KR100842161B1 - Excellent izod impact strength polypropylene composition having superior flowability and glossless property - Google Patents

Abstract

A polypropylene resin composition is provided to realize excellent impact strength, aesthetic effect, processability, flow property and matte characteristics suitable for car exterior and interior parts. A polypropylene resin composition comprises: 85-95 wt% of a propylene-ethylene block copolymer formed of 75-85 wt% of polypropylene and 15-25 wt% of ethylene-propylene rubber; and 5-15 wt% of a high-density polyethylene. The propylene-ethylene block copolymer has a polydispersity of at least 10, and a melt index of 6-40 g/10 minutes. The high-density polyethylene has a density of 0.94-0.96 g/cm^3.

Description

High impact polypropylene resin composition excellent in flowability and matte properties {EXCELLENT IZOD IMPACT STRENGTH POLYPROPYLENE COMPOSITION HAVING SUPERIOR FLOWABILITY AND GLOSSLESS PROPERTY}

The present invention relates to a high-impact polypropylene resin composition having excellent flowability and having a matte property, and more particularly, to room temperature Izod by blending high density polyethylene in a propylene-ethylene block copolymer having a wide molecular weight distribution and a high content of rubber. In terms of impact strength, the present invention relates to a high-impact polypropylene resin composition which exhibits non-break (NB) characteristics, improves low-temperature impact strength, and is excellent in flowability and matt properties.

In general, polypropylene resin has excellent rigidity, chemical resistance and the like compared to other polyolefin-based materials, and has a low specific gravity and low cost, and thus is widely used for exterior materials such as automobile bumpers and interior materials such as various fillers. However, when used as a material for automotive interior materials, it is required to develop a material that can satisfy both safety and aesthetic effects at the same time, and can also satisfy the ease of injection of large objects at the same time. There is a situation.

There are several ways to improve the impact properties of polypropylene resins, one of which is rubber such as ethylene-butene copolymer (EBM), ethylene-octene copolymer (EOM) or ethylene propylene diene copolymer (EPDM) BACKGROUND OF THE INVENTION A method of melt-mixing a component material into polypropylene has been widely used. However, in this case, the distribution of EBM, EOM or EPDM can be a problem, and the price rises.

As another method, a method of improving the impact strength while reducing the amount of expensive rubbers by adding high crystalline polypropylene, polyethylene, and an inorganic filler to the crystalline polypropylene resin of a partial crosslinking system has been proposed. In relation to these methods, Korean Patent Application No. 2000-64690 proposed a polypropylene resin composition having excellent impact strength and scratch resistance, but in this case, when crosslinking is excessive, a high molecular weight elastomer is generated to generate a flow mark. This has the disadvantage of deteriorating the appearance quality.

In order to solve the problems as described above, the present invention has excellent flowability by blending high density polyethylene with a propylene-ethylene block copolymer obtained by adjusting the molecular weight distribution of the polymer and the content of copolymerized ethylene-propylene rubber (EPR), An object of the present invention is to provide a high impact polypropylene resin composition having excellent matt characteristics.

The polypropylene resin composition according to the present invention includes 5 to 15% by weight of high density polyethylene in 85 to 95% by weight of a propylene-ethylene block copolymer composed of 75 to 85% by weight of polypropylene and 15 to 25% by weight of ethylene-propylene rubber. Characterized in that made.

In the present invention, the propylene-ethylene block copolymer is also referred to as an impact copolymer or a heteropolymer, and is a two-phase structure in which ethylene-propylene rubber is dispersed in a propylene homopolymer matrix. It has a phase structure.

Two or more reactors are required for the preparation of the above propylene-ethylene block copolymer, a propylene homopolymer is prepared in the front reactor, and ethylene-propylene rubber is prepared in the rear reactor and blended in the reactor to have a two-phase structure.

The content of ethylene-propylene rubber in the propylene-ethylene block copolymer used in the present invention is preferably 15 to 25% by weight. If the content is less than 15% by weight, the low temperature impact property is deteriorated. Since heat resistance, surface hardness, and remarkably fall, it is unpreferable.

The propylene-ethylene block copolymer used in the present invention preferably has a molecular weight distribution of 10 or more and a melt index of 6 to 40 g / 10 minutes. If the molecular weight distribution is less than 10, the flowability is deteriorated and the product has a complicated shape such as a grill. It is not preferable because molding may cause defects of unmolding. In addition, if the melt index of the propylene-ethylene block copolymer is less than 6g / 10 minutes, the workability is not good, productivity is lowered, and if it exceeds 40g / 10 minutes, the dispersion of rubber worsens and the impact strength is lowered, which is not preferable.

In order for the high density polyethylene used in the present invention to exhibit excellent physical properties, it is preferable that the density of polyethylene is 0.94-0.96 g / cm ³ and the usage amount is 5 to 15% by weight. It is not preferable because there is no improvement, and if it exceeds 15% by weight, further improvement effect is insignificant in the impact characteristic, and the phenomenon that the stiffness is lowered is not preferable.

