JPH0551498A - Thermoplastic resin composition and its injection-molded article - Google Patents

Abstract

PURPOSE:To provide a thermoplastic resin having excellent low-temperature impact strength, rigidity and Rockwell hardness and small linear expansion coefficient and suitable for injection molded article such as automobile bumper. CONSTITUTION:The objective composition is produced by compounding (A) 50-75wt.% (especially 60-65wt.%) of a crystalline polypropylene with (B) 15-35wt.% (especially 20-28wt.%) of an ethylene/butene-1 copolymer rubber having a butene-1 content of 20-30wt.%, intrinsic viscosity of 1.1-2(dl/g) in xylene at 70 deg.C and a Mooney viscosity of 10-40 at 100 deg.C and (C) 5-20wt.% (especially 10-18wt.%) of talc having an average particle diameter of <=4mum. The sum of the components B and C is >=30wt.%, especially >=35wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is mainly composed of crystalline polypropylene and is blended with a specific ethylene-butene-1 copolymer rubber and talc and is excellent in rigidity, low temperature impact resistance and scratch resistance. The present invention relates to a novel thermoplastic resin composition and an injection-molded article excellent in dimensional stability obtained by molding the composition by an injection molding method, particularly to a bumper for automobiles.

[0002]

2. Description of the Related Art Recently, in order to reduce the weight and safety of automobile bumpers, polyurethane bumpers and crystalline propylene-ethylene block copolymer bumpers have begun to be used in place of conventional iron bumpers. However, the polyurethane bumper is expensive and has a relatively high specific gravity, and the crystalline propylene-ethylene block copolymer bumper is excellent in thermal properties such as rigidity and heat distortion temperature, but has low impact strength at low temperature. Low.

In order to improve low temperature impact strength, it is known to compound an ethylene-propylene copolymer rubber with a crystalline propylene-ethylene block copolymer, for example, Japanese Patent Laid-Open No. 53-2.
Proposed in 2552 and 53-40045. However, since the ethylene-propylene copolymer rubber is blended, the thermal properties such as rigidity and heat distortion temperature are poor, and in order to solve this, further calcium carbonate, barium sulfate,
Mixing by adding an inorganic filler such as mica, crystalline calcium silicate and talc is disclosed in, for example, JP-A-51-136735.
No. 53, No. 53-64256, No. 53-64257, No. 55-3374, No. 57
-55952, 57-207630, 58-17139, 58-111846
No. 59-98157 and the like. Among them, the composition for bumper is disclosed in JP-A-57-55952 and 57-2.
No. 07630, No. 58-111846, No. 59-98157, etc., especially in JP-A No. 51-136735, talc, No. 57-2.
No. 07630 describes that talc, mica or calcium silicate can further reduce the molding shrinkage, that is, the effect of improving dimensional stability.

For the same purpose, in JP-A Nos. 58-17139 and 58-17140, a crystalline propylene-ethylene block copolymer is used in place of an ethylene-propylene copolymer rubber and an ethylene-butene-polymer rubber. It has been proposed to compound one copolymer rubber. Particularly, in JP-A-58-17140, by using an ethylene-butene-1 copolymer rubber, it is possible to reduce the impact whitening area as compared with the ethylene-propylene copolymer rubber and to improve the scratch resistance. It is described that it can be obtained.

The composition of crystalline propylene-ethylene copolymer / ethylene-propylene copolymer rubber / talc (hereinafter abbreviated as ethylene-propylene copolymer rubber-based composition) has a problem in scratch resistance. It is widely used for bumpers because it is inexpensive and has good moldability. Recently, together with the problem of recycling, there is a movement to replace reinforced RIM-urethane. On the other hand, the bumper is required to have a feeling of unity with the body as a part of the design of the automobile, and therefore the resin material for the bumper is required to have dimensional stability close to that of iron used in Hoddy. ..

Physically, the scratch resistance can be evaluated by Rockwell hardness, and the dimensional stability can be evaluated by a coefficient of linear thermal expansion. The larger the Rockwell hardness is, the better the scratch resistance is, and the smaller the linear expansion coefficient is, the better the dimensional stability is. However, the ethylene-propylene copolymer rubber-based composition is
The fact is that the use of propylene copolymer rubber has limitations in scratch resistance and dimensional stability.

[0007]

In view of the above situation, the present invention mainly uses crystalline polypropylene, which satisfies the low temperature impact strength and rigidity required for bumpers, and is ethylene-propylene which has been conventionally used. It is an object of the present invention to obtain a thermoplastic resin composition having a higher level of Rockwell hardness and a smaller linear expansion coefficient than a copolymer rubber composition, and further to provide an injection molded article from the composition.

[0008]

According to the present invention, crystalline polypropylene (A): 50 to 75% by weight, ethylene-butene-1 copolymer rubber (B): 15 to 35% by weight, talc (C): 5 to 20% by weight, and the butene-1 content of the ethylene-butene-1 copolymer rubber (B) is 20 to 30.
Wt%, intrinsic viscosity in 70 ° C. xylene solution is 1.1-
2.0 (dl / g), Mooney viscosity ML _{1 + 4} 10 at 100 ℃
0 is 10 to 40, the average particle diameter of talc (C) is 4 μm or less, and the total amount of (B) and (C) is 30% by weight or more, and the thermoplastic resin composition. The present invention relates to an injection-molded article, which is obtained by molding a thermoplastic resin composition by an injection molding method, and a bumper.

