Tensionable Depilatory Article with High Modulus Substrate
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Solution Overview
Problem
Existing depilatory articles face challenges in achieving a balance between ease of handling and conformability to the body surface, with flexible substrates collapsing or stretching, leading to poor contact with hair and potential irritation, while rigid substrates lack conformability and result in unsatisfactory hair removal.
Innovation Solution
A depilatory article with a flexible substrate having a high secant modulus and nominal tensile strength, equipped with finger-tabs to apply tension and maintain rigidity, ensuring accurate placement and uniform composition application, and a water-impermeable layer to prevent drying and irritation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a flexible substrate is used for the depilatory article, then conformability to the body surface is improved, but the substrate may collapse during handling and be difficult to accurately place on the unwanted hair
Solution Approach 1:
The substrate is divided into a coated region containing the depilatory composition and at least two finger-tabs that are substantially free of depilatory composition. This segmentation allows the user to hold and position the article using the finger-tabs without direct contact with the composition, enabling accurate placement while maintaining flexibility for body contour conformability.
Solution Approach 2:
The substrate is designed as a flexible yet tension-resistant structure that can conform to body surfaces. By incorporating finger-tabs and controlling the substrate's mechanical properties (secant modulus and nominal tensile strength), the article maintains structural integrity during handling while adapting to curved body contours during application.
2Ease of operation
If an excessively rigid substrate is used for the depilatory article, then ease of handling is improved, but the article lacks the capability to be conformed to the area of the body upon which there is unwanted hair
Solution Approach 1:
The substrate uses a flexible material with controlled mechanical properties (specific secant modulus and nominal tensile strength ranges) that provides a balance between handling ease and conformability. The flexibility allows the article to adapt to body contours, while the controlled rigidity prevents excessive deformation during application.
Solution Approach 2:
By separating the coated region from the finger-tabs, the design allows the non-coated finger-tabs to provide structural support and handling capability, while the coated region maintains flexibility for body contour adaptation. This functional segmentation resolves the contradiction between rigidity for handling and flexibility for conformability.
3Adaptability or versatility
If a flexible substrate is used for the depilatory article, then conformability to the body surface is improved, but the substrate may stretch under tension, thus altering the thickness of depilatory composition upon the substrate
Solution Approach 1:
The substrate is engineered with specific mechanical properties (secant modulus greater than 1379.0 bar at 2% strain and nominal tensile strength of at least 5 MPa) that provide high tension resistance. This prevents stretching and maintains uniform composition thickness even when the flexible substrate conforms to body surfaces, ensuring consistent depilatory performance without excessive composition transfer to the skin.
Solution Approach 2:
The substrate's mechanical parameters (secant modulus and nominal tensile strength) are optimized to specific ranges that balance flexibility for conformability with resistance to stretching. This parameter control ensures the substrate can adapt to body contours without deforming the depilatory composition layer, maintaining thickness uniformity and preventing skin irritation from excessive composition transfer.
4Ease of operation
If the depilatory composition is applied directly to the skin without a water-impermeable layer, then ease of application is improved, but the composition may dry out and cause irritation
Solution Approach 1:
A water-impermeable layer is incorporated into the substrate structure to prevent the depilatory composition from drying out during application. This protective barrier maintains the composition's moisture and chemical stability, preventing skin irritation while allowing easy application of the article to the treatment area.
Data Source
Figure 1~2
Figure 3
AI summary
A depilatory article comprising a flexible substrate partially coated with a depilatory composition, the coating of depilatory composition forming a coated region of the depilatory article, wherein the depilatory article comprises at least two finger-tabs being substantially free of depilatory composition and positioned on substantially opposing sides of the coated region, and wherein the flexible substrate has a secant modulus at 2% strain of greater than 689.5 bar (10,000 psi), more preferably greater than 1379.0 bar (20,000 psi), even more preferably greater than 2068.4 bar (30,000 psi) and even more preferably still greater than 2757.9 bar (40,000 psi).