JP2010065216A - Polypropylene resin composition, production method thereof and foamed molded product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polypropylene resin composition having excellent fluidity and good mechanical property balance, to provide a production method thereof, and to provide a foamed molded product. <P>SOLUTION: The polypropylene resin composition is provided by heat-treating a resin composition which comprises 40-99 mass% propylene polymer (A), 1-60 mass% ethylene-&alpha;-olefin copolymer (B) (wherein, the total mass of (A) and (B) is 100 mass%), and a phosphite represented by formula (I) and of 0.001-5 pts.mass based on 100 pts.mass total mass of (A) and (B) and an organic peroxide (D) of 0.0001-0.5 pts.mass based on 100 pts.mass total mass of (A) and (B) and has 40-200 g/10 min MFR, and the production method of the resin composition and the foamed molded product are provided. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

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 composition for obtaining a foamed molded product of polypropylene or a polypropylene molded foamed product, for example, a copolymer comprising propylene and α, ω-diene produced using a metallocene supported catalyst, the copolymer Discloses a polypropylene-based resin composition containing a foaming agent, a foam obtained by heating, melting, kneading and foam-molding the composition, and a foam-molded body obtained by molding the foam (Patent Document 1).

  Moreover, in patent document 2, with respect to 100 mass parts of polyolefin-type resin (A), specific phosphorous acid ester (B) 0.001-5 mass parts, and organic-type peroxide (C) 0.001. A polyolefin-based resin composition obtained by heating, melting and mixing 0001 to 0.5 parts by mass is disclosed.

JP 2001-316510 A JP 2002-212347 A

  The problem to be solved by the present invention is to provide a polypropylene resin composition having a high fluidity and a good mechanical property balance, a method for producing the same, and a foamed molded article comprising the polypropylene resin composition. .

The above object of the present invention has been achieved by means described in the following <1> to <3>.
<1> 40 to 99% by mass of the propylene polymer (A) and 1 to 60% by mass of the ethylene-α-olefin copolymer (B) (however, the total mass of (A) and (B) is 100). And 0.001 to 5 parts by mass of the phosphites (C) represented by the following formula (I) with respect to 100 parts by mass of the total mass of (A) and (B) And an organic peroxide (D) obtained by heat-treating a resin composition containing 0.0001 to 0.5 parts by mass with respect to a total of 100 parts by mass of (A) and (B), A polypropylene resin composition having a melt flow rate (MFR, measurement temperature: 230 ° C., load: 2.16 kg) of 40 to 200 g / 10 minutes,

（式（Ｉ）中、Ｒ¹、Ｒ²、Ｒ⁴およびＲ⁵はそれぞれ独立に水素原子、炭素原子数１〜８のアルキル基、炭素原子数５〜８のシクロアルキル基、炭素原子数６〜１２のアルキルシクロアルキル基、炭素原子数７〜１２のアラルキル基またはフェニル基を表し、Ｒ³は水素原子または炭素原子数１〜８のアルキル基を表す。Ｘは単結合、硫黄原子もしくは−ＣＨＲ⁶−基（Ｒ⁶は水素原子、炭素数１〜８のアルキル基または炭素数５〜８のシクロアルキル基を示す。）を表す。Ａは炭素数２〜８のアルキレン基または＊−ＣＯ（Ｒ⁷）_m−基（Ｒ⁷は炭素数１〜８のアルキレン基を表し、＊は酸素原子と結合する部位であることを表し、ｍは０または１を表す。）を表す。ＹおよびＺは、いずれか一方がヒドロキシル基、炭素原子数１〜８のアルコキシ基または炭素原子数７〜１２のアラルキルオキシ基を表し、もう一方が水素原子または炭素原子数１〜８のアルキル基を表す。）

(In the formula (I), R ¹ , R ² , R ⁴ and R ⁵ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, or 6 carbon atoms. Represents an alkylcycloalkyl group having 12 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, or a phenyl group, R ³ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, X is a single bond, a sulfur atom or — CHR ⁶ — represents a group (R ⁶ represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a cycloalkyl group having 5 to 8 carbon atoms), and A represents an alkylene group having 2 to 8 carbon atoms or * —CO. (R ⁷ ) _m -group (R ⁷ represents an alkylene group having 1 to 8 carbon atoms, * represents a site bonded to an oxygen atom, and m represents 0 or 1) Y and Z is either a hydroxyl group or an alkyl group having 1 to 8 carbon atoms. A coxy group or an aralkyloxy group having 7 to 12 carbon atoms is represented, and the other represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.)

<2> 40 to 99% by mass of the propylene polymer (A) and 1 to 60% by mass of the ethylene-α-olefin copolymer (B) (however, the total mass of (A) and (B) is 100). And 0.001 to 5 parts by mass of the phosphite ester (C) represented by the above formula (I) with respect to 100 parts by mass of the total mass of (A) and (B). A step of supplying 0.0001 to 0.5 parts by mass of the organic peroxide (D) to 100 parts by mass of the total mass of (A) and (B) to the melt-kneading apparatus, and Including a step of heat-treating the resin composition containing the above (A) to (D) with a melt kneader, and a melt flow rate (MFR, measurement temperature: 230 ° C., load: 2.16 kg) is 40 to 200 g / 10 min. A method for producing a polypropylene resin composition,
<3> A foam molded article comprising the polypropylene resin composition according to <1> above or the polypropylene resin composition produced by the production method according to <2> above.

  According to the present invention, it is possible to provide a polypropylene resin composition having a high fluidity and a good mechanical property balance, a method for producing the same, and a foamed molded article comprising the polypropylene resin composition.

  The polypropylene resin composition of the present invention has a propylene polymer (A) of 40 to 99% by mass and an ethylene-α-olefin copolymer (B) of 1 to 60% by mass (however, (A) and (B ) And the phosphites (C) represented by the following formula (I) with respect to a total of 100 parts by mass of the masses of (A) and (B). A resin composition comprising 0.001 to 5 parts by mass and 0.0001 to 0.5 parts by mass of the organic peroxide (D) with respect to a total of 100 parts by mass of the mass of (A) and (B). The melt flow rate (MFR, measurement temperature: 230 ° C., load: 2.16 kg) is 40 to 200 g / 10 min.

