A kind of nucleating agent composition and preparation process of polypropylene

Abstract

The present application relates to the field of nucleating agents, and specifically discloses a preparation process of a nucleating agent composition and polypropylene. The nucleating agent composition includes 2,2'-methylene-bis-(4,6-di-tert-butylphenyl) sodium phosphate, bis[2,2'-methylene-bis(4,6-di-tert-butylphenyl) phosphate] hydroxyaluminum and lithium stearate. The nucleating agent composition of the present application has excellent nucleation and nucleation efficiency, and can further improve the crystallization behavior of polypropylene, so that the spherulite defects formed by polypropylene are few and the size is small, and polypropylene with further improved mechanical properties and optical properties is prepared.

Description

Technical Field

[0001] The present application relates to the field of nucleating agents, and in particular to a nucleating agent composition and a preparation process of polypropylene. Background Art

[0002] Polypropylene is synthesized through polymerization reaction. Due to its regular molecular chain structure and high flexibility, polypropylene is a polymer material with strong crystallization properties. This makes its molding cycle longer and the spherulite size larger during the processing. This crystallization behavior will bring adverse effects to polypropylene, such as reduced mechanical properties and transparency, limiting its application in structural parts, packaging materials and other fields.

[0003] The addition of nucleating agents can change the crystallization behavior of polypropylene, thereby improving the defects of long processing cycle and poor product performance during the processing of polypropylene. Organic phosphates are a common type of nucleating agent, among which 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate sodium has the advantages of strong nucleating ability, good thermal stability and no special odor, which can improve the optical and mechanical properties of polypropylene. However, due to its poor dispersibility in the polypropylene matrix, it affects its nucleation efficiency, making its improvement on the performance of polypropylene limited. Summary of the invention

[0004] The present application is made in view of the above-mentioned problems, and its purpose is to provide a nucleating agent composition, which can further improve the mechanical properties and optical properties of polypropylene.

[0005] The first aspect of the present application provides a nucleating agent composition, which includes sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate, bis[2,2′-methylenebis(4,6-di-tert-butylphenyl) phosphate]hydroxyaluminum and lithium stearate.

[0006] Sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate has the advantage of strong nucleation ability. As a polypropylene nucleating agent, it can improve the mechanical properties and transparency of polypropylene materials. However, due to its high melting point and large particle size, its dispersibility in polypropylene resin is poor, which makes its effect on improving the performance of polypropylene materials limited. The addition of lithium stearate can make the nucleating agent composition further improve the mechanical properties and optical properties of polypropylene materials. This may be because sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate can react with lithium stearate through ion exchange during the polypropylene processing process to generate organic phosphates with smaller particle size and better dispersibility in situ, which induces a better crystallization rate of polypropylene, making the nucleating effect and nucleation efficiency of the nucleating agent composition better, and the mechanical properties and optical properties of polypropylene are further improved. However, it still faces the problem of low content of organic phosphates generated in situ and limited improvement of polypropylene performance. The applicant found in the experiment that by further adding bis[2,2'-methylenebis(4,6-di-tert-butylphenyl)phosphate]hydroxyaluminum to the nucleating agent composition, the nucleating agent composition can further improve the mechanical properties and optical properties of polypropylene. This may be because the addition of bis[2,2'-methylenebis(4,6-di-tert-butylphenyl)phosphate]hydroxyaluminum can promote the ion exchange reaction between 2,2'-methylene-bis-(4,6-di-tert-butylphenyl)phosphate sodium and lithium stearate during the processing. The reason may be that the hydroxyl group in bis[2,2'-methylenebis(4,6-di-tert-butylphenyl)phosphate]hydroxyaluminum The base can promote the occurrence of ion exchange reaction through the proton transfer mechanism, so that 2,2'-methylene-bis-(4,6-di-tert-butylphenyl) sodium phosphate generates more organic phosphates with smaller particle size and better dispersibility in situ, and fully exerts the nucleating effect. In addition, bis[2,2'-methylenebis(4,6-di-tert-butylphenyl) phosphate] hydroxyaluminum also has excellent dispersibility and nucleating effect, so that the nucleating effect and nucleating efficiency of the nucleating agent composition are improved, which is beneficial to further improve the crystallization behavior of polypropylene, so that the spherulites formed by polypropylene have fewer defects and smaller sizes, and polypropylene with further improved mechanical properties and optical properties is prepared.

