Pressure Sensitive Adhesive Composition for Medical Devices
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Solution Overview
Problem
Pressure sensitive adhesives used in medical devices face challenges in maintaining skin friendliness, moisture absorption, and ease of removal without causing skin damage, as they often become too hard with hydrocolloid incorporation, leading to issues with adhesion and skin maceration.
Innovation Solution
A pressure sensitive adhesive composition comprising 4-15 w/w % SIS copolymer, 20-35 w/w % SI diblock copolymer, 4-15 w/w % tackifier, and 30-45 w/w % hydrocolloid with particle sizes below 40 μm, which balances tackiness, moisture absorption, and ease of removal by using A-B-A block copolymers, paraffin oil, and specific hydrocolloids like sodium carboxymethyl cellulose.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrocolloid particles are incorporated into adhesives to maintain moisture absorption, then the adhesive can absorb moisture, but the hardness of the adhesive increases making it less skin-friendly
Solution Approach 1:
The patent applies parameter changes by controlling the particle size of hydrocolloid to be below 40 μm and optimizing the compositional ratios of different polymers (SIS 4-15%, SI 20-35%, tackifier 4-15%). This maintains moisture absorption capability while reducing particle-induced hardness and improving skin compatibility.
Solution Approach 2:
The patent creates a composite adhesive system combining multiple components: SIS triblock copolymer, SI diblock copolymer, tackifier, paraffin oil, and hydrocolloid particles. This composite approach balances moisture absorption, flexibility, and skin friendliness by distributing functions across different material components.
2Reliability
If hydrocolloid particles are added to increase moisture absorption, then the adhesive retains moisture, but the processing difficulty increases
Solution Approach 1:
By specifying hydrocolloid particle size below 40 μm and optimizing the viscosity and composition ratios of the adhesive matrix, the patent reduces processing difficulties while maintaining moisture absorption. The controlled particle size prevents aggregation and improves manufacturability.
3Object-affected harmful factors
If the adhesive is made softer to be skin-friendly, then the adhesive follows skin movements, but the adhesion strength decreases causing device to fall off
Solution Approach 1:
The patent uses a composite formulation where SIS and SI block copolymers provide flexibility and skin compliance, while tackifiers (4-15% w/w) and paraffin oil (6-18% w/w) ensure adequate adhesion strength. The hydrocolloid particles (30-45% w/w) maintain moisture absorption without compromising overall adhesive performance.
Solution Approach 2:
By optimizing the molecular weight, composition ratios, and particle size parameters of the adhesive components, the patent achieves a balance where the adhesive remains soft and skin-friendly while maintaining sufficient adhesion strength to prevent device detachment during normal use.
4Strength
If the adhesive tackiness is increased to improve initial adhesion, then the adhesive attaches better, but the removal causes skin damage
Solution Approach 1:
The patent carefully controls the tackifier content (4-15% w/w) and the composition of the polymer matrix to achieve optimal initial adhesion. The balanced formulation ensures sufficient tack for secure attachment while maintaining skin compatibility for pain-free removal, avoiding excessive bonding strength that would cause skin damage.
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 composition provides a thin, flexible, and breathable layer that maintains moisture absorption while allowing for pain-free removal, suitable for various medical devices, including wound dressings and ostomy appliances, without causing skin damage.
Implementation Method 1
Hydrocolloid adhesives containing hydrophilic particles or absorbents, which absorb moisture into the adhesive bulk
Implementation Method 2
transmit moisture when conditions are saturated
Data Source
AI summary
A pressure sensitive adhesive composition includes 4-15 w/w % styrene-isoprene-styrene copolymer, 20-35 w/w % styrene-isoprene diblock copolymer, 4-15 w/w % tackifier, 6-18 w/w % paraffin oil, and 30-45 w/w % hydrocolloid. The size of the hydrocolloid is below 40 μm.