A high-gloss, high-rigidity and high-toughness polypropylene composite material for injection-molded products and a preparation method thereof

Abstract

The present invention discloses a high-gloss, high-rigidity and high-toughness polypropylene composite material for injection molded products, and its preparation and application. The high-gloss, high-strength polypropylene material, in parts by weight, comprises the following raw materials: 40-80 parts of general-purpose polypropylene, 5-10 parts of ultra-high melt index polypropylene, 5-10 parts of ultra-high molecular weight polyethylene powder, 5-30 parts of basalt fiber chopped yarn, 1-5 parts of maleic anhydride grafted polypropylene; 1-5 parts of maleic anhydride grafted polypropylene, 1-5 parts of maleic anhydride grafted POE, 0.3-2 parts of anti-aging additive, basalt fiber chopped yarn is added from the side feed, and the rest is added from the main feed port of a twin-screw extruder, and the product is obtained by melt extrusion and granulation. The high-gloss, high-rigidity and high-toughness polypropylene composite material of the present invention performs well in three dimensions: flexural modulus, simply supported beam notched impact strength, and gloss.

Description

Technical Field

[0001] The present invention relates to the field of polymer materials, and in particular to a high gloss, high rigidity and high toughness polypropylene composite material for injection molded products and a preparation method thereof Background Art

[0002] Polypropylene offers advantages such as low density, low cost, and ease of recycling. However, compared to engineering plastics like polycarbonate and polyamide, its tensile strength and impact toughness are significantly lower, significantly limiting its applications. To improve its mechanical properties, polypropylene is typically reinforced with glass fiber or basalt fiber. However, these reinforced materials can exhibit shortcomings such as surface warping, floating fibers, and low gloss.

[0003] Many existing studies on basalt fiber reinforced polypropylene are based on studying the performance of the system, the compatibility of the system or cost optimization.

[0004] For example, Chinese patent publication CN 110483897 A discloses a basalt fiber-reinforced polypropylene material and its preparation method. The material comprises the following raw materials by weight: 50-80% polypropylene resin, 20-50% basalt fiber, 0.3-0.5% silane coupling agent, 5-10% ethylene-octene copolymer grafted with maleic anhydride, 1-5% polypropylene grafted with maleic anhydride, and 0.5% lubricant. The silane coupling agent, ethylene-octene copolymer grafted with maleic anhydride (POE-g-MAH), and polypropylene grafted with maleic anhydride (PP-g-MAH) are grafted onto the polypropylene resin to modify its surface polarity, thereby increasing the interfacial bond strength between the basalt fiber and the polypropylene. The material is primarily optimized for both performance and cost of the reinforcement system.

[0005] Therefore, further research is still needed to obtain enhanced polypropylene with better surface quality. Summary of the Invention

[0006] In response to the shortcomings in this field, the present invention provides a high-gloss, high-rigidity and high-toughness polypropylene composite material for injection molded products, which has excellent rigidity, toughness and high-gloss surface and can be used in fields with high requirements for rigidity, toughness and gloss.

[0007] A high-gloss, high-rigidity and high-toughness polypropylene composite material for injection molding products, the raw materials comprising, by weight:

[0008] 40~80 parts of general-purpose polypropylene,

[0009] Ultra-high melt index polypropylene 5-10 parts;

[0010] 5-10 parts of ultra-high molecular weight polyethylene powder,

[0011] Basalt fiber chopped yarn 5~30 parts,

[0012] Compound compatibilizer 3~15 parts,

[0013] 0.1~2 parts of anti-aging additives.

[0014] The compound compatibilizer comprises:

[0015] 1~5 parts of maleic anhydride grafted polyethylene,

[0016] Maleic anhydride grafted polypropylene 1~5 parts,

[0017] Maleic anhydride grafted POE 1~5 parts.

[0018] The present invention uses maleic anhydride grafted polyethylene, maleic anhydride grafted polypropylene, and maleic anhydride grafted POE as a compatibilizer, preferably maleic anhydride grafted linear low-density polyethylene, and applies them to a specific polypropylene material formula system. The three compounds not only play a compatibilizing role, but also change the melt rheological properties, thereby affecting the surface gloss. Among them, the maleic anhydride grafted polyethylene accounts for 1 / 4 to 1 / 5 of the total amount of the compounded compatibilizer, and the surface gloss is optimal.

[0019] The general-purpose polypropylene is homopolymer polypropylene and / or copolymer polypropylene, and has a melt flow rate of 1 to 50 g / 10 min under test conditions of 230° C. and 2.16 kg.

[0020] The ultra-high melt index polypropylene is homopolymer polypropylene, and the melt flow rate under the test conditions of 230°C and 2.16 kg is 1500~2500 g / 10 min.

[0021] The ultra-high molecular weight polyethylene powder is polyethylene with a commercial molecular weight greater than 1 million and is in powder form.

[0022] The basalt fiber chopped yarn has a single fiber diameter of 5.5-25 μm, a length of 6-100 mm, and is coated with a silane coupling agent.

