Single-Material PET Closure Cap for Homogeneous Recycling

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Solution Overview

Problem

Recycling of beverage containers with mixed materials (PET bottle body and PE/PP closure cap) is complex due to separation requirements, leading to incineration instead of recycling.

Innovation Solution

A closure cap design that allows for injection molding without forced demolding, made from a single material like PET, ensuring the cap and bottle body can be recycled together without separation, using a mold with undercut-free cavities and linear displacement for easy removal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the closure cap is made from a different material (PE or PP) than the container body (PET), then the closure cap can be manufactured with suitable materials for sealing, but the recycling process becomes extremely complex due to material separation requirements

Engineering Contradiction:

Improvesealing performanceVSAvoidrecycling complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The closure cap is manufactured from the same PET material as the container body, merging the materials of both components. This eliminates the need for material separation during recycling, resolving the contradiction between achieving reliable sealing (through proper material selection) and simplifying recycling processes.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If the closure cap design includes features requiring forced demolding or spindle removal, then the cap can be securely attached to the container, but the manufacturing process becomes more complex and costly

Engineering Contradiction:

Improveattachment securityVSAvoidmolding process simplicity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Instead of designing the closure cap with features that require forced demolding or spindle removal, the invention inverts the approach by designing the mold cavity to be undercut-free, allowing the cap to be easily removed from the mold in the opposite direction of traditional designs. This resolves the contradiction between secure attachment and manufacturing simplicity.

Inventive Principle:

Principle #13The other way round (Inversion)

3Adaptability or versatility

If the mold cavity includes undercuts, then the closure cap can have more complex functional features, but the demolding process requires forced demolding or spindle removal

Engineering Contradiction:

Improvefunctional featuresVSAvoiddemolding process

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The mold cavity is segmented into two halves that can move relative to each other, allowing the closure cap to be formed with complex features while enabling easy removal by separating the mold halves. This resolves the contradiction between having functional features and simplifying the demolding process.

Inventive Principle:

Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Facilitates easy recycling of containers by eliminating the need for material separation, reducing production costs, and ensuring the entire container is homogeneously recyclable.

Implementation Method 1

a first mold half (21) and a second mold half (22) form a shaping cavity (23) in the closed state, in which the outer contour of the closure cap (2) is determined by the first mold half (21), in which the inner contour of the closure cap (2) is essentially determined by the second mold half (22)

Methodology Applied

Scientific EffectInjection molding:

Implementation Method 2

wherein a cavity part delimiting the engagement element (6) is defined by a mold part (22b) of the second mold half (22) and by a tip (21d) of the web (21a) of the first mold half (21), such that, when the cavity (23) is filled with plastic, the closure cap (2) comprising the cover disc (5) and the cap skirt (3) with engagement element (6) is produced, wherein the web (21a) also creates an opening (4) in the cover disc (5)

Methodology Applied

Scientific EffectPlastic flow:

Implementation Method 3

The two mold halves (21, 22) are linearly displaced relative to one another during opening, and the produced closure cap (2) is released and ejected, preferably without forced demolding

Methodology Applied

Scientific EffectLinear displacement: Displacement

Data Source

PatentEP4399162B1Closure cap, container comprising the closure cap and method for manufacturing a closure cap

Publication Date: 2025.10.01 CAPARTIS

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Figure 8~10

AI summary

The invention relates to a closure cap (2) comprising a closure cap axis (10), a cylindrical cap casing (3), a cover disc (5) and an engaging element (6) formed on the inner side of the cap casing (3) and projecting towards the closure cap axis (10), wherein the engaging element (6) is designed as an internal thread part or as a bayonet closure part, wherein the cover disc (5) has a through-opening (4) in the peripheral region thereof, and wherein the engaging element (6) is arranged below the through-opening (4) in the direction of the closure cap axis (10) relative to the through-opening (4).