Latex foam

L tex Foa.m Rubber. Latex foam mbber was the first ceUular polymer to be produced by frothing. (/) A gas is dispersed in a suitable latex 2) the mbber latex particles are caused to coalesce and form a continuous mbber phase in the water phase (7) the aqueous soap film breaks owing to... 

Latex mbber foams are generally prepared in slab or molded forms in the density range 64—128 kg/m (4—8 lbs/fT). Synthetic SBR latexes have replaced natural mbber latexes as the largest volume raw material for latex foam mbber. Other elastomers used in significant quantities are polychloroprene, nitrile mbbers, and synthetic i j -polyisoprene (115). 

Various geometric coring patterns ki polyurethanes (171,175) and ki latex foam mbber (176) exert significant influences on thek compressive behavior. A good discussion of the effect of cell size and shape on the properties of flexible foams is contained ki References 60 and 156. The effect of open-ceU content is demonstrated ki polyethylene foam (173). 

Latex foam mbber was initially accepted as a desirable comfort-cushioning material because of its softness to the touch and its resiUence (equal to that of a steel spring alone but with better damping quaUties than the spring). 

Cellular mbber has been used extensively as shoe soles, where its combination of cushioning abiUty and wear resistance, coupled with desirable economics, has led to very wide acceptance. In this case the cushioning properties are of minor importance compared with the abrasion resistance and cost. Other significant cushioning appHcations for cellular mbbers and latex foam mbbers are as carpet underlay and as cushion padding ia athletic equipment. 

Many different processes are patented for preparing latex foam but only two are of commercial interest for preparing molded cushioning stock the Dunlop, which is most widely used, and the Talalay processes. Some producers have developed variations, which are combinations of the two processes. 

The bulk properties of a polymer ean often be altered considerably by the incorporation of additives. Probably the most well-known examples of this occur in rubber technology where variations in the choice of additives can produce such widely differing products as tyres, battery boxes, latex foam upholstery, elastic bands and erasers. It is also possible to achieve variations as extensive as this amongst plastics materials, in particular with PVC from which rigid rainwater piping, baby pants, conveyor belting, footballs and domestic insulating flex may all be prepared. 

In suspension processes the fate of the continuous liquid phase and the associated control of the stabilisation and destabilisation of the system are the most important considerations. Many polymers occur in latex form, i.e. as polymer particles of diameter of the order of 1 p.m suspended in a liquid, usually aqueous, medium. Such latices are widely used to produce latex foams, elastic thread, dipped latex rubber goods, emulsion paints and paper additives. In the manufacture and use of such products it is important that premature destabilisation of the latex does not occur but that such destabilisation occurs in a controlled and appropriate manner at the relevant stage in processing. Such control of stability is based on the general precepts of colloid science. As with products from solvent processes diffusion distances for the liquid phase must be kept short furthermore, care has to be taken that the drying rates are not such that a skin of very low permeability is formed whilst there remains undesirable liquid in the mass of the polymer. For most applications it is desirable that destabilisation leads to a coherent film (or spongy mass in the case of foams) of polymers. To achieve this the of the latex compound should not be above ambient temperature so that at such temperatures intermolecular diffusion of the polymer molecules can occur. 

Today polyether foam with a density of less than half that of rubber latex foam is widely used as a cushioning material. Polyester foams, although tending to be more expensive, continue to have a number of outlets, particularly where a high initial modulus is desirable. In addition to miscellaneous upholstery applications... 

A method of manufacturing latex foam. Compounded latex is foamed and gelling agent added the mould is filled and the gelled foam vulcanised by steam at 100 °C the product is stripped from the mould, washed and dried. See Talalay Process. 

A product produced exclusively from a liquid base, e.g., latex. Latex foam has an interconnecting cell structure and is most commonly used for cushioning applications. Foamback... 

A substance which assists in holding the foam structure produced by whipping or frothing in the manufacture of latex foam rubber. 

The treatment of latex which is to be shipped as latex differs somewhat from that which is to be made immediately into dry rubber. For short-term preservation it is customary to add a small amount of an anti-coagulant to the tapping cups Where the latex is to be concentrated and shipped as such, much greater preservation is necessary and additional ammonia is added, up to about 0.7%. For latex foam manufacture most of this ammonia must be removed, and to eliminate the de-ammoniation operation several low ammonia latices have been developed. 

The principal branches of the latex manufacturing industry are latex foam and dipped goods. See Dipping, Casting, Adhesives and Rubberised Hair. 

A method of manufacturing latex foam. Compounded latex is partially frothed and fully expanded by application of vacuum to the mould the gel is frozen, set by carbon dioxide and vulcanised by raising the temperature of the mould. See Dunlop Process. 

Madge, E. W., Latex Foam Rubber, John Wiley Sons, New York, 1962. 

Large GMEF reclaimed reclaimed LDEM Latex foam ... 

No latex foam facilities are known to be in operation at this time. 

The production of foamed rubber by whipping a latex is known for a long time. Rubber mattresses are still being made in this way. The latex is whipped into a foamy substance and then poured into a mould. The water is evaporated, and the rubber is vulcanised with the aid of vulcanization ingredients (sulphur etc.) added before to the latex. The density of a rubber latex foam for mattresses is about 70 kg/m3. 

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