A low-temperature high-toughness polypropylene composition and preparation method thereof

Abstract

The invention discloses a low-temperature high-toughness polypropylene composition and a preparation method thereof, which belongs to the technical field of polypropylene materials, and comprises the following raw materials in parts by weight: 100 parts of polypropylene, 7-11 parts of flame retardant additives, 0.1-0.15 parts of rubber, 0.06-0.1 parts of N,N'-dicyclohexyl terephthalamide, 0.05-0.1 parts of nucleating agents, 0.1-0.2 parts of lubricants, and 0.3-0.5 parts of antioxidants. The present invention uses HPN-20E nucleating agent and β-nucleating agent in combination, so that the polypropylene composition can obtain better low-temperature impact performance; by adding rubber, the low-temperature impact performance of the polypropylene composition can also be improved to a certain extent; in addition, the present invention adds a flame retardant additive to the polypropylene composition, which can give the composition safe, efficient and environmentally friendly flame retardant performance, and the flame retardant additive can also have a toughening effect on the polypropylene composition, synergistic nucleating agent, and further improve the toughness of the polypropylene composition.

Description

Technical Field

[0001] The invention belongs to the technical field of polypropylene materials, and in particular relates to a low-temperature high-toughness polypropylene composition and a preparation method thereof. Background Art

[0002] Polypropylene is a non-toxic, odorless, tasteless milky white highly crystalline polymer with a density of about 0.9g / cm 2 Polypropylene has high crystallinity and regular structure. It has excellent mechanical properties (high tensile strength) at room temperature. In addition, polypropylene has excellent heat resistance. It will not deform at 150°C without external force. In addition, polypropylene has good chemical stability. Except for being corroded by concentrated sulfuric acid and concentrated nitric acid, it is relatively stable to other chemical reagents. Polypropylene materials are widely used due to their good comprehensive properties, such as plastic products for daily use, especially in the automotive field. However, the brittleness of polypropylene at room temperature and low temperature limits its use in winter and severe cold environments. At the same time, the strength of polypropylene composites must be taken into account to ensure the wider application of parts. Therefore, toughening and low-temperature toughening of polypropylene are one of the important research directions of polypropylene composites today.

[0003] In addition, polypropylene is a hydrocarbon and has the disadvantage of being flammable, which also limits its application areas. Adding flame retardants to polypropylene is currently a common means of improving the flame retardancy of polypropylene. However, conventional flame retardants have a large polarity and poor compatibility with polypropylene. During use, they are easy to migrate to the surface of polypropylene, affecting the flame retardant effect of polypropylene. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a high-toughness polypropylene composition and a preparation method thereof.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A low-temperature high-toughness polypropylene composition, comprising the following raw materials, measured by weight: 100 parts of polypropylene, 7-11 parts of flame retardant additives, 0.1-0.15 parts of rubber, 0.06-0.1 parts of N,N'-dicyclohexyl terephthalamide, 0.05-0.1 parts of nucleating agents, 0.1-0.2 parts of lubricants, and 0.3-0.5 parts of antioxidants;

[0007] The preparation method of the polypropylene composition is specifically as follows:

[0008] The above raw materials are added into a high-speed mixer according to a proportion and mixed. After being mixed evenly, they are transferred into a twin-screw extruder, and subjected to melt extrusion, granulation and drying to obtain a polypropylene composition.

[0009] Furthermore, the rubber is one or more of radiation-crosslinked fully vulcanized carboxylated styrene-butadiene rubber, fully vulcanized nitrile rubber, fully vulcanized carboxylated nitrile rubber, fully vulcanized acrylate rubber and fully vulcanized silicone rubber.

[0010] Furthermore, the nucleating agent is nucleating agent HPN-20E, and N,N'-dicyclohexylterephthalamide is a β-nucleating agent. The combination of the two can make the polypropylene composition have better low-temperature impact performance; in addition, the addition of rubber can also improve the low-temperature impact performance of the polypropylene composition to a certain extent.

[0011] Furthermore, the lubricant is one or more of calcium stearate, zinc stearate, oleamide, erucamide and ethylene bisstearamide.

[0012] Furthermore, the antioxidant is one or more of antioxidant 1010 , antioxidant 1076 , antioxidant 168 and antioxidant 2246 .

