Toughness-balanced and odor-low polypropylene composition and method for preparing the same

Abstract

This invention relates to the field of polypropylene compound technology, specifically to a polypropylene composition with a balanced rigidity and toughness and low odor, and its preparation method. It comprises the following raw materials in parts by weight: 90-97 parts polypropylene, 3-10 parts VLDPE, 0.15-0.3 parts antioxidant, 0.01-0.02 parts nucleating agent A, 0.02-0.03 parts nucleating agent B, 0.08-0.15 parts acid scavenger, and 0.05-0.1 parts lubricant. In this invention, antioxidant B (a 3-aryl-benzofuranone compound) replaces the commonly used antioxidant 168. After extrusion granulation and injection molding with nucleating agent A and novel β-nucleating agent B, the release of volatile organic compounds and the odor level are significantly reduced. Because the molecular structure of antioxidant B, nucleating agent A, and novel β-nucleating agent B is more stable, the benzene ring is less likely to break and generate free radicals during processing, reducing the generation of low-molecular-weight substances and thus improving the odor performance of polypropylene.

Description

Technical Field

[0001] This invention relates to the field of polypropylene composition technology, specifically to a polypropylene composition with a balance of rigidity and toughness and low odor, and its preparation method. Background Technology

[0002] Polypropylene (PP) possesses excellent physicochemical properties and is a widely used polymer material. The main drawbacks of PP are poor light resistance, easy aging, poor impact strength at low temperatures, and low elasticity, which limit its application in many fields. To address these issues, PP properties are improved through copolymerization modification, crosslinking modification, grafting modification, filler modification, and blending modification. Commonly used modified products mainly include polyethylene, rubber or elastomers, inorganic particles, and core-shell particles. Researching the modification process of PP materials to improve material properties and expand its applications has significant theoretical and practical value.

[0003] In the first half of 2023, China's modified polypropylene (PP) production reached 3.69 million tons, a year-on-year increase of 2.2%, with a market size of 43.26 billion yuan, a year-on-year increase of 1.8%. Modified PP has a wide range of applications, including modified PP for medical use, modified PP for automotive use (lightweighting, balance of rigidity and toughness, reduced shrinkage and odor levels, etc.), modified PP for sports flooring, and modified recycled PP.

[0004] The sources of VOCs in polypropylene are complex, occurring during polymerization, processing, transportation, and storage. During propylene polymerization, catalysts, comonomers, trace amounts of propane and polymerization solvents contained in propylene gas, and oligomers generated during polymerization may all remain in the polypropylene. In addition, antioxidants and other additives used in polypropylene processing may remain or degrade during processing or storage, easily generating volatile substances such as hydrocarbons, aldehydes, and ketones. Furthermore, the polypropylene backbone can degrade under the influence of light, heat, oxygen, and mechanical forces, producing alkanes, aldehydes, and ketones, leading to an increase in the VOC content in polypropylene. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a polypropylene composition with a balance of rigidity and toughness and low odor, with stable raw material structure and effective reduction of VOC release during processing.

[0006] The present invention also provides a preparation method that is simple and easy to implement, suitable for large-scale production, has stable quality, and good batch-to-batch reproducibility.

[0007] The polypropylene composition of the present invention, which has a balance of rigidity and toughness and low odor, is composed of the following raw materials in parts by weight:

[0008]

[0009]

[0010] The nucleating agent A is a phosphate-based stiffening nucleating agent;

[0011] The nucleating agent B is a β-type nucleating agent, and the β-type nucleating agent is NA-B99P. This component can improve the toughness of PP and has excellent thermal stability and yellowing resistance.

[0012] The antioxidant is a mixture of antioxidant A and antioxidant B, and the mass ratio of antioxidant A to antioxidant B is (0.05-0.1):(0.1-0.2).

[0013] The antioxidant A is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (antioxidant 1010), 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanuric acid (antioxidant 3114), and 1,3,5-trimethyl-2,4,6-(3,5-di-tert-butyl-4-hydroxybenzyl)benzene (antioxidant 1330).

[0014] Preferably, antioxidant A is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (antioxidant 1010), and antioxidant B is a 3-aryl-benzofuranone compound.

[0015] The antioxidant B, a 3-aryl-benzofuranone compound, has the structural formula shown in Formula I below:

[0016]

[0017] The conventional antioxidant 168 in the prior art has the following structural formula (Formula II):

[0018]

[0019] In summary, 3-aryl-benzofuranones have a more stable molecular structure, and the benzene ring is less likely to break and generate free radicals during processing.

