JPH06322191A - Polyolefin composition - Google Patents

Abstract

PURPOSE:To provide a polyolefin composition having excellent impact whitening resistance, moldability and surface-matting effect of molded article. CONSTITUTION:The polyolefin composition is composed of a propylene-ethylene block copolymer and two kinds of polyethylenes. The ratio of the melt viscosity of a polyethylene to that of the propylene-ethylene block copolymer falls within a prescribed range in the molding shear rate range and the melt viscosity of the other polyethylene is higher than that of the former polyethylene. The ratios of the components are selected in such a manner that the melt flow rate of the propylene-ethylene block copolymer and the total content of the two kinds of polyethylenes satisfy a prescribed relational formula.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin composition, and more particularly to a polyolefin composition excellent in impact whitening resistance, molding processability and matting effect on the surface of a molded article.

[0002]

BACKGROUND OF THE INVENTION Propylene homopolymers and copolymers are lightweight and have excellent mechanical strength and the like, and are therefore widely used in various fields. In particular, the propylene-ethylene block copolymer has high impact strength and rigidity, and is therefore suitable for injection molded products and the like.

However, this propylene-ethylene block copolymer generally has a problem that it has a certain degree of gloss (gloss) when formed into a molded product by injection molding or the like. However, in recent years, it has been required to reduce the gloss of the surface of the molded body of the propylene-ethylene block copolymer to give a high-grade feeling. Further, the propylene-ethylene block copolymer is excellent in impact resistance and rigidity, but when formed into a molded product by injection molding or the like,
There is also a problem that it is inferior in so-called impact whitening resistance, which is easily whitened by impact.

In order to solve such a problem, a composition obtained by adding an inorganic substance powder to a propylene-ethylene block copolymer (Japanese Patent Publication No. Sho 59-19145, JP-A No. 2-274743).
Or a polyolefin composition consisting of a propylene-ethylene block copolymer with a broadened molecular weight distribution (Mw / Mn> 16) and a high-density polyethylene with a melt index (MI, 190 ° C, 2.16 kg load) of 0.2 g / 10 min or less. Japanese Patent Application Laid-Open No. 62-277450 has been proposed.

However, even the above-mentioned polyolefin composition has a problem that it does not yet have a sufficient matting effect and impact whitening resistance. Further, the above composition also has a problem that the melt flow rate is small and molding processability, particularly injection moldability, is not sufficient.

Therefore, an object of the present invention is to provide a polyolefin composition which is excellent in impact whitening resistance, moldability and matte effect on the surface of a molded article.

[0007]

As a result of earnest research in view of the above object, the present inventors have found that in a composition of propylene-ethylene block copolymer and polyethylene, molding is performed on the propylene-ethylene block copolymer. Two types of polyethylene, polyethylene having a melt viscosity ratio within a predetermined range in the shear rate range and another polyethylene having a larger melt index value than the polyethylene are used, and a propylene-ethylene block copolymer is used. If the blending ratio of each component is set so that the melt flow rate and the total content of the two types of polyethylene satisfy a predetermined relational expression, good impact resistance and mechanical strength are maintained. As it is, it is possible to improve impact whitening resistance, molding processability and matte effect on the surface of molded products. Out, it was conceived with the present invention.

That is, the polyolefin composition of the present invention comprises (a) an ethylene content of 1 to 30% by weight and 20 to 100 g /
40-80% by weight of propylene-ethylene block copolymer having a melt flow rate of 10 minutes (230 ° C, 2.16 kg load), and (b) a density of 0.935 g / cm ³ or more and a melt of 5-60 g / 10 minutes. Polyethylene with index (190 ℃, 2.16 kg load) and (c) Density of 0.935 g / cm ³ or more and 0.01
~ 4.9 g / 10 min melt index (190 ℃, 2.16 kg
Polyethylene with load ((b) and (c) total 20-60
And the weight ratio of (c) to (b) ((c) / (b)) is 0.13 to 3.2,
Melt flow rate of the propylene-ethylene block copolymer (MFR _PP , 230 ° C, 2.16 kg load, unit: g /
10 minutes) and the content rate of (b) + (c) (V _PE , the unit is% by weight) satisfy the following formula: (log (MFR _PP )) / V _PE ≦ 0.060, and The melt flow rate MFR of (a) above
Frequency of 100rad / sec and 210 ° C by _PP and rotational viscometer
Wherein in measured and the ratio (R ₁₀₀₎ of the melt viscosity [eta _{100 (a)]} wherein for (c) the melt viscosity of [eta _{100 (c)]} of (a), measured at a frequency 500 rad / sec and 210 ° C. The melt viscosity of (c) against the melt viscosity of (a) (η500 _(a) ) (η500 _(c) )
The ratio (R ₅₀₀ ) is expressed by the following formula: (log (R ₁₀₀ / R ₅₀₀ ) +0.80) / log (MFR
It is characterized by satisfying _PP ) ≧ 0.40.

