PVOH Film Blend for Stronger Cold-Water Dissolving Unit Doses
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Solution Overview
Problem
Water-soluble unit dose articles using polyvinyl alcohol films face issues with premature rupture during storage and transport due to insufficient strength, and delayed dissolution and residue formation in cold water due to gelling with detergent, especially in short cleaning processes.
Innovation Solution
A water-soluble film comprising a blend of two PVOH homopolymers with specific viscosity and hydrolysis ranges, along with optional additives, to enhance strength and dissolution performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single PVOH film is used to provide sufficient strength for storage and transport, then the film strength is improved, but the dissolution speed deteriorates due to gelling with detergent in cold water
Solution Approach 1:
The patent applies composite materials by creating a film from a blend of two different PVOH homopolymers with distinct viscosity characteristics. The first PVOH homopolymer (higher viscosity: 10-40 cP) provides film strength and structural integrity, while the second PVOH homopolymer (lower viscosity: 3-20 cP) ensures rapid dissolution and prevents gelling. This composite approach allows the single film to simultaneously achieve both high strength and fast dissolution performance that neither polymer could achieve alone.
2Speed
If the film dissolves rapidly in cold water, then the dissolution speed is improved, but the film strength deteriorates leading to premature rupture
Solution Approach 1:
The patent resolves this contradiction by formulating a composite film system where the lower viscosity PVOH homopolymer (3-20 cP) contributes to rapid dissolution and the higher viscosity PVOH homopolymer (10-40 cP) contributes to film strength. The synergistic interaction between these two polymers in the blend allows the film to maintain adequate strength during storage while dissolving rapidly upon contact with water, eliminating the need to choose between these opposing properties.
3Productivity
If the film interacts with detergent during initial dissolution, then the cleaning action is initiated, but gelling occurs that slows down further dissolution and leaves residues
Solution Approach 1:
The patent uses the lower viscosity PVOH homopolymer as an intermediary component that mediates between the detergent and the higher viscosity PVOH homopolymer. This lower viscosity polymer facilitates initial wetting and detergent penetration into the film matrix, preventing the formation of a gelled barrier that would otherwise block further dissolution. By controlling the interaction dynamics, it enables continuous dissolution and complete disintegration without residue formation.
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 film blend provides adequate strength for storage and transport while ensuring rapid dissolution without residue formation, even in cold water, maintaining cleaning efficiency.
Implementation Method 1
When the water-soluble unit dose article is added to water, the film dissolves/disintegrates releasing the internal contents into the surrounding water to create a wash liquor
Data Source
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AI summary
Water-soluble films, water-soluble unit dose articles, and methods of their manufacture and use. One type of film includes a polyvinyl alcohol resin blend comprising a polyvinyl alcohol resin blend comprising a first PVOH homopolymer consisting essentially of vinyl alcohol monomer units and vinyl acetate monomer units and a second PVOH homopolymer consisting essentially of vinyl alcohol monomer units and vinyl acetate monomer units,