Low-temperature-toughness high-flow polypropylene composite material and preparation method thereof

Abstract

According to the low-temperature-toughness high-fluidity polypropylene composite material and the preparation method thereof provided by the invention, the high-fluidity polypropylene resin and the impact-resistant co-polypropylene resin serving as a toughening agent are degraded and blended, so that the low-temperature toughness of the polypropylene composite material is improved, the polypropylene composite material has high fluidity, and excessive loss of other properties is avoided. The polypropylene composite material obtained by the preparation method has good rigidity-toughness balance in a low-temperature environment, the application range and the service time in the low-temperature environment are expanded, and the polypropylene composite material has a wide market prospect. Meanwhile, by optimizing the extrusion granulation process, the content of volatile organic compounds (VOC) in the product is reduced, and the problem of peculiar smell residue of the product is avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of polypropylene composites, and particularly relates to a polypropylene composite with high low-temperature toughness and high fluidity and a preparation method thereof. Background Art

[0002] Polypropylene is a thermoplastic synthetic resin with excellent properties, having chemical resistance, heat resistance, electrical insulation, good mechanical properties and molding and processing properties, etc. It has a wide range of applications in industries such as food and drug packaging, household appliances, automobiles, electronics, building materials and home furnishings, and chemical equipment. However, generally, polypropylene has poor toughness, low notched impact strength, especially its low-temperature resistance is poor, which limits its application range. To improve the low-temperature toughness of polypropylene, rubber or elastomers can be added, such as propylene-ethylene copolymer, ethylene-propylene-diene monomer rubber, ethylene-octene copolymer, styrene-butadiene-styrene copolymer, etc.; or the molecular structure of polypropylene can be changed by copolymerization, grafting, crosslinking and other methods to make it have better toughness at low temperatures. The former is more widely used due to its lower cost, simple production process and easy operation. Among them, ethylene-propylene rubber has good compatibility with polypropylene and has become a commonly used rubber variety in toughening polypropylene.

[0003] The production process types of high-fluidity polypropylene include loop process, autoclave liquid-phase bulk process, gas-phase fluidized bed process, etc. The industrial production of high-fluidity polypropylene resin mainly adopts the reactor hydrogen regulation method and the controlled rheology method. The controlled rheology method is to add peroxide to polypropylene powder during the extrusion granulation process to cause the powder to degrade, thereby increasing the melt index. The products produced by this method have too large fluctuations in melt index and unstable product performance. Existing large-scale polypropylene plants mainly prepare high-fluidity polypropylene by adopting the reactor hydrogen regulation method, that is, increasing the amount of hydrogen added during the propylene polymerization process to reduce the molecular weight of polypropylene to increase its melt index. Its advantage is that the products produced have good comprehensive performance and stable quality. Therefore, the reactor hydrogen regulation method and the controlled rheology method can be combined to achieve the low-cost advantage, make the polypropylene resin have high fluidity, endow it with good mechanical properties and ensure the quality stability of the products.

[0004] For high-flow polypropylene materials, the higher the fluidity, the more significantly the impact toughness will decrease. Most of the polypropylene materials obtained by the modification methods of introducing elastomers or changing the molecular structure of polypropylene only solve the problem of toughening at room temperature. For low-temperature toughening, due to harsh environmental conditions, it has become a difficult point in research and development. At the same time, existing technologies often result in the loss of other properties, such as flexural modulus and tensile yield strength, while improving the low-temperature toughness of polypropylene. In addition, these technologies often require complex process conditions or special equipment, which also increases the production cost. More importantly, some additives or methods of changing the polymer structure used in existing technologies may cause environmental pollution and do not conform to the current development trend of green chemistry. Summary of the Invention

[0005] The object of the present invention is to overcome the defects of the existing technology and provide a high-flow polypropylene composite material with high low-temperature toughness and its preparation method. By blending and extruding two materials obtained by respectively degrading a high-flow polypropylene resin and an impact copolymer polypropylene resin with a degradable molecular weight regulator masterbatch, the target product is obtained, ensuring the high fluidity of the target product while increasing its low-temperature impact resistance. It meets the current market requirements for high-efficiency processing of packaging materials and convenient long-term low-temperature storage.

