Composite polypropylene materials and their preparation methods

Abstract

This invention relates to the field of polypropylene materials technology, and discloses a composite polypropylene material and its preparation method. The preparation method of the composite polypropylene material includes: ball milling and mixing modified homopolymer polypropylene and calcium carbonate modified copolymer polypropylene at -100℃ to -10℃ to obtain a polypropylene mixture; mixing the polypropylene mixture with a β-crystal nucleating agent and then melt-extruding; the modified homopolymer polypropylene is a product obtained by modifying homopolymer polypropylene with a modified monomer, wherein the modified monomer is at least one of 1,6-hexanediol diacrylate and tripropylene glycol diacrylate; the calcium carbonate modified copolymer polypropylene is a product obtained by modifying copolymer polypropylene with calcium carbonate. The composite polypropylene material is obtained by the above preparation method. The preparation method provided by this invention can produce a composite polypropylene material with high rigidity and toughness.

Description

Technical Field

[0001] This invention relates to the field of polypropylene materials technology, and more specifically, to composite polypropylene materials and their preparation methods. Background Technology

[0002] Currently, the main methods for producing high-rigidity and high-toughness polypropylene materials are mixed modification, nucleation modification, filler modification, or a combination of these methods.

[0003] Some existing patent applications use homopolymer polypropylene as a raw material. However, during the subsequent melt co-extrusion process, the polypropylene molecular chains are broken due to shearing, leading to a decrease in the material's rigidity and toughness. To prevent the average molecular weight of the polyolefin from decreasing during subsequent processing, this invention employs electron beam radiation technology to treat the polypropylene. This treatment increases the molecular weight of the polypropylene and can, to some extent, prevent the decrease in average molecular weight during subsequent melt co-extrusion. Furthermore, after electron beam treatment, the molecular weight distribution of the polypropylene changes from a unimodal distribution to a bimodal distribution. This bimodal distribution helps to improve toughness while maintaining the material's rigidity.

[0004] In some existing patent applications, melt co-extrusion (twin-screw extrusion) is used to blend and modify homopolymer polypropylene, copolymer polypropylene, and fillers. Grafting is typically performed to improve the connectivity between the different components. However, for inorganic fillers such as calcium carbonate or talc, the grafted material cannot bond well with these inorganic materials, leading to sliding between the inorganic material surface and the polypropylene surface, affecting mechanical properties. This invention addresses this problem by first subjecting calcium carbonate to mechanochemical ball milling with acrylic acid, allowing for good bonding between the two. Then, it is blended with polypropylene, resulting in a good bond at the microscopic level among the three materials, further enhancing the performance advantages of each component.

[0005] Currently, in the preparation of high-rigidity and high-toughness polypropylene, both homopolymer and copolymer polypropylene are produced using melt co-extrusion. Due to the relatively large macroscopic particle size of these two polyolefins, they may not be fully and uniformly mixed during the compounding process, resulting in an inability to effectively improve the material's rigidity-toughness balance.

[0006] In view of this, the present invention is proposed. Summary of the Invention

[0007] The purpose of this invention is to provide composite polypropylene materials and their preparation methods.

[0008] This invention is implemented as follows:

[0009] In a first aspect, the present invention provides a method for preparing a composite polypropylene material, comprising:

[0010] Modified homopolymer polypropylene and calcium carbonate modified copolymer polypropylene were ball-milled and mixed uniformly at -100℃ to -10℃ to obtain a polypropylene mixture.

[0011] The polypropylene mixture is mixed evenly with a β-crystal nucleating agent and then melt-extruded.

[0012] Modified homopolymer polypropylene is a product obtained by modifying homopolymer polypropylene with a modified monomer, wherein the modified monomer is at least one of 1,6-hexanediol diacrylate and tripropylene glycol diacrylate.

[0013] Calcium carbonate modified copolymer polypropylene is the product of calcium carbonate modified copolymer polypropylene.

