High-transparency high-impact polypropylene composition and process for the preparation thereof

Abstract

The application belongs to the technical field of polymer materials, and particularly relates to a high-transmittance high-impact polypropylene composition and a preparation method thereof. The high-transmittance high-impact polypropylene composition is prepared from the following raw materials in percentage by weight: polypropylene resin: 59.2-89.85%; polyethylene resin: 10-25%; elastomer: 0-10%; light diffuser: 0-5%; nucleating agent: 0.05-0.5%; and antioxidant: 0.1-0.3%. The polypropylene resin is an impact copolymer polypropylene, the rubber phase content is 14-18%, and the ratio of the intrinsic viscosity of the rubber phase to the polypropylene resin is 1-1.2; the polyethylene resin is prepared from a metallocene catalyst; and the elastomer is a copolymer of propylene and ethylene. The prepared polypropylene composition has excellent physical properties such as high transmittance, high impact, high haze and high strength, and can meet the requirements of light-transmitting components in various fields; and meanwhile, the polypropylene composition has strong processing adaptability.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a high-transmittance, high-impact polypropylene composition and its preparation method. Background Technology

[0002] Polypropylene (PP) possesses advantages such as low density, excellent mechanical properties, good heat resistance, and high chemical stability, making it one of the most widely used general-purpose plastics. It is widely used in home furnishings, automobiles, piping, and medical fields. As the application of polypropylene continues to expand, the requirements for its performance are constantly increasing, including high rigidity, high impact resistance, and high light transmittance. Some specialized fields require polypropylene to have high light transmittance, low haze, high impact resistance, and good processability.

[0003] Polypropylene mainly exists in three types: homopolymer, random copolymer, and impact copolymer. Homopolymer and random copolymer polypropylene have high light transmittance but low impact strength, while impact copolymer polypropylene has high impact strength but poor light transmittance. To obtain polypropylene with high light transmittance, low haze, and high impact strength, current technologies mainly modify homopolymer and random copolymer polypropylene by adding ethylene propylene diene monomer (EPDM), ethylene propylene diene monomer (EPDM), POE, and inorganic modifiers. However, from the perspective of modification effects, it is difficult to achieve a good balance between light transmittance and impact strength. Adding inorganic fillers further reduces impact strength and affects the hygiene of the material, thus limiting its use in food, medical, and human contact applications. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a high-transmittance, high-impact polypropylene composition, which possesses excellent physical properties such as high transmittance, high impact resistance, high haze, and high strength, and can meet the requirements of various fields for light-transmitting components; at the same time, it has strong processing adaptability and can be widely used in injection molding, compression molding, and other processes to produce products with high strength, impact resistance, and easy molding.

[0005] Another objective of this invention is to provide a method for preparing a high-transmittance, high-impact polypropylene composition that is scientific, reasonable, simple, and easy to implement.

[0006] The technical solution adopted in this invention is as follows:

[0007] The high light transmittance and high impact resistance polypropylene composition comprises the following raw materials in weight percentages:

[0008] Polypropylene resin: 59.2-89.85%;

[0009] Polyethylene resin: 10-25%;

[0010] Elastomer: 0-10%;

[0011] Light diffusing agent: 0-5%;

[0012] Nucleating agent: 0.05-0.5%;

[0013] Antioxidant: 0.1-0.3%;

[0014] The polypropylene resin is an impact-resistant copolymer polypropylene, and the intrinsic viscosity ratio of the rubber phase to the polypropylene resin is 1-1.2.

[0015] The polyethylene resin was prepared by catalysis using a metallocene catalyst;

[0016] The elastomer is a copolymer of propylene and ethylene or butene.

[0017] The polypropylene resin has a melt flow rate of 1-30 g / 10 min (2.16 kg weight, 230 °C); a copolyethylene monomer content of 4-7%, preferably 5-6%; and a weight-average molecular weight of (15-50) × 10⁻⁶. 4 The molecular weight distribution is 3-7, preferably 4-6; the polypropylene resin can optimize the compatibility between the rubber phase and the continuous polypropylene phase, as well as the optical properties of the rubber phase, while ensuring that it has better impact strength than homopolymer and random copolymer polypropylene.

