The Dow Chemical Company

Stephen P Krupp

Edward N Knickerbocker

John O Bieser

Scott L Gessner

Wesley L Archer

Susan M Dallessandro

Donald D Waters

Thomas K Fletcher

An improved method of melt spinning linear polyethylene into fiber, especially fine denier fiber, with minimal fiber breakage is disclosed. The method includes imparting high shear into the polyethylene just prior to extrusion through the spinneret die and also results in lower die swell. The high shear can be imparted by use of sintered metal filter media, multiple stacks of fine mesh screens or similar shear inducing media. The method is especially effective when the linear polyethylene contains a relatively high molecular weight species, as determined using gel permeation chromatography with a low angle laser light scattering detector.

Method of improving melt spinning of linear ethylene polymers

Blends of high molecular weight linear polyethylene and low molecular weight linear polyethylene provide improved staple fiber-forming capabilities over that found with either polymer taken alone. Preferably at least one of the polymers used in the blend is a linear low density polyethylene, LLDPE, which is a linear polyethylene comprising ethylene copolymerized with an amount of a higher alpha-olefin which causes the density of the copolymer to be less than that of a homopolymer made using the same process and catalyst. The higher alpha-olefin can be at least one in the C.sub.3 -C.sub.12 range, preferably in the C.sub.3 -C.sub.8 range.

Linear ethylene polymer staple fibers

A fiber made of pitch having a percent elongation of about 2 percent or greater is made by melt spinning an optically isotropic pitch to form a fiber typically in the range of about 5 to about 50 microns diameter, treating the fiber with an oxidizing atmosphere, subsequently removing a certain portion of the oxidant thereby reducing the weight of the fiber, with the optional post-treatment step of repetitively stretching in the elastic range short of breakage to increase the percent elongation.

Method of making elastic carbon fibers

Blends of high molecular weight linear polyethylene and low molecular weight linear polyethylene provide improved fiber-forming capabilities over that found with either polymer taken alone. Preferably at least one of the polymers used in the blend is a linear low density polyethylene, LLDPE, which is a linear polyethylene comprising ethylene copolymerized with an amount of a higher alpha-olefin which causes the density of the copolymer to be less than that of a homopolymer made using the same process and catalyst. The higher alpha-olefin can be at least one in the C.sub.3 -C.sub.12 range, preferably in the C.sub.4 -C.sub.8 range.

Improved spunbonding of linear polyethylenes

A fiber made of pitch is disclosed. In the preferred and illustrated embodiment, the fiber has a percent elongation of about 2 percent or greater. This fiber is made by melt spinning an optically isotropic pitch to form a fiber typically in the range of about 5 to about 50 microns diameter, treating the fiber with an oxidizing atmosphere, subsequently removing a certain portion of the oxidant thereby reducing the weight of the fiber, with the optional post-treatment step of repetitively stretching in the elastic range short of breakage to increase the percent elongation.

Elastic carbon fibers

Polyethylene fibers and spunbonded fabric or web

A diaphragm or membrane for use in electrolysis cells resistant to chemical action thereof is disclosed. In the preferred and illustrated embodiment, a fluoropolymer binder cooperative with a random mix of carbon fibers up to about 13 mm long and up to about 0.01 mm in diameter forms such diaphragm or membrane. The carbon fibers are preferably pliable, nonbrittle, resilient, electrically nonconductive, impervious to chemical attack, and are annealed up to a specified temperature.

Inert carbon fiber diaphragm

Stable methylchloroform solvent compositions in combination with from about 3 to about 5 volume percent of 2-butanol and from about 1 to about 3 volume percent of 3-methyl-1-butyn-3-ol have been shown to be superior solvents for removing flux from circuit boards. Such compositions have no flash point and maintain excellent distribution of the components in the vapor and liquid sections of the defluxing apparatus.

Growing community of inventors

Houston, TX, United States of America

Stephen P Krupp