JP2605369B2 - Polyolefin composition - Google Patents

Description

The present invention relates to a polyolefin composition containing a propylene / α-olefin block copolymer resin, and particularly to a polyolefin composition having excellent impact resistance and rigidity, and having a gate when injection-molded. The present invention relates to a polyolefin composition capable of providing a colored molded article without color unevenness called white streaks formed on the outer surface on the extension of the above.

[Conventional technology]

Propylene / ethylene block copolymer resin has strength,
Mechanical properties such as impact resistance, moldability, chemical resistance, weather resistance,
Because of its excellent heat resistance, it is used for automotive interior parts such as bumpers, instrument panels, interior trims, and other molded products. In such a propylene / ethylene block copolymer resin, a rubber component is added to further improve impact resistance in addition to the above properties, and an inorganic filler made of talc is added to improve rigidity, Pigments and the like are compounded for coloring purposes, and molded products are formed by injection molding or the like.

However, when the propylene / ethylene block copolymer resin is injection-molded, color irregularities called almost linear white stripes occur on the outer surface on the extension of the gate immediately after the gate or in a portion where the thickness changes, Hurt the appearance. Even when the color unevenness is not compounded with a rubber component, an inorganic filler, a pigment, etc., color unevenness due to a difference in gloss is formed, but becomes noticeable when a rubber component having a large molecular weight is compounded. When it is blended, it is formed as a remarkable white streak, and when it is further colored, it becomes more conspicuous especially when it is colored black, blue or grayish dark black.

The streaky color unevenness as described above is different from a flow mark formed in a ripple shape around the gate and a silver streak formed radially from the gate,
Injection molding conditions under which flow marks and silver streaks are not formed, for example, even when the flow rate of the injection resin is low, may cause formation of flow marks and silver streaks and white streaks simultaneously.

Conventionally, in order to prevent such streaky color unevenness, a polyolefin composition comprising a propylene / ethylene block copolymer and a multi-component pigment containing iron black (Japanese Patent Publication No.
No. 62-14576).

[Problems to be solved by the invention]

The object of the present invention is a propylene / α-olefin block copolymer, a modified polyolefin, a rubber component, an inorganic filler and a pigment, when injection-molding a polyolefin composition having an excellent balance of impact resistance and rigidity, An object of the present invention is to provide an improved polyolefin composition which can prevent the occurrence of streaky color unevenness.

[Means for solving the problem]

The present invention relates to 100 to 100 parts by weight of a propylene / α-olefin block copolymer resin having a propylene content of 40 to 99 mol%, 0.1 to 5 parts by weight of a modified polyolefin having an acid value of 4 mg-KOH / g or more, and Mooney viscosity ML _{1+ 4} (100 ° C) 40 ~ 120 rubber component 3 ~ 9
A polyolefin composition comprising 0 parts by weight, 1 to 100 parts by weight of an inorganic filler made of talc, and a pigment.

The propylene / α-olefin block copolymer resin of the present invention is prepared during polymerization so that the polypropylene component, the polyethylene component and / or the ethylene / propylene random copolymer component are present in a mixed state, and is commercially available. And so-called block polypropylene resins.

The propylene / α-olefin block copolymer resin in the present invention generally contains a propylene component in an amount of 40 to 99 mol%,
Preferably, it contains 70 to 90 mol%, and the remaining components are α-olefins other than propylene. And the melt flow index MF
R _{230 ° C} (ASTM D 1238, (L)) 1 to 60 g / 10 min, preferably 5 to 40 g / 10 min can be used. Examples of the α-olefin other than propylene include ethylene, butene-1, hexene-1, and 4-methylpentene-1, and ethylene is preferred.

The modified polyolefin is a polyolefin having an acid group in the molecular structure, and specific examples thereof include the following.

(I) A polymer obtained by oxidizing a polymer obtained by homo- or copolymerizing an α-olefin such as ethylene, propylene, butene-1, 4-methylpentene-1, or octene-1 to introduce a carboxyl group.

