JP5548353B2 - POLYPROPYLENE RESIN COMPOSITION, PROCESS FOR PRODUCING THE SAME, AND FOAM MOLDED BODY - Google Patents

Description

  The present invention relates to a polypropylene resin composition, a method for producing the same, and a foamed molded product.

Polypropylene is widely used in various molding fields because it is excellent in mechanical properties, chemical resistance, etc., and extremely useful in balance with economy.
Foam-molded products obtained by foaming polypropylene are used as cushioning materials, sound-absorbing materials, water-permeable drain materials, various fillers and the like in the automotive field. As a means for obtaining a polypropylene foamed molded product or a polypropylene molded foamed product, for example, a copolymer of propylene and α, ω-diene produced using a metallocene-supported catalyst, foamed into the copolymer A polypropylene resin composition containing an agent, a foam obtained by heating, melting, kneading, and foam-molding the composition, and a foam-molded body obtained by molding the foam are disclosed (Patent Document 1).

  Patent Document 2 includes (A) 50 to 95 parts by weight of polypropylene having a melt flow rate (ASTM D 1238, 230 ° C., 2.16 kg load) of 10 to 100 g / 10 minutes, and (B) amorphous or low 3 to 45 parts by weight of crystalline α-olefin copolymer and 2 to 45 parts by weight of (C) inorganic filler (the total amount of components (A), (B) and (C) is 100 parts by weight) And (D) a polypropylene resin composition obtained by melt blending 0.005 to 0.2 parts by weight of an organic peroxide, the polypropylene resin composition comprising: (i) a melt flow rate (ASTM D 1238, 230 ° C., 2.16 kg load) is 50 to 150 g / 10 min, (ii) Izod impact strength at 23 ° C. (notched; ASTM D 628) is 100 J / m or more, (i Polypropylene resin compositions are disclosed, wherein i) a tensile elongation at break (ASTM D 638) is 20% or more.

  In Patent Document 3, (A) a propylene-ethylene block copolymer having a melt flow rate (MFR) of 0.1 to 80 g / 10 minutes and an ethylene content of an amorphous part of 30% by weight or more is 50 to 100% by weight. Parts, (B) 0 to 35 parts by weight of the rubbery polymer with respect to the component (A), (C) 0 to 35 parts by weight of the inorganic filler with respect to the component (A), and (D) an organic peroxide. A polypropylene resin composition in which 0.005 to 0.2 parts by weight is blended with respect to 100 parts by weight of the total of the components (A), (B) and (C) is melt-kneaded.

In Patent Document 4, the melt flow rate (measured at 230 ° C. and a 2.16 kg load) is 70 to 120 g / 10 min, the flexural modulus is 1,300 to 4,000 MPa, and the IZOD impact strength is 30 to 100 kJ. A polypropylene resin composition that is / m ² is disclosed.

JP 2001-316510 A JP-A-10-87919 JP 11-279369 A JP 2004-307842 A

  The problem to be solved by the present invention is to provide a foamed molded product with less silver streak, a polypropylene resin composition that provides the foamed molded product, and a method for producing the same.

The above object of the present invention has been achieved by the following means.
<1> 40 to 94% by mass of a propylene polymer (A) including a propylene homopolymer (A-1) and / or a propylene-ethylene copolymer (A-2), and the following ethylene-α-olefin copolymer Resin composition containing 5 to 30% by mass of coalescence (B) and 1 to 30% by mass of inorganic filler (C) (however, the total of (A), (B) and (C) is 100% by mass A polypropylene-based resin composition characterized by containing
Ethylene-α-olefin copolymer (B): The α-olefin has 4 to 20 carbon atoms, the density is 0.85 to 0.89 g / cm ³ , and the melt flow rate (190 ° C., 2.16 kg). An ethylene-α-olefin copolymer having a load) greater than 10 g / 10 minutes and 40 g / 10 minutes or less,
<2> 40 to 94% by mass of a propylene polymer (A) including a propylene homopolymer (A-1) and / or a propylene-ethylene copolymer (A-2), and the following ethylene-α-olefin copolymer Resin composition containing 5 to 30% by mass of coalescence (B) and 1 to 30% by mass of inorganic filler (C) (however, the total of (A), (B) and (C) is 100% by mass A polypropylene-based resin composition obtained by heat treatment,
Ethylene-α-olefin copolymer (B): The α-olefin has 4 to 20 carbon atoms, the density is 0.85 to 0.89 g / cm ³ , and the melt flow rate (190 ° C., 2.16 kg). An ethylene-α-olefin copolymer having a load) greater than 10 g / 10 minutes and 40 g / 10 minutes or less,
<3> The method for producing a polypropylene resin composition according to <2>, wherein the propylene polymer (A), the ethylene-α-olefin copolymer (B), and the inorganic filler (C) are combined. A step of supplying to the melt-kneading apparatus, and a heat treatment of the resin composition containing the propylene polymer (A), the ethylene-α-olefin copolymer (B) and the inorganic filler (C) by the melt-kneading apparatus. A process for producing a polypropylene-based resin composition, comprising the step of:
<4> A foamed molded article comprising the polypropylene resin composition according to <1> or <2>.

  ADVANTAGE OF THE INVENTION According to this invention, the polypropylene resin composition which gives the said foaming molding with few silver streaks, the said foaming molding, and its manufacturing method can be provided.

