Fiber-Bundled Pen Tip with Composite Multifilaments

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Solution Overview

Problem

Existing fiber-bundled parts for writing instruments, particularly those with small diameters and irregular cross-sections, face challenges in maintaining uniform density and strength due to thermal shrinkage and entanglement issues, leading to weakened fiber bundles and compromised ink or liquid supply performance.

Innovation Solution

A fiber-bundled part comprising multifilaments of long fibers with different melting points, including crimped fibers with a specific crimp ratio, which are thermally fused to create three-dimensional reticulate structures and solidify without using short fibers or binder resins, ensuring uniform density and strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If short fibers are used to thermally fuse low-melting-point fibers, then bonding stability is improved, but fiber density uniformity deteriorates due to loosening and gaps

Engineering Contradiction:

Improvebonding stabilityVSAvoidfiber density uniformity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent changes the fiber length parameter from short fibers to long fibers (specifically, long-staple fibers with length of 50mm or more), which prevents loosening and gap formation during thermal fusion while maintaining bonding stability. This parameter change resolves the contradiction by eliminating the root cause of density non-uniformity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite fibers consisting of low-melting-point fibers (for bonding) and high-melting-point fibers (for structural integrity), where the high-melting-point fibers prevent loosening during thermal fusion. This composite structure maintains both bonding stability and fiber density uniformity simultaneously.

Inventive Principle:

Principle #40Composite materials

2Volume of moving object

If the content of short fibers is reduced to form small diameter cores, then core size is reduced, but bundle strength deteriorates due to loosening and separation

Engineering Contradiction:

Improvecore diameterVSAvoidbundle strength

Core Design Contradiction:

Volume of moving objectVSStrength

Solution Approach 1:

The patent changes the fiber length parameter to long fibers, which maintain bundle integrity and strength even when the core diameter is reduced. The long fibers prevent loosening and separation, enabling the formation of small diameter cores with excellent strength.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite fibers where high-melting-point fibers provide structural strength and prevent bundle separation, while low-melting-point fibers provide bonding. This allows small diameter cores to maintain both strength and integrity.

Inventive Principle:

Principle #40Composite materials

3Ease of manufacture

If low-melting-point fibers are used for thermal fusion, then bonding is achieved, but dimensional stability deteriorates due to thermal shrinkage

Engineering Contradiction:

Improvebonding capabilityVSAvoiddimensional stability

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The patent uses composite fibers combining low-melting-point fibers (for bonding capability) and high-melting-point fibers (for dimensional stability). The high-melting-point fibers resist thermal shrinkage during fusion, maintaining dimensional stability while the low-melting-point fibers provide bonding.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies different fiber types in specific roles: low-melting-point fibers localized at bonding points provide bonding capability, while high-melting-point fibers distributed throughout provide dimensional stability. This local quality differentiation resolves the contradiction.

Inventive Principle:

Principle #3Local quality

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 fiber-bundled parts with excellent strength and durability, maintaining uniform yarn density along the longitudinal direction without impairing ink or liquid supply performance, even in small diameter cores, and allows for flexible and porous structures suitable for writing instruments and cosmetics.

Implementation Method 1

the fibers are bound via the low-melting-point portion when thermally fused

Methodology Applied

Scientific EffectThermal fusion: Melting

Implementation Method 2

when thermally fused in such a state as to form continuous pores between the fibers

Methodology Applied

Scientific EffectHeating: Heating

Data Source

PatentUS12187068B2Fiber-bundled part for writing instruments, and pen tip and writing instrument using the fiber-bundled part

Publication Date: 2025.01.07 MITSUBISHI PENCIL CO LTD

AI summary

This application is related to a fiber-bundled part for writing instruments having excellent strength and durability, as well as a pen tip and a writing instrument using the fiber-bundled part, which can be suitably used for pen tips, ink feed cores and relay cores of writing instruments such as marking pens and felt-tip pens. The fiber-bundled part for writing instruments of the present disclosure is used for the ink feed core leading to the pen tip or a writing pen core, and comprises a multifilament of long fibers having different melting points, and the multifilament at least contain crimped fibers.