Urethane and Polyurethane Industry Glossary

TDI

A common symbol for tolylene diisocyanate, particularly the 80-20 isomer blend although it is sometimes used for other blends, Occasionally it is misused to represent any isocyanate bearing material, resulting in some confusion since many of the so-called 'crude or undistilled isocyanates' are not related to TDI at all other than by the attached NCO groups.

TMBDA

Is a symbol for one of the Amine catalysts used in foam formulations. The actual name of the catalyst is N,N,N1,N1- tetramethyl-l,3-butanediamine making it easy to understand why the symbol is used.

TMEDA

A symbol for one of the Amine catalysts used in foam formulations. The actual name of the catalyst is N,N,N1,N1- tetramethyl ethylenediamine.

TMG

A symbol for one of the Amine catalysts used in foam formulations, particularly rigid foam. The actual name of the catalyst is tetramethyl guanidine.

Tachometer

A device used to indicate the speed of some mechanism, usually the number of revolutions per minute of a pump or impellers. Under specified operating conditions, tachometer readings can be accurately related to flow rate. The combined information from tachometers, temperature gauges, pressure gauges, metering data, etc., provides the necessary background on which to base troubleshooting judgments. tachometer indicator-the dial or meter portion of a tachometer device that actually displays the information.

Tack-Free Time

The time between pouring the liquid mixture and the time that the surface of the foam can be touched with a spatula or a finger without sticking. This is a very difficult interval to relate positively to other factors since it is often influenced by environmental temperature and humidity. See also string time and rise time.

Tacky Surface

The condition of the surface of a foamed object, particularly free rise in the atmosphere, during which any object touching its surface will stick to the surface. This is normally a stage in the cure through which foams pass on their way to final cure. See tack-free time and string time.

Take-Away Conveyor

A name given to a conveyor on the discharge side of an in-line cutoff saw that is designed to take away the cut pieces of foam at a slightly faster rate than that of the main foam conveyor in order to prevent fouling the saw blade.

Tapered Impeller

A mixing blade or impellers characterized as having nonparallel sides coming closer together towards the discharge opening. Symmetrical impellers of this type could be called cone shaped with the inlet being the wide end of the cone and the outlet being at the narrow part of the cone. See straight sided impellers.

Tear Resistance

The ability of a piece of flexible foam to resist deepening a cut already made in the foam sample.

Technicalese

The special technical language often used by science or engineering trained personnel which has meaning only to others of similar training.

Temperature Conditioning

The process of bringing the object or surface to a specified operating temperature. It is normally used to indicate a passive operation such as storing drums of chemicals in a room with a controlled temperature between 70° and 75° F., allowing the chemicals to acquire the temperature of the room over a several day period, with no attempt at agitation of the drum contents. Foam samples prior to testing are temperature conditioned.

Temperature Indicator

That portion of a temperature sensing device that displays the information on a dial or meter.

Temperature Indicator-Controller

A combination of temperature sensing element, temperature display and thermostat. This is used for controlling the temperature of one of the urethane foam components in a metering system through control of the operation of a heat exchanger.

Temperature Stratification

The unmixed or layered condition often encountered in machine tanks without agitation, particularly the larger ones. Under some conditions warmer material returning to the tanks after passage through a heat exchanger will slide out on top of the cooler material without mixing, resulting in a warm strata at the top and a cold strata at the bottom. Under other conditions the warmer material will channel right through to the pump suction, leaving the bulk of the colder material in the tank and out of the flow circuit. tensile strength-normally expressed as the pounds per square inch of force required to stretch a foam sample to the breaking point. See elongation.

Tertiary Amine

An Amine catalyst of the type useful in urethane foam reactions, characterized by a molecular structure in which the nitrogen is directly connected to organic radicals only and not to hydrogen atoms as in ammonia. The tertiary Amines are generally more powerful catalysts than the primary or secondary types of Amines.

Testing Equipment

The equipment or devices necessary to carry out the Test Methods. It should be kept in mind that although some degree of testing is necessary for quality control, most of the tests necessary cannot be performed with any degree of Accuracy within two or three days of the production run of foam. In most cases this foam would already be distributed to the customers so that for practical purposes quality control starts with the foam production equipment and is directly dependent on it. Many manufacturers have so called 'quick tests' which they use to exAmine the uncured foam. These are relative rather than absolute but can be quite useful.

Thermal Conductivity

Ability of a material to conduct heat; physical constant for quantity of heat that passes through unit cube of a substance in unit of time when difference in temperature of two faces is 1 degree.

Thermal Froth

The production of a partially expanded fluid from the discharge nozzle of the mixer by means of heating the component(s) containing fluorocarbon 11 to levels far above the normal boiling point, while maintaining them under pressure from the tank through the mixing zone. The sudden reduction of pressure at the discharge nozzle allows the blowing agent to boil, and thus partially expand (or froth) the discharging liquid mixture. This is apparently a useful technique for working with high viscosity or high elastic component polyols that are otherwise difficult to keep mixed after discharge and prior to the cream time.

Thermal Gravimetric Analysis

The analysis of a foam sample by graphically recording the weight loss of the sample at different temperatures through the decomposition point or zone. See differential thermal analysis.

Thermoplastic

A material which is capable of softening or melting at elevated temperatures without degradation so that cooling of the material restores it to its original condition.