（式（Ｉ）中、Ｒ¹、Ｒ²、Ｒ⁴およびＲ⁵はそれぞれ独立に水素原子、炭素原子数１〜８のアルキル基、炭素原子数５〜８のシクロアルキル基、炭素原子数６〜１２のアルキルシクロアルキル基、炭素原子数７〜１２のアラルキル基またはフェニル基を表し、Ｒ³は水素原子または炭素原子数１〜８のアルキル基を表す。Ｘは単結合、硫黄原子もしくは−ＣＨＲ⁶−基（Ｒ⁶は水素原子、炭素数１〜８のアルキル基または炭素数５〜８のシクロアルキル基を示す。）を表す。Ａは炭素数２〜８のアルキレン基または＊−ＣＯ（Ｒ⁷）_m−基（Ｒ⁷は炭素数１〜８のアルキレン基を表し、＊は酸素原子と結合する部位であることを表し、ｍは０または１を表す。）を表す。ＹおよびＺは、いずれか一方がヒドロキシル基、炭素原子数１〜８のアルコキシ基または炭素原子数７〜１２のアラルキルオキシ基を表し、もう一方が水素原子または炭素原子数１〜８のアルキル基を表す。）

(In the formula (I), R ¹ , R ² , R ⁴ and R ⁵ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, or 6 carbon atoms. Represents an alkylcycloalkyl group having 12 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, or a phenyl group, R ³ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, X is a single bond, a sulfur atom or — CHR ⁶ — represents a group (R ⁶ represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a cycloalkyl group having 5 to 8 carbon atoms), and A represents an alkylene group having 2 to 8 carbon atoms or * —CO. (R ⁷ ) _m -group (R ⁷ represents an alkylene group having 1 to 8 carbon atoms, * represents a site bonded to an oxygen atom, and m represents 0 or 1) Y and Z is either a hydroxyl group or an alkyl group having 1 to 8 carbon atoms. A coxy group or an aralkyloxy group having 7 to 12 carbon atoms is represented, and the other represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.)

In the present invention, the description such as “40 to 99% by mass” indicating the numerical range is synonymous with “40% by mass or more and 99% by mass or less”, and the description of other numerical ranges is the same unless otherwise specified. And
Moreover, the polypropylene resin composition of the present invention can be particularly suitably used as a polypropylene resin composition for foam molding.

<Propylene polymer (A)>
The polypropylene resin composition of the present invention preferably contains a propylene homopolymer (A-1) and / or a propylene-ethylene copolymer (A-2) as the propylene polymer (A). More preferably, it is a blend (A-1) or a mixture of a propylene homopolymer (A-1) and a propylene-ethylene copolymer (A-2).
The propylene polymer (A) that can be used in the present invention includes a propylene homopolymer (A-1), a propylene-ethylene copolymer (A-2), a propylene-α-olefin copolymer, and A propylene-ethylene-α-olefin copolymer can be exemplified.

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 propylene-ethylene block copolymer (A-2-2) is a copolymer composed of a propylene homopolymer 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 copolymer composed of 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 copolymer composed of 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 a propylene-ethylene copolymer (A-2).

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

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 polymer molecular chain. In other words, five propylene monomer units are consecutive. This is the fraction of propylene monomer units in a 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”) ([η] _P ), propylene-ethylene block copolymer (A-2) -2) propylene homopolymer component intrinsic viscosity ([η] _P ) measured in a 135 ° C. tetralin solvent, propylene-ethylene random copolymer (A-2-1) in a 135 ° C. tetralin solvent Intrinsic viscosity ([η]) measured in (1) is preferably 0.7 to 5.0 dl / g, more preferably 0.8 to 4.0 dl / g, and still more preferably 0.8. -2.0 dl / g.

  Further, propylene homopolymer (A-1), propylene homopolymer component of propylene-ethylene block copolymer (A-2-2), gel of propylene-ethylene random copolymer (A-2-1) The molecular weight distribution (Q value, Mw / Mn) measured by permeation chromatography (GPC) is preferably 3 to 7, respectively. It is preferable if it is within the above numerical value range since excellent mechanical strength can be obtained.

  The ethylene content contained in the propylene-ethylene random copolymer component of the block copolymer (A-2-2) is preferably 20 to 65% by mass, more preferably 25 to 50% by mass (provided that The total amount of 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 intrinsic viscosity ([η] _EP ) measured in a tetralin solvent at 135 ° C. of the propylene-ethylene random copolymer component of the block copolymer (A-2-2) is preferably 2 to 8 dl / g. More preferably, it is 2-6 dl / g, More preferably, it is 2-5 dl / g. It is preferable for it to be within the above numerical value range since the fineness of the cells of the foam molded article is increased.

  The content of the propylene-ethylene random copolymer component constituting the block copolymer (A-2-2) is preferably based on 100% by mass of the propylene-ethylene block copolymer (A-2-2). Is 10 to 60% by mass, more preferably 10 to 40% by mass, still more preferably 15 to 40% by mass, and particularly preferably 20 to 40% by 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. 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.

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 and JP-A-10-212319.

  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 the catalyst system, at least two polymerization tanks are arranged in series to produce the propylene homopolymer component of the propylene-ethylene block copolymer (A-2-2). This is a method for producing a propylene-ethylene block copolymer (A-2-2) by transferring the components to the next polymerization tank and continuously producing the propylene-ethylene random copolymer component in the polymerization tank.
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 usually −30 to 300 ° C., 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)>
The polypropylene resin composition of the present invention contains an ethylene-α-olefin copolymer (B), and the ethylene-α-olefin copolymer (B) has a density of 0.85 to 0.89 g / cm ^3. It is preferable that the melt flow rate (190 ° C., 2.16 kg load) is 1 to 40 g / 10 min.

  Examples of the ethylene-α-olefin copolymer (B) used in the present invention include an ethylene-α-olefin random copolymer or a mixture thereof. These 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.