[0020] The preparation method of the 3-aryl-benzofuranone compound is as follows: using 2,4-di-tert-butylphenol, glyoxylic acid solution and o-xylene as raw materials, and p-toluenesulfonic acid and nickel trifluoromethanesulfonate as catalysts, the reaction is carried out at 90-160℃ for 10-24h. After the reaction is completed, the compound is obtained by recrystallization.

[0021] The acid absorbent is a stearate, including calcium stearate, zinc stearate, and sodium stearate, with calcium stearate being preferred.

[0022] The lubricant is glycerol monostearate (GMS), which has a lubricating effect and reduces surface scratches caused by friction between the injection molded product and the mold and die opening.

[0023] The polypropylene mentioned is an impact-resistant copolymer polypropylene resin with a melt flow rate (MFR) of 8-12 g·(10 min). -1 The melting temperature range is 163℃-166℃, the ethylene content is 2.0-4.0% by mass, and the VLDPE is metallocene linear ultra-low density polyethylene with a melt flow rate (MFR) of 0.5-4.5 g·(10 min). -1 Its density is 0.9115-0.9250 g·cm³. 3 .

[0024] The method for preparing the polypropylene composition with a balance of rigidity and toughness and low odor according to the present invention includes the following steps:

[0025] 1) Mix polypropylene, VLDPE, antioxidant, nucleating agent A, nucleating agent B, acid absorbent, and lubricant thoroughly.

[0026] 2) Add the mixed material from step 1) into a twin-screw extruder for compounding and granulation.

[0027] The stirring speed is 100 rpm, and the stirring time is 1-3 minutes.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] (1) The present invention blends impact copolymer polypropylene, VLDPE, antioxidant A and antioxidant B, nucleating agent A and novel β-nucleating agent B, calcium stearate and lubricant, which achieves a synergistic effect and achieves a balance between rigidity and toughness.

[0030] (2) In this invention, antioxidant B: 3-aryl-benzofuranone compounds replace commonly used antioxidant 168. After extrusion granulation and injection molding with nucleating agent A and novel β-nucleating agent B, the release of volatile organic compounds (VOCs) and odor level are significantly reduced. Because the molecular structure of antioxidant B, nucleating agent A and novel β-nucleating agent B is more stable, the benzene ring is not easily broken and free radicals are generated during processing, reducing the generation of low molecular weight substances (low molecular weight substances are the main factor for VOC increase), thereby improving the odor performance of polypropylene. Detailed Implementation

[0031] The present invention will be further described below with reference to embodiments. The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple, and relevant parts can be referred to the description of the method embodiments.

[0032] The raw materials used in the following examples and comparative examples are:

[0033] Impact-resistant copolymer polypropylene: melt flow rate 10 g / (10 min) -1 Melting temperature 163℃, ethylene content 3.1% by mass;

[0034] VLDPE: Metallocene linear ultra-low density polyethylene: density 0.9150 g·cm³ -3 The melt mass flow rate is 2.0 g·(10 min). -1 ;

[0035] Antioxidant A: Antioxidant 1010;

[0036] Antioxidant B: 3-aryl-benzofuranone compounds, prepared by the following method:

[0037] Add 200g of 2,4-di-tert-butylphenol, 160mL of glyoxylic acid, 340mL of o-xylene, 500mg of p-toluenesulfonic acid, and 7.2g of nickel trifluoromethanesulfonate to the reaction vessel. Purge with nitrogen and evacuate the vessel. Heat the vessel to 90℃ and react for 10h. Distill off the o-xylene under reduced pressure. Cool the vessel to 70℃ and add 800mL of methanol dropwise while stirring. A dark red solid precipitates. Filter the solid and wash it with methanol to obtain the crude product. Dissolve the crude product in dichloromethane and recrystallize it with methanol dropwise to obtain a white solid, which is the finished product.

[0038] Nucleating agent A (phosphate): GRH-621;

[0039] POE: 8150;

[0040] Nucleating agent B: Novel β-nucleating agent ADK STAB NA-B99P;

[0041] Acid absorbent: Calcium stearate:

[0042] Lubricant: GMS.

[0043] The preparation methods for the examples and comparative examples are as follows:

[0044] The impact copolymer polypropylene, VLDPE, antioxidant A, antioxidant B, nucleating agent A, novel β-nucleating agent B, lubricant and acid absorbent were stirred at 100 rpm for 2 minutes until they were evenly mixed.

