URETHANE INDUSTRY GLOSSARY - C

The common abbreviation for the cubic centimeter of the metric system. For liquid measurement the abbreviation ml (milliliter is often used in place of cc. The two measurements are approximately equal.)

A common abbreviation for Compression-Deflection curve.

An abbreviation for cubic feet per minute.

The abbreviation for centipoise.

The abbreviation for cycles per second. A recent international decision suggests the use of HERZ instead of CPS with reference to electrical wave motions. CPS is satisfactory for mechanical cycles.

The chemical symbol for carbon dioxide.

Foam in which all of the gas for expanding or blowing is carbon dioxide, generated by the chemical reaction between water and the isocyanate material. This type foam is called 'water blown foam'.

A synonym for metering, referring to the weighing of carefully timed amounts of chemicals from the dispensing ports of the mixing head in order to set an exact ratio of flow rates between each component or to set an exact total

A term used to describe the filling of small molds with liquid, nonfoaming formulations of urethanes or other types of polymers, sometimes called solid elastomers or casting resins. Occasionally used to describe the potting of electrical or mechanical parts in foam.

Foam made from a formula in which the major polyol ingredient is derived from castor oil.

Technically, a chemical that has the property of being able to change the speed of a chemical reaction without apparently taking part in the reaction. Most of the so-called catalysts of urethane form reactions do have some part in the reaction and consequently do not fall under the proper definition, although they are often referred to by that name. (See Accelerator.)

A device used to surround a catalyst metering tube with a compressed air flow in order to prevent unwanted accumulation of foam around the port that could interfere with the flow of the liquid.

The ratio between the Amine catalyst and the organotin catalyst. See reaction balance.

A shortened form for catalyst mixture. Most formulations require delicate balancing between the blowing and gelation reactions, and consequently blends of different types of catalysts are often used together with an inert carrier or diluent to aid in metering accuracy or in miscibility.

A synonym for catalyst mix.

Is synonymous with bubble or pore. It refers to the cavities left in the foam structure after the bubble walls have completely polymerized and solidified or curled back and fused into the boundary joints to form a skeletal structure. Cells can be closed (intact walls) or open (skeletal ribs only). Cell shape is more like an irregular polygon than a globe.

The number of cells or bubbles per linear inch or per centimeter. Cell count is very important to the physical properties of foam. See cell size.

The thin intact film that forms the bubble walls in closed cells, also called windows.

A term which refers to the average diameter of the pores (bubbles) in the filial foam product. Although often still referred to as fine, medium or coarse, or by the diameter in microns, most workers refer to the number of cells per linear inch (cell count).

(See cell size) A term often used to point out overall uniformity of foam cell diameter. Example, 'uniform cell structure' describes foam with generally equal cell diameters.

A plastic with numerous cells disposed throughout its mass. The terms cellular, expanded, and foamed plastic are used synonymously. A cellular plastic may be produced by (1) incorporating a blowing agent which decomposes to liberate a gas; (2) mechanically stirring in a fluid or gas; (3) adding a water soluble salt or a solvent extractible agent to the mix prior to foaming then leaching out the agent after foaming to leave voids; or (4) other techniques.

1/100th of a poise, commonly used in describing the viscosities of the various chemical components in urethane foam. Although many formula viscosities are less than 2000 centipoise, some individual components may have viscosities as high as 100,000 to 200,000 centipoise. See poise.

Is the lengthening of the spine or main chain of polymer molecules by end to end attachment usually involving condensation of functional groups between two or more molecules during the chemical (polymerization) reaction. Cross linking, a side to side attachment of molecules, also occurs during polymerization. Some physical properties are enhanced more by chain extension, others by cross linking.

A small scale or narrow undercutting of the expanding or rising foam front by a stream of the mixed clear liquid. This is usually due to wrinkles in the paper or uneven distribution of the liquid. Channeling often results in high density ridges on the bottom of the foam Block referred to by some as bones and others as striations or flow lines. Occasionally the term is used to refer to the condition arising when a heated portion of a viscous liquid is recirculated back into a tank without agitation, flowing immediately to the inlet of the pump without mixing with the cooler liquid.

A term occasionally used to describe the process of filling the machine tanks with the various quantities of chemicals.

The disks and flanges used to separate the foam ingredients from the operating mechanism, usually of a pressure gauge. The interior of the bourdon tube or bellows is filled, under vacuum conditions, with an inert fluid, up to the back side of the metal disk or diaphragm. This combination of liquid and membrane effectively isolates the mechanism without affecting Accuracy.

