Mid-flow high-impact low odor polypropylene composition and process for the preparation thereof

Abstract

The application belongs to the technical field of high polymer materials, and particularly relates to a medium-flow high-impact low-odor polypropylene composition and a preparation method thereof. The polypropylene composition takes an impact copolymerized polypropylene as a base resin, and is prepared by adding an elastomer POE, a rigidifying nucleating agent and other additives, mixing uniformly through a low-speed stirring machine, and then being granulated through double-screw multiple extrusion. After multiple extrusion granulation, the prepared polypropylene composition has a significantly reduced organic volatile release amount and odor grade compared with a conventional material, and solves the problem that, in the prior art, long-chain branches are broken due to multiple high-temperature melting, and the VOC release amount is increased. The composition improves the crystallization performance of the polypropylene, increases the structure regularity of the polypropylene, hinders the movement of small volatile molecules, and makes it difficult for the small volatile molecules to escape from the matrix, thereby improving the odor performance of the polypropylene composition.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a medium-flow, high-impact, low-odor polypropylene composition and its preparation method. Background Technology

[0002] Impact copolymer polypropylene (ICP) is a high-performance thermoplastic synthetic resin with advantages such as low density, non-toxicity, easy processing, good chemical stability, and good electrical insulation. It boasts the best heat resistance among general-purpose resins and has wide applications in the automotive industry, home appliances, electronics, packaging, and building materials and furniture. ICP is a polymer alloy system with propylene homopolymer as the matrix and dispersed phases composed of ethylene-propylene random copolymers and ethylene-propylene multiblock copolymers. This system exhibits not only differences in molecular chain composition and chain structure but also the resulting differences in macroscopic phase structure.

[0003] ICPs are mainly divided into three types: low flow, medium flow, and high flow. Medium flow ICPs are mainly used in automobiles, small appliance housings, turnover boxes, cooling boxes, and other fields, with an annual market share of 18×10 in South China. 4 The demand for t. Internationally and domestically, various ICP grades have been developed, but differences exist in structure and performance between these grades, leading to variations in product quality.

[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 sulfides in propylene gas, polymerization solvents, and oligomers generated during polymerization may all remain in polypropylene, and these substances cannot be effectively removed by flash evaporation or drying. Antioxidants and stabilizers added during polypropylene processing may remain or degrade during processing or storage, easily generating volatile substances such as hydrocarbons, aldehydes, and ketones. Furthermore, the polypropylene backbone degrades under the influence of light, heat, oxygen, and mechanical forces, producing alkanes, aldehydes, and ketones through free radical reactions, leading to an increase in VOC content in polypropylene. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a medium-flow, high-impact, low-odor polypropylene composition. By selecting specific raw materials and making reasonable combinations, the toughness of the product is improved, VOC emissions and odor levels are reduced, and the resulting composition has good flowability and impact resistance.

[0006] Another objective of this invention is to provide a method for preparing a medium-flow, high-impact, low-odor polypropylene composition, which is simple, scientific, and reasonable.

[0007] The technical solution adopted in this invention is as follows:

[0008] The medium-flow, high-impact, low-odor polypropylene composition comprises the following raw materials in parts by weight:

[0009]

[0010]

[0011] The impact-resistant copolymer polypropylene has a melt flow rate of 15-18 g / 10 min, a melting temperature of 163℃-166℃, and an ethylene content of 10-12 wt.%.

[0012] The elastomer is one of ethylene propylene diene monomer (EPDM), ethylene propylene diene monomer (EPDM), styrene-butadiene-styrene block copolymer, or ethylene-octene copolymer, wherein the density of the ethylene-octene copolymer is 0.834-0.925 g / cm³. 3 The tensile strength is 8.5-12.5 MPa, and the melt flow rate is 7-12 g / 10 min. Ethylene-octene copolymer is preferred, as it possesses both excellent toughness and good processability.

[0013] The nucleating agent is one of the following: sorbitol derivatives, organophosphates, rosin salts, or organic carboxylates. Preferably, it is an organophosphate nucleating agent, prepared as follows: 3.56 g of sodium 2,2'-methylenebis(4,6-di-tert-butylphenol) phosphate is placed in 200 ml of ammonia water and stirred at 80°C until dissolved. After the reaction is stopped, the solution is rapidly cooled, filtered, and recrystallized again using 100 ml of ethanol-water solution to obtain a non-metallic organophosphate, i.e., the nucleating agent. The melting temperature of the nucleating agent is 262°C, and the crystalline morphology is a smooth, plate-like structure.

[0014] The antioxidant is a compound antioxidant consisting of a main antioxidant and a secondary antioxidant, with a mass ratio of 1:(2-2.5).

[0015] The primary antioxidant is one of antioxidant 1010, antioxidant 3114 or antioxidant 1330, preferably antioxidant 1010; the secondary antioxidant is one of antioxidant 168, light stabilizer 770 or antioxidant PEP36, preferably antioxidant 168.

