JPH07103280B2 - Polypropylene resin composition for automobile interior and exterior parts - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polypropylene resin composition for automobile interior and exterior parts, and more specifically to a polypropylene resin, an ethylene-α-olefin copolymer rubber, and a low molecular weight. An ethylene-α-olefin-based polymer of
The present invention relates to a soft polypropylene resin composition that is useful for automobile interior and exterior parts such as inner panels and dashboards.

[Conventional technology]

In recent years, soft materials have been desired from the viewpoint of stability in applications such as automobile interior and exterior parts, particularly bumpers, inner panels, dashboards and the like. However, conventional materials have many problems in terms of cost and aging characteristics.

For example, as a means for softening a polypropylene resin, a method has been adopted in which a large amount of ethylene-propylene rubber is mixed with the resin or a softening agent such as oil is added.

However, in order to soften the polypropylene resin by these methods, it is necessary to add a large amount of compounding parts, resulting in an increase in cost, deterioration of aging resistance, and a softening agent such as oil that is added to the surface of the molded product. There was a problem such as the phenomenon of bleeding (bleeding phenomenon).

[Problems to be solved by the invention]

The present invention has been made against the background of these problems of the prior art, and provides a polypropylene resin composition for automobile interior / exterior parts having a low flexural modulus, impact resistance, and improved bleed resistance. To aim.

[Means for solving problems]

The present invention relates to (A) 50 to 90 parts by weight of polypropylene resin, (B) Mooney viscosity (ML _{1 + 4} , 100 ° C.) of 10 to 150, ethylene-α-olefin copolymer rubber (hereinafter referred to as “copolymer rubber”). 5 to 45 parts by weight, and (C) the weight average molecular weight (Mw) is 5,000 to 50,000, and the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn).
Of 2 to 5 and an α-olefin content of 30 to 75% by weight, and a low molecular weight ethylene-α-olefin copolymer (hereinafter referred to as "low molecular weight copolymer") 5 to 45 parts by weight [where (A ) + (B) + (C) = 100 parts by weight] is provided. A polypropylene resin composition for automobile interior / exterior parts (hereinafter, also simply referred to as “polypropylene resin composition”) is provided. .

The polypropylene resin (A) used in the present invention is a propylene homopolymer obtained by homopolymerizing propylene using a so-called Ziegler-Natta catalyst, or propylene and a small amount of ethylene or an α-olefin having 4 to 12 carbon atoms. It is a copolymer of propylene and ethylene or α-olefin obtained by copolymerizing. When the polypropylene resin is a copolymer, the copolymerization ratio of ethylene or α-olefin in the copolymer is 3 to 20% by weight, and the copolymer may be a random copolymer or a block copolymer.

The melt flow rate of the polypropylene resin (A) is 0.3 to 80 g / 10 minutes (230 ° C), preferably 1.2 to 5
It is 0 g / 10 minutes (230 ° C).

In carrying out the present invention, these polypropylene resins may be used alone or in combination of two or more kinds.

The proportion of the above (A) polypropylene resin in 100 parts by weight of the composition is 50 to 90 parts by weight, preferably 50 to 90 parts by weight.
80 parts by weight, if less than 50 parts by weight the resulting composition becomes too soft and the scratching property deteriorates, while if it exceeds 90 parts by weight, the effect of the present invention cannot be achieved due to a small proportion of softening. .

Next, the (B) copolymer rubber used in the present invention is obtained, for example, by copolymerizing ethylene with an α-olefin and / or a non-conjugated diene using a Ziegler type catalyst.

The α-olefin used as the copolymerization monomer of the (B) copolymer rubber is an α-olefin having 3 to 12 carbon atoms, and specific examples thereof include propylene, butene-1,
4-Methylpentene-1, octene-1, preferably propylene and / or butene-1. These α
-The olefins may be used alone or in combination of two or more.

