JPH0859953A - Polypropylene resin composition for automobile interior materials - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a polypropylene resin composition for automobile interior materials, which has excellent balance between rigidity and low temperature embrittlement temperature and also has excellent fluidity. [Structure] Ethylene having an average intrinsic viscosity ([η]) of the ethylene-propylene copolymer part of 7 to 12 g / dl
Propylene block copolymer (A) 95 to 85% by weight,
And an inorganic filler (B) having an average particle size of 1 to 4 μm 5
A polypropylene resin composition comprising 15% by weight and having a melt index (MI) of 15
~ 40g / 10min, flexural modulus (FM) is 2
300 to 3000 MPa, low temperature embrittlement temperature (LB)
Is less than 30 ° C., and the relation between FM and LB satisfies the inequality: FM> 8.4 × LB + 2300. A polypropylene resin composition for automobile interior materials.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polypropylene resin composition for automobile interior materials, which has excellent balance between rigidity and low temperature embrittlement temperature and is excellent in fluidity.

[0002]

2. Description of the Related Art In recent years, it has been required to reduce the weight of parts used in automobiles in order to reduce the fuel consumption of automobiles. By reducing the weight of automobiles, it is possible to reduce the amount of exhaust gas and the amount of carbon dioxide gas released into the atmosphere, resulting in conservation of the global environment. As a method of reducing the weight of parts such as automobiles, a method of reducing the specific gravity of the material, a method of increasing the rigidity to the extent that the impact strength is not significantly decreased, and reducing the product thickness, etc. are conceivable. The method is most desirable because it can reduce the cost of the molding material, and in the case of injection molding, the thinning reduces the cooling efficiency and improves the productivity. However, in the injection molding method, there is a limit to the thinning due to the fluidity of the resin and the performance of the molding machine. For example, a material with poor fluidity requires a large pressure when pouring resin into a narrow gap in a mold, and problems such as mold opening may occur unless a molding machine with excellent injection pressure and mold clamping pressure is used. . However, a molding machine with a high mold clamping pressure becomes large, expensive, and requires a large installation area, which is not economical.

On the other hand, regarding the fluidity of the resin, the usual injection molding material has a melt index of 2 to 15 g / 10 m.
It is generally in the range of in, and when thinning, the polypropylene resin composition has a melt index of 15 g.
/ 10 min or more is required. As a method of increasing the fluidity of the resin, a method of lowering the molecular weight of the resin is usually taken, but when the molecular weight of the resin is reduced, impact strength, tensile elongation at break, deterioration of mechanical properties such as low temperature embrittlement temperature may occur. It is easy to occur. In order to prevent such a decrease in impact strength, conventionally, an ethylene-propylene block copolymer was used as polypropylene, and further, in order to increase the impact strength by lowering the molecular weight of the homo portion to improve the fluidity. This has been dealt with by increasing the molecular weight of the copolymerization part. However, if the molecular weight of the homo-part becomes too low, the impact strength, especially the room temperature Izod impact strength, will drop sharply. Therefore, as disclosed in JP-A-5-98126, JP-A-5-98127, and the like, a material excellent in impact strength containing a large amount of a rubber component in an exterior material such as a bumper of an automobile. Has been used. Further, in JP-A-3-197549, a crystalline ethylene-propylene block copolymer and a thermoplastic elastomer having a saturated main chain (for example, ethylene-propylene copolymer rubber), and an inorganic filler (for example, talc, etc.) are disclosed. ) Is disclosed as a main component of the polypropylene resin composition having improved paintability. Further, in JP-A-5-98122, the melt index is 30 to 120 g / 10 mi.
n ethylene-propylene block copolymer, a binary copolymer elastomer of ethylene and propylene or butene-1, and a copolymer elastomer selected from the ternary copolymer of these with cyclopentadiene or ethylidene norbornene, and A polypropylene resin composition containing an inorganic filler is disclosed. Such a bumper material is sufficiently improved in not only Izod impact strength but also low temperature embrittlement temperature by a large amount of rubber.

On the other hand, JP-A-58-83015 discloses that an ethylene-propylene block copolymer having excellent impact resistance has an ethylene / propylene ratio of 60/4 in the copolymerized portion.
0 to 95/5, and further, the intrinsic viscosity [η] of the copolymerization part
Has been proposed. Further, in the examples, a two-stage polymerization of a copolymerization section is disclosed in which the blowing amount of ethylene is increased in the latter half of the polymerization of the copolymerization section.