[0018] The polyethylene resin is linear ultra-low density polyethylene, and the comonomer is hexene; the melt flow rate is 1-5 g / 10 min (with a weight of 2.16 kg and a temperature of 190 °C); the monomer bonding content is 1-6%, preferably 3-5%; and the density is 0.910-0.915 g / cm³. 3 The molecular weight distribution is 2-7, preferably 3-5; the rubber phase content is 14-18%.

[0019] The elastomer has a melt flow rate of 1-10 g / 10 min, preferably 5-7 g / 10 min; and a density of 0.860-0.890 g / cm³. 3 The preferred dosage is 4-7%.

[0020] The light diffusing agent is an organosilicon powder, the main component of which is a vinyl polydimethylsiloxane / polymethylsiloxane sesquioxane crosslinked polymer; the average particle size is 2-10 μm, preferably 2-5 μm.

[0021] The nucleating agent is one of sorbitol-based nucleating agents, phosphate-based nucleating agents, or benzoate-based nucleating agents, with a preferred dosage of 0.2-0.4%.

[0022] The antioxidant is a compound antioxidant composed of one of the following: phenolic antioxidants and phosphite antioxidants or thioester antioxidants (such as DLTP or DSTP), with a compounding ratio of 1:1.

[0023] The preparation method of the high light transmittance and high impact resistance polypropylene composition is as follows: the raw materials of the formulation components are mixed and stirred, and then melt-extruded, stretched, and pelletized by a twin-screw extruder to obtain the high light transmittance and high impact resistance polypropylene composition.

[0024] The mixing and stirring time is 4-6 minutes.

[0025] The temperature of the twin-screw extruder is 150-230℃.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] The high-transmittance, high-impact polypropylene composition prepared by this invention has a density of 0.89-0.91 g / cm³. 3 The notched impact strength of a simply supported beam is 40-60 kJ / m. 2 This polypropylene material boasts a flexural modulus greater than 900 MPa, a light transmittance (2mm thick sheet) greater than 70%, and high haze. Furthermore, it exhibits broad processing adaptability, suitable for injection molding, compression molding, blow molding, and other processing methods. It can be used to produce lampshades, light boxes, and translucent yet opaque components for automobiles and motorcycles. The resulting products are characterized by high strength, good impact resistance, and ease of processing and molding. They can meet the demands for high light transmittance, high impact resistance, and high haze polypropylene products in various fields, including daily necessities, industrial products such as light boxes, automotive and motorcycle components requiring light transmission, decorative parts, and translucent components in medical devices. Therefore, it has broad application prospects. Detailed Implementation

[0028] The present invention will be further described below with reference to the embodiments, but these embodiments do not limit the implementation of the present invention.

[0029] Unless otherwise specified, the raw materials used in the examples and comparative examples are all commercially available materials, and the process methods used in the examples and comparative examples are all conventional methods in the art.

[0030] The following is a description of some of the raw materials used in the examples and comparative examples:

[0031] Phosphate nucleating agent NA-11: purchased from Adico (China) Investment Co., Ltd.;

[0032] Sorbitol nucleating agent NX8000 was purchased from Milliken.

[0033] Example 1

[0034] The high light transmittance and high impact resistance polypropylene composition comprises the following raw materials in weight percentages:

[0035] Polypropylene resin 1: 80.6%;

[0036] Polyethylene resin 1:10%;

[0037] Elastomer 1: 9%;

[0038] Nucleating agent 1: 0.2%;

[0039] Antioxidant: 0.2%.