[0007] In any embodiment, based on the total mass of the nucleating agent composition, the mass proportion of the sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate is 40%-60%, the mass proportion of the bis[2,2′-methylenebis(4,6-di-tert-butylphenyl) phosphate]hydroxyaluminum is 20%-30%, and the mass proportion of the lithium stearate is 20%-40%.

[0008] The mass proportions of sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate, bis[2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate] hydroxyaluminum and lithium stearate are within the above ranges. The three substances can further enhance the nucleation effect and nucleation efficiency through synergistic effects, and further improve the crystallization behavior of polypropylene, so that the spherulites formed by polypropylene have fewer defects and smaller sizes, thereby preparing polypropylene with further improved mechanical and optical properties.

[0009] In any embodiment, in the nucleating agent composition, the ratio of the total mass of the sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate and the bis[2,2′-methylenebis(4,6-di-tert-butylphenyl) phosphate]hydroxyaluminum to the mass of the lithium stearate is 1.5:1-4:1.

[0010] When the mass ratio of the total mass of sodium 2,2'-methylene-bis-(4,6-di-tert-butylphenyl) phosphate and bis[2,2'-methylene-bis(4,6-di-tert-butylphenyl) phosphate]hydroxyaluminum to lithium stearate is within the above range, it can be avoided that the content of the aryl phosphate with high efficiency inducing nucleation in the nucleating agent composition is too small due to excessive lithium stearate, and it can also be avoided that the sodium 2,2'-methylene-bis-(4,6-di-tert-butylphenyl) phosphate in the nucleating agent composition has poor dispersibility and cannot fully exert the nucleating effect due to too little lithium stearate. When the ratio of the total mass of sodium 2,2'-methylene-bis-(4,6-di-tert-butylphenyl) phosphate and bis[2,2'-methylene-bis(4,6-di-tert-butylphenyl) phosphate]hydroxyaluminum to the mass of lithium stearate is within the above range, the nucleating agent composition can further improve the crystallization behavior of polypropylene, and the mechanical properties and optical properties of polypropylene are further improved.

[0011] In any embodiment, in the nucleating agent composition, the mass ratio of the sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate to the bis[2,2′-methylenebis(4,6-di-tert-butylphenyl) phosphate]hydroxyaluminum is 1.5:1-3:1.

[0012] In the nucleating agent composition, when the mass ratio of sodium 2,2'-methylene-bis-(4,6-di-tert-butylphenyl) phosphate to bis[2,2'-methylene-bis(4,6-di-tert-butylphenyl) phosphate]hydroxyaluminum is within the above range, it can avoid that too much sodium 2,2'-methylene-bis-(4,6-di-tert-butylphenyl) phosphate makes the nucleating agent composition poor in dispersibility, and it can also avoid that too little sodium 2,2'-methylene-bis-(4,6-di-tert-butylphenyl) phosphate makes the in-situ generated organic phosphate with smaller particle size and better dispersibility too little. When the mass ratio of sodium 2,2'-methylene-bis-(4,6-di-tert-butylphenyl) phosphate to bis[2,2'-methylene-bis(4,6-di-tert-butylphenyl) phosphate]hydroxyaluminum is within the above range, the nucleating agent composition can further improve the crystallization behavior of polypropylene, and the mechanical properties and optical properties of polypropylene are further improved.

[0013] In any embodiment, the average particle size of the sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate is 0.2 um-0.4 um.

[0014] When the average particle size of sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate is within the above range, it can prevent sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate from being difficult to disperse due to too large a particle size, and can also avoid agglomeration due to too small a particle size, so that it has more excellent dispersibility and nucleation efficiency, and the nucleation effect and nucleation efficiency of sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate added to the nucleating agent composition are improved, so that the nucleating agent composition further improves the crystallization behavior of polypropylene, and the mechanical properties and optical properties of polypropylene are further improved, which has an impact.

