Boron Nitride Colored Lead Composition for Erasability and Lightfastness
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Solution Overview
Problem
Existing erasable colored pencils face challenges with softness, erasability, and lightfastness, particularly in non-sintered leads, and lack the ability to create both erasable and permanent applications.
Innovation Solution
A non-sintered colored lead or chalk composition using boron nitride as a filler, pigments as colorants, and specific waxes and binders, combined in a lamellar structure, allowing for easy removal and improved lightfastness, with the option to make writings permanent using solubilizing solutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If low melting point waxes are used in polymeric leads, then softness is improved, but penetration into paper fibers increases making removal difficult
Solution Approach 1:
The patent changes the melting point parameter of the wax from low to high (above 60°C), which fundamentally alters the wax's behavior during application. This parameter change prevents the wax from becoming too soft and penetrating deeply into paper fibers, while still providing adequate softness for smooth writing. The high melting point wax maintains its structural integrity during erasing, enabling easy removal without damaging the paper.
Solution Approach 2:
The patent creates a composite material system combining polymer particles with high melting point wax and pigment. This composite structure allows the wax to serve multiple functions: providing softness for smooth application, maintaining structural integrity to prevent excessive penetration, and enabling easy erasing. The composite approach resolves the contradiction by integrating materials with complementary properties.
2Ease of operation
If sintered leads with dyes are used, then softness is improved, but lightfastness deteriorates
Solution Approach 1:
The patent changes the chemical composition parameter by replacing dyes with pigments in the lead formulation. This substitution fundamentally alters the optical and chemical stability properties. Pigments provide superior lightfastness compared to dyes, while the high melting point wax maintains the softness needed for comfortable writing. This parameter change in material composition directly addresses the lightfastness issue.
3Strength
If sintering process is used, then structural integrity is improved, but production time increases
Solution Approach 1:
The patent extracts and removes the sintering step from the production process entirely. Instead of using a sintering process to achieve structural integrity, the invention uses a mechanical mixing and extrusion method where polymer particles are combined with wax and pigment, then formed into leads. This extraction of the sintering operation significantly reduces production time while still achieving the necessary structural integrity through the composite material formulation and extrusion forming process.
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 results in a soft, break-resistant, and highly erasable colored lead or chalk with excellent paper coverage and lightfastness, offering a wide range of colors and the ability to switch between erasable and permanent applications.
Implementation Method 1
The application of these materials to the paper reduces the penetration of substances such as pigments or dyes that are present in the formulation. It is known that hexagonal boron nitride, also known as 'white graphite', has a crystalline structure similar to graphite, therefore, the line written on the paper is applied in a layered manner, not penetrating the innermost layers of the paper, making it easier to be removed from the paper with an eraser.
Implementation Method 2
Normally, for this type of polymeric leads, waxes with a high melting point are used, since it is believed that using low melting wax may negatively affect the application. This effect may be due to shear forces generated during the application on the paper, which could be able to warm the wax and therefore allow significant penetration into the paper fibers.
Implementation Method 3
at least one pigment is present as colorant
Data Source
AI summary
The invention relates to an erasable, unburnt colored lead for writing, drawing and painting devices or erasable, unburnt colored chalk containing at least one filler material, graphite, at least one colorant, at least one binding agent and at least one wax, wherein boron nitride is present as a filler material and at least on pigment is present as colorant. The invention further relates to a writing, painting or drawing device comprising an erasable, unburnt colored lead and a method for manufacturing such a colored lead or colored chalk.