[0014] In an optional implementation, the modified monomer modifies the homopolymer polypropylene as follows:

[0015] Homopolymer polypropylene and modified monomers are mixed and then subjected to internal mixing followed by irradiation treatment;

[0016] Preferably, the conditions for the internal mixing process are: treatment at 170℃~200℃ for 30min~80min;

[0017] Preferably, the irradiation treatment conditions are: treatment at an irradiation intensity of 0.5 kGy to 10 kGy for 30 min to 80 min.

[0018] In an optional embodiment, the ratio of homopolymer polypropylene to modified monomer is 100g:1 to 100mmol;

[0019] Preferably, an antioxidant is also used when modifying homopolymer polypropylene with modified monomers, and the ratio of the amount of antioxidant to the mass of homopolymer polypropylene is 0.05 to 0.3:100.

[0020] In an optional embodiment, the mass ratio of the β-crystal nucleating agent to the polypropylene mixture is 0.01 to 0.5:100.

[0021] In an optional implementation, the calcium carbonate-modified copolymer polypropylene is produced as follows:

[0022] The first batch of acrylic acid and calcium carbonate were ball-milled in a ball mill to modify the calcium carbonate, thus obtaining modified calcium carbonate.

[0023] The modified calcium carbonate, the second part of acrylic acid, and the copolymer polypropylene were mixed evenly and then melt-extruded to obtain calcium carbonate modified copolymer polypropylene.

[0024] In an optional embodiment, the mass ratio of the first portion of acrylic acid to calcium carbonate is 1-10:1-10, the mass ratio of the second portion of acrylic acid to calcium carbonate is 1-100:1-100, and the mass ratio of the copolymer polypropylene to calcium carbonate is 1-10:1-2.

[0025] In an optional embodiment, the ball milling conditions for the first batch of acrylic acid and calcium carbonate in a ball mill are as follows: ball milling speed range of 10 r / min to 300 r / min, ball mass: material mass of 1 to 10: 1 to 10, and ball milling time of 30 to 900 min.

[0026] In an optional embodiment, the mass ratio of modified homopolymer polypropylene to calcium carbonate modified copolymer polypropylene is 1-10:1-10.

[0027] In an optional embodiment, the ball milling mixing conditions for the modified homopolymer polypropylene and the calcium carbonate modified copolymer polypropylene are: ball milling speed range of 10 r / min to 500 r / min, and ball milling time of 1 to 100 min.

[0028] Secondly, the present invention provides a composite polypropylene material, which is prepared by any of the preparation methods described in the foregoing embodiments.

[0029] The present invention has the following beneficial effects:

[0030] The method for preparing composite polypropylene provided in this application involves treating a mixture of modified homopolymer polypropylene and calcium carbonate modified copolymer polypropylene at a low temperature to bring it close to the glass transition temperature. At this temperature, the material becomes brittle. Ball milling and crushing the mixture can significantly improve the compatibility of the two materials. Subsequent melt extrusion can yield a high-rigidity and high-toughness composite polypropylene material with a good balance of rigidity and toughness. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0032] The composite polypropylene material and its preparation method provided in the embodiments of the present invention will be described in detail below.

[0033] The method for preparing composite polypropylene material provided by the present invention includes:

[0034] Modified homopolymer polypropylene and calcium carbonate modified copolymer polypropylene were ball-milled and mixed uniformly at -100℃ to -10℃ to obtain a polypropylene mixture.

[0035] The polypropylene mixture is mixed evenly with a β-crystal nucleating agent and then melt-extruded.

[0036] Modified homopolymer polypropylene is a product obtained by modifying homopolymer polypropylene with a modified monomer, wherein the modified monomer is at least one of 1,6-hexanediol diacrylate (HDDA) and tripropylene glycol diacrylate (TPGDA).

[0037] Calcium carbonate modified copolymer polypropylene is the product of calcium carbonate modified copolymer polypropylene.

