Austrian packaging expert Alpla has developed a valve-less polypropylene (PP) screw cap with a flip lid for viscous liquids, such as ketchup, mayonnaise and honey. The fully recyclable cap allows for controlled dosing and prevents unwanted dripping when dispensing contents too quickly or in too large quantities.
The cap is also compatible with standard bottles and can be produced cost-effectively. Alpla highlights many commercially available PP caps contain a valve for more precise dosing made from an additional, easily mouldable material – typically silicone or a thermo-plastic elastomer.
Standard caps open when light pressure is applied. The valve then closes again when the pressure is released. Alpla’s new dosing mechanism employs the laws of physics for controlled squeezing.
Squeezing the bottle creates a pressure difference inside the bottle. The bottle’s contents are diverted into a screw within the cap, which it has to pass before making it to the opening.
At the same time, high negative pressure is created. When the pressure on the bottle is reduced, there is pressure compensation, and the content is drawn back in by the suction effect without dripping. The principle is similar to that of a drinking straw.
The cap retains a similar design as standard caps and meets all the market requirements. It allows for customer-specific adaptations and can be produced cost-efficiently.