Thermoset

A material that is cured or transformed by elevated temperatures into a solid condition from which it does not change, upon reheating, until it reaches the decomposition point. Most urethane materials are thermosetting materials (e.g. flexible and rigid foams). Certain urethane elastomers and fibers are thermoplastic.

Thixotropic

Refers to the ability of a fluid to be jelly-like or semi-solid at rest, but reverting to a liquid on being agitated or stirred. Some degree of thixotropy helps a spray formulation to achieve greater thickness in a single pass.

Three Roll Paper Feed System

A system of paper supply for a slab foam conveyor consisting of a single bottom sheet of paper with two separate side sheets. The three roll type is usually tied in with a paper unrolling or removal system of the constant tensioning type. Although this system is more expensive than the single roll type, it usually pays for itself through fewer wrinkles and less foam damage. In addition there is greater freedom of paper supply when producing extremely wide Blocks of foam, since paper roll widths required are up to 4 or 6 feet less than that required for a single roll system. See paper handling device.

Throughput

A synonym for flow rate.

Throughput Control

The condition of being able to vary the flow rate or throughput of a metering machine.

Throughput Indicater

Any one of several devices that have been calibrated to have some direct relationship with flow rate such as tachometers, speed adjusting knobs, flowmeters, etc.

Throughput Rating

A term which applied to metering machines and mixing heads generally refers to the maximum flow rate that can be metered and mixed with all pumps at their maximum delivery or with some specified formulation. This can be a very misleading statement because of the diversity of formulation ratios for urethane foam. For example, a machine with maximum flow rate of 30 pounds per minute with a 50-50 ratio for a 2 component formula may only be able to deliver 15 to 16 pounds per minute of a total prepolymer formula with a 97/3 ratio. Under some conditions of extreme high viscosity the maximum flow rate may not be achieved within the pressure or pump suction limitations of the machine.

Throw Pillows

See decorator pillows.

Tin Catalyst

See organotin catalyst.

Tolerance

A specified allowance for deviations in weighing, measuring, etc., or for deviations from the standard dimensions or weight. Also applied to foam formulations. A formula is said to have tolerance if it can reproduce good quality product from day to day despite variations in raw materials, environmental conditions or small metering errors.

Tombstone Effect

A term used to describe a weakness that can occur in the joint area between multiple pours of foam in a single, usually thin, high rise cavity. The name comes from the characteristic shape of the joint shown in a vertical cross-section of the foam. Under certain conditions severe cracking can occur in this area during exposure to -15° F. temperatures.

Top Cracks

Cracks in the top surface of a foam slab that extend across the width of the conveyor. The edges of the cracks are widely separated and the inner surface of the crack is fairly smooth because they occur during a liquid phase. This is usually associated with undercutting. In contrast the edges of a split are usually close together and the inner surface is rough or jagged because they usually occur later during the final stages of polymerization.

Top Cure

The process of shortening the tack-free time of the top skin of continuous slab foam by heating it with radiant, steam or hot water heat. It is highly desirable that all tack (or tackiness) should be gone by the time the slab foam is cut, handled and stacked.

Top Cure Oven

The oven or device used to effect top curing of foam slab.

Top Splits

See flaps.

Topper Pads

Thin cushioning pads used as the top layer of an automobile seat to provide a good 'feel' to the seat.

Total Flow Rate

See flow rate.

Total Prepolymer

A urethane foam intermediate in which all of the isocyanate material is premixed with all of the polyol material and reacted under controlled conditions. To make foam this prepolymer is then blended with a catalyst mixture consisting of the water, catalyst and surfactant. The ratio between the total prepolymer and the catalyst mixture is about 97/3 or 95/5. See also prepolymer, modified total prepolymer, partial prepolymer and one shot.

Transfer Pumping

A term which generally refers to the method of filling the foam machine tanks or of keeping them filled. The most usual technique is to use air operated bung pumps installed in the chemical supply drums. These can be either manually valved at the machine tank or connected in conjunction with a level control device which automatically causes shut off of the transfer pump at the proper time. The term also is used to refer to the elaborate pumping network installed in the factories of large foam producers who buy their chemicals in bulk. The purpose of the network is to transfer the bulk chemicals to the proper machine tanks at the proper time.

Transportable

Another ambiguous term referring to movable equipment. See portable and movable.

Traveling Cut-Off Saw

See cut-off saw.

Traverse Mechanism

See spreader.

Triethylenedi Amine

The chemical name of one of the more common Amine type catalyst used to make urethane foam. It is one of the most active.

Trim

A term which refers to the small pieces of good quality foam that are removed from the crude Block of foam during converting operations. Trim consists of bottom, top, and side skins plus odd length or thickness leftovers. With proper management many profitable items can be manufactured from this trim material. See also scrap and crumb.

Trim Loss

The percentage of the total good foam produced that is not sold directly after the primary cutting operation but must be further cut or converted or reduced in price in order to be saleable. The percentage may be by weight or by volume. Trim losses as low as 3% and as high as 45% have been reported.

Triol

A polyol characterized by having three reactive hydroxyl (OH) groups attached to the molecule.

Two Phase Material

A term which generally refers to a composite material such as a fiber or pellet filled plastic or foam in which the composite has superior properties to either of the starting materials.

URETHANE INDUSTRY GLOSSARY - T

TDI