JPH08104791A - Polypropylene resin composition - Google Patents

Abstract

PURPOSE: To obtain a lightweight polypropylene resin compsn. capable of providing a molded product excellent in rigidity, thermal deformation resistance and impact resistance, and suitable for an automobile outside plate, etc., by mixing two specific block copolymers with talc at a specific wt. ratio. CONSTITUTION: 60-90wt.% crystalline ethylene-propylene block copolymer having an ethylene unit content of 0.5 to 8wt.%, a boiling n-heptane insolubles content of at least 95wt.% in the polypropylene component thereof, and a melt flow rate of 5 to 70g/10min is mixed with (B) 5-20wt.% hydrogenated polybutadiene block copolymer comprising 15-30wt.% polybutadiene block(s) having a 1,2-vinyl bond content of at most 20mol% and 85-70wt.% polybutadiene block(s) having a 1,2-vinyl bond content of 30 to 50mol%, and having at least 90mol% of the double bonds thereof hydrogenated and a melt flow rate of 2 to 15g/10min and (C) 5-35wt.% talc having an average particle diameter of 3 to 5μm, a BET specific surface area of 5 to 13m<2> /g, and a top-cut diameter smaller than 20μm.

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 which is lightweight and excellent in rigidity, heat distortion resistance and impact resistance and which can provide a molded article having a good appearance. INDUSTRIAL APPLICABILITY The present invention can be suitably used for industrial parts such as automobiles and home electric appliances.

[0002]

2. Description of the Related Art Conventionally, a polypropylene-based resin such as a propylene / ethylene block copolymer has been used as a main component, and an ethylene / propylene rubber, an ethylene / butene rubber, an elastomer such as a hydrogenated product of a styrene / butadiene block copolymer, and A polypropylene resin composition combined with an inorganic filler such as talc has excellent rigidity and impact resistance, has high moldability, and is relatively easy to recycle. It has been widely used for such purposes. Further, various studies have been made to improve the rigidity, impact resistance, moldability, etc. of the polypropylene resin composition by changing the polypropylene resin, the elastomer, or the inorganic filler. An example of such a polypropylene resin composition is a combination of a crystalline ethylene / propylene copolymer, a specific ethylene / α-olefin copolymer rubber, and talc (JP-A-58-168649). Further, a combination of a crystalline ethylene / propylene copolymer with a specific hydrogenated styrene / butadiene block copolymer, ethylene / propylene rubber, and talc (Japanese Patent Laid-Open No. 3-172339) was also investigated. Further, a crystalline ethylene / propylene copolymer is combined with a specific hydrogenated styrene / butadiene block copolymer, ethylene / butene rubber, and talc (JP-A-4-57).
848) was also considered.

[0003]

In recent years, regarding automobile interior parts and exterior parts made of polypropylene resin,
From the viewpoint of process simplification, non-painting has come to be considered. Further, it has been considered to use polypropylene resin for a housing of audio equipment such as a CD player or a housing of home electric appliances such as an electric vacuum cleaner and a television receiver.
Therefore, polypropylene resin products are required to have rigidity, heat distortion resistance, and impact resistance more than ever before.
It has also been demanded that the appearance of products after injection molding be good. However, a polypropylene resin composition satisfying all such requirements has not yet been obtained. It is an object of the present invention to obtain a polypropylene resin composition which has a high level of rigidity, heat distortion resistance and impact resistance, and which has a good product appearance.

[0004]

The polypropylene-based resin composition of the present invention comprises the following components, that is, component (A): the component has an ethylene content of 0.5 to 8% by weight; A crystalline ethylene / propylene block copolymer having a tan insoluble content of 95% by weight or more and a melt flow rate (MFR; 230 ° C., 2160 g) of 5 to 70 g / 10 min. 60-90% by weight (B) component (a) Block of polybutadiene having a 1,2-vinyl bond ratio of 20 mol% or less (block I) and 1,2-vinyl bond ratio of 30-50 (B) the proportion of block I is 15 to 30% by weight, the proportion of block II is 70 to 85% by weight, and the block components are bonded together. Is a linear or branched block copolymer represented by the general formula I-II, (I-II) nX (X is a coupling agent residue, n ≧ 2), and 90 of the double bonds (c) MFR (230 ° C., 10 kg load) having a hydrogen content of more than mol% is 2 to 15 Hydrogenated polybutadiene block polymer: 5 to 20% by weight (C) component (a) Laser diffraction method The average particle diameter measured by 3 to 5 μm (b) the BET specific surface area is 5 to 13 m ² / g (c) the top cut diameter is less than 20 μm Talc ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ A polypropylene resin composition comprising 5 to 35% by weight. Is.

