE-HIPS co-extruded composite sheet according to claim 1, characterized in that: The polypropylene A is at least one of isotactic polypropylene, atactic polypropylene and syndiotactic polypropylene.

3. The PP / PE-HIPS co-extruded composite sheet according to claim 1, characterized in that: The polypropylene B is at least one of isotactic polypropylene, atactic polypropylene and syndiotactic polypropylene.

4. The PP / PE-HIPS co-extruded composite sheet according to claim 1, characterized in that: The polypropylene C is at least one of isotactic polypropylene, atactic polypropylene and syndiotactic polypropylene.

5. The PP / PE-HIPS co-extruded composite sheet according to claim 1, characterized in that: The linear low-density polyethylene has a melt index of 1-2 g / 10 min under the test conditions of 230° C. and 2.16 kg.

6. The PP / PE-HIPS co-extruded composite sheet according to claim 1, characterized in that: The foaming agent is at least one of an azo compound, a carbonate and a bicarbonate.

7. The PP / PE-HIPS co-extruded composite sheet according to claim 1, characterized in that: The filler is at least one of zinc oxide, silicon dioxide, zinc carbonate, carbon black, kaolin, montmorillonite, diatomaceous earth, needle-shaped wollastonite and ceramic powder.

8. The PP / PE-HIPS co-extruded composite sheet according to claim 1, characterized in that: The rubber is at least one of polybutadiene, ethylene-propylene rubber, styrene-butadiene rubber and ethylene-propylene-diene rubber.

9. A method for preparing the PP / PE-HIPS co-extruded composite sheet as claimed in any one of claims 1 to 8, characterized in that: The method comprises the following preparation steps: S1, mixing polypropylene A, polypropylene B, polypropylene C, linear low-density polyethylene and a foaming agent to obtain a mixture A; S2, mixing high impact polystyrene A, high impact polystyrene B, high impact polystyrene C, high impact polystyrene D, a filler and rubber to obtain a mixture B; S3. Divide the mixture A into two parts, and then add the two parts of mixture A and mixture B into three extruders respectively. The melts extruded by the three extruders are compounded in a co-extrusion head to obtain a PP / PE-HIPS co-extruded composite sheet.

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