KR20130074396A - Polypropylene resin composition - Google Patents

Abstract

PURPOSE: A polypropylene resin composition is provided to have excellent rigidity and impact strength, to have excellent moldability, and to remarkably reduce flow marks. CONSTITUTION: A polypropylene resin composition comprises 45-90 wt% of a xylene-soluble part and a propylene homopolymer with a melt index of 25-100 g/10 minutes (230 °C); 5-50 wt% of a blend of two or more ethylene-alpha-olefin-based random copolymers having different inherent viscosities from each other; and 5-50 wt% of an inorganic filler. The polydispersity index of the propylene-based block copolymer is 5-12, and the stereoregularity thereof by a pentad method is 94% or more.

Description

Polypropylene Resin Composition

The present invention relates to a polypropylene resin composition, and more particularly, to a high-flow polypropylene resin composition having good mechanical properties such as rigidity and impact resistance, and having excellent moldability during injection, and which can significantly reduce flow marks. will be.

Today, the price of raw materials, such as international oil prices and steel, is rising, which increases the demand for automotive parts materials that can provide high fuel efficiency cars at economical prices. Plastic materials are emerging as automotive parts materials that can satisfy these demands, and in recent years, polypropylene resins have been in the spotlight.

Since the polypropylene resin has the advantage of high weight and easy recycling of parts, it is not only a vehicle interior material such as a panel, a console body, a pillar, and a door trim, but also a bumper ( It has been applied to various applications such as exterior materials such as bumpers and side moldings. However, in the injection process using the polypropylene resin, a coating process must be introduced in order to prevent appearance defects due to flow marks, that is, flow traces of the molten resin, and the cost of the injection process is increased due to the introduction of the coating process. There is an increasing problem. Therefore, there is a demand for the development of a polypropylene resin that is excellent in mechanical properties for application to automotive parts, and can reduce the occurrence of flow marks during injection to simplify the injection process and provide a product at economical cost.

The present invention is to solve the problems of the prior art as described above, the object of the present invention is good mechanical properties such as stiffness and impact resistance, excellent moldability during injection and can significantly reduce the flow mark It is to provide a high flow polypropylene resin composition.

Aspects of the present invention for achieving the above object,

 (A) 45 to 90% by weight of a high flow propylene block copolymer having a melt index of 25 to 100 g / 10 min (230 ° C.) and an intrinsic viscosity ratio of the xylene soluble portion to the propylene homopolymer of 3 to 8;

(B) 5 to 50% by weight of two or more ethylene-α-olefin based random copolymers having different intrinsic viscosity; And

(C) 5 to 50% by weight of inorganic filler

It relates to a polypropylene resin composition comprising a.

The (A) propylene-based block copolymer may have a polydispersity index (PI) of 5 to 12.

The (A) propylene block copolymer may have a stereoregularity index of 94% or more by the nuclear magnetic resonance pentad method.

The ethylene-α-olefin-based random copolymer having the lowest intrinsic viscosity among the blends of (B) two or more ethylene-α-olefin-based random copolymers may be included in an amount of 20 to 40% by weight based on the blend. In addition, the intrinsic viscosity ratio of the (B) two or more ethylene-α-olefin-based random copolymer may be 2 to 5.

The content of the α-olefin comonomer in the (B) two or more ethylene-α-olefin based random copolymers may be included in an amount of 10 to 50% by weight based on the ethylene-α-olefin based random copolymer.

The α-olefin-based comonomer may be 4 to 12 carbon atoms.

The polypropylene resin composition according to the present invention is excellent in moldability and at the same time excellent in balance between rigidity and impact resistance.

In the polypropylene resin composition according to the present invention, flow marks can be suppressed to reduce appearance defects caused by flow marks.

Therefore, the polypropylene resin composition according to the present invention can produce molded articles having excellent appearance characteristics without a coating process during injection, and thus can provide automotive interior / exterior components at a more economical cost than conventional polypropylene resins. .

Hereinafter, the present invention will be described in detail so that those skilled in the art can easily practice.

