Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1999-01-26
2001-11-20
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
active
06320009
ABSTRACT:
FIELD OF THE TECHNIQUE
The present invention relates to a resin composition based on polypropylene and injection-molded articles made of such resin composition.
BACKGROUND OF THE TECHNIQUE
Polypropylene has widely been used in various fields including parts in automobile, parts for machines, parts for electric appliances, household commodities, kitchen utensils, packaging films and so on, wherein improvements in the performances thereof have been proposed by incorporation of additives therein which provide facilitation of requisite properties. For example, addition of an inorganic filler, such as talc, has been practised for improving stiffness and heat resistance. However, a plastic resin containing talc exhibits disadvantages, such as higher density, tendency to easy occurrence of surface damages and scratches on articles molded therefrom and tendency to whitening of the damaged portion.
In Japanese Patent Kokai Hei-6-93034 A (corresponding European Patent Application No. EP 573862 A2), a polypropylene product is described in which the processibility in molten state is improved. This polypropylene product exhibits, however, insufficient improvements in the mechanical properties, such as inferior flexural modulus and lower thermal deformation temperature.
In Japanese Patent Kokai Hei-4-202507 A, a process for producing a polypropylene resin in multiple polymerization staged in the presence of a catalyst having a specific solid titanium catalyst component is described, in which it is said that the resulting polypropylene resin is superior in the stiffness, heat resistance and so on. However, this process requires a prepolymerization of, such as, 3-methyl-1-butene, and is complicated. The polypropylene resin obtained by this process exhibits insufficient improvement in the stiffness.
In Japanese Patent Kokai Sho-59-172507 A, a process for producing a polypropylene resin superior in the stiffness, processibility and heat resistance is described, in which propylene is polymerized in two polymerization stages using a Ziegler catalyst. In this polypropylene resin, however, the improvements in the flexural modulus and in the stiffness are insufficient.
Japanese Patent Kokai Hei-4-370103 discloses a process for producing a polypropylene resin superior in the processibility and stiffness in a multi-stage polymerization using a specific catalyst. This polypropylene resin provides, however, insufficient improvement in the flexural modulus.
The object of the present invention is to provide a polypropylene resin composition, which is light-weighing and has very high values of stiffness and heat resistance, superior scratch-proof or anti-damaging property and better flowability upon molding or shaping with superior processibility, as well as injection molded articles made of such polypropylene resin composition.
DISCLOSURE OF THE INVENTION
The present invention provides for the following polypropylene resin composition and injection-molded articles:
(1) A resin composition based on polypropylene (which is referred to in the following as “the first polypropylene-based resin composition”), comprising a predominant proportion of polypropylene and having the following characteristic features A and B, namely,
A: a melt flow rate (MFR), determined at 230° C. under a load of 2.16 kg, in the range of 5-50 g/10 min. and
B: a content of a high molecular weight polypropylene having an intrinsic viscosity [&eegr;] of 9-13 dl/g in the range of 15-30% by weight.
(2) A resin composition based on polypropylene as defined in the above (1), wherein it has the following further characteristic feature C, namely,
C: an isotactic pentad proportion (mmmm proportion) determined by
13
C-NMR of 98.0% or higher.
(3) A resin composition based on polypropylene as defined in the above (1) or (2), wherein it has the following further characteristic feature D, namely,
D: a molecular weight distribution expressed by Mw/Mn determined by gel permeation chromatography (GPC) of 20 or higher and a molecular weight distribution expressed by Mz/Mw of 7 or higher.
(4) A resin composition based on polypropylene as defined in any one of the above (1) to (3), wherein it has the following further characteristic features E to I, namely,
E: a specific gravity determined by water-displacement method (ASTM D 1505) of 0.915 or lower,
F: a flexural modulus (ASTM D 790) of 2600 MPa or higher,
G: a thickness of the skin layer of at least 300 &mgr;m, which is formed on an injection-molded article when the resin composition of 190° C. is injected into a mold of 60° C. and held therein for 30 seconds.
H: a heat distortion temperature (ASTM D 648, under a load of 0.45 MPa) of 145° C. or higher and
I: a heat distortion temperature (ASTM D 648, under a load of 1.82 MPa) of 100° C. or higher.
(5) A resin composition based on polypropylene (which is referred to in the following as “the second polypropylene-based resin composition”), comprising a predominant proportion of polypropylene and having the following characteristic features C to H, namely,
C: an isotactic pentad proportion (mmmm proportion) determined by
13
C-NMR of 98.0% or higher.
D: a molecular weight distribution expressed by Mw/Mn determined by gel permeation chromatography (GPC) of 20 or higher and a molecular weight distribution expressed by Mz/Mw of 7 or higher.
E: a specific gravity determined by water-displacement method (ASTM D 1505) of 0.915 or lower,
F: a flexural modulus (ASTM D 790) of 2600 MPa or higher,
G: a thickness of the skin layer of at least 300 &mgr;m, which is formed on an injection-molded article when the resin composition of 190° C. is injected into a mold of 60° C. and held therein for 30 seconds, and
H: a heat distortion temperature (ASTM D 648, under a load of 0.45 MPa) of 145° C. or higher.
(6) A resin composition based on polypropylene, comprising a predominant proportion of polypropylene and having the following characteristic features C to H, namely,
C: an isotactic pentad proportion (mmmm proportion) determined by
13
C-NMR of 98.0% or higher.
D: a molecular weight distribution expressed by Mw/Mn determined by gel permeation chromatography (GPC) of 20 or higher and a molecular weight distribution expressed by Mz/Mw of 8 or higher.
E: a specific gravity determined by water-displacement method (ASTM D 1505) of 0.910 or lower,
F: a flexural modulus (ASTM D 790) of 2500 MPa or higher,
G: a thickness of the skin layer of at least 380 &mgr;m, which is formed on an injection-molded article when the resin composition of 190° C. is injected into a mold of 60° C. and held therein for 30 seconds, and
H: a heat distortion temperature (ASTM D 648, under a load of 0.45 MPa) of 150° C. or higher.
(7) A resin composition based on polypropylene as defined in the above (5) or (6), wherein it has the following further characteristic features A and B, namely,
A: a melt flow rate (MFR), determined at 230° C. under a load of 2.16 kg, in the range of 5-50 g/10 min. and
B: a content of a high molecular weight polypropylene having an intrinsic viscosity [&eegr;] of 9-13 dl/g in the range of 15-30% by weight.
(8) A resin composition based on polypropylene as defined in any one of the above (5) to (7), wherein it has the following further characteristic feature I, namely,
I: a heat distortion temperature (ASTM D 648, under a load of 1.82 MPa) of 100° C. or higher.
(9) A resin composition for injection molding based on polypropylene, comprising a predominant proportion of polypropylene and having the following characteristic features C to H, namely,
C: an isotactic pentad proportion (mmmm proportion) determined by
13
C-NMR of 98.0% or higher.
D: a molecular weight distribution expressed by Mw/Mn determined by gel permeation chromatography (GPC) of 20 or higher and a molecular weight distribution expressed by Mz/Mw of 8 or higher.
E: a specific gravity determined by water-displacement method (ASTM D 1505) of 0.910 or lower,
F: a flexural modulus (ASTM D 790) of 2500 MPa or higher,
G: a thickness of the skin layer of at least 380 &mgr;m, which is formed on an in
Hashimoto Mikio
Nakagawa Hideki
Nakano Yoshifumi
Sakuda Yoshiyuki
Yoshikawa Hiroshi
Grand Polymer Co Ltd
Harlan B.
Wu David W.
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