Web Charge Control via Liquid Interface

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Solution Overview

Problem

Existing methods for controlling static electricity on webs conveyed by rollers are inadequate, leading to peeling discharge, uneven coating, and dust attraction, as they either require space for static eliminators, have insufficient capacity, or result in charge imbalances and dust absorption.

Innovation Solution

A method and device that supply a liquid to the interface between the web and the conveying roller to control the amount of charge generated by frictional electrification, using a liquid that generates a frictional charge opposite in polarity to neutralize the surface charge, thereby reducing or preventing charging on the web.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a static eliminator is used to neutralize charge on the web, then static elimination capability is improved, but device complexity and space requirements increase

Engineering Contradiction:

Improvestatic elimination capabilityVSAvoidspace requirement

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the charge neutralization function from a separate static eliminator device and integrates it into the conveying roller itself. The conveying roller is designed with conductive portions that can be grounded to neutralize charges directly at the contact point with the web, eliminating the need for a separate static eliminator device and reducing space requirements.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the conveying function and charge neutralization function into a single integrated conveying roller structure. The roller simultaneously performs web conveyance and charge neutralization through its conductive portions, simplifying the overall system configuration and reducing device complexity.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If a static eliminator is used to generate ions, then charge neutralization is improved, but safety in explosion-prone environments deteriorates

Engineering Contradiction:

Improvecharge neutralizationVSAvoidexplosion risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the electrical discharge mechanism of traditional static eliminators with a mechanical/physical grounding mechanism. The conveying roller uses direct electrical contact and grounding through conductive portions to neutralize charges, avoiding the generation of ions through discharge that could pose explosion risks.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If conveying speed is increased to improve productivity, then production efficiency is improved, but static elimination capability deteriorates

Engineering Contradiction:

Improveconveying speedVSAvoidstatic elimination capability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent implements charge neutralization at the very point where the web contacts the conveying roller, before the web proceeds to subsequent processing steps. This preliminary neutralization action ensures that charges are eliminated early in the conveying process, maintaining effectiveness even at high conveying speeds.

Inventive Principle:

Principle #10Preliminary action

4Strength

If conveying rollers are made conductive for mechanical strength, then structural integrity is improved, but ion absorption increases reducing static elimination capability

Engineering Contradiction:

Improvestructural integrityVSAvoidstatic elimination capability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent applies conductive material only to specific local portions of the conveying roller that contact the web, rather than making the entire roller conductive. This localized conductivity provides the necessary charge neutralization function at the contact interface while maintaining the overall structural integrity of the roller body.

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

This approach effectively controls the surface charge of the web, preventing peeling discharge and dust attraction, while ensuring precise control over the charge amount without the need for pre-imparting charges or static eliminators, even in environments with space constraints or explosion protection requirements.

Implementation Method 1

a liquid for charge control is supplied to an interface between the web and a conveying roller that conveys the web... control an amount of charge generated on a surface of the web by frictional electrification between the conveying roller and the web

Methodology Applied

Scientific EffectFrictional electrification: Triboelectric Effect

Data Source

PatentEP3706515B1Web manufacturing method, charge control method, and charge control device

Publication Date: 2024.01.03 TORAY INDUSTRIES INC

Figure 1~2

AI summary

The purpose of the present invention is to manufacture a charge amount-controlled web without providing the web, such as an elongated polymer film, with an advance charge. Provided is a web manufacturing method comprising a transfer step of transferring a web, wherein a liquid is supplied to the interface of a transfer roll transferring the web and the web, and a charge amount on a surface of the web due to frictional charging between the transfer roll and the web is controlled. The liquid includes, for example, a liquid that produces, between the transfer roll and the web, a frictional charge of the opposite polarity from the charge polarity produced on the surface of the web due to frictional charge between the transfer roll and the web.