[0006] To achieve the above object, the present invention adopts the following technical solutions: A high-flow polypropylene composite material with high low-temperature toughness, comprising the following components in parts by weight: High-flow polypropylene resin: 40 - 80 parts by weight; Impact copolymer polypropylene resin: 20 - 60 parts by weight; Degradable molecular weight regulator masterbatch: 0.1 - 0.6 parts by weight; Antioxidant: 0.1 - 0.2 parts by weight; Nucleating agent: 0.03 - 0.06 parts by weight; Stabilizer: 0.01 - 0.05 parts by weight.

[0007] The high-flow polypropylene resin is a homopolypropylene or a copolymer of propylene and ethylene; the content of ethylene in the copolymer of propylene and ethylene is 0 - 3%; the melt index of the high-flow polypropylene resin at 230 °C and a load of 2.16 kg is 60 - 80 g / 10min, and the weight-average molecular weight is 170000 - 200000 g / mol.

[0008] The impact copolymer polypropylene resin is a copolymer of propylene and ethylene, the ethylene content is 10 - 20%, the rubber phase content is 25 - 40 wt%, and the melt index at 230 °C and a load of 2.16 kg is 5 - 15 g / 10min.

[0009] The degradable molecular weight regulator masterbatch is a composite material of peroxide and polypropylene resin, and the content of peroxide is 8-25%; the peroxide is one of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane or 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxynonane.

[0010] The antioxidant includes a main antioxidant and a co-antioxidant. The main antioxidant is a hindered phenol antioxidant, and the co-antioxidant is a phosphite antioxidant.

[0011] The hindered phenol antioxidant is at least one of 2,6-di-tert-butyl-p-cresol, pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and n-octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; the phosphite antioxidant is at least one of tris(2,4-di-tert-butylphenyl)phosphite and dipentaerythritol diphosphite diisodecyl ester.

[0012] The nucleating agent is one or more of aryl phosphate salts, dibenzylidene sorbitols, substituted aluminum benzoates, dehydroabietic acid soaps, and cyclic dicarboxylate nucleating agents.

[0013] The stabilizer is any one of calcium stearate or zinc stearate.

[0014] A preparation method of a high-flow polypropylene composite material with high low-temperature toughness is as follows: (1) Preparation of the masterbatch: S1: Add high-flow polypropylene resin, degradable molecular weight regulator masterbatch, antioxidant, nucleating agent, and stabilizer to a high-speed mixer according to their weight parts, where the high-flow polypropylene resin is 0-65 parts, the degradable molecular weight regulator masterbatch is 0-0.2 parts, the main antioxidant is 0.01-0.05 parts, the co-antioxidant is 0.02-0.08 parts, the nucleating agent is 0.02-0.05 parts, and the stabilizer is 0.01-0.05 parts. After all components are mixed evenly, masterbatch 1 is obtained through a twin-screw extruder granulator; the extrusion temperature is 180-220 °C, and the screw speed is 100-160 r / min; the melt index of masterbatch 1 at 230 °C and a load of 2.16 kg is 70-150 g / 10min; S2: Add impact copolymer polypropylene resin, degradable molecular weight regulator masterbatch, antioxidant, nucleating agent and stabilizer into a high-speed mixer according to their weight parts. Among them, the impact copolymer polypropylene resin is 0 - 50 parts, the degradable molecular weight regulator masterbatch is 0 - 0.6 parts, the main antioxidant is 0 - 0.03 parts, the auxiliary antioxidant is 0 - 0.05 parts, the nucleating agent is 0 - 0.05 parts, and the stabilizer is 0 - 0.03 parts. After all components are mixed evenly, masterbatch 2 is obtained through a twin-screw extrusion granulator; the temperature of the extrusion section is 180 - 220 °C, and the screw speed is 100 - 160 r / min; the melt index of masterbatch 2 under the conditions of 230 °C and a load of 2.16 kg is 10 - 60 g / 10min; (2) Add the masterbatch 1 and masterbatch 2 respectively prepared in the above step (1) into a high-speed mixer, mix for 20 - 30 min at a stirring speed of 300 - 600 r / min to make the materials fully mixed evenly, and add the mixed materials into a twin-screw extruder for melt extrusion granulation to prepare the low-temperature toughness and high-flow polypropylene composite material.

