摘要:
A bimodal polyethylene having a high density ranging from about 0.955 to about 0.959 g/cc, an improved environmental stress cracking resistance (ESCR) of from about 400 to about 2500 hours, and an improved 0.4% flexural modulus of from about 180,000 to about 260,000 psi (1,200 MPa to about 1,800 MPa) may be formed using a Ziegler-Natta polymerization catalyst using two reactors in series. The bimodal polyethylene may have a high load melt index (HLMI) of from about 2 and about 30 dg/min and may be optionally made with a small amount of alpha-olefinic comonomer in the second reactor. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.
摘要:
A process for the polymerization of ethylene to provide an ethylene polymer of reduced Yellowness Index. A feed stream, comprising an inert hydrocarbon diluent containing ethylene in a minor amount, is supplied to a polymerization reactor. A chromium-based polymerization catalyst and a triethylboron co-catalyst are incorporated into the feed stream within the reactor. The polymerization catalyst will normally be used in an amount within the range of 0.008-0.1 wt. % of the diluent in the feed stream and the triethylboron co-catalyst is incorporated in an amount within the range of 0.1-50 ppm of the diluent. The polymer fluff from the reactor is heated to a temperature sufficient to melt the fluff which is then extruded to produce a polymer product. The Yellowness Index after high temperature aging is at least 5% less than the corresponding Yellowness Index of a corresponding polymer product produced without the triethylboron co-catalyst.
摘要:
An improved method of manufacturing blown polyolefin films with increased bubble stability and higher blown film production rates is disclosed. A method in which the amounts and ratios of known antioxidant polymer film additives (phosphites and phenolics) are controlled to provide limited long chain branching (LCB) and greater rheological breadth in a polyethylene melt to improve both processing characteristics and mechanical properties in the resulting film.
摘要:
A bimodal polyethylene having a high density ranging from about 0.955 to about 0.959 g/cc, an improved environmental stress cracking resistance (ESCR) of from about 400 to about 2500 hours, and an improved 0.4% flexural modulus of from about 180,000 to about 260,000 psi (1,200 MPa to about 1,800 MPa) may be formed using a Ziegler-Natta polymerization catalyst using two reactors in series. The bimodal polyethylene may have a high load melt index (HLMI) of from about 2 and about 30 dg/min and may be optionally made with a small amount of alpha-olefinic comonomer in the second reactor. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.
摘要:
The present invention includes an end use article (i.e., an article of manufacture) and a process for making the same, wherein the end use article has a relatively high gloss and exhibits excellent processability over a wide range of processing conditions. The end use article can be formed with glossy polyethylene having an “a” parameter less than or equal to about 0.40, and the glossy polyethylene can be a Metallocene polyethylene. The end use article can have a 60° specular gloss of at least about 40%, or from about 40% to about 80%, or from about 60% to about 80%. The end use article may be pigmented or unpigmented.
摘要:
The rheology of polyethylene resin may be controlled by measuring the specific energy input (SEI) to the extruder and then adjusting a process parameter in response to a change in the SEI and/or by introducing both a free radical initiator and an alkali earth metal stearate into the polymerization. Indeed, the process parameter changed in response to the SEI measurement may be adjusting the proportion of free radical initiator, adjusting the proportion of alkali earth metal stearate, or both. The free radical initiator may be a peroxide, and the alkali earth metal stearate may be calcium stearate.
摘要:
Pipe articles and methods of forming the same are described herein. The pipe articles generally include a bimodal polyethylene including a greater amount of high molecular weight fraction than low molecular weight fraction and wherein the pipe article exhibits a critical temperature of less than about 0° C. at 5 bar.
摘要:
The invention relates generally to the production of polyethylene, and particularly to the production of polyethylene that is mixed with peroxides during extrusion to increase the level of long-chain branching. In an aspect, the polyethylene is used for large part blow molding (LPBM) applications. In an embodiment, the cross-linked polyethylene has a density of from about 0.945 g/cc to about 0.965 g/cc, a molecular weight distribution (MWD) of at least from 10 to 25, for example, and a high load melt index (HLMI) (ASTM D1238 21.6 kg) of from about 1 dg/min to about 30 dg/min. In an embodiment, the cross-linked polyethylene is comprised of at least one olefin having an ESCR of 100 hours to 1000 hours, and a flexural modulus of 120,000 psi to 250,000 psi.
摘要:
A polymer, and a process of producing the polymer, that comprises at least one olefin and has an ESCR of 100 hours to 500 hours, a density of 0.955 g/cc to 0.959 g/cc, and a flexural modulus of 140,000 psi to 220,000 psi. An article of manufacture that comprises the polymer.
摘要:
The present invention includes an end use article (i.e., an article of manufacture) and a process for making the same, wherein the end use article has a relatively high gloss and exhibits excellent processability over a wide range of processing conditions. The end use article can be formed with glossy polyethylene having an “a” parameter less than or equal to about 0.40, and the glossy polyethylene can be a Metallocene polyethylene. The end use article can have a 60° specular gloss of at least about 40%, or from about 40% to about 80%, or from about 60% to about 80%. The end use article may be pigmented or unpigmented.