The present invention will be described in detail below. First, each component of the polypropylene resin composition of the present invention will be described.

Component (A) The component (A) used in the polypropylene resin composition of the present invention is a crystalline ethylene / propylene block copolymer, and the following are particularly preferred.

The crystalline ethylene / propylene block copolymer of the component (A) used in the present invention has an ethylene content of 0.5 to 8% by weight, particularly preferably 2 to 5% by weight. When it is less than 0.5% by weight, the impact resistance of the obtained resin composition is insufficient even if the hydrogenated diene polymer is added, and when it exceeds 10% by weight, the rigidity and the heat distortion resistance are deteriorated. Remarkable. Further, the polypropylene component of the crystalline ethylene / propylene block copolymer must have a boiling n-heptane insoluble content of 95% by weight or more. The boiling n-heptane insoluble content is an index showing the crystallinity of polypropylene, and if it is less than 95% by weight, rigidity and heat distortion resistance are insufficient. Here, the polypropylene component of the block copolymer refers to a polypropylene homopolymer produced in the preceding stage of ethylene / propylene copolymerization. The boiling n-heptane-insoluble matter is obtained by placing the polypropylene homopolymer in a cylindrical filter paper and subjecting it to boiling extraction for 6 hours with a Soxhlet extractor to obtain the residue. The crystalline ethylene / propylene block copolymer has a MFR (230 ° C., 2160
g) is 5 to 70 g / 10 minutes, preferably 10 to 50 g /
10 minutes. Since a composition using polypropylene having an MFR of less than 5 g / 10 min has a poor flow, there is a problem that when injection molding into a complicated shape, poor moldability and poor product appearance are likely to occur. On the other hand, since polypropylene having an MFR of 70 g / 10 min or more has an excessively low molecular weight, there is a problem that the composition using such polypropylene is inferior in rigidity and mechanical strength.

The ethylene / propylene block copolymer preferably has an ethylene content of 8% by weight or less, more preferably 2 to 5% by weight. Here, the ethylene content refers to the content of ethylene contained in the ethylene / propylene block copolymer as polyethylene or an ethylene / propylene copolymer. The ethylene content in the ethylene / propylene block copolymer can be determined as follows. First, the infrared absorption spectrum of the component (A) whose ethylene copolymerization amount is known is measured, and the absorbance of the characteristic absorption of each of the methyl group (corresponding to the propylene structure) and the methylene group (corresponding to the propylene structure and ethylene structure) Ask for. A calibration curve is prepared from the absorbance of these characteristic absorptions and the ratio of the amount of copolymerized ethylene. It can be determined using this calibration curve.

The ethylene / propylene block copolymer comprises a room temperature p-xylene soluble matter and a room temperature p-xylene insoluble matter, and the room temperature p-xylene soluble matter ratio is 4 to 2.
The range of 0% by weight is preferable, and the range of 5-12% by weight is particularly preferable. Here, the room temperature p-xylene-soluble component means that the ethylene / propylene block copolymer completely dissolved in boiling p-xylene is allowed to stand and is allowed to stand.
The polymer was recovered by cooling the temperature to ℃, allowing it to stand overnight for one day, separating the precipitated room temperature p-xylene insoluble matter by filtration, and recovering it from the obtained filtrate. Mainly low-molecular polypropylene and ethylene-propylene copolymer rubber It is mainly composed of. On the other hand, the room temperature p-xylene insoluble matter is mainly composed of high molecular weight isotactic polypropylene. Further, the room-temperature p-xylene-soluble component of the crystalline ethylene / propylene block copolymer has an ethylene content of 20 to 4
It is 5% by weight, preferably 25-40% by weight. When the ethylene content is less than 20% by weight, the compatibility between the ethylene / propylene block copolymer rubber and the crystalline polypropylene is increased, the rigidity and the heat distortion resistance are remarkably lowered, and the glass transition temperature of the copolymer rubber is increased to increase the resistance. Impact resistance is also reduced.
When the ethylene content is 40% by weight or more, the size of the dispersed phase of the copolymer rubber domain dispersed in the crystalline polypropylene becomes large and the impact resistance decreases, which is not preferable.

