What is Carpet Underlay? How is it made?
Polyurethane Foam (PU)
PU is particularly good at insulation and impact sound reduction, and is inherently comfortable.
It is also lightweight, making it easy to carry and fit.
So how is it made?
The foam used in PU underlay is either from offcuts or trimming from other processes, or are recycled after use such as furniture foam, so all of the foam is recycled in some way.
This foam is shredded and then granulated into smaller pieces.
It is mixed and coated with a binding agent before moulding into a large ‘log’ of a pre-defined density.
The log is subjected to steam under high pressure to cure the binding agent and bond the material together.
he log is then dried to remove residual moisture and peeled to a pre-defined product thickness.
During the lamination stage, backing and films are applied.
The underlay is then finished, trimmed, cut and rolled, and finally wrapped into branded polythene packaging.
Manufacturing of sponge rubber for Tredaire and Duralay ranges
Sponge rubber
Sponger rubber underlays are the most traditional form of underlay and have been around since the 1950s.
They are extremely comfortable; no other underlay produces quite the same feel underfoot.
They are also exceptionally good at minimising both impact sound and airborne sound between rooms.
They are incredibly flexible and cover more applications than any other type of underlay.
The manufacturing process
The styro butadiene synthetic rubber (SBR) is blended with oils, blowing agents and fillers to create the desired performance characteristics.
This is followed by a process called calendarising, where the mix is converted to a smooth and consistent paste.
Once the paste is ready it is rolled into a wide thin sheet, and this in turn is rolled onto a chain to produce the desired profile of either a ‘flat’ or ‘waffle’ underlay.
The sheet is then heated at temperatures up to 250˚c and blown, cured and allowed to cool. Finally it is trimmed, cut, rolled and wrapped into branded polythene packaging.
Manufacturing process of crumb rubber underlay products
Crumb rubber
Therefore being the number one choice for hard wearing, high traffic and very large areas.
The rubber comes from used car tyres, so the basic raw material comes from 100% recycled sources.
Every square metre of crumb rubber underlay contains the rubber of at least one car tyre!
The used car tyres are ground and processed to produce tiny crumbs. These are mixed with latex foam, and the mixture is then poured on to various types of backing material and the gauge or thickness of the underlay is set.
The underlay is then passed through a large oven, heated up to 250˚c and then cured and cooled.
Finally it is trimmed, cut, rolled and wrapped into branded polythene packaging.
Latex foam
It is not plastic foam like polyurethane, but is a denser product made of rubber.
Duralay Counterflame is made in this way and contains ATH which breaks down under heat to form water, giving the underlay a self-extinguishing property.
It is IMO certified flame retardant underlay.
The process
Synthetic latex in liquid form is mechanically frothed to create bubbles.
The frothed latex is then flowed onto a belt/roller system carrying the backing which guarantees strong adhesion as the contact happens in the wet phase.
The composite is then cured at a high temperature where excess moisture is also driven off.
The curing ovens create three rolls simultaneously which are trimmed, cut and wrapped.
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