The polypropylene resin composition according to the present invention includes a propylene block copolymer.

The propylene-based block copolymer may improve the fluidity of the polypropylene resin composition to reduce appearance defects due to flow marks during molding.

The propylene block copolymer includes a propylene homopolymer and a propylene-α-olefin based random copolymer. The propylene-α-olefin-based random copolymer is a random copolymer of propylene and an α-olefin-based comonomer having 2 to 12 carbon atoms (excluding 3 carbon atoms). The α-olefin comonomer may be included in an amount of 1 to 10 wt% based on the propylene-α-olefin based random copolymer. When the α-olefin-based comonomer is included in less than 1% by weight, the impact resistance of the injection product of the polypropylene resin composition may be lowered and the flow mark appearance defect may be intensified. This difficulty can increase the appearance defect of the molded body.

The propylene block copolymer may have a melt index (MI, 230 ° C. and 2.16 kg under conditions of ASTM D1238) of 25 to 100 g / 10 minutes, and preferably 50 g / 10 minutes to 70 g / 10 minutes. . When the melt index (MI) of the propylene block copolymer is less than 25 g / 10 minutes, the flowability of the resin composition in the mold may be lowered when the polypropylene resin composition is injected, and when it exceeds 100 g / 10 minutes, Impact resistance may be lowered.

The xylene soluble portion (XS) of the propylene block copolymer and the intrinsic viscosity ratio (h _XS / h _homoPP ) of the propylene homopolymer may be 3 to 8, preferably 4 to 6. When the intrinsic viscosity ratio (h _XS / h _homoPP ) of the propylene block copolymer is less than 3, a flow mark may be severely generated on the appearance of the molded article when the polypropylene resin composition is injected. It is lowered and the effect of improving moldability cannot be obtained.

The propylene block copolymer may have a polydispersity index (PI) of 5 to 12 or less, and preferably 6 to 9. If the polydispersity index of the propylene-based block copolymer is less than 5, the flowability in the mold may be lowered and the flow mark may be deepened when the polypropylene resin composition is injected. If the polydispersity index is more than 12, the injection product is injected. The distortion of can significantly increase.

The polydispersity index of the propylene block copolymer indicates properties related to the molecular weight distribution of the resin, and can be measured using a rotational viscometer (Rheometric Dynamic Spectrometer, RDS) through a rheological method known in the art. Can be.

The propylene-based block copolymer may have a high stereoregularity having a stereoregularity index of 94% or more on the nuclear magnetic resonance pentad method. The stereoregularity index represents the stereoregularity index of the propylene homopolymer in the propylene block copolymer. If the stereoregularity index of the propylene homopolymer in the propylene block copolymer is less than 94%, the rigidity of the injected product may be lowered, which is not preferable.

In the nuclear magnetic resonance pentad method, the stereoregularity index is a measure of isotacticity, which is a pentad unit in a polypropylene molecule, using 13C-NMR. The isotacticity is a fraction of propylene monomer units at the center of a chain in which five propylene monomer units are meso-bonded in series. More specifically, the isotacticity which is the area fraction of the meso bond peak (mmmm) in the total absorption peak of the methyl carbon region of the 13C-NMR spectrum, ie, the stereoregularity index according to the pentad method, is measured. (Prog. Polym. Sci. 26, 443 (2001)).

The propylene-based block copolymer may be included in 45 to 90% by weight with respect to the resin composition, preferably 50 to 80% by weight. When the propylene-based block copolymer is included in less than 45% by weight, the stiffness and hardness of the resin composition may be lowered, the melt index may be lowered, and the moldability may be lowered. The impact resistance of may be lowered.

The polypropylene resin composition according to the present invention may include an ethylene-α-olefin-based random copolymer. The ethylene-α-olefin-based random copolymer may act as a rubber component in the polypropylene resin composition and improve the impact resistance of the resin composition.

