JP2008019346A - Polypropylene resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polypropylene resin composition which can produce a molded product excellent in weld appearance and flow-mark appearance when molded into a product, is excellent in flowability and has well-balanced properties of high stiffness and impact resistance, and to provide molded products thereof. <P>SOLUTION: The polypropylene resin composition comprises 93-50 wt.% of a polypropylene resin (A) comprising a crystalline propylene/ethylene block copolymer satisfying specific requirements, 1-25 wt.% of an ethylene/alpha-olefin copolymer rubber (B) having a melt flow rate (230°C, 2.16 kg load) of 0.05-1 g/10 min, 1-25 wt.% of an ethylene-alpha-olefin copolymer rubber (C) having a melt flow rate (230°C, 2.16 kg load) of 2-20 g/10 min, and 5-18 wt.% of an inorganic filler (D). The molded product obtained from the same is also provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polypropylene resin composition and a molded body comprising the same. More specifically, when formed into a molded product, a polypropylene-based resin that can provide a molded product with excellent weld appearance and flow mark appearance, and has excellent fluidity and a good balance between high rigidity and impact resistance. The present invention relates to a composition and a molded article comprising the composition.

  Polypropylene-based resin compositions are materials that are excellent in rigidity, impact resistance, and the like, and are therefore used in a wide range of applications as molded bodies such as automobile interior and exterior materials and electrical component boxes.

  For example, in JP-A-9-71711, as a propylene-based resin composition having moldability, mechanical strength balance and paintability, a crystalline propylene homopolymer portion and an ethylene content are 20 to 80% by weight. A propylene / ethylene block copolymer containing an ethylene / propylene random copolymer part and having a melt flow rate (MFR) of 25 to 140 g / 10 min, and an MFR of 0.5 to 15 g / 10 min, A propylene resin composition comprising an ethylene / α-olefin copolymer having a fraction of 55 to 70% and talc is described.

  JP-A-2000-26697 also discloses a crystalline polypropylene homopolymer portion and an ethylene content for the purpose of improving low gloss and weld appearance as well as injection molding processability and balance of physical properties, and for commercialization without coating. Is 30% by weight or more, and a propylene / ethylene-block copolymer containing an ethylene / propylene / random copolymer part having a weight average molecular weight of 200,000 to 1,000,000, and an MFR of 0.05 Propylene resin comprising ethylene / α-olefin copolymer rubber or ethylene / α-olefin / diene copolymer rubber, talc, and high density polyethylene having an MFR of 11 g / 10 min or more. A composition is described.

  JP-A-2000-178389 discloses that the propylene homopolymer portion has an MFR of 100 g / 10 min or more for the purpose of improving fluidity, low-temperature impact resistance, appearance, and moldability. A propylene / ethylene block copolymer having an MFR of 55 to 200 g / 10 minutes for the whole polymer, and an ethylene / α-olefin copolymer having an MFR of less than 0.9 g / 10 minutes and a comonomer content of 28% by weight or more. A polypropylene resin composed of polymer rubber and talc is described.

JP-A-9-71711 JP 2000-26697 A JP 2000-178389 A

  However, even if the polypropylene resin composition described in the above publication is used, further improvements are required in the field of automotive interior and exterior parts where higher quality is desired. Therefore, improvement in the fluidity and balance between rigidity and impact resistance is required, and improvement in the weld appearance and flow mark appearance is required for the molded body.

  Under such circumstances, the object of the present invention is to obtain a molded product having an excellent weld appearance and flow mark appearance when formed into a molded product, and has excellent fluidity, high rigidity, and good impact resistance. An object of the present invention is to provide a polypropylene-based resin composition having a balance and a molded body comprising the same.

As a result of intensive studies, the present inventor has found that the present invention can solve the above problems, and has completed the present invention.
That is, the present invention
Polypropylene resin (A) 93-50 wt%,
It contains an α-olefin having 4 to 12 carbon atoms and ethylene, a density of 0.850 to 0.870 g / cm ³ , and a melt flow rate (230 ° C., 2.16 kg load) of 0.05 to 1 g / 10 minutes. 1 to 25% by weight of ethylene-α-olefin copolymer rubber (B),
It contains an α-olefin having 4 to 12 carbon atoms and ethylene, has a density of 0.850 to 0.870 g / cm ³ , and a melt flow rate (230 ° C., 2.16 kg load) of 2 to 20 g / 10 minutes. 1 to 25% by weight of ethylene-α-olefin copolymer rubber (C),
A polypropylene resin composition containing an inorganic filler (D) of less than 5 to 18% by weight (provided that the total amount of the polypropylene resin composition is 100% by weight),
The polypropylene resin (A) is a crystalline propylene-ethylene block copolymer (A-1) that satisfies the following requirements (1), (2), (3), and (4): The present invention relates to a polypropylene resin composition which is a polymer mixture (A-3) containing a polymer (A-1) and a crystalline propylene homopolymer (A-2).
Requirement (1):
The block copolymer (A-1) is a crystalline propylene-ethylene block copolymer containing 55 to 90% by weight of a crystalline polypropylene portion and 10 to 45% by weight of a propylene-ethylene random copolymer portion. (However, the total amount of the block copolymer is 100% by weight).
Requirement (2):
The crystalline polypropylene portion of the block copolymer (A-1) is
Propylene homopolymer, or
A copolymer of propylene and at least one olefin selected from the group consisting of ethylene and an α-olefin having 4 or more carbon atoms;
When the crystalline polypropylene portion is a copolymer of propylene and at least one olefin selected from the group consisting of ethylene and an α-olefin having 4 or more carbon atoms, ethylene and an α-olefin having 4 or more carbon atoms The content of at least one olefin selected from the group consisting of 1 mol% or less (provided that at least one olefin selected from the group consisting of ethylene and an α-olefin having 4 or more carbon atoms and propylene) The total amount of copolymer is 100 mol%).
Requirement (3):
The ratio (propylene / ethylene (weight / weight)) of propylene and ethylene contained in the propylene-ethylene random copolymer portion of the block copolymer (A-1) is 70/30 to 50/50. It is.
Requirement (4):
The intrinsic viscosity [η] _EP-A-1 of the propylene-ethylene random copolymer portion of the block copolymer (A-1) is 4 to 5.5 dl / g or less.

  According to the present invention, it is possible to obtain a polypropylene resin composition having excellent fluidity and a good balance between high rigidity and impact resistance, and a molded article excellent in weld appearance and flow mark appearance.

  The polypropylene-based resin composition of the present invention comprises polypropylene resin (A) 93 to 50% by weight, ethylene-α-olefin copolymer rubber (B) 1 to 25% by weight, and ethylene-α-olefin copolymer rubber. (C) A polypropylene resin composition containing 1 to 25% by weight and an inorganic filler (D) of less than 5 to 18% by weight (however, the total amount of the polypropylene resin composition is 100% by weight). .

  The polypropylene resin (A) contains a crystalline propylene-ethylene block copolymer (A-1) or the block copolymer (A-1) and a crystalline propylene homopolymer (A-2). It is a polymer mixture (A-3).