[0040] The polypropylene resin 1 is an impact-resistant copolymer polypropylene with a melt flow rate of 10 g / 10 min (weight 2.16 kg, temperature 230℃); the content of copolyethylene monomer is 5.1%; and the weight-average molecular weight is 23 × 10⁻⁶. 4 The molecular weight distribution is 6; the rubber phase content is 15.6%; the intrinsic viscosity ratio of the rubber phase to the polypropylene resin is 1.05; and the size of the rubber phase is 300±100nm.

[0041] The polyethylene resin 1 is linear ultra-low density polyethylene, obtained by catalysis with a metallocene catalyst, and the comonomer is hexene; the melt flow rate is 1.1 g / 10 min (with a weight of 2.16 kg and a temperature of 190 °C); the monomer bonding content is 3.5%; and the density is 0.914 g / cm³. 3 The molecular weight distribution is 3.6.

[0042] The elastomer 1 is a copolymer of propylene and ethylene; the melt flow rate is 5.2 g / 10 min; and the density is 0.863 g / cm³. 3 .

[0043] The nucleating agent 1 is a phosphate nucleating agent NA-11, specifically sodium 2,2-methylene-bis(4,6-di-n-butylphenol) phosphate.

[0044] The antioxidant is a compound antioxidant of antioxidant 1010 and antioxidant 168, with a compounding ratio of 1:1.

[0045] The preparation method of the high light transmittance and high impact resistance polypropylene composition is as follows: weigh each component in the composition according to the proportion, mix them in a high-speed mixer for 5±1 min, and then melt-extrude, stretch, and pelletize them through a twin-screw extruder to obtain the high light transmittance and high impact resistance polypropylene composition. The extrusion screw temperature is set at 150℃, 160℃, 180℃, 190℃, 200℃, 210℃, and 200℃ from the feed end to the extrusion end, respectively.

[0046] Example 2

[0047] The high light transmittance and high impact resistance polypropylene composition comprises the following raw materials in weight percentages:

[0048] Polypropylene resin 1: 74.6%;

[0049] Polyethylene resin 1:15%;

[0050] Elastomer 1: 7%;

[0051] Light diffusing agent 1:3%;

[0052] Nucleating agent 1: 0.1%;

[0053] Antioxidant: 0.3%.

[0054] The light diffusing agent 1 is an organosilicon powder, the main component of which is a vinyl polydimethylsiloxane / polymethylsiloxane sesquioxane crosslinked polymer; the average particle size is 2μm.

[0055] Everything else is the same as in Example 1.

[0056] Example 3

[0057] The high light transmittance and high impact resistance polypropylene composition comprises the following raw materials in weight percentages:

[0058] Polypropylene resin 1: 74.6%;

[0059] Polyethylene resin 1:20%;

[0060] Elastomer 1:3%;

[0061] Light diffusing agent 1:2%;

[0062] Nucleating agent 1: 0.3%;

[0063] Antioxidant: 0.1%.

[0064] Everything else is the same as in Example 1.

[0065] Example 4

[0066] The high light transmittance and high impact resistance polypropylene composition comprises the following raw materials in weight percentages:

[0067] Polypropylene resin 1: 69.75%;

[0068] Polyethylene resin 1:25%;

[0069] Light diffusing agent 1:5%;

[0070] Nucleating agent 1: 0.05%;

[0071] Antioxidant: 0.2%.

[0072] Everything else is the same as in Example 1.

[0073] Example 5

[0074] The high light transmittance and high impact resistance polypropylene composition comprises the following raw materials in weight percentages:

[0075] Polypropylene resin 2: 74.4%;

[0076] Polyethylene resin 2: 25%;

[0077] Nucleating agent 2: 0.3%;

[0078] Antioxidant: 0.3%.

[0079] The polypropylene resin 2 is an impact-resistant copolymer polypropylene with a melt flow rate of 22 g / 10 min (weight 2.16 kg, temperature 230℃); the content of copolyethylene monomer is 5.6%; and the weight-average molecular weight is 21 × 10⁻⁶. 4 The molecular weight distribution is 6.2; the rubber phase content is 16.3%; the intrinsic viscosity ratio of the rubber phase to the polypropylene resin is 1.09; and the size of the rubber phase is 300±100nm.

