Custom breathable foam laminate composite for an orthotic appliance
Dal-Bac has been creating custom flexible foam laminate composites for over twenty-five years. Many of these composites utilize a foam substrate, of one type or another, to provide bulk, padding, stretch, air permeability or other important features. While we have worked with cross-linked polyethylene foams, polystyrene foams, vinyl-nitrile sponges, EVA sponges and other expanded polymers and elastomers. Our primary focus has always been low density, open-cell polyurethane foams. We work with grades, peeled or skived to a wide range of thicknesses, of polyether or polyester base, clickable or non-clickable, in soft to firm grades and in a range of densities, to meet the performance characteristics that our customers have come to expect of our laminates.
A not untypical project for Dal-Bac was the challenge to provide a padding composite for the design of an orthotic appliance. Our customer requested a foam laminate with specific technical fabrics laminated to opposite sides of polyurethane foam. The customer specified a foam laminate in a thickness of .375” that would have a firmness that he could not stipulate. We sampled a few foams with different ILD values (this is the unit of measurement that speaks to comparative firmness, or force to compress), and they replied with their selection.
For best value, given their design, they chose a fully clickable grade that would provide a uniformity of edge appearance without expensive trim sewing, but they expressed concern about the breathability of the foam laminate. The appliance they were manufacturing was to be worn for extended periods of time, and they did not want the patient to deal with too much sweat. We selected a grade that would be skived from flat stock to ensure a uniformity of cell structure through the cross-section, insuring optimum breathability.
Having chosen the appropriate foam core for their project, we addressed the requirements of the fabrics on each side. One was to be a hook-compatible knit loop fabric that would hold up to a moderate number of cycles – engagement and disengagement of the hook and loop components – so we offered a medium weight loop that could be dyed to their custom color. The fabric on the opposite side was to be in skin contact while the appliance was worn, so we had to deal with issues of comfort, breathability, wicking and bacterial growth. We met the requirements with knit polyester, that was given a faux suede surface condition for comfort, and had it treated for enhanced wicking and anti-microbial characteristics.
These three component substrates, now selected, were brought together into a foam laminate composite utilizing flame lamination – a cost effective lamination technique that requires no adhesive. The product was put up in bulk rolls of 58” effective width to allow the customer to die cut brace components, of various geometrical configurations and sizes, with a reasonable yield per linear yard. They continue to manufacture and successfully market this brace today, with the confidence that their padding components meet the demanding expectations of their customers.