Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
1999-08-27
2001-06-19
Nutter, Nathan W. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S216000, C525S238000, C525S240000, C525S241000
Reexamination Certificate
active
06248830
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a polyolefin resin composition exhibiting its superior characteristics for high-speed tensile breaking extension while ensuring harmony with a bending elastic modulus.
2. Description of Related Art
Recently, a shock absorbing structure is likely to be employed at various sites from the viewpoint of ensuring human protection. This shock absorbing structure generally comprises a resin based energy absorbing body. Even if a human being bumps against this shock absorbing structure, the resin based energy absorbing body absorbs shock energy at that time. Recently, it is expected to increase capability of absorbing the shock energy of the resin based energy absorbing body (for instance, from the viewpoint of better human protection (reduction of injury or the like), it is expected to enable shock energy to be absorbed over a long time while a crush acceleration at the time of collision is maintained at a low level (in a state in which a speed change is small)).
However, when the shock energy absorbing capability is increased as described above, the thickness of the resin based energy absorbing body muse be thickened, and collision strokes at the time of collision must be increased, thus causing deterioration of the use (mounting) environment of the shock absorbing structure.
The following description will be given with reference to a specific example. The above-mentioned shock absorbing structure is applicable to vehicles such as automobiles having possibility of collision in which a clew (the head or the like) may bump against the body, as disclosed in Japanese Patent Laid-Open Nos. 10-129377 and 10-76893. However, in the case where an attempt is made to lower a maximum acceleration at the time of crush of the resin based energy absorbing body from the viewpoint of better human protection, it becomes impossible to absorb shock energy due to lowered maximum acceleration at the time of the crush. In this case, the thickness of the resin based energy absorbing body must be thickened to ensure the shock absorption stroke. It is difficult to adopt such a construction considering a limited vehicle space.
On the other hand, as disclosed in Japanese Patent Laid-Open No. 8-127298, it is proposed that a resin based energy absorbing body is crushed, and a pillar as a strength member is also deformed by the resin based energy absorbing body to increase shock absorption strokes at the time of collision. Recently, to improve body rigidity, the thickness of the pillar is increased, reinforcement is added, high tension or the like is applied. Therefore, it is difficult to deform the pillar as a strength member to increase the shock absorption strokes based on the above-mentioned proposal.
SUMMARY OF THE INVENTION
In view of such circumstance, the present invention has been achieved under the recognition that, as to shock absorption, there is a limitation to improvement from a structural aspect, and there is a need for ensuring improvement from a material aspect (a resin composition). It is a technical object of the present invention to provide a polyolefin resin composition capable of enhancing its shock absorption performance while considering human protection and use environment or the like.
To achieve the above-mentioned technical object, in a first aspect of the present invention, there is provided: a polyolefin resin composition comprising a component (A) comprising polypropylene or propylene-ethylene block copolymer with a melt flow rate (MFR) greater than 16 (g/10 minutes); a component (B) comprising ethylene based rubber; and a component (D) compatible with the component (B), wherein a ratio of summation of a propylene-ethylene copolymer part in the component (A), the component (B), and the component (D) to summation of the component (A), the component (B), and the component (D) is 25 wt. % or more and 45 wt. % or less, and a ratio of a blend quantity of the component (D) to summation of the blend quantity of the component (B) and the blend quantity of the component (D) is less than 0.8.
In a second aspect of the present invention, a melt flow rate (MFR) of the component (A) is greater than 45 (g/10 minutes).
In a third aspect of the present invention, the component (B) is a copolymer containing at least both of a styrene skeleton and an ethylene skeleton.
In a fourth aspect of the present invention, the component (B) contains a propylene skeleton.
In a fifth aspect of the present invention, the component (B) contains a butylene skeleton.
In a sixth aspect of the present invention, the component (B) contains an &agr;-olefin copolymer containing ethylene.
In a seventh aspect of the present invention, the melt flow rate (MFR) of the copolymer of the component (B) is 0.5 (g/10 minutes) or more and 140 (g/10 minutes) or less.
In an eighth aspect of the present invention, the styrene skeleton content in the copolymer of the component (B) is 13 wt. % or more and less than 35 wt. % of the component (B).
In a ninth aspect of the present invention, the component (D) is an aromatic vinyl polymer.
In a tenth aspect of the present invention, the melt flow rate (MFR) of the component (D) is 6 (g/10 minutes) or more.
In an eleventh aspect of the present invention, the component (D) is polystyrene.
In a twelfth aspect of the present invention, the component (B) surrounds the component (D), and these components each have a fine structure dispersed in the component (A).
In a thirteenth aspect of the present invention, a ratio of the viscosity before mixing in the component (B) to that in the component (A) (viscosity of the component (B) /viscosity of the component (A)) is 2.6 to 10.
In a fourteenth aspect of the present invention, a ratio of the viscosity before mixing in the component (D) to that in the component (B) (viscosity of the component (D) /viscosity of the component (B)) is 0.4 or less.
In a fifteenth aspect of the present invention, the composition is fractionated into an extraction residue component and an extracted component by Soxhlet fractionation using chloroform; the extracted component is fractionated into a methyl ethyl ketone insoluble component and a methyl ethyl ketone soluble component by dissolution fractionation using methyl ethyl ketone; the methyl ethyl ketone soluble component is fractionated into a hexane soluble component and a hexane insoluble component by dissolution fractionation using hexane; an n-decane soluble component is fractionated by heating dissolution fractionation using n-decane with respect to the extraction residue component; and when limiting viscosity &eegr;
1
of the hexane insoluble component, limiting viscosity &eegr;
2
of a mixture in which the hexane soluble component and the methyl ethyl ketone insoluble component are mixed with each other, and limiting viscosity &eegr;
3
of the n-decane soluble component are obtained, a ratio of the limiting viscosity &eegr;
2
of the mixture to the limiting viscosity &eegr;
3
of the n-decane soluble component (&eegr;
2
/&eegr;
3
) is 0.6 or more and 0.9 or less.
In a sixteenth aspect of the present invention, the composition is fractionated into an extraction residue component and an extracted component by Soxhlet fractionation using chloroform; the extracted component is fractionated into a methyl ethyl ketone soluble component and a methyl ethyl ketone soluble component by dissolution fractionation using methyl ethyl ketone; the methyl ethyl ketone insoluble component is fractionated into a hexane soluble component and a hexane insoluble component by dissolution fractionation using hexane; an n-decane soluble component is fractionated by heating dissolution fractionation using n-decane with respect to the extraction residue component; and when the limiting viscosity &eegr;
1
of the hexane insoluble component, the limiting viscosity &eegr;
2
of the mixture in which the hexane soluble component and the methyl ethyl ketone insoluble component are mixed with each other, and the limiting viscosity &eegr;
3
of the n-decane soluble comp
Adachi Daisaburou
Hara Masao
Matsuda Yushi
Brooks & Kushman P.C.
Mazda Motor Corporation
Nutter Nathan W.
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