[0005]

However, since such a material contains a large amount of rubber, it has a low rigidity and is easily scratched unless a strong coating is applied on the surface. It couldn't be used on the part that was not painted or was unpainted at all. Further, since the price of rubber is higher than that of polypropylene, the raw material cost is high and the price of the product may be high. Although it is possible to increase the impact strength by increasing the amount of filler and adding rubber to that extent, the specific gravity increased by that amount and the material was not made lighter. An object of the present invention is to provide a polypropylene resin composition for automobile interior materials, which has an excellent balance of rigidity and low temperature embrittlement temperature and also has excellent fluidity.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that compared with ethylene-propylene block copolymers that have been conventionally used as polypropylene for interior materials. The inventors have found that a material having an excellent balance of rigidity, low temperature embrittlement temperature, and fluidity can be obtained by using an ethylene-propylene block copolymer having a high average intrinsic viscosity of the copolymerized portion, and arrived at the present invention. That is, the polypropylene resin composition for automobile interior materials of the present invention has an ethylene-propylene block copolymer (A) 95- having an average intrinsic viscosity ([η]) of the ethylene-propylene copolymer portion of 7-12 g / dl. A polypropylene resin composition comprising 85% by weight and 5 to 15% by weight of an inorganic filler (B) having an average particle size of 1 to 4 μm, and the melt index (MI) of the resin composition is 15 to 40 g / 10m
and the flexural modulus (FM) is 2300-3000.
MPa, the low temperature embrittlement temperature (LB) is less than 30 ° C., and the relationship between FM and LB satisfies the inequality: FM> 8.4 × LB + 2300.

The ethylene-propylene block copolymer (A) used in the polypropylene resin composition of the present invention has an average value of intrinsic viscosity (hereinafter abbreviated as [η]) of its copolymerized portion, that is, an average [η]. 7-12 g / dl, preferably 8
10 to 10 g / dl. When the average [η] of the copolymerized part is less than 7 g / dl, the low temperature embrittlement temperature is not sufficiently low,
Impact strength is not sufficient. Further, if it exceeds 12 g / dl, it is difficult to finely disperse the copolymerized portion in the matrix of homopolypropylene during melt-kneading, the room temperature Izod impact strength is not sufficient, and further it is easily decomposed by heat so that it can be recycled. The fluidity and impact strength change with each recycling, and stable recycling cannot be achieved.

In the ethylene-propylene block copolymer (A), the weight ratio of ethylene / propylene in the copolymerized portion is preferably in the range of 0.8 to 2.0. However, in that range, when the ethylene / propylene weight ratio is lower, the tensile elongation at break and the room temperature Izod impact strength are excellent, but the low temperature Izod impact strength, the low temperature embrittlement temperature, and the rigidity are poor, and the ethylene / propylene When the weight ratio of propylene is higher, the low temperature Izod impact strength, the low temperature embrittlement temperature and the rigidity are excellent, but the tensile elongation at break and the room temperature Izod impact strength are poor.

Further, if the copolymer has a high fluidity and the copolymer part has a high molecular weight, the homo part needs to have a very low molecular weight. Therefore, usually, when polymerizing the homo-part, a large amount of hydrogen is blown to lower the molecular weight, but when polymerizing the copolymerized part having a high molecular weight continuously, degassing of the hydrogen blown during the homo-part polymerization is sufficient. Otherwise, it is difficult to adjust the molecular weight by adjusting the hydrogen concentration when polymerizing the high molecular weight copolymerized portion, and it is difficult to obtain the copolymerized portion having excellent performance. Also, the polymerization time becomes long and the yield is poor. The ethylene-propylene block copolymer (A) may be polymerized in two stages, the low molecular weight copolymerization part may be polymerized in the first half and the high molecular weight copolymerization part may be polymerized in the second half. The polymer (A) is polymerized in three stages, in which case the first stage polymerization product (C
The ethylene / propylene weight ratio of the copolymerized portion of 1) is 0.1.
5 to 1.2, the ethylene / propylene weight ratio of the copolymerization part of the second stage polymerization product (C2) is 0.9 to 2.0, and the copolymerization ratio of the third stage polymerization product (C3) is Polymerization part of ethylene /
The weight ratio of propylene is 1.5 to 3.0, and C2 + C3
The ethylene / propylene weight ratio of the copolymerization part of is 1.3-
2.5, the ratio of C1 to (C1 + C2 + C3) is 30 to 60% by weight, and the ratio of C2 is 20 to 50.
The polymer which is polymerized so that the C3 ratio is 20 to 50% by weight is more flexible in bending elasticity, impact strength and elongation than the one obtained by polymerizing the ethylene-propylene block copolymer in one or two steps. It is preferable because it has an excellent flowability balance.