In the present invention, the crystalline polypropylene (A) means (a) a crystalline propylene homopolymer,
(B) a crystalline propylene-α-olefin random copolymer obtained by copolymerizing propylene and 6 mol% or less of ethylene and / or at least one other α-olefin (for example, butene-1, hexene-1, etc.), ( c) a crystalline propylene homopolymer portion as the first segment polymerized in the first step, or ethylene and / or at least one other α-olefin (for example, butene-1, hexene-1, etc.) is 6 mol% or less. Having a crystalline propylene-α-olefin random copolymer moiety, ethylene and / or at least one other α-olefin (eg, butene-1, hexene-1, etc.) is used as the second segment polymerized in the second step. Crystalline propylene having a propylene-α-olefin random copolymer moiety of not less than mol% It refers to at least one selected from the emissions -α- olefin block copolymers.

The crystalline polypropylene can be obtained, for example, by reacting it in the presence of a combination catalyst of titanium trichloride and an alkylaluminum compound, which is usually called a Ziegler-Natta type catalyst.

The polymerization can be carried out between 0 ° C. and 300 ° C. However, in the highly stereoregular polymerization of α-olefins such as propylene, it is usually preferable to carry out the polymerization 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. Is. The polymerization pressure is not particularly limited, but a pressure of about 3 to 100 atm is desirable from the viewpoint of being industrial and economical.

The polymerization method may be either continuous or batch. As the polymerization method, butane, pentane, hexane, heptane, slurry polymerization with an inert hydrocarbon solvent such as octane, solvent polymerization in which the resulting polymer is polymerized in a state of being dissolved in the inert hydrocarbon solvent, without solvent Bulk polymerization in liquefied monomers and vapor phase polymerization in gaseous monomers are possible. A chain transfer agent such as hydrogen can be added to adjust the molecular weight of the polymer.

The polypropylene used in the present invention can be prepared using an iospecific Ziegler-Natta catalyst. It is preferable that the catalyst used has a high isospecificity.

The catalyst which can be preferably used is a composite solid compound of which the transition metal catalyst component is a titanium trichloride or magnesium compound having a layered crystal structure and a titanium compound, and the 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. Aluminum as a reducing agent,
Metals such as titanium, hydrogen, and organometallic compounds are known. 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 AA)
Is. 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 is represented by the general formula R ¹ —O—R ² (R ¹ and R ² are alkyl groups having 1 to 18 carbon atoms), and di-n-butyl ether and di-t-amyl ether are preferred. Used. Halogen compounds are iodine, iodine trichloride, titanium halides are titanium tetrachloride, halogenated hydrocarbons are carbon tetrachloride,
It is preferably selected from 1,2-dichloroethane. The organoaluminum compound has 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, n is a number satisfying 3 ≧ n> 1, and diethylaluminum chloride, ethylaluminum sesquichloride, etc. Is preferred.

Regarding the production method of these titanium trichloride, JP-A-47-34470, JP-A-53-33289, JP-A-53-51285,
54-11986, 58-142903, 60-28405, 60-2
It is described in detail in Japanese Patent No. 28504.

When titanium trichloride having a layered crystal structure is used as the transition metal compound component, the typical metal compound component is represented by the general formula AlR ⁴ _m X _3-m (R ⁴ is 1 to 1 carbon atoms).
Preferred are 18 hydrocarbon groups, X is a halogen selected from Cl, Br and I, and m is 3 ≧ m> 0). Specifically, it is a compound in which R ⁴ is an ethyl or isobutyl group and m is 2.5 ≧ m ≧ 1.5, and diethylaluminum chloride, diethylaluminum bromide, diethylaluminum iodide and triethylaluminum or ethylaluminum dichloride are used. The mixture of can be illustrated. When using the third component described later together, 3 ≧ m ≧ 2.5
Alternatively, an organoaluminum compound having 1.5 ≧ m> 0 can also be preferably used. 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. Ester compounds such as ε-caprolactam, methyl methacrylate, ethyl benzoate and methyl toluate as the third component,
Examples thereof include phosphite esters such as triphenyl phosphite and tributyl phosphite, and phosphoric acid derivatives such as hexamethylphosphoric triamide. The amount of the third component to be used must be experimentally determined for each individual compound because the acting power varies depending on the compound, but it is generally not more than equimolar to the organoaluminum.

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
Compounds represented by a hydrocarbon group of 18 to 18, X is a halogen selected from Cl, Br and I, and p is 3 ≧ p> 2) are preferable. 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. Si-O
R ⁶ bond (R ⁶ is a hydrocarbon group having 1 to 20 carbon atoms)
The silicon compound having the general formula is represented by the general formula R ⁷ _a Si (OR ⁶ ).
_4-a (R ⁶ and R ⁷ are hydrocarbon groups having 1 to 20 carbon atoms,
a represents a number of 0 ≦ a ≦ 3. An alkoxysilane compound represented by the formula (4) is preferably used. Specific examples include tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, ethyltrimethoxysilane, phenyltrimethoxysilane, tetraethoxysilane, methyltriethoxysilane, ethyltriethoxysilane,
Examples thereof include vinyltriethoxysilane, phenyltriethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, butyltriethoxysilane, tetrabutoxysilane, vinyltributoxysilane and diethyldiethoxysilane. The electron-donating compound is 1 mol or less with respect to 1 mol of the organoaluminum compound,
It is particularly preferably used within the range of 0.05 to 1 mol.