[0038] The preparation method provided in this application involves treating a mixture of modified homopolymer polypropylene and calcium carbonate modified copolymer polypropylene at a low temperature to bring it close to the glass transition temperature. At this temperature, the material becomes brittle. Ball milling and crushing the mixture can significantly improve the compatibility of the two materials. Subsequent melt extrusion can yield a high-rigidity and high-toughness composite polypropylene material with a good balance of rigidity and toughness.

[0039] Specifically, the method for preparing the composite polypropylene material provided in this application includes:

[0040] S1. Preparation of modified homopolymer polypropylene

[0041] After mixing homopolymer polypropylene and modified monomers, the mixture is first fed into an internal mixer for internal mixing, then irradiated with an electron beam accelerator, and finally fed into a twin-screw extruder for high-temperature mixing and extrusion to obtain modified homopolymer polypropylene.

[0042] Mixing and irradiation can alter the molecular weight distribution of homopolymer polypropylene, increasing the average molecular weight and thus further improving the rigidity properties of polypropylene (tensile strength, flexural strength, flexural modulus, etc.). In addition, electron beam irradiation treatment can increase the surface activity of polypropylene, which is beneficial for subsequent mixing with homopolymer polypropylene materials.

[0043] Preferably, the conditions for the internal mixing process are: 170℃~200℃ (e.g., 170℃, 180℃, 190℃ or 200℃) for 30min~80min (e.g., 30min, 50min, 60min or 80min);

[0044] Preferably, the irradiation treatment conditions are: 0.5 kGy to 10 kGy (e.g., 0.5 kGy, 1 kGy, 2 kGy, 4 kGy, 6 kGy, 8 kGy or 10 kGy) irradiation intensity for 30 min to 80 min (e.g., 30 min, 50 min, 60 min or 80 min).

[0045] The specific mixing and irradiation conditions described above ensure that modified homopolymer polypropylene with a high average molecular weight is obtained.

[0046] Modifying homopolymer polypropylene with modified monomers can increase its rigidity. Preferably, to ensure that the obtained composite polypropylene material has better rigidity, the ratio of homopolymer polypropylene to modified monomer is 100g:1 to 100mmol (e.g., 100g:1mmol, 100g:5mmol, 100g:10mmol, 100g:20mmol, 100g:40mmol, 100g:50mmol, 100g:60mmol, 100g:80mmol or 100g:100mmol), preferably 100g:40 to 60mmol.

[0047] Furthermore, to improve the antioxidant properties of the composite polypropylene material, in this step, the antioxidant can be mixed and kneaded together with the homopolymer polypropylene and the modified monomer, then irradiated, and finally extruded and granulated.

[0048] Preferably, to ensure that the prepared composite material has good antioxidant properties without affecting the rigidity and toughness of the composite material, the mass ratio of the antioxidant to the homopolymer polypropylene is 0.05 to 0.3:100 (e.g., 0.05:100, 0.1:100, 0.2:100 or 0.3:100).

[0049] Furthermore, the antioxidants include at least one of BASF Irganox 1010 and Irgafos 168, or other antioxidants from manufacturers with the same formulation.

[0050] S2, Preparation of calcium carbonate modified copolymer polypropylene

[0051] The first batch of acrylic acid and calcium carbonate were ball-milled in a ball mill to modify the calcium carbonate, thus obtaining modified calcium carbonate.

[0052] The modified calcium carbonate, the second part of acrylic acid, and the copolymer polypropylene were mixed evenly and then melt-extruded to obtain calcium carbonate modified copolymer polypropylene.

[0053] The first batch of acrylic acid and calcium carbonate were mixed and ball-milled to perform mechanical and chemical modification of the calcium carbonate, so that the acrylic acid and calcium carbonate formed chemical bonds. This can further improve the bonding between the calcium carbonate and the polypropylene bulk in the modified material. The first and second batches of acrylic acid can improve the bonding strength between copolymer polypropylene and homopolymer polypropylene, thereby improving the bonding between different components in the material.