[0015] The process conditions for the extrusion granulation are as follows: the temperature of the conveying section is 80 - 210 °C, the temperature of the melting section is 200 - 250 °C, the temperature of the extrusion section is 170 - 220 °C, the screw speed is 120 - 180 r / min. After the extruded strip passes through the cooling water at 23 °C, granulation is carried out, and the rotational speed of the granulation motor is 600 - 800 r / min.

[0016] Compared with the existing technology, the beneficial effects of the technical solution are as follows: (1) In the present invention, the common high-flow polypropylene resin and the impact copolymer polypropylene resin as a toughening agent are blended after degradation, thereby improving the low-temperature toughness of the polypropylene composite material and endowing it with high fluidity. This method meets the requirements of high-efficiency processing of polypropylene composite materials, improves the low-temperature toughness of polypropylene, and avoids excessive loss of other properties, such as flexural modulus, tensile yield strength, etc. The polypropylene composite material can have good rigidity-toughness balance in a low-temperature environment, which will greatly expand its application range and service time in a low-temperature environment and has broad market prospects.

[0017] (2) In the present invention, the target product is obtained by blending two polypropylene resins prepared by the hydrogen regulation method of the Unipol process and the degradation masterbatch, avoiding the increase in production cost caused by simply using the hydrogen regulation method and the problems such as yellowing of the product appearance and peculiar smell of the product caused by simply using the degradation method. The combination of the hydrogen regulation method and the degradation method enables the prepared polypropylene composite material to meet the requirements of rapid injection molding processing, improves the processing efficiency; at the same time, reduces the production cost and energy consumption.

[0018] (3) By optimizing the extrusion granulation process, the present invention reduces the content of volatile organic compounds (VOC) in the product and avoids the problem of odor residue in the product.

[0019] (4) The raw materials of the present invention are green and environmentally friendly, which are in line with the current development trend of green chemistry. Specific Embodiments

[0020] The following will describe clearly and completely the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. The illustrative embodiments and descriptions thereof of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0021] The raw materials in the following embodiments can all be purchased from the market.

[0022] Example 1 (1) Preparation of the blend masterbatch: S1: 65 parts of high-flow polypropylene resin (prepared by the hydrogen regulation method, melt index of 70 g / 10min, ethylene content of 1.2%, weight-average molecular weight of 190,000 g / mol), 0.16 part of a degradable molecular weight regulator masterbatch (containing 20% of peroxide 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), 0.0325 part of the main antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 0.05 part of the co-antioxidant tris(2,4-di-tert-butylphenyl)phosphite, 0.0325 part of the nucleating agent calcium cyclohexanedicarboxylate, and 0.0195 part of the stabilizer calcium stearate are added to a high-speed mixer according to their weight parts, and mixed evenly at a rotation speed of 300 r / min, and then extruded and granulated to obtain masterbatch 1; the extrusion temperature is 190 °C and the screw rotation speed is 140 r / min.

[0023] S2: 35 parts of impact copolymer polypropylene resin (prepared by the Unipol process, rubber phase content of 30%, ethylene content of 14%, melt index of 9 g / 10min), the degradable molecular weight regulator masterbatch, the main antioxidant, the co-antioxidant, the nucleating agent and the stabilizer are the same as in step S1, and their weight parts are 0.35 part, 0.0175 part, 0.025 part, 0.0175 part and 0.0105 part respectively. All the above materials are added to a high-speed mixer and mixed evenly at a rotation speed of 300 r / min, and then extruded and granulated to obtain masterbatch 2; the extrusion section temperature is 190 °C and the screw rotation speed is 140 r / min.

[0024] (2) Add the masterbatch 1 and masterbatch 2 prepared in step (1) into a twin-screw extruder, mix for 20 min at a stirring speed of 350 r / min to make the materials fully and evenly mixed; conduct melt extrusion granulation, and the process conditions for extrusion granulation are: the temperature of the conveying section is 200 °C, the temperature of the melting section is 220 °C, the temperature of the extrusion section is 180 °C, the screw speed is 150 r / min, and the cutting motor speed is 720 r / min.

[0025] Example 2 (1) Preparation of the blended masterbatch: S1: Add 65 parts of high-flow polypropylene resin (prepared by the hydrogen regulation method, with a melt index of 70 g / 10 min, an ethylene content of 1.2%, and a weight-average molecular weight of 190,000 g / mol), 0.12 parts of a degradable molecular weight regulator masterbatch (containing 20% of peroxide 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), 0.0325 parts of the main antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 0.05 parts of the co-antioxidant tris(2,4-di-tert-butylphenyl) phosphite, 0.0325 parts of the nucleating agent calcium cyclohexanedicarboxylate, and 0.0195 parts of the stabilizer calcium stearate into a high-speed mixer according to their weight parts, and mix evenly at a speed of 300 r / min and then extrude and granulate to obtain masterbatch 1; S2: Add 35 parts of an impact copolymer polypropylene resin (prepared by the Unipol process, with a rubber phase content of 30%, an ethylene content of 14%, and a melt index of 9 g / 10 min). The degradable molecular weight regulator masterbatch, main antioxidant, co-antioxidant, nucleating agent, and stabilizer used are the same as in step S1, and their weight parts are 0.25 parts, 0.0175 parts, 0.025 parts, 0.0175 parts, and 0.0105 parts respectively. Add the above materials into a high-speed mixer, mix evenly at a speed of 300 r / min and then extrude and granulate to obtain masterbatch 2; (2) Add the masterbatch 1 and masterbatch 2 prepared in step (1) above into a twin-screw extruder, mix for 20 min at a stirring speed of 350 r / min to make the materials fully and evenly mixed; conduct melt extrusion granulation, and the process conditions for extrusion granulation are: the temperature of the conveying section is 200 °C, the temperature of the melting section is 220 °C, the temperature of the extrusion section is 180 °C, the screw speed is 150 r / min, and the cutting motor speed is 720 r / min.

[0026] Example 3 (1) Preparation of the blended masterbatch: S1: Add high-flow polypropylene resin (prepared by hydrogen regulation method, melt index of 70 g / 10 min, ethylene content of 1.2%, weight-average molecular weight of 190,000 g / mol), 0.15 part of a degradable molecular weight regulator masterbatch (containing 20% peroxide 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), 0.03 part of the primary antioxidant pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 0.045 part of the co-antioxidant tris(2,4-di-tert-butylphenyl) phosphite, 0.03 part of the nucleating agent calcium cyclohexanedicarboxylate, and 0.018 part of the stabilizer calcium stearate into a high-speed mixer according to their weight parts, and mix evenly at a rotation speed of 300 r / min and then extrude and pelletize to obtain masterbatch 1; S2: 40 parts of an impact copolymer polypropylene resin (prepared by Unipol process, rubber phase content of 30%, ethylene content of 14%, melt index of 9 g / 10 min), the degradable molecular weight regulator masterbatch, primary antioxidant, co-antioxidant, nucleating agent and stabilizer are the same as in step S1, and their weight parts are 0.35 part, 0.02 part, 0.03 part, 0.02 part and 0.012 part respectively. Add the above materials into a high-speed mixer, mix evenly at a rotation speed of 300 r / min and then extrude and pelletize to obtain masterbatch 2; (2) Add masterbatch 1 and masterbatch 2 prepared respectively in the above step (1) into a twin-screw extruder, mix for 20 min at a stirring speed of 350 r / min to make the materials fully mixed evenly; carry out melt extrusion and pelletization, and the process conditions for extrusion and pelletization are: conveying section temperature of 200 °C, melting section temperature of 250 °C, extrusion section temperature of 180 °C, screw rotation speed of 150 r / min, and pelletizing motor rotation speed of 720 r / min.

[0027] Example 4 (1) Preparation of the blend masterbatch: S1: Add 50 parts of high-flow homopolypropylene resin (prepared by hydrogen regulation method, melt index of 70 g / 10 min, weight-average molecular weight of 180,000 g / mol), 0.1 part of a degradable molecular weight regulator masterbatch (containing 20% peroxide 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), 0.025 part of the primary antioxidant pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 0.035 part of the co-antioxidant tris(2,4-di-tert-butylphenyl) phosphite, 0.025 part of the nucleating agent calcium cyclohexanedicarboxylate, and 0.015 part of the stabilizer calcium stearate into a high-speed mixer according to their weight parts, and mix evenly at a rotation speed of 300 r / min and then extrude and pelletize to obtain masterbatch 1; S2: 50 parts of impact copolymer polypropylene resin (prepared by Unipol process, rubber phase content 30%, ethylene content 14%, melt index 9 g / 10min), the degradable molecular weight regulator masterbatch, primary antioxidant, secondary antioxidant, nucleating agent and stabilizer are the same as in step S1, and their weight parts are 0.16 part, 0.025 part, 0.035 part, 0.025 part and 0.015 part respectively. Add the above materials into a high-speed mixer, mix evenly at a rotation speed of 300 r / min and extrude and pelletize to obtain masterbatch 2; (2) Add the masterbatch 1 and masterbatch 2 prepared in the above step (1) into a twin-screw extruder, mix for 20 min at a stirring speed of 350 r / min to make the materials fully mixed evenly; carry out melt extrusion and pelletization, and the process conditions for extrusion and pelletization are: conveying section temperature 200 °C, melting section temperature 220 °C, extrusion section temperature 180 °C, screw rotation speed 150 r / min, pelletizing motor rotation speed 720 r / min.

[0028] Example 5 (1) Preparation of the blend masterbatch: S1: Add 60 parts of high-flow polypropylene resin (prepared by hydrogen regulation method, melt index 70 g / 10min, ethylene content 1.2%, weight average molecular weight 190000 g / mol), 0.12 part of degradable molecular weight regulator masterbatch (containing 20% peroxide 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), 0.03 part of primary antioxidant pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 0.045 part of secondary antioxidant tris[2,4-di-tert-butylphenyl]phosphite, 0.03 part of nucleating agent calcium cyclohexanedicarboxylate, and 0.018 part of stabilizer calcium stearate into a high-speed mixer according to their weight parts, mix evenly at a rotation speed of 300 r / min and extrude and pelletize to obtain masterbatch 1; S2: 40 parts of impact copolymer polypropylene resin (prepared by Unipol process, rubber phase content 30%, ethylene content 14%, melt index 9 g / 10min), the degradable molecular weight regulator masterbatch, primary antioxidant, secondary antioxidant, nucleating agent and stabilizer are the same as in step S1, and their weight parts are 0.22 part, 0.02 part, 0.03 part, 0.02 part and 0.012 part respectively. Add the above materials into a high-speed mixer, mix evenly at a rotation speed of 300 r / min and extrude and pelletize to obtain masterbatch 2; (2) Add the masterbatch 1 and masterbatch 2 prepared in the above step (1) into a twin-screw extruder, mix for 20 min at a stirring speed of 350 r / min to make the materials fully and evenly mixed; conduct melt extrusion granulation, and the process conditions for extrusion granulation are: the temperature of the conveying section is 200 °C, the temperature of the melting section is 250 °C, the temperature of the extrusion section is 180 °C, the screw speed is 150 r / min, and the cutting motor speed is 720 r / min.

[0029] Comparative Example 1 (1) Add 100 parts of high-flow polypropylene resin (prepared by the hydrogen regulation method, melt index is 70 g / 10 min, ethylene content is 1.2%, weight-average molecular weight is 190000 g / mol), 0 parts of a degradable molecular weight regulator masterbatch (containing 20% of peroxide 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), 0.05 part of the main antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 0.075 part of the co-antioxidant tris(2,4-di-tert-butylphenyl) phosphite, 0.05 part of the nucleating agent calcium cyclohexanedicarboxylate, and 0.03 part of the stabilizer calcium stearate into a high-speed mixer according to their weight parts, and mix for 20 min at a stirring speed of 350 r / min to make the materials fully and evenly mixed; (2) Add the materials uniformly mixed in the above step (1) into a twin-screw extruder for melt extrusion granulation, and the process conditions for extrusion granulation are: the temperature of the conveying section is 200 °C, the temperature of the melting section is 220 °C, the temperature of the extrusion section is 180 °C, the screw speed is 150 r / min, and the cutting motor speed is 720 r / min.

[0030] Comparative Example 2 (1) Preparation of the blend masterbatch: S1: Add 50 parts of high-flow polypropylene resin (prepared by the hydrogen regulation method, melt index is 70 g / 10 min, ethylene content is 1.2%, weight-average molecular weight is 190000 g / mol), 0.025 part of the main antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 0.035 part of the co-antioxidant tris(2,4-di-tert-butylphenyl) phosphite, 0.025 part of the nucleating agent calcium cyclohexanedicarboxylate, and 0.015 part of the stabilizer calcium stearate into a high-speed mixer according to their weight parts, and mix and extrude granulate at a speed of 300 r / min to obtain masterbatch 1; S2: 50 parts of impact copolymer polypropylene resin (prepared by Unipol process, rubber phase content 30%, ethylene content 14%, melt index 9 g / 10min), 0.6 part of the degradable molecular weight regulator masterbatch (containing 20% of peroxide 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), 0.025 part of the primary antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 0.035 part of the secondary antioxidant tris(2,4-di-tert-butylphenyl) phosphite, 0.025 part of the nucleating agent calcium cyclohexanedicarboxylate, and 0.015 part of the stabilizer calcium stearate. Add the above materials into a high-speed mixer and mix them evenly at a rotation speed of 300 r / min and then extrude and pelletize to obtain masterbatch 2; (2) Add the masterbatch 1 and masterbatch 2 prepared respectively in the above step (1) into a twin-screw extruder and mix them for 20 min at a stirring speed of 350 r / min to make the materials fully mixed evenly; conduct melt extrusion and pelletization. The process conditions for extrusion and pelletization are: conveying section temperature 200 °C, melting section temperature 220 °C, extrusion section temperature 180 °C, screw rotation speed 150 r / min, and pelletizing motor rotation speed 720 r / min.

[0031] Inject and mold the pellets prepared in Examples 1-5 and Comparative Examples 1-2. The temperatures of each section of the injection molding machine are 170 °C, 180 °C, 190 °C, 195 °C, 195 °C, the holding pressure is 60 MPa, the holding time is 40 s, and the cooling time is 15 s to obtain injection molded samples and test their properties.

[0032] The tests for various properties are carried out according to the following standards: Melt index, carried out according to the standard of GB / T 3682.1-2018, and the test conditions are 230 °C and a load of 2.16 kg.

[0033] Bending property test, carried out according to the standard of GB / T 9341-2008.

[0034] Tensile property test, carried out according to the standard of GB / T 1040.2-2006.

[0035] Impact property test, carry out the notched Izod impact strength test according to GB / T 1043.1-2008. The sample has a V-shaped notch. After being placed for 40-96 h, carry out the impact test under the conditions of 23 °C and low temperature -20 °C. The test method for the low-temperature impact test is to place the sample after conditioning in a low-temperature refrigerator for 2 h and then quickly carry out the impact test.

[0036] Odor test was conducted in accordance with the VDA 270-2018 standard. Note: Odor level: 1, no abnormal odor; 2, slightly abnormal odor; 3, has a smell but not irritating; 4, has an irritating odor; 5, strong irritating odor; 6, intolerable smell.

[0037] Table 1 Formulations of Examples 1-5 and Comparative Examples 1-2, by weight parts.

[0038]

[0039] Table 2 Performance test results of Examples 1-5 and Comparative Examples 1-2

[0040] It can be seen from the above results that the composite material prepared by the present invention has a relatively high melt index and good fluidity. Compared with Comparative Example 1, the melt index is increased by at least 14% or more; at the same time, the low-temperature toughness of polypropylene is improved. Under the condition of -20 °C, the impact strength is increased by more than twice, and the comprehensive performance of the composite material is excellent.

[0041] It can be seen from the comparison between Examples 1-5 and Comparative Example 2 that under the conditions of reducing the degradation masterbatch and optimizing the extrusion process, the content of volatile organic compounds (VOC) in the composite material is significantly reduced, avoiding the problems of residual abnormal odor of the product and easy yellowing of the product.

[0042] The above are only the preferred embodiments of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope covered by the present invention.

Claims

1. A low-temperature toughness high-flow polypropylene composite material, characterized in that: It comprises the following components in parts by weight: High flow polypropylene resin: 40-80 parts by weight; Impact-resistant copolymer polypropylene resin: 20-60 parts by weight; Degradable molecular weight regulator masterbatch: 0.1-0.6 parts by weight; Antioxidant: 0.1-0.2 parts by weight; Nucleating agent: 0.03-0.06 parts by weight; Stabilizer: 0.01-0.05 parts by weight.

2. The low-temperature toughness and high-flow polypropylene composite material according to claim 1, characterized in that: The high-flow polypropylene resin is homopolymer polypropylene or a copolymer of propylene and ethylene, with a melt index of 60-80 g / 10min at 230°C and a load of 2.16 kg and a weight average molecular weight of 170,000-200,000 g / mol; the ethylene content in the copolymer of propylene and ethylene is 0-3%.

3. The low-temperature toughness and high-flow polypropylene composite material according to claim 1, characterized in that: The impact-resistant copolymer polypropylene resin is a copolymer of propylene and ethylene, wherein the ethylene content is 10-20%, the rubber phase content is 25-40 wt%, and the melt index is 5-15 g / 10 min at 230° C. and a load of 2.16 kg.

4. The low-temperature toughness and high-flow polypropylene composite material according to claim 1, characterized in that: The degradable molecular weight regulator masterbatch is a composite material of peroxide and polypropylene resin, wherein the content of peroxide is 8-25%; the peroxide is one of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane or 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxynonane.

5. The low-temperature toughness and high-flow polypropylene composite material according to claim 1, characterized in that: The antioxidant comprises a main antioxidant and an auxiliary antioxidant, the mass ratio of the main antioxidant to the auxiliary antioxidant is 1:1-2, the main antioxidant is a hindered phenol antioxidant, and the auxiliary antioxidant is a phosphite antioxidant.

6. The low-temperature toughness and high-flow polypropylene composite material according to claim 1, characterized in that: The hindered phenol antioxidant is at least one of 2,6-di-tert-butyl-p-cresol, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and n-octadecylβ-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; and the phosphite antioxidant is at least one of tris[2.4-di-tert-butylphenyl]phosphite and diisobutyl diphosphite pentaerythritol.

7. The low-temperature toughness and high-flow polypropylene composite material according to claim 1, characterized in that: The nucleating agent is one or more of aryl phosphate salts, dibenzylidene sorbitol, substituted benzoic acid aluminum salts, dehydroabietic acid soaps, and cyclic dicarboxylate nucleating agents.

8. The low-temperature toughness and high-flow polypropylene composite material according to claim 1, characterized in that: The stabilizer is any one of calcium stearate or zinc stearate.

9. A method for preparing a low-temperature toughness high-flow polypropylene composite material, characterized in that: The specific steps are as follows: (1) Preparation of blended masterbatch: S1: adding high-flow polypropylene resin, degradation-type molecular weight regulator masterbatch, antioxidant, nucleating agent and stabilizer into a high-speed mixer according to their weight parts, wherein the high-flow polypropylene resin is 0-65 parts, the degradation-type molecular weight regulator masterbatch is 0-0.2 parts, the main antioxidant is 0.01-0.05 parts, the auxiliary antioxidant is 0.02-0.08 parts, the nucleating agent is 0.02-0.05 parts, and the stabilizer is 0.01-0.05 parts. After all the components are uniformly mixed, the masterbatch 1 is obtained by a twin-screw extruder granulator; the extrusion temperature is 180-220°C, and the screw speed is 100-160 r / min; the melt index of the masterbatch 1 at 230°C and a load of 2.16 kg is 70-150g / 10min; S2: Add impact-resistant copolymer polypropylene resin, degradation-type molecular weight regulator masterbatch, antioxidant, nucleating agent and stabilizer into a high-speed mixer according to their weight parts, wherein the impact-resistant copolymer polypropylene resin is 0-50 parts, the degradation-type molecular weight regulator masterbatch is 0-0.6 parts, the main antioxidant is 0-0.03 parts, the auxiliary antioxidant is 0-0.05 parts, the nucleating agent is 0-0.05 parts, and the stabilizer is 0-0.03 parts. After all the components are evenly mixed, the masterbatch 2 is obtained by a twin-screw extruder granulator; the extrusion section temperature is 180-220 ° C, and the screw speed is 100-160 r / min; the melt index of the masterbatch 2 at 230 ° C and a load of 2.16 kg is 10-60 g / 10min; (2) The master batch 1 and the master batch 2 respectively prepared in the above step (1) are added into a high-speed mixer, and mixed at a stirring speed of 300-600 r / min for 20-30 min to fully mix the materials, and the mixed materials are added into a twin-screw extruder for melt extrusion granulation to prepare the low-temperature toughness and high-flow polypropylene composite material.

10. The preparation method according to claim 9, characterized in that: The extrusion granulation process conditions are: conveying section temperature 80-210°C, melting section temperature 200-250°C, extrusion section temperature 170-220°C, screw speed 120-180 r / min, extruded material strips are granulated after being cooled with 23°C water, and the pelletizing motor speed is 600-800 r / min.

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