The ethylene / propylene weight ratio value of the C2 copolymerization portion is 1.1 to 2 times the ethylene / propylene weight ratio value of the C1 copolymerization portion, and the ethylene / propylene weight ratio value of the C2 copolymerization portion is The value of the weight ratio of propylene is preferably 0.9 to 0.5 times the value of the weight ratio of ethylene / propylene in the C3 copolymerization part. When the ethylene / propylene weight ratio of the C1 copolymerization part is less than 0.5 or (C1 + C2 + C
When the ratio of C1 to 3) exceeds 60% by weight, the low temperature embrittlement temperature and the rigidity are not always sufficient,
When the ethylene / propylene weight ratio of the C3 copolymerized portion exceeds 3.0 or the ratio of C1 to (C1 + C2 + C3) is less than 30% by weight, tensile elongation at break and room temperature Izod impact strength are high. Not always enough. If the ethylene / propylene weight ratio of the C1 copolymerization portion exceeds 1.5 or if the ethylene / propylene weight ratio of the C3 copolymerization portion is less than 1.5, a one-stage polymerization of the copolymerization portion is carried out. There is no advantage compared to. When the ethylene / propylene weight ratio of the C2 copolymerized portion is less than 0.9, it is difficult to stably polymerize C3, resulting in poor low temperature impact strength, and the C2 copolymerized portion. In order for the ethylene / propylene weight ratio of above to exceed 2.0, it is necessary to blow a large amount of ethylene after polymerizing C1, and as a result, the ethylene component increases and the ultra high molecular weight that cannot be sufficiently dispersed during pelletization. In some cases, the copolymer (1) is by-produced and the tensile elongation at break is inferior. Copolymerization part (C1
+ C2 + C3) preferably accounts for 15 to 25% by weight in the ethylene-propylene block copolymer (A), and if less than 15% by weight, low temperature Izod impact strength, low temperature embrittlement temperature, tensile elongation at break. Is not sufficient, and when it exceeds 25% by weight, the polypropylene powder is apt to become sticky, so that problems are likely to occur in the steps of post-treatment after polymerization, mixing with filler, and pelletization.

Regarding the average [η] of the homo part of the ethylene-propylene block copolymer (A) used in the polypropylene resin composition of the present invention, when a filler is added and pelletized, MI is 15 g / 10 min or more, Preferably 20 g / 10 min or more, more preferably 25 g /
It is selected to be 10 min or more, and most preferably 30 g / 10 min or more. If it is less than 15 g / 10 min, the fluidity is insufficient and it is not suitable for thinning. Further, the upper limit thereof is not particularly specified, but is preferably 40 g / 10 min or less in view of problems such as burrs during injection molding.
Regarding the stereoregularity of the homo portion, those having [mmmm] of 97% or more have excellent rigidity.

The ethylene-propylene block copolymer (A) used in the polypropylene resin composition of the present invention is obtained by any of ordinary slurry polymerization method, bulk polymerization method and gas phase polymerization method. It can be used even if it exists, but especially when polymerized by the slurry polymerization method, atactic polypropylene, a low molecular weight isotactic polypropylene, and a low molecular weight copolymer that reduce the balance of rigidity, heat resistance and room temperature Izod impact strength, low temperature embrittlement temperature Since the polymerized part is removed by the solvent, the most excellent ethylene-propylene block copolymer is obtained, which is preferable. The polypropylene resin composition of the present invention contains 95 to 85% by weight of the ethylene-propylene block copolymer (A). The content of the ethylene-propylene block copolymer (A) is determined by the required amount of the inorganic filler used together,
The reason for the limitation is as described below.

