JP3119691B2 - Resin composition for bumper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for bumpers, and more particularly, to a resin composition having a surface hardness of 55 or more (Rockwell®
-Scale), melt flow index is 15g / 10min or more, low temperature embrittlement temperature is -30 ℃ or less, light weight and moldability,
The present invention relates to a bumper resin composition having good coatability and appearance.

[0002]

2. Description of the Related Art Polypropylene resins are often used as materials for automobile bumpers from the viewpoints of weight reduction, rust prevention and design freedom. However, the conventional resin composition for bumpers was not sufficient in impact resistance and paintability.
Therefore, JP-A-57-55952 and JP-A-58-111846,
No. 59-98157, No. 58-17139, No. 57-177038, No. 57-207630, No. 57-195134, No. 57-
As disclosed in 159841 and 55-21494, in order to impart impact resistance and coatability to a polypropylene resin, an ethylene-propylene copolymer is blended to impart rigidity and dimensional stability. Attempts have been made to fill the resin composition with an inorganic filler such as talc, but such a resin composition has a low surface hardness and an insufficient appearance.

[0003]

In recent years, automobile bumpers have become larger, and conventional materials are heavy and have low fluidity, which makes injection molding difficult.
When the center of the cross section of the bumper molded with such a resin composition is observed with a transmission electron microscope (hereinafter abbreviated as TEM), as shown in FIG. 3 and FIG. And the interface of the rubber component of the resin is observed as a clear line.

[0004]

Means for Solving the Problems Accordingly, the present inventors have:
Lightweight with good moldability, high hardness, high-temperature impact resistance,
In addition, as a result of intensive studies aimed at obtaining a resin composition having good appearance and coatability, specific high crystalline ethylene-propylene block copolymers, amorphous ethylene-propylene copolymers, ethylene-α-olefin copolymers were obtained. The present invention has been completed by blending a polymer, an amorphous ethylene-butene copolymer and talc in a specific ratio.

That is, the present invention relates to (A) an ethylene content
0.5 to 10% by weight, boiling point n-heptane insoluble content of polypropylene component is 97% by weight or more, and p-xylene soluble content of 5 to 5 at room temperature
Including 20 wt%, intrinsic viscosity (decalin, 135 ° C) 2 or more, melt flow index 30-100 and flexural modulus
18,000 kg / cm ² or more of highly crystalline ethylene-propylene block copolymer 45-80% by weight, (B) ethylene content 70-
90% by weight and 10-20% by weight of an amorphous ethylene-propylene copolymer having a Mooney viscosity of ML _{1 + 4} (100 ° C.) 5 to 70, (C)
Melt flow index (230 ° C) with α-olefin content of 4 to 10 carbon atoms, content of 5 to 15 mol% and density of 0.91 or less
Amorphous ethylene having an ethylene-α-olefin copolymer of 2.2 to 50 g / 10 min, 5 to 15% by weight, (D) butene content of 10 to 25% by weight, Mooney viscosity ML _{1 + 4} (100 ° C.) 5 to 20 -1 to 10% by weight of butene copolymer and (E) average particle diameter D50
A resin composition for a bumper comprising less than 8% by weight of talc having a particle size of 1.0 to 3.0 [mu] m and not containing a particle size of 10 [mu] m or more, wherein the component (B) is present as a rubber component reinforced by a polyethylene lamella. About.

When the center of the cross section of the bumper molded with the resin composition for a bumper of the present invention is observed by TEM, FIG.
As shown in FIGS. 2 and 3, a morphology distinct from the conventional FIGS. 3 and 4 is observed. That is, (1) the rubber component has a flat shape and is distributed not only as islands but also in many continuously connected portions. (2) The interface between the resin and the rubber component is extremely vague. Furthermore, the decisive difference from the conventional one is that (3) polyethylene lamella was observed in the rubber component mainly composed of amorphous ethylene-propylene copolymer, and a rubber reinforced with polyethylene was clearly observed. Can be

