JPH0598093A - Flexible thermoplastic resin coposition and injectionmolded product thereof - Google Patents

Abstract

PURPOSE:To obtain the title compsn. excellent in impact strength at low temp., etc., by using a specific crystalline PP, a specific ethylene-butene-1 copolymer rubber and a specific ethylene-propylene copolymer rubber to provide the compsn. with predetermined properties. CONSTITUTION:The title compsn. is constituted of a predetermined amt. of (A) one crystalline PP selected from (i) a crystalline propylene-ethylene block copolymer comprising a first segment(s) of propylene homopolymer having specific properties such as a specific intrinsic viscosity and a second segment(s) of a propylene-ethylene random copolymer having specific properties such as a specific intrinsic viscosity and (ii) a mixture of component (i) with a crystalline propylene homopolymer having specific properties such as a specific intrinsic viscosity, a predetermined amt. of (B) an ethylene- butene-1 copolymer rubber having specific properties such as a specific intrinsic viscosity, and a predetermined amt. of (C) an ethylene-propylene copolymer rubber having specific properties such as a specific intrinsic viscosity. When the second segment (s) of component (i) in (A) is referred to as component (A), the amts. of components (A'), (B) and (C) comply with a predetermined ratio. The title compsn. has a specific melt flow rate and a specific modulus of elasticity.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention has excellent physical properties in terms of rigidity, low-temperature impact resistance, and scratch resistance, and in terms of injection molding processability, has a short molding cycle, and has a flow mark The present invention relates to a novel soft thermoplastic resin composition having no surface quality such as generation or surface distortion, and an injection molded article excellent in dimensional stability, which is molded by an injection molding method, particularly to a bumper for automobiles. More specifically, with a particular crystalline polypropylene as a main component, a specific ethylene-butene-1 copolymer rubber, a specific ethylene-
Made of propylene copolymer rubber and talc, it is a new type of soft material with excellent rigidity, low temperature impact resistance and scratch resistance in terms of physical properties, and a short molding cycle and excellent surface quality in terms of injection molding processability. Thermoplastic resin composition,
The present invention also relates to an injection-molded article having excellent dimensional stability, which is formed by an injection-molding method, and more particularly to a bumper for automobiles.

[0002]

2. Description of the Related Art Recently, as for automobile bumpers, polyurethane bumpers and crystalline propylene-ethylene block copolymer bumpers have begun to be used in place of conventional iron bumpers in terms of weight reduction and safety. However, a polyurethane bumper is expensive and has a relatively high specific gravity, and a crystalline propylene-ethylene block copolymer bumper has excellent thermal properties such as rigidity and heat distortion temperature, but has low impact strength at low temperatures. In order to improve the low temperature impact strength, it is possible to compound an ethylene-propylene copolymer rubber with a crystalline propylene-ethylene block copolymer, for example, JP-A Nos. 53-22552 and 53-52.
It is proposed in Japanese Patent No. 40045. But ethylene
Since the propylene copolymer rubber is blended, the thermal properties such as rigidity and heat distortion temperature are poor. In order to solve this, it is preferable to further add inorganic fillers such as calcium carbonate, barium sulfate, mica, crystalline calcium silicate, and talc, and mix them together, for example, JP-A-51-136735, JP-A-53-64256, and JP-A-53-64256. 53-64257, 57-
55952, 57-207630, 58-17.
No. 139, No. 58-111846, No. 59-9815.
7 and Japanese Patent Publication No. 55-3374. Among them, the composition for bumper is disclosed in JP-A-57-5.
No. 5952, No. 57-207630, No. 58-111.
No. 846 and 59-98157. Further, by adding talc in JP-A-51-136735 and by adding talc, mica or calcium silicate in JP-A-57-207630, it is possible to further reduce the molding shrinkage and improve the dimensional stability. Has been done. In JP-A-58-17139 and JP-A-58-17140, ethylene-butene-1 is used in place of the ethylene-propylene copolymer rubber in the crystalline propylene-ethylene block copolymer.
It has been proposed to incorporate a copolymer rubber. Particularly, in JP-A-58-17140, by using an ethylene-butene-1 copolymer rubber, the impact whitening area is made smaller than that of an ethylene-propylene copolymer rubber,
It is described that an effect of improving scratch resistance can be obtained.

Crystalline propylene-ethylene copolymer /
An ethylene-propylene copolymer rubber / talc composition (abbreviated as an ethylene-propylene copolymer rubber-based composition) has a drawback in scratch resistance but is inexpensive and has good moldability. For reasons such as
Widely used for bumpers. Recently, along with the problem of resource recycling, there is a movement to replace reinforced RIM-urethane. The ethylene-propylene copolymer rubber resin composition is usually molded into a bumper by an injection molding method. First regarding its injection molding processability
Secondly, in order to improve productivity, the molding cycle of the present composition is shortened. Secondly, the present composition is a reinforced RIM-urethane which is free of flow marks and melamera by injection molding and has no surface distortion. It is required to provide bumper molded products having equivalent excellent surface quality. On the other hand, the bumper is also required to have a feeling of unity with the body as a part of the design of the automobile, and dimensional stability close to that of iron used for the body is required for the resin material for the bumper. However, the conventional ethylene-propylene copolymer rubber-based composition has a limit in scratch resistance and has a problem in dimensional stability. In addition, surface quality is improved in injection molding by simply increasing the fluidity,
The low temperature impact strength required as a bumper is not satisfied,
On the other hand, there is a problem that the molding cycle time is not shortened as a result because the filling time is shortened but the plasticization time is lengthened.

[0004]

In view of the above situation, the present invention mainly uses crystalline polypropylene, satisfies the low temperature impact strength and the rigidity required as a bumper in terms of physical properties, and has been used conventionally. A thermoplastic resin composition having a higher Rockwell hardness than that of the ethylene-propylene copolymer rubber composition described above and having a short molding cycle and good surface quality in terms of injection moldability. And further to provide an injection-molded article, particularly a bumper, having a small linear expansion coefficient by using the composition.

[0005]

The present invention provides a crystalline polypropylene (A): 50% by weight or more, ethylene-butene-
1 copolymer rubber (B): 15 to 25% by weight, ethylene-
Propylene copolymer rubber (C): 15 to 25% by weight, crystalline polypropylene (A) is one selected from the following (i) or (ii), and (A),
(B) and (C) have the following structures and physical properties, and (A)
When the amount of the second segment of the crystalline propylene-ethylene block copolymer of (1) is (A) ', the formula: (A) + (B) + (C) = 100% by weight (1) (B) + (C) ≧ 30% by weight (2) 0.35 ≦ {[(A) ′ + (B) + (C)] / 100} ≦ 0.55 (3) 0.1 ≦ {(A) ′ / [(A) ′ + (B) + (C)]} (4) 0.4 ≦ {(B) / [(B) + (C)]} ≦ 0.6 (5), and the melt flow rate (230 ° C. , 2.1
Under a load of 6 kg) is 15 to 25 (g / 10 minutes), and 2
Flexural modulus at 3 ° C is 10,000 (kg / cm ² )
Crystalline polypropylene (A): (i) The Q value (= ratio of the weight average molecular weight to the number average molecular weight) of the propylene homopolymer portion of the first segment by GPC (gel permeation chromatography) is 5 Hereinafter, the intrinsic viscosity of the 135 ° C. tetralin solution is 0.85 to 0.95 (dl / g), and the intrinsic viscosity of the 135 ° C. tetralin solution of the propylene-ethylene random copolymer portion which is the second segment is 4.5 to 5.5.
(Dl / g), the ratio of propylene / ethylene is 75/2
5 to 60/40 (weight% ratio) crystalline propylene-
Ethylene block copolymer, (ii) crystalline propylene-ethylene block copolymer of (i) and Q value by GPC method of 5 or less, viscosity of 135 ° C. tetralin solution is 0.85 to 0.95 (dl / g)
Ethylene-butene-1 copolymer rubber (B) having a Q value of 2.7 or less by GPC method, a butene-1 content of 15 to 20% by weight, and a 70 ° C xylene solution. Intrinsic viscosity 1.1 to 2.1
(Dl / g) and Mooney viscosity at 100 ° C ML _{1 + 4}
100 is 7 to 90, ethylene-propylene copolymer rubber (C): Q value by GPC method is 2.7 or less, propylene content is 20 to 30% by weight, and intrinsic viscosity of 70 ° C xylene solution is 1.8 to 2 .2
(Dl / g) and Mooney viscosity at 100 ° C ML _{1 + 4}
100 is 35 to 100, wherein the soft thermoplastic resin composition is crystalline polypropylene (A): 40% by weight or more, ethylene-butene-1 copolymer rubber (B): 15 to 25% by weight. , Ethylene-propylene copolymer rubber (C): 15 to 15
25% by weight, and talc having an average particle size of 4 μm or less (D): 1 to 7% by weight, (A), (B),
(C) and (D) represent the amount of the second segment of the crystalline propylene-ethylene block copolymer of (A) by (A) '.
In this case, the formula is: (A) + (B) + (C) + (D) = 100 wt% (1) (B) + (C) + (D) ≧ 30 wt% (2) 0.35 ≦ {[(A) '+ (B) + (C)] / 100} ≤0.55 (3) 0.1≤ {(A)' / [(A) '+ (B) + (C)]} (4) 0.4 ≦ {(B) / [(B) + (C)]} ≦ 0.6 (5) is satisfied and the melt flow rate (230 ° C., 2.1) is satisfied.
Under a load of 6 kg) is 15 to 25 (g / 10 minutes), and 2
Flexural modulus at 3 ° C is 10,000 (kg / cm ² )
A soft thermoplastic resin composition characterized by being a soft thermoplastic resin composition characterized by the following and characterized in that these soft thermoplastic resin compositions are molded by an injection molding method. The injection-molded article and the injection-molded article relate to a bumper.

In the present invention, crystalline polypropylene means a crystalline propylene homopolymer and a crystalline propylene homopolymer portion as the first segment polymerized in the first step, or ethylene and / or at least one other α-olefin. (Eg, butene-1, hexene-1) is 6 mol% or less of crystalline propylene-
having an α-olefin random copolymer portion, and ethylene and / or as a second segment polymerized in the second step
Alternatively, it refers to a crystalline propylene-α-olefin block copolymer in which at least one other α-olefin (for example, butene-1, hexene-1, etc.) has a propylene-α-olefin random copolymer portion of 10 mol% or more. Among them, crystalline polypropylene (A) is a crystalline propylene-ethylene block copolymer having a crystalline propylene homopolymer portion as the first segment and a propylene-ethylene random copolymer portion as the second segment, which are polymerized in the first step, or Refers to a mixture of crystalline propylene-ethylene block copolymer and crystalline propylene homopolymer.

The crystalline polypropylene can be obtained, for example, by reacting in the presence of a combination catalyst of titanium trichloride and an alkylaluminum compound, which is usually called a Ziegler-Natta type catalyst. Polymerization is 0 ℃ -300 ℃
Can be carried out for up to However, in highly stereoregular polymerization of α-olefins such as propylene,
It is usually preferable to carry out the heating in the range of 0 ° C. to 100 ° C. for the reason that a polymer having a high stereoregularity cannot be obtained at 100 ° C. or higher. The polymerization pressure is not particularly limited, but is 3 to 100 from the viewpoint of being industrial and economical.
A pressure of about atmospheric pressure is desirable, and a chain transfer agent such as hydrogen can be added to adjust the molecular weight of the polymer. The polymerization method may be either continuous or batch type, slurry polymerization with an inert hydrocarbon solvent such as butane, pentane, hexane, heptane, octane, the resulting polymer is dissolved in the inert hydrocarbon solvent. Solvent polymerization that polymerizes in a state, bulk polymerization in a liquefied monomer without a solvent, vapor phase polymerization in a gaseous monomer and the like are applied.

The polypropylene used in the present invention can be produced using an isospecific Ziegler-Natta catalyst. The catalyst used preferably has a high isospecificity. A catalyst that can be preferably used is a composite solid compound of which the transition metal catalyst component has a layered crystal structure and a titanium compound or a titanium compound, and a titanium compound, and a typical metal component thereof is an organoaluminum compound. The catalyst may contain a known electron donating compound as the third component. As the titanium trichloride, those produced by reducing titanium tetrachloride with various reducing agents can be used. Known reducing agents include metals such as aluminum and titanium, hydrogen, and organometallic compounds. A typical example of titanium trichloride produced by metal reduction contains aluminum chloride activated by reducing titanium tetrachloride with metallic aluminum and then pulverizing it in a device such as a ball mill or a vibration mill. Titanium trichloride composition (TiCl ₃ A
A). A compound selected from ether, ketone, ester, aluminum chloride, titanium tetrachloride and the like can be coexisted at the time of pulverization for the purpose of improving isospecificity, polymerization activity, particle properties and the like.

Further preferred titanium trichloride for the purpose of the present invention is to reduce titanium tetrachloride with an organoaluminum compound and subject the resulting titanium trichloride composition to a catalytic reaction simultaneously or sequentially with an ether compound and a halogen compound. It is titanium trichloride obtained by The ether compound has the general formula R ¹ —O—R ² (R ¹ and R ² are each a carbon number of 1 to 18).
Those having an alkyl group of), especially di-n-butyl ether and di-t-amyl ether are preferable. The halogen compound is preferably selected from iodine, the halogen compound is particularly selected from iodine trichloride, the titanium halide is preferably selected from titanium tetrachloride, and the halogenated hydrocarbon is preferably selected from carbon tetrachloride and 1,2-dichloroethane. The organoaluminum compound is represented by the general formula AlR ³ _n X _3-n (R ³ is a hydrocarbon group having 1 to 18 carbon atoms, X is a halogen selected from Cl, Br and I, and n is a number satisfying 3 ≧ n> 1. Are particularly preferable, and diethylaluminum chloride and ethylaluminum sesquichloride are preferable. For the production method of these titanium trichlorides, see JP-A-47-34470 and 53-53.
No. 33289, No. 53-51285, No. 54-11
No. 986, No. 58-142903, No. 60-2840.
No. 5, No. 60-228504, and the like. When titanium trichloride having a layered crystal structure is used as the transition metal compound component, the general formula AlR ⁴ _m X _3-m (R ⁴ is a carbon number of 1 to 18) is used as the typical metal compound component.
Is preferable, X is a halogen selected from Cl, Br, and I, and m is 3 ≧ m> 0). Particularly preferred organoaluminum compounds for the purposes of the present invention are those in which R ⁴ is an ethyl or isobutyl group and m is 2.5 ≧ m ≧ 1.5. Specific examples thereof include diethyl aluminum chloride, diethyl aluminum bromide, diethyl aluminum iodide, and mixtures thereof with triethyl aluminum or ethyl aluminum dichloride. 3 when using together with the third component described later
Organoaluminum compounds having ≧ m ≧ 2.5 or 1.5 ≧ m> 0 can also be preferably used for the purpose of the present invention. The ratio of the organoaluminum compound to titanium trichloride can be selected from a wide range of molar ratios of 1: 1 to 1000: 1. The catalyst composed of titanium trichloride and organoaluminum may contain a known third component. As the third component, ε-caprolactam, methyl methacrylate, ethyl benzoate, ester compounds such as methyl toluate, triphenyl phosphite, phosphite such as tributyl phosphite, phosphorus such as hexamethylphosphoric triamide, etc. An acid derivative etc. can be illustrated. The amount of the third component used is generally equimolar or less with respect to the organic aluminum.

When a complex solid compound of a magnesium compound and a titanium compound is used as the transition metal solid catalyst component of the catalyst, the typical metal catalyst component is an organoaluminum compound, particularly AlR ⁵ _p X _3-p (R ⁵ is Carbon number 1
Preferably, the compound is represented by a hydrocarbon group of 18 to 18, X is a halogen selected from Cl, Br and I, hydrogen or an alkoxy group, and p is 3 ≧ p> 2). Specific examples include triethylaluminum, triisobutylaluminum, and mixtures thereof with diethylaluminum chloride or diisobutylaluminum chloride. The catalyst preferably further contains an electron-donating compound, particularly an aromatic monocarboxylic acid ester and / or a silicon compound having a Si—OR ⁶ bond. A silicon compound having a Si—OR ⁶ bond (R ⁶ is a hydrocarbon group having 1 to 20 carbon atoms) is represented by the general formula R ⁷ _a Si (OR ⁶ ).
_An alkoxysilane compound represented by _4-a (R ⁶ and R ⁷ are hydrocarbon groups having 1 to 20 carbon atoms, and a represents a number of 0 ≦ a ≦ 3) is preferably used. Specific examples include tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, ethyltrimethoxysilane, phenyltrimethoxysilane, tetraethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, vinyltriethoxysilane, phenyltriethoxy. Silane, diphenyldimethoxysilane, diphenyldiethoxysilane, butyltriethoxysilane, tetrabutoxysilane, vinyltributoxysilane, diethyldiethoxysilane, cyclohexylmethyldimethoxysilane, cyclohexylethyldimethoxysilane, t-butylmethyldimethoxysilane, iso-butyl Methyldimethoxysilane etc. can be mentioned. The electron donating compound is preferably used in an amount of 1 mol or less, particularly 0.05 to 1 mol, per 1 mol of the organoaluminum compound.

Examples of the composite solid compound of a magnesium compound and a titanium compound include titanium trichloride containing a chloride of magnesium obtained by reducing titanium tetrachloride with an organic magnesium compound, or a solid magnesium compound in a liquid phase of titanium. A so-called "supported catalyst" is used, which is produced by catalytically reacting with a compound. The solid magnesium compound preferably contains an electron-donating compound, particularly an aromatic monocarboxylic acid ester, an aromatic dicarboxylic acid diester, an ether compound, alcohols and / or phenols. The aromatic monocarboxylic acid ester may be allowed to coexist during the catalytic reaction with the titanium compound. There are many patent publications about the composite solid compound of the magnesium compound and the titanium compound, but the catalyst suitable for the purpose of the present invention is described in JP-A Nos. 54-112988 and 54-11958.
No. 6, No. 56-30407, No. 57-59909,
57-59910, 57-59911, 57
-59912, 57-59914, 57-59.
No. 915, No. 57-59916, No. 54-11298.
No. 2, No. 55-133408, No. 58-27704.
No. 61-218606, JP-A-1-319508.
And Japanese Patent Application Laid-Open No. 1-115909. When the soft thermoplastic resin composition of the present invention is used in applications where heat resistance, rigidity, scratch resistance, etc. are required, the crystalline polypropylene is a crystalline propylene homopolymer or a crystalline propylene-α-olefin block copolymer. The isotactic pentad fraction of the boiling heptane-insoluble part of the crystalline propylene homopolymer part which is the first segment polymerized in the first step of 0.970 is 0.970.
Above, and the content of the boiling heptane soluble portion is 5.0% by weight
The content of the xylene-soluble part at 20 ° C. is not more than 2.
It is preferable to use highly crystalline polypropylene of 0% by weight or less.

The isotactic pentad fraction of the boiling heptane-insoluble portion, the content of the boiling heptane-soluble portion and the content of the polymer soluble in xylene at 20 ° C. are as follows.
It is decided as follows. After completely dissolving 5 g of crystalline polypropylene in 500 ml of boiling xylene, the temperature is lowered to 20 ° C. and the mixture is left standing for 4 hours. Then, this is separated by filtration to separate the xylene-insoluble portion at 20 ° C. The filtrate is concentrated and evaporated to dryness to evaporate xylene, and further dried under reduced pressure at 60 ° C to 20 ° C.
A polymer soluble in xylene is obtained. The value obtained by dividing the dry weight by the weight of the charged sample was expressed as a percentage.
It is the content of the 0 ° C xylene soluble part. The 20 ° C xylene-insoluble portion is dried and then Soxhlet extracted with boiling n-heptane for 8 hours. This extraction residue is called a boiling heptane-insoluble part, and the value obtained by subtracting the value obtained by subtracting the dry weight from the charged sample weight (5 g) by the charged sample weight is expressed as a percentage, which is the content of the boiling heptane-soluble part. is there.
The isotactic pentad fraction means A. Zamb
by elli et al., Macromolecules,
6, 925 methods published in (1973), i.e. isotactic sequence in a pentad unit in the crystalline polypropylene molecular chain as measured using the ¹³ C-NMR, propylene monomer units five in other words It is the fraction of propylene monomer units at the center of a chain that is continuously meso-bonded. However, regarding the attribution of NMR absorption peaks, the publication of Macromolecule
s, 8 , 687 (1975). Specifically, the isotactic pentad fraction is measured as the area fraction of the mmmm peak in all the absorption peaks in the methyl carbon region of the ¹³ C-NMR spectrum. By this method, British PHYSICAL L
ABORATORY's NPL reference material CRM No. M1
9-14 Polypropyrene PP / MWD
The isotactic pentad fraction of / 2 was 0.944. The highly crystalline polypropylene is disclosed, for example, in JP-A-60-28405 and 60-2285.
04, 61-218606, 61-28791.
7, JP-A-1-319508, JP-A1-1159.
It can be manufactured by the method exemplified in Japanese Patent Publication No. 09.

When used in applications requiring impact resistance, the crystalline polypropylene is the first polymerized in the first step.
Crystalline propylene-α-olefin comprising a crystalline propylene homopolymer part or a crystalline propylene-α-olefin random copolymer part which is a segment and a propylene-α-olefin random copolymer part which is a second segment polymerized in the second step Preference is given to using block copolymers. The block copolymer can be produced by a slurry polymerization method and a gas phase polymerization method. Especially when it is used in applications where high impact resistance is required, it is necessary to increase the amount of the second segment and it is preferably produced by a gas phase polymerization method. High impact polypropylene obtained by the gas phase polymerization method is disclosed in, for example, JP-A-61 / 1986.
It can be manufactured by the method exemplified in JP-A-287917. In the block copolymer, the first segment has a crystalline propylene homopolymer portion or a crystalline propylene-α-olefin random copolymer portion containing 6 mol% or less of ethylene and / or at least one other α-olefin. Those having a crystalline propylene homopolymer portion are preferable. Second
The segment is ethylene and / or at least 1
Two other alpha-olefins have greater than 10 mole% propylene-alpha-olefin random copolymer moieties. Those having a propylene-α-olefin random copolymer portion of propylene having an ethylene content of 10 mol% or more and ethylene and / or α-olefin having 4 to 6 carbon atoms are preferable. Ethylene content 10
Those having a propylene-ethylene random copolymer portion of not less than mol% are particularly preferable. As the first segment, a crystalline homopolymer portion, and as the second segment, propylene having an ethylene content of 10 mol% or more.
Combinations with ethylene random copolymer moieties are especially preferred. Hereinafter, the copolymer is abbreviated as crystalline propylene-ethylene block copolymer. The second segment is 10 to 70% by weight based on the total polymerization amount.

In the slurry polymerization method, the second segment amount is 1
It is preferably produced in the range of 0 to 30% by weight, and 10 to 70% by weight in the gas phase polymerization method. In the gas phase polymerization method, the second
A crystalline propylene-α-olefin block copolymer having a large amount of segments can be produced by the method exemplified in JP-A-1-98604, and is suitably used for applications requiring ultrahigh impact resistance. The intrinsic viscosity of the second segment in a 135 ° C. tetralin solvent needs to be changed depending on the productivity at the time of production, the powder properties of the polymer or the intrinsic viscosity of the first segment.
15 (dl / g) and 1 to 5 (dl / g in the gas phase polymerization method.
g). Weight ratio of propylene-ethylene random copolymer portion to total block copolymer X
Can be calculated from the following equation by measuring the heats of crystal fusion of the crystalline propylene homopolymer part and the entire block copolymer. X = 1- (ΔHf) _T / (ΔHf) _P (ΔHf) _T : Heat of fusion of the entire block copolymer (cal / g) (ΔHf) _P : Heat of fusion of the crystalline propylene homopolymer portion (cal / g) Propylene -The ethylene content of the ethylene random copolymer portion can be calculated by the following formula by measuring the ethylene content in the whole block copolymer by weight% by the infrared absorption spectroscopy. ^{_{(C '2) EP = (}} C' 2) T / X (C '2) T: Ethylene content of the entire block copolymer ^{_{(wt%) (C' 2) EP}} : Propylene - Ethylene content in the ethylene random copolymer portion ( weight%)

Intrinsic viscosity [η] _EP of 135 ° C. tetralin solution of propylene-ethylene random copolymer part
Can be calculated from the following equation by measuring the intrinsic viscosity of each of the crystalline homopolymer portion and the entire block copolymer. [Η] _EP = [η] _T / X- (1 / X-1) [η] _P [η] _P : Intrinsic viscosity of crystalline propylene homopolymer part (dl / g) [η] _T : Whole block Intrinsic viscosity of copolymer (dl
/ G) The crystalline propylene-ethylene block copolymer used in the soft thermoplastic resin composition of the present invention is as follows. In the crystalline propylene-ethylene block copolymer, the Q value (= ratio of the number average molecular weight to the weight average molecular weight) showing the molecular weight distribution by the GPC (gel permeation chromatography) method of the propylene homopolymer part which is the first segment is 5 or less. , Preferably 4.5
It is below. If the Q value exceeds 5, injection molding cannot obtain a desirable result in terms of the relationship between the molding cycle and surface quality at the time of working. Further, the intrinsic viscosity of the tetralin solution at 135 ° C. of the propylene homopolymer portion is 0.85 to 0.95 (dl /
g). When it exceeds 0.95 (dl / g), the melt flow rate of the composition is low, the fluidity deteriorates, and the filling time becomes long, so that the molding cycle becomes long and good surface quality cannot be obtained. When it is less than 0.85 (dl / g), tensile elongation and low-temperature impact strength are low in terms of physical properties, and good surface quality is obtained in terms of injection moldability, but the plasticization time is long, so the molding cycle is long. It is not possible to obtain favorable results. Propylene - ethylene content of the ethylene random copolymer portion (C _{^'2)
The EP} (% by weight) is preferably 25 to 40% by weight, more preferably 30 to 35% by weight. If it is less than 25% by weight or exceeds 40% by weight, favorable results cannot be obtained with respect to the low temperature impact strength of the composition. The intrinsic viscosity of the propylene-ethylene random copolymer part [η] _EP (dl
/ G) is preferably 4.5 to 5.5 (dl / g), and more preferably 4.8 to 5.3 (dl / g). 4.
If it is less than 5 (dl / g), flow marks are generated during the injection molding process, and if it exceeds 5.5 (dl / g), melamine is generated in the vicinity of the gate, which is not preferable in terms of surface quality.

In the present invention, the ethylene-butene-1 copolymer rubber (B) is a copolymer rubber obtained by polymerizing ethylene and butene-1 by using a so-called Ziegler-Natta catalyst which is a usual production catalyst, As the catalyst, for example, an organoaluminum compound and a trivalent to pentavalent vanadium compound soluble in a hydrocarbon solvent are used in combination. As the aluminum compound, alkylaluminum sesquichloride, trialkylaluminum, dialkylaluminum monochloride, or a mixture thereof is used, and as the vanadium compound, vanadium oxytrichloride, vanadium tetrachloride or VO (O) is used.
A vanadate compound represented by R ⁸ ) _q X _3-q (0 <q ≦ 3, R ⁸ is a linear, branched, or cyclic hydrocarbon having 1 to 10 carbon atoms) and the like can be used. The number average molecular weight of the ethylene-butene-1 copolymer rubber is preferably such that it can be kneaded in an extruder, 10,000 to 10
It is 10,000. If the molecular weight is too small, it will be difficult to handle it when it is supplied to the extruder, and if the molecular weight is too large, the fluidity will be small and processing will be difficult. The molecular weight distribution is also not particularly limited, and any copolymer rubber having various molecular weight distributions, such as monomodal type and bimodal type, which are usually produced or marketed, can be used. Further, ethylene-butene-1-non-conjugated diene copolymer rubber can be used, but the content of non-conjugated diene in the raw material rubber is preferably 7% by weight or less. When the content of non-conjugated diene exceeds 7% by weight, gelation occurs during kneading, which is not preferable. The butene-1 content in the ethylene-butene-1 copolymer rubber is 15 to 20% by weight, preferably 1
It is 6 to 19% by weight, more preferably 17 to 18% by weight. When it is less than 15% by weight, favorable results regarding low temperature impact strength cannot be obtained, and when it exceeds 20% by weight, favorable results regarding Rockwell hardness cannot be obtained. Ethylene
The Q value of the butene-1 copolymer rubber by the GPC method is 2.7.
Or less, preferably 2.5 or less, 70 ° C., intrinsic viscosity in a xylene solution is 1.1 to 2.1 (dl / g) and 100 ° C.
And the Mooney viscosity ML _{1 + 4} 100 is 7 to 90, preferably 1.2 to 2.0 (dl / g) and 10 to 80, respectively.
Is. If the Q value exceeds 2.7, the Rockwell hardness becomes low, which is not preferable. When the intrinsic viscosity in a 70 ° C. xylene solution is less than 1.1 (dl / g) and the Mooney viscosity ML _{1 + 4} 100 at 100 ° C. is less than 7, favorable results regarding Rockwell hardness and low temperature impact strength are not obtained, Further, when it exceeds 2.0 (dl / g) and exceeds 90, respectively, the dispersion with the crystalline polypropylene (A) is poor, and a preferable result cannot be obtained with respect to low temperature impact strength.

In the present invention, the ethylene-propylene copolymer rubber (C) is a copolymer rubber obtained by polymerizing ethylene and propylene using a so-called Ziegler-Natta catalyst which is a usual production catalyst. An organoaluminum compound and a trivalent to pentavalent vanadium compound soluble in a hydrocarbon solvent are used in combination. As the aluminum compound, alkylaluminum sesquichloride, trialkylaluminum, dialkylaluminum monochloride, or a mixture thereof is used, and as the vanadium compound, vanadium oxytrichloride, vanadium tetrachloride or VO (O) is used.
A vanadate compound represented by R ⁸ ) _q X _3-q (0 <q ≦ 3, R ⁸ is a linear, branched, or cyclic hydrocarbon having 1 to 10 carbon atoms) and the like can be used. The number average molecular weight of the ethylene-propylene copolymer rubber is preferably such that it can be kneaded in an extruder, 10,000 to 10
It is 10,000. If the molecular weight is too small, it will be difficult to handle it when it is supplied to the extruder, and if the molecular weight is too large, the fluidity will be small and processing will be difficult. The molecular weight distribution is also not particularly limited, and any copolymer rubber having various molecular weight distributions, such as monomodal type and bimodal type, which are usually produced or marketed, can be used. Further, ethylene-propylene-non-conjugated diene copolymer rubber can be used, but the content of non-conjugated diene in the raw rubber is preferably 7% by weight or less. When the content of non-conjugated diene exceeds 7% by weight, gelation occurs during kneading, which is not preferable. The propylene content of the ethylene-propylene copolymer rubber is 20 to 30% by weight, preferably 2
It is 2 to 28% by weight. If it is less than 20% by weight, favorable results regarding low temperature impact strength cannot be obtained, and if it exceeds 30% by weight, favorable results regarding Rockwell hardness cannot be obtained. The Q value of the ethylene-propylene copolymer rubber by GPC method is 2.7 or less, preferably 2.5 or less, and the intrinsic viscosity in a 70 ° C. xylene solution is 1.8 to 2.2 (dl /
g), and the Mooney viscosity ML _{1 + 4} 100 at 100 ° C. is 35 to 100, preferably 1.9 to 2.1, respectively.
(Dl / g), 50 to 90. If the Q value exceeds 2.7, the Rockwell hardness becomes low, which is not preferable. 70 ° C
The intrinsic viscosity in xylene solution is less than 1.8 (dl / g), and the Mooney viscosity ML _{1 + 4} 100 at 100 ° C. is 3
When it is less than 5, favorable results are not obtained with respect to Rockwell hardness and low temperature impact strength, and each of them is 2.2 (dl /
g) When it exceeds 100, the dispersion with the crystalline polypropylene (A) is poor, and favorable results cannot be obtained with respect to low temperature impact strength.

The talc (D) used in the present invention has an average particle size of 4 μm or less, preferably 3 μm or less.
If it is larger than 4 μm, the impact strength is largely reduced and the appearance such as gloss is deteriorated. Talc may be used without treatment, but various silane coupling agents, titanium coupling agents, and higher fatty acids that are commonly known for the purpose of improving interfacial adhesion with polypropylene resins and improving dispersibility. , Higher fatty acid ester, higher fatty acid amide, higher fatty acid salt, or those whose surface is treated with other surfactant can be used. Here, the average particle diameter of talc is the 50% equivalent particle diameter D obtained from the integral distribution curve of the sieving method measured by suspending it in a dispersion medium such as water or alcohol using a centrifugal sedimentation type particle size distribution measuring device. Means ₅₀ .

In order to use the soft thermoplastic resin composition of the present invention as, for example, a bumper, regarding the physical properties, the scratch resistance is evaluated by Rockwell hardness, and the dimensional stability is evaluated by the coefficient of linear thermal expansion. You can The larger the Rockwell hardness, the better the scratch resistance, and the smaller the coefficient of linear expansion, the better the dimensional stability. Regarding the injection molding workability, it is necessary to evaluate by molding a full-scale large bumper in terms of molding cycle time and surface quality. The fluidity can be evaluated by the melt flow rate, but the plasticization time and surface strain cannot be evaluated by a simple model die, and a large bumper must be molded and evaluated. As a concrete physical property value, the flexural modulus at 23 ° C. is 10
000 (kg / cm ² ) or more, the impact strength at low temperature is 5 (k) for Izod impact strength (with notch) at −30 ° C.
g · cm / cm) or more and the brittleness temperature must be −30 ° C. or less. The Rockwell hardness is preferably 50 or more at 23 ° C., and the linear expansion coefficient of the molded product is −30.
7 × 10 ^-5 (cm / cm ・ in the practical temperature range of -80 ° C)
℃) or less. The soft thermoplastic resin composition of the present invention comprises crystalline polypropylene (A), ethylene-butene-1 copolymer rubber (B), ethylene-propylene copolymer rubber (C) and talc (D), Particularly when a softer thermoplastic composition is obtained, crystalline polypropylene (A) without the addition of talc (D),
Ethylene-butene-1 copolymer rubber (B), ethylene-
It consists of a propylene copolymer rubber (C). Its composition is
When talc (D) is added, the crystalline polypropylene (A) is 40% by weight or more, and the ethylene-butene-1 copolymer rubber (B) is 15 to 25% by weight, preferably 17 to 2
3% by weight, the ethylene-propylene copolymer rubber (C) is 15 to 25% by weight, preferably 17 to 23% by weight, and the talc (D) is 1 to 7% by weight. The total amount of the second segment amount (A) ′ of (A), (B) and (C) is 35 to 5
5% by weight, preferably 32-53% by weight, and (A) 'is 10% by weight or more based on the total amount.
(B) is 40 to 60% by weight, preferably 45 to 55% by weight, based on the total amount of (B) and (C). Further, the total amount of (B), (C) and (D) is 30% by weight or more, preferably 35% by weight or more, and more preferably 37.
It is more than weight%. In injection molding, in order to satisfy both the shortening of the molding cycle and the surface quality, the melt flow rate (230 ° C., under 2.16 kg load) of the composition is 15 to
25 (g / 10 minutes), preferably 17-23 (g / 10
Minutes). When talc (D) is not added, crystalline polypropylene (A) is 50% by weight or more, ethylene-butene-1 copolymer rubber (B) is 15 to 25% by weight, preferably 17 to 23% by weight, ethylene -Propylene copolymer rubber (C) is 15 to 25% by weight, preferably 17 to 2
It is 3% by weight. (A) second segment amount (A) ′,
The total amount of (B) and (C) is 35 to 55% by weight, preferably 32 to 53% by weight, and (A) 'is 10% by weight or more based on the total amount. (B) is 40 to 60% by weight, preferably 45 to 55, relative to the total amount of (B) and (C).
% By weight. Further, the total amount of (B) and (C) is 30% by weight or more, preferably 35% by weight or more, and more preferably 37% by weight or more. In injection molding, the melt flow rate (230 ° C., under 2.16 kg load) of the composition is 15 to 25 (g / 10 minutes), preferably 17 to 23, in order to satisfy both the shortening of molding cycle and surface quality. (G
/ 10 minutes). When the amount of the crystalline polypropylene (A) is less than 40% by weight when the talc (D) is added, and when it is less than 50% by weight, the rigidity and the Rockwell hardness are low. When the ethylene-butene-1 copolymer rubber (B) is less than 15% by weight, low temperature impact strength is low, and when it exceeds 25% by weight, rigidity and Rockwell hardness are low. The same applies to the ethylene-propylene copolymer rubber (C) used in combination. (A) 'is the first of (A)
The impact strength is improved by improving the dispersion of the segments and (B) to (C). When the total amount of (A) ′, (B) and (C) is less than 35% by weight, low temperature impact strength is low, and when it exceeds 55% by weight, rigidity and Rockwell hardness are low.
When (A) 'is less than 10% by weight based on the total amount, favorable results regarding low temperature impact strength cannot be obtained.
Further, (B) is used together with (C) for the purpose of improving low temperature impact strength, but if (B) is less than 40% by weight based on the total amount of (B) and (C), the Rockwell hardness is low, 60
When the content is more than 10% by weight, the low temperature impact strength is low and a desirable result cannot be obtained. Further, when talc (D) is added, if the amount of talc exceeds 7% by weight, the rigidity becomes high and the low temperature impact strength becomes low. (B), the total amount of (C) or (B),
If the total amount of (C) and (D) is less than 30% by weight, the coefficient of linear expansion becomes large and there is a practical problem. When the melt flow rate of the composition is less than 15 (g / 10 minutes), the fluidity is poor, surface distortion occurs, and favorable results cannot be obtained in surface quality, and when it exceeds 25 (g / 10 minutes), the plasticizing time is exceeded. And the molding cycle becomes longer, so that a desirable result cannot be obtained. Thus, the soft thermoplastic resin composition of the present invention has the structure of each component to be used specified as described above,
It can be obtained only by limiting the mixing ratio of each component and the specific range.

The composition of the present invention can be produced by using a kneader such as a single-screw extruder, a twin-screw extruder, a Banbury mixer or a hot roll. The respective components may be mixed at the same time or separately. As a method of divided addition, a method of kneading crystalline polypropylene and talc and then adding an ethylene-butene-1 copolymer rubber and an ethylene-propylene copolymer rubber (hereinafter collectively abbreviated as rubber), or in advance. There is a method in which talc is kneaded with crystalline polypropylene at a high concentration to form a masterbatch, which is separately kneaded while being diluted with crystalline polypropylene, rubber or the like. As a second method of divided addition,
After kneading crystalline polypropylene and rubber, there is a method of kneading by adding talc, or a method of kneading rubber to crystalline polypropylene at a high concentration in advance to form a masterbatch, and then adding crystalline polypropylene and talc and kneading. ..
A third method of divided addition is a method in which crystalline polypropylene and talc, crystalline polypropylene and rubber are kneaded in advance, and finally they are combined and kneaded. The temperature required for kneading is 160 to 230 ° C., and the time is 1 to 20 minutes. Furthermore, in these kneaders, in addition to these basic components, an antioxidant, an ultraviolet absorber,
Additives such as a lubricant, a pigment, an antistatic agent, a copper damage inhibitor, a flame retardant, a neutralizing agent, a foaming agent, a plasticizer, a nucleating agent, an antifoaming agent and a cross-linking agent can be added.

Among these additives, as a composition, it is preferable to add an antioxidant or an ultraviolet absorber in order to improve outdoor weather resistance, heat resistance and oxidation stability. As antioxidants, 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-α-dimethylamino-vara-cresol, 6- (4 -Hydroxy-3,5-di-tert-butylanilino) -2,4-bisoctyl-thio-1,
3,5-triazine, 2,6-di-tert-butyl-4-methylphenol, tris- (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, tetrakis- [methylene-3- (3 ' , 5'-di-tert-butyl-4'-hydroxyphenyl) propionate] methane, diteuril thiodipropionate, and the like, as a UV absorber, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4- Octadecyloxybenzophenone, 4-
Dodecyloxy-2-hydroxybenzophenone, 2-
(2'-Hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2-
(2'-hydroxy-3 ', 5'-di-tert-butyl-phenyl) -5-chlorobenzotriazole, bis- (2,
6-dimethyl-4-piperidyl) sebacate and the like can be mentioned. The soft thermoplastic resin composition of the present invention is excellent in rigidity, Rockwell hardness and low temperature impact strength, and a molded body can be obtained by various molding methods such as extrusion molding, blow molding, press molding or injection molding. Among these, the injection molding method is most preferable in order to further reduce the linear expansion coefficient of the molded body. It has major features in terms of injection moldability such as short molding cycle time and excellent surface quality. Also, the molded body molded by the injection molding method,
Excellent surface quality and small linear expansion coefficient. Therefore, the composition is
It is suitable for use in automobile bumper materials, especially large bumper applications where surface quality and dimensional stability are strictly required.

[0022]

The present invention will be described below with reference to examples, but these are merely examples, and the present invention is not limited to these examples without departing from the gist thereof. Next, methods for measuring physical property values in Examples will be shown below. (1) Melt flow rate According to the method specified in JIS K6758. The measurement temperature is 230 ℃ and the load is 2.16k unless otherwise specified.
It is measured in g. (2) Tensile test According to the method specified in ASTM D638. A test piece molded by injection molding is used. The thickness of the test piece is 3.
It is 2 mm and the tensile elongation is evaluated. The measurement temperature is 23 ° C. unless otherwise specified. (3) Bending test According to the method specified in JIS K7203. A test piece molded by injection molding is used. The thickness of the test piece is 6.
4 mm, span length 100 mm, load speed 2.0
The flexural modulus and flexural strength are evaluated under the condition of mm / min. The measurement temperature is 23 ° C. unless otherwise specified. (4) Izod impact strength According to the method specified in JIS K7110. A test piece molded by injection molding is used. The thickness of the test piece is 6.
It is 4 mm, and the impact strength with notch that is notched after molding is evaluated. The measurement temperature is 23 ° C. unless otherwise specified. When the temperature is other than the above, the measurement is performed after the condition is adjusted for 2 hours in a constant temperature bath.

(5) Embrittlement temperature According to the method specified in JIS K6758. A predetermined 6.3 × 38 × 2 (mm) test piece is punched out from a 25 × 150 × 2 (mm) flat plate formed by injection molding, and evaluation is performed by a predetermined method. (6) Rockwell hardness According to the method specified in JIS K7207. A test piece molded by injection molding is used. The test piece has a thickness of 3.0
Two sheets having a thickness of 2 mm were used by stacking them. The steel ball is R, and the evaluation value is displayed on the R scale. (7) Heat distortion temperature According to the method specified in JIS K7207. Fiber stress is measured at 4.6 kg / cm ² . (8) As a linear expansion coefficient measuring device, a thermomechanical analyzer T manufactured by Shimadzu Corporation
The measurement was carried out as follows using MA-40. 100 × 400 × 3 molded by injection molding unless otherwise specified
(Mm) flat plate test pieces are used. Flat plate at 120 ℃ 30
After annealing for 1 minute, 12.7 x 12.7 x from the center
A test piece of 3 (mm) is cut out, and the dimension at 23 ° C. is accurately measured. Set in the device so that the dimensional change in the MD or TD direction during injection molding can be measured. The temperature is raised at −30 to 80 ° C. at a heating rate of 5 ° C./min, and the dimensional change in the MD or TD direction during that is measured. The dimensional change per unit length and unit temperature is obtained as a linear expansion coefficient by calculation based on the dimension at 23 ° C. (9) Mooney viscosity Measured by the method specified in JIS K6300.
The measurement temperature is 100 ° C. (10) Ethylene content, propylene content, butene-1 content press sheet for ethylene content or propylene content appearing in the infrared absorption spectrum was fabricated to measure a methyl group (-CH ₃₎ and methylene group - the (-CH ₂₎ The absorbance of characteristic absorption was used, and the butene-1 content was determined by the calibration curve method using the absorbance of characteristic absorption of the ethyl group.

(11) Intrinsic viscosity The reduced viscosities were measured at three concentrations of 0.1, 0.2 and 0.5 g / dl using an Ubbelohde viscometer. Intrinsic viscosity is described in “Polymer Solution, Polymer Experiments 11” (198
2 years Kyoritsu Shuppan Co., Ltd.) The calculation method described on page 491, that is, the reduced viscosity was plotted against the concentration, and the concentration was determined by extrapolation to zero. The crystalline polypropylene was evaluated at a temperature of 135 ° C. using tetralin as a solvent. The ethylene-butene-1 copolymer rubber and the ethylene-propylene copolymer rubber were evaluated at a temperature of 70 ° C. using xylene as a solvent. (12) Molecular weight distribution It was measured by gel permeation chromatography (GPC), and the measurement was performed under the following conditions. Crystalline polypropylene GPC: Waters 150C type column: Showa Denko Shodex 80 MA 2
Sample volume: 300 μl (polymer concentration 0.2 wt%) Flow rate: 1 ml / min Temperature: 135 ° C. Solvent: o-dichlorobenzene Using standard polystyrene manufactured by Toyo Soda Co., Ltd., a calibration curve for the elution volume and molecular weight was obtained. Created. The polystyrene-reduced weight average molecular weight and number average molecular weight of the sample were determined using a calibration curve, and Q value = weight average molecular weight / number average molecular weight was determined as a measure of the molecular weight distribution. Ethylene-butene-1 copolymer rubber, ethylene-propylene copolymer rubber GPC: Waters 150C type column: Showa Denko Shodex 80 MA 1
Sample volume: 300 μl (polymer concentration 0.2 wt%) Flow rate: 1 ml / min Temperature: 145 ° C. Solvent: o-dichlorobenzene Using standard polystyrene manufactured by Toyo Soda Co., Ltd., a calibration curve for the elution volume and molecular weight was obtained. Created. The polystyrene-reduced weight average molecular weight and number average molecular weight of the sample were determined using a calibration curve, and Q value = weight average molecular weight / number average molecular weight was determined as a measure of the molecular weight distribution. (13) Talc average particle size (D ₅₀ ) Using a centrifugal sedimentation type particle size distribution analyzer SA-CP2-20 manufactured by Shimadzu Corporation as a measuring device, talc was suspended in water, and a small amount of sodium hexametaphosphate was further added to obtain a uniform suspension. As a suspension, it was put into a cell to have a liquid surface height of 3 cm, and a particle size distribution curve was measured at a rotation speed of 500 rpm. An integral cloth cloth curve was prepared by a sieving method plot, and an average particle diameter D ₅₀ corresponding to 50% by weight was obtained.

(14) Evaluation of injection molding processability The composition was dried in a hot air dryer at 120 ° C. for 2 hours, and the automobile bumper shown in FIG. 1 was evaluated by injection molding under the following molding conditions. The dimensions and weight of the injection-molded bumper are as follows. Bumper dimensions 1) Perimeter 2930 mm 2) Width l ₁ : 510 mm, l ₂ : 370 mm 3) Wall thickness 4 mm 4) Gate width 600 mm Bumper weight 4900-5000 g Ube Industries UBEMAX-UV 4000-830
I. M. M. Cylinder set temperature 2 using die injection molding machine
Molding was carried out at the following standard cycle at 00 ° C. and mold set temperature of 30 ° C. Die down- [Injection-Screw forward]-
[Holding pressure-cooling, plasticization (measurement)]-Die rise- [Extrusion-
Take-out] cycle. The sum of these times is called the molding cycle time. However, parts in parentheses are steps that proceed simultaneously. Figure 1 shows the phenomenon of poor surface quality of bumpers.
It was shown to. The defective phenomena are 2 ...
..Gate strain, 4 ... end strain, 5 ... flow mark. Melamella is a regular streaky irregularity that occurs in the flow direction near the gate. The gate strain and the terminal strain are undulations generated near the gate and at the terminal, respectively, and both are collectively called surface strain. The flow mark is a regular strip-shaped irregularity that occurs at the end at right angles to the flow direction. In all cases, the surface of the mold is not faithfully transferred and micron-order distortion is generated on the surface of the bumper molded body, which is a defective phenomenon of the surface. In order to eliminate surface distortion in the surface defect phenomenon, methods such as lengthening the pressure holding time and the cooling time are mainly used. The plasticizing time basically needs to be within the range of the cooling time. If the plasticizing time does not fall within the range of the cooling time even if the cooling time becomes short, the molding cycle time will not be shortened as a result. Therefore, the molding cycle time is evaluated by the following items. 1) Holding time for eliminating surface strain 2) Cooling time for eliminating surface strain 3) Plasticization time On the other hand, the surface quality is evaluated by the following items. 1) Surface strain 2) Flow mark 3) Mela Mela (15) Pendulum test According to the method specified in FMVSS 581. An impact test was performed on the bumper molded body obtained by the above injection molding. Measurement temperature is -30 ° C, effective impact mass is 1000k
g.

(16) Initial Adhesion of Coating The cut-out piece of the bumper obtained by the above injection molding was used as a test piece, and this test piece was subjected to surface treatment in 1,1,1-trichloroethane vapor (74 ° C.) for 30 seconds. After washing and drying at room temperature, as a primer, RB29 manufactured by Nippon Bee Chemical Co., Ltd.
1H is applied and baked in an oven at 100 ° C for 20 minutes, and then a urethane-based paint (Flexen # 101 manufactured by Nippon Bee Chemical Co., Ltd.) is spray-applied at 120 ° C.
Baking finish for 40 minutes in the oven. A razor blade was applied to the coating film of this coating test, and a square of 2 mm square 10
After carving 0 pieces (10 length x 10 width), crimping a 24 mm wide cellophane tape (made by Nichiban Co., Ltd.) with fingers, grasping the end face, and peeling it all at once Was evaluated as the residual rate (%). (17) Dimensional stability The bumper obtained by the above injection molding was subjected to 1
After annealing for a period of time, it was mounted on the body of an automobile and a heat cycle test was conducted under the following conditions. The degree of displacement between the bumper and the body at 80 ° C and -30 ° C in the heat cycle test was visually evaluated. Hold at 80 ° C for 7.5 hours, then at 23 ° C for 0.5 hours, then -30
Hold at 7.5 ° C for 7.5 hours. This is set as one cycle, and this is repeated for four cycles. Above (2), (3),
The test pieces for evaluating physical properties of (4), (6) and (7) were produced under the following injection molding conditions unless otherwise specified.
The composition was dried in a hot air drier at 120 ° C. for 2 hours and then molded at a molding temperature of 20 using an IS150E-V type injection molding machine manufactured by Toshiba Machine.
Injection molding was performed at 0 ° C., mold temperature 50 ° C., injection time 15 sec, and cooling time 30 sec. The above-mentioned (5) test piece for evaluating physical properties was produced under the following injection molding conditions unless otherwise specified. The composition is dried in a hot air dryer at 120 ° C for 2
After drying for an hour, injection molding was performed using a FS75 (N) type injection molding machine manufactured by Nissei Plastic Industry Co., Ltd. at a molding temperature of 200 ° C., a mold cooling temperature of 50 ° C., an injection time of 15 sec, and a cooling time of 30 sec. The test piece for evaluating physical properties in (8) above was manufactured under the following injection molding conditions unless otherwise specified. The composition was dried in a hot air dryer at 120 ° C. for 2 hours and then molded at a molding temperature of 20 using a Sumitomo Heavy Industries, Ltd. Neomat 515/150 type injection molding machine.
Injection molding was performed at 0 ° C., mold temperature 50 ° C., injection time 15 sec, and cooling time 30 sec. The following compositions were produced under the following conditions unless otherwise specified. Predetermined amounts of each component were weighed and uniformly pre-mixed with a Henschel mixer, then a continuous twin-screw kneader (TEX made by Japan Steel Works Ltd.)
44 SS 30BW-2V type) extrusion rate 30 kg /
The resin temperature was 180 ° C., the screw rotation speed was 350 rotations / minute, and the suction was performed under vent suction. The screw was constructed by arranging a three-row type rotor and a kneading disk in two kneading zones, each in the zone next to the first feed port and the second feed port. In the following Examples and Comparative Examples, the raw materials obtained by the methods described in Reference Examples 1 to 4 were used.

Reference Example 1: Production of crystalline polypropylene (A) PP-1; crystalline polypropylene is disclosed in JP-A-60-228.
It was produced by the slurry polymerization method described in Japanese Patent Publication No. 504. Melt flow rate (hereinafter referred to as MFR) is 60 (g /
10 minutes), an intrinsic viscosity in a solvent of 135 ° C. tetralin (hereinafter abbreviated as [η] _T ) is 1.4 (dl / g), and a homopolymer portion of propylene which is the first segment polymerized in the first step ( The proportion of the P portion is 88% by weight, and the proportion of the random copolymer part of ethylene and propylene (hereinafter abbreviated as EP portion) which is the second segment polymerized in the second step (hereinafter abbreviated as EP content) ) Is 12
% By weight, the Q value of the molecular weight distribution of the P part is 7, and the intrinsic viscosity in a 135 ° C. tetralin solvent (hereinafter [η]
_P (abbreviated as _P ) is 0.9 (dl / g), and the content of the cold xylene-soluble portion at 20 ° C. (hereinafter abbreviated as CXS) is 2.4.
% By weight, content of boiling heptane-soluble portion (hereinafter abbreviated as BHS) is 6.5% by weight, isotactic pentad fraction of boiling heptane-insoluble portion (hereinafter abbreviated as IPF)
Is 0.972, the molecular structure of the EP part is 135 ° C, and the intrinsic viscosity in a tetralin solvent (hereinafter abbreviated as [η] _EP )
Is 5.2 (dl / g) and the proportion of ethylene content is 100% by weight of EP part (hereinafter abbreviated as (C ' ₂ ) _EP )
Is 32 wt% crystalline propylene-ethylene block copolymer. PP-2; crystalline polypropylene is disclosed in JP-A-1-3195.
It was produced by the slurry polymerization method described in JP-A-08. MFR
Is 58 (g / 10 minutes) and [η] _T is 1.4 (dl /
g), the EP content is 12% by weight, the Q value of the P part is 4,
[Η] _P is 0.9, CXS is 0.9% by weight, BHS is 3.6% by weight, IPF is 0.972, and [η] _EP of the EP part is 5.2 (dl / g), A crystalline propylene-ethylene block copolymer having a (C ′ ₂ ) _EP of 32% by weight. Hereinafter, crystalline propylene-ethylene block copolymers PP-3 to PP-10 having the molecular structures shown in Table 1 were produced by the same production method as PP-2. Table 1 collectively shows the contents of the crystalline polypropylenes PP-1 to PP-10.

Reference Example 2: Production of ethylene-butene-1 copolymer rubber (B) An ethylene-butene-1 copolymer rubber was prepared in JP-B-44-93.
Polymerization was carried out by a homogeneous solution method with reference to the method described in JP-A-90. EBR-1; butene-1 content 25% by weight, intrinsic viscosity in 70 ° C xylene solution is 1.0 (dl / g), 100 ° C
Ethylene-butene-1 copolymer rubber having a Mooney viscosity ML _{1 + 4} 100 of 3 and a molecular weight distribution Q value of 2.0. EBR-2 to EB having different molecular structures in a similar manner
Up to R-5, four kinds of ethylene-butene-1 copolymer rubbers were polymerized. The contents of the five ethylene-butene-1 copolymer rubbers including EBR-1 are summarized in Table 2.

Reference Example 3: Production of ethylene-propylene copolymer rubber (C) Polymerization was carried out in the same manner as in Reference Example 2. EPR-1; propylene content 27% by weight, intrinsic viscosity in 70 ° C. xylene solution is 1.5 (dl / g), 100 ° C.
An ethylene-propylene copolymer rubber having a Mooney viscosity ML _{1 + 4} 100 of 23. In the same manner, four kinds of ethylene-propylene copolymer rubbers having different molecular structures, EPR-2 to EPR-5, were polymerized. Table 3 summarizes the contents of the five ethylene-propylene copolymers including EPR-1.

Reference Example 4: Talc (D) Talc rough ore was mechanically crushed and classified by a dry method to obtain talc having the following average particle size. Talc-1; D ₅₀ = 2.1 μm

Examples 1 to 3, Comparative Examples 1 to 7 As ethylene-butene-1 copolymer rubber (B), EB
R-2, EPR-2 is used as the ethylene-propylene copolymer rubber (C), and various crystalline propylene-ethylene block copolymers PP-1 to PP-10 shown in Table 1 are used as the crystalline polypropylene (A). I was there. The blending ratio of each component in% by weight was fixed as follows. Crystalline polypropylene (A): EBR-2: EPR-
2: = 62: 19: 19 crystalline polypropylene (A)
Is a Q value, [η] _P , CX from PP-1 to PP-10.
S, BHS, IPF, [η] _EP , and (C ′ ₂ ) _{EP having} different structures were used. These compositions were kneaded under predetermined conditions to prepare a composition, and test pieces were injection-molded under the predetermined conditions. Table 4 shows the results of physical property evaluation. Further, the injection molding processability of these compositions was evaluated by a predetermined method. The evaluation results are shown in Table 5. The examples of the present invention are superior to the comparative examples in both physical properties such as tensile elongation, low temperature Izod impact strength, embrittlement temperature and injection molding processability. Example 1
~ 3 is CXS, BHS of crystalline polypropylene (A)
And compositions with different levels of IPF. The physical properties and molding processability of each composition are good. Comparing these, the less CXS and BHS, the more I
The higher the PF, the higher the flexural modulus, heat distortion temperature, and Rockwell hardness.