The ethylene-α-olefin-based random copolymer is a random copolymer of ethylene and an α-olefin-based comonomer having 4 to 12 carbon atoms. Specifically, ethylene-1-butene random copolymer, ethylene-1-pentene random copolymer, ethylene-1-hexene random copolymer, ethylene-1-heptene random copolymer, ethylene-1-octene random air It may be one or more selected from the group consisting of a copolymer, ethylene-1-deken random copolymer, ethylene-1-undeken random copolymer and ethylene-1-dodecene random copolymer, preferably ethylene-1-butene ( butene) random copolymer, 1-ethylene-1-hexene random copolymer or ethylene-1-octene random copolymer.

The ethylene-α-olefin-based random copolymer may include 10 to 50% by weight of the α-olefin-based comonomer relative to the ethylene-α-olefin-based random copolymer, preferably 10 to 25% by weight It may include. When the α-olefin-based comonomer is included in less than 10% by weight can not improve the impact resistance of the polypropylene resin composition, if contained in more than 50% by weight gel (gel) is formed on the surface of the injection molding of the resin composition There is a fear that poor appearance.

Preferably, the polypropylene resin composition includes a resin in which two or more kinds of ethylene-α-olefin based random copolymers having different intrinsic viscosity are blended. In the case of constituting two or more kinds of the ethylene-α-olefin-based random copolymers, mechanical properties, flow properties, and moldability, such as impact strength of the resin composition, are higher than those of the ethylene-α-olefin-based random copolymers alone. Can be further improved.

The inherent viscosity ratio for each of the ethylene-α-olefin-based random copolymers in the blend of two or more ethylene-α-olefin-based random copolymers may be 2 to 5. The intrinsic viscosity ratio is a ratio of high intrinsic viscosity to low intrinsic viscosity of the ethylene-α-olefin-based random copolymer. If the intrinsic viscosity ratio of the ethylene-α-olefin-based random copolymer is less than 2, the effect of improving the melt index of the polypropylene resin composition may not be obtained, and if it exceeds 5, the ethylene-α-olefin-based random copolymers may blend properly. Not moldability may be reduced when the injection of the resin composition. The intrinsic viscosity of the ethylene-α-olefin based random copolymer having the lowest intrinsic viscosity in the two or more ethylene-α-olefin based random copolymers is 0.5dL / g to 0.8dL / g.

The ethylene-α-olefin-based random copolymer having the lowest intrinsic viscosity may be included in 10 to 90% by weight, preferably 20 to 80% by weight relative to the blend of ethylene-α-olefin-based random copolymer It may be included as. When the ethylene-α-olefin-based random copolymer having a low intrinsic viscosity is included in less than 10% by weight, the effect of improving the flowability of the polypropylene resin composition or reducing the appearance defect due to the flow mark is low. When included in excess of the weight% may be improved in appearance or flowability in the mold during injection, the impact resistance is lowered may be difficult to apply to the product.

The blend of the two or more ethylene-α-olefin-based random copolymer may be included in 5 to 50% by weight, preferably 15 to 30% by weight relative to the resin composition. When the blend of the two or more ethylene-α-olefin-based random copolymer is included in less than 5% by weight of the rubber component in the polypropylene resin composition may be reduced impact resistance, if included in excess of 50% by weight Excessive rubber components in the resin composition may lower the flowability and increase the appearance defect of the molded body.

The polypropylene resin composition according to the present invention may include an inorganic filler.

The inorganic filler may improve mechanical properties such as impact properties and stiffness in the polypropylene resin composition.

The inorganic filler may be powdery or fibrous, at least one selected from the group consisting of barium sulfate, calcium sulfate, magnesium sulfate, calcium carbonate, mica, crystalline calcium silicate, talc, and the like, and preferably talc. .

The inorganic filler may be included in 2 to 50% by weight. When the inorganic filler is included in less than 2% by weight, the rigidity of the polypropylene resin composition may be lowered. When the inorganic filler is included in an amount of more than 50% by weight, the flowability of the injection surface may be reduced.