The present invention is described in detail below. The polyolefin composition of the present invention comprises a propylene-ethylene block copolymer and two types of polyethylenes having different melt index values (hereinafter referred to as first and second polyethylenes).

[1] Composition Component (a) Propylene-Ethylene Block Copolymer The (a) propylene-ethylene block copolymer used in the present invention has an ethylene content of 1 to 30% by weight.

When the ethylene content of the propylene-ethylene block copolymer is less than 1% by weight, the physical properties such as impact strength deteriorate, while when it exceeds 30% by weight, the physical properties such as rigidity deteriorate. The preferred ethylene content is 2 to 15% by weight.

The propylene-ethylene block copolymer preferably has a melt flow rate (MFR _PP , 230 ° C., 2.16 kg load) of 20 to 100 g / 10 minutes, particularly 40 to 80 g / 10 minutes. When the MFR _PP value is less than 20 g / 10 minutes, the moldability of the obtained composition, particularly the injection moldability, is deteriorated, and
If it exceeds g / 10 minutes, the mechanical strength decreases, which is not preferable.

The melt viscosity [η _{100 (a)} ] (measured by a rotational viscometer _{) of} the propylene-ethylene block copolymer at a frequency of 100 rad / sec and a temperature of 210 ° C. is 1000 to 30.
00, particularly preferably 1000-2000, frequency 500 ra
The melt viscosity [η _{500 (a)} ] (measured by a rotational viscometer _{) at} d / sec and 210 ° C. is preferably 600 to 1000, particularly preferably 600 to 900.

Examples of the propylene-ethylene block copolymer as described above include, for example, (1) first, only propylene is polymerized to produce a propylene polymerized portion, and then ethylene is supplied for copolymerization to carry out this operation. Those obtained by repeating once or twice or more, and (2) propylene-ethylene block copolymer synthesized by multistage polymerization can be used.

The propylene-ethylene block copolymer synthesized by multistage polymerization comprises a substantially crystalline propylene polymerized portion and a propylene-ethylene copolymerized portion.
It is composed of a crystalline ethylene polymerized portion, and each portion may be present as a single polymer or may be in a state where they are bonded.

Examples of the crystalline propylene polymerized portion include a homopolymer of propylene or a propylene copolymer containing a small amount (about 3 mol% or less) of a comomer component. As the comonomer component, butene-1, octene-
Other α-olefins and diene-based monomers such as 1 may be mentioned.

The propylene-ethylene copolymerized portion is a low crystalline portion and has an ethylene content of 30 to 60% by weight. Ethylene content is less than 30% by weight or
If it exceeds 60% by weight, ductility is insufficient. Further, the propylene-ethylene copolymer part may also contain a small amount (about 3 mol% or less) of a comonomer component.

Examples of the crystalline ethylene polymerized portion include a homopolymer of ethylene or an ethylene copolymer containing a small amount (about 3 mol% or less) of a comonomer component.

The content of the crystalline propylene-polymerized portion, the propylene-ethylene-copolymerized portion, and the ethylene-polymerized portion of the entire multistage polymerized propylene-ethylene block copolymer containing the above-mentioned portions is ++. If the total is 100% by weight, the crystalline propylene polymerized portion is 6
0-96% by weight, 1 part of propylene-ethylene copolymerization
-20% by weight and crystalline ethylene polymerized portion is preferably 1-20% by weight.