The polypropylene resin composition of the present invention comprises 40 to 94% by mass of a propylene polymer (A) containing a propylene homopolymer (A-1) and / or a propylene-ethylene copolymer (A-2). Resin composition containing 5 to 30% by mass of ethylene-α-olefin copolymer (B) and 1 to 30% by mass of inorganic filler (C) (however, (A), (B) and (C) The total content is 100 mass%).
Moreover, the polypropylene resin composition of the present invention comprises 40 to 94% by mass of a propylene polymer (A) containing a propylene homopolymer (A-1) and / or a propylene-ethylene copolymer (A-2), 5-30 mass% of the following ethylene-α-olefin copolymer (B) and a resin composition (however, (A), (B) and (1) containing 1-30 mass% of inorganic filler (C) The total of C) is 100% by mass.) And is obtained by heat treatment.
The ethylene-α-olefin copolymer (B) has a carbon number of α-olefin of 4 to 20, a density of 0.85 to 0.89 g / cm ³ , and a melt flow rate (hereinafter referred to as “MFR”). It is also referred to as “.” (190 ° C., 2.16 kg load) is greater than 10 g / 10 min and not greater than 40 g / 10 min. In addition, description of "40-94 mass%" etc. which show a numerical range is synonymous with "40 mass% or more and 94 mass% or less", and description of other numerical ranges is also the same unless there is particular notice. In addition, the description such as “(190 ° C., 2.16 kg load)” is 190 ° C. and the measurement load is 2.16 kg in the measurement of the melt flow rate performed according to the method defined in JIS K7210. The same shall apply hereinafter unless otherwise specified. Hereinafter, the present invention will be described in detail.

<Propylene polymer (A)>
The polypropylene resin composition of the present invention includes a propylene polymer (A) including a propylene homopolymer (A-1) and / or a propylene-ethylene copolymer (A-2).
Examples of the propylene polymer (A) that can be used in the present invention include a propylene homopolymer (A-1) and / or a propylene-ethylene copolymer (A-2), and a propylene-α-olefin copolymer. And propylene-ethylene-α-olefin copolymers.

Examples of the propylene-ethylene copolymer (A-2) include a propylene-ethylene random copolymer (A-2-1) and a propylene-ethylene block copolymer (A-2-2).
The term “block copolymer” as used herein means a mixture of a crystalline homopolymer and a rubber component such as an ethylene-propylene copolymer (“New Polymer Production Process” (edited by Industrial Research Institute, Inc.). (1994), Chapter 5, p129) That is, in the present invention, the propylene-ethylene block copolymer (A-2-2) is a propylene homopolymer component which is a crystalline homopolymer, and a rubber component. And a propylene-ethylene random copolymer component.
Examples of the propylene-α-olefin copolymer include a propylene-α-olefin random copolymer or a propylene-α-olefin block copolymer. The propylene-α-olefin block copolymer is a mixture comprising a propylene homopolymer component and a propylene-α-olefin random copolymer component. The α-olefin in the present invention includes α-olefins having 4 or more carbon atoms.
Examples of the propylene-ethylene-α-olefin copolymer include a propylene-ethylene-α-olefin random copolymer or a propylene-ethylene-α-olefin block copolymer. The propylene-ethylene-α-olefin block copolymer is a mixture comprising a propylene homopolymer component and a propylene-ethylene-α-olefin random copolymer component.
Examples of the α-olefin used in the propylene-α-olefin copolymer and the propylene-ethylene-α-olefin copolymer include α-olefins having 4 to 20 carbon atoms such as 1-butene, 1- Examples include pentene, 1-hexene, 1-octene, and 1-decene. Two or more types of propylene polymers (A) may be used in combination.
Preferably, the polypropylene resin composition of the present invention contains a propylene homopolymer (A-1) and / or a propylene-ethylene copolymer (A-2) as a main component of the propylene polymer (A). The “main component” as used herein refers to a component that occupies 50% by mass or more, preferably 80% by mass or more, and more preferably 100% by mass of the propylene polymer (A), and the same shall apply hereinafter.

  The main component of the propylene polymer (A) is more preferably a propylene homopolymer (A-1) and a propylene-ethylene block copolymer (A-2-2) from the viewpoint of increasing rigidity, heat resistance or hardness. ) Or a propylene-ethylene block copolymer (A-2-2).

The isotactic pentad fraction measured by ¹³ C-NMR of the propylene homopolymer (A-1) is preferably 0.95 or more, more preferably 0.98 or more.
The isotactic pentad fraction measured by ¹³ C-NMR of the propylene homopolymer component of the propylene-ethylene block copolymer (A-2-2) is preferably 0.95 or more, more preferably 0.8. 98 or more.

The isotactic pentad fraction is the fraction of the propylene monomer unit at the center of the isotactic chain in the pentad unit in the propylene homopolymer molecular chain. In other words, five propylene monomer units are consecutive. It is the fraction of propylene monomer units in the meso-bonded chain (hereinafter referred to as mmmm). The method for measuring the isotactic pentad fraction is as follows. The method described by Zambelli et al., Macromolecules, 6, 925 (1973), that is, the method measured by ¹³ C-NMR (however, the assignment of the NMR absorption peak is the subsequently published Macromolecules, 8, 687 ( 1975)).

Specifically, the ratio of the mmmm peak area to the absorption peak area of the methyl carbon region measured by ¹³ C-NMR spectrum is the isotactic pentad fraction. NPL reference material CRM No. of NATIONAL PHYSICAL LABORATORY measured by this method. The isotactic pentad fraction of M19-14 Polypropylene PP / MWD / 2 was 0.944.

Intrinsic viscosity of the propylene homopolymer (A-1) measured in a tetralin solvent at 135 ° C. (same as “extreme viscosity number”), 135 of propylene-ethylene random copolymer (A-2-1) The intrinsic viscosity measured in a tetralin solvent at 135 ° C. and the intrinsic viscosity measured in a 135 ° C. tetralin solvent of the propylene homopolymer component contained in the propylene-ethylene block copolymer (A-2-2) are respectively Preferably, it is 0.6-5.0 dl / g, More preferably, it is 0.7-4.0 dl / g, More preferably, it is 0.8-2.0 dl / g.
In particular, the intrinsic viscosity (hereinafter also referred to as [η] _p ) of the propylene homopolymer component contained in the propylene-ethylene block copolymer (A-2-2) is 0.7 to 1.5 dl / g. It is preferable that it is 0.8 to 1.1 dl / g. When it is within the above numerical range, the fluidity is excellent.