As the composite solid compound of a magnesium compound and a titanium compound, titanium trichloride containing magnesium chloride 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.

The above-mentioned composite solid compound of a magnesium compound and a titanium compound is described in many patent publications, but catalysts suitable for the purpose of the present invention are disclosed in JP-A-54-112988 and JP-A-54-119586. 56-30407, 57
-59909, 57-59910, 57-59911, 57-59912
No. 57, No. 57-59914, No. 57-59915, No. 57-59916, No. 54
-112982, 55-133408, 58-27704, 61-218
606 Gazette etc. have detailed description.

When the thermoplastic resin composition of the present invention is used in applications requiring heat resistance, rigidity, scratch resistance, etc., the crystalline polypropylene is a crystalline propylene homopolymer or a crystalline propylene-α-olefin block. The isotactic pentad fraction in the boiling heptane-insoluble portion of the crystalline propylene homopolymer portion, which is the first segment polymerized in the first step of the copolymer, is 0.970 or more, and the boiling heptane-soluble portion content is 5.0% by weight. It is preferable to use a highly crystalline polypropylene having the following content and a content of the 20 ° C. xylene-soluble part of 2.0% 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 xylene soluble polymer at 20 ° C. is determined as follows.

5 g of crystalline polypropylene is boiled with xylene
After completely dissolving in 500 ml, the temperature was lowered to 20 ° C. and the mixture was allowed to stand for 4 hours and then filtered off to separate a 20 ° C. xylene-insoluble portion.
The filtrate is concentrated and dried to evaporate xylene, and further dried under reduced pressure at 60 ° C. to obtain a polymer soluble in xylene at 20 ° C. The value obtained by dividing the dry weight by the weight of the charged sample and expressed as a percentage is the content of the 20 ° C xylene-soluble portion. After the xylene-insoluble portion at 20 ° C is dried, it is subjected to Soxhlet extraction with boiling n-heptane for 8 hours. This extraction residue is referred to as a boiling heptane-insoluble part, and the value obtained by subtracting the dry weight of the boiling heptane-insoluble part from the charged sample weight (5 g) divided by the charged sample weight is expressed as a percentage. The content of parts.

The isotactic pentad fraction is
A. Zambelli et al., Macromolecules, 6 , 925 (197
3), that is, an isotactic chain of pentad units in a crystalline polypropylene molecular chain measured by using ¹³ C-NMR, in other words, five consecutive propylene monomer units are meso-continuous. It is the fraction of propylene monomer units at the center of the linked chains. However,
Regarding the attribution of the NMR absorption peak, Ma published later.
cromolecules, 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. When the isotactic pentad fraction of NPL standard substance CRM No. M19 -14 Polypropylene PP / MWD / 2 of NATIONAL PHYSICAL LABORATORY in the United Kingdom was measured by this method, it was 0.94.
It was 4.

The highly crystalline polypropylene is disclosed in
60-28405, 60-228504, 61-218606, 61-2
It can be manufactured by the method exemplified in 87917.

When the thermoplastic resin composition of the present invention is used in applications requiring impact resistance, the crystalline polypropylene is the first segment polymerized in the first step, ie, the crystalline propylene homopolymer portion or crystalline. It is preferable to use a crystalline propylene-α-olefin block copolymer comprising a propylene-α-olefin random copolymer part and a propylene-α-olefin random copolymer part which is the second segment polymerized in the second step.

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.

The high impact-resistant polypropylene obtained by the gas phase polymerization method can be produced, for example, by the method exemplified in JP-A-61-287917. 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.

The second segment has a propylene-α-olefin random copolymer portion containing 10 mol% or more of ethylene and / or at least one other α-olefin. Propylene and ethylene having an ethylene content of 10 mol% or more and / or α having 4 to 6 carbon atoms
Those having a propylene-α-olefin random copolymer portion with an olefin are preferable, and those having a propylene-ethylene random copolymer portion having an ethylene content of 10 mol% or more are particularly preferable. A combination having a crystalline homopolymer portion as the first segment and a propylene-ethylene random copolymer portion having an ethylene content of 10 mol% or more as the second segment is particularly preferable. 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 amount of the second segment is 10
-30% by weight, and preferably 10 to 70% by weight in the gas phase polymerization method. In the gas phase polymerization method, a propylene block copolymer having a large amount of the second segment is disclosed in Japanese Patent Application No. 62-2.
It can be manufactured by the method exemplified in No. 56015, 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 property of the polymer or the intrinsic viscosity of the first segment. It is 15 (dl / g) and is 1 to 5 (dl / g) in the gas phase polymerization method.

