KR20070048992A - Polypropylene resin composition for automobile trim - Google Patents

Abstract

The present invention relates to a low specific gravity polypropylene resin composition, and more particularly, high crystalline high molecular weight polypropylene, low molecular weight polypropylene, an inorganic filler, an elastomer and a lubricant in an optimal ratio, and minimized the ratio of the inorganic filler molded article It reduces the weight of, and is excellent in terms of physical properties such as impact resistance and stiffness of the conventional, but overcomes the drawback that the weight increases as the impact strength is high, maintaining the superiority of the characteristics such as stiffness, heat resistance and low temperature impact strength, heat The present invention relates to a low specific gravity polypropylene resin composition that can be suitably used as an automotive interior material having minimized deformation and scratch crack generation.

Polypropylene, low specific gravity, rigid, heat resistant, automotive, trim

Description

Polypropylene resin composition for automobile trim

The present invention relates to a low specific gravity polypropylene resin composition, and more particularly, high crystalline high molecular weight polypropylene, low molecular weight polypropylene, an inorganic filler, an elastomer and a lubricant in an optimal ratio to minimize the ratio of the inorganic filler material of the molded article It reduces the weight and is excellent in terms of physical properties such as impact resistance and stiffness, but overcomes the drawback of increasing weight with higher impact strength, and maintains superiority of properties such as stiffness, heat resistance and low temperature impact strength, and thermal deformation The present invention relates to a low specific gravity polypropylene resin composition which can be suitably used as an automotive interior material having minimal durability of scratch crack generation.

Polycarbonate / acrylonitrile-butadiene-styrene copolymer resin (PC / ABS), an engineering resin widely used as a conventional automotive interior material, was able to satisfy the physical properties required for each component, but the component weight was relatively high due to its high specific gravity. Due to its high price and high price, it is being tried to replace with polyolefin composite resin to reduce the weight and cost of vehicles. Polyolefin resins have emerged as an alternative material of such materials, and among them, polypropylene composite resins are widely used in interior and exterior materials of automobiles because they have great advantages such as moldability, impact resistance, and chemical resistance. However, the polypropylene resin composition developed so far is well balanced in terms of molecular structure, low in price, and has excellent properties such as rigidity, impact strength, and bendability. This increases, there is a problem that the weight of the part during injection molding increases. Therefore, as the weight of the vehicle becomes thinner, it is urgent to develop a polypropylene composite resin having dimensional stability and securing fluidity required for injection molding as parts thickness becomes thinner. Automotive interior materials that are commonly used have been used by injection molding a material in which polyolefin rubbers and various inorganic fillers are added to polypropylene, but there are high specific gravity difficulties mentioned above.

Therefore, there is an urgent need for the development of excellent materials with low specific gravity while having impact resistance suitable as automobile interior materials, especially as trim materials.

Accordingly, the present inventors have tried to solve the high specific gravity problem of the conventional polypropylene composite resin as described above.

As a result, low-molecular-weight polypropylene resins, inorganic fillers, elastomers, and lubricants were mixed with high-crystalline high-molecular-weight polypropylene resins in an optimum ratio to enhance impact strength and formability, thereby completing a low specific gravity polypropylene resin.

Therefore, an object of the present invention is to provide a low specific gravity polypropylene resin composition having improved rigidity, moldability and high specific gravity.

In the low specific gravity polypropylene resin composition,

High crystalline high composition consisting of one or more mixtures selected from propylene having a weight average molecular weight of 15,000 to 16,000 g / mol and an ethylene-propylene block copolymer having an isoprotective index of at least 97% mm and a melt index of 0.5 to 50 g / 10 minutes Molecular weight polypropylene 55-70 wt%;

10-30% by weight of low molecular weight polypropylene consisting of propylene having a melt index of 0.5 to 50 g / 10 minutes, a weight average molecular weight of 13,000 to 14,000 g / mol, and a mixture of one or more selected from ethylene-propylene block copolymers ;

5-10 wt% of inorganic filler;

10-30% by weight of elastomer; And

The low specific gravity polypropylene resin composition, characterized in that 0.1 to 0.3% by weight of lubricant is contained.