[0015] The second aspect of the present application provides a method for preparing polypropylene, the preparation method comprising: mixing a nucleating agent composition with a polypropylene matrix resin, adding the mixture into an extruder for extrusion, and preparing polypropylene; wherein the nucleating agent composition comprises sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate, bis[2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate] hydroxyaluminum and lithium stearate.

[0016] The nucleating agent composition includes sodium 2,2'-methylene-bis-(4,6-di-tert-butylphenyl) phosphate, bis[2,2'-methylene-bis(4,6-di-tert-butylphenyl) phosphate] hydroxyaluminum and lithium stearate, which is beneficial to further improve the crystallization behavior of polypropylene, so that the spherulites formed by polypropylene have fewer defects and smaller sizes, and polypropylene with further improved mechanical properties and optical properties is prepared.

[0017] In any embodiment, the temperature range of the extruder from one section to the die head is 190°C-250°C.

[0018] When the temperature from the first section to the die head of the extruder is within the above range, it can not only ensure the good performance of polypropylene during the extrusion process, but also increase the content of organic phosphates with smaller particles, better dispersibility and better nucleation effect generated in situ through ion exchange reaction during the extrusion process, thereby further improving the crystallization behavior of polypropylene, and the mechanical properties and optical properties of polypropylene are further improved.

[0019] In any embodiment, the temperature of the fourth section of the extruder is 240°C-250°C.

[0020] When the temperature of the fourth section of the extruder is within the above range, it can not only meet the preparation conditions of polypropylene, but also further improve the conversion rate of 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) sodium phosphate in the nucleating agent composition into organic phosphates with smaller particles, better dispersibility and better nucleating effect during the extrusion process, thereby further improving the crystallization behavior of polypropylene, and the mechanical properties and optical properties of polypropylene are further improved.

[0021] In any embodiment, the mass ratio of the nucleating agent composition to the polypropylene matrix resin is 0.5:1000-4:1000.

[0022] The nucleating agent composition includes sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate, bis[2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate]hydroxyaluminum and lithium stearate. The synergistic effect between the three substances improves the nucleation induction ability and nucleation efficiency of the nucleating agent composition. Under the same addition amount, the nucleating agent composition of the present application has a better improvement on the mechanical properties of polypropylene, which is beneficial to further improve the mechanical properties and optical properties of polypropylene.

[0023] In summary, the present application includes at least one of the following beneficial technical effects:

[0024] 1. The nucleating agent composition of the present application has excellent nucleation effect and nucleation efficiency, which is conducive to further improving the crystallization behavior of polypropylene, so that the spherulites formed by polypropylene have fewer defects and smaller sizes, and the prepared polypropylene has further improved mechanical properties and optical properties. This may be because 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) sodium phosphate can react with lithium stearate through ion exchange during the polypropylene processing process to generate organic phosphates with smaller particle size and better dispersibility in situ, which induces a better crystallization rate of polypropylene, making the nucleating effect of the nucleating agent composition more excellent, and the mechanical properties and optical properties of polypropylene are further improved. Further adding bis[2,2'-methylenebis(4,6-di-tert-butylphenyl)phosphate]hydroxyaluminum can further improve the mechanical properties and optical properties of polypropylene. This may be because the hydroxyl group in bis[2,2'-methylenebis(4,6-di-tert-butylphenyl)phosphate]hydroxyaluminum can promote the ion exchange reaction between 2,2'-methylene-bis-(4,6-di-tert-butylphenyl) phosphate sodium and lithium stearate during processing through a proton transfer mechanism, so that 2,2'-methylene-bis-(4,6-di-tert-butylphenyl) phosphate sodium generates more organic phosphates with smaller particle size and better dispersibility in situ, fully exerting the nucleating effect, and bis[2,2'-methylenebis(4,6-di-tert-butylphenyl)phosphate]hydroxyaluminum also has an excellent nucleating effect, so that the nucleating agent composition has a better nucleating effect than the single nucleating agent substance, further improving the mechanical properties and optical properties of polypropylene.

