Polyurethane Film Composition Viscosity Stabilization
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Solution Overview
Problem
Film-forming compositions containing polyurethane and thickeners face stability issues during storage, leading to a decrease in viscosity over time, making them too fluid and unusable for medical applications.
Innovation Solution
A liquid composition comprising a film-forming polymer derived from polyurethane, a thickener, and hydroxamic acid, with a dry matter content of 25-60% by weight, which stabilizes viscosity and provides resistance, adhesion, and elasticity when applied to tissues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a thickener is added to the film-forming composition to increase viscosity and improve texture, then the composition becomes too fluid over time during storage, making it unusable
Solution Approach 1:
The patent introduces hydroxamic acid as a new component that chemically interacts with the thickener to prevent its degradation over time. This changes the chemical parameters of the system, creating a stable complex that maintains viscosity without requiring excessive thickener concentration, thereby preserving usability during extended storage periods
2Stability of the object's composition
If the composition is made sufficiently thick to remain on the treatment area during drying, then it becomes difficult to apply uniformly
Solution Approach 1:
The composition exhibits dynamic rheological properties where the hydroxamic acid-thickener system provides shear-thinning behavior. During application, the composition becomes more fluid under shear stress, allowing easy spreading. Once applied and at rest, it rapidly regains higher viscosity to ensure film retention on the treatment area, thus resolving the contradiction between ease of application and film retention
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 composition maintains stable viscosity and forms a durable, uniform film with excellent resistance and adhesion properties, suitable for medical applications, even after prolonged storage.
Implementation Method 1
the optimal viscosity obtained during the formulation of the compositions tends to decrease over time, particularly during storage of the compositions which can last several months... the use of a hydroxamic acid to stabilize the viscosity of such a composition
Implementation Method 2
They are generally liquid upon application and conventionally contain a film-forming polymer dissolved in a volatile solvent, typically water or an alcohol. The evaporation of the solvent then allows the formation of a solid protective film.
Implementation Method 3
It is therefore often desirable to introduce into these compositions thickening agents capable of texturing the formulation, without however making it too solid
Implementation Method 4
a film-forming polymer capable of forming, on its own or in the presence of an auxiliary film-forming agent, a continuous and adherent film on a support, in particular on the skin
Data Source
AI summary
The invention relates to a film-forming liquid composition comprising a film-forming polymer derived from polyurethane present in the composition in a dry matter content of between 25 and 60 wt. % in relation to the total weight of the composition, a hydroxamic acid, the salts and/or complexes thereof and at least one thickener. The invention also relates to a film that can be produced from such a composition and to the use of hydroxamic acid for stabilising the viscosity of a composition comprising at least one film-forming polymer derived from polyurethane and a thickener.