The Dow Chemical Company

Kun S Hyun

Stephen R Betso

Chung P Park

Steven R Jenkins

Mark J Hall

Donald E Kirkpatrick

James A Stevenson

Warren L Treptow

Thomas J Parsons

Ravi Ramanathan

Patrick M Russell

Duane F Foye

Paul T Louks

Robert E Wrisley

Jack A Berdasco

Bobby A Howell

Bernard C Obi-Ahuba

A gear pump exhibiting improved efficiency over a broader range of fluid viscosity and pump speed includes a compression zone defined between each of a pair of pump gears and internal walls of a gear chamber, wherein the compression zones have a non-uniform thickness along a longitudinal direction of the gears. The geometry of the compression zones provides a mechanism whereby the drag of the viscous fluid which is induced by the rotation of the pump gears carries the viscous fluid through a progressively narrower gap in the direction of rotation ending in a final smooth pinch-off at the start of the seal zone. The geometry of the compression zone maximizes the drag and pressurization of the viscous fluid being pumped into the teeth of the gears, thereby assisting in the complete filling of the teeth. The result is improved fill efficiency over a broader range of pump speeds and over a broader range of fluid viscosity.

High efficiency gear pump for pumping highly viscous fluids

An extruder screw for use in a barrel of an extruder for forwarding thermoplastic polymer from a first end to a second end of the extruder. The extruder comprises a transition section and at least one flight extending substantially along the length of the screw. A dam is positioned at the point where the rapid melting of the solids starts to slow down and the rate of solid bed width decrease approaches zero. The dam provides the screw with a high output of extrudate and close control of the residence time of polymer particles as they are transported through the screw, resulting in an extrudate which is uniformly melted and which is substantially free of degradation products and/or entrapped air.

Extruder screw

The present invention is a coated particulate in the form of a powder or in the form of a pellet, the particulate comprising a vinylidene chloride interpolymer and being coated with at least one processing aid at a level effective to improve the extrudability of the vinylidene chloride interpolymer. The processing aid beneficially is selected from the group consisting of fatty esters; wax esters; glycerol esters; glycol esters; fatty alcohol esters, fatty alcohols; fatty amides; metallic salts of fatty acids; olefin polymers and polyolefin waxes.

Extrudable thermoplastic particulates

In one embodiment, the present invention is a polymeric composition, in pellet form, which comprises a vinyldene chloride interpolymer, and a friction reducing polymer (FRP) in an amount of from about 0.1 to about 40 weight percent, said weight percent being based on the total weight of the polymeric composition. The FRP is selected to selected to lower the frictional coefficient and the mechanical energy to extrude of the polymeric composition. In another embodiment, the present invention is a polymeric composition, in either power or pellet form, possessing improved extrudability, composition comprises a vinylidene chloride interpolymer in an amount of from about 55 to about 99.85 weight percent, a FRP in an amount from about 0.1 to about 40 weight percent, and a salt of an acid in an amount of between about 0.05 and about 5 weight percent, said weight percents being based on the total weight of the polymeric composition.

Extrudable polymeric composition

The present invention is a process for forming an extruded article containing a copolymer of vinylidene chloride and at least one other ethylenically-unsaturated comonomer, said process comprising the step of extruding the copolymer in the presence of (1) at least one gas which is inert with respect to the copolymer and does not plasticize the copolymer; and (2) essentially no gases which are not inert with respect to the copolymer. Vinylidene chloride copolymers extruded according to the process of the present invention have lower metal adhesion and less tendency to contain specks of carbon than do vinylidene chloride copolymer copolymers extruded under an air atmosphere.

Extrusion of vinylidene chloride copolymers under inert atmosphere

A method and equipment for processing a thermoplastic polymer wherein at least a portion of the surfaces which contact the thermoplastic polymer, while said thermoplastic polymer is in a heat plastified state, comprise boron carbide.

Process and equipment for processing thermoplastic polymers

A process for improving the extrudability of a vinylidene chloride interpolymer pellet. A vinylidene chloride interpolymer pellet displaying a first endotherm, as determined by differential scanning calorimetry according to American Society of Testing and Materials Test Method D-3417, below 75.degree. Celsius is exposed to a temperature above about 55.degree. Celsius for a length of time sufficient to raise said first endotherm to 75.degree. Celsius or above. Pellets treated in such a manner possess improved extrudability.

Vinylidene chloride interpolymer possessing improved extrudability

A polymeric composition is provided which includes the reaction product of vinylidene chloride, an optional copolymerizable monomer, and an .alpha.,.beta. ethylenically unsaturated silane crosslinking agent. The polymeric reaction product may also be used to form films and coating. The composition further may include a volatile blowing agent which, when activated, expands the polymeric reaction product into a low density cellular structure.

Crosslinked silane-functional vinylidene chloride polymer and films or

A polymeric composition is provided which includes the reaction product of vinylidene chloride, an optional copolymerizable monomer, and an .alpha.,.beta. ethylenically unsaturated silane crosslinking agent. The polymeric reaction product may also be used to form films and coatings. The composition further may include a volatile blowing agent which, when activated, expands the polymeric reaction product into a low density cellular structure.

Foamed shapes having an elongate cross-sectional configuration are prepared extruding with the major axis of the cross-sectional configuration of the die opening in a generally vertical plane, passing the extrudate to a shaping device having the desired elongate cross-sectional configuration which has its major axis in a generally horizontal plane. Improved extrusion rates are obtainable and the amount of blowing agent required to provide a given degree of expansion is reduced when compared to extrusion with the major axis of the extrusion die disposed in a horizontal plane.

Growing community of inventors

Midland, MI, United States of America

Kun S Hyun