A heat exchanger used for cooling the chemical materials. Scraped surface, tube and shell, and plate type exchangers are all used, with the scraped surface being the most efficient, particularly with the higher viscosity materials,

A heat exchanger used for cooling the material but including the cooling source. It usually consists of a scraped surface, tube and shell, or plate type heat exchanger plus a refrigeration compressor and controls. The package unit may be a direct expansion type in which the refrigerant expands directly into the main heat exchanger or it may be of the liquid transfer type in which the refrigerant gas expands into an intermediate heat exchanger, and then a circulating liquid is used to conduct the heat from the main heat exchanger. See cooling media.

A term sometimes used to describe the in-line type cut-off saw, and sometimes used to describe a device used to cut or chop urethane foam trims into small pieces for rebonding, stuffing toys, pillows, etc. See crumb.

A special type chemical seal permitting cleaning of the chemicals side of the disk without complete disassembly. See chemical seal.

Foam that recovers 100% from the pinching effects of clicking.

The process of stamping out irregular shaped articles from thin sheets of foam by means of a hammering mechanism and a steel-rule die. See die cutting.

Is the property of a foam of having each individual bubble completely sealed off from its neighbor so that no exchange of gas can take place except by diffusion through the walls, With rigid foams, it is usual to try for 100% closed cells to achieve maximum thermal insulating ability and minimum water pickup. With flexible foams, it is normal to try for 100% open cells for maximum flexibility, resilience, and breathability even to the extent of achieving a true skeletal foam in which even the broken membranes between cells have been removed or fused back into the ribs."

The practice of molding a foam object in a cavity in which the foaming liquid is 100% contained with only gas being allowed to escape.

Very large bubbles averaging not over 20 to 30 cells per lineal inch. See cell size.

The process of flexible foam molding in which the molds are maintained at temperatures between approximately 100° F and 150° F as compared with the alternate "one shot" molding technique in which temperatures of 250° F to 350° F are obtained within one minute of pouring. Flexible prepolymer molding normally has utilized temperatures in the "cold molding" range.

The sudden or complete loss of height occurring after the foam has partially or completely expanded. Under extreme conditions, the foaming chemical mixture may not expand at all but may merely boil violently and then harden into a solid sheet. See boiling.

A dye or pigment used to color the foam for appearance, identification, or for other sales purposes. Occasionally a necessary minor ingredient may act as a colorant.

A term normally used by those interested in continuous slab processing and referring to all of the equipment required to make a product. This comprehensive list generally includes the paper handling equipment, chemical handling equipment, the foam machine, the conveyors, the spreading or traversing device, curing devices or ovens, cutting equipment and packaging equipment. Testing equipment and technical service may or may not be included.

A term used to describe a separately metered stream of liquid that will be directly introduced into the mixing head for the final mixing. Although as many as 11 or more chemical components may be used in a formulation, these may be preblended into as few as two components for the final formulation used in the machine. See number of components.

The determination of the resistance to compression of a foam sample when the entire area of the sample is compressed. This Test Method is described in ASTM.

An industry expression used to describe the recovery of foam from static or fixed compression. Less than 10% compression set (which is greater than 90% recovery) is usually accepted as good. Also called 'percent set.' This Test Method is described in ASTM D 1564-63T.

A term primarily used to describe the resistance of rigid foam to compression. This test method is described in ASTM D 1621-59T.

A mixing device capable of dispensing homogeneously mixed material continuously, without affecting the temperature or pressure of the mixture by virtue of its continuous operation. The individual components may be valved as in the 'on-off' mixing heads, but are not required to be. Instantaneous start and/or stop of all components is not essential, although desirable.

The production of a continuous, homogeneous, seamless loaf of urethane or other foam by laying down a uniformly distributed liquid film of mixed materials on a conveyor belt moving beneath the mixing head at such a rate of speed as to form a stable rising front of foam. The process may only last for a few minutes, or it may run for 24 hours per day depending on sales requirements.

A method of foam production in which the mixed material being discharged from the mixing head is a clear liquid. This term is used to differentiate between non- frothed (conventional) and frothed systems of production.

A term which refers to the process of cutting and shaping used to convert bread loaf shaped slab foam Blocks into saleable items.

An endless loop of material, either metal, cloth, rubber, or paper, used to carry the expanding foam mixture in the manufacture of continuous slab foam. The types are usually further described as 'linked metal', 'slat type metal', 'rubber' (even when fabric reinforced), 'cloth', 'cotton', or 'canvas belt'.

The splitting of a sheet of flexible foam while it is variably compressed so that two matching pieces of foam are created, each with alternating patterns of hills and hollows on their adjacent sides. The main advantages are that the foam can be made softer and more resilient mechanically and that two pieces of foam are produced, each of which is almost as thick as the original piece.

The material that carries the heat away from the chemicals. In the direct expansion type of heat exchanger, the refrigerant gas is the cooling medium; in the liquid transfer or 'brine' cooled type of heat exchanger, the 'brine' is the cooling medium for the chemicals and the refrigerant gas is the cooling medium for the 'brine'. In most modern cases, a solution of ethylene glycol permanent anti-freeze is used for the 'brine' solution rather than the salt solution. See chiller package.

