KR20100133765A - A polypropylene resin composition for automotive interior part - Google Patents

Abstract

PURPOSE: A polypropylene resin composition is provided to ensure excellent scratch resistance while maintaining impact resistance of a conventional material. CONSTITUTION: A polypropylene resin composition for an automotive interior material door trim comprises: 70~85 weight% highly crystalline ethylene-propylene copolymers with 8~12 mole% of xylene content and 20~40 g/10 min(230 °C, 2.16 Kg) of melt index; 8~18 weight% of a rubber mixture consisting of an ethylene-octene elastomer with 0.86~0.91 g/cm^3 of specific gravity and an ethylene-butene rubber elastomer in a weight ratio of 1 : 1 ~ 2 : 1; 5~15 weight% of inorganic filler; 60~70 weight% of silicon component; 0.5~3 weight% of slip agent containing 30 ~ 40 weight% of silica ash; and 0.5~4 weight% of graft-modified polypropylene.

Description

Polypropylene Resin Composition for Automotive Interior Part

The present invention relates to a polypropylene resin composition usable for automotive interiors.

In general, the material applied to the automotive door trim is a polypropylene composition that requires high impact resistance, but the impact resistance is very good, but it is very vulnerable to scratches in the molded state. Appearance damage must be a negative effect from the user's point of view because the performance that the user can feel directly is focused on the appearance evaluation. In addition, the development of a door-trim material having excellent scratch resistance by applying various embossings to improve customer satisfaction with the appearance of unpainted parts is a very important task.

Accordingly, an object of the present invention is to provide a composition having excellent scratch resistance at a specific gravity of 1 or less while improving the scratch resistance, which is a lack of the existing door trim material, and at the same time, a characteristic of the existing material.

The present invention is 8 to 12 mol% xylene content, 70 to 85% by weight of the highly crystalline ethylene-propylene copolymer having a melt index of 20 to 40 g / 10 min (230 ℃, 2.16 Kg); 8 to 18% by weight of a rubber mixture composed of an ethylene-octene rubber elastomer having an specific gravity of 0.86 to 0.91 g / cm 3 and an ethylene-butene rubber elastomer having a weight ratio of 1: 1 to 2: 1; Inorganic fillers 5-15 wt%; 0.5 to 3% by weight of a slip agent containing ash and a burned silicon and silica; and 0.5 to 4% by weight of modified polypropylene with a polar group of 1 to 2 mol%; polypropylene resin composition for automotive interior door trim It is characterized by.

As described above, the polypropylene resin composition for automobile interior materials produced by the present invention is equivalent to the conventional material properties (particularly impact strength), and has excellent scratch resistance than the existing polypropylene resin composition, and thus is a door trim material. Suitable for use as In addition, it can be applied to interior parts in addition to door trim as an effective material that can contribute to the user's quality satisfaction by overcoming the limit of scratchability of the existing material.

The present invention is 8 to 12 mol% xylene content, 70 to 85% by weight of a highly crystalline ethylene-propylene copolymer having a melt index of 20 to 40 g / 10 min (230 ℃, 2.16 Kg); 8 to 18% by weight of a rubber mixture composed of an ethylene-octene rubber elastomer having an specific gravity of 0.86 to 0.91 g / cm 3 and an ethylene-butene rubber elastomer having a weight ratio of 1: 1 to 2: 1; Inorganic fillers 5-15 wt%; 0.5 to 3% by weight of a slip agent containing ash burned with silicon and silica; and 0.5 to 4% by weight of modified polypropylene having a polar group of 1 to 2 mol%; It relates to a polypropylene resin composition for automobile interior door trim containing.

Hereinafter, the present invention will be described in detail.

(1) high crystalline ethylene-propylene copolymer

The composition of the highly crystalline ethylene-propylene copolymer uses a highly crystalline propylene homopolymer or an ethylene-propylene block copolymer containing ethylene as the main component of the propylene monomer. The highly crystalline ethylene-propylene copolymer has an ethylene content of 8 to 12 mol% according to xylene solubility measurement, and has a melt index of 20 to 40 g / 10 min (230 ° C., 2.16 Kg). It is preferable to use 70 to 85 weight% with respect to the propylene resin composition. When the content of the high crystalline ethylene-propylene copolymer is out of the above range, the scratch resistance is lowered, which may lower the effect pursued by the invention, so the above range is preferable. Such a highly crystalline ethylene-propylene copolymer has a 97 to 99.9% ISOTATIC INDEX measured by ¹³ C NMR.