[0054] Preferably, to obtain a composite polypropylene material with better performance, the mass ratio of the first part of acrylic acid to calcium carbonate is 1–10:1–10 (e.g., 1:10, 2:10, 5:10, 10:10, 10:1, 10:2, or 10:5), more preferably 4–6:4–6 (e.g., 4:6, 1:1, or 6:4), and the mass ratio of the second part of acrylic acid to calcium carbonate is 1–100:1–100 (e.g., 1:100, 10:100, 50). The mass ratio of copolymerized polypropylene to calcium carbonate is 1 to 10:1 to 2 (e.g., 10:1, 8:1, 6:1, 4:1, 2:1, 1:1 or 1:2), preferably 5 to 10:1 (e.g., 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1).

[0055] Furthermore, to ensure that acrylic acid can fully bond with calcium carbonate through chemical bonds, the ball milling conditions for the first batch of acrylic acid and calcium carbonate in a ball mill are as follows: ball milling speed range of 10 r / min to 500 r / min (e.g., 10 r / min, 20 r / min, 50 r / min, 100 r / min, 200 r / min, 300 r / min, 400 r / min or 500 r / min), ball mass to material bulk volume ratio of 1 to 10:1 to 10 (e.g., 1:10, 2:10, 5:10, 10:10, 10:1, 10:2 or 10:5), and ball milling time of 30 to 900 min (e.g., 30 min, 50 min, 80 min, 100 min, 200 min, 400 min, 600 min or 900 min), preferably 60 to 120 min.

[0056] Preparation of S3 and polypropylene mixtures

[0057] After the modified homopolymer polypropylene and the calcium carbonate modified copolymer polypropylene are mixed evenly, they are ball-milled at -100℃ to -10℃ (e.g., -100℃, -80℃, -60℃, -40℃, -20℃ or -10℃) to obtain a polypropylene mixture.

[0058] Preferably, in order to obtain a composite polypropylene material with better rigidity and toughness, the mass ratio of modified homopolymer polypropylene to calcium carbonate modified copolymer polypropylene is 1 to 10:1 to 10 (e.g., 1:10, 2:10, 5:10, 10:10, 10:1, 10:2 or 10:5).

[0059] Furthermore, to ensure that the modified homopolymer polypropylene and the calcium carbonate modified copolymer polypropylene can be mixed more thoroughly and uniformly, the ball milling mixing conditions for the modified homopolymer polypropylene and the calcium carbonate modified copolymer polypropylene are as follows: ball milling speed range of 10 r / min to 500 r / min (e.g., 10 r / min, 20 r / min, 50 r / min, 100 r / min, 200 r / min, 300 r / min, 400 r / min or 500 r / min), and ball milling time of 1 to 100 min (e.g., 1 min, 10 min, 20 min, 40 min, 60 min, 80 min or 100 min).

[0060] S4, melt co-extrusion

[0061] After the polypropylene mixture is obtained, the ball milling is stopped and the temperature is raised to room temperature. Then, the polypropylene mixture is mixed evenly with a β-crystal nucleating agent and finally fed into a twin-screw extruder for melt co-extrusion to obtain a composite polypropylene material.

[0062] Preferably, to further ensure the preparation of a composite polypropylene material with good rigidity and toughness, the mass ratio of the amount of β-crystal nucleating agent to the polypropylene mixture is 0.01 to 0.5:100 (e.g., 0.01:100, 0.05:100, 0.1:100, 0.2:100, 0.4:100 or 0.5:100), preferably 0.1 to 0.5:100.

[0063] This application also provides a composite polypropylene material, prepared using the method provided in this application. Because this composite polypropylene material is prepared using the method provided in this application, it exhibits high rigidity and toughness.

[0064] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0065] Example 1

[0066] (1) Homopolymer polypropylene with an average molecular weight of 500,000, HDDA and antioxidant are mixed and fed into an internal mixer for internal mixing, then irradiated with an electron beam accelerator, and finally fed into a twin-screw extruder for compounding and extrusion to obtain modified homopolymer polypropylene.