The density of the foam at the center of the foam object. In most cases, foam will form a density gradient in an object with the highest density being at the outer or skin surfaces and the lowest density being in the center or core of the object.

Long narrow openings or cavities in the foam Block that have widely separated and relatively smooth sides. These are subdivided into side cracks, top cracks and pocket blows (internal cracks) for trouble shooting purposes. See the specific headings for more detailed descriptions.

The condition in which the top surface of the continuous slab of foam resembles a photograph of the surface of the moon. It is normally caused by entrapment of very large gas bubbles that may have originated in the mixer or developed from excessive lay down splashing or possibly liquid undercutting (channeling) the foam front.

Globules which may pop to the surface of the foam front under certain conditions of flexible slab foam manufacture. The balls may race madly down the slope of the rising foam front or dash erratically around on the surface or just beneath the surface of the rising foam.

The point on a continuous foam slab conveyor where the clear mixed liquid becomes cloudy and begins to expand. When streamers are present, they extend upstream from the cream line into the clear material. When all variables have been stabilized during a production run, the cream line will remain at a fixed distance downstream from the mixing head.

A time interval defined somewhat differently between a laboratory batch or hand mix and a production machine mixer. The laboratory or batch type mixing definition is usually 'the time between the start of the final mixing and the point at which the clear mixture turns creamy or cloudy and starts to expand'. With the machine mixing process the cream time is generally taken to be 'the time between the first material being poured until that material turns creamy or cloudy'. Occasional misunderstandings arise over this and over the occasional practice of labeling the time between final mixing and the start of creaming or foaming as 'cream time' for laboratory or Batch Mixing when it could more properly he termed 'liquid handling time'. The problem results from the fact that laboratory type mixing requires as much as 100 times more mixing time than machine mixing. "Frothing" masks the cream time but usually extends the overall 'handling time'.

The dimensional change with time of a material under load, following the initial instantaneous elastic deformation, Creep at room temperature is sometimes called Cold Flow.

Applied to polymer molecules, the setting-up of chemical links between the molecular chains. When extensive, as in most thermosetting resins, cross-linking makes one infusible super-molecule of all the chains.

A term used by the furniture industry to describe a mattress or cushion that is thicker in the middle than it is at any edge. This is much easier to achieve with molded articles but can be achieved for slab produced articles with the use of special cutting or abrading machines.

Is a term sometimes used to describe an undistilled isocyanate mixture containing several different polymeric isocyanates. These mixtures are ordinarily a dark brown in color as opposed to the clear water white color of distilled TDP. Some chemical manufactures object to the description 'crude' and consequently many prefer the term 'polymeric' isocyanate or 'undistilled' isocyanate.

A term used to describe very finely divided pieces of flexible urethane foam that have been shredded, ground, milled or torn from flexible foam trims or scraps.

A common metric measure of volume developed from lineal measurement. There are approximately 16.4 cubic centimeters in a cubic inch. The liter is a preferred volumetric measurement, particularly liquids. One milliliter (ml) is approximately equal to 1cc.

A common measure of volume in the English System. This is a cube with length, width and height all equal to 1 foot. There are 1,728 cubic inches in a cubic foot. See cubic centimeter.

A common measure of volume in the metric system developed from lineal measurement. This is a cube with length, width, and height all equal to 1 meter. Since there are 100 centimeters in a meter, there would be 1 million cc's in a cubic meter. There are approximately 35.3 cubic feet in a cubic meter. A meter is approximately 39.4 inches in length.

A term which refers to the completeness of the chemical reaction. At 100% completion, the foam should have 100% of the maximum physical properties attainable with that particular formulation used. Because 100% cure is not always reached in a practical length of time, some arbitrary time- temperature period is usually assigned to a particular formula to designate a practical level of cure at which testing for physical properties may be started. See cure time.

The final oven into which foam articles are placed in order to achieve the desired final level of accelerated cure. The term is sometimes ambiguous in normal use and is usually qualified with a prefix or another word to make it more specific, such as pre-cure or post-cure.

The time required to achieve a specified level of cure. See pre-cure, post-cure and handling time.

Any type of panel that is hung on the outside of a building to form the exterior skin of the building, without bearing any structural load other than that which itself generates, sandwich panels with a foam core are often used in this type application.

A special type of foam cutting saw that is used to make vertical cuts. The traveling cut-off saw is used to make cuts on a continuous slab line in a direction across or perpendicular to the direction of foam movement, while the foam is moving. The stationary cut-off saw is used to cut long slabs into shorter slabs while the foam slab is stationary. This type of cutter is normally a special band saw, having the blades twisted 90" from the plane of the wheel surfaces in order to avoid interference problems with the saw wheels or the other portion of the blade. Another version of this type saw is based on the vibrating bayonet type of blade.