  The block copolymer (A-1) is a crystalline propylene-ethylene block copolymer containing 55 to 90% by weight of a crystalline polypropylene portion and 10 to 45% by weight of a propylene-ethylene random copolymer portion. (Requirement (1), provided that the total amount of the block copolymer is 100% by weight).

  Preferably, it is a block copolymer containing 65 to 90% by weight of a crystalline polypropylene portion and 10 to 35% by weight of a propylene-ethylene random copolymer portion, and more preferably 70 to 85% by weight of a crystalline polypropylene portion. %, And a block copolymer containing 15 to 30% by weight of a propylene-ethylene random copolymer portion.

  When the crystalline polypropylene portion is less than 55% by weight (that is, when the propylene-ethylene random copolymer portion exceeds 45% by weight), the rigidity and hardness are decreased, and the melt flow rate (MFR) is sufficiently decreased. If the crystalline polypropylene portion exceeds 90% by weight (that is, the propylene-ethylene random copolymer portion is less than 10% by weight), toughness and impact resistance are reduced. Sometimes.

The crystalline polypropylene portion of the block copolymer (A-1) is
Propylene homopolymer, or
A copolymer of propylene and at least one olefin selected from the group consisting of ethylene and an α-olefin having 4 or more carbon atoms;
When the crystalline polypropylene portion is a copolymer of propylene and at least one olefin selected from the group consisting of ethylene and an α-olefin having 4 or more carbon atoms, ethylene and an α-olefin having 4 or more carbon atoms The content of at least one olefin selected from the group consisting of 1 mol% or less (provided that at least one olefin selected from the group consisting of ethylene and an α-olefin having 4 or more carbon atoms and propylene) The total amount of copolymer is 100 mol%).

  When the crystalline polypropylene portion of the block copolymer (A-1) is a copolymer of propylene and at least one olefin selected from the group consisting of ethylene and an α-olefin having 4 or more carbon atoms. When the content of at least one olefin selected from the group consisting of ethylene and an α-olefin having 4 or more carbon atoms exceeds 1 mol%, rigidity, heat resistance or hardness may be lowered.

The crystalline polypropylene portion of the block copolymer (A-1) is preferably a propylene homopolymer from the viewpoint of rigidity, heat resistance or hardness, and more preferably an isopropylene measured by ¹³ C-NMR. A propylene homopolymer having a tactic pentad fraction of 0.97 or more. More preferably, it is a propylene homopolymer having an isotactic pentad fraction of 0.98 or more.

The isotactic pentad fraction is defined as A.I. The method described in Macromolecules, 6, 925 (1973) by Zambelli et al., Ie isotactic linkage in pentad units in a polypropylene molecular chain measured using ¹³ C-NMR, in other words propylene monomer units Is the fraction of propylene monomer units at the center of a chain of five consecutive meso-bonded chains (however, regarding the assignment of NMR absorption peaks, it is performed based on the published Macromolecules, 8, 687 (1975)). ). Specifically, the isotactic pentad fraction is measured as the area fraction of the mmmm peak in the total absorption peak in the methyl carbon region of the ¹³ C-NMR spectrum. By this method, NPL standard material CRM No. of NATIONAL PHYSICAL LABORATORY, UK It was 0.944 when the isotactic pentad fraction of M19-14 Polypropylene PP / MWD / 2 was measured.

The intrinsic viscosity [η] _P of the crystalline polypropylene portion of the block copolymer (A-1) is preferably 0.7 from the viewpoint of improving the balance between the fluidity at the time of melting and the toughness of the molded body. It is -1.3 dl / g, More preferably, it is 0.85-1.1 dl / g.
The molecular weight distribution (Q value, Mw / Mn) measured by gel permeation chromatography (GPC) of the crystalline polypropylene portion of the block copolymer (A-1) is preferably 3 or more and less than 7. More preferably, it is 3-5.

  The ratio of propylene to ethylene content (propylene / ethylene (weight / weight)) contained in the propylene-ethylene random copolymer portion of the block copolymer (A-1) is good rigidity and impact resistance. From the standpoint of obtaining a balance of 70/30 to 50/50 (requirement (3)), preferably 65/35 to 55/45.

The intrinsic viscosity [η] _EP-A-1 of the propylene-ethylene random copolymer portion of the block copolymer (A-1) prevents generation of weld lines (excellent weld appearance), and It is 4.0 dl / g or more and 5.5 dl / g or less (requirement (4)), preferably from the viewpoint of preventing occurrence (excellent flow mark appearance) and obtaining a good balance between rigidity and impact resistance. Is 4.3 to 5.5.

  The melt flow rate (MFR) of the crystalline propylene-ethylene block copolymer (A-1) is preferably 10 to 120 g / 10 minutes, more preferably 20 from the viewpoint of improving moldability and impact resistance. ~ 53 g / 10 min.

  Examples of the method for producing the crystalline propylene-ethylene block copolymer (A-1) include (a) a solid catalyst component containing magnesium, titanium, halogen and an electron donor as essential components, and (b) an organoaluminum compound. And (c) a method of producing by a known polymerization method using a catalyst system obtained by contacting an electron donor component. Examples of the method for producing this catalyst include the methods described in JP-A-1-319508, JP-A-7-216017, JP-A-10-212319, and the like.

As a polymerization method of the crystalline propylene-ethylene block copolymer (A-1), for example,
It consists of at least two polymerization steps, and after producing the crystalline polypropylene portion in the first step, in the second step, the ethylene content is 30 wt% or more and 50 wt% or less, and the intrinsic viscosity [η] _EP is 4 And a method for producing a propylene-ethylene random copolymer component of 0.0 dl / g or more and 5.5 dl / g or less.

  Examples of the polymerization method include a bulk polymerization method, a solution polymerization method, a slurry polymerization method, and a gas phase polymerization method. These polymerization methods can be either batch type or continuous type, and these polymerization methods may be arbitrarily combined. From the viewpoint of being industrially and economically advantageous, a continuous gas phase polymerization method and a continuous bulk gas phase polymerization method are preferable.

As a more specific manufacturing method,
(1) A polymerization tank consisting of at least two tanks is arranged in series in the presence of a catalyst system obtained by contacting the solid catalyst component (a), the organoaluminum compound (b) and the electron donor component (c). Then, after producing the crystalline polypropylene portion in the first polymerization tank, the product was transferred to the second polymerization tank, and the ethylene content in the second polymerization tank was 30% by weight to 50% by weight. A method for continuously producing a propylene-ethylene random copolymer component having an intrinsic viscosity [η] _EP of 4.0 dl / g or more and 5.5 dl / g or less,
(2) A polymerization tank comprising at least four tanks is arranged in series in the presence of a catalyst system obtained by contacting the solid catalyst component (a), the organoaluminum compound (b) and the electron donor component (c). Then, after producing the crystalline polypropylene portion in the first and second polymerization tanks, the product was transferred to the third polymerization tank, and the ethylene content in the third and fourth polymerization tanks was 30% by weight. A method for continuously producing a propylene-ethylene random copolymer component having a viscosity of not less than 50% by weight and an intrinsic viscosity [η] _EP of not less than 4.0 dl / g and not more than 5.5 dl / g,
Etc.