[0067] The antioxidant is 1010, and its dosage is 0.05:100 by mass of homopolymer polypropylene.

[0068] The ratio of HDDA to homopolymer polypropylene is 1 mmol: 100 g.

[0069] The conditions for the internal mixing process are: treatment at 170℃ for 30 minutes;

[0070] The irradiation conditions were: 0.5 kGy irradiation intensity for 30 min.

[0071] (2) The first part of acrylic acid and calcium carbonate were ball-milled in a ball mill to modify the calcium carbonate and obtain modified calcium carbonate.

[0072] Modified calcium carbonate, a second part of acrylic acid, and a copolymer polypropylene with an average molecular weight of 350,000 were mixed evenly and then melt-extruded to obtain calcium carbonate modified copolymer polypropylene.

[0073] The first part has a mass ratio of acrylic acid to calcium carbonate of 1:10, the second part has a mass ratio of acrylic acid to calcium carbonate of 1:100, and the copolymer polypropylene has a mass ratio of 10:1.

[0074] The ball milling conditions for the first batch of acrylic acid and calcium carbonate in a ball mill were as follows: ball milling speed range of 10 r / min, ball mass: bulk volume ratio of the processed material of 1:10, and ball milling time of 30 min.

[0075] (3) After mixing the modified homopolymer polypropylene and the calcium carbonate modified copolymer polypropylene evenly, the mixture is ball-milled at -10℃ to obtain a polypropylene mixture.

[0076] The mass ratio of modified homopolymer polypropylene to calcium carbonate modified copolymer polypropylene is 1:10;

[0077] The ball milling conditions for the modified homopolymer polypropylene and the calcium carbonate modified copolymer polypropylene were: ball milling speed range of 10 r / min and ball milling time of 1 min.

[0078] (4) After ball milling, the temperature of the polypropylene mixture is raised to room temperature. Then, the polypropylene mixture is mixed evenly with the β-crystal nucleating agent and finally fed into a twin-screw extruder for melt co-extrusion to obtain the composite polypropylene material.

[0079] The mass ratio of the β-crystal nucleating agent to the polypropylene mixture is 0.01:100.

[0080] Example 2

[0081] (1) Homopolymer polypropylene with an average molecular weight of 500,000, TPGDA and antioxidant are mixed and fed into an internal mixer for internal mixing, then irradiated with an electron beam accelerator, and finally fed into a twin-screw extruder for compounding and extrusion to obtain modified homopolymer polypropylene.

[0082] The antioxidant is 1010, and its dosage is 0.3:100 by mass of homopolymer polypropylene.

[0083] The ratio of TPGDA to homopolymer polypropylene is 100 mmol: 100 g.

[0084] The conditions for the internal mixing process are: treatment at 200℃ for 80 minutes;

[0085] The irradiation conditions were: 10 kGy irradiation intensity for 80 min.

[0086] (2) The first part of acrylic acid and calcium carbonate were ball-milled in a ball mill to modify the calcium carbonate and obtain modified calcium carbonate.

[0087] Modified calcium carbonate, a second part of acrylic acid, and a copolymer polypropylene with an average molecular weight of 350,000 were mixed evenly and then melt-extruded to obtain calcium carbonate modified copolymer polypropylene.

[0088] The first part has a mass ratio of acrylic acid to calcium carbonate of 10:1, the second part has a mass ratio of acrylic acid to calcium carbonate of 100:1, and the copolymer polypropylene has a mass ratio of 1:2.

[0089] The ball milling conditions for the first batch of acrylic acid and calcium carbonate were as follows: ball milling speed range of 500 r / min, ball mass: bulk volume ratio of the processed material of 10:1, and ball milling time of 900 min.

[0090] (3) After mixing the modified homopolymer polypropylene and the calcium carbonate modified copolymer polypropylene evenly, the mixture is ball-milled at -100℃ to obtain a polypropylene mixture.

