Water-Soluble Capsule Curved Sealing Web Prevents Drooping
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Solution Overview
Problem
Multi-compartment water-soluble detergent capsules with flat sealing webs are prone to drooping, leading to handling issues and leakage, and existing solutions either complicate manufacturing or compromise film thickness, affecting segregation and dissolution efficiency.
Innovation Solution
A unit dose capsule with three compartments formed from two sheets of water-soluble film, featuring a sealing web with a peripheral skirt and inter-compartment sealing webs, maintaining an average surface extension ratio of 1.5 to 3 to prevent breakage and leakage, and ensuring rapid and complete dissolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If multi-compartment capsules use flat sealing webs to separate compartments, then manufacturing is simplified, but the capsule becomes floppy and folds along the seal causing drooping and handling problems
Solution Approach 1:
The sealing web is transformed from a flat configuration to a curved configuration that follows the contour of the capsule. This curvature prevents the sealing web from folding along flat lines and eliminates drooping, while the capsule is manufactured using conventional thermoforming processes.
2Shape
If multi-compartment capsules use stacked configuration to prevent seal folding, then capsule stability is improved, but manufacturing complexity increases and triple layer seals cause dissolution problems
Solution Approach 1:
The sealing web is configured to curve along the capsule contour rather than forming flat seals or stacked triple-layer structures. This single curved sealing approach provides stability without increasing manufacturing complexity or creating dissolution issues associated with multiple film layers.
Solution Approach 2:
The problematic triple-layer seal structure is eliminated entirely. Instead of stacking multiple capsules or layers to prevent folding, the invention uses a single curved sealing web that inherently prevents folding while maintaining simplicity.
3Area of stationary object
If film thickness is reduced to accommodate triple layer seals, then seal area is increased, but leakage due to pin-holing increases
Solution Approach 1:
The curved sealing web configuration allows for adequate seal area without requiring triple-layer construction. This enables use of sufficient film thickness to prevent pin-holing and leakage while maintaining appropriate seal coverage.
4Ease of manufacture
If single thin layer of polyvinyl alcohol film is used to separate liquid compartments, then manufacturing is simplified, but ingredient segregation is compromised
Solution Approach 1:
The curved sealing web provides enhanced separation between compartments compared to flat seals. The curvature creates a more effective barrier that maintains ingredient segregation while using a single layer of film, preserving both manufacturing simplicity and composition stability.
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
The solution enhances handling and in-use performance by preventing drooping and leakage, ensuring efficient dissolution and dispersion of the detergent composition, while minimizing film residue and improving cleaning efficacy.
Implementation Method 1
water-soluble film
Implementation Method 2
heating the film to soften it
Implementation Method 3
application of vacuum to hold the film in the moulds
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The present invention provides a unit dose capsule (101) for treatment of a substrate, the capsule (101) comprising three compartments (102, 103, 104) containing a substrate treatment composition, wherein: the capsule (101) is formed from two sheets of water-soluble film, the two sheets of film being sealed together forming a sealing web lying on a sealing plane, the sealing web comprising a peripheral sealing skirt (108), inter-compartment sealing webs (1024, 1023, 1034) between compartments thereby separating the compartments from one another and a central sealing web (10234), wherein wherein the compartments have an average surface extention ratio in the range of 1.5 to 3, the surface extension ratio is the surface area of the film above the sealing plane to surface area of footprint the compartments located in the sealing plane.