  The amount of the solid catalyst component (a), the organoaluminum compound (b) and the electron donor component (c) used in the above polymerization method and the method of supplying each catalyst component to the polymerization tank are determined by the known method of using the catalyst. Can be determined as appropriate.

  The polymerization temperature is usually −30 to 300 ° C., preferably 20 to 180 ° C. The polymerization pressure is usually normal pressure to 10 MPa, preferably 0.2 to 5 MPa. Further, for example, hydrogen may be used as the molecular weight regulator.

  In the production of the crystalline propylene-ethylene block copolymer (A-1), preliminary polymerization may be performed by a known method before carrying out the main polymerization. As a known prepolymerization method, for example, a method of supplying a small amount of propylene in the presence of the solid catalyst component (a) and the organoaluminum compound (b) and carrying out in a slurry state using a solvent can be mentioned.

  Various additives may be added to the block copolymer (A-1) as necessary. Additives include, for example, antioxidants, ultraviolet absorbers, lubricants, pigments, antistatic agents, copper damage inhibitors, flame retardants, neutralizers, foaming agents, plasticizers, nucleating agents, anti-bubble agents, and crosslinking Agents and the like. Among these additives, it is preferable to add an antioxidant or an ultraviolet absorber in order to improve heat resistance, weather resistance, and oxidation stability.

In addition to the polymer obtained by the above production method, the block copolymer copolymer (A-1) is blended with a peroxide in the polymer obtained by the above production method, and melt-kneaded. A polymer obtained by a decomposition treatment may be used.
The intrinsic viscosity [η] _EP-A of the propylene-ethylene random copolymer portion contained in the polymer obtained by blending a peroxide, melt-kneading and decomposing is the weight obtained by decomposing. It is determined by measuring the intrinsic viscosity of the 20 ° C. xylene soluble component of the coalesced pellet.

As the peroxide, an organic peroxide is generally used, and examples thereof include alkyl peroxides, diacyl peroxides, peroxide esters, and carbonate carbonates.
Examples of alkyl peroxides include dicumyl peroxide, di-t-butyl peroxide, di-t-butylcumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane. 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3, t-butylcumyl, 1,3-bis (t-butylperoxyisopropyl) benzene, 3,6,9-triethyl- 3,6,9-trimethyl-1,4,7-triperoxonane and the like.

Examples of the diacyl peroxides include benzoyl peroxide, lauroyl peroxide, decanoyl peroxide, and the like.
Examples of the peroxide esters include 1,1,3,3-tetramethylbutylperoxyneodecanoate, α-cumylperoxyneodecanoate, t-butylperoxyneodecanoate, and t-butyl. Peroxyneoheptanoate, t-butylperoxypivalate, t-hexylperoxypivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, t-amylperoxyl- 2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, di-t-butylperoxyhexahydroterephthalate, t-amylperoxy3,5,5 -Trimethylhexanoate, t-butyl peroxy 3,5,5-trimethylhexanoate, t-butyl peroxy Oxyacetate, t- butyl peroxybenzoate, di - butylperoxy trimethyl Adi adipate, and the like.

  Examples of the peroxide carbonates include di-3-methoxybutyl peroxydicarbonate, di (2-ethylhexyl) peroxydicarbonate, diisopropyl peroxycarbonate, t-butylperoxyisopropyl carbonate, and di (4-t- Butylcyclohexyl) peroxydicarbonate, dicetyl peroxydicarbonate, dimyristyl peroxydicarbonate and the like.

  The content of the propylene-ethylene random copolymer portion contained in the block copolymer (A-1) is preferably a polypropylene resin composition from the viewpoint of improving the balance between the weld appearance and the flow mark appearance. 3 to 13% by weight of the product (however, the total amount of polypropylene resin composition is 100% by weight).

  As the polypropylene resin (A) contained in the polypropylene resin composition of the present invention, the block copolymer (A-1) may be used alone, or the block copolymer (A-1) and crystals may be used. A polymer mixture (A-3) containing a functional propylene homopolymer (A-2) may be used.

  The content of the block copolymer (A-1) contained in the polymer mixture (A-3) is usually 30 to 99% by weight, and the content of the homopolymer (A-2) is The content of the block copolymer (A-1) is usually 45 to 90% by weight, and the content of the homopolymer (A-2) is 55. -10% by weight.

  The homopolymer (A-2) is preferably a homopolymer having an isotactic pentad fraction of 97% or more, and more preferably 98% or more.

  The melt flow rate (MFR: 230 ° C., load 2160 g) of the homopolymer (A-2) is usually 10 to 500 g / 10 minutes, preferably 40 to 350 g / 10 minutes.

  As a manufacturing method of the said homopolymer (A-2), the manufacturing method using the catalyst similar to the said block copolymer (A-1) is mentioned.

The content of the polypropylene resin (A) contained in the polypropylene resin composition of the present invention is 94 to 50% by weight, preferably 90 to 55% by weight, more preferably 85 to 60% by weight. (However, the total amount of the polypropylene resin composition is 100% by weight).
When the content of the polypropylene resin (A) is less than 50% by weight, the rigidity may be lowered, and when it exceeds 93% by weight, the impact strength may be lowered.

The ethylene-α-olefin copolymer rubber (B) used in the present invention contains an α-olefin having 4 to 12 carbon atoms and ethylene, and has a density of 0.850 to 0.870 g / cm ³ . This is an ethylene-α-olefin copolymer rubber having a melt flow rate (230 ° C., 2.16 kg load) of 0.05 to 1 g / 10 min.
Examples of the α-olefin having 4 to 12 carbon atoms include butene-1, pentene-1, hexene-1, heptene-1, octene-1, decene and the like, preferably butene-1, hexene-1 Octene-1.

  The content of the α-olefin contained in the copolymer rubber (B) is usually 20 to 50% by weight, preferably 24 to 50% from the viewpoint of increasing impact strength, particularly low temperature impact strength. % (However, the total amount of the copolymer rubber (B) is 100% by weight).

  Examples of the copolymer rubber include ethylene-butene-1 random copolymer rubber, ethylene-hexene-1 random copolymer rubber, and ethylene-octene-1 random copolymer rubber. Ethylene-octene-1 random copolymer rubber or ethylene-butene-1 random copolymer rubber. Moreover, you may use together at least 2 sorts of ethylene-alpha-olefin random copolymer rubber.

The density of the copolymer rubber (B) is 0.850 to 0.870 g / cm ³ , preferably 0.850 to 0.865 g / cm, from the viewpoint of obtaining a good balance between rigidity and impact resistance. cm ³ .

  The melt flow rate (230 ° C., 2.16 kg load) of the copolymer rubber (B) prevents the generation of weld lines (excellent weld appearance) and obtains a good balance between rigidity and impact resistance. From this viewpoint, it is 0.05 to 1 g / 10 minutes, and preferably 0.2 to 1 g / 10 minutes.