(Ii) α, β- such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, etc.
Graft polymerized unsaturated carboxylic acid or its anhydride.

(Iii) ethylene-acrylic acid copolymer, ethylene
A random copolymer of the above α-olefin such as a methacrylic acid copolymer and the above α, β-unsaturated carboxylic acid.

(Iv) A sulfonated product of the above polyolefin.

Among them, polyethylene oxide, polypropylene oxide, polybutene-1, polyolefin oxide such as ethylene oxide / α-olefin copolymer, or maleic anhydride grafted polyethylene, maleic anhydride grafted polypropylene, maleic anhydride grafted polyethylene, α Maleic anhydride grafted polyolefins such as olefin copolymers are preferred. These can be used alone or in combination of two or more.

Such a modified polyolefin preferably has an acid value of 4 mg-KOH / g or more, preferably 10 to 100 mg-KOH / g, and an intrinsic viscosity [η] (measured in decalin at 135 ° C.) of 0.04 to 2 dl / g.

The amount of the modified polyolefin is usually 0.1 to 100 parts by weight of the propylene / α-olefin block copolymer resin.
To 5 parts by weight, preferably 0.5 to 3 parts by weight. Even when injection molding is performed, generation of streak-like color unevenness is prevented by blending such a modified polyolefin.

The rubber component used in the present invention is preferably an olefin copolymer rubber, but may be another rubber.

Olefin copolymer rubber is an amorphous random elastic copolymer mainly composed of an α-olefin having 2 to 20 carbon atoms, and is composed of two or more different α-olefin copolymers and is non-crystalline. And two or more α-olefins further copolymerized with a non-conjugated diene.

The following can be exemplified as such an olefin-based copolymer rubber.

Ethylene / α-olefin copolymer rubber containing ethylene as a main component, (ethylene / α-olefin (molar ratio) = about 90/10 to 50 /
50) Ethylene / α-olefin / non-conjugated diene copolymer rubber containing ethylene as a main component, (ethylene / α-olefin (molar ratio) = about 90/10 to 50 /
50) A propylene / α-olefin copolymer rubber containing propylene as a main component, (propylene / α-olefin (molar ratio) = about 90/10 to 5)
0/50) Butene / α-olefin copolymer rubber containing butene-1 as a main component.

(Butene / α-olefin (molar ratio) = about 90/10 to 50/5
0) Examples of the above α-olefin include ethylene, propylene, butene-1, 4-methylpentene-1, hexene-1, and octene-1.

As the non-conjugated diene, dicyclopentadiene,
Hexadiene-1,4, cyclooctadiene, methylene norbornene, ethylidene norbornene and the like can be mentioned.

The Mooney viscosity ML _{1 + 4} (100 ° C) of these copolymer rubbers is
Those having 40 to 120, preferably 40 to 80 are used. When the non-conjugated diene is copolymerized, the iodine value (unsaturation degree) of the olefin copolymer rubber is preferably 16 or less.

Examples of other rubbers that can be used as the rubber component in the present invention include SBR, NBR, natural rubber, diene rubbers such as IIR, AEBS, polyisobutylene, and the like.

These rubber components are used singly or as a mixture of two or more, and are usually 3 to 90 parts by weight, preferably 5 to 40 parts by weight, based on 100 parts by weight of the propylene / α-olefin block copolymer resin. Be blended. By blending such a rubber component, impact resistance, especially at low temperatures, is improved.

Takul is used as the inorganic filler. The inorganic filler is used to impart properties such as rigidity to the polyolefin composition, and the amount thereof is usually 1 to 100 parts by weight, preferably 5 to 100 parts by weight, based on 100 parts by weight of the propylene / α-olefin block copolymer resin. 60 parts by weight.

