KR20040054899A - Polypropylene resin composition with superior scratch resistance and impact strength - Google Patents

Abstract

PURPOSE: A polypropylene resin composition for the interior materials of a car is provided, to improve scratch resistance, impact strength, heat resistance and hardness. CONSTITUTION: The resin composition comprises 30-70 wt% of a propylene-ethylene block copolymer which comprises 70-100 wt% of a propylene polymer and 0-30 wt% of a propylene-ethylene copolymer; 5-30 wt% of an olefin-based elastomer which comprises an ethylene-propylene copolymer rubber or an ethylene-α-olefin copolymer; 0.01-0.2 wt% of an organic peroxide; 0.06-1.2 wt% of a crosslinking auxiliary; 5-40 wt% of an inorganic filler which is a needle-like silica or a mixture of a needle-like silica and one selected from talc, barium sulfate, calcium carbonate and wollastonite; and 1-7 wt% of a modified polypropylene resin which is grafted by an unsaturated carbonic acid and its derivatives and has a degree of grafting of 0.5-5 wt%.

Description

Polypropylene resin composition with superior scratch resistance and impact strength

The present invention relates to a polypropylene resin composition for automobile interior having excellent scratch resistance and impact strength, and more particularly, to an propylene-ethylene block copolymer, to which an olefin elastomer, an organic peroxide and a crosslinking aid are added, and a needle-like silica or plate It is useful as parts of automobiles and home appliances by adding talc and modified polypropylene, and having excellent scratch resistance to damage the surface of molded products, and excellent molding processability as well as physical properties such as heat resistance, low temperature impact properties, and rigidity. The present invention relates to a polypropylene resin composition which can be suitably used for interior parts of automobiles and the like, in which appearance quality of products is important.

Conventional propylene-based resins are widely used for exterior materials such as automobile bumpers and interior materials such as various fillers because they have excellent moldability, impact resistance, chemical resistance, and the like, and have advantages of low specific gravity and low cost. However, in the case of automobile interior materials such as glove box, console, and pillar trim, the development of materials with significantly improved impact strength and scratch resistance balance to satisfy safety and aesthetic effects at the same time This situation is required.

Polypropylene resin compositions developed as automotive interior materials such as glove boxes, consoles, and filler trims are good products in terms of physical properties such as impact resistance and stiffness, but the higher the impact strength, the lower the scratch resistance. . Therefore, when impact resistance and scratch resistance are required at the same time, a separate paint work is required, which is accompanied by a cost increase. In Korea Patent Application No. 2000-64690, a polypropylene resin composition having excellent impact strength and scratch resistance has been proposed, but in this case, when crosslinking is excessive, a high molecular weight elastomer is produced, which improves scratch resistance while processing flow marks. It has a disadvantage in that the appearance quality is deteriorated due to the occurrence and there is a problem that the scratch performance is not improved if the crosslinking is insufficient.

Therefore, the development of a resin composition not only excellent in mechanical properties such as impact strength and rigidity, flow marks and the like but also excellent in scratch resistance has emerged as an urgent problem that is very important in the automobile industry.

In order to solve the conventional problems, the present inventors add olefin-based elastomers, organic peroxides and crosslinking aids to propylene-ethylene block copolymers, and add acicular silica or plate-like talc, modified polypropylene, and the like to damage the surface of the molded article. The present invention has been completed by developing a polypropylene resin composition which is very useful for parts of automobiles and home appliances by having excellent scratch resistance and excellent molding processability as well as physical properties such as heat resistance, low temperature impact characteristics and rigidity.

Accordingly, an object of the present invention is to provide a polypropylene resin composition for automobile interior having excellent scratch resistance and impact strength.

The present invention

30 to 70 wt% of a propylene-ethylene block copolymer composed of 70 to 100 wt% of a propylene polymer and 0 to 30 wt% of a propylene-ethylene copolymer;

5 to 30% by weight of an olefin elastomer composed of an ethylene-propylene copolymer rubber or an ethylene-α-olefin copolymer;

0.01 to 0.2% by weight of organic peroxide;

0.06 to 1.2% by weight of crosslinking aid;

5 to 40% by weight of an inorganic filler having a needle-like silica having an average particle diameter of 0.5 to 10 µm or a mixture of other inorganic fillers selected from talc, barium sulfate, and calcium carbonate stononite; And

It is characterized by a polypropylene resin composition which is grafted with unsaturated carboxylic acid and derivatives thereof and contains 1 to 7% by weight of a modified polypropylene resin having a graft ratio of 0.5 to 5% by weight.