It is also possible to copolymerize the (B) copolymer rubber used in the resin composition of the present invention with a non-conjugated diene, and examples of such a diene include the following compounds.

Dicyclopentadiene, tricyclopentadiene, 5-
Methyl-2,5-norbornadiene, 5-methylene-2-
Norbornene, 5-ethylidene-2-norbornene, 5
-Isopropylidene-2-norbornene, 5-isopropenyl-2-norbornene, 5- (1-butenyl) -2
-Norbornene, cyclooctadiene, vinylcyclohexane, 1,5,9-cyclododecatriene, 6-methyl-
4,7,8,9-Tetrahydroindene, 2,2'-dicyclopentenyl, trans-1,2-divinylcyclobutane, 1,4-
Hexadiene, 1,6-octadiene, 1,6-octadiene, 1,7-octadiene, 1,8-nonadiene, 1,9-decadiene, 3,6-dimethyl-1,7-octadiene, 4,5-dimethyl- 1,7-octadiene, 1,4,7-octatriene,
5-methyl-1,8-nonadiene.

Among these non-conjugated dienes, especially 5-ethylidene-2-
Norbornene (ENB) and / or dicyclopentadiene (DCP) are preferred.

The (B) copolymer rubber has an α-olefin content of 15 to 80.
% By weight, Mooney viscosity (ML _{1 + 4} , 100 ° C.) is 10-150.

The (B) copolymer rubber can be obtained by the following manufacturing method.

That is, as the catalyst component used in the production of the (B) copolymer rubber, a catalyst comprising a combination of a vanadium compound and / or a titanium compound and an organometallic compound of a metal of Group I to IV of the periodic table is used.

As a vanadium compound, it is soluble in an inert organic solvent.
A pentavalent vanadium compound is used.

As the vanadium compound, a vanadium halide, an oxyhalide, a chelate complex with an oxygen-containing compound,
Vanadates and the like are preferable.

Specific examples of these compounds include vanadium tetrachloride, vanadium oxytrichloride, vanadium trisacetylacetonate, vanadic acid triethoxide, vanadic acid tri-n-butoxide, vanadic acid di-n-butoxymonochloride, vanadic acid. Examples thereof include reaction products of ethoxydichloride, vanadium tetrachloride or vanadium oxytrichloride and alcohol. These may be used alone or in combination of two or more.

Among these compounds, more preferred are vanadium tetrachloride, vanadium oxytrichloride and reaction products of these vanadium compounds with alcohol.

As the titanium compound, solid or dissolved titanium trichloride catalyst, titanium trichloride or titanium tetrachloride catalyst supported on magnesium chloride is used, and vanadium compound is preferable.

Examples of the organometallic compound of a metal of groups I to IV of the periodic table include:
Mention may be made of organolithium compounds, organozinc compounds, organomagnesium compounds and organoaluminum compounds. Of these, organoaluminum compounds are particularly preferable.

Examples of the organic aluminum compound include triethyl aluminum, tri-n-propyl aluminum, tri-isopropyl aluminum, tri-n-butyl aluminum,
Triisobutyl aluminum, tri-n-hexyl aluminum, tri-n-octyl aluminum, tri-n
-Decyl aluminum, tri-n-dodecyl aluminum, diethyl monochloro aluminum, dibutyl monochloro aluminum, di-n-hexyl monochloro aluminum, di-n-octyl monochloro aluminum, ethyl aluminum sesquichloride, n-butyl aluminum sesquichloride, ethyl aluminum dichloride ,
Examples thereof include n-butyl aluminum dichloride, isobutyl aluminum dichloride, n-hexyl aluminum dichloride, n-octyl aluminum dichloride and the like.

It is also possible to use reaction products of these organoaluminum compounds with alcohols, amines and the like.

