JPH069852A - Resin composition for bumper - Google Patents

Abstract

PURPOSE:To provide a lightweight resin composition for bumper good in moldability, with high hardness and high low-temperature impact resistance, also good in appearance and coatability, thus suitable for injection molding for automotive bumpers, having a specific composition. CONSTITUTION:The composition comprising (A) a highly crystalline ethylene- propylene block copolymer 0.5-10wt.% in ethylene content, >=97wt.% in the boiling n-heptane insolubles for the polypropylene component, 30-100g/10min in melt flow index and >=18000kg/cm<2> in flexural modulus, (B) an amorphous ethylene-propylene copolymer 70-90wt.% in ethylene content and 5-70 in Mooney viscosity and present in the form of a rubber component reinforced with polyethylene lamellae, (C) an ethylene-alpha-olefin copolymer 5-15mol% in 4-10C alpha-olefin content and 2.2-50g/10min in melt flow index, (D) an amorphous ethylene-butene copolymer 10-25wt.% in butene content and 5-20 in Mooney viscosity, and (E) talc 1-3mum in mean particle diameter.

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, more specifically, a surface hardness of 55 or more (Rockwell R
-Scale) with a melt flow index of 15 g / 10 min or more, low temperature embrittlement temperature of -30 ° C or less, light weight and moldability,
The present invention relates to a bumper resin composition having good paintability and appearance.

[0002]

2. Description of the Related Art Polypropylene resin is often used as a material for automobile bumpers from the viewpoints of weight reduction, rust prevention, and freedom of design. However, the conventional resin composition for bumpers has insufficient impact resistance and paintability.
Therefore, JP-A-57-55952, 58-111846, and
59-98157, 58-17139, 57-177038, 57-207630, 57-195134, 57-
As disclosed in JP 159841 and JP 55-21494, in order to impart impact resistance and paintability to a polypropylene resin, an ethylene-propylene copolymer is blended to impart rigidity and dimensional stability. In order to do so, it has been attempted to fill 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 large in size, and conventional materials are heavy and have low fluidity, which makes injection molding difficult.
Observing the central part of the cross section of the bumper molded with such a resin composition with a transmission electron microscope (hereinafter abbreviated as TEM), as shown in FIGS. 3 and 4, the rubber component is an island in the sea of polypropylene resin. As a result, the interfaces of the rubber component of the resin are observed as clear lines.

[0004]

Therefore, the present inventors have
Light weight, good moldability, high hardness, high temperature impact resistance,
Moreover, as a result of intensive studies aimed at obtaining a resin composition having good appearance and coatability, a specific highly crystalline ethylene-propylene block copolymer, an amorphous ethylene-propylene copolymer, an ethylene-α-olefin copolymer were obtained. The present invention was completed by blending a polymer, an amorphous ethylene-butene copolymer, and talc in specific proportions.

That is, the present invention relates to (A) ethylene content
0.5-10% by weight, boiling component of polypropylene component insoluble in n-heptane of 97% by weight or more and room temperature p-xylene soluble component 5-5%
Contains 20% by weight, intrinsic viscosity (decalin, 135 ° C) of 2 or more, melt flow index 30 to 100, and flexural modulus
Highly crystalline ethylene-propylene block copolymer of 18,000 kg / cm ² or more 45-80% by weight, (B) ethylene content 70-
90% by weight and Mooney viscosity ML _{1 + 4} (100 ° C) 10 to 20% by weight of amorphous ethylene-propylene copolymer of 5 to 70 (C)
Melt flow index (230 ° C) with a C4-10 α-olefin content of 5-15 mol% and a density of 0.91 or less
2.2-50 g / 10 min ethylene-α-olefin copolymer 5-15 wt%, (D) butene content 10-25 wt%, Mooney viscosity ML _{1 + 4} (100 ° C) 5-20 amorphous ethylene 1 to 10% by weight of butene copolymer, and (E) average particle diameter D50
Resin composition for bumper, characterized by comprising less than 8% by weight of talc having a particle size of 1.0 to 3.0 μm and having a particle size of 10 μm or more, and the component (B) is present as a rubber component reinforced by polyethylene lamella. Regarding

[0006] Observation of the central portion of the cross section of the bumper molded with the resin composition for bumpers of the present invention by TEM shows
As shown in FIGS. 2 and 3, a morphology distinctly different from the conventional FIGS. 3 and 4 is observed. That is, (1) the rubber component has a flat shape and is not only distributed as islands, but many continuous parts are recognized. (2) The interface between the resin and the rubber component is extremely vague. Furthermore, as a point that is decisively different from the conventional one, (3) lamella of polyethylene was observed in the rubber component containing the amorphous ethylene-propylene copolymer as the main component, and the rubber reinforced with polyethylene was clearly observed. To be