Intrinsic viscosity (hereinafter also referred to as [η] _EP ) measured in a 135 ° C. tetralin solvent of the propylene-ethylene random copolymer component contained in the propylene-ethylene block copolymer (A-2-2). Is preferably 1.5 to 12.0 dl / g, more preferably 2.0 to 8.0 dl / g, still more preferably 2.5 to 6.0 dl / g. It is preferable for it to be within the above numerical value range because the fineness of the cell is increased.
The propylene-ethylene block copolymer (A-2-2) has an intrinsic viscosity (hereinafter also referred to as [η] _T ) measured in a tetralin solvent at 135 ° C. of 1.0 to 2.0 dl / g. It is preferable that it is 1.4-1.7 dl / g.

  Further, propylene homopolymer component (A-1), propylene homopolymer component contained in propylene-ethylene block copolymer (A-2-2), propylene-ethylene random copolymer (A-2-1) The molecular weight distribution (Q value, Mw / Mn) measured by gel permeation chromatography (GPC) is preferably 3 to 7, respectively. It is preferable for it to be within the above numerical value range because the amount of silver streak generated is small.

  The ethylene content of the propylene-ethylene random copolymer component contained in the propylene-ethylene block copolymer (A-2-2) is preferably 20 to 65% by mass, more preferably 25 to 50% by mass, and still more preferably. Is 30 to 45% by mass (provided that the total amount of the propylene-ethylene random copolymer component is 100% by mass). It is preferable for it to be within the above numerical value range because the amount of silver streak generated is small.

  The content of the propylene-ethylene random copolymer component contained in the propylene-ethylene block copolymer (A-2-2) is preferably 10 to 60% by mass, more preferably 10 to 40% by mass, More preferably, it is 10-25 mass%.

  The melt flow rate (MFR) of the propylene homopolymer (A-1) is preferably 0.1 to 400 g / 10 minutes, more preferably 1 to 300 g / 10 minutes. However, the measurement temperature is 230 ° C. and the load is 2.16 kg. The measurement of the melt flow rate (MFR) in the present invention is preferably performed according to the method specified in JIS K7210, and the same applies hereinafter.

The melt flow rate (MFR) of the propylene-ethylene copolymer (A-2) is preferably 0.1 to 200 g / 10 minutes, more preferably 5 to 150 g / 10 minutes, and further preferably 30 to 130 g. / 10 minutes. However, the measurement temperature is 230 ° C. and the load is 2.16 kg.
The melt flow rate (MFR) of the propylene polymer (A) is preferably 0.1 to 200 g / 10 minutes, more preferably 5 to 150 g / 10 minutes. However, the measurement temperature is 230 ° C. and the load is 2.16 kg. It is preferable for it to be within the above numerical value range because of excellent foam moldability.

The polypropylene resin composition of the present invention comprises a propylene polymer (A), an ethylene-α-olefin copolymer (B) and an inorganic filler (C) as a total of 100% by mass. 40 to 94% by mass, preferably 40 to 80% by mass, more preferably 40 to 75% by mass. When the content of the propylene polymer (A) is less than 40% by mass, the rigidity of the foamed molded product may be inferior. Moreover, when content of a propylene polymer (A) exceeds 94 mass%, it may be inferior to the impact resistance of a foaming molding.
Moreover, the compounding ratio (mass ratio) of the propylene homopolymer (A-1) and the propylene-ethylene copolymer (A-2) contained in the propylene polymer (A) is the propylene homopolymer (A-1). ): Propylene-ethylene copolymer (A-2) = 0: 100 to 70:30, preferably 0: 100 to 50:50, more preferably 8:92 to 40:60. More preferably. Within the above range, the mechanical property balance is excellent.

As a manufacturing method of the said propylene polymer (A), the method of manufacturing with a well-known polymerization method using a well-known polymerization catalyst is mentioned, for example.
Examples of the known polymerization catalyst used in the method for producing the propylene polymer (A) include (1) a solid catalyst component containing magnesium, titanium, halogen and an electron donor as essential components, and (2) organoaluminum. And a catalyst system comprising a compound and (3) an electron donor component. Examples of the method for producing this catalyst include the production methods described in JP-A-1-319508, JP-A-7-216017, JP-A-10-212319, and JP-A-2004-182876. Is mentioned.

  Examples of known polymerization methods used in the above production method include a bulk polymerization method, a solution polymerization method, a slurry polymerization method, and a gas phase polymerization method. These polymerization methods may be either batch type or continuous type, and these polymerization methods may be arbitrarily combined.

As a manufacturing method of said propylene-ethylene block copolymer (A-2-2), Preferably from said solid catalyst component (1), organoaluminum compound (2), and electron donor component (3). In the presence of a catalyst system, a polymerization tank consisting of at least two tanks is arranged in series to produce a propylene homopolymer component contained in the propylene-ethylene block copolymer (A-2-2). The above component is transferred to the next polymerization tank, and a propylene-ethylene random copolymer component is continuously produced in the polymerization tank to produce a propylene-ethylene block copolymer (A-2-2). Can be mentioned.
The amount of the solid catalyst component (1), the organoaluminum compound (2) and the electron donor component (3) used in the above production method and the method of supplying each catalyst component to the polymerization tank may be appropriately determined. .

  The polymerization temperature is preferably -30 to 300 ° C, more preferably 20 to 180 ° C. The polymerization pressure is preferably normal pressure to 10 MPa, more preferably 0.2 to 5.0 MPa. For example, hydrogen may be used as the molecular weight modifier.

  In the production of the propylene polymer (A), prepolymerization 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 (1) and the organoaluminum compound (2) and carrying out in a slurry state using a solvent can be mentioned.

<Ethylene-α-olefin copolymer (B)>
In the polypropylene resin composition of the present invention, the α-olefin has 4 to 20 carbon atoms, includes 5 to 30% by mass of the ethylene-α-olefin copolymer (B), and the ethylene-α-olefin copolymer The coalescence (B) has a density of 0.85 to 0.89 g / cm ³ , and a melt flow rate (190 ° C., 2.16 kg load) is greater than 10 g / 10 minutes and 40 g / 10 minutes or less.