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

The present invention is excellent in scratch resistance and heat resistance by adding olefin elastomer, organic peroxide and crosslinking aid to the propylene-ethylene block copolymer, and adding needle-like silica or plate-like talc, modified polypropylene to damage the surface of the molded article. The present invention relates to a polypropylene resin composition which is very useful for parts of automobiles and home appliances due to excellent molding processability as well as physical properties such as low temperature impact characteristics and rigidity.

In the resin composition according to the present invention, the polypropylene polymer is a crystalline polymer composed of a propylene polymer containing propylene monomer as a main component and a propylene-ethylene copolymer containing ethylene, and a mixture of propylene polymer alone or a part of propylene-ethylene copolymer Also used. The propylene polymer has a value of mmmm fraction of 96% or more, preferably 96.5% or more, and more preferably 97% or more in the pentad fraction (mmmm fraction) measured by ¹³ C-NMR. If the mmmm fraction is less than 96%, the stiffness and heat resistance will be degraded. Moreover, the intrinsic viscosity [(eta)] measured in 135 degreeC decalin of the propylene polymer is 1.0-3.0 dl / g. If [η] is less than 1.0 dl / g, the impact strength is lowered, and if it exceeds 3.0 dl / g, moldability is lowered, so it is preferably 1.5 to 2.5 dl / g. Moreover, as for the propylene ethylene copolymer, intrinsic viscosity [(eta)] in 135 degreeC decalin of xylene extract has preferable 3.0 dl / g or more. If the intrinsic viscosity [η] is less than 3.0 dl / g, the impact strength is lowered. More preferable intrinsic viscosity [eta] is 3.5 dl / g or more, especially 4.0 dl / g or more. In addition, the content of ethylene is 3 to 20% by weight, preferably 5 to 15% by weight. If the ethylene content is less than 3% by weight, there is a problem of lowering the impact strength, and if it exceeds 20% by weight, there is a problem of scratch resistance and stiffness.

In addition, the propylene polymer and the propylene-ethylene copolymer have a weight ratio of 70 to 100: 30 to 0, more preferably 80 to 100: 20 to 0, and a weight ratio is preferable in terms of impact strength and fluid balance. In other words, the propylene polymer lacks impact resistance, and the propylene-ethylene copolymer lacks moldability, rigidity, heat resistance, and the like. .

The blending ratio of the propylene-ethylene block copolymer in the polypropylene resin composition is 30 to 70% by weight, preferably 45 to 65% by weight of the total composition. At this time, when it exceeds 70% by weight, the impact strength is lowered, and when it is less than 30%, moldability is lowered.

Meanwhile, the rubber component of the polypropylene resin composition according to the present invention is an olefin elastomer composed of ethylene-propylene copolymer rubber and ethylene-α-olefin copolymer alone or in a blend, the content of which is 5 to 30% by weight, Preferably it is 15-25 weight%. If it exceeds 30% by weight, the rigidity and formability are inferior, and when it is less than 5% by weight, the impact strength is lowered.

In ethylene propylene copolymer rubber (EPR), melt index (MI) of 230 degreeC is 0.1-50 g / 10min, Preferably it is 1.0-30 g / 10min. If the MI is less than 0.1 g / 10min, a dispersion mark is caused, resulting in a flow mark. On the other hand, when it exceeds 50 g / 10min, there exists a problem that impact resistance falls. The propylene content in the EPR is 20 to 70% by weight, preferably 40 to 60% by weight. It is because impact strength falls that propylene content is less than 20 weight%, and rigidity falls when it exceeds 70 weight%. In addition, the ethylene-α-olefin copolymer is generally used an ethylene octene-1 copolymer (EOM), in the case of the EOM used is C ₈ (octene) content of 15 to 45% by weight, preferably 25 to 35 Weight%, Mooney viscosity ML 1 + 4 (121 ° C.) is 1-50 dl / g, preferably 1.5-35 dl / g, density is 0.86-0.91 g / cm 3, preferably 0.87- 0.90 g / cm 3. At this time, when the content of octene is less than 15% by weight, the impact strength is lowered, and when the content of octene is more than 45% by weight, the rigidity is lowered. The lower the impact strength, the lower the density, if the density is less than 0.86 g / cm 3, the rigidity is lowered, if the density exceeds 0.91 g / cm 3 it is not preferable because the impact strength is lowered.

The organic peroxide in the polypropylene resin composition preferably has a half life of 1 minute and a decomposition temperature of 150 to 270 ° C. This is because scratch resistance must be improved without generating a flow mark. The content of the organic peroxide is 0.01 to 0.2% by weight, more preferably 0.02 to 0.1% by weight, and at the same time, it is necessary to consider the blending ratio with the crosslinking aid. If the content thereof is less than 0.01% by weight, the reactivity decreases, so that excellent physical properties cannot be obtained. If the content thereof exceeds 0.2% by weight, the reactivity is increased while the flowability is very severe.

In the polypropylene resin composition, a divinyl compound, a maleimide compound, a quinone dioxim compound, etc. are preferable as a crosslinking aid, and are blended in an amount of 0.06 to 1.2% by weight and blended with an organic peroxide [ (Crosslinking aid) / (organic peroxide)] should satisfy 4 to 10: 1 (weight ratio). If the organic peroxide is less than 0.05% by weight or the blending ratio is less than 3, the decomposition reaction is prioritized, and the physical properties are inferior. If the crosslinking aid is more than 1.5% by weight or the blending ratio is more than 12, physical properties cannot be expected to be improved.

As the inorganic filler used in the present invention, needle-like silica (1) having an average particle diameter of 0.5 to 10 µm is used alone, or in addition to talc, barium sulfate, calcium carbonate, and the like having an average particle size of 0.5 to 7 µm ( 2) can be used by mixing a part, and especially the talc whose average particle diameter is 7 micrometers or less is more preferable. When the average particle diameter of the silica is less than 0.5 μm, the mechanical properties are lowered due to poor dispersion, and when the average particle diameter is greater than 10 μm, the impact resistance is decreased. When the average particle diameter of the talc is less than 0.5 μm, the mechanical properties are degraded due to poor dispersion, and 7 μm. If it exceeds, impact resistance will fall. At this time, in the case of (2), 0 to 25% by weight of (1) is normally used, and when it exceeds 25% by weight, scratch performance is lowered.

Such an inorganic filler is contained within the range of 5 to 40% by weight in the total resin composition, when the content is less than 5% by weight, the rigidity and heat resistance is lowered, and when the content exceeds 40% by weight, the impact strength is lowered.

On the other hand, in addition to the above components, a polar group-containing polypropylene is used, which is added to enhance the scratching performance by increasing the bonding force between polypropylene and silica and an inorganic filler. The polar group-containing resin of the present invention uses a modified polypropylene (modified PP) in which a carboxyl group is grafted to the side chain.

The modified polypropylene of the present invention is obtained by grafting unsaturated carboxylic acid or a derivative thereof to polypropylene. At this time, a graft ratio of 0.5 to 5.0% by weight, preferably 1.5 to 5.0% by weight is used. If the graft rate is less than 0.5% by weight, the improvement of the scratch does not occur, and when 5.0% by weight is exceeded, the physical properties of the stiffness and the impact strength occur. In addition, examples of unsaturated carboxylic acids or derivatives thereof that can be used in the graft reaction include one or two or more selected from maleic acid, acrylic acid, methacrylic acid, maleic anhydride, and dimethylol paraoctylphenol, and grafting the polypropylene resin. Can be used.

In particular, the modified polypropylene resin of the present invention is 1 to 7% by weight, preferably 1 to 5% by weight based on the total polypropylene resin composition. At this time, when the content is lower than the above range, it becomes difficult to give an effect on improving scratch performance, and when it is high, it may cause a decrease in physical properties in impact and stiffness.

In the present invention, the MI of the product finally granulated under such conditions is 3 to 40. When the MI is less than 3, a decrease in productivity and a flow mark may occur in the final product, and when the MI exceeds 40, It is difficult to obtain desired physical properties in terms of stiffness and impact strength.

Additives that may be added in the present invention are conventional, for example antioxidants, neutralizing agents, nucleating agents, antistatic agents and the like, which are contained within an appropriate content range. Here, as the antioxidant, phenol-based antioxidants, phosphite-based antioxidants, thiodipropionate synergists, etc. may be used, and as neutralizing agents, calcium stearate, zinc oxide, etc. may be used, and these or other additives may be used in this field. It can be easily used by those skilled in the art.

The manufacturing method of the polypropylene resin composition of this invention is not specifically limited. For example, the polypropylene resin composition of the present invention can produce the above components by a conventional mechanical kneading method. Specifically, for example, a method using a general melt kneading machine such as a short-barrier mixer, a single screw extruder, a twin screw extruder, a multi-screw screw extruder, or the like can be adopted. Moreover, it is preferable to perform kneading temperature at 180-270 degreeC.

The molding process for the composition of the present invention is not particularly limited to extrusion molding, blow molding, injection molding, sheet molding, etc., but injection molding is most suitable.

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

Examples 1-4 and Comparative Examples 1-6

Next, a gasket composition was prepared in the same composition and content as Table 1 below.

division Example Comparative example One 2 3 4 One 2 3 4 5 6 Polypropylene PP-1 37.65 38 37.85 65.95 37.65 49.65 37.65 66.65 PP-2 PP-3 35 PP-4 35 35 72.65 35 35 79.65 Olefin Elastomer EPR-1 5 5 5 5 5 5 10 32 ERP-2 5 EOM-1 5 Organic peroxide PO-1 0.05 0.05 0.05 0.05 0.05 0.05 0.05 PO-2 0.05 0.05 Crosslinking aid CA-1 0.3 0.3 0.3 0.1 1.0 0.3 0.3 0.3 CA-2 0.3 Inorganic filler S-1 20 15 20 20 15 20 15 20 15 T-1 5 5 5 20 Polar group-containing resin MPP 2 2 3 2 2 2 3 2 3

PP-1: Melt index 8 g / min, mmmm fraction: 98.3%

PP-2: Melt index 14.5 g / min, mmmm fraction: 96.4%

PP-3: melt index 27 g / min, ethylene 60 wt%, xylene extract 15 wt%, intrinsic viscosity [η]: 3.6 dl / g

PP-4: melt index 27 g / min, ethylene 60 wt%, xylene extract 10 wt%, intrinsic viscosity [η]: 4.3 dl / g

EPR-1: melt index 3.5 g / min, comonomer 31% by weight

EPR-2: Melt index 3.5 g / min, comonomer 35% by weight

EOM-1: Mooney viscosity 23, comonomer 24 wt%

PO-1: 1,3-bis (t-butylperoxy isopropyl) benzene

PO-2: 2,5-dimethyl 2,5-di (t-butylperoxy) hexane

CA-1: Di-vinyl benzene

CA-2: P-quinone di-oxime

S-1: acicular silica with an average particle diameter of 6.7 mu m

T-1: Talc with an average particle diameter of 2.6 mu m

MPP: Polar group graft ratio 1.5 weight%, COOH group containing resin

Test Example

In order to investigate the physical properties and processability of the molding material produced using the resin produced in the present invention, MFR, impact strength, flexural strength, pencil hardness, and flow mark were evaluated according to the procedure mentioned below.

1) intrinsic viscosity

The propylene homopolymer and propylene-ethylene copolymer were used completely dissolved in decalin at 135 ° C. The Ubbeholde viscometer was used to measure the viscosity of solutions having various concentrations from 0.1 to 0.5 dl / g. Reduced viscosity was obtained by extrapolating to zero concentration.

2) ¹³ Isotatcric pentad fraction measured by C-NMR

The fraction of propylene monomers connected in series in the propylene unit was measured by ¹³ C-NMR.

3) Melt Index (MFR)

According to ASTM D1238 the melt index was measured at 230 ° C. and a load of 2.16 kg.

4) Flexural modulus

It was measured according to ASTM D790.

5) Izod impact strength

According to ASTM D256, measured with a Notched test specimen at room temperature (23 ℃).

6) Mooney viscosity

It was measured at 121 ° C. according to ASTM D1646.

7) Pencil Hardness

It was measured at room temperature (23 ° C) according to JIS K5401-1969.

8) Visual observation of Flowmark

(Double-circle): A flow mark is not observed at all.

(Circle): 1-2 flowmarks are observed faintly.