The inorganic filler used in the polypropylene resin composition of the present invention has an average particle size of 1 to 4 μm, preferably 1
˜3 μm, more preferably 1.5 to 2.5 μm, most preferably 1.8 to 2.3 μm, and such inorganic fillers include talc, calcium carbonate, carbon black, silica, clay, Potassium titanate, magnesium carbonate and the like are used, and talc is preferably used. An inorganic filler having an average particle size of less than 1 μm is not preferable because it lowers the rigidity. Further, it is not preferable to use an inorganic filler having an average particle size of more than 4 μm, because it is inferior in Izod impact strength, low temperature embrittlement temperature, and tensile elongation at break. It is also possible to use fibrous fillers such as magnesium sulfate whiskers and potassium titanate whiskers as the inorganic fillers in whole or in part as long as the anisotropy of the molding shrinkage is not a serious problem. 5 to 15 for inorganic filler
% By weight, preferably 7 to 13% by weight, more preferably 8
~ 12 wt%, most preferably 9-12 wt%. If the amount added is less than 5% by weight, the rigidity becomes insufficient when the wall is thinned. On the other hand, when it exceeds 15% by weight, the effect of weight reduction is not obtained as compared with the conventional automobile interior material, and the flow marks and weld lines are apt to stand out.

The polypropylene resin composition of the present invention has the above-mentioned composition, in which the flexural modulus thereof exceeds 2300 MPa, preferably exceeds 2300 MPa and 3000 MPa or less, more preferably 2350 to.
2800 MPa, most preferably 2400-2700 M
Those having Pa are selected to be the subject of the present invention. Since the polypropylene resin composition of the present invention is used for automobile interior materials, when the bending elastic modulus is 2300 MPa or less, problems such as depression by pushing with a finger are likely to occur, and the commercial value is reduced.

Further, the polypropylene resin composition of the present invention has a flexural modulus (FM) (unit: MPa) and a low temperature embrittlement temperature (LB) (unit: ° C) of FM> 8.4 × LB + 2300, and It is necessary that the composition has a relationship of LB <30. In a polypropylene resin composition having a high low-temperature brittleness temperature such that the value on the right side of the above equation exceeds the flexural modulus (FM), the flexural modulus and the low-temperature brittleness temperature are not well balanced, and the assembly in a low temperature state is difficult. Parts may be damaged during work. If the low temperature embrittlement temperature is 30 ° C. or higher, the product becomes brittle and cannot be used as an automobile interior material.

In the present invention, in addition to the ethylene-propylene block copolymer (A), other resins may be blended as long as the physical properties are not significantly deteriorated. Examples of such resins include ethylene-propylene copolymer elastomer (EPR), ethylene-propylene-diene copolymer elastomer (EPDM), ethylene-butene-1 copolymer elastomer (EBM), ultra-low density polyethylene, styrene- Examples thereof include a butadiene block copolymer elastomer, a styrene-butadiene random copolymer elastomer, and a styrene-isoprene block copolymer elastomer.

In the polypropylene resin composition of the present invention, the weather resistance improver, heat resistance improver, dispersant, pigment and the like which have been used in conventional interior materials for automobiles can be used as they are. Regarding the polypropylene resin composition of the present invention, polypropylene, an inorganic filler and various additives are mixed by a ribbon blender, a Henschel mixer, and the like, and then melt-kneaded and pelletized by a device such as a Banbury mixer, a heat roll, an extruder, and a kneader. After that, the conventional manufacturing method of injection molding is available.

The polypropylene resin composition of the present invention is used as an automobile interior material. What is an automobile interior material?
Examples include front pillars, center pillars, rear pillars, door trims, armrests, and console boxes. Such an interior material can be molded by usual injection molding under normal conditions. It is preferable that these automobile parts are excellent in Izod impact strength and tensile elongation at break in addition to the low temperature embrittlement temperature in order to cope with impact during assembly and the like during use in automobiles. For example, the Izod impact strength at 23 ° C is 4 kg / cm ² or more, more preferably 5 kg / cm ² ,
Most preferably, it is 6 kg / cm ² or more, and the tensile elongation at break is 3
It is 0% or more, more preferably 100% or more, and most preferably 300% or more.

