E.i. Dupont De Nemours and Company

David Martin Taylor

Hyunkook Shin

Roger Keith Siemionko

Ervin Townsend Powers, Jr

David Jackson McGinty

Richard A Satterfield

The efficiency of electrostatic charging of polyolefin web in a process for flash-spinning polyolefin plexifilament from solution in a C -C hydrocarbon, forming the plexifilament into a web, electrostatically charging the web, and laying the web down as a sheet is improved by having present in the electrostatic charging step environment a charge-improving compound, which can be any one of a number of specifically identified classes of charge-improving compounds. The charge improving compounds are present in an amount of at least 0.1 ppm of the atmosphere in that environment or more.

Process for improving electrostatic charging of plexifilaments

The efficiency of electrostatic charging of polyolefin web in a process for flash-spinning polyolefin plexifilament from solution in a C.sub.4 -C.sub.7 hydrocarbon, forming the plexifilament into a web, electrostatically charging the web, and laying the web down as a sheet is improved by having present in the electrostatic charging step environment a charge-improving compound, which can be any one of a number of specifically identified classes of charge-improving compounds. The charge improving compounds are present in an amount of at least 0.1 ppm of the atmosphere in that environment or more.

A process to detect the loss of a continuous spun web of plexifilament fibers exiting a forwarding apparatus depends on the manner in which the filament oscillate in a cross machine direction prior to depositing onto a collecting surface. The loss of these fibers, due to hang up in the filament forwarding device, can cause multiple position spinning machine loss due to the knock down of nearby spinning positions or wrap the sheet on forwarding rolls. The hang up in the forwarding device is referred to as a blow-up. This process detects the instant a blow-up occurs through the loss of electrostatic charge due to the absence of the oscillating swath at the sensor. When the instant charge is lost at the sensor, a signal indicates a blow-up has occurred.

Process for making a non-woven sheet

A device to detect the loss of a continuous spun web of plexifilament fibers exiting a forwarding apparatus depends on the manner in which the filaments oscillate in a cross machine direction prior to depositing onto a collecting surface. The loss of these fibers, due to hang up in the filament forwarding device, can cause multiple position spinning machine loss due to the knock down of nearby spinning positions or wrap the sheet on forwarding rolls. The hang up in the forwarding device is referred to as a blow-up. This invention detects the instant a blow-up occurs through the loss of electrostatic charge due to the absence of the oscillating swath at the sensor. When the instant charge is lost at the sensor, a signal indicates a blow-up has occurred.

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Gwynedd, United Kingdom

David Martin Taylor