Low-Sulfur PSA Sheet for Metal Corrosion Prevention

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Solution Overview

Problem

Water-dispersed acrylic pressure-sensitive adhesive (PSA) sheets can cause non-contact metal corrosion due to the release of sulfur-containing gases, leading to contact defects and quality issues in electronic devices and other applications.

Innovation Solution

A PSA sheet with a water-dispersed acrylic polymer synthesized using a sulfur-containing chain transfer agent, such as tertiary mercaptans or aromatic mercaptans, is developed to minimize sulfur-containing gas emission, preventing metal corrosion while maintaining effective adhesive properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a water-dispersed acrylic PSA composition is used instead of organic solvent-based composition, then environmental health and safety are improved, but metal corrosion occurs due to sulfur-containing gas emission

Engineering Contradiction:
Improveenvironmental health safetyVSAvoidmetal corrosion
Core Design Contradiction:
Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The invention changes the chemical structure parameters of the chain transfer agent from conventional sulfur-containing agents to specific tertiary mercaptans or aromatic mercaptans with restricted sulfur content (0.01-5 mass%). This parameter change reduces sulfur-containing gas emission while maintaining the water-dispersed acrylic PSA composition's environmental benefits and adhesive performance.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention converts the potentially harmful sulfur-containing chain transfer agent into a beneficial component by selecting specific types (tertiary mercaptans or aromatic mercaptans) that minimize sulfur-containing gas emission. The sulfur component, which could cause corrosion, is transformed into a controlled additive that maintains polymerization efficiency without generating harmful emissions.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

2Strength

If a sulfur-containing chain transfer agent is used in acrylic polymer synthesis, then adhesive properties are improved, but sulfur-containing gas is emitted causing metal corrosion

Engineering Contradiction:
Improveadhesive strengthVSAvoidsulfur-containing gas emission
Core Design Contradiction:
StrengthVSObject-generated harmful factors

Solution Approach 1:

The invention changes the structural parameters of the chain transfer agent to tertiary mercaptans or aromatic mercaptans with specific sulfur content ranges (0.01-5 mass%). This structural modification maintains the chain transfer agent's ability to control molecular weight and enhance adhesive strength while significantly reducing sulfur-containing gas emission that causes metal corrosion.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite PSA composition that combines water-dispersed acrylic polymer with specifically selected sulfur-containing chain transfer agents (tertiary mercaptans or aromatic mercaptans). This composite approach integrates the adhesive benefits of sulfur-containing agents while mitigating their harmful emission effects through careful material selection and composition control.

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 PSA sheet achieves low sulfur-containing gas emission, effectively preventing metal corrosion and ensuring strong adhesive properties, making it suitable for use in electronic devices and other applications where metal corrosion is a concern.

Implementation Method 1

a water-dispersed acrylic polymer synthesized in the presence of a chain transfer agent containing sulfur as a constituent atom (sulfur-containing chain transfer agent)

Methodology Applied
Scientific EffectPolymerization: Photopolymerisation

Implementation Method 2

The PSA sheet achieves low sulfur-containing gas emission, effectively preventing metal corrosion

Methodology Applied
Scientific EffectCorrosion prevention:

Data Source

PatentEP2206758B1Pressure-sensitive adhesive sheet with low emission of sulfur-containing volatile components
Publication Date: 2012.09.26 NITTO DENKO CORP
  • EP2206758B1 patent drawingFigure 1~3
  • EP2206758B1 patent drawingFigure 4~6

AI summary

A pressure-sensitive adhesive (PSA) sheet with low sulfur gas emission is provided. Metal corrosion due to outgassing components of the adhesive sheet is thereby prevented. The sheet comprises a PSA layer formed from a water-dispersed PSA composition. The PSA composition contains a water-dispersed acrylic polymer synthesized using a sulfur-containing chain transfer agent. Moreover, in a gas generation test whereby the PSA sheet is heated at 85°C for one hour, the emission of sulfur-containing gas is 0.043 μg or less per 1 cm2 surface area of the sheet, when converted to SO42-.