[0025] 2. The present application adopts 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) sodium phosphate with an average particle size of 0.2um-0.4um, so that the nucleation effect and nucleation efficiency of the added 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) sodium phosphate can be further improved, so that the nucleating agent composition can further improve the crystallization behavior of polypropylene, and the mechanical properties and optical properties of polypropylene are further improved.

[0026] 3. In the preparation process of the present application, by setting the temperature of the fourth section of the extruder to 240°C-250°C, the preparation conditions of polypropylene can be met, and the conversion rate of 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) sodium phosphate in the nucleating agent composition to an organic phosphate with smaller particles, better dispersibility and better nucleating effect can be further improved during the extrusion process, thereby further improving the crystallization behavior of polypropylene, and the mechanical properties and optical properties of polypropylene are further improved. DETAILED DESCRIPTION

[0027] The present application is further described in detail below in conjunction with embodiments and comparative examples.

[0028] In the following examples, if no specific conditions are specified, the reaction was carried out according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following examples can be obtained from common commercial sources. Example

[0029] 1. Preparation method Example 1

[0030] At room temperature, sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate, bis[2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate] hydroxyaluminum, and lithium stearate are added to a high-speed stirrer and mixed evenly to obtain a nucleating agent composition. Based on the total mass of the nucleating agent composition, the mass proportion of sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate is 50%, and the average particle size is 0.3um; the mass proportion of bis[2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate] hydroxyaluminum is 20%, and the mass proportion of lithium stearate is 30%.

[0031] The nucleating agent composition and the polypropylene matrix resin were uniformly mixed in a high-speed mixer at a mass ratio of 2:1000, and the mixture was extruded through a twin-screw extruder to prepare polypropylene. The temperatures of the extruder from the feed port to each zone of the die were 190°C, 210°C, 228°C, 242°C, 230°C, 210°C, and 200°C, respectively.

[0032] The prepared polypropylene was used to prepare standard specimens required for performance testing by injection molding in an injection molding machine, and the temperature of the injection molding machine from the first stage to the head was 200°C-230°C. Example 2

[0033] At room temperature, sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate, bis[2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate] hydroxyaluminum, and lithium stearate are added to a high-speed stirrer and mixed evenly to obtain a nucleating agent composition. Based on the total mass of the nucleating agent composition, the mass proportion of sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate is 60%, and the average particle size is 0.3um; the mass proportion of bis[2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate] hydroxyaluminum is 20%, and the mass proportion of lithium stearate is 20%.

[0034] The nucleating agent composition and the polypropylene matrix resin were uniformly mixed in a high-speed mixer at a mass ratio of 2:1000, and the mixture was extruded through a twin-screw extruder to prepare polypropylene. The temperatures of the extruder from the feed port to each zone of the die were 190°C, 210°C, 228°C, 242°C, 230°C, 210°C, and 200°C, respectively.

[0035] The prepared polypropylene was used to prepare standard specimens required for performance testing by injection molding in an injection molding machine, and the temperature of the injection molding machine from the first stage to the head was 200°C-230°C. Example 3

[0036] At room temperature, sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate, bis[2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate] hydroxyaluminum, and lithium stearate are added to a high-speed stirrer and mixed evenly to obtain a nucleating agent composition. Based on the total mass of the nucleating agent composition, the mass proportion of sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate is 40%, and the average particle size is 0.3um; the mass proportion of bis[2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate] hydroxyaluminum is 20%, and the mass proportion of lithium stearate is 40%.

[0037] The nucleating agent composition and the polypropylene matrix resin were uniformly mixed in a high-speed mixer at a mass ratio of 2:1000, and the mixture was extruded through a twin-screw extruder to prepare polypropylene. The temperatures of the extruder from the feed port to each zone of the die were 190°C, 210°C, 228°C, 242°C, 230°C, 210°C, and 200°C, respectively.