In the polypropylene resin composition of the present invention, the total of the propylene polymer (A) and the ethylene-α-olefin copolymer (B) is 100% by mass, and the ethylene-α-olefin copolymer (B) is 1 to Including 60% by mass, preferably 15 to 60% by mass, more preferably 15 to 40% by mass. It is excellent in impact resistance and the rigidity of a foaming molding as it is the said range.
Moreover, it may be inferior to impact resistance as content of an ethylene-alpha-olefin copolymer (B) is less than 1 mass%. Moreover, when content of an ethylene-alpha-olefin copolymer (B) exceeds 60 mass%, it may be inferior to the rigidity of a foaming molding.

  The ethylene content contained in the ethylene-α-olefin copolymer (B) is preferably 20 to 95% by mass, more preferably 30 to 90% by mass, and further preferably 60 to 90% by mass. . The α-olefin content is preferably 80 to 5% by mass, more preferably 70 to 10% by mass, and further preferably 40 to 10% by mass.

The density of the ethylene -α- olefin copolymer (B) is preferably 0.85~0.89g / cm ^3, more preferably from 0.85~0.88g / cm ^3, more preferably 0.86 to 0.88 g / cm ³ . When the density is 0.85 g / cm ³ or more, the foam moldability is excellent, and when the density is 0.89 g / cm ³ or less, the uniformity and fineness of the foamed cells are preferable.

  The melt flow rate (190 ° C., 2.16 kg load) of the ethylene-α-olefin copolymer (B) is preferably 1 to 40 g / 10 minutes, and more preferably 10 to 40 g / 10 minutes. 10 to 35 g / 10 min is more preferable. It is preferable for the melt flow rate to be 1 g / 10 min or more because the occurrence of silver streaks in the obtained foamed molded article is suppressed.

<Phosphites represented by formula (I) (C)>
In the polypropylene resin composition of the present invention, the phosphite ester (C) represented by the following formula (I) is 0.001 to 5 parts per 100 parts by mass in total of the masses of (A) and (B). It is obtained by heat-treating a resin composition containing parts by mass.

（式（Ｉ）中、Ｒ¹、Ｒ²、Ｒ⁴およびＲ⁵はそれぞれ独立に水素原子、炭素原子数１〜８のアルキル基、炭素原子数５〜８のシクロアルキル基、炭素原子数６〜１２のアルキルシクロアルキル基、炭素原子数７〜１２のアラルキル基またはフェニル基を表し、Ｒ³は水素原子または炭素原子数１〜８のアルキル基を表す。Ｘは単結合、硫黄原子もしくは−ＣＨＲ⁶−基（Ｒ⁶は水素原子、炭素数１〜８のアルキル基または炭素数５〜８のシクロアルキル基を示す。）を表す。Ａは炭素数２〜８のアルキレン基または＊−ＣＯ（Ｒ⁷）_m−基（Ｒ⁷は炭素数１〜８のアルキレン基を表し、＊は酸素原子と結合する部位であることを表し、ｍは０または１を表す。）を表す。ＹおよびＺは、いずれか一方がヒドロキシル基、炭素原子数１〜８のアルコキシ基または炭素原子数７〜１２のアラルキルオキシ基を表し、もう一方が水素原子または炭素原子数１〜８のアルキル基を表す。）

(In the formula (I), R ¹ , R ² , R ⁴ and R ⁵ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, or 6 carbon atoms. Represents an alkylcycloalkyl group having 12 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, or a phenyl group, R ³ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, X is a single bond, a sulfur atom or — CHR ⁶ — represents a group (R ⁶ represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a cycloalkyl group having 5 to 8 carbon atoms), and A represents an alkylene group having 2 to 8 carbon atoms or * —CO. (R ⁷ ) _m -group (R ⁷ represents an alkylene group having 1 to 8 carbon atoms, * represents a site bonded to an oxygen atom, and m represents 0 or 1) Y and Z is either a hydroxyl group or an alkyl group having 1 to 8 carbon atoms. A coxy group or an aralkyloxy group having 7 to 12 carbon atoms is represented, and the other represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.)

In the formula (I), the substituents R ¹ , R ² , R ⁴ and R ⁵ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, or a carbon atom. An alkylcycloalkyl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, or a phenyl group is represented.

  Here, as a representative example of an alkyl group having 1 to 8 carbon atoms, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, Examples include t-butyl group, t-pentyl group, i-octyl group, t-octyl group, 2-ethylhexyl group and the like. Typical examples of the cycloalkyl group having 5 to 8 carbon atoms include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, and the like. Typical examples of the alkylcycloalkyl group having 6 to 12 carbon atoms include 1-methylcyclopentyl group, 1-methylcyclohexyl group, 1-methyl-4-i-propylcyclohexyl group and the like. Typical examples of the aralkyl group having 7 to 12 carbon atoms include benzyl group, α-methylbenzyl group, α, α-dimethylbenzyl group and the like.

R ¹ , R ² and R ⁴ are preferably an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, and an alkylcycloalkyl group having 6 to 12 carbon atoms.
Among them, R ¹ and R ⁴ are more preferably a t-alkyl group such as a t-butyl group, a t-pentyl group, or a t-octyl group, a cyclohexyl group, and a 1-methylcyclohexyl group.

R ² is more preferably carbon such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, t-pentyl group, etc. An alkyl group having 1 to 5 atoms, more preferably a methyl group, a t-butyl group, or a t-pentyl group.

R ⁵ is preferably a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a cycloalkyl group having 5 to 8 carbon atoms, more preferably a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, i -An alkyl group having 1 to 5 carbon atoms such as a propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, t-pentyl group.

The substituent R ³ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and examples of the alkyl group having 1 to 8 carbon atoms include the same alkyl groups as described above. Preferably they are a hydrogen atom or a C1-C5 alkyl group, More preferably, they are a hydrogen atom or a methyl group.

