Designing an Efficient Dispensing Package

The Opportunity

The customer came to PTI to develop an automatic soap dispenser for use in industrial/institutional restrooms. The company’s prior system featured a flexible pouch, but they discovered that the pouch would not fully evacuate, thereby wasting a significant amount of liquid soap and forcing more frequent servicing.

The ask was to develop both a 1 and 1.2 liter rigid PET containers which would be housed in a battery-powered dispensing unit. The containers needed to be flexible enough so that they would collapse at a specified millibar of vacuum and still evacuate all the contents. Because the critical performance attributes would be driven by the bottle design, they needed to develop that first, before moving on to the dispenser design.

The Innovation

Because the customer wanted to put a label on the front of the bottle that would show through the dispensing window, it was important that the bottle to collapse back to front, without also collapsing side to side. Through simulation and design iterations, PTI was able to guide the client toward a package that would collapse properly. During prototyping, PTI made a mold with multiple inserts which would allow the container volume to be changed, as well as depth of the rib that ran along the side of the bottle.

The end result was a reheat stretch blow molded bottle with side indentations which facilitate collapsing along that area and propagate through to the rest of the container. Because it is inserted inverted into the container with the finish at the bottom, the shoulders were rounded to help the liquid soap slope toward the neck. Also, because the bottle is wide, stretch blow molding into those base corners is challenging. To eliminate this problem, the corners were chamfered.

The Outcome

The new bottle design, coupled with the reheat stretch blow molding process, significantly reduced the client’s packaging costs for this particular application.