  The ethylene-α-olefin copolymer (B) used in the present invention may be used alone or in combination of two or more.

  Examples of the α-olefin used in the ethylene-α-olefin copolymer (B) include α-olefins having 4 to 20 carbon atoms, such as 1-butene, 1-pentene, 1-hexene, 4-methyl. Examples include -1-pentene, 1-heptene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-eicocene. These α-olefins may be used alone or in combination of two or more. The α-olefin is preferably an α-olefin having 4 to 12 carbon atoms such as 1-butene, 1-hexene and 1-octene.

As a method for producing the ethylene-α-olefin copolymer (B), a predetermined monomer is polymerized using a metallocene catalyst by a slurry polymerization method, a solution polymerization method, a bulk polymerization method, a gas phase polymerization method, or the like. Is mentioned.
Examples of the metallocene catalyst include, for example, JP-A-3-16388, JP-A-4-268307, JP-A-9-12790, JP-A-9-87313, JP-A-11-80233, and special tables. Examples thereof include metallocene catalysts described in JP-A-10-508055.
As a method for producing the ethylene-α-olefin copolymer (B) using a metallocene catalyst, a method described in EP-A-1211287 is preferable.

The polypropylene resin composition of the present invention comprises an ethylene-α-olefin copolymer having a total of 100% by mass of the propylene polymer (A), the ethylene-α-olefin copolymer (B) and the inorganic filler (C). The coalescence (B) is contained in an amount of 5 to 30% by mass, preferably 10 to 30% by mass.
When the content of the ethylene-α-olefin copolymer (B) is less than 5% by mass, the impact resistance may be inferior. Moreover, when content of an ethylene-alpha-olefin copolymer (B) exceeds 30 mass%, it may be inferior to foam moldability.
Moreover, it is preferable that an ethylene-alpha-olefin copolymer (B) accounts for 30-100 mass% of the total amount of the ethylene-alpha-olefin copolymer contained in a polypropylene resin composition, and 50-100 mass%. More preferably. Within the above range, a molded product with less silver streak can be provided.

  The ethylene content of the ethylene-α-olefin copolymer (B) is preferably 20 to 95% by mass, more preferably 30 to 90% by mass, and the α-olefin content is preferably 80 to 5% by mass. More preferably, it is 70-10 mass%.

The density of the ethylene-α-olefin copolymer (B) is 0.85 to 0.89 g / cm ³ , preferably 0.85 to 0.88 g / cm ³ , more preferably 0.86 to 0.86. 0.88 g / cm ³ . If the density is less than 0.85 g / cm ³ , the foam moldability may be inferior. On the other hand, if it exceeds 0.89 g / cm ³ , the uniformity and fineness of the foamed cells may be inferior. Moreover, it is difficult to achieve both foam moldability and suppression of silver streak.

  The melt flow rate (190 ° C., 2.16 kg load) of the ethylene-α-olefin copolymer (B) is larger than 10 g / 10 minutes and not larger than 40 g / 10 minutes, larger than 10 g / 10 minutes, 35 g / 10 min or less is preferable. When the melt flow rate is 10 g / 10 min or less, silver streaks may occur in the obtained foamed molded article.

<Inorganic filler (C)>
The polypropylene resin composition of the present invention contains 1 to 30% by mass of the inorganic filler (C).

  As the inorganic filler (C), known ones can be used, and are not limited, but specifically, granular fillers such as glass beads, calcium carbonate, and barium sulfate, and kaolin, Plate-like fillers such as glass flakes, talc, layered silicates (bentonite, montmorillonite, smectite) and mica are mentioned, and among them, plate-like fillers are preferable. By blending a plate-like filler, a foamed molded article having an excellent flexural modulus is obtained, which is preferable. Moreover, since it is excellent in cost among plate-like fillers, talc is preferable.

As an average particle diameter of an inorganic filler (C), Preferably it is 0.01-50 micrometers, More preferably, it is 0.1-30 micrometers, More preferably, it is 0.1-5 micrometers. Here, the average particle size of the inorganic filler (C) was obtained from an integral distribution curve of a sieving method measured by suspending in a dispersion medium such as water or alcohol using a centrifugal sedimentation type particle size distribution measuring device. means that 50% equivalent particle diameter D _50.

The inorganic filler (C) may be used without treatment, and improves the interfacial adhesive strength with the polypropylene resin composition or improves the dispersibility of the inorganic filler in the polypropylene resin composition. Therefore, the surface of the inorganic filler may be used with various known silane coupling agents, titanium coupling agents, higher fatty acids, higher fatty acid esters, higher fatty acid amides, higher fatty acid salts or other surfactants. Good.
The inorganic filler (C) may be previously melt-kneaded with the propylene polymer (A) and / or the ethylene-α-olefin copolymer (B) and used as a master batch.

The polypropylene resin composition of the present invention comprises 100% by mass of the total of the propylene polymer (A), the ethylene-α-olefin copolymer (B) and the inorganic filler (C), and the inorganic filler (C). Including 1 to 30% by mass, preferably 1 to 25% by mass, and more preferably 1 to 20% by mass.
If the content of the inorganic filler (C) is less than 1% by mass, the foamed molded article may have poor rigidity. Moreover, when content of an inorganic filler (C) exceeds 30 mass%, it may be inferior to the impact resistance of a foaming molding.

<Organic peroxide (D)>
The polypropylene resin composition of the present invention is added to the total of 100 parts by mass of the propylene polymer (A), the ethylene-α-olefin copolymer (B), and the inorganic filler (C) as necessary. Further, it may be obtained by adding 2 parts by mass or less of organic peroxide (D) and heat-treating it.

  Examples of the organic peroxide (D) used in the present invention include conventionally known organic peroxides. For example, organic peroxides having a decomposition temperature of less than 120 ° C. with a half-life of 1 minute, and half-lives An organic peroxide having a decomposition temperature of 120 [deg.] C. or higher can be given.