[0091] The mass ratio of modified homopolymer polypropylene to calcium carbonate modified copolymer polypropylene is 10:1;

[0092] The ball milling conditions for the modified homopolymer polypropylene and the calcium carbonate modified copolymer polypropylene were: ball milling speed 500 r / min and ball milling time 100 min.

[0093] (4) After ball milling, the temperature of the polypropylene mixture is raised to room temperature. Then, the polypropylene mixture is mixed evenly with the β-crystal nucleating agent and finally fed into a twin-screw extruder for melt co-extrusion to obtain the composite polypropylene material.

[0094] The mass ratio of the β-crystal nucleating agent to the polypropylene mixture is 0.5:100.

[0095] Example 3

[0096] (1) Homopolymer polypropylene with an average molecular weight of 450,000, modified monomers and antioxidants are mixed and fed into an internal mixer for internal mixing, then irradiated with an electron beam accelerator, and finally fed into a twin-screw extruder for compounding and extrusion to obtain modified homopolymer polypropylene.

[0097] The antioxidant is 1010, and its dosage is 0.1:100 by mass of homopolymer polypropylene.

[0098] The ratio of the amount of modified monomer to homopolymer polypropylene is 100 mmol: 100 g, and the modified monomer is a mixture of HDDA and TPGDA with a molar ratio of 2:1.

[0099] The conditions for the internal mixing process are: treatment at 180℃ for 60 minutes;

[0100] The irradiation conditions were: 5 kGy irradiation intensity for 50 min.

[0101] (2) The first part of acrylic acid and calcium carbonate were ball-milled in a ball mill to modify the calcium carbonate and obtain modified calcium carbonate.

[0102] Modified calcium carbonate, a second part of acrylic acid, and a copolymer polypropylene with an average molecular weight of 350,000 were mixed evenly and then melt-extruded to obtain calcium carbonate modified copolymer polypropylene.

[0103] The first part has an acrylic acid to calcium carbonate mass ratio of 1:1, the second part has an acrylic acid to calcium carbonate mass ratio of 1:5, and the copolymer polypropylene to calcium carbonate mass ratio of 9:1.

[0104] The ball milling conditions for the first batch of acrylic acid and calcium carbonate were as follows: ball milling speed range of 300 r / min, ball mass: bulk volume ratio of the processed material of 1:1, and ball milling time of 100 min.

[0105] (3) After mixing the modified homopolymer polypropylene and the calcium carbonate modified copolymer polypropylene evenly, the mixture is ball-milled at -50℃ to obtain a polypropylene mixture.

[0106] The mass ratio of modified homopolymer polypropylene to calcium carbonate modified copolymer polypropylene is 6:4;

[0107] The ball milling conditions for the modified homopolymer polypropylene and the calcium carbonate modified copolymer polypropylene were as follows: ball milling speed range of 100 r / min, ball mass: bulk volume ratio of the processed material of 1:1, and ball milling time of 20 min.

[0108] (4) After ball milling, the temperature of the polypropylene mixture is raised to room temperature. Then, the polypropylene mixture is mixed evenly with the β-crystal nucleating agent and finally fed into a twin-screw extruder for melt co-extrusion to obtain the composite polypropylene material.

[0109] The mass ratio of the β-crystal nucleating agent to the polypropylene mixture is 0.15:100.

[0110] Example 4

[0111] This embodiment is basically the same as embodiment 3, except that: the first batch of acrylic acid and calcium carbonate were not ball-milled, but mechanically stirred, and the stirring speed and time were the same as those for ball milling.

[0112] Example 5

[0113] This embodiment is basically the same as embodiment 3, except that electron beam radiation was not performed.

[0114] Example 6

[0115] This embodiment is basically the same as Example 1, except that the mass ratio of modified homopolymer polypropylene to calcium carbonate modified copolymer polypropylene is 0.5:10.