Weight ratio X of propylene-ethylene random copolymer portion to total block copolymer
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 all block copolymers (ca
l / g) (ΔHf) _P : heat of fusion of the crystalline propylene homopolymer part (cal / g) The ethylene content of the propylene-ethylene random copolymer part is determined by infrared absorption spectroscopy, and the ethylene content of the whole block copolymer is represented by% by weight. Can be calculated by the following formula. (C ^′ ₂ ) _EP = (C ^′ ₂ ) _T / X (C ^′ ₂ ) _T : ethylene content of the entire block copolymer (wt%) (C ′ ₂ ) _EP : ethylene content of the propylene-ethylene random copolymer part ( wt%)

Intrinsic viscosity [η] of a propylene-ethylene random copolymer portion in a tetralin solution at 135 ° C.
_{The EP} can be calculated from the following equation by measuring the intrinsic viscosity of each of the crystalline homopolymer part and the whole block copolymer. [Η] _EP = [η] _T / X- (1 / X-1) [η] _P [η] _P : intrinsic viscosity (dl / g) of crystalline propylene homopolymer part [η] _T : whole block Intrinsic viscosity of copolymer (dl /
g) The ethylene content (C ^' ₂ ) _EP (wt%) of the propylene-ethylene random copolymer portion is preferably 20 to 70 wt%,
More preferably, it is 25-60 wt%. Less than 20wt% or 7
If it exceeds 0 wt%, favorable results cannot be obtained with respect to the low temperature impact strength of the thermoplastic resin composition. In addition, the intrinsic viscosity of the propylene-ethylene random copolymer part [η] _EP
(Dl / g) is preferably 4 (dl / g) or more, more preferably 5 (dl / g) or more. If it is less than 4 (dl / g), favorable results cannot be obtained with regard to Rockwell hardness.

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 represented by 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, and is 10,000 to 100,000. 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 of the ethylene-butene-1 copolymer rubber is not particularly limited, and any copolymer rubber having various molecular weight distributions such as monomodal type and bimodal type which are usually produced and marketed. Can also be used. The preferable range of the Q value (weight average molecular weight / number average molecular weight) of the molecular weight distribution is 1 to 30, and more preferably 2 to 20.
Is.

Although ethylene-butene-1-non-conjugated diene copolymer rubber can be used, it is preferable that the content of non-conjugated diene in the raw rubber is 3% by weight or less. When the content of the non-conjugated diene exceeds 3% by weight, gelation occurs during kneading, which is not preferable.

The butene-1 content in the ethylene-butene-1 copolymer is 20 to 30% by weight, preferably 23 to 28% by weight, more preferably 24 to 27% by weight. If it is less than 20% by weight, favorable results cannot be obtained with respect to the linear expansion coefficient, and if it exceeds 30% by weight, favorable results cannot be obtained with respect to Rockwell hardness.

70 of ethylene-butene-1 copolymer rubber
The intrinsic viscosity in a xylene solution is 1.1 to 2.0 (dl / g), and the Mooney viscosity ML _{1 + 4} 100 at 100 ℃ is 10 to 40, preferably 1.2 to 1.8 (dl / g) and 13 to 35, respectively. , And more preferably 1.3 to 1.7 (dl / g) and 14 to 30, respectively. 70
If the intrinsic viscosity in a xylene solution is less than 1.1 (dl / g) and the Mooney viscosity ML _{1 + 4} 100 is less than 10 at 100 ° C, the Rockwell hardness is not favorable, and 2.0 (dl / dl) If it exceeds g) and exceeds 40, the dispersion with crystalline polypropylene is poor and favorable results cannot be obtained with respect to low temperature impact strength.

The average particle size of talc (C) used in the present invention is 4 μm or less, preferably 3 μm or less. 4μ
The larger ones have a large decrease in impact strength, and the appearance such as gloss becomes worse. 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. ,
The higher fatty acid ester, the higher fatty acid amide, the higher fatty acid salt or the one whose surface is treated with other surfactant can be used.

Here, the average particle diameter of talc is 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.
It means a 50% equivalent particle diameter D ₅₀ .

To use the thermoplastic resin composition of the present invention (hereinafter sometimes simply referred to as a composition) as, for example, a bumper, the concrete physical properties are as follows: the rigidity is 23 ° C. and the flexural modulus is 10,000 ( kg / cm ² ) or more, the impact strength at low temperature is Izod impact strength (notched) at -30 ° C is 5
(Kg · cm / cm 2) or more, and also in a high-speed surface impact test at −30 ° C., 3 m / sec, the absorbed energy is large and ductile fracture occurs. Rockwell hardness is desirably 55 at 23 ° C.
Above, the coefficient of linear expansion is 7 × 10 in the practical temperature range of -30 to 80 ° C.
^-5 (cm / cm · ℃) or less is required.

Therefore, the compounding ratio of each component of the composition is 50 to 75% by weight of the crystalline polypropylene (A), preferably
55-70 wt%, more preferably 60-65 wt%, ethylene-butene-1 copolymer rubber (B) 15-35 wt%, preferably 18-32 wt%, more preferably 20-28 wt% The talc (C) is 5 to 25% by weight, preferably 8 to 20% by weight, more preferably 10 to 18% by weight. To further reduce the linear expansion coefficient, the total amount of (B) and (C) is
It is 30% by weight or more, preferably 32% by weight or more, more preferably 35% by weight or more.

