Composite TPE-PP Valve for Cap-less Marker Ink Sealing

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Solution Overview

Problem

Cap-less writing utensils with ultra-fine tips face issues of ink vapor permeation and dry-out due to poor vapor barrier properties and structural integrity of all-TPE valves, leading to 'hard starting' and complete dry-out, especially when compared to those with large fiber-type tips.

Innovation Solution

A valve design combining a thermoplastic elastomer (TPE) with a hard thermoplastic material like polypropylene (PP) for improved vapor barrier properties and structural stability, featuring a two-step injection molding process to create a valve with a fluorocarbon monofilament string mechanism that efficiently seals and opens to prevent ink evaporation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an all-TPE valve is used in cap-less markers with large fibrous nibs, then the valve provides adequate sealing and structural integrity, but the valve exhibits poor vapor barrier properties allowing solvent vapor permeation that dries out the nib

Engineering Contradiction:

Improvesealing performanceVSAvoidsolvent vapor permeation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The valve is constructed from a composite of TPE and PP materials, combining the sealing properties of TPE with the vapor barrier properties of PP. The TPE portion provides elasticity and sealing contact, while the PP portion provides the vapor barrier to prevent solvent permeation.

Inventive Principle:

Principle #40Composite materials

2Reliability

If an all-TPE valve is used in cap-less markers, then the valve provides initial sealing capability, but the valve deforms over time due to material creep under spring and string loading

Engineering Contradiction:

Improveinitial sealing capabilityVSAvoidstructural stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The combination of TPE and PP creates a composite structure where PP provides dimensional stability and resistance to creep under load, while TPE maintains sealing contact. The PP portion does not deform under the spring and string loading, maintaining the valve's structural integrity over time.

Inventive Principle:

Principle #40Composite materials

3Manufacturing precision

If an ultra-fine tip marker with very small capillary channels is used, then the marker achieves fine writing line, but the marker is vulnerable to hard starting and complete dry-out due to minimal ink volume

Engineering Contradiction:

Improvewriting line finenessVSAvoidfunctional reliability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The composite valve structure with superior vapor barrier properties prevents solvent permeation, protecting the minimal ink volume in ultra-fine tip markers. This maintains the marker's functionality by preventing dry-out while preserving the fine writing capability.

Inventive Principle:

Principle #40Composite materials

4Ease of operation

If a cap-less design with retractable nib is used, then the marker eliminates the need for a separate cap, but the marker becomes susceptible to ink evaporation if the valve sealing is insufficient

Engineering Contradiction:

Improvecap-less convenienceVSAvoidink evaporation

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The composite TPE-PP valve provides both the sealing action needed for cap-less operation and the vapor barrier properties to prevent ink evaporation. This enables cap-less convenience without sacrificing protection against solvent loss.

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 solution effectively prevents ink evaporation and maintains a tight seal, ensuring the ultra-fine tip marker remains functional by minimizing solvent vapor permeability and structural deformation, thus avoiding dry-out and 'hard starting' issues.

Implementation Method 1

Methodology Applied

Scientific EffectTwo-step injection molding:

Implementation Method 2

improved vapor barrier properties

Methodology Applied

Scientific EffectVapor barrier:

Implementation Method 3

prevents ink evaporation by minimizing solvent vapor permeability

Methodology Applied

Scientific EffectPermeation: Permeation

Data Source

PatentUS8246265B2Valve made from two materials and writing utensil with retractable tip incorporating same

Publication Date: 2012.08.21 SANFORD LP

AI summary

A valve includes a first valve portion made from a first material, the first valve portion including a body, a door, and an inner hinge pivotably connecting the body to the door, the body including a first opening at a first end and a second opening at a second end opposite the first end, and a circumferential recess disposed in the second end, wherein the inner hinge pivotably connects the door to the body at the first end and a second valve portion made from a second material, the second valve portion including an inner seal disposed in the circumferential recess, the inner seal including a circumferential ridge extending inwardly, the second valve portion further including a door seal disposed on the first end of the body.