[0045] The well-mixed materials are then added to a twin-screw extruder for compounding and granulation.

[0046] Example 1

[0047] The aforementioned polypropylene composition, which exhibits a balance of rigidity and toughness and low odor, comprises the following raw materials in parts by weight:

[0048]

[0049] Example 2

[0050]

[0051]

[0052] Example 3

[0053]

[0054] Example 4

[0055]

[0056] Comparative Example 1

[0057]

[0058]

[0059] Comparative Example 2

[0060]

[0061] Comparative Example 3

[0062]

[0063] Comparative Example 4

[0064]

[0065] Comparative Example 5

[0066]

[0067]

[0068] Comparative Example 6

[0069]

[0070] Comparative Example 7

[0071]

[0072] Comparative Example 8

[0073]

[0074] The performance characterization results of the examples and comparative examples are shown in Tables 1-3 below:

[0075] Table 1 Performance Characterization of Examples

[0076]

[0077]

[0078] Table 2 Comparative Performance Characterization (I)

[0079]

[0080] Table 2 Comparative Performance Characterization (Part 3)

[0081]

[0082] Comparative Example 3 had no added nucleating agent A, Comparative Example 4 had no added novel nucleating agent B, Comparative Example 5 replaced phosphate nucleating agent A with sorbitol nucleating agent, and Comparative Example 8 replaced it with a common brand of β nucleating agent. All of these examples showed that the flexural modulus decreased and the odor level and response value increased significantly because they did not have a synergistic effect.

[0083] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A polypropylene composition with a balanced rigidity and toughness and low odor, characterized in that, It consists of the following parts by weight of raw materials: The nucleating agent A is a phosphate-based stiffening nucleating agent; The nucleating agent B is a β-type nucleating agent.

2. The polypropylene composition with a balanced rigidity and toughness and low odor according to claim 1, characterized in that, The antioxidant is a mixture of antioxidant A and antioxidant B, and the mass ratio of antioxidant A to antioxidant B is (0.05-0.1):(0.1-0.2).

3. The polypropylene composition with a balanced rigidity and toughness and low odor according to claim 2, characterized in that, The antioxidant A is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanuric acid, and 1,3,5-trimethyl-2,4,6-(3,5-di-tert-butyl-4-hydroxybenzyl)benzene.

4. The polypropylene composition with a balanced rigidity and toughness and low odor according to claim 2, characterized in that, The antioxidant A is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and the antioxidant B is a 3-aryl-benzofuranone compound; The preparation method of the 3-aryl-benzofuranone compound is as follows: using 2,4-di-tert-butylphenol, glyoxylic acid solution and o-xylene as raw materials, and p-toluenesulfonic acid and nickel trifluoromethanesulfonate as catalysts, the reaction is carried out at 90-160℃ for 10-24h. After the reaction is completed, the compound is obtained by recrystallization.

5. The polypropylene composition with a balanced rigidity and toughness and low odor according to claim 1, characterized in that, The acid absorbent is a stearate.

6. The polypropylene composition with a balanced rigidity and toughness and low odor according to claim 1, characterized in that, The lubricant is glycerol monostearate.

7. The polypropylene composition with a balanced rigidity and toughness and low odor according to claim 1, characterized in that, The polypropylene mentioned is an impact-resistant copolymer polypropylene resin with a melt flow rate (MFR) of 8-12 g·(10 min). -1 The melting temperature range is 163℃-166℃, the ethylene mass percentage content is 2.0-4.0%, and the VLDPE is metallocene linear ultra-low density polyethylene with a melt mass flow rate of 0.5-4.5 g·(10 min). -1 Its density is 0.9115-0.9250 g·cm³. 3 .

8. The polypropylene composition with a balanced rigidity and toughness and low odor according to claim 1, characterized in that, The β-type nucleating agent is NA-B99P.

9. A method for preparing a polypropylene composition with a balanced rigidity and toughness and low odor as described in any one of claims 1-8, characterized in that, Includes the following steps: 1) Mix polypropylene, VLDPE, antioxidant, nucleating agent A, nucleating agent B, acid absorbent, and lubricant thoroughly. 2) Add the mixed material from step 1) into a twin-screw extruder for compounding and granulation.

10. The method for preparing the polypropylene composition with a balanced rigidity and toughness and low odor according to claim 9, characterized in that, The stirring time is 1-3 minutes.

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