[0080] The polyethylene resin 2 is linear ultra-low density polyethylene, obtained by catalysis with a metallocene catalyst, and the comonomer is hexene; the melt flow rate is 2 g / 10 min (weight 2.16 kg, temperature 190℃); the monomer bonding content is 3.7%; and the density is 0.915 g / cm³. 3 The molecular weight distribution is 3.5.

[0081] The nucleating agent 2 is a sorbitol-based nucleating agent NX8000.

[0082] The antioxidant is a compound antioxidant of antioxidant 1076 and antioxidant 168, with a compounding ratio of 1:1.

[0083] The preparation method of the high light transmittance and high impact resistance polypropylene composition is the same as that in Example 1.

[0084] Example 6

[0085] The high light transmittance and high impact resistance polypropylene composition comprises the following raw materials in weight percentages:

[0086] Polypropylene resin 2: 77.6%;

[0087] Polyethylene resin 2: 15%;

[0088] Elastomer 2: 7%;

[0089] Nucleating agent 2: 0.2%;

[0090] Antioxidant: 0.2%.

[0091] The elastomer 2 is a copolymer of propylene and ethylene; the melt flow rate is 5.5 g / 10 min; and the density is 0.87 g / cm³. 3 .

[0092] The rest is the same as in Example 5.

[0093] Example 7

[0094] The high light transmittance and high impact resistance polypropylene composition comprises the following raw materials in weight percentages:

[0095] Polypropylene resin 2: 71.5%;

[0096] Polyethylene resin 2: 20%;

[0097] Elastomer 2:3%;

[0098] Light diffusing agent 2:5%;

[0099] Nucleating agent 2: 0.3%;

[0100] Antioxidant: 0.2%.

[0101] The light diffusing agent 2 is an organosilicon powder, the main component of which is a vinyl polydimethylsiloxane / polymethylsiloxane sesquioxane crosslinked polymer; the average particle size is 5 μm.

[0102] The rest is the same as in Example 5.

[0103] Example 8

[0104] The high light transmittance and high impact resistance polypropylene composition comprises the following raw materials in weight percentages:

[0105] Polypropylene resin 2: 76.4%;

[0106] Polyethylene resin 2: 10%;

[0107] Elastomer 2: 10%;

[0108] Light diffusing agent 2:3%;

[0109] Nucleating agent 2: 0.5%;

[0110] Antioxidant: 0.1%.

[0111] The rest is the same as in Example 5.

[0112] Comparative Example 1

[0113] The difference from Example 1 is that polypropylene resin 3 is used instead of polypropylene resin 1. The polypropylene resin 3 used is an impact copolymer polypropylene with a melt flow rate of 12 g / 10 min (weight 2.16 kg, temperature 230 °C); the content of copolyethylene monomer is 7%; and the weight average molecular weight is 21 × 10⁻⁶. 4The molecular weight distribution is 6.2; the rubber phase content is 15.3%; the intrinsic viscosity ratio of the rubber phase to the polypropylene resin is 1.6; the rubber phase size is 1000±500 nm. Other parameters are the same as in Example 1.

[0114] Comparative Example 2

[0115] The difference from Example 2 is that polypropylene resin 4 is used instead of polypropylene resin 1. The polypropylene resin 4 used is random copolymer polypropylene with a melt flow rate of 12 g / 10 min (weight 2.16 kg, temperature 230 °C); the content of copolyethylene monomer is 3.2%; and the weight average molecular weight is 21 × 10⁻⁶. 4 The molecular weight distribution is 6.2; there is no rubber phase. Other aspects are the same as in Example 2.

