Medium-flow high-impact low-odor polypropylene composition and preparation method thereof

Abstract

The invention 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 is prepared by taking impact-resistant co-polypropylene as base resin, adding an elastomer POE, a stiffening nucleating agent and other auxiliaries, uniformly mixing through a low-speed stirrer, and extruding and granulating for multiple times through double screws. After the prepared polypropylene composition is extruded and granulated for multiple times, the release amount of volatile organic compounds and the odor level are obviously reduced compared with those of conventional materials, the problems that in the prior art, due to multiple times of high-temperature melting, long-chain branched chains are broken, and the release amount of VOC is increased are solved, the composition improves the crystallization property of polypropylene, the structural regularity of the polypropylene is increased, and the mechanical property of the polypropylene is improved. The movement of the volatile small molecules is blocked, and the difficulty of escaping from the matrix is high, so that the odor performance of the polypropylene composition is improved.

Description

Technical Field

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

[0002] Impact copolymer polypropylene (ICP) is a thermoplastic synthetic resin with excellent performance. It has the advantages of low density, non-toxicity, easy processing, chemical stability and good electrical insulation. It is the product with the best heat resistance among general resins and is widely used in the automotive industry, household appliances, electronics, packaging, building materials and furniture. ICP is a polymer alloy system with propylene homopolymer as the matrix and ethylene-propylene random copolymer and ethylene-propylene multi-block copolymer as the dispersed phase. There are not only differences in molecular chain composition and chain structure in the system, but also differences in macroscopic phase structure caused by this.

[0003] ICP is mainly divided into three types: low flow, medium flow and high flow. Medium flow ICP is mainly used in automobiles, small appliance housings, turnover boxes, cooling boxes and other fields. It has an annual market share of 18×10 4 t demand. Foreign and domestic ICP brands with medium flow have been developed one after another, but there are still differences in structure and performance between different brands, which also leads to different product quality.

[0004] The sources of VOC in polypropylene are relatively complex, and they are produced during its polymerization, processing, transportation, storage, etc. In the process of propylene polymerization, catalysts, comonomers, trace propane and sulfides contained in propylene gas, polymerization solvents, oligomers produced during the polymerization process, etc. may remain in polypropylene, and these substances cannot be effectively removed by flash evaporation, drying and other processes; antioxidants, stabilizers and other additives added during the processing of polypropylene will remain or degrade during processing or storage and transportation, and volatile substances such as hydrocarbons, aldehydes, and ketones are easily produced; in addition, the main chain of polypropylene will degrade under the action of light, heat, oxygen, and mechanical factors, thereby producing alkanes, aldehydes, ketones and other substances through free radical reactions, resulting in an increase in the VOC content in polypropylene. Summary of the invention

[0005] In view of the shortcomings of the prior art, the object of the present invention is to provide a medium-flow, high-impact, low-odor polypropylene composition, which improves the toughness of the product, reduces the VOC emission and odor level, and the prepared composition has good fluidity and impact resistance by selecting specific raw materials and reasonable matching;

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

[0007] The technical solution adopted by the present invention is as follows:

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

[0009]

[0010]

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

[0012] The elastomer is one of EPDM, EPDM, styrene-butadiene-styrene block copolymer or ethylene-octene copolymer, and the density of the ethylene-octene copolymer is 0.834-0.925 g / cm 3 , tensile strength of 8.5-12.5 MPa, melt mass flow rate of 7-12 g / 10 min. Preferred is ethylene-octene copolymer, which has both excellent toughness and good processability.

[0013] The nucleating agent is one of sorbitol derivatives, organic phosphates, rosin acid salts or organic carboxylate nucleating agents. Preferably, it is an organic phosphate nucleating agent, and its preparation method is as follows: 2,2'-methylene bis (4,6-di-tert-butylphenol) sodium phosphate (3.56g) is placed in 200ml ammonia water, and it is placed in an environment of 80°C for stirring to dissolve, and after stopping the reaction, the solution is quickly cooled and filtered, and then recrystallized again using 100ml ethanol aqueous solution to obtain a non-metallic organic phosphate, i.e., a nucleating agent. The melting temperature of the nucleating agent is 262°C, and the crystal morphology is a lamellar structure with a smooth surface.

