Adhesive Skin Patch Material with Thin Polyurethane Film

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Solution Overview

Problem

Adhesive skin patch materials face challenges in achieving a balance between good skin contact and reduced irritation, especially when peeling, due to skin irregularities and moisture issues, and often cause sweaty and itchy sensations.

Innovation Solution

A polyurethane elastomer film with a thickness of 1-9 µm and a pressure-sensitive adhesive layer containing an acrylic-based copolymer and a liquid or pasty ingredient at room temperature, ensuring flexibility and moisture permeability, is used, along with a release liner for the adhesive layer, to address these issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the adhesive skin patch material is strongly bonded to the skin surface, then good stickability is achieved, but skin irritation occurs at the time of peeling

Engineering Contradiction:
ImprovestickabilityVSAvoidskin irritation
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent changes the physical and chemical parameters of the pressure-sensitive adhesive by incorporating specific ingredients in liquid or pasty state at room temperature (20-100 parts by mass per 100 parts of acrylic-based copolymer). This modifies the adhesive's bonding strength and peeling characteristics, achieving both good stickability and reduced skin irritation during removal.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite pressure-sensitive adhesive system by combining acrylic-based copolymer with additional liquid or pasty ingredients. This composite formulation provides balanced properties: sufficient adhesion for good stickability while maintaining skin-friendliness to reduce irritation during peeling.

Inventive Principle:
Principle #40Composite materials

2Object-affected harmful factors

If the pressure-sensitive adhesive layer is made thinner to reduce irritation, then peeling comfort improves, but stickability decreases

Engineering Contradiction:
Improveskin irritationVSAvoidstickability
Core Design Contradiction:
Object-affected harmful factorsVSStrength

Solution Approach 1:

The patent maintains adhesive layer thickness within 20-35 μm and compensates for the reduced thickness by changing the chemical composition and adding liquid/pasty ingredients. This ensures sufficient bonding strength is achieved despite the thin profile, while the thin design itself contributes to reduced skin irritation during peeling.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If the base film thickness is reduced to improve flexibility and moisture permeability, then skin comfort improves, but mechanical strength decreases

Engineering Contradiction:
Improveflexibility and moisture permeabilityVSAvoidmechanical strength
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The patent optimizes the base film thickness to 1-9 μm, balancing flexibility and moisture permeability against mechanical strength. This thin film design allows the adhesive patch to conform to skin contours and permit moisture transmission while maintaining sufficient structural integrity through the selected thickness range.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs a thin polyurethane elastomer film as the base film, which inherently provides flexibility and moisture permeability. The thin film structure allows close conformity to skin surface while the elastomer material maintains adequate mechanical strength for handling and application.

Inventive Principle:
Principle #30Flexible shells and thin films

4Strength

If the adhesive layer is made thicker to improve stickability, then bonding strength increases, but sweaty and itchy sensations increase

Engineering Contradiction:
ImprovestickabilityVSAvoidsweaty and itchy sensations
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent controls the pressure-sensitive adhesive layer thickness to 20-35 μm and incorporates liquid or pasty ingredients to optimize the adhesive's performance. This composition and thickness control ensures adequate stickability while preventing excessive adhesive contact that would cause sweaty and itchy sensations on the skin.

Inventive Principle:
Principle #35Parameter changes

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 solution provides excellent stickability, reduces sweaty and itchy sensations, and minimizes skin irritation during peeling, while maintaining a comfortable fit and preventing adhesive residue.

Implementation Method 1

a pressure-sensitive adhesive layer provided on one side of the polyurethane elastomer film

Methodology Applied
Scientific EffectAdhesion: Adhesive

Implementation Method 2

high moisture permeability is required of adhesive skin patch materials

Methodology Applied
Scientific EffectPermeation: Permeation

Data Source

PatentEP3281996B1Adhesive skin patch material and roll body of adhesive skin patch material
Publication Date: 2021.06.16 NITTO DENKO CORP
  • EP3281996B1 patent drawingFigure 1

AI summary

The present invention relates to an adhesive skin patch material, which comprises a polyurethane elastomer film, a pressure-sensitive adhesive layer provided on one side of the polyurethane elastomer film, and a release liner releasably laminated so as to cover the sticky surface of the pressure-sensitive adhesive layer. The polyurethane elastomer film has a thickness of 1 µm to 9 µm, and the pressure-sensitive adhesive layer contains an acrylic-based copolymer and an ingredient in a liquid or pasty state at room temperature.