Specific materials in modern disposable diapers are designed to control the main factors which cause diaper rash.
Materials Used in Diapers
| Material | Where Used in Diapers |
|---|---|
| Polypropylene (PP) | Primarily used for the topsheet, the part of the diaper next to baby’s skin, tapes and fastening system |
| Polyethylene (PE) | Primarily used for the backsheet, the outer cover, tapes, and fastening systems |
| Cellulose fluff pulp | Absorbent core and core tissue |
| Superabsorbent polymer | Absorbent core |
| Elastics | Along leg opening and waist to improve fit. |
| Adhesives | Throughout the diaper to bond various other materials together |
Superabsorbent Polymers
Historically, diapers used fluff pulp, made of cellulose derived from wood, as the sole absorbent material in the core. Fluff pulp was good at absorbing wetness, but not good at keeping it away from the baby’s skin. It is also easily saturated, making it unable to absorb additional urine.
Today, superabsorbent materials are used in most of the diapers sold throughout the world. These superabsorbent polymers can absorb from several tens to several hundred times their weight in fluids. Typically 1 gram of superabsorbent material in a diaper can absorbs at least 35g of urine. By contrast, 1 gram of pulp absorbs approximately 10g of urine.
A small amount of modified fluff pulp is used in the diaper core to initially absorb the urine, and pull it into to the polymer material for final storage. Once absorbed the wetness cannot be squeezed back out towards the skin by the pressures exerted by a sitting or moving infant. Over time, superabsorbent materials have been designed to absorb more urine and absorb it more quickly, minimizing the time that wetness contacts the skin.
Topsheets
The topsheet is the layer that comes in contact with the child’s skin. It is specially designed to quickly pass fluids through to the superabsorbent layer, while remaining soft and dry to the touch. Some topsheets may include a lotion, similar to those found in diaper skin-care products, to further protect the skin from over-hydration and irritation.