For example, methanol, ethanol, n-butanol, isobutanol, t-butanol, n-hexanol, n
-Octanol, 2-ethyl-hexanol, n-decanol, triethylamine, tri-n-propylamine, tri-n-butylamine, tri-isobutylamine, tri-n-hexylamine, tri-n-octylamine, tri-2 -Ethylhexylamine, diethylamine, di-n-butylamine, di-isobutylamine, di-n-octylamine, di-2-ethylhexylamine, ethylamine, n-propylamine, n-butylamine, isobutylamine, 2-ethylhexylamine, etc. Is. The ratio of the organoaluminum compound to the reactant is 0.01 to 0.5, preferably 0.05 to 0.2 (molar ratio), based on the aluminum compound.

These organoaluminum compounds or the reaction products of the organoaluminum compounds can be used as a mixture of two or more kinds.

As the polymerization solvent, an inert hydrocarbon solvent such as n-hexane, n-heptane, n-octane, isooctane, n-decane, cyclohexane is used, and the polymerization temperature is usually about 0 to 80 ° C. .

The proportion of the above (B) copolymer rubber in 100 parts by weight of the composition is 5 to 45 parts by weight, preferably 10 to 40 parts by weight. If it is less than 5 parts by weight, the effect of improving impact resistance is small. On the other hand, if it exceeds 45 parts by weight, it becomes impossible to mix a large amount of the low molecular weight copolymer (C). That is, 45 parts by weight or more of the (B) copolymer rubber and 5 parts of the (C) low molecular weight copolymer.
If blended in an amount of more than 1 part by weight, problems such as surface texture and shrinkage of the molded product will occur, and (B) copolymer rubber in an amount of 45 parts by weight or more,
In the case of blending (C) the low molecular weight copolymer in an amount of 5 parts by weight or less, the effect of adding the (C) low molecular weight copolymer is small, and it is the same as simply mixing the (A) polypropylene resin and the (B) copolymer rubber. Therefore, the effect of the present invention cannot be obtained.

Next, the low molecular weight copolymer (C) of the present invention has a weight average molecular weight of 5,000 to 50,000, preferably 7,000 to 30,0.
If it is less than 5,000, the low molecular weight copolymer migrates to the surface of the molded product of the obtained resin composition with the passage of time, and stickiness occurs, as in the case of adding oil or a plasticizer. In addition to increasing stains by the bleeding phenomenon, it causes disadvantages such as a decrease in coating strength when coating is applied.On the other hand, when it exceeds 50,000, it softens somewhat compared to ordinary ethylene-propylene copolymers. Although the effect is high, the softening effect intended by the present invention cannot be achieved.

The weight average molecular weight (Mw) of the low molecular weight copolymer (C)
The ratio (Mw / Mn) to the number average molecular weight (Mn) is 2 to 5, preferably 2 to 4. If it is less than 2, it is difficult to produce a low molecular weight copolymer under ordinary production conditions. On the other hand, if it exceeds 5, on the other hand, there is no big difference in the softening effect, but the width of the molecular weight distribution is too wide and the low molecular weight components contained therein migrate to the molded product, and the weight average molecular weight is as described above.
The same disadvantages as in the case of blending a low molecular weight copolymer of less than 5,000 will result.

Further, the propylene content in the low molecular weight copolymer (C) is 30 to 75% by weight, preferably 35 to 65% by weight,
If it is less than 5% by weight, crystals of ethylene segment are formed and the softening effect is lowered, while if it exceeds 75% by weight, it is an economically disadvantageous production condition in the production method described later, which is not a good idea.

The (C) low molecular weight copolymer used in the resin composition of the present invention may be copolymerized with a non-conjugated diene similar to that used in the (B) copolymerized rubber in iodine value of about 20 or less. It is possible.

The (C) low-molecular weight copolymer can be obtained by the same production method as the (B) copolymerized rubber, but in order to obtain a low molecular weight (5,000 to 50,000), a vanadium compound is used as a catalyst component. A catalyst comprising a combination of a metal of Group I to IV of the periodic table with an organometallic compound is used.

