Polymeric Razor Blade Manufacturing via 2-Photon Polymerization

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Solution Overview

Problem

Current methods for manufacturing razor blades from polymeric materials are not cost-effective for mass production and struggle to achieve the required sharpness and tip radius for cutting hair, with existing processes like melt flow processing and high-resolution additive manufacturing facing issues such as material viscosity, flashing, shrinkage, and internal stresses.

Innovation Solution

A method using 2-photon polymerization to create razor blades by activating a precursor material with electromagnetic radiation, forming a focal point to shape the cutting edge, and curing the material to produce a polymeric cutting edge structure with a tip radius less than 1 micrometer, allowing for complex shapes and reduced internal stresses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If melt flow processing techniques are used to inject molten polymer into a mold cavity, then mass production can be achieved, but the polymer is too viscous to fully penetrate into sub-micro-meter dimensioned spaces required to create razor blade edges

Engineering Contradiction:
Improvemass production capabilityVSAvoidcutting edge tip radius
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent changes the physical and chemical parameters of the polymeric material by reducing molecular weight and adjusting composition to achieve optimal viscosity range (10-10,000 centiPoise) that enables both mass production and sub-micrometer precision in cutting edge formation

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces traditional mechanical grinding processes with a chemical/curing-based formation process where the cutting edge is created during polymerization in the mold cavity, eliminating the need for subsequent mechanical sharpening operations

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If injection pressure is increased to improve penetration into sub-micro-meter dimensioned spaces, then cutting edge sharpness improves, but the polymeric material penetrates between the mating surfaces of the mold tool causing flashing

Engineering Contradiction:
Improvecutting edge tip radiusVSAvoidflashing
Core Design Contradiction:
Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent optimizes the viscosity parameter of the polymeric material to a specific range (10-10,000 centiPoise) that allows adequate flow into sub-micrometer spaces at moderate injection pressures, preventing flashing while achieving the required cutting edge sharpness

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses controlled partial penetration of the polymer into the mold cavity with precise pressure control, allowing just enough flow to fill the cutting edge spaces without excessive pressure that would cause flashing between mold surfaces

Inventive Principle:
Principle #16Partial or excessive action

3Manufacturing precision

If the polymeric material is heated above the glass transition temperature to decrease viscosity, then penetration into sub-micro-meter spaces improves, but shrinkage and rounding of the edge occur during cooling

Engineering Contradiction:
Improvecutting edge tip radiusVSAvoidedge sharpness
Core Design Contradiction:
Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The patent selects polymeric materials with glass transition temperatures and viscosity characteristics that minimize thermal expansion and shrinkage effects during processing, maintaining cutting edge geometry through the heating and cooling cycles

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The cutting edge geometry is formed during the polymerization process itself before cooling occurs, so that the final cooling and shrinkage affect the bulk material uniformly without distorting the already-formed cutting edge shape

Inventive Principle:
Principle #10Preliminary action

4Adaptability or versatility

If conventional additive manufacturing techniques are used to fabricate polymeric structures, then complex shapes can be created, but the spatial resolution is limited to tens of micro-meters which is greater than the ultimate tip radius required

Engineering Contradiction:
Improvecomplex shape capabilityVSAvoidtip radius
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent replaces conventional layer-by-layer additive manufacturing with a mold cavity injection process where the cutting edge is formed by direct polymerization in the final geometry, achieving sub-micrometer precision without the resolution limits of voxel-based additive manufacturing

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses photopolymerization parameters (light wavelength, intensity, exposure time) to control the curing process at sub-micrometer scales, enabling precision far beyond the capabilities of conventional additive manufacturing techniques

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

Enables the efficient and cost-effective production of razor blades with sharp, precise cutting edges and complex shapes, overcoming the limitations of previous methods by achieving sub-micrometer resolution and reducing fabrication time and stress-related instability.

Implementation Method 1

activating portions of the precursor material in a focal point with electromagnetic radiation, wherein a wavelength of the radiation is about double a wavelength required to activate the precursor material

Methodology Applied
Scientific EffectPhotopolymerization: Photopolymerisation

Implementation Method 2

activating portions of the precursor material in a focal point with electromagnetic radiation

Methodology Applied
Scientific EffectFocusing: Focusing

Data Source

PatentEP3475053B1Cutting edge structures and method of manufacturing polymeric cutting edge structures
Publication Date: 2021.05.26 THE GILLETTE CO
  • EP3475053B1 patent drawingFigure 1
  • EP3475053B1 patent drawingFigure 2
  • EP3475053B1 patent drawingFigure 3~4

AI summary

A functional polymeric cutting edge structure (510) and methods for the manufacturing of cutting edge structures comprised of polymeric materials are provided. The cutting edge structures may be produced on a substrate (215) having a blade body or blade support type. The polymeric material is produced by curing a precursor material activated by electromagnetic radiation wherein a wavelength of said radiation is about double a wavelength required to activate the precursor material. A razor blade (72,82) for use in a razor cartridge (70) or a blade box (86) may be formed using the present invention.