Claims
- 1. An injection-molding polyethylene composition characterized in that
- (1) it comprises an ultrahigh-molecular-weight polyethylene having an intrinsic viscosity, measured in decalin solvent at 135.degree. C., of 10 to 40 dl/g and a low-molecular-weight or high-molecular-weight polyethylene having an intrinsic viscosity, measured in decalin solvent at 135.degree. C., of 0.1 to 5 dl/g,
- (2) the proportion of the ultrahigh-molecular-weight polyethylene is in the range of 15 40 % by weight based on the total weight of the ultrahigh-molecular-weight polyethylene,
- (3) it has an intrinsic viscosity {.eta.}.sub.c, measured in decalin solvent at 135.degree. C., of 4.0 to less than 10 dl/g,
- (4) it has a melting torque T of not more than 4.5 kg-cm, and
- (5) it is produced by a multistep polymerization process which comprises polymerizing ethylene in at least one polymerization step to form an ultrahigh-molecular-weight polyethylene having an intrinsic viscosity of 10 to 40 dl/g and polymerizing ethylene in another polymerization step in the presence of hydrogen to form a low-molecular-weight of high-molecular-weight polyethylene having an intrinsic viscosity of 0.1 to 5 dl/g, both in the presence of a Ziegler-type catalyst formed from (A) a highly active titanium catalyst component containing magnesium, titanium and halogen as essential ingredients and (B) an organoaluminum compound catalyst component.
- 2. The composition set forth in claim 1 wherein the ultrahigh-molecular-weight polyethylene has an intrinsic viscosity of 15 to 35 dl/g.
- 3. The composition set forth in claim 1 wherein the intrinsic viscosity of the low-molecular-weight or high-molecular-weight polyethylene is 0.5 to 3 dl/g.
- 4. The composition set forth in claim 1 wherein the proportion of the ultrahigh-molecular-weight polyethylene is 20 to 35 % by weight based on the total weight of the ultrahigh-molecular-weight polyethylene and the low-molecular-weight or high-molecular-weight polyethylene.
- 5. The composition set forth in claim 1 which has an intrinsic viscosity of 4 to 9 dl/g.
- 6. A molded article which is characterized in that
- (1) it has been prepared by injection molding the polyethylene composition of claim 1, and
- (2) it has no delamination.
Priority Claims (1)
Number |
Date |
Country |
Kind |
61-156168 |
Jul 1986 |
JPX |
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Parent Case Info
This application is a continuation of application Ser. No. 07/163,816 filed Feb. 23, 1988 now abandoned.
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Continuations (1)
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Number |
Date |
Country |
Parent |
163816 |
Feb 1988 |
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