[0116] Example 7

[0117] This embodiment is basically the same as Embodiment 2, except that the mass ratio of modified homopolymer polypropylene to calcium carbonate modified copolymer polypropylene is 10:0.5.

[0118] Comparative Example 1

[0119] This comparative example is basically the same as Example 3, except that the mixing of modified homopolymer polypropylene and calcium carbonate modified copolymer polypropylene is carried out at room temperature (25°C).

[0120] Comparative Example 2

[0121] This comparative example is basically the same as Example 3, except that the mixing of modified homopolymer polypropylene and calcium carbonate modified copolymer polypropylene is carried out at room temperature (25°C).

[0122] The first batch of acrylic acid and calcium carbonate was not ball-milled, but mechanically stirred. The stirring speed and time were the same as those for ball milling.

[0123] Experimental Example

[0124] The stiffness (tensile strength and flexural modulus) and toughness (notched impact strength of a simply supported beam) of the composite polypropylene materials prepared in Examples 1-7 and Comparative Examples 1 and 2 were tested. Standard tensile measurements and bending tests were performed using a general-purpose material testing instrument. Dumbbell-shaped specimens used for tensile testing were tested according to ASTM D-638 (Type I) at a tensile speed of 50 mm / min and a gauge length of 50 mm. Static bending tests were performed using a three-point bend test set according to ASTM D-790 at a crosshead speed of 2 mm / min, with dimensions of 127 × 12.7 × 3.0 mm. 3 The notched impact strength of a simply supported beam was tested using an impact testing machine according to ASTM D-256. The specimen dimensions were 63.5 × 12.7 × 33.0 mm. 3It features a "V"-shaped notch. All mechanical tests were performed at room temperature. For each specimen, five measurements were taken and the average result was calculated.

[0125] Record the test results in Table 1.

[0126] Table 1 Performance of each group of composite polypropylene materials

[0127]

[0128]

[0129] The test results in the table above show that the composite polypropylene materials prepared in each embodiment of this application have high rigidity and toughness, which are significantly better than those in Comparative Example 2, especially Examples 1-3, which have significantly better rigidity and toughness. Comparing Example 3 with Comparative Example 1, it can be seen that the rigidity and toughness of Example 3 are significantly higher than those of the Comparative Example, indicating that ball milling and mixing the modified homopolymer polypropylene and the calcium carbonate modified copolymer polypropylene at low temperature can significantly improve the uniformity of the mixture and thus improve the performance of the final composite material. Comparing Example 4 with Example 3, its notched impact strength index is slightly worse, indicating that ball milling allows acrylic acid to form chemical bonds with calcium carbonate first, which is beneficial to improving the performance of the composite material. Comparing Example 5 with Example 3, the tensile strength and impact toughness of Example 5 are slightly worse, indicating that electron beam radiation treatment helps to improve the rigidity of the composite material. Comparing Examples 6 and 7 with Examples 1 and 2, respectively, the performance of Examples 6 and 7 is slightly worse than the corresponding examples, indicating that when the ratio of modified homopolymer polypropylene to calcium carbonate modified copolymer polypropylene is within the preferred range defined in this application, a composite material with better performance can be obtained.

[0130] In summary, the method for preparing composite polypropylene materials provided in this application involves treating a mixture of modified homopolymer polypropylene and calcium carbonate modified copolymer polypropylene at a low temperature to bring it close to the glass transition temperature. At this temperature, the material becomes brittle. Ball milling and crushing the mixture can significantly improve the compatibility of the two materials. Subsequent melt extrusion can yield a high-rigidity and high-toughness composite polypropylene material with a good balance of rigidity and toughness.

[0131] In the preferred embodiment, mixing and irradiation can alter the molecular weight distribution of homopolymer polypropylene, increase the average molecular weight, and thus further improve the rigidity properties of polypropylene (tensile strength, flexural strength, flexural modulus, etc.). In addition, electron beam irradiation treatment can increase the surface activity of polypropylene, which is beneficial for the subsequent mixing performance with homopolymer polypropylene materials.