Hereinafter, each component of the resin composition for a bumper according to the present invention will be specifically described. Component (A) Component (A) used in the present invention is important for ensuring the fluidity and rigidity of the composition, and its ethylene content is
0.5 to 10% by weight, preferably 1.5 to 7% by weight,
The boiling n-heptane insoluble content of the polypropylene component is 97% by weight or more, preferably 97.5% by weight or more, and the room temperature para-xylene solubles (comprising an amorphous ethylene-propylene copolymer and a low molecular weight polymer) 5 to 20% by weight %, Preferably 6 to
15 wt%, having an intrinsic viscosity (decalin, 135 ° C.) of 2 or more, preferably 3 to 12, and a melt flow index of 30 to 100 g / 10 min, preferably 40 to 80 g / 10 min.
Flexural modulus of 18,000 kg / cm ² or more, preferably 19,000 to ²
It is 5,000 kg / cm ² . Flexural modulus of 18,000kg / c
If it is less than m ² , the rigidity and surface hardness of the molded product will be low. In this specification, the boiling n of the polypropylene component
The term “heptane-insoluble matter” refers to a boiling n-heptane-insoluble matter of a crystalline polypropylene (sometimes referred to as a matrix) used in a block copolymer reaction. When the boiling n-heptane-insoluble content of the polypropylene component is less than 97% by weight, the surface hardness decreases, and when the intrinsic viscosity (decalin, 135 ° C.) of the normal-temperature para-xylene soluble content is less than 2, Means that the Izod impact strength at a temperature of −30 ° C. decreases. If the ethylene content is less than 0.5% by weight, the impact resistance decreases, and if it exceeds 10% by weight, the rigidity decreases. If the amount of the soluble component in normal-temperature para-xylene is less than 5% by weight, the impact resistance is reduced, and if it exceeds 20% by weight, the rigidity is reduced. If the melt flow index is less than 30, the appearance of the molded product and the moldability of the resin composition will be poor, and if it exceeds 100, the impact resistance will be reduced. In any case, outside the range specified above, the resin composition cannot be used as a material for a molded article requiring excellent appearance at the same time as rigidity, surface hardness, low-temperature impact resistance, and paintability. is there.

The highly crystalline ethylene-propylene block copolymer is contained in the composition of the present invention in an amount of 45 to 80% by weight, preferably 50 to 75% by weight. If the content is less than 45% by weight, the moldability will be poor, and if it exceeds 80% by weight, the paintability will be poor. If the total amount of the highly crystalline ethylene-propylene block copolymer is within the above range, two or more kinds may be used. Further, as long as it does not deviate from the object of the present invention, a crystalline ethylene-propylene block copolymer which is graft-modified with an unsaturated organic acid or a derivative thereof may be used.

Component (B) Amorphous ethylene used as component (B) in the present invention
The propylene copolymer is important for ensuring the embrittlement temperature, has an ethylene content of 70 to 90% by weight, and has a Mooney viscosity ML _{1 + 4} (100 ° C.) of 5 to 70, preferably 10 to 60.
belongs to. If the ethylene content is less than 70% by weight, the surface hardness decreases, and if it exceeds 90% by weight, the impact resistance becomes insufficient. If the Mooney viscosity is less than 5, the molecular weight is too small and the impact resistance is insufficient, and if it exceeds 70, the molecular weight is too large and it is difficult to sufficiently disperse it in the highly crystalline ethylene-propylene block copolymer. And the impact resistance is reduced, and the fluidity is also reduced. The component (B) is contained in the composition according to the present invention in an amount of 10 to 20% by weight, preferably 12 to 20% by weight. If it is less than 10% by weight, impact resistance and paintability will be insufficient, and if it exceeds 20% by weight, rigidity will be insufficient.

Component (C) The ethylene-α-olefin copolymer used as component (C) in the present invention is important for reinforcing component (B) and improving flowability. The α-olefin has 4 to 10 carbon atoms, and among them, those having 4 or 6 or 8 carbon atoms are preferable. α-olefin content is 5 to 15
If it is less than 5 mol%, the component (B) is too reinforced and the impact resistance is reduced. If it exceeds 15 mol%, the component (B) cannot be reinforced, Surface hardness and flexural modulus decrease. The density of component (C) is 0.91 or less.
If it exceeds 0.91, impact resistance is insufficient. The melt flow index (230 ° C.) of component (C) is 2.2 to 50 g / 10 min, preferably 6 to 40 g / 10 min. When it is less than 2.2 g / 10 minutes, the fluidity is low, and when it exceeds 50 g / 10 minutes, the impact resistance is reduced. Component (C) is contained in the composition of the present invention in an amount of 5 to 15% by weight, preferably 8 to 15% by weight. If the content exceeds the above range, the balance between rigidity and impact resistance will be poor. Component (C) is sometimes referred to as "ultra low density polyethylene".