Hereinafter, each component of the bumper resin composition according to the present invention will be specifically described. Component (A) The component (A) used in the present invention is important for ensuring the fluidity and rigidity of the composition, and its ethylene content is
0.5-10% by weight, preferably 1.5-7% by weight,
Boiling n-heptane insoluble component of polypropylene component is 97% by weight or more, preferably 97.5% by weight or more, normal temperature para-xylene soluble component (consisting of amorphous ethylene-propylene copolymer and low molecular weight polymer) 5 to 20% by weight %, Preferably 6 to
15% by weight, the intrinsic viscosity (decalin, 135 ° C.) of 2 or more, preferably 3 to 12, and the melt flow index of 30 to 100 g / 10 minutes, preferably 40 to 80 g / 10 minutes,
Flexural modulus 18,000 kg / cm ² or more, preferably 19,000 to ²
It is 5,000 kg / cm ² . Flexural modulus is 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 of polypropylene component n
The term “heptane insoluble matter” refers to a boiling n-heptane insoluble matter of crystalline polypropylene (sometimes referred to as a matrix) used in a block copolymer reaction. When the boiling n-heptane insoluble component of the polypropylene component is less than 97% by weight, the surface hardness is lowered, and when the room temperature para-xylene soluble component has an intrinsic viscosity (decalin, 135 ° C.) of less than 2, Has a low Izod impact strength at a temperature of -30 ° C. If the ethylene content is less than 0.5% by weight, impact resistance is lowered, and if it exceeds 10% by weight, rigidity is lowered. If the room temperature para-xylene soluble content is less than 5% by weight, impact resistance is lowered, and if it exceeds 20% by weight, rigidity is lowered. Further, when the melt flow index is less than 30, the appearance of the molded product and the moldability of the resin composition deteriorate, and when it exceeds 100, the impact resistance decreases. In any case, since the resin composition cannot be used as a material for a molded product which is required to have excellent appearance at the same time as rigidity, surface hardness, low temperature impact resistance and paintability, outside the range specified above, 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. When the content is less than 45% by weight, moldability becomes poor, and when it exceeds 80% by weight, coatability becomes poor. Two or more highly crystalline ethylene-propylene block copolymers may be used as long as the total amount thereof is within the above range. Further, unless deviating from the object of the present invention, a crystalline ethylene-propylene block copolymer 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, its ethylene content is 70 to 90% by weight, and the Mooney viscosity ML _{1 + 4} (100 ° C.) 5 to 70, preferably 10 to 60.
belongs to. If the ethylene content is less than 70% by weight, the surface hardness will decrease, and if it exceeds 90% by weight, the impact resistance will be insufficient. When the Mooney viscosity is less than 5, the molecular weight is too small and impact resistance is insufficient, and when it exceeds 70, the molecular weight becomes too large and it is difficult to sufficiently disperse it in the highly crystalline ethylene-propylene block copolymer. Therefore, the impact resistance is lowered and the fluidity is also lowered. 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 are insufficient, and if it exceeds 20% by weight, rigidity is insufficient.

Component (C) The ethylene-α-olefin copolymer used as the component (C) in the present invention is important for reinforcing the component (B) and improving the fluidity. The α-olefin has 4 to 10 carbon atoms, and among them, those having 4 or 6 or 8 carbon atoms are preferable. The α-olefin content is 5 to 15
Mol%, preferably 7 to 15 mol%. If it is less than 5 mol%, the component (B) is excessively strengthened to lower the impact resistance, and 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, the impact resistance is insufficient. The melt flow index (230 ° C.) of component (C) is 2.2 to 50 g / 10 minutes, preferably 6 to 40 g / 10 minutes. If it is less than 2.2 g / 10 minutes, the fluidity is low, and if it exceeds 50 g / 10 minutes, the impact resistance is lowered. The component (C) is contained in the composition according to 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 becomes 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 compatibilizing agent for the components (B) and (C), and has a butene content of 10 to 25% by weight and a Mooney viscosity of ML _{1 + 4} (100 ° C) of 5 to 20. It is a thing. If the butene content is less than 10% by weight, the crystallinity of the ethylene chain will be high and the impact resistance will be reduced, and if it exceeds 25% by weight, it will be softened and the surface hardness of the molded product will be insufficient. As described above, the Mooney viscosity is 5 to 20, and when the Mooney viscosity is less than 5, the molecular weight is too small and impact resistance is insufficient.
When it exceeds 20, the molecular weight becomes too large and the moldability is deteriorated. The content of component (D) in the composition according to the present invention is 1 to
It is 10% by weight, preferably 1 to 7% by weight. If the content is outside 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.