The present invention will be described in more detail as follows.

The present invention provides a high crystalline high molecular weight polypropylene having an MDTD of 97% mm or more and a weight average molecular weight of 15,000 to 16,000 g / mol, a low molecular weight polypropylene having an melt index of 0.5 to 50 g / 10 minutes, an inorganic filler, The present invention relates to a polypropylene resin composition containing an elastic body and a lubricant, having excellent mechanical performance such as rigidity by minimizing the ratio of inorganic fillers, and particularly suitable for molding a low-cost automotive door trim.

The components of the polypropylene resin composition of the present invention will be described in more detail as follows.

The high crystalline high molecular weight polypropylene resin used in the present invention imparts durability and scratch resistance to the resin due to its high degree of crystallinity, and is usually produced by a Ziegler-Natta based catalyst. The high crystalline high molecular weight polypropylene of the present invention is a propylene, ethylene-propylene block copolymer having an isoprotective water (ISOTATIC INDEX) of 97% or more, which is a pentad fraction (% mm) measured by 13C nuclear magnetic resonance spectroscopy (NMR SPECTROSCOPY), And mixtures of one or two or more selected from these. The high crystalline high molecular weight polypropylene of the present invention preferably has an MDTD of 97 to 99.9% mm or more, a problem such as deformation due to shrinkage when less than 97% mm, and a melt index (MI) of 0.5. It is preferably in the range of 50 g / 10 min. If the melt index is less than 0.5 g / 10 min, there is a problem in moldability, and when it exceeds 50 g / 10 min, there is a problem of lowering the impact strength at low temperature. In the case of the high crystalline high molecular weight polypropylene, it is used in the range of 55 to 70% by weight relative to the total low specific gravity polypropylene resin composition, and if the content is less than 55% by weight, the scratch resistance of the high crystalline high molecular weight polypropylene It is difficult to maintain rigidity such as flexural modulus, and when the melt index exceeds 70% by weight, a high elasticity of 25 or more is not preferable because of insufficient impact strength.

In the present invention, the highly crystalline ethylene-propylene block copolymer contains 3 to 10% by weight of ethylene, and if the ethylene content is less than 3% by weight, it tends to be too hard, so that the impact resistance is lowered, and the ethylene content is 10% by weight. If it exceeds%, it tends to be too soft, resulting in deterioration of scratch resistance.

As another component, low molecular weight polypropylene resins are added to improve the flowability of the resin during molding and to compensate for the low impact strength at low temperatures. The low molecular weight polypropylene is preferably one or two or more mixtures selected from propylene, ethylene-propylene block copolymers and mixtures thereof, and has a melt index (MI) of 0.5 to 50 g / 10 min, wherein the melt If the index is less than 0.5 g / 10 minutes, there is a problem in moldability, when 50 g / 10 minutes is exceeded it is not preferable because the problem of low temperature impact strength decreases. The content of the low molecular weight polypropylene resin is 10 to 30% by weight, preferably 15 to 20% by weight. If the content is less than 10% by weight does not affect the flowability, if it exceeds 30% by weight is insufficient impact strength and scratch resistance is poor.

In another composition, the inorganic filler of the present invention serves as a filler in a low specific gravity polypropylene resin composition to improve scratch resistance, reduce cost, slightly stiffness, and adjust the size of molded articles in the resin. Indicates. In the present invention, the particles of the inorganic filler are smaller and spherical, so as to induce a reinforcing effect by increasing the tension of the particle surface, using an average particle size in the range of 1 ~ 4 ㎛, if less than 1 ㎛ in the conventional mixing method uniform It is difficult to disperse, and when 4 µm is exceeded, there is a fear that cracks occur around the particles, and the elongation is insufficient. In addition, the content of the inorganic filler is contained in the range of 5 to 10% by weight with respect to the total content, if less than 5% by weight does not sufficiently serve as a filler in the polypropylene resin, when it exceeds 10% by weight elongation is insufficient. The weight of the part becomes heavy. In the present invention, the inorganic filler is not particularly limited to those used in the art, but may be used one or a mixture of two or more selected from talc and wollastonite, clay, calcium carbonate and stone powder.