  Substituent X, when n is 0, represents that two groups having a phenoxy group skeleton are directly bonded, and when n is 1, it is a sulfur atom or an alkyl group having 1 to 8 carbon atoms. Or the methylene group which the C5-C8 cycloalkyl group may substitute is represented. Here, examples of the alkyl group having 1 to 8 carbon atoms and the cycloalkyl group having 5 to 8 carbon atoms substituted on the methylene group include the same alkyl groups and cycloalkyl groups as described above. As the substituent X, n is preferably 0 and a group having two phenoxy group skeletons is directly bonded, or n is 1, and a methylene group, a methyl group, an ethyl group, or an n-propyl group , I-propyl group, n-butyl group, i-butyl group, t-butyl group and the like are substituted methylene groups.

Substituent A is an alkylene group having 2 to 8 carbon atoms or * —CO (R ⁷ ) _m — group (R ⁷ is an alkylene group having 1 to 8 carbon atoms, and * is a site bonded to an oxygen atom. And m is 0 or 1.

Here, as typical examples of the alkylene group having 2 to 8 carbon atoms, for example, ethylene group, propylene group, butylene group, pentamethylene group, hexamethylene group, octamethylene group, 2,2-dimethyl-1,3- A propylene group etc. are mentioned, Preferably it is a propylene group. The * -COR ⁷ - * in group indicates that the carbonyl group is a site that binds to the oxygen atom of the phosphite group. Representative examples of the alkylene group having 1 to 8 carbon atoms in R ⁷ include, for example, methylene group, ethylene group, propylene group, butylene group, pentamethylene group, hexamethylene group, octamethylene group, 2,2-dimethyl- Examples include 1,3-propylene group. * —CO (R ⁷ ) _m — group is preferably * —CO— group in which m is 0, or —CO (CH ₂ CH ₂ ) — group in which m is 1 and R ⁷ is ethylene. It is.

  One of Y and Z represents a hydroxyl group, an alkoxy group having 1 to 8 carbon atoms or an aralkyloxy group having 7 to 12 carbon atoms, and the other represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.

  Here, examples of the alkyl group having 1 to 8 carbon atoms include the same alkyl groups as described above. Examples of the alkoxy group having 1 to 8 carbon atoms include an alkyl moiety having the above-described alkyl having 1 to 8 carbon atoms. The alkoxy group which is the same alkyl is mentioned, and the aralkyloxy group having 7 to 12 carbon atoms includes, for example, an aralkyloxy group in which the aralkyl moiety is the same aralkyl as the aralkyl having 7 to 12 carbon atoms.

The phosphites (C) represented by the formula (I) used in the present invention are preferably the following compounds (1) to (13).
Compounds (1) to (13) are shown below together with the chemical structural formula.

化合物（１）：２，４，８，１０−テトラ−ｔ−ブチル−６−［３−（３−メチル−４−ヒドロキシ−５−ｔ−ブチルフェニル）プロポキシ］ジベンゾ［ｄ，ｆ］［１，３，２］ジオキサホスフェピン、

Compound (1): 2,4,8,10-tetra-tert-butyl-6- [3- (3-methyl-4-hydroxy-5-tert-butylphenyl) propoxy] dibenzo [d, f] [1 , 3,2] dioxaphosphepine,

化合物（２）：２，１０−ジメチル−４，８−ジ−ｔ−ブチル−６−［３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロポキシ］−１２Ｈ−ジベンゾ［ｄ，ｇ］［１，３，２］ジオキサホスホシン、

Compound (2): 2,10-dimethyl-4,8-di-t-butyl-6- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propoxy] -12H-dibenzo [d , G] [1, 3, 2] dioxaphosphocin,

化合物（３）：２，４，８，１０−テトラ−ｔ−ブチル−６−［３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロポキシ］ジベンゾ［ｄ，ｆ］［１，３，２］ジオキサホスフェピン、

Compound (3): 2,4,8,10-tetra-t-butyl-6- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propoxy] dibenzo [d, f] [1 , 3,2] dioxaphosphepine,

化合物（４）：２，４，８，１０−テトラ−ｔ−ペンチル−６−［３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロポキシ］−１２−メチル―１２Ｈ−ジベンゾ［ｄ，ｇ］［１，３，２］ジオキサホスホシン、

Compound (4): 2,4,8,10-tetra-t-pentyl-6- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propoxy] -12-methyl-12H-dibenzo [D, g] [1,3,2] dioxaphosphocin,

化合物（５）：２，１０−ジメチル−４，８−ジ−ｔ−ブチル−６−［３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオニルオキシ］−１２Ｈ−ジベンゾ［ｄ，ｇ］［１，３，２］ジオキサホスホシン、

Compound (5): 2,10-dimethyl-4,8-di-t-butyl-6- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -12H-dibenzo [ d, g] [1,3,2] dioxaphosphocin,

化合物（６）：２，４，８，１０−テトラ−ｔ−ペンチル−６−［３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオニルオキシ］−１２−メチル―１２Ｈ−ジベンゾ［ｄ，ｇ］［１，３，２］ジオキサホスホシン、

Compound (6): 2,4,8,10-tetra-t-pentyl-6- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -12-methyl-12H- Dibenzo [d, g] [1,3,2] dioxaphosphocin,

化合物（７）：２，４，８，１０−テトラ−ｔ−ブチル−６−［３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオニルオキシ］−ジベンゾ［ｄ，ｆ］［１，３，２］ジオキサホスフェピン、

Compound (7): 2,4,8,10-tetra-t-butyl-6- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -dibenzo [d, f] [1,3,2] dioxaphosphepine,

化合物（８）：２，１０−ジメチル−４，８−ジ−ｔ−ブチル−６−（３，５−ジ−ｔ−ブチル−４−ヒドロキシベンゾイルオキシ）−１２Ｈ−ジベンゾ［ｄ，ｇ］［１，３，２］ジオキサホスホシン、

Compound (8): 2,10-dimethyl-4,8-di-t-butyl-6- (3,5-di-t-butyl-4-hydroxybenzoyloxy) -12H-dibenzo [d, g] [ 1,3,2] dioxaphosphocin,

化合物（９）：２，４，８，１０−テトラ−ｔ−ブチル−６−（３，５−ジ−ｔ−ブチル−４−ヒドロキシベンゾイルオキシ）−１２−メチル−１２Ｈ−ジベンゾ［ｄ，ｇ］［１，３，２］ジオキサホスホシン、