(2) rubber mixture

Application of the rubber elastomer of the ethylene-octene component and the ethylene-butene component is a composition for improving impact resistance, and the ethylene-octene rubber elastomer is called EOR, and the ethylene-butene rubber elastomer is called EBR. The effect of the mixing of EOR and EBR is better at low temperature impact strength and less scratch resistance reduction compared to the conventional application of ethylene-octene rubber elastomer (EOR) and ethylene-propylene-diene-based elastomer (EPDM). can see. The octene content of the EOR is 16-26 mol%, the butene content of the EBR is most preferably applied to the elastomer of 25 to 35 mol%. The mixing ratio of EOR and EBR is most suitable in a weight ratio of 1: 1 to 2: 1, and the rubber mixture mixed in the above range preferably contains 8 to 18% by weight based on the total polypropylene resin composition. If the content of the elastic body is less than 8% by weight may be disadvantageous to low-temperature impact, if the content of more than 18% by weight may reduce the scratch resistance is preferred in the above range.

(3) inorganic filler

The average particle diameter of the inorganic filler used in this invention is 1-12 micrometers, Preferably it is 2-8 micrometers. If the average particle size of the inorganic filler is less than 1 μm, problems of dispersibility and productivity and molding shrinkage may occur, and if the average particle size exceeds 12 μm, the overall mechanical properties may decrease or compatibility may be reduced. Do. For such inorganic fillers, it is preferable to use 5 to 15% by weight, preferably 8 to 12% by weight, based on the total polypropylene resin composition. When the content of the inorganic filler is less than 5% by weight, the rigidity and dimensions required for the door trim The above range is preferable because the safety may be lowered, and if it exceeds 15% by weight, the surface may be excessively roughened, which may be a factor that inhibits scratch resistance. In the present invention, talc, mica, wellastonite, calcium carbonate, silica, glass fiber, and the like may be used as the inorganic filler, and among them, the use of talc is most preferred.

(4) slip agent

A slip agent is added to improve the scratch resistance by providing slip property to the surface. The slip agent used in the present invention is composed of 60 to 70% by weight of silicon and 30 to 40% by weight of ash with silica. do. Such a slip agent contains 0.5 to 3% by weight, preferably 1 to 2% by weight, based on the total polypropylene resin composition. When the slip agent is used outside of the above range, the overall physical properties may be deteriorated. The above range is preferred because it may impair compatibility between different compositions.

(5) modified polypropylene

Modified polypropylene having a polar group of 1 to 2 mol% grafted improves compatibility and binding properties between polypropylene compositions, thereby increasing mutual affinity and exhibiting beneficial effects on physical properties. More specifically, the combination of homo polypropylene, maleic anhydride, and peroxide serves to double the bondability of polypropylene with inorganic fillers and stabilizers by the action of amine-based polar groups. Such modified polypropylene is used in an amount of 0.5 to 4% by weight based on the total polypropylene resin composition, but the above range is preferable because the physical properties of the entire resin may be deteriorated if the above range is exceeded.

The mixing method of the polypropylene resin composition for automobile interior of the present invention is mixed by a method such as a super mixer, ribbon mixer, etc., and the extruders used for manufacturing are manufactured using a bumpy, single screw and twin screw extruder, and the like through water-cooled cooling Solidify and cut. The resin thus prepared is used by injection molding, extrusion molding, sheet molding, and the like, and a general molding method applied to the door trim may be injection molding.

The polypropylene resin for automobile interior of the present invention is a low specific gravity material having a specific gravity less than 1, and has excellent impact strength and scratch resistance, and maximizes slip performance and polar group graft by a silicone-based film applied to the surface. Due to the compatibility of the modified modified polypropylene, it is possible to improve the bonding property of the inorganic filler and the polypropylene, thereby showing the characteristics specific to scratches. The existing scratch material has some disadvantages in impact because it requires rigidity, but this polypropylene resin has excellent impact strength (particularly low temperature impact) and scratch resistance.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the scope of the present invention is not limited by the following examples.

[Example]

Examples 1-5: Polypropylene Resin Specimen Preparation

Highly crystalline polypropylene, EOR and EBR rubber elastomers, talc, silicone-based slip agent, modified polypropylene, and antioxidants constituting the scratch-resistant polypropylene composition were mixed in a supermixer in the following component ratios Thereafter, the biaxial extruder was extruded under a temperature of 180 to 230 ° C., Feeding RPM 90, and SCREW RPM 260 using a twin screw extruder having a diameter of 45 kV, thereby injection molding to prepare a polypropylene resin specimen.