As a vanadium compound, it is soluble in an inert organic solvent.
A pentavalent vanadium compound is used.

As the vanadium compound, a vanadium halide, an oxyhalide, a chelate complex with an oxygen-containing compound,
Vanadates and the like are preferable.

Specific examples of these compounds include vanadium tetrachloride, vanadium oxytrichloride, vanadium trisacetylacetonate, vanadic acid triethoxide, vanadic acid tri-n-butoxide, vanadic acid di-n-butoxymonochloride, vanadic acid. Examples thereof include reaction products of ethoxydichloride, vanadium tetrachloride or vanadium oxytrichloride and alcohol. These may be used alone or in admixture of two or more.

Among these compounds, more preferred are vanadium tetrachloride, vanadium oxytrichloride and reaction products of these vanadium compounds with alcohol.

Examples of the organometallic compound of a metal of groups I to IV of the periodic table include:
Mention may be made of organolithium compounds, organozinc compounds, organomagnesium compounds and organoaluminum compounds. Of these, organoaluminum compounds are particularly preferable.

As the organoaluminum compound, the same kind as the organoaluminum compound used in the production of the (B) copolymer rubber can be used.

For these catalyst components, a polyhalogen compound can be used as an activity improver.

Specific examples of the multi-halogen compound include trichloroacetic acid,
Examples include 2,3,4,4-tetrachlorobutenoic acid, 2,3,4,4-tetrachlorobutenoic acid ester, and hexachloroacetone.

As a polymerization solvent, n-hexane, n-heptane, n-
Inert hydrocarbons such as octane, isooctane, n-decane, and cyclohexane are used, and the polymerization temperature is about 0 to 80 ° C.

The α-olefin such as ethylene and propylene is brought into contact with the catalyst component as described above, and a chain transfer agent such as hydrogen or diethylzinc is further added to obtain a low molecular weight copolymer having a desired molecular weight.

Moreover, in order to set the molecular weight distribution (Mw / Mn) to 2 to 5,
The composition ratio (M / V) of the vanadium compound (V) and the organometallic compound (M) of a metal of Groups I to IV of the periodic table is 5 to 40.

The proportion of the low molecular weight copolymer (C) as described above in 100 parts by weight of the composition is 5 to 45 parts by weight, preferably 10 to 40 parts by weight.
If it is less than 5 parts by weight, the softening effect is small, while if it exceeds 45 parts by weight, it becomes too soft and the surface of the molded product is easily scratched, which is not preferable.

The resin composition of the present invention can be produced by a commonly used method of mixing a polypropylene resin and a copolymer rubber. For example, the polypropylene resin (A) used in the present invention, the copolymer rubber (B) and the low molecular weight copolymer (C) are melted and mixed by using an extruder, a kneader blender, a Banbury mixer, or the like, or The order of the mixing method is such that (C) the low molecular weight copolymer is mixed in advance with (B) the copolymer rubber, (A) polypropylene resin is added, and the mixture is melted and mixed by using a Banbury mixer, a kneader blender or the like. It is not limited, and after kneading, pelletized by a commonly used method, and finally the ratio of (A) polypropylene resin, (B) copolymer rubber, (C) low molecular weight copolymer is A molded article comprising the resin composition of the present invention can be obtained within the scope of the present invention.

The resin composition of the present invention may also be added with a conventional auxiliary additive component such as an antioxidant, a heat stabilizer, an ultraviolet absorber and a colorant. Also, calcium carbonate, kaolin,
Fillers such as talc, asbestos and glass fiber, olefin (co) polymer rubbers other than the (B) copolymer rubber or (C) low molecular weight copolymer used in the present invention (eg EP
R, ethylene-butene copolymer, polyisobutylene, etc.), polyethylene resin, polystyrene resin, acrylonitrile-butadiene-styrene copolymer resin, ethylene-vinyl acetate copolymer resin, polybutadiene resin, etc. The amount of addition is preferably 0 to 40 parts by weight with respect to 100 parts by weight of the resin composition of the present invention.