When the crystalline polypropylene (A) is less than 50% by weight, the rigidity and Rockwell hardness are low, and when it exceeds 75% by weight, the low temperature impact strength is 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 35% by weight, rigidity and Rockwell hardness are low. Talc (C) has a low rigidity when it is less than 5% by weight, and has a low temperature impact strength when it exceeds 20% by weight. If the total amount of (B) and (C) is less than 30% by weight, the coefficient of linear expansion is large and there is a practical problem. As described above, the composition intended by the present invention can be obtained only after the structures of the respective components used are limited to the specific ranges as described above and the mixing ratios of the respective components are specified.

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, after kneading the crystalline polypropylene and talc, a method of adding ethylene-butene-1 copolymer rubber, or kneading the talc to the crystalline polypropylene in a high concentration in advance as a masterbatch, which Separately, there is a method of kneading while diluting with crystalline polypropylene, ethylene-butene-1 copolymer rubber or the like, and molding can be performed by the same method. The temperature required for kneading is 160-260 ℃,
The time is 1 to 20 minutes.

Further, in these kneading machines, in addition to these basic components, an antioxidant, an ultraviolet absorber, a lubricant,
Additives such as pigments, antistatic agents, copper anti-corrosion agents, flame retardants, neutralizing agents, foaming agents, plasticizers, nucleating agents, anti-foaming agents and cross-linking agents can be added.

Among these additives, it is preferable to add an antioxidant or an ultraviolet absorber as a composition in order to improve weather resistance, heat resistance and oxidation resistance in the outdoors. As the antioxidant, 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-4-ethylphenol,
2,6-di-tert-butyl-α-dimethylamino-vala-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, diteurilthiodipropionate, and the like, and 2-hydroxy-4 as an ultraviolet absorber.
-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. Be done.

The composition of the present invention is excellent in rigidity, Rockwell hardness and low temperature impact strength, and molded articles 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.
Since the molded product molded by the injection molding method has a small linear expansion coefficient, the composition is suitable for use as a material for automobile bumpers, especially for large bumpers where dimensional stability is strictly required.

[0051]

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. Measurement temperature is 230 ° C
Unless otherwise specified, the load is measured at 2.16 kg. (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 3.2 mm and the tensile yield strength 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, and the bending elastic modulus and bending strength are evaluated under the conditions of a span length of 100 mm and a load speed of 2.0 mm / min. The measurement temperature is 23 ° C unless otherwise specified. For other temperatures, measure the condition after adjusting the condition for 30 minutes in a constant temperature bath. (4) Izod impact strength Measured according to JIS K7110. A test piece molded by injection molding is used. The thickness of the test piece is 6.4 mm, and the impact strength with a 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) Surface Impact Strength High Rate Impact Tes made by Rheometrics (USA)
100 x 400 x injection molded using ter (RIT-8000 type)
A 100 × 100 × 3 (mm) flat plate tester piece cut out from a 3 (mm) flat plate was fixed with a 2-inch circular holder, and the diameter was 5
1/8 inch (5/16 inch radius of the tip spherical surface) is used, the impact probe is applied to the test piece at a speed of 3 m / sec, and the deformation amount and stress of the test piece are detected.
The surface impact strength is evaluated by drawing a curve as shown in and calculating the area integral value. The energy value required for yielding a material is evaluated as the yield point energy, and the energy value required for breaking is evaluated as the total energy, and all units are expressed in joules (J). Condition adjustment is performed using the thermostatic chamber attached to the equipment. The test piece is put in a constant temperature bath previously adjusted to a predetermined temperature, and the condition is adjusted for 2 hours, and then the above test is performed. This predetermined temperature is taken as the measurement temperature. FIG. 1 shows an example of surface impact strength. The horizontal axis is the amount of deformation of the test piece, and the vertical axis is the stress for a certain amount of deformation. The measurement chart is obtained by continuously detecting both values and plotting them continuously on an XY plotter. Obtain the yield point energy by performing the area integration of the displacement and stress from the rising part of the detected stress to the point where the material yields,
The total energy is calculated by performing the area integration of the amount of displacement and the stress from the rising portion to the material fracture. The fracture state of the material is ductile fracture (D) by observing the fracture test piece of the actual material.
Or brittle fracture (B).

(6) Rockwell hardness According to the method specified in JIS K7207. A test piece molded by injection molding is used. The thickness of the test piece is 3.0 mm, the steel ball is R, and the evaluation value is shown on the R scale. (7) As a linear expansion coefficient measuring device, a thermomechanical analyzer TMA-40 manufactured by Shimadzu Corporation was used for measurement as follows. Unless otherwise noted, injection molded 100 x 400 x 3 (mm)
The flat plate test piece of is used. After annealing the flat plate for 30 minutes at 120 ° C, a 12.7 × 12.7 × 3 (mm) test piece is cut out from the center and the dimensions at 23 ° C are measured accurately. Set in the device so that the dimensional change in 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, and the dimensional change in the MD or TD direction is measured during that period. twenty three
The dimensional change per unit length and unit temperature is obtained as a coefficient of linear expansion by calculation based on the dimension at ° C.