[0019]

EXAMPLES The present invention will be described in detail below with reference to production examples and examples. Production Example of Ethylene-Propylene Block Copolymer 100 liters of heptane was charged in a 250 liters volume autoclave made of SUS in a nitrogen stream, and the inside of the polymerization system was replaced with propylene. On the other hand, it consists of a supported catalyst component, triethylaluminum, and cyclohexylmethyldimethoxysilane, which was obtained by adding heptanes to another glass container, adding diethyl phthalate to magnesium chloride, and pulverizing the pulverized product, which was heat-treated with titanium tetrachloride and then washed. Prepare a catalyst, charge it in an autoclave, and set the temperature to 75 ℃ and the pressure to 5kg.
Polymerization was carried out for 4 hours under the condition of / cm ² (gauge pressure). During that time, the hydrogen partial pressure is adjusted to adjust the [η] of the produced polypropylene.
Was set to about 1. In this way, a propylene homopolymer part was obtained. Then, the inside of the autoclave was decompressed with a vacuum pump to remove the residual propylene and hydrogen, and under the conditions of a polymerization temperature of 50 ° C. and a polymerization pressure of 1.8 kg / cm ² (gauge pressure), the copolymer produced in the copolymerization section Ethylene (EL)
/ Propylene (PL) weight ratio is 1.5 and [η] is about 9
The partial pressures of EL, PL, and hydrogen in the gas phase were adjusted so that the reaction was carried out, and the polymerization was carried out for 2 hours. The ethylene-propylene block copolymer PP-1 shown in Table 1 was obtained by carrying out the polymerization so that the ratio of the produced polymer in the copolymerization portion to the total polymer was about 18% by weight.

In the above-mentioned polymerization method, the polymerization is carried out by changing the hydrogen concentration when forming the propylene homopolymerization part, the EL / PL weight ratio when forming the propylene-ethylene copolymerization part and the hydrogen concentration. Ethylene-propylene block copolymers PP-2 to PP shown in Table 1
-6, PP-9 and PP-10 were obtained. In the above-mentioned polymerization method, the polymerization at the time of producing the propylene-ethylene copolymerization part is three-stage polymerization, and the weight ratio of EL / PL is increased in the latter part so that the ethylene-propylene block copolymer PP- shown in Table 1 is obtained. 7, PP-8 and PP-11 were obtained.

Compositions of ethylene-propylene block copolymers PP-1 to PP-11 obtained by the above-mentioned methods,
The characteristic values are summarized in Table 1. These ethylene-propylene block copolymers were used in the following examples and comparative examples.
In addition, in the following Table 1, Table 2 and Table 3, the homo-part [η] of the polypropylene, the average [η] of the copolymerization part, the [η1] of the copolymerization part of the first-stage polymerization product C1, the Two-stage polymerization product C
[Η2] of the copolymerization part of No. 2 and [η3] of the copolymerization part of the third stage polymerization product C3 are the intrinsic viscosities measured by sampling the polymer at the time when the homopolymerization is completed, Intrinsic viscosity measured by sampling the polymer at the end of the polymerization,
Obtained from the intrinsic viscosity measured by collecting the polymer at the time when the polymerization of the C2 component was completed and the intrinsic viscosity measured by collecting the polymer at the time when the polymerization of the C3 component was completed, the homo-part [mmm
m] is measured by ¹³ C-NMR, MI is ASTM
The flexural modulus was measured by the D-1238 method (load 2.16 kg), and the flexural modulus was determined by ASTM D-790 (bending speed 2 mm / m.
in) method, and the Izod impact strength at 23 ° C and -30 ° C is measured according to ASTM D-
The tensile breaking elongation is measured according to the ASTM method D-638 (tensile speed 10 mm / mi).
n), the low temperature embrittlement temperature is ASTM D-74.
It was measured by method 6. The average particle size of the inorganic filler was measured by a laser diffraction particle size distribution measuring method (measuring device: Shimadzu SALD-2000A). In addition,
Regarding the EL / PL weight ratio of the copolymerization part, the weight ratio of the first-stage polymerization product C1 is E / P1, the weight ratio of the second-stage polymerization product C2 is E / P2, and the third-stage polymerization product C3 is E weight ratio
It was described as / P3. The total amount FrTo of the amount of the copolymerized portion, the average [η] that is the average value of the copolymerized portion [η], and the average value E / PAv of the weight ratio of EL / PL of the copolymerized portion were calculated by the following formulas. What is: FrTo = C1 + C2 + C3, average [η] = (C1 × [η1] + C2 × [η2] + C3 × [η3]) / (C
1 + C2 + C3), E / PAv = (C1 × E / P1 + C2 × E / P2 + C3 × E / P3) / (C
1 + C2 + C3).

Examples 1 to 92 92 parts by weight of any of ethylene-propylene block copolymers PP-1 to PP-3 obtained by the slurry polymerization method, talc "LMS300" (manufactured by Fuji Talc Co., Ltd., average particle size) 8 parts by weight of 2 μm, abbreviated as talc 1 hereinafter), 0.05 parts by weight of “Ionol” as a heat stabilizer, 0.1 parts by weight of “Irganox 1010”, and 0.1 parts by weight of calcium stearate as a dispersant, a Henschel mixer. After mixing with, a 36 mm twinning extruder with a kneading desk was used to extrude pellets under the extrusion conditions of 220 ° C and 15 kg / hr to obtain pellets, and a test piece for measuring physical properties was measured using an injection molding machine with a mold clamping pressure of 100 tons. Then, the physical properties were measured. In Table 2, the mixing ratio of the ethylene-propylene block copolymer and talc, the MI of the resulting resin composition, the flexural modulus, the 23 ° C Izod impact strength, the -30 ° C Izod impact strength, the tensile elongation at break, and the low temperature brittleness. The temperature and specific gravity are shown.

Comparative Examples 1 and 2 Ethylene-containing copolymers having an average [η] of 15 and 4 respectively
Pelletizing and molding in the same manner as in Example 1 except that the propylene block copolymers PP-4 and PP-5 were used,
A test piece for measuring physical properties was obtained and the physical properties were measured. Table 2 shows the mixing ratio of ethylene-propylene block copolymer and talc, MI of the resin composition, flexural modulus, 23 ° C Izod impact strength, -30 ° C Izod impact strength, tensile elongation at break, low temperature embrittlement. Indicates temperature and specific gravity. Ethylene-propylene block copolymer PP-4 having [η] of 15 in the copolymerization part
The resin composition obtained by using the above is inferior in tensile elongation at break and 23 ° C. Izod impact strength, and a resin obtained by using the ethylene-propylene block copolymer PP-5 having [η] of 4 in the copolymerization part. The composition was inferior in tensile elongation at break, 23 ° C. Izod impact strength, −30 ° C. Izod impact strength and low temperature embrittlement temperature.

Comparative Example 3 As an example in which MI is out of the range of the present invention, [η] in the homo region is
And the stereoregularity is almost the same as that of ordinary polypropylene, except that the ethylene-propylene block copolymer PP-6 was used, pelletized and molded in the same manner as in Example 1, and a test piece for measuring physical properties was obtained. Was measured. Table 2 shows the mixing ratio of ethylene-propylene block copolymer and talc, MI of the resin composition, flexural modulus, 23 ° C Izod impact strength, -30 ° C Izod impact strength, tensile elongation at break, low temperature embrittlement. Indicates temperature and specific gravity. The homoregularity of the homo region was low and the flexural modulus was low. Further, the low temperature embrittlement temperature and the -30 ° C Izod impact strength were also low. Furthermore M
I was low, and flow marks were generated during molding.

Comparative Example 4 Talc “80R” (made by Asada Flour Milling) having an average particle size of 9 μm
Pellets were molded in the same manner as in Example 1 except that talc (hereinafter abbreviated as talc 2) was used, and a test piece for measuring physical properties was obtained to measure physical properties. Table 2 shows the mixing ratio of ethylene-propylene block copolymer and talc, MI of the resin composition, flexural modulus, 23 ° C Izod impact strength, -30 ° C Izod impact strength, tensile elongation at break, low temperature embrittlement. Indicates temperature and specific gravity. It was inferior to the resin composition of Example 1 in tensile elongation at break, 23 ° C. Izod impact strength, −30 ° C. Izod impact strength and low temperature embrittlement temperature.