[0116] Comparative Example 3

[0117] The difference from Example 3 is that polyethylene resin 3 is used instead of polyethylene resin 1. The polyethylene resin 3 used is prepared by titanium-based catalyst, and the comonomer is butene. The melt flow rate is 1.1 g / 10 min (weight 2.16 kg, temperature 190 °C); the monomer bonding content is 1.5%; and the density is 0.920 g / cm³. 3 The molecular weight distribution is 5.7. Other parameters are the same as in Example 3.

[0118] Comparative Example 4

[0119] The polypropylene composition comprises the following raw materials in weight percentages:

[0120] Polypropylene resin 1: 72.75%;

[0121] Polyethylene resin 1:15%;

[0122] Elastomer 3:7%;

[0123] Light diffusing agent 1:5%;

[0124] Nucleating agent 1: 0.05%;

[0125] Antioxidant: 0.2%.

[0126] The elastomer 3 is a copolymer of octene and ethylene; the melt flow rate is 5 g / 10 min; and the density is 0.87 g / cm³. 3 .

[0127] Everything else is the same as in Example 2.

[0128] Comparative Example 5

[0129] The polypropylene composition comprises the following raw materials in weight percentages:

[0130] Polypropylene resin 1: 94.6%;

[0131] Light diffusing agent 1:5%;

[0132] Nucleating agent 1: 0.2%;

[0133] Antioxidant: 0.2%.

[0134] Everything else is the same as in Example 1.

[0135] The polypropylene compositions prepared in Examples 1-8 and Comparative Examples 1-5 were subjected to performance tests. Injection-molded samples were used, with an injection screw temperature of 200°C. The conditioning of the samples and the standard testing environment were performed according to GB / T 2918-2018, with a temperature of 23±2°C and a relative humidity of 50±5%. The specific test methods are as follows:

[0136] Melt mass flow rate (g / 10min): Refer to GB / T 3682-2018;

[0137] Density (g / cm³) 3 (Refer to GB / T 1033.2-2010);

[0138] Notched impact strength of simply supported beam (23℃, kJ / m) 2 (Refer to GB / T 1043.1-2008)

[0139] Flexural modulus of elasticity (MPa): Refer to GB / T 9341-2008;

[0140] Light transmittance (2mm thick sample, %): Refer to GB / T2410-2008;

[0141] Haze (2mm thick sample, %): Refer to GB / T2410-2008;

[0142] The test results are shown in Table 1-3:

[0143] Table 1 Performance test results of Examples 1-4

[0144] project Example 1 Example 2 Example 3 Example 4 density 0.91 0.91 0.89 0.90 melt mass flow rate 8.8 8.9 8.7 8.6 Notched impact strength of simply supported beam 56.3 50.1 48.6 46.7 Flexural modulus 970 1019 1133 1165 Light transmittance 72 75 77 80 Haze 95.7 97.8 96.6 98.5

[0145] As can be seen from the data in Table 1, the polypropylene compositions prepared in Examples 1-4 have a light transmittance of over 70% and high flexural modulus and impact strength.

[0146] Table 2 Performance test results of Examples 5-8

[0147] project Example 5 Example 6 Example 7 Example 8 density 0.91 0.90 0.91 0.90 melt mass flow rate 13.2 12.3 13.0 11.8 Notched impact strength of simply supported beam 43.5 55.8 52.2 59.3 Flexural modulus 973 951 966 938 Light transmittance 78 73 75 72 Haze 65.1 61.3 97.7 98.6

[0148] As can be seen from the data in Table 2, the polypropylene prepared in Examples 5-8 has a light transmittance of over 70% and exhibits high flexural modulus and impact strength. Example 5 used polyethylene resin 2 in its formulation, resulting in high light transmittance and a high flexural modulus. Examples 6 and 8 used more elastomer 2, leading to slightly lower light transmittance and flexural modulus in the prepared polypropylene.