  Examples of the organic peroxide having a decomposition temperature of less than 120 ° C. with a half-life of 1 minute include a diacyl peroxide compound and a percarbonate compound (having a structure represented by the following formula (1) in the molecular skeleton). Examples thereof include compound (I) and alkyl perester compounds (compound (II) having a structure represented by the following formula (2) in the molecular skeleton).

  As the compound (I) having the structure represented by the above formula (1), di (3-methoxybutyl) peroxydicarbonate, di (2-ethylhexyl) peroxydicarbonate, bis (4-t-butylcyclohexyl) ) Peroxydicarbonate, diisopropyl peroxydicarbonate, t-butyl peroxyisopropyl carbonate, dimyristyl peroxycarbonate and the like.

  Examples of the compound (II) having the structure represented by the above formula (2) include 1,1,3,3-tetramethylbutyl neodecanoate, α-cumylperoxyneodecanoate, and t-butylperoxy. Neodecanoate etc. are mentioned.

  Examples of the organic peroxide having a decomposition temperature of 120 ° C. or more with a half-life of 1 minute include 1,1-bis (t-butylperoxy) cyclohexane, 2,2-bis (4,4- Di-t-butylperoxycyclohexyl) propane, 1,1-bis (t-butylperoxy) cyclododecane, t-hexylperoxyisopropyl monocarbonate, t-butylperoxy-3,5,5-trimethylhexa Noate, t-butylperoxylaurate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-butylperoxyacetate, 2,2-bis (t-butylperoxy) butene, t-butyl peroxybenzoate, n-butyl-4,4-bis (t-beroxy) valerate, di-t-butylberoxyisophthalate Dicumyl peroxide, α, α′-bis (t-butylperoxy-m-isopropyl) benzene, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 1,3-bis ( t-butylperoxydiisopropyl) benzene, t-butylcumyl peroxide, di-t-butyl peroxide, p-menthane hydroperoxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne -3 and the like.

  It is preferable that the usage-amount of an organic peroxide (D) is 2 mass parts or less with respect to a total of 100 mass parts of said (A)-(C), and it is more preferable that it is 0.002-1 mass parts. Preferably, it is 0.005-0.5 mass part. It is preferable that the amount of the organic peroxide (D) used is within the above numerical range because excellent foam moldability can be obtained. In the present invention, an embodiment containing no organic peroxide (D) is also preferable.

<Additives>
The polypropylene resin composition of the present invention may contain additives as necessary, for example, neutralizers, antioxidants, light proofing agents, ultraviolet absorbers, copper damage inhibitors, lubricants, and processing. Auxiliaries, plasticizers, dispersants, antiblocking agents, antistatic agents, nucleating agents, flame retardants, foaming agents, antifoaming agents, crosslinking agents, colorants, pigments and the like can be mentioned.

<Melt flow rate of polypropylene resin composition>
The melt flow rate (MFR) (230 ° C., 2.16 kg load) of the polypropylene resin composition of the present invention is preferably 50 to 150 g / 10 minutes, and more preferably 50 to 120 g / 10 minutes. . Generation | occurrence | production of a silver streak can be effectively suppressed as it is in the range of said numerical value.

<Method for Producing Polypropylene Resin Composition>
The method for producing a polypropylene resin composition of the present invention comprises a step of supplying the propylene polymer (A), the ethylene-α-olefin copolymer (B) and the inorganic filler (C) to a melt-kneading apparatus, And a step of heat-treating the resin composition containing the propylene polymer (A), the ethylene-α-olefin copolymer (B) and the inorganic filler (C) with the melt-kneader. To do.
Moreover, an organic peroxide (D) with respect to a total of 100 mass parts of the said propylene polymer (A), the said ethylene-alpha-olefin copolymer (B), and the said inorganic filler (C) as needed. 2 parts by mass or less may be further included before the heat treatment step. For example, the organic peroxide (D) is mixed with the propylene polymer (A) and the ethylene-α-olefin copolymer. You may mix with unification | combination (B) and the said inorganic filler (C), and you may supply simultaneously to a melt-kneading apparatus.

In the present invention, the heat treatment means melt kneading.
Examples of the method for producing the polypropylene resin composition of the present invention include a method of melt-kneading each component. Examples of the apparatus used for melt kneading include a single screw extruder, a twin screw extruder, a Banbury mixer, and a hot roll.
The heat treatment temperature (melt kneading temperature) is preferably 170 to 250 ° C., and the time is preferably 20 seconds to 20 minutes. Moreover, the melt-kneading of each component may be performed simultaneously or may be performed in a divided manner. For example, it is preferable to include a step of weighing a predetermined amount of each component of the resin composition and uniformly premixing with a tumbler or the like, and a step of melt kneading the premixture.

<Foamed molded product>
The foamed molded article of the present invention is characterized by comprising the polypropylene resin composition of the present invention or the polypropylene resin composition produced by the production method of the present invention.

  The foamed molded product of the present invention is obtained by adding a foaming agent to the polypropylene resin composition of the present invention and molding.

  The foaming agent used by this invention is not specifically limited, A well-known chemical foaming agent and a physical foaming agent can be used. The addition amount of the foaming agent is preferably 0.1 to 10 parts by mass, and more preferably 0.2 to 8 parts by mass with respect to 100 parts by mass of the polypropylene resin composition of the present invention.

The chemical foaming agent may be an inorganic compound or an organic compound, or two or more kinds may be used in combination. Examples of the inorganic compound include bicarbonates such as sodium bicarbonate. Examples of the organic compound include polycarboxylic acids such as citric acid and azo compounds such as azodicarbonamide (ADCA).
Examples of the physical foaming agent include inert gases such as nitrogen and carbon dioxide, and volatile organic compounds. Among these, it is preferable to use carbon dioxide in a supercritical state, nitrogen, or a mixture thereof. Two or more kinds of physical foaming agents may be used in combination, or a chemical foaming agent and a physical foaming agent may be used in combination.

