URETHANE INDUSTRY GLOSSARY - D

Is a registered trademark used for triethylenediamine, a very powerful Accelerator or catalyst of the tertiary Amine family. It is used as a highly selective blowing reaction catalyst for flexible foam and a more general catalyst for rigid foams.

See differential thermal analysis.

A slang expression generally meaning either Batch Tanks or machine tanks used for one day's production run. The tanks may not have to be very large as a 'daily' production run may be only 20 minutes long for some factories.

Small, variously shaped pillows, usually with bright colors, that are thrown onto chairs and sofas for color accent or general decoration. Also called throw pillows or occasional pillows.

The number of structural units or mers in the 'average' polymer molecule in a particular sample. In most plastics the DP must reach several thousand if worthwhile physical properties are to be had.

The time between pouring the liquid into the mold and the removal of the foamed article from the mold. This is usually kept to the minimum possible time in which the partially cured object can be handled without damage, since it is more economical to reuse the molds as quickly as possible.

The weight of a specified volume of material (foam). In some countries this is expressed as pounds per cubic foot; in others it is expressed as grams per cubic centimeter or kilograms per cubic meter.

The graph plotted from variations in density occurring in foam samples due to physical problems of heat loss, surface wetting, and shearing of foam during movement. Because of these factors, most foamed articles exhibit a variation in density from the outer skin into the geometrical center. When this variation is plotted on a graph, the result is a density profile shaped like the letter 'U'.

Is a powerful catalyst of the organotin group. See organotin catalysts.

Is a powerful catalyst of the organotin group. This is one of the best, but is, unfortunately, not destroyed by the heat of reaction. See organotin catalysts.

Is a powerful catalyst of the organotin group. It is sometimes used for rigid foam and for adhesives. See organotin catalysts.

The process whereby shaped foam articles are stamped out of a sheet of foam by the impact of a die against the sheet of foam. This can be done by an impact device hitting a steel-rule type die on an individual basis, or by a special roller die compressing the foam sheet against a cutting bar or roller on a continuous basis. This is a low cost method of providing very unusual shapes. Another name for this process is 'clicking'. The lowest cost dies for this type work are called 'steel rule dies' and consist of specially shaped, sharp edged steel straps imbedded in a wooden backing. See also clicking and clickable foam.

Is an examination technique whereby the foam may be heated to destruction while a temperature profile recording is being taken. This test assists the developmental chemists and engineers to better understand the behavior of foams during exposure to high temperature and flames.

Is one of the major chemicals used in the manufacture of urethane foam, particularly flexible foam and rigid prepolymer intermediates. Tolylene diisocyanate (TDI), which is currently the most popular one, is an Aromatic chemical having a benzene ring type structure and two isocyanate (NCO) groups attached to two of the six possible positions. The most commonly used type of TDI is a mixture with approximately 80% of the molecules having one of the NCO groups in the ortho position and one in the para position with the other 20% of the molecules having both NCO groups in the ortho position. One of the reasons for the warning against allowing this type material to freeze is that these two isomers will selectively separate during freezing, changing final foam properties if reacted partly frozen.

Is a term sometimes applied to a liquid that resists being moved but is quite fluid at rest. Some of the polyols used in the manufacture of urethane foam are not Newtonian (water- like) fluids and can be described by this term. They are characterized as being very difficult to handle, particularly at higher flow rates. The phrase 'high elastic component of viscosity' is also used.

A material used to extend or bulk up another material without changing the reactivity of the original material other than by the dilution occurring. The term is usually applied to fluids; whereas the words bulking agent, extender and filler are generally used with solids. This type material is also called 'liquid filler'.

Ability of a plastic part to retain the precise shape in which it was molded, fabricated, or cast.

A substance (comprising molecules) formed from two molecules of a monomer.

A polyol or resinous material having two reactive hydroxyl (OH) groups attached to each molecule.

The port or opening through which the chemicals are discharged. This term is usually restricted to the final discharge of the mixed materials rather than to intermediate points opening into the mixing chamber, which are normally called metering ports or metering tubes'.

The gradual yellowing of urethane foam due to a photochemical reaction occurring from the effect of certain wave lengths of light. It is faster in sunlight than in artificial light, although it occurs in both. At the moment there is no inexpensive method of prevention, although several methods are in use to retard the reaction and to lessen the final extreme of discoloration. It is possible to mask the reaction through the use of colorants. Occasionally fresh foam will discolor in the center of the Block for several reasons, one of which may be an excessively high internal temperature.

A term which on urethane foam equipment refers to a manifold arrangement used on continuous or non-recirculating systems for collecting the various component streams together to enter the mixing chamber. There is no valving in this type Block, although there may be valves in the feed lines.

A slang term used by some as a synonym for buckshotting.

Long lines of undesirable large bubbles rather close together and usually just under the top skin of Blocks of slab foam. They generally result from a combination of excessive channeling and too much air entrapped in the liquid deposited on the moving conveyor belt. The channeling tends to line up the bubbles and carry them under the foam front resulting in dribble marks. These unsightly chains of bubbles create a low tensile line at which tears or rips can easily initiate.

An accelerated aging test that helps to screen out formulations that may have a tendency to deteriorate too rapidly under certain climatic conditions. The foam samples are exposed to dry heat for varying periods of time as specified in ASTM Test Method D 1564-63T.

A term sometimes used to describe the stability achieved after all operating variables are in balance on a continuous slab foam production line, and the cream line and peak rise point remain at an exact point indefinitely.