Comparative Example 5 Talc having an average particle size of 0.7 μm (hereinafter abbreviated as talc 3) was sampled from a talc “FFR” (made by Asada Flour Milling) having an average particle size of 1.5 μm and used. Other than the above, pelletization and molding were performed in the same manner as in Example 1 to obtain a test piece for measuring physical properties, and physical properties were measured. Table 2 shows the blending ratio of the ethylene-propylene block copolymer and talc, the MI of the resulting resin composition, the flexural modulus, the 23 ° C. Izod impact strength,
-30 ° C Izod impact strength, tensile elongation at break, low temperature embrittlement temperature, and specific gravity are shown. The flexural modulus was inferior to that of the resin composition of Example 1.

Examples 4 and 5 90 parts by weight of ethylene-propylene block copolymers PP-7 and PP-8 obtained by polymerizing so that the copolymerization part has 3 components by changing the ethylene / propylene ratio. Talc "SKC2" with an average particle size of 2.2 μm
(Made by Shokoyama Co., Ltd.) (hereinafter abbreviated as talc 4) is 10
Pelletization and molding were carried out in the same manner as in Example 1 except that parts by weight were used, and test pieces for measuring physical properties were obtained and the physical properties were measured.
In Table 3, the compounding ratio of the ethylene-propylene block copolymer and talc, MI of the produced resin composition, flexural modulus, 23
℃ Izod impact strength, -30 ℃ Izod impact strength,
It shows tensile elongation at break, low temperature embrittlement temperature, and specific gravity. A resin composition having a better balance of flexural modulus and impact strength than the resin composition using PP-1 or the like obtained by one-step polymerization of the copolymerized portion was obtained.

Example 6 Ethylene-propylene block copolymers PP-9 and PP-1 having different ethylene / propylene weight ratios in the copolymerization part
Pelletization and molding were carried out in the same manner as in Example 4 except that 45 parts by weight of each of 0 was blended and used, and a test piece for measuring physical properties was obtained to measure physical properties. Table 3 shows the mixing ratio of the ethylene-propylene block copolymer and talc, MI of the resulting resin composition, flexural modulus, 23 ° C. Izod impact strength, −30 ° C. Izod impact strength, tensile elongation at break, low temperature embrittlement. Indicates temperature and specific gravity.

Example 7 Pelletization and molding were carried out in the same manner as in Example 4 except that the ethylene-propylene block copolymer PP-11 was used, and a test piece for measuring physical properties was obtained to measure physical properties. Table 3 shows the mixing ratio of the ethylene-propylene block copolymer and talc, MI of the resulting resin composition, flexural modulus, 23 ° C. Izod impact strength, −30 ° C. Izod impact strength, tensile elongation at break, low temperature embrittlement. Indicates temperature and specific gravity.

Example 8 Example 4 except that 87 parts by weight of PP-8 was used as the base PP and "EP07P" (manufactured by Nippon Synthetic Rubber Co., Ltd., Mooney viscosity 70, ethylene amount 73% by weight) was used as the EPR.
Pelletizing and molding were performed in the same manner as in 1. to obtain a test piece for measuring physical properties, and the physical properties were measured. Table 3 shows the compounding ratio of the ethylene-propylene block copolymer and talc, MI of the resin composition produced, flexural modulus, 23 ° C. Izod impact strength, -30.
℃ Izod impact strength, tensile elongation at break, low temperature embrittlement temperature,
Indicates specific gravity. Compared with the resin composition of Example 4, the flexural modulus was reduced, but the Izod impact strength and low temperature embrittlement temperature were improved. Also, the rear pillars (1.5, 2.0,
A 3.0 mm rib was molded, but there was no problem.

Comparative Example 7 PP-8 was used in an amount of 97 parts by weight and pelletized and molded in the same manner as in Example 8 except that talc was not added, and a test piece for measuring physical properties was obtained to measure physical properties. Table 3 shows the mixing ratio of the ethylene-propylene block copolymer and talc, MI of the resulting resin composition, flexural modulus, 23 ° C. Izod impact strength, −30 ° C. Izod impact strength, tensile elongation at break, low temperature embrittlement. Indicates temperature and specific gravity. A rear pillar was molded in the same manner as in Example 8, but it was too soft because of its low flexural modulus and dented when pressed with a finger.