[0023] The anti-aging additive is at least one of an antioxidant and a light stabilizer. The antioxidant can be selected from one or more of the group consisting of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, tris(2,4-di-tert-butylphenyl) phosphite, distearyl thiodipropionate, dilauryl thiodipropionate, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanuric acid, and n-octadecanol β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate. The light stabilizer can be selected from BASF's light stabilizer 855. The anti-aging additive is preferably a composite antioxidant system.

[0024] During the injection molding, the injection speed parameter is set to low speed, the injection speed is 10%-25% (the percentage of the highest speed in the injection speed parameter of the injection molding machine itself), and the injection volume does not exceed 3g / s.

[0025] Research has found that when the above conditions are met, the resulting polypropylene material has excellent mechanical properties and high surface gloss.

[0026] The present invention also provides a method for preparing the high-gloss, high-rigidity and high-toughness polypropylene composite material, comprising the steps of:

[0027] (1) Mix and stir the raw materials except basalt fiber chopped yarn in a proportion, the stirring speed is 80-90 rpm, and the stirring time is 10-15 minutes;

[0028] (2) The mixture obtained in step (1) is added from the main feed port of a twin-screw extruder, and chopped basalt fiber yarn is added through a side feed (the side feed position is halfway through the extruder), and the high-gloss, high-rigidity and high-toughness polypropylene composite material is obtained by melt extrusion and granulation.

[0029] In step (2), the feeding speed of the main feed is 20±5 Hz, the temperature of the melt extrusion is 170~240°C, and the main engine speed of the twin-screw extruder is 300~500 rpm.

[0030] In step (2), the specific distribution of the melt extrusion temperature is: 180±10°C in zone 1, 200±10°C in zone 2, 220±10°C in zone 3, and 230±10°C in zones 4 to 9.

[0031] The high-gloss, high-rigidity and high-toughness polypropylene composite material of the present invention is suitable for the field of injection-molded plastic products requiring high gloss, high rigidity and high toughness.

[0032] Compared with the prior art, the main advantages of the present invention include: the present invention uses ultra-high molecular weight polyethylene and basalt fiber chopped yarn as fillers to enhance the rigidity and toughness of polypropylene materials; and creatively adds ultra-high melt index polypropylene with extremely high fluidity. The high-gloss, high-fluidity ultra-high melt index polypropylene is more enriched on the surface of the workpiece, providing a high-gloss, high-smoothness surface; the ultra-high molecular weight polyethylene and basalt fiber chopped yarn system is enriched inside the workpiece, providing the composite material with extremely high mechanical strength and toughness. At the same time, it should be noted that in order to prevent the composite material from delamination, the injection molding speed needs to be kept at a low speed. By compounding compatibilizers and their proportions, it was unexpectedly discovered that the compounding of three common compatibilizers has a huge impact on the surface gloss only when the proportion of maleic anhydride grafted polyethylene in the compounded compatibilizer is within a certain range. The composite material obtained according to the method and requirements disclosed in the present invention performs excellently in the three dimensions of flexural modulus, simply supported beam notched impact strength and gloss. Implementation Method

[0033] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present invention and are not intended to limit the scope of the invention. The operating methods in the following examples where no specific conditions are specified are generally performed under conventional conditions or as recommended by the manufacturer.

[0034] The formulations of Examples 1 to 6 and Comparative Examples 1 to 3 are shown in Table 1;

[0035] Except for the fiber, the other raw materials were stirred in a stirring pot for 10 minutes according to the formula. After being evenly mixed, they were placed in the extruder hopper and melt-blended through a twin-screw extruder. Basalt fiber chopped yarn was added through side feeding. The extrusion temperature was controlled at 170~240℃ to prepare a high-gloss, high-rigidity and high-toughness polypropylene composite material. The sources of various raw materials were selected from those listed in Table 2.

[0036] The resulting polypropylene material was dried in a forced-air drying oven at 85°C for 2 hours and then injection-molded into test bars using an injection molding machine. The injection speed for Examples 1-5 and Comparative Examples 1-3 was 20%, and for Example 6, it was 45%. Flexural modulus testing was performed according to GB / T 9341-178 at a speed of 2 mm / min. Charpy notched impact strength was tested according to GB / T 1043.1 with a pendulum of 3.75 J. Surface gloss was tested according to GB / T 9754 at a 60° angle. The test performance data are shown in Table 3 below, with the data retained to a certain number of significant digits.

[0037] Table 1 Recipe components

[0038] Components Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Comparative Example 3 General purpose polypropylene 65.4 65.4 65.4 65.4 65.4 65.4 72.4 72.4 72.4 Ultra-high melt index polypropylene 7 7 7 7 7 7 0 7 7 Ultra-high molecular weight polyethylene powder 7 7 7 7 7 7 7 7 7 Basalt fiber chopped yarn 15 15 15 15 15 15 15 15 15 Maleic anhydride grafted polyethylene 0.8 1 1.2 1.6 1 1 1 0 1 Maleic anhydride grafted polypropylene 2.1 2 1.9 1.7 2 2 2 2.5 4 Maleic anhydride grafted POE 2.1 2 1.9 1.7 2 2 2 2.5 0 Anti-aging additives 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6