[0149] Table 3 Performance test results for Comparative Examples 1-5

[0150] project Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 density 0.91 0.91 0.90 0.91 0.90 melt mass flow rate 9.1 8.8 8.9 8.7 10.3 Notched impact strength of simply supported beam 53.6 29.7 28.5 43.2 6.5 Flexural modulus 1020 834 972 825 1320 Light transmittance 55 72 62 58 81 Haze 99.1 87.8 97.6 98.6 95.6

[0151] As can be seen from the test data in Table 3, Comparative Example 1 used polypropylene resin 3, and the prepared polypropylene composition had a light transmittance of 55%, which was significantly lower than that of Example 1. Comparative Example 2 used polypropylene resin 4 (random copolymer polypropylene) as the base resin for modification, resulting in higher light transmittance, but the impact strength was significantly lower than that of Example 2. Comparative Example 3 used polyethylene resin 3 instead of polyethylene resin 1 in Example 3, and compared with Example 3, both the impact strength and light transmittance of Comparative Example 3 were significantly reduced. Comparative Example 4 used elastomer 3 instead of elastomer 1 in Example 2, and compared with Example 2, the light transmittance of Comparative Example 4 was significantly reduced. Comparative Example 5 did not use polyethylene or elastomer; this formulation had high light transmittance and flexural modulus, but extremely low impact strength.

Claims

1. A high-transmittance, high-impact polypropylene composition, characterized in that, It consists of the following raw materials by weight percentage: Polypropylene resin: 59.2-89.85%; Polyethylene resin: 10-25%; Elastomer: 0-10%; Light diffusing agent: 0-5%; Nucleating agent: 0.05-0.5%; Antioxidant: 0.1-0.3%; The polypropylene resin is an impact-resistant copolymer polypropylene, and the intrinsic viscosity ratio of the rubber phase to the polypropylene resin is 1-1.

2. The polyethylene resin was prepared by catalysis using a metallocene catalyst; The elastomer is a copolymer of propylene and ethylene or butene.

2. The high light transmittance and high impact resistance polypropylene composition according to claim 1, characterized in that, The polypropylene resin has a melt flow rate of 1-30 g / 10 min (2.16 kg weight, 230 °C), a copolyethylene monomer content of 4-7%, and a weight-average molecular weight of (15-50) × 10⁻⁶. 4 The molecular weight distribution is 3-7; the rubber phase content is 14-18%.

3. The high light transmittance and high impact resistance polypropylene composition according to claim 1, characterized in that, The polyethylene resin has hexene as its comonomer, a melt flow rate of 1-5 g / 10 min (with a 2.16 kg weight and a temperature of 190 °C), a monomer bonding content of 1-6%, and a density of 0.910-0.915 g / cm³. 3 The molecular weight distribution is 2-7.

4. The high light transmittance and high impact resistance polypropylene composition according to claim 1, characterized in that, The elastomer has a melt flow rate of 1-10 g / 10 min and a density of 0.860-0.890 g / cm³. 3 .

5. The high light transmittance and high impact resistance polypropylene composition according to claim 1, characterized in that, The light diffusing agent is an organosilicon powder, the main component of which is a vinyl polydimethylsiloxane / polymethylsiloxane sesquioxane crosslinked polymer.

6. The high light transmittance and high impact resistance polypropylene composition according to claim 1, characterized in that, The nucleating agent is one of sorbitol-based nucleating agents, phosphate-based nucleating agents, or benzoate-based nucleating agents.

7. The high light transmittance and high impact resistance polypropylene composition according to claim 1, characterized in that, The antioxidant is a compound antioxidant composed of phenolic antioxidants and one of phosphite antioxidants or thioester antioxidants.

8. A method for preparing the high light transmittance and high impact resistance polypropylene composition according to any one of claims 1-7, characterized in that, The steps are as follows: Mix and stir the raw materials of the formulation components, then melt-extrude, stretch, and pelletize them through a twin-screw extruder to obtain a high light transmittance and high impact resistance polypropylene composition.

9. The method for preparing the high light transmittance and high impact resistance polypropylene composition according to claim 8, characterized in that, The temperature of the twin-screw extruder is 150-230℃.