(8) Mooney viscosity Measured by the method specified in JIS K6300. The measuring temperature is 100 ° C. (9) Ethylene content for ethylene content appearing in the infrared absorption spectrum was fabricated to measure the butene-1 content press sheet methyl group (-CH ₃₎ and methylene group - using the absorbance of characteristic absorption of (-CH ₂₎ Then, the butene-1 content was determined by the calibration curve method using the absorbance of the characteristic absorption of the ethyl group.

(10) Intrinsic viscosity Using an Ubbelohde viscometer, concentrations of 0.1, 0.2 and 0.5 g
The reduced viscosity was measured at three points of / dl. Intrinsic viscosity is
The calculation method described in “Polymer Solution, Polymer Experiments 11” (1982, Kyoritsu Shuppan Co., Ltd.), page 491, that is, the extrapolated method of plotting the reduced viscosity against the concentration and extrapolating the concentration to zero I asked. The crystalline polypropylene was evaluated at a temperature of 135 ° C. using tetralin as a solvent. The ethylene-butene-1 copolymer rubber was evaluated at a temperature of 70 ° C. using xylene as a solvent. (11) 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. The suspension was put into a cell, the height of the liquid surface was 3 cm, and the particle size distribution curve was measured at a rotation speed of 500 rpm. An integral cloth curve was created by a screen-down method plot, and an average particle diameter D ₅₀ corresponding to 50% by weight was determined. (12) Drop weight impact strength Measured according to JIS K7211. The test piece is a cutout piece of a bumper obtained by injection molding described below,
It is a 10 cm square type test piece. The test piece was conditioned at −30 ° C. for 2 hours and then measured.

(13) Pendulum test According to the method specified in FMVSS 581. An impact test was performed on a bumper molded body obtained by injection molding described later.
The measurement temperature was −30 ° C. and the effective impact mass was 1000 kg. (14) Initial adhesion of coating The cut-out piece of the bumper obtained by injection molding shown below was used as a test piece, and this test piece was surface-cleaned in 1,1,1-trichloroethane vapor (74 ° C) for 30 seconds. After drying at room temperature,
As a primer, paint BB291H manufactured by Nippon Bee Chemical Co., Ltd. and bake it in an oven at 100 ° C for 20 minutes, then
Urethane paint (made by Nippon Bee Chemical Co., Flexen #
Spray paint 101) and bake for 40 minutes in an oven at 120 ° C. Engrave 100 squares (10 vertical x 10 horizontal) of 2 mm square on the coating film of this coating test with a razor blade,
A cellophane tape having a width of 24 mm (manufactured by Nichiban Co., Ltd.) was crimped on it with a finger, and then the end face was grasped and peeled off at a stretch, and the number of gobangs left was evaluated as a residual rate (%).

(15) Dimensional stability A bumper obtained by injection molding as described below was subjected to 1
After annealing for a period of time, it was mounted on a car body and a heat cycle test was conducted under the following conditions. The degree of displacement between the bumper and the car 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, and then at -30 ° C for 7.5 hours. This is set as one cycle, and this is repeated for four cycles.

The above (2), (3), (4) and (6)
The test piece for physical property evaluation was prepared under the following injection molding conditions unless otherwise specified. The composition is heated to 120 ° C in a hot air dryer.
After drying for 2 hours, using IS150E-V type injection molding machine manufactured by Toshiba Machine, molding temperature 200 ℃, mold cooling temperature 50 ℃, injection time 15sec.
Injection molding was performed with a cooling time of 30 seconds. The above-mentioned test pieces for evaluating physical properties (5) and (7) were produced 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 using a Neomat 515/150 type injection molding machine manufactured by Sumitomo Heavy Industries Ltd., molding temperature 200 ° C, mold cooling temperature 50 ° C, injection time 15sec, cooling time 30sec. Injection molding was performed. The molded articles for physical property evaluation of (12) to (15) were produced under the following injection molding conditions. The composition was dried in a hot air drier at 120 ° C for 2 hours, and then using a UBE MAX2500 injection molding machine manufactured by Ube Industries, the molding temperature was 200 ° C and the mold cooling temperature was 50 ° C.
Injection molding was carried out with an injection time of 30 seconds and a cooling time of 60 seconds to mold a bumper for automobile (weight 4500 g).

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, and then the continuous twin-screw kneader (TEX 44 SS 30BW-2V type manufactured by Japan Steel Works, Ltd.) extruded at 30 kg / hour and resin temperature. 220 ℃, screw rotation speed
It was carried out under vent suction at 350 rpm. 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) Crystalline polypropylene (A) was produced by the slurry polymerization method described in JP-A-60-28405, and PP-1, PP-2,
It was set to PP-3. PP-1; melt flow rate 26 (g / 10 minutes), 135 ° C
Intrinsic viscosity in a tetralin solvent is 1.93 (dl / g), the proportion of the homopolymer portion of propylene which is the first segment polymerized in the first step (hereinafter abbreviated as P portion) is 84% by weight,
The proportion of the ethylene-propylene copolymer (hereinafter abbreviated as EP part) which is the second segment polymerized in the second step is
16% by weight, the P part has a molecular structure of 135 ° C and an intrinsic viscosity of 1.12 (dl / g) in tetralin solvent, the content of the cold xylene soluble part at 20 ° C is 1.7% by weight, and the boiling heptane soluble part is The content was 4.9% by weight, the isotactic pentad fraction in the boiling heptane-insoluble part was 0.985, and the molecular structure of the EP part was 13%.
A highly crystalline propylene-ethylene block copolymer having an intrinsic viscosity of 5.9 (dl / g) in a tetralin solvent at 5 ° C and an ethylene / propylene ratio in the EP part of 25/75% by weight.