Component (D) Amorphous ethylene used as component (D) in the present invention
The butene copolymer is important as a compatibilizer for the component (B) and the component (C), and has a butene content of 10 to 25% by weight and a Mooney viscosity of ML _{1 + 4} (100 ° C) 5 to 20. Things. If the butene content is less than 10% by weight, the crystallinity of the ethylene chain is increased, and the impact resistance is reduced. If the butene content exceeds 25% by weight, the molded product becomes soft, and the surface hardness of the molded product becomes insufficient. As described above, the Mooney viscosity is 5 to 20, and if the Mooney viscosity is less than 5, the molecular weight is too small and the impact resistance is insufficient,
If it exceeds 20, the molecular weight becomes too large and the moldability decreases. The content of the component (D) is 1 to 3 in the composition according to the present invention.
It is 10% by weight, preferably 1 to 7% by weight. If the content is out of the above range, the compatibility between the component (B) and the component (C) becomes poor, and the balance between rigidity and impact resistance becomes poor.

[0012] The average particle diameter D ₅₀ of the talc used as component (E) in component (E) The present invention is, 1.0 m 3.0 [mu] m, preferably 1.0μ
It is important that the particle diameter is from m to 2.5 μm and the particle diameter is not more than 10 μm. The particle size distribution of talc is measured using a natural centrifugal sedimentation type automatic particle size distribution analyzer CAPA-300 manufactured by Horiba, Ltd.
Was performed. The average particle diameter D _{50 of the} talc is 1.0 μm
If less than, it is difficult to disperse the composition of the present invention,
Insufficient impact resistance of molded products. If it exceeds 3.0 μm, the balance between rigidity and impact resistance will be poor. Said talc is present in the composition according to the invention in less than 8% by weight, preferably 7%.
% By weight or less. When the content of talc is 8% by weight or more, the appearance deteriorates, the weight of the molded product increases,
Impact resistance also decreases.

The talc used in the present invention may be surface-treated with various treating agents as long as the purpose is not adversely affected. Examples of the surface treatment agent include a silane coupling agent system,
Chemical or physical surface treatment with various treating agents such as higher fatty acids, fatty acid metal salts, unsaturated organic acids or derivatives thereof, organic titanates, resin acids, and polyethylene glycol ethers can be mentioned.

The components constituting the resin composition of the present invention are mixed using a Banbury mixer, a single screw extruder, a twin screw extruder,
Although it can be carried out using a high-speed twin-screw extruder or the like, particularly preferably, it can be easily carried out by melt-mixing using a Banbury mixer or a high-speed twin-screw extruder. Also,
As a mixing order of the components, the components (A) to (E) may be blended and then melt-mixed. The components (A) and (E) may be mixed with a high-speed twin-screw extruder or a twin-screw extruder or a Banbury mixer. May be melt-mixed first, and then the components (B) to (D) may be melt-mixed by the mixer.

In order to further enhance the performance of a molded product obtained by molding the resin composition of the present invention, an antioxidant, an ultraviolet ray absorbing agent, or the like may be used when mixing each component of the composition of the present invention or after mixing each component. Agents, pigments, coatability improvers, lubricants, and the like. As antioxidants, 2,6
-Di-tert-butylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-n-butylphenol, 2,6-
Ditertiarybutyl-α-dimethylamino-para-cresol, 6- (4-hydroxy-3,5-ditertiarybutylianilino) -2,4-bisoctyl-thio-
1,3,5-triazine, n-octadecyl-3-
(4'-hydroxy-3 ', 5'-di-tert-butylphenyl) propionate, 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, 1,3,5-trimethyl-2,
4,6-tris (3,5-di-tert-butyl-4-
(Hydroxybenzyl) benzene, dilaurylthiodipropionate and the like.

The ultraviolet absorber which can be used in the composition of the present invention includes 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-octadecyloxybenzophenone, and 4-dodecyloxy-2-ene. Hydroxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2- (2'-hydroxy-
3'-tert-butyl-5'-methylphenyl)-
5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'-ditert-butyl-phenyl)-
5-chlorobenzotriazole, bis- (2,6-dimethyl-4-piperidinyl) sebacate, 1,2,3,4
-Butanetetracarboxylic acid 1,2,2,6,6-pentamethyl-4-piperidinol tridecyl alcohol condensate.