[0038] The prepared polypropylene was used to prepare standard specimens required for performance testing by injection molding in an injection molding machine, and the temperature of the injection molding machine from the first stage to the head was 200°C-230°C. Example 4

[0039] At room temperature, sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate, bis[2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate] hydroxyaluminum, and lithium stearate are added to a high-speed stirrer and mixed evenly to obtain a nucleating agent composition. Based on the total mass of the nucleating agent composition, the mass proportion of sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate is 35%, and the average particle size is 0.3um; the mass proportion of bis[2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate] hydroxyaluminum is 15%, and the mass proportion of lithium stearate is 50%.

[0040] The nucleating agent composition and the polypropylene matrix resin were uniformly mixed in a high-speed mixer at a mass ratio of 2:1000, and the mixture was extruded through a twin-screw extruder to prepare polypropylene. The temperatures of the extruder from the feed port to each zone of the die were 190°C, 210°C, 228°C, 242°C, 230°C, 210°C, and 200°C, respectively.

[0041] The prepared polypropylene was used to prepare standard specimens required for performance testing by injection molding in an injection molding machine, and the temperature of the injection molding machine from the first stage to the head was 200°C-230°C. Example 5

[0042] At room temperature, sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate, bis[2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate] hydroxyaluminum, and lithium stearate are added to a high-speed stirrer and mixed evenly to obtain a nucleating agent composition. Based on the total mass of the nucleating agent composition, the mass proportion of sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate is 60%, and the average particle size is 0.3um; the mass proportion of bis[2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate] hydroxyaluminum is 30%, and the mass proportion of lithium stearate is 10%.

[0043] The nucleating agent composition and the polypropylene matrix resin were uniformly mixed in a high-speed mixer at a mass ratio of 2:1000, and the mixture was extruded through a twin-screw extruder to prepare polypropylene. The temperatures of the extruder from the feed port to each zone of the die were 190°C, 210°C, 228°C, 242°C, 230°C, 210°C, and 200°C, respectively.

[0044] The prepared polypropylene was used to prepare standard specimens required for performance testing by injection molding in an injection molding machine, and the temperature of the injection molding machine from the first stage to the head was 200°C-230°C. Example 6

[0045] At room temperature, sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate, bis[2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate] hydroxyaluminum, and lithium stearate are added to a high-speed stirrer and mixed evenly to obtain a nucleating agent composition. Based on the total mass of the nucleating agent composition, the mass proportion of sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate is 50%, and the average particle size is 0.2um; the mass proportion of bis[2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate] hydroxyaluminum is 20%, and the mass proportion of lithium stearate is 30%.

[0046] The nucleating agent composition and the polypropylene matrix resin were uniformly mixed in a high-speed mixer at a mass ratio of 2:1000, and the mixture was extruded through a twin-screw extruder to prepare polypropylene. The temperatures of the extruder from the feed port to each zone of the die were 190°C, 210°C, 228°C, 242°C, 230°C, 210°C, and 200°C, respectively.

[0047] The prepared polypropylene was used to prepare standard specimens required for performance testing by injection molding in an injection molding machine, and the temperature of the injection molding machine from the first stage to the head was 200°C-230°C. Example 7

[0048] At room temperature, sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate, bis[2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate] hydroxyaluminum, and lithium stearate are added to a high-speed stirrer and mixed evenly to obtain a nucleating agent composition. Based on the total mass of the nucleating agent composition, the mass proportion of sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate is 50%, and the average particle size is 0.4um; the mass proportion of bis[2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate] hydroxyaluminum is 20%, and the mass proportion of lithium stearate is 30%.

[0049] The nucleating agent composition and the polypropylene matrix resin were uniformly mixed in a high-speed mixer at a mass ratio of 2:1000, and the mixture was extruded through a twin-screw extruder to prepare polypropylene. The temperatures of the extruder from the feed port to each zone of the die were 190°C, 210°C, 228°C, 242°C, 230°C, 210°C, and 200°C, respectively.

