12th May 2021

#PLASTICPACKAGING: Recyclable cap with an innovative dosing mechanism

ALPLA has developed a cap for viscous liquids such as ketchup and mayonnaise which is made entirely of polypropylene (PP), making it optimally recyclable. Its innovative mechanism allows for controlled dosing and prevents unwanted dripping. The cap is compatible with standard bottles and can be produced cost-effectively.


Caps for viscous filling media like ketchup, mayonnaise and honey present manufacturers with certain challenges if they wish to meet the consumers’ requirements. Many of us are familiar with the experience of a ketchup bottle dispensing its contents onto our food too quickly and in too great a quantity, and then dripping too. Manufacturers have therefore been paying particular attention to the cap dosing system for years. Various materials are used here, but they are problematic in terms of sustainability. With its new controlled dosing cap (CDC), ALPLA presents a cap that makes an impression in terms of its handling, dosability and recyclability.

Made entirely of one material

Many commercially available caps made of PP feature a valve for more precise dosing which is made of an additional, easily mouldable material. This is usually silicone or a thermoplastic elastomer (TPE). This opens when light pressure is applied and the contents can flow out of the packaging. The valve then closes again when the pressure eases off. The disadvantage of this solution is that the use of a second plastic reduces the cap’s recyclability. With silicone, the PET or HDPE recycling streams are contaminated, which is why this type of cap is increasingly forfeiting market acceptance. In contrast, the CDC does without a valve. It is made entirely of PP and is 100 per cent recyclable in the interests of a functioning circular economy.

Innovative dosing mechanism

Another advantage of the CDC is its intelligent dosing mechanism. Whereas other monomaterial caps either simply do without a mechanism or feature elaborately produced moving parts, the CDC makes use of a simple mechanism and the laws of physics. Squeezing the bottle creates a pressure difference inside the bottle. The filling medium is 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 is no different to standard caps and meets all the market requirements. It is compatible with all standard bottles, allows for customer-specific adaptations and can be produced cost-efficiently.

  • Technology: IM
  • Material: PP
  • Cap: Screw cap with flip lid
  • Bottle mouth: 38-400 thread, compatible with standard bottles
  • Recycle: Fully recyclable in the existing recycling streams (no silicone, no TPE)
  • Usage which is familiar to the consumers
  • Controlled, uniform dosing and emptying without any dripping
  • Cost-efficient production, customer-specific adaptations possible
  • Standard cap which meets the market requirements

‘We at ALPLA have set ourselves the goal of making all of our packaging solutions fully recyclable by 2025. We firmly believe that recycling design is a key success factor on our way to establishing an effective circular economy. The controlled dosing cap is a 100 per cent recyclable cap made entirely of PP. It features a dosing mechanism which is both simple and intelligent that allows for very good dosability and effectively prevents the bothersome dripping of ketchup and other viscous contents.’

Maik Göpfert and Steffen Kroon, ALPLA Föritztal

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