Compound (9): 2,4,8,10-tetra-t-butyl-6- (3,5-di-t-butyl-4-hydroxybenzoyloxy) -12-methyl-12H-dibenzo [d, g ] [1,3,2] dioxaphosphocin,

化合物（１０）：２，１０−ジメチル−４，８−ジ−ｔ−ブチル−６［３−（３−メチル−４−ヒドロキシ−５−ｔ−ブチルフェニル）プロポキシ］−１２Ｈ−ジベンゾ［ｄ，ｇ］［１，３，２］ジオキサホスホシン、

Compound (10): 2,10-dimethyl-4,8-di-tert-butyl-6 [3- (3-methyl-4-hydroxy-5-tert-butylphenyl) propoxy] -12H-dibenzo [d, g] [1,3,2] dioxaphosphocin,

化合物（１１）：２，４，８，１０−テトラ−ｔ−ブチル−６−［３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロポキシ］−１２Ｈ−ジベンゾ［ｄ，ｇ］［１，３，２］ジオキサホスホシン、

Compound (11): 2,4,8,10-tetra-t-butyl-6- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propoxy] -12H-dibenzo [d, g ] [1,3,2] dioxaphosphocin,

化合物（１２）：２，１０−ジエチル−４，８−ジ−ｔ−ブチル−６−［３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロポキシ］−１２Ｈ−ジベンゾ［ｄ，ｇ］［１，３，２］ジオキサホスホシン、

Compound (12): 2,10-diethyl-4,8-di-t-butyl-6- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propoxy] -12H-dibenzo [d , G] [1, 3, 2] dioxaphosphocin,

化合物（１３）：２，４，８，１０−テトラ−ｔ−ブチル−６−［１，１−ジメチル−３−（３−ｔ−ブチル−４−ヒドロキシ−５−メチルフェニル）プロポキシ］−ジベンゾ［ｄ，ｆ］［１，３，２］ジオキサホスフェピン。

Compound (13): 2,4,8,10-tetra-t-butyl-6- [1,1-dimethyl-3- (3-t-butyl-4-hydroxy-5-methylphenyl) propoxy] -dibenzo [D, f] [1,3,2] dioxaphosphine.

  The amount of the phosphite ester (C) represented by the formula (I) is 0.001 to 5 parts by mass with respect to 100 parts by mass in total of the masses of (A) and (B), preferably It is 0.01-1 mass part, More preferably, it is 0.01-0.5 mass part. When the amount of the phosphite ester (C) represented by the formula (I) is less than 0.001 part by mass, the thermal stability of the polypropylene resin composition may be insufficient, and 5 parts by mass If it exceeds, it is not economical.

  The phosphites (C) represented by the formula (I) may contain amines, acid-bonded metal salts, etc., and by containing amines, acid-bonded metal salts, etc. , Hydrolysis resistance can be improved.

  Examples of amines include trialkanolamines such as triethanolamine, tripropanolamine, and tri-i-propanolamine, diethanolamine, dipropanolamine, di-i-propanolamine, tetraethanolethylenediamine, and tetra-i-propanol. Dialkanolamines such as ethylenediamine, monoalkanolamines such as dibutylethanolamine and dibutyl-i-propanolamine, aromatic amines such as 1,3,5-trimethyl-2,4,6-triazine, dibutylamine, Alkylamines such as piperidine, 2,2,6,6-tetramethylpiperidine, 4-hydroxy-2,2,6,6-tetramethylpiperidine, hexamethylenetetramine, triethylenediamine, triethylenetetra Emissions, polyalkylene polyamines such as tetraethylene pentamine, and hindered amine based light stabilizer and the like.

  Further, a long-chain aliphatic amine described in JP-A-61-63686, a compound containing a sterically hindered amine group described in JP-A-6-329830, and a hindered dye described in JP-A-7-90270. Examples thereof include peridinyl light stabilizers and organic amines described in JP-A-7-278164.

  The content of the amines in the case where the phosphites (C) represented by the formula (I) are incorporated with amines is 100 masses of the phosphites (C) represented by the formula (I). It is preferable that it is 0.01-25 mass% with respect to%.

Examples of the acid-bonded metal salt include hydrotalcites and the like, which may be natural products or synthetic products, and the crystal structure, crystal particle size, etc. are not particularly limited. Absent. Examples of hydrotalcites include double salt compounds represented by the following formula (II).
M ²⁺ _1-x , M ³⁺ _x , (OH ⁻ ) ₂ , (A ⁿ⁻ ) _{x / n} , pH ₂ O (II)
( ^Wherein M ²⁺ represents Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , Zn ²⁺ , Pb ²⁺ , Sn ²⁺ and / or Ni ²⁺ , and M ³⁺ represents al ^3+, represent B ³⁺ or Bi ^3+, n is an integer of 1 or more, x is a number of 0 to 0.5, p represents .A ^n-is the number of 0 to 2, n-valent Represents an anion of
Here, examples of the n-valent anion represented by A ⁿ⁻ include OH ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , ClO ₄ ⁻ , HCO ₃ ⁻ , C ₆ H ₅ COO ⁻ , CO ₃ ²⁻ , ^{SO 2-, - OOCCOO -, (} CH (OH) COO) 2 2-, C 2 H 4 (COO) 2 2-, (CH 2 COO) 2 2-, CH 3 CH (OH) COO -, SiO 3 ^2- , SiO ₄ ⁴⁻ , Fe (CN) ₆ ⁴⁻ , BO ₃ ⁻ , PO ₃ ³⁻ , HPO ₄ ^{2− and the} like.

Among the double salt compounds represented by the above formula (II), hydrotalcites represented by the following formula (III) are particularly preferable.
Mg _1-x Al _x (OH) ₂ (CO ₃ ) _{x / 2} · pH ₂ O (III)
(In the formula, x represents a number from 0 to 0.5, and p represents a number from 0 to 2.)