When a physical foaming agent is used, it is preferable to mix the physical foaming agent into a molten polypropylene resin composition in a supercritical state. The supercritical physical foaming agent has high solubility in the resin and can be uniformly diffused into the molten polypropylene resin composition in a short time, so the foaming ratio is high and foaming has a uniform foamed cell structure. A molded body can be obtained.
Examples of the step of mixing the physical foaming agent into the molten polypropylene resin composition include a step of injecting the physical foaming agent into the nozzle or cylinder of the injection molding apparatus.

  Specific examples of the foam molding method for the polypropylene resin composition of the present invention include known methods such as an injection foam molding method, a press foam molding method, an extrusion foam molding method, and a stampable foam molding method.

  The foamed molded product of the present invention can be made into a decorative foamed molded product by bonding a skin material by a method such as insert molding or adhesion.

A known skin material can be used as the skin material. Specific skin materials include woven fabrics, non-woven fabrics, knitted fabrics, films and sheets made of thermoplastic resins or thermoplastic elastomers. Further, a composite skin material in which sheets of polyurethane, rubber, thermoplastic elastomer or the like are laminated on these skin materials may be used.
A cushion layer can be further provided on the skin material. Examples of the material constituting the cushion layer include polyurethane foam, EVA (ethylene / vinyl acetate copolymer) foam, polypropylene foam, polyethylene foam, and the like.

<Uses of foam moldings>
Examples of the use of the foamed molded article of the present invention include automobile parts such as automobile interior parts and exterior parts, motorcycle parts, furniture and electrical product parts, etc., among which automobile parts are preferred. It is more preferable that the component is a part for use.

  Examples of automobile interior parts include instrument panels, trims, door panels, side protectors, console boxes, column covers, and the like. Examples of automobile exterior parts include bumpers, fenders, wheel covers, and the like. Examples of the parts include a cowling and a muffler cover.

Hereinafter, the present invention will be described with reference to examples and comparative examples.
In the examples or comparative examples, the following resins and additives were used.

(1) Propylene homopolymer (A-1)
It manufactured by the solvent polymerization method using the solid catalyst component prepared based on the manufacturing method of the alpha-olefin polymerization catalyst and alpha-olefin polymer of Unexamined-Japanese-Patent No. 10-212319.
MFR: 300g / 10min

(2) Propylene-ethylene block copolymer (A-2-2)
(2-1) Propylene-ethylene block copolymer (A-2-2) a
It manufactured by the solvent polymerization method using the solid catalyst component prepared based on the manufacturing method of the alpha-olefin polymerization catalyst and alpha-olefin polymer of Unexamined-Japanese-Patent No. 10-212319.
MFR: 130 g / 10 minutes Intrinsic viscosity [η] _{T of the} entire propylene-ethylene block copolymer: 1.4 dl / g
Intrinsic viscosity [η] _P of propylene homopolymer component: 0.8 dl / g
Mass ratio X of propylene-ethylene random copolymer component to the whole copolymer X: 12% by mass
Intrinsic viscosity [η] _{EP of} propylene-ethylene random copolymer component: 6.0 dl / g
Ethylene unit content of propylene-ethylene random copolymer component: 30% by mass

(2-2) Propylene-ethylene block copolymer (A-2-2) b
By a gas phase polymerization method using a solid catalyst component for α-olefin polymerization described in JP-A No. 2004-182876 and a solid catalyst component prepared in accordance with a method for producing the solid catalyst component for α-olefin polymerization Manufactured.
MFR: 60 g / 10 minutes Intrinsic viscosity [η] _{T of the} entire propylene-ethylene block copolymer: 1.55 dl / g
Intrinsic viscosity [η] _P of propylene homopolymer component: 0.89 dl / g
Mass ratio X of propylene-ethylene random copolymer component to the whole copolymer X: 13% by mass
Intrinsic viscosity [η] _{EP of} propylene-ethylene random copolymer component: 6.0 dl / g
Ethylene unit content of propylene-ethylene random copolymer component: 32% by mass

(2-3) Propylene-ethylene block copolymer (A-2-2) c
By a gas phase polymerization method using a solid catalyst component for α-olefin polymerization described in JP-A No. 2004-182876 and a solid catalyst component prepared in accordance with a method for producing the solid catalyst component for α-olefin polymerization Manufactured.
MFR: 32 g / 10 minutes Intrinsic viscosity [η] _{T of the} entire propylene-ethylene block copolymer: 1.64 dl / g
Intrinsic viscosity [η] _P of propylene homopolymer component: 1.00 dl / g
Mass ratio X of propylene-ethylene random copolymer component to the whole copolymer X: 16% by mass
Intrinsic viscosity [η] _{EP of} propylene-ethylene random copolymer component: 5.0 dl / g
Ethylene unit content of propylene-ethylene random copolymer component: 34.5% by mass

(2-4) Propylene-ethylene block copolymer (A-2-2) d
By a gas phase polymerization method using a solid catalyst component for α-olefin polymerization described in JP-A No. 2004-182876 and a solid catalyst component prepared in accordance with a method for producing the solid catalyst component for α-olefin polymerization Manufactured.
MFR: 30 g / 10 minutes Intrinsic viscosity [η] _{T of the} entire propylene-ethylene block copolymer: 1.42 dl / g
Intrinsic viscosity of propylene homopolymer component [η] _P : 1.06 dl / g
Mass ratio X of propylene-ethylene random copolymer component to the whole copolymer X: 20.5% by mass
Intrinsic viscosity [η] _{EP of} propylene-ethylene random copolymer component: 2.8 dl / g
Ethylene unit content of propylene-ethylene random copolymer component: 37% by mass