As a manufacturing method of the said copolymer rubber (B), the method of manufacturing by copolymerizing ethylene and various alpha olefins using a well-known catalyst and a well-known polymerization method is mentioned.
Examples of the known catalyst include a catalyst system composed of a vanadium compound and an organoaluminum compound, a Ziegler-Natta catalyst system, or a metallocene catalyst system. Known polymerization methods include a solution polymerization method, a slurry polymerization method, a high-pressure ion weight method, and the like. Examples thereof include a combination method and a gas phase polymerization method.

The content of the copolymer rubber (B) contained in the polypropylene resin composition of the present invention is 1 to 25% by weight, preferably 3 to 22% by weight, more preferably 5 to 22% by weight. % (However, the total amount of the polypropylene resin composition is 100% by weight).
When the content of the copolymer rubber (B) is less than 1% by weight, the weld appearance may be insufficient or the impact strength may decrease. When the content exceeds 25% by weight, the rigidity decreases. There is.

The ethylene-α-olefin copolymer rubber (C) used in the present invention contains an α-olefin having 4 to 12 carbon atoms and ethylene, and has a density of 0.850 to 0.870 g / cm ³ . This is an ethylene-α-olefin copolymer rubber having a melt flow rate (230 ° C., 2.16 kg load) of 2 to 20 g / 10 min.
Examples of the α-olefin having 4 to 12 carbon atoms include butene-1, pentene-1, hexene-1, heptene-1, octene-1, decene and the like, preferably butene-1, hexene-1 Octene-1.

  The content of the α-olefin contained in the copolymer rubber (C) is usually 20 to 50% by weight, preferably 24 to 50% from the viewpoint of increasing impact strength, particularly low temperature impact strength. % (However, the total amount of the copolymer rubber (C) is 100% by weight).

  Examples of the copolymer rubber (C) include ethylene-butene-1 random copolymer rubber, ethylene-hexene-1 random copolymer rubber, ethylene-octene-1 random copolymer rubber, and the like. Preferred is ethylene-octene-1 random copolymer rubber or ethylene-butene-1 random copolymer rubber. Moreover, you may use together at least 2 sorts of ethylene-alpha-olefin random copolymer rubber.

The density of the copolymer rubber (C) is 0.850 to 0.870 g / cm ³ , preferably 0.850 to 0.865 g / cm, from the viewpoint of obtaining a good balance between rigidity and impact resistance. cm ³ .

  The melt flow rate (230 ° C., 2.16 kg load) of the copolymer rubber (C) prevents the generation of weld lines (excellent weld appearance) and obtains a good balance between rigidity and impact resistance. From the viewpoint, it is 2 to 20 g / 10 minutes, preferably 2.3 to 15 g / 10 minutes, and more preferably 2.5 to 10 g / 10 minutes.

  Examples of the method for producing the copolymer rubber (C) include the same method as the method for producing the copolymer rubber (B).

The content of the copolymer rubber (C) contained in the polypropylene resin composition of the present invention is 1 to 25% by weight, preferably 3 to 22% by weight, more preferably 5 to 20% by weight. % (However, the total amount of the polypropylene resin composition is 100% by weight).
When content of the said copolymer rubber (C) is less than 1 weight%, impact strength may fall, and when it exceeds 25 weight%, rigidity may fall.

When the total amount of the weight of the copolymer rubber (B) and the weight of the copolymer rubber (C) contained in the polypropylene resin composition of the present invention is 100% by weight, the copolymer The ratio (B _W / C _W ) between the rubber (B) content (B _W , wt%) and the copolymer rubber (C) content (C _W , wt%) is the occurrence of Weld lines. Is preferably 15/85 to 85/15 (% by weight /% by weight), and more preferably from the viewpoint of obtaining a good balance between rigidity and impact resistance. 20/80 to 45/55 (wt% / wt%).

  The inorganic filler (D) used in the present invention is usually used for improving the rigidity of the polypropylene resin composition. For example, calcium carbonate, barium sulfate, mica, crystalline calcium silicate, talc , Magnesium sulfate fibers, and the like. Talc or magnesium sulfate fibers are preferable. More preferred is talc. These inorganic fillers may be used in combination of at least two kinds.

  The talc used as the inorganic filler (D) is preferably pulverized hydrous magnesium silicate. The crystal structure of the hydrous magnesium silicate molecule is a pyrophyllite type three-layer structure, and talc is a stack of these structures. The talc is more preferably a flat plate obtained by finely pulverizing hydrous magnesium silicate molecular crystals to a unit layer level.

The average particle diameter of the talc is preferably 3 μm or less. Here, the average particle diameter of talc is a 50% equivalent particle diameter obtained from an integral distribution curve of a sieving method measured by suspending in a dispersion medium that is water or alcohol using a centrifugal sedimentation type particle size distribution measuring device. means that the D _50.

  The talc may be used as it is, or various known surfactants for improving the interfacial adhesion with the polypropylene resin (A) and the dispersibility in the polypropylene resin (A). The surface may be treated and used. Examples of the surfactant include silane coupling agents, titanium coupling agents, higher fatty acids, higher fatty acid esters, higher fatty acid amides, and higher fatty acid salts.

  The average fiber length of the magnesium sulfate fiber used as the inorganic filler (D) is preferably 5 to 50 μm, more preferably 10 to 30 μm. Moreover, as an average fiber diameter of a magnesium sulfate fiber, Preferably it is 0.3-2 micrometers, More preferably, it is 0.5-1 micrometer.

  The content of the inorganic filler (D) contained in the polypropylene resin composition of the present invention is 5 to less than 18% by weight, preferably 7 to 7% from the viewpoint of improving the balance between rigidity and impact strength. It is 17% by weight, more preferably 8 to 15% by weight (however, the total amount of the polypropylene resin composition is 100% by weight).

  Examples of the method for producing the polypropylene resin composition of the present invention include a method of melt-kneading each component, for example, a method using a kneader such as a single screw extruder, a twin screw extruder, a Banbury mixer, a hot roll, or the like. Can be mentioned. The kneading temperature is usually 170 to 250 ° C., and the time is usually 1 to 20 minutes. In addition, the kneading of each component may be performed simultaneously or may be performed separately.

Examples of the method of kneading each component separately include the following methods (1), (2), (3), and (4).
(1) The block copolymer (A-1) is previously kneaded and pelletized, the pellet, the copolymer rubber (B), the copolymer rubber (C), and an inorganic filler (D). A method of kneading all together.
(2) The block copolymer (A-1) is previously kneaded and pelletized, and the pellet, the homopolymer (A-2), the copolymer rubber (B), and the copolymer rubber ( A method in which C) and the inorganic filler (D) are kneaded together.
(3) A method in which the block copolymer (A-1), the copolymer rubber (B), and the copolymer rubber (C) are kneaded, and then the inorganic filler (D) is added and kneaded. .
(4) A method in which the block copolymer (A-1) and the inorganic filler (D) are kneaded, and then the copolymer rubber (B) and the copolymer rubber (C) are added and kneaded.
In the above method (3) or (4), the crystalline propylene homopolymer (A-2) may be optionally added.

  Various additives may be added to the polypropylene resin composition of the present invention as necessary. Additives include, for example, antioxidants, ultraviolet absorbers, lubricants, pigments, antistatic agents, copper damage inhibitors, flame retardants, neutralizers, foaming agents, plasticizers, nucleating agents, anti-bubble agents, and crosslinking Agents and the like. In order to improve heat resistance, weather resistance and oxidation resistance stability, it is preferable to add an antioxidant or an ultraviolet absorber.

