Hot-Melt PSA Composition Suppressing Rapid Gelling

Solution Overview

Problem

The formation of PSA layers using solvent-free hot-melt PSA compositions is hindered by rapid gelling when heated, leading to non-uniform thickness and poor appearance in the resulting PSA sheets.

Innovation Solution

A solvent-free hot-melt PSA composition is developed, comprising a base polymer, an isocyanate crosslinking agent, and a tackifier derived from specific reaction products of compounds X and Y, which suppresses rapid gelling during heating, ensuring uniform thickness and improved adhesive performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a solvent-free hot-melt PSA composition containing a crosslinking agent is heated to achieve adequate fluidity for film formation, then the composition can be processed into a PSA layer, but rapid gelling occurs and generates gelled substances that degrade uniformity and appearance

Engineering Contradiction:

Improvefluidity for film formationVSAvoiduniformity of thickness

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The invention changes the chemical parameter of the composition by introducing a specific tackifier (reaction product of compound X and compound Y) that modifies the gelling behavior during heating, allowing the composition to maintain adequate fluidity without rapid gelling

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The tackifier acts as an intermediary substance between the base polymer and crosslinking agent, controlling the gelling process during heating to prevent premature gel formation while maintaining processability

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If a solvent-free hot-melt PSA composition containing a crosslinking agent is heated to achieve adequate fluidity for film formation, then the composition can be processed into a PSA layer, but rapid gelling occurs and generates gelled substances that degrade appearance

Engineering Contradiction:

Improvefluidity for film formationVSAvoidgelled substance generation

Core Design Contradiction:

Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The invention changes the chemical parameter of the composition by introducing a specific tackifier (reaction product of compound X and compound Y) that modifies the gelling behavior during heating, allowing the composition to maintain adequate fluidity without rapid gelling

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention converts the potentially harmful rapid gelling effect into a beneficial controlled gelling process by using the specific tackifier to regulate crosslinking, ensuring uniform gel formation that improves rather than degrades appearance

Inventive Principle:

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

3Reliability

If conventional PSA compositions are used to form PSA layers, then adhesive performance can be improved by adding crosslinking agents, but rapid gelling occurs during heating that degrades processability

Engineering Contradiction:

Improveadhesive performanceVSAvoidprocessability during film formation

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention changes the chemical parameter of the composition by introducing a specific tackifier (reaction product of compound X and compound Y) that modifies the gelling behavior during heating, allowing the composition to maintain adequate fluidity without rapid gelling

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite composition combining base polymer, crosslinking agent, and specific tackifier in defined ratios, where the synergistic interaction between components achieves both improved adhesive performance and maintained processability

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 composition effectively prevents rapid gelling during the melting process, resulting in PSA layers with enhanced uniformity, adhesive strength, and a favorable appearance, while reducing environmental impact.

Implementation Method 1

the progression of rapid gelling at the time of being melted by heating may be suppressed

Methodology Applied

Scientific EffectGelling suppression:

Implementation Method 2

a hot-melt PSA composition which is solvent-free and includes a base polymer, an isocyanate crosslinking agent, and a tackifier T

Methodology Applied

Scientific EffectMixing:

Implementation Method 3

the hot-melt PSA composition is formed as a film in a state of being melted by heating

Methodology Applied

Scientific EffectMelting: Melting

Data Source

PatentUS12098311B2Hot-melt pressure-sensitive adhesive composition and hot-melt pressure-sensitive adhesive sheet

Publication Date: 2024.09.24 NITTO DENKO CORP

AI summary

Provided is a hot-melt pressure-sensitive adhesive composition which enables to form a pressure-sensitive adhesive layer without allowing the progression of rapid gelation at the time of heating and melting. The pressure-sensitive adhesive composition provided by the present invention is a solvent-free hot-melt pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition includes a base polymer, an isocyanate crosslinking agent, and a tackifier T which is a reaction product of a compound X and a compound Y. A content of the tackifier T with respect to 100 parts by weight of the base polymer is 20 parts by weight or more and 40 parts by weight or less.