[0039] Table 2 Raw material manufacturer brand

[0040] Components Raw material manufacturer and brand information Polypropylene The melt flow rate of COSCO Shell homopolymer polypropylene HP840N-Z is 12 g / 10 min (230℃, 2.16kg) Ultra-high melt index polypropylene Basel polypropylene MF650Y melt flow rate is 1800 g / 10 min (230℃, 2.16kg) Ultra-high molecular weight polyethylene powder American Celanese ultra-high molecular weight polyethylene grade 2126, molecular weight 1.5 million Maleic anhydride grafted polyethylene Examples 1 to 4, Example 6 and the comparative example selected LLDPE-g-MAH easily soluble CMG5904, and Example 5 selected HDPE-g-MAH easily soluble CMG5804 Maleic anhydride grafted polypropylene Jiayirong MPP 9801 Maleic anhydride grafted POE Cotton KT 915B Basalt fiber chopped yarn Jiangsu Tianlong basalt fiber chopped yarn BCS7-22 diameter 7 μm, silane coupling agent impregnation Anti-aging agent German BASF antioxidants 168, 1076 and light stabilizer 855 are compounded in a mass ratio of 2:3:2

[0041] Table 3 Performance test results

[0042] Performance indicators Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Comparative Example 3 Flexural modulus (MPa) 5017 5321 5412 5583 5354 5386 5311 4810 5853 Simple supported beam notched impact strength (kJ / m2) 30 28 28 27 29 25 26 30 19 Surface gloss (°) 32 60 58 33 42 The surface peeled and delaminated after injection molding and could not be tested. 21 30 29

[0043] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A high gloss, high rigidity and high toughness polypropylene composite material for injection molded products, comprising, by weight: 40~80 parts of general-purpose polypropylene, Ultra-high melt index polypropylene 5~10 parts, 5-10 parts of ultra-high molecular weight polyethylene powder, Basalt fiber chopped yarn 5~30 parts, Compound compatibilizer 3~15 parts, 0.1~2 parts of anti-aging additive; The compound compatibilizer comprises: 1~5 parts of maleic anhydride grafted polyethylene, Maleic anhydride grafted polypropylene 1~5 parts, Maleic anhydride grafted POE 1-5 parts; Maleic anhydride grafted polyethylene accounts for 1 / 4 to 1 / 5 of the total amount of the compounded compatibilizer; The maleic anhydride grafted polyethylene is maleic anhydride grafted linear low-density polyethylene; During the injection molding, the injection speed is 10%-25%, and the injection amount does not exceed 3g / s.

2. The high gloss, high rigidity and high toughness polypropylene composite material for injection molded products according to claim 1, characterized in that: The general-purpose polypropylene is homopolymer polypropylene and / or copolymer polypropylene, and has a melt flow rate of 1 to 50 g / 10 min under test conditions of 230° C. and 2.16 kg.

3. The high gloss, high rigidity and high toughness polypropylene composite material for injection molded products according to claim 1, characterized in that: The ultra-high melt index polypropylene is homopolymer polypropylene, and the melt flow rate under the test conditions of 230°C and 2.16 kg is 1500~2500 g / 10 min.

4. The high gloss, high rigidity and high toughness polypropylene composite material for injection molded products according to claim 1, characterized in that: The ultra-high molecular weight polyethylene powder is polyethylene with a commercial molecular weight greater than 1 million and is in powder form.

5. The high gloss, high rigidity and high toughness polypropylene composite material for injection molded products according to claim 1, characterized in that: The basalt fiber chopped yarn has a single fiber diameter of 5.5-25 μm, a length of 6-100 mm, and is coated with a silane coupling agent.

6. The high gloss, high rigidity and high toughness polypropylene composite material for injection molded products according to claim 1, characterized in that: The anti-aging auxiliary agent is at least one of an antioxidant and a light stabilizer; the antioxidant is selected from one or more of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]pentaerythritol, tris(2,4-di-tert-butylphenyl) phosphite, distearyl thiodipropionate, dilauryl thiodipropionate, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanuric acid, and β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; the light stabilizer is selected from German BASF light stabilizer 855.

7. The method for preparing a high-gloss, high-rigidity and high-toughness polypropylene composite material according to claim 1, comprising the steps of: (1) Mix and stir the raw materials except basalt fiber chopped yarn in a proportion, the stirring speed is 80-90 rpm, and the stirring time is 10-15 minutes; (2) The mixture obtained in step (1) is added from the main feed port of a twin-screw extruder, and the chopped basalt fiber yarn is added through a side feed, the side feed position being one-half of the extruder. After melt extrusion and granulation, the high-gloss, high-rigidity and high-toughness polypropylene composite material is obtained.

8. The method for preparing a high-gloss, high-rigidity and high-toughness polypropylene composite material according to claim 7, characterized in that: The feature is that In step (2), the feeding speed of the main feed is 20±5 Hz, the temperature of the melt extrusion is 170~240°C, and the main engine speed of the twin-screw extruder is 300~500 rpm; in step (2), the specific distribution of the melt extrusion temperature is: 180±10°C in zone 1, 200±10°C in zone 2, 220±10°C in zone 3, and 230±10°C in zones 4 to 9.