The polypropylene resin composition of the present invention thus obtained is useful for automobile interior and exterior parts, particularly bumpers, inner panels, dashboards and the like.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples as long as the gist thereof is not exceeded.

Parts and% in the examples are by weight unless otherwise specified.

Further, various measuring methods are as follows.

The α-olefin content in the (B) copolymer rubber was measured using an infrared spectrophotometer and 100 MHz ₁ H-NMR.

The weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured as follows according to Takeuchi, Gel Permeation Chromatograph, published by Maruzen Co., Ltd.

Standard polystyrene with known molecular weight (Toyo Soda Co., Ltd.)
Manufactured by monodisperse polystyrene) and its molecular weight M and its
GPC (Gel Permeation Chromatograph) count is measured, and a correlation diagram calibration curve of molecular weight M and EV (Elution Volume) is drawn. The concentration at this time is 0.02% by weight.

The calibration curve of standard polystyrene is corrected to the calibration curve of EP (D) M (ethylene-α-olefin copolymer rubber by the universal method.

The GPC pattern of the sample is taken by the GPC measurement method, and the molecular weight M is known from the above. Sample preparation conditions and
The GPC measurement conditions are as follows.

Sample preparation (a) Anti-aging agent in o-dichlorobenzene solvent
0.08% by weight of 2,6-di-t-butyl-p-cresol is added and dissolved.

(B) A sample is put together with an o-dichlorobenzene solvent in an Erlenmeyer flask so that the sample becomes 0.1% by weight.

(C) The Erlenmeyer flask is heated to 120 ° C. and stirred for about 60 minutes to dissolve it.

(D) Apply the solution to GPC. In addition, it is automatically filtered in a GPC device with a sintered filter having a pore size of 0.5 μm.

GPC measurement conditions (a) Apparatus: Waters Co., Ltd. 150C type (b) Column: Toyo Soda Co., Ltd., H type (c) Sample amount; 500μ (d) Temperature; 135 ° C (e) Flow velocity; (F) Total theoretical plate number of column; 1 × 10 ⁴ to 2 × 10 ⁴ (measured value with acetone) Mw / Mn was calculated from the above results.

The propylene content and iodine value of the low molecular weight copolymer (C) were determined by the KBr tablet method using an infrared spectrophotometer.

Mooney viscosity (ML _{1 + 4} , 100 ° C) conforms to JIS K6300,
Preheating was performed for 1 minute, measurement for 4 minutes, and temperature at 100 ° C.

Izod impact strength (with notch) is measured according to JIS K7110.

Flexural modulus is measured according to JIS K7203.

The surface gloss was measured according to JIS K7105.

The hardness was measured according to JIS K 7202.

Bleed property is polypropylene resin composition 110 × 50m
m, 2 mm thick plate was injection molded (for injection molding conditions, see Example 1), aged in a constant temperature bath at 80 ° C. for 100 hours, and whether or not there was a bleed on the plate surface after aging. Then, visual inspection was carried out, and it was judged according to the following criteria.

Fogging on the plate surface is severe; XX Fogging on the plate surface is noticeable; X Fogging on the plate surface; △ Slight fogging on the plate surface; ○ No fogging on the plate surface; ◎ Example 1 (C) Manufacture of low molecular weight copolymer After replacing a continuous polymerization reactor made of stainless steel with an internal volume of 10 with nitrogen gas, dehydrated and deoxygenated n-hexane was placed in this device for 4 hours. Introduced continuously. Then, sufficiently dry ethylene gas, propylene gas and hydrogen gas were adjusted so that the pressure was 7 kg / cm ² G and the gas phase ethylene / propylene / hydrogen gas was 8/14/78 mol%, and the temperature was 45 ° C. While maintaining the temperature, vanadium oxytrichloride (VOCl ₃ ) was 3.5 mmol / hour, and ethylaluminum sesquichloride [(C ₂ H ₅ ) _1.5 AlCl _1.5 ] was 28 mmol / hour.
Contacted for a time.