[0132] In the preferred embodiment, the first portion of acrylic acid and calcium carbonate are mixed and ball-milled to perform mechanochemical modification on the calcium carbonate, so that the acrylic acid and calcium carbonate form a chemical bond. This can further improve the bonding between the calcium carbonate and the polypropylene bulk in the modified material. The first and second portions of acrylic acid can improve the bonding strength between the copolymer polypropylene and the homopolymer polypropylene, thereby improving the bonding between different components in the material.

[0133] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a composite polypropylene material, characterized in that, include: Modified homopolymer polypropylene and calcium carbonate modified copolymer polypropylene were ball-milled and mixed uniformly at -100℃ to -10℃ to obtain a polypropylene mixture; The polypropylene mixture is mixed evenly with a β-crystal nucleating agent and then melt-extruded. The modified homopolymer polypropylene is a product obtained by modifying homopolymer polypropylene with a modified monomer, wherein the modified monomer is at least one of 1,6-hexanediol diacrylate and tripropylene glycol diacrylate. The calcium carbonate modified copolymer polypropylene is the product of calcium carbonate modified copolymer polypropylene; The method of modifying the copolymer polypropylene with calcium carbonate is as follows: The first part of acrylic acid and the calcium carbonate were ball-milled in a ball mill to modify the calcium carbonate, thereby obtaining modified calcium carbonate. The modified calcium carbonate, the second part of acrylic acid, and the copolymer polypropylene were mixed evenly and then melt-extruded to obtain the calcium carbonate modified copolymer polypropylene. The mass ratio of the modified homopolymer polypropylene to the calcium carbonate modified copolymer polypropylene is 1~10:1~10.

2. The method for preparing the composite polypropylene material according to claim 1, characterized in that, The method by which the modified monomer modifies the homopolymer polypropylene is as follows: The homopolymer polypropylene and the modified monomer are mixed and then subjected to internal mixing followed by irradiation.

3. The method for preparing the composite polypropylene material according to claim 2, characterized in that, The conditions for internal mixing are: 170℃~200℃ for 30min~80min.

4. The method for preparing the composite polypropylene material according to claim 2, characterized in that, The irradiation treatment conditions were: 0.5 kGy to 10 kGy irradiation intensity for 30 min to 80 min.

5. The method for preparing the composite polypropylene material according to any one of claims 1 to 4, characterized in that, The ratio of homopolymer polypropylene to the modified monomer is 100g:1~100mmol.

6. The method for preparing the composite polypropylene material according to any one of claims 1 to 4, characterized in that, An antioxidant is also used when modifying the homopolymer polypropylene with the modified monomer, and the mass ratio of the antioxidant to the homopolymer polypropylene is 0.05~0.3:

100.

7. The method for preparing the composite polypropylene material according to claim 1, characterized in that, The mass ratio of the β-crystal nucleating agent to the polypropylene mixture is 0.01~0.5:

100.

8. The method for preparing the composite polypropylene material according to claim 1, characterized in that, The mass ratio of the first part of acrylic acid to the calcium carbonate is 1~10:1~10, the mass ratio of the second part of acrylic acid to the calcium carbonate is 1~100:1~100, and the mass ratio of the copolymer polypropylene to the calcium carbonate is 1~10:1~2.

9. The method for preparing the composite polypropylene material according to claim 8, characterized in that, The ball milling conditions for the first part of acrylic acid and the calcium carbonate in the ball mill are as follows: ball milling speed 10 r / min to 500 r / min, ball mass: bulk volume ratio of processed material 1 to 10: 1 to 10, and ball milling time 30 to 900 min.

10. The method for preparing the composite polypropylene material according to claim 1, characterized in that, The ball milling conditions for the modified homopolymer polypropylene and the calcium carbonate modified copolymer polypropylene are: 10 r / min to 500 r / min, and the ball milling time is 1 to 100 min.

11. A composite polypropylene material, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 10.

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