The multi-stage propylene-ethylene block copolymer as described above is produced by first polymerizing propylene in the presence of a Ziegler catalyst or the like to form a crystalline propylene homopolymer portion, and then ethylene + propylene in the next step. To produce a propylene-ethylene copolymerization moiety (a trace amount of an ethylene homopolymer moiety is also generated in this step), and in some cases, by further polymerizing ethylene, a crystalline ethylene homopolymer moiety is generated. Can be synthesized.

Among these propylene-ethylene block copolymers, the multi-stage propylene-ethylene block copolymer (2) is particularly preferable.

(B) First polyethylene The first polyethylene is 0.935 g / cm ³ or more, preferably
Density of 0.945 to 0.980 g / cm ³ and melt index (MI, 19 to 5 to 60 g / 10 minutes, preferably 20 to 60 g / 10 minutes).
0 ℃, 2.16kg load). If the melt index is less than 5 g / 10 minutes, the fluidity of the resulting composition will be poor, whereas if it exceeds 60 g / 10 minutes, the matting property and impact strength of the resulting composition will be poor. The density is 0.935 g / cm ³
Below, the rigidity of the composition decreases.

(C) Second polyethylene The second polyethylene is 0.935 g / cm ³ or more, preferably
Density of 0.945 to 0.980 g / cm ³ and 0.01 to 4.9 g / 10
Min, preferably 0.05 to 1.2 g / 10 min melt index (MI, 190 ° C., 2.16 kg load). If the melt index value is less than 0.01 g / 10 minutes, the fluidity and surface appearance of the resulting composition will be poor, whereas if it exceeds 4.9 g / 10 minutes, the effect of improving the matteness by blending two types of polyethylene will be obtained. I can't get it.

The frequency of the second polyethylene is 100 ra.
The melt viscosity at d / sec and 210 ° C [η _{100 (c)} ] (measured with a rotational viscometer) is 5500 to 17000, especially 9000 to 15000.
Is preferable, and the melt viscosity at a frequency of 500 rad / sec and 210 ° C. [η _{500 (c)} ] (measured by a rotational viscometer)
Is preferably 3000 to 8000, particularly 4000 to 8000.

[2] Blending Ratio The blending ratio between the above-mentioned (a) propylene-ethylene block copolymer and (b) first polyethylene and (c) second polyethylene is (a) propylene-ethylene block The copolymer is 40 to 80% by weight, preferably 60 to 80% by weight, and the total of (b) + (c) is 20 to 60% by weight, preferably 20.
~ 40% by weight. If the propylene-ethylene block copolymer is less than 40% by weight ((b) + (c) exceeds 60% by weight), the rigidity and moldability are deteriorated, while the propylene-ethylene block copolymer is less than 80% by weight. When it exceeds ((b) +
(If (c) is less than 20% by weight), sufficient impact whitening resistance, moldability and matte effect on the surface of the molded product cannot be obtained.

Further, (b) for the first polyethylene
(c) The weight ratio of the second polyethylene ((c) / (b)) is 0.
It is 13 to 3.2, preferably 0.2 to 3.0. Weight ratio 0.13
If it is less than 3.2, sufficient mattness cannot be obtained, while if it exceeds 3.2, the fluidity of the obtained composition is lowered.

However, in the present invention, the content rate of polyethylene ((b) + (c)) (V _PE , unit is% by weight) is
(a) Melt flow rate of propylene-ethylene block copolymer (MFR _PP , 230 ° C, 2.16 kg load, unit g / 10
Min) and the following relational expression (1) must be set. (Log (MFR _PP )) / V _PE ≦ 0.060 ・ ・ ・ (1)

In the above formula (1), if the left side exceeds 0.060, the area of the interface between the matrix phase of the propylene-ethylene block copolymer and the matrix phase of polyethylene cannot be increased sufficiently, It becomes difficult to sufficiently improve the impact whitening resistance.

It is particularly preferable that (log (MFR _PP )) / V _PE ≦ 0.055 (2) is satisfied.

[3] Melt Viscosity Ratio In the present invention, the melt flow rate (MFR _PP , 230 ° C.) of the above-mentioned (a) propylene-ethylene block copolymer,
2.16 kg load, unit g / 10 min), and melt viscosity [c] of [ _a ] against [ _a ] melt viscosity [η _{100 (a)} ] measured with a rotational viscometer at a frequency of 100 rad / sec and 210 ° C. η _{100 (c)} ] ratio ([η _{100 (c)} ] / [η _{100 (a)} ]: R
₁₀₀ ) and the above measured at a frequency of 500 rad / sec and 210 ° C
The ratio of the melt viscosity [eta _{500 (c)]} of the relative melt viscosity of (a) [eta _{50 0 (a)]} (c) ([eta _{500 (c)]} / [eta _{500 (a)]:} R
₅₀₀ ) must satisfy the following formula (3): (log (R ₁₀₀ / R ₅₀₀ ) +0.80) / log (MFR _PP ) ≧ 0.40 (3).

In the above formula, when the left side is less than 0.40, the melt viscosity of polyethylene at the molding temperature is too low and the polyethylene does not solidify into a spherical shape on the surface of the molded product, so that sufficient impact whitening resistance and moldability are obtained. Also, the matte effect on the surface of the molded product cannot be obtained.

In particular, it is preferable to satisfy (log (R ₁₀₀ / R ₅₀₀ ) +0.80) / log (MFR _PP ) ≧ ... (4).

[4] Other Components (1) Organic Peroxide In the present invention, an organic peroxide is used for the purpose of further improving impact whitening resistance, molding processability and matting effect on the surface of a molded article. Is preferably added.

Examples of organic peroxides include dicumyl peroxide, di-t-butyl peroxide, and 2,5.
-Dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3,1,3-bis (t-butylperoxy) Isopropyl) benzene, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, n-butyl-4,4-bis (t-butylperoxy) valerate, benzoyl peroxide, p- Those that generate radicals such as chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, t-butylperoxybenzoate, t-butylperoxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, t-butylcumyl peroxide If

The compounding amount of the organic peroxide is 10 to 1000 ppm with respect to the total of the resin components ((a) + (b) + (c)).
It is particularly preferably 50 to 800 ppm.

(2) Others The polyolefin composition of the present invention has other additives for the purpose of modification, such as fillers, heat stabilizers, antioxidants, light stabilizers, flame retardants, plasticizers, An antistatic agent, a release agent and the like can be added as appropriate.

[5] Production Method The polyolefin composition of the present invention can be obtained by mixing the above-mentioned components by various blending methods. Examples of the blending method include blending by multistage polymerization, post-reactor blending, powder blending, pellet blending, dry blending, and the like.
The above-mentioned (a) component, (b) component and (c) component are respectively polymerized, these powders are mixed in-line at a predetermined mixing ratio, and after blending the above-mentioned various additives as necessary,
Using an extruder such as a single-screw extruder or a twin-screw extruder, 170-26
It is preferably produced by so-called post-reactor blending, which is melt-kneading and pelletizing at 0 ° C, preferably 180 to 230 ° C. In some cases, the (a) component,
The components (b) and (c) may be mixed by a reactor blend.

[0038]

In the present invention, in the composition of propylene-ethylene block copolymer and polyethylene, the ratio of melt viscosity in the range of molding shear rate to the propylene-ethylene block copolymer is within a predetermined range. Two types of polyethylene, polyethylene and another polyethylene having a larger melt index than the polyethylene, are used, and the melt flow rate of the propylene-ethylene block copolymer and the total content of the two types of polyethylene are used. Since the compounding ratios of the respective components are set so that and satisfy the predetermined relational expression, the resulting composition retains good impact resistance and mechanical strength, and has impact whitening resistance, molding And the matte effect on the surface of the molded product are improved.

The reason why such an effect is obtained is not always clear, but it is presumed that it is due to the following actions (1) to (3).

(1) By mixing polyethylene with a propylene-ethylene block copolymer having a high melt viscosity at a molding temperature by a specific value, the polyethylene forms a domain due to surface tension between phases, and the domain is A layered structure is not formed even by the shearing force at the time of molding, and it is solidified into a spherical shape on the surface of the molded product, and the surface smoothness is lost.

(2) By blending the propylene-ethylene block copolymer and polyethylene so that the melt flow rate of the propylene-ethylene block copolymer and the blending amount of polyethylene satisfy a predetermined relational expression, The area of the interface between the matrix phase of the propylene-ethylene block copolymer and the matrix phase of polyethylene is increased, which improves the impact resistance per unit volume of the composition. (3) By blending two types of polyethylenes having different melt index values, the moldability can be improved without impairing the impact whitening resistance and the matting effect.

[0042]

The present invention will be described in more detail by the following examples. The following resins and talc were used as raw materials.

[1] Propylene-ethylene block copolymer BPP-1 [BJ540A manufactured by Tonen Kagaku KK, ethylene content 7.5% by weight, MFR _PP (230 ° C., 2.16 kg load) 4
0 g / 10 min, log (MFR _PP ) = 1.602, melt viscosity measured by rotational viscometer: [η _{100 (a)} ] ( ₁₀₀ rad / sec and
210 ° C.) = 2000, [η _{500 (a)} ] ( ₅₀₀ rad / sec and 210 ° C.) = 900, multistage polymer] BPP-2 [XJ580 Tonen Kagaku KK, ethylene content 2.8% by weight, MFR _PP (230 ℃, 2.16kg load) 80
g / 10 min, log (MFR _PP ) = 1.903, melt viscosity measured by rotational viscometer: [η _{100 (a)} ] ( ₁₀₀ rad / sec and 21
At 0 ° C) = 1050, [η _{500 (a)} ] ( ₅₀₀ rad / sec and
(At 210 ° C.) = 600, multi-stage polymerized product) BPP-3 [XJ520 manufactured by Tonen Chemical Co., Ltd., ethylene content 4.0% by weight, MFR _PP (230 ° C., 2.16 kg load) 21
g / 10 minutes, log (MFR _PP ) = 1.322, melt viscosity measured by rotational viscometer: [η _{100 (a)} ] ( ₁₀₀ rad / sec and 21
At 0 ° C) = 3000, [η _{500 (a)} ] ( ₅₀₀ rad / sec and
(At 210 ° C) = 950, multistage polymerized product)

[2] First polyethylene PE-b1 [J6331 Tonen Chemical Co., Ltd., density 0.
955 g / cm ³ , melt index (190 ℃, 2.16 kg load) 30 g / 10 minutes] PE-b2 [J6170 Tonen Chemical Co., Ltd., density 0.
961 g / cm ³ , melt index (190 ℃, 2.16 kg load) 7.5 g / 10 minutes]

[3] Second polyethylene PE-c1 [B6011 Tonen Chemical Co., Ltd., density 0.
954 g / cm ³ , melt index (190 ° C, 2.16 kg load) 0.25 g / 10 minutes, melt viscosity measured by rotational viscometer: [η _{100 (c)} ] (at ₁₀₀ rad / sec and 210 ° C) =
13500, [η _{500 (c)} ] (at ₅₀₀ rad / sec and 210 ° C.) = 4200] PE-c2 [Y6111 Tonen Chemical Co., Ltd., density 0.
953 g / cm ³ , melt index (190 ℃, 2.16 kg load) 1.2 g / 10 min, melt viscosity measured by rotational viscometer: [η _{100 (c)} ] (at ₁₀₀ rad / sec and 210 ℃) =
10200, [η _{500 (c)} ] (at ₅₀₀ rad / sec and 210 ° C) = 6000] PE-c3 [J6211 Tonen Chemical Co., Ltd., density 0.
957 g / cm ³ , melt index (190 ℃, 2.16 kg load) 12 g / 10 min, melt viscosity measured by rotational viscometer:
[Η _{100 (c)} ] (at ₁₀₀ rad / sec and 210 ℃) = 250
0, [η _{500 (c)} ] (at ₅₀₀ rad / sec and 210 ℃) = 2
000)

Examples 1 to 4 and Comparative Examples 1 to 7 Propylene-ethylene block copolymers (BPP-1 to BPP-3) and the first polyethylene (PE-b1,
PE-b2), second polyethylene (PE-c1 to PE-c3), talc (Fuji Talc Co., Ltd., Micron White 5000A),
An antistatic agent (HS-12, manufactured by Kao Corporation) and an organic peroxide (Perhexa25B, manufactured by NOF CORPORATION) are dry blended with a super mixer, and then a twin-screw extruder is used.
(65mmφ), 230 ℃, screw rotation speed 200r
The mixture was kneaded at pm to obtain pellets of the composition.

Weight ratio of the second polyethylene to the first polyethylene in the above composition ((PE-c) / (PE-b))
The value of was calculated. The results are shown in Table 1 together with the composition.

Further, from the value of log (MFR _PP ) of the propylene-ethylene block copolymer (BPP-1 to BPP-3) and the contents of the first and second polyethylenes, the following formula (I): ( log (MFR _PP )) / V _PE ... (I) (wherein, MFR _PP represents the value of the melt flow rate of BPP (unit: g / 10 minutes), V _PE represents propylene-ethylene block copolymer) And the sum of the first and second polyethylene
The value of the total content of the first and second polyethylenes (units are weight% respectively) when 100% by weight was calculated. The results are shown in Table 1 together with the composition.

Further, the propylene-ethylene block copolymer (BPP-1 to BPP-3) and the second polyethylene.
Regarding (PE-c1 to PE-c3), the melt viscosity ratio R ₁₀₀ ([η
_{100 (c)]} / [eta _{100 (a)]),} R ₅₀₀ ([eta _{500 (c)]} /
[Η _{500 (a)} ]) and the following formula: (log (R ₁₀₀ / R ₅₀₀ ) +0.80) / log (MFR _PP ) ... (II) (wherein MFR _PP is the melt flow of BPP) The value of the rate (indicating the unit g / 10 minutes) was calculated. The results are shown in Table 1 together with the composition.

Next, the melt flow rate (MFR) of the obtained pellets was measured and the injection temperature was adjusted to 210 by an injection molding machine.
° C., to produce an injection pressure of 300 kg / cm ² and mold temperature of 60 ° C. with the test piece.

For the test piece thus obtained,
The whitened area, Izod impact strength, flexural modulus and Rockwell hardness were measured. The results are shown in Table 2.

Further, a test piece for measuring gloss (80 mm × 80 mm × 2 mm) was prepared in the same manner except that the injection temperature was 250 ° C. The glossiness was measured using this test piece. Second result
Shown according to the table.

Table 1 Composition (parts by weight) Example 1 Example 2 Example 3 Example 4 BPP-1 60−−60 BPP−2−60−− BPP−3−−69−PE-b1 32− 20 32 PE-b2-10 − − PE-c1 8 − 10 8 PE-c2 − 30 − − PE-c3 − − − − Talc − − 1 − Antistatic agent − − 0.4 − Peroxide (ppm) ^* − − − 50 (PE-c) / (PE-b) 0.25 3 0.5 0.25 Value of formula (I) 0.040 0.048 0.043 0.040 Melt viscosity ratio R ₁₀₀ 6.75 9.71 4.50 6.75 R ₅₀₀ 4.67 10.00 4.42 4.67 Value of formula (II) 0.60 0.41 0.62 0.60 Note) *: Addition amount (unit is ppm) based on the total resin component (+ talc).

Table 1 (Continued) Composition (parts by weight) Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 BPP-1 59 60 35 60 BPP-2 --- BPP-3 --- PE -B1 37 8 35 10 PE-b2 --- PE-c1 3 32 30 -PE-c2 --- PE-c3 --- 30 Talc 1 --- Peroxide (ppm) ^* 50 --- (PE-c) / (PE-b) 0.08 4 0.86 3 Value of formula (I) 0.040 0.040 0.025 0.048 Melt viscosity ratio R ₁₀₀ 6.75 6.75 6.75 1.25 R ₅₀₀ 4.67 4.67 4.67 2.22 Value of formula (II) 0.60 0.60 0.60 0.34 Note) *: Addition amount (unit is ppm) relative to the total of resin component + talc.