Next, while keeping the liquid level in the reactor at 4, the reaction product was continuously taken out, a small amount of n-butyl alcohol was added to stop the reaction, and a small amount of an antioxidant (2,6-di-t- -Butyl-p-cresol) was added.

The obtained reaction product was placed in an evaporation kettle equipped with a stainless steel jacket and heated to 40 to 50 ° C. to remove n-hexane under reduced pressure.

From the amount of the recovered low molecular weight copolymer,
It was found that a low molecular weight copolymer was obtained at a rate of 310 g / hour.

The propylene content of this low molecular weight copolymer was 45%, the weight average molecular weight (Mw) was 15,000, and Mw / Mn was 2.8.

Manufacture of polypropylene resin composition (A) polypropylene resin as a component, manufactured by Mitsubishi Yuka Kogyo Co., Ltd., 80 parts of Noblen BC-2, and (B) component manufactured by Japan Synthetic Rubber Co., Ltd., EP02P [Moonie viscosity] (M
L _{1 + 4} , 100 ° C.) = 24] and 10 parts of (C) the low molecular weight copolymer obtained above were mixed with 4 Banbury mixer (manufactured by Godo Heavy Industries Co., Ltd., 30 horsepower, 4 tests). (Banbury), rotor speed 70 rpm, preheat temperature 120
The kneading was carried out at 0 ° C., a ram pressure of 4 kg / cm ² , and a kneading time of 5 minutes.
After kneading, pelletizing was performed with a pelletizer, and then a test piece was produced with a 6.5 ounce injection molding machine (produced by Nippon Steel Co., Ltd., 6.5 ounce in-line screw type).

The injection molding conditions are shown below.

The results of the physical property test are shown in Table 1.

Injection pressure; Primary pressure 500kg / cm ² Secondary pressure 400kg / cm ² Injection time; Primary pressure + secondary pressure 15 seconds Molding temperature; 240 ° C cooling time; 40 ° C cooling time; 20 seconds Comparative Example 1 In Example 1 , (B) component EP02P 16 times,
A polypropylene resin composition was prepared in the same manner as in Example 1 except that the same low-molecular weight copolymer as the component (C) was used in the same amount as in Example 1, and the physical properties were tested.
The results are shown in Table 1.

In comparison between Example 1 and Comparative Example 1, the soft polypropylene resin composition in which the low molecular weight copolymer (C) of the present invention was blended in a specific amount had a large flexural modulus even though the polypropylene resin was blended in the same amount. It was found to be extremely low and the softening effect was great.

Example 2 (C) Production of low-molecular weight copolymer Using the same apparatus and method as in the production of the low-molecular weight copolymer of Example 1, 5-ethylidene-2-norbornene was added to 0.2%.
A low molecular weight copolymer (C) was produced in the same manner as in Example 1 except that the compound was continuously introduced at a rate of 23 g / hour.

From the recovered low molecular weight copolymer, 240 g in the polymerization reaction
It was found that a low molecular weight copolymer was obtained at a ratio of / hour.

The propylene content in this (C) low molecular weight copolymer is 50
%, The weight average molecular weight (Mw) was 14,000, and Mw / Mn was 2.9.

Production of Polypropylene Resin Composition Polypropylene in the same manner as in Example 1 except that the low molecular weight copolymer of the component (C) of Example 1 was replaced with the low molecular weight copolymer obtained as described above. A resin composition was prepared and a physical property test was conducted.

The results are shown in Table 1.

From Table 1, it can be seen that the resin composition of this example has a lower flexural modulus than that of Comparative Example 1, and that the softening effect is large by incorporating the low molecular weight copolymer.

