pH-Dependent Polymer Films for Long-Wear and Easy Removal
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Solution Overview
Problem
Conventional cosmetic products either require frequent reapplication due to easy removal or are difficult to remove and may require harsh solvents, lacking a balance between long-wear and easy removability.
Innovation Solution
Cosmetic compositions utilizing pH-dependent film-forming polymers, such as poly(methacrylic acid-co-methyl methacrylate), which form durable films on the skin that are resistant to removal at acidic pH but become soluble and dispersible at higher pH, allowing for easy removal with soap and water.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional cosmetic products are formulated for easy removal with soap and water, then ease of removal is improved, but wear duration deteriorates (product is inadvertently removed by sweat and contact)
Solution Approach 1:
The patent applies parameter changes by utilizing pH-dependent polymers that change their solubility properties based on pH conditions. The cosmetic composition remains insoluble at skin pH (maintaining long wear) but becomes soluble at higher pH (enabling easy removal with soap and water). This resolves the contradiction by making the removal property dependent on a controllable parameter (pH) rather than a fixed characteristic.
Solution Approach 2:
The patent implements dynamics by creating a cosmetic film that dynamically responds to pH changes. The film transitions from a water-insoluble, adherent state during wear to a water-soluble state during removal. This dynamic behavior allows the same material to provide both long wear and easy removal, resolving the contradiction between these opposing requirements.
2Duration of action of moving object
If conventional cosmetic products are formulated for long-lasting wear, then wear duration is improved, but ease of removal deteriorates (requires harsh solvents or organic removers)
Solution Approach 1:
The patent uses parameter changes by formulating with pH-dependent polymers that remain insoluble at physiological pH (providing long wear) but become soluble at elevated pH levels achieved with mild soap and water. This eliminates the need for harsh solvents while maintaining long wear, resolving the contradiction between wear duration and ease of removal.
3Duration of action of moving object
If pH-dependent polymers are used to form durable cosmetic films, then wear duration is improved, but formulation complexity worsens
Solution Approach 1:
The patent addresses formulation complexity by selecting pH-dependent polymers with transition pH values above physiological pH (6.8-7.4). This allows the use of commercially available polymers with straightforward formulations, avoiding complex multi-component systems while achieving both durable wear and easy removal through the inherent pH-responsive properties of the polymer.
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 compositions provide long-wear cosmetic films that can be easily removed under mild, aqueous conditions, maintaining adhesion for extended periods while allowing for effortless removal, enhancing user convenience.
Implementation Method 1
a pH-dependant film-forming polymer capable of forming an adherent film on said integument that is substantially resistant to removal by water at a first pH, but readily dispersible or soluble in water at a second pH higher than said first pH
Implementation Method 2
readily dispersible or soluble in water at a second pH higher than said first pH
Data Source
AI summary
Cosmetic compositions are provided, which are capable of forming a cosmetic film on a human integument when applied thereto. Cosmetic compositions according to the invention typically include a cosmetically acceptable vehicle, optionally, one or more colorants, and a pH-dependant film-forming polymer of poly(methacrylic acid-co-methyl methacrylate) having a ratio of methacrylic acid to methyl methacrylate of about 1:1 to about 1:2, an acid value of from about 150 to about 350 mg KOH/g, and a weight average molar mass between about 100,000 and about 150,000 g/mol. The compositions are capable of forming an adherent film on the integument that is substantially resistant to removal by water at a first pH, but readily dispersible or soluble in water at a second pH higher than said first pH.