Lubricating Strip Geometry for Razor Blade Comfort

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Solution Overview

Problem

Sharper, slimmer, and stronger blades in razor cartridges can cause discomfort, irritation, and nicks due to skin sensitivity, despite improving shaving efficiency.

Innovation Solution

Optimizing the geometry of the lubricating strip or cap, including strip exposure and angle, to interact synergistically with multiple blades, reducing blade load and improving comfort without sacrificing closeness, using materials like polyethylene oxide and polystyrene, and incorporating features like swelling and lubricious coatings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If blades are made sharper and slimmer to increase shaving efficiency, then productivity is improved, but object-affected harmful factors increase causing discomfort and irritation

Engineering Contradiction:
Improveshaving efficiencyVSAvoidskin irritation and nicks
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

A lubricating strip composed of a water-insoluble polymer matrix and water-soluble shaving aid is introduced as an intermediary between the sharp blade and the skin. The strip releases lubricant during shaving to reduce friction and irritation caused by the sharp blade, while maintaining the blade's cutting efficiency.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The lubricating strip's composition parameters are optimized by controlling the molecular weight of polyethylene oxide (a balance between low and high molecular weight) and the ratio of water-insoluble to water-soluble components. This enables the strip to maintain structural integrity while releasing adequate lubricant to mitigate blade-induced skin irritation.

Inventive Principle:
Principle #35Parameter changes

2Force

If blades are made stronger to reduce hair cutting force, then force required for shaving is reduced, but device complexity increases

Engineering Contradiction:
Improvehair cutting forceVSAvoidcartridge design complexity
Core Design Contradiction:
ForceVSDevice complexity

Solution Approach 1:

The lubricating strip uses a composite material system consisting of a water-insoluble polymer matrix ( providing structural strength) and water-soluble shaving aid (providing lubrication). This composite structure reduces the force required for hair cutting while maintaining blade strength, without significantly increasing device complexity.

Inventive Principle:
Principle #40Composite materials

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 optimized geometry and materials reduce blade force load by up to 30%, enhancing comfort and closeness during and after shaving, while minimizing irritation and nicks, even with sharper blades.

Implementation Method 1

a watersoluble shaving aid, typically polyethylene oxide, which leaches out of the strip during shaving to enhance shave comfort

Methodology Applied
Scientific EffectLeaching: Diffusion

Implementation Method 2

incorporating features like swelling and lubricious coatings

Methodology Applied
Scientific EffectSwelling: Absorption (physical)

Implementation Method 3

applying a thin lubricious polymer coating on the blade edge

Methodology Applied
Scientific EffectLubrication: Lubrication

Data Source

PatentEP2323817B1Shaving aid geometry for wet shave system
Publication Date: 2017.11.01 THE GILLETTE CO
  • EP2323817B1 patent drawingFigure 1
  • EP2323817B1 patent drawingFigure 2~2A
  • EP2323817B1 patent drawingFigure 3

AI summary

The invention discloses a novel geometry for a lubricating body, strip or cap (14), composed of shaving aids, taking into consideration their shape, materials and placement along with their interaction with multiple blades (12) for improved shaving attributes in a wet shaving system. A strip exposure (16) and a strip angle (22) are disclosed where generally a maximum height of the lubricating strip is greater than or equal to the maximum height of the blade plane (15) and thus, the skin contacting surface of the lubricating body is generally above the skin contacting surface of the blades.