Component (B) The component (B) used in the polypropylene resin composition of the present invention has (a) 1,2-vinyl bond ratio of 2;
It comprises a polybutadiene block (block I) of 0 mol% or less and a polybutadiene block (block II) having a 1,2-vinyl bond ratio of 30 to 50 mol%. 30% by weight, the proportion of block II is 70 to 85% by weight, and the bond of the block component is represented by the general formula I-II, (I-II) nX (X is a coupling agent residue, n ≧ 2). (C) MFR in which 90 mol% or more of double bonds is hydrogenated (230 ° C., 10
It is a hydrogenated polybutadiene-based block polymer having a kg load of 2 to 15.

The component (B) comprises a block (block I) having a 1,2-vinyl bond ratio of 20 mol% or less,
It is a hydrogenated polybutadiene-based block polymer consisting of a block (block II) having a ratio of 1,2-vinyl bonds of 30 to 50 mol%. In the above polybutadiene-based block polymer, the bonding of the block components is represented by the general formula I
-II, (I-II) nX (X is a coupling agent residue, n ≧
It is a linear or branched block copolymer represented by 2) and has an MFR (230 ° C., 10 kg load) of 2 to 15.

In the polybutadiene block copolymer, block I is a polybutadiene block in which the proportion of 1,2-vinyl bonds in double bonds is 20 mol% or less, and mainly consists of cis-1,4-bonds and trans
It consists of -1,4-bonds. Therefore, in the component (B) obtained by hydrogenating the polybutadiene-based block copolymer, the block I has a structure similar to polyethylene. Therefore, in the component (B), the portion corresponding to the block I has high crystallinity and serves as a hard segment, and thus has the function of increasing the rigidity and the heat distortion temperature of the polypropylene resin composition.

The proportion of 1,2-vinyl bonds in block I must be less than 20 mol%. If the proportion of 1,2-vinyl bonds in Block I exceeds 20 mol%, the proportion of the structure similar to the ethylene / butene-1 copolymer will increase after hydrogenation, resulting in low crystallinity and hard segment. Because it will not be able to play the role of.

The block I is 5,000 or more, preferably 10,000 or more, more preferably 15.0.
It must have a molecular weight of 00 or higher. If the molecular weight of the block I is less than 5,000, the molecular weight of the block I is too small, so that it cannot sufficiently fulfill the role of the hard segment after hydrogenation, which is not preferable.

On the other hand, block II occupies a double bond 1,
The proportion of 2-vinyl bonds is 30 to 50 mol%, preferably 35 to 45 mol%. Therefore, in the component (B) obtained by hydrogenating the polybutadiene block copolymer, the block II has a structure similar to that of the ethylene / butene-1 random copolymer or styrene / butadiene rubber, and therefore, as a soft segment. Fulfill the function of. This has the function of increasing the impact resistance of the polypropylene resin composition. When the proportion of 1,2-vinyl bonds in the double bonds of the block II is out of the range of 30 to 50 mol%, the block II in the component (B) has a structure similar to polyethylene or polybutene-1. , The rubber property becomes low. Therefore, even if such component (B) is used, a polypropylene resin composition having high impact resistance cannot be obtained. The block II should have a molecular weight of 5,000 or more, preferably 10,000 or more, and more preferably 15,000 or more. When the molecular weight of the block II is less than 5,000, the molecular weight of the block II is too small to obtain a polypropylene resin composition having high impact resistance.

The proportions of block I and block II in the polybutadiene block copolymer are as follows.
When the total amount of II is 100% by weight, the proportion of block I is 15 to 30% by weight, the proportion of block II is 70 to 85% by weight, and the proportion of block I is preferably 15 to 2%.
5% by weight and the proportion of block II must be 75 to 85% by weight. If the proportion of the block I is less than 15% by weight, the polyethylene segment derived from the block I in the component (B) will be insufficient. Therefore, when the component (B) is used, a polypropylene resin having high rigidity and high heat distortion temperature There is a problem that a composition cannot be obtained. On the other hand, when the proportion of the block I exceeds 30% by weight, the polyethylene segment derived from the block I in the component (B) becomes excessive. Therefore, when the component (B) is used, a polypropylene resin having high impact resistance is used. No composition is obtained.