[0016] The acid absorbent is one of calcium stearate, zinc stearate, or sodium stearate, preferably calcium stearate.

[0017] The lubricant is one of glycerol stearate, erucamide, or ethylene bis-stearamide. This component has a lubricating effect and can reduce surface scratches during the friction between the injection molded product and the mold / dip.

[0018] The preparation method of the medium-flow, high-impact, low-odor polypropylene composition comprises the following steps:

[0019] (1) Mix the impact copolymer polypropylene, elastomer, nucleating agent, antioxidant, acid absorber and lubricant, and stir for 1 to 3 minutes to obtain a mixture;

[0020] (2) The mixture obtained in step (1) is added to a twin-screw extruder for melt mixing and extrusion granulation to obtain a medium-flow, high-impact, low-odor polypropylene composition.

[0021] The extrusion granulation temperature in step (2) is 180-210℃.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] (1) The medium-flow, high-impact, low-odor polypropylene composition of the present invention, by blending random copolymer polypropylene, POE, nucleating agent, antioxidant, acid absorber and lubricant, the components have a synergistic effect, which significantly improves the toughness of the composition, while the rigidity does not decrease significantly. In practical applications, it can improve the durability and service life of the product.

[0024] (2) The medium-flow, high-impact, low-odor polypropylene composition of the present invention, after multiple extrusion granulation, has significantly reduced volatile organic compound (VOC) release and odor level compared with conventional materials (generally, due to multiple high-temperature melting, long branches break, increasing VOC release). Because the composition improves the crystallization performance of polypropylene, it increases the regularity of its structure, hinders the movement of volatile small molecules, and makes it difficult for them to escape from the matrix, thereby improving the odor performance of polypropylene, enhancing the environmental performance and comfort of the product, and reducing environmental pollution during production and use. Detailed Implementation

[0025] The present invention will be further described below with reference to the embodiments, but these embodiments do not limit the implementation of the present invention.

[0026] Unless otherwise specified, the raw materials used in the examples and comparative examples are all commercially available products.

[0027] The following describes some of the raw materials used in the examples and comparative examples:

[0028] Impact-resistant copolymer polypropylene: melt flow rate of 17 g / 10 min, melting temperature of 163 °C, and ethylene content of 11.2%;

[0029] Ethylene-octene copolymer (POE): density 0.868 g / cm³ 3 The tensile strength is 9.5 MPa, and the melt mass flow rate is 8 g / 10 min;

[0030] The preparation method of the stiffening nucleating agent is as follows: 3.56 g of sodium 2,2'-methylene bis(4,6-di-tert-butylphenol) phosphate is placed in 200 ml of ammonia water and stirred at 80°C to dissolve it. After the reaction is stopped, the solution is rapidly cooled, filtered, and then recrystallized again using 100 ml of ethanol aqueous solution to obtain a non-metallic organophosphate, namely the stiffening nucleating agent.

[0031] Antioxidant: It is obtained by compounding antioxidant 1010 and antioxidant 168 in a mass ratio of 1:2.

[0032] Example 1

[0033] The medium-flow, high-impact, low-odor polypropylene composition comprises the following raw materials in parts by weight:

[0034]

[0035] The preparation method of the medium-flow, high-impact, low-odor polypropylene composition comprises the following steps:

[0036] (1) Mix impact copolymer polypropylene, POE, stiffening nucleating agent, antioxidant, calcium stearate and glycerol stearate, stir for 3 minutes to obtain a mixture;

[0037] (2) The mixture obtained in step (1) is added to a twin-screw extruder for melt mixing and extrusion granulation to obtain a medium-flow, high-impact, low-odor polypropylene composition. The temperatures of each zone of the extruder are 180℃, 180℃, 190℃, 200℃, 210℃, and 200℃, respectively.

[0038] Example 2

[0039] The medium-flow, high-impact, low-odor polypropylene composition comprises the following raw materials in parts by weight:

[0040]

[0041] The preparation method of the medium-flow, high-impact, low-odor polypropylene composition is the same as that in Example 1.

[0042] Example 3

[0043] The medium-flow, high-impact, low-odor polypropylene composition comprises the following raw materials in parts by weight:

[0044]

[0045] The preparation method of the medium-flow, high-impact, low-odor polypropylene composition is the same as that in Example 1.

[0046] Example 4

[0047] The medium-flow, high-impact, low-odor polypropylene composition comprises the following raw materials in parts by weight:

[0048]

[0049] The preparation method of the medium-flow, high-impact, low-odor polypropylene composition is the same as that in Example 1.

[0050] Comparative Example 1

[0051] The polypropylene composition comprises the following raw materials in parts by weight:

[0052]

[0053]

[0054] The preparation method of the polypropylene composition is the same as that in Example 1.

[0055] Comparative Example 2

[0056] The polypropylene composition comprises the following raw materials in parts by weight:

[0057]

[0058] The preparation method of the polypropylene composition is the same as that in Example 1.

[0059] Comparative Example 3

[0060] The polypropylene composition comprises the following raw materials in parts by weight:

[0061]

[0062] The preparation method of the polypropylene composition is the same as that in Example 1.