A vinyl aromatic compound-containing rubber may be added to the polypropylene resin composition of the present invention in order to further improve the balance of mechanical properties.
Examples of the vinyl aromatic compound-containing rubber include a block copolymer composed of a vinyl aromatic compound polymer block and a conjugated diene polymer block, and the hydrogenation rate of the double bond of the conjugated diene portion is as follows. It is preferably 80% by weight or more, more preferably 85% by weight or more (provided that the total amount of double bonds contained in the conjugated diene moiety is 100% by weight).

  The molecular weight distribution (Q value) measured by the GPC (gel permeation chromatography) method of the vinyl aromatic compound-containing rubber is preferably 2.5 or less, more preferably 1 to 2.3 or less. is there.

  The content of the vinyl aromatic compound contained in the above-mentioned vinyl aromatic compound-containing rubber is preferably 10 to 20% by weight, more preferably 12 to 19% by weight (however, the vinyl aromatic compound-containing rubber) Of 100% by weight).

  The melt flow rate (MFR, JIS-K-6758, 230 ° C.) of the vinyl aromatic compound-containing rubber is preferably 0.01 to 15 g / 10 minutes, more preferably 0.03 to 13 g / 10 minutes. It is.

  Examples of the vinyl aromatic compound-containing rubber include styrene-ethylene-butene-styrene rubber (SEBS), styrene-ethylene-propylene-styrene rubber (SEPS), styrene-butadiene rubber (SBR), and styrene- Examples thereof include block copolymers such as butadiene-styrene rubber (SBS) and styrene-isoprene-styrene rubber (SIS), and block copolymers obtained by hydrogenating these block copolymers. Further, rubber obtained by reacting a vinyl aromatic compound such as styrene with ethylene-propylene-nonconjugated diene rubber (EPDM) is also exemplified. Further, at least two types of vinyl aromatic compound-containing rubbers may be used in combination.

  Examples of the method for producing the above vinyl aromatic compound-containing rubber include a method in which a vinyl aromatic compound is bonded to an olefin copolymer rubber or a conjugated diene rubber by polymerization or reaction.

The injection molded product of the present invention is an injection molded product obtained by injection molding the polypropylene resin composition of the present invention by a known injection molding method.
The use of the injection-molded product of the present invention is preferably an injection-molded product for automobiles, and examples thereof include door rims, pillars, instrument panels, and bumpers.

Hereinafter, the present invention will be described with reference to examples and comparative examples. The measuring methods of the physical properties of the polymers and compositions used in Examples and Comparative Examples are shown below.
(1) Intrinsic viscosity (unit: dl / g)
Using a Ubbelohde viscometer, reduced viscosities were measured at three concentrations of 0.1, 0.2 and 0.5 g / dl. The intrinsic viscosity is a calculation method described in “Polymer Solution, Polymer Experimental 11” (published by Kyoritsu Shuppan Co., Ltd.), page 491. That is, the reduced viscosity is plotted against the concentration, and the concentration is extrapolated to zero. Obtained by extrapolation. Measurement was performed at a temperature of 135 ° C. using tetralin as a solvent.

(1-1) Intrinsic viscosity of crystalline propylene-ethylene block copolymer (1-1a) Intrinsic viscosity of crystalline polypropylene portion: [η] _P
Crystalline polypropylene portion contained in crystalline propylene-ethylene block copolymer

The intrinsic viscosity [η] _P of the polymer propylene-ethylene block copolymer is obtained by taking out the polymer powder from the polymerization tank after the polymerization of the crystalline polypropylene portion, which is the first step, in the production of the crystalline propylene-ethylene block copolymer. Determined by measuring by the method.

(1-1b) Intrinsic viscosity of the propylene-ethylene random copolymer portion: [η] _EP
The intrinsic viscosity [η] _EP of the propylene-ethylene random copolymer portion contained in the crystalline propylene-ethylene block copolymer is the intrinsic viscosity [η] _P of the propylene homopolymer portion and the propylene-ethylene block copolymer The total intrinsic viscosity [η] _T is measured by the method of (1) above, and calculated from the following formula using the weight ratio X of the propylene-ethylene random copolymer portion to the entire propylene-ethylene block copolymer. And asked. (The weight ratio X with respect to the entire propylene-ethylene block copolymer was determined by the measuring method (2) below).
[Η] _EP = [η] _T / X− (1 / X−1) [η] _P
[Η] _P : intrinsic viscosity of the propylene homopolymer part (dl / g)
[Η] _T : intrinsic viscosity of the entire propylene-ethylene block copolymer (dl / g)

The intrinsic viscosity [η] _EP of the propylene-ethylene random copolymer portion contained in the crystalline propylene-ethylene block copolymer thermally decomposed with peroxide is a 20 ° C. xylene-soluble component obtained by the following method. The intrinsic viscosity was measured and used.
[20 ° C xylene soluble component]
After 5 g of the crystalline propylene-ethylene block copolymer is completely dissolved in 500 ml of boiling xylene, the temperature is lowered to 20 ° C. and left for 4 hours. Thereafter, this was separated by filtration to separate a 20 ° C. xylene-insoluble portion. The filtrate was concentrated and dried to evaporate xylene and further dried at 60 ° C. under reduced pressure to obtain a polymer component soluble in xylene at 20 ° C.

(2) Weight ratio of propylene-ethylene random copolymer portion to the entire propylene-ethylene block copolymer: X, and ethylene content of propylene-ethylene random copolymer portion in propylene-ethylene block copolymer: [ (C2 ') _EP ]
It calculated | required based on the report (Macromolecules 1982, 15, 1150-1152) of Kakugo et al. From the < ¹³ > C-NMR spectrum measured on condition of the following.
A sample was prepared by uniformly dissolving about 200 mg of propylene-ethylene block copolymer in 3 ml of orthodichlorobenzene in a 10 mmφ test tube, and the ¹³ C-NMR spectrum of the sample was measured under the following conditions.
Measurement temperature: 135 ° C
Pulse repetition time: 10 seconds Pulse width: 45 °
Integration count: 2500 times

(3) Melt flow rate (MFR, unit: g / 10 minutes)
The measurement was performed according to the method defined in JIS-K-6758. Unless otherwise specified, the measurement temperature was 230 ° C. and the load was 2.16 kg.

(4) Tensile test (elongation at break (UE), unit:%)
The measurement was performed according to the method specified in ASTM D638. Using a test piece formed by injection molding and having a thickness of 3.2 mm, the tensile rate was 20 mm / min, and the elongation at break (UE) was evaluated.

(5) Flexural modulus (FM, unit: MPa)
The measurement was performed according to the method defined in JIS-K-7203. Using a test piece having a thickness of 6.4 mm and a span length of 100 mm formed by injection molding, the load speed was 2.0 mm / min and the measurement temperature was 23 ° C.

(6) Izod impact strength (Izod, unit: kJ / m ² )
The measurement was performed according to the method defined in JIS-K-7110. The thickness formed by injection molding was 6.4 mm, and the measurement temperature was measured at −30 ° C. using a notched test piece that was notched after molding.