PP-2: Melt flow rate is 26 (g / 10
Min), and the intrinsic viscosity in 135 ° C tetralin solvent is 1.93 (dl /
g), the proportion of the P part which is the first segment polymerized in the first step is 84% by weight, and the proportion of the EP part which is the second segment polymerized in the second step is 16% by weight. It has a molecular structure of 135 ° C and an intrinsic viscosity of 1.12 (dl /
g), the content of the cold xylene-soluble part at 20 ° C is 2.4% by weight,
The content of soluble parts in boiling heptane is 6.5% by weight, and the isotactic pentad fraction in insoluble parts in boiling heptane is 0.972.
And a highly crystalline propylene-ethylene block copolymer in which the molecular structure of the EP part is 135 ° C, the intrinsic viscosity in a tetralin solvent is 5.9 (dl / g), and the ethylene / propylene ratio in the EP part is 25/75% by weight. ..

PP-3: Melt flow rate is 26 (g / 10
Min), and the intrinsic viscosity in 135 ° C tetralin solvent is 1.93 (dl /
g), the proportion of the P part which is the first segment polymerized in the first step is 84% by weight, and the proportion of the EP part which is the second segment polymerized in the second step is 16% by weight. The molecular structure is 135 ° C, and the intrinsic viscosity in tetralin solvent is 1.12 (dl / g),
The content of cold xylene-soluble part at 20 ℃ is 3.5% by weight, the content of boiling heptane-soluble part is 9.0% by weight, the isotactic pentad fraction of boiling heptane-insoluble part is 0.950, and the molecule of EP part is A crystalline propylene-ethylene block copolymer having a structure of 5.9 (dl / g) in a tetralin solvent at 135 ° C and an ethylene / propylene ratio of 25/75% by weight in the EP part.

Reference Example 2: Production of ethylene-butene-1 copolymer rubber (B) An ethylene-butene-1 copolymer rubber was prepared by a homogeneous solution method with reference to the method described in JP-B-44-9390. Polymerized, E
It was set to BR-1 to EBR-9. EBR-1; ethylene-butene-1 copolymer having a butene-1 content of 25% by weight, an intrinsic viscosity in a xylene solution at 70 ° C. of 1.0 (dl / g), and a Mooney viscosity ML _{1 + 4} 100 of 100 at 3 Combined rubber. EBR- having various different molecular structures in the same manner
Eight types of ethylene-butene-1 copolymer rubbers from 2 to EBR-9 were polymerized. The contents of nine kinds of ethylene-butene-1 copolymer rubbers including EBR-1 are summarized in Table 1.

Reference Example 3: Production of ethylene-propylene copolymer rubber Polymerization was carried out in the same manner as in Reference Example 2 to obtain EPR-1. EPR-1; ethylene-propylene copolymer rubber having a propylene content of 25% by weight, an intrinsic viscosity in a xylene solution at 70 ° C of 1.5 (dl / g), and a Mooney viscosity ML _{1 + 4} 100 of 23 at 100 ° C.

Reference Example 4: Talc (C) Raw talc stone was mechanically pulverized and classified by a dry method to obtain talc having the following average particle size. Talc -1; D ₅₀ = 2.1 μm talc -2; D ₅₀ = 5.0 μm

Examples 1 to 3 and Comparative Examples 1 to 7 PP-2 as the crystalline polypropylene (A) and various ethylene-butene-1 copolymer rubbers (B) EBR-1 as shown in Table 1 as the rubber. EBR-9 and ethylene-propylene copolymer rubber EPR-1, talc-1 was used as talc (C), and the blending ratio of each component was kept constant at the following ratios (weight ratio). PP-2: Rubber: Talc-1 = 63: 22: 15 Ethylene-butene-1 copolymer rubber (B) is EBR-1.
Up to EBR-9, butene-1 content and modified structure of intrinsic viscosity in 70 ° C. xylene solution were used. EP for comparison with ethylene-propylene copolymer rubber
I used R-1. These compositions were kneaded under predetermined conditions to prepare a composition, and test pieces were molded under predetermined injection molding conditions. The physical property evaluation results are shown in Table 2. The examples of the present invention are superior to the comparative examples in the balance of low temperature impact strength, Rockwell hardness and linear expansion coefficient.

Comparative Example 8 A composition was prepared in the same manner as in Example 2 except that talc-2 was used instead of talc-1, and the physical properties were evaluated. Table 3 shows the results of physical property evaluation. The low-temperature impact strength, particularly the surface impact strength, is significantly inferior to that of Example 2 in which the average particle size of talc is small.