Further, pigments which can be optionally compounded in the resin composition of the present invention include iron black, carbon black, titanium oxide and the like; paintability improving agents such as magnesium benzoate; and lubricants such as fatty acid metal salts. And fatty acid amides. By molding from the resin composition of the present invention by a conventionally known injection molding method, it is possible to obtain a bumper that is lightweight and has good appearance, moldability, and coatability.

[0018]

EXAMPLES Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but it goes without saying that the scope of the present invention is not limited to these Examples.

Examples 1 to 4 and Comparative Examples 1 to 8 In addition to the formulation of each component shown in Table 1,
2,6-di-tert-butyl-4-methylphenol
0.1 PHR, pentaerythrityl-tetrakis [3-
(3,5-Ditert-butyl-4-hydroxyphenyl) propionate] 0.3 PHR, bis (2,2,6,
6-tetramethyl-4-piperidyl) sebacate 0.3PH
R, 0.2 PHR of magnesium stearate and 1.0 PHR of carbon black are added and mixed with a tumbler.
After melt kneading at 220 ° C and granulation by a screw extruder,
A test piece for evaluation was molded by an injection molding machine and evaluated by the following test method. The results are also shown in Table 1.

[0020]

[Table 1]

(1) Melt flow index conforms to ASTM D1238 (Temperature 230 ° C, load 2,160 kg) (2) Density conforms to ASTM D1505 (3) Low temperature embrittlement temperature conforms to JIS K7216 (4) Izod impact strength conforms to ASTM D256 Compliant (test temperature −30 ° C) (5) Flexural modulus compliant with ASTM D790 (test temperature 23 ° C) (6) Surface hardness compliant with ASTM D785 (Rockwell R-Scale) (7) Appearance Resin composition under the following conditions Then, the appearance quality of the obtained flat test piece (mirror surface) was visually judged. Judgment standard ○ Almost no Torishima pattern is recognized. Δ: A half-tone pattern was observed in half of the molded product. C: A torashima pattern is observed on the entire surface of the molded product. Molding condition Molding machine UBE MAX D150-10 Specimen shape 360mm * 140mm * 3mm Injection temperature 210-210-210-200-190 ℃ Injection pressure 980 kg / cm ² Holding pressure 420 kg / cm ² Mold temperature 50 ° C Cooling time 30 seconds (8) Paintability The resin composition was injection molded to obtain a 50 mm × 90 mm × 2 mm flat test piece. This flat test piece is
The surface was cleaned by exposure to saturated vapor of 1,1-trichloroethane for 30 seconds. It was then placed in an oven set at 90 ° C. for 10 minutes to dry. Next, plasma processing was performed. The conditions for the plasma treatment were as follows.・ Vacuum degree 1.0Torr ・ Microwave output 0.05kw ・ Treatment time 0.3sec ・ Gas flow rate 600cc / min ・ Treatment gas Air After plasma treatment, apply one-component urethane top coat so that the film thickness becomes 40μm did. At 120 ° C
It was dried for 30 minutes and then left at room temperature for 48 hours to obtain a coated product. The paintability of this coated product was evaluated as follows. First, the coating film of this test piece was cut in a grid pattern with a cutter knife and divided into 100 sections.
In this section, one section is 1 mm square. A cellophane tape was stuck from above, and when the cellophane tape was peeled off, the sections where the coating was peeled off were counted. Regarding the paintability, the case where there was no section where the coating was peeled was evaluated as ○, the case where 1 to 10 frames out of 100 sections were peeled was evaluated as Δ, and the case where 11 or more frames were peeled was evaluated as ×.

The characteristics of each component used in Examples and Comparative Examples are shown below. Component (A): Name of crystalline ethylene-propylene block copolymer A-1 A-2 A-3 Ethylene content 4.5 4.3 7.0 (% by weight) Boiling n-heptane 97.8 97.5 93.8 Insoluble matter (% by weight) -Xylene 4.5 4.3 4.2 Intrinsic viscosity of soluble component Melt flow index 47 35 42 (g / 10 min) Flexural modulus (kg / cm ² ) 19,000 18,000 15,600

[0023]

Component (C): Ethylene-α-olefin copolymer name C-1 C-2 Process High-pressure method Gas-phase method Catalyst Ti-Mg-Si-Al / toluene Catalyst Acetate ethylaluminum chlorite Comonomer 1-Phenene 1-Phenene gas composition ratio 1: 1.5 − (C ₂ : C ₄ ) Hydrogen (mol% / monomer) 0.2 − Polymerization pressure (kg / cm ² ) 1500 − Polymerization temperature (° C) 200max −

(Polymerized Polymer) MI (g / 10 min) 30 2 1-Phthene concentration (mol%) 10 4 Density (g / cm ³ ) 0.89 0.92 The ethylene-α-olefin copolymer represented by C-1 is:
For example, it is a copolymer polymerized by the following method.