The pigment is not particularly limited and those generally used can be used, for example, carbon black, iron black, red iron oxide, titanium oxide, cadmium yellow, cadmium red, zinc white, ultramarine, cobalt blue, calcium carbonate, titanium yellow, Inorganic pigments such as lead white, lead red, graphite, navy blue and the like, and organic pigments such as quinacridone, polyazo yellow, anthraquinone yellow, polyazo red, azo lake yellow, berylene, phthalocyanine blue, phthalocyanine green, and isoindolinone yellow. . This pigment is added for coloring a molded article, and the amount of the pigment is appropriately selected according to the intended degree of coloring, but the propylene / α-olefin block copolymer resin is used.
Usually, about 0.1 to 7 parts by weight is blended with respect to 100 parts by weight.

The composition of the present invention has an appropriate amount of another resin as desired,
Alternatively, additives such as a dispersant, an antioxidant and a lubricant can be blended.

Examples of the resin that can be blended include a polyethylene resin, an ethylene-vinyl acetate copolymer resin, and a polybutene resin. The blending of polyethylene resin shows an excellent effect in improving the balance between rigidity and impact resistance, and can be blended up to about 20 parts by weight with respect to 100 parts by weight of propylene / α-olefin block copolymer resin. .

As a method for producing the polyolefin composition according to the present invention,
A known method can be applied, and examples thereof include a method of mechanically blending the above components with an extruder, a kneader, or the like.

The polyolefin composition thus obtained is molded into a molded product by a usual molding method, but when injection-molded, a line-like uneven color such as a white streak does not occur, and the product is excellent in appearance. Becomes

〔The invention's effect〕

The polyolefin composition of the present invention is a propylene / α-olefin block copolymer resin modified polyolefin,
Since the rubber component, the inorganic filler, and the pigment are blended, a colored injection molded article which prevents generation of streaky color unevenness during injection molding and has an excellent balance between impact resistance and rigidity can be obtained.

〔Example〕

Hereinafter, examples of the present invention will be described. However, parts indicate parts by weight.

Example 1 An acid value of 30 mg-KOH / g, [η] 0.4 dl / g, based on 100 parts of a propylene / ethylene block copolymer resin (I) having a propylene content of 75 mol% and an MFR of _{230 ° C. at} 12 g / 10 minutes. Of maleic anhydride-grafted polypropylene (1 part), ethylene content 81 mol%, Mooney viscosity ML _{1 + 4} (100 ° C) 55 ethylene / propylene random copolymer rubber of 55, 10 parts of talc, and 2.2 parts of carbon black as a pigment After blending, stirring and mixing with a Henschel mixer, granulation was performed while kneading with a twin-screw extruder (CIM-50, manufactured by Nippon Steel Works, trademark). Thereafter, a plate-shaped molded sample of 120 mm × 130 mm was prepared by injection molding, and the occurrence of streak-like color unevenness (white streaks) was visually observed. Table 1 shows the results.

Examples 2 to 3 and Comparative Examples 1 to 3 Samples were prepared and observed in the same manner as in Example 1 with the compositions shown in Table 1. Table 1 shows the results.

The propylene / ethylene block copolymer (I
Table 2 shows the physical properties of I), propylene homopolymer, polyethylene oxide wax (I), polyethylene oxide wax (II), and ethylene / propylene random copolymer rubbers (I) and (II).

Example 4 100 parts of propylene / ethylene block copolymer resin (I) used in Example 1, 1 part of maleic anhydride-grafted polypropylene, MFR (ASTM D 1238 (E)) 1.1, density 0.9
When the same operation as in Example 1 was carried out with a composition of 54 parts of polyethylene resin, 10 parts of ethylene / propylene random copolymer rubber (I), 50 parts of talc and 2.2 parts of carbon black, occurrence of color unevenness was observed. Did not.

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Claims (1)

(57) [Claims] 1. A propylene / α-olefin block copolymer resin having a propylene content of 40 to 99 mol%, 100 to 100 parts by weight of a modified polyolefin having an acid value of 4 mg-KOH / g or more, 0.1 to 5 parts by weight, Mooney viscosity ML _{1 +4} (100 ° C) 40 ~ 120 rubber component 3 ~ 9
A polyolefin composition comprising 0 parts by weight, 1 to 100 parts by weight of an inorganic filler made of talc, and a pigment.