(2-5) Propylene-ethylene block copolymer (A-2-2) e
It was produced by a solvent polymerization method using a solid catalyst component described in JP-A-7-216017.
MFR: 30 g / 10 minutes Intrinsic viscosity [η] _{T of the} entire propylene-ethylene block copolymer: 1.5 dl / g
Intrinsic viscosity [η] _{P of the} propylene homopolymer component: 1.05 dl / g
Mass ratio X of propylene-ethylene random copolymer component to the whole copolymer X: 16% by mass
Intrinsic viscosity [η] _{EP of} propylene-ethylene random copolymer component: 4.0 dl / g
Ethylene unit content of propylene-ethylene random copolymer component: 45% by mass

(3) Ethylene-α-olefin copolymer (B)
(B-1) Ethylene-butene copolymer rubber Product name: CX5505 (manufactured by Sumitomo Chemical Co., Ltd.)
Density: 0.878 (g / cm ³ )
MFR (190 ° C., 2.16 kg load): 14 (g / 10 min)

(B-2) Ethylene-butene copolymer rubber Product name: A35050 (Mitsui Chemicals, Inc.)
Density: 0.863 (g / cm ³ )
MFR (190 ° C., 2.16 kg load): 35 (g / 10 min)

(B-3) Ethylene-octene copolymer rubber Product name: TAFMER A0250S (manufactured by Mitsui Chemicals, Inc.)
Density: 0.860 (g / cm ³ )
MFR (190 ° C., 2.16 kg load): 0.2 (g / 10 min)

(B-4) Ethylene-butene copolymer rubber Product name: VL800 (manufactured by Sumitomo Chemical Co., Ltd.)
Density: 0.905 (g / cm ³ )
MFR (190 ° C., 2.16 kg load): 20 (g / 10 min)

(B-5) Ethylene-octene copolymer rubber Product name: Encage 8842 (manufactured by Dow Chemical Co., Ltd.)
Density: 0.858 (g / cm ³ )
MFR (190 ° C., 2.16 kg load): 1 (g / 10 min)

(4) Talc (C)
(C-1) Product name JR-63, particle size 1.8 μm, manufactured by Kamitaruku Co., Ltd.
(C-2) Hayashi Kasei Co., Ltd. product name JR-46 Particle size 2.7 μm

(5) Talc master batch (C ')
Propylene-ethylene block copolymer (A-2-2) e-based talc masterbatch (C ′) (talc (C-2) content = 70 mass%)

(6) Organic peroxide (D)
(D-1)
Product name: Parkadox 14R-P (bis (t-butyldioxyisopropyl) benzene) manufactured by Kayaku Akzo Corporation
(D-2)
Product name: Perhexa 25B (2,5-dimethyl-2,5-di (tert-butylperoxy) hexane) manufactured by NOF Corporation

(Examples 1-8 and Comparative Examples 1 and 2)
Each component shown in Table 1 was weighed in a predetermined amount, uniformly premixed with a tumbler, and then extruded using a twin-screw kneading extruder (Tex44SS 30BW-2V type manufactured by Nippon Steel). The mixture was kneaded and extruded under the conditions of hr, screw rotation speed of 300 rpm, temperature of 200 ° C. and vent suction to produce polypropylene resin composition pellets.

Using this pellet, injection foam molding was performed using an ES2550 / 400HL-MuCell (clamping force 400 ton) injection molding machine manufactured by Engel. Nitrogen in a supercritical state was used as the blowing agent.
As a mold, the dimensions of the molded body are approximately 290 mm × 370 mm, the height is 45 mm, and the basic cavity clearance (initial plate thickness) is 1.5 mmt in a clamped state. A box shape (gate structure: direct gate) having a 6 mmt portion was used.
The cylinder temperature was set to 250 ° C. and the mold temperature was set to 50 ° C. After the mold was clamped, the injection of the polypropylene resin composition containing the foaming agent was started. The polypropylene resin composition was completely injected into the mold cavity, and then the cavity wall surface of the mold was retreated by 2.0 mm to increase the cavity to foam the polypropylene resin composition. The expanded polypropylene resin composition was further cooled and solidified to obtain a foamed molded product, and the foamed molded product was evaluated at a site 100 mm from the gate. The results are shown in Table 1.

The measurement methods of the physical properties of the resin components and polypropylene resin compositions used in Examples and Comparative Examples are shown below.
(1) Melt flow rate (MFR, unit: g / 10 minutes)
The measurement was performed according to the method defined in JIS K7210. Unless otherwise specified, the measurement temperature was 230 ° C. and the load was 2.16 kg load.

(2) Structural analysis of propylene-ethylene block copolymer (A-2-2) (2-1) Intrinsic viscosity of propylene-ethylene block copolymer (A-2-2) (2-1-a) propylene Intrinsic viscosity of homopolymer component: [η] _P
Intrinsic viscosity of the propylene homopolymer component contained in the propylene-ethylene block copolymer (A-2-2): [η] _P is a polymerization tank after the polymerization of the propylene homopolymer component, which is the first step, during its production The propylene homopolymer component was taken out from the inside, and [η] _P of the taken out propylene homopolymer component was measured in a tetralin solvent at 135 ° C.

(2-1-b) Intrinsic viscosity of propylene-ethylene random copolymer component: [η] _EP
Intrinsic viscosity of propylene-ethylene random copolymer component contained in propylene-ethylene block copolymer (A-2-2): [η] _EP is intrinsic viscosity of propylene homopolymer component: [η] _P and propylene -Intrinsic viscosity of the entire ethylene block copolymer: [η] _T was measured in a tetralin solvent at 135 ° C, respectively, and a propylene-ethylene block copolymer (A-2-2) as a propylene-ethylene random copolymer component The mass ratio to the whole was obtained by calculation from the following formula using X.
[Η] _EP = [η] _T / X − {(1 / X) −1} [η] _P
[Η] _P : intrinsic viscosity of propylene homopolymer component (dl / g)
[Η] _T : Intrinsic viscosity (dl / g) of the entire propylene-ethylene block copolymer (A-2-2)

(2-2) Mass ratio of propylene-ethylene random copolymer component to the entire propylene-ethylene block copolymer (A-2-2): X
Mass ratio of propylene-ethylene random copolymer component to the entire propylene-ethylene block copolymer (A-2-2): X is a propylene homopolymer component and propylene-ethylene block copolymer (A-2-2) The total crystal melting heat quantity was measured and calculated by the following formula. The amount of crystal melting heat was measured by suggestive scanning thermal analysis (DSC).
X = 1− (ΔHf) _T / (ΔHf) _P
(ΔHf) _T : heat of fusion of the entire propylene-ethylene block copolymer (A-2-2) (cal / g)
(ΔHf) _P : heat of fusion of propylene homopolymer component (cal / g)

(2-3) Ethylene content of propylene-ethylene random copolymer component in propylene-ethylene block copolymer (A-2-2): (C2 ′) _EP
Ethylene content of propylene-ethylene random copolymer component contained in propylene-ethylene block copolymer (A-2-2): (C2 ′) _EP is a propylene-ethylene block copolymer (A 2-2) Total ethylene content (C2 ′) _T was measured and calculated by the following formula.
(C2 ′) _EP = (C2 ′) _T / X
(C2 ′) _T : Ethylene content (mass%) of propylene-ethylene block copolymer (A-2-2) as a whole
(C2 ′) _EP : ethylene content (mass%) of propylene-ethylene random copolymer component
X: Mass ratio of propylene-ethylene random copolymer component to the entire propylene-ethylene block copolymer (A-2-2)

(3) Appearance evaluation of molded foam (silver streak)
A range of a circle having a diameter of 60 mm shown in FIG. 1 (part where silver streak was evaluated) 2 shown in FIG. 1 was visually observed in a part 100 mm away from the gate part 1 of the foamed molded article 3 made of a polypropylene resin composition obtained by foam molding. And evaluated as shown below.
○: Silver streaks on the surface of the foamed molded product cannot be confirmed visually. Δ: Silver streaks are slightly noticeable. X: Silver streaks are conspicuous.

(4) Evaluation of foam moldability When the obtained polypropylene resin composition was foam-molded, the ease of expansion of the foamed cells and the molding condition width were determined as shown below.
◯: When the cavity wall surface of the mold is retracted after the mold cavity is completely injected and filled, the foamed molded body swells according to the retracted amount of the cavity wall surface. Further, even if the time from when the mold cavity is completely injected and filled to when the cavity wall surface of the mold is retracted is extended, the foamed molded body swells in accordance with the retracted amount of the cavity wall surface.
(Triangle | delta): When a cavity wall surface is retracted, a foaming molding will swell.
X: Even if the cavity wall surface is retracted, the foamed molded product does not expand according to the retracted amount of the cavity wall surface, and the foam moldability is poor.
A case where the evaluation of foam moldability was ○ or Δ was regarded as acceptable.

It is a perspective view showing an example of the foaming molding of this invention produced in the Example.

Explanation of symbols

1: Gate part 2: Range of a circle with a diameter of 60 mm (part where silver streak was evaluated)
3: Foam molding

Claims (8)

40 to 94% by mass of a propylene polymer (A) containing a propylene homopolymer (A-1) and / or a propylene-ethylene copolymer (A-2),
5-30 mass% of the following ethylene-α-olefin copolymer (B), and
A resin composition containing 1 to 30% by mass of the inorganic filler (C) (however, the total of (A), (B) and (C) is 100% by mass) is included.
Polypropylene resin composition for foam molded articles.
Ethylene-α-olefin copolymer (B): The α-olefin has 4 to 20 carbon atoms, the density is 0.85 to 0.89 g / cm ³ , and the melt flow rate (190 ° C., 2.16 kg). Ethylene-α-olefin copolymer having a load of greater than 10 g / 10 min and not greater than 40 g / 10 min The polypropylene resin composition for foam molded articles according to claim 1, wherein the polypropylene resin composition has a melt flow rate (230 ° C, 2.16 kg load) of 50 to 150 g / 10 minutes. 40 to 94% by mass of a propylene polymer (A) containing a propylene homopolymer (A-1) and / or a propylene-ethylene copolymer (A-2),
5-30 mass% of the following ethylene-α-olefin copolymer (B), and
A resin composition containing 1 to 30% by mass of the inorganic filler (C) (provided that the total of (A), (B) and (C) is 100% by mass),
Characterized by heat treatment
Polypropylene resin composition for foam molded articles.
Ethylene-α-olefin copolymer (B): The α-olefin has 4 to 20 carbon atoms, the density is 0.85 to 0.89 g / cm ³ , and the melt flow rate (190 ° C., 2.16 kg). Ethylene-α-olefin copolymer having a load of greater than 10 g / 10 min and not greater than 40 g / 10 min The resin composition is an organic peroxidation of 2 parts by mass or less with respect to a total of 100 parts by mass of the propylene polymer (A), the ethylene-α-olefin copolymer (B), and the inorganic filler (C). The polypropylene resin composition for foam molded articles according to claim 3, further comprising a product (D). A method for producing a polypropylene resin composition for foam molded articles according to claim 3 or 4,
Supplying the propylene polymer (A), the ethylene-α-olefin copolymer (B) and the inorganic filler (C) to a melt-kneading apparatus; and
It includes a step of heat-treating the resin composition containing the propylene polymer (A), the ethylene-α-olefin copolymer (B), and the inorganic filler (C) with the melt-kneading apparatus.
The manufacturing method of the polypropylene resin composition for foaming moldings . 2 parts by mass or less of organic peroxide (D) is supplied to 100 parts by mass in total of the propylene polymer (A), the ethylene-α-olefin copolymer (B) and the inorganic filler (C). The manufacturing method of the polypropylene-type resin composition for foam molded objects of Claim 5 which further includes the process to do before the process to heat-process. It consists of the polypropylene-type resin composition for foam molded objects as described in any one of Claims 1-4, The foam molded object characterized by the above-mentioned.   The foam molded article according to claim 7, wherein the foam molded article is for automobile parts.

Images