In the component (B), 90 mol% or more of the double bonds in the polybutadiene block copolymer must be hydrogenated. When the proportion of hydrogenated double bonds is less than 90 mol%, the heat resistance and weather resistance are insufficient, and it is not preferable to use such hydrogenated products.

The melt flow rate (230 ° C., 10 kg) of the component (B) is in the range of 2 to 15 g / 10 minutes, preferably 2 to 10 g / 10 minutes. The polypropylene resin composition using the component (B) having a melt flow rate (230 ° C., 10 kg) of less than 2 g / 10 minutes has a problem that flow marks are likely to occur on the surface of an automobile part when molded. have. On the other hand, the component (B) whose melt flow rate exceeds 15 g / 10 minutes is
Since the molecular weights of block I and block II become too small, the rigidity and impact resistance of the polypropylene resin composition are not so improved even if such a component (B) is used.

The component (B) is, for example, Japanese Patent Application No. 3-12895.
It can be obtained by a method as shown in No. 7, that is, by living polymerization of 1,3-butadiene in two steps. Specifically, 1,3-butadiene is subjected to living polymerization with an organic alkali metal compound such as an organic lithium compound to obtain block I, and subsequently, ethers such as diethyl ether and THF, and a secondary methyl ether such as tetramethylethylenediamine. Lewis bases such as tertiary amines and 1,3-
Butadiene is added and the second stage polymerization is carried out to obtain a polybutadiene having a structure in which block I and block II are bonded. The polybutadiene obtained is reacted with a coupling agent such as tetrachlorosilicon, butyltrichlorosilicon, tetrachlorotin, or tetrachlorogermanium to obtain a so-called radial type polybutadiene block copolymer. The obtained polybutadiene block copolymer is hydrogenated to obtain the component (B).

Organolithium compounds used in the first stage polymerization include ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, t-butyl lithium, hexamethylene dilithium and butadiene. Examples thereof include enyllithium and isoprenyldilithium.

Examples of Lewis bases added in the second-stage polymerization include ethers such as diethyl ether, THF, propyl ether, butyl ether, ethylene glycol dimethyl ether, diethylene glycol dibutyl ether and triethylene glycol dimethyl ether, tetramethylethylenediamine and pyridine. And tertiary amines such as tributylamine.

As the coupling agent, diethyl adipate, divinylbenzene, tetrachlorosilicon, butyltrichlorosilicon, tetrachlorotin, butyltrichlorotin,
Tetrachlorogermanium, 1,2-dibromoethane,
One or more selected from 1,4-chloromethylbenzene, bis (trichlorosilyl) ethane, epoxidized linseed oil, tolylene diisocyanate, 1,2,4-benzenetriisocyanate and the like can be used.

As the hydrogenating agent, dicyclopentadienyl titanium halide, nickel organic carboxylate, a hydrogenation catalyst comprising nickel organic carboxylate and an organometallic compound of Group I to III of the periodic table, nickel or platinum. Rare earths such as palladium, ruthenium, rhenium and rhodium and catalysts supported on carbon, metal complexes such as cobalt complex, nickel complex, rhodium complex and ruthenium complex, Z
r-Ti-Fe-V-Cr alloy, Zr-Ti-Nb-F
An e-V-Cr alloy is mentioned.

Component (C) The component (C) used in the polypropylene resin composition of the present invention is talc, and (a) the average particle size measured by a laser diffraction method is 3 to 5 μm.
m (b) BET specific surface area is 5 to 13 m ² / g (c) Top cut diameter satisfies the requirement of less than 20 μm.

The talc used as the component (C) needs to have an average particle size measured by a laser diffraction method of 3 to 5 μm. Since talc having an average particle size of less than 3 μm has a small average aspect ratio, the rigidity of the polypropylene resin composition is not so improved even if such talc is used. On the other hand, when talc having an average particle size of more than 5 μm is used, a polypropylene resin composition having high impact resistance cannot be obtained. Also, the rigidity is not improved so much.

BET specific surface area, that is, talc absorbs nitrogen at a liquid nitrogen temperature, and B
The adsorption amount of nitrogen at the liquid nitrogen temperature determined by the ET theory is 5 to 13 m ² / g, preferably 7 to 11 m ² / g. When talc having a BET specific surface area of less than 5 m ² / g is used, the rigidity of the polypropylene resin composition is not improved so much. On the other hand, talc having a BET specific surface area of more than 13 m ² / g has a large proportion of fine particles. Therefore, when such talc is used, the rigidity of the polypropylene resin composition is not improved so much.

