A breakthrough in injectionstretchblowmolding technology lies behind the recent introduction of a new laundry product from procter & gamble. The new bottles are stretchblowmolded from preforms that are injectionmolded from polypropylene, a resin not usually associated with reheating and blowing preforms. Previously, these forms have almost always used pet. The stress crack resistance of a pet bottle is not the best if a product contains bleach or a high concentration of detergent. In addition, other household products contain hydrogen peroxide, which releases oxygen that can cause internal pressure to build in pet containers and deform them, producing an unsightly package on shelf. Pp, on the other hand, has passive venting properties because it&rsquos 30 times more permeable to gas than pet.