The polypropylene resin composition according to the present invention may further include additives and solvents known in the art within the scope of not impairing the object of the present invention. Specifically, for example, antioxidants, nucleating agents, heat stabilizers, weather stabilizers, antistatic agents, lubricants, slip agents, flame retardants, pigments, dyes and the like can be used, preferably antioxidants and ultraviolet rays to impart heat and weather stability An absorbent etc. can be added. The additives can be appropriately adjusted by those skilled in the art without departing from the object of the present invention.

There is no restriction | limiting in particular in the method of manufacturing the polypropylene resin composition of this invention, A conventionally well-known method of manufacturing a polypropylene resin composition can be used, or a part can be modified and used in order to achieve the objective of this invention. In addition, the components constituting the resin composition may be selected and mixed according to a desired order without any particular order limitation, and specifically, kneader, for example, by the required amount of each component and other additives as described above. It may be prepared by a method of kneading raw materials introduced by using a device such as a roll, a kneader such as a Banbury mixer, or a single screw twin screw extruder, but is not limited thereto. no.

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 In the comparative example  Ingredients Used>

1. Propylene-ethylene block copolymer ( PE )

Item PE 1 PE 2 PE 3 PE 4 PE 5 Melt Index (g / 10 min) 62 55 68 22 61
PI (propylene homopolymer) 8.2 4.2 6.2 6.7 6.5
Stereogram (%) 97 96 92 96 96
Intrinsic viscosity ratio ( _XS / _homoPP ) 4.5 3.7 3.9 4.3 1.5
Ethylene Content (%) 4.2 4.1 4.5 4.0 3.9

2. Ethylene-α-olefin random copolymer ( ER )

Item ER 1 ER 2 α-olefin comonomer type 1-butene 1-butene Ethylene Content (%) 86 88 Density (g / cc) 0.861 0.867 Intrinsic viscosity (dL / g) 2.1 0.7

** Ethylene-α-olefin random copolymer ( Tafmer , Mitsui Chemical )

 3. Talc  And black masterbatch

1) Talc: Manufacturer, Product Name (Koch co., KC2000)

2) Black Masterbatch: Manufacturer, Product Name (Woosung Chemical, MK450G)

< Example  1 to 3 and Comparative example  1 to 3>

According to the content of Table 3 below, the propylene-ethylene block copolymer and the ethylene-α-olefin-based random copolymer were collectively added to a twin screw extruder (Japan Ikegai) and kneaded to prepare a polypropylene resin composition. The content of the composition is shown in Table 3. The content in Table 3 is by weight.

Configuration Example Comparative example One 2 3 One 2 3 Composite resin composition
(weight%) PE 1 60 60 PE 2 60 PE 3 60 PE 4 60 PE 5 60 ER 1 13 13 13 13 13 - ER 2 7 7 7 7 7 20 Talc 18 18 18 18 18 18 Masterbatch 2 2 2 2 2 2

< Experimental Example > Standard Specimen Preparation and Property Evaluation

The polypropylene resin composition shown in Table 3 was injected into Samsung Klucner FCM-110 (110 tons of clamping force) and injected (cylinder temperature: 230 ° C, mold temperature: 60 ° C), 2 mm thick sheet specimens and specimens specified in ASTM D638 standard. Was produced. The specimens were measured for physical properties in the following manner, and the results are described in Table 5.

How to measure property

1) Melt Index

The melt index was measured at 230 ° C. with a 2.16 kg load in accordance with ASTM D1238.

2) flexural modulus

Flexural modulus was measured at room temperature in accordance with ASTM D770.

3) impact strength

Impact strength was measured by measuring the Izod impact strength in a notched specimen of 3.2mm thickness at room temperature and minus 30 ℃ according to ASTM D256.

4) hardness

Hardness was measured by R-scale at room temperature according to ASTM D785.

5) Flow mark appearance defect

Flow mark appearance defects were injected by injection molding machine (LG LGH140N) through a spiral flow mold (thickness of 1.5mm thickness, 3cm in width), and evaluated visually.

Item unit shame Injection condition Injection force ton 140 Injection pressure % 70 Injection speed mm / s 5.0 Injection time second 20 Cooling time second 15 Weighing mm / s 60/60 Genus mm / s 15/15 meterage mm 70 Sukbaek completion mm 72 Mold temperature ℃ 40 Resin temperature ℃ 210

Item Example Comparative example One 2 3 One 2 3 Physical property measurement / evaluation result Melt Index (g / 10min) 27 23 28 12 27 31 Flexural modulus (kg / cm ² ) 16,000 15.200 12,200 15,900 16,500 16,100 Impact strength (room temperature, kg cm / cm) 47.2 49.1 38.3 52.3 47.5 21.1 Impact strength
(-30 ℃, kg cm / cm) 5.2 5.7 4.2 5.6 5.8 3.7 Hardness (R-scale) 61 67 56 63 65 68 Flow mark
Evaluation results Injection flow length (mm) 650 525 640 350 610 720 Flow mark occurrence degree Ⓞ △ △ ○ × △

Flow  Mark occurrence degree

Ⓞ: The flow mark is hardly noticeable.

○: The flow mark is faint.

(Triangle | delta): A flow mark is seen.

X: Flow mark is clearly seen.

As shown in Table 5, when the stereoregularity of the propylene block copolymer according to the present invention is lowered, the flexural modulus and hardness of the polypropylene resin composition are lowered, and when the polydispersity index of the propylene block copolymer is lowered, the injection product It can be seen that the flow mark increases as the length of the flow decreases.

When the melt index of the propylene block copolymer decreases, the flow length of the injection product of the polypropylene resin composition decreases, and when the intrinsic viscosity ratio (h _XS / h _homoPP ) of the propylene block copolymer decreases, the flow mark appearance defects Noticed.

When the ethylene-α-olefin-based random copolymer according to the present invention is used alone, the impact strength is drastically reduced compared to the case where the resin composition includes two or more ethylene-α-olefin-based random copolymers, and the flow You can see that the mark occurs.

The polypropylene resin composition according to the present invention can improve the flowability in the mold during injection while maintaining the mechanical properties, and can improve the appearance defect due to the flow mark of the molded body.

The polypropylene resin composition according to the present invention can provide an automotive interior / exterior component having a low cost and excellent appearance and mechanical properties by simplifying the injection process.

Claims (8)

(A) 45 to 90% by weight of a high flow propylene block copolymer having a melt index of 25 to 100 g / 10 min (230 ° C.) and an intrinsic viscosity ratio of the xylene soluble portion to the propylene homopolymer of 3 to 8;
(B) 5 to 50% by weight of a blend of two or more ethylene-α-olefin based random copolymers having different intrinsic viscosities; And
(C) 5 to 50% by weight of inorganic filler
And a polypropylene resin composition.
The method of claim 1,
The (A) propylene-based block copolymer has a polydispersity index (PI) of 5 to 12, characterized in that the polypropylene resin composition.
The method of claim 1,
The (A) propylene-based block copolymer is a polypropylene resin composition characterized in that the stereoregularity index of 94% or more by the nuclear magnetic resonance pentad method.
The method of claim 1,
(B) the ethylene-α-olefin-based random copolymer having the lowest intrinsic viscosity in the blend of two or more ethylene-α-olefin-based random copolymer is characterized in that it comprises 10 to 90% by weight relative to the blend Polypropylene resin composition.
The method of claim 1,
The polypropylene resin composition according to claim 2, wherein the intrinsic viscosity ratio of the two or more ethylene-α-olefin random copolymers is 2 to 5.
The method of claim 1,
The content of the α-olefin-based comonomer in the ethylene-α-olefin-based random copolymer is 10 to 50% by weight relative to the ethylene-α-olefin-based random copolymer.
The method according to claim 6,
The α-olefin-based comonomer is a polypropylene resin composition, characterized in that 4 to 12 carbon atoms.
A molded article made of the polypropylene resin composition of claim 1.