In the present invention, an elastomer is used, and an ethylene-propylene elastomer (EPR), an ethylene-propylene-diene-based elastomer (EPDM), a polyethylene elastomer made of a metallocene catalyst, and one or two elastomers by ethylene-propylene copolymerization. The elastomer is used in the range of 10 to 30% by weight, and when used below 10% by weight, the impact strength is lowered by lowering the impact strength when used at less than 10% by weight. Problems such as scratching due to scratchability deterioration and moldability deterioration due to fluidity deterioration occur.

In addition, the lubricant used in the present invention (ANTIADDITIVE) is used to improve the flow resistance and scratch resistance of the entire polypropylene resin composition, mainly fatty acids, fatty acid amides, monoesters and 40 to 90 of the fatty acids, fatty acid amides, monoesters One or a mixture of two or more selected from monostearate and the like containing a weight% may be used. In the present invention, the lubricant is used in the range of 0.1 to 0.3% by weight with respect to the total polypropylene resin composition, when less than 0.1% by weight does not show the effect of improving the fluidity, when 0.3% by weight is no longer improved scratch resistance Do not.

In addition, as an additive, an antioxidant, a heat stabilizer, a processing aid, and an ultraviolet stabilizer may be appropriately added in addition to the composition. The low specific gravity polypropylene resin composition of the present invention is usually produced by the following process. First, a high crystalline high molecular weight polypropylene, a low molecular weight polypropylene, an inorganic filler, an elastomer lubricant, and other additives are mixed / kneaded, and then pelletized and injection molded to prepare a component based on a low specific gravity polypropylene resin composition. The low specific gravity polypropylene resin composition prepared according to the present invention can be applied to trim parts of doors or pillars of automobiles. By changing and applying the existing high specific weight polypropylene resin composition applied to trim parts such as the door and pillar to the low specific weight polypropylene resin prepared according to the present invention, workability (productivity) is reduced due to the weight of each part This increases and costs are reduced.

Hereinafter, the present invention will be described in more detail based on the following examples, but the present invention is not limited to the examples.

In the examples and comparative examples, the symbol means the following contents.

1. Polypropylene

P: High crystalline high molecular weight polypropylene (ethylene content 5%, melt index 30)

P-1: Polypropylene (Block) (Korea Petrochemical Company, SB9430)

P-2: Polypropylene (Homo) (Korea Oil Chemical, HJ4045)

P-3: Polyethylene (LDPE) (LG Daesan Emulsification, BF610)

P-4: Polypropylene (block) (ethylene content 10%, melt index 30)

2. Elastomer

E: ethylene-propylene copolymer (Dupont-Dow, EG8180)

3. Inorganic filler

I: Talc (KDM, KDM-9300)

4. Activator

A: Fatty acid amide (era trading, Ca-ST)

5. Other inhibitors

Prevent-O: Antioxidant (Songhwa Industry, AO-1010)

The physical property evaluation method of the following Example and a comparative example was performed based on the following test method.

<Test method>

1) Melt index (MI, g / 10min): The test was carried out according to ASTM D1238 (230 ° C, 2.16 kg).

2) Specific gravity (g / μl): It was performed according to ASTM D 791.

3) Tensile strength (Kg / cm ³ ): It was carried out in accordance with ASTM D 638 (thickness of 3 mm, 23 ℃).

3) Flexural modulus (Kg / cm ³ ): It was carried out in accordance with ASTM D 790 (test thickness 6 mm, 23 ℃).

4) Impact strength (NOTCHED IZOD, Kgcm / cm ² ): It was carried out in accordance with ASTM D 256 (6 mm thickness, 23 ℃).

