Spandex is polyurethane fiber with elastic properties used for sports wear, lingerie, swimsuits and undergarment. It goes under variety of names that depend on the trademark. DuPont call it Lycra, there are other fibers called elastane.
Spandex aka Lycra aka Elastane should be washed in warm water using mild detergent. Iron with care with low-temperature iron and do not hold the iron on one spot to prevent a damage of the material.