Component (E) The talc used as the component (E) in the present invention has an average particle diameter D ₅₀ of 1.0 μm to 3.0 μm, preferably 1.0 μm.
It is important that the particle size is from m to 2.5 μm and does not include particles having a particle size of 10 μm or more. The particle size distribution of talc is measured by the Horiba Seisakusho natural centrifugal sedimentation automatic particle size analyzer CAPA-300.
Went by. The average particle diameter D ₅₀ of the above talc is 1.0 μm
If less than, it becomes difficult to disperse the composition of the present invention,
The molded product lacks impact resistance. If it exceeds 3.0 μm, the balance between rigidity and impact resistance becomes poor. The talc is less than 8% by weight, preferably 7% in the composition according to the present invention.
It is contained by weight% or less. If the content of talc is 8% by weight or more, the appearance becomes poor and the weight of the molded product becomes heavy.
Impact resistance is also reduced.

The talc used in the present invention may be surface-treated with various treating agents, as long as it does not violate its purpose. As the surface treatment agent, for example, a silane coupling agent system,
Examples thereof include chemical or physical surface treatment with various treating agents such as higher fatty acid type, fatty acid metal salt type, unsaturated organic acid or its derivative, organic titanate type, resin acid type and polyethylene glycol ether.

The respective components constituting the resin composition of the present invention are mixed by using a Banbury mixer, a single screw extruder, a twin screw extruder,
It can be performed using a high-speed twin-screw extruder or the like, but particularly preferably, it can be easily performed 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 in a high-speed twin-screw extruder, a twin-screw extruder, or a Banbury mixer. Thus, the components (B) to (D) may be melt-mixed by the above mixer first.

In order to further improve the performance of a molded article obtained by molding the resin composition of the present invention, an antioxidant, an ultraviolet ray absorbing agent, or when each component of the composition of the present invention is mixed or after the components are mixed. Agents, pigments, paintability improving agents, lubricants and the like can be added. 2,6 as an antioxidant
-Ditertiary butylphenol, 2,6-ditertiary butyl-4-ethylphenol, 2,6-ditertiary butyl-4-n-butylphenol, 2,6-
Ditert-butyl-α-dimethylamino-para-cresol, 6- (4-hydroxy-3,5-ditert-butyranilino) -2,4-bisoctyl-thio-
1,3,5-triazine, n-octadecyl-3-
(4'-Hydroxy-3 ', 5'-ditertiarybutylphenyl) propionate, 2,6-ditertiarybutyl-4-methylphenol, tris- (2-methyl-4-hydroxy-5-tert-butylphenyl)
Butane, tetrakis- [methylene-3- (3 ', 5'-
Ditertiary butyl-4'-hydroxyphenyl) propionate] methane, 1,3,5-trimethyl-2,
4,6-Tris (3,5-ditert-butyl-4-
(Hydroxybenzyl) benzene, dilaurylthiodipropionate and the like.

Further, as the ultraviolet absorber which can be used in the composition of the present invention, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-octadecyloxybenzophenone, 4-dodecyloxy-2- Hydroxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2- (2'-hydroxy-
3'-tert-butyl-5'-methylphenyl)-
5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'-ditertiarybutyl-phenyl)-
5-chlorobenzotriazole, bis- (2,6-dimethyl-4-piperidinyl) sebacate, 1,2,3,4
Examples include butanetetracarboxylic acid 1,2,2,6,6-pentamethyl-4-piperidinol tridecyl alcohol condensate.

Further, iron black, carbon black, titanium oxide and the like can be optionally added to the resin composition of the present invention, magnesium benzoate and the like can be used as a paintability improving agent, and a fatty acid metal salt can be used as a lubricant. , Fatty acid amides, and the like. From the resin composition of the present invention, it is possible to obtain a lightweight bumper having good appearance, moldability, and coatability by molding by a conventionally known injection molding method.