Comparative Example 8 Pelletization and molding were carried out in the same manner as in Example 8 except that 57 parts by weight of PP-8 and 40 parts by weight of talc were used.
A test piece for measuring physical properties was obtained and the physical properties were measured. Table 3 shows the mixing ratio of the ethylene-propylene block copolymer and talc, MI of the resulting resin composition, flexural modulus, 23 ° C. Izod impact strength, −30 ° C. Izod impact strength, tensile elongation at break, low temperature embrittlement. Indicates temperature and specific gravity. Compared with the resin composition of Example 8, MI was low and it was inferior in Izod impact strength, low temperature embrittlement temperature, and tensile elongation at break. A rear pillar was molded in the same manner as in Example 8, but the fluidity was poor and the thickness was 1.5 m.
Insufficient filling was observed in the rib of m. In addition, flow marks and weld lines were noticeable on the surface of the molded product.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

[Table 3]

[0036]

The polypropylene resin composition of the present invention is
It has an excellent balance of flexural modulus and low temperature embrittlement temperature as compared with the conventional automobile interior materials compounded with fillers, and therefore it is optimal as a material for reducing the amount of filler or thinning it and making parts lighter. Further, since the polypropylene resin composition of the present invention has excellent fluidity, it is possible to manufacture a thin injection-molded product. The polypropylene resin composition of the present invention is most suitable for producing parts requiring relatively high rigidity such as pillars, roof side, door trim among automobile interior materials. An automobile interior material molded using the polypropylene resin composition of the present invention can be directly attached to an automobile as a product, but further coated with a matte coating on the surface, genuine leather, artificial leather, or cloth. It is also possible to attach them to each other using an adhesive or the like. In addition, it is also possible to flock nylon and polyester fibers. Further, since the polypropylene resin composition of the present invention has excellent fluidity, it is possible to perform stamping molding under low pressure, and at that time, it is possible to bond in a molten state with a skin material without using an adhesive material.

The polypropylene resin composition of the present invention is mainly composed of polypropylene and an inorganic filler and can be recycled without any problem. It is also possible to crush a defective molding product and mix it with a virgin material at the time of injection molding. It is also possible to pulverize waste materials generated by color change, etc. and color them with black color etc., and use them for parts other than automobile interior materials. Use the waste materials by mixing with other polypropylene resin composition. Is also possible.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazunori Aotsuka, Toyota City, Aichi Prefecture, Toyota Town, Toyota Motor Co., Ltd. (72) Inventor, Takao Nomura, Toyota City, Aichi Prefecture, Toyota City, Ltd. (72) 72) Inventor Takesumi Nishio 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd.

Claims (3)

[Claims] 1. An ethylene-propylene block copolymer (A) having an average intrinsic viscosity ([η]) of the ethylene-propylene copolymer part of 7 to 12 g / dl (A) of 95 to 85% by weight, and an average particle size of Inorganic filler (B) having a size of 1 to 4 μm
A polypropylene resin composition comprising 5 to 15% by weight, the melt index (MI) of the resin composition being 1
5 to 40 g / 10 min, flexural modulus (FM) of 2300 to 3000 MPa, low temperature embrittlement temperature (L
B) is less than 30 ° C., and the relation between FM and LB satisfies the inequality: FM> 8.4 × LB + 2300. A polypropylene resin composition for automobile interior materials, characterized in that: 2. The ethylene-propylene block copolymer (A) is polymerized in three stages, and the ethylene / propylene weight ratio of the copolymerized portion of the first stage polymerization product (C1) is 0.5. To 1.2, and the ethylene / propylene weight ratio of the copolymerization part of the second-stage polymerization product (C2) is 0.9 to 2.0.
And the ethylene / propylene weight ratio of the copolymerization part of the third stage polymerization product (C3) is 1.5 to 3.0, and C2 +
The weight ratio of ethylene / propylene in the C3 copolymerization part is 1.
3 to 2.5, and C1 for (C1 + C2 + C3)
The ratio of C2 is 30-60% by weight, and the ratio of C2 is 20-
50% by weight, and the ratio of C3 is 20 to 50% by weight
The polypropylene resin composition for automobile interior materials according to claim 1, wherein 3. An automobile interior material formed by molding the polypropylene resin composition according to claim 1 or 2.