Water-Soluble Unit Dose Films with Layered PVOH for Dissolution and Barrier Control
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Solution Overview
Problem
Water-soluble polymeric films used in unit dose articles often fail to completely dissolve under stressed wash conditions, leaving residue, and have inadequate barrier properties, leading to chemical migration and reduced consumer satisfaction, while also being challenging to manufacture with desired characteristics like cold water solubility, strength, and ease of production.
Innovation Solution
The development of water-soluble unit dose articles comprising multiple layers of polyvinyl alcohol (PVOH) polymeric films with specific molecular weight ranges and plasticizers, where each layer has distinct properties, such as varying water vapor transmission rates and tensile strengths, to ensure complete dissolution, prevent chemical migration, and enhance manufacturing simplicity through extrusion processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If water-soluble polymeric films are used to make unit dose articles, then consumer convenience and accurate dosing are improved, but the films incompletely dissolve under stressed wash conditions leaving residue
Solution Approach 1:
The film is segmented into multiple layers with different molecular weights and hydrophilicities. The outer layer has higher molecular weight for strength and barrier properties, while the inner layer has lower molecular weight for complete dissolution. This segmentation allows the film to maintain structural integrity during handling while ensuring complete dissolution during washing.
Solution Approach 2:
The patent changes the molecular weight parameter of the polyvinyl alcohol polymer across different layers. By using a gradient of molecular weights (higher in outer layers, lower in inner layers), the film achieves both mechanical strength for handling and complete solubility for dissolution, resolving the contradiction between reliability and ease of operation.
2Device complexity
If water-soluble polymeric films are used for unit dose articles, then packaging simplicity is improved, but barrier properties are insufficient allowing chemical migration
Solution Approach 1:
The patent uses composite film structures with multiple layers of polyvinyl alcohol with different molecular weights and compositions. This composite structure provides enhanced barrier properties that prevent chemical migration while maintaining the simplicity of a water-soluble packaging system, thus resolving the contradiction between packaging simplicity and preventing harmful chemical migration.
3Manufacturing precision
If solution cast processes are used to manufacture water-soluble films, then film properties can be controlled, but manufacturing time increases and productivity decreases
Solution Approach 1:
The patent replaces the solution cast process with an extrusion process. This substitution maintains the ability to control film properties through formulation while dramatically increasing manufacturing speed and productivity, as extrusion is a faster, more efficient process for producing water-soluble films with controlled characteristics.
4Strength
If higher molecular weight polyvinyl alcohol is used in films, then film strength is improved, but dissolution rate decreases leaving residue
Solution Approach 1:
The film structure is segmented into layers with different molecular weights. The outer layers use higher molecular weight polyvinyl alcohol for strength, while the inner layers use lower molecular weight for complete dissolution. This segmentation allows both strength and complete dissolution to be achieved simultaneously in different parts of the same film structure.
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 ensures complete dissolution of the films under various wash conditions, reduces chemical migration, improves consumer satisfaction by maintaining chemical effectiveness, and simplifies manufacturing by using extrusion processes that do not require water throughout the process, thus overcoming the challenges of residue, migration, and production complexity.
Implementation Method 1
Water-soluble unit dose articles made from a combination of water-soluble films
Implementation Method 2
Manufacturing water-soluble unit dose articles having good dissolution in various wash conditions, adequate barrier properties, and adequate strength can prove to be challenging for manufacturers. Common film-forming processes include solution cast and extrusion cast processes.
Data Source
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AI summary
The present disclosure relates to water-soluble unit dose articles made from a combination of water-soluble films and containing household care compositions that are at least partially enclosed by the water-soluble films in at least one compartment.