5) Heat deflection temperature (° C.): It was carried out according to ASTM D 648 (4.6Kg rod, specimen thickness 6 mm).

6) Pencil hardness: It carried out based on JISK0220.

Example 1

First, as shown in Table 1 below, each component is melt mixed / kneaded in a twin screw extruder under conditions of 190 to 210 ° C., feeding 90 rpm, screw 260 rpm, and screw diameter 45 poise according to the content ratio to prepare pellets. Afterwards, specimens for measuring physical properties were manufactured using an injection molding machine, and each specimen was tested by the test method, and the results are shown in Table 2 below.

Comparative Examples 1 to 4

Perform the same as Example 1, but melt mixing in a twin screw extruder under conditions of 190 to 210 ℃, feeding 90 rpm, screw 260 rpm, and screw diameter 45 poise depending on the content ratio as shown in Table 1 After kneading and preparing pellets, specimens for measuring physical properties were prepared by using an injection molding machine, and each specimen was tested by the test method, and the results are shown in Table 2.

Division (weight%) Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 P 60    34.4 30 39.4 39.4 P-1 - 35 - 20 20 P-2 - - - 20 - P-3 - 5 - - - P-4 17.2 - 46.4 - - E 15 10 8 - 15 I 7 15 15 20 25 A 0.3 0.1 0.1 0.1 0.1 Prevent-O 0.5 0.5 0.5 0.5 0.5

division Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Melt index 27.2 22 35 8 8 importance 0.95 0.99 1.00 1.04 1.10 The tensile strength 245 220 200 300 250 Elongation at Break 150 40 30 10 30 Flexural modulus 18700 18000 18000 25000 26000 Izod impact strength 16.4 9.0 7.0 4.5 15.0 Heat deflection temperature 128 125 125 135 125 Pencil hardness 2B 2B 2B F 2B

In summary, as shown in Table 2, the use of high crystalline high molecular weight polypropylene resin is particularly low in specific gravity and excellent mechanical properties such as melt index, elongation at break, and Izod impact strength. In order to achieve a balanced performance improvement, it is shown that the optimum ratio of the present invention should be followed.

As described above, according to the present invention, the low specific gravity polypropylene resin composition is economical and instrument panel by providing a molded article of low specific gravity at the same time without significantly lowering the mechanical performance compared to the conventional high specific gravity polypropylene resin It can also be used as interior parts for automobiles.

Claims (4)

In the low specific gravity polypropylene resin composition, High crystallinity consisting of one or more mixtures selected from propylene and ethylene-propylene block copolymers having a weight average molecular weight of 15,000 to 16,000 g / mol with an isomer of at least 97% mm and a melt index of 0.5 to 50 g / 10 min. 55 to 70 weight percent of high molecular weight polypropylene; 10 to 30% by weight of low molecular weight polypropylene consisting of propylene having a melt index of 0.5 to 50 g / 10 minutes, a weight average molecular weight of 13,000 to 14,000 g / mol, and one or more mixtures selected from ethylene-propylene block copolymers ; 5-10 wt% of inorganic filler; 10-30% by weight of elastomer; And Low specific gravity polypropylene resin composition, characterized in that 0.1 to 0.3% by weight of lubricant. The method of claim 1, The inorganic filler has an average particle diameter of 1 to 4 ㎛, low specific gravity polypropylene resin composition, characterized in that one or two or more selected from talc, wollastonite, clay, calcium carbonate and stone powder. The method of claim 1, wherein the elastomer is one or a mixture of two or more of ethylene-propylene elastomer, ethylene-propylene-diene-based elastomer, polyethylene elastomer made of metallocene catalyst, and elastomer by ethylene-propylene copolymerization. A low specific gravity polypropylene resin composition. The low specific gravity polypropylene resin composition according to claim 1, wherein the lubricant is one or a mixture of two or more of fatty acids, fatty acid amides, and monoesters.