[0050] The prepared polypropylene was used to prepare standard specimens required for performance testing by injection molding in an injection molding machine, and the temperature of the injection molding machine from the first stage to the head was 200°C-230°C. Example 8

[0051] At room temperature, sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate, bis[2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate] hydroxyaluminum, and lithium stearate are added to a high-speed stirrer and mixed evenly to obtain a nucleating agent composition. Based on the total mass of the nucleating agent composition, the mass proportion of sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate is 50%, and the average particle size is 3um; the mass proportion of bis[2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate] hydroxyaluminum is 20%, and the mass proportion of lithium stearate is 30%.

[0052] The nucleating agent composition and the polypropylene matrix resin were uniformly mixed in a high-speed mixer at a mass ratio of 2:1000, and the mixture was extruded through a twin-screw extruder to prepare polypropylene. The temperatures of the extruder from the feed port to each zone of the die were 190°C, 210°C, 228°C, 242°C, 230°C, 210°C, and 200°C, respectively.

[0053] The prepared polypropylene was used to prepare standard specimens required for performance testing by injection molding in an injection molding machine, and the temperature of the injection molding machine from the first stage to the head was 200°C-230°C. Example 9

[0054] At room temperature, sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate, bis[2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate] hydroxyaluminum, and lithium stearate are added to a high-speed stirrer and mixed evenly to obtain a nucleating agent composition. Based on the total mass of the nucleating agent composition, the mass proportion of sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate is 50%, and the average particle size is 0.3um; the mass proportion of bis[2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate] hydroxyaluminum is 20%, and the mass proportion of lithium stearate is 30%.

[0055] The nucleating agent composition and the polypropylene matrix resin were uniformly mixed in a high-speed mixer at a mass ratio of 4:1000, and the mixture was extruded through a twin-screw extruder to prepare polypropylene. The temperatures of the extruder from the feed port to each zone of the die were 190°C, 210°C, 228°C, 242°C, 230°C, 210°C, and 200°C, respectively.

[0056] The prepared polypropylene was used to prepare standard specimens required for performance testing by injection molding in an injection molding machine, and the temperature of the injection molding machine from the first stage to the head was 200°C-230°C. Example 10

[0057] At room temperature, sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate, bis[2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate] hydroxyaluminum, and lithium stearate are added to a high-speed stirrer and mixed evenly to obtain a nucleating agent composition. Based on the total mass of the nucleating agent composition, the mass proportion of sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate is 50%, and the average particle size is 0.3um; the mass proportion of bis[2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate] hydroxyaluminum is 20%, and the mass proportion of lithium stearate is 30%.

[0058] The nucleating agent composition and the polypropylene matrix resin were uniformly mixed in a high-speed mixer at a mass ratio of 2:1000, and the mixture was extruded through a twin-screw extruder to prepare polypropylene. The temperatures of the extruder from the feed port to the die head were 190°C, 200°C, 210°C, 218°C, 210°C, 200, and 190°C, respectively.

[0059] The prepared polypropylene was used to prepare standard specimens required for performance testing by injection molding in an injection molding machine, and the temperature of the injection molding machine from the first stage to the head was 200°C-230°C.

[0060] Comparative Example 1

[0061] The polypropylene matrix resin was extruded through a twin-screw extruder to prepare polypropylene, wherein the temperatures of the extruder from the feed port to the die head were 190°C, 210°C, 228°C, 242°C, 230°C, 210°C, and 200°C, respectively.

[0062] The prepared polypropylene was used to prepare standard specimens required for performance testing by injection molding in an injection molding machine, and the temperature of the injection molding machine from the first stage to the head was 200°C-230°C.

[0063] Comparative Example 2

[0064] At room temperature, sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate, tri-coordinated [2,2′-methylene-bis-(4,6-di-tert-butylphenyl) aluminum phosphate, and lithium stearate are added to a high-speed stirrer and mixed evenly to obtain a nucleating agent composition. Based on the total mass of the nucleating agent composition, the mass proportion of sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate is 50%, and the average particle size is 0.3 um; the mass proportion of tri-coordinated [2,2′-methylene-bis-(4,6-di-tert-butylphenyl) aluminum phosphate is 20%, and the mass proportion of lithium stearate is 30%.