Division (weight%) Example One 2 3 4 5 High Crystalline Polypropylene Melt Index 30 43 46 46 48 48 Melt Index60 29.5 26.5 26 24 23 Rubber mixture EOR 10 8 8 7 7 EBR 4 6 6 7 7 Inorganic filler ¹⁾ Talc 10 10 10 10 10 Slip agent ²⁾ 0.5 0.5 One One 2 Modified polypropylene 3 3 3 3 3 1) Inorganic filler: average 10 ㎛
2) Slip agent: 65% silicon, 35% silica-burned ash

Experimental Examples 1 to 5

The following physical properties of the specimens prepared in Examples 1 to 5 were evaluated, and the results are shown in Table 4 below.

end. Melt Index (MI, g / 10min): Performed according to ASTM D 1238 (230 ° C., 2.16 Kg).

I. Specific gravity (g / μl): Performed according to ASTM D 792.

All. Tensile strength and elongation at break (Kgf / cm 2): Test was carried out in accordance with ASTM D 638 (thickness of 3 mm, 23 ° C.).

la. Flexural modulus and flexural strength (Kgf / cm 2): The test was conducted in accordance with ASTM D 790 (thickness 6 mm, 23 ° C.).

hemp. Impact strength (NOTCHED IZOD, Kgfcm / cm): The test was carried out in accordance with ASTM D 256 (6 mm thick, 23 ° C.).

bar. Heat deformation temperature (° C.): It was carried out in accordance with ASTM D 648 (4.6 Kg LOAD, specimen thickness 6 mm).

four. Scratch resistance: The surface state after the experiment under the conditions of Table 2 using a sapphire scratcher was determined by Table 3 below.

Item Condition Load (kgf) 0.5 (including scratcher weight) STROKE (mm) 100 ± 5 Scratching speed (mm / sec) 100





Scratcher

Scratches 1 time

Rating Criteria Scratch width (㎛) Exterior 5 <100 Surface damage not recognized 4 100 to 250 Surface damage is weakly perceived 3 250-400 Surface damage is recognized but no whitening 2.5 400-475 Partial surface damage and whitening 2 475-550 Obvious surface damage and whitening One > 550 Very severe surface damage

Test Items Experimental Example One 2 3 4 5 Psalter Example 1 Example 2 Example 3 Example 4 Example 5 Melt index 24.2 24.5 25.1 24.4 25.8 importance 0.97 0.97 0.97 0.97 0.97 The tensile strength 252 253 244 242 235 Elongation at break 138 135 155 159 185 Flexural modulus 19,350 19,220 18,930 18,900 18,550 Flexural strength 388 387 385 385 380 IZOD impact strength (23 ℃) 17.6 17.7 18.1 18.1 18.5 IZOD impact strength (-10 ℃) 6.2 6.2 6.4 6.3 6.6 Heat deflection temperature 128 128 126 125 124 Scratch resistance Level 3 Level 3 3.5 grade 3.5 grade 4th grade

As a result of examining the performance of the present invention as a result of Table 4, when the range of the composition is within the allowable range of the present invention, the result of the level can be seen. The higher the scratch resistance grade, the better the result. Normally, level 3 or above is defined as the satisfaction level. It was found that the scratch resistance is improved depending on the selective application of high crystalline polypropylene, the composition of EOR and EBR, and the amount of slip agent applied. However, the content of the inorganic filler, namely talc, was kept the same for dimensional stability and objective comparison.

Claims (3)

70 to 85 wt% of a highly crystalline ethylene-propylene copolymer having an xylene content of 8 to 12 mol% and a melt index of 20 to 40 g / 10 min (230 ° C., 2.16 Kg); 8 to 18% by weight of a rubber mixture composed of an ethylene-octene rubber elastomer having an specific gravity of 0.86 to 0.91 g / cm 3 and an ethylene-butene rubber elastomer having a weight ratio of 1: 1 to 2: 1; Inorganic fillers 5-15 wt%; 0.5 to 3% by weight of a slip agent containing 60 to 70% by weight of the silicone component and 30 to 40% by weight of silica-burned ash; and 0.5 to 4% by weight of modified polypropylene having a polar group of 1 to 2 mol% grafted; Polypropylene resin composition for a door trim for automobile interior material comprising a. The method of claim 1, The high crystalline ethylene-propylene copolymer has an ISOTATIC INDEX of 97 to 99.9% as measured by ¹³ C NMR, and is characterized in that an automobile is used alone or in combination. Interior polypropylene resin composition. The method of claim 1, The inorganic filler is at least one selected from talc, mica, wellastonite, calcium carbonate, silica, glass fiber, and the average particle diameter of the inorganic filler is an automotive interior polypropylene resin composition.