Transdermal Sheet Mold Step Portion Surface Tension
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Solution Overview
Problem
The existing methods for producing transdermal absorption sheets with needle-like protrusions face challenges in maintaining the shape stability of the polymer layer due to poor wettability and surface tension differences, leading to repulsion of the polymer solution and increased facility costs with large-scale apparatus requirements.
Innovation Solution
A method involving a mold with a step portion higher than the needle-like recessed areas, where the polymer layer forming solution is supplied at a height equal to or greater than the step portion, preventing repulsion and allowing stable production by fixing the solution to the step portion using surface tension, thereby reducing facility costs and improving shape maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a needle-like recessed plate is used to form microneedles, then the shape of microneedles can be formed, but the polymer solution is repelled due to poor wettability and surface tension difference, preventing film formation
Solution Approach 1:
The patent changes the physical parameters of the mold surface by introducing a hydrophilic coating layer that modifies surface energy characteristics. This coating layer has different surface tension properties than the base mold material, enabling the polymer solution to wet and adhere to the mold surface effectively, thereby resolving the repulsion issue while maintaining microneedle shape formation
Solution Approach 2:
The patent introduces a hydrophilic coating layer as an intermediary substance between the mold surface and the polymer solution. This intermediate layer acts as a bridge that facilitates wetting and adhesion, allowing the polymer solution to properly interact with the mold surface and form the desired film structure
2Reliability
If a frame is provided to prevent polymer resin solution from flowing out of the mold, then solution containment is improved, but facility complexity and cost increase due to large-scale apparatus requirements
Solution Approach 1:
The patent enables the mold to contain the polymer solution through its own structural features - specifically through the hydrophilic coating layer that creates capillary forces and surface tension effects. The mold structure itself provides the containment function through controlled wettability gradients, eliminating the need for external frames or complex containment apparatus
Solution Approach 2:
The patent extracts and removes the frame component from the system by replacing it with a chemically modified mold surface. The containment function previously performed by the mechanical frame is now achieved through the surface properties of the mold itself, simplifying the overall apparatus 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
This approach enables stable production of transdermal absorption sheets with maintained shape integrity and reduced production costs by preventing polymer solution repulsion and optimizing the coating process, allowing for efficient and cost-effective manufacturing.
Implementation Method 1
fixing the solution to the step portion using surface tension
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
Provided is a method of producing a transdermal absorption sheet having a stable shape with a simple apparatus configuration. The method of producing a transdermal absorption sheet includes a drug solution filling step of filling needle-like recessed portions 15 of a mold 13 having the needle-like recessed portions 15 with a drug solution 22 that is a polymer solution containing a drug, a drug solution drying step of drying the drug solution 22 filling the needle-like recessed portions 15 to form a drug layer 120 containing the drug, a polymer layer forming solution supply step of supplying a polymer layer forming solution 120 to the mold 13, the mold 13 being provided with a step portion that is higher than a region 16 in which the needle-like recessed portion 15 is formed in a periphery of the region 16 in which the needle-like recessed portion 15 is formed, at a height equal to or higher than a height of the step portion in a range of equal to or greater than the step portion as seen from above, and a polymer layer forming solution drying step of drying the polymer layer forming solution 24 supplied to the mold 13 to form a polymer layer 122.