(7) Heat distortion temperature (HDT, unit: ° C)
The measurement was performed according to the method defined in JIS-K-7207. Fiber stress was measured at 1.82 kg / cm ² .

(8) Rockwell hardness (HR, R scale)
The measurement was performed according to the method defined in JIS-K-7202. It measured using the test piece which was shape | molded by injection molding and whose thickness is 3.0 mm. The measured value was displayed on the R scale.

(9) Brittle temperature (BP, unit: ° C)
It measured according to the method prescribed | regulated to JIS-K-7216. A predetermined 6.3 × 38 × 2 mm test piece was punched from a 25 × 150 × 2 mm flat plate formed by injection molding, and measurement was performed.

(10) Isotactic pentad fraction ([mmmm])
The isotactic pentad fraction is defined as A.I. The method published in Macromolecules, 6, 925 (1973) by Zambelli et al., Ie isotactic linkage in pentad units in a polypropylene molecular chain measured using ¹³ C-NMR, in other words propylene monomer units Is the fraction of propylene monomer units in the center of a chain of five consecutive meso-bonded chains. However, the assignment of the NMR absorption peak was performed based on Macromolecules, 8, 687 (1975), which was subsequently published.

Specifically, the isotactic pentad fraction was measured as the area fraction of the mmmm peak in the total absorption peak in the methyl carbon region of the ¹³ C-NMR spectrum. By this method, NPL standard material CRM No. of NATIONAL PHYSICAL LABORATORY, UK It was 0.944 when the isotactic pentad fraction of M19-14 Polypropylene PP / MWD / 2 was measured.

[Production of injection-molded body-1]
The test piece, which is an injection-molded body for evaluating physical properties of the above (4) to (7), is a molding temperature 220 ° C., a mold cooling temperature 50 ° C., and an injection time 15 using an IS150E-V type injection molding machine manufactured by Toshiba Machine. And injection molding was performed at a cooling time of 30 seconds.

(11) Manufacture of injection line for weld line and flow mark appearance evaluation A small injection molded body, which is a test piece for evaluating the occurrence of weld lines and flow marks, was prepared according to the following method.
SE180D made by Sumitomo Heavy Industries, Ltd. as the injection molding machine, 180 tons mold clamping force, 100 mm x 400 mm x 3.0 mmt as the mold, and molding was performed at a molding temperature of 220 ° C using a parallel two-point gate. The flat plate molding shown was obtained. In FIG. 1, 1 and 2 are two-point gates, 3 is a weld line, 4 is a flow mark A generated on the end face side, and 5 is a flow mark B generated in the center.

(12) Occurrence of Weld Lines Weld lines were visually observed using the flat plate formed by the method of (11). The weld line length and noticeability shown in FIG. 1 were observed. In this case, the shorter the weld line length is, the less noticeable the appearance performance is.

(13) Flow Mark Generation Situation The flow mark was visually observed using the flat plate formed by the method (11). The distance from the gate end surface where the flow mark shown in FIG. 1 starts to occur (flow mark generation position A (end surface side generation position), unit: mm) and the degree of conspicuousness were observed. In this case, the longer the flow mark generation position and the less noticeable, the better the appearance performance.

A method for synthesizing the solid catalyst component (I) used in the production of the polymers used in Examples and Comparative Examples is shown below.
(1) Solid catalyst component (I)
A 200 liter cylindrical reactor (with a stirrer having 3 pairs of stirring blades having a diameter of 0.35 m and 4 baffles having a width of 0.05 m and having a diameter of 0.5 m) was purged with nitrogen, and 54 liters of hexane, 100 g of diisobutyl phthalate, 20.6 kg of tetraethoxysilane and 2.23 kg of tetrabutoxy titanium were added and stirred. Next, 51 liters of dibutyl ether solution of butyl magnesium chloride (concentration 2.1 mol / liter) was dropped into the stirred mixture over 4 hours while maintaining the temperature in the reactor at 7 ° C. At this time, the stirring rotation speed was 150 rpm. After completion of the dropping, the mixture was stirred at 20 ° C. for 1 hour and then filtered. The obtained solid was washed with 70 liters of toluene at room temperature three times, and toluene was added to obtain a solid catalyst component precursor slurry. The solid catalyst component precursor contained Ti: 1.9% by weight, OEt (ethoxy group): 35.6% by weight, and OBu (butoxy group): 3.5% by weight. The average particle size was 39 μm, and the amount of fine powder components of 16 μm or less was 0.5% by weight. Next, toluene is extracted so that the volume of the slurry becomes 49.7 liters, and stirred at 80 ° C. for 1 hour. Thereafter, the slurry is cooled to 40 ° C. or less, and with stirring, 30 liters of tetrachlorotitanium and A mixed solution of 1.16 kg of butyl ether was added, and 4.23 kg of orthophthalic acid chloride was further added. The temperature in the reactor was set at 110 ° C. and stirred for 3 hours, followed by filtration. The obtained solid was washed with 90 liters of toluene at 95 ° C. three times. Toluene was added to form a slurry. After standing, the toluene was withdrawn so that the slurry volume was 49.7 liters. Under stirring, 15 liters of tetrachlorotitanium, 1.16 kg of dibutyl ether, 0.87 kg of diisobutyl phthalate Was added. The temperature in the reactor was set at 105 ° C. and stirred for 1 hour, followed by filtration. The obtained solid was washed twice with 90 liters of toluene at 95 ° C. Toluene was added to form a slurry, and after standing, toluene was extracted so that the volume of the slurry was 49.7 liters, and a mixed liquid of 15 liters of tetrachlorotitanium and 1.16 kg of dibutyl ether was added with stirring. The temperature in the reactor was set at 105 ° C. and stirred for 1 hour, followed by filtration. The obtained solid was washed twice with 90 liters of toluene at 95 ° C. Toluene was added to form a slurry, and after standing, toluene was extracted so that the volume of the slurry was 49.7 liters, and a mixed liquid of 15 liters of tetrachlorotitanium and 1.16 kg of dibutyl ether was added with stirring. The temperature in the reactor was set at 105 ° C. and stirred for 1 hour, followed by filtration. The obtained solid was washed with 90 liters of toluene three times at 95 ° C. and twice with 90 liters of hexane. The obtained solid component was dried to obtain a solid catalyst component. The solid catalyst component contained Ti: 2.1% by weight and phthalate ester component: 10.8% by weight. This solid catalyst component is hereinafter referred to as solid catalyst component (I).

(Polymer polymerization)
(1) Polymerization of propylene homopolymer (HPP) (1-1) Polymerization of HPP-1 In the continuous gas phase polymerization using the solid catalyst component (I), the hydrogen concentration and polymerization temperature in the system are controlled. To obtain a propylene homopolymer. The obtained polymer had an intrinsic viscosity [η] _P of 0.93 dl / g, an isotactic pentad fraction of 0.984, and a molecular weight distribution Q value (Mw / Mn) of 4.3. Moreover, MFR was 120 g / 10min.