Further, the top cut diameter of talc, that is, the diameter of the largest of the particles contained in the talc must be less than 20 μm. Since talc having a top cut diameter of more than 20 μm has a large proportion of particles having a large particle size, when such talc is used, the impact resistance of the resulting polypropylene resin composition is significantly reduced.

Such talc is produced by crushing raw talc to a predetermined average particle size with a known crusher such as a roller mill or a crusher, and then using a dry classifier to remove large and small particles. be able to.

The polypropylene resin composition of the present invention is
The ratio of the crystalline polypropylene as the component (A) is 60 to 90.
%, The proportion of the hydrogenated polybutadiene block copolymer of the component (B) is 5 to 20 weight%, and the proportion of talc of the component (C) is 5 to 35 weight%. The polypropylene resin composition containing less than 5% by weight of the component (B) has too low impact resistance, and the polypropylene resin composition containing more than 20% by weight has low rigidity. Further, the component (C) is 5% by weight.
Less polypropylene resin composition has low rigidity,
The polypropylene resin composition of more than 35% by weight has a problem of low impact resistance.

The polypropylene resin composition of the present invention further comprises, as the component (D), ethylene / propylene rubber, ethylene / propylene / diene terpolymer rubber,
Ethylene / butene rubber, hydrogenated styrene / butadiene /
Elastomers such as styrene block copolymer rubber can be added.

The ethylene / propylene rubber has an ethylene content of 60 to 80% by weight and a Mooney viscosity ML.
It is preferable that _{1 + 4} (100 ° C.) is 10 to 70.

The ethylene / propylene / diene terpolymer rubber having an ethylene content of 60 to 80% by weight and a Mooney viscosity ML _{1 + 4} (100 ° C.) of 10 to 70 is preferable.

As the ethylene / butene copolymer rubber,
Butene content 10-25% by weight, Mooney viscosity ML _{1 + 4}
Those having a (100 ° C.) of 5 to 20 can be used.

The hydrogenated styrene / butadiene / styrene block copolymer is composed of a block having a polystyrene structure (block S) and a block having a polybutadiene structure (block B), and the ratio of the block S to the whole is 10 to 30. It is in the range of wt% and the melt flow rate (MFR; 230 ° C, 5 kg) is 0.7 to 10.
The range of g / 10 minutes is preferable.

The addition amount of the component (D) is preferably 200 parts by weight or less based on 100 parts by weight of the hydrogenated polybutadiene block copolymer of the component (B).

If desired, an antioxidant, an ultraviolet absorber, a light stabilizer, a pigment or the like can be added to the composition of the present invention. As the antioxidant, 2,6-di-t-butylphenol, 2,6-di-t-butyl-4-ethylphenol, 2,6-di-t-butyl-4-n-butylphenol, 2,6 -Di-t-butyl-α-dimethylamino-p-cresol, 6- (4-hydroxy-3,5-
Di-t-butylaniline) -2,4-bisoctyl-thio-1,3,5-triazine, N-octadecyl-3-
(4'-hydroxy-3 ', 5'-di-t-butylphenyl) butane, tetrakis [methylene-3- (3',
5'-di-t-butylphenyl-4'-hydroxyphenyl) propionate] methane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4)
-Hydroxybenzyl) benzene, dilaurylthiodipropiodinate and the like.

As the ultraviolet absorber and the light stabilizer, 2
-Hydroxy-4-n-octoxybenzophenone, 2
-Hydroxy-4-octadecyloxybenzophenone,
4-dodecyloxy-2-hydrochioxybenzophenone,
2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl) -5-chlorobenzotriazole, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, 1,2 , 3,4-butanetetracarboxylic acid-
Examples include 1,2,2,6,6-pentamethyl-4-piperidinol tridecyl alcohol condensate.