[0055]

Table 2 Physical Properties Example 1 Example 2 Example 3 Example 4 M FR ⁽¹⁾ 28 35 19 31 Whitening area ⁽²⁾ 113 95 130 86 Izod impact strength (notched) ⁽³⁾ 23 ℃ 4.5 5.4 7.8 5.0 Flexural modulus ⁽⁴⁾ 12100 14500 10500 11600 Rockwell hardness ⁽⁵⁾ 80 85 72 75 Gloss ⁽⁶⁾ 80 63 78 76

Table 2 (continued) Physical Properties Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 M F R ⁽¹⁾ 30 9 15 35 Whitening Area ⁽²⁾ 105 138 Less than 20 95 Izod Impact Strength (with notch) ) ⁽³⁾ 23 ℃ 4.2 9.8 8.6 4.6 Flexural modulus ⁽⁴⁾ 12500 10700 9600 14500 Rockwell hardness ⁽⁵⁾ 80 76 67 85 Gloss ⁽⁶⁾ 88 26 35 91

[0058]

(1) MFR: 230 ° C., 21 according to ASTM D1238
It was measured under a load of 60 g (unit: g / 10 minutes). (2) Whitening area: Using a DuPont Impact Tester,
A 7.7 mmφ hammer was used to drop a 500 g weight from a height of 50 cm, and the whitening area was measured with an image analyzer when a sample of 80 mm × 80 mm × 2 mm in thickness was placed under the hammer (the unit is mm ² ). . (3) Izod impact strength: Measured according to JIS K7110 at 23 ° C with a notch (unit is kgf-cm / cm). (4) Flexural modulus: Measured according to JIS K7203 (Unit: kg
f / cm ² ). (5) Rockwell hardness: Measured according to JIS K7202 (unit is R). (6) Gloss: Digital variable angle gloss meter (Suga Test Instruments Co., Ltd.)
Manufactured at an angle of 60 ° (unit:%).

As is clear from Table 2, the polyolefin composition of the present invention has good moldability (MFR value), flexural modulus, Izod impact strength and Rockwell hardness, and has a whitened area. Was small and the glossiness was low. On the other hand, the compositions of the comparative examples were significantly inferior in at least one of the above physical properties.

[0061]

As described in detail above, in the present invention, in the composition of propylene-ethylene block copolymer and polyethylene, melting in the range of molding shear rate with respect to propylene-ethylene block copolymer. Polyethylene having a viscosity ratio within a predetermined range and two types of polyethylene having a larger melt index value than this polyethylene are used, and a propylene-ethylene block copolymer melt flow rate is used. Since the compounding ratios of the respective components are set so that the total content of the two types of polyethylene satisfies a predetermined relational expression, the resulting composition retains good impact resistance and mechanical strength. As it is, impact whitening resistance,
The moldability and the matte effect on the surface of the molded product are improved.

The polyolefin composition of the present invention as described above is suitable for injection molded products such as automobile interior and exterior products, home electric appliances, various miscellaneous goods, stationery and industrial products, especially large injection molded products.

Claims (1)

[Claims] (A) An ethylene content of 1 to 30% by weight and 20
~ 100 g / 10 min melt flow rate (230 ℃, 2.16 kg
Load) propylene-ethylene block copolymer
40-80% by weight, (b) a density of 0.935 g / cm ³ or more and 5-
Polyethylene having a melt index of 60 g / 10 min (190 ° C, 2.16 kg load) and (c) a density of 0.935 g / cm ³ or more and a melt index of 0.01 to 4.9 g / 10 min (19
Polyethylene ((b) and (c) with 0 ° C and 2.16kg load)
A total of 20 to 60% by weight) and a weight ratio of (c) to (b) above ((c)).
/ (B)) is 0.13 to 3.2, and the melt flow rate (MFR) of the propylene-ethylene block copolymer is
_PP , 230 ℃, 2.16kg load, unit is g / 10 minutes)
(b) + the content rate of (c) (V _PE , the unit is% by weight),
The following formula is satisfied: (log (MFR _PP )) / V _PE ≦ 0.060, and the melt flow rate MFR of (a) above.
Frequency of 100rad / sec and 210 ° C by _PP and rotational viscometer
Wherein in measured and the ratio (R ₁₀₀₎ of the melt viscosity [eta _{100 (a)]} wherein for (c) the melt viscosity of [eta _{100 (c)]} of (a), measured at a frequency 500 rad / sec and 210 ° C. The melt viscosity of (c) against the melt viscosity of (a) (η500 _(a) ) (η500 _(c) )
The ratio (R ₅₀₀ ) is expressed by the following formula: (log (R ₁₀₀ / R ₅₀₀ ) +0.80) / log (MFR
_PP ) ≧ 0.40 is satisfied, The polyolefin composition characterized by the above-mentioned.