[0063] Comparative Example 4

[0064] The polypropylene composition comprises the following raw materials in parts by weight:

[0065]

[0066]

[0067] Comparative Example 5

[0068] The polypropylene composition comprises the following raw materials in parts by weight:

[0069]

[0070] The preparation method of the polypropylene composition is the same as that in Example 1.

[0071] Detection method:

[0072] (1) Melt mass flow rate (MFR): Tested in accordance with GB / T 3682-2000;

[0073] (2) Tensile yield stress: tested according to GB / T 1040.2-2006;

[0074] (3) Flexural modulus of elasticity: tested according to GB / T 9341-2008;

[0075] (4) Notched impact strength of simply supported beams: tested according to GB / T 1043.1-2008;

[0076] (5) Odor rating: Tested according to SMC 30156-2007;

[0077] (6) Volatile organic compound content: tested according to GB / T 27630-2011;

[0078] The test results of the examples and comparative examples are shown in Tables 1 to 4.

[0079] Table 1 Performance of Examples 1-4

[0080]

[0081] Table 2. Gas chromatography-mass spectrometry (GC-MS) test results for volatile organic compound (VOC) content in Examples 1-4 (80°C)

[0082]

[0083]

[0084] Table 3 Performance of Comparative Examples 1-4

[0085]

[0086] Table 4. Gas chromatography-mass spectrometry (GC-MS) analysis of volatile organic compound (VOC) content in Comparative Examples 1–4 (80℃)

[0087]

[0088] In the examples, through screening of the composition formulation, the toughness of the obtained medium-flow, high-impact, low-odor polypropylene composition was significantly improved without a decrease in rigidity, while the odor level and volatile organic compounds decreased after multiple extrusion granulation. In the comparative examples, when the formulation components or proportions were changed, the basic physical properties (toughness and rigidity) of the resulting compositions decreased significantly, while the odor level and volatile organic compounds increased significantly.

Claims

1. A medium-flow, high-impact, low-odor polypropylene composition, characterized in that, It consists of the following raw materials in parts by weight: 92-99 parts of impact-resistant copolymer polypropylene; 1 to 8 parts of elastomer; Nucleating agent 0.08–0.2 parts; Antioxidant 0.1-0.2 parts; Acid absorbent: 0.08–0.15 parts; Lubricant 0.05-0.1 parts; The elastomer is an ethylene-octene copolymer with a density of 0.834–0.925 g / cm³. 3 The tensile strength is 8.5–12.5 MPa, and the melt mass flow rate is 7–12 g / 10 min; The nucleating agent is prepared as follows: 3.56 g of sodium 2,2'-methylenebis(4,6-di-tert-butylphenol) phosphate is placed in 200 mL of ammonia water and stirred at 80 °C to dissolve it. After the reaction is stopped, the solution is rapidly cooled, filtered, and recrystallized again using 100 mL of ethanol aqueous solution to obtain a non-metallic organophosphate, namely the stiffening nucleating agent. The melting temperature of the stiffening nucleating agent is 262 °C, and the crystal morphology is a smooth lamellar structure.

2. The medium-flow, high-impact, low-odor polypropylene composition according to claim 1, characterized in that, The impact-resistant copolymer polypropylene has a melt flow rate of 15-18 g / 10 min, a melting temperature of 163℃-166℃, and an ethylene content of 10-12 wt.%.

3. The medium-flow, high-impact, low-odor polypropylene composition according to claim 1, characterized in that, The antioxidant is a compound antioxidant consisting of a primary antioxidant and a secondary antioxidant, with a mass ratio of 1:(2-2.5).

4. The medium-flow, high-impact, low-odor polypropylene composition according to claim 3, characterized in that, The primary antioxidant is one of antioxidant 1010, antioxidant 3114, or antioxidant 1330; the secondary antioxidant is one of antioxidant 168, light stabilizer 770, or antioxidant PEP36.

5. The medium-flow, high-impact, low-odor polypropylene composition according to claim 1, characterized in that, The acid absorbent is one of calcium stearate, zinc stearate, or sodium stearate.

6. The medium-flow, high-impact, low-odor polypropylene composition according to claim 1, characterized in that, The lubricant is one of glycerol stearate, erucamide, or ethylene bis-stearamide.

7. A method for preparing the medium-flow, high-impact, low-odor polypropylene composition according to any one of claims 1 to 6, characterized in that, The steps are as follows: (1) Mix the impact copolymer polypropylene, elastomer, nucleating agent, antioxidant, acid absorber and lubricant, and stir to obtain a mixture; (2) The mixture obtained in step (1) is added to a twin-screw extruder for melt mixing and extrusion granulation to obtain a medium-flow, high-impact, low-odor polypropylene composition.

8. The method for preparing the medium-flow, high-impact, low-odor polypropylene composition according to claim 7, characterized in that, In step (2), the extrusion granulation temperature is 180-210℃.

Images