Adhesive Patch Viscoelastic Modulus and Methyl Salicylate Balance
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Solution Overview
Problem
Conventional adhesive patches containing methyl salicylate face issues with poor adhesion and skin irritation, leading to difficulties in maintaining continuous application and effective drug delivery, especially when applied to joints that undergo twisting motions.
Innovation Solution
An adhesive patch with a stretchable support made of woven fabric and an adhesive layer containing 25-50% liquid organic ingredient, 10-50% thermoplastic elastomer, and 10% methyl salicylate, which provides improved adhesion, cohesion, and drug release properties, along with a storage elastic modulus of 30000-75000 Pa, ensuring continuous application and reduced irritation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If methyl salicylate is highly formulated in the adhesive layer, then medicinal properties are improved, but adhesion stability deteriorates due to volatilization and plasticizer effects
Solution Approach 1:
The patent controls the content of methyl salicylate within 10-50% by mass and adjusts the storage elastic modulus to 10³-10⁵ Pa at 10 rad/s and 37°C. This parameter optimization balances the medicinal effect with adhesion stability, preventing both insufficient drug delivery and adhesive failure due to volatilization or plasticizer effects.
Solution Approach 2:
The adhesive layer is formulated as a composite system containing methyl salicylate, adhesive resin, and plasticizer in specific proportions. This composite structure allows the methyl salicylate to exert its medicinal effect while the adhesive resin and plasticizer work together to maintain stable adhesion properties despite the presence of the volatile active ingredient.
2Adaptability or versatility
If the adhesive patch is applied to joints with twisting motions, then treatment coverage is improved, but adhesion deteriorates causing the patch to come off
Solution Approach 1:
The patent designs the adhesive layer with viscoelastic properties, specifically controlling the storage elastic modulus to 10³-10⁵ Pa at 10 rad/s and 37°C. This dynamic modulus allows the adhesive to deform and follow the skin's twisting motions at joint areas while maintaining sufficient adhesive force to prevent the patch from coming off.
Solution Approach 2:
The storage elastic modulus is optimized as a frequency-dependent parameter. At the physiological frequency of joint motion (10 rad/s), the modulus is controlled to provide both flexibility for movement adaptation and sufficient strength for adhesion, resolving the contradiction between coverage and reliability.
3Ease of operation
If the adhesive layer is peeled off from the skin, then application is completed, but pain is caused to the user
Solution Approach 1:
The patent incorporates plasticizers in the adhesive layer that provide gradual detachment characteristics. This beforehand cushioning effect reduces the sudden stress on skin-adhesive bonds during peeling, thereby minimizing pain. The plasticizer allows the adhesive to release gradually rather than all at once, cushioning the harmful peeling effect.
4Ease of operation
If the adhesive layer has high flexibility, then application properties are improved, but cohesion deteriorates leading to poor shape retention
Solution Approach 1:
The storage elastic modulus is precisely controlled within the range of 10³-10⁵ Pa at 10 rad/s and 37°C. This parameter optimization achieves the right balance: the adhesive layer is flexible enough to conform to skin contours and joint movements (good application properties) while maintaining sufficient internal strength and cohesion for shape retention and preventing disintegration.
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 adhesive patch maintains excellent application properties, improves drug release and percutaneous absorbability, and enhances the continuity of stimulation while minimizing the risk of coming off or causing pain upon peeling, even with joint movements.
Implementation Method 1
the adhesive layer contains 25 to 50% by mass of a liquid organic ingredient and 25 to 50% by mass of a thermoplastic elastomer... good cohesion and shape retention of the adhesive layer can be maintained
Implementation Method 2
methyl salicylate itself acts as a plasticizer... since the adhesive layer contains 10% by mass or more of methyl salicylate
Implementation Method 3
the storage elastic modulus (G') of the adhesive layer is 30000 to 75000 Pa at 10 rad/s and 37°C
Data Source
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AI summary
An adhesive patch comprising a stretchable support and an adhesive layer laminated on at least one side of the support, wherein the stretchable support comprises a woven fabric knitted in stockinette stitch on both sides having two or more rows of crimped polyethylene terephthalate multifilament yarns, the adhesive layer contains 25 to 50% by mass of a liquid organic ingredient and 25 to 50% by mass of a thermoplastic elastomer based on the total mass of the layer and contains 10% by mass or more of methyl salicylate as the liquid organic ingredient based on the total mass of the layer, and the storage elastic modulus (G') of the adhesive layer is 30000 to 75000 Pa at 10 rad/s and 37°C.