  Furthermore, examples of the acid-bonded metal salt that can be contained in the phosphites (C) represented by the formula (I) include ultrafine zinc oxide described in JP-A-6-329830, Examples include inorganic compounds described in JP-A-7-278164.

  The content of the acid-bonded metal salt when the acid-bonded metal salt is contained in the phosphite ester (C) represented by the formula (I) is the phosphite ester represented by the formula (I) ( C) It is preferable that it is 0.01-25 mass% with respect to 100 mass%.

<Organic peroxide (D)>
The polypropylene resin composition of the present invention is a resin composition containing 0.0001 to 0.5 parts by mass of the organic peroxide (D) with respect to 100 parts by mass in total of the mass of (A) and (B). It is obtained by heat treatment.

  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, Mention may be made of organic peroxides having a decomposition temperature of 120 ° C. or more with a period of 1 minute.

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

  Examples of the compound (I) having the structure represented by the above formula (1) include di (3-methoxybutyl) peroxydicarbonate, di (2-ethylhexyl) peroxydicarbonate, and 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-trimethylhexano Ate, t-butyl peroxylaurate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-butyl peroxyacetate, 2,2-bis (t-butylperoxy) butene, t -Butyl peroxybenzoate, n-butyl-4,4-bis (t-butylperoxy) 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-butylperoxide And oxy) hexyne-3.

  The usage-amount of an organic peroxide (D) is 0.0001-0.5 mass part with respect to a total of 100 mass parts of the mass of (A) and (B), and 0.005-0.2 mass. Part is more preferable, and 0.01 to 0.1 part by mass is even more preferable. It is excellent in foam moldability as it is the said range.

<(E) Inorganic filler>
The polypropylene resin composition of the present invention may contain (E) an inorganic filler.

  (E) As the inorganic filler, known ones can be used, and are not limited. Specifically, granular fillers such as glass beads, calcium carbonate, and barium sulfate, kaolin, and glass flakes. And plate-like fillers such as talc. Among them, plate-like fillers are preferable. A foamed molded article having excellent bending elasticity can be obtained by blending the plate-like filler. Moreover, since it is excellent in cost among plate-like fillers, talc is preferable.

(E) As an average particle diameter of an inorganic filler, 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 (E) was determined from the integral distribution curve of the 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.

  (E) The inorganic filler 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.

  (E) The addition amount of the inorganic filler is preferably 1 to 30 parts by mass, more preferably 1 to 20 parts by mass with respect to 100 parts by mass in total of the mass of (A) and (B). More preferably, it is 10 mass parts. Within the above range, a molded article having excellent rigidity and impact resistance can be obtained.

<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 (230 ° C., 2.16 kg load) of the polypropylene resin composition of the present invention is 40 to 200 g / 10 minutes, preferably 40 to 150 g / 10 minutes, preferably 40 to 120 g / 10 minutes. It is more preferable that Within the range of the above numerical values, it is possible to obtain a molded article having an excellent balance of mechanical properties, and further, it is possible to effectively suppress the occurrence of silver streaks in the foam molded article, which is preferable because of excellent foam moldability. .

<Method for Producing Polypropylene Resin Composition>
The production method of the polypropylene resin composition of the present invention is 40 to 99% by mass of the propylene polymer (A) and 1 to 60% by mass of the ethylene-α-olefin copolymer (B) (however, (A) And the total mass of (B) is 100% by mass) and the phosphites (C) represented by the following formula (I) are 100 parts by mass in total of the masses of (A) and (B). 0.001 to 5 parts by mass with respect to 100 parts by mass of the organic peroxide (D) with respect to 100 parts by mass in total of the masses of (A) and (B) A step of supplying to the kneading apparatus (hereinafter also referred to as “supplying step”), and a step of heat-treating the resin composition containing the components (A) to (D) by the melt-kneading apparatus (hereinafter also referred to as “heat treatment step”). MFR (melt flow rate, measurement temperature: 230) Load: 2.16 kg) is a method for producing a polypropylene resin composition which is a 40~200g / 10 min.
The above heat treatment is performed by melt-kneading, whereby the resin composition is uniformly mixed, and the organic peroxide (D) is decomposed, resulting in a reaction (for example, propylene heavy weight). The molecular chain of the coalescence breaks, etc.).
The method for producing a polypropylene resin composition of the present invention can suitably produce the polypropylene resin composition of the present invention.

In the supply step, the order in which (A) to (D) are supplied to the melt-kneading apparatus is not particularly limited, and each may be supplied in any order or two or more may be supplied simultaneously. In addition, in each component, the entire amount used may be supplied all at once, a part of the amount used may be added in multiple portions, or may be added continuously.
Above all,
Supplying (A) to (D) all at once to the melt-kneading apparatus;
(D) is supplied after collectively supplying (A), (B) and (C) to the melt-kneading apparatus, or
It is preferable to supply (B) after collectively supplying (A), (C) and (D) to the melt-kneading apparatus.

In addition, when the component (E) is used, the supply order is not particularly limited.
Supplying (A) to (E) to a melt-kneading apparatus at a time,
Supplying (D) after collectively supplying (A), (B), (C) and (E) to the melt-kneading apparatus,
Supplying (B) after collectively supplying (A), (C), (D) and (E) to the melt-kneading apparatus, or
It is preferable to supply (B) and (E) after collectively supplying (A), (C) and (D) to the melt-kneading apparatus.

The method for producing a polypropylene resin composition of the present invention includes a step of melt-kneading each component, and as a melt-kneading apparatus used for kneading, there are a single screw extruder, a twin screw extruder, a Banbury mixer, a hot roll, and the like. Can be mentioned.
The temperature of melt kneading (heat treatment) is preferably 170 to 250 ° C., and the heat treatment time is preferably 20 seconds to 20 minutes. Moreover, kneading | mixing of each component may be performed simultaneously and may be performed by dividing | segmenting. 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 foam molded article of the present invention is a foam molded article comprising the polypropylene resin composition of the present invention or the polypropylene resin composition produced by the method for producing the polypropylene resin composition of the present invention. A foamed molded article obtained by adding a foaming agent to a polypropylene resin composition or a polypropylene resin composition produced by the method for producing a polypropylene resin composition of the present invention and molding it is preferable.