Example 3 and Comparative Example 2 In producing a soft polypropylene resin composition,
The components (A) and (C) used were the same as those used in Example 1, and the amount of n-hexane introduced was the same as that used in the production of the low molecular weight copolymer of Example 1 as the component (B). 5
/ Hour, the composition of the gas phase is 44/44/12 (mol%), vanadium oxytrichloride is 2.8 mmol / hour, ethylaluminum sesquichloride is continuously polymerized under the conditions of 20 mmol / hour, and after the polymerization reaction , The product contains a small amount of n-butyl alcohol and an antioxidant (2,6-di-t-butyl-p
-Cresol) was added, and the solvent was blown in by a usual method to remove the solvent, and then the solid was dried with a roll at 100 ° C to obtain (B) a copolymer rubber (propylene content = 50%, Mooney viscosity = 27). ) Was used to prepare a soft polypropylene resin composition by the same method as in Example 1 and a physical property test was conducted (Example 3).

Further, as Comparative Example 2, a polypropylene resin composition was prepared without adding the component (C), and a physical property test was conducted. The results are shown together in Table 2.

From Table 2, it can be seen that in contrast to Comparative Example 2, Example 3, which is the resin composition of the present invention, has a high softening effect and excellent impact resistance.

Examples 4 to 5 and Comparative Examples 3 to 4 As the component (B), a copolymer rubber having propylene as an α-olefin, a propylene content of 26% and a Mooney viscosity of 70 is used, and the component (C) is produced in Example 1. The soft polypropylene resin composition was produced in the same manner as in Example 1 by using the above low molecular weight copolymer and varying the amount thereof (Examples 4 to 5).

On the other hand, as a comparative example, paraffin oil (Idemitsu Kosan Co., Ltd.) was used instead of the low molecular weight copolymer as the component (C).
Manufactured by Diana Process PW-380) in the same manner as in Example 1 to obtain a polypropylene resin composition. The results of these physical property tests are also shown in Table 2.

It can be seen from Table 2 that the composition of the present invention has the same softening effect as that of the comparative example using paraffin oil which is a general softening agent, but is excellent in impact resistance and bleeding property. .

Examples 6 to 10 and Comparative Examples 5 to 8 In Example 1, the composition of the component (C), molecular weight, Mw / Mn
Was changed to obtain a polypropylene resin composition in the same manner as in Example 1.

The component (C) was produced by adjusting the monomer composition and the amount of catalyst in the same manner as in the low molecular weight copolymer (C) of Example 1. The results of physical property tests of these compositions are shown in Table 3.

[Effects of the Invention] The polypropylene resin composition of the present invention is softer and more excellent in impact resistance, especially low temperature impact resistance, and bleeding occurs as compared with the conventional composition comprising polypropylene resin and ethylene-propylene rubber. It is difficult to use and is useful for automobile interior and exterior parts, especially bumper, inner panel, dashboard and other applications.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenya Makino 2-11-24 Tsukiji, Chuo-ku, Tokyo Within Nippon Synthetic Rubber Co., Ltd. (56) Reference JP-A-60-202137 (JP, A)

Claims (2)

[Claims] 1. (A) 50 to 90 parts by weight of a polypropylene resin, (B) 5 to 45 parts by weight of an ethylene-α-olefin copolymer rubber having a Mooney viscosity (ML _{1 + 4} , 100 ° C.) of 10 to 150. , And (C) the weight average molecular weight (Mw) is 5,000 to 50,000, and the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) (Mw / M
n) is 2 to 5 and the content of α-olefin is 30 to 75% by weight. Low molecular weight ethylene-α-olefin copolymer 5 to 45 parts by weight (however, (A) + (B) + (C)) = 100
Parts by weight]. A polypropylene resin composition for automobile interior and exterior parts. 2. The ethylene-α-olefin copolymer rubber (B), wherein the α-olefin is propylene and / or butene-1, and the α-olefin content is 15 to 80% by weight.
The polypropylene resin composition for automobile interior / exterior parts according to claim 1.