[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, the composition was
2,6-ditertiary butyl-4-methylphenol
0.1PHR, pentaerythrityl-tetrakis [3-
(3,5-ditertiarybutyl-4-hydroxyphenyl) propionate] 0.3PHR, bis (2,2,6
6-tetramethyl-4-piperidyl) sebacate 0.3PH
R, magnesium stearate 0.2PHR, carbon black 1.0PHR were added and mixed in a tumbler, then high speed 2
After melt-kneading and granulating at 220 ° C with a shaft 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 according to ASTM D1238 (temperature 230 ° C, load 2,160 kg) (2) density according to ASTM D1505 (3) low temperature embrittlement temperature according to JIS K7216 (4) Izod impact strength according to ASTM D256 Conformity (Test temperature -30 ℃) (5) Flexural modulus Conforms to ASTM D790 (Test temperature 23 ℃) (6) Surface hardness Conforms to ASTM D785 (Rockwell R-Scale) (7) Appearance Then, the appearance quality of the obtained flat plate-shaped test piece (mirror surface) was visually determined. Judgment criteria ○ There is almost no trasima pattern. △ A trasima pattern is observed in half of the molded product. × A trasima pattern is observed on the entire surface of the molded product. Molding conditions Molding machine UBE MAX D150-10 Test piece 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 ℃ Cooling time 30 seconds (8) Paintability The resin composition was injection-molded to obtain a flat test piece of 50 mm x 90 mm x 2 mm. This flat test piece
The surface was cleaned by exposing it to a 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 treatment was performed. The conditions of plasma treatment were as follows.・ Vacuum level 1.0 Torr ・ Microwave output 0.05kw ・ Processing time 0.3 seconds ・ Gas flow rate 600 cc / min ・ Processing gas Air After plasma processing, 1-component urethane topcoat paint is applied to a film thickness of 40 μm did. This at 120 ℃
It was dried for 30 minutes and then left at room temperature for 48 hours to obtain a coated article. The paintability of this coated article was evaluated as follows. First, the coating film of this test piece was cut in a grid pattern with a cutter knife to divide it into 100 sections.
This section is 1 mm square. A cellophane tape was attached from above, and when the cellophane tape was peeled off, the areas where the paint had peeled off were counted. The paintability was evaluated as ◯ when there was no section where the paint was peeled, Δ when 1 to 10 of 100 zones were peeled, and X when 11 or more were peeled.

The characteristics of each component used in Examples and Comparative Examples are shown below. Component (A): Crystalline ethylene-propylene block copolymer name A-1 A-2 A-3 Ethylene content 4.5 4.3 7.0 (wt%) Boiling n-heptane 97.8 97.5 93.8 Insoluble matter (wt%) Normal temperature Para -Xylene 4.5 4.3 4.2 Intrinsic viscosity of soluble matter Melt flow index 47 35 42 (g / 10 minutes) 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 vapor-phase method catalyst Ti-Mg-Si-Al / toluene-auxiliary agent diethylaluminum chloride-comonomer 1-butene 1-butene gas composition ratio _{1: 1.5 - (C 2:} C 4) hydrogen (mol% / monomers) 0.2 - polymerization pressure (kg / cm ²⁾ 1500 - polymerization temperature (℃) 200max -

(Polymerized Polymer) MI (g / 10 min) 30 2 1-butene 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 produced by the following method.

(Preparation of catalyst) A toluene solution containing 1.3 kg of methyltriethoxysilane was added dropwise to a toluene slurry containing 1 kg of aluminum chloride at about 20 ° C, and the mixture was kept at 30 ° C. N-Butyl magnesium chloride was added to the reaction mixture at -10 ° C.
After 1.6 kg of an isoamyl ether solution was added dropwise and kept at 25 ° C, 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 the carrier, and the mixture was kept at 90 ° C. The solid catalyst component obtained was filtered and washed.

(Polymerization) Monomers and hydrogen shown in the table are continuously supplied to a tubular reactor having a total length of about 400 m, and the catalyst and co-catalyst are continuously injected from an injection point of an inlet of the reactor to a predetermined pressure. -Copolymerized at temperature. C-2 Made by 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 all 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 paintability, and is optimal 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 drawings]

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

FIG. 2 is an electron micrograph (100,000 times) showing the structure 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 times) showing the structure of the structure of the resin of Comparative Example 1.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshifumi Nakano 3-chome, Chikko Shinmachi, Sakai City, Osaka Prefecture Ube Industries Ltd., Sakai Factory (72) Ikunori Sakai 3-chome, Chikko Shinmachi, Sakai City, Osaka Prefecture Ube Industries Sakai Plant Co., Ltd. (72) Inventor Takesumi Nishio 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor Takao Nomura 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (72 ) Inventor Hisayuki Iwai 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Automobile Co., Ltd.

Claims (1)

[Claims] (A) An ethylene content of 0.5 to 10% by weight, a boiling n-heptane insoluble component of polypropylene component of 97% by weight or more and a room temperature p-xylene soluble component of 5 to 20% by weight, and an intrinsic viscosity (decalin). , 135 ° C) 2 or higher, melt flow index 30 to 100, and flexural modulus 18,000 kg / cm ² or higher highly crystalline ethylene-propylene block copolymer 45 to 80
% By weight, (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) C4 to C10 α-olefin content 5 to 15 mol%
And a density of 0.91 or less, the melt flow index (230
℃) 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 to 20 amorphous ethylene-butene copolymer 1 to
10% by weight, and (E) average particle diameter D50 is 1.0 to 3.0 μm and particle diameter is 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 polyethylene lamella.