[0038]

EXAMPLES The present invention will be specifically described below with reference to examples. The methods for measuring the physical properties in the examples are shown below. The test pieces used for measuring the physical properties were injection molded under the conditions of a cylinder set temperature of 210 ° C. and a mold temperature of 40 ° C. using a J100SAII type injection molding machine manufactured by Japan Steel Works, Ltd. (1) Melt Flow Rate (MFR) It was measured by the method specified in ASTM D1238. (2) Bending elastic modulus It was measured by the method specified in ASTM D790. (3) Heat distortion temperature It was measured by the method specified in ASTM D648.
Fiber stress was measured at 18.5 kg / cm ² . (4) Surface hardness Measured by the method specified in ASTM D685.
The steel ball was R and the evaluation value was shown on the R scale. (5) Izod impact strength The Izod impact strength was measured by the method specified in ASTM D256.
The measurement temperature was 23 ° C. (6) Flow mark generation rate Flow marks are regular strip-shaped irregularities that are not transferred faithfully to the mold surface and are generated perpendicularly to the flow direction, and are defects in which micron-order distortion occurs on the surface of the molded product. is there. The flow mark generation rate was 3 mm in thickness, 10 mm in width, and 2000 mm in length. A resin flow path length measuring die having a spiral flow path was used for injection molding to measure the flow path length.
In this spiral sample for flow length measurement, the flow path length at which flow marks began to be generated was measured, and the ratio of the flow path length in which the flow marks were generated to the total length of the sample was defined as the flow mark generation rate. .

[Each component of the polypropylene resin composition]
The components used in the preparation of the polypropylene resin compositions used in Examples and Comparative Examples are as shown in Tables 1 to 4.

[0040]

[Table 1]

[0041]

[Table 2]

[0042]

[Table 3]

[0043]

[Table 4]

Examples 1 to 9 Components (A) to (D), antioxidants, light stabilizers, and pigments having the formulations shown in Table 5 were kneaded in a tumbler mixer and then melted in a twin-screw kneading extruder. The mixture was kneaded to prepare a polypropylene resin composition and pelletized. As antioxidants, 2,6-di-t-butyl-4-methylphenol and tetrakis [methylene 3 (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane were used as polypropylene type. 0.1 part by weight of the former and 0.2 part by weight of the latter were used per 100 parts by weight of the resin composition.
As the light stabilizer, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate was used in an amount of 0.1 part by weight based on 100 parts by weight of the polypropylene resin composition. As the pigment, 0.7 parts by weight of iron oxide and 0.3 parts by weight of titanium oxide were used with respect to 100 parts by weight of the polypropylene resin composition. A pellet of the polypropylene resin composition was molded into a test piece by an injection molding machine, and a physical property test was performed. The results are shown in Table 5.

[0045]

[Table 5]

Comparative Examples 1 to 3 A polypropylene resin was prepared in the same manner as in Example 1 except that the components (A) were changed to those outside the range specified in the present invention (P-4 to P-6). The composition was prepared into pellets. This pellet is molded into a test piece with an injection molding machine,
A physical property test was conducted. The results are shown in Table 6. The polypropylene-based resin composition of Comparative Example 1 has a higher generation rate of flow marks and is inferior in the appearance of the product as compared with the polypropylene-based resin composition of Example. Further, Comparative Examples 2 and 3 are inferior in Izod impact strength.

Comparative Examples 4 and 5 (B) Component outside the scope of the present invention (R-6, R-7)
A polypropylene-based resin composition was prepared in the same manner as in Example 1 except that the above was changed into pellets. This pellet was molded into a test piece by an injection molding machine and a physical property test was conducted. The results are shown in Table 6. Compared with the example, the comparative example 4 has a low Izod impact strength, a high flow mark generation rate, and a problem of product appearance. Further, Comparative Example 5 has a low flexural modulus, a heat deformation temperature, and a surface hardness, and has a low rigidity for application to industrial parts.

Comparative Examples 6 to 9 A polypropylene resin composition was prepared in the same manner as in Example 1 except that the component (B) was not used and the component (D) was added instead, and pelletized. This pellet was molded into a test piece by an injection molding machine and a physical property test was conducted. The results are shown in Table 6. The polypropylene resin compositions of Comparative Examples 6 to 9 are
Compared with the polypropylene-based resin compositions of the examples, the flexural modulus, heat distortion temperature, surface hardness and Izod impact strength are poorly balanced, and for use in industrial parts, increase the thickness in terms of product design, etc. It needs to be done and is not suitable.

[0049]

[Table 6]

Comparative Examples 10 and 11 A polypropylene resin composition was prepared in the same manner as in Example 1 except that the component (C) that did not satisfy the conditions specified in the present invention was used. did. This pellet was molded into a test piece by an injection molding machine and a physical property test was conducted. The results are shown in Table 7. When the polypropylene resin compositions of Comparative Examples 10 and 11 were compared with the polypropylene resin compositions of Examples, it was found that the Izod impact strength was low.