[0014] The antioxidant is a compound antioxidant of a main antioxidant and an auxiliary antioxidant, and the mass ratio thereof is 1:(2-2.5).

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

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

[0017] The lubricant is one of glycerol stearate, erucic acid amide or ethylene bis stearamide. The component has a lubricating effect and can reduce surface scratches during the friction between the injection molded product and the mold and the die mouth.

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

[0019] (1) mixing impact copolymer polypropylene, elastomer, nucleating agent, antioxidant, acid absorbent and lubricant, and stirring for 1 to 3 minutes to obtain a mixed material;

[0020] (2) adding the mixture obtained in step (1) into a twin-screw extruder for melt mixing, and extruding and granulating to obtain a medium-flow, high-impact, low-odor polypropylene composition.

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

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The medium-flow, high-impact, low-odor polypropylene composition of the present invention is prepared by blending random copolymer polypropylene, POE, a nucleating agent, an antioxidant, an acid absorber, and a lubricant. The components act synergistically, so that the toughness of the composition is significantly improved, while the rigidity is not significantly reduced. In practical applications, the durability and service life of the product can be improved.

[0024] (2) The medium-flow, high-impact, low-odor polypropylene composition of the present invention, after multiple extrusion granulation, has significantly lower volatile organic compound (VOC) release and odor level than conventional materials (generally, due to multiple high-temperature melting, long chain branches are disconnected and VOC release increases). This is because the composition improves the crystallization properties of polypropylene, increases its structural regularity, 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, improving the environmental performance and comfort of the product, and reducing environmental pollution during production and use. DETAILED DESCRIPTION

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

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

[0027] Some of the raw materials used in the embodiments and comparative examples are described as follows:

[0028] Impact copolymer polypropylene: melt mass flow rate is 17g / 10min, melting temperature is 163℃, ethylene content is 11.2%;

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

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

[0031] Antioxidant: prepared 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 is composed of the following raw materials in parts by weight:

[0034]

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

[0036] (1) mixing impact copolymer polypropylene, POE, stiffening nucleating agent, antioxidant, calcium stearate and glycerol stearate, and stirring for 3 minutes to obtain a mixed material;

[0037] (2) adding the mixture obtained in step (1) into a twin-screw extruder for melt mixing and extrusion granulation to obtain a medium-flow, high-impact, low-odor polypropylene composition, wherein the temperatures of the extruder zones are 180° C., 180° C., 190° C., 200° C., 210° C., and 200° C., respectively.

[0038] Example 2

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

[0040]

[0041] The preparation method of the medium-flow, high-impact and low-odor polypropylene composition has the same steps as Example 1.

[0042] Example 3

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

[0044]

[0045] The preparation method of the medium-flow, high-impact and low-odor polypropylene composition has the same steps as Example 1.

[0046] Example 4

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

[0048]

[0049] The preparation method of the medium-flow, high-impact and low-odor polypropylene composition has the same steps as Example 1.

[0050] Comparative Example 1

[0051] The polypropylene composition is composed of the following raw materials in parts by weight:

[0052]

[0053]

[0054] The preparation method of the polypropylene composition has the same steps as Example 1.

[0055] Comparative Example 2

[0056] The polypropylene composition is composed of the following raw materials in parts by weight:

[0057]

[0058] The preparation method of the polypropylene composition has the same steps as Example 1.

[0059] Comparative Example 3

[0060] The polypropylene composition is composed of the following raw materials in parts by weight:

[0061]

[0062] The preparation method of the polypropylene composition has the same steps as Example 1.

[0063] Comparative Example 4

[0064] The polypropylene composition is composed of the following raw materials in parts by weight:

[0065]

[0066]

[0067] Comparative Example 5

[0068] The polypropylene composition is composed of the following raw materials in parts by weight:

[0069]

[0070] The preparation method of the polypropylene composition has the same steps as Example 1.

[0071] Detection method:

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

[0073] (2) Tensile yield stress: tested in accordance with GB / T 1040.2-2006;

[0074] (3) Flexural modulus: tested in accordance with GB / T 9341-2008;

[0075] (4) Simply supported beam notched impact strength: tested in accordance with GB / T 1043.1-2008;

[0076] (5) Odor level: tested in accordance with SMC 30156-2007;

[0077] (6) Volatile organic matter content: tested in accordance with GB / T 27630-2011;

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

[0079] Table 1 Performance of Examples 1 to 4

[0080]

[0081] Table 2 GC-MS test of organic volatile content in Examples 1 to 4 (80°C)

[0082]

[0083]

[0084] Table 3 Comparative Examples 1 to 4 Performance

[0085]

[0086] Table 4 GC-MS test of organic volatile content of comparative examples 1 to 4 (80°C)

[0087]

[0088] In the examples, by screening the composition formula, the toughness of the obtained medium flow high impact low odor polypropylene composition is significantly improved without decreasing the rigidity, and the odor level and organic volatiles are reduced after multiple extrusion granulation. In the comparative examples, when the formula components or proportions are changed, the basic physical properties (toughness and rigidity) of the obtained composition are significantly reduced, and the odor level and organic volatiles are significantly improved.

Claims

1. A medium flow, high impact and low odor polypropylene composition, characterized in that: It is composed of the following raw materials in parts by weight:

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

3. The medium flow, high impact and low odor polypropylene composition according to claim 1, characterized in that: The elastomer is one of EPDM, EPDM, styrene-butadiene-styrene block copolymer or ethylene-octene copolymer, and the density of the ethylene-octene copolymer is 0.834-0.925 g / cm 3 , tensile strength is 8.5-12.5Mpa, and melt mass flow rate is 7-12g / 10min.

4. The medium flow, high impact and low odor polypropylene composition according to claim 1, characterized in that: The nucleating agent is one of sorbitol derivatives, organic phosphates, rosin acid salts or organic carboxylate nucleating agents.

5. The medium flow, high impact and low odor polypropylene composition according to claim 1, characterized in that: The antioxidant is a compound antioxidant of a main antioxidant and an auxiliary antioxidant, and the mass ratio thereof is 1:(2-2.5).

6. The medium flow, high impact and low odor polypropylene composition according to claim 1, characterized in that: The main antioxidant is one of antioxidant 1010, antioxidant 3114 or antioxidant 1330; the auxiliary antioxidant is one of antioxidant 168, light stabilizer 770 or antioxidant PEP36.

7. The medium flow, high impact and low odor polypropylene composition according to claim 1, characterized in that: The acid absorber is one of calcium stearate, zinc stearate or sodium stearate.

8. The medium flow, high impact and low odor polypropylene composition according to claim 1, characterized in that: The lubricant is one of glycerol stearate, erucic acid amide or ethylene bis stearamide.

9. A method for preparing the medium flow, high impact resistance and low odor polypropylene composition according to any one of claims 1 to 8, characterized in that: Here are the steps: (1) mixing impact copolymer polypropylene, an elastomer, a nucleating agent, an antioxidant, an acid absorbent and a lubricant, and stirring to obtain a mixed material; (2) adding the mixture obtained in step (1) into a twin-screw extruder for melt mixing, and extruding and granulating to obtain a medium-flow, high-impact, low-odor polypropylene composition.

10. The method for preparing the medium flow, high impact resistance and low odor polypropylene composition according to claim 9, characterized in that: The extrusion granulation temperature in the step (2) is 180-210°C.

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