Example 4, Comparative Examples 8-10 PP-2 was used as the crystalline polypropylene (A), EPR-2 was used as the ethylene-propylene copolymer rubber (C), and the ethylene-butene-1 copolymer rubber ( As B), those having various molecular structures shown in Table 2 were used. The blending ratio of each component in% by weight was fixed as follows. PP-2: ethylene-butene-1 copolymer rubber (B):
EPR-2: = 62: 19: 19 The ethylene-butene-1 copolymer rubber (B) has the butene-1 content, intrinsic viscosity from EBR-1 to EBR-5 except for EBR-2 used in Example 1. The one having a different Mooney viscosity was used. These compositions were kneaded under predetermined conditions to prepare a composition, and a test piece was injection-molded under the predetermined conditions. Table 6 shows the physical property evaluation results. The examples of the present invention have a better balance between the brittle temperature and the Rockwell hardness than the comparative examples.

Example 5, Comparative Examples 11 to 13 PP-2 was used as the crystalline polypropylene (A), EBR-2 was used as the ethylene-butene-1 copolymer rubber (B), and the ethylene-propylene copolymer rubber (C ) Having various molecular structures shown in Table 3 were used. The blending ratio of each component in% by weight was fixed as follows. PP-2: EBR-4: ethylene-propylene copolymer rubber (C): = 62:19:19 The ethylene-propylene copolymer rubber (C) is EPR-1 except for EPR-2 used in Example 1. Up to EPR-5, those having different propylene content, intrinsic viscosity and Mooney viscosity were used. These compositions were kneaded under predetermined conditions to prepare a composition, and a test piece was injection-molded under the predetermined conditions. The results of evaluation of physical properties are shown in Table 7. The examples of the present invention have a better balance between the brittle temperature and the Rockwell hardness than the comparative examples.

Example 6 59% by weight of PP-2 was used as the crystalline polypropylene (A), and E was used as the ethylene-butene-1 copolymer rubber (B).
A composition was prepared in the same manner as in Example 1 using 19% by weight of BR-2, 19% by weight of ethylene-propylene copolymer rubber (C) and EPR-2, and 3% by weight of talc-1 as talc (D). Then, a test piece was prepared. Table 8 shows the results of physical property evaluation.

Comparative Example 14 A composition was prepared in the same manner as in Example 6 except that PP-2 was 52% by weight and talc-1 was 10% by weight in the composition of Example 6, and a test piece was prepared and evaluated. did. Table 9 shows the physical property evaluation results.

Examples 7 to 8 and Comparative Examples 15 to 16 Automotive bumpers were molded from the compositions of Examples 1 and 6 and Comparative Examples 1 and 14 by injection molding under predetermined conditions.
The bumper pendulum test, initial paint adhesion, dimensional stability and scratch resistance were evaluated. The scratch resistance was qualitatively evaluated visually by observing the degree of damage to the molded product during handling during the coating operation. Table 1 shows these evaluation results.
It shows in 0. In the practical evaluation using the bumper, Examples 7 to 8 gave good results in all items, while Comparative Examples 15 to 16 each showed some points of failure.

[0037]

The soft thermoplastic resin composition according to the present invention is excellent in low-temperature impact strength, rigidity, injection moldability, and dimensional stability essential for large-sized injection-molded articles, and is excellent in handling molded articles. It has a great effect in that the problematic scratch resistance is good. The novel soft thermoplastic resin composition provided by the present invention can be easily processed into a molded product, a film, a sheet and the like by a usual processing method such as injection molding, extrusion molding and press molding.
Among them, the injection molding method is the most preferable molding method in the sense that it imparts good dimensional stability to the soft thermoplastic resin composition. Suitable for use in rigid bumpers.

[0038]

[Table 1]

[0039]

[Table 2]

[0040]

[Table 3]

[0041]

[Table 4]

[0042]

[Table 5]

[0043]

[Table 6]

[0044]

[Table 7]

[0045]

[Table 8]

[0046]

[Table 9]

[0047]

[Table 10]

[Brief description of drawings]

FIG. 1 is a perspective view of a part of an injection-molded bumper.

[Explanation of Codes] 1 ... Gate portion, 2 ... Melamella, 3 ... Gate distortion, 4 ... End distortion, 5 ... Flow mark, l
₁ ... Bumper width, l ₂ ... Bumper width

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location C08L 53/00 LLY 7142-4J // (C08L 23/10 53:00 23:08) B29K 23: 00 B29L 31:30 4F (72) Masashi Yamamoto 5-1 Anezaki Kaigan, Ichihara, Chiba Sumitomo Chemical Co., Ltd. (72) Inventor Tsukasa Wakatsuki 1-5 Anesaki Kaigan, Ichihara, Chiba Sumitomo Chemical Co., Ltd. Company (72) Inventor Takao Nomura 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor Takesumi Nishio 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor Hisayuki Iwai 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Corporation

Claims (4)

[Claims] 1. Crystalline polypropylene (A): 50% by weight
Above, ethylene-butene-1 copolymer rubber (B): 15
To 25% by weight, ethylene-propylene copolymer rubber (C): 15 to 25% by weight, the crystalline polypropylene (A) is one selected from the following (i) or (ii), and ( A), (B), and (C) have the following structures and physical properties, and when the amount of the second segment of the crystalline propylene-ethylene block copolymer of (A) is (A) ', the formula: (A) + (B) + (C) = 100 wt% (1) (B) + (C) ≧ 30 wt% (2) 0.35 ≦ {[(A) ′ + (B) + (C)] / 100 } ≦ 0.55 (3) 0.1 ≦ {(A) ′ / [(A) ′ + (B) + (C)]} (4) 0.4 ≦ {(B) / [(B) + (C)]} ≦ 0.6 (5) and the melt flow rate (230 ° C., 2.1
Under a load of 6 kg) is 15 to 25 (g / 10 minutes), and 2
Flexural modulus at 3 ° C is 10,000 (kg / cm ² )
The following is a soft thermoplastic resin composition.
However, the crystalline polypropylene (A): (i) the Q value (= ratio of the weight average molecular weight to the number average molecular weight) of the propylene homopolymer portion which is the first segment by GPC (gel permeation chromatography) is 5 or less, The 135 ° C. tetralin solution has an intrinsic viscosity of 0.85 to 0.95 (dl / g), and the 135 ° C. tetralin solution of the propylene-ethylene random copolymer portion of the second segment has an intrinsic viscosity of 4.5 to 5.5.
(Dl / g), the ratio of propylene / ethylene is 75/2
5 to 60/40 (weight% ratio) crystalline propylene-
Ethylene block copolymer, (ii) the crystalline propylene-ethylene block copolymer of (i) and a Q value by GPC method of 5 or less, and the intrinsic viscosity of a 135 ° C. tetralin solution is 0.85 to 0.95 (dl /
g) a mixture of crystalline propylene homopolymers, ethylene-butene-1 copolymer rubber (B): Q value by GPC method of 2.7 or less, butene-1 content of 15 to 20% by weight, 70 ° C xylene. The intrinsic viscosity of the solution is 1.1 to 2.1
(Dl / g) and Mooney viscosity at 100 ° C ML _{1 + 4}
100 is 7 to 90, ethylene-propylene copolymer rubber (C): Q value by GPC method is 2.7 or less, propylene content is 20 to 30% by weight, and intrinsic viscosity of 70 ° C xylene solution is 1.8 to 2 .2
(Dl / g) and Mooney viscosity at 100 ° C ML _{1 + 4}
100 is 35-100. 2. The crystalline polypropylene (A) according to claim 1, 40% by weight or more, ethylene-butene-1 copolymer rubber (B): 15 to 25% by weight, ethylene-propylene copolymer rubber (C). ): 15-
25% by weight and talc (D) having an average particle size of 4 μm or less: 1 to 7% by weight, and (A),
(B), (C), and (D) are formulas (A) + (B) + (C) where (A) is the second segment amount of the crystalline propylene-ethylene block copolymer of (A). + (D) = 100% by weight (1) (B) + (C) + (D) ≧ 30% by weight (2) 0.35 ≦ {[(A) ′ + (B) + (C)] / 100 } ≦ 0.55 (3) 0.1 ≦ {(A) ′ / [(A) ′ + (B) + (C)]} (4) 0.4 ≦ {(B) / [(B) + (C)]} ≦ 0.6 (5) and the melt flow rate (230 ° C., 2.1
Under a load of 6 kg) is 15 to 25 (g / 10 minutes), and 2
Flexural modulus at 3 ° C is 10,000 (kg / cm ² )
The following is a soft thermoplastic resin composition. 3. An injection-molded article obtained by molding the soft thermoplastic resin composition according to claim 1 or 2 by an injection molding method. 4. The injection molded body according to claim 3, wherein the injection molded body is a bumper.