[0065] The nucleating agent composition and the polypropylene matrix resin were uniformly mixed in a high-speed mixer at a mass ratio of 2:1000, and the mixture was extruded through a twin-screw extruder to prepare polypropylene. The temperatures of the extruder from the feed port to each zone of the die were 190°C, 210°C, 228°C, 242°C, 230°C, 210°C, and 200°C, respectively.

[0066] The prepared polypropylene was used to prepare standard specimens required for performance testing by injection molding in an injection molding machine, and the temperature of the injection molding machine from the first stage to the head was 200°C-230°C.

[0067] Comparative Example 3

[0068] 2,2'-methylene-bis-(4,6-di-tert-butylphenyl) sodium phosphate and polypropylene matrix resin were mixed uniformly in a high-speed mixer at a mass ratio of 2:1000, and the mixture was extruded through a twin-screw extruder to prepare polypropylene. The average particle size of 2,2'-methylene-bis-(4,6-di-tert-butylphenyl) sodium phosphate was 0.3um. The temperatures of the extruder from the feed port to the die head were 190°C, 210°C, 228°C, 242°C, 230°C, 210, and 200°C, respectively.

[0069] The prepared polypropylene was used to prepare standard specimens required for performance testing by injection molding in an injection molding machine, and the temperature of the injection molding machine from the first stage to the head was 200°C-230°C.

[0070] Comparative Example 4

[0071] At room temperature, sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate and lithium stearate are added to a high-speed stirrer and mixed evenly to obtain a nucleating agent composition. Based on the total mass of the nucleating agent composition, the mass proportion of sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate is 70%, and the average particle size is 0.3um; the mass proportion of lithium stearate is 30%.

[0072] The nucleating agent composition and the polypropylene matrix resin were uniformly mixed in a high-speed mixer at a mass ratio of 2:1000, and the mixture was extruded through a twin-screw extruder to prepare polypropylene. The temperatures of the extruder from the feed port to each zone of the die were 190°C, 210°C, 228°C, 242°C, 230°C, 210°C, and 200°C, respectively.

[0073] The prepared polypropylene was used to prepare standard specimens required for performance testing by injection molding in an injection molding machine, and the temperature of the injection molding machine from the first stage to the head was 200°C-230°C.

[0074] Comparative Example 5

[0075] Bis[2,2'-methylenebis(4,6-di-tert-butylphenyl)phosphate]hydroxyaluminum and polypropylene matrix resin were uniformly mixed in a high-speed mixer at a mass ratio of 2:1000, and the mixture was extruded through a twin-screw extruder to prepare polypropylene. The temperatures of the extruder from the feed port to the die head were 190°C, 210°C, 228°C, 242°C, 230°C, 210, and 200°C, respectively.

[0076] The prepared polypropylene was used to prepare standard specimens required for performance testing by injection molding in an injection molding machine, and the temperature of the injection molding machine from the first stage to the head was 200°C-230°C.

[0077] Comparative Example 6

[0078] At room temperature, bis[2,2'-methylenebis(4,6-di-tert-butylphenyl)phosphate]hydroxyaluminum and lithium stearate are added to a high-speed stirrer and mixed evenly to obtain a nucleating agent composition. Based on the total mass of the nucleating agent composition, the mass proportion of bis[2,2'-methylenebis(4,6-di-tert-butylphenyl)phosphate]hydroxyaluminum is 70%, and the mass proportion of lithium stearate is 30%.

[0079] The nucleating agent composition and the polypropylene matrix resin were uniformly mixed in a high-speed mixer at a mass ratio of 2:1000, and the mixture was extruded through a twin-screw extruder to prepare polypropylene. The temperatures of the extruder from the feed port to each zone of the die were 190°C, 210°C, 228°C, 242°C, 230°C, 210°C, and 200°C, respectively.

[0080] The prepared polypropylene was used to prepare standard specimens required for performance testing by injection molding in an injection molding machine, and the temperature of the injection molding machine from the first stage to the head was 200°C-230°C.