The polypropylene resin composition of the present invention may further include an organometallic nucleus agent and an inorganic nucleus agent.

The organometallic nucleating agent is not particularly limited in its kind, but may be used aluminum parabutyl benzoic acid, sodium benzoic acid, calcium benzoic acid and the like.

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The inorganic nucleating agent that can be used in the present invention is not particularly limited in its kind, but a talc having an average particle diameter of 2.0 µm and a maximum particle diameter of 6 µm or less may be preferably used. In the case of talc, when the maximum particle diameter is 6 µm or more, the effect efficiency due to the use of the nucleating agent is lowered, which is not preferable.

The resin composition of the present invention may further include reinforcing materials, fillers, heat stabilizers, weather stabilizers, antistatic agents, lubricants, slip agents, nucleating agents, flame retardants, pigments, dyes, and the like, which are added to general resin compositions.

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There is no restriction | limiting in particular in the method of manufacturing the high impact polypropylene resin composition of this invention, The manufacturing method of the polypropylene resin composition generally known can be used. Propylene-ethylene block copolymer, high-density polyethylene, and if necessary, the nucleating agent and each additive component can be freely selected according to the desired order, kneaders such as kneader, roll, and short-barrier mixer, tandem extruder, and single-axis. Or the kneading | mixing using a twin screw extruder etc. can manufacture the resin composition of this invention.

Hereinafter, the present invention will be described in more detail with reference to the following Examples and Comparative Examples. The following examples are merely examples for illustrating the present invention, and do not limit the protection scope of the present invention.

Example  And Comparative example

The measuring method of the physical property in each Example and a comparative example is as follows.

Melt Flow Index Measurement: measured at 230 ° C. and 2.16 kg according to ASTM D1238.

Mw / Mn ratio (molecular weight distribution): The ratio of the weight average molecular weight (Mn) and the number average molecular weight (Mn) measured by the gel permeation chromatography (GPC) method was measured.

Izod impact strength: measured according to ASTM D256 method.

Flexural modulus: measured according to ASTM D790 method.

Glossiness: measured according to ASTM D2457 method.

Spiral flow: measured at 200 ° C. according to STC Method.

Using the propylene-ethylene block copolymer shown in Table 1 below, each component was kneaded using a twin screw extruder according to the composition shown in Table 2 to prepare a polypropylene resin composition. Each prepared resin composition was made into ASTM Family 4 specimens using an injection molding machine. The injection machine used was Samsung Klockner FM110TON, and the injection conditions were set at 30 ℃, 190 ℃, 210 ℃, 210 ℃, 210 ℃ (nozzle temperature), 60 ℃ (molding temperature) from the hopper. , Injection pressure was carried out in the range of 50 ~ 120bar. The injected specimen was measured for 72 hours in a room temperature room temperature (23 ° C.), and the results are shown in Table 2 together.

Table 1

Resin properties Propylene-ethylene block copolymer 1 Propylene-Ethylene Block Copolymer 2 Propylene-Ethylene Block Copolymer 3 Melt Index (g / 10min) 10 10 10 Mw / Mn 11 10 6 Ethylene-propylene rubber (% by weight) 20 13 21

TABLE 2

Example Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4      Polypropylene Resin Composition Propylene-ethylene block copolymer 1 90 97 100 Propylene-Ethylene Block Copolymer 2 90 Propylene-Ethylene Block Copolymer 3 90 High density polyethylene 10 3 10 10      Properties Flexural modulus (kgf / cm ² ) 10000 10500 11000 11500 9800 23 ℃ Izod Impact Strength (kgf.cm/cm) 66 63 62 12.1 62 -20 ℃ Izod Impact Strength (kgf.cm/cm) 10.6 8.7 8.5 4.7 9.3 Spiral Flow (cm) 138 138 137 135 116 Glossiness 27 40 43 31 29

As can be seen from the results of Table 2, when compared with Comparative Examples 1 and 2, the gloss was significantly lowered, and the low temperature impact strength was also increased. In addition, compared with Comparative Example 3, the Example shows that the room temperature impact strength and the low temperature impact strength are significantly increased, and it can be seen that the flowability is very excellent as compared with Comparative Example 4.

As described above, the high impact polypropylene resin composition according to the present invention has a high molecular weight distribution and excellent impact strength by blending high density polyethylene in a propylene-ethylene block copolymer having an ethylene-propylene rubber content of 15 to 25% by weight. Because of its flowability and matte properties, it is possible to obtain impact strength, aesthetic effect and easy processability suitable for use in automobile exterior materials and interior components.

Claims (4)

Polypropylene resin composition comprising 85 to 95% by weight of propylene-ethylene block copolymer consisting of 75 to 85% by weight of polypropylene, 15 to 25% by weight of ethylene-propylene rubber and 5 to 15% by weight of high density polyethylene. . The polypropylene resin composition of claim 1, wherein the propylene-ethylene block copolymer has a molecular weight distribution of 10 or more and a melt index of 6 to 40 g / 10 minutes. The polypropylene resin composition according to claim 1, wherein the high density polyethylene has a density of 0.94-0.96 g / cm ³ . delete