(Preparation of Catalyst) A toluene solution of 1.3 kg of methyltriethoxysilane was added dropwise to a toluene slurry of 1 kg of aluminum chloride at about 20 ° C., and the temperature was maintained at 30 ° C. N-Butyl magnesium chloride was added to the reaction mixture at -10 ° C.
1.6 kg of an isoamyl ether solution was added dropwise, and the mixture was kept at 25 ° C., and the precipitated carrier was separated by filtration and washed. 8.3 L of titanium tetrachloride was added to 15 L of a toluene suspension of a carrier, and the mixture was maintained at 90 ° C. The obtained solid catalyst component was separated by filtration and washed.

(Polymerization) The monomer and hydrogen shown in the table were continuously supplied to a tubular reactor having a total length of about 400 m, and the catalyst and cocatalyst were continuously injected from the injection point of the reactor at a predetermined pressure. -Copolymerized at temperature. C-2 Nippon Unicar NUCG5210

[0028]

[0029]

As is clear from the results shown in Table 1, the resin compositions of the examples according to the present invention have good quality, are lightweight, have high fluidity and surface hardness, and have high rigidity. It has a good balance of impact resistance, good mechanical properties, and good appearance and coatability, and is most suitable as a resin composition for large bumpers. On the other hand, the compositions of Comparative Examples 1 to 8 have problems in either mechanical properties or paintability.

[Brief description of the drawings]

FIG. 1 is an electron micrograph (× 5000) showing the structure of the structure of a resin of Example 1 according to the present invention.

FIG. 2 is an electron micrograph (× 100,000) showing the structure of the structure of the resin of Example 1 according to the present invention.

FIG. 3 is an electron micrograph (× 5000) showing the structure of the resin structure of Comparative Example 1.

FIG. 4 is an electron micrograph (× 100,000) showing the structure of the resin structure of Comparative Example 1.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI C08L 23:16) (72) Inventor Yoshifumi Nakano 3-1-1 Chikushinmachi, Sakai-shi, Osaka Ube Industries, Ltd. Sakai Plant (72 ) Inventor Ikunori Sakai 3-1-1, Chikko Shinmachi, Sakai City, Osaka Prefecture Inside the Sakai Plant of Ube Industries, Ltd. (72) Inventor Takezumi Nishio 1st Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Nomura Takao 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Co., Ltd. (72) Inventor Hisayuki Iwai 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (56) References JP-A-2-294443 (JP) JP-A-1-132649 (JP, A) JP-A-3-275753 (JP, A) JP-A-5-59251 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB (Name) C08L 5 3/00 C08L 3/34 C08L 23/00-23/24

Claims (1)

(57) [Claims] (A) It contains an ethylene content of 0.5 to 10% by weight, a boiled n-heptane insoluble content of a polypropylene component of 97% by weight or more, and a p-xylene soluble content of 5 to 20% by weight at room temperature. , 135 ° C) Highly crystalline ethylene-propylene block copolymer having a melt flow index of 30 or more and a flexural modulus of 18,000 kg / cm ² or more of 45 to 80.
(B) ethylene content 70-90% by weight and Mooney viscosity ML
_{1 + 4} (100 ° C.) 5 to 70 amorphous ethylene-propylene copolymer 10 to 20% by weight, (C) α-olefin having 4 to 10 carbon atoms 5 to 15 mol%
And a density of 0.91 or less, the melt flow index (230
C) 2.2 to 50 g / 10 min ethylene-α-olefin copolymer 5 to 15% by weight, (D) butene content 10 to 25% by weight, Mooney viscosity ML _{1 + 4}
(100 ° C.) 5-20 amorphous ethylene-butene copolymer 1
(E) an average particle diameter D50 of 1.0 to 3.0 μm and a particle diameter of 10 μm
Consisting of less than 8% by weight of talc not containing
A resin composition for a bumper, wherein the component (B) is present as a rubber component reinforced by a polyethylene lamella.