(1-2) Polymerization of HPP-2 The polymerization was obtained by controlling the hydrogen concentration in the system and the polymerization temperature by a general solvent polymerization method using a catalyst described in JP-A-10-212319. The obtained polymer had an intrinsic viscosity [η] _P of 0.76 dl / g, an isotactic pentad fraction of 0.991, and a molecular weight distribution Q value (Mw / Mn) of 5.3. Moreover, MFR was 307 g / 10min.

(2) Polymerization of propylene-ethylene block copolymer (BCPP) (2-1) Polymerization of BCPP-1 Using the solid catalyst component (I), after the polymerization of the propylene homopolymer part in the first stage, the second In stages, the propylene-ethylene random copolymer portion was continuously polymerized by a two-stage gas phase polymerization process. In the first stage, the hydrogen concentration in the system and the polymerization temperature are controlled, and in the second stage, propylene is continuously supplied so as to keep the reaction temperature and the reaction pressure constant, and the hydrogen concentration in the gas phase part, Gas phase polymerization of the propylene-ethylene random copolymer portion was continued while supplying hydrogen and ethylene so as to keep the ethylene concentration in the gas phase portion constant. As a result of sampling and analyzing the propylene homopolymer polymerized in the first stage, the intrinsic viscosity [η] _P was 0.93 dl / g, and the stereoregularity (mmmm fraction) was 0.987. The intrinsic viscosity ([η] _Total ) of the finally obtained propylene-ethylene block copolymer was 1.64 dl / g. As a result of analysis, the propylene-ethylene random copolymer content (EP content) was 19.2% by weight, so that the intrinsic viscosity [η] of the propylene-ethylene random copolymer component (EP part) produced in the third tank was _{The EP} was 4.6 dl / g. As a result of analysis, the ethylene content in the EP part was 42% by weight. Moreover, MFR was 30 g / 10min. The analysis results of the obtained polymer are shown in Table 1.

(2-2) Polymerization of BCPP-2 The same as BCPP-1 except that the polymer shown in Table 1 was adjusted by controlling the hydrogen concentration in the gas phase, the polymerization temperature, and the ethylene / propylene concentration. It was carried out by the method. The analysis results of the obtained polymer are shown in Table 1.

(2-3) Polymerization of BCPP-3 Similar to BCPP-1 except that the hydrogen concentration in the gas phase, the polymerization temperature, and the ethylene / propylene concentration were controlled so as to obtain the polymers shown in Table 1. It was carried out by the method. The analysis results of the obtained polymer are shown in Table 1.

(2-4) Polymerization of BCPP-4 After using the catalyst described in JP-A-10-212319 to polymerize the propylene homopolymer part in the first stage, the propylene-ethylene random copolymer part is polymerized in the second stage. Polymerized in a continuous two-stage solvent polymerization process. The propylene-ethylene block copolymer having the following structure was obtained by controlling the hydrogen concentration, polymerization temperature, and ethylene / propylene concentration in the system. As a result of sampling and analyzing the propylene homopolymer polymerized in the first stage, the intrinsic viscosity [η] _P was 0.80 dl / g, and the stereoregularity (mmmm fraction) was 0.991. The intrinsic viscosity ([η] _Total ) of the finally obtained propylene-ethylene block copolymer was 1.39 dl / g. As a result of the analysis, the propylene-ethylene random copolymer content (EP content) was 10% by weight. Therefore, the intrinsic viscosity [η] _EP of the propylene-ethylene random copolymer component (EP part) produced in the third tank was It was 6.7 dl / g. As a result of analysis, the ethylene content in the EP part was 40% by weight. Moreover, MFR was 88 g / 10min. The analysis results of the obtained polymer are shown in Table 1.

Example 1
For 100 parts by weight of propylene-ethylene block copolymer powder (BCPP-1), 0.05 part by weight of calcium stearate (manufactured by NOF Corporation) as a stabilizer, 3,9-bis [2- {3- (3- t-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5.5] undecane (Sumilyzer GA80, manufactured by Sumitomo Chemical Co., Ltd.) After adding 0.05 part by weight and 0.05 part by weight of bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite (Ultranox U626, manufactured by GE Specialty Chemicals), granulate with an extruder. did.

As BCPP-1 pellets 40% by weight, propylene homopolymer (HPP-1) powder 14% by weight, propylene homopolymer (HPP-2) powder 14% by weight, ethylene-α-olefin copolymer rubber (B) The ethylene-butene-1 random copolymer rubber EBR-1 (density 0.861 g / cm ³ , MFR (230 ° C., 2.16 kg load) g / 10 min) was 0.46. ) 7 wt%, ethylene-octene-1 random copolymer rubber as ethylene-α-olefin copolymer rubber (C) EOR-1 (density 0.857 g / cm ³ , MFR (230 ° C., 2.16 kg load) ) G / 10 min) was 2.7. ) In an amount of 13% by weight and an inorganic filler (D) at a composition ratio of 12% by weight of talc with an average particle size of 2.7 μm, and premixed uniformly with a tumbler, Using a TEX44SS-30BW-2V type), a polypropylene resin composition was produced by kneading and extruding at an extrusion rate of 50 kg / hr, 230 ° C., and a screw rotation speed of 350 rpm.
Table 2 shows the blending ratio of each component and the evaluation results of the MFR of the polypropylene resin composition obtained by granulation, the physical properties of the injection molded product, and the weld appearance.

Example-2
BCPP-2 pellets 51% by weight pelletized in the same manner as BCPP-1 pellets, propylene homopolymer (HPP-2) powder 17% by weight, ethylene-α-olefin copolymer rubber (B) as ethylene-butene-1 Random copolymer rubber EBR-1 (density 0.861 g / cm ³ , MFR (230 ° C., 2.16 kg load) g / 10 min) was 0.46. ) 7 wt%, ethylene-octene-1 random copolymer rubber as ethylene-α-olefin copolymer rubber (C) EOR-1 (density 0.857 g / cm ³ , MFR (230 ° C., 2.16 kg load) ) G / 10 min) was 2.7. ) 13 wt%, inorganic filler (D) as a composition ratio of talc 12 wt% with an average particle diameter of 2.7 μm, the same treatment as in Example-1 was performed to measure the physical properties of MFR and injection molded product, The weld appearance of the injection molded product was evaluated. Table 2 shows the evaluation results.

Comparative Example-1
68 wt% of BCPP-3 pellets pelletized in the same manner as the BCPP-1 pellets, ethylene-butene-1 random copolymer rubber EBR-1 (density 0.861 g / as ethylene-α-olefin copolymer rubber (B)) cm ³ and MFR (230 ° C., 2.16 kg load) g / 10 min) were 0.46. ) 7 wt%, ethylene-octene-1 random copolymer rubber as ethylene-α-olefin copolymer rubber (C) EOR-1 (density 0.857 g / cm ³ , MFR (230 ° C., 2.16 kg load) ) G / 10 min) was 2.7. ) 13 wt%, inorganic filler (D) as a composition ratio of talc 12 wt% with an average particle diameter of 2.7 μm, the same treatment as in Example-1 was performed to measure the physical properties of MFR and injection molded product, The weld appearance of the injection molded product was evaluated. Table 2 shows the evaluation results.