[0081] 2. Performance test

[0082] 1. Test of flexural modulus

[0083] The specimens with the specifications of 80 mm × 10 mm × 4 mm were prepared, and the test standard was carried out according to GB / T 9341-2008 standard.

[0084] 2. Haze test

[0085] The specimens with the specification of 50 mm×50 mm×1 mm were prepared, and the test standard was carried out according to the ASTM D1003-07 standard.

[0086] III. Analysis of test results of various embodiments and comparative examples

[0087] The polypropylene of each embodiment and comparative example was prepared according to the above method, and the performance parameters were measured. The results are shown in Tables 1-3.

[0088] Table 1

[0089]

[0090] Table 2

[0091]

[0092] Table 3

[0093]

[0094] From the comparison of Examples 1-10 and Comparative Examples 1, 3, 4, 5, and 6 in Table 1, it can be seen that compared with no addition of the nucleating agent composition, only addition of 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) sodium phosphate nucleating agent, only addition of bis[2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate] hydroxyaluminum nucleating agent or addition of 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) sodium phosphate and lithium stearate nucleating agent composition, 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) sodium phosphate and lithium stearate nucleating agent composition, the nucleating agent composition of the present application at the same addition amount can further improve the flexural modulus and transparency of polypropylene through the synergistic effect between the three substances.

[0095] From the comparison of Examples 1-10 in Table 1 and Comparative Example 2 in Table 3, it can be seen that compared with tri-coordinated [2,2'-methylenebis(4,6-di-tert-butylphenyl)aluminum phosphate, the bis[2,2'-methylenebis(4,6-di-tert-butylphenyl)phosphate]hydroxyaluminum added to the nucleating agent composition can effectively improve the flexural modulus and transparency of polypropylene. However, tri-coordinated [2,2'-methylenebis(4,6-di-tert-butylphenyl)aluminum phosphate has poor thermal stability and does not promote the ion exchange reaction between 2,2'-methylene-bis-(4,6-di-tert-butylphenyl) sodium phosphate and lithium stearate. Therefore, the addition of tri-coordinated [2,2'-methylenebis(4,6-di-tert-butylphenyl)aluminum phosphate cannot further improve the flexural modulus performance and transparency of the nucleating agent composition for polypropylene.

[0096] From the comparison between Examples 1-3 and Examples 4-5, it can be seen that based on the total mass of the nucleating agent composition, when the mass proportion of 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) sodium phosphate is 40%-60%, the mass proportion of bis[2,2'-methylenebis(4,6-di-tert-butylphenyl) phosphate] hydroxyaluminum is 20%-30%, and the mass proportion of lithium stearate is 20%-40%, the improvement of the flexural modulus and transparency of polypropylene is better than that of nucleating agent compositions with other ratios.

[0097] From the comparison between Examples 1, 6, 7 and Example 8, it can be seen that the average particle size of sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate is 0.2 um-0.4 um, which is beneficial to further improve the flexural modulus and transparency of polypropylene.

[0098] It can be seen from Examples 1 and 10 and Tables 1 and 2 that when the temperature of the fourth section of the extruder is 240° C.-250° C., the flexural modulus and transparency of the polypropylene can be further improved.

[0099] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A method for preparing polypropylene, characterized in that: The preparation method comprises: uniformly mixing a nucleating agent composition and a polypropylene matrix resin in a high-speed mixer at a mass ratio of 2:1000, and extruding the mixture through a twin-screw extruder to prepare polypropylene; wherein the temperatures of various zones of the extruder from a feed port to a die are 190° C., 210° C., 228° C., 242° C., 230° C., 210° C., and 200° C., respectively; The preparation method of the nucleating agent composition comprises the following steps: adding sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate, bis[2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate] hydroxyaluminum and lithium stearate into a high-speed stirrer at room temperature, and mixing them uniformly to obtain the nucleating agent composition; based on the total mass of the nucleating agent composition, the mass proportion of sodium 2,2′-methylene-bis-(4,6-di-tert-butylphenyl) phosphate is 50%, and the average particle size is 0.3 um; the mass proportion of bis[2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate] hydroxyaluminum is 20%, and the mass proportion of lithium stearate is 30%.

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