Examples 4 to 5 Compositions were prepared in the same manner as in Example 2 except that PP-1 or PP-3 was used in place of PP-2, and the physical properties were evaluated. The example using PP-1 is Example 4, and the example using PP-3 is Example 5. Table 4 shows the results of physical property evaluation. All of Examples 2, 4 and 5 show good physical properties. Rockwell hardness increases as the number of cold xylene-soluble parts in the P part of the crystalline polypropylene (A) decreases.

Examples 6 to 7 and Comparative Examples 9 to 12 PP-1 or P as the crystalline polypropylene (A)
P-2, ethylene-butene-1 copolymer rubber (B), EBR-3, and talc (C), talc-1 were used in the proportions shown in Table 5. These compositions were kneaded under predetermined conditions to prepare a composition, and test pieces were molded under predetermined injection molding conditions. Table 5 shows the results of physical property evaluation. Comparative Example 9 has a difficulty in rigidity and Rockwell hardness, Comparative Examples 10 to 11 have a linear expansion coefficient, and Comparative Example 12 has a low temperature impact strength.

Comparative Example 13 A test piece for measuring the linear expansion coefficient of the composition of Example 2 was prepared by the press molding method under the following conditions. Using a compression molding machine (model F-37) manufactured by Kondo Metal Industry Co., Ltd., temperature 22
Press molding was carried out at 0 ° C., 5 minutes of preheating and 5 minutes of pressurization, and solidified by a cooling press at a temperature of 30 ° C. to obtain a test piece of 50 × 200 × 3 (mm). After annealing this test piece for 30 minutes at 120 ° C., a test piece of 12.7 × 12.7 × 3 (mm) was cut out from the central portion and the linear expansion coefficient was measured in the same manner as in Example 2. The linear expansion coefficient of Example 2 obtained by injection molding was 6.5 × 10 ⁵ (cm / cm · ° C.), and the linear expansion coefficient of Comparative Example 13 obtained by press molding was 10.9 × 10 ⁵ (cm / c).
m · ° C). The linear expansion coefficient becomes low only when the composition is molded by the injection molding method.

Example 8 and Comparative Examples 14 to 19 Automotive bumpers were molded from the compositions of Example 2 and Comparative Examples 1, 2, 4, 6, 7, and 10 by injection molding. The bumper falling weight impact strength, pendulum test, initial coating adhesion and dimensional stability were evaluated. Further, the scratch resistance was evaluated qualitatively by visually observing the degree of damage to the molded body during handling during the coating work. Table 6 shows these evaluation results.
Shown in. In practical evaluation using a bumper, Example 8
While good results were obtained in all items,
In Comparative Examples 14 to 19, some points were defective.

[0073]

EFFECTS OF THE INVENTION The thermoplastic resin composition according to the present invention is not only excellent in low-temperature impact strength and rigidity, but also has good dimensional stability essential for large-sized molded articles, and has a problem in handling molded articles. It has a great effect in that the scratch resistance is good. The novel thermoplastic resin composition provided by the present invention can be easily processed into a molded product, a film, a sheet, etc. by a usual processing method such as injection molding, extrusion molding, press molding method and the like. Of these, the injection molding method is the most preferable molding method in the sense that it imparts good dimensional stability to the thermoplastic resin composition. In particular, it is suitable for use in large bumpers, which have recently become large in size, and the requirements for mounting accuracy on the vehicle body and dimensional stability have become strict.

[0074]

[Table 1]

[0075]

[Table 2]

[0076]

[Table 3]

[0077]

[Table 4]

[0078]

[Table 5]

[0079]

[Table 6]

[Brief description of drawings]

FIG. 1 is an explanatory diagram of surface impact strength measurement.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI technical display location C08L 23:08) B29K 23:00 B29L 31:30 4F (72) Inventor Masashi Yamamoto Ichihara City, Chiba Prefecture 5-1 Anesaki Kaigan Sumitomo Chemical Co., Ltd. (72) Inventor Katsunari Inagaki Ichihara, Chiba 1-5 Anesaki Kaigan Sumitomo Chemical Co., Ltd. (72) Inventor Takao Nomura 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd. (72) Inventor Takesumi Nishio 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor Shinya Kawamura 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd.

Claims (3)

[Claims] 1. Crystalline polypropylene (A): 50 to 75
% By weight, ethylene-butene-1 copolymer rubber (B): 15-35
% By weight, talc (C): 5 to 20% by weight, the butene-1 content of the ethylene-butene-1 copolymer rubber (B) is 20 to 30% by weight, and the intrinsic viscosity in a 70 ° C. xylene solution is 1.1 to 2.0 (dl / g), the Mooney viscosity ML _{1 + 4} 100 at 100 ° C. is 10 to 40, the average particle diameter of talc (C) is 4 μm or less, and (B) and (C The total amount of the above) is 30% by weight or more, and a thermoplastic resin composition. 2. An injection-molded article obtained by molding the thermoplastic resin composition according to claim 1 by an injection molding method. 3. The injection molded body according to claim 2, wherein the injection molded body is a bumper.