[0013] Furthermore, the flame retardant additive is prepared by the following steps:

[0014] S1. DIC (N,N-diisopropylcarbodiimide, dehydration condensation agent), carboxyethylphenyl hypophosphorous acid, benzene and acetone are added to a three-necked flask with a stirring device, and nitrogen is introduced for protection. After stirring and dissolving evenly, 1,3-bis(aminopropyl)tetramethyldisiloxane, triethylamine and hydroquinone (inhibitor) are added to the system, and stirred for reaction for 3 hours at room temperature and under N2 protection. After the reaction is completed, the solvent (benzene and acetone) is removed by reduced pressure distillation, deionized water is added to the product, and mixed evenly, and the mixture is extracted with ethyl acetate, the organic layer is taken, dried over anhydrous magnesium sulfate, filtered, and ethyl acetate is removed by reduced pressure rotary distillation to obtain intermediate product 1; the ratio of DIC, carboxyethylphenyl hypophosphorous acid, 1,3-bis(aminopropyl)tetramethyldisiloxane, triethylamine and hydroquinone is 12.6g:0.1mol:0.11mol:10.1g:0.3g;

[0015] Under the action of DIC and triethylamine, -COOH on the carboxyethylphenylphosphorous acid molecule and -NH2 on the 1,3-bis(aminopropyl)tetramethyldisiloxane molecule undergo amidation reaction. By controlling the molar ratio of the two to be close to 1:1 and the 1,3-bis(aminopropyl)tetramethyldisiloxane slightly excessive, under the action of the inhibitor, only -NH2 at one end of the 1,3-bis(aminopropyl)tetramethyldisiloxane participates in the reaction to obtain the intermediate product 1. The reaction process is as follows:

[0016]

[0017] S2, first vacuum-dry the double-bond-terminated polyethylene at 40°C for 1 hour, then fill with nitrogen, inject toluene, stir to fully dissolve, add mercaptopropionic acid and azobisisobutyronitrile under nitrogen atmosphere, react at 80°C for 4 hours, wash the polymer with a large amount of anhydrous methanol, filter, and vacuum-dry at 40°C for 12 hours to obtain intermediate product 2; the ratio of the amount of double-bond-terminated polyethylene, mercaptopropionic acid and azobisisobutyronitrile is 0.1 mol:0.1 mol:0.2 g;

[0018] Under the action of azobisisobutyronitrile, the terminal unsaturated carbon-carbon double bond of the double-bond-terminated polyethylene undergoes a thiol-ene click reaction with mercaptopropionic acid to obtain the intermediate product 2. The reaction process is as follows:

[0019]

[0020] S3. Add intermediate product 2, triethylamine and toluene to a dry three-necked flask equipped with a stirring device, a condensing reflux device and a nitrogen conduit, introduce nitrogen, and continue to introduce it for 10 minutes, then add intermediate product 1 and DIC. After the addition, stir and react at room temperature under N2 protection for 3 hours. After the reaction is completed, wash with a large amount of anhydrous methanol, filter, and vacuum dry at 40°C for 12 hours to obtain a flame retardant additive; the ratio of intermediate product 2, triethylamine, intermediate product 1, and DIC is 0.1 mol: 10.1 g: 0.1 mol: 12.6 g;

[0021] The -COOH on the intermediate product 2 molecule undergoes an amidation reaction with the -NH2 on the intermediate product 1 molecule to obtain a flame retardant additive. The process is as follows:

[0022]

[0023] The flame retardant additive molecules obtained contain phosphate groups, N-containing groups, -Si-O-Si- segments and thioether bonds. The phosphate groups and N-containing groups belong to P-series flame retardant components and N-series flame retardant components respectively, and have different flame retardant mechanisms (condensed phase flame retardant, gas phase flame retardant, etc.), so that the flame retardant additive has a PN synergistic flame retardant effect, and the -Si-O-Si- segment is a good flame retardant and smoke suppression component, which can not only further improve the flame retardant properties of the flame retardant additive, but also improve the smoke suppression effect during the flame retardant process. The thioether bond has the effect of promoting cross-linking of the matrix to form carbon, exerting the flame retardant advantage, and further improving the flame retardant effect of the flame retardant additive. In summary, the flame retardant additive has a safe, efficient, halogen-free and environmentally friendly flame retardant effect.

[0024] In addition, flame retardant additives are polymer compounds, the main body of which is polyethylene molecular chains. Compared with small molecule flame retardants, polymer compounds have the advantages of being more heat-resistant and more stable, and the polyethylene molecular chains have a high compatibility with the PP matrix. Therefore, the flame retardant components can be more evenly distributed in the polypropylene composition. In addition, the polyethylene molecular chain has extremely high flexibility, and its interlacing between PP molecular chains can also achieve a toughening effect on PP and improve the toughness of the polypropylene composition. Finally, it should be supplemented that the -Si-O-Si- segment also has extremely high flexibility, which can further enhance the toughness of the polypropylene composition.

[0025] Beneficial effects of the present invention:

[0026] The present invention uses a HPN-20E nucleating agent and a β nucleating agent in a polypropylene composition, so that the polypropylene composition can obtain better low-temperature impact performance; the addition of rubber can also improve the low-temperature impact performance of the polypropylene composition to a certain extent; in addition, the present invention adds a flame retardant auxiliary agent to the polypropylene composition, the flame retardant auxiliary agent has a multi-effect flame retardant mechanism, belongs to a safe, efficient, halogen-free and environmentally friendly flame retardant component, can give the polypropylene composition safe, efficient and environmentally friendly flame retardant performance, and the flame retardant auxiliary agent can also have a toughening effect on the polypropylene composition, synergistically act with the nucleating agent, and further improve the toughness of the polypropylene composition; the polypropylene composition finally obtained has a wider application field and high application value. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Example 1

[0029] Preparation of flame retardant additives:

[0030] S1, 12.6g of DIC, 21.4g of carboxyethylphenyl hypophosphorous acid, 80mL of benzene and 120mL of acetone were added to a three-necked flask with a stirring device, nitrogen was introduced for protection, and after stirring and dissolving evenly, 27.3g of 1,3-bis(aminopropyl)tetramethyldisiloxane, 10.1g of triethylamine and 0.3g of hydroquinone were added to the system, and stirred for 3h at room temperature and under N2 protection. After the reaction was completed, the solvent (benzene and acetone) was removed by vacuum distillation, deionized water was added to the product, mixed evenly, and the mixture was extracted with ethyl acetate, the organic layer was taken, dried over anhydrous magnesium sulfate, filtered, and ethyl acetate was removed by vacuum rotary distillation to obtain intermediate product 1;

[0031] S2, first vacuum-dry 39g of double-bond-terminated polyethylene at 40°C for 1h, then fill with nitrogen, inject 150mL of toluene, stir to fully dissolve, add 12.1g of mercaptopropionic acid and 0.2g of azobisisobutyronitrile under nitrogen atmosphere, react at 80°C for 4h, wash the polymer with a large amount of anhydrous methanol, filter, and vacuum-dry at 40°C for 12h to obtain intermediate 2;

[0032] S3. Add 51.2 g of intermediate product 2, 10.1 g of triethylamine and 200 mL of toluene to a dry three-necked flask equipped with a stirring device, a condensing reflux device and a nitrogen tube, and introduce nitrogen for 10 minutes. Then add 44.5 g of intermediate product 1 and 12.6 g of DIC. After the addition, stir and react at room temperature under N2 protection for 3 hours. After the reaction is completed, wash with a large amount of anhydrous methanol, filter, and vacuum dry at 40°C for 12 hours to obtain a flame retardant additive.

[0033] Example 2

[0034] Preparation of flame retardant additives:

[0035] S1, 25.2g of DIC, 42.8g of carboxyethylphenyl hypophosphorous acid, 150mL of benzene and 200mL of acetone were added to a three-necked flask with a stirring device, nitrogen was introduced for protection, and after stirring and dissolving evenly, 54.6g of 1,3-bis(aminopropyl)tetramethyldisiloxane, 20.2g of triethylamine and 0.6g of hydroquinone were added to the system, and stirred for 3h at room temperature and under N2 protection. After the reaction was completed, the solvent (benzene and acetone) was removed by vacuum distillation, deionized water was added to the product, mixed evenly, and the mixture was extracted with ethyl acetate, the organic layer was taken, dried over anhydrous magnesium sulfate, filtered, and ethyl acetate was removed by vacuum rotary distillation to obtain intermediate product 1;

[0036] S2, first vacuum-dry 78g of double-bond-terminated polyethylene at 40°C for 1h, then fill with nitrogen, inject 280mL of toluene, stir to fully dissolve, add 24.2g of mercaptopropionic acid and 0.4g of azobisisobutyronitrile under nitrogen atmosphere, react at 80°C for 4h, wash the polymer with a large amount of anhydrous methanol, filter, and vacuum-dry at 40°C for 12h to obtain intermediate 2;

[0037] S3. Add 102.4 g of intermediate product 2, 20.2 g of triethylamine and 380 mL of toluene into a dry three-necked flask equipped with a stirring device, a condensing reflux device and a nitrogen tube, and introduce nitrogen for 10 minutes. Then add 89 g of intermediate product 1 and 25.2 g of DIC. After the addition, stir and react at room temperature under N2 protection for 3 hours. After the reaction is completed, wash with a large amount of anhydrous methanol, filter, and vacuum dry at 40°C for 12 hours to obtain a flame retardant additive.

[0038] The double-bond-terminated polyethylene used in Example 1-2: M n GPC =390g / mol, relative molecular mass distribution coefficient (D) is 1.34, M NMR =690 g / mol, and the end group selectivity is greater than 91%.

[0039] Example 3

[0040] Preparation of polypropylene composition:

[0041] 1 kg of polypropylene, 70 g of the flame retardant additive prepared in Example 1, 1 g of fully vulcanized carboxylated styrene-butadiene rubber, 0.6 g of N,N'-dicyclohexyl terephthalamide, 0.5 g of nucleating agent HPN-20E, 1 g of calcium stearate, and 3 g of antioxidant 1010 were added to a high-speed mixer for mixing. After mixing evenly, the mixture was transferred to a twin-screw extruder, and melt-extruded, granulated, and dried to obtain a polypropylene composition.

[0042] Example 4

[0043] Preparation of polypropylene composition:

[0044] 1 kg of polypropylene, 90 g of the flame retardant additive prepared in Example 2, 1.3 g of fully vulcanized nitrile rubber, 0.8 g of N,N'-dicyclohexyl terephthalamide, 0.7 g of nucleating agent HPN-20E, 1.5 g of zinc stearate, and 4 g of antioxidant 1076 were added to a high-speed mixer for mixing. After mixing evenly, the mixture was transferred to a twin-screw extruder, and melt-extruded, granulated, and dried to obtain a polypropylene composition.

[0045] Example 5

[0046] Preparation of polypropylene composition:

[0047] 1 kg of polypropylene, 110 g of the flame retardant additive prepared in Example 1, 1.5 g of fully vulcanized carboxyl nitrile rubber, 1 g of N,N'-dicyclohexyl terephthalamide, 1 g of nucleating agent HPN-20E, 2 g of oleic acid amide, and 5 g of antioxidant 168 were added to a high-speed mixer for mixing. After mixing evenly, the mixture was transferred to a twin-screw extruder, and melt-extruded, granulated, and dried to obtain a polypropylene composition.

[0048] Comparative Example 1

[0049] The polypropylene composition is obtained by replacing the flame retardant auxiliary agent in Example 3 with a nitrogen-phosphorus flame retardant of equal mass (HF-900A halogen-free flame retardant produced by Connaught Corporation) and keeping the other raw materials and the preparation process unchanged.

[0050] Comparative Example 2

[0051] Ordinary polypropylene.

[0052] The polypropylene compositions obtained in Examples 3-5 and Comparative Examples 1-2 were processed and cut into test samples, and the following performance tests were performed:

[0053] Simply supported beam notched impact strength: tested according to GB / T 1043-1993;

[0054] Flame retardant performance: oxygen index test of materials is carried out in accordance with GB / T 2406.2-2009;

[0055] The measured results are shown in the following table:

[0056]

[0057] It can be seen from the data in the above table that the polypropylene composition obtained by the present invention has relatively high low-temperature toughness and flame retardant properties. Combined with the data of Comparative Example 1, it can be seen that the flame retardant additive of the present invention can not only greatly improve the flame retardant properties of polypropylene, but also have a positive effect on the toughness of polypropylene.

[0058] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0059] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A low-temperature high-toughness polypropylene composition, characterized in that: According to weight parts, it includes the following raw materials: 100 parts of polypropylene, 7-11 parts of flame retardant additives, 0.1-0.15 parts of rubber, 0.06-0.1 parts of N,N'-dicyclohexyl terephthalamide, 0.05-0.1 parts of nucleating agent, 0.1-0.2 parts of lubricant, and 0.3-0.5 parts of antioxidant; Wherein, the flame retardant additive is prepared by the following steps: S1. DIC, carboxyethylphenylphosphite, benzene and acetone were added to a three-necked flask, nitrogen was introduced for protection, and after stirring and dissolving evenly, 1,3-bis(aminopropyl)tetramethyldisiloxane, triethylamine and hydroquinone were added to the system, and stirred for reaction for 3 hours at room temperature under N2 protection, and post-treated to obtain intermediate 1; S2, first vacuum-dry the double-bond-terminated polyethylene at 40°C for 1 hour, then fill with nitrogen, inject toluene, stir to fully dissolve, add mercaptopropionic acid and azobisisobutyronitrile under nitrogen atmosphere, react at 80°C for 4 hours, wash the polymer with a large amount of anhydrous methanol, filter, and dry to obtain intermediate 2; S3. Add intermediate product 2, triethylamine and toluene into a dry three-necked flask, introduce nitrogen for 10 minutes, then add intermediate product 1 and DIC. After the addition, stir and react for 3 hours at room temperature under N2 protection. After the reaction is completed, wash with a large amount of anhydrous methanol, filter and dry to obtain a flame retardant additive.

2. A low-temperature high-toughness polypropylene composition according to claim 1, characterized in that: Post-treatment process in step S1: remove the solvent by distillation under reduced pressure, add deionized water to the product, mix evenly, extract the mixture with ethyl acetate, take the organic layer, dry it over anhydrous magnesium sulfate, filter it, and remove the ethyl acetate by rotary distillation under reduced pressure.

3. A low-temperature high-toughness polypropylene composition according to claim 1, characterized in that: In step S1, the ratio of DIC, carboxyethylphenylphosphorous acid, 1,3-bis(aminopropyl)tetramethyldisiloxane, triethylamine and hydroquinone is 12.6 g: 0.1 mol: 0.11 mol: 10.1 g: 0.3 g.

4. A low-temperature high-toughness polypropylene composition according to claim 1, characterized in that: In step S2, the ratio of the amount of the terminal double-bond polyethylene, mercaptopropionic acid and azobisisobutyronitrile is 0.1 mol: 0.1 mol: 0.2 g.

5. A low-temperature high-toughness polypropylene composition according to claim 1, characterized in that: In step S3, the ratio of the amount of intermediate product 2, triethylamine, intermediate product 1, and DIC is 0.1 mol:10.1 g:0.1 mol:12.6 g.

6. A low-temperature high-toughness polypropylene composition according to claim 1, characterized in that: The rubber is one or more of radiation-crosslinked fully vulcanized carboxylated styrene-butadiene rubber, fully vulcanized nitrile rubber, fully vulcanized carboxylated nitrile rubber, fully vulcanized acrylate rubber and fully vulcanized silicone rubber.

7. A low-temperature high-toughness polypropylene composition according to claim 1, characterized in that: The nucleating agent is nucleating agent HPN-20E.

8. A low-temperature high-toughness polypropylene composition according to claim 1, characterized in that: The lubricant is one or more of calcium stearate, zinc stearate, oleamide, erucamide and ethylene bisstearamide.

9. A low-temperature high-toughness polypropylene composition according to claim 1, characterized in that: The antioxidant is one or more of antioxidant 1010 , antioxidant 1076 , antioxidant 168 and antioxidant 2246 .

10. The method for preparing a low-temperature high-toughness polypropylene composition according to claim 1, characterized in that: The details are as follows: The raw materials are added into a high-speed mixer according to a proportion and mixed. After being mixed evenly, they are transferred into a twin-screw extruder, and subjected to melt extrusion, granulation and drying to obtain a polypropylene composition.

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