(Triangle | delta): Three to six flow marks exist and it is observed a little clearly.

×: 6 or more flow marks exist and are observed very clearly.

division Example Comparative example One 2 3 4 One 2 3 4 5 6 MI 16.6 17.8 19.8 22.3 18.5 19.3 8.3 17.4 16.3 4.7 Izod impact strength 9.1 9.5 8.6 11.2 9.2 5.8 11.5 8.9 6.2 36 Flexural Modulus (× 10 ³ ) 24.0 23.8 27.5 20.8 26.0 22.5 22.0 23.0 27.5 17.0 Pencil strength B 2B 2B 3B 5B 4B 2B 3B 2B 4B Flowmark ○ ○ ○ ◎ ◎ ◎ × △ × ×

From the results shown in Table 2, any of the resin compositions of Examples 1 to 4 could be obtained a molded article having impact resistance, rigidity, and scratch resistance. However, as in the case of Comparative Examples 1 and 2, there is no scratch resistance when there is no introduction or small amount of the crosslinking aid, and in Comparative Example 3, the flow mark is remarkable when the crosslinking aid is excessively used. The scratch resistance was inferior even when the silica compound of Comparative Example 4 was not added. In the case of Comparative Example 5, the impact strength and flexural modulus were lowered in the absence of the polar group-containing polypropylene. In Comparative Example 6, it was found that the overall physical properties were reduced except the impact strength due to excessive use of EPR.

As described above, the polypropylene resin composition according to the present invention is a thermoplastic resin, and not only has excellent physical properties such as impact resistance, rigidity, heat resistance, etc., but also has excellent scratch resistance, and thus requires different glove boxes. It is expected to be very useful for automotive interior applications such as console, pillar trim, etc. In addition, there is an economic advantage due to the removal of the coating treatment for improving the scratch resistance.

Claims (7)

30 to 70 wt% of a propylene-ethylene block copolymer composed of 70 to 100 wt% of a propylene polymer and 0 to 30 wt% of a propylene-ethylene copolymer; 5 to 30% by weight of an olefin elastomer composed of an ethylene-propylene copolymer rubber or an ethylene-α-olefin copolymer; 0.01-0.2 wt% organic peroxide; 0.06 to 1.2% by weight of crosslinking aid; 5 to 40% by weight of an inorganic filler having a needle-like silica having an average particle diameter of 0.5 to 10 µm or a mixture of other inorganic fillers selected from talc, barium sulfate, and calcium carbonate stononite; And A polypropylene resin composition characterized by containing 1 to 7% by weight of a modified polypropylene resin having a grafting rate of 0.5 to 5% by weight by grafting with unsaturated carboxylic acid and derivatives thereof. The propylene polymer according to claim 1, wherein the propylene polymer is a propylene polymer composed of propylene having an intrinsic viscosity [η] of 1.0 to 3.0 dl / g, with a pentad fraction (% mmmm) measured by ¹³ C-NMR of 96% or more. Wherein the propylene ethylene copolymer has an intrinsic viscosity [η] of the xylene extract of 3.0 to 5.0 dl / g and an ethylene content of 3 to 20 wt%. The ethylene-propylene copolymer rubber according to claim 1, wherein the ethylene-propylene copolymer rubber has a melt index of 0.1 to 50 g / 10 min, a propylene content of 20 to 70% by weight, and the ethylene-α-olefin copolymer rubber has 15 to 45 weight of octene. Polypropylene resin composition, characterized in that the%. The polypropylene resin composition of claim 1, wherein the organic peroxide has a half-life of 1 minute and a decomposition temperature in the range of 150 to 270 ° C. The method of claim 1, wherein the crosslinking aid is selected from divinyl compounds, maleimide compounds, and quinone dioxim compounds, and the blending ratio of the crosslinking aid and the organic peroxide is 4 to 10: 1 (weight ratio). Polypropylene resin composition, characterized in that. The polypropylene-based resin composition according to claim 1, wherein the talc has an average particle diameter of 0.5 to 7 mu m. The polypropylene resin composition according to claim 1, wherein the unsaturated carboxylic acid and its derivatives are single or a mixture of two or more selected from maleic acid, acrylic acid, methacrylic acid, maleic anhydride and dimethylol paraoctylphenol.