Comparative Example-2
68 wt% of BCPP-4 pellets pelletized in the same manner as BCPP-1 pellets, ethylene-butene-1 random copolymer rubber EBR-1 (density 0.861 g / as ethylene-α-olefin copolymer rubber (B)) cm ³ and MFR (230 ° C., 2.16 kg load) g / 10 min) were 0.46. ) 7 wt%, ethylene-octene-1 random copolymer rubber as ethylene-α-olefin copolymer rubber (C) EOR-1 (density 0.857 g / cm ³ , MFR (230 ° C., 2.16 kg load) ) G / 10 min) was 2.7. ) 13 wt%, inorganic filler (D) as a composition ratio of talc 12 wt% with an average particle diameter of 2.7 μm, the same treatment as in Example-1 was performed to measure the physical properties of MFR and injection molded product, The weld appearance of the injection molded product was evaluated. Table 2 shows the evaluation results.

Comparative Example-3
BCPP-2 pellets 51% by weight pelletized in the same manner as BCPP-1 pellets, propylene homopolymer (HPP-2) powder 17% by weight, ethylene-α-olefin copolymer rubber (B) as ethylene-butene-1 Random copolymer rubber EBR-1 (density 0.861 g / cm ³ , MFR (230 ° C., 2.16 kg load) g / 10 min) was 0.46. ) 7 wt%, ethylene-butene-1 random copolymer rubber EBR-2 (density 0.870 g / cm ³ , MFR (230 ° C., 2.16 kg load) g / 10 min) was 27.6. . ) 13 wt%, inorganic filler (D) as a composition ratio of talc 12 wt% with an average particle diameter of 2.7 μm, the same treatment as in Example-1 was performed to measure the physical properties of MFR and injection molded product, The weld appearance of the injection molded product was evaluated. Table 2 shows the evaluation results.

＊１）ウエルドの目視による目立ち易さ
○：ウエルドが目立たなかった。
△：ウエルドがやや目立った。
×：ウエルドが目立った。
＊２）フローマークの目視による目立ち易さ
○：フローマークが目立たなかった。
△：フローマークがやや目立った。
×：フローマークが目立った。

* 1) Easiness of visual observation of welds ○: Welds were not conspicuous.
Δ: Weld was slightly conspicuous.
X: The weld was conspicuous.
* 2) Ease of visual recognition of the flow mark ○: The flow mark was inconspicuous.
Δ: The flow mark was slightly conspicuous.
X: The flow mark was conspicuous.

  The polypropylene resin compositions of Examples-1 and -2 that satisfy the requirements of the present invention, and molded articles comprising the same are excellent in weld appearance and flow mark appearance, excellent in fluidity, high rigidity and impact resistance. It can be seen that this has a good balance.

In Comparative Example-1, since the intrinsic viscosity [η] _EP of the propylene-ethylene random copolymer portion of the polypropylene resin does not satisfy the requirements of the present invention, the flow mark appearance and weld appearance are not sufficient, and the rigidity, toughness, It can be seen that the impact balance is not sufficient.

In Comparative Example-2, since the intrinsic viscosity [η] _EP of the propylene-ethylene random copolymer portion of the polypropylene resin does not satisfy the requirements of the present invention, the weld appearance is not sufficient, and the balance between rigidity, toughness, and impact resistance is insufficient. Is not enough.

  Comparative Example-3 shows that since the ethylene-α-olefin copolymer rubber (C) does not satisfy the requirements of the present invention, the weld appearance is not sufficient, and the balance between rigidity, toughness, and impact resistance is not sufficient. .

  The polypropylene resin composition of the present invention can be used in fields where high quality is desired, such as automobile interior and exterior parts.

The top view of the flat plate molded object for evaluating an external appearance is shown.

Explanation of symbols

1 Gate 1
2 Gate 2
3 Weld 4 Flow Mark A
5 Flow Mark B

Claims (5)

Polypropylene resin (A) 93-50 wt%,
It contains an α-olefin having 4 to 12 carbon atoms and ethylene, a density of 0.850 to 0.870 g / cm ³ , and a melt flow rate (230 ° C., 2.16 kg load) of 0.05 to 1 g / 10 minutes. 1 to 25% by weight of ethylene-α-olefin copolymer rubber (B),
It contains an α-olefin having 4 to 12 carbon atoms and ethylene, has a density of 0.850 to 0.870 g / cm ³ , and a melt flow rate (230 ° C., 2.16 kg load) of 2 to 20 g / 10 minutes. 1 to 25% by weight of ethylene-α-olefin copolymer rubber (C),
A polypropylene resin composition containing an inorganic filler (D) of less than 5 to 18% by weight (provided that the total amount of the polypropylene resin composition is 100% by weight),
The polypropylene resin (A) is a crystalline propylene-ethylene block copolymer (A-1) that satisfies the following requirements (1), (2), (3), and (4): A polypropylene resin composition which is a polymer mixture (A-3) containing a polymer (A-1) and a crystalline propylene homopolymer (A-2).
Requirement (1):
The block copolymer (A-1) is a crystalline propylene-ethylene block copolymer containing 55 to 90% by weight of a crystalline polypropylene portion and 10 to 45% by weight of a propylene-ethylene random copolymer portion. (However, the total amount of the block copolymer is 100% by weight).
Requirement (2):
The crystalline polypropylene portion of the block copolymer (A-1) is
Propylene homopolymer, or
A copolymer of propylene and at least one olefin selected from the group consisting of ethylene and an α-olefin having 4 or more carbon atoms;
When the crystalline polypropylene portion is a copolymer of propylene and at least one olefin selected from the group consisting of ethylene and an α-olefin having 4 or more carbon atoms, ethylene and an α-olefin having 4 or more carbon atoms The content of at least one olefin selected from the group consisting of 1 mol% or less (provided that at least one olefin selected from the group consisting of ethylene and an α-olefin having 4 or more carbon atoms and propylene) The total amount of copolymer is 100 mol%).
Requirement (3):
The ratio (propylene / ethylene (weight / weight)) of propylene and ethylene contained in the propylene-ethylene random copolymer portion of the block copolymer (A-1) is 70/30 to 50/50. It is.
Requirement (4):
The intrinsic viscosity [η] _EP-A-1 of the propylene-ethylene random copolymer portion of the block copolymer (A-1) is 4 to 5.5 dl / g or less. When the total of the weight of the ethylene-α-olefin copolymer rubber (B) and the weight of the ethylene-α-olefin copolymer rubber (C) is 100% by weight, the content ratio of the rubber (B) ( B _W, the content (C _W wt%) and the rubber (C), the ratio of the weight%) (B _W / C _W), is 15 / 85-85 / 15 (wt% / wt%) The polypropylene resin composition according to claim 1.   The polypropylene resin composition according to claim 1, wherein the isotactic pentad fraction of the crystalline polypropylene portion of the block copolymer (A-1) is 0.97 or more.   The polypropylene resin composition according to any one of claims 1 to 3, wherein the inorganic filler (C) is talc.   An injection-molded article comprising the polypropylene resin composition according to any one of claims 1 to 4.

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