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% by mass, and more preferably 0.2 to 8% 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 them, 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.

  Specifically, the step of foam molding the polypropylene resin composition of the present invention includes a step using a known method such as an injection foam molding method, a press foam molding method, an extrusion foam molding method, or a stampable foam molding method. It is done.

  When using a physical foaming agent, it is preferable to mix with 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 method of mixing the physical foaming agent into the molten polypropylene resin composition include a method of injecting the physical foaming agent into a nozzle or cylinder of an injection molding apparatus.

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

  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, and polyethylene foam.

<Uses of foam moldings>
Applications of the foamed molded article of the present invention include, for example, automobile parts such as automobile interior parts and exterior parts, motorcycle parts, furniture and electrical product parts. Especially, the foaming molding of this invention can be used suitably for automotive parts, and can be used suitably for automotive interior components.

  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-ethylene block copolymer (A-1)
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 by.
MFR: 30 g / 10 minutes Intrinsic viscosity [η] _{T of the} entire propylene-ethylene block copolymer: 1.40 dl / g
Intrinsic viscosity of propylene homopolymer part [η] _P : 1.06 dl / g
Proportion of propylene-ethylene random copolymer portion to the whole copolymer: 20.5% by mass
Intrinsic viscosity [η] _{EP of} propylene-ethylene random copolymer portion: 2.8 dl / g
Ethylene unit content of propylene-ethylene random copolymer portion: 37% by mass

(2) Propylene-ethylene block copolymers (A-2) to (A-4)
It manufactured using the method similar to the said propylene-ethylene block copolymer (A-1).
(A-2)
MFR: 60 g / 10 min propylene - ethylene block copolymer overall intrinsic viscosity [η] _T: 1.55dl / g
Intrinsic viscosity of propylene homopolymer part [η] _P : 0.89 dl / g
Mass ratio of propylene-ethylene random copolymer portion to the whole copolymer: 13% by mass
Intrinsic viscosity [η] _{EP of} propylene-ethylene random copolymer portion: 6.0 dl / g
Ethylene unit content of propylene-ethylene random copolymer portion: 32% by mass

(A-3)
MFR: 35 g / 10 min propylene - ethylene block copolymer overall intrinsic viscosity [η] _T: 1.58dl / g
Intrinsic viscosity of propylene homopolymer part [η] _P : 0.90 dl / g
Mass ratio of propylene-ethylene random copolymer portion to the whole copolymer: 22% by mass
Intrinsic viscosity [η] _{EP of the} propylene-ethylene random copolymer portion: 4.0 dl / g
Ethylene unit content of propylene-ethylene random copolymer portion: 32% by mass

(A-4)
MFR: 100 g / 10 min propylene - ethylene block copolymer overall intrinsic viscosity [η] _T: 1.48dl / g
Intrinsic viscosity [η] _P of propylene homopolymer part: 0.80 dl / g
Mass ratio of propylene-ethylene random copolymer portion to the whole copolymer: 11% by mass
Intrinsic viscosity [η] _{EP of the} propylene-ethylene random copolymer portion: 7.0 dl / g
Ethylene unit content of propylene-ethylene random copolymer portion: 32% by mass

(3) Elastomer (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-octene copolymer rubber Product name: EG8137 (manufactured by Dow Chemical Co., Ltd.)
Density: 0.864 (g / cm ³ )
MFR (190 ° C., 2.16 kg load): 13 (g / 10 min)

(4) Phosphites (C)
Product name: Sumilizer GP (manufactured by Sumitomo Chemical Co., Ltd.)
Chemical name: 2,4,8,10-tetra-t-butyl-6- [3- (3-methyl-4-hydroxy-5-t-butylphenyl) propoxy] dibenzo [d, f] [1,3 , 2] Dioxaphosphepine

(5) Organic peroxide (D)
Product name: Parkadox 14R-P (bis (t-butyldioxyisopropyl) benzene) manufactured by Kayaku Akzo Corporation

(6) Inorganic filler (E)
Product name: JR-46 (talc), particle size: 2.7 μm, manufactured by Hayashi Kasei Co., Ltd.

(Example 1 and Comparative Example 1)
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, a cylinder set temperature of 220 ° C., a mold cooling temperature of 50 ° C., an injection time of 15 seconds, a cooling time of 30 using an IS150E-V type injection molding machine (clamping force of 150 tons) manufactured by Toshiba Machine Co., Ltd. Injection molding was performed in seconds.

The measuring method of the physical property of the resin component and polypropylene resin composition which were used in the Example and the comparative example was 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) (2-1) Intrinsic viscosity of propylene-ethylene block copolymer (A) (2-1-a) Propylene homopolymer portion (first segment ) Intrinsic viscosity: [η] _P
Intrinsic viscosity of the propylene homopolymer portion which is the first segment of the propylene-ethylene block copolymer: [η] _P is the propylene homopolymer from the inside of the polymerization tank after the polymerization of the propylene homopolymer which is the first step. The coalescence was taken out, and [η] _P of the taken out propylene homopolymer was measured and determined.

(2-1-b) Intrinsic viscosity of propylene-ethylene random copolymer portion (second segment): [η] _EP
The intrinsic viscosity of the propylene-ethylene random copolymer portion, which is the second segment of the propylene-ethylene block copolymer: [η] _EP is the intrinsic viscosity of the propylene homopolymer portion: [η] _P and the propylene-ethylene block copolymer. Intrinsic viscosity of the entire polymer: [η] _T was measured, and the mass ratio: X of the propylene-ethylene random copolymer portion to the entire propylene-ethylene block copolymer was calculated from the following formula.
[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 block copolymer (dl / g)

(2-2) Mass ratio of propylene-ethylene random copolymer portion to the entire propylene-ethylene block copolymer: X
Mass ratio of the propylene-ethylene random copolymer portion to the entire propylene-ethylene block copolymer: X is the amount of heat of crystal melting of the propylene homopolymer portion (first segment) and the entire propylene-ethylene block copolymer. And obtained by calculation using the following equation. 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 block copolymer (cal / g)
(ΔHf) _P : heat of fusion of the propylene homopolymer portion (cal / g)