Comparative Examples 12 to 14 In Comparative Example 12, the amount of the (B) component was reduced, in Comparative Example 13, the (C) component was removed, and in Comparative Example 14, the amount of the (C) component was increased. A polypropylene-based resin composition was prepared in the same manner as in Example 1 except that the compounding conditions were not satisfied to prepare pellets. This pellet was molded into a test piece by an injection molding machine and a physical property test was conducted. The results are shown in Table 7. Compared to the examples, Izod impact strength in Comparative example 12, bending elastic modulus, heat deformation temperature in Comparative example 13,
It was found that the rigidity such as surface hardness and the Izod impact strength and the flow mark generation rate were inferior in Comparative Example 14.

[0052]

[Table 7]

[0053]

EFFECTS OF THE INVENTION The polypropylene resin composition of the present invention is lightweight and excellent in rigidity, heat distortion resistance and impact resistance, and can provide a molded article having a good appearance.
It is preferably used for industrial parts such as outer panels and interiors of automobiles and housings of home electric appliances.

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Claims (3)

[Claims] 1. Component (A) The component has an ethylene content of 0.5 to 8% by weight, a boiling n-heptane insoluble content of the polypropylene component of 95% by weight or more, and a melt flow rate (MFR; 230 ° C., 2160 g). 5 to 70 g / 10 minutes Crystalline ethylene / propylene block copolymer 60 to 90% by weight (B) Component (a) 1,2-vinyl bond ratio Of polybutadiene having a content of 20 mol% or less (block I) and a polybutadiene block having a ratio of 1,2-vinyl bonds of 30 to 50 mol% (block II). (B) The ratio of block I is 15 to 30% by weight, the proportion of block II is 70 to 85% by weight, and the binding of the block component is represented by the general formula I-II, (I-II) nX (X is a coupling agent residue, n ≧ 2). Straight chain indicated by Or a branched block copolymer (c) A hydrogenated polybutadiene block polymer having an MFR (230 ° C., 10 kg load) of 2 to 15 in which 90 mol% or more of double bonds is hydrogenated. 5 to 20% by weight (C) component (a) Average particle diameter measured by laser diffraction method is 3 to 5 μm (b) BET specific surface area is 5 to 13 m ² / g (c) Top cut diameter is A talc having a thickness of less than 20 μm A polypropylene resin composition comprising 5 to 35% by weight of talc ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 2. The crystalline ethylene / propylene block copolymer as the component (A) has a room temperature p-xylene soluble content of 4 to 2.
The polypropylene resin composition according to claim 1, wherein the polypropylene content is 0% by weight, and the ethylene content of the room temperature p-xylene soluble component is 20 to 45% by weight. 3. The component (A) comprises a component having an ethylene content of 0.5 to 8% by weight, a polypropylene component having a boiling n-heptane insoluble content of 95% by weight or more, and a melt flow rate (MFR; 230 ° C., 2160 g). 5 to 70 g / 10 minutes Crystalline ethylene / propylene block copolymer 60 to 90% by weight (B) Component (a) 1,2-vinyl bond ratio Of polybutadiene having a content of 20 mol% or less (block I) and a polybutadiene block having a ratio of 1,2-vinyl bonds of 30 to 50 mol% (block II). (B) The ratio of block I is 15 to 30% by weight, the proportion of block II is 70 to 85% by weight, and the binding of the block component is represented by the general formula I-II, (I-II) nX (X is a coupling agent residue, n ≧ 2). Straight chain indicated by Or a branched block copolymer (c) A hydrogenated polybutadiene block polymer having an MFR (230 ° C., 10 kg load) of 2 to 15 in which 90 mol% or more of double bonds is hydrogenated. 5 to 20% by weight (C) component (a) Average particle diameter measured by laser diffraction method is 3 to 5 μm (b) BET specific surface area is 5 to 13 m ² / g (c) Top cut diameter is Below 20 μm Talc ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ -Propylene copolymer rubber (b) Ethylene / propylene / diene terpolymer rubber (c) Ethylene / butene copolymer rubber (d) Block having polystyrene structure (block S) and polybutadiene structure 200 parts by weight or less of one or two or more elastomers selected from the group consisting of hydrogenated styrene / butadiene block copolymer consisting of a block (block B) having A polypropylene resin composition comprising: