Abstract: A blown film process wherein: the temperature of the film is continually monitored in a select control or target area that is remote from the film frost line; a control of "target temperature" is determined based empirically or otherwise on a given set of companion operating conditions; and a variable film cooling source or supply is regulated to establish the control temperature as an essentially constant or non-variable operating condition. The process is characterized by an essentially stable frost line position and to the extent movement of the frost line can be optically or otherwise observed or sensed, and an appropriate signal derived therefrom, the process can be alternately practiced based on monitoring the position of the frost line, defining a control or "target" frost line position, and regulating a film cooling source responsive to deviances or movement from the control position.
Abstract: Low density, closed cell, soft foam products having dimensional stability are made from ethylenic resins having low stiffness, especially comprising copolymers consisting essentially of ethylene and monoethylenically unsaturated non-ionic comonomers, by release to lower pressure of a flowable, foamable gel under pressure, e.g., by extrusion foaming, wherein the gel comprises the ethylenic polymer and a volatile mixed blowing agent. The stating polymers are preferably copolymers of ethylene and vinyl acetate having stiffness less than about 20,000 psi. The mixed blowing agents are particularly characterized as mixtures of at least one fluorocarbon constituent I and at least one fluorocarbon constituent II, as defined. Exemplary mixtures contain (I) 1,2-dichloro-1,1,2,2-tetrafluoroethane and (II) from 25 to 50 percent chloropentafluoroethane, octafluoropropane or octafluorocyclobutane based on the mixtures of I and II.
January 27, 1977
Date of Patent:
July 18, 1978
The Dow Chemical Company
Chung Poo Park, Warren H. Griffin, John M. Corbett
Abstract: A railroad crosstie is constructed from at least two individually distinct rail support blocks interconnected by a web system which is fastened to the blocks and which comprises at least one self-supporting rigid sheet member adapted to be buried in the roadway ballast when the tie is in place. The blocks are selected to support and secure rails in conventional manner, and the interconnecting web system holds the blocks in relative position in the roadbed. The rigid sheet member adapted to be buried in the roadway ballast is advantageously disposed or provided with means such as horizontal longitudinal corrugations to interact mechanically with the particles of standard railroad ballast, whereby the tie resists being withdrawn from the roadbed.