(2-3) Ethylene content of propylene-ethylene random copolymer portion in propylene-ethylene block copolymer: (C2 ′) _EP
Ethylene content of the propylene-ethylene random copolymer portion of the propylene-ethylene block copolymer: (C2 ′) _EP measures the ethylene content (C2 ′) _T of the entire propylene-ethylene block copolymer by infrared absorption spectroscopy. And obtained by calculation using the following equation.
(C2 ′) _EP = (C2 ′) _T / X
(C2 ′) _T : ethylene content (mass%) of the entire propylene-ethylene block copolymer
(C2 ′) _EP : ethylene content (% by mass) of propylene-ethylene random copolymer portion
X: Mass ratio of propylene-ethylene random copolymer portion to the entire propylene-ethylene block copolymer

(3) Measurement of flexural modulus (FM, unit: MPa) According to the method defined in JIS K7171, the flexural modulus of the unfoamed molded body was measured. For the measurement, a test piece molded by injection molding was used. The thickness of the test piece was 6.4 mm, and the flexural modulus was evaluated under the conditions of a span length of 100 mm, a width of 12.7 mm, and a load speed of 2.0 mm / min. The measurement temperature was 23 ° C.

(4) Elongation at break (UE, unit:%)
In accordance with the method prescribed in ASTM D638, the elongation at break of a non-foamed molded article was measured. A test piece molded by injection molding was used. The thickness of the test piece was 3.2 mm, the pulling speed was 50 mm / min, and the elongation at break (UE) was evaluated. The measurement was performed at 23 ° C.

(5) Izod impact strength (Izod, unit: kJ / m ² )
In accordance with the method defined in JIS K7110, a test piece (thickness: 6.4 mm) molded by injection molding was used to perform notch processing after molding, and the impact strength with notch of the molded product that was not foamed was evaluated. The measurement temperature was 23 ° C. unless otherwise specified.

Claims (7)

40-99 mass% of propylene polymer (A),
1 to 60% by mass of the ethylene-α-olefin copolymer (B) (provided that the total mass of (A) and (B) is 100% by mass);
0.001 to 5 parts by mass of the phosphite ester (C) represented by the following formula (I) with respect to a total of 100 parts by mass of the mass of (A) and (B),
0.0001 to 0.5 parts by mass of the organic peroxide (D) with respect to a total of 100 parts by mass of the mass of (A) and (B),
Obtained by heat-treating a resin composition containing
A polypropylene resin composition having a melt flow rate (MFR, measurement temperature: 230 ° C., load: 2.16 kg) of 40 to 200 g / 10 minutes.

(In the formula (I), R ¹ , R ² , R ⁴ and R ⁵ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, or 6 carbon atoms. Represents an alkylcycloalkyl group having 12 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, or a phenyl group, R ³ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, X is a single bond, a sulfur atom or — CHR ⁶ - group (R ⁶ is a hydrogen atom, an alkyl group or a cycloalkyl group having a carbon number of 5-8 having from 1 to 8 carbon atoms.) alkylene or * -CO of .A 2 to 8 carbon atoms representing the (R ⁷ ) _m -group (R ⁷ represents an alkylene group having 1 to 8 carbon atoms, * represents a site bonded to an oxygen atom, and m represents 0 or 1) Y and Z is either a hydroxyl group or an alkyl group having 1 to 8 carbon atoms. A coxy group or an aralkyloxy group having 7 to 12 carbon atoms is represented, and the other represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.) The polypropylene resin composition according to claim 1, wherein the ethylene-α-olefin copolymer (B) has a density of 0.85 to 0.89 g / cm ³ .   The polypropylene according to claim 1 or 2, wherein the MFR (melt flow rate, measurement temperature: 190 ° C, load: 2.16 kg) of the ethylene-α-olefin copolymer (B) is 1 to 40 g / 10 min. -Based resin composition.   The polypropylene resin composition according to any one of claims 1 to 3, wherein the propylene polymer (A) contains a propylene homopolymer and / or a propylene-ethylene copolymer.   The polypropylene system according to claim 4, wherein the propylene-ethylene copolymer is a propylene-ethylene block copolymer containing a propylene-ethylene random copolymer component having an intrinsic viscosity of 2 dl / g or more and 8 dl / g or less. Resin composition. 40 to 99% by mass of the propylene polymer (A) and 1 to 60% by mass of the ethylene-α-olefin copolymer (B) (however, the total mass of (A) and (B) is 100% by mass) And phosphites (C) represented by the following formula (I) with respect to a total of 100 parts by mass of (A) and (B), 0.001 to 5 parts by mass, and organic Supplying the peroxide (D) to the melt-kneading apparatus in an amount of 0.0001 to 0.5 parts by mass with respect to a total of 100 parts by mass of the masses of (A) and (B); and
Including a step of heat-treating the resin composition containing (A) to (D) by the melt kneading apparatus,
A method for producing a polypropylene resin composition, wherein a melt flow rate (MFR, measurement temperature: 230 ° C., load: 2.16 kg) is 40 to 200 g / 10 minutes.

(In the formula (I), R ¹ , R ² , R ⁴ and R ⁵ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, or 6 carbon atoms. Represents an alkylcycloalkyl group having 12 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, or a phenyl group, R ³ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, X is a single bond, a sulfur atom or — CHR ⁶ — represents a group (R ⁶ represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a cycloalkyl group having 5 to 8 carbon atoms), and A represents an alkylene group having 2 to 8 carbon atoms or * —CO. (R ⁷ ) _m -group (R ⁷ represents an alkylene group having 1 to 8 carbon atoms, * represents a site bonded to an oxygen atom, and m represents 0 or 1) Y and Z is either a hydroxyl group or an alkyl group having 1 to 8 carbon atoms. A coxy group or an aralkyloxy group having 7 to 12 carbon atoms is represented, and the other represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.)   The foaming molding which consists of a polypropylene resin composition